Fuel cell system with valved anode tail gas oxidizer conduit assembly

Abstract

A fuel cell system includes an anode exhaust bypass element and a valved anode tail gas oxidizer conduit assembly.SOLUTION: The fuel cell system includes a hot box, a stack of fuel cells located in the hot box and configured to generate power and anode exhaust, an anode tail gas oxidizer (ATO) located in the hot box and configured to oxidize a portion of the anode exhaust, a recirculation conduit located outside the hot box and configured to receive the anode exhaust output from the hot box, a fuel conduit assembly configured to supply fuel to the stack, and an ATO conduit assembly concentrically surrounding the fuel conduit assembly and configured to receive a first portion of the anode exhaust diverted from the recirculation conduit and supply the first portion of the anode exhaust to the ATO.SELECTED DRAWING: Figure 3B

Description

[Technical Field]

[0001] Aspects of the invention relate to fuel cell systems and methods, and more particularly to fuel cell systems including an anode exhaust bypass element and a valved anode tail gas oxidizer conduit assembly. [Background technology]

[0002] Fuel cells, such as solid oxide fuel cells, are electrochemical devices that can convert energy stored in a fuel into electrical energy with high efficiency. High-temperature fuel cells include solid oxide fuel cells and molten carbonate fuel cells. These fuel cells can operate using hydrogen and / or hydrocarbon fuels. There are classes of fuel cells, such as solid oxide regenerative fuel cells, that also allow for reverse operation, such that oxidized fuel can be re-reduced to unoxidized fuel using electrical energy as an input. Summary of the Invention

[0003] According to various embodiments, a fuel cell system includes a hot box, one or more stacks of fuel cells located within the hot box and configured to generate power and anode exhaust, an anode tail gas oxidizer (ATO) located within the hot box and configured to oxidize a portion of the anode exhaust, a recirculation conduit located outside the hot box and configured to receive anode exhaust discharged from the hot box, a fuel conduit assembly configured to supply fuel to the one or more stacks, and an ATO conduit assembly concentrically surrounding the fuel conduit assembly and configured to receive a first portion of the anode exhaust diverted from the recirculation conduit and supply the first portion of the anode exhaust to the ATO.

[0004] According to various embodiments, a fuel cell power module includes a hot box, a fuel cell column including a fuel cell stack located within the hot box and configured to generate electrical power and an anode exhaust, a recirculation conduit configured to receive the anode exhaust generated by the fuel cell column and discharged from the hot box, a bypass conduit configured to fluidly connect the recirculation conduit to an exhaust treatment system, a return conduit fluidly connected to the bypass conduit, and a central column surrounded by the fuel cell column. The central column includes an anode recuperator configured to use the anode exhaust to heat fuel supplied to the fuel cell column, an anode tail gas oxidizer (ATO) surrounding the anode recuperator and configured to oxidize a portion of the anode exhaust, an anode exhaust cooling heat exchanger located above the anode recuperator, a fuel conduit assembly configured to supply fuel to the fuel cell column through the anode recuperator, wherein the central vertical axis of the fuel conduit assembly is laterally offset relative to the central vertical axis of the central column, and an ATO conduit assembly located adjacent to the fuel conduit assembly and configured to fluidly connect the return conduit to the ATO.

[0005] According to various embodiments, a fuel cell system includes a plurality of fuel cell power modules, each including at least one fuel cell column and an anode tail gas oxidizer (ATO); an oxidation module containing an exhaust oxidizer conduit and an injection nozzle located within the exhaust oxidizer conduit; a cathode exhaust manifold fluidly connecting the exhaust oxidizer to outlets of the ATOs of the plurality of fuel cell power modules; and an anode exhaust manifold fluidly connecting the injection nozzle to an anode exhaust recirculation conduit of the plurality of fuel cell power modules.

[0006] According to various embodiments, a method of operating a fuel cell system includes supplying an air inlet stream to a stack of fuel cells located within a hot box; supplying a fuel inlet stream to the stack of fuel cells through a fuel conduit assembly to generate power, a cathode exhaust, and an anode exhaust; supplying an anode exhaust outside the hot box; recirculating a first portion of the anode exhaust supplied outside the hot box to the fuel inlet stream; supplying a second portion of the anode exhaust supplied outside the hot box to an exhaust treatment system located outside the hot box; supplying a third portion of the anode exhaust supplied outside the hot box to an anode tail gas oxidizer (ATO) located within the hot box; and supplying the cathode exhaust to the ATO to oxidize the third portion of the anode exhaust.

[0007] The accompanying drawings, which are incorporated in and constitute a part of this specification, and together with the general description above and the detailed description below, illustrate exemplary embodiments of the invention. [Brief explanation of the drawings]

[0008] [Figure 1A] FIG. 1A is a schematic diagram of a SOFC system according to various embodiments of the present disclosure. [Figure 1B] FIG. 1B is a schematic diagram of a SOFC system according to various embodiments of the present disclosure. [Figure 2A] FIG. 2A is a cross-sectional view of the central column of the system of FIGS. 1A and 1B. [Figure 2B] FIG. 2B is a top view of the central column of FIG. 2A. [Figure 3A] FIG. 3A is a perspective view of a concentric manifold that may be included within the central column of FIG. 2A, according to various embodiments of the present disclosure. [Figure 3B] FIG. 3B is a cross-sectional view of a concentric manifold according to various embodiments of the present disclosure. [Figure 3C] FIG. 3C is a cross-sectional view of portion P of the central column of FIG. 2A according to various embodiments of the present disclosure. [Figure 4A] FIG. 4A is a cross-sectional view showing the fuel and anode exhaust streams entering through the central column of FIG. 2A according to various embodiments of the present disclosure. [Figure 4B] FIG. 4B is a cross-sectional view showing the anode exhaust flow exiting through the central column of FIG. 2A according to various embodiments of the present disclosure. [Figure 5A] FIG. 5A is a partially transparent perspective view showing a central column with an alternative offset manifold according to various embodiments of the present disclosure. [Figure 5B] FIG. 5B is a top view of the offset manifold of FIG. 5A according to various embodiments of the present disclosure. [Figure 6] FIG. 6 is a cross-sectional view illustrating an alternative offset manifold according to various embodiments of the present disclosure. [Figure 7A] FIG. 7A is a cross-sectional view illustrating a central column with an alternative concentric manifold according to various embodiments of the present disclosure. [Figure 7B] FIG. 7B is a perspective view of the anode exhaust conduit assembly of FIG. 7A according to various embodiments of the present disclosure. [Figure 8A] FIG. 8A is a cross-sectional view illustrating a central column with an alternative concentric manifold according to various embodiments of the present disclosure. [Figure 8B] FIG. 8B is a perspective view of the anode exhaust conduit assembly of FIG. 8A according to various embodiments of the present disclosure. [Figure 9A] FIG. 9A is a cross-sectional view illustrating a central column with an alternative concentric manifold according to various embodiments of the present disclosure. [Figure 9B] FIG. 9B is a perspective view of the anode exhaust conduit assembly of FIG. 9A according to various embodiments of the present disclosure. [Figure 10A] FIG. 10A is a perspective view of a modular fuel cell power system according to various embodiments of the present disclosure. [Figure 10B] FIG. 10B is a side view of the system of FIG. 10A. [Figure 10C] FIG. 10C is a cross-sectional view of the exhaust oxidizer of FIG. 10A. [Figure 10D] FIG. 10D is a perspective view of the injection nozzle of the exhaust oxidizer of FIG. 10C. DETAILED DESCRIPTION OF THE INVENTION

[0009] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References to specific examples and implementations are made for illustrative purposes and are not intended to limit the scope of the invention or the claims.

