Solid oxide fuel cell conduction

Abstract

Solid oxide fuel cell (SOFC) systems include high thermal conductivity materials such as copper to increase thermal energy transfer through heat conduction. The copper is protected from oxidation by electroplating with nickel and from thermal damage by providing an oxidation-resistant lining within the combustion chamber.

Description

[0001] 1. Copyright Notice

[0002] Portions of the disclosure of this patent document may contain material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever. The following notice applies to this document: 2020 Northern Powerhouse ( 2020 Upstate Power Inc). Technical Field 2.1 Technical Field

[0004] The exemplary illustrative techniques herein relate to solid oxide fuel cell (SOFC) systems, methods of use, and methods of making SOFC systems. Specifically, the exemplary illustrative techniques relate to improved systems and methods for thermal energy management within SOFC systems. Background Art

[0005] 2.2 Related Technologies

[0006] Conventional SOFC systems include a hot zone that contains or at least partially encloses system components that are maintained at a higher operating temperature (e.g., above 350°C or 500°C during operation, depending on the SOFC technology). The hot zone houses the SOFC energy generator or solid oxide fuel cell stack. A conventional SOFC fuel cell stack is formed by one or more fuel cells, each of which participates in an electrochemical reaction that produces an electric current. The fuel cells are electrically interconnected in series or in parallel as needed to provide the desired output voltage of the stack. Each fuel cell includes three main layers: an anode layer or fuel electrode, a cathode layer or air electrode, and an electrolyte layer that separates the anode layer from the cathode layer.

[0007] The anode layer is exposed to a gaseous or vaporized fuel containing at least hydrogen (H2) and / or carbon monoxide (CO). Simultaneously, the cathode layer is exposed to a cathode gas, such as air or any other gaseous or vaporized oxygen (O2) source. In the cathode layer, the oxygen (air) supplied to the cathode layer receives electrons and becomes oxygen ions (O -2 Oxygen ions are transferred from the cathode layer to the anode layer through the ceramic electrolyte layer. At the three-phase boundary, in the anode layer, hydrogen (H2) and / or carbon monoxide (CO) supplied to the anode layer by the fuel react with the oxide ions to produce water and carbon dioxide. Electrons emitted during this reaction generate electricity and heat. Other reaction byproducts in the fuel stream may include methane, ethane, or ethylene. The electrical energy generated by the electrochemical reaction is extracted to the DC power supply terminals to power an electrical load.

[0008] Common anode materials include cermets such as nickel and doped zirconia (Ni-YSZ), nickel and doped ceria (Ni-SDC and / or Ni-GDC), copper and doped ceria, etc. Perovskite anode materials such as La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-δ (LSCM) and other ABO3 structures are also available. Common cathode materials include lanthanum strontium cobalt oxide (LSC), lanthanum strontium cobalt iron oxide (LSCF) and lanthanum strontium manganate (LSM). The electrolyte layer is an ion-conducting ceramic, typically an oxygen ion conductor, such as yttria-doped zirconium oxide or gadolinium-doped cerium oxide. Alternatively, the electrolyte layer is a proton-conducting ceramic, such as barium cerate or barium zirconate. The electrolyte layer serves as a nearly sealed barrier to prevent fuel and air from mixing and burning.

[0009] Conventional SOFC systems use cross-flow heat exchangers or parallel-flow heat exchangers (commonly referred to as recuperators) to heat the cathode gas (air) entering the SOFC system. The airflow heat exchanger heats the cold air entering the hot zone by exchanging heat energy between the incoming cold air and the hot exhaust gas leaving the hot zone. Compared to heat energy transfer by thermal conduction, air-to-air cross-flow heat exchangers are inefficient. Conventional SOFC power generation systems rely primarily on the incoming cathode air flow to manage thermal energy distribution. However, the cathode air flow rate is typically selected to redistribute thermal energy rather than optimize the SOFC reaction. When the cathode air volume rate (e.g., liters / second) or mass flow rate (e.g., kg / s) is selected to optimize the SOFC reaction, the required volume or mass flow rate is significantly less than the volume or mass flow rate required to redistribute thermal energy, and in some cases, thermal energy distribution requires a cathode air flow rate that is 300% greater than the cathode air flow rate required for the SOFC reaction. The result of using a higher volumetric air flow rate in the SOFC system is a decrease in power generation efficiency due to the energy required to move the excess air flow. Furthermore, the thermal energy used to heat the excess air flow is not available to heat the SOFC stack and other surfaces, especially during startup.

[0010] In conventional SOFC systems, a recuperator or gas countercurrent heat exchanger is arranged to receive hot gases exhausted from the tail gas burner and to receive cool gases entering the SOFC system in countercurrent ducts separated by a common wall. Again, convection and radiation are the primary heat transfer mechanisms, as the hot gases from the burner heat the duct walls as they pass to the outlet port, and the duct walls heat the incoming air. In short, the heat exchange within both the tail gas burner and the recuperator is not efficient. As a result, conventional SOFC systems are notoriously difficult to control and often develop hot spots, for example, in the combustion housing, which can damage the housing walls or even burn through them when the combustion housing walls become too hot. Alternatively, when the temperature of the SOFC system is reduced, for example, by reducing the fuel input flow rate and increasing the input cathode air flow rate to cool the hot spots, the SOFC reaction changes, which often leads to undesirable operation, such as reduced power output, incomplete fuel processing (which causes carbon formation on the anode surface), and ultimately reduced power output and eventual failure.

[0011] To better address hot and cold spots, conventional SOFC systems typically include multiple thermocouples or thermistors positioned at various system points to monitor temperature and adjust operation to avoid hot spots and prevent cold spots. However, due to the high operating temperatures of SOFC systems (e.g., 350°C-1200°C near the tail gas combustion chamber), temperature sensing and monitoring systems are costly and prone to failure. In addition, the need to adjust fuel input as a measure to avoid damage to the SOFC system results in inefficient and variable power output. Therefore, there is a need in the art to avoid thermal gradients and eliminate hot spots to avoid damage to the SOFC system and to deliver a more consistent power output and improve power generation efficiency. In addition, there is a need to provide a more efficient and passive method for thermal energy management in a SOFC system that does not rely on changing fuel and air flow rates to manage thermal energy distribution, such as reducing the temperature of a hot spot.

[0012] Conventional SOFC systems use heat- and corrosion-resistant materials to withstand the effects of long-term operation in high-temperature, severely corrosive environments that continuously oxidize metal surfaces, sometimes to the point of failure. Specialized, high-temperature, corrosion-resistant nickel-chromium alloys, such as Inconel, Monel, and Hastelloy, are commonly used in SOFC systems. However, while these materials perform well in the high-temperature, corrosive environment of SOFC generators, they often have very low thermal conductivity compared to, for example, highly thermally conductive materials such as copper, aluminum, molybdenum, or their equivalents. For example, Inconel has a thermal conductivity ranging from 17 W / (m°K) to 35 W / (m°K) over a temperature range of 150°C to 875°C, compared to copper, which has a thermal conductivity of approximately 370 W / (m°K) at 500°C and approximately 332 W / (m°K) at 1027°C. Thus, copper has a thermal conductivity greater than 10 times that of Inconel.While copper offers increased thermal conductivity relative to high temperature non-corrosive metal alloys, copper is highly susceptible to decomposition by oxidation at high temperatures and has heretofore been avoided as a SOFC housing material. Summary of the Invention

[0013] 3 Technical Introduction

[0014] The present technology overcomes problems associated with conventional SOFC systems by providing various embodiments of an improved SOFC system including a configuration of a hot zone housing assembly (8042) formed from a U-shaped main housing wall assembly (8045) and a hot zone housing assembly (12042) including two L-shaped main housing wall assemblies (12045), as well as other hot zone housing assembly embodiments (14042, 15042) utilizing one or more U-shaped and L-shaped main housing wall assemblies. Each main housing wall assembly is formed to enclose an SOFC stack (8005), a cathode chamber (8055, 12055), and a combustion zone (8030) located above the fuel output (8025) of each individual fuel cell. Each main shell wall assembly includes a combustion zone wall (8060, 12060) and at least one opposing main shell side wall (8065, 8070, 12070), wherein the combustion zone wall (8060, 12060) is formed to define a combustion zone, and at least one opposing main shell side wall (8065, 8070, 12070) extends from an edge of the combustion zone wall (8060, 12060) to the cathode input end of each fuel cell, so that the main shell wall assembly encloses the SOFC stack along the input end (8020) at least along the entire longitudinal length (x) of the SOFC stack.

[0015] Each main housing wall (8060, 12060), (8065) ​​and (8070, 12070) includes a thermally conductive core (8200) that is protected from oxidation by an external layer applied to its exposed surface. The thermally conductive core (8200) comprises one or more materials having a thermal conductivity greater than 100 W / (m°K), preferably greater than 200 W / (m°K). The thermally conductive core is formed of copper or molybdenum, or aluminum copper, or a copper-nickel alloy, or a combination thereof. The thermally conductive core has a thickness in the range of 0.127 mm to 6.0 mm (0.005 inch to 0.24 inch).

[0016] To prevent oxidation of the thermally conductive core (8200), each of the core sections (8205, 8210, 8215, 12010, 12015, 12017) is protected by a protective layer applied to or attached to the exposed surface of the thermally conductive core. The protective layer may include a nickel plating applied to the surface of each core section by an electroplating process, the thickness of which is at least 0.0005 inches and extends to 0.002 inches. Alternatively or additionally, the protective layer comprises one or more metal sheets arranged to contact and mate with the exposed surface of each of the three core sections (8205), (8210, 12010) and (8215, 12015, 12017). The metal sheets are applied directly to the uncoated surface of the thermally conductive core or to the electroplated surface of the thermally conductive core. The inner protective metal sheet (8220) is manufactured as a U-shaped structure that is attached to the inner surface of each of the three core sections (8205), (8210), (8215), wherein the inner surface of the inner protective layer (8220) faces the SOFC stack. The outer protective layer (8250) includes two substantially identical outer sidewall sections (8255), (8260) and an outer top section (8265). The three outer protective layer sections, when joined together with the respective outer surfaces of the thermally conductive core, form a U-shaped sheet metal structure that is shaped to attach to the outer surface of the thermally conductive core (8200) and protect the outer surface of the thermally conductive core (8200) from exposure to the oxygen-rich cathode air flow. Preferably, the inner surface of the outer protective layer contacts and mates with the respective outer surface of the thermally conductive core facing away from the SOFC stack. A second embodiment of the inner protective layer (12220) and the outer protective layer (12250) is also described herein.

[0017] Each wall portion of the inner and outer protective layers is made of ferritic steel, such as Alloy 18 distributed by Rolled Metal Products, Inc. of Alsip, IL, US. Stainless steel. Alloy18 The stainless steel is an aluminum stabilized ferritic stainless steel designed for high temperature applications with improved scaling and corrosion resistance achieved by the addition of aluminum in the range of 1.5 weight percent to 2.5 weight percent. Stainless steel is preferred because at the operating temperatures and conditions of the SOFC system (8000), the added aluminum content advantageously forms an aluminum oxide surface layer that prevents oxidation of the exposed surfaces of the inner and outer protective layers. This aluminum oxide surface layer prevents oxidation and prevents chromium from being removed from the Alloy 18. Leaching into stainless steel.

[0018] Each hot zone housing assembly (8042, 12042, 14042, 15042) optionally includes end walls (8080, 8085) and a bottom wall (8075), which further enclose the cathode chamber (8055, 12055) or the cathode chamber is further enclosed by the intermediate housing (9000), which includes end walls (9020, 9025) and a bottom wall (9010). The end walls (8080, 8085) and the base wall (8075) may include a thermally conductive core provided with a protective layer, the protective layer provided to prevent oxidative damage to the core material. BRIEF DESCRIPTION OF THE DRAWINGS 4 Description of the accompanying drawings

[0020] The features of the present technology will be best understood from the detailed description of the technology and exemplary embodiments thereof, which are chosen for purposes of illustration and are shown in the accompanying drawings, in which:

[0021] Figure 1 Depicted is a schematic diagram of a first exemplary SOFC system in accordance with the present technology.

[0022] Figure 2 Depicted is a schematic diagram of an exemplary hot zone of a SOFC system in accordance with the present technology.

[0023] Figure 3 Depicted is a schematic diagram of an exemplary fuel flow path for a SOFC system in accordance with the present technology.

[0024] Figure 4 Depicted is a schematic diagram of an exemplary air flow path for a SOFC system in accordance with the present technology.

[0025] Figure 5A Depicted is a cross-sectional view taken through a first exemplary hot zone exterior wall of a SOFC system according to the present technique.

[0026] Figure 5B Depicted is a cross-sectional view taken through a second exemplary hot zone exterior wall of a SOFC system in accordance with the present technology.

[0027] Figure 5C Depicted is a cross-sectional view taken through an exemplary bottom tube support wall including a thermally conductive block of a SOFC system according to the present technology.

[0028] Figure 5D Depicted is a cross-sectional view taken through an exemplary combustion zone end wall including a thermally conductive block of a SOFC system according to the present technology.

[0029] Figure 5E Depicted is a cross-sectional view taken through an exemplary combustion zone bottom wall including a thermally conductive block of a SOFC system according to the present technology.

[0030] Figure 6 Depicted is a schematic top cross-sectional view of a SOFC system having a plurality of rod-shaped fuel cells arranged in two concentric circular patterns in accordance with the present technology.

[0031] Figure 7A A first improved fuel cell system according to the present technology is schematically depicted and includes a first U-shaped main housing wall assembly disposed above a single SOFC stack.

[0032] Figure 7B Schematically depicts a Figure 7A 1 , the dashed line with arrows shows the synthesis gas flow and the thermal conductive heat flow through the U-shaped main housing, and the solid line with arrows shows the cathode gas flow and the radiation emission from the high temperature area.

[0033] Figure 8A Depicted is an isometric transparent view of an intermediate housing for a hot zone assembly in accordance with the present technology.

[0034] Figure 8B Depicted is a cross-sectional view taken through a main housing wall assembly in accordance with the present technology.

[0035] Figure 9A Depicted is an isometric side view of an improved hot zone configuration in accordance with the present technology.

[0036] Figure 9B Depicted is a detailed isometric side view of a cathode flow channel for receiving a cathode into a hot zone housing assembly in accordance with the present technology.

[0037] Figure 9C Depicted is an exploded isometric view of a main housing assembly in accordance with the present technology.

[0038] Figure 10A Schematically depicts a SOFC stack test fixture used to measure fuel cell temperature at five points along the SOFC stack axis while operating a text-fixture fuel cell to produce a DC current output.

[0039] Figure 10B A comparison of fuel cell temperatures at five points along the SOFC stack axis when operating the test fixture without a thermally conductive core (shown in black) and when operating the test fixture with a thermally conductive core layer installed (shown in cross-hatching) is graphically depicted.

[0040] 11A graphically depicts temperature measurements at five locations along the SOFC stack axis during a 2.5 hour startup and shutdown cycle without a thermally conductive core of the present technology.

[0041] FIG. 11B graphically depicts temperature measurements of a thermally conductive core having the present technology at five locations along the SOFC stack axis during a 2.5 hour startup and shutdown cycle.

[0042] Figure 12 A fuel cell system including a T-shaped main housing wall assembly disposed above two SOFC stacks is schematically depicted in accordance with one aspect of the present technique.

[0043] Figure 13 Depicted is an isometric side view of a hot zone housing assembly including two halves of a T-shaped main housing wall, with each half enclosing a SOFC stack and other cathode chamber portions, according to one aspect of the present technology.

[0044] Figure 13A Depicted is an isometric side view of an assembled L-shaped main housing wall assembly according to one aspect of the present technology.

[0045] Figure 13B Depicted is an exploded isometric side view of one half of a T-shaped main housing wall assembly according to one aspect of the present technology.

[0046] Figure 14 A fuel cell system including an L-shaped main housing wall assembly disposed above an SOFC stack is schematically depicted in accordance with one aspect of the present technique.

[0047] Figure 15 A fuel cell system including two SOFC stacks, each enclosed by a U-shaped main housing wall assembly, is schematically depicted in accordance with one aspect of the present technique.

[0048] Figure 16A Depicted is a method for encapsulating Figure 12 、 Figure 14 and Figure 15 Isometric side view of the exterior housing of the hot zone assembly.

[0049] Figure 16B Depicted is a method for encapsulating Figure 12 、 Figure 14 and Figure 15 Exploded side isometric view of the outer and center shells of the hot zone assembly.

[0050] Figure 17 Depicted is a method for encapsulating Figure 12 、 Figure 14 and Figure 15 Exploded side isometric view of the center housing of the hot zone assembly.

[0051] 4.1 Definition

[0052] Unless otherwise specified, the following definitions apply throughout:

[0053]

[0054]

[0055] 4.2 List of reference numerals

[0056] Unless otherwise specifically stated, the following project numbers are used throughout the paper.

[0057]

[0058]

[0059]

[0060]

[0061]

[0062] Specific embodiments

[0063] 4.3 Detailed description of the embodiment

[0064] refer to Figure 1A schematic diagram of a first embodiment of the present technology depicts a solid oxide fuel cell (SOFC) system (100). The system (100) includes a hot zone (105) and a cold zone (110), the hot zone (105) including at least one SOFC fuel cell, and preferably a plurality of fuel cells, forming an SOFC stack maintained at a high operating temperature, and the cold zone (110) including fuel input and output modules, a DC power output module, and other control elements. A hot zone housing wall (115) is provided to enclose a hot zone cavity (120) therein. An insulation layer (130) surrounds the housing wall (115) to thermally insulate the hot zone (105). An air gap (125) is provided between the insulation layer (130) and the sidewalls of the hot zone housing wall (115), the air gap (125) providing a gas flow conduit for gas to flow through the outer surface of the hot zone housing wall.

[0065] According to an important aspect of the present technology, the hot zone housing wall (115) and associated thermal management elements described below are in thermal communication with each other to provide a conductive thermal path for transferring thermal energy to all areas of the hot zone through thermal conduction of the hot zone housing wall (115). More specifically, the hot zone housing wall (115) and any thermal management elements described below comprise a material having a high thermal conductivity, such as a thermal conductivity of 100 W / (m°K) to 300 W / (m°K) at temperatures ranging from 350°C to 1200°C, and preferably a thermal conductivity greater than 200 W / (m°K). Accordingly, the hot zone housing outer wall and other thermal management elements described below are made of one or more of copper, molybdenum, aluminum copper, copper nickel alloy, or a combination thereof. Specifically, the hot zone housing wall (115) and associated thermal management elements are configured to provide a conductive thermal path for rapidly transferring thermal energy from one area of ​​the hot zone to another. More specifically, the hot zone housing wall (115) and associated thermal management elements are configured to manage thermal energy within the hot zone by rapidly conducting thermal energy from high temperature areas of the hot zone to low temperature areas of the hot zone to ensure that the entire hot zone is maintained at a more uniform temperature than is typical of conventional SOFC systems.

[0066] An electrochemical energy generator or fuel cell stack (135) comprising one or more solid oxide fuel cells (SOFCs) or other types of fuel cells is enclosed within a hot zone (105) and supported relative to a housing wall (115) by one or more support elements, as described below. The fuel cell stack (135) comprises one or more fuel cells, each of which participates in an electrochemical reaction that produces an electric current. The fuel cells are electrically interconnected in series or parallel as needed to provide a desired output voltage for the stack (135). Each fuel cell comprises three main layers: an anode layer or fuel electrode (150), a cathode layer or air electrode (155), and an electrolyte layer (145) separating the anode layer from the cathode layer.

[0067] The anode layer (150) is exposed to a reactant, such as a gaseous or vaporized reformate containing at least hydrogen (H2) and / or carbon monoxide (CO). Simultaneously, the cathode layer (155) is exposed to air or a source of vaporized oxygen (O2) or any other oxidizing gas. In the cathode layer 155, the oxygen (air) supplied to the cathode layer accepts electrons and becomes oxygen ions (O -2 ). The cathode reaction is I / 2O2+2e - =O -2 , sometimes written as O Ⅱ .

[0068] Oxygen ions are transferred from the cathode layer to the anode layer (150) through the electrolyte layer (145). In the anode layer, hydrogen (H2) and / or carbon monoxide (CO) supplied to the anode layer via fuel react with the oxygen ions to produce water and carbon dioxide, and electrons emitted during the reaction generate electricity and heat. The electrical energy generated by the electrochemical reaction is extracted to the DC current output terminal (140) to power an electrical load.

[0069] Common anode materials include metal ceramics such as nickel and doped zirconia, nickel and doped ceria, copper and ceria, etc. Perovskite anode materials such as Sr2Mg 1-x MnxMoO 6-δ or La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-δ etc. are also available. Common cathode materials include lanthanum strontium cobalt oxide (LSC), lanthanum strontium cobalt iron oxide (LSCF) and lanthanum strontium manganate (LSM). The electrolyte layer is an ion-conducting ceramic, typically an oxygen ion conductor, such as yttria-doped zirconium oxide or gadolinium-doped cerium oxide. Alternatively, the electrolyte layer is a proton-conducting ceramic, such as barium cerate or barium zirconate. The electrolyte layer serves as a nearly airtight barrier to prevent fuel and air from mixing and burning.

[0070] Typically, each fuel cell is configured with one of the anode layer (150), cathode layer (155), or electrolyte layer (145) formed as a support or mechanical structural element, and the other two layers are coated onto the support element, such as by dipping, spraying, etc. Various support element structures can be used, including Figure 2 A non-limiting exemplary embodiment is shown in , wherein each fuel cell includes an anode support element configured as a hollow tube forming a cylindrical gas conduit, wherein an anode layer (150) forms an inner diameter of the cylindrical conduit, a ceramic electrolyte layer (145) is coated on the outer diameter of the structural anode layer (150), and a cathode layer (155) is coated on the outer diameter of the electrolyte layer (145).

[0071] A fuel containing at least hydrogen (H2) and / or carbon monoxide (CO) flows through the hollow ceramic tube in contact with the anode layer, and air flows over the outer surface of the hollow tube in contact with the cathode layer. Electric current is generated as described above.

[0072] Although Figure 2 The specific cell stack includes a plurality of tubular fuel cells, but other cell stacks formed from fuel cells having different known form factors may be used without departing from the present technology. These cell stacks may include a fuel cell stack (135) formed from a plurality of flat sheet-type fuel cells formed into a stack, each cell including a sheet-like support layer (with other layers coated on the support layer) and a separator disposed between adjacent flat support layers (with other layers coated on the support layer).

[0073] A feed fuel input line (160) delivers feed fuel (8050), which includes a gaseous or vaporized hydrocarbon fuel received from a feed fuel container stored in the cold zone (110) or from an external feed fuel source. A feed fuel delivery controller (197) in communication with an electronic controller (190) is disposed in the cold zone along the feed fuel input line (160) to adjust the feed fuel input volume or mass flow rate as needed to control the feed fuel input rate and to mix the feed fuel with air. The feed fuel input line (160) delivers the feed fuel-air mixture (2025) to a fuel reformer (165) for fuel processing. The feed fuel and air mixture (2025) flows to the fuel reformer (165), which decomposes the mixture (2025) to form a reformate, hereinafter referred to as fuel (2027). The fuel (2027) is a reactant suitable for chemically reacting with the anode surface of the SOFC stack. The fuel (2027) or reformate typically comprises a mixture of H2, CO, CO2, and H2O with trace amounts of CH4 and other hydrocarbons. Other reformate contents may include methane, ethane, or ethylene. In alternative embodiments, the feed fuel (8050) comprises primarily hydrogen (H2) with little or no additional components, and a reformer (165) is not required. Fuel received from a fuel reformer or directly from a feed fuel source passes over the surface of the anode layer (150) for electrochemical reaction therewith.

[0074] The cathode gas input line (170) delivers gaseous or vaporized oxygen (such as ambient air or another oxygen source) to the cold zone (110), for example, via an intake fan. An air delivery controller (198) in communication with an electronic controller (190) is optionally provided along the air input line (170) in the cold zone to adjust the air input volume or mass flow rate as needed. The air input line (170) delivers room temperature air to a recuperator (175), which heats the input air by exchanging heat energy between the hot gas leaving the hot zone and the incoming cooler air. The heated incoming air passes over the surface of the cathode layer (155) to chemically react with it.

