Fuel inlet valve systems for controlling fuel flow to fuel cell columns of a fuel cell system

Abstract

Fuel inlet valve systems are that control fuel flow to fuel cell columns are disclosed. They include a valve with a valve stem coupled to a captive linear actuator that adjusts the position of the valve head based on actuator signals. The position of the valve head controls the fuel flow between the fuel inlet and the fuel cell column. The actuator signals are sent by a control system that may adjust the fuel flow to any of the fuel cell columns based on health of the fuel cell column, rebalancing the fuel cell system, or the like. The valve head includes a valve face that adjusts fuel flow based on its position with respect to a valve seat or a ceramic ball that adjusts fuel flow based on its position with respect to a metallic ring inside the fuel conduit leading to the fuel cell column.

Description

FUEL INLET VALVE SYSTEMS FOR CONTROLLING FUEL FLOW TO FUEL CELL COLUMNS OF A FUEL CELL SYSTEMInventors: Joshua Ming Rodrigo Orta Guerra Karanpal Bhangu Adil Abbas Ashary Joshua Baime Michael PetruchaCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 669,578, titled “FUEL INLET VALVE SYSTEM FOR CONTROLLING FUEL FLOW TO FUEL CELL COLUMNS OF A SOLID OXIDE FUEL SYSTEM,” filed July 10, 2024, and U.S. Provisional Application No. 63 / 704,789, titled “FUEL INLET VALVE SYSTEM FOR CONTROLLING FUEL FLOW TO FUEL CELL COLUMNS OF A SOLID OXIDE FUEL SYSTEM,” filed October 8, 2024, the contents of each of which are incorporated herein by reference in their entireties for all purposes.BACKGROUND

[0002] Fuel cell systems, including solid oxide fuel cell (SOFC) systems, provide sustainable, resilient power. SOFC systems include electrochemical devices which can convert energy stored in fuels to electrical energy with high efficiency. Overall efficiency is one of the main factors that determines how long an SOFC system can stay on and in service. Many SOFC systems include multiple fuel cell columns in a single hotbox, where each column can function as an independent electrochemical device. In current hotbox designs, a single weak column can impact overall efficiency such that the one weak column may reduce system efficiency below minimum requirements. In such instances, a single weak column may require shutdown of the entire hotbox. Accordingly, improvements are needed.SUMMARY

[0003] To address the issues described above, described herein is a SOFC system having intelligent fuel shutoff for individual fuel cell columns with rebalancing logic to ensure maximum lifespan of SOFC hotboxes and systems. The SOFC system includes logic (e.g., software or firmware) that monitors the status of each fuel cell column of the SOFC system and the SOFC system overall. The SOFC system further includes a fuel inlet valve for each fuel cell column that is adjusted with a signal to an actuator controlling the fuel inlet valve. When needed, command signals are sent to the actuator for the identified fuel cell column to set the valve to a desired position for the identified fuel cell column. The remaining fuel cell columns are monitored and, in some embodiments, additional command signals are sent for rebalancing the remaining fuel cell columns to achieve optimal performance. For example, the fuel inlet valves may be used to modify the fuel flow by sending control signals to the relevant actuator to partially close a valve, setting a fuel flow that is anywhere from 100% (i.e., fully open or on) to 0% (i.e., fully closed or off).

[0004] One general aspect includes a fuel cell system having a plurality of electrochemical fuel cell columns and a control system. Each electrochemical fuel cell column includes one or more sensors and a fuel inlet valve system configured to control fuel flow to the electrochemical fuel cell column. The fuel inlet valve system includes a valve having a valve head disposed within a valve chamber and a valve stem coupled to the valve head. The valve is configured to control fuel flow between a fuel inlet tube and a fuel conduit based on a position of the valve head within the valve chamber. The fuel conduit is configured to deliver fuel to the electrochemical fuel cell column coupled to the fuel conduit. Each electrochemical fuel cell column also includes a captive linear actuator coupled to the valve stem. The captive linear actuator is configured to adjust the position of the valve head based one or more actuator signals from the control system. The control system includes a processing system and a memory storing instructions that are executable by the processing system. When in operation, the control system receives health signals from the one or more sensors of each of the plurality of electrochemical fuel cell columns, analyzes the health signals to determine a status of each of the plurality of electrochemical fuel cell columns, and in response to determining that a performance of a first electrochemical fuel cell column of the plurality of electrochemical fuel cell columns falls below a threshold value, transmits one or more actuator signals to the captive linear actuators of one ormore fuel inlet valve systems to modify the fuel flow to the one or more electrochemical fuel cell columns. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0005] Implementations of this aspect may include one or more of the following features. In some embodiments, the valve head includes a valve face, and the valve is configured to control the fuel flow between the fuel inlet tube and the fuel conduit based on a position of the valve face with respect to a valve seat within the valve chamber.

[0006] In some embodiments, the valve head includes a ceramic ball, and the ceramic ball is configured to control the fuel flow between a fuel inlet tube and a fuel conduit based on a position of the ceramic ball with respect to a metallic ring disposed inside the fuel conduit.

[0007] In some embodiments, each fuel inlet valve system includes a threaded coupler made of a thermally insulative material and configured to couple the captive linear actuator and the valve stem. In some embodiments, each fuel inlet valve system includes an insulation chamber surrounding at least the threaded coupler and includes insulation material.

[0008] In some embodiments, each fuel inlet valve system includes valve bellows disposed about the valve stem and configured to stabilize linear motion of the valve stem and restrict gaseous and liquid flow from an upper portion of the valve chamber toward the captive linear actuator. In some embodiments, each fuel inlet valve system includes an insulation chamber surrounding at least the valve bellows and includes insulation material.

[0009] In some embodiments, each fuel inlet valve system includes an insulation chamber surrounding the captive linear actuator and includes insulation material.

[0010] In some embodiments, each fuel inlet valve system includes an insulation chamber surrounding at least a lower portion of the valve chamber through which the valve stem travels and includes insulation material.

[0011] In some embodiments, each fuel inlet valve system includes a first link having a first end and a second end, the first end of the first link coupled to the valve stem and the second end of the first link coupled via a pivot joint to a first end of a second link. The second link has the first end and a second end, and the second end of the second link is coupled to the captive linear actuator. The captive linear actuator travels in a first linear motion, the valve travels in a second linear motion, and the first linear motion is orthogonal to the second linear motion.

[0012] In some embodiments, the captive linear actuator includes stepper motor control. In some embodiments, the one or more actuator signals may include a signal to the captive linear actuator of the first fuel inlet valve system instructing the captive linear actuator to close the valve connected to the first electrochemical fuel cell column to disable fuel flow to the first electrochemical fuel cell column. In some embodiments, after the captive linear actuator closes the valve of the first fuel inlet valve system, the control system analyzes current health signals from the one or more sensors of each active electrochemical fuel cell column of the plurality of electrochemical fuel cell columns and transmits one or more additional signals to the captive linear actuators of one or more active fuel inlet valve systems to balance thermal activity and output of the active electrochemical fuel cell columns.

[0013] In some embodiments, the captive linear actuator of each of the plurality of fuel inlet valve systems is mounted such that the captive linear actuator is positioned below a bottom surface of a hot box base plate.

[0014] In some embodiments, each fuel inlet valve system includes a fan configured to cool the captive linear actuator.

[0015] Another general aspect includes a computer-implemented method. The computer - implemented method includes receiving health signals from one or more sensors of each of a plurality of electrochemical fuel cell columns of a fuel cell system, analyzing the health signals to determine a status of each of the plurality of electrochemical fuel cell columns, and in response to determining that a performance of a first electrochemical fuel cell column of the plurality of electrochemical fuel cell columns falls outside a threshold range, transmit one or more actuator signals to a captive linear actuator of one or more fuel inlet valve systems of the plurality of electrochemical fuel cell columns to modify a fuel flow to the one or more electrochemical fuel cell columns, where for each of the plurality of fuel inlet valve systems, the captive linear actuator is coupled to a respective valve controlling the fuel flow to the respective electrochemical fuel cell column. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0016] Implementations may include one or more of the following features. In some embodiments, the one or more actuator signals include a signal to the captive linear actuator of the first fuel inlet valve system instructing the captive linear actuator to close the valve of thefirst fuel inlet valve system to disable the flow of fuel to the first electrochemical fuel cell column. In some embodiments, after disabling the flow of fuel to the first electrochemical fuel cell column, current health signals from the one or more sensors of each active electrochemical fuel cell column of the plurality of electrochemical fuel cell columns are analyzed and one or more additional signals are transmitted to the captive linear actuators of one or more active fuel inlet valve systems to balance thermal activity and output of the active electrochemical fuel cell columns. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In the drawings, like reference characters generally refer to like parts throughout the different views. Also, the drawings are not necessarily to scale, with an emphasis instead generally being placed upon illustrating the principles of the technology disclosed. In the following description, various implementations are described with reference to the following drawings.

[0018] FIG. 1 illustrates a hotbox and an enlarged view of a fuel inlet valve system and its location, according to various embodiments of the present disclosure.

[0019] FIG. 2 illustrates another view of a hotbox base section and an enlarged view of a fuel inlet valve system, according to various embodiments of the present disclosure.

[0020] FIG. 3 illustrates a cross-sectional perspective view of the fuel inlet valve system of FIG. 1, according to various embodiments of the present disclosure.

[0021] FIG. 4 illustrates a closer view of the valve face and seat of the fuel inlet valve system of FIG. 1, according to various embodiments of the present disclosure.

[0022] FIG. 5 illustrates a detailed view of the fuel inlet valve system of FIG. 1 when closed, according to various embodiments of the present disclosure.

[0023] FIG. 6A illustrates a fuel inlet valve system when the valve is open, according to various embodiments of the present disclosure.

[0024] FIG. 6B illustrates a fuel inlet valve system when the valve is closed, according to various embodiments of the present disclosure.

[0025] FIG. 7 illustrates a fuel inlet valve system with various welding locations for assembly and hermetic sealing, according to various embodiments of the present disclosure.

[0026] FIG. 8A illustrates a fuel inlet valve system with the actuator mounted below the base plate of the hotbox, according to various embodiments of the present disclosure.

[0027] FIG. 8B illustrates a bottom view of the base plate having a plurality of fuel inlet valve systems of FIG. 8A, according to various embodiments of the present disclosure.

[0028] FIG. 9 illustrates a perspective view showing a fuel inlet conduit for a fuel cell column installed on a hotbox base and an enlarged view of fuel inlet valve system, according to another embodiment of the present disclosure.

[0029] FIG. 10 illustrates an alternative fuel inlet valve system, according to various embodiments of the present disclosure.