[0010] Solid oxide fuel cell (SOFC) systems can operate using hydrocarbon fuels such as natural gas, methane, propane, or non-hydrocarbon fuels such as hydrogen (H) or ammonia. The anode exhaust generated by a SOFC system can contain relatively small amounts of hydrogen, nitrogen (N), and carbon monoxide (CO), along with carbon dioxide and water.

[0011] 1A and 1B are schematic diagrams of an SOFC system 10 according to various embodiments of the present disclosure. FIG. 2A is a cross-sectional view of a central column 320 of the system 10 of FIGS. 1A and 1B, and FIG. 2B is a top view of the central column 320 of FIG. 2A. The SOFC system 10 may correspond to one of the power modules of a power generation system. Referring to FIGS. 1A, 1B, and 2A, the system 10 includes a hot box 100 and various components located within or adjacent to the hot box 100. The hot box 100 may house at least one fuel cell column 200 including a fuel cell stack 202, such as an SOFC stack including alternating fuel cells and interconnects. One solid oxide fuel cell includes a ceramic electrolyte such as yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (SSZ), scandia- and ceria-stabilized zirconia, or scandia-, yttria-, and ceria-stabilized zirconia, an anode electrode such as nickel-YSZ, nickel-SSZ, or nickel-doped ceria cermet, and a cathode electrode such as lanthanum strontium manganite (LSM). The interconnect can be a metal alloy interconnect, such as a chromium-iron alloy interconnect.

[0012] Hot box 100 may also house an anode recuperator heat exchanger 110, a cathode recuperator heat exchanger 120, an anode tail gas oxidizer (ATO) 130, an anode exhaust cooling heat exchanger 140, and an optional water injector 160. System 10 may also include a catalytic partial oxidation (CPOx) reactor 50, a CPOx blower 52 (e.g., a CPOx air blower), a system blower 208 (e.g., a system air blower), and an anode recycle blower 212, which may be located outside hot box 100. However, the present disclosure does not limit each of the components to a particular location with respect to hot box 100.

[0013] The CPOx reactor 50 receives a fuel inlet stream from a fuel source 20 through a first fuel inlet conduit 300A. The fuel source 20 may be a fuel tank or a utility natural gas line with a valve controlling the amount of fuel supplied to the CPOx reactor 50. A CPOx blower 52 may supply air to the CPOx reactor 50 during system startup. Fuel and / or air exhausted from the CPOx reactor 50 may be supplied to a fuel inlet 352 of a fuel conduit assembly 360 by a second fuel inlet conduit 300B. The fuel flows through the fuel conduit assembly 360 to the anode recuperator 110. The fuel is heated in the anode recuperator 110 by the fuel (anode) exhaust, and then the fuel flows from the anode recuperator 110 through the fuel conduit assembly 360 to the fuel cell column 200. The fuel conduit assembly 360 may include one or more inlet conduits, such as a third fuel inlet conduit 300C and a fourth fuel inlet conduit 300D.

[0014] The system blower 208 can be configured to supply an air flow (e.g., an air inlet flow) to the anode exhaust cooler 140 through a first air conduit 302A. The air flows from the anode exhaust cooler 140 through a second air conduit 302B to the cathode recuperator 120. The air is heated by the ATO exhaust in the cathode recuperator 120. The air flows from the cathode recuperator 120 to the fuel cell column 200 through a third air conduit 302C.

[0015] Anode exhaust (e.g., a fuel exhaust stream) generated within the fuel cell column 200 is supplied to the anode recuperator 110 through an anode exhaust collection conduit 308. The anode exhaust may contain unreacted fuel and may also be referred to herein as fuel exhaust. The anode exhaust may be supplied from the anode recuperator 110 to a second fuel inlet conduit 300B by one or more recirculation conduits 310A-310D, allowing the anode exhaust to mix with fresh fuel flowing into the second fuel inlet conduit 300B. A first recirculation conduit 310A may fluidly connect the outlet of the anode recuperator 110 to the inlet of the anode exhaust cooler 140. A second recirculation conduit 310B may fluidly connect an anode exhaust outlet 354 of the hot box 100 to a secondary anode exhaust cooler 142 located outside the hot box 100, the anode exhaust being configured to receive the anode exhaust from the anode exhaust cooler 140 located inside the hot box 100. A third recirculation conduit 310C may fluidly connect the outlet of the secondary anode exhaust cooler 142 to the inlet of the anode recirculation blower 212. A fourth recirculation conduit 310D may fluidly connect the outlet of the recirculation blower 212 to the second fuel inlet conduit 300B, where the anode exhaust mixes with incoming fresh fuel.

[0016] The secondary anode exhaust cooler 142 can be, for example, a finned radiator or heat exchanger located outside of the hot box 100. The secondary anode exhaust cooler 142 can be configured to cool the anode exhaust exhaust discharged from the hot box 100 to protect the recirculation blower from thermal stress and / or damage. In some embodiments, the hot box 100 can be located within a module cabinet or housing (shown in FIG. 10A ), and the secondary anode exhaust cooler 142 can be configured to cool the anode exhaust using ventilation air flowing through the module cabinet.

[0017] Water flows from a water source 40, such as a water tank or water pipe, through a water conduit 42 to a water injector 160. The water injector 160 can be configured to inject water into the anode exhaust flowing through a first recirculation conduit 310A. Heat from the anode exhaust (also referred to as the recirculated anode exhaust stream) evaporates the water to generate steam, humidifying the anode exhaust. The humidified anode exhaust is supplied to an anode exhaust cooler 140. Heat from the anode exhaust supplied to the anode exhaust cooler 140 can be transferred from the system blower 208 to the air inlet stream supplied to the cathode recuperator 120. The humidified and cooled anode exhaust can then be supplied from the anode exhaust cooler 140 to a secondary anode exhaust cooler 142 through a second recirculation conduit 310B. The anode recirculation blower 212 can be configured to move the anode exhaust through the second recirculation conduit 310B, the third recirculation conduit 310C, and the fourth recirculation conduit 310D into the mixer 210. The anode exhaust stream mixes with the fuel inlet stream from the second fuel inlet conduit 300B in the mixer 210 to form a humidified fuel mixture. The mixer 210 can include a “T” shaped junction between the second fuel inlet conduit 300B and the fourth recirculation conduit 310D.