[0075] Both the spent fuel and the oxygen-reduced air exit the fuel cell stack (135) and mix in a combustion zone or tail gas burner (180). The mixture of unreacted fuel and unreacted air delivered to the tail gas burner (180) spontaneously combusts therein, generating heat energy locally. The burner wall, described in detail below, comprises a material having a high thermal conductivity, such as 100 W / (m°K) to 300 W / (m°K), and preferably greater than 200 W / (m°K). In addition, the burner wall is in thermal communication with the hot zone housing wall (115), such that the heat energy generated by combustion within the burner (180) heats the burner wall to a high temperature that quickly begins to transfer heat energy to all areas of the hot zone by conducting heat energy transfer through the hot zone housing wall (115).

[0076] Combustion byproducts, including hot gases, exhausted from the tail gas burner (180) are conveyed to a recuperator (175). The recuperator comprises a cross-flow heat exchanger having counter-flow piping configured to transfer heat energy from the hot combustion byproducts to cooler incoming air, thereby heating the incoming air before it enters the SOFC fuel cell stack (135). After passing through the recuperator (175), the combustion byproducts are exhausted through an exhaust gas port (185).

[0077] A thermocouple or other temperature sensor (157) is attached to the surface of the housing wall (115) to sense its temperature and transmit the temperature information to the electronic controller (190). The controller (190) communicates with other electronic components, such as one or more electrically operable airflow valves, airflow rate detectors and / or modulators, components associated with a fuel delivery controller (197), an air delivery controller (198), and an electrical power output detector, as well as other components that may be required to control various operating parameters of the SOFC (100). The electronic controller (190) monitors the DC current output and the temperature measured at the thermocouple and further operates to vary the fuel supply input and air flow rate as a means of controlling the temperature.

[0078] In addition, an optional cold start module (195) can be provided to preheat the input fuel supply and / or air at startup. The cold start module (195) can be a fuel supply igniter that can be used to ignite a portion of the fuel supply to preheat the housing walls and SOFC, or the cold start module (195) can include an electric heater that can be used to preheat the input fuel, or the cold start module (195) can include both.

[0079] 4.4 Example Hot Zone Architecture

[0080] Now turn Figure 2 A first non-limiting exemplary embodiment of an improved SOFC system hot zone (2000) according to the present technology includes a SOFC fuel cell stack (2005) comprising a plurality of individual fuel cells enclosed within a hot zone cavity (2010). The hot zone cavity (2010) is surrounded by a housing wall (2015), wherein the housing wall is formed from one or more of copper, molybdenum, aluminum-copper, copper-nickel alloy, or a combination thereof. The housing wall is surrounded by an insulation layer (2012), which limits the flow of heat energy out of the hot zone. An air gap (2155) is provided between the hot zone housing wall (2015) and the insulation layer (2012). The air gap (2155) provides a fluid flow conduit that leads to a hot zone outlet port (2165) and is used to carry exhaust gas out of the hot zone.

[0081] The housing wall (2015) is configured to provide a heat conduction path, the heat conduction path comprising a material having a thermal conductivity of 100 W / (m°K) to 300 W / (m°K), and preferably greater than 200 W / (m°K). In addition, the heat conduction path is configured to act as a heat energy conduit, which is suitable for conducting heat energy from a high temperature area of ​​the hot zone to a low temperature area of ​​the hot zone to reduce the temperature difference between each area of ​​the hot zone.

[0082] 4.4.1 Reformer

[0083] The hot zone chamber (2010) of the present non-limiting exemplary embodiment is a can-shaped cylindrical volume bounded by a hot zone housing wall (2015) comprising side walls (2002), a top wall (2004), and a bottom wall (2006). The hot zone (2000) operates most efficiently at temperatures above 350°C or above 500°C, depending on the SOFC reaction being used, and can operate at temperatures ranging from 350°C to 1200°C. Thus, each element of the hot zone of the present technology is configured to operate reliably at the highest temperature expected for that element, for example, 350°C in some areas and up to 1200°C inside the fuel reformer, such as near the catalytic reaction or inside the combustion zone.

[0084] According to a preferred non-limiting exemplary embodiment of the present technology, a fuel reformer (2020) that uses an exothermic reaction to reform a feed fuel and air mixture (2025) is provided within or partially within the hot zone to reform the feed fuel to produce a fuel (2027) or reformate for delivery to each fuel cell of the fuel cell stack (2005). The reformer (2020) of this exemplary embodiment includes a catalytic partial oxidation (CPOX) reactor that partially burns the feed fuel and air mixture (2025) delivered thereto. The feed fuel reforming process produces a hydrogen-rich fuel (2027), such as a reformate. The CPOX reactor includes a catalytic medium (2040), such as a metal or oxide phase of rhodium (Rh) coated on its inner surface or other suitable catalyst (e.g., platinum, palladium, copper, nickel, ruthenium, and cerium). The feed fuel and air mixture (2025) passing through the CPOX reactor is catalyzed as it passes over the catalytic media (2040) coated surface, and the heat released by the reaction is radiated and thermally conducted to the hot zone housing wall (2015) and helps to heat the fuel cell stack.

[0085] The CPOX reformer (2020) includes a reformer housing wall (2030) surrounding a cylindrical catalytic chamber (2035). The cylindrical catalytic chamber (2035) supports a catalytic medium (2040) therein. In this exemplary embodiment, the catalytic medium (2040) is a square unit extruded monolith, the exposed surface of which is coated with a suitable catalyst. The monolith is positioned so that the incoming feed fuel and air mixture (2025) flows through the exposed surface of the square unit extruded monolith to undergo a catalytic reaction. Other suitable catalytic structures may include a plurality of parallel plates or concentric ring structures or porous metal or ceramic foam structures, such as sintered elements or extruded elements, the sintered elements or extruded elements being formed with exposed surfaces coated with catalysts. Alternatively, the catalytic structure may include a plurality of mesh screens having exposed surfaces coated with catalysts. The feed fuel and air mixture (2025) enters the reformer (2020) through the reformer input port (2045) and flows through the catalytic medium (2040) to undergo reforming by contact with the catalytic surface. Reformed fuel or reformate, hereinafter referred to as "fuel," flows out of the reformer through the reformer outlet port (2050) and into the fuel input manifold (2055).

[0086] In this non-limiting exemplary embodiment, the reformer housing wall (2030) comprises a cylindrical or square wall enclosing a catalytic cavity (2035) of cylindrical or square cross-section. A catalytic medium (2040) is supported within the catalytic cavity (2035), which is configured to force an incoming feed fuel and air mixture (2025) to flow through the catalytic structure over the catalytic surface. A thermal insulation element (2065) is provided around the outer surface of the catalytic cavity (2035). The thermal insulation element (2065) is provided to limit the entry or exit of thermal energy into or out of the catalytic cavity (2035): the reformer housing wall (2030) may comprise a high temperature steel alloy, such as Inconel, a high temperature copper alloy (e.g., Monel), or other suitable high temperature material.

[0087] 4.4.2 SOFC fuel cell stack

[0088] The SOFC fuel cell stack (2005) is supported within a can-shaped hot zone housing wall (2015). A plurality of rod-shaped fuel cells (2080) are longitudinally supported within a cathode chamber (2090). The cathode chamber (2090) is a cylindrical chamber defined by a hot zone housing sidewall (2002) and a pair of opposing disc-shaped top and bottom tube support walls (2070, 2075). Each tube support wall (2070, 2075) is attached to the sidewall (2002) by a suitable attachment method, such as by welding or brazing, by pinching and mechanical fastening, or by clamping force held in place without fasteners. Preferably, the fuel cell stack (2005) is assembled before installation into the hot zone housing wall (2015) and can be removed from the hot zone housing wall (2015) as a unit, for example, to repair or inspect the stack as needed. Thus, the top and bottom tube support walls (2070, 2075) can be captured in place between opposing end stops (not shown). The top tube support wall (2070) mechanically engages and fixedly supports the top or input end of each of the plurality of rod-shaped fuel cells (2080). The mechanical interface between the top support wall (2070) and each of the plurality of fuel cell input ends is a substantially airtight interface to prevent the supply fuel and air mixture (2025) in the fuel input manifold (2055) from entering the cathode chamber (2090). The top tube support wall (2070) is preferably formed of Inconel. In addition, each top end cap (2095) is also formed of Inconel, which is an effective material for avoiding creep in high temperature environments. The bottom tube support wall (2075) is mechanically engaged with and movably supports the bottom end or output end of each of the plurality of rod-shaped fuel cells (2080). In particular, the output end of each fuel cell (2080) is longitudinally movable relative to the bottom tube support wall (2075) to accommodate changes in the length of each fuel cell when the fuel cell is heated to an operating temperature of 350° C. to 1200° C. Palumbo disclosed an exemplary tube support system that can be used in the present technology in related U.S. patent application No. 13 / 927,418, entitled “SOLID OXIDE FUELCELL WITH FLEXIBLE RODS SUPPORT STRUCTURE,” filed on June 26, 2013.

[0089] Now see Figure 2 and Figure 5CThe bottom tube support wall (2075) includes a disc-shaped heat conductive block (2180), which includes one or more materials having a thermal conductivity greater than 100 W / (m°K) and preferably greater than 200 W / (m°K), such as one or more of copper, molybdenum, aluminum copper, copper nickel alloy or a combination thereof. The disc-shaped heat conductive block (2180) is made of the following Figure 5C The top protective surface layer (5045) and the bottom protective surface layer (5050) described herein are protected. In a non-limiting exemplary embodiment, each of the top protective surface layer (5045) and the bottom protective surface layer (5050) comprises a separate disc-shaped element in thermally conductive contact with the disc-shaped heat conductive block (2180). Specifically, the top surface layer (5045) facing the cathode chamber (2090) comprises a disc-shaped chromium-free high-temperature metal alloy such as monel copper-nickel alloy, and the bottom surface layer (5050) facing the combustion area (2135) or tail gas burner comprises a disc-shaped high-temperature, corrosion-resistant metal such as Hastelloy alloy.

[0090] Preferably, each of the top protective surface layer (5045) and the bottom protective surface layer (5050) is in thermally conductive contact with a heat conductive block (2180), which is also in thermally conductive contact with the cylindrical side wall (2002) of the hot zone housing. Thus, when the fuel-air mixture is burned in the tail gas burner or combustion zone (2135), the heat energy generated by the combustion is radiated to the wall enclosing the combustion zone (2135) and is thermally conductively conducted from the enclosing wall through the hot zone enclosing wall (2015) to the heat conductive block (2180) and other areas of the hot zone. In addition, the heat energy emitted from the heat conductive block (2180) is radiated into the cathode chamber (2090), where it heats the cathode gas or air flowing through the cathode chamber and heats the surfaces of the fuel cells enclosed in the cathode chamber.

[0091] Each rod-shaped fuel cell (2080) includes a tubular annular wall (2085), wherein the anode layer is a support layer. The tubular annular wall (2085) is open at both ends. The tubular annular wall (2085) forms a fuel conduit that extends through the cathode chamber (2090) to transport the fuel (2027) through the cathode chamber (2090). Other rod shapes, including square, triangle, pentagon, hexagon, etc., may be used without departing from the present technology. In addition, other support layers can be used to provide structural integrity. Each fuel cell includes two metal end caps (2095), (2100) or pipe manifold adapters, one of which is attached to each of the two opposite ends of the pipe annular wall (2085).

[0092] Each end cap (2095), (2100) or pipe manifold adapter includes a cup-shaped attachment end (2105) and a journal-shaped support end (2110). The attachment end (2105) includes a blind hole that is sized to receive the outer diameter of the annular wall (2085) therein. Each attachment end (2105) is fixedly attached to the rod end by a press fit or interference fit or by another fastening means (such as by brazing or adhesive bonding using a material suitable for the operating temperature of the hot zone (350°C-1200°C). The journal-shaped support end (2110) includes an annular wall that is formed with an outer diameter that is sized to engage with corresponding through holes through the top tube support wall (2070) on the input side and corresponding through holes through the bottom tube support wall (2075) on the output side. The journal-shaped support end (2110) further includes a through-hole extending therethrough, which serves as a battery input port (2115) at the top end of the rod-shaped fuel cell or as a battery output port (2120) at the bottom end of the rod-shaped fuel cell (2080). Preferably, the end caps (2095, 2100) or the pipe manifold adapter each comprise a high-temperature, low-chromium, corrosion-resistant metal alloy that is thermally compatible with the fuel cell. The cap may comprise a ceramic coating on a metal cap to prevent chromium contamination.

[0093] See also Figure 2 and Figure 3 The top end cap (2095) of each fuel cell (2080) can provide electrical communication with the outer diameter of the annular wall (2085) or the cathode layer, so that the outer diameter of the annular wall (2085) is electrically connected to one of the DC current output terminals (140) through an electrical lead (2125) passing through the end cap (2095). A second electrical lead (2130) is electrically connected to the inner diameter of the annular wall (2085) or the anode layer and to a different terminal of the DC current output terminal (140). In addition, an electrical insulator (not shown) is provided between each end cap (2095) and (2100) and the corresponding top tube support wall (2070) and bottom tube support wall (2075) to electrically isolate the hot zone housing wall (2015) from the current generated by the fuel cell stack (2005).

[0094] Each rod-shaped fuel cell formed by the annular wall (2085) includes an anode support layer, which is a structured anode material layer formed with an inner diameter and an outer diameter. The anode support layer can include a cermet, as previously described. The outer diameter of the anode support layer annular wall (2085) is at least partially coated with a ceramic electrolyte layer, such as yttria-stabilized zirconia or a cerium (Ce)-based or lanthanum gallate-based ceramic. The outer diameter of the ceramic electrolyte layer is at least partially coated with a cathode material layer, such as lanthanum strontium cobalt oxide (LSC), lanthanum strontium cobalt iron oxide (LSCF), lanthanum strontium manganate (LSM), etc.

[0095] In a second non-limiting exemplary embodiment of the system hot zone (2000), the mechanical structure of the hot zone housing wall and inner end wall is similar to Figure 2 As shown in and described above; the anode layer and the cathode layer are on opposite sides of the ceramic electrolyte layer. Specifically, in the second embodiment, the inner diameter (opposite to the outer diameter) of the anode support layer annular wall (2085) is at least partially coated with a ceramic electrolyte layer, such as yttria-stabilized zirconia or a cerium (Ce)-based or lanthanum gallate-based ceramic, and the inner diameter of the ceramic electrolyte layer is at least partially coated with a cathode material layer, such as lanthanum strontium cobalt oxide (LSC), lanthanum strontium cobalt iron oxide (LSCF), lanthanum strontium manganate (LSM), etc. In this exemplary embodiment, the anode support layer of the annular wall (2085) is the outer diameter of each fuel cell, and the inner diameter of each fuel cell is the cathode layer. Therefore, in the second exemplary embodiment, the cathode chamber (2090) becomes the anode chamber, and the fuel is delivered to the anode chamber, while the cathode gas and air flow through the rod-shaped fuel cells.

[0096] The fuel (2027) flows through the anode material layer, while the cathode gas (oxygen-containing gas, such as air) flows through the cathode material layer to generate a current flow. The current flows out of the cell stack through the electrical leads (2125), (2130) to the DC current output terminal (140) and can be used to power an external device. It should be noted that in other embodiments (such as the second embodiment briefly described above), without departing from the present technology, the anode and cathode surfaces can be reversed, wherein the cathode layer is on the inner diameter of the fuel cell and the anode layer is on the outer diameter of the fuel cell, the air flows through the airflow duct formed by the fuel cell, and the fuel flows through the outer surface of the fuel cell.

[0097] The fuel input manifold (2055) includes a cylindrical chamber defined by a disc-shaped top wall (2170) and an opposing disc-shaped top tube support wall (2070). The disc-shaped fuel input manifold top wall (2170) includes a heat conductive block (2160). The heat conductive block (2160) includes one or more materials having a thermal conductivity greater than 100 W / (m°K), preferably greater than 200 W / (m°K), such as one or more of copper, molybdenum, aluminum copper, copper-nickel alloy, or a combination thereof. The heat conductive block (2160) is in thermal conductive communication with the hot zone housing wall (2015), particularly with the side wall (2002). The heat conductive block (2160) is positioned proximate to the annular cold start combustion chamber (2305), as described below, so as to receive thermal energy from fuel combusted within the annular cold start combustion chamber (2305) during startup and to conduct the thermal energy received therefrom to the hot zone outer wall (2015). In addition, when the fuel (2027) passes through the fuel input manifold (2055), the heat conductive block (2160) radiates the following heat energy to the fuel (2027): the heat energy received from the combustion of the fuel in the annular cold start combustion chamber (2305) and the heat energy received through thermal conduction of the hot zone shell wall.

[0098] The top tube support wall (2070) forms an airtight seal with the journal-shaped support end (2110) of each fuel cell top end cap (2095). In addition, each fuel cell (2080) is fixedly suspended from the top tube support wall (2070) via a mechanical interface formed in the top tube support wall (2070), and the top tube support wall (2070) includes a through hole for receiving the journal-shaped support end (2110) or a manifold adapter therethrough. In addition, the fuel input manifold (2055) is defined by the side wall (2002).

[0099] Since the present exemplary embodiment utilizes a CPOX reformer (2002), which uses an exothermic reaction to reform the feed fuel, the reformer (220) is a thermal energy source that is advantageously positioned within the hot zone (2000) to heat the incoming feed fuel and air mixture (2025) as the fuel enters the hot zone. However, in other embodiments of SOFC systems of the present technology, the reformer (2020) may utilize an endothermic reaction (e.g., a steam reformer) or a thermoneutral reaction (e.g., an autothermal reformer for reforming the fuel), and in these cases, the reformer (220) may be positioned outside the hot zone (2000) and instead placed in the cold zone (110), as in Figure 1 Thus, the improved hot zone (2000) of the present technology may be operated without the reformer (2020) without departing from the present technology.

[0100] 4.5 Exhaust Combustion Chamber

[0101] The tail gas burner or combustion zone (2135) is an annular volume disposed between a disc-shaped bottom tube support wall (2075) and a disc-shaped burner end wall (2140), the disc-shaped bottom tube support wall (2075) including a heat block (2180), both of which are described above and Figure 2 As shown in FIG, the disc-shaped burner end wall (2140) further includes a heat block (2175). The heat blocks (2180) and (2175) each include one or more materials having a thermal conductivity greater than 100 W / (m°K), preferably greater than 200 W / (m°K), such as one or more of copper, molybdenum, aluminum copper, copper-nickel alloy, or a combination thereof. The heat blocks (2180) and (2175) are positioned to receive thermal energy from the combustion zone (2135) and are configured to conduct the thermal energy received from the combustion zone to the hot zone housing wall (2015) and radiate the thermal energy received from the combustion zone into the cathode chamber (2090) and the recuperator chamber (2210).

[0102] An annular burner baffle (2185) is provided within the annular burner region to redirect airflow through the combustion zone (2135) and create turbulence, thereby increasing convective energy transfer to the sidewalls of the combustion zone (2135). The burner baffle (2185) may be fixedly attached to the hot zone casing sidewall (2002) or may comprise a portion of the combustor liner described below.

[0103] The cathode feed tube (2145) described below passes through the combustion zone (2135) along the central longitudinal axis (2060). The walls of the cathode feed tube (2145) are heated by convective heat transfer from the combustion gases within the combustion zone (2135). The air flowing through the cathode feed tube (2145) to the cathode chamber (2090) is heated by heat energy radiated from the cathode feed tube (2145) to the air flowing through the cathode feed tube (2145).

[0104] The inner wall of the combustion zone (2135) is lined with a high temperature resistant, corrosion resistant metal, such as a Hastelloy alloy. In the case of the disc-shaped bottom tube support wall (2075), the surface facing the burner zone comprises Hastelloy alloy. In the case of the burner zone end wall (2140), the surface facing the burner zone comprises Hastelloy alloy. In each case, the walls (2075), (2140) are formed as a composite structure having a Hastelloy alloy disc-shaped lining in thermal contact with the corresponding heat block (2180), (2175), respectively. The side wall of the combustion zone (2135) is also lined with a high temperature resistant, corrosion resistant metal, such as Hastelloy alloy. In a non-limiting exemplary embodiment, the side wall lining comprises a separate element formed as a tubular open-ended cylindrical wall, wherein the burner baffle (2185) is formed integrally with the cylindrical wall. Additionally, the sidewall liner is formed to be inserted into the hot zone housing sidewall (2002) and from either open end thereof and to be in thermally conductive contact with the sidewall (2002) over substantially the entire surface of the wall liner.

[0105] 4.6 Recuperator

[0106] Air (2200) enters the cathode feed tube (2145) through an input port (2205) and flows into a recuperator chamber (2210). The recuperator chamber (2210) is located proximate to the tail gas combustion zone (2135) to heat the incoming air (2200) using heat energy generated by the combustion of the waste fuel occurring within the combustion zone (2135). The recuperator chamber (2210) is an annular chamber surrounding the cathode feed tube (2145) and is bounded on the top side by a disc-shaped burner end wall (2140), on the bottom side by a disc-shaped hot zone housing bottom wall (2006), and on its sides by the hot zone housing side walls (2002).

[0107] Thermal energy is conducted to the walls of the recuperator chamber (2210) through the hot zone housing wall (2015), the burner end wall (2140), and to a lesser extent through the cathode feed tube (2145). Thermal energy is radiated from the recuperator chamber walls to the air as the air (2200) passes through the recuperator chamber (2210). The outer walls of the recuperator chamber (2210) are further heated by the hot exhaust gases exiting the combustion zone (2135). Specifically, the recuperator chamber (2210) is surrounded by an air gap (2155), which carries the hot exhaust gases exiting the combustion zone (2135) through the burner outlet port (2150) to the hot zone outlet port (2165). Thermal energy from the hot exhaust gases heats the outer wall portion of the recuperator chamber walls through convective heat transfer.

[0108] A recuperator baffle (2215) is provided inside the recuperator chamber (2210) and across the cathode feed tube (2145), thereby preventing air from flowing through the cathode feed tube (2145). Thus, the air (2200) entering the cathode feed tube (2145) through the input port (2205) hits the recuperator baffle (2215) inside the cathode feed tube and is forced into the recuperator chamber (2210) through one or more air input ports (2225). The input air (2200) flowing into the recuperator chamber through the air input port (2225) bypasses the recuperator baffle (2215) and re-enters the cathode feed tube through one or more recuperator air output ports (2235) after being heated in the recuperator chamber (2210).

[0109] 4.7 Cold start burner

[0110] refer to Figure 2 The SOFC hot zone (2000) optionally includes a cold start burner (2300) that is provided to initially heat the hot zone to an operating temperature above 350°C or at least until spontaneous combustion occurs in the tail gas burner region. The cold start burner includes an annular start combustion chamber (2305). The annular start combustion chamber (2305) surrounds the catalytic cavity (2035) and the annular thermal insulation element (2065). The annular start combustion chamber (2305) is defined at the top by the disc-shaped hot zone housing top wall (2004) and at the bottom by the disc-shaped fuel input manifold top wall (2170) including the annular thermal block (2175). The annular start combustion chamber (2305) is further defined by the hot zone housing side wall (2002).

[0111] The start-up burner inlet port (2310) receives unreformed start-up fuel (2315) from a start-up fuel source (not shown). The start-up fuel (2315) can include various combustible gases or vaporized liquid fuels, such as natural gas, propane, methane, hydrogen, alcohol, or a mixture of fuel and air. In some exemplary embodiments, the start-up fuel (2315) includes a supply fuel and air mixture (2025). The start-up fuel (2315) is delivered to the annular start-up combustion chamber (2305) along with air or another oxygen-containing gas through the burner inlet port (2310) and ignited by an electric spark igniter (2320) or some other ignition source.

[0112] During the startup combustion, the heat energy generated by the combustion of the startup fuel in the annular startup combustion chamber (2305) is transferred by convective heat transfer to the hot zone housing top wall (2004) and side walls (2002) and the fuel input manifold top wall (2170). From each of these walls, the heat energy of the startup combustion is transferred to other areas of the hot zone through the heat conductive hot zone housing wall (2015).

[0113] Exhaust gases from the startup combustion exit the annular startup combustion chamber (2305) through the startup burner outlet port (2325), which is in fluid communication with the air gap (2155) leading to the hot zone outlet port (2165). Thus, the exhaust gases flowing from the annular startup combustion chamber (2305) to the hot zone outlet (2165) further heat the outer surface of the hot zone shell wall (2015) through convective heat transfer.

