Solid oxide fuel cell system with carbon capture and increased efficiency

Abstract

A fuel cell system comprises a fuel cell module having an inlet and an outlet. The fuel cell module receives a fuel stream containing gaseous fuel and discharges a degraded fuel stream. The system also includes an exhaust treatment module positioned relative to the fuel cell module so that waste heat from the fuel cell module is available to the exhaust treatment module. The system is configured to direct a first portion of the degraded fuel stream to the exhaust treatment module, wherein the degraded fuel stream contains degraded fuel and at least one gaseous byproduct including oxygen and carbon dioxide. The exhaust treatment module causes the first portion of the degraded fuel stream to co-electrolyze using waste heat from the fuel cell module to produce a fuel-enrichment stream. The system is configured to direct the fuel-enrichment stream to the inlet of the fuel cell module.

Description

Technology Field

[0001] Cross-reference regarding related applications

[0002] This application claims interest and priority to U.S. Provisional Application No. 63 / 199060, filed on December 4, 2020, the entirety of which is incorporated herein by reference. Background Technology

[0003] The present application generally relates to the field of solid oxide fuel cell (SOFC) systems, and more specifically to an SOFC system having a high-purity carbon dioxide (CO2) exhaust stream to facilitate carbon capture.

[0004] Generally, a fuel cell comprises an anode, a cathode, and an electrolyte layer that induce a chemical reaction to produce electricity. Specifically, an SOFC is a solid-state electrochemical cell comprising a solid, gas-impermeable electrolyte interposed between a porous anode and a porous cathode. Oxygen is transported through the cathode to the cathode / electrolyte interface, where it is reduced to oxygen ions that migrate through the electrolyte to the anode. At the anode, ionic oxygen reacts with a fuel, such as hydrogen or methane, to release electrons. These electrons then travel through an external circuit to the cathode to generate power.

[0005] Anode exhaust, which may contain a mixture of steam, hydrogen, carbon monoxide, and carbon dioxide, is produced as a byproduct from the anode of a fuel cell. Anode exhaust contains useful byproduct gases such as hydrogen and carbon monoxide, which can be discharged as syngas for other uses, such as fuel for fuel cells or feed for other chemical reactions. Additionally, CO2 and water in the exhaust may also be discharged for sequestration or further downstream processing. However, to prepare the anode exhaust for these uses, the CO2 present in the anode exhaust must be separated from the remaining byproduct gases.

[0006] Therefore, it would be advantageous to provide an SOFC system that delivers a CO2-rich exhaust stream to enable easy carbon capture without compromising system efficiency or incurring excessive operating costs. means of solving the problem

[0007] One aspect of the present invention relates to a fuel cell system. The system comprises a fuel cell module having an inlet and an outlet, wherein the fuel cell module is configured to receive a fuel stream containing gaseous fuel at the inlet and discharge a depleted fuel stream at the outlet. The system further comprises an exhaust treatment module in fluid communication with the fuel cell module. The exhaust treatment module is positioned relative to the fuel cell module so that waste heat from the fuel cell module is available to the exhaust treatment module. The system is configured to direct a first portion of the depleted fuel stream to the exhaust treatment module, wherein the depleted fuel stream contains at least one gaseous byproduct including depleted fuel and oxygen and carbon dioxide. The exhaust treatment module is configured to co-electrolyze the first portion of the depleted fuel stream using waste heat from the fuel cell module to produce a fuel-enriched stream. The system is configured to direct the fuel-enrichment stream to the inlet of the fuel cell module.

[0008] In various embodiments, the system also includes a controller configured to operate at least one of a fuel cell module or an exhaust treatment module based on the composition of the depleted fuel stream. In some embodiments, the fuel cell module includes at least one solid oxide fuel cell. In other embodiments, the exhaust treatment module includes at least one solid oxide electrolysis stack. In yet another embodiment, the exhaust treatment module is contained within the fuel cell module. In various embodiments, the fuel cell module includes a plurality of fuel cell stacks, a first subset of the plurality of fuel cell stacks is a solid oxide fuel cell, and a second subset of the plurality of fuel cell stacks is a solid oxide electrolysis stack. In some embodiments, the exhaust treatment module is separated from the fuel cell module. In other embodiments, the exhaust treatment module includes a plurality of branches connected in parallel, each of the plurality of branches has at least one solid oxide electrolysis stack, and each solid oxide electrolysis stack includes a plurality of solid oxide electrolysis cells.

[0009] In various embodiments, the system further includes an afterburner that is fluidly connected to the fuel cell module and positioned downstream of the outlet. In some embodiments, the afterburner is configured to receive a second portion of the depleted fuel stream and produce a first exhaust stream by reacting the unreacted fuel within the second portion. In other embodiments, the exhaust treatment module is configured to discharge oxygen produced during the co-electrolysis of the first portion into the exhaust stream. In yet another embodiment, the system is configured to direct the exhaust stream to the afterburner, whereby oxygen from the first exhaust stream facilitates the combustion of the unreacted fuel contained within the first portion. In various embodiments, the afterburner is configured to discharge a second exhaust stream consisting of carbon dioxide. In some embodiments, the exhaust treatment module is configured to provide a reducing gas to the fuel cell module. In other embodiments, the exhaust treatment module is configured to provide a reducing gas during a shutdown event of the fuel cell system.

[0010] Another aspect of the present invention relates to a method of operating a fuel cell system. The method is configured such that a fuel cell module discharges a depleted fuel stream from an outlet, and the fuel cell module receives gaseous fuel at an inlet. The method further comprises the step of receiving a first portion of the depleted fuel stream by an exhaust treatment module, wherein the first portion comprises depleted fuel and at least one gaseous byproduct comprising carbon dioxide and oxygen. The method also comprises the step of producing a fuel-enriched stream from a first portion of the depleted fuel stream by co-electrolyzing the first portion using waste heat from the fuel cell module by an exhaust treatment module. The method further comprises the step of directing the fuel-enriched stream produced by the exhaust treatment module to the fuel cell module by the fuel cell system.