[0030] FIG. 11 illustrates a perspective and partially transparent view of an alternative fuel inlet valve system installed in a hotbox with an actuator positioned outside of, but not under, the hotbox, according to various embodiments of the present disclosure.

[0031] FIG. 12 illustrates a perspective and partially transparent view of an alternative fuel inlet valve system according to various embodiments of the present disclosure.

[0032] FIG. 13 illustrates data flow and processing components for analyzing hotbox health and controlling fuel flow to specific fuel cell columns of the hotbox of FIG. 1, according to various embodiments of the present disclosure.

[0033] FIG. 14 is a perspective view of an electrochemical cell column (e.g., fuel cell column), according to various embodiments of the present disclosure.

[0034] FIG. 15 is a perspective view of one counter-flow solid oxide electrochemical cell (e.g., solid oxide fuel cell (SOFC) or solid oxide electrolyzer cell (SOEC)) stack included in the column of FIG. 14, according to various embodiments of the present disclosure.

[0035] FIG. 16 is a side cross-sectional view of a portion of the stack of FIG. 15, according to various embodiments of the present disclosure.

[0036] FIG. 17 is a schematic of a fuel cell system, according to various embodiments of the present disclosure.

[0037] FIG. 18A is a sectional view showing components of the hotbox of the system of FIG. 17, according to various embodiments of the present disclosure.

[0038] FIG. 18B shows an enlarged portion of the system of FIG. 18 A, according to various embodiments of the present disclosure.

[0039] FIG. 18C is a three-dimensional cut-away view of a central column of the system of FIG. 18A, according to various embodiments of the present disclosure.

[0040] FIG. 18D is a perspective view of an anode hub structure disposed below the central column of the system of FIG. 18A, according to various embodiments of the present disclosure.

[0041] FIGS. 19A - 19C are sectional views showing fuel and air flow through the central column of the system of FIG. 18A, according to various embodiments of the present disclosure.

[0042] FIG. 20 is a side cross-sectional view showing an alternative embodiment of the components of the hotbox of the system of FIG. 17.

[0043] FIG. 21 is a perspective view of an exemplary modular SOFC system, according to various embodiments of the present disclosure.

[0044] FIG. 22 illustrates an example of a computing system that may be used to perform operations described herein in accordance with some embodiments of the present technology.

[0045] FIGS. 23A - 23D illustrate an alternative fuel cell column design that can be utilized with various embodiments of the present disclosure.

[0046] FIG. 24 illustrates a method of controlling fuel flow with a fuel inlet valve system, according to various embodiments of the present disclosure.DETAILED DESCRIPTION

[0047] Historically, when a fuel cell column in a hotbox underperforms, it remains active until it and other fuel cell column operations result in overall hotbox efficiency that falls below minimum requirements. At that time, the entire hotbox may be shut down. Accordingly, a single weak fuel cell column may result in shutdown of an entire hotbox. In many cases, other fuel cell columns of the hotbox may otherwise be able to continue operating within system requirements if the under or non-performing fuel cell column were cut off. However, current systems do not have the ability to control or shut off individual fuel cell columns. In the same regard, there may be situations where all the fuel cell columns in a hotbox do not need to operate to meet the load requirements of a SOFC system installation. For instance, it may be the case that a SOFC system is installed for powering a residential location and the system need only output 20kW of power (even though the system has a maximum output of 50kW or more). In that scenario, it is possible that the load can be met using half of the fuel cell columns in the hotbox (e.g., half are receiving fuel and half are not receiving fuel). In such a case, when theperformance of the initial fuel cell columns degrade such that they can no longer meet the required load, it would be beneficial if the system had the ability to individually bring additional fuel cell columns online in order to satisfy the load.

[0048] To address these issues, disclosed herein is an SOFC hotbox with multiple fuel cell columns that each include a fuel inlet valve system controlled by control logic executed by a system controller. The control logic can determine when one or more fuel cell columns are under- or non-performing and command an actuator in the fuel inlet valve system of the identified fuel cell column to close the fuel inlet valve, cutting off fuel to the non-performing fuel cell column. As a result, the remaining fuel cell columns can continue to operate, extending the uptime of the overall SOFC hotbox. Similarly in scenarios where a system is operating at partial output conditions, the system control logic can determine when overall hotbox power generation is degrading to a minimum required threshold amount, and if possible, command an actuator in the fuel inlet valve system of an offline column to open in order to bring that fuel cell column online.

[0049] In some embodiments, the controller can rebalance the remaining fuel cell columns to ensure the overall SOFC hotbox remains safely active. For example, increasing or decreasing fuel flow to other fuel cell columns to balance the overall system may be required depending on which fuel cell columns may have been cut off and if more than one fuel cell column is cut off (i.e., shut down).

[0050] The fuel inlet valve system includes a captive linear actuator that is controlled by control logic and designated drivers and is mechanically coupled to a valve stem of a valve that is positioned to allow or restrict fuel flow into the fuel cell column. Valve bellows around the valve stem permit linear travel while creating a hermetic seal as the valve is adjusted (e.g., closes and opens) as dictated by the linear actuator. When closed, the valve face seals against a valve seat interface, stopping fuel flow to the fuel cell column. Because the fuel inlet valve system is positioned within a hot zone of the hotbox of the SOFC system, insulation is strategically placed within the fuel inlet valve system to help limit heat exposure to the actuator. Various embodiments employ different configurations of the valve including a valve head having a flat valve face and a spherical valve head as described in detail with respect to FIGS. 9-12.

[0051] Turning now to FIG. 1, a hotbox 100, a control system 101, and an enlarged view 105 of a fuel inlet valve system 110 are illustrated. Control system is generally representative of acomputing system such as computing system 2200 described in connection with FIG 22. Additional details of control system 101 are discussed with respect to FIG. 13. Control system 101 receives signals from sensors within hotbox 100 via signal line 103. Sensors (not depicted) may include, for example, thermocouples having an end placed within hotbox 100 to measure temperature, pressure, concentrations of gases, voltages, and the like. The second end of the thermocouples extend outside of hotbox 100 and provide signals indicating the readings of the sensors to control system 101 via signal line 103. Control system 101 sends actuator signals to actuator 140 via signal cable 102 as discussed in detail throughout this disclosure. For clarity, FIG. 1 depicts one signal line 103 and one signal cable 102, but it is to be understood that a system may have multiple signal lines 103 and multiple signal cables 102 per hotbox.

[0052] Hotbox 100 may be representative of hotbox 1305 and 1750 described in more detail with respect to FIGS. 13 and 17 - 21. Hotbox 100 includes multiple fuel cell columns (e.g., comprised of stacks 1410 described with respect to FIGS. 14 - 21) placed around a circular column (e.g., column 1802 described with respect to FIGS. 18A - 20). Each fuel cell column includes a fuel inlet valve system 110. Enlarged view 105 includes fuel inlet 150, fuel conduit 155, and fuel inlet valve system 110.

[0053] Fuel inlet 150 is coupled to a fuel source such that fuel flows into the fuel cell column through fuel inlet 150. Fuel passes through fuel inlet valve system 110, when open, and flows into fuel conduit 155. Fuel conduit 155 is used to provide fuel to a fuel cell column and the fuel cells contained therein. Fuel inlet valve system 110 may be open or closed. When open, fuel flows through fuel inlet valve system 110 from fuel inlet 150 to fuel conduit 155. When closed, fuel inlet valve system 110 stops fuel flow from fuel inlet 150 to fuel conduit 155, ceasing operation of the fuel cell column supplied by fuel conduit 155. In some embodiments, precise control of fuel inlet valve system 110 allows partial opening such that the fuel flow may be restricted to regulate operation of the fuel cell column. In other words, the fuel cell column may not be fully operational or operating at one hundred percent (100%) capacity when the fuel flow is restricted. Alternatively, precise control of the fuel inlet valve system 110 may be utilized to maintain a certain fuel pressure in conduit 155 to ensure optimal operation of the associated fuel cell column.

[0054] Fuel inlet valve system 110 includes formed transition tube 115, valve seat 120, valve 125, valve bellows 130, threaded coupler 135, linear actuator 140, actuator mounting 145,insulation 160, insulation 165, lower portion valve chamber 170, upper portion valve chamber 180, and insulation chamber 175. The environment in which fuel inlet valve system 110 operates is extremely hot (e.g., 600° to 800° C). Accordingly, various components of fuel inlet valve system 110 are able to withstand extreme temperatures, and the design of fuel inlet valve system 110 attempts to limit exposure of components such as linear actuator 140 to extreme temperatures.

[0055] Formed transition tube 115 is formed to allow fuel flow around the valve face 125a when fuel inlet valve system 110 is open without excessive restriction of the fuel flow. Further, formed transition tube 115 narrows to couple to fuel conduit 155 once past the valve face 125a. Formed transition tube 115 may be formed from any suitable material such as, for example, Inconel.

[0056] Valve seat 120 is configured such that no fuel flow is allowed from fuel inlet 150 to fuel conduit 155 when valve face 125a is held against the surface of valve seat 120. Valve seat 120 may be formed via forging or machining from any suitable material such as, for example, Inconel. Valve seat 120 is coupled between formed transition tube 115 and upper portion valve chamber 180. Valve seat 120 is welded completely around to top plate 185 of the anode tail oxidizer (ATO) skirt of hotbox 100. Upper portion valve chamber 180 is welded completely around to bottom plate 190 of the ATO skirt. Additional details of formed transition tube 115 and valve seat 120 are shown in FIGS. 4 and 5.

[0057] Valve 125 includes valve face 125a and valve stem 125b. When closed, valve face 125a is seated in valve seat 120 to seal off fuel flow. Valve 125 may be spun formed in some embodiments. Valve 125 may be formed from any suitable material including, for example, Inconel. Valve stem 125b may be coupled to threaded coupler 135 and surrounded at least partially by valve bellows 130. Valve stem 125b includes a male threaded portion 127 at the end that threads into the female threaded portion 137 of threaded coupler 135.

[0058] Threaded coupler 135 may be formed from any suitable material that limits thermal conductivity between valve stem 125b and linear actuator 140. For example, threaded coupler 135 may be ceramic. Threaded coupler 135 couples linear actuator 140 to valve 125. Threaded coupler 135 includes a female threaded portion 137, 139 at each end into which the male threaded portion 127 of valve stem 125b and the male threaded portion 142 of actuator 140 may be threaded.

[0059] Valve bellows 130 may be, for example, welded bellows. Valve bellows 130 provide flexibility such that when fuel inlet valve system 110 is open, valve bellows are compressed. When fuel inlet valve system 110 is closed, valve bellows are extended. Valve bellows serve to stabilize the linear motion of valve stem 125b during opening and closing as well as provide sealing protection in the space around valve stem 125b such that fuel and heat are restricted from flowing toward linear actuator 140.