[0114] The inner wall of the annular start-up combustion chamber (2305) is lined with a high-temperature, corrosion-resistant metal, such as Hastelloy. In the case of the disc-shaped hot zone housing top wall (2004), the wall is lined on its inner surface with a layer of Hastelloy material, wherein the Hastelloy layer is in thermally conductive contact with the hot zone housing top wall (2004). In the case of the disc-shaped fuel input manifold top wall (2170), the top side of the wall includes a layer of Hastelloy material in thermally conductive contact with an annular heat conductive block (2175). In the case of the side wall, a cylindrical wall liner comprising Hastelloy material is inserted into the start-up combustion chamber and is in thermally conductive contact with the hot zone housing side wall (2002).

[0115] 4.8 Gas Flow Diagram

[0116] 4.8.1 Fuel flow diagram

[0117] Now see Figure 3, a schematic fuel flow diagram describes the flow path of the supply fuel and air mixture (2025) as it passes through the hot zone (2000). The supply fuel and air mixture (2025) enters the reformer input port (2045) and passes through the reformer catalytic chamber (2035) to produce fuel (2027), such as reformate (reformed fuel). The fuel (2027) exits the reformer through the reformer outlet port (2050) and enters the fuel input manifold (2055). From the input manifold (2055), the fuel enters each fuel cell (2080) through the corresponding cell input port (2115), flows through each fuel cell, and exits the fuel cell through the corresponding cell output port (2120). Inside the fuel cell (2080), the fuel reacts on the anode material layer forming the inner surface of the cell annular wall (2085). After exiting the fuel cell through the cell outlet port (2120), the remaining fuel (2027) (which includes unreacted fuel and reaction byproducts) enters the combustion zone (2135), where the remaining fuel (2027) mixes with the air exiting the cathode chamber (2090) to form a mixture that spontaneously combusts in the combustion zone (2135). As described above, the heat energy generated by the combustion in the combustion zone (2135) is transferred to the side walls of the burner zone by radiation and convection, and is thermally conducted through the hot zone housing wall (2015) to other areas of the hot zone. In addition, the heat energy generated by the combustion in the combustion zone (2135) can be transferred to each of the heat conductive blocks (2175) and (2180) proximate to the burner zone by gas-to-surface heat transfer (through the housing wall by convection and heat conduction). Additionally, heat conductive blocks (2175) and (2180) near the burner area radiate heat energy into the recuperator chamber (2210) and cathode chamber (2090), respectively, to heat the air passing therethrough.

[0118] After combustion, exhaust gases from the burned mixture (as indicated by dashed arrows) exit the combustion zone (2135) through one or more burner outlet ports (2150) to the air gap (2155). From the air gap (2155), exhaust gases from the burned mixture exit the hot zone through the hot zone outlet port (2165).

[0119] 4.8.2 Fuel Flowchart Cold Start

[0120] like Figure 3 As further shown in FIG, the start-up fuel (2315) and air pass through the start-up burner inlet port (2310) into the annular start-up combustion chamber (2305), where the start-up fuel is combusted.

[0121] The exhaust gases after combustion (as shown by the dotted arrows) leave the combustion zone (2135) through one or more startup burner outlet ports (2325) to the air gap (2155). The exhaust gases from the startup burners leave the hot zone from the air gap (2155) through the hot zone outlet (2165).

[0122] 4.8.3 Air flow diagram

[0123] Now see Figure 4 , a schematic air flow diagram depicts the flow path of air (2200) as it passes through the hot zone (2000). The air (2200) enters the cathode feed tube (2145) through the air input port (2205). The air (2200) exits the cathode feed tube through the recuperator air input port (2230) to enter the recuperator chamber (2210). The air flows around the recuperator baffle (2215) and re-enters the cathode feed tube (2145) through the recuperator air output port (2235). Inside the recuperator chamber (2210), the air (2200) is heated by heat energy radiated from the recuperator chamber walls (2006), (2002) and the burner end wall (2140) and is associated with the annular heat conductive block (2175).

[0124] The air (2200) passes through the combustion zone (2135) as it flows through the cathode feed tube (2145). In the combustion zone, the air is further heated by heat energy radiated from the surface of the cathode feed tube (2145) before entering the cathode chamber (2090) while still flowing through the cathode feed tube (2145). The air (2200) exits the cathode feed tube and enters the cathode chamber (2090) through a plurality of cathode chamber air input ports (2240) disposed along a portion of the length of the cathode feed tube (2145) extending into the cathode chamber (2090).

[0125] Once inside the cathode chamber (2090), air (2200) fills the cathode chamber and strikes the outer diameter or cathode layer of each fuel cell (2080) and reacts with the cathode material layer coated on at least a portion of the outer diameter of each fuel cell. The reaction between the air passing through the cathode material layer and the reaction of the fuel (2027) passing through the anode material layer forming the inner diameter of each fuel cell couples to produce an electric current, which flows through the cathode material layer. Figure 3 The electrical leads (2125), (2130) shown are routed to the DC current output terminals (140).

[0126] After reacting with the cathode material layer coated on each fuel cell, the oxygen-reduced air (2200) (as shown by the dotted flow lines) exits the cathode chamber (2090) through one or more cathode chamber output ports (2245) leading to the combustion zone (2135). In the combustion zone (2135), the oxygen-depleted air mixes with the unconsumed fuel (2027) exhausted from the fuel cell and the mixture is burned. The exhaust gas from the burned mixture exits the combustion zone (2135) through the burner outlet port (2150), which leads to the air gap (2155). The air gap (2155) transports the exhaust gas to the hot zone outlet port (2165) and is exhausted from the hot zone.

[0127] Although Figure 4 Two diametrically opposed recuperator air input ports (2230), two diametrically opposed recuperator air output ports (2235), and multiple pairs of diametrically opposed cathode chamber air input ports (2240) are schematically shown, however a practical arrangement may include any hole pattern having one or more holes arranged circumferentially around the cathode feed tube (2145) as required for air flow distribution. Similarly, Figure 4 Two diametrically opposed cathode chamber air output ports (2245) and two diametrically opposed burner outlet ports (2150) are shown, however, a practical device may include any hole pattern having one or more holes arranged around the circumference of the disc-shaped wall (2004) or side wall (2002) as required for air flow distribution. Instead of any of the above gas ports, the gas ports may have non-circular shapes, such as square, rectangular, and oval or slotted shapes, without departing from the present technology.

[0128] 4.9 Shell wall surface treatment

[0129] According to one aspect of the present technology, no copper surfaces are exposed to oxygen / air to avoid oxidative damage to the copper. This includes all surfaces forming the entire fuel flow path and all surfaces forming the entire air flow path, as both the fuel and the air contain or may contain oxygen. Copper surfaces that may be exposed to the fuel flow or the air flow are protected by at least a nickel plating layer, which is applied to a thickness of 0.0005 inches to 0.0015 inches (12.5 μm to 38.1 μm) by electro-deposition plating or the like. The thickness of the nickel plating layer is greater than 100 times the normal thickness of a conventional nickel electrodeposited coating, and the thicker nickel coating is used to substantially prevent oxygen from diffusing through the nickel coating.

[0130] This aspect of the technology Figure 5A As shown in Figure 5AA non-limiting exemplary cross-sectional view (2015) taken through any one of the hot zone housing walls is depicted. The hot zone cavity wall cross section (5005) includes a copper core (5010) comprising copper having a thermal conductivity range of approximately 370 W / (m°K) at 500°C and approximately 332 W / (m°K) at 1027°C. The copper core (5010) has a thickness in the range of 0.01 inches to 0.125 inches (0.25 mm to 3.2 mm), although other thicknesses may be used without departing from the present technology. More generally, the hot zone cavity wall thickness may be increased or decreased as desired for a particular application. Generally, thicker housing walls (e.g., up to about 0.25 inches) take longer to heat to the desired operating temperature, but have the following advantages: once heated to the operating temperature, the thicker walls have higher thermal conductivity and are less prone to forming thermal gradients, and when surface oxidation is the failure mode, provide longer operating life than thinner walls simply because it takes longer for the thicker walls to oxidize to the point where the walls become unusable.

[0131] The copper core (5010) includes two opposing surfaces that form the inner and outer surfaces of the housing wall, and in a preferred embodiment, each of the inner and outer surfaces of the copper core (5010) is covered on the inner surface by an electrodeposited nickel coating (5015) and completely covered on the outer surface by an electrodeposited nickel coating (5020). Each nickel coating is applied to a layer thickness of at least 0.0005 inches (12.5 μm), which is suitably thick to prevent oxygen from diffusing through the nickel coating. More generally, a desired nickel coating thickness in the range of 0.0005 to 0.0015 (12.5 μm to 38.1 μm) provides sufficient surface protection from oxidation to achieve a product life of up to about 40,000 hours, and thicker nickel coatings may be used to increase product life without departing from the present technology. See Figure 2 , the wall section (5005) represents at least the outer wall of the hot zone shell wall (2015) including the side walls (2002), the disc-shaped top wall (2004), and the disc-shaped bottom wall (2006), and may represent some walls of the reformer shell wall (2030).

[0132] According to one aspect of the present technology, the combustion chamber surface is lined with a high temperature resistant, corrosion resistant metal (such as Hastelloy) to protect the interior surface of the combustion chamber from surface damage caused by exposure to high temperatures, combustion byproducts and corrosive elements. Alternative monel copper-nickel alloys or inconel alloys may be used without departing from the present technology.

[0133] This aspect of the technology Figure 5B As shown in Figure 5BA non-limiting exemplary cross-sectional view (5025) taken through the combustion chamber sidewall is depicted. The sidewall cross-section (5025) includes the copper core (5010) of the hot zone housing sidewall (2002) and the electrodeposited nickel coatings (5015), (5020) applied to opposite sides of the copper core as described above. Specifically, the cross-sectional view (5025) includes Figure 5A In addition, the combustion chamber sidewall section (5025) further includes a Hastelloy liner (5030) positioned to line the inner surface of the combustion chamber. Figure 2 , the sidewall cross section (5025) shows at least the cylindrical outer wall of the annular tail gas combustion zone (2135) and the cylindrical outer wall of the annular cold start combustion chamber (2305). The sidewall cross section (5025) shows the hot zone sidewall (2002) protected by the Hastelloy liner element (5030). In the specific example of the tail gas combustion zone (2135), the Hastelloy liner element (5030) also includes a burner baffle (2185) attached thereto or formed integrally therewith. However, in addition to the presence of the burner baffle (2185), the cross section (5025) also shows the top wall and sidewall of the annular cold start combustion chamber (2305).

[0134] Each of the combustion zones (2135), (2305) is further lined with a pair of opposing disc-shaped Hastelloy lining elements positioned to line the interior top and interior bottom surfaces of the burner zone. In the case of the tail gas burner zone (2135), its chamber top wall is formed by the bottom tube support wall (2075), which includes the disc-shaped Hastelloy lining elements (5050), such as Figure 5C As shown. The lining element (5050) is arranged to face the interior of the annular tail gas combustion area or the annular tail gas combustion chamber (2135). The tail gas combustion area bottom wall is formed by the burner end wall (2140), and the burner end wall (2140) also includes a disc-shaped Hastelloy liner (5060) facing the interior of the annular combustion area chamber (2135).

[0135] In the case of the annular cold start combustion chamber (2305) of the cold start burner (2300), its top chamber wall is formed by the hot zone housing top wall (2004), and the hot zone housing top wall (2004) includes an annular Hastelloy lining element (5030) in contact with the inner top wall of the annular cold start combustion chamber (2305). Specifically, the hot zone housing top wall (2004) and the top wall of the annular cold start combustion chamber (2305) are Figure 5B The cross-sectional view is detailed. Figure 5BA copper core (5010) is shown covered on the inner surface by an electrodeposited nickel layer (5015) and on the outer surface by an electrodeposited nickel layer (5020), and includes a Hastelloy liner element (5030) in contact with the nickel layer (5015). Although the cross-section (5025) is vertically oriented and includes a Hastelloy burner baffle (2185), the cross-section is identical to the top wall (2004) without the burner baffle (2185) and is rotated to a horizontal orientation like the top wall (2004).

[0136] The bottom wall of the annular cold start combustion chamber (2305) is formed by the top wall of the fuel inlet manifold (2170). This wall also includes an annular Hastelloy liner element (5060) similar to Figure 5B As shown, it contacts and cooperates with the inner bottom wall of the annular cold start combustion chamber (2305).

[0137] According to one aspect of the present technology, no incoming air (2200) is exposed to surfaces formed from materials comprising chromium to avoid contaminating the cathode layer applied to the outer surface of the fuel cell (2080). This includes all surfaces forming the entire incoming air flow path, including the inner surface of the cathode feed tube (2145), the recuperator chamber (2210), the recuperator baffles (2215), the outer surface of the cathode feed tube (2145), the inner surface of the cathode chamber (2090), and the components housed within the cathode chamber, including the fuel cell end caps (2095), (2100) and the top and bottom tube support walls (2070), (2075).

[0138] In a non-limiting exemplary embodiment, the cathode feed tube (2145), the recuperator baffle (2215), and each bottom end cap (2100) are formed of a high-temperature metal alloy that is chromium-free and corrosion-resistant, such as monel copper-nickel alloy. Additionally, at least the bottom surface of the burner end wall (2140) forming the top surface of the recuperator chamber (2210) is formed of or lined with a protective element formed of a high-temperature metal alloy that is chromium-free and corrosion-resistant, such as monel copper-nickel alloy. Similarly, at least the top surface of the bottom tube support wall (2075) forming the bottom surface of the cathode chamber (2090) is formed of or lined with a protective element formed of a high-temperature metal alloy that is chromium-free and corrosion-resistant, such as monel copper-nickel alloy.

[0139] The inner surfaces of the chamber that are associated with the incoming air flow and are coated with the above-mentioned electrodeposited nickel layer can be exposed to the air flow without being exposed to chromium. The nickel-plated surfaces that can be exposed to the incoming air flow include: side walls (2002) and a disc-shaped bottom wall (2006), the side walls (2002) forming the side walls of each of the recuperator chamber (2210) and the cathode chamber (2090); the disc-shaped bottom wall (2006) forming the bottom wall of the recuperator chamber (2210). The surfaces each have Figure 5A In addition, other surfaces formed of chromium-containing materials inside the cathode chamber (2090), such as the top tube support wall (2070) and the top end cap (2095), both formed of Inconel, are covered with a nickel plating layer applied to a thickness of 0.0005 to 0.0015 inches (12.5 μm to 38.1 μm) by electrodeposition plating or the like to prevent air contamination by chromium.

[0140] Now see Figure 5C , a detailed cross-sectional view depicts a section (5040) taken through the bottom tube support wall (2075). The detailed cross-sectional view shows a thermally conductive block (2180) comprising a copper block having a thermal conductivity of approximately 370 W / (m°K) at 500°C and a thermal conductivity of approximately 332 W / (m°K) at 1027°C. The copper block (2180) has a thickness in the range of 0.01 inches to 0.375 inches (2.5 mm to 9.5 mm), however, other thicknesses may be used without departing from the present technology. The top surface of the bottom tube support wall (2075) faces the interior of the cathode chamber (2090) and is therefore lined with a disc-shaped lining element (5045) formed of a chromium-free and corrosion-resistant high-temperature metal alloy (e.g., monel copper-nickel alloy) to avoid contamination of the cathode gas with chromium. The bottom surface of the bottom tube support wall (2075) faces the exhaust gas combustion area (2135) and is lined with a disc-shaped liner (5050) formed of Hastelloy.

[0141] Now see Figure 5D, a non-limiting exemplary detailed cross-sectional view depicts a section (5055) taken through the combustor end wall (2140). The detailed cross-section shows a thermally conductive block (2140) comprising a copper block having a thermal conductivity in the range of about 370 W / (m°K) at 500°C and about 332 W / (m°K) at 1027°C. The copper block (2175) has a thickness in the range of 0.01 inches to 0.375 inches (2.5 mm to 9.5 mm), although other thicknesses may be used without departing from the present technology. The top surface of the wall (2140) faces the interior of the exhaust combustion zone (2135) and is therefore lined with an annular liner element (5060) formed of solid Hastelloy. The bottom surface of the wall (2140) faces the recuperator chamber (2210) and is lined with an annular lining (5065) formed of a high temperature metal alloy that is chromium-free and corrosion-resistant; for example, monel copper-nickel alloy.

[0142] Now see Figure 5E , a non-limiting exemplary detailed cross-sectional view depicts a cross-section (5070) taken through the fuel input manifold top wall (2170). The detailed cross-sectional view shows a thermally conductive block (2160) comprising a copper block having a thermal conductivity range of approximately 370 W / (m°K) at 500°C and approximately 332 W / (m°K) at 1027°C. The thermally conductive copper block (2160) has a thickness in the range of 0.01 inches to 0.375 inches (2.5 mm to 9.5 mm), however, other thicknesses may be used without departing from the present technology. The opposing top and bottom surfaces of the thermally conductive copper block (2160) are optionally covered with a nickel plating layer (5075) applied to a thickness of 0.0005 inches to 0.0015 inches (12.5 μm to 38.1 μm) by electrodeposition plating or the like. Nickel plating is applied to prevent contact between the supplied fuel and air mixture (2025) and the heat conductive copper block (2160) to prevent oxidation of the copper block surface. The top surface of the fuel input manifold top wall (2170) faces the interior of the annular cold start combustion chamber (2305) and is therefore lined with an annular lining member (5080) formed of solid Hastelloy to protect the heat conductive block (2160) from thermal damage.

[0143] Figure 5D and Figure 5C Another variation of the walls (2075) and (2180) shown in detail in FIG is that both sides of the copper blocks (2180), (2175) are covered with a nickel plating layer applied to a thickness of 0.0005 to 0.0015 inches (12.5 μm to 38.1 μm) by, for example, electrodeposition plating as described above, see Figure 5E. Nickel plating is included to avoid contact between the supplied fuel and air mixture (2025) and / or air (2200) and the respective copper blocks (2180), (2175), thereby avoiding oxidation of the copper block surfaces. In the case where the Hastelloy elements (5050), (5060) and the Monel elements (5045), (5065) comprise separate lining elements, i.e. are not formed integrally with the copper blocks (2180), the copper blocks are preferably nickel plated on two opposing surfaces thereof (e.g. as Figure 5E However, in other cases where the disc-shaped or annular liner elements (5045), (5050), (5060), (5065) are integrally formed with the copper blocks (2180) and / or (2175) being nickel plated, the copper blocks may not be required.

[0144] Typically, the Hastelloy and Monel elements described above are used to protect various surfaces from damage or contamination of incoming air through contact with chromium-containing surfaces, such as Inconel or Hastelloy surfaces. In one non-limiting exemplary embodiment, one or more protective elements are manufactured separately from the hot zone housing wall (2015) and installed in place during assembly, such as by brazing a layer of protective material onto the surface being protected. Figure 5C and Figure 5D In the exemplary copper blocks (2180, 2175) shown, protective monel and hastelloy layers are brazed directly to opposing surfaces of the copper blocks without nickel plating the copper blocks. Preferably, the brazing step substantially gas-seals the copper blocks to prevent air or fuel from contacting and oxidizing the surfaces of the copper blocks.

[0145] exist Figure 5E In the example thermally conductive copper block (2160) shown in FIG, a protective Hastelloy layer is brazed directly to a nickel layer (5075) on one surface of the copper block disposed within the combustion zone (2135). In a non-limiting exemplary embodiment, the Hastelloy layer is installed to protect the copper block surface from direct exposure to combustion and corrosive elements. On the opposing surface, only the nickel plated protective layer (5075) is applied to the copper block surface disposed inside the recuperator chamber (2210) because the nickel layer is only needed to protect the copper block surface from oxidation by incoming air. Figure 5E In the example, the Hastelloy layer (5080) can be mechanically attached, such as by fasteners or clamping in place, without the need for a gas-sealed copper surface because the copper surface is already protected by the nickel layer (5075) disposed between the thermally conductive copper block (2160) and the Hastelloy layer (5080).

[0146] Therefore, as above and especially with respect to Figure 5B 、 Figure 5C 、 Figure 5D and Figure 5EAs described, the Hastelloy and Monel elements may comprise a plurality of separate elements, such as disc-shaped elements (5040), (5050), (5060), (5065), (5080) that engage with the disc-shaped heat block elements (2180), (2175), (2160), or the Hastelloy and Monel elements may comprise cylindrical wall portions, such as (5030), configured to engage with the inner cylindrical wall surface of the combustion chamber, such as the sidewall (2002) of the hot zone housing wall. The cylindrical wall portions are inserted into appropriate locations within the hot zone housing wall, such as within the annular cold start combustion chamber (2305) and within the tail gas combustion area (2135), and brazed, welded, or otherwise fastened or clamped in place, engaging with the surface to be protected. In some embodiments, the Hastelloy and Monel elements can be applied directly to the conductive core surface (e.g., brazed directly to the surface of the thermal block) with a substantially airtight seal. In other embodiments, the thermal block or core wall surface is nickel-plated, and the Hastelloy or Monel elements can be applied over the nickel plating without providing a substantially airtight seal, and instead of brazing over the entire surface to provide a gas seal, the elements can be held in place by clamping, by mechanical fasteners, or by brazing or spot welding at selected points. In further embodiments, any of the above-described wall structures can be formed as a metal casting, with various layers of protective material formed on selected surfaces of the metal casting by well-known methods (including electroplating, sputtering, spray coating, hot dipping, etc.).

[0147] However, in other non-limiting embodiments of the present technology, portions of the outer and / or inner walls of the hot zone housing wall (2015) are formed from prefabricated multi-layer composite materials. Composite materials include plates and / or tubes made from multiple layers of different metals, which can be used to form the various hot zone housing walls described herein.

[0148] In the first step, sheets of dissimilar metals are joined together by an extrusion or rolling process commonly referred to as cladding. In an exemplary embodiment, see Figure 5C , a composite sheet comprising a copper block (2180), a Hastelloy layer (5050) and a Monel copper-nickel alloy layer (5045) is hot roll welded to form a composite sheet. Once formed, the bottom tube support wall (2075) can be cut from the composite sheet and holes and other features added in a secondary operation. The bottom tube support wall (2075) is then assembled to the hot zone shell wall (2015) by brazing, welding, mechanical fastening, clamping, high temperature adhesive bonding, etc. In addition, in Figure 5D The wall 2140 shown in FIG. 1 includes the Figure 5CThe same layers of material as the bottom tube support wall 2075 shown in FIG (only the order is reversed) can be cut from the same composite sheet, and holes and other features added in a secondary operation. Each of the wall (2140) and the bottom tube support wall (2075) are then assembled to the hot zone shell wall (2015) by brazing, welding, mechanical fastening, clamping, high temperature adhesive bonding, etc.

[0149] In an exemplary embodiment, see Figure 5E The composite sheet comprising the thermally conductive copper block (2160) and the Hastelloy layer (5080) is hot roll welded to form the composite sheet. In this exemplary embodiment, the nickel layer (5075) can be omitted, resulting in a composite sheet having only two layers. Once formed, the fuel input manifold top wall (2170) can be cut from the composite sheet, and holes and other features added in a secondary operation. The fuel input manifold top wall (2170) is then assembled to the hot zone housing wall (2015) by brazing, welding, mechanical fastening, clamping, high temperature adhesive bonding, etc. In a further step, the composite sheet can be nickel plated on at least the copper surface to prevent oxidation of the exposed copper surface.

[0150] Similar reference Figure 5B , two layers of composite sheet including a copper core (5010) and a Hastelloy layer (5030) are hot roll welded to form a composite sheet. In this exemplary embodiment, the nickel layers (5015), (5020) can be omitted so that the composite sheet has only two layers. Once formed, holes and other features are formed by secondary operations, and then the composite sheet is formed into a cylindrical wall. The cylindrical wall is cut to a certain size and assembled with other cylindrical wall sections to form a portion of the hot zone shell side wall (2002) associated with enclosing the combustion zone. The cylindrical wall portions can be joined together by brazing, welding, mechanical fastening, clamping, high temperature adhesive bonding, etc. In another step, the composite sheet can be nickel plated on one or both sides, and the assembled hot zone shell side wall can be nickel plated to protect the exposed copper surface from oxidation.