[0011] In some embodiments, the method also includes the step of receiving a second portion of a depleted fuel stream by an afterburner fluidly communicating with a fuel cell module, and the step of generating a first exhaust stream by reacting unreacted fuel in the second portion by the afterburner. In various embodiments, the method also includes the step of removing water from at least a portion of a fuel-enriched stream by a water knockout unit fluidly communicating with an exhaust treatment module. In another embodiment, the method further includes the step of operating at least one of the fuel cell module or the exhaust treatment module based on the composition of the depleted fuel stream by a controller communicating with the fuel cell system. In yet another embodiment, the controller is configured to adjust the operating conditions of at least one of the fuel cell system based on the composition of the gaseous fuel within the fuel cell system. Brief explanation of the drawing

[0012] The advantages and features constituting the present disclosure, and the clear concept of the configuration and operation of a typical mechanism provided by the present disclosure, will become more readily apparent by referring to the non-limiting embodiments illustrated in the accompanying drawings and forming part of the specification, wherein the same reference numerals designate the same elements in multiple drawings. FIG. 1 is a schematic diagram of a fuel cell system according to one embodiment of the present invention. FIG. 2 is a schematic diagram of a fuel cell system including an exhaust gas treatment module for carbon capture according to one embodiment of the present invention. FIG. 3 is a schematic diagram of a fuel cell system according to another embodiment of the present invention. FIG. 4 is a schematic diagram of a fuel cell system including an exhaust treatment module for carbon capture according to another embodiment of the present invention. The foregoing and other features of the present disclosure will become apparent from the following description taken together with the accompanying drawings and the appended claims. It is understood that these drawings illustrate only some embodiments according to the present disclosure and are therefore not to be construed as limiting the scope thereof. The present disclosure will be described in additional specifics and details through the use of the accompanying drawings. Specific details for implementing the invention

[0013] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, unless otherwise indicated by the context, similar symbols typically identify similar components. The exemplary embodiments described in the detailed description, drawings, and claims are not intended to be limiting. Other embodiments may be used and other modifications made without departing from the spirit or scope of the subject matter set forth in this specification. It will be readily understood that the aspects of the present disclosure outlined herein and illustrated in the drawings may be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly considered and manufactured as part of the present disclosure.

[0014] The present invention provides a fuel cell system that enables effective CO2 treatment and subsequent carbon capture without inducing an efficiency penalty. Furthermore, the fuel cell system of the present invention includes an exhaust treatment module that facilitates the generation of a CO2-rich exhaust stream enabling carbon capture, as well as providing increased operating efficiency compared to conventional systems. The fuel cell system avoids known limitations associated with conventional fuel cell systems configured to recirculate the anode exhaust stream (e.g., for a dilution effect).

[0015] One embodiment of the present disclosure relates to a fuel cell system comprising a fuel supply unit, an air supply unit, and a fuel cell module coupled to a variable load. The fuel cell module may be configured to receive fuel from the fuel supply unit through a fuel inlet at a fuel electrode (e.g., anode) and to receive air from the air supply unit through an air inlet at an air electrode (e.g., cathode). The fuel cell system may further comprise an exhaust treatment module and / or a combustion component (e.g., an afterburner) that may be fluidly coupled to the outlet of the fuel cell module. The exhaust treatment module may be configured to receive at least a portion of the fuel exhaust discharged from the outlet of the fuel cell module as a recirculation stream. The exhaust treatment module may be further configured to treat the received fuel exhaust to enrich the fuel content within the recirculation stream before routing the recirculation stream back to the fuel inlet.

[0016] In various embodiments, the exhaust treatment module may be configured as a Solid Oxide Electrolytic Stack (SOEC) module. Thus, the SOEC module can accommodate a portion of the fuel cell exhaust and enrich the fuel content through a co-electrolysis process, thereby lowering the net fuel supply requirements for the fuel cell system. In various embodiments, the SOEC module may be configured to utilize waste heat from the fuel cell to facilitate operation within the endothermic region, thereby increasing the efficiency of the SOEC module.

[0017] A second embodiment relates to the use of electrolytically produced oxygen (e.g., produced by an SOEC module) as an oxidizer for a combustion component (e.g., an afterburner). In various embodiments, using the electrolytic product as an oxidizer allows the exhaust product to be combusted without introducing nitrogen (e.g., from air) so that the final outlet becomes a nearly pure blend of CO2 and H2O. In various embodiments, H2O is removed from the blend by condensation, leaving a high-purity CO2 stream ready for isolation or downstream processing.

[0018] Referring to FIG. 1, a schematic diagram of a conventional fuel cell system (10) is shown. The fuel cell system (10) may be a solid oxide fuel cell (SOFC) system having an SOFC module (15) that is fluidly flowably coupled to an air supply unit (20) and a fuel supply unit (25) and configured to generate power in the form of electricity therefrom. The SOFC module (15) may include a solid electrochemical cell, which includes a solid, gas-impermeable electrolyte (e.g., dense ceramic) interposed between a porous anode (e.g., porous ceramic) and a porous cathode (e.g., porous ceramic). Oxygen supplied to the SOFC module (15) through the air supply unit (20) may be transported through the cathode to the cathode / electrolyte interface within the SOFC module (15), where it is reduced to oxygen ions. Then, the oxygen ions may move through the electrolyte within the SOFC module (15) to the anode. At the anode, ionic oxygen can react with input fuel (30) received from the fuel supply unit (25) through the inlet manifold (35). In various embodiments, the fuel may be hydrocarbons, synthesis gas, or any suitable fuel known in the art to release electrons when reacting with ionic oxygen. Power is produced when the electrons move back to the cathode through an external circuit.

[0019] When ionic oxygen (i.e., produced from the received air supply unit (20)) is reacted with the input fuel (30), the SOFC module (15) can output oxygen-depleted air (40) and depleted fuel (45) streams. As illustrated, the depleted fuel stream (45) can be routed to an output manifold (50), where a first portion (55) of the depleted fuel (45) can be sent to a fluidly flowable coupled combustion component ("afterburner") (60), and a second portion or recirculation stream (70) of the depleted fuel (45) can form a recirculation stream back to the fuel inlet manifold (35). The afterburner (60), which can also receive the depleted air (40), enables the combustion of residual oxidizer from the depleted air (40) and the first portion (55) of the depleted fuel (45), thereby producing CO2, nitrous oxide (NO₂). x It is configured to produce an exhaust stream (65) containing nitrogen (N2) and H2O. The exhaust stream (65) may further contain oxygen (O2) when the system (10) operates with excess air.