[0018] The system 10 may also include one or more fuel reforming catalysts 118 located within and / or downstream of the anode recuperator 110. The reforming catalyst(s) partially reform the humidified fuel mixture before it is supplied to the fuel cell column 200.

[0019] Cathode (i.e., air) exhaust generated in the fuel cell column 200 is supplied to the ATO 130 by a first cathode exhaust conduit 304A. The system 10 may also include an exhaust catalyst 138 (see FIG. 2A) located within the ATO 130 and configured to react with exhaust components, such as carbon monoxide. The ATO exhaust flows from the ATO 130 through a second cathode exhaust conduit 304B to the cathode recuperator 120. The ATO exhaust flows from the cathode recuperator 120 out of the hot box 100 through an ATO exhaust conduit 305.

[0020] The system 10 may further include a system controller 225 configured to control various elements of the system 10. The system controller 225 may include a central processing unit configured to execute stored instructions. For example, the system controller 225 may be configured to control the fuel and / or air flow through the system 10 according to the fuel composition data by controlling the blowers 52, 208, and / or 212.

[0021] 2A and 2B, a central column 320 located inside the hot box 100 can include an anode recuperator 110, an ATO 130, and an anode exhaust cooler 140. The fuel cell columns 200 can surround the central column 320, and the cathode recuperator 120 can surround the fuel cell columns 200. As discussed in detail with respect to FIGS. 3A-3C, the central column 320 can also include a concentric manifold 350 including an anode exhaust outlet 354, a fuel conduit assembly 360, and an ATO conduit assembly 370 that includes an anode exhaust inlet 356.

[0022] Fuel inlet 352, anode exhaust outlet 354, anode exhaust inlet 356, and optionally an upper portion of anode exhaust cooler 140 can be located in the portion of central column 320 that extends outside the top surface of hot box 100. As shown in FIG. 2B , angle α formed between fuel inlet 352 and anode exhaust inlet 356 can be in the range of about 70° to about 100°, e.g., 80° to 90°. Angle β formed between fuel inlet 352 and anode exhaust outlet 354 can be in the range of about 55° to about 75°, e.g., 60° to 70°.

[0023] The anode exhaust may contain about 35% to 45% by weight of water, which can be removed using a condenser. The remaining dry content of the anode exhaust may include about 95% by weight of carbon dioxide and about 5% by weight of hydrogen and carbon monoxide.

[0024] In prior art SOFC systems, the anode exhaust can be routed directly to the ATO using a splitter, ATO injector, and / or conduits located within the hot box. However, when the anode exhaust is routed outside the hot box 100, for example, when the anode exhaust is fed to an exhaust treatment system 60 as shown in FIGS. 1A and 1B, the conduits used to return the anode exhaust to the ATO can significantly restrict the flow of the anode exhaust. In particular, the inventors have determined that space constraints within the hot box 100 limit the size of such conduits, which can result in a significant pressure drop in the system.

[0025] 1A may include an exhaust oxidizer 400, a bypass conduit 312, a return conduit 314, a treatment conduit 62, a bypass valve 316, a return valve 318 (ATO valve), a first splitter 320, and a second splitter 322. The bypass conduit 312 may fluidly connect a third recirculation conduit 310C to the inlet of the exhaust oxidizer 400. The first splitter 320 may be located on the third recirculation conduit 310C and may split the anode exhaust between the bypass conduit 312 and the recirculation blower 212. The ATO exhaust conduit 305 may also be fluidly connected to the exhaust oxidizer 400. Thus, the ATO exhaust and the anode exhaust may be discharged from the hot box 100 to the exhaust oxidizer 400 via conduits 305 and 312, respectively. 10A-10C, the exhaust oxidizer 400 can be configured to oxidize the anode exhaust using the ATO exhaust received from one or more hot boxes 100. In some embodiments, the exhaust oxidizer 400 can include one or more exhaust oxidation catalysts configured to produce carbon dioxide by oxidizing the exhaust received from one or more hot boxes 100.

[0026] Exhaust gas treatment system 60 may be fluidly connected to exhaust gas oxidizer 400 by treatment conduit 62. In the embodiment of FIG. 1A, exhaust gas treatment system 60 may include a heat recovery system that recovers heat from the exhaust gas oxidizer 400 outlet stream supplied by treatment conduit 62.

[0027] In an alternative embodiment shown in FIG. 1B, exhaust oxidizer 400 is omitted. In this embodiment, the anode exhaust is supplied to exhaust treatment system 60 via treatment conduit 62 without passing through exhaust oxidizer 400 or being mixed with the ATO exhaust flowing through ATO exhaust conduit 305. In this embodiment, exhaust treatment system 60 can include a carbon dioxide separation system configured to separate carbon dioxide from the anode exhaust to produce a commercially useful carbon dioxide product. Exhaust treatment system 60 can also include other exhaust treatment elements, such as a condenser to remove remaining water from the anode exhaust and / or at least one electrochemical pump and / or distillation system to separate other useful exhaust components, such as hydrogen and / or carbon monoxide. In some embodiments, exhaust treatment system 60 can be configured to receive exhaust from multiple hot boxes 100 (e.g., can be connected to multiple systems 10).

[0028] 1A and 1B , the return conduit 314 can be connected to a second splitter 322 located on the bypass conduit 312. The second splitter 322 divides the anode exhaust between the exhaust oxidizer 400 and the return conduit 314. The return conduit 314 fluidly connects the bypass conduit 312 to the anode exhaust inlet 356. An ATO conduit assembly 370 can fluidly connect the anode exhaust inlet 356 to the ATO 130. The bypass valve 316 can control the anode exhaust flow through the bypass conduit 312, and the return valve 318 can control the anode exhaust flow through the return conduit 314. The valves 316, 318 can be electrically operated valves, such as solenoid valves, controlled by the system controller 225.

[0029] In some embodiments, the bypass conduit 312 can be connected to a third recirculation conduit 310C that is upstream of the recirculation blower 212 with respect to the direction of the anode exhaust flow through the third recirculation conduit 310C. However, in alternative embodiments, the bypass conduit 312 may be fluidly connected to a fourth recirculation conduit 310D that is downstream of the anode recirculation blower 212 to provide additional anode exhaust flow pressure to the bypass conduit 312.

