Fuel cell system glow plug
Patent Information
- Application Number
- JP2024118287
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-07-25
- Filing Date
- 2024-07-24
- Publication Date
- 2025-02-19
Smart Images
Figure 2025023899000001_ABST
Abstract
Description
[Technical field]
[0001] Aspects of the invention relate to components for electrochemical cell systems, and more particularly, to glow plugs for fuel cell systems. [Background technology]
[0002] Fuel cells, such as solid oxide fuel cells, are electrochemical devices that can convert energy stored in a fuel into electrical energy with high efficiency. High temperature fuel cells include solid oxide fuel cells and molten carbonate fuel cells. These fuel cells can operate using hydrogen and / or hydrocarbon fuels. There are classes of fuel cells, such as solid oxide regenerative fuel cells, that also allow for the reverse operation, such that oxidized fuel can be reduced back to unoxidized fuel using electrical energy as an input. Summary of the Invention
[0003] According to various embodiments, a glow plug includes a housing formed from a metal or metal alloy and having a first end with a first opening and an opposing second end with a second opening, a heating element having a working end extending through the first opening and exposed outside the first end of the housing and an opposing terminal end located inside the housing, a braze sealant assembly connected to the second end of the housing, first and second terminal wires extending through the braze sealant assembly and electrically connected to the terminal ends of the heating element, and a dielectric disk located inside the housing and surrounding a portion of the terminal ends of the heating element.
[0004] According to various embodiments, a catalytic partial oxidation (CPOx) reactor includes a CPOx housing surrounding a reaction zone, a catalyst located within the reaction zone, and a glow plug extending through the CPOx housing and into the reaction zone and located upstream of the catalyst relative to the direction of fuel flow through the CPOx reactor.
[0005] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate exemplary embodiments of the invention and, together with the general description above and the detailed description below, serve to explain features of the invention. [Brief description of the drawings]
[0006] [Figure 1] FIG. 1 is a schematic diagram of a fuel cell system according to various embodiments of the present disclosure. [Figure 2AB] 2A is a cross-sectional view showing components of a hot box of the system of FIG. 1 according to various embodiments of the present disclosure, and FIG. 2B shows an enlarged portion of the system of FIG. 2A according to various embodiments of the present disclosure. [Figure 2C] FIG. 2C is a three-dimensional cutaway view of the central column of the system of FIG. 2A according to various embodiments of the present disclosure. [Figure 2D] FIG. 2D is a perspective view of an anode hub structure positioned below the central column of the system of FIG. 2A according to various embodiments of the present disclosure. [Figure 3A] FIG. 3A is a perspective view of a glow plug according to various embodiments of the present disclosure. [Figure 3B] FIG. 3B is a partial perspective view showing the internal components of the glow plug of FIG. 3A. [Figure 4A] FIG. 4A is a perspective view of a glow plug with the braze sealant assembly removed. [Figure 4B] FIG. 4B is a perspective view of the braze sealant assembly. [Figure 4C] FIG. 4C is a perspective view of the braze sealant assembly. [Figure 4D] FIG. 4D is an exploded view of the braze sealant assembly. [Figure 4E] FIG. 4E is a cross-sectional view of the braze sealant assembly. [Figure 5A]FIG. 2 is a perspective view of a glow plug and first and second temperature sensors inserted into a CPOx reactor according to various embodiments of the present disclosure. [Figure 5B] 1 is a schematic cross-sectional view of a CPOx reactor including a glow plug and a temperature sensor according to various embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0007] Various embodiments will now be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References to specific examples and implementations are made for illustrative purposes and are not intended to limit the scope of the invention or the claims.
[0008] Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. Examples of when such ranges are expressed include from one particular value and / or to the other particular value. In some embodiments, a value "about X" may include the value + / - 1% X. It will be further understood that the endpoints of each of the ranges are significant in relation to the other endpoint, and independently of the other endpoint.