[0020] In various embodiments, the SOFC module (15) may comprise a single SOFC cell. In other embodiments, the SOFC module (15) may comprise a plurality of assembled fuel cells to form a fuel cell stack. In other embodiments, the SOFC module (15) may comprise a plurality of fuel cell stacks. In various embodiments, the SOFC module (15) may be configured to output electricity based on demand from one or more variable loads. In various embodiments, the SOFC module (15) and / or combined components within the fuel cell system (10) may be communicably coupled to one or more controllers to facilitate operation.

[0021] The fuel cell system (10) includes a recirculation stream for recirculating depleted fuel (45) back to the SOFC module inlet (30). A fuel recirculation stream, such as the fuel recirculation stream (70), can be used to provide two advantages. In the case of hydrocarbon fuel, the product water in the depleted fuel stream (45) can support the steam reforming of the fuel (25), thereby simplifying the entire system by eliminating the requirement for a separate water supply. Additionally, the fuel recirculation stream (70) can favorably increase the total fuel content while adversely reducing the fuel concentration at the fuel input (30). It is recognized by modern technology that excess fuel is typically required for the best overall system lifespan and efficiency. In particular, it is recognized that it is not practical to operate an SOFC module, such as the SOFC module (15), without excess fuel provided by the fuel supply unit (25). For example, if the SOFC module (15) is operated solely by stoichiometric fuel input from the fuel supply unit (25), the result will be a completely depleted outlet fuel (e.g., depleted fuel stream (45)), which is potentially advantageous for carbon capture but will destabilize the SOFC module (15) and negatively affect both its lifespan and efficiency. Therefore, the amount of fuel required supplied by the fuel supply unit (25) may typically exceed at least 10% of the amount of fuel electrochemically reacted within the SOFC module (15). Additionally, as the fuel cell system (10) generates an exhaust stream (65) containing various greenhouse gases and any unreacted fuel, this exhaust stream (65) must be discharged for downstream treatment before distribution for various use applications or before decontamination of the gases within the exhaust stream (65). Such additional treatment further reduces the efficiency of the fuel cell system (10).

[0022] FIG. 2 illustrates a schematic diagram of a fuel cell system (100) according to an exemplary embodiment. In various embodiments, the elements (115 to 170) of the fuel cell system (100) are identical or equivalent to the corresponding elements (15 to 70) of the fuel cell system (10). As illustrated in FIG. 2, the fuel cell system (100) may further include an exhaust treatment module (175) fluidly flowably coupled to a second portion (170) of the depleted fuel (145). In various embodiments, the exhaust treatment module (175) may be an SOEC module. The SOEC module (175) may include a plurality of electrically parallel connected branches, each branch comprising at least one solid oxide water electrolysis cell stack, and each solid oxide water electrolysis cell stack comprising a plurality of solid oxide water electrolysis cells. In various embodiments, the SOEC module (175) includes an anode, an electrolyte layer, and a cathode, and the electrolyte layer serves to transfer ions between the anode and the cathode to facilitate a reaction that generates electricity by generating electrons.

[0023] As described, the SOEC module (175) may be positioned relative to the SOEC module (115) so that waste heat (180) from the SOFC module (115) can be used to support operation by the SOEC module (175). The SOEC module (175) may receive a second portion (170) of depleted fuel (145), which will contain unreacted fuel remaining from the SOFC module (115) and various gaseous byproducts such as, but not limited to, CO2 and H2O. The SOEC module (175) may undergo a co-electrolysis process (i.e., electrolysis of both H2O and CO2) facilitated by the waste heat (180) and depending on the received second portion (170), whereby the gaseous byproducts may react to form fuel and oxygen. Accordingly, the SOEC module (175) can output a fuel-enriched recirculation stream (185), which can then be routed to an input manifold (135) for recirculation through the SOFC module (115). Oxygen produced by the SOEC module (175) can be removed from the SOEC module (175) in the effluent stream (190) and supplied as an oxidizer to the afterburner (160) to facilitate the combustion of unreacted fuel remaining in the first portion (155) of the depleted fuel (145). As illustrated, implementing the effluent stream (190) from the SOEC module (175) as an oxidizer for the afterburner (160) can enable complete combustion of the fuel in the first portion (155) such that the final exhaust stream (165) from the afterburner consists almost exclusively of CO2 and H2O.

[0024] Because the fuel cell system (100) regenerates fuel within the SOEC module (175) to produce a richened recirculation stream (185) from a second portion (170) of depleted fuel (145) from the SOFC module (115), the fuel cell system (100) can reduce the net fuel supply (125) required to operate the fuel cell system (100) (e.g., compared to the fuel cell system (10)). The efficiency loss resulting from the operation of the SOEC module (175) can be compensated for by a reduction in the inlet fuel requirement (125), the use of waste heat (180), and / or increased efficiency due to an improved gas composition at the inlet (130) (i.e., a higher fuel content due to a concentrated recirculated stream (185)), the latter of which can enable lower relative parasitism within the fuel cell system (100) and / or a higher operating voltage of the SOFC module (115) (e.g., compared to that of the fuel cell system (10)).

[0025] In various embodiments, the SOEC module (175) may be configured as a separate module from the SOFC module (115) and may exchange heat with it through one or more gas streams. In another embodiment, the SOFC module (115) may include a plurality of stacks, each stack may include a plurality of cells, and some of the cells within each stack may be SOEC cells. In yet another embodiment, the SOFC module (115) and the SOEC module (175) may collectively form a plurality of stacks, wherein the SOEC module (175) is included within one of the plurality of stacks.

[0026] In various embodiments, the SOEC module (175) may be configured to contribute to the balance of the plant and / or load after the operation of the fuel cell system (100) by assisting load absorption and / or power release. In various embodiments, the SOEC module (175) may be configured to facilitate the preservation of the fuel cell system (100) components during a shutdown event. In various embodiments, the SOEC module (175) may be configured to act as a source of reducing gas to protect the anode of the SOFC module (115). In various embodiments, the SOEC module (175) may be configured to introduce reducing gas over a period of time during or immediately after a shutdown event.