[0060] Linear actuator 140 may be a captive linear actuator with stepper motor control. Linear actuator 140 may be coupled with a controller and driver to receive and send signals indicating when to open and close fuel inlet valve system 110. Linear actuator 140 may reduce friction when opening or closing fuel inlet valve system 110 by moving valve 125 slowly. Linear actuator 140 is mounted using actuator mounting 145, which is shown in further detail in FIG. 3. Linear actuator 140 is susceptible to failure due to the high temperatures in the hot zone of hotbox 100. The hot zone may reach temperatures exceeding 800° C. Valve bellows 130 and threaded coupler 135 help insulate linear actuator 140 from hot zone temperatures. Additionally, insulation 160 may be placed about linear actuator 140 and the lower portion of valve chamber 170 within insulation chamber 175 to further insulate linear actuator 140 from excessive temperatures. Insulation 160 may be, for example, super wool. Additionally, insulation 165 may be used to further help create an isolated environment for linear actuator 140. Insulation 165 may be an insulation paper such as 333-E paper. Linear actuator 140 includes a male threaded portion.

[0061] FIG. 2 illustrates a perspective view 205 and a top view 215 of hotbox base section 200 and an enlarged view of a cross-sectional view of fuel inlet valve system 210. As seen in hotbox base section 200, multiple fuel cell columns (e.g., eight) may be placed about the central column. Each linear actuator is mounted to base plate 208 of the hotbox base.

[0062] Top view 215 shows where fuel inlet valve system 210 is placed. For the hotbox shown in FIG. 2, eight fuel cell columns may be placed about the central column, and each fuel cell column has a fuel inlet valve system positioned as shown by the dashed circles. Each fuel cell column also includes sensors associated with that particular fuel cell column. For example, thermocouples for each fuel cell column may be disposed in proximity to the respective fuel cell column and / or inserted into various locations of the respective fuel cell column.

[0063] Fuel inlet valve system 210 has a slightly different configuration of insulation material than that of fuel inlet valve system 110. However, fuel inlet valve system 210 includes the same components and serves the same purpose as fuel inlet valve system 110. Accordingly, the various components of fuel inlet valve system 210 are numbered consistently with those of fuel inlet valve system 110. The cross-sectional view of fuel inlet valve system 210 shows a perspective view for additional detail.

[0064] FIG. 3 illustrates a cross-sectional perspective view of a portion of fuel inlet valve system 110. The view provides an additional view of valve bellows 130 creating a seal between lower portion valve chamber 170 and upper portion valve chamber 180.

[0065] FIG. 4 illustrates a portion of fuel inlet valve system 110. The viewable portion includes formed transition tube 115, valve seat 120, valve 125, and upper portion valve chamber 180. When valve face 125a is spaced from the surface of valve seat 120, fuel flow around valve face 125a through formed transition tube 115 into fuel conduit 155 is not restricted. When valve face 125a is pressed into contact with valve seat 120, fuel flow around valve face 125a is restricted.

[0066] FIG. 5 illustrates further details of fuel inlet valve system 110 when closed. When valve face 125a is in the closed position, it is seated on valve seat 120 to form line of contact sealing 505. Valve face 125a is created with a seating angle 510 that is slightly different than valve seat angle 515 to create line of contact sealing 505. For example, seating angle 510 on valve face 125a may be one degree less than valve seat angle 515. In other words, seating angle 510 may be 39° and valve seat angle may be 40°, seating angle 510 may be 34° and valve seat angle may be 35°, seating angle 510 may be 44° and valve seat angle may be 45°, or the like.

[0067] FIG. 6A illustrates a fuel inlet valve system 600 (e.g., fuel inlet valve system 110, fuel inlet valve system 210) when the valve is open. In the open position, fuel flow to the associated fuel cell column is unrestricted. Valve bellows 130 is compressed, and valve face 125a is spaced from valve seat 120.

[0068] FIG. 6B illustrates fuel inlet valve system 600 when the valve is closed. To close valve 125, linear actuator 140 pulls down on valve stem 125b. Valve bellows 130 extend, and valve face 125b is lowered into pressing contact with valve seat 120. During contact, line of contact sealing 505 is created as discussed with respect to FIG. 5.

[0069] FIG. 7 illustrates fuel inlet valve system 700 with various welding locations for assembly. Fuel inlet valve system 700 may be representative of the depicted portions of fuel inlet valve system 110 or fuel inlet valve system 210. To assemble fuel inlet valve system 700, weld 705 is used to weld the top of valve bellows 130 to upper portion valve chamber 180. Weld 705 is formed about the entire circumference of upper portion valve chamber 180 and valve bellows 130 to create a seal. Weld 710 is formed about the entire circumference of upper portion valve chamber 180 and valve seat 120 to couple them. Weld 715 is formed to couple valve bellows 130 to valve stem 125b. To determine where to form weld 715, valve bellows 130 are compressed to set the initial lift of valve 125. Weld 720 is formed about the entire circumference of fuel inlet 150 to couple it to a side wall of upper portion valve chamber 180. Fuel inlet 150 is welded to form a seal to ensure fuel does not leak outside the valve system from fuel inlet 150.

[0070] FIG. 8 A illustrates a portion 800 of a hotbox (e g., hotbox 1750) having a fuel inlet valve system 810. Fuel inlet valve system 810 includes valve 125, couplers 135a, 135b, 135c, threaded connectors 806a, 806b, linear actuator 140, fan 804, and an actuator signal cable 102. Portion 800 also includes base plate 808 and fuel inlet 150. Fuel inlet valve system 810 operates substantially the same as fuel inlet valve system 110. However, fuel inlet valve system 810 includes three couplers 135a, 135b, 135c, each of which is substantially the same as coupler 135 described with respect to FIG. 1. Threaded coupler 135a is coupled to valve stem 125b at the first end and to threaded connector 806a at the second end. Threaded coupler 135b is coupled to threaded connector 806a at the first end and to threaded connector 806b at the second end.Threaded coupler 135c is coupled to threaded connector 806b at the first end and to actuator 140 at the second end. Each of threaded connector 806 are threaded rods that have a male threaded portion at each end, and which may extend from the first end to the second end. Each coupler 135 includes a female threaded portion at each end such that the threaded connectors 806, the threaded end of valve stem 125b, and the threaded connection point of actuator 140 may couple with the couplers 135. Couplers 135 extend the distance between the hotbox and actuator 140 and allow actuator 140 to be mounted below base plate 808, helping to thermally protect actuator 140 from the extreme heat of the hotbox. To further thermally protect fuel inlet valve system 810 and actuator 140, fuel inlet valve system 810 includes larger insulation chambers 812 that hold additional insulation and surround the lower portion of the valve chamber. Fan 804 is alsomounted beneath base plate 808 and is directed to blow air across actuator 140 for additional cooling.

[0071] FIG. 8B illustrates a bottom-up view 850 of the hotbox depicted in portion 800. Bottom -up view 850 depicts the bottom surface of base plate 808, which upon installation of the hotbox, sits upon lift base 814. Lift base 814 is generally representative of lift base 1834 described with respect to FIG. 18C. Base plate 808 is generally representative of cast base plate 1804 described with respect to FIG. 18C. As illustrated in FIG. 8B, fuel inlet valve systems 810, actuators 140 and fans 804 are mounted such that they are positioned below the bottom surface of base plate 808.

[0072] FIG. 9 illustrates a portion of a hotbox 900 and an enlarged view of a fuel inlet valve system 935 of hotbox 900. Hotbox 900 also includes a fuel cell column 905 positioned over a hotbox base plate 910. A fuel inlet conduit 915 is configured to provide fuel to fuel cell column 905. Linear actuator 920 is generally representative of linear actuator 140. Linear actuator 920 is positioned below the fuel cell column 905 and above the hotbox base plate 910. In other words, linear actuator 920 is positioned between fuel cell column 905 and hotbox base plate 910. While directional indications are used throughout with respect to the orientation of the drawings for ease of description, the components may be positioned in space in any orientation without departing from the spirit and scope of the disclosure. Accordingly, while “up” is used to describe direction with respect to the figures as oriented, the positioning or direction of “up,” “down,” and the like are not intended to limit the disclosure to components positioned in space the same as they are oriented in the figures. For example, while linear actuator 920 and valve stem 945 are positioned vertically in FIG. 9, they may be positioned horizontally in space in some embodiments. Continuing with the description of FIG. 9, linear actuator 920, when affixed in an operating hotbox 900, may be surrounded by insulating material (free flow insulation in the area between the hotbox base plate 910 and the ATO bottom skirt 925). Enlarged view 930 shows additional detail of fuel inlet valve system 935 including ceramic ball 940, linear actuator 920, valve stem 945, bellows 950, and valve chamber 955 as illustrated in FIG. 9. Fuel inlet valve system 935 is configured differently than fuel inlet valve system 110, though they serve the same purpose and interact with control system 101 in the same way since they each have a linear actuator (140, 920) that is controlled by control signals from control system 101 to open, close, or modify the fuel flow from fuel supply conduit 960 to fuel inlet conduit 915. Bellows 950 isgenerally representative of bellows 130 of FIG. 1 . Valve stem 945 is connected to linear actuator 920 on one end and ceramic ball 940 is attached to the other end of valve stem 945. In one embodiment, ceramic ball 940 comprises alumina (aluminum oxide). Ceramic ball 940 may comprise another ceramic material, such as cordierite (N^AUSisOis) or mullite (SAhCh ^SiCh). Ceramic ball 940 may be made from any suitable material such that it should not oxidize, should have a low coefficient of thermal expansion, and should be able to withstand the high temperature atmosphere present in hotbox 900. In some embodiments, valve stem 945 includes a male threaded portion on each end that is threaded into a female threaded portion of ceramic ball 940 and linear actuator 920. In some embodiments, valve stem 945 is attached to linear actuator with another coupling mechanism such as soldering, welding, a pin, or the like. One end of bellows 950 is welded to valve stem 945, and the other end of bellows 950 is welded to ATO bottom skirt 925. The two welds prevent or limit fuel from leaking into the area under ATO bottom skirt 925.

[0073] As illustrated in FIG. 9, fuel supply conduit 960 is configured to supply fuel to fuel inlet conduit 915. Enlarged view 930 illustrates that ceramic ball 940 is retracted away from the intersection of fuel supply conduit 960 with fuel inlet conduit 915. In this configuration, fuel will flow from fuel supply conduit 960 to fuel inlet conduit 915 and eventually to fuel cells located in fuel cell column 905. Thus, FIG. 9 illustrates fuel inlet valve system 935 in its open configuration. To seal or inhibit the fuel flow, ceramic ball 940 is raised in valve chamber 955 to block or at least partially block the opening of fuel supply conduit 960. Metallic ring 902 serves as a stopping mechanism for ceramic ball 940 such that it seats within metallic ring 902 when linear actuator 920 forces valve stem 945 to raise, raising ceramic ball 940 to seat and press against metallic ring 902. Metallic ring 902 is disposed at the top of valve chamber 955 and joins valve chamber 955 to fuel inlet conduit 915.

[0074] FIG. 10 illustrates fuel inlet valve system 1000, having a different configuration for actuating the ceramic ball 940 as compared to fuel inlet valve system 935 of FIG. 9. As illustrated in FIG. 10, linear actuator 920 is connected to valve stem 945 via links 1010 and 1015. The first end of link 1015 is attached to valve stem 945 via a pivot joint and the second end of link 1015 is attached to the first end of link 1010 via a second pivot joint. The second end of link 1010 is fixedly attached to linear actuator 920. When activated, linear actuator 920 pushes link 1010 towards link 1015, which in turn causes valve stem 945 (as well as ceramic ball940) to extend in an upward direction. In some embodiments, valve stem 945 may be oriented such that it extends in a different direction. The direction in which valve stem 945 extends may be determined by valve chamber 955 in which ceramic ball 940 has freedom of movement for travelling. Further, in some embodiments, valve stem 945 may be substantially perpendicular to link 1010. However, in some embodiments, the angle at which link 1010 and valve stem 945 are positioned with respect to each other may vary. Referring to FIG. 9, moving ceramic ball 940 up results in ceramic ball 940 inhibiting the flow gas from fuel supply conduit 960 to fuel inlet conduit 915 (and in some cases blocking fuel from flowing to fuel cell column 905). As previously mentioned, for ease of description of directional movement described herein, directional terms such as “up” and “down” are used with respect to the relative position indicated by the orientation of the figures. However, fuel inlet valve system 935 may be positioned in any orientation in space without departing from the scope and spirit of the present disclosure.

[0075] FIG. 11 illustrates a perspective and partially transparent view of a portion of a hotbox 1100. FIG. 11 illustrates fuel inlet valve system 1000 installed in hotbox 1100 with linear actuator 920 positioned outside of, but not under, hotbox 1100. As opposed to linear actuator 920 depicted with fuel inlet valve system 935 shown in FIG. 9, linear actuator 920 in fuel inlet valve system 1000 is attached to the outside of hotbox ring portion 1105, which in turn is welded to hotbox base plate 910. Thus, as illustrated in FIG. 11, linear actuator 920 is outside of hotbox 1100 and is not exposed to the same temperatures compared to the configuration illustrated in FIG. 9 (where linear actuator 920 is located inside hotbox 900 due to being mounted to the top surface of hotbox base plate 910).

[0076] FIG. 12 illustrates a perspective and partially transparent view of fuel inlet valve system 935 in a closed configuration. In the closed configuration, linear actuator 920 has been activated to position ceramic ball 940 to inhibit the flow of fuel from fuel supply conduit 960 to fuel cell column 905. As illustrated in FIG. 12, valve stem 945 has been pushed up by linear actuator 920, causing bellows 950 to compress and causing ceramic ball 940 to inhibit the flow of fuel from fuel supply conduit 960 to fuel cell column 905. The action of linear actuator 920 causes ceramic ball 940 to be pressed against metallic ring 902, inhibiting the flow of fuel into inlet conduit 915 from fuel supply conduit 960. Metallic ring 902 is welded to the inside of fuel inlet conduit 915.

[0077] FIG. 13 is a block diagram overview of part of an SOFC system 1300 having fuel inlet valve systems (e.g., fuel inlet valve system 110, 210, 700, 810, 935, 1000) associated with a hotbox 1305. System 1300 includes at least hotbox 1305 and control system 101. System 1300 may include multiple hotboxes 1305.

[0078] Hotbox 1305 is generally representative of hotbox 100, 900, 1100, and 1750 as described herein. Hotbox 1305 includes multiple fuel cell columns 1330. There may be any number of fuel cell columns as shown by fuel cell columns 1330a - 1330n. Each fuel cell column 1330 may include one or more electrochemical cell stacks (e.g., electrochemical cell stack 1410 described with respect to FIGS. 14 - 20). Hotbox 1305 may include many more components as described in other detailed figures herein, but a high-level representative depiction is used here for brevity.

[0079] Each fuel cell column 1330 includes sensors 1335 (sensors 1335a - 1335n) and an actuator 1340 (actuator 1340a - 1340n). Sensors 1335 include any sensors used for monitoring the status of the fuel cell column 1330 and hotbox 1305, and the sensors may include temperature sensors, voltage sensors, pressure sensors, gas concentration sensors, and other sensors that provide information about the status and operation of the respective fuel cell column 1330 and / or hotbox 1305. In some embodiments, sensors 1335 include thermocouples of which a sensing end is positioned within hotbox 1305 and a signal end extends outside hotbox 1305 to control system 101. Actuator 1340 is representative of linear actuators 140, 920 of each fuel inlet valve system 110, 210, 700).

[0080] Control system 101 is representative of computing system 2200. Control system 101 may be a microprocessor associated with hotbox 1305 in some embodiments. In some embodiments, control system 101 may be associated with SOFC system 2100. In some embodiments, control system 101 may monitor multiple hotboxes within a larger system such as SOFC system 2100. Control system 101 may perform hotbox monitoring and fuel shutoff and rebalancing processes (e.g., hotbox monitoring and fuel shutoff and rebalancing processes 2215). To perform such processes, control system 101 may include health monitoring 1320, fuel cell column fuel flow modification / rebalancing 1325, and actuator signaling 1345. Control system 101 may include more components, and the hotbox monitoring and fuel shutoff and rebalancing processes described herein may be performed using more or fewer modules than depicted without departing from the spirit and scope of the present description.

[0081] Health monitor 1320 may include instructions for receiving signals from sensors 1335 from each fuel cell column 1330 in hotbox 1305. Health monitor 1320 may process the signals to determine fuel cell column efficiency and operation. The signals may include operational signals such as temperature, electrical output values (e.g., voltage and / or current output), and the like. Using these signals, health monitor 1320 can evaluate the overall health of hotbox 1305 as well as the health of each fuel cell column 1330. For example, if one fuel cell column is operating at a low efficiency (e.g., electrical output values are below expected), that fuel cell column may have a low health value, and it may lower the health value overall for hotbox 1305. When one or more fuel cell columns are operating at a low efficiency or otherwise are determined that they are not at a sufficient health value, health monitor 1320 may provide an indication to column fuel flow modification / rebalancing 1325.

[0082] Column fuel flow modification / rebalancing 1325 may determine, based on the signal from health monitor 1320, that one or more fuel cell columns 1330 should be shut off or their fuel flow modified. For example, one non- or under-performing fuel cell column may drag down the overall efficiency of hotbox 1305. To avoid prematurely shutting down the entire hotbox 1305, the under- or non-performing fuel cell column 1330 may be shut off, increasing efficiency of the system overall with respect to the remaining fuel cell columns. For example, fuel cell column 1330a may be under-performing. Health monitor 1320 may determine, based on signals from sensors 1335a that fuel cell column 1330a is under-performing. Health monitor 1320 may send an indication to column fuel flow modification / rebalancing 1325 that fuel cell column 1330a is under-performing. Column fuel flow modification / rebalancing 1325 may determine that fuel flow to fuel cell column 1330a should be shut off and send an indication to actuator signaling 1345. Alternatively, column fuel flow modification / rebalancing 1325 may determine that fuel flow to another fuel cell column should be enabled in order bring the performance of the hotbox up given the degradation of the currently operating fuel cell columns.

[0083] Actuator signaling 1345 transmits signals to actuators 1340 instructing the actuators 1340 to set their respective valves to open, close, or open to a percentage. Actuators 1340 may offer precise control over the percentage that the valves in fuel inlet valve systems 110 are open. For example, fuel flow may be restricted to certain fuel cell columns 1330 to limit the amount of power generated by a specific fuel cell column 1330 while still providing some operating effect. In the example above where fuel cell column 1330a is under-performing, actuator signaling 1345may transmit a signal to actuator 1340a to close fuel inlet valve system 110 in fuel cell column 1330a.

[0084] Once closed, health monitor 1320 may receive additional signals from the remaining fuel cell columns 1330b - 1330n, and further modification may be performed based on the health of the remaining fuel cell columns. For example, column fuel flow modification / rebalancing 1325 may modify fuel flow to other fuel cell columns 1330 to ensure the overall efficiency of hotbox 1305 remains above a threshold value. Once the overall efficiency of hotbox 1305 cannot be stabilized above the threshold value, hotbox 1305 may be shut down pending maintenance or repair to improve efficiency or completely decommissioned. In some embodiments, column fuel flow modification / rebalancing 1325 may modify fuel flow to multiple fuel cell columns 1330 if fuel flow to one or more fuel cell columns is to be shut off. For example, in the example where fuel cell column 1330a is to be shut down (i.e., closing the fuel inlet valve system in fuel cell column 1330a), column fuel flow modification / rebalancing 1325 may limit fuel flow to an opposing fuel cell column (e.g. a fuel cell column physically placed on an opposite side of the central column) to keep one side of hotbox 1305 from overheating. Various reasons for rebalancing may occur based on shutting off fuel flow to one or more fuel cell columns 1330, and column fuel flow modification / rebalancing 1325 may preemptively modify fuel flow to one or more fuel cell columns by restricting a percentage of opening of one or more actuators 1340 via actuator signaling 1345. In some embodiments, rather than preemptively modifying fuel flow, additional signals from sensors 1335 in the remaining operating fuel cell columns 1330 may be used to rebalance or modify fuel flow to the respective fuel cell columns 1330.

[0085] Advantageously, by modifying fuel flow to various fuel cell columns 1330, hotbox 1305 may remain in service longer than otherwise would be possible without having precise control over fuel flow to individual fuel cell columns 1330.

[0086] The inventive fuel inlet valve system may be utilized in high temperature electrochemical cell systems, such as solid oxide fuel cell and solid oxide electrolyzer cell systems. In a high temperature fuel cell system, such as a solid oxide fuel cell (SOFC) system, an oxidizing flow is directed to the cathode side of the fuel cell while a fuel (i.e., reactant) flow is directed to the anode side of the fuel cell. The oxidizing flow is typically air, while the fuel flow can be hydrogen (H2) or a hydrocarbon fuel, such as methane, natural gas, ethanol, or methanol,or a hydrogen containing fuel such as ammonia. The fuel cell, operating at a typical temperature between 750°C and 950°C, enables the transport of negatively charged oxygen ions from the cathode flow stream to the anode flow stream, where the ions combine with either free hydrogen or hydrogen in a hydrocarbon molecule to form water vapor and / or with carbon monoxide to form carbon dioxide. The excess electrons from the negatively charged ions are routed back to the cathode side of the fuel cell through an electrical circuit completed between anode and cathode, resulting in an electrical current flow through the circuit.

[0087] In an electrolyzer system, such as a solid oxide electrolyzer system (SOEC), a reactant flow comprising water (e.g., steam) is separated into hydrogen and oxygen by applying a voltage across the electrolyzer cells. In the SOEC stack, the anode is the air electrode, and the cathode is the reactant electrode. Thus, the electrode to which the reactant (e.g., hydrogen, ammonia, or hydrocarbon fuel in a SOFC, and steam in a SOEC) is supplied may be referred to as the reactant electrode and the opposing electrode may be referred to as the air electrode in both SOFC and SOEC cells.

[0088] FIG. 14 is a perspective view of an electrochemical cell column 1430, FIG. 15 is a perspective view of one counter-flow solid oxide electrochemical cell (e.g., SOFC or SOEC) stack 1410 included in the column 1430 of FIG. 14, and FIG. 16 is a side cross-sectional view of a portion of the stack 1410 of FIG. 15.

[0089] Referring to FIGS. 14 and 15, column 1430 may include one or more electrochemical cell stacks 1410, a reactant inlet conduit 1432, a reactant exhaust conduit 1434, and reactant feed / return assemblies 1436 (e.g., reactant splitter plates (RSPs) 1436). The reactant inlet conduit 1432 is fluidly connected to RSPs 1436 and is configured to provide the reactant feed to each RSP 1436, and reactant exhaust conduit 1434 is fluidly connected to RSPs 1436 and is configured to receive reactant exhaust from each RSP 1436. In some embodiments, fuel conduit 155 of FIG. 1 or fuel inlet conduit 915 of FIG. 9 corresponds to reactant inlet conduit 1432 in FIG. 14.

[0090] The RSPs 1436 are disposed between stacks 1410 and are configured to provide a reactant (e.g., fuel or steam) feed to the stacks 1410 and to receive reactant exhaust from the stacks 1410. A RSP 1436 may also be positioned adjacent to a single stack depending upon the number of stacks in column 1430. RSPs 1436 may be fluidly connected to internal reactant holes 1422 formed in the stacks 1410.

[0091] Column 1430 may also include a compression assembly 1440, and a ceramic frame comprising side baffles 1441, a top plate 1442, a bottom plate 1443, top connectors 944 and bottom connectors 1445. The top connectors 944 and the bottom connectors 1445 connect the side baffles 1441 to the top plate 1442 and the bottom plate 1443, respectively.

[0092] Referring to FIG. 16, stack 1410 includes multiple electrochemical cells 1401 that are separated by interconnects 1402, which may also be referred to as gas flow separator plates or bipolar plates. Each electrochemical cell 1401 includes an air electrode 1403, a solid oxide electrolyte 1405, and a reactant electrode 1407.

[0093] Each interconnect 1402 electrically connects adjacent electrochemical cells 1401 in stack 1410. In particular, an interconnect 1402 may electrically connect the reactant electrode 1407 of one electrochemical cell 1401 to the air electrode 1403 of an adjacent electrochemical cell 1401. FIG. 16 shows that the lower electrochemical cell 1401 is located between two interconnects 1402.

[0094] Each interconnect 1402 includes reactant ribs 1412a that at least partially define reactant channels 8A and air ribs 1412b that at least partially define the air channels 8B. The interconnect 1402 may operate as a gas-reactant separator that separates a reactant flowing to the reactant electrode of one cell in the stack from oxidant, such as air, flowing to the air electrode 1403 of an adjacent cell in the stack. At either end of stack 1410, there may be an air end plate or reactant end plate (not shown) for providing air or reactant, respectively, to the end electrode in the stack. The end plate may comprise an interconnect 1402 where the channels on one side of the interconnect are not utilized for air or reactant flow as the case may be.

[0095] FIG. 17 is a schematic representation of a SOFC system 1700, according to various embodiments of the present disclosure. While FIG. 17 illustrates a SOFC system 1700, in other embodiments, the electrochemical cell system of the embodiments of the present disclosure may comprise a SOEC system.

[0096] Referring to FIG. 17, the system 1700 includes a hotbox 1750 and various components disposed therein or adjacent thereto. Hotbox 1750 is generally representative of hotbox 100, 900, and 1100. Hotbox 1750 may contain fuel cell stacks 1410, such as SOFC stacks containing alternating fuel cells and interconnects. One SOFC of the stack contains 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 anodeelectrode, such as a nickel-YSZ, a nickel -SSZ or nickel -doped ceria cermet, and a cathode electrode, such as lanthanum strontium manganite (LSM). The interconnects may be metal alloy interconnects, such as chromium-iron alloy, ferritic or martensitic stainless steels, or cast-iron interconnects. The stacks 1410 may be arranged over each other to assemble a fuel cell column (e.g., stacks 1410 in column 1430 in FIG. 14).

[0097] The hotbox 1750 may also contain an anode recuperator heat exchanger 1730, a cathode recuperator heat exchanger 1724, an anode tail gas oxidizer (ATO) 1728, an anode exhaust cooler heat exchanger 1718, a splitter 1726, a vortex generator 1742, and a water injector 1744. The system 1700 may also include a catalytic partial oxidation (CPOx) reactor 1708, a mixer 1712, a CPOx blower 1706 (e.g., air blower), a system blower 1740 (e.g., air blower), and an anode recycle blower 1714, which may be disposed outside of the hotbox 1750. However, the present disclosure is not limited to any particular location for each of the components with respect to the hotbox 1750.

[0098] The CPOx reactor 1708 receives a fuel inlet stream from fuel inlet 1704, through fuel conduit 1704a. The fuel inlet 1704 may be a fuel tank or a utility natural gas line including a valve to control an amount of fuel provided to the CPOx reactor 1708. The CPOx blower 1706 may provide air to the CPOx reactor 1708 during system start-up. The fuel and / or air may be provided to the mixer 1712 by fuel conduit 1704b. Fuel flows from the mixer 1712 to the anode recuperator 1730 through fuel conduit 1704c. The fuel is heated in the anode recuperator 1730 by a portion of the fuel exhaust and the fuel then flows from the anode recuperator 1730 to the stack 1410 through fuel conduit 1704d. Inventive fuel inlet valve systems 110 are coupled to fuel conduit 1704d to individually control the supply of fuel to individual columns in hotbox 1750.

[0099] The main air blower 1740 may be configured to provide an air stream (e.g., air inlet stream) to the anode exhaust cooler 1718 through air conduit 1710a. Air flows from the anode exhaust cooler 1718 to the cathode recuperator 1724 through air inlet conduit 1710b. The air is heated by the ATO exhaust in the cathode recuperator 1724. The air flows from the cathode recuperator 1724 to the stack 1410 through air conduit 1710c.

[0100] An anode exhaust stream (e.g., the fuel exhaust stream described below with respect to FIGS. 19A - 19C) generated in stack 1410 is provided to the anode recuperator 1730 through anode exhaust conduit 1716a. The anode exhaust may contain unreacted fuel and may also bereferred to herein as fuel exhaust. The anode exhaust may be provided from the anode recuperator 1730 to the splitter 1726 by anode exhaust conduit 1716b. A first portion of the anode exhaust may be provided from the splitter 1726 to the anode exhaust cooler 1718 through the water injector 1744 and the anode exhaust conduit 1716c. A second portion of the anode exhaust is provided from the splitter 1726 to the ATO 1728 through the anode exhaust conduit 1716d. The first portion of the anode exhaust heats the air inlet stream in the anode exhaust cooler 1718 and may then be provided from the anode exhaust cooler 1718 to the mixer 1712 through the anode exhaust conduit 1716e. The anode recycle blower 1714 may be configured to move anode exhaust though anode exhaust conduit 1716e, as discussed below.

[0101] Cathode exhaust generated in stack 1410 flows to the ATO 1728 through exhaust conduit 1722a. The vortex generator 1742 may be disposed in exhaust conduit 1722a and may be configured to swirl the cathode exhaust. The anode exhaust conduit 1716d may be fluidly connected to the vortex generator 1742 or to the cathode exhaust conduit 1722a or the ATO 1728 downstream of the vortex generator 1742. The swirled cathode exhaust may mix with the second portion of the anode exhaust provided by the splitter 1726 before being provided to the ATO 1728. The mixture may be oxidized in the ATO 1728 to generate an ATO exhaust. The ATO exhaust flows from the ATO 1728 to the cathode recuperator 1724 through exhaust conduit 1722b. Exhaust flows from the cathode recuperator and out of the hotbox 1750 through exhaust conduit 1722c.

[0102] Water flows from a water source 1746, such as a water tank or a water pipe, to the water injector 1744 through water conduit 1748. The water injector 1744 injects water directly into the first portion of the anode exhaust provided in conduit 1716c. Heat from the first portion of the anode exhaust (also referred to as a recycled anode exhaust stream) provided in exhaust conduit 1716c vaporizes the water to generate steam. The steam mixes with the anode exhaust, and the resultant mixture is provided to the anode exhaust cooler 1718. The mixture is then provided from the anode exhaust cooler 1718 to the mixer 1712 through the anode exhaust conduit 1716e. The mixer 1712 is configured to mix the steam and first portion of the anode exhaust with fresh fuel (i.e., fuel inlet stream). This humidified fuel mixture may then be heated in the anode recuperator 1730 by the anode exhaust, before being provided to the stack 1410. System 1700 may also include one or more fuel reforming catalysts 1732, 1734, and 1736located inside and / or downstream of the anode recuperator 1730. The reforming catalyst(s) reform the humidified fuel mixture before it is provided to stack 1410.

[0103] The system 1700 may further include a control system 1720 configured to control various elements of the system 1700. The controller 1720 may include a central processing unit configured to execute stored instructions. For example, the controller 1720 may be configured to control fuel and / or air flow through system 1700, according to fuel composition data. Control system 1720 provides control signals to actuator 140 in fuel inlet valve system 110 to set the valve to open, closed, or anywhere in between (e.g., a percentage of open such as 20% open).

[0104] FIG. 18A is a sectional view showing components of the hotbox 1750 of the system 1700 of FIG. 17, and FIG. 18B shows an enlarged portion of FIG. 18A. FIG. 18C is a three- dimensional cut-away view of a central column 1802 of the system 1700, according to various embodiments of the present disclosure, and FIG. 18D is a perspective view of an anode hub structure 1806 disposed in hotbox base 1804 on which the column 1802 may be disposed.