[0009] FIG. 1 is a schematic diagram of a solid oxide fuel cell (SOFC) system 10 according to various embodiments of the present disclosure. Referring to FIG. 1, the system 10 comprises a hot box 100 and various components disposed within or adjacent thereto. The hot box 100 can include a stack (e.g., a fuel stack) 102 including alternating fuel cells, such as solid oxide fuel cells, and interconnects. Thus, in one embodiment, the stack 102 can include a SOFC stack. One solid oxide fuel cell of the stack 102 includes a ceramic electrolyte, such as yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (SSZ), scandia- and ceria-stabilized zirconia, or scandia-, yttria- and ceria-stabilized zirconia, an anode electrode, such as nickel-YSZ, nickel-SSZ, or nickel-doped ceria cermet, and a cathode electrode, such as lanthanum strontium manganite (LSM). The interconnect can be a metal alloy interconnect, such as a chromium-iron alloy interconnect. The stacks 102 may be internally or externally manifolded for fuel and may be arranged on top of each other in multiple rows.
[0010] The hot box 100 may also include an anode recuperative heat exchanger 110, a cathode recuperative heat exchanger 120, an anode tail gas oxidizer (ATO) 150, an anode exhaust cooling heat exchanger 140, a splitter 158, a vortex generator 159, and a water injector 160. The system 10 may also include a catalytic partial oxidation (CPOx) reactor 200, a mixer 210, a CPOx blower 104 (e.g., an air blower), a main air blower 108 (e.g., a system blower), and an anode recirculation blower 106, which may be located outside the hot box 100. However, the present disclosure does not limit each of the components to a particular location with respect to the hot box 100.
[0011] The CPOx reactor 200 can include a reaction zone 201 that includes an oxidation catalyst configured to partially oxidize a fuel. During system start-up, a heat source can be used to initiate an oxidation reaction in the CPOx reactor 200, which may also be referred to as "ignition." In various embodiments, the system 10 can include a glow plug 500 configured to provide heat to initiate ignition of the CPOx reactor 200. In particular, one end of the glow plug 500 can be inserted into the reaction zone 201 and sealed within an opening in the housing 202 of the CPOx reactor 200, as shown in FIG. 5B. The glow plug 500 is described in more detail below with respect to FIGS. 3A, 3B, and 4A-4D.
[0012] The CPOx reactor 200 receives a fuel inlet stream from a fuel inlet 30 through a fuel conduit 300A. The fuel inlet 30 may be a fuel tank or a utility natural gas line with a valve that controls the amount of fuel provided to the CPOx reactor 200. The CPOx blower 104 may provide air to the CPOx reactor 200 during system start-up. Fuel and / or air may be provided to the mixer 210 by a fuel conduit 300B. Fuel (e.g., the fuel inlet stream) flows from the mixer 210 through a fuel conduit 300C to the anode recuperator 110. The fuel is heated in the anode recuperator 110 by a portion of the fuel exhaust, and then the fuel flows from the anode recuperator 110 through a fuel conduit 300D to the stack 102.
[0013] The main air blower 108 can be configured to supply an air flow (e.g., an air inlet flow) to the anode exhaust cooler 140 through air conduit 302A. The air flows from the anode exhaust cooler 140 through air conduit 302B to the cathode recuperator 120. The air is heated by the ATO exhaust in the cathode recuperator 120. The air flows from the cathode recuperator 120 to the stack 102 through air conduit 302C.
[0014] An anode exhaust stream (e.g., a fuel exhaust stream) generated in the stack 102 is provided to the anode recuperator 110 through an anode exhaust conduit 308A. The anode exhaust may include unreacted fuel and may also be referred to herein as fuel exhaust. The anode exhaust may be provided from the anode recuperator 110 to the splitter 158 by an anode exhaust conduit 308B. A first portion of the anode exhaust may be provided from the splitter 158 to the water injector 160 and the anode exhaust conduit 308C to the anode exhaust cooler 140. A second portion of the anode exhaust may be provided from the splitter 158 to the ATO 150 through an anode exhaust conduit 308D. The first portion of the anode exhaust may heat an air inlet stream in the anode exhaust cooler 140 and then provided from the anode exhaust cooler 140 to the mixer 210 through an anode exhaust conduit 308E. The anode recirculation blower 106 may be configured to move the anode exhaust through an anode exhaust conduit 308E, as described below.