[0027] In various embodiments, the fuel cell system (100) may be operably coupled to one or more controllers, and the one or more controllers are configured to control the operation of the SOFC module (115), SOEC module (175), and / or other components included within the fuel cell system (100). Accordingly, in various embodiments, the fuel cell system (100) may be configured to monitor the composition of the fuel gas input within the SOFC module (115) (e.g., input fuel (130)) and / or the SOEC module (175) (e.g., depleted fuel portion (170)). In various embodiments, the fuel cell system (100) may be configured to monitor the composition of the fuel gas output from the SOFC module (115) (e.g., depleted fuel (145)) and / or the SOEC module (175) (e.g., enriched recirculation stream (185)). Accordingly, the controller may be configured to set and / or adjust one or more operating conditions of the fuel cell system (100) based on the monitored fuel gas composition within the system (100). In various embodiments, the fuel cell system (100) may be configured to implement the fuel gas composition according to a protocol, wherein, upon determination (e.g., by the controller) that the fuel gas composition does not satisfy one or more predetermined thresholds, the SOFC module (115) and / or SOEC module (175) may coordinate operations cooperatively or complementarily to restore the fuel gas composition to a satisfactory level (i.e., at the inlet and / or outlet within the system (100). In various embodiments, the fuel cell system (100) may be configured to adjust the amount of fuel gas provided by the fuel supply unit (125) based on the fuel gas determination (e.g., by the controller).

[0028] In various embodiments, the fuel cell system (100) may be operated at or around operating conditions (i.e., conditions known in the art as 100% fuel utilization conditions) where the inflow fuel flow (125) can be set to roughly match the fuel electrochemically consumed in the SOFC module (115). Thus, when the inflow fuel flow (125) is controlled so that substantially all inflow fuel is electrochemically consumed in the SOFC module (115), the amount of unreacted fuel in the first portion (155) of the depleted fuel stream (145) can be largely determined by the operating conditions of the SOEC module (175). In the case of a pure reactant (e.g., pure methane), such control may require scaling the inflow fuel flow (125) in proportion to the operating current. For fuels having various compositions (e.g., natural gas), direct scaling of the incoming fuel stream (125) may only be possible by considering the composition of the incoming fuel and / or exhaust along with composition measurements to facilitate optimal CO2 capture. Exemplary composition measurements may include characterization of the incoming fuel stream (125) or exhaust (e.g., depleted fuel stream (145), exhaust stream (165)) using gas chromatography or similar analysis. Additionally or alternatively, measurement of the oxygen concentration in the exhaust stream (e.g., depleted fuel stream (145), exhaust stream (165)) may be performed, for example, using one or more oxygen sensors. Accordingly, the amount of oxygen in the effluent stream (190) can roughly match the excess fuel in the first portion (155) of the depleted fuel stream (145) when the SOEC module (175) is operated under stoichiometric conditions, so that in the case of a substantially complete reaction, the afterburner (160) can convert the remaining unreacted fuel into H2O and / or CO2. Thus, for example, the ratio of fuel supplied by the fuel supply unit (125) to the output of the SOFC module (115) is 1.By varying the stoichiometry in the afterburner (160) to greater than and less than 0, the stoichiometry can be changed correspondingly from lean to rich, respectively. Unlike conventional systems such as fuel cell systems (10) that always require excess fuel from the fuel supply unit (25), the fuel enrichment provided by the SOEC module (175) in the fuel cell system (200) can instead enable stable operation with the incoming fuel from the fuel supply unit (125) at a level below that required to support the electrochemical power production of the SOFC module (115).

[0029] In various embodiments, the fuel cell system may include one or more components for increasing and / or controlling the flow of air and / or fuel gas within it. FIG. 3 illustrates a schematic diagram of a conventional fuel cell system (200). The fuel cell system (200) may be an SOFC system having an SOFC module (215) that is fluidly coupled to an air supply unit (220) and a fuel supply unit (225) and configured to generate power to support a variable load (217). The heat generated by the SOFC module (215) may be released as waste heat (219). As illustrated, air from the air supply unit (220) may be introduced into the fuel cell system (200) through an air intake manifold (221) and may be circulated to the SOFC module (215) through one or more blowers (224) that are fluidly coupled to the air intake line (227). Similarly, fuel from the fuel supply unit (224) can be introduced into the fuel cell system (200) through the fuel gas inlet manifold (235) and can be circulated to the SOFC module (215) through one or more blowers (237) fluidly coupled to the fuel gas inlet line (230). As illustrated, oxygen-depleted air can flow away from the SOFC module (215) through the depleted air stream (240). Similarly, fuel-depleted fuel gas can flow away from the SOFC module (215) through the depleted fuel gas stream (245). The depleted fuel gas stream (245) can be fluidly coupled to the fuel output manifold (250), where the depleted fuel gas stream (245) can be divided into a first depleted stream (255) and a second depleted stream (270).As described, the first depleted stream (255) can be routed together with the depleted air stream (240) to an afterburner (260) configured to combust the remaining fuel from the first depleted stream (255) with oxygen from the depleted air stream (240). In various embodiments, the afterburner (260) can be fluidly coupled to one or more processing units (263) capable of processing combustion products and outputting them as an exhaust stream (265) containing a plurality of gaseous byproducts and water.

[0030] As illustrated in FIG. 3, the second depleted fuel stream (270) can flow as a recirculation stream from the fuel outlet manifold (250) toward the fuel inlet manifold (235), so that the depleted fuel can be recirculated to the SOFC module (215) through the fuel gas inlet line (230) and the blower (237). In various embodiments, the depleted fuel stream (270) can simultaneously provide additional fuel (at a lower concentration) to the SOFC module (215) in addition to a product such as steam (H2O), thereby supporting steam reforming without requiring a separate water supply.

[0031] Accordingly, the fuel supply unit (225) must continuously supply an amount of fuel gas to the fuel gas inlet line (230) to facilitate the operation of the SOFC module (215). As illustrated, the fuel cell system (200) may include a plurality of controllable valve components (267 and 268) (e.g., solenoid valves, poppet valves, etc.) disposed within each of the air inlet line (227), the fuel gas inlet line (230), the depleted air stream (240), and the individual first and second depleted fuel gas streams (255 and 270). In various embodiments, the fuel cell system (200) may include a plurality of discharge flow lines (269), which are fluidly connected to the air inlet line (227), the fuel gas inlet line (230), and the second depleted fuel gas stream (270) to facilitate the release of pressure within them (e.g., during a shutdown event). As described, the exhaust stream (265) is CO2, NO x It may contain a plurality of gaseous by-products, including but not limited to N2 and H2O.

[0032] In various embodiments, the SOFC module (215) may comprise a single SOFC cell. In other embodiments, the SOFC module (215) may comprise a plurality of assembled fuel cells to form a fuel cell stack. In various embodiments, the SOFC module (215) and / or combined components within the fuel cell system (200) may be communicably coupled to one or more controllers to facilitate their operation.