[0030] The system controller 225 may be configured to control the operation of the valves 316 , 318 and / or the recirculation blower 212 to control the flow of anode exhaust to the exhaust treatment system 60 , the ATO 130 , and / or the fuel cell column 200 .

[0031] For example, during system startup, shutdown, and / or transient operation, bypass valve 316 can be closed, return valve 318 can be open, and recirculation blower 212 can be turned off or operated at a low speed, so that anode exhaust is supplied to ATO 130 to generate heat and bring system 10 up to system operating temperature (e.g., above 700°C, e.g., 750°C to 900°C). During steady-state operation, bypass valve 316 can be opened and return valve 318 can be closed, so that all or most of the anode exhaust is supplied to exhaust treatment system 60.

[0032] In an alternative embodiment, the return valve 318 can be partially open during steady-state operation to provide a relatively low amount of anode exhaust to the ATO 130. When the system 10 operates using a hydrocarbon fuel (e.g., natural gas, methane, etc.), some amount of anode exhaust can be provided to the ATO 130 to maintain the system operating temperature during steady-state operation. In some embodiments, the amount of anode exhaust provided to the exhaust treatment system 60 and / or the ATO 130 and the corresponding amount of anode exhaust recirculated to the fuel cell column 200 can be controlled, at least in part, by controlling the speed of the recirculation blower 212.

[0033] Thus, a method of operating fuel cell system 10 includes providing an air inlet stream to stack 202 of fuel cells located within hot box 100; providing a fuel inlet stream to stack 102 through fuel conduit assembly 360 to generate electrical power, a cathode exhaust, and an anode exhaust; providing an anode exhaust (e.g., via conduit 310B) outside of hot box 100; recirculating a first portion of the anode exhaust provided outside of hot box 100 into the fuel inlet stream (e.g., via conduits 310C and 310D); supplying a second portion of the anode exhaust supplied outside the hot box to an exhaust treatment system 60 located outside the hot box 100 (e.g., via conduit 312); supplying a third portion of the anode exhaust supplied outside the hot box to an ATO 130 located within the hot box 100 (e.g., via conduit 314 and an ATO conduit assembly 370 concentrically surrounding the fuel conduit assembly 360); and supplying the cathode exhaust to the ATO 130 (e.g., via conduit 304A) to oxidize the third portion of the anode exhaust.

[0034] 1A , the method also includes supplying a second portion of the anode exhaust supplied outside the hot box 100 to an exhaust oxidizer 400 located outside the hot box 100, and supplying system exhaust from the ATO 130 to the exhaust oxidizer 400 (e.g., via conduit 305) to oxidize the second portion of the anode exhaust in the exhaust oxidizer. In the embodiment of FIG. 1A , the oxidized second portion of the anode exhaust is supplied from the exhaust oxidizer 400 to the exhaust treatment system 60.

[0035] 1A, a second portion of the anode exhaust is supplied to the exhaust oxidizer 400 during steady-state operation of the fuel cell system and is not supplied to the exhaust oxidizer 400 during start-up or shut-down of the fuel cell system, while a third portion of the anode exhaust is supplied to the ATO 130 during start-up and shut-down of the fuel cell system. Optionally, the third portion of the anode exhaust may also be supplied to the ATO 130 during steady-state operation of the fuel cell system.

[0036] Locating the bypass valve 316 and return valve 318 outside of the hot box 100 can provide the benefit of protecting the valves 316, 318 from damage due to exposure to high temperatures inside the hot box 100. For example, this configuration allows for the use of relatively inexpensive valves compared to valves rated for high temperature operation.

[0037] The present inventors have determined that space constraints within conventional SOFC systems limit the size of the conduit used to deliver the anode exhaust to the ATO, resulting in undesirable restriction of the anode exhaust flow to the ATO. Consequently, conventional systems experience excessive anode exhaust pressure drop when directing the exhaust back to the ATO. Accordingly, embodiments of the present disclosure provide various configurations that significantly improve anode exhaust flow to the ATO 130 by reducing the anode exhaust flow restriction and the corresponding anode exhaust pressure drop.

[0038] Figure 3A is a perspective view and Figure 3B is a cross-sectional view of a concentric manifold 350 that may be included within the central column 320 of Figures 2A and 2B according to various embodiments of the present disclosure. Figure 3C is a cross-sectional view of portion P of the central column 320 of Figure 2A.

[0039] 3A and 3B, concentric manifold 350 may include various metallic components welded or brazed together. For example, concentric manifold 350 may include fuel conduit assembly 360 and ATO conduit assembly 370, where fuel conduit assembly 360 is surrounded concentrically by ATO conduit assembly 370 about the vertical axis of central column 320.

[0040] The fuel conduit assembly 360 may include a first fuel conduit 362A, a second fuel conduit 362B, a first bellows 364A, and a second bellows 364B. The first fuel conduit 362A may be fluidly connected to the fuel inlet 352. The first bellows 364A may fluidly connect the first fuel conduit 362A to the second fuel conduit 362B. The second bellows 364B may fluidly connect the second fuel conduit 362B to the top plate 112 (e.g., a finger plate) of the anode recuperator 110 shown in FIG. 4A . The bellows 364A, 364B may be configured to expand and contract to accommodate differential thermal expansion between the concentric manifold 350 and other system components or within the central column 320. In other words, the bellows 364A, 364B compensate for mismatches in coefficients of thermal expansion (CTE) between components at high system operating temperatures, and also for different temperatures when the CTE is the same.

[0041] The ATO conduit assembly 370 may concentrically surround the fuel conduit assembly 360. The ATO conduit assembly 370 may include a first anode exhaust (also known as an ATO supply) conduit 372A, a second anode exhaust conduit 372B, a bellows 374, and a distribution conduit 376. The first anode exhaust conduit 372A may be fluidly connected to the anode exhaust inlet 356. The bellows 374 may fluidly connect the first anode exhaust conduit 372A to the second anode exhaust conduit 372B. A bottom of the second anode exhaust conduit 372B may be attached to the second fuel conduit 362B. The distribution conduit 376 may extend radially from the second anode exhaust conduit 372B and may fluidly connect the second anode exhaust conduit 372B to the ATO 130.

[0042] 3A and 3B, the ATO conduit assembly 370 may include six evenly spaced distribution conduits 376. However, the ATO conduit assembly 370 may include any suitable number of distribution conduits 376 that evenly distribute the anode exhaust to the ATO 130. For example, the ATO conduit assembly 370 may include between two and ten distribution conduits 376. The bellows 374 may be configured to expand and contract to accommodate differential thermal expansion between the concentric manifold 350 and other system components. In other words, the bellows 374 compensates for mismatches in coefficient of thermal expansion (CTE) between components at high system operating temperatures or to compensate for different components at different operating temperatures.

[0043] 3C , the central column 320 may include an upper cylinder 322, a lower cylinder 324, a bellows 326, the ATO injector 132, and the water injector 160. The upper cylinder 322 and the lower cylinder 324 may be connected to opposite sides of the bellows 326. The anode exhaust cooler 140 may be attached to the outer surface of the upper cylinder 322. A concentric manifold 350 may extend inside the upper cylinder 322, the bellows 326, and the lower cylinder 324.

[0044] The ATO injector 132 can be attached to the outer surface of the lower cylinder 324 such that an injection space is formed between the outer surface of the lower cylinder 324 and the inner surface of the ATO injector 132. A distribution conduit 376 can extend through the lower cylinder 324 to the inside of the ATO injector 132. An injection hole 132A can be formed in the ATO injector 132 so that anode exhaust is supplied from the ATO injector 132 to the ATO 130 through the injection hole 132A.

[0045] The anode recuperator 110 may be located inside the lower cylinder 324. An insulating layer 330 may be located on the exterior surface of the lower cylinder 324 to insulate the ATO 130 from the anode recuperator 110. The water injector 160 may be located within the lower cylinder 324 adjacent to the distribution conduit 376. The water injector 160 may comprise a curved pipe with openings for injecting liquid water or steam into the anode exhaust flowing through the first recirculation conduit 310A. A vortex generator (e.g., a sloped metal plate) 134 may be located at the top of the ATO 130 and configured to swirl the cathode exhaust entering the top of the ATO 130 from the first cathode exhaust conduit 304A.

[0046] The anode recuperator 110, the ATO 130, the anode exhaust cooler 140, and the concentric manifold 350 may all be aligned concentrically about the central vertical axis V of the central column 320. In particular, the fuel conduit assembly 360 and the ATO conduit assembly 370 may both be concentrically disposed about the vertical axis V.

[0047] FIG. 4A is a cross-sectional view showing the fuel and anode exhaust flow entering through the central column 320 of FIGS. 2A and 2B according to various embodiments of the present disclosure, and FIG. 4B is a cross-sectional view showing the anode exhaust flow exiting through the central column 320 of FIGS. 2A and 2B according to various embodiments of the present disclosure.

[0048] 3A-3C and 4A, the fuel inlet stream is provided from second fuel inlet conduit 300B to fuel inlet 352. The fuel inlet stream then flows through fuel conduit assembly 360 to anode recuperator 110. In particular, the fuel inlet stream may flow sequentially through first fuel conduit 362A, first bellows 364A, second fuel conduit 362B, and second bellows 364B before entering anode recuperator 110.

[0049] The anode exhaust is supplied from the return conduit 314 to the anode exhaust inlet 356. The anode exhaust then flows through the ATO conduit assembly 370 to the ATO 130 by flowing between the inner surface of the ATO conduit assembly 370 and the outer surface of the fuel conduit assembly 360.

[0050] Anode exhaust flows through the first anode exhaust conduit 372A and bellows 374 into the second anode exhaust conduit 372B. A distribution conduit 376 delivers the anode exhaust from the second anode exhaust conduit 372B to the ATO injector 132. The anode exhaust then flows through the holes 132A of the ATO injector 132 and is injected into the ATO 130 as a separate anode exhaust stream. Within the ATO, the anode exhaust mixes with the cathode exhaust, which flows through the vortex generators 134 to the top of the ATO 130. Radial separation of the anode exhaust into multiple anode exhaust streams at the ATO injector 132 improves the radial flow and mixing of the anode exhaust within the ATO 130. Due to the large area of ​​the ATO conduit assembly 370, the backpressure into the ATO conduit assembly 370 is relatively low, e.g., 0.1 psi or less, e.g., 0.1 psi to 0.005 psi. Thus, the ATO conduit assembly 370 can be configured to provide anode exhaust to the ATO 130 with very little pressure drop.

[0051] 3C and 4B, the anode exhaust supplied to the anode recuperator 110 can exit the top of the anode recuperator 110, flow upward through the first recirculation conduit 310A in the lower cylinder 324, and flow radially out of the concentric manifold 350. The anode exhaust can then enter the bottom of the anode exhaust cooler 140, flow upward through the anode exhaust cooler 140, and then exit the top of the anode exhaust cooler 140. The anode exhaust can then flow through the anode exhaust outlet 354 into the second recirculation conduit 310B. Because the anode exhaust flow is blocked by the wall of the lower cylinder 324, there is no direct path for the anode exhaust to flow from the anode recuperator 110 to the ATO injector 132. This allows the carbon dioxide in the anode exhaust to be separated from the ATO exhaust.

[0052] 5A is a partially transparent perspective view illustrating an alternative embodiment central column 320 with an alternative offset manifold 550, and FIG. 5B is a top view of the offset manifold 550 of FIG. 5A, according to various embodiments of the present disclosure. The central column 320 may be similar to the central column 320 of FIGS. 2A-3C. Therefore, only the differences from the central column 320 of FIGS. 2A-3C will be discussed in detail.

[0053] 5A and 5B, the offset manifold 550 may comprise a fuel conduit assembly 560 including a fuel inlet 352, a first fuel conduit 362A fluidly connected to the fuel inlet 352, and a bellows 364 fluidly connecting the first fuel conduit 362A to a second fuel conduit 362B (see FIG. 6 ) that is connected to the anode recuperator 110. The first fuel conduit 362A may include a straight upper portion 362A1 and a curved lower portion 362A2. The central vertical axis of the upper portion 362A1 may be offset relative to the central vertical axis V (see FIG. 3C ) of the central column 320. The central axis of the lower fuel conduit and the bellows 364 may be aligned with the vertical axis V of the central column 320.

[0054] The offset manifold 550 may also include an anode exhaust conduit assembly 570 including a first anode exhaust conduit 372A and a second anode exhaust conduit 372B fluidly connected to the anode exhaust inlet 356 and the ATO 130 by the ATO injector 132. The anode exhaust conduits 372A, 372B may include a straight upper portion and a curved lower portion. For example, the first anode exhaust conduit 372A may include a straight upper portion 372A1 and a curved lower portion 372A2. The central axis of the straight upper portion 372A1 may be offset with respect to the central vertical axis V (see FIG. 3C ) of the central column 320.

[0055] Thus, the upper portion of the first fuel conduit 362A can be positioned closer to the inner surface of the upper cylinder 322 to provide additional space for the anode exhaust conduits 372A, 372B within the upper cylinder 322. In other words, the offset location of the first fuel conduit 362A allows two relatively large diameter anode exhaust conduits 372A, 372B to be accommodated within the upper cylinder 322 without increasing the diameter of the upper cylinder 322. Thus, the offset manifold 550 can provide a lower anode exhaust pressure drop compared to conventional designs that include one or more smaller diameter anode exhaust conduits.

[0056] 6 is a cross-sectional view illustrating an alternative offset manifold 550A according to various embodiments of the present disclosure. The offset manifold 550A can be similar to the offset manifold 550 of FIG. 5A. Therefore, only the differences from the offset manifold 550 of FIG. 5A will be discussed in detail.

[0057] Referring to FIG. 6 , the offset manifold 550A can include an offset fuel conduit assembly including a first fuel conduit 362A, a bellows 364, and a second fuel conduit 362B, all of which can be offset from the central axis of the central column 320. The offset manifold 550A can also include a first anode exhaust conduit 372A and a second anode exhaust conduit (not shown) that fluidly connect the anode exhaust inlet 356 to the ATO injector 132. Therefore, using two straight fuel conduits 362A, 362B can reduce manufacturing costs compared to utilizing one or more curved fuel conduits. This embodiment can also reduce the likelihood of buckling of the curved conduits shown in FIG. 5A .

[0058] Figure 7A is a cross-sectional view illustrating a central column 320 with an alternative concentric manifold 750, and Figure 7B is a perspective view of an anode exhaust conduit assembly 770 of Figure 7A, according to various embodiments of the present disclosure. The central column 320 may be similar to the central column 320 of Figures 2A-3C. Therefore, only the differences from the central column 320 of Figures 2A-3C will be discussed in detail.

[0059] 7A and 7B, the concentric manifold 750 may include a fuel conduit assembly 360 concentrically positioned within an anode exhaust conduit assembly 770. The fuel conduit assembly 360 may include a first fuel conduit 362A, a first bellows 364A, and a second fuel conduit 362B, as shown in FIG. 7A. However, in other embodiments, the fuel conduit assembly 360 may optionally include a second bellows 364B, as shown in FIG. 3B.

[0060] The anode exhaust conduit assembly 770 may include a first anode exhaust conduit 772, a second anode exhaust conduit 774, and an injection conduit 776. The first anode exhaust conduit 772 and the second anode exhaust conduit 774 may surround the fuel conduit assembly 360. The inner and outer walls of the first anode exhaust conduit 772 and the second anode exhaust conduit 774 may define an annular flow path for the anode exhaust flow from the anode exhaust inlet 356, through the injection conduit 776, to the ATO 130.

[0061] The first anode exhaust conduit 772 may include a first portion 772A and a second portion 772B located below the first portion. The first portion 772A may fluidly connect the anode exhaust inlet 356 to the second portion 772B. The first portion 772A may be arcuate (e.g., wedge-shaped). In particular, the first portion 772A may have an arcuate radius ranging from about 130° to about 170°, e.g., from about 140° to about 160°, or about 150°. Thus, the first portion 772A may form an arcuate internal anode exhaust flow path. Additionally, the first portion 772A may provide additional space at the top of the central column 320 for other components, such as the anode exhaust outlet 354 and associated conduits.

[0062] The second portion 772B may be cylindrical and may be fluidly connected to a second anode exhaust conduit 774. The second portion 772B may form an annular internal anode exhaust flow path.

[0063] The second anode exhaust conduit 774 can surround the bellows 364 of the fuel conduit assembly 360. The second anode exhaust conduit 774 can have a larger diameter than the first anode exhaust conduit 772 to accommodate the bellows 364 and to utilize additional space below the upper cylinder 322 in the central column 320.

[0064] An injection conduit 776 can fluidly connect the second anode exhaust conduit 774 to the ATO 130. In particular, the injection conduit 776 can extend radially from the second anode exhaust conduit 774 through the lower cylinder 324 of the central column 320 and enter the ATO 130. In one embodiment, the ATO injector 132 may be omitted. Alternatively, the ATO injector 132 may be provided at the end of the injection conduit 776.

[0065] 8A is a cross-sectional view illustrating a central column 320 with an alternative concentric manifold 750A, and FIG. 8B is a perspective view of an anode exhaust conduit assembly 770A of FIG. 8A, according to various embodiments of the present disclosure. The central column 320 may be similar to the central column 320 of FIGS. 2A-3C. Therefore, only the differences from the central column 320 of FIGS. 2A-3C will be discussed in detail.

[0066] 8A and 8B , the concentric manifold 750A may include a fuel conduit assembly 360 concentrically positioned within an anode exhaust conduit assembly 770A. The anode exhaust conduit assembly 770A may include a first anode exhaust conduit 772 and an inlet conduit 778 that fluidly connects the first anode exhaust conduit 772 to the ATO 130. The inlet conduit 778 may extend radially from a bottom of the first anode exhaust conduit 772. For example, the inlet conduit 778 may extend downwardly through the bellows 364 to connect the first anode exhaust conduit 772 to the ATO 130.

[0067] The inlet conduit 778 can include a first conduit 778A, a second conduit 778B, and a bellows 780 connecting the first conduit 778A and the second conduit 778B. The bellows 780 can be a flexible structure configured to compensate for differences in CTE in the central column 320. The first conduit 778A and the second conduit 778B can be bent to form approximately a 90° curve. The inlet conduit 778 can be longer than the inlet conduit 776 of FIGS. 7A and 7B, and the second anode exhaust conduit 774 can be omitted.

[0068] 9A is a cross-sectional view illustrating a central column 320 with an alternative concentric manifold 750B, and FIG. 9B is a perspective view of an anode exhaust conduit assembly 770B of FIG. 9A, according to various embodiments of the present disclosure. The central column 320 may be similar to the central column 320 of FIGS. 2A-3C. Therefore, only the differences from the central column 320 of FIGS. 2A-3C will be discussed in detail.

[0069] 9A and 9B, the concentric manifold 750B can include a fuel conduit assembly 360 concentrically positioned within an anode exhaust conduit assembly 770B. The anode exhaust conduit assembly 770B can include a first anode exhaust conduit 772, a second anode exhaust conduit 774A, and an injection conduit 778 fluidly connecting the second anode exhaust conduit 774A to the ATO 130. The injection conduit 778 can include a first conduit 778A, a second conduit 778B, and a bellows 780 connecting the first conduit 778A and the second conduit 778B. The second anode exhaust conduit 774A can include a disk-shaped manifold having a larger diameter than the first anode exhaust conduit 772. Thus, the first conduit 778A can be substantially straight and extend downward from the outer periphery of the second anode exhaust conduit 774A. The second conduit 778B can be bent to form an approximately 90° bend, with the outlet of the second conduit 778B facing the ATO 130.

[0070] FIG. 10A is a partial perspective view of a modular fuel cell power system 12 according to various embodiments of the present disclosure, FIG. 10B is a partial side view of the system 12 of FIG. 10A, and FIG. 10C is a cross-sectional view of the exhaust oxidizer 400 of FIG. 10A.

[0071] 1A, 10A, and 10B, system 12 includes a plurality of power modules 500, one or more auxiliary modules 510, such as a fuel processing module, a water processing module, a telemetry module, and / or a power conditioning module, and an oxidation module 600. Power modules 500 may each include a cabinet 502 or housing within which SOFC system 10, including hot box 100 and corresponding components, is located.

[0072] The oxidation module 600 may comprise the exhaust oxidizer 400 and may be fluidly connected to the power module 500 by a cathode exhaust manifold 604 and an anode exhaust manifold 606. For clarity, only a portion of the manifolds 604, 606 are shown in FIGS. 10A and 10B. The cathode exhaust manifold 604 may be fluidly connected to the ATO exhaust conduit 305 of the power module 500, and the anode exhaust manifold 606 may be fluidly connected to the bypass conduit 312 of the power module 500. In some embodiments, a diversion conduit 608 may be connected to the cathode exhaust manifold 604 upstream of the oxidation module 600. A damper (not shown) may be used to control the flow of ATO exhaust through the diversion conduit 608.

[0073] The oxidation module 600 may comprise a cabinet or housing 602 within which the exhaust oxidizer 400 is located. As shown in FIG. 10C , the exhaust oxidizer 400 may include an oxidation conduit comprising an inlet 402, an outlet 404, an injection nozzle 410, a reaction zone 420, and an oxidation catalyst 430. A cathode exhaust manifold 604 may be configured to deliver ATO exhaust from the multiple power modules 500 to the inlet 402 of the exhaust oxidizer 400. An anode exhaust manifold 606 may be configured to deliver anode exhaust from the multiple power modules 500 to the injection nozzle 410 located within the exhaust oxidizer 400. The outlet 404 of the exhaust oxidizer 400 may be fluidly connected to a process conduit 62.

[0074] The ATO exhaust can flow from the ATO exhaust conduit 305 to the cathode exhaust manifold 604. From the cathode exhaust manifold 604, the ATO exhaust then enters the inlet 402 of the exhaust oxidizer 400, passes through the injection nozzle 410, through the reaction zone 420, and passes through the oxidation catalyst 430 before flowing to the outlet 404 of the exhaust oxidizer 400. The injection nozzle 410 can be located upstream of the reaction zone 420 and can be configured to inject the anode exhaust into the ATO exhaust stream. Thus, an oxidation reaction can occur between the anode exhaust stream and the ATO exhaust stream in the reaction zone 420. Oxidation of any remaining oxidizable species can be facilitated by the oxidation catalyst 430, which can be located downstream of the reaction zone 420. The oxidized exhaust can then be supplied to the exhaust treatment system 60 via the treatment conduit 62. While a single oxidation catalyst 430 bed is shown in FIG. 10C , in alternative embodiments, two or more oxidation catalyst 430 beds can be arranged in series within the oxidation module 600. In one embodiment, providing gaps between oxidation catalyst 430 beds allows for better mixing of the ATO exhaust and the anode exhaust and / or allows the combined exhaust stream to have a longer residence time at elevated temperatures before being fed to the subsequent oxidation catalyst 430 bed.

[0075] 10D , the injection nozzle 410 can include at least one conduit having one or more openings. For example, the injection nozzle 410 can include a horizontal conduit 402 connected to the anode exhaust manifold 606, a vertical conduit 404 connected to the horizontal conduit 402, a central distribution hub 405, a central distribution conduit 406 extending horizontally from the central distribution hub 405, and peripheral distribution conduits 408 extending horizontally from the central distribution conduit 406 in a direction perpendicular to the direction of the central distribution conduit 406. The peripheral distribution conduit 408 includes an opening 409 facing upward toward the reaction zone 420. The vertical conduit 404, the central distribution hub 405, the central distribution conduit 406, and the peripheral distribution conduit 408 are located inside the exhaust oxidizer 400. The anode exhaust flows from anode exhaust manifold 606 through conduits 402 and 404, hub 405, conduits 406 and 408, and out opening 409 into reaction zone 420 where it mixes with the ATO exhaust.

[0076] The fuel cell systems of the disclosed embodiments are designed to reduce greenhouse gas emissions and have a positive impact on the climate.

[0077] The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art. Furthermore, the general principles defined herein may be applied to other embodiments without departing from the scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Hot box and one or more stacks of fuel cells located within the hot box and configured to generate electrical power and an anode exhaust; an anode tail gas oxidizer (ATO) located within the hot box and configured to oxidize a portion of the anode exhaust; a recirculation conduit located outside the hot box and configured to receive the anode exhaust discharged from the hot box; a fuel conduit assembly configured to supply fuel to the one or more stacks; an ATO conduit assembly concentrically surrounding the fuel conduit assembly and configured to receive a first portion of the anode exhaust diverted from the recirculation conduit and to supply the first portion of the anode exhaust to the ATO; A fuel cell system comprising:

2. The fuel conduit assembly includes: A fuel inlet; a first fuel conduit fluidly connected to the fuel inlet; a second fuel conduit fluidly connected to the anode recuperator; a first bellows fluidly connecting the first fuel conduit and the second fuel conduit; 10. The fuel cell system of claim 1, comprising:

3. The ATO conduit assembly includes: an anode exhaust inlet; a first anode exhaust conduit fluidly connected to the anode exhaust inlet and surrounding the first fuel conduit; a second anode exhaust conduit surrounding the second fuel conduit; a second bellows fluidly connecting the first anode exhaust conduit and the second anode exhaust conduit and surrounding the first bellows; an injection conduit fluidly connecting the second anode exhaust conduit to the ATO; 3. The fuel cell system of claim 2, comprising:

4. 4. The fuel cell system of claim 3, wherein the injection conduit extends radially from the second anode exhaust conduit and supplies the anode exhaust to an ATO injector having an injection hole, the ATO injector configured to inject the first portion of the anode exhaust into the ATO.

5. an anode recuperator located within the hot box and configured to use the anode exhaust to heat the fuel supplied to the one or more stacks; The fuel cell system of claim 3 , wherein the fuel conduit assembly is configured to supply fuel to the one or more stacks through the anode recuperator.

6. an anode exhaust cooling heat exchanger surrounding the first anode exhaust conduit; 6. The fuel cell system of claim 5, wherein the anode recuperator is located below the anode exhaust cooling heat exchanger and the fuel conduit assembly and is surrounded by the ATO.

7. The ATO conduit assembly includes: an anode exhaust inlet; a first anode exhaust conduit fluidly connected to the anode exhaust inlet and including an arcuate first portion partially surrounding an upper portion of the first fuel conduit, and a cylindrical second portion fluidly connected to the first portion and surrounding a lower portion of the first fuel conduit; a second anode exhaust conduit fluidly connected to the second portion of the first anode exhaust conduit and surrounding the first bellows; an injection conduit fluidly connecting the second anode exhaust conduit to the ATO; 3. The fuel cell system of claim 2, comprising:

8. 8. The fuel cell system of claim 7, wherein the injection conduit extends radially outward from a side of the second anode exhaust conduit and fluidly connects to the ATO.

9. 8. The fuel cell system of claim 7, wherein the injection conduit extends downward from a bottom surface of the second anode exhaust conduit and then extends radially outward to fluidly connect to the ATO.

10. The ATO conduit assembly includes: an anode exhaust inlet; a first anode exhaust conduit, an arcuate first portion fluidly connected to the anode exhaust inlet and partially surrounding an upper portion of the first fuel conduit; a cylindrical second section fluidly connected to the arcuate first section and surrounding a lower portion of the first fuel conduit; the first anode exhaust conduit comprising: an infusion conduit fluidly connecting the cylindrical second portion to the ATO, the infusion conduit including a first curved conduit extending from a side of the cylindrical second portion, a second curved conduit extending from the ATO, and a bellows fluidly connecting the first curved portion and the second curved portion; 3. The fuel cell system of claim 2, comprising:

11. a bypass conduit fluidly connecting the recirculation conduit to an exhaust oxidizer and configured to supply a second portion of the anode exhaust to the exhaust oxidizer; a return conduit fluidly connecting the bypass conduit to the ATO conduit assembly; a bypass valve configured to control the second portion of the anode exhaust flow through the bypass conduit; a return valve configured to control the first portion of the anode exhaust flow through the return conduit; The fuel cell system of claim 1 further comprising:

12. The fuel cell system of claim 11 , wherein the one or more stacks are disposed within a fuel cell column disposed within the hot box.

13. a central column located within the hot box and surrounded by the fuel cell columns; The central column is an anode recuperator configured to use the anode exhaust to heat the fuel supplied to the fuel cell column; the anode tail gas oxidizer (ATO) surrounding the anode recuperator; an anode exhaust cooling heat exchanger located above the anode recuperator; the fuel conduit assembly; the ATO conduit assembly; The fuel cell system of claim 12 , comprising:

14. the hot box is located within a first power module cabinet; The fuel cell system of claim 12 , wherein a system exhaust conduit is fluidly connected to the outlet of the ATO.

15. a plurality of additional power module cabinets each housing an additional hot box housing an additional fuel cell column; an oxidation module cabinet that houses the exhaust gas oxidizer; a cathode exhaust manifold fluidly connecting the exhaust oxidizer to the system exhaust conduit of the first power module cabinet and to a system exhaust conduit of each of the additional power module cabinets; an anode exhaust manifold fluidly connecting the exhaust oxidizer to the bypass conduit of the first power module cabinet and to each bypass conduit of the additional power module cabinets; The fuel cell system of claim 14 further comprising:

16. The exhaust gas oxidizer comprises: an oxidation conduit fluidly connecting the cathode exhaust manifold to an exhaust treatment system configured to separate components in the exhaust oxidizer exhaust stream; an injection nozzle located within the oxidation conduit, fluidly connected to the anode exhaust manifold, and configured to inject the second portion of the anode exhaust into an ATO exhaust to oxidize the second portion of the anode exhaust; an oxidation catalyst located within the oxidation conduit; 16. The fuel cell system of claim 15, comprising:

17. Hot box and a fuel cell column located within the hot box and including a fuel cell stack configured to generate electrical power and an anode exhaust; a recirculation conduit configured to receive the anode exhaust generated by the fuel cell column and discharged from the hot box; a bypass conduit configured to fluidly connect the recirculation conduit to an exhaust treatment system; a return conduit fluidly connected to the bypass conduit; a central column surrounded by the fuel cell columns; The central column is an anode recuperator configured to use the anode exhaust to heat fuel supplied to the fuel cell column; an anode tail gas oxidizer (ATO) surrounding the anode recuperator and configured to oxidize a portion of the anode exhaust; an anode exhaust cooling heat exchanger located above the anode recuperator; a fuel conduit assembly configured to supply the fuel to the fuel cell column through the anode recuperator, the fuel conduit assembly having a central vertical axis that is laterally offset from the central vertical axis of the central column; an ATO conduit assembly located adjacent to the fuel conduit assembly and configured to fluidly connect the return conduit to the ATO; A fuel cell power module comprising:

18. a plurality of fuel cell power modules each comprising at least one fuel cell column and an anode tail gas oxidizer (ATO); an oxidation module containing an exhaust oxidizer conduit and an injection nozzle located within the exhaust oxidizer conduit; a cathode exhaust manifold fluidly connecting an exhaust oxidizer to the outlets of the ATOs of the plurality of fuel cell power modules; an anode exhaust manifold fluidly connecting the injection nozzle to an anode exhaust recirculation conduit of the plurality of fuel cell power modules; A fuel cell system comprising:

19. 1. A method of operating a fuel cell system, comprising: providing an air inlet flow to a stack of fuel cells located within the hot box; providing a fuel inlet stream to the stack of fuel cells through a fuel conduit assembly to generate electrical power, a cathode exhaust, and an anode exhaust; supplying the anode exhaust outside the hot box; recirculating a first portion of the anode exhaust delivered external to the hot box to the fuel inlet stream; supplying a second portion of the anode exhaust supplied outside the hot box to an exhaust treatment system located outside the hot box; supplying a third portion of the anode exhaust supplied outside the hot box to an anode tail gas oxidizer (ATO) located within the hot box; supplying the cathode exhaust to the ATO to oxidize the third portion of the anode exhaust; A method comprising:

20. supplying the second portion of the anode exhaust supplied outside the hot box to an exhaust oxidizer located outside the hot box; supplying system exhaust from the ATO to the exhaust oxidizer to oxidize the second portion of the anode exhaust, the oxidized second portion of the anode exhaust being supplied from the exhaust oxidizer to the exhaust treatment system; 20. The method of claim 19 further comprising:

21. the second portion of the anode exhaust is supplied to the exhaust oxidizer during steady-state operation of the fuel cell system and is not supplied to the exhaust oxidizer during start-up or shut-down of the fuel cell system; the third portion of the anode exhaust is supplied to the ATO during the start-up and the shut-down of the fuel cell system; 21. The method of claim 20, wherein the third portion of the anode exhaust is supplied to the ATO through an ATO conduit assembly that concentrically surrounds the fuel conduit assembly.

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