[0015] Cathode exhaust generated in the stack 102 flows through exhaust conduit 304A to the ATO 150. A vortex generator 159 can be disposed in the exhaust conduit 304A and can be configured to swirl the cathode exhaust. An anode exhaust conduit 308D can be fluidly connected to the vortex generator 159 or to the cathode exhaust conduit 304A or the ATO 150 downstream of the vortex generator 159. The swirled cathode exhaust can be mixed with a second portion of the anode exhaust provided by the splitter 158 before being provided to the ATO 150. The mixture can be oxidized in the ATO 150 to generate the ATO exhaust. The ATO exhaust flows from the ATO 150 to the cathode recuperator 120 through exhaust conduit 304B. The exhaust flows from the cathode recuperator out of the hot box 100 through exhaust conduit 304C.
[0016] During system startup, a heat source can be used to initiate an oxidation reaction within the ATO 150. In various embodiments, the system 10 can include an ATO glow plug 500' configured to heat the fuel mixture supplied to the ATO 150. The ATO glow plug 500' can be fluidly connected upstream of the ATO 150 and sealed within an opening in the housing of the hot box 100.
[0017] Water flows from a water source 316, such as a water tank or water line, through a water conduit 306 to the water injector 160. The water injector 160 injects water directly into a first portion of the anode exhaust, which is fed into the anode exhaust conduit 308C. Heat from a first portion of the anode exhaust (also referred to as the recirculated anode exhaust stream) fed into the anode exhaust conduit 308C causes the water to evaporate and generate water vapor. The water vapor mixes with the anode exhaust and the resulting mixture is fed to the anode exhaust cooler 140. This mixture is then fed from the anode exhaust cooler 140 through the anode exhaust conduit 308E to the mixer 210. The mixer 210 is configured to mix the water vapor and the first portion of the anode exhaust with fresh fuel (i.e., the fuel inlet stream). This humidified fuel mixture can then be heated in the anode recuperator 110 by the anode exhaust before being fed to the stack 102. The system 10 may also include one or more fuel reforming catalysts 112, 114, and 116 located within and / or downstream of the anode recuperator 110. The reforming catalyst(s) reform the humidified fuel mixture before it is delivered to the stack 102.
[0018] The system 10 may further include a system controller 225 configured to control various elements of the system 10. The controller 225 may include a central processing unit configured to execute stored instructions. For example, the controller 225 may be configured to control fuel and / or air flow through the system 10 according to the fuel composition data.
[0019] Figure 2A is a cross-sectional view showing components of hot box 100 of system 10 of Figure 1, and Figure 2B shows an enlarged portion of Figure 2A. Figure 2C is a three-dimensional cutaway view of a central column 400 of system 10 according to various embodiments of the present disclosure, and Figure 2D is a perspective view of anode hub structure 60 disposed within hot box base 101 in which column 400 may be disposed.
[0020] 2A-2D, the fuel cell stack 102 may be arranged around a central column 400 in the hot box 100. For example, the stack 102 may be arranged in a ring configuration around the central column 400 and positioned on the hot box base 101. The column 400 may include an anode recuperator 110, an ATO 150, and an anode exhaust cooler 140. In particular, the anode recuperator 110 is disposed radially inward of the ATO 150, and the anode exhaust cooler 140 is mounted above the anode recuperator 110 and the ATO 150. An anode exhaust cooler inner core insulation 140A may be located between the fuel conduit 300C and the combination of the anode exhaust cooler 140 and the bellows 142 below the anode exhaust cooler 140. In one embodiment, an oxidation catalyst 112 and / or a hydrogenation catalyst 114 may be located in the anode recuperator 110. A reforming catalyst 116 may also be located at the bottom of the anode recuperator 110 as a steam methane reforming (SMR) insert.