[0151] 4.10 SOFC fuel cell stack configuration

[0152] Now see Figure 6 , a portion of a non-limiting exemplary embodiment of an SOFC system embodiment (7000) that can be used with the present technology is shown in top cross-sectional view. The configuration (7000) shown in top cross-sectional view depicts a cathode chamber (7010) enclosed by a circular hot zone housing wall (7015). The circular housing wall (7015) is surrounded by a circular thermal insulation layer (7020), which is separated from the circular housing wall by a small air gap (not shown) that can serve as a gas flow conduit as described above.

[0153] The cathode feed tube (7025) is shown centered relative to the circular hot zone housing wall (7015). The plurality of rod-shaped fuel cells are arranged in two concentric circular patterns, wherein each circular pattern is centered relative to the same central axis (7030). The inner circular pattern (7035) includes eight inner rod-shaped fuel cells (7040). The outer circular pattern (7045) includes fourteen outer rod-shaped fuel cells (7050). Other housing shapes and fuel cell patterns may be used without departing from the present technology.

[0154] 4.11 Alternative SOFC System Examples

[0155] Now turn to Figures 7-9 and Figure 12-15 , Figures 7A-9C A first alternative non-limiting exemplary embodiment of a portion of an improved SOFC system (8000) shown in includes a U-shaped main housing wall assembly (8045) enclosing a SOFC stack (8005). Figure 12-13B A second alternative non-limiting exemplary embodiment of a portion of an improved SOFC system is shown in The second alternative SOFC system includes two L-shaped main housing wall assemblies (12045), wherein each L-shaped main housing wall assembly (12045) encloses a single SOFC stack (8005) to provide a dual-stack SOFC system (12000). Figure 14 A third alternative non-limiting exemplary embodiment of a portion of an improved SOFC system (14000) is shown. The third alternative SOFC system (14000) includes an L-shaped main housing wall assembly (12045) enclosing a single SOFC stack (8005). Figure 15 A fourth alternative non-limiting embodiment of a portion of an improved SOFC system (15000) is shown in FIG. The fourth alternative SOFC system (15000) includes two U-shaped main housing wall assemblies (8045), each U-shaped main housing wall assembly (8045) enclosing a different SOFC stack (8005). Each SOFC stack (8005) includes a plurality of individual fuel cells (8010). In a non-limiting exemplary embodiment, the individual fuel cells (8010) are arranged in pairs of two individual fuel cells along the axis indicated by the system coordinate diagram (8100) (in FIG. Figure 9A 、 Figure 12 and Figure 14The SOFC stack is arranged in a manner that they are positioned side by side along the stack transverse width axis (y) defined by the stack (shown in Figure 1). In this embodiment, multiple pairs of two fuel cells (8010) are positioned side by side along the stack longitudinal length axis (x). However, the technology described herein is not limited to the exemplary arrangement of fuel cells in this embodiment, and is further not limited to tubular fuel cells. Any other suitable arrangement of fuel cells within the SOFC stack may be used without departing from the concepts of the technology described herein. The number of fuel cells (8010) in the SOFC stack is selected to meet a predetermined power generation demand or other stack capacity factor. In other embodiments, the number of fuel cells arranged along either the stack transverse width axis (y) or the stack longitudinal length axis (x) can be one or more, wherein the total number of individual fuel cells (8010) is selected to meet a predetermined power generation demand or other stack capacity factor.

[0156] In a non-limiting exemplary embodiment, each fuel cell (8010) includes an open-ended hollow fluid conduit disposed along a central axis of the conduit. The shape of the hollow fluid conduit is preferably cylindrical or elliptical; however, other fluid conduit shapes, such as square, rectangular, triangular, or other polygonal shapes, may be used without departing from the present technology. Alternatively, the hollow fluid conduit may be arranged in any embodiment that includes an anode layer separated from a cathode layer by an electrolyte layer, wherein an anode gas (e.g., reformate or synthesis gas) passes through the anode layer and a cathode gas (e.g., air) passes through the cathode layer without departing from the present technology.

[0157] Each fuel cell is formed by a peripheral wall surrounding a hollow fluid conduit. The peripheral wall comprises three main material layers, each of which is formed by a Figure 1 Schematically shown in . The three main material layers include an anode layer or fuel electrode (150), a cathode layer or air electrode (155), and an electrolyte layer (145) separating the anode layer from the cathode layer. All layers include solid materials, some of which (e.g., the anode) may include solid materials formed into a porous structure. In this non-limiting exemplary embodiment, the outer edge wall includes an inner surface formed by the anode layer, an outer surface formed by the cathode layer, and an electrolyte layer disposed between the anode layer and the cathode layer. Preferably, one of the three layers is configured as a support layer (e.g., the anode layer), wherein the support layer is formed to have sufficient structural rigidity and integrity to support each individual fuel cell (8010) in the operating position described below.

[0158] See also Figure 7A and Figure 7B, each fuel cell (8010) includes a fuel input end (8020) and a fuel output end (8025) corresponding to opposite open ends of the hollow fluid conduit. At least the fuel input end (8020) is supported by an interface with the fuel input manifold (8015) or other support structure. In a non-limiting example, the fuel input end (8020) of each fuel cell includes an end cap (2100) and a journal-shaped support end (2110), the end cap being formed as a cup-shaped attachment end (2105), and the journal-shaped support end being configured to mechanically interface the fuel input end of each fuel cell with the fuel input manifold (8015) so that the end cap (2100) couples the fuel input end to the fuel input manifold. Other mechanical interfaces of each fuel cell with the fuel input manifold (8015) are available without departing from the present technology. The mechanical interface of each fuel cell (8010) to the fuel input manifold (8015) is configured to fixedly support each individual fuel cell (8010) in an operating position in which the central longitudinal axis of the hollow fluid conduit of each individual fuel cell (8010) is supported to be approximately parallel to the stack gas flow axis (z). The mechanical interface between the fuel input manifold and the fuel input end (8020) of each individual fuel cell (8010) forms an airtight seal. In a preferred embodiment, the fuel output end (8025) of the fuel cell (8010) is unsupported; however, an upper support structure or other mechanical support structure that supports the fuel output end (8025) of an individual fuel cell (8010) relative to the main housing wall may be used without departing from the present technology.

[0159] and Figure 2 Compared to the embodiment shown and described above in which the fuel stream (2027) is delivered to the top of the SOFC system and the cathode air stream (2200) is delivered to the bottom of the SOFC system (2000), in Figure 7A 、 Figure 7B 、 Figure 12 、 Figure 14 and Figure 15The direction of fuel flow through the SOFC stack shown in is reversed because the respective fuel input manifold (8015) is near the bottom or end of the respective SOFC system, with only the bottom or fuel input end (8020) supported by the fuel input manifold (8015) and the end cap (2100) or other coupling element. Thus, according to one aspect of the present technology, the fuel output end (8025) of an individual fuel cell is not supported or mechanically interfaced by other elements of the SOFC system. Such a support structure is advantageous because it allows the fuel cell to expand and contract longitudinally during thermal cycling (e.g., on-off cycling), thereby avoiding stresses in the fuel cell during thermal cycling. Furthermore, such a support structure is advantageous because it does not require a gas seal at the fuel output end (8025). Overall, the lack of output end support reduces cost and complexity while improving reliability by eliminating potential system failure modes.

[0160] like Figure 7A 、 Figure 7B 、 Figure 12 、 Figure 14 and Figure 15 As shown in each of the figures, the fuel output end (8025) of each individual fuel cell (8010) is positioned to discharge the spent fuel from the fuel output end (8025) to the combustion area (8030) after the fuel has passed through the hollow tubes and interacted with the anode layer forming the inner surface of each hollow tube. Figure 7A 、 Figure 7B 、 Figure 12 、 Figure 14 and Figure 15 As shown by the dashed fuel flow indicator lines and arrows, the fuel supply exiting the fuel reactor or fuel reformer (8035) flows through the fuel delivery conduit (8040) to the fuel input manifold (8015), where the fuel flow is distributed from the fuel input manifold to the fuel input end (8020) of each individual fuel cell (8010).

[0161] The fuel reformer (8035) is described above as Figure 2 The fuel reformer (2020) and Figure 1 The fuel reformer (165) shown in FIG. Details of a non-limiting embodiment of the fuel reformer (8035) are disclosed in related U.S. patent application No. 15 / 287,402 filed on October 16, 2016, and published as US: 10573911 B2 on February 25, 2020. While passing through each fuel cell, the fuel is mixed with oxygen ions (O + ) reaction and consumes hydrogen (H 2) and carbon monoxide (MO) to produce electricity. Spent fuel or waste fuel exits each fuel cell through an output (8025) to mix with spent cathode air in a combustion zone (8030). Other fuel reformer configurations and operating modes are available without departing from the present technology.

[0162] exist Figure 2-Figure 4 The SOFC system (2000) shown in FIG and described above is configured with a separate fuel cell input port or input end (2125) positioned at the top of the SOFC stack and a fuel cell output port or output end (2120) positioned at the bottom of the SOFC stack. The SOFC system (2000) also positions a fuel input manifold (2055) above the fuel cell input port or input end (2125). The SOFC system (2000) is also configured with an annular cold start combustion chamber (2305) surrounding the catalytic chamber (2035) of the fuel reformer (2035). The SOFC system (2000) also positions a tail gas chamber (2135) and a recuperator chamber (2210) at the bottom of the SOFC stack to receive spent fuel from the fuel cell output port or output end (2120). The SOFC system (2000) receives incoming air (cathode gas) into the recuperator chamber (2210) from the air input port (2225) located at the bottom end of the SOFC system (2000) and exhausts exhaust gas from the recuperator chamber through the hot zone outlet port (2165). Figure 2 As further shown, a fuel and air mixture (2025) is supplied into the SOFC system (2000) to the fuel reformer (2020) for steady state operation and through the inlet port (2310) to the start-up combustion chamber (2305), both of which are positioned at the top end of the SOFC stack.

[0163] According to one aspect of the present technology, the alternative SOFC systems (8000, 12000, 14000, 15000) described herein provide alternative gas flow patterns compared to the gas flow characteristics of the system (2000) described above. Figure 7A 、 Figure 9A 、 Figure 12 、 Figure 14 and Figure 15 The fuel and air mixture (2025) is received at the top of the SOFC system into the corresponding fuel reformer (8035). The fuel (8150) is delivered from the fuel reformer (8035) to the corresponding fuel input manifold (8015) via the fuel delivery pipe (8040). In a preferred embodiment, the fuel delivery pipe (8040) is housed within each of the intermediate housing (9000) or outer housing (16000) described below.

[0164] like Figure 9A As best shown in FIG, the start-up fuel (8152) is delivered to the burner assembly (8155) through the conduit (8145). The burner assembly extends through the corresponding combustion zone (8030) and injects the start-up fuel (8152) into the combustion zone during cold start operation. The igniter (8160) is positioned within the combustion zone to ignite the fuel flow exiting the burner assembly to initiate combustion within the corresponding combustion zone (8030). Figure 12 and Figure 15 As shown, when the SOFC system is a dual stack system, these systems preferably include a burner assembly (8155) and an igniter (8160) provided in each combustion zone (8030). As described in detail below, each burner assembly includes a startup fuel conduit (8145) for receiving startup fuel (8152) from a connection to the supply fuel input pipeline (160) or from a separate startup fuel source. Each fuel delivery pipeline (8040) may include a pipeline section connected to one or more startup conduits (8145) for use during startup. The corresponding fuel delivery conduits may include control elements, such as valves and valve actuator elements, which can be operated by an electronic controller (190) to independently adjust fuel flow and / or divert fuel from the fuel reformer (8035) to one or more fuel input manifolds (8015), and divert supply fuel from the supply fuel input pipeline (160) to one or more startup conduits (8145) under the control of the electronic controller (190).

[0165] 4.12 Cold Start Operation of Alternative SOFC

[0166] refer to Figure 7A 、 Figure 9A 、 Figure 12 、 Figure 14 and Figure 15 , cathode air is received into the corresponding recuperator chamber (9050) located at the top of the SOFC system through the cathode input port (9040), and the exhaust gas is directed out of the hot zone exhaust duct (9055) through the exhaust port (9045) also located at the top of the SOFC system. Figure 16B As best shown in , each alternative SOFC system ( 8000 , 12000 , 14000 , 15000 ) of the present technology is configured with all input and outlet gas ports extending from the top wall of the SOFC system.

[0167] The combustion zone (8030) includes a burner element (8155), such as Figure 9AAs shown, during cold start operation, start-up fuel is delivered through the burner element via the start-up fuel input conduit (8145). The start-up fuel is ignited in the combustion zone (8030), for example by an electrical igniter (8160), to provide thermal energy for heating one or more main housing wall components (e.g., (8045) or (12045)) during cold start operation. After the SOFC system is heated to an operating temperature that can support the SOFC reaction in the fuel cell, fuel flow begins to flow from the fuel reformer (8035) through the input manifold (8015) to the SOFC stack to initiate the SOFC reaction. The start-up fuel can be, for example, a reformate produced by the fuel reformer when fuel (8150) is delivered to the start-up conduit (8145) as the start-up fuel (8052), the supply fuel and air mixture (2025), or an alternative start-up fuel (8152) (e.g., propane, etc.). The start-up fuel can be delivered from, for example, through Figure 16A Another source of additional startup fuel conduits (16020) is shown in FIG. In this embodiment, the startup input conduit (16020) is fluidly interfaced with one or more startup conduits (8145). Figure 7A 、 Figure 7B 、 Figure 12 、 Figure 14 and Figure 15 An advantage of the configuration of the combustion zone (8030) shown is that the combustion zone (8030) is configured for two operating modes: a startup mode, in which fuel is delivered to the burner elements (8155); and / or a steady-state power generation mode, in which fuel (8150) is delivered from the fuel input manifold (8015) to individual fuel cells, and the spent fuel and spent cathode gas are combusted in the combustion zone (8030). In other embodiments and operating modes, the fuel delivery conduit (8040) feeds each startup conduit (8145), and the startup mode includes delivering fuel (8150) simultaneously to the corresponding startup burner element (8155) and the fuel input manifold (8015). The combination of the functions of the combustion zone (8030) for start-up and power generation is advantageous because it reduces the overall volume of the SOFC system and reduces the number of components and complexity, as well as directly heating the main housing assemblies (8045) and (12045) as described below, the incoming cathode air and the fuel cell (8010), which is heated on the interior surface by the fuel flowing therethrough and on the exterior surface by the cathode air flow and by heat energy transferred by radiation and convection from the main housing wall assembly. Figures 1 to 4, compared to the embodiment shown in , in which the start-up chamber (2035) more directly heats the fuel reformer, and the incoming anode gas configuration including a combustion zone (8030) partially surrounded by a combustion wall more directly heats the main shell wall assembly (8045, 12045), and the main shell wall assembly (8045, 12045) redistributes heat energy absorbed from the combustion zone (8030) to other areas away from the combustion zone by heat conduction.

[0168] 4.12.1 U-shaped main housing wall assembly

[0169] See also Figure 9A and Figure 9C , an exemplary hot zone housing assembly (8042) is shown in a side isometric view. The hot zone housing assembly (8042) includes a U-shaped main housing wall assembly (8045), the U-shaped main housing wall assembly (8045) including a combustion zone wall (8060) formed with a cylindrical radius and two opposing main housing side walls (8065, 8070) extending from the edge of the combustion zone wall (8060). Each of the side walls (8065, 8070) extends from the combustion zone wall along an axis parallel to the air flow axis (z) to a lower volume (8142) of the cathode chamber, for example, below the cathode chamber input port (8095). The hot zone housing assembly (8042) also includes a fuel input manifold (8015), an optional hot zone housing base wall (8075) and two optional hot zone housing end walls (8080, 8085). The U-shaped main housing wall assembly (8045) defines the cathode chamber (8055) (at Figure 7A and Figure 7B ). The cathode chamber (8055) encloses the SOFC stack (8005) and the combustion zone (8030), such that the cathode layer formed on the outer surface of each individual fuel cell (8010) is exposed to the cathode chamber (8055). The cathode chamber (8055) is defined by a U-shaped main housing wall assembly (8045), a fuel input manifold (8015), and optionally by a hot zone housing base wall (8075) and optionally by hot zone housing end walls (8080, 8085).

[0170] The cathode chamber (8055) receives a continuous heated cathode gas flow (in this case a heated air flow) from an external air flow source, e.g. Figure 1 The air delivery control system (198) is shown. The combustion zone (8030) forms the uppermost volume of the cathode chamber (8055). The lower volume (8142) of the cathode chamber near the fuel input end (8020) passes through Figure 9BThe plurality of cathode chamber input ports (8095) shown in FIG receive heated air flow (cathode gas). The middle volume (8140) of the cathode chamber extends from the lower volume (8142) of the cathode chamber to the fuel output end (8025) of each individual fuel cell (8010). When the heated cathode air flow passes over the outer surface of each fuel cell, the heated cathode air flow reacts with the cathode layer surface of each individual fuel cell (8010).

[0171] A non-limiting exemplary embodiment of a U-shaped main housing assembly (8045) includes a combustion region wall (8060) formed to enclose a combustion region (8030). The combustion region wall (8060) provides an upper boundary of the combustion region (8030) that extends substantially along the entire length of the stack length axis (x) and may further extend beyond the entire stack length. The U-shaped main housing wall assembly (8045) further includes two opposing main housing side walls (8065, 8070). Each main housing side wall (8065, 8070) extends from the combustion region wall (8060) and is fixedly attached to or integrally formed with the combustion region wall. Preferably, each main housing side wall extends the length of the fuel cell stack (8005) from the open fuel output end (8025) parallel to the air flow axis (z) to the fuel input end (8020).

[0172] The two opposing main shell side walls (8065, 8070) and the combustion zone wall (8060) together define the top and opposite sides of the cathode chamber (8055) along the stack length axis (x), which is determined by Figure 7B . Preferably, the combustion zone wall (8060) and the housing side walls (8065, 8070) are formed as a unitary element to facilitate overall heat conduction. However, when the combustion zone wall (8060) and the housing side walls (8065, 8070) are formed as separate wall elements, the separate elements are joined in a manner that provides high thermal conductivity across the joint boundary, for example using a joining material having a thermal conductivity of 100 W / m°K to 300 W / m°K.

[0173] In a non-limiting exemplary first embodiment, as Figure 9C As shown, the hot zone housing assembly base wall (8075) is mechanically interfaced with the bottom edge of each of the two opposing main housing side walls (8065, 8070). The mechanical interface is a welded or soldered joint; however, other mechanical interface elements may be used, including fasteners, interconnecting fastening elements such as rivets, clips, or interlocking features integrally formed with each of the two opposing main housing side walls (8065, 8070) and / or integrally formed with the hot zone housing base wall (8075), or the hot zone housing base wall (8075) may be integrally formed with one of the two opposing main housing side walls (8065, 8070). Figure 9AIn a non-limiting first embodiment, the fuel input manifold (8015) can be mechanically interfaced with the hot zone housing base wall (8075), such as by welding, brazing, soldering, or mechanical fasteners, without having to interface with one or both of the two opposing main housing side walls (8065, 8070).

[0174] exist Figure 7A In the non-limiting second exemplary embodiment shown in , each of the two opposing main housing assembly side walls (8065, 8070) is or can be mechanically interfaced with the fuel input manifold (8015) in the absence of a base wall (8075). The mechanical interface between each hot zone housing assembly side wall and the fuel input manifold is a welded or soldered joint; however, other mechanical interface elements are available, including separate fasteners and / or fastening elements that are integrally formed with one or both of the two opposing main housing assembly side walls (8065, 8070) and / or integrally formed with the fuel input manifold (8015) in a manner that provides the desired mechanical interface. Figure 7A In a non-limiting second embodiment, when the fuel input manifold (8015) is configured to extend along the lower boundary of the cathode chamber (8055) along the full length of the stack length axis (x), and in some cases further beyond the full stack length, the hot zone housing base wall (8075) is optional. Preferably, the mechanical interface between the two opposing main housing assembly side walls (8065, 8070) and the fuel input manifold (8015) forms a gas seal at the lower boundary of the cathode chamber (8055) or provides a high impedance to gas flow to prevent cathode gas flow from escaping from the lower boundary of the cathode chamber (8055).

[0175] 4.12.2 Intermediate casing

[0176] The hot zone shell wall assembly (8042) is installed inside the intermediate shell (9000). Figure 8AThe intermediate housing is or can be formed into an airtight gas flow chamber, which includes opposing intermediate housing top walls (9005) and intermediate housing bottom walls (9010), opposing intermediate housing side walls (9015) and intermediate housing side walls (9020), and opposing intermediate housing end walls (9025) and intermediate housing end walls (9030). The intermediate housing (9000) includes a fuel access port (9035), a cathode input port (9040), and a hot zone exhaust port (9045). The fuel access port (9035) is used to receive a fuel delivery pipe (8040) through the fuel access port (9035); the cathode input port (9040) is used to receive a cathode air flow through the cathode input port; and the hot zone exhaust port (9045) is used to exhaust exhaust gas therefrom. Each of the ports (9035), (9040), and (9045) passes through the wall of the intermediate housing as needed to guide the appropriate air flow interface. In a non-limiting exemplary embodiment, the fuel port passes through one of the side walls (9015, 9020) and each of the cathode gas input port (9040) and the hot zone exhaust port (9045) passes through the intermediate housing top wall (9005).

[0177] exist Figure 7A The recuperator chamber (9050) and the hot zone exhaust duct (9055) shown in FIG are each a gas flow chamber formed inside the intermediate housing (9000) and together form a counter-current gas-to-gas heat exchanger. The recuperator chamber (9050) receives the cathode air flow from a source (e.g., Figure 1 The cathode air flow is directed through the cathode input port (9040) by the air delivery control element (198) shown. Inside the recuperator chamber (9050), the incoming cathode air flow (e.g., ambient temperature air) is heated by convection and by radiation emitted from the walls of the hot zone exhaust duct (9055). The heated cathode air flow is forced through the recuperator chamber (9050) and exits the recuperator chamber through the recuperator outlet port (9065) to the cathode input manifold (9070). The cathode air flow source includes a variable speed air moving device (e.g., a fan or blower) that can be controlled to increase or decrease the flow rate of the incoming cathode air flow based on electrical output requirements and other operational control commands.

[0178] The hot zone exhaust duct (9055) receives the hot gas mixture from the combustion zone (8030) through the combustion exhaust port (9060). Within the hot zone exhaust duct (9055), the hot gas mixture is cooled as energy is transferred convectively and radiatively to the walls of the hot zone exhaust duct (9055). The hot gas mixture is forced through the combustion exhaust channel (9060) and out of the SOFC system through the hot zone exhaust port (9045) by operation of a controllable variable speed air moving device (e.g., a fan or blower) to increase or decrease the flow rate of the incoming cathode gas flow.

[0179] exist Figure 7A In a non-limiting exemplary configuration, a recuperator chamber (9050) is formed inside the hot zone exhaust duct (9055) and the two chambers share a common wall (9075). When the high temperature gas mixture is forced from the combustion zone (8030) into the hot zone exhaust duct (9055), the high temperature gas mixture transfers heat energy to the common wall (9075) by radiation emission and convection. The common wall (9075) then transfers heat energy to the cathode air flow passing through the recuperator chamber (9050) by convection and radiation emission therefrom. Other gas-to-gas heat exchange configurations are available without departing from the present technology, including providing multiple heat exchange chambers connected in series or parallel.

[0180] Each of the recuperator chamber (9050) and the hot zone exhaust duct (9055) is preferably arranged along the length of the SOFC stack along the stack length axis (x). Each of the cathode input port (9040) and / or the hot zone exhaust port (9045) and / or the combustion exhaust port (9060) can be implemented as a single port, a plurality of ports (e.g., spaced apart along the stack length axis (x)), and / or one or more openings (e.g., circular, slot-shaped, or other openings formed to provide a gas flow channel) arranged along the stack length axis (x). Alternatively, each of the recuperator chamber (9050) and the hot zone exhaust duct (9055) can be implemented as a single recuperator chamber and a single exhaust chamber extending along the stack length axis (x), or as a plurality of separate recuperator and exhaust chambers arranged in parallel along the stack length axis (x), wherein each separate chamber is provided with its own cathode input port (9040) and / or the hot zone exhaust gas port (9045).