[0033] As previously described, in order to advantageously produce an integrated final exhaust stream consisting mainly of CO2 and H2O, increase the overall system efficiency, and reduce the amount of fuel required from the fuel supply unit, the fuel cell system may include one or more components for processing depleted air and / or fuel gas to recirculate and facilitate carbon capture. FIG. 4 illustrates a schematic diagram of a fuel cell system (300) including an exhaust treatment module (375) according to an exemplary embodiment. In various embodiments, the elements (215 to 270) of the fuel cell system (200) are identical or equivalent to the corresponding elements (315 to 370) of the fuel cell system (300). Accordingly, the fuel cell system (300) further includes an exhaust treatment module (375) fluidly flowably coupled to both the second depleted fuel gas stream (370) and the fuel gas inlet manifold (335).

[0034] As illustrated in FIG. 4, the exhaust treatment module (375) is configured to receive depleted fuel gas from a depleted fuel gas stream (370) exhausted from the SOFC module (315) through a fuel gas outlet manifold (350) (e.g., anode exhaust). The depleted fuel gas received from the depleted fuel gas stream (370) is input into the SOEC module (395). In various embodiments, the exhaust treatment module (375) may be an SOEC module. The SOEC module (395) may include a plurality of branches connected in parallel electrically, each branch may include at least one solid oxide water electrolysis cell stack, and each solid oxide water electrolysis cell stack may include a plurality of solid oxide water electrolysis cells. In various embodiments, the SOEC module (395) may include an anode, an electrolyte layer, and a cathode, and the electrolyte layer serves to transfer ions between the anode and the cathode to facilitate a reaction that generates electrons to produce electricity.

[0035] In various embodiments, the SOEC module (395) may be positioned relative to the SOFC module (315) so that waste heat from the SOFC module (315) can be used by the SOEC module (395) to support its operation. The SOEC module (395) may receive a second portion (370) of depleted fuel (345), which will contain unreacted fuel remaining in addition to various gaseous byproducts from the SOFC module (315), such as but not limited to CO2 and H2O. The SOEC module (395) may rely on the received second portion (370) and undergo a co-electrolysis process facilitated by waste heat (e.g., electrolysis of both H2O and CO2), whereby the gaseous byproducts may react to form fuel and oxygen. Accordingly, the SOEC module (395) can output a fuel-enriched stream (385), which can eventually be recirculated through the SOFC module (315). Oxygen produced by the SOEC module (395) can be removed from the SOEC module (395) in the effluent stream (390) and supplied as an oxidizer to the afterburner (360) to facilitate the combustion of unreacted fuel remaining in the first portion (355) of the depleted fuel (345). As illustrated, implementing the effluent stream (390) from the SOEC module (395) as an oxidizer for the afterburner (360) can enable complete combustion of the fuel in the first portion (355) such that the final exhaust stream (365) from the afterburner consists almost exclusively of CO2 and H2O.

[0036] As illustrated in FIG. 4, the fuel cell system (300) may further include a water knockout unit (403) comprising a condenser (410) fluidly flowably coupled to the first and second manifolds (400 and 405), respectively. As illustrated, the water knockout unit (403) may be configured to receive a enrichment stream (385) output from the SOEC module (395). The enrichment stream (385) may be received by the first manifold (400), which divides the stream so that a portion of the first portion (413) is divided and circulated to the condenser (410), where excess water may be removed from the first portion (413) of the enrichment stream (385). This process can not only improve the composition of the final recirculation stream, but can also act as a cooling mechanism for a blower (337) configured to circulate fuel gas in the fuel inlet line (330) to the SOFC module (315). In various embodiments, the first portion (413) may contain less than 20% of the total gas in the enrichment stream (385). When excess water is removed from the first portion (413), it can be circulated to the second manifold (405) and recirculated to the fuel gas inlet manifold (335) as a recirculated stream (420). A second portion (415) of the enrichment stream (385), containing the remainder of the gas in the enrichment stream (385), is circulated directly to a second manifold (405), where the gas in the second portion (415) can be mixed with the dried first portion (413) when recirculated to the fuel gas inlet manifold (335) via a recirculation stream (420). In various embodiments, a water knockout unit (403) may be included in the fuel cell system (300) to prevent suppression of stack voltage through the supply of excess steam resulting from the implementation of the recirculation stream (420) combined with reduced inlet fuel flow (e.g., in the SOEC module (395)).Therefore, removing water from at least a portion of the enrichment stream (385) exiting the SOEC module (395) can facilitate maintaining the efficiency of the SOEC module (395) stack. Similar to a conventional system such as a fuel cell system (200), the recirculation stream (e.g., stream (370)) of the fuel cell system (300) can increase the fuel in the gas inlet line (330) and provide a product (e.g., steam, H2O) that can support the reforming of the incoming fuel (e.g., in the gas inlet line (330)) while providing the water (e.g., in the form of steam) necessary to support steam reforming. However, unlike a conventional system (e.g., fuel cell system (200)), the incoming fuel in the fuel gas inlet manifold (335) can be significantly reduced and thus require less steam (H2O) for reforming and protection against carbon deposition.

[0037] Because the fuel cell system (300) regenerates fuel within the SOEC module (395) to generate a richened recirculation stream (385) from a second portion (370) of depleted fuel (345) from the SOFC module (315), the fuel cell system (300) can reduce the net fuel supply (325) required to operate the fuel cell system (300) (e.g., compared to the fuel cell system (200)). Additionally, efficiency loss due to the operation of the SOEC module (375) can be compensated for by increased efficiency due to the use of waste heat in the inlet manifold (335) and improved gas composition (i.e., higher fuel content due to the enriched and dried recirculated stream (420)), the latter of which can enable lower relative parasitism within the fuel cell system (300) and / or a higher operating voltage of the SOFC module (315) (e.g., compared to that of the fuel cell system (200)).

[0038] In various embodiments, the SOEC module (395) may be configured as a separate module from the SOFC module (315) and may exchange heat through one or more gas streams. In another embodiment, the SOFC module (315) may include a plurality of stacks, each stack may include a plurality of cells, and some of the cells within each stack may be SOEC cells. In yet another embodiment, the SOFC module (315) and the SOEC module (395) may collectively form a plurality of stacks, wherein the SOEC module (395) is included within one of the plurality of stacks.