[0021] The ATO 150 comprises an outer cylinder 152 positioned around the outer wall of the anode recuperator 110. Optionally, an ATO inner cylinder 154 may surround an ATO insulation 156. Thus, the insulation 156 may be located between the anode recuperator 110 and the ATO 150. An ATO oxidation catalyst may be located in the space between the outer cylinder 152 and the ATO insulation 156. An ATO thermocouple feedthrough 161 extends through the anode exhaust cooler 140 to the top of the ATO 150. The temperature of the ATO 150 may thereby be monitored by inserting one or more thermocouples (not shown) through the feedthrough 161.
[0022] The anode hub structure 60 may be positioned below the anode recuperator 110 and the ATO 150 and above the hot box base 101. The anode hub structure 60 is covered by an ATO skirt 153. A vortex generator 159 and a fuel exhaust splitter 158 are located above the anode recuperator 110 and the ATO 150 and below the anode exhaust cooler 140. An ATO glow plug 500' may be located near the bottom of the ATO 150 to initiate oxidation of the stack fuel exhaust in the ATO during start-up.
[0023] The anode hub structure 60 is used to uniformly distribute fuel from the central column 400 to the fuel cell stacks 102 arranged around the central column 400. The anode hub structure 60 comprises a grooved cast base 62 and a "spider" hub with fuel inlet conduits 300D and anode exhaust conduits 308A. Each pair of conduits 300D, 308A connects to a fuel cell stack 102 (or a column of fuel cell stacks 102). Additionally, the anode side cylinders (e.g., anode recuperator 110 inner and outer cylinders, and ATO outer cylinder 152) are welded or brazed into the grooves of the base 62 to provide a uniform volumetric cross-section for flow distribution as described below.
[0024] 2A and 2B, air enters the top of the hot box 100 and then flows into the cathode recuperator 120 where it is heated by the ATO exhaust exhausted from the ATO 150. The ATO exhaust then flows through the cathode recuperator 120 and exits the hot box 100.
[0025] In the case of a solid oxide fuel cell, air then flows through the stack 102 and oxygen ions diffuse from the cathode electrode, through the fuel cell electrolyte to the anode electrode to react with fuel (i.e., the fuel inlet stream) supplied to the anode electrode of the fuel cell from the anode hub structure 60. The air exhaust flows from the stack 102 and then swirls through the vanes of the vortex generators 159 before entering the ATO 150.
[0026] The splitter 158 can direct a second portion of the fuel exhaust exiting the top of the anode recuperator 110 through an opening (e.g., a slit) in the splitter and into the swirled air exhaust (e.g., into the vortex generator 159, or into exhaust conduit 304A downstream of the vortex generator 159, or into the ATO 150). Thus, the fuel and air exhaust can mix before entering the ATO 150.
[0027] Glow plugs Figure 3A is a perspective view of a glow plug 500 according to various embodiments of the present disclosure, and Figure 3B is a partial perspective view showing internal components of the glow plug 500 of Figure 3A.
[0028] 3A and 3B, the glow plug 500 may be hermetically sealed and may have high temperature, voltage, and thermal cycle stability. For example, the glow plug 500 may be configured to withstand temperatures of at least 800° C. for a period of at least 25,000 hours.
[0029] The glow plug 500 may include a housing 510, a heating element 520, a first terminal wire 522, a second terminal wire 524, a dielectric disk 530, and a brazed sealant assembly 540. The housing 510 may be a hollow cylindrical structure including a tapered first end 512E including a first opening 512 and an opposite second end 514E including a second opening 514 to an interior volume of the housing. An optional thread 513 may surround the heating element between the first end 512E of the housing 510 and the tip of the heating element 520. A connection groove 516 may be formed in an exterior surface of the housing 510 adjacent the first opening 512. The connection groove 516 may be configured to facilitate connection of the glow plug 500 to a component of a fuel cell system. For example, the connecting groove 516 may be fitted to a side wall of the housing 202 of the CPOx reactor 200 if the glow plug 500 is used in the CPOx reactor 200, or to a side wall of the hot box 100 housing if the glow plug 500 is used as an ATO glow plug 500'. The housing 510 may be formed from a high temperature stable metal or metal alloy, such as stainless steel. For example, the housing 510 may be formed from a chromium-nickel containing stainless steel alloy, such as stainless steel 316, stainless steel 310, or a nickel-chromium alloy, such as Inconel 625.