[0105] Referring to FIGS. 18A - 18D, fuel cell stacks 1410 (or columns 1430) may be disposed around central column 1802 in hotbox 1750. For example, the stacks 1410 may be disposed in a ring configuration around the central column 1802 and may be positioned on the hotbox base 1804. Column 1802 may include anode recuperator 1730, ATO 1728, and anode exhaust cooler 1718. In particular, the anode recuperator 1730 is disposed radially inward of the ATO 1728, and anode exhaust cooler 1718 is mounted over anode recuperator 1730 and ATO 1728. In one embodiment, oxidation catalyst 1732 and / or hydrogenation catalyst 1734 may be located in anode recuperator 1730. Reforming catalyst 1736 may also be located at the bottom of anode recuperator 1730 as a steam methane reformation (SMR) insert.

[0106] ATO 1728 comprises an outer cylinder 1728a that is positioned around inner ATO insulation 1728b / outer wall of the anode recuperator 1730. Optionally, the insulation 1728b may be enclosed by an inner ATO cylinder 1728c. Thus, the insulation 1728b may be located between the anode recuperator 1730 and the ATO 1728. An ATO oxidation catalyst may be located in the space between the outer cylinder 1728a and the ATO insulation 1728b. A fuel inlet path bellows 1822 may be located between the anode exhaust cooler 1718 and inner ATO cylinder 1728c. ATO thermocouple feed through 1014 extends through the anode exhaust cooler 1718, to the top of the ATO 1728. The temperature of the ATO 1728 may thereby be monitored by inserting one or more thermocouples (not shown) through this feed through 1014.

[0107] Anode hub structure 1806 may be positioned under anode recuperator 1730 and ATO 1728 and over hotbox base 1804. Anode hub structure 1806 is covered by ATO skirt 1836. The vortex generator (e.g., ATO mixer) 1742 and fuel exhaust splitter 1726 are located over the anode recuperator 1730 and ATO 1728 and below the anode exhaust cooler 1718. An ATO glow plug 1832, which initiates the oxidation of the stack fuel exhaust in the ATO during startup, may be located near the bottom of the ATO 1728.

[0108] The anode hub structure 1806 is used to distribute fuel evenly from the central column to fuel cell stacks 1410 disposed around the central column 1802. The anode flow hub structure 1806 includes a grooved cast base 1812 and a “spider” hub of fuel inlet conduits 1704d and outlet conduits 1716a. Each pair of conduits 1704d, 1716a connects to a fuel cell stack 1410. A fuel inlet valve system 110 is coupled to each inlet fuel conduit 1704d. Anode side cylinders (e.g., anode recuperator 1730 inner and outer cylinders and ATO outer cylinder 1728a) are then welded or brazed into the grooves in the base 1812, creating a uniform volume cross section for flow distribution as discussed below.

[0109] A lift base 1834 is located under the hotbox base 1804, as illustrated in FIG. 18C. In an embodiment, the lift base 1834 includes two hollow arms with which the forks of a forklift can be inserted to lift and move the system, such as to remove the system from a cabinet (not shown) for repair or servicing.

[0110] As shown by the arrows in FIGS. 18A and 18B, air enters the top of the hotbox 1750 and then flows into the cathode recuperator 1724 where it is heated by ATO exhaust (not shown) from the ATO 1728. The heated air then flows inside the cathode recuperator 1724 through a first vent or opening 1808. The air then flows through stacks 1410 and reacts with fuel (i.e., fuel inlet stream) provided from the anode hub structure 1806. Air exhaust flows from the stacks 1410, through a second vent or opening 1810. The air exhaust then passes through vanes of the vortex generator 1 42 and is swirled before entering the ATO 1728.

[0111] The splitter 1726 may direct the second portion of the fuel exhaust exiting the top of the anode recuperator 1730 through openings (e.g., slits) in the splitter into the swirled air exhaust (e.g., in the vortex generator 1742 or downstream of the vortex generator in conduit 1722a or in the ATO 1728). The fuel and air exhaust may be mixed before entering ATO 1728.

[0112] FIGS. 19A and 19B are side cross-sectional views showing flow distribution through the central column 1802, and FIG. 19C is top cross-sectional view taken through the anoderecuperator 1730. Referring to FIGS. 18 A, 18B, 19A, and 19C, the anode recuperator 1730 includes an inner cylinder 1730a, a corrugated plate 1730b, and an outer cylinder 1730c that may be coated with the ATO insulation 1728b. Fuel from fuel conduit 1704c enters the top of the central column 1802. The fuel then bypasses the anode exhaust cooler 1718 by flowing through its hollow core and then flows through the anode recuperator 1730, between the outer cylinder 1730c and the and the corrugated plate 1730b. The fuel then flows through the hub base 1812 and conduits 1704d of the anode hub structure 1806 shown in FIG. 19B, to the stacks 1410.

[0113] Referring to FIGS. 18A, 18B, 18C, 19A, and 19B, the fuel exhaust flows from the stacks 1410 through conduits 1716a into the hub base 1812, and from the hub base 1812 through the anode recuperator 1730, between inner cylinder 1730a and the corrugated plate 1730b, and through conduit 1716b into the splitter 1726. The first portion of the fuel exhaust flows from the splitter 1726 to the anode exhaust cooler 1718 through conduit 1716c, while the second portion flows from the splitter 1726 to the ATO 1728 through conduit 1716d, as shown in FIG. 17. Anode exhaust cooler inner core insulation 1718a may be located between the fuel conduit 1704c and bellows 1820 / supporting cylinder 1820a located between the anode exhaust cooler 1718 and the vortex generator 1742, as shown in FIG. 19A. This insulation minimizes heat transfer and loss from the first portion of the anode exhaust stream in conduit 1716c on the way to the anode exhaust cooler 1718. Insulation 1718a may also be located between conduit 1704c and the anode exhaust cooler 1718 to avoid heat transfer between the fuel inlet stream in conduit 1704c and the streams in the anode exhaust cooler 1718. In other embodiments, insulation 1718a may be omitted from inside the cylindrical anode exhaust cooler 1718.

[0114] FIG. 19B also shows air flowing from the air conduit 1710a to the anode exhaust cooler 1718 (where it is heated by the first portion of the anode exhaust) and then from the anode exhaust cooler 1718 through conduit 1710b to the cathode recuperator 1724. The first portion of the anode exhaust is cooled in the anode exhaust cooler 1718 by the air flowing through the anode exhaust cooler 1718. The cooled first portion of the anode exhaust is then provided from the anode exhaust cooler 1718 to the anode recycle blower 1714 shown in FIG. 17.

[0115] As will be described in more detail below and as shown in FIGS. 18A and 19B, anode exhaust exits the anode recuperator 1730 and is provided into splitter 1726 through conduit 1716b. The splitter 1726 splits the anode exhaust into first and second anode exhaust portions(i.e., streams). The first stream is provided into anode exhaust cooler 1718 through conduit 1716c. The second stream is provided to the ATO 1728 through conduit 1716d.

[0116] The relative amounts of anode exhaust provided to ATO 1728 and anode exhaust cooler 1718 are controlled by anode recycle blower 1714. The higher the blower 1714 speed, the larger portion of the anode exhaust is provided into conduit 1716c, and a smaller portion of the anode exhaust is provided to ATO 1728 via conduit 1716d, and vice-versa.

[0117] The anode exhaust provided to the ATO 1728 is not cooled in anode exhaust cooler 1718. This allows higher temperature anode exhaust to be provided into ATO 1728 than if the anode exhaust were provided after flowing through anode exhaust cooler 1718. For example, the anode exhaust provided into ATO 1728 from splitter 1726 may have a temperature of above 350 °C, such as from about 350 to about 500 °C, for example, from about 375 to about 425 °C, or from about 390 to about 410 °C. Furthermore, since a smaller amount of anode exhaust is provided into the anode exhaust cooler 1718 (e.g., not 100% of the anode exhaust is provided into the anode exhaust cooler due to the splitting of the anode exhaust in splitter 1726), the heat exchange area of the anode exhaust cooler 1718 may be reduced. The anode exhaust provided to the ATO 1728 may be oxidized by the stack cathode (i.e., air) exhaust and provided to the cathode recuperator 1724 through conduit 1722b.

[0118] FIG. 20 illustrates an alternative configuration of hotbox 1750 components of the fuel cell system 1700. As illustrated in FIG. 20, central column 1802 includes the slit type splitter 1726 described above with respect to FIG. 19A. Furthermore, water injector 1744 of FIG. 20 includes injection apertures 2002a on the inner surface of injector ring 2002. Finally, catalysts 1732, 1734 and 1736 of FIG. 20 are located inside the inner plenum, which is surrounded by anode recuperator 1730, similar to the configuration described in U.S. Patent Number 9,287,572 B2, issued March 15, 2016, and incorporated herein by reference in its entirety.

[0119] During operation of fuel cell system 1700, such as during system startup, water is generally not required until stack 1410 reaches a temperature of about 300 °C or more, such as a temperature ranging from about 300 °C to about 325 °C. Once stack 1410 approaches about 300 °C, water is provided from water source 1746 to water conduit 1748 at the top of the central column 1802. Water conduit 1748 passes through insulation 1718a that is located between and separates fuel conduit 1704c from anode exhaust cooler 1718. The insulation reduces the amount of heat exchange between the water in water conduit 1748 and anode exhaust cooler1718. Accordingly, while passing through water conduit 1748, the water may be slightly heated above ambient temperature by anode exhaust in the surrounding toroidal anode cooler 1718. However, it is believed that at least the majority of the water remains in a liquid state while in the water conduit 1748.

[0120] The water is then provided by water conduit 1748 to water injector 1744. For example, the water is provided by the water conduit into the injector ring 2002. The water flows circumferentially in injector ring 2002 and is circumferentially dispersed before being ejected into the first portion of the anode exhaust through injection apertures 2002a, 2004. In one embodiment, at least a portion of the water is injected in the liquid state into the first portion of the anode exhaust stream. The water is then vaporized in the first portion of the anode exhaust to form a humidified anode exhaust. The humidified anode exhaust is then provided through conduit 1716e to mixer 1712 for mixing with fresh fuel (i.e., fuel inlet stream) before being provided to the anode recuperator 1730 and stack 1410 as discussed above.

[0121] FIG. 21 is a perspective view of a modular SOFC system 2100, according to various embodiments of the present disclosure. Fuel cell system 2100 may contain modules and components described in U.S. Patent Nos. 9,190,693 and 9,755,263, which are incorporated herein by reference in their entireties. The modular design of fuel cell system 2100 provides flexible system installation and operation. Modules allow scaling of installed generating capacity, reliable generation of power, flexibility of fuel processing, and flexibility of power output voltages and frequencies with a single design set. The modular design results in an “always on” unit with very high availability and reliability. This design also provides an easy means of scale up to meet specific requirements of customer installations. The modular design also allows the use of available fuels and required voltages and frequencies which may vary by customer and / or by geographic region.

[0122] The modular fuel cell system 2100 includes one or more fuel cell power modules 1310 and one or more power conditioning (i.e., electrical output) modules 2105. In embodiments, the power conditioning modules 2105 are configured to deliver direct current (DC). In alternative embodiments, the power conditioning modules 2105 are configured to deliver alternating current (AC). In these embodiments, the power conditioning modules 2105 include a mechanism to convert DC to AC, such as an inverter. For example, the fuel cellsystem 2100 may include any desired number of modules, such as 2 - 30 power modules, for example 3 - 12 power modules, such as 6 - 12 modules.

[0123] Fuel cell system 2100 of FIG. 21 includes a row of seven power modules 2110 and one power conditioning module 2105 disposed on pad 2120. While one row of power modules 2110 is shown, fuel cell system 2100 may comprise more than one row of modules 2110. For example, fuel cell system 2100 may comprise two rows of power modules 2110 arranged back- to-back / end-to-end.

[0124] Each power module 2110 is configured to house one or more hotboxes 1750. Each hotbox 1750 contains one or more stacks or columns of fuel cells (not shown for clarity), such as one or more stacks or columns of SOFCs having a ceramic oxide electrolyte separated by conductive interconnect plates.

[0125] The fuel cell stacks may comprise externally and / or internally manifolded stacks. For example, the stacks may be internally manifolded for fuel and air with fuel and air risers extending through openings in the fuel cell layers and / or in the interconnect plates between the fuel cells.

[0126] Alternatively, the fuel cell stacks may be internally manifolded for fuel and externally manifolded for air, where only the fuel inlet and exhaust risers extend through openings in the fuel cell layers and / or in the interconnect plates between the fuel cells, as described in U.S.Patent Number 7,713,649, which is incorporated herein by reference in its entirety. The fuel cells may have a cross flow (where air and fuel flow roughly perpendicular to each other on opposite sides of the electrolyte in each fuel cell), counter flow parallel (where air and fuel flow roughly parallel to each other but in opposite directions on opposite sides of the electrolyte in each fuel cell) or co-flow parallel (where air and fuel flow roughly parallel to each other in the same direction on opposite sides of the electrolyte in each fuel cell) configuration.

[0127] Power conditioning module 2105 may include components for converting the fuel cell stack generated DC power to AC power (e.g., DC / DC and DC / AC converters described in U.S. Patent Number 7,705,490, incorporated herein by reference in its entirety), electrical connectors for AC power output to the grid, circuits for managing electrical transients, and a system controller (e.g., a computer or dedicated control logic device or circuit). Power conditioning module 2105 may be designed to convert DC power from the fuel cell modules todifferent AC voltages and frequencies. Designs for 208V, 60Hz; 480V, 60Hz; 415V, 50Hz and other common voltages and frequencies may be provided.

[0128] The linear array of power modules 2110 is readily scaled. For example, more or fewer power modules 2110 may be provided depending on the power needs of the building or other facility serviced by the fuel cell system 2100. Power modules 2110 and input / output modules may also be provided in other ratios. For example, in other exemplary embodiments, more or fewer power modules 2110 may be provided.

[0129] The modular fuel cell system 2100 may be configured in a way to ease servicing of the components of the fuel cell system 2100. For example, the fuel cell system 2100 may include access doors 2115. All of the routinely or high serviced components (such as the consumable components) may be placed in a single module to reduce the amount of time required for the service person.

[0130] For example, when one power module 2110 is taken offline (i.e., no power is generated by the stacks in the hotbox 1750 in the offline module 2110), the remaining power modules 2110 and the power conditioning module 2105 are not taken offline. Furthermore, the fuel cell system 2100 may contain more than one of each type of module 2110, 2105. When at least one module of a particular type is taken offline, the remaining modules of the same type are not taken offline.

[0131] Thus, in a system comprising a plurality of modules, each of the modules 2110 or 2105 may be electrically disconnected, removed from the fuel cell system 2100 and / or serviced or repaired without stopping an operation of the other modules in the system, allowing the fuel cell system to continue to generate electricity. The entire fuel cell system 2100 does not have to be shut down if one stack of fuel cells in one hotbox 1750 malfunctions or is taken offline for servicing.

[0132] FIG. 22 illustrates computing system 2200 to perform hotbox monitoring, valve shutoff, and fuel flow rebalancing according to an implementation of the present technology. Computing system 2200 could be a part of control system 1720 in FIG. 17 or control system 101 in FIGS. 1 and 13. Computing system 2200 is representative of any system or collection of systems with which the various operational architectures, processes, scenarios, and sequences disclosed herein for health analysis and valve shutoff may be employed. Computing system 2200 may be implemented as a single apparatus, system, or device or may be implemented in adistributed manner as multiple apparatuses, systems, or devices. Computing system 2200 includes, but is not limited to, processing system 2220, storage system 2205, software 2210, communication interface system 2225, and user interface system 2230 (optional). Processing system 2220 is operatively coupled with storage system 2205, communication interface system 2225, and user interface system 2230.

[0133] Processing system 2220 loads and executes software 2210 from storage system 2205. Software 2210 includes and implements valve shutoff process 2215, which is representative of the hotbox monitoring, valve shutoff, and fuel flow rebalancing discussed with respect to the preceding Figures (e.g., FIG. 13). When executed by processing system 2220 to provide hotbox monitoring, valve shutoff, and fuel flow rebalancing functions, software 2210 directs processing system 2220 to operate as described herein for at least the various processes, operational scenarios, and sequences discussed in the foregoing implementations. Computing system 2200 may optionally include additional devices, features, or functionality not discussed for purposes of brevity.

[0134] Referring still to FIG. 22, processing system 2220 may comprise a microprocessor and other circuitry that retrieves and executes software 2210 from storage system 2205. Processing system 2220 may be implemented within a single processing device but may also be distributed across multiple processing devices or sub-systems that cooperate in executing program instructions. Examples of processing system 2220 include general purpose central processing units, graphical processing units, application specific processors, and logic devices, as well as any other type of processing device, combinations, or variations thereof.

[0135] Storage system 2205 may comprise any computer readable storage media readable by processing system 2220 and capable of storing software 2210. Storage system 2205 may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data. Examples of storage media include random access memory, read only memory, magnetic disks, optical disks, optical media, flash memory, virtual memory and non-virtual memory, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other suitable storage media. In no case is the computer readable storage media a propagated signal.

[0136] In addition to computer readable storage media, in some implementations storage system 2205 may also include computer readable communication media over which at least some of software 2210 may be communicated internally or externally. Storage system 2205 may be implemented as a single storage device but may also be implemented across multiple storage devices or sub-systems co-located or distributed relative to each other. Storage system 2205 may comprise additional elements, such as a controller, capable of communicating with processing system 2220 or possibly other systems.

[0137] Software 2210 (including hotbox monitoring and fuel shutoff and rebalancing processes 2215) may be implemented in program instructions and among other functions may, when executed by processing system 2220, direct processing system 2220 to operate as described with respect to the various operational scenarios, sequences, and processes illustrated herein. For example, software 2210 may include program instructions for implementing hotbox monitoring, valve shutoff, and fuel flow rebalancing system as described herein.

[0138] In particular, the program instructions may include various components or modules that cooperate or otherwise interact to carry out the various processes and operational scenarios described herein. The various components or modules may be embodied in compiled or interpreted instructions, or in some other variation or combination of instructions. The various components or modules may be executed in a synchronous or asynchronous manner, serially or in parallel, in a single threaded environment or multi -threaded, or in accordance with any other suitable execution paradigm, variation, or combination thereof. Software 2210 may include additional processes, programs, or components, such as operating system software, virtualization software, or other application software. Software 2210 may also comprise firmware or some other form of machine-readable processing instructions executable by processing system 2220.

[0139] In general, software 2210 may, when loaded into processing system 2220 and executed, transform a suitable apparatus, system, or device (of which computing system 2200 is representative) overall from a general-purpose computing system into a special-purpose computing system customized to provide valve shutoff functions as described herein. Indeed, encoding software 2210 on storage system 2205 may transform the physical structure of storage system 2205. The specific transformation of the physical structure may depend on various factors in different implementations of this description. Examples of such factors may include, but are not limited to, the technology used to implement the storage media of storage system2205 and whether the computer-storage media are characterized as primary or secondary storage, as well as other factors.

[0140] FIGS. 23A - 23D illustrate an alternative fuel cell column design that can be utilized with the fuel inlet valve systems 110 disclosed herein. FIG. 23 A illustrates a fuel cell column 2300 comprised of a single stack 2310 of fuel cells. The fuel cell stack 2310 includes multiple fuel cells 2301 that are separated by interconnects 2302. The stack 2310 is surrounded by ceramic side baffles 2341, stack compression assembly 2340, and a fuel plenum 2304. A fuel inlet conduit (inlet conduit 150 in FIG. 1, fuel inlet conduit 915 in FIG. 9, or inlet conduit 1704d in FIG. 18D) is coupled to fuel plenum 2304 to provide fuel to the fuel cell column 2300. A fuel inlet valve system 110 is coupled to the fuel inlet conduit and the fuel plenum to control the flow of fuel to the fuel cell column 2300.

[0141] As illustrated in FIGS. 23B and 23D, each fuel cell 2301 may include a solid oxide electrolyte 2305, an anode 2307, and a cathode 2303. When arranged in a SOFC stack 2310, the anode 2307 of one fuel cell 2301 is placed in contact with the fuel side of one interconnect 2302, while the cathode of fuel cell 2301 is placed in contact with the air side of another interconnect 2302. In some embodiments, a conductive layer 2308, such as a nickel mesh, may be disposed between the anode 2307 and the adjacent interconnect 2302.

[0142] As illustrated in FIG. 23B, as the fuel cell stack 2310 is assembled, fuel inlet holes 2322 are aligned to create fuel inlet risers in the stack 2310. As illustrated in FIG. 23C, fuel flows from the fuel inlet risers created from fuel inlet holes 2322 across the surface of each interconnect and exists through fuel outlet holes 2324. As illustrated in FIG. 23C, fuel F flows in one direction across the fuel side of each interconnect, while air A flows in a substantially perpendicular direction across the air side of each interconnect. In contrast to the stack in FIG. 15, this stack is an example of a cross-flow configuration.

[0143] FIG. 24 illustrates a method 2400 for controlling fuel flow to a fuel cell column. Method 2400 may be performed by system 1300, and more particularly by control system 101 using any of the fuel inlet valve systems (e.g., 110, 210, 935, 1000) disclosed herein. The steps of method 2400 may be performed in any order or multiple times, and method 2400 may include additional steps not discussed herein.

[0144] Step 2402 includes receiving health signals from one or more sensors of each of a plurality of electrochemical fuel cell columns of a solid oxide fuel cell system. For example,control system 101 may receive signals from thermocouples or sensors disposed within a hotbox (e.g., hotbox 100, 900, 1100, and 1750). Each fuel cell column may include sensors associated with that particular fuel cell column such that control system 101 may obtain signals for each fuel cell column.

[0145] Step 2404 includes analyzing the health signals to determine a status of each of the plurality of electrochemical fuel cell columns. For example, control system 101 analyzes the signals from each of the sensors associated with a given fuel cell column to determine whether the fuel cell column is operating within parameters. Operating parameters may include temperature, pressure, gas concentrations, output (e.g., voltage output obtained by voltage sensors), and the like. Each operating parameter may have associated threshold values such that if the operating parameter falls outside an acceptable operating range, the fuel cell column is deemed unhealthy.

[0146] Step 2406 includes in response to determining that the performance of a first electrochemical fuel cell column of the plurality of electrochemical fuel cell columns falls outside a threshold range, transmitting one or more actuator signals to a captive linear actuator of one or more fuel inlet valve systems of the plurality of electrochemical fuel cell columns, where the captive linear actuator of a respective fuel inlet valve system is coupled to a respective valve controlling the fuel flow in the respective electrochemical fuel cell column. For example, control system 101 may determine that one of the electrochemical fuel cell columns is not performing well based on an operating parameter falling outside the acceptable range (below or above a threshold value). For example, an operating temperature may exceed an upper limit, a pressure may exceed or fall below a range, or the like. In response, control system 101 may send a signal to the respective actuator instructing the actuator to close the valve (e.g., valve 125) associated with that fuel cell column to inhibit the flow of fuel to that the fuel cell column. Further, in some embodiments, control system 101 may analyze further health signals and rebalance the remaining (i.e., active) fuel cell columns by modifying the fuel flow to one or more of the active fuel cell columns. For example, having one fuel cell column disabled may make the hotbox unstable, so a second fuel cell column may be disabled to stabilize the system. For example, referring to FIG. 2, if fuel cell column 1 is unhealthy, to stabilize the system, fuel cell column 5 may also be disabled to balance the overall hotbox.

[0147] The aforementioned discussion is presented to enable any person skilled in the art to make and use the technology disclosed and is provided in the context of a particular application and its requirements. Various modifications to the disclosed implementations will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the spirit and scope of the technology disclosed. Thus, the technology disclosed is not intended to be limited to the implementations shown but is to be accorded the widest scope consistent with the principles and features disclosed herein.

[0148] Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise," "comprising," and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of "including, but not limited to." As used herein, the terms "connected," "coupled," or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, or a combination thereof. Additionally, the words "herein," "above," "below," and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the above Detailed Description using the singular or plural number may also include the plural or singular number, respectively. The word "or" in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

[0149] The phrases "in some embodiments," "according to some embodiments," "in the embodiments shown," "in other embodiments," and the like generally mean the particular feature, structure, or characteristic following the phrase is included in at least one implementation of the present technology and may be included in more than one implementation. In addition, such phrases do not necessarily refer to the same embodiments or different embodiments.

[0150] The above detailed description of examples of the technology is not intended to be exhaustive or to limit the technology to the precise form disclosed above. While specific examples for the technology are described above for illustrative purposes, various equivalent modifications are possible within the scope of the technology, as those skilled in the relevant artwill recognize. For example, while processes or blocks are presented in a given order, alternative implementations may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and / or modified to provide alternative or subcombinations. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed or implemented in parallel or may be performed at different times. Further any specific numbers noted herein are only examples: alternative implementations may employ differing values or ranges.

Claims

CLAIMSWhat is claimed is:

1. A fuel cell system, comprising: a plurality of electrochemical fuel cell columns, wherein each electrochemical fuel cell column of the plurality of electrochemical fuel cell columns comprises: one or more sensors, and a fuel inlet valve system configured to control fuel flow to the electrochemical fuel cell column, wherein the fuel inlet valve system comprises: a valve comprising a valve head disposed within a valve chamber and a valve stem coupled to the valve head, wherein: the valve is configured to control fuel flow between a fuel inlet tube and a fuel conduit based on a position of the valve head within the valve chamber, and the fuel conduit is configured to deliver fuel to the electrochemical fuel cell column coupled to the fuel conduit; a captive linear actuator coupled to the valve stem, wherein the captive linear actuator is configured to adjust the position of the valve head based one or more actuator signals; and a control system, comprising: a processing system, and a memory having stored thereon instructions that, upon execution by the processing system, cause the processing system to: receive health signals from the one or more sensors of each of the plurality of electrochemical fuel cell columns; analyze the health signals to determine a status of each of the plurality of electrochemical fuel cell columns; and in response to determining that a performance of a first electrochemical fuel cell column of the plurality of electrochemical fuel cell columns falls below a threshold value: transmit one or more actuator signals to the captive linear actuators of one or more fuel inlet valve systems of the plurality ofelectrochemical fuel cell columns to modify the fuel flow to the one or more electrochemical fuel cell columns.

2. The fuel cell system of claim 1, wherein: the valve head comprises a valve face; and the valve is configured to control the fuel flow between the fuel inlet tube and the fuel conduit based on a position of the valve face with respect to a valve seat within the valve chamber.

3. The fuel cell system of claim 1, wherein: the valve head comprises a ceramic ball; and the ceramic ball is configured to control the fuel flow between a fuel inlet tube and a fuel conduit based on a position of the ceramic ball with respect to a metallic ring disposed inside the fuel conduit.

4. The fuel cell system of claim 1, wherein each fuel inlet valve system further comprises: a threaded coupler comprising a thermally insulative material and configured to couple the captive linear actuator and the valve stem.

5. The fuel cell system of claim 4, wherein each fuel inlet valve system further comprises: an insulation chamber surrounding at least the threaded coupler and comprising insulation material.

6. The fuel cell system of claim 1, wherein each fuel inlet valve system comprises: valve bellows disposed about valve stem and configured to: stabilize linear motion of the valve stem; and restrict gaseous and liquid flow from an upper portion of the valve chamber toward the captive linear actuator.

7. The fuel cell system of claim 6, wherein each fuel inlet valve system further comprises: an insulation chamber surrounding at least the valve bellows and comprising insulation material.

8. The fuel cell system of claim 1, wherein each fuel inlet valve system further comprises: an insulation chamber surrounding the captive linear actuator and comprising insulation material.

9. The fuel cell system of claim 1, wherein each fuel inlet valve system further comprises: an insulation chamber surrounding at least a lower portion of the valve chamber through which the valve stem travels and comprising insulation material.

10. The fuel cell system of claim 1, wherein each fuel inlet valve system further comprises: a first link having a first end and a second end, the first end of the first link coupled to the valve stem and the second end of the first link coupled via a pivot joint to a first end of a second link; and the second link having the first end and a second end, the second end of the second link coupled to the captive linear actuator, wherein the captive linear actuator travels in a first linear motion, the valve travels in a second linear motion, and the first linear motion is orthogonal to the second linear motion.

11. The fuel cell system of claim 1, wherein the captive linear actuator comprises stepper motor control.

12. The fuel cell system of claim 1, wherein the one or more actuator signals comprise a signal to the captive linear actuator of the fuel inlet valve system associated with the first electrochemical fuel cell column instructing the captive linear actuator to close the valve of the fuel inlet valve system to inhibit the fuel flow to the first electrochemical fuel cell column.

13. The fuel cell system of claim 12, wherein the instructions comprise further instructions that cause the processing system to: contemporaneously or after the captive linear actuator closes the valve of the fuel inlet valve system associated with first electrochemical fuel cell column, analyzecurrent health signals from the one or more sensors of each active electrochemical fuel cell column of the plurality of electrochemical fuel cell columns; and transmit one or more additional signals to the captive linear actuators of one or more fuel inlet valve systems to balance thermal activity and output of the active electrochemical fuel cell columns.

14. The fuel cell system of claim 1, further comprising: a hot box, wherein the plurality of electrochemical fuel cell columns are located inside of the hot box; and a base plate located at one end of the hot box, wherein the captive linear actuator of each of the plurality of fuel inlet valve systems is mounted such that the captive linear actuator is positioned outside of the hot box.

15. The fuel cell system of claim 14, wherein each fuel inlet valve system further comprises: a fan configured to cool the captive linear actuator.

16. The fuel cell system of claim 1, wherein: one or more of the plurality of electrochemical fuel cell columns contain stacks of solid oxide fuel cells.

17. A computer-implemented method, comprising: receiving health signals from one or more sensors of each of a plurality of electrochemical fuel cell columns of a fuel cell system; analyzing the health signals to determine a status of each of the plurality of electrochemical fuel cell columns; and in response to determining that a performance of a first electrochemical fuel cell column of the plurality of electrochemical fuel cell columns falls below a threshold value: transmitting one or more actuator signals to a captive linear actuator of one or more fuel inlet valve systems associated with the plurality of electrochemical fuel cell columns to modify a fuel flow to the one or more electrochemical fuel cell columns, wherein for each of the plurality ofelectrochemical fuel cell columns, the captive linear actuator is coupled to a fuel inlet valve system.

18. The computer-implemented method of claim 17, wherein the one or more actuator signals comprise a signal to the captive linear actuator of a fuel inlet valve system coupled to the first electrochemical fuel cell column instructing the captive linear actuator to close a valve of the fuel inlet valve system coupled to the first electrochemical fuel cell column to inhibit the fuel flow to the first electrochemical fuel cell column.

19. The computer-implemented method of claim 18, further comprising: contemporaneously with or after inhibiting the fuel flow to the first electrochemical fuel cell column, analyzing current health signals from the one or more sensors of each active electrochemical fuel cell column of the plurality of electrochemical fuel cell columns; and transmitting one or more additional signals to the captive linear actuators of one or more fuel inlet valve systems coupled to active electrochemical fuel cell columns to balance thermal activity and output of the active electrochemical fuel cell columns.

20. The computer-implemented method of claim 17, wherein the plurality of electrochemical fuel cell columns comprise one or more columns containing stacks of solid oxide fuel cells.

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