[0039] As illustrated in FIG. 4, the fuel cell system (300) may include a plurality of heat exchange components (427 and 428) disposed within each of the air inlet line (327), the fuel gas inlet line (330), the depleted air stream (340), and the individual first and second depleted fuel gas streams (355 and 370). In various embodiments, the fuel cell system (300) may include a plurality of thermal coupling paths (429) that can be thermally coupled to the air inlet line (327), the fuel gas inlet line (330), and the second depleted fuel gas stream (370) to facilitate thermal management and thermal protection within the system (300).

[0040] In various embodiments, the SOEC module (395) may be configured to contribute to the balance of the plant and / or load after the operation of the fuel cell system (300) by assisting in load absorption and / or power release. In various embodiments, the SOEC module (395) may be configured to facilitate the preservation of fuel cell system (300) components during shutdown events, as the electrolyzer system (such as the SOEC module (395)) can safely absorb a relatively large power input while rapidly switching the load on and off. Generally, solid oxide electrolyzers (such as the SOEC module (395)) tend to operate endothermally over a wide range of current densities. Therefore, the electrochemical efficiency of these systems may exceed 100% for most of their operating window, which may require external heat for the continued operation of the system. Consequently, the SOEC module (e.g., SOEC module (395)) can typically operate at a higher reaction rate than the equivalent SOFC module (e.g., SOFC module (315)) before reaching a thermal limit, which is determined by the maximum heat that can be extracted from the SOFC module (e.g., SOFC module (315)) during stable operation. Thus, the thermally limited electrolytic power rating of the SOEC module (e.g., SOEC module (395)) can be 5 times greater than that of the equivalent SOFC module (e.g., SOFC module (315)). Therefore, from the perspective of control and stability, it is generally easier to change the power level of the SOEC module (e.g., SOEC module (395)) faster than the power level of the equivalent SOFC module (e.g., SOFC module (315)).

[0041] For example, an electrolytic cell such as an SOEC module (395) operates thermally at approximately 0.25 W / cm 2Compared to a standard fuel cell such as an SOFC module (315) capable of producing approximately 1.3 W / cm² while operating near thermally neutral conditions 2 It can be configured to absorb more than (i.e., power per unit active area of ​​the cell within the SOEC module (395)). Thus, the integration of the SOEC (395) within the exhaust treatment module (375) enables the fuel cell system (300) to contribute to grid stabilization at a faster rate than a conventional system (e.g., fuel cell system (200)). In various embodiments, the SOFC module (315) may be operated according to time-averaged load conditions or requirements, whereas the SOEC module (395) may provide high-speed modulation above or below average conditions (e.g., + / - 10%).

[0042] In various embodiments, the SOEC module (395) may be configured to act as a source of reducing gas to protect the anode of the SOFC module (315). In various embodiments, the SOEC module (395) may be configured to introduce reducing gas during or immediately after a shutdown event or over a period of time during startup. In various embodiments, the SOEC module (395) may be configured to control the generation of reducing gas within the SOEC module (395) by monitoring the cell voltage within the SOFC module (315) to generate a voltage proportional to the fuel content (e.g., defined by the Nernst equation) when the SOFC module (315) is not generating power.

[0043] In various embodiments, the fuel cell system (300) may be operably coupled to one or more controllers, and the one or more controllers are configured to control the operation of the SOFC module (315), SOEC module (395), and / or other components included within the fuel cell system (300). Accordingly, in various embodiments, the fuel cell system (300) may be configured to monitor the composition of the fuel gas input within the SOFC module (315) (e.g., within the input fuel line (330)) and / or the SOEC module (395) (e.g., the depleted fuel stream portion (370)). In various embodiments, the fuel cell system (300) may be configured to monitor the composition of the fuel gas output from the SOFC module (315) and / or the SOEC module (395) (e.g., the enriched stream (385) and / or the recirculated stream (420)) (e.g., within the depleted fuel gas stream (345)). Accordingly, the controller may be configured to set and / or adjust one or more operating conditions of the fuel cell system (300) based on the monitored fuel gas composition within the system (300). In various embodiments, the fuel cell system (300) may be configured to implement the fuel gas composition according to a protocol, wherein, upon determination (e.g., by the controller) that the fuel gas composition does not satisfy one or more predetermined thresholds, the SOFC module (315) and / or SOEC module (395) may coordinate operations cooperatively or complementarily to restore the fuel gas composition to a satisfactory level (i.e., at the inlet and / or outlet within the system (300). In various embodiments, the fuel cell system (300) may be configured to adjust the amount of fuel gas provided by the fuel supply unit (325) based on the fuel gas determination (e.g., by the controller).

[0044] In various embodiments, the fuel cell system (300) may be configured to adjust the amount of fuel gas into the module and the amount of reforming on the stack within the SOFC module (315) during a transient event. In various embodiments, to cause the fuel cell system (300) to follow a load transition that would otherwise exceed the system response speed, the fuel cell system (300) may release some CO2 into the environment during this transient state. For example, if the fuel cell plant must undergo rapid unloading, a conventional system (such as the fuel cell system (200)) may expose the SOFC stack (e.g., within the SOFC module (215)) to significant endothermics because unreformed fuel gas may flow into the partially or completely unloaded stack before the fuel cell system has time to reduce the gas flow in the stack. In contrast, the fuel cell system (300) can be configured to rapidly increase demand in the SOEC module (395) to initiate a net plant unload process without unloading the SOFC module (315). Thus, as the fuel cell system (300) process control regulates the fuel gas supply (e.g., from the source (325)) to decrease (e.g., via a controller), the SOEC (395) can follow the SOFC module (315) unload profile while continuously adding hydrogen to the recirculation stream (420). This addition of hydrogen to the recirculation stream (420) can help keep the SOFC module (315) in a reduced state in the case of longer unload events, in addition to maintaining a fuel-rich environment when power demand for the fuel cell system (300) increases rapidly. In various embodiments, when power demand increases rapidly, the power of the SOEC module (395) may be reduced, and at the same time, the net power output of the fuel cell system (300) is increased and the loading speed of the SOFC module (315) is reduced.

[0045] Computational modeling data of the CO2 capture-capable fuel cell system (300) versus the conventional fuel cell system (200) demonstrated operational feasibility and showed improved performance due to the implementation of the SOEC module (395) and water knockout unit (303) within the exhaust treatment module (375). In summary, Table 1 below illustrates the relative performance parameters of the fuel cell system (300) compared to the conventional fuel cell system (200).

[0046] Table 1

[0047]

[0048] As can be seen from Table 1, the integration of the SOEC module (395) and the SOFC module enables a net increase in efficiency while increasing the exhaust CO2 concentration in the exhaust stream (365) from just 5% dryness to 100% dryness.

[0049] Additionally, for a given net power output of a fuel cell system (300) including both production by the SOFC module (315) and consumption by the SOEC module (395), the fuel cell system (300) may require a larger SOFC module (15) (i.e., 16% higher than the baseline amount to facilitate a higher contribution by the SOFC module (315)). In various embodiments, the SOEC module (395) may be configured to operate at a higher current compared to a conventional fuel cell system (e.g., fuel cell system (200)), which may reduce the net increase in the cell (or total cell active area) that must be included in the fuel cell system (300) to provide carbon capture capabilities (e.g., a total increase of 20 to 25%). In various embodiments, the fuel supply of the system (300) may be approximately 3-5% larger than that of a conventional system (e.g., fuel cell system (200)) despite a 14% larger SOFC module (315) contribution by the SOEC module (395) and a 20-25% increase in the cell.

[0050] Furthermore, despite the existence of competing approaches that enable carbon capture, fuel cell systems such as the fuel cell system (300) provide relatively superior operating characteristics. In summary, Table 2 below illustrates the operating parameters of the fuel cell system (300) compared to a baseline conventional system (e.g., fuel cell system (200)) and an alternative competing system for CO2 separation.

[0051] Table 2

[0052]

[0053] As can be seen from Table 2, data collected using computational modeling methods (i.e., HYSYS chemical process simulation) and supported by single-cell testing indicates that integrating the SOEC module (395) with the SOFC module (315) requires a higher system fuel utilization rate and a higher total power output by the SOFC module (315), along with a higher SOFC stack fuel utilization rate (within the SOFC module (315)). Additionally, the fuel cell system (300) can operate with higher efficiency and produce CO2 output with higher purity (i.e., within the exhaust stream (365)) with only a small amount of impurities. Furthermore, compared to the latest competing systems based on oxygen combustion, the fuel cell system (300) produces nearly pure CO2 output exhaust while requiring a moderate increase in other process equipment (e.g., air blower, fuel blower) and a moderate increase in cell count (e.g., +20%), which can be easily redirected for downstream use applications without additional processing. Competitive, state-of-the-art oxygen-combustion-based systems offer lower overall efficiency and lower purity depleted CO2, which limits commercial applicability while also providing reduced operational flexibility and higher capital costs. Additionally, while competing amine absorption CO2 capture technologies are relatively well understood, these technologies present challenges regarding high capital and operating costs. For example, the US DOE suggests that post-combustion carbon capture leads to an 80% increase in electricity costs and imposes an efficiency penalty of 20% to 30%. Refer to the page titled "Post-Combustion Carbon Capture Research," last accessed November 30, 2020, on the US Department of Energy website, available at https: / / www.energy.gov- / fe / science-innovation / carbon-capture-and-storage-research / carbon-capture-rd / post-combustion-carbon.No competing carbon capture approach provides a combination of high efficiency, relatively low capital cost, and high CO2 purity as a fuel cell system (300).

[0054] Notwithstanding the embodiments described above in FIGS. 1 to 4, various modifications and inclusions to these embodiments are considered and regarded within the scope of the present disclosure.

[0055] Furthermore, the configuration and arrangement of elements of systems and methods as illustrated in representative embodiments should be understood as merely illustrative. Although only a few embodiments of the present disclosure have been described in detail, those skilled in the art reviewing the present disclosure will readily recognize that many modifications (e.g., variations in the sizes, dimensions, structures, shapes, and proportions of various elements, values ​​of parameters, mounting arrangements, use of materials, colors, orientations, etc.) are possible without departing significantly from the novel teachings and advantages of the subject matter disclosed.

[0056] Accordingly, all such modifications are intended to be included within the scope of this disclosure. Any means-plus-function clause is intended to include structures and structural equivalents described herein as performing the cited function, as well as equivalent structures. Other alternatives, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of preferred and other exemplary embodiments without departing from the scope of this disclosure or the scope of the appended claims.

[0057] In addition, the functions and procedures described above may be performed by specialized equipment designed to execute specific functions and procedures. Functions may also be performed by general-purpose equipment that executes commands related to the functions and procedures, and each function and procedure may be performed by other equipment where one piece of equipment acts as the control unit, or by a separate control device.

[0058] The subject matter described herein illustrates different components that are sometimes included within or connected to other components. It should be understood that the architectures described are merely examples, and that many other architectures that achieve the same function may be implemented. In a conceptual sense, any arrangement of components to achieve the same function is effectively "associated" so that the desired function is achieved. Thus, any two components of this specification combined to achieve a specific function may be seen as "associated" with each other, regardless of the architecture or intermediate component, so that the desired function is achieved. Likewise, any two components so associated may also be seen as "operably connected" or "operably coupled" to each other to achieve the desired function, and any two components that may be so associated may also be seen as "operably coupled" to each other to achieve the desired function. Specific examples of operablely combinables include, but are not limited to, physically matable and / or physically interacting components and / or wirelessly interacting and / or wirelessly interacting components and / or logically interacting and / or logically interacting components.

[0059] With respect to the use of substantially any plural and / or singular terms in this invention, those skilled in the art may convert from plural to singular and / or from singular to plural as appropriate to the context and / or application. Various singular / plural substitutions may be explicitly described in this specification for clarity.

[0060] Those skilled in the art will understand that the terms used in this specification, and particularly in the appended claims (e.g., the text of the appended claims), are generally intended as "open" terms (e.g., the term "including" should be interpreted as "included but not limited thereto," the term "having" as "at least having," the term "includes" as "included but not limited thereto," etc.). Those skilled in the art will further understand that if a specific number of introduced claim citations are intended, such intent will be explicitly stated in the claim, and if there are no such citations, such intent does not exist. For example, for the sake of understanding, the following appended claims may include the use of introductory phrases "at least one" and "one or more" to introduce claim citations. However, the use of such wording, even where the same claim includes the introductory phrases “one or more” or “at least one” and the indefinite article, e.g., “a” or “an” (e.g., “a” and / or “an” should generally be interpreted to mean “at least one” or “one or more”), shall not be interpreted as limiting any specific claim containing such introduced claim citation to an invention containing only one such citation; the same applies to the use of the definite article used to introduce claim citations. Furthermore, even if specific numbers of introduced claims are explicitly enumerated, those skilled in the art will recognize that such references should typically be interpreted to mean at least the enumerated numbers (e.g., a citation of “two citations” without other modifiers, typically meaning at least two citations, or two or more citations).Similarly, unless otherwise specified, the phrase “based on” should not be interpreted in a restrictive manner and should therefore be understood as “at least partially based on”. Furthermore, where conventions similar to “at least one of A, B, and C, etc.” are used, such constructions are generally intended to mean that a person skilled in the art will understand the convention (e.g., “a system having at least one of A, B, and C” includes, but is not limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B, and C together, etc.). In such cases, where a convention similar to “at least one of A, B, or C, etc.” is used, such configuration is generally intended to mean that a person skilled in the art will understand the convention (e.g., “a system having at least one of A, B, or C” includes, but is not limited to, systems having A alone, B alone, C alone, A and B together, A and C together, B and C together, and / or A, B and C together, and C together, and / or A, B, and C together, etc.). A person skilled in the art will further understand that virtually any alternative word and / or phrase presenting two or more alternative terms, whether in the detailed description, claims, or drawings, should be understood as considering the possibility of including one, either, or both of the terms. For example, the phrase “A or B” will be understood as including the possibility of “A” or “B” or “A and B”. Additionally, unless otherwise noted, the use of words such as “approximate,” “about,” “roughly,” or “substantially” implies plus or minus 10 percent. Furthermore, while the drawings illustrate a specific sequence of method operations, the sequence of operations may differ from that illustrated. Additionally, two or more operations may be performed simultaneously or partially simultaneously.These variations will vary depending on the selected software and hardware systems and the designer's choice. All such variations are within the scope of this disclosure. Likewise, software embodiments may be achieved using standard programming techniques with rule-based logic and other logic to achieve various linking operations, processing operations, comparison operations, and decision operations.

Claims

Claim 1 A fuel cell system comprising a fuel cell module having an inlet and an outlet, wherein the fuel cell module is configured to receive a fuel stream containing gaseous fuel at the inlet and discharge a depleted fuel stream from the outlet; A fuel cell system comprising: a fuel cell module fluidly connected to the fuel cell module, wherein the fuel cell module comprises a solid oxide water electrolysis stack module comprising a plurality of solid oxide water electrolysis cells; wherein the fuel cell module is positioned relative to the fuel cell module such that waste heat from the fuel cell module can be utilized by the fuel cell module; wherein the fuel cell system is configured to direct a first portion of the depleted fuel stream to the fuel cell module, and the depleted fuel stream comprises at least one gaseous byproduct comprising depleted fuel and oxygen and carbon dioxide; wherein the fuel cell module is configured to use the waste heat from the fuel cell module to co-electrolyze the water and carbon dioxide of the first portion of the depleted fuel stream to produce a fuel-enriched stream comprising hydrogen and carbon monoxide; and wherein the fuel cell system is configured to direct the fuel-enriched stream to the inlet of the fuel cell module. Claim 2 A fuel cell system according to claim 1, further comprising a controller, wherein the controller is configured to operate the exhaust treatment module endothermally. Claim 3 A fuel cell system according to claim 1, wherein the fuel cell module comprises at least one solid oxide fuel cell. Claim 4 A fuel cell system according to any one of claims 1 to 3, wherein the exhaust treatment module comprises at least one solid oxide electrolysis cell stack. Claim 5 In paragraph 4, the exhaust treatment module is a fuel cell system included within the fuel cell module. Claim 6 In paragraph 5, the fuel cell module comprises a plurality of fuel cell stacks, forming a fuel cell system. Claim 7 In paragraph 4, the fuel cell system, wherein the exhaust treatment module is separate from the fuel cell module. Claim 8 A fuel cell system according to any one of claims 1 to 3, further comprising an afterburner that is in fluid communication with the fuel cell module and is disposed downstream of the outlet. Claim 9 A fuel cell system according to claim 8, wherein the afterburner is configured to receive a second portion of the degraded fuel stream and to produce a first exhaust stream by reacting unreacted fuel within the second portion. Claim 10 In claim 9, the exhaust treatment module is configured to discharge oxygen produced during the co-electrolysis of the first part into an outlet stream, and the fuel cell system is configured to direct the outlet stream to the afterburner, and the oxygen from the outlet stream facilitates the combustion of the unreacted fuel contained in the first part, the fuel cell system. Claim 11 A fuel cell system according to paragraph 2, wherein the controller is configured to operate the exhaust treatment module to provide reducing gas to the fuel cell module during a shutdown event of the fuel cell system. Claim 12 A method of operating a fuel cell system comprises: a discharge step in which a depleted fuel stream is discharged from an outlet by a fuel cell module, wherein the fuel cell module is configured to receive gaseous fuel at an inlet; a receiving step in which a first portion of the depleted fuel stream is received by an exhaust treatment module, wherein the first portion comprises depleted fuel and at least one gaseous byproduct comprising carbon dioxide and oxygen; a fuel-enriched stream comprising hydrogen and carbon monoxide from the first portion of the depleted fuel stream by co-electrolyzing water and carbon dioxide of the first portion using waste heat from the fuel cell module by the exhaust treatment module; and a step of directing the fuel-enriched stream produced by the exhaust treatment module to the fuel cell module by the fuel cell system; wherein the exhaust treatment module is a solid oxide water electrolysis stack module and comprises a plurality of solid oxide water electrolysis cells. Claim 13 A method according to claim 12, further comprising: receiving a second portion of the degraded fuel stream by means of an afterburner fluidly communicating with the fuel cell module; and producing a first exhaust stream by reacting unreacted fuel within the second portion by means of the afterburner. Claim 14 A method according to claim 12 or 13, further comprising the step of removing water from at least a portion of the fuel-enriching stream by means of a water knockout unit fluidly communicating with the exhaust treatment module. Claim 15 A method according to claim 12 or 13, further comprising the step of operating at least one of the fuel cell module or the exhaust treatment module based on the composition of the degraded fuel stream by a controller communicating with the fuel cell system. Claim 16 delete Claim 17 delete Claim 18 delete Claim 19 delete Claim 20 delete

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