[0030] The heating element 520 may be a resistive heating element extending through the first opening 512 such that a working end 520A of the heating element 520 is exposed outside the housing 510 and an opposite terminal end 520B of the heating element 520 is disposed inside the housing 510. The heating element 520 may include a heating core disposed within a dielectric cladding or matrix. In some embodiments, the heating core may include a conductive material. The conductive material may include a metal or metal alloy, such as a metal silicide, e.g., molybdenum disilicide (MoSi2). The cladding or matrix may include a dielectric material, such as silicon nitride. In one embodiment, the core is surrounded by the cladding. In another embodiment, the conductive material of the core is dispersed within a dielectric matrix to make the heating element 520 conductive. The heating element 520 may be configured to have low creep characteristics during thermal cycling. The working end 520A generates a sufficient amount of heat (e.g., is heated until it emits light) to initiate a catalytic reaction within the CPOx reactor 200 or ATO 150 when a sufficient voltage, such as 20V-30V, such as about 24V, is applied to the heating element 520.
[0031] The heating element 520 can extend through a central opening in the dielectric disk 530. The dielectric disk 530 is disposed adjacent the first opening 512 in the first end 512E of the housing 510 such that the dielectric disk 530 supports and electrically insulates the terminal end 520B of the heating element 520. The dielectric disk 530 can be formed from a dielectric ceramic material, such as alumina.
[0032] The heating element 520 (e.g., a heating core) can be electrically connected to a first terminal wire 522 and a second terminal wire 524 configured to supply a voltage or current to the heating element. In particular, the first terminal wire 522 and the second terminal wire 524 can be brazed to the terminal end 520B of the heating element 520. The terminal wires 522, 524 can be formed from a metal having high electrical conductivity and thermal stability, such as nickel. The dielectric disk 530 prevents or reduces hot gases from reaching the brazed joint connecting the terminal wires 522, 524 and the heating element 520. The dielectric disk 530 acts as an insulator for the brazed wire joint. Because the brazed wire joint is close to the working end 520A of the heating element 520 that emits light during operation, the dielectric disk 530 provides sufficient dielectric gap to prevent short circuits.
[0033] Additionally, the terminal wires 522, 524 may be at least partially surrounded by respective dielectric sheaths 526, 528, thereby preventing short circuits between the two terminal wires 522, 524 and between the housing 510 and one or both of the terminal wires 522, 524. The sheaths 526, 528 may be formed from a dielectric ceramic material, such as alumina.
[0034] The housing 510 may also be filled with a potting compound 518 configured to encapsulate the terminal wires 522, 524. In particular, the potting compound 518 and / or the sheaths 526, 528 may be configured to prevent electrical contact between the two terminal wires 522, 524 and between the housing 510 and one or more of the terminal wires 522, 524. For example, the potting compound 518 may be an electrically insulating resin such as an epoxy resin or another electrically insulating material such as an alumina or zirconia potting compound, and may protect the terminal wires 522, 524 from shock and vibration and may be configured to prevent fluids from entering the housing 510.
[0035] The terminal wires 522, 524 may be disposed in the second opening 514 and extend through a braze sealant assembly 540, which may be attached to the second end 514E of the housing 510. The braze sealant assembly 540 may be welded to the housing 510. For example, the braze sealant assembly 540 may be laser welded to a circular edge surface of the second end 514E of the housing 510.
[0036] Figure 4A is a perspective view of the glow plug 500 with the braze sealant assembly 540 removed. Figures 4B and 4C are perspective views of the braze sealant assembly 540. Figure 4D is an exploded view of the braze sealant assembly 540, and Figure 4E is a cross-sectional side view of the braze sealant assembly 540.