[0181] In a preferred embodiment, each wall portion of the intermediate housing (9000) is made of ferritic stainless steel, such as Alloy 18 Stainless steel, etc., such as distributed by Rolled Metal Products, Alsip, Illinois, USA. Alloy18 Stainless steel is preferred because at the operating temperatures and conditions of the SOFC system (8000), the added aluminum content advantageously forms a surface layer of aluminum oxide that prevents oxidation of the exposed surfaces of the intermediate housing (9000), which further prevents chromium from being removed from the Alloy 18. In a non-limiting example, Alloy 18 Stainless steel has the following chemical composition in approximate weight percentages: carbon 0.015, chromium 18.0, manganese 0.30, silicon 0.60, aluminum 2.0, titanium 0.25, and the remainder iron. Stainless steel has a thermal conductivity of approximately 22.8 (W / m°K) and a -6 (Ft / Ft / °F) or 10.1x10 -6 (m / m / °K) thermal expansion coefficient. At least for the surrounding intermediate shell wall (9005, 9010, 9015, 9020, 9025, 9030), Alloy18 The preferred thickness of the stainless steel is 4 mm (0.16 inches); however, a thickness range of 0.127 mm to 8.0 mm (0.005 inches to 0.32 inches) is available and may depend on the shape and size of the intermediate shell (9000), the forming method used to form the intermediate shell (9000), the availability of standard rolled stock thicknesses, the desired operating life in hours, etc. without departing from the present technology.

[0182] Regarding material selection, the walls surrounding the intermediate housing walls (9005, 9010, 9015, 9020, 9025, 9030) can have a different thickness than the walls forming the hot zone exhaust duct (9055), the recuperator chamber (9050), the baffles (9080), and the various ports (9040, 9045, 9060), as the selection of wall thickness can depend on the wall operating temperature requirements, the desired operating life of the SOFC system, thermal energy management requirements, and / or structural and manufacturing technology differences from one SOFC system to another. In an alternative exemplary embodiment, at least a portion of the walls of the intermediate housing (9000) can include a chromium-free high-temperature metal alloy, such as monel, which is a nickel-copper alloy with small additions of aluminum and titanium.

[0183] 4.12.3 Cathode Input Manifold

[0184] Reference Figure 7A 、 Figure 8AThe intermediate housing (9000) is formed as a cathode gas flow chamber, which includes a recuperator chamber (9050) and a cathode input manifold (9070). The cathode input manifold receives an incoming cathode air flow from the recuperator chamber, which fills the cathode input manifold (9070). The hot zone housing assembly (8042) is mounted inside the cathode input manifold (9070), and the U-shaped main housing wall assembly (8045) separates the cathode input manifold from the cathode chamber (8055), except that the cathode gas flow can be passed from the cathode input manifold to the cathode chamber through a plurality of cathode chamber input ports (8095) located proximate to the open fuel input end (8020) of each of the plurality of SOFC fuel cells to direct the cathode gas flow into the bottom volume of the cathode chamber so that the cathode gas flow inside the cathode chamber passes along the gas flow axis (z) through the entire length of the cathode of each fuel cell. The cathode input manifold (9070) is defined by the inwardly facing surface of each of the intermediate housing bottom wall (9010), the intermediate housing side walls (9015, 9020), the intermediate housing end walls (9025, 9030), the outwardly facing surface of the bottom wall (9059) of the hot zone exhaust duct (9055), and the outwardly facing surface of the U-shaped main housing wall assembly (8045). The cathode input manifold (9070) receives a heated cathode air flow from the recuperator outlet port (9065). Inside the cathode input manifold (9070), as the heated cathode air flow is received from the recuperator outlet port (9065), the heated cathode air flow is supplied by the cathode air flow from the U-shaped main housing wall assembly (8045) and the intermediate housing walls (e.g., at the bottom wall). Figure 8A The cathode air is further heated by radiation emitted by (9005, 9010, 9015, 9020, 9025, 9030) shown in Figure 1, and further heated by convection due to the movement of the cathode air flow through the cathode input manifold. The cathode air flow exits the cathode input manifold (9070) and enters the cathode chamber (8055) through one or more cathode chamber input ports (8095), passing from the cathode input manifold (9070) to the lower volume (8142) of the cathode chamber (8055). In a preferred embodiment, multiple cathode chamber input ports (8095) pass through each of the main housing side walls (8065, 8070) near its bottom edge. Once inside the cathode chamber (8055), the preheated cathode air flows upward from the cathode chamber input ports (8095) to the cathode chamber middle volume, where the cathode air reacts with the outer surface of the fuel cell to promote the SOFC reaction. The preheated cathode air then reaches the combustion zone (8030) where the spent cathode air is mixed with the spent fuel and the mixture is combusted.

[0185] exist Figure 7A, the cathode air flow through the SOFC system (8000) is shown as indicated by the black solid line with black arrows showing the direction of the cathode air flow and its path. The input cathode air flow is received from the air delivery module (198), which includes a variable speed fan or other air moving device and a corresponding air flow rate delivery controller. The cathode air flow is passed from the air delivery module (198) to the cathode input port (9040) to the recuperator chamber (9050) and exits the recuperator chamber through the recuperator outlet port (9065) to the cathode input manifold (9070). From the cathode input manifold (9070), the air flow is passed through the cathode flow channel (8095) into the cathode chamber lower volume (8142), then passes over the cathode electrode surface of each individual fuel cell (8010), and then mixes with the waste fuel exiting from the fuel output end (8025) of each individual fuel cell (8010). The spent fuel and spent cathode air are burned within the combustion zone (8030), further heating the main housing wall assembly (8045). The hot gas mixture of the combustion passes from the combustion zone (8030) to the hot zone exhaust duct (9055) and passes through the combustion exhaust port (9060), and then flows out of the system through the hot zone exhaust port (9045).

[0186] exist Figure 7AAlso shown is the fuel flow through the SOFC system, indicated by black dashed lines and arrows, showing the direction of the fuel flow and its path. A supply of hydrogen-rich fuel mixed with air is received from a fuel delivery control system (197), which includes a variable speed fan, a pressure regulator, an atomizer or other gas or fluid flow rate regulator device and a corresponding fuel delivery flow rate controller. The fuel flow is passed from the fuel delivery control system to a fuel reformer (8035), where the fuel reformer (8035) reforms the supply fuel to provide a fuel, typically a reformate containing hydrogen, carbon monoxide, and carbon dioxide. From the fuel reformer (8035), the fuel flows through a fuel delivery conduit (8040) to a fuel input manifold (8015). Inside the fuel input manifold, the fuel is heated by radiation and convection as it flows through the walls of the input fuel manifold (8015). Fuel flows from the fuel input manifold (8015) into the hollow chamber of each individual fuel cell (8010), where it passes over the anode electrode surface of the fuel cell, thereby participating in the SOFC reaction. The fuel leaves each individual fuel cell through the open output end (8025) and reaches the combustion zone (8030), where the spent fuel is mixed with the spent cathode air. The spent fuel and spent cathode air are burned in the combustion zone (8030). The burned hot gas mixture is transferred from the combustion zone (8030) to the hot zone exhaust duct (9055) through the combustion exhaust port (9060), and then flows out of the system through the hot zone exhaust port (9045). The heat energy generated by the combustion of the spent syngas and spent cathode air mixture is transferred to the inner surface (8045) of the U-shaped main housing wall assembly. The fuel delivery control system (197) and the cathode air delivery module (198) can both be operated independently to change the flow rate as needed, for example, by changing the fuel flow rate to adjust the current output, or by changing the air flow rate to adjust the stack temperature.

[0187] 4.12.4 Heat flow and air flow diagrams

[0188] Figure 7BThe heat energy flow diagram shown in depicts the non-restrictive heat energy transfer mode enabled by the present technology. The solid black line with black arrows points inward from the wall surface to the cathode or fuel flow area, indicating the radiation emission from the higher temperature wall surface to the lower temperature air flow or to the lower temperature surface of other walls (such as the wall of the intermediate shell (9000)). Although not indicated by the flow arrows, because the high temperature gas volume near the higher temperature wall surface mixes with the cooler gas volume away from the high temperature surface, convective heat flow from the high temperature fluid / gas flow to the lower temperature fluid / gas area occurs in each air flow. The flow of cathode gas is indicated by the black solid line with black solid arrows. The flow of anode gas is indicated by the black dashed line with black solid arrows. As noted above, the fuel and cathode gas streams each enter the cathode chamber (8055) near the input end (8020) of each fuel cell and flow upward toward the combustion zone (8030), where the spent fuel gas and spent cathode gas are mixed and combusted before exiting the cathode chamber to the recuperator chamber (9050) through the combustion exhaust port (9060). Furthermore, the black dashed lines with solid black arrows shown within the heat conductive core (8200) of the U-shaped main housing wall assembly (8045) described below indicate the direction and path of heat conduction along the heat conductive path provided thereby. As shown, the direction of heat conduction provided by the heat conductive core (8200) is from the high temperature combustion zone wall portion (8060) toward the end of each side wall (8065, 8070).

[0189] The incoming cathode air stream enters the recuperator chamber (9050) at ambient temperature and as the cathode air stream is heated by heat exchange between the higher temperature common wall (9075) and the lower temperature incoming cathode air stream, the temperature of the cathode air stream increases, as indicated by the arrows pointing from the common wall (9075) into the recuperator chamber (9050). Inside the cathode input manifold (9070), as the cathode air stream is heated by heat exchange between the higher temperature U-shaped main housing wall assembly (8045) and the lower temperature cathode air stream, the temperature of the cathode air stream further increases, as indicated by the arrows pointing from the outer surface of the U-shaped main housing wall assembly (8045) into the cathode input manifold (9070). In addition, each of the intermediate housing walls (9005, 9010, 9015, 9020, 9025, 9030) is heated by radiation emission from the higher temperature U-shaped main housing wall assembly (8045) and by heat exchange with the cathode air stream. Whenever the temperature of the intermediate housing wall is higher than the temperature of the cathode air stream, the cathode air stream is further heated by heat exchange between the intermediate housing wall and the cathode air stream. Alternatively, when the temperature of the intermediate housing wall is lower than the temperature of the cathode air stream, such as during a startup cycle, the intermediate housing wall is heated by heat exchange between the higher temperature cathode air stream and the intermediate housing wall.

[0190] Within the cathode chamber (8055), the temperature of the cathode air stream is further increased by heat exchange between the inner surface of the U-shaped main housing wall assembly (8045), the outer surface of the individual fuel cells (8010), and the surfaces of the input fuel manifold (8015) and the cathode air stream, wherein the direction of heat flow is from a higher temperature surface or higher temperature gas flow area to a lower temperature surface or gas flow area, as indicated by the arrows directed from the surfaces and cathode air streams listed above. Thus, the temperature of the cathode air stream continues to increase as it flows through the cathode chamber from the cathode chamber flow channel (8095) toward the combustion zone (8030).

[0191] In a non-limiting example operating mode, before a steady-state SOFC reaction occurs and a direct current can be maintained output from the SOFC stack (8005), the temperature of the gas mixture in the combustion zone (8030) and within at least a portion of the anode surface within the cell is at least 350°C. Once a steady-state SOFC reaction is established, the temperature of the gas mixture in the combustion zone (8030) can exceed 500°C. Thus, the gas mixture has a temperature that is much higher than the temperature of the incoming cathode air flow and higher than the surrounding walls of the hot zone exhaust duct (9055) while passing from the combustion zone (8030) through the hot zone exhaust duct (9055) to the hot zone exhaust port (9045). Thus, the temperature of the gas mixture decreases while passing through the hot zone exhaust duct (9055) because heat is transferred by heat exchange between the higher temperature exhaust gas and the walls of the hot zone exhaust duct (9055), including the common wall (9075). The heated walls of the hot zone exhaust duct (9055), particularly the common wall (9075), cause heat exchange with the cooler incoming cathode air as it flows through the recuperator chamber (9050).

[0192] See again Figure 7BThe incoming fuel-air mixture enters the fuel reformer (8035) at ambient temperature and is heated by the catalytic partial oxidation (CPOX) reactor or partial combustion in the fuel reformer (8035). During the CPOX reaction, the temperature of the fuel can peak at around 1200°C. Therefore, the temperature of the fuel exiting the fuel reformer (8035) decreases as the fuel passes from the fuel reformer through the fuel conduit (8040) and the fuel input manifold (8015) and through each fuel cell from the fuel input end (8020) to the fuel output end (8025). Thus, during steady-state operation, after the SOFC reaction that produces output current has been established, the temperature of the fuel stream may continue to decrease along the flow path extending from the fuel reformer (8035) to the input fuel manifold (8015), and then as the fuel stream passes from the input fuel manifold to the combustion zone (8030), the temperature of the fuel stream may increase or decrease as heat flows from the fuel stream through heat exchange to lower temperature surfaces of the surrounding fuel channels (including the walls of the fuel input manifold (8015) and the walls of the fuel cell (8010) that increase in temperature due to heat absorption from the fuel stream). In some embodiments, the direction of heat exchange may change, for example, when the temperature of the fuel stream becomes less than the temperature of the inner walls of the fuel cell. As described above, the temperature of the gas mixture from the combustion zone (8030) continues to decrease as the gas mixture flows out of the SOFC system.

[0193] See again Figure 7B , the black dashed line with black arrows shows the direction and path of heat energy transfer from the high temperature area of ​​the heat conductive core to the low temperature area of ​​the heat conductive core by heat conduction. The heat conductive core passively reduces the thermal gradient between the core top portion (8215) and each core side wall (8205), (8210). The core top portion defines the combustion zone (8030), which, as described above, has a temperature of at least 350°C and reaches approximately 1200°C. The gas mixture within the combustion zone has a higher temperature than the surrounding surface, so that heat flows from the gas mixture to the combustion zone wall (8060) by forced thermal convection, and radiation absorbed by the combustion zone wall is transferred to each side wall (8065, 8075) by heat conduction, as will be described below.

[0194] 4.12.5 U-shaped hot zone shell assembly

[0195] Now see Figure 7A 、 Figure 9A 、 Figure 9B and Figure 9CThe hot zone housing assembly (8042) includes an SOFC stack (8005), a fuel input manifold (8015), and a U-shaped main housing wall assembly (8045). Optionally, the hot zone housing assembly (8042) further includes a hot zone housing base wall (8075), a first hot zone housing end wall (8080), and a second hot zone housing end wall (8085). The U-shaped main housing wall assembly (8045) includes a combustion zone wall portion (8060), a first main housing side wall (8065), and a second main housing side wall (8070), both of which are joined to the combustion zone wall portion.

[0196] Each main housing wall portion (8060), (8065) ​​and (8070) includes a thermally conductive core (8200) and is protected from oxidation by an outer layer applied to its exposed surface. The thermally conductive core (8200) includes one or more materials having a thermal conductivity greater than 100 W / (m°K), preferably greater than 200 W / (m°K). In a non-limiting exemplary embodiment, the one or more thermally conductive core materials include copper, molybdenum, aluminum, beryllium, iridium, rhodium, silver, tungsten, or an alloy or combination, so that it can be manufactured to have the desired thermal conductivity and can reliably meet the structural requirements at the operating temperature of the hot zone. In a preferred embodiment, the thermally conductive core (8200) includes copper or a copper alloy having a thermal conductivity of 370 (W / m°K) at 500°C and a thermal conductivity of 332 (W / m°K) at 1027°C as described above. The thermally conductive core (8200) preferably has a thickness in the range of 0.127 mm to 3.2 mm (0.005 inch to 0.125 inch); however, other thicknesses, such as 0.5 mm to 6.0 mm (0.02 inch to 0.24 inch), may be used without departing from the present technology. The core thickness may be increased or decreased as needed to meet design requirements. Thicker thermally conductive cores (8200) (e.g., up to 6.0 mm (0.24 inch or greater)) require more thermal energy to heat the core material to the desired operating temperature; however, increasing the core thickness is beneficial because it increases the rate of thermal energy transfer from one area of ​​the core to another, which advantageously redistributes thermal energy more quickly. If surface oxidation is a possible failure mode, other reasons for increasing the core thickness would be to conduct thermal energy over a longer distance or to achieve a longer operating life. As will be appreciated, the thicker the thermally conductive core (8200), the longer it will take for the thicker walls to oxidize to the point where the core becomes unusable. Furthermore, aluminum may be used as a core material in a SOFC system capable of generating electricity when the SOFC system is capable of generating electricity without subjecting the core material to temperatures exceeding about 550°C.

[0197] The thermal core (8200) is a passive element that emits and absorbs radiation in proportion to the fourth power of the absolute temperature difference (°K) between the thermal core and its surroundings, based on the standard blackbody principle. Furthermore, thermal energy is transferred to and from the thermal core by thermal conduction from other surfaces of the U-shaped main housing wall assembly (8045) in thermal contact. When a thermally conductive path exists and a temperature difference exists between regions of the thermal core, thermal energy is further transferred by conduction from one region of the thermal core to another region of the thermal core.

[0198] In a first non-limiting exemplary embodiment, the thermally conductive core (8200) is a monolithic element shaped to encapsulate the SOFC stack (8005) and form a cathode chamber (8055) around the stack. The monolithic element is formed from a flat sheet of the core material described above, sized to include three main housing wall portions (8060), (8065), (8070), and bent to form Figure 9C As will be appreciated, the U-shaped core element (8200) can be formed by a metal bending jig configured to bend a flat sheet of metal into a desired U-shape. Other shapes, for example, rectangular shaped core elements, may be used without departing from the present technology.

[0199] In a second non-limiting exemplary embodiment, the thermally conductive core (8200) includes three separate core sections (8205, 8210, 8215), each of which includes one or more of the core materials described above and each having a wall thickness within the thickness ranges described above. The three separate core sections include two substantially identical side sections (8205), (8210) and a core top wall section (8215). The core top wall section (8215) is formed with a cylindrical radius along its longitudinal length, and each side section (8205), (8210) is formed from a flat sheet of metal. Preferably, the longitudinal dimension along the stack length axis (x) is the same for all three separate core sections. The three separate core sections (8205, 8210, 8215) are joined together, for example, by a soldered joint, by a brazed joint, by a welded joint, and / or by other mechanical joining techniques, such as by rolling or pressing the mating edge of each side wall with the corresponding mating edge of the core top wall section (8215), by cladding sheets of dissimilar metals together along the joint between the core section mating edges, or by otherwise fastening the core section mating edge of each side wall with the corresponding core section edge of the core top section (8215). Regardless of the fastening or joining method, the mechanical interface between the three separate core sections provides a thermally conductive path between the core top section (8215) and each of the two side core sections (8205), (8210), and preferably the thermally conductive path is along the entire longitudinal length and thickness of the joined core wall sections.

[0200] To prevent oxidation of the thermally conductive core (8200), each core portion (8205, 8210, 8215) is protected by a protective layer applied to or attached to the exposed surface of the thermally conductive core (8200). In a first non-limiting exemplary embodiment, the protective layer comprises nickel plating applied by an electroplating process to a thickness of at least 0.0005 inches and extending to 0.002 inches or greater. The nickel plating is applied to prevent oxygen from diffusing through it at operating temperatures of 350°C to 1200°C. In a second non-limiting exemplary embodiment, the protective layer comprises an anodized surface formed above the exposed core material. The anodized surface can be formed in a pre-assembly controlled electroplating or oxygen-rich environment, or the anodized surface can be formed by exposing the protective layer surface to oxygen (i.e., cathode air flow over time during operation of the SOFC system). In a non-limiting exemplary embodiment, when the core material comprises aluminum or an aluminum-copper alloy, the anodized surface is formed directly on the core material surface. When the anodized surface is formed by electroplating or an oxygen-enriched anodizing process in a pre-assembly controlled environment, the desired thickness of the anodized layer is preferably 0.0005 inches, but in some applications ranges up to about 0.002 inches to prevent oxygen from diffusing through the anodized surface at operating temperatures of 350° C. to 1200° C. Regardless of the electroplating process or other type of anodized layer application, the thickness of the protective layer will depend on the expected operating life of the SOFC system or thermal core, based on the average and / or peak operating temperatures near the thermal core, and the oxidant concentration and / or oxidation rate to which the coating will be exposed based on the thickness of the coating.

[0201] In a third non-limiting exemplary embodiment, the protective layer comprises one or more metal sheets arranged to engage with the exposed surface of each of the three core sections (8205), (8210), and (8215). The metal sheets may be applied directly to the uncoated surface of the thermally conductive core or may be applied to the electroplated surface of the thermally conductive core. However, as described above, the electroplated nickel layer may be used as the protective layer without the metal sheets. Figure 9CAs shown in the exploded isometric view of , the inner protective sheet metal layer (8220) is manufactured into a U-shaped structure that is formed to be attached to the inner surface of each of the three core sections (8205), (8210), (8215), wherein the inner surface of the inner protective layer (8220) faces the SOFC stack. Preferably, the outer surface of the inner protective layer (8220) facing away from the SOFC stack and the inner surfaces of the three core wall sections (8205, 8210, 8215) are in contact and fit over the entire inner surface area of ​​the three core wall sections. The inner protective layer (8220) may extend beyond a portion of the U-shaped thermally conductive core (8200), for example, when the longitudinal length of the inner protective layer (8220) along the longitudinal length axis (x) of the stack extends beyond the longitudinal length of the thermally conductive core (8200), or when the dimension of the inner protective layer along the gas flow axis (z) is greater than the dimension of the thermally conductive core along the same axis, such as Figure 9C As shown, the bottom edges (8240, 8245) of the inner protective layer (8220) each extend to mate with the hot zone housing base wall (8075) or other mechanical interface surface (such as may be provided by the fuel input manifold (8015). Similarly, the side edges of the inner protective layer (8220) may extend beyond the side edges of all three core sections (8205), (8210), (8215), for example, to mate with the hot zone housing end walls (8080), (8085) and / or extend the length of the cathode chamber (8055) along the longitudinal axis (x) of the stack. The inner protective layer (8220) includes: an inner top portion (8225) and two opposite inner side wall portions (8230), (8235), the inner top portion (8225) being formed with a cylindrical radius along the stack length axis (x); each of the two opposite inner side wall portions (8230), (8235) extending from a different edge of the cylindrical radius of the inner top portion (8225).

[0202] Each of the inner protective layer side wall portions (8230), (8235) is attached to the hot zone housing base wall (8075), such as by a mechanical interface between the inner side wall bottom edge (8240), (8245) and the main housing base wall (8075) joined along the entire interface, such as by welding, soldering, or other mechanical interface configured to be gas-tight or provide high resistance to gas flow. The hot zone housing base wall (8075) is also attached to the intermediate housing (9000) at its bottom wall (9010) and / or side and end walls (9015, 9020, 9025, 9030) such that the mechanical interface between the inner side wall bottom edge (8240), (8245) and the main housing bottom wall fixedly supports the U-shaped main housing wall assembly (8045) inside the intermediate housing (9000). Alternatively, each of the inner protective layer side wall portions (8230), (8235) is directly attached to the intermediate housing bottom wall (9010) via a mechanical interface between the fixedly attached inner side wall bottom edge (8240), (8245) and the intermediate housing bottom wall (9010), such as by welding, brazing, soldering, or other mechanical interface. Alternatively, each side wall portion (8230), (8235) is attached to the fuel input manifold (8015) via a mechanical interface between the inner side wall bottom edge (8240), (8245) and the fuel input manifold (8015), the inner side wall bottom edge and the fuel input manifold being fixedly attached, such as by welding, brazing, soldering, or other mechanical interface. In this embodiment, the fuel input manifold (8015) is attached to the intermediate housing bottom wall (9010) or other intermediate housing wall so that the mechanical interface between the inner sidewall bottom edge (8240), (8245) and the fuel input manifold (8015) fixedly supports the U-shaped main housing wall assembly (8045) inside the intermediate housing (9000). Regardless of the attachment technique, the mechanical interface between the inner sidewall bottom edge (8240), (8245) and the hot zone housing base wall (8075), or between the inner sidewall and the input fuel manifold (8015), or between the inner sidewall and the intermediate housing bottom wall (9010) preferably provides a gas seal or provides high impedance to gas flow corresponding to the lower boundary of the cathode chamber (8055). In a preferred embodiment, each inner protective layer sidewall portion (8230), (8235) includes a plurality of cathode chamber input ports (8095), the cathode chamber input ports (8095) extending through the inner sidewall portion extending below and proximate to the bottom edge (8240), (8245) of the thermal core sidewall (8205), (8210), and the input ports (8095) are evenly spaced along the stack length axis (x). The position of the cathode chamber input ports (8095) along the air flow axis (z) is selected to deliver cathode air into the lower volume (8142) of the cathode chamber (8055) proximate to the fuel input end (8020).Alternative cathode chamber input port embodiments include a single slotted opening and / or multiple holes of various opening shapes, such as circular, oval, square, rectangular, etc. Alternatively, the cathode chamber input port (8095) may pass through the inner sidewalls (8230, 8235) and the core sidewalls (8205, 8210) when the inner surface of the cathode chamber input port (8095) is protected from oxidation (e.g., by plating or an insert configured to prevent oxidation).

[0203] The outer protective layer (8250) includes two substantially identical outer sidewall portions (8255), (8260) and an outer top portion (8265). Figure 9C As shown in the exploded isometric view of FIG, the three outer protective layer portions, when joined together and with the respective outer surfaces of the thermally conductive core (8200), form a U-shaped sheet metal structure shaped to attach to the outer surface of the thermally conductive core (8200) and protect the outer surface of the thermally conductive core from exposure to the oxygen-rich cathode air flow (e.g., flowing through the cathode air input manifold (9070)). Preferably, the inner surface of the outer protective layer (8250) is in contact with the respective outer surface of the thermally conductive core (8200) facing away from the SOFC stack. The outer protective layer top wall portion (8265) is formed to have a cylindrical radius along the stack length axis (x), wherein the inner radius of the cylindrical radius of the outer protective layer top wall portion (8260) matches the outer radius of the cylindrical radius of the thermally conductive core top portion (8215) so that when the inner and outer radii are joined together, they provide a contact fit therebetween. The outer protective layer sidewall portions (8255), (8260) are each formed from a flat sheet metal blank that is cut to have a height dimension along the airflow axis (z) and a length dimension along the longitudinal axis (x) of the stack. The height dimension of each sidewall portion (8255, 8260) is selected to position the outer sidewall bottom edge (8270), (8275) below or mate with the corresponding bottom edge of the thermally conductive core sidewall portion (8205), (8210). When the cathode flow path (8095) only passes through the inner sidewalls (8230, 8235), the height dimension of the outer sidewalls (8255, 8260) is sufficiently short to prevent the outer sidewalls from covering the cathode flow path (8095). In other embodiments, the cathode flow channel (8095) can pass through the outer sidewalls (8260, 8255), the core sidewalls (8205, 8210), and the inner sidewalls (8230, 8235). Preferably, the inner surface of the outer sidewall (8255, 8260) and the outer surface of the core sidewall (8205, 8210) are in contact fit after assembly.

[0204] In a preferred embodiment, each wall portion of the inner protective layer and the outer protective layer is made of ferritic steel (such as Alloy 18 Stainless steel, etc.), such as those distributed by Rolled Metal Products of Alsip, Illinois, USA. Stainless steel is preferred because at the operating temperatures and oxygen-rich conditions of the SOFC system (8000), the added aluminum content responds to oxygen exposure to advantageously form a surface layer of aluminum oxide, which prevents further oxidation of the exposed surfaces of the inner and outer protective layers and prevents chromium from being removed from the Alloy 18. Leaching in stainless steel. Alloy18 The preferred thickness of the stainless steel is 4 mm (0.16 inches); however, a thickness range of 0.13 mm to 6.0 mm (0.005 inches to 0.24 inches) is useful and may depend on the shape and size of the inner and outer protective layers, the formation methods used to form the inner and outer protective layers, the availability of standard rolled stock thicknesses, the desired operating life in hours, etc., without departing from the present technology. In another exemplary embodiment, the inner and outer protective layers at least partially comprise a chromium-free high-temperature metal alloy (such as monel, etc.), which is a nickel-copper alloy with minor additions of aluminum and titanium. The preferred thickness of each wall portion is approximately 4 mm (0.16 inches); however, the actual thickness may be in the range of 0.13 mm to 6.0 mm (0.005 inches to 0.24 inches) without departing from the present technology.

[0205] The hot zone housing base wall (8075) and each hot zone housing end wall (8080, 8085) may optionally include a heat conductive core portion (8200) and two protective layer portions, the two protective layer portions including an inner protective layer (8280) and an outer protective layer (8285), e.g. Figure 8B As depicted in the cross-sectional view in . As with the other protective layers described herein, the inner and outer protective layers (8280, 8285) may comprise a nickel plating layer applied to the exposed surface of the thermally conductive core, or the thermally conductive layer may be protected by the inner and outer protective layers of the sidewalls (8230, 8235, 8255, 8260) as described above, which are configured to form an anodized layer prior to assembly or formed by exposure to cathode air during operation of the SOFC system. As described above, the surface of the thermally conductive core (8200) is protected by an electroplating process in which nickel is applied to a thickness of at least 0.0005 inches and in a range extending to 0.002 inches or greater, and / or by a process having a thickness of 4 mm (0.16 inches) or a thickness in the range of 0.13 mm to 6.0 mm (0.005 inches to 0.24 inches) including Alloy 18 Attachment protection for stainless steel sheet metal.

[0206] The thermally conductive core portion (8200) and the protective layer portions (8280), (8285) are configured similarly to the main housing walls (8060), (8065), and (8070) described above, wherein the thermally conductive core portion (8200) is protected from oxidation by the two protective layer portions (8280), (8285). The thermally conductive core portion (8200) comprises one or more materials having a thermal conductivity greater than 100 W / (m°K) and preferably greater than 200 W / (m°K).

[0207] More generally, choose Figure 9C The above-mentioned protective layers (8250, 8220) and Figure 8B Each of the above-described protective layers (8280, 8285) shown in FIG, and the nickel plating layer and / or the anodized layer applied by the electroplating process are selected to provide a stable protective outer layer that is capable of preventing oxygen from diffusing through the stable protective outer layer. Preferably, the stable protective layer does not include chromium; however, the stable protective layer preferably prevents chromium from leaching through the stable protective layer. Exemplary stable protective outer layer materials include aluminum oxide, titanium oxide, or other suitable oxides or passivation layers.

[0208] Figure 9A The hot zone housing assembly (8042) shown is equipped with Figure 1 A start-up fuel input conduit (8145) is shown in fluid communication with a fuel delivery control module (197) for delivering a start-up fuel flow (8152) into the start-up fuel input conduit (8145), which is in fluid communication with a burner element (8155) passing through a combustion zone (8030). Figure 7A The fuel igniter element (8160) shown in the figure extends into the combustion zone (8030) and is used to ignite the startup fuel flow (8152) as the startup fuel flow (8152) exits the burner element (8155) inside the combustion zone during a cold start cycle to quickly increase the temperature of the U-shaped main housing wall assembly (8045) and the SOFC stack (8005). The startup fuel flow (8152) includes a mixture of hydrogen-rich fuel and unreformed air or unreformed hydrocarbon-rich gas (such as propane). During a cold start of the SOFC system, the fuel delivery control module (197) can deliver the startup fuel flow (8152) directly to the burner element (8155) and use the igniter element (8160) to ignite the fuel discharged from the burner element (8155). In addition, Figure 1The air delivery module (198) shown in the figure can deliver the air flow to the recuperator chamber (9050) to be heated before passing through the cathode input manifold (9070) and the cathode chamber (8055) and then to the combustion area (8030). When the U-shaped main housing wall assembly (8045) and the SOFC stack (8005) reach a predetermined startup temperature, the fuel delivery control module can deliver the startup fuel flow (8152) to the burner element (8155) and supply the fuel flow (8050) to the fuel reformer (8035) to start the fuel (8150) flowing through the SOFC stack (8005) while the hot air flow moves through the cathode chamber to ultimately start the SOFC reaction.

[0209] 4.12.5.1 Shell wall assembly manufacturing process:

[0210] In a first non-limiting exemplary manufacturing process, each of the inner protective layer (8220) and the heat conductive core (8200) is formed as a whole flat sheet of suitable materials as described above. Each flat sheet is cut into predetermined finished dimensions corresponding to the finished dimensions of the inner protective layer and the heat conductive core. While the whole flat sheet is still a flat sheet, any additional processing of either sheet is preferably completed. The additional processing includes at least drilling, punching or otherwise forming the cathode chamber input port (8095) through the inner protective layer (8220) (or the inner protective layer and the core), and adding other holes or formed features as may be needed to provide mechanical interface elements for attaching the inner protective layer bottom edge (8240, 8245) to the hot zone housing base wall (8075), or attaching the inner protective layer bottom edge (8240, 8245) to the input fuel manifold (8015) and / or attaching the inner protective layer bottom edge (8240, 8245) to the intermediate housing (9000). Additional holes or features that may be required to provide other mechanical interface features are also added before assembling the U-shaped main shell wall assembly (8045), such as for attaching the inner protective layer (8220) to the hot zone shell end wall (8080, 8085) or for attaching the inner protective layer (8220) or the outer protective layer (8250) to the thermal core (8200) or for providing a fuel or cathode air flow port (such as a combustion exhaust port (9060), or for providing an inlet to the fuel delivery pipeline (8040)), or for providing a fuel pipeline to the combustion area for use during cold start, or for providing an access port for an electrical interface for a sensor attachment point, etc.

[0211] After preparing the flat sheets for assembly, including electroplating, machining, stamping, etc., the inner protective layer (8220) and the thermally conductive core (8200) are joined together in a plane, such as by aligning and clamping the two sheets in contact with each other, and joining the two sheets together to form a composite sheet metal structure that is still a flat sheet. Joining techniques may include welding, brazing, soldering, fastening (e.g., riveting, self-riveting, or self-riveting) by folding tab joints, etc.

[0212] In the case where either sheet material is a rolled sheet, the grain direction extends parallel to the rolling direction. Therefore, the rolling direction of each sheet should be identified before the sheets are cut and assembled together, and if the sheets are to be bent, consideration should be given to orienting the grain direction relative to the bending axis. Furthermore, the grain direction of the thermally conductive core may have a different thermal conductivity relative to other axes of the core material. Therefore, the thermally conductive core should be oriented in such a way that the axis of highest thermal conductivity is directed from the core top portion (8215) toward the bottom edge of the core sidewalls (8205, 8210).

[0213] Then, the composite sheet including the heat conductive core (8200) and the inner protective layer (8220) joined together in contact fit is bent to form Figure 9C The U-shaped structure shown in FIG, wherein the inner protective layer is positioned facing the SOFC stack. The cylindrical radius has a longitudinal axis along the stack longitudinal axis (x). In a non-limiting exemplary embodiment, the bend radius is formed by a hydraulic bending device operable to bend or form the composite sheet metal structure on a press breaker or the like at room temperature (air bending). The bend radius that can be bent without damaging the material and managing undesirable consequences (such as springback) is affected by material properties (e.g., hardness, tensile strength, material thickness, material grain orientation, etc.), and these properties are considered when determining the manufacturing process for different embodiments of the U-shaped main housing wall assembly (8045). Generally, it is preferred to bend the material transversely to the material grain direction to avoid material cracking and separation of the joined material layers; however, this varies with material thickness. The composite sheet metal structure can be preheated to, for example, 90° to 150° prior to bending to reduce localized stresses during bending, thereby helping to prevent material separation and / or undesirable deformation. Other forming methods, such as forging at higher temperatures, may be used without departing from the present technique.

[0214] In a first non-limiting exemplary manufacturing process, the outer protective layer (8250) is formed from three separate flat sheets of the appropriate sheet material described above. The three separate flat sheets correspond to the outer top portion (8265), and each of the two outer portions (8255), (8260). Each flat sheet is cut into a predetermined finished size (8045) corresponding to the finished size of the U-shaped main shell wall assembly. When the sheet is still a flat sheet, any additional processing of each of the three flat sheets is completed, and the processing can be performed before the sheet is cut into the finished size. Additional processing can include drilling, stamping or otherwise forming a channel for providing a fuel flow port or a cathode air flow port (such as a combustion exhaust port (9060)), or a channel for providing an inlet for a fuel delivery pipeline to enter the combustion area during cold start, or an inlet for providing an electrical interface for current collection, sensor attachment points, etc. Additional holes or features that may be required to provide other mechanical interface features are added at this stage of the manufacturing process, such as for attaching the outer protective layer elements (8265, 8255, 8260) to the thermal core (8200) and / or to the hot zone shell end walls (8080, 8085) or for attaching the outer protective layer to the inner protective layer that may be required.

[0215] After preparing the flat sheet for assembly, including plating, machining, stamping, etc., the outer top portion (8265) is bent to form Figure 9C The U-shaped structure shown in FIG, wherein the inner radius of the outer top portion is positioned facing the SOFC stack. The cylindrical radius has a longitudinal axis along the stack length axis (x) and has an inner radius that matches the outer radius of the core top portion (8215). The bending radius is formed by a hydraulic bending device that is operable to bend or form a flat sheet metal structure on a press breaker or the like at room temperature (air bending). The bending radius that can be bent without damaging the material and managing undesirable consequences (such as springback) is affected by, for example, material properties (e.g., hardness, tensile strength, material thickness, material grain orientation, etc.), and these properties are considered when determining the manufacturing process for different embodiments of the outer top portion (8265). Generally, it is preferred to bend the material transversely to the material grain direction to avoid material cracking and separation of the joined material layers; however, this varies with material thickness. The composite sheet metal structure can be preheated to, for example, 90° to 150° before bending to reduce localized stresses during bending, thereby helping to prevent material separation and / or undesirable deformation. Other forming methods, such as forging at higher temperatures, etc., may be used without departing from the technology.

[0216] After preparing the two flat sheets (8255, 8260) and the curved outer top portion (8265) for assembly (including machining, punching, etc.), each of the three outer protective layers is assembled to the outer surface of the heat-conducting core (8200) and bonded to the heat-conducting core. Bonding techniques may include welding, brazing, soldering, fastening (e.g., riveting, self-riveting, or self-riveting) through folded tab joints, or a combination thereof. As described above, the three outer protective layers are assembled to completely cover the outer surface of the heat-conducting core (8200) to prevent oxidation caused by the cathode air flow and / or the mixture of spent cathode gas and spent synthesis gas in the combustion zone (8030).

[0217] 4.12.5.2 Manufacturing process: Three sheets joined together

[0218] In a second non-limiting exemplary manufacturing process, each of the inner protective layer (8220), the thermally conductive core (8200), and the outer protective layer (8250) is formed as a unitary flat sheet from its appropriate sheet material as described above. Each flat sheet is cut into predetermined finished dimensions (8045) corresponding to the finished dimensions of the U-shaped main housing wall assembly. Any additional processing of each of the three unitary flat sheets is completed while the unitary flat sheets are still flat sheets. Additional processing includes at least drilling, stamping or otherwise forming a cathode chamber input port (8095) through the inner protective layer (8220), and adding other holes or formed features as may be required to provide mechanical interface elements for attaching the bottom edge of the inner protective layer (8240, 8245) to the hot zone shell base wall (8075), or attaching the bottom edge of the inner protective layer (8240, 8245) to the input fuel manifold (8015), and / or attaching the bottom edge of the inner protective layer (8240, 8245) to the intermediate shell (9000). Additional holes or features that may be required to provide other mechanical interface features are also added before assembling the U-shaped main shell wall assembly (8045), such as for attaching the inner protective layer (8220) to the hot zone shell end wall (8080, 8085), or for attaching the inner protective layer (8220) or the outer protective layer (8250) to the thermal core (8200), or for providing fuel or cathode air flow ports (such as combustion exhaust ports (9060) or providing an inlet for a fuel delivery pipeline (8040)), or for providing a fuel pipeline to the combustion area for use during cold start, or for providing an inlet for an electrical interface for current collection, sensor attachment points, etc.

[0219] After preparing the three flat sheets for assembly including electroplating, machining, stamping, etc., the flat sheets corresponding to the inner protective layer (8220) and the outer protective layer (8250) are each joined to the flat sheet corresponding to the thermally conductive core (8200), for example by aligning and clamping the three sheets in contact with each other and brazing the three sheets together to form a composite sheet metal structure that is still a flat sheet. As noted above, the rolling direction of each sheet is identified before the sheets are cut and assembled together, and consideration is given to orienting the grain direction relative to the bending axis corresponding to the bending radius of the inner top portion (8225), the core top wall (8215), and the outer top portion (8265). The composite sheet metal structure is then bent to form Figure 9C A U-shaped structure is shown, with the inner protective layer positioned facing the SOFC stack. The cylindrical radius has a longitudinal axis along the stack length axis (x). The bending radius is formed using a hydraulic bending device operable to bend or form the composite sheet metal structure at room temperature (air bending) on ​​a press breaker or the like. The bending radius that can be bent without damaging the material and managing undesirable consequences (such as springback, separation of individual sheets, or cracking along the bending axis) is influenced by material properties (e.g., hardness, tensile strength, material thickness, material grain orientation, etc.), and these properties are considered when determining the manufacturing process for different embodiments of the U-shaped main housing wall assembly (8045). Generally, it is preferred to bend the material transversely to the material grain direction to avoid cracking and separation of joined material layers; however, this varies with material thickness. The composite sheet metal structure can be preheated to, for example, 90° to 150° prior to bending to reduce localized stresses during bending, thereby helping to prevent material separation and / or undesirable deformation. Other forming methods, such as forging at higher temperatures, may be used without departing from the present technique. 4.12.5.3 Additional Manufacturing Process Examples

[0220] As described in the first and second manufacturing processes above, any one of the inner protective layer (8220), the thermally conductive core (8200), and the outer protective layer (8250) can be formed from a whole flat sheet blank comprising all three parts, including a top portion to be bent into a cylindrical radius and two side portions extending from opposite edges of the cylindrical radius. Depending on the further manufacturing process, two or three of the three whole flat sheet blank parts can be joined together by cladding. The cladding can be implemented by a single cladding step, wherein the flat sheet blanks corresponding to the inner protective layer (8220) and the outer protective layer (8250) are each joined to the flat sheet corresponding to the thermally conductive core (8200) in a single cladding or rolling step. Alternatively, the coating can be performed in a two-step process, wherein a flat sheet blank corresponding to the inner protective layer (8220) or the outer protective layer (8250) is joined to a flat sheet corresponding to the thermally conductive core (8200), and then in a second coating step, the remaining flat sheet blank corresponding to the inner protective layer (8220) or the outer protective layer (8250) is joined to a flat sheet corresponding to the thermally conductive core (8200).

[0221] During the cladding process, the width of the clad blank is transverse to the rolling direction, so that the width of the clad blank is preferably selected to correspond to the desired length dimension of the U-shaped main shell wall assembly (8045) along the SOFC stack axis (x).

[0222] The composite cover sheet is cut from the cover blank into predetermined finished sizes corresponding to forming the inner protective layer, the thermally conductive core and the outer protective layer. Any additional processing of the composite cover sheet is completed while the composite cover sheet is still flat. Additional processing includes at least drilling, stamping or otherwise forming a cathode chamber input port (8095), plus adding other holes or forming features such as may be required to provide mechanical interface elements for attaching the composite cladding sheet to the hot zone shell base wall (8075) and / or to the input fuel manifold (8015) and / or to the intermediate shell (9000), and adding other mechanical interface features such as may be required before bending the single clad flat sheet embodiment, other mechanical interface features such as for attaching the composite cladding sheet to the hot zone shell end wall (8080, 8085) or for providing a fuel flow port or cathode air flow port (such as a combustion exhaust port (9060) or for providing an inlet for a fuel delivery pipe (8040)), or for providing a fuel pipe to the combustion area for use during cold start, or for providing an inlet for an electrical interface for current collection, sensor attachment points, etc.

[0223] After preparing the composite cladding sheet (including electroplating, machining, stamping, etc.), the composite cladding sheet is bent to form Figure 9CThe U-shaped structure shown in FIG, wherein the inner protective layer is positioned facing the SOFC stack. The cylindrical radius has a longitudinal axis along the stack length axis (x). The bending radius is formed by a hydraulic bending device operable to bend or form the composite sheet metal structure on a press breaker or the like at room temperature (air bending). The bending radius that can be bent without damaging the material and managing undesirable consequences (such as springback, separation of individual sheets, or cracks along the bending axis) is affected by material properties (e.g., hardness, tensile strength, material thickness, material grain orientation, etc.), and these properties are considered when determining the manufacturing process for different embodiments of the U-shaped main housing wall assembly (8045). Generally, it is preferred to bend the composite cover sheet transverse to the material grain direction to avoid material cracking and separation of the joined material layers; however, this varies with material thickness. The composite cover sheet can be preheated prior to bending, for example to 90°C to 150°C or up to 1000°C, to reduce localized stresses during bending, thereby helping to prevent material separation and / or undesirable deformation.

[0224] As further described in the first and second manufacturing processes above, any of the inner protective layer (8220), the thermally conductive core (8200), and the outer protective layer (8250) can be formed as three separate flat sheet blank elements, corresponding to the top portion to be bent into a cylindrical radius and the two side portions extending from opposite edges of the cylindrical radius. In the case of the thermally conductive core (8200), it is manufactured by cutting each of the two core sidewall portions (8205, 8210) and the core top portion (8215) from a flat sheet of core material. Thereafter, any drilling, stamping, machining, or electroplating is performed while the three core portions are still flat. The core top portion (8215) is then bent into the desired cylindrical radius, and then the two core sidewall portions (8205, 8210) are attached along different edges of the cylindrical radius to form the assembled thermally conductive core (8200).

[0225] The inner and outer protective layers (8220 and 8250) are each manufactured in the same manner, with the inner and outer top portions (8225 and 8265) and inner and outer sidewall portions (8230, 8235, 8255, 8260) being formed from a flat sheet of core material. Thereafter, any drilling, stamping, machining, or plating is performed on the inner and outer protective layer portions, which remain flat. The inner and outer top portions (8225 and 8265) are then bent to the desired cylindrical radius, for example, to match the inner and outer radii corresponding to the core top portion (8215). Thereafter, the inner top portion (8225) and outer top portion (8265) and inner side wall portions (8230, 8235) and outer side wall portions (8255, 8260) are mounted to the assembled thermally conductive core and clamped in place and then soldered, welded or otherwise mechanically attached to the thermally conductive core.

[0226] As further described above in the first and second manufacturing processes, any one of the inner protective layer (8220), the thermally conductive core (8200), and the outer protective layer (8250) can be formed as a separate flat sheet blank element that corresponds to all three of the top portion and both sidewall portions of the finished element. Thereafter, any drilling, stamping, machining, or plating is performed while the three separate flat sheet blank elements are still flat. Thereafter, each of the three separate flat sheet blank elements is bent into the desired cylindrical radius in three separate bending steps. Thereafter, each of the three previously bent elements is assembled together, clamped, and joined together by soldering, welding, or other mechanical fastening elements.

[0227] 4.12.6 Heat conduction through core material

[0228] See also Figure 7B and Figure 9C , the heat energy radiated from the combustion zone (8030) largely impinges on the combustion zone wall portion (8060) and specifically on the inner top wall portion (8225). In addition, the gas moving through the combustion zone (8030) transfers heat energy to the inner top wall portion (8225) to a large extent by convection. Although the same heat energy transfer mechanism occurs at each inner protective layer sidewall (8230, 8235), the heat energy transfer rate from the gas in the combustion zone wall portion (8060) is greater than the heat energy transfer rate from the gas not in the combustion zone, or the gas rate or gas heat energy transfer is smaller because the temperature or gas in the combustion zone (8030) is higher. Therefore, the heat energy transfer rate to the inner top wall portion (8225) is higher than the heat energy transfer rate to the inner sidewalls (8230, 8235).

[0229] Thermal energy is transferred from the inner protective layer (8220) to the thermally conductive core (8200) through a combination of thermal conductivity between the mating surfaces of the inner protective layer (8220) and the thermally conductive core (8200) and radiation emitted from the higher temperature surface to the lower temperature surface. Furthermore, thermal energy is transferred from the higher temperature region of the inner protective layer (in this case, the inner protective top portion (8225)) to the lower temperature inner sidewalls (8230, 8235) by thermal conduction through the inner layer material. Similarly, thermal energy is transferred from the higher temperature region of the thermally conductive core (in this case, the core top portion (8215)) to the lower temperature core sidewalls (8205, 8210) by thermal conduction through the thermally conductive core material. However, because the material of the heat-conducting core has a much higher thermal conductivity than the material of the inner protective layer (8220), the rate of heat energy transfer by heat conduction from the core top portion (8215) to each core side wall (8205), (8210) is seven times the rate of heat energy transfer from the inner protective layer top portion (8025) to the inner protective layer side portions (8235), (8240). The heat conduction energy flow path from the core top portion (8215) to each core side wall (8205), (8210) is Figure 7B The thermal conductivity of the core is shown by a black dashed line with backward arrows pointing from the core top portion (8215) to each of the core sidewalls (8205), (8210). The transfer of thermal energy from the core top portion (8215) reduces the thermal gradient existing in the core material, thereby causing the temperature of the core top portion to decrease and correspondingly increasing the temperature of the core sidewall portions. Ideally, the increased rate of thermal energy transfer in the thermally conductive core passively reduces the thermal gradient between the core top portion (8215) and the two core sidewalls (8205), (8210), thereby causing a reduction in the thermal gradient of each of the inner protective layer (8220) and the outer protective layer (8250). As the thermal gradient is reduced, the entire U-shaped main housing wall assembly (8045) emits thermal energy more uniformly along the airflow axis (z), and thus redistributes thermal energy received from the combustion zone (8030) to the cathode air passing through the middle and lower volumes of the cathode chamber (8055) and the cathode input manifold (9070), and to the walls of the SOFC tubes (8010) and the middle housing. Applicants note that a single core sidewall (such as either of the core sidewalls (8205), (8210)) may be used to provide the desired passive reduction of the thermal gradient between the core top portion (8215) and the core sidewall alone without departing from the present technology.

[0230] A significant benefit of reducing the thermal gradient along the gas flow axis (z) is that the thermal gradient along the gas flow axis (z) along the SOFC stack (8005) is reduced. For example, by increasing the surface area of ​​the anode and cathode layers maintained at the optimal SOFC reaction temperature, the SOFC reaction yield is increased, for example, measured as the DC current generated per unit of synthesis gas delivered. When only a portion of the anode and cathode surface areas participate in the SOFC reaction, because the non-participating portions of the anode and cathode surface areas are not at the optimal reaction temperature, or when the cathode gas flow is not at the optimal reaction temperature, as described above, reducing the thermal gradient tends to convert the non-participating SOFC reaction portion of the SOFC system into a participating portion, thereby increasing the current output.

[0231] The second benefit is that the more uniform temperature of the SOFC stack along the airflow axis (z) may reduce damage to the SOFC fuel cell and other components caused by thermal expansion mismatch. The fuel cell is formed by three ceramic layers, each of which has a different thermal expansion coefficient. When the length of each material layer along the airflow axis (z) changes differently during thermal cycling (e.g., startup or shutdown), the cracking or separation of the three ceramic layers is a common failure mode. Any reduction in the temperature gradient along the airflow axis (z) potentially reduces damage to the SOFC fuel cell. Similarly, the hot zone housing assembly (8042) includes three walls, a heat conductive core (8200) and two protective layers (8220, 8250), each of which is formed by two different materials having different thermal expansion coefficients. During thermal cycling, when different wall materials expand at different rates, the separation and deformation of the three metal layers is a potential failure mode. The reduction in the temperature gradient change along the airflow axis (z) potentially reduces damage to the U-shaped hot zone housing assembly wall during thermal cycling.

[0232] Heat conduction is described as the rate of heat energy transfer (per unit time), also known as heat flow or heat flux, which can be expressed in watts or joules per second. The following equation 1 defines the flux Q as,

[0233] Q=kA / d(ΔT) Equation 1

[0234] Where (Q) is the rate of heat transfer in Watts, (k) is the thermal conductivity in W / (m°K), and (A) is the area of ​​the heat conduction path, e.g., in square meters (m 2 ), (d) is the length of the conductive path in meters, and (ΔT) is the temperature gradient in degrees Kelvin. In the case of the thermally conductive core of this embodiment, the length of the conductive path (d) is equal to the linear distance from the center of the top portion (8215) of the thermally conductive core to the bottom edge of one of the side portions (8205) and (8210). The dimension of area (A) is the product of the thickness of the conductive path and the length of the conductive path (e.g., along the stack length axis (x)).

[0235] In a sample calculation, based on a thermal gradient ΔT of 200°K, a thermal conductivity coefficient of 350 W / (m°K), a core thickness of 2.5 mm (0.0025 m), and a length dimension (d) of 0.4 m, a unit area of ​​core material (e.g., a square dimension equal to the core thickness) provides a heat flow or flux of 1.1 W per unit area, where the unit area is a square with a side dimension of 2.5 mm (0.1 in). When the area dimension exceeds the entire stack length dimension (e.g., 0.61 m or 24 in), the heat flow or flux of the thermal conductivity through each side wall is 267 W. By comparison, when the thermal conductivity of the core material is 50 W / (m°K), the heat flow or flux through each side wall is 38.0 W. Thus, the thermally conductive core of the present embodiment potentially provides a 7-fold increase in heat flux through the thermally conductive core (8200) compared to hot zone housing walls made of conventional high temperature environment materials having a thermal conductivity of 50 W / (m°K) or less (e.g., steel alloys, including Hastelloy, as well as Monel and Inconel).

[0236] 4.12.7 Blackbody Characteristics

[0237] In addition to thermal conduction, the thermally conductive core (8200) exhibits blackbody properties, where the energy radiated per unit surface area per unit time across all wavelengths is proportional to the fourth power of the blackbody temperature. Figure 7B As depicted in and described above, blackbody energy radiated from the airflow is included. In the case of a thermally conductive core, the radiation emitted thereby tends to be incident on the inner protective layer (8220) and the outer protective layer (8250), and the radiation absorbed by the thermally conductive core tends to be emitted by the inner protective layer (8220) and the outer protective layer (8250).

[0238] The blackbody radiation emissivity is described in Equation 2, which assumes that the emitter has a surface emissivity which it may not have.

[0239] Q=σA(Tir 4 -Ts 4 ) Equation 2

[0240] Where Q is the rate of heat transfer per unit time in Watts and A is the area of ​​the radiating surface in m 2 is the unit, σ is the Stefan constant ’ sconstant), (5.6703×10 -8 W / s 2 K 4 ), T iris the temperature of the radiating surface, and Ts is the temperature of the surrounding wall, in degrees Kelvin. As will be appreciated, when thermal energy is thermally conducted from the core top portion (8215) to the lower ends of the core side walls (8230, 8235) through the thermally conductive core (8200), the temperature of the core top portion decreases while the temperature of the core side wall portions increases. The change in the two wall temperatures changes the blackbody radiation emissivity at each location, which is proportional to the fourth power of the temperature difference. In an exemplary comparison, assume that the temperature of the lower ends of the main shell side walls (8065, 8070) increases from 650°C (923°K) to 700°C (973°K) due to thermal conduction through the core, and assume that the temperature of the surrounding wall surfaces does not change, for example, 550°C (823°K), and the area of ​​the radiating surface is one square centimeter (1.0x10 -4 m 2 ), as described above. In this example, at a temperature of 650°C, the rate of thermal energy transfer (radiative emissivity) is 1.514 W. At an elevated temperature of 700°C, the rate of thermal energy transfer is 2.481 W, which is a 64% increase in radiative emissivity per square centimeter.

[0241] 4.12.8 Temperature Measurements Demonstrate Passive Thermal Gradient Reduction

[0242] Now see Figure 10A 、 Figure 10B 11A and 11B , temperature measurements taken by a five-thermocouple arrangement demonstrate the passive reduction of thermal gradients along the gas flow axis (z) for multiple individual fuel cells mounted on a test fixture. Figure 10A Five SOFC fuel cells (10005) arranged on a test fixture (10000) are schematically depicted. The SOFC fuel cell is tubular with a cylindrical outer wall surrounding a fluid conduit. The anode surface is formed on the inner diameter of the fluid conduit of each fuel cell, and the cathode surface is formed on the outer diameter of each fuel cell. The test fixture includes a fuel input manifold (10010) that is configured to support each fuel cell from its bottom end. The synthesis gas flow is delivered to each tube fluid conduit through the fuel input manifold. The cathode chamber is formed by enclosing the test fixture fuel cell in a test housing that is designed to provide the same function as the above-mentioned hot zone housing assembly (8042). As described below, two test housing units are constructed. The first test housing does not include a thermally conductive core of the present technology and the second test housing includes a thermally conductive core of the present technology.

[0243] The test fixture includes five thermocouples (TC1 to TC5) located at five locations indicated by five asterisks (10030), as shown in FIG. Figure 10AAs shown. These five thermocouples (TC1-TC5) are distributed along the air flow axis (z) and are evenly spaced. The thermocouples are installed between the fuel cells (10005) or close to the surface of a fuel cell. The length of each fuel cell (10005) along the air flow axis (z) is selected to match the desired fuel cell size, for example, 150mm-300mm (6 inches-12 inches). Thermocouple TC5 is positioned at about 15mm (0.6 inches) from the upper end of the SOFC stack, and the remaining thermocouples are evenly distributed along the length of the cell. Each thermocouple (TC1 to TC5) is electrically connected to an electrical controller (not shown). The electrical controller is configured to receive a temperature signal from each of the five thermocouples to process the temperature signal, such as comparing the temperature signal with a temperature calibration table, storing a series of temperature signals detected by each thermocouple over a period of time, and determining an average temperature value over a given time period.

[0244] During the first set of temperature measurements, each of the five thermocouples was operated to monitor the temperature at each of the five star positions (10030) over a two and a half hour startup to cool-down operation period, recording temperature data at predetermined time intervals and calculating an average temperature. The first set of temperature measurements was recorded as the test fixture heated from a cold start to an operating temperature corresponding to generating current output, during the entire time the test fixture generated current, and as the test fixture cooled to the cold start temperature. In this example, the operating temperature corresponding to generating current output was maintained for approximately one and a half hours, with the startup and cool-down phases each lasting approximately 30 minutes.

[0245] During the first set of temperature measurements, the test fixture was operated inside the furnace without a thermally conductive core installed to enclose the stack.

[0246] exist Figure 10B A first set of temperature measurements is graphically illustrated in FIG. 1 by black bars (10035), where each black bar indicates the average temperature corresponding to one of the thermocouples during steady-state operation. A dashed line (10050) extends between each black bar (10035) and one of the thermocouples (TC1-TC5) to indicate which thermocouple the average temperature value is associated with. Each temperature measurement corresponding to a black bar (10035) is the average temperature measured by the corresponding thermocouple during the current output of the test fixture. As shown by the black bars (10035), the average temperature measured at TC1 is approximately 775°C, the average temperature measured at TC2 is approximately 700°C, the average temperature measured at TC3 is approximately 720°C, the average temperature measured at TC4 is approximately 630°C, and the average temperature measured at TC5 is approximately 640°C. The temperatures are averaged over an operating period of approximately one hour.

[0247] During the second set of temperature measurements, the test fixture was operated with a second test housing assembly that included a thermally conductive core. The second test housing assembly used the aforementioned U-shaped main housing wall assembly (8045) that included an inner protective layer (8220), a thermally conductive core (8200), and an outer protective layer (8250), as described above. Figure 9C As shown. The inner protective layer (8220) and the outer protective layer (8250) of the second test housing assembly are formed of a monel copper-nickel alloy having a thermal conductivity of approximately 22.8 (W / m°K) and a thickness of the inner and outer protective layers of approximately 4.0 mm (0.16 inches). The thermal conductive core (8200) of the second test housing is formed of a copper alloy having a thermal conductivity of approximately 350 (W / m°K), and the thickness of the thermal conductive core corresponding to the second test housing is approximately 3.0 mm (0.12 inches).

[0248] The second set of temperature measurements corresponding to the second test shell is Figure 10B 1-TC5). The temperature measurements corresponding to the striped white bars are shown in graphical form by striped white bars (10040), where each striped white bar is associated with a thermocouple, as indicated by the dashed line (10050) extending between each striped white bar (10040) and one of the thermocouples (TC1-TC5). Each temperature measurement corresponding to the striped white bar is an average temperature recorded during the period of time when the test fixture was generating a current output. As shown by the striped white bars (10040), the average temperature measured at TC1 was approximately 710°C, the average temperature measured at TC2 was approximately 720°C, the average temperature measured at TC3 was approximately 730°C, the average temperature measured at TC4 was approximately 740°C, and the average temperature measured at TC5 was approximately 710°C.

[0249] As predicted in the above description, the thermal gradient along the stack airflow axis (z) was reduced by adding the copper core in the second test fixture. The temperature measurement data for the first set of temperature values ​​measured using the first test housing assembly that did not include the thermally conductive core and the second set of temperature values ​​measured using the second test housing assembly (including the thermally conductive core) are listed in Table 1 below. As can be seen from the data listed in Table 1 and in Figure 10B As is apparent from the data graphically presented in Figure 1, the addition of the thermally conductive wick to the second test housing assembly reduced the thermal gradient along the airflow axis (z) of the test fixture fuel cell (10005). Applicants further note that in the second data set corresponding to the second test housing assembly including the thermally conductive wick, the highest temperature measured was at TC4, indicating that the addition of the thermally conductive wick actually shifted the location of the peak temperature from the combustion region (8030) to a point below the midpoint of the fuel cell.

[0250]

[0251]

[0252] Table 1 Temperature change at each temperature measurement position (℃)

[0253] FIG11A graphically depicts temperature measurement data recorded during a first test cycle using a first test housing assembly that did not include a thermally conductive core. FIG11A illustrates a graph with a vertical axis corresponding to temperature in degrees Celsius as measured by five thermocouples, and a horizontal axis corresponding to time in hours. FIG11A illustrates a graph that includes five different temperature versus time plots, one for each of five thermocouple locations. A legend (10045) indicates which data plots correspond to which thermocouple locations (TC1, TC2, TC3, TC4, TC5).

[0254] Similarly, FIG11B graphically depicts temperature measurement data recorded during a second test cycle using a second test housing assembly including a thermally conductive core. The vertical axis of the graph of FIG11B corresponds to the temperature in ° C. measured by the five thermocouples, and the horizontal axis of FIG11B corresponds to time in hours. The graph of FIG11B includes five different temperature versus time plots, one for each of the five thermocouple locations. The legend (10055) indicates which data plots correspond to which thermocouple locations (TC1, TC2, TC3, TC4, TC5).

[0255] Comparison of the two plots reveals that during the startup period, when the temperature of the thermocouple increases from 100°C to above 700°C over a period of approximately 30 minutes, the rate of temperature increase at each of the five thermocouple locations is almost the same when the thermal wick is in place ( FIG. 11B ) and significantly different when the thermal wick is not in place ( FIG. 11A ). This is evident when comparing the startup period of FIG. 11A with the startup period of FIG. 11B . FIG. 11A shows that the rate of temperature increase in °C per unit time is greatest at thermocouple location (TC1) and least at thermocouple location (TC5). In contrast, FIG. 11B shows that the rate of temperature increase in °C per unit time is more uniform across the five thermocouple locations (TC1, TC2, TC3, TC4, TC5) throughout the startup period.

[0256] When different portions of an individual fuel cell (8010) are heated at different rates, this can lead to layer cracking and / or spalling of the fuel cell ceramic layers and failure of interfaces between ceramic and metal components in the stack. Similarly, when different portions of the hot zone housing assembly wall are heated at different rates, this can lead to layer delamination and / or warping of the thermally conductive core and the inner and outer protective layers.

[0257] 4.12.9 Additional SOFC System Examples

[0258] Now see Figure 12 The non-limiting exemplary SOFC system (12000) includes two hot zone housing assemblies (12042). The two hot zone housing assemblies are each disposed inside the intermediate housing (9000), as shown in FIG9 , Figure 16B and Figure 17 As shown, and spaced apart along the stack transverse axis (y). Each hot zone housing assembly (12042) includes an SOFC stack (8005), a fuel input manifold (8015) fluidly connected to a fuel reformer (8035) via a fuel delivery conduit (8040), and an L-shaped main housing wall assembly (12045). Each SOFC stack (8005) is enclosed within a different cathode chamber (12055). Each cathode chamber (12055) is partially defined by one of the L-shaped main wall assemblies (12045) and partially defined by the intermediate housing base wall (9010) sidewalls (9015 or 9020), as shown. Figure 13 In addition, each cathode chamber can be composed of Figure 9C The opposing main housing end walls (8080, 8085) and the main housing base wall (8075) shown in FIG.

[0259] Figure 13 Two L-shaped main housing assemblies (12045) are depicted, one of which is positioned above a first SOFC stack (8005) and the other is positioned above another SOFC stack (8005). Figure 13A As shown, each L-shaped main housing wall assembly (12045) is formed with three wall sections, a combustion region curved wall section (12062), a combustion region flat wall section (12064) extending from a first edge of the curved wall section, and a main housing side wall (12070) extending from a second edge of the curved wall section. The combined curved wall section (12060) and combustion region flat wall section (12064) provide an upper boundary of the cathode chamber (12055) (described below) and form an upper boundary of the combustion region (8030) to receive heat energy from the combustion region (8030). The side wall section extends from the edge of the curved wall section and is disposed along the gas flow axis (z) between the SOFC tube output end (8025) and the SOFC tube input end (8020).

[0260] Each L-shaped main housing wall assembly (12045) defines a cathode chamber (12055). The cathode chamber (12055) encloses the corresponding SOFC stack (8005) and the combustion zone (8030), such that the cathode layer formed on the outer surface of each individual fuel cell (8010) is exposed to the cathode chamber (12055). The cathode chamber (12055) is partially defined by the corresponding L-shaped main housing wall assembly (12045), by the intermediate housing side wall (9015 or 9020), and by the intermediate housing bottom wall (9010) or by the fuel input manifold (8015), or another bottom wall such as (8075), as shown in FIG. Figure 9C Each L-shaped main housing wall assembly (12045) defines a different cathode chamber (12055).

[0261] The SOFC system (12000) includes a recuperator chamber (9050) and a hot zone exhaust duct (9055) each formed inside the intermediate housing (9000). The recuperator chamber (9050) and the hot zone exhaust duct (9055) together form the above-mentioned Figure 7A and Figure 7B Ambient temperature cathode air flow is received into the recuperator chamber (9050) through the cathode input port (9040) and exhaust gases are exhausted from the exhaust duct through the hot zone exhaust port (9045).

[0262] Inside the recuperator chamber (9050), the incoming cathode air stream (e.g., ambient temperature air) is heated by convection and by radiation emitted from the walls of the recuperator chamber, and in particular, the shared wall (9075) separating the hot zone exhaust gas duct (9055) from the recuperator chamber (9050). The heated cathode air stream is forced through the recuperator chamber (9050) and exits the recuperator chamber through one or more recuperator outlet ports (9065) to the cathode input manifold (13070). The cathode air stream source includes a variable speed air moving device (e.g., a fan) that is controlled to increase or decrease the flow rate of the incoming cathode air stream based on electrical output demand and other process control instructions.

[0263] The hot zone exhaust duct (9055) receives the hot gas mixture from the two combustion zones (8030) through two combustion exhaust ports (9060), wherein each combustion exhaust port (9060) extends from one of the two combustion zones (8030) to the hot zone exhaust duct (9055). Inside the hot zone exhaust duct (9055), the hot gas mixture is cooled as energy is transferred convectively and radiatively to the walls of the hot zone exhaust duct (9055). The hot gas mixture passes from the combustion zone (8030) through the outlet of the SOFC hot zone through the hot zone exhaust port (9045), and finally exits the SOFC hot zone through the hot zone exhaust port (9045).

[0264] The recuperator chamber (9050) and the hot zone exhaust duct (9055) are each preferably arranged along the stack length axis (x) along the entire length of the SOFC stack. Each of the cathode input port (9040), the hot zone exhaust port (9045), and the two combustion exhaust ports (9060) can be implemented as a single instance of all three ports, such as a cathode input port (9040) positioned at the center or one end of the stack length along the stack length axis (x) or a plurality of cathode input ports (9040), hot zone exhaust ports (9045), and combustion exhaust ports (9060). The combustion exhaust ports (9060) can be spaced apart along the stack length axis (x) to more evenly distribute the cathode gas flow to the individual fuel cells and to more evenly distribute the exhaust gas from the SOFC hot zone. The port orifices can be circular, slot-shaped, or other examples of port shapes that are arranged along the stack length axis (x). Alternatively, the recuperator chamber (9050) and the hot zone exhaust duct (9055) can each be implemented as a single chamber instance extending along the entire stack length axis (x), or the recuperator chamber and exhaust duct can be configured as multiple separate chamber and duct instances, with the multiple separate chambers and ducts being arranged side by side along the stack length axis (x), wherein each separate chamber instance is provided with its own cathode input port (9040), and / or hot zone exhaust port (9045) and a combustion exhaust port (9060) is provided for each cathode chamber.

[0265] like Figure 12As shown, two cathode chambers (12055) share a single cathode input manifold (13070). The top boundary of the cathode input manifold (13070) is defined by the exhaust duct bottom wall (9059). The opposing cathode input manifold side boundaries are defined by the outer surface of each of the two L-shaped main housing wall components (12045), and the cathode input manifold (13070) has a bottom boundary defined by the intermediate housing bottom wall (9010) or the other bottom wall (8070) described above, or both. Each end of the cathode input manifold (13070) can be defined by the intermediate housing end walls (9025, 9030) described above or by the end walls (8065, 8085).

[0266] Cathode gas flow Figure 12 1 is shown by solid flow lines with arrows. The cathode air flow enters through the cathode input port (9040), passes through the recuperator chamber (9050) and then enters the cathode input manifold (13070) through each of the two recuperator outlet ports (9065). Inside the cathode input manifold (13070), the cathode air flow is directed downward from the recuperator outlet ports (9065) to enter two sets of cathode chamber input ports (8095), with one set of cathode flow channels corresponding to each L-shaped main housing wall (12045). The cathode air is then passed from the cathode input manifold (13070) to each of the two cathode chambers (12055). Inside the cathode chamber, the cathode gas flows upward over the exposed cathode surface of the SOFC stack until it reaches the combustion zone (8030), where the spent cathode air flow mixes with the spent fuel. Further flow paths of the mixture of spent fuel and spent cathode air are indicated by dashed flow lines with arrows showing the mixture flowing from the combustion zone (8030) through two combustion exhaust ports (9060) (one for each cathode chamber) and through the hot zone exhaust duct (9055) where the mixture transfers heat energy to the common wall (9075) surface and other wall surfaces before exiting the SOFC system through the hot zone exhaust port (9045). The combustion region wall portion (12060) is formed with a combustion region curved wall portion (12062) and a flat combustion region wall (12264), the combustion region curved wall portion (12062) and the flat combustion region wall (12264) each extending from a different intermediate shell side (the intermediate shell side being the (9015) or (9020) side wall) to form the top boundary of the corresponding cathode chamber (12055), and the main shell side wall (12070) extending from the second edge of the combustion region curved wall portion (12062) forms the side boundary of the corresponding cathode chamber (12055). The L-shaped main shell wall (12045) is arranged along the entire length of the stack length axis (x) and can further extend beyond the entire stack length dimension.

[0267] See also Figure 13B and Figure 14 Each L-shaped main housing wall assembly (12045) includes a heat conductive core (12200) protected by an inner protective layer (12220) and an outer protective layer (12250). The heat conductive core (12200) is similar in material, construction, function and thermal characteristics to the heat conductive core (12200) described herein. Figure 7A 、 Figure 7B 、 Figure 8B 、 Figure 9A 、 Figure 9B and Figure 9C The thermally conductive core (8200) discussed above is substantially similar, and the thermally conductive core (12200) includes a core material having a thermal conductivity greater than 100 W / (m°K) and preferably greater than 200 W / (m°K), such as one or more copper, molybdenum, aluminum nickel, beryllium, iridium, rhodium, silver, tungsten, or an alloy or combination, so that the thermally conductive core (12200) can be manufactured to have a desired thermal conductivity and can reliably meet structural requirements at hot zone operating temperatures. In a specific exemplary, non-limiting embodiment, the thermally conductive core (12200) includes a copper block having a thermal conductivity in the approximate range of 370 W / (m°K) at 500°C and 332 W / (m°K) at 1027°C.

[0268] The L-shaped main housing wall assembly (12045) includes an inner protective layer (12220) and an outer protective layer (12250) configured to protect the thermally conductive core wall (12200) from oxidation. The application of the inner and outer protective layers (12220, 12250) is as described above. In a first embodiment, each of the inner and outer protective layers (12220, 12250) comprises a nickel plating layer applied to the thermally conductive core (12200) by an electroplating process, having a thickness of at least 0.0005 inches and extending to 0.002 inches or greater. The nickel plating layer is applied to prevent oxygen from diffusing through the nickel plating layer at operating temperatures of 350°C to 1200°C. In a second embodiment, the inner protective layer (12220) comprises an inner sheet metal layer formed to mate with the inner surface of the thermally conductive core (12200), and the outer protective layer (12250) comprises an outer sheet metal layer formed to mate with the outer surface of the thermally conductive core (12200) to prevent oxygen from diffusing through either of the protective layers at an operating temperature of 350°C to 1200°C.

[0269] The inner protective sheet metal layer and the outer protective sheet metal layer are made of the above Figure 9CThe inner protective layer (8220) and the outer protective layer (8250) shown in FIG and described above are made of the same material. In an exemplary non-limiting embodiment, each inner protective layer (12220) and outer protective layer (12250) are formed of a material that is resistant to corrosion and especially resistant to oxidation under SOFC operating conditions. In a preferred embodiment, each inner protective layer (12220) and outer protective layer (12250) are made of ferritic stainless steel (such as Alloy 18 Stainless steel, such as that distributed by Rolled Metal Products, Inc. of Alsip, Illinois, USA). Figure 12 As shown in , the inner protective layer (12220) faces the cathode chamber (12055) and the outer protective layer (12250) faces the cathode input manifold (13070).

[0270] In an exemplary operating mode, heat energy generated in the combustion zone (8030) is transferred to the combustion zone wall (12060) by radiation and convection. Heat energy absorbed by the combustion zone wall is passively conducted through the inner protective layer (12220) to the conductive core (12200). The heat energy reaching the conductive core is passively conducted via the conductive core (12200) to a lower temperature area of ​​the heat-conducting core, such as to the end of the main shell side wall (12070). As a result, the temperature gradient existing in the core (12200) is reduced. During steady-state operation, the thermal gradient between the combustion zone wall (12060) and the bottom end of the main shell side wall (12070) is reduced. Heat energy is primarily exchanged via radiation between each L-shaped main shell wall assembly (12045) and the SOFC cell (8010). However, as the thermal gradient between the combustion zone wall and the side wall is reduced, the corresponding thermal gradient along the length of each SOFC cell along the airflow axis z is also reduced. Heat is conducted between the conductive core (12200) and the outer protective layer (12250). The cathode gas flowing in the cathode input manifold (13070, 14070, 15070) is heated by heat exchange between the outer protective layer (12250) and the cathode gas via conduction and convection.

[0271] refer to Figure 13B In a non-limiting exemplary embodiment, the L-shaped main housing wall assembly (12045) includes an inner protective layer (12220) formed as a single piece of material having an inner side wall portion (12230), an inner curved wall portion (12225), and an inner top wall portion (12227). The exemplary conductive core (12200) is preferably formed from a single piece of material having a core side wall portion (12210), a core curved wall portion (12215), and a core top wall portion (12217). Figure 13BAs shown in FIG, the outer protective layer (12250) is formed into three separate parts: an outer side wall portion (12260), an outer curved wall portion (12265), and an outer top wall portion (12267). The inner protective layer (12220), the thermally conductive core (12200), and the outer protective layer (12250) can be formed and joined together using any of the methods discussed with respect to the U-shaped main housing wall assembly (8045), such as Figure 9C shown.

[0272] Reference Figure 14 The SOFC system (14000) includes a single L-shaped hot zone housing assembly (14042) enclosing a single SOFC stack (8005) and an input fuel manifold (8015) and a fuel delivery pipe (8040). The L-shaped hot zone housing assembly (14042) is similar to the above Figure 12-13B The hot zone housing assembly (14042) is mounted within the intermediate housing (9000), which is sized to accommodate the single L-shaped hot zone housing assembly (14042). The intermediate housing provides the recuperator chamber (9050), hot zone exhaust port (9045), cathode input port (9040), cathode input manifold (14070), and cathode chamber (12055), all as described above. An advantage of the SOFC hot zone (14000) is its compact size.

[0273] See also Figure 15 The SOFC hot zone (15000) includes a hot zone housing assembly (15042) shown in a schematic diagram. The hot zone housing assembly (15042) includes two SOFC stacks (8055), two fuel input manifolds (8015), and U-shaped main housing wall assemblies (8045), each of which encloses one of the two SOFC stacks and forms an isolated cathode chamber (8055) around each SOFC stack, as described herein. Figure 7A 、 Figure 7B 、 Figure 9A 、 Figure 9B and Figure 9C The cathode input manifold (15070) is sized to receive the hot zone housing assembly (15042) therein and is defined by the inner facing surfaces of the intermediate housing side walls (9015, 9020) and the intermediate housing bottom wall (9010), by the outer facing surface of each of the two U-shaped main housing wall assemblies (8045), by the bottom wall (9059) of the hot zone exhaust duct (9055), and by the inner facing surfaces of the hot zone housing end walls (8080, 8085). Figure 9C Shown in.

[0274] 4.12.10 Intermediate casing

[0275] The hot zone housing wall components (12045, 14045, 15042) are each mounted inside the intermediate housing (9000), as shown in FIG16b and FIG16c. Figure 17 The intermediate housing is shown in an isometric view in FIG. The intermediate housing is formed into a chamber including opposing intermediate housing top walls (9005) and intermediate housing bottom walls (9010), opposing intermediate housing side walls (9015) and intermediate housing side walls (9020), and opposing intermediate housing end walls (9025) and intermediate housing end walls (9030). The intermediate housing (9000) encloses the fuel delivery pipeline (8040) in the gap between the intermediate housing end wall (9025) and the hot zone housing end wall (8080). The intermediate housing includes a cathode input port (9040) for receiving cathode air flow passing through the cathode input port (9040) and a hot zone exhaust port (9045) for exhausting exhaust gas from the intermediate housing. The intermediate housing includes a startup fuel inlet port (8145) for receiving a fuel flow during a startup mode of operation of the SOFC system and for directing the fuel flow to each startup burner element (8155). Each port (8145), (9040) and (9045) passes through the wall of the intermediate housing as needed to direct the gas flow to the receiving area interface. In a non-limiting exemplary embodiment, the fuel port passes through one of the side walls (9015, 9020), and each of the cathode gas input port (9040) and the hot zone exhaust port (9045) passes through the intermediate housing top wall (9005). The intermediate chamber (9000) also encloses or partially encloses the recuperator chamber (9050) and the hot zone exhaust duct (9055), and the function of each of the hot zone exhaust port (9045), the cathode input port (9040), the combustion exhaust port (9060, 9060a, 9060b), and the recuperator outlet port (9065) is as described with respect to Figure 7A 、 Figure 7B and Figure 8A described.

[0276] 4.12.11 External shell

[0277] like Figure 16A 、 Figure 16B and Figure 17As shown, the intermediate housing (9000) is mounted inside an insulating layer (2012), which preferably includes a top portion and a bottom portion (not shown) to thermally insulate the intermediate housing surface. The intermediate housing and the surrounding insulating layer are each mounted inside the outer housing (16000). In a first non-limiting exemplary embodiment, the outer housing (16000) includes two opposing outer housing side walls (16015) and two opposing outer housing end walls (16010), an outer housing top wall (16005), and an opposing outer housing bottom wall (16002). Preferably, the outer housing walls are thermally insulated from the intermediate housing (9000). In a preferred embodiment, the insulating layer (2012) is disposed between the inner housing (9000) and the outer housing (16000) and is configured to prevent the temperature of the outer wall from exceeding a maximum temperature, for example, greater than 60°C from the ambient temperature. The outer housing is formed to provide various input and output ports for interfacing with the anode gas fuel and cathode air conduits, exhaust gas outlet ports, power output from the SOFC stack, and an interface for a control system including temperature and power sensors, fluid flow meters, and other control elements as needed. Preferably, the outer housing is formed to have structural integrity designed to protect the inner intermediate housing, fuel cells, and other internal systems from damage by impact or moisture and to prevent contaminants from escaping from and / or entering the SOFC hot zone from the outside.

[0278] The outer housing (16000) is preferably formed of a metal wall, such as steel, stainless steel, aluminum, or the like. In some embodiments, for example, the outer housing, or a portion of the outer housing, or an element extending from the interior of the outer housing, can be used as a heat sink to radiate heat energy absorbed from within the SOFC system (e.g., from the fuel reformer, exhaust gas channel, or recuperator) to the air surrounding the SOFC hot zone. All patents, patent applications, and other references disclosed herein are hereby expressly incorporated herein by reference in their entirety.

[0279] Those skilled in the art will also recognize that, although the present technology has been described above with respect to preferred embodiments, it is not limited thereto. The various features and aspects of the above-described technology may be used individually or in combination. Further, although the technology has been described in the context of its implementation in a specific environment and for a specific application (e.g., a solid oxide fuel cell system), those skilled in the art will recognize that its applicability is not limited thereto, and that the technology may be beneficially used in any number of environments and implementations that desire to increase thermal energy transfer through thermal conduction using high thermal conductivity materials at high temperatures and in corrosive environments. Therefore, the claims set forth below should be interpreted in light of the full scope and spirit of the technology disclosed herein.

Claims

1. A main housing wall assembly (8045) for balancing the temperature within a solid oxide fuel cell (SOFC) stack, the main housing wall assembly comprising: a combustion zone wall and a first side wall, the combustion zone wall defining a cathode chamber (8055), the SOFC stack being disposed in the cathode chamber, the cathode chamber comprising a combustion zone surrounding an outlet end of the SOFC stack for collecting a spent fuel stream and a spent cathode air stream exiting the SOFC stack, wherein the spent fuel and the spent cathode air mix and combust in the combustion zone and generate heat, wherein the heat is transferred from the combustion mixture to the combustion zone; The first sidewall depends from the combustion zone wall along the SOFC stack gas flow axis, wherein: a cathode air manifold disposed externally of the main housing wall assembly, at least one wall of the cathode air manifold including both the combustion zone wall and the first side wall; The combustion zone wall includes an inner surface defining a portion of the cathode chamber and an outer surface facing the cathode air manifold, the first side wall includes an inner surface facing and also defining the cathode chamber, an outer surface facing the cathode air manifold, and the first side wall has an end adjacent to an inlet end of the SOFC stack; heat absorbed by the combustion zone wall is thermally conducted to the distal end of the first side wall; and The heat conducted to the end of the first side wall is radiated from the inner surface of the first side wall and radiated to the outer surface of the cell, the inner surface of the first side wall extending from the combustion zone wall through the cathode chamber to the inlet end of the SOFC stack, and the heat is transferred to the cathode air flow in the cathode air manifold by convection and radiation from the outer surface of the combustion zone wall and from the outer surface of the first side wall to reduce the temperature of the combustion zone wall and increase the temperature of the surface of the first side wall, the surface of the first side wall extending from the combustion zone wall to the inlet end of the SOFC stack.

2. The main housing wall assembly (8045) of claim 1, further comprising: a second sidewall depending from the combustion zone wall along the SOFC stack gas flow axis and opposite the sidewall, wherein the combustion zone wall is disposed above the SOFC stack along the SOFC stack transverse width axis; wherein the combustion zone wall, the first side wall and the second side wall are formed as an integral component; The second side wall includes an inner surface facing the cathode chamber and an outer surface facing the cathode air manifold; wherein the first sidewall and the second sidewall face opposite sides of the SOFC stack, and wherein the second sidewall further defines the cathode chamber; A first hot zone shell end wall and a second hot zone shell end wall (8080, 8085) coupled to each of the first side wall and the second side wall enclose the SOFC stack inside the cathode chamber (8055).

3. The main shell wall assembly (8045) according to claim 1 further includes a fuel input manifold (8015) or a hot zone shell base wall or an intermediate chamber shell base wall (9010), wherein the fuel input manifold (8015) or the hot zone shell bottom wall or the intermediate chamber shell base wall (9010) is configured to provide a bottom boundary of the cathode chamber.

4. The main housing wall assembly (8045) of claim 1, wherein: The combustion zone wall and the first side wall each include a thermally conductive core having a thermal conductivity greater than 100 W / m°K at a temperature of 350°C.

5. The main housing wall assembly (8045) of claim 2, wherein: The monolithic element includes a thermally conductive core having a thermal conductivity greater than 100 W / m°K at a temperature of 350°C.

6. The main housing wall assembly (8045) of claim 5, wherein: The thermally conductive core is made of a material selected from the group consisting of: copper and copper alloys; aluminum or aluminum alloys; molybdenum; aluminum-copper alloys; copper-nickel alloys; and combinations thereof.

7. The main housing wall assembly (8045) of claim 6, wherein: The shape of the fuel cell stack is selected from the group consisting of: oval, square, rectangular and triangular.

8. The main housing wall assembly of claim 1, wherein: The SOFC stack includes at least two rows of SOFC cells, the at least two rows of SOFC cells including a first row of SOFC cells and a second row of SOFC cells, wherein the first row of SOFC cells and the second row of SOFC cells are separated from each other by the side wall, wherein the side wall is disposed between the first row and the second row.

9. The main housing wall assembly of claim 1, wherein: The SOFC stack includes at least two rows of SOFC cells, and the main housing wall assembly further includes: a first exterior sidewall depending from the combustion zone wall along the SOFC stack gas flow axis and enclosing a first row of at least two rows of SOFC cells; a second outer sidewall depending from the combustion zone wall along the SOFC stack gas flow axis and enclosing a second row of SOFC cells of the at least two rows of SOFC cells; The first exterior side wall, the second exterior side wall and the combustion zone wall are formed as a unitary element; The first outer sidewall and the second outer sidewall receive heat from the combustion zone wall through heat conduction and radiate the heat to the inlet end of the SOFC stack.

10. The main housing wall assembly (8045) of claim 1 further comprising a burner assembly (8155) disposed within the combustion zone (8030) for providing a flow of start-up fuel (8152) to the combustion zone during cold start operation, wherein the combustion zone wall and the first outer side wall comprise integral elements.

11. The main housing wall assembly (8045) of claim 10, wherein: During startup operation, combustion of the startup fuel (8152) within the combustion zone (8030) generates thermal energy, which is absorbed by a portion of the integral element including the combustion zone wall, is thermally conducted from the portion of the integral element including the combustion zone wall by the integral element to the first side wall, is radiated to the outer surface of the cells including the SOFC stack, and is conducted and radiated to the cathode air in the cathode air manifold.

12. A solid oxide fuel cell (SOFC) system comprising: a main wall assembly (8045), the main wall assembly (8045) comprising a unitary element including a combustion region wall and one or more side walls, the unitary element being configured to enclose a cathode chamber (8055) therein and formed to provide one or more heat conductive paths extending between different regions of the main wall assembly; as well as An SOFC stack (8005) and a combustion zone, the SOFC stack (8005) and the combustion zone being enclosed by the main wall assembly in the cathode chamber, wherein a first portion of the integral element receives heat from the combustion zone and conducts the heat to a second portion of the integral element, and the second portion radiates heat to the first portion of the SOFC stack in the cathode chamber and transfers the heat to the cathode air flow passing through the surface of the main wall assembly outside the cathode chamber through heat exchange.

13. The solid oxide fuel cell (SOFC) system according to claim 12 further comprises a burner assembly (8155) disposed within the combustion zone (8030) for providing a flow of start-up fuel (8152) to the combustion zone during cold start operation.

14. The solid oxide fuel cell (SOFC) system according to claim 13, wherein: During startup operation, combustion of the startup fuel (8152) within the combustion zone (8030) generates thermal energy, which is absorbed by a portion of the integral element including the combustion zone wall, is thermally conducted from the portion of the integral element including the combustion zone wall to a portion of the integral element including the first side wall and is radiated to an outer surface of a cell including the SOFC stack, the first side wall depending from the combustion zone wall along the SOFC stack airflow axis.

15. A hot zone housing assembly (8042) for balancing temperature in a solid oxide fuel cell (SOFC) stack, the hot zone housing assembly comprising: a combustion zone wall defining a combustion zone around an outlet end of the SOFC stack for collecting anode fuel and cathode air exiting the SOFC stack, wherein the anode fuel and the cathode air combust in the combustion zone and generate heat such that the heat is absorbed by the combustion zone wall; and a sidewall depending from the combustion zone wall along the SOFC stack; and a thermally conductive core formed as a unitary element, the unitary element including the combustion zone wall and the side wall, the unitary element extending along a transverse width axis of the SOFC stack and extending from the transverse width axis along a gas flow axis of the SOFC stack, wherein: The combustion zone wall and the side wall define a cathode chamber in which the SOFC stack is disposed, wherein the combustion zone is disposed in an upper portion of the cathode chamber above the outlet end of the SOFC stack; The side wall has an end adjacent to an inlet end of the SOFC stack within the cathode chamber; the absorbed heat is transferred to the end of the side wall by conduction through the monolithic element; and The absorbed heat is radiated from the end of the SOFC stack to the inlet end to equalize temperature along the SOFC stack.

16. The hot zone housing assembly (8042) of claim 15, further comprising: a second sidewall depending from the combustion zone wall opposite the sidewall, wherein the monolithic element further comprises the second sidewall and extends along the gas flow axis of the SOFC stack; a hot zone housing base wall (8075) coupled to the side wall (8070) and the second side wall; as well as A first hot zone shell end wall and a second hot zone shell end wall (8080, 8085) are coupled to the combustion zone wall, the side wall and the second side wall to enclose the SOFC stack.

17. The hot zone housing assembly (8042) of claim 15, further comprising a cathode gas manifold disposed outside the hot zone housing, wherein inner surfaces of the combustion zone wall and the side wall face the combustion zone, and outer surfaces of the combustion zone wall and the side wall are opposite the inner surface of the surface for the cathode flow manifold.

18. The hot zone housing assembly (8042) of claim 15, wherein: The monolithic element has a thermal conductivity greater than 100 W / m°K at temperatures above 350°C.

19. The hot zone housing assembly (8042) of claim 15, wherein: The integral element is made of a material selected from the group consisting of copper, aluminum or aluminum alloy, molybdenum, aluminum copper, copper nickel alloy, and combinations thereof.

20. The hot zone housing assembly (8042) of claim 15, further comprising a fuel input manifold (8015) adjacent to an inlet end of the SOFC stack.

21. The hot zone housing assembly (8042) of claim 17, wherein: The SOFC stack is configured to receive cathode gas from an external air flow source, the cathode gas flows through the cathode gas manifold on the surface of the combustion zone wall and the side wall, flows from the cathode gas manifold into the cathode chamber, and reacts with the surface of the cathode layer of the fuel cell in the SOFC stack.

22. The hot zone housing assembly (8042) of claim 21, further comprising an intermediate housing, wherein the hot zone housing assembly is disposed within the intermediate housing, and wherein the cathode gas manifold is disposed outside the hot zone housing assembly and inside the intermediate housing.

23. The hot zone housing assembly of claim 15, wherein: The SOFC stack includes at least two rows of SOFC cells separated by the side wall.

24. The hot zone housing assembly of claim 15, wherein: The SOFC stack includes at least two rows of SOFC cells, and the hot zone housing assembly further includes: a first exterior sidewall depending from the combustion zone wall and enclosing a first row of SOFC cells of the at least two rows of SOFC cells with the sidewall; and a second outer side wall depending from the combustion zone wall and enclosing a second row of SOFC cells among the at least two rows of SOFC cells with the side wall, wherein the integral element extends along the combustion zone wall and each of the first outer side wall and the second outer side wall; and wherein the first outer side wall and the second outer side wall receive heat from the combustion zone wall by thermal conduction and radiate heat to the inlet end of the SOFC stack.

25. The hot zone housing assembly of claim 15, further comprising a burner assembly (8155) disposed within the combustion zone (8030) for providing a flow of start-up fuel (8152) to the combustion zone during cold start operation.

26. The hot zone housing assembly of claim 25, wherein: During startup operation, combustion of the startup fuel (8152) within the combustion zone (8030) generates thermal energy, which is absorbed by the combustion zone wall, thermally conducted from the combustion zone wall to the first side wall, and radiated to the outer surface of the cells comprising the SOFC stack.

27. A solid oxide fuel cell (SOFC) system comprising: an elongated SOFC stack disposed within a hot zone cavity along a gas flow axis, wherein the elongated SOFC stack has a top end and a bottom end, and wherein the top end and the bottom end are each disposed within a cathode cavity comprising the hot zone cavity; a combustion zone for combusting mixed cathode air and waste fuel disposed within the cathode chamber; and an integral element extending above the top end of the SOFC stack along a lateral width axis of the SOFC stack and along the gas flow axis of the stack adjacent to the SOFC cells of the SOFC stack; the integral element receiving heat from the hot zone cavity, conducting heat from the top end to the bottom end along the gas flow axis, and radiating heat radially to the bottom end relative to the gas flow axis, wherein the combustion zone is disposed in the cathode cavity between the top end of the SOFC stack and the integral element.

28. The solid oxide fuel cell (SOFC) system according to claim 27 further comprises a burner assembly (8155) disposed within the combustion zone (8030) for providing a flow of start-up fuel (8152) to the combustion zone during cold start operation.

29. The solid oxide fuel cell (SOFC) system according to claim 28, wherein: During startup operation, combustion of the startup fuel (8152) within the combustion zone (8030) generates thermal energy, which is absorbed by the combustion zone wall, thermally conducted from the combustion zone wall to the first side wall, and radiated to the outer surface of the cells comprising the SOFC stack.

30. A solid oxide fuel cell (SOFC) system comprising: an elongated SOFC stack disposed along an axis within the hot zone cavity, wherein the elongated SOFC stack has an outlet end and an inlet end; and a thermal block configured to receive heat from the hot zone cavity, conduct the heat along the axis from the outlet end to the inlet end, and radiate the heat radially relative to the axis to the inlet end; wherein the hot zone cavity has a bottom end adjacent to the inlet end and a top end in which the outlet end is disposed, and the thermal block encloses the top end of the hot zone cavity and extends along the axis toward the inlet end of the SOFC stack to enclose a side of the hot zone cavity; The thermal block comprises a thermally conductive core and an inner protective layer formed as a unitary component, wherein the inner protective layer comprises an inner surface facing the hot zone cavity and an outer surface opposite the inner surface, wherein the thermally conductive core is attached to the outer surface of the inner protective layer in thermally conductive contact with the inner protective layer, wherein the inner protective layer is formed and arranged to receive heat from the cathode chamber at a first position and conduct the heat to the heat-conducting core, and the heat-conducting core is formed and arranged to conduct heat from the top end of the heat block to other parts of the heat block and transfer thermal energy by radiation between the heat block and the SOFC stack.

31. The solid oxide fuel cell (SOFC) system according to claim 30, Also comprising a combustion zone disposed at the outlet end, the SOFC stack and the combustion zone being disposed within the hot zone cavity and enclosed by the thermal block; the combustion zone for combusting fuel during system startup and for combusting a mixture of spent cathode and anode gases during operation of the SOFC system, the combustion zone including a burner element for providing fuel and air flow into the combustion zone during system startup; and The inner protective layer is formed and arranged to receive heat from the combustion zone and conduct the heat to the thermally conductive core, and the thermally conductive core is formed and arranged to conduct heat away from the combustion zone from the outlet end toward the inlet end.

32. The solid oxide fuel cell (SOFC) system according to claim 30, wherein: At an operating temperature of the SOFC stack, a value of the thermal conductivity of the thermally conductive core is greater than a value of the thermal conductivity of the inner protective layer.

33. The solid oxide fuel cell (SOFC) system according to claim 30, further comprising an intermediate housing, wherein: The thermal block includes a hot zone housing assembly, the hot zone cavity being disposed within the hot zone housing assembly; The hot zone housing assembly is disposed within the intermediate housing, wherein an air gap is external to the hot zone housing assembly and internal to the intermediate housing; and The air gap forms a cathode air manifold for providing a cathode air flow to the cathode chamber, wherein the thermal block transfers thermal energy to the cathode air flowing through the cathode air manifold.

34. The solid oxide fuel cell (SOFC) system of claim 33, wherein the heat block has a thermal conductivity greater than a thermal conductivity of the intermediate casing at an operating temperature of the SOFC stack.

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