[0037] 4B-4E, the brazed sealant assembly 540 can include a cap 550, a first bushing 562, a second bushing 564, and a seal ring 570. The cap 550 can be formed from a dielectric ceramic material such as alumina. The cap 550 can include a recess 552 (i.e., a step in the outer diameter of the cap), a first through hole 554, and a second through hole 556. The recess 552 can extend around the periphery of the cap 550 and can be configured to receive the seal ring 570 such that the seal ring 570 is mounted over the recess and brazed to two orthogonal (i.e., perpendicular) surfaces of the cap 550. The first through hole 554 can include a relatively large diameter portion 554A that is larger than the outer diameter of the first bushing 562 and a relatively small diameter portion 554B for the feedthrough of the terminal wire 522. The second through hole 556 may include a relatively large diameter portion 556A that is larger than the outer diameter of the second bushing 564, and a relatively small diameter portion 556B for feeding through the terminal wire 524. The small diameter portions 554B, 556B are smaller in diameter than the large diameter portions 554A, 556A, respectively.
[0038] The larger diameter portions 554A, 556A can be configured to receive the respective ends of the first and second bushings 562, 564. The first and second bushings 562, 564 are brazed to the inner surfaces of the larger diameter portions 554A, 556A of the first and second through holes 554, 556, respectively. In one embodiment, the first and second bushings 562, 564 do not extend into the smaller diameter portions 554B, 556B of the respective first and second through holes 554, 556. The smaller diameter portions 554B, 556B can be configured to receive the first and second terminal wires 522, 524, respectively. In some embodiments, the cap 550 can include a protrusion 558 having a flat surface in which the second through hole 556 is formed. In particular, the cap 550 may have a stepped structure such that the second through-hole 556 is formed longer than the first through-hole 554 .
[0039] The first and second bushings 562, 564 may be hollow tubular structures configured to receive the first and second terminal wires 522, 524, respectively. In some embodiments, the first and second bushings 562, 564 and the seal ring 570 may be formed from a nickel-cobalt iron alloy. For example, the first and second bushings 562, 564 and the seal ring 570 may be formed from a low coefficient of thermal expansion (CTE) alloy. In particular, the alloy may include, by weight, about 29% Ni, about 17% Co, less than about 0.01% C, about 0.2% Si, about 0.3% Mn, and the balance Fe. However, the relative amounts of these components may be adjusted to achieve a desired coefficient of thermal expansion (CTE).
[0040] In various embodiments, the seal ring 570 and the bushings 562, 564 can be attached to the cap 550 using a brazing material 580. In particular, the seal ring 570 can be brazed to the recess 552 and the bushings 562, 564 can be brazed to the through holes 554, 556 of the cap 550 using an active metal brazing process, such as a high temperature vacuum brazing process. Active metal brazing allows for joining metal to ceramic without metallization using a brazing material 580, such as an active brazing alloy including silver, copper, and / or titanium. For example, a suitable active brazing alloy can include, by weight, about 72% Ag and about 28% Cu, or about 63.0% Ag, about 35.25% Cu, and about 1.75% Ti.
[0041] The recess 552 can increase the contact area between the cap 550 and the sealing ring 570. In one embodiment shown in FIG. 4E, the sealing ring 570 is brazed to both the axial surface 552A and the perpendicular radial surface 552R of the recess 552. Thus, the recess 552 can allow for a reduction in the thickness of the sealing ring 570 without sacrificing bond strength, which can beneficially minimize thermal expansion and / or contraction of the sealing ring 570, such as during brazing and / or thermal cycling.
[0042] The protrusions 558 can be configured to reduce mixing of the braze material 580 used to attach the bushings 562, 564 to the cap 550. In particular, during brazing, the braze material 580 may spill out of the through holes 554, 556 onto the surface of the cap 550. The protrusions 558 may be configured to prevent contact between the spilled braze material, thereby preventing the spilled braze material from electrically shorting the terminal wires 522, 524.
[0043] 5A is a perspective view of a glow plug 500 and first and second temperature sensors 209A and 209B inserted in the CPOx reactor 200, and FIG. 5B is a cross-sectional side view of the CPOx reactor 200 including the glow plug 500 and temperature sensors 209A, 209B, according to various embodiments of the present disclosure. With reference to FIGS. 3A-5B, the CPOx reactor 200 can include a catalyst 204, a glow plug opening 206, a first and second sensor opening 208A and 208B, a fuel inlet 212, and a fuel outlet 214. The catalyst 204 can be in the form of a porous catalyst bed or a porous substrate (e.g., a porous monolith) located in the reaction zone 201 inside the CPOx reactor 200. Alternatively or additionally, the catalyst 204 can be coated on the interior sidewalls of the CPOx reactor 200 within the reaction zone 201. Glow plug 500 can be inserted into glow plug opening 206 such that working end 520A of heating element 520 protrudes into reaction zone 201 upstream of catalyst 204 relative to the fuel and air flow direction from fuel inlet 212 to fuel outlet 214. Fuel inlet 212 is fluidly connected to fuel conduit 300A and fuel outlet 214 is fluidly connected to fuel conduit 300B.
[0044] The first temperature sensor 209A and the second temperature sensor 209B may comprise any suitable temperature sensors, such as thermocouples. The first temperature sensor 209A may be inserted into the first sensor opening 208A such that an operative end of the first temperature sensor 209A is located within the reaction zone 201 upstream of the catalyst 204. The second temperature sensor 209B may be inserted into the second sensor opening 208B such that an operative end of the second temperature sensor 209B is located within the reaction zone 201 downstream of the catalyst 204.
[0045] The glow plug 500 and temperature sensor(s) are located upstream and / or downstream of the catalyst 204 rather than being inserted within the catalyst 204. This placement of the glow plug and temperature sensor(s) eliminates or reduces dead zones within the catalyst and reduces coking within the CPOx reactor 200.
[0046] During start-up of system 10, power may be supplied to glow plug 500 to heat working end 520A, thereby initiating a catalytic reaction of fuel and air flowing through fuel inlet 212 into catalyst 204 or ATO 150 of CPOx reactor 200. Thus, during operation, working end 520A of heating element 520 may generate and / or be exposed to temperatures of 800° C. or greater.
[0047] In one embodiment, the seal ring 570 and bushings 562, 564 of the braze sealant assembly 540 may have a maximum temperature rating of about 400° C. and the braze material 580 may have a maximum temperature rating of about 500° C., which are below the operating temperature of the working end 520A of the heating element 520. However, the housing 510 may separate the braze sealant assembly 540 from the reaction zone 201 by a distance ranging from about 75 mm to about 150 mm, such as about 100 mm. Thus, the braze sealant assembly 540 may only be exposed to temperatures of about 300° C. or less, thereby protecting the braze sealant assembly 540 from damage due to excessive temperatures.
[0048] Additionally, the CTE of the cap 550, which may be formed from alumina, may be very close to the CTE of the seal ring 570 and bushings 562, 564, which may be formed from a nickel-cobalt iron alloy. As a result, the residual stresses imposed on the glow plug 500 during thermal cycling may be very low, thereby protecting the brazed joints of the braze sealant assembly 540 from damage, such as cracking, during thermal cycling.
[0049] The fuel cell systems of the disclosed embodiments are designed to reduce greenhouse gas emissions and have a positive impact on the climate.
[0050] The above description of the disclosed embodiments is provided to enable those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art. Moreover, the general principles defined herein can be applied to other embodiments without departing from the scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A glow plug, comprising: a housing comprising a metal or metal alloy and having a first end with a first opening and an opposing second end with a second opening; a heating element extending through the first opening and having a working end exposed outside the first end of the housing and an opposing terminal end located inside the housing; a braze sealant assembly connected to the second end of the housing; a first terminal wire and a second terminal wire extending through the braze sealant assembly and electrically connected to the terminal end of the heating element; a dielectric disk located inside the housing and surrounding a portion of the terminal end of the heating element; The glow plug.
2. The braze sealant assembly comprises: a seal ring connected to the second end of the housing, the seal ring comprising a metal or metal alloy; a cap connected to the seal ring, the cap including a ceramic material; a first bushing and a second bushing connected to the cap, the first bushing and the second bushing comprising a ceramic material; The glow plug of claim 1 .
3. 3. The glow plug of claim 2, wherein the seal ring is welded to the second end of the housing.
4. The glow plug of claim 2 , wherein the cap is brazed to the seal ring.
5. The cap includes a recess. the seal ring is mounted over the recess such that the seal ring is brazed to two surfaces of the cap; 5. The glow plug according to claim 4.
6. the cap, the first bushing, and the second bushing comprise alumina; 6. The glow plug of claim 5, wherein said seal ring comprises a nickel-cobalt iron alloy.
7. The glow plug of claim 4 , wherein the first bushing and the second bushing are brazed to the cap.
8. the seal ring and the first and second bushings are brazed to the cap using an active brazing alloy; The active brazing alloy is Silver and copper, or Silver, copper and titanium, 8. The glow plug of claim 7, comprising:
9. The glow plug of claim 7 , wherein the cap includes a first through hole and a second through hole.
10. the cap has a stepped structure such that the second through hole is longer than the first through hole; the stepped structure is configured to prevent electrical shorting of the first terminal wire and the second terminal wire by a brazing material used to braze the first bushing and the second bushing to the cap; The first through hole and the second through hole each have a relatively large diameter portion and a relatively small diameter portion, the first terminal wire extends through the first bushing, through the first through hole, and to the terminal end of the heating element; the second terminal wire extends through the second bushing, through the second through hole, and to the terminal end of the heating element; The first bushing and the second bushing are brazed to the inner surfaces of the large diameter portions of the first through hole and the second through hole.
10. The glow plug according to claim 9.
11. a first sheath and a second sheath at least partially surrounding the first terminal wire and the second terminal wire, respectively, within the housing; the housing comprises stainless steel; the dielectric disk and the first and second sheaths comprise a ceramic material.
2. The glow plug according to claim 1.
12. The heating element comprises: a core comprising molybdenum disilicide; a cladding or matrix surrounding the core and comprising silicon nitride; The glow plug of claim 1 , comprising:
13. The glow plug of claim 1 further comprising a potting material located within said housing.
14. 1. A fuel cell system comprising: The glow plug according to claim 1 ; a fuel cell stack disposed within the hot box; The fuel cell system comprising:
15. a catalytic partial oxidation (CPOx) reactor comprising a CPOx housing surrounding a reaction zone and a catalyst located within the reaction zone; 15. The fuel cell system of claim 14, wherein the glow plug extends through the CPOx housing into the reaction zone and is located upstream of the catalyst relative to a fuel flow direction through the CPOx reactor.
16. a first temperature sensor inserted into the CPOx reactor upstream of the catalyst; a second temperature sensor inserted into the CPOx reactor downstream of the catalyst; The fuel cell system of claim 15 further comprising:
17. an anode tail gas oxidizer (ATO) located within the hot box; 15. The fuel cell system of claim 14, wherein the working end of the glow plug is configured to heat a mixture of fuel exhaust and air that is provided into the ATO.
18. 1. A catalytic partial oxidation (CPOx) reactor comprising: a CPOx housing surrounding the reaction zone; a catalyst located within the reaction zone; a glow plug extending through the CPOx housing into the reaction zone and positioned upstream of the catalyst relative to the direction of fuel flow through the CPOx reactor; The CPOx reactor comprising:
19. a first temperature sensor inserted in the reaction zone upstream of the catalyst; a second temperature sensor inserted in the reaction zone downstream of the catalyst; 20. The CPOx reactor of claim 18 further comprising:
20. 1. A fuel cell system comprising: A CPOx reactor according to claim 18; a fuel cell stack disposed within the hot box; The fuel cell system comprising: