Fuel cell system including anode tail gas oxidizer having catalyst ring

Abstract

To provide a fuel cell system anode tail gas oxidizer.SOLUTION: A fuel cell system anode tail gas oxidizer includes an ATO inner wall (514), an ATO outer wall (512), and a first catalyst ring (510) disposed in a chamber formed between the ATO inner wall (514) and the ATO outer wall (512). The first catalyst ring (510) includes an inner wall (514), an outer wall (512), and a matrix (515) disposed between the inner wall (514) and the outer wall (512) and loaded with an oxidation catalyst.SELECTED DRAWING: Figure 5D

Description

Technical Field

[0001] Aspects of the present invention relate to a fuel cell system, and more particularly to a fuel cell system comprising an anode tail gas oxidizer (ATO) having a catalyst ring.

Background Art

[0002] Fuel cells, such as solid oxide fuel cells, are electrochemical devices capable of efficiently converting the energy stored in a fuel into electrical energy. 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, which also enable reverse operation so that by using electrical energy as an input, oxidized fuel can be re-reduced to unoxidized fuel.

Summary of the Invention

[0003] According to various embodiments, there is provided an anode tail gas oxidizer (ATO) of a fuel cell system, comprising an ATO inner wall, an ATO outer wall, and a first catalyst ring disposed in a chamber formed between the ATO inner wall and the ATO outer wall, the first catalyst ring comprising an inner wall, an outer wall, and a matrix disposed between the inner wall and the outer wall and filled with an oxidation catalyst.

[0004] Exemplary embodiments of the present invention are shown by the accompanying drawings which are incorporated herein and form a part of this specification. The accompanying drawings, together with the above general description and the following detailed description, serve to explain the features of the present invention.

Brief Description of the Drawings

[0005] [Figure 1] FIG. 1 is a schematic diagram of a fuel cell system according to various embodiments of the present disclosure. [Figure 2AB]Figure 2A is a cross-sectional view showing the components of the hotbox of the system of Figure 1 according to various embodiments of the present disclosure, and Figure 2B is a diagram showing an enlarged portion of the system of Figure 2A according to various embodiments of the present disclosure. [Figure 2C] Figure 2C is a three-dimensional cutaway view of the central column of the system shown in Figure 2A, according to various embodiments of the present disclosure. [Figure 2D] Figure 2D is a perspective view of an anode hub structure located below the central column of the system in Figure 2A, according to various embodiments of the present disclosure. [Figure 3A] Figure 3A is a cross-sectional view showing the fuel and airflow through the central column of the system in Figure 2A according to various embodiments of the present disclosure. [Figure 3B] Figure 3B is a cross-sectional view showing the fuel and airflow through the central column of the system of Figure 2A according to various embodiments of the present disclosure. [Figure 3C] Figure 3C is a cross-sectional view showing the fuel and airflow through the central column of the system in Figure 2A according to various embodiments of the present disclosure. [Figure 4] Figure 4 is a partial perspective view of the central column of the system in Figure 2A according to various embodiments of the present disclosure. [Figure 5A] Figure 5A is a photograph showing an exemplary central column 400 with the outer cylinder of the ATO removed. [Figure 5B] Figure 5B is a photograph showing a top perspective view of the ATO catalyst ring. [Figure 5C] Figure 5C is a photograph showing an enlarged view of the upper surface of a portion of a catalyst ring according to various embodiments of this disclosure. [Figure 5D] Figure 5D is a top view relating to alternative catalyst rings according to various embodiments of the present disclosure. [Figure 6] Figure 6 is a perspective view of a modified ATO according to various embodiments of this disclosure. [Modes for carrying out the invention]

[0006] Various embodiments will be described in detail with reference to the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. References to specific examples and embodiments are for illustrative purposes only and are not intended to limit the scope of the invention or the claims.

[0007] In solid oxide fuel cell (SOFC) systems, the fuel inlet flow can be humidified to promote fuel reforming reactions such as steam reforming and water-gas shift reactions. In addition, water can be added to the fuel inlet flow to prevent coking of system components such as catalysts during system startup, shutdown, and power grid interruption events. Conventionally, such humidification is performed by evaporating water within a steam generator containing corrugated tubing. The water flows through the corrugated tubing and is heated by the exhaust flow of the cathode reconverter flowing around the outside of the tubing. However, utilizing the relatively low-temperature exhaust flow of the cathode reconverter usually requires a considerable length of corrugated tubing to absorb enough heat to evaporate the water. Furthermore, steam generators are relatively large and bulky, which increases the size, complexity, and manufacturing cost of the system.

[0008] In contrast, embodiments of the present disclosure provide a water injector configured to directly inject water into the anode exhaust recirculation flow, thereby heating and evaporating the water into steam, and / or aerosolizing the water into droplets small enough to be carried along with the anode exhaust flow. The anode exhaust recirculation flow is recirculated into a fuel inlet flow supplied to the fuel cell stack, so that humidified fuel is supplied to the fuel cells of the fuel cell stack. Thus, a conventional steam generator can be omitted to reduce the size, complexity, and cost of the system. In addition, the system of the embodiment can operate using relatively short, uncorrugated water conduits, thereby improving the system response time and reducing the system size and cost.

[0009] Figure 1 is a schematic diagram of SOFC system 10 according to various embodiments of the present disclosure. Referring to Figure 1, system 10 comprises a hot box 100 and various components arranged inside or adjacent to it. The hot box 100 may include a fuel cell stack 102, such as a solid oxide fuel cell stack, which alternately includes fuel cells and interconnects. One solid oxide fuel cell in the stack 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 interconnects may be metal alloy interconnects such as chromium-iron alloy interconnects. The stacks 102 can be arranged stacked on top of each other in a plurality of columns.

[0010] The hot box 100 may also include an anode reconstitution heat exchanger 110, a cathode reconstitution heat exchanger 120, an anode tail gas oxidizer (ATO) 500, an anode exhaust cooling heat exchanger 140, a splitter 550, a vortex generator 552, and a water injector 160. The system 10 may also include a catalytic partial oxidation (CPOx) reactor 200, a mixer 210, a CPOx blower 204 (e.g., an air blower), a system blower 208 (e.g., an air blower), and an anode recirculation blower 212, which may be located outside the hot box 100. However, this disclosure does not limit each of the components to a specific location relative to the hot box 100.

[0011] The CPOx reactor 200 receives the fuel inlet flow from the fuel inlet 300 through the fuel conduit 300A. The fuel inlet 300 can be a fuel tank or utility natural gas line equipped with a valve to control the amount of fuel supplied to the CPOx reactor 200. A CPOx blower 204 can supply air to the CPOx reactor 200 at system startup. Fuel and / or air can be supplied to the mixer 210 by the fuel conduit 300B. The fuel (e.g., the fuel inlet flow 1721 described later with respect to Figures 4A-4C) flows from the mixer 210 through the fuel conduit 300C to the anode reconverter 110. The fuel is heated in the anode reconverter 110 by a portion of the fuel exhaust, and then the fuel flows from the anode reconverter 110 through the fuel conduit 300D to the stack 102.

[0012] The system blower 208 can be configured to supply an airflow (e.g., an air inlet flow) to the anode exhaust cooler 140 through the air conduit 302A. Air flows from the anode exhaust cooler 140 through the air conduit 302B to the cathode regenerator 120. The air is heated by the ATO exhaust within the cathode regenerator 120. Air flows from the cathode regenerator 120 through the air conduit 302C to the stack 102.

[0013] The anode exhaust flow generated within the stack 102 (for example, the fuel exhaust flow described later with respect to Figures 3A and 3C) is supplied to the anode reconverter 110 through the anode exhaust conduit 308A. The anode exhaust may contain unreacted fuel and may be referred to as fuel exhaust in this specification. The anode exhaust can be supplied from the anode reconverter 110 to the splitter 550 through the anode exhaust conduit 308B. A first portion of the anode exhaust can be supplied from the splitter 550 to the anode exhaust cooler 140 through the water injector 160 and the anode exhaust conduit 308C. A second portion of the anode exhaust is supplied from the splitter 550 to the ATO 500 through the anode exhaust conduit 308D. The first portion of the anode exhaust heats the air inlet flow in the anode exhaust cooler 140 and can then be supplied from the anode exhaust cooler 140 to the mixer 210 through the anode exhaust conduit 308E. The anode recirculation blower 212 can be configured to move the anode exhaust through the anode exhaust conduit 308E, as will be described later.

[0014] The cathode exhaust generated within the stack 102 flows through the exhaust conduit 304A to the ATO 500. A vortex generator 552 can be positioned within the exhaust conduit 304A and configured to swirl the cathode exhaust. The anode exhaust conduit 308D can be fluidly connected to the vortex generator 552, or to the cathode exhaust conduit 304A or ATO 500 downstream of the vortex generator 552. The swirled cathode exhaust can be mixed with a second portion of the anode exhaust supplied by the splitter 550 before being supplied to the ATO 500. This mixture can be oxidized within the ATO 500 to generate ATO exhaust. The ATO exhaust flows from the ATO 500 through the exhaust conduit 304B to the cathode reconverter 120. The exhaust flows out of the hot box 100 through the exhaust conduit 304C from the cathode reconverter.

[0015] Water flows from a water source 206, such as a water tank or water supply pipe, through a water conduit 306 to a water injector 160. The water injector 160 directly injects water into a first portion of the anode exhaust supplied into conduit 308C. The heat from the first portion of the anode exhaust (also called the recirculated anode exhaust flow) supplied into exhaust conduit 308C causes the water to evaporate and produce steam. The steam mixes with the anode exhaust, and the resulting mixture is supplied to the anode exhaust cooler 140. This mixture is then supplied from the anode exhaust cooler 140 through the anode exhaust conduit 308E to a mixer 210. The mixer 210 is configured to mix the steam and the first portion of the anode exhaust with fresh fuel (i.e., fuel inlet flow). This humidified fuel mixture can then be heated in the anode refractor 110 by the anode exhaust before being supplied to the stack 102. System 10 may also include one or more fuel reforming catalysts 112, 114, and 116 located inside and / or downstream of the anode reconverter 110. The reforming catalyst(s) reform the humidified fuel mixture before it is supplied to the stack 102.

[0016] System 10 may further comprise a system controller 225 configured to control various elements of System 10. The controller 225 may comprise a central processing unit configured to execute stored instructions. For example, the controller 225 may be configured to control the fuel and / or airflow through System 10 according to fuel composition data.

[0017] Figure 2A is a cross-sectional view showing the components of the hotbox 100 of system 10 in Figure 1, and Figure 2B shows an enlarged portion of Figure 2A. Figure 2C is a three-dimensional cutaway view of the central column 400 of system 10 according to various embodiments of the present disclosure, and Figure 2D is a perspective view of the anode hub structure 600 located within the hotbox base 101 in which the column 400 can be placed.

[0018] Referring to FIGS. 2A to 2D, the fuel cell stack 102 can be arranged around the central column 400 within the hot box 100. For example, the stack 102 can be arranged in a ring configuration around the central column 400 and positioned on the hot box base 101. The column 400 can include an anode reheater 110, an ATO 500, and an anode exhaust cooler 140. In particular, the anode reheater 110 is arranged radially inside the ATO 500, and the anode exhaust cooler 140 is mounted above the anode reheater 110 and the ATO 500. In one embodiment, an oxidation catalyst 112 and / or a hydrogenation catalyst 114 can be located within the anode reheater 110. A reforming catalyst 116 can also be located at the bottom of the anode reheater 110 as a steam methane reforming (SMR) insert.

[0019] The ATO 500 includes an outer cylinder 502 positioned around the outer wall of the ATO inner insulation 556 / anode reheater 110. Optionally, the insulation 556 can be surrounded by an ATO inner cylinder 504. Thus, the insulation 556 can be located between the anode reheater 110 and the ATO 500. An ATO oxidation catalyst can be located within the space between the outer cylinder 502 and the ATO insulation 556. A fuel inlet path bellows 854 can be located between the anode exhaust cooler 140 and the ATO inner cylinder 504. An ATO thermocouple feedthrough 1601 extends through the anode exhaust cooler 140 to the top of the ATO 500. Thereby, the temperature of the ATO 500 can be monitored by inserting one or more thermocouples (not shown) through this feedthrough 1601.

[0020] The anode hub structure 600 can be positioned below the anode reheater 110 and the ATO 500 and above the hot box base 101. The anode hub structure 600 is covered by the ATO skirt 1603. The vortex generator 552 and the fuel exhaust splitter 550 are located above the anode reheater 110 and the ATO 500 and below the anode exhaust cooler 140. The ATO glow plug 1602, which initiates the oxidation of the stack fuel exhaust during ATO startup, can be positioned near the bottom of the ATO 500.

[0021] The anode hub structure 600 is used to uniformly distribute fuel from the central column to the fuel cell stack 102 disposed around the central column 400. The anode flow hub structure 600 includes a grooved cast base 602 and a "spider" hub formed by the fuel inlet conduit 300D and the fuel outlet conduit 308A. Each pair of conduits 300D, 308A is connected to the fuel cell stack 102. Also, the anode-side cylinders (e.g., the inner and outer cylinders of the anode reheater 110 and the ATO outer cylinder 502) are welded or brazed into the grooves of the base 602, providing a uniform volumetric cross-section for the flow distribution described later.

[0022] As shown in FIG. 2C, a lift 1604 is positioned below the hot box base 101. In one embodiment, the lift 1604 includes two hollow arms, and for example, to remove the system from a cabinet (not shown) for repair or maintenance, the forks of a forklift can be inserted into the two hollow arms to lift and move the system.

[0023] As indicated by the arrows in Figures 2A and 2B, air enters from the top of the hot box 100 and then flows into the cathode regenerator 120, where it is heated by the ATO exhaust (not shown) from the ATO 500. The heated air then flows through the cathode regenerator 120 through the first vent or opening 121. The air then flows through the stack 102 and reacts with the fuel supplied from the anode hub structure 600 (i.e., the fuel inlet flow). The exhaust air flows from the stack 102 through the second vent or opening 123. The exhaust air then passes through the blades of the vortex generator 552 and is swirled before entering the ATO 500.

[0024] The splitter 550 can direct a second portion of the fuel exhaust exiting the top of the anode reconverter 110 through an opening (e.g., a slit) in the splitter to a swirling air exhaust (e.g., into the vortex generator 552, or into the conduit 304A downstream of the vortex generator, or into the ATO 500). Thus, the fuel and air exhaust can be mixed before entering the ATO 500.

[0025] Figures 3A and 3B are side cross-sectional views showing the flow distribution through the central column 400, and Figure 3C is a top cross-sectional view through the anode reconverter 110. Referring to Figures 2A, 2B, 3A, and 3C, the anode reconverter 110 comprises an inner cylinder 110A, a corrugated plate 110B, and an outer cylinder 110C which can be covered by ATO insulation material 556. Fuel from the fuel conduit 300C enters from the top of the central column 400. The fuel then bypasses the anode exhaust cooler 140 by flowing through the hollow core of the anode exhaust cooler 140, and then flows between the outer cylinder 110C and the corrugated plate 110B of the anode reconverter 110. The fuel then flows to the stack 102 through the hub base 602 and conduit 300D of the anode hub structure 600 shown in Figure 3B.

[0026] Referring to Figures 2A, 2B, 2C, 3A, and 3B, the fuel exhaust flows from the stack 102 through conduit 308A to the hub base 602, from the hub base 602 through the anode reheater 110 between the inner cylinder 110A and the corrugated plate 110B, and through conduit 308B into the splitter 550. As shown in Figure 1, the first portion of the fuel exhaust flows from the splitter 550 through conduit 308C to the anode exhaust cooler 140, while the second portion flows from the splitter 550 through conduit 308D to the ATO 500. The anode exhaust cooler inner core insulation 140A can be located between the fuel conduit 300C and the bellows 852 / support cylinder 852A, which is located between the anode exhaust cooler 140 and the vortex generator 552, as shown in Figure 3A. This insulation minimizes heat transfer and heat loss from the first portion of the anode exhaust flow in the conduit 308C on its way to the anode exhaust cooler 140. The insulation 140A may also be located between the conduit 300C and the anode exhaust cooler 140 to avoid heat transfer between the fuel inlet flow in the conduit 300C and the flow in the anode exhaust cooler 140. In other embodiments, the insulation 140A can be omitted from within the cylindrical anode exhaust cooler 140.

[0027] Figure 3B also shows that air flows from the air conduit 302A to the anode exhaust cooler 140 (where the air is heated by the first portion of the anode exhaust), and then from the anode exhaust cooler 140 through conduit 302B to the cathode reheater 120. The first portion of the anode exhaust is cooled in the anode exhaust cooler 140 by the air flowing through the anode exhaust cooler 140. The cooled first portion of the anode exhaust is then supplied from the anode exhaust cooler 140 to the anode recirculation blower 212 shown in Figure 1.

[0028] As described in more detail below and as shown in Figures 2A and 3B, the anode exhaust exits the anode reconverter 110 and is supplied into the splitter 550 through conduit 308B. The splitter 550 divides the anode exhaust into a first and second part (i.e., flow). The first flow is supplied into the anode exhaust cooler 140 through conduit 308C. The second flow is supplied to the ATO 500 through conduit 308D.

[0029] The relative amount of anode exhaust supplied to ATO500 and anode exhaust cooler 140 is controlled by anode recirculation blower 212. The faster the blower 212 is, the more anode exhaust is supplied into conduit 308C and the less anode exhaust is supplied to ATO500 via conduit 308D, and vice versa.

[0030] The anode exhaust supplied to the ATO 500 is not cooled within the anode exhaust cooler 140. This results in a higher temperature anode exhaust being supplied to the ATO 500 compared to when the anode exhaust flows through the anode exhaust cooler 140 before being supplied. For example, the anode exhaust supplied from the splitter 550 into the ATO 500 can have a temperature exceeding 350°C, for example, approximately 350°C to 500°C, for example, approximately 375°C to 425°C, or approximately 390°C to 410°C. Furthermore, since a smaller amount of anode exhaust is supplied into the anode exhaust cooler 140 (for example, the anode exhaust is split in the splitter 550, so that 100% of the anode exhaust is not supplied into the anode exhaust cooler), the heat exchange area of ​​the anode exhaust cooler 140 can be reduced. The anode exhaust supplied to ATO500 is oxidized by stack cathode (i.e., air) exhaust and can be supplied to the cathode reconverter 120 through conduit 304B.

[0031] Figure 4 is a cross-sectional perspective view showing the water injector 160 and ATO 500 in the central column of Figure 2A. Referring to Figure 4, the splitter 550 has a horizontal slit as shown in Figure 3A. However, in other embodiments, the splitter 550 may have a tube penetrating the outer wall of the anode exhaust conduit 308B instead of a slit.

[0032] The water injector 160 may comprise an injector ring 162 and a shroud 166. The injector ring 162 may be located within the anode exhaust conduit 308C between the anode exhaust cooler 140 and the anode reconverter 110 and may be fluidly connected to the water conduit 306. The injector ring 162 is a tube extending around the fuel conduit 300C. The injector ring 162 may have an injection hole (i.e., an opening) 162A configured to directly inject water into a first portion of the anode exhaust flowing from the splitter 550 and the anode reconverter 110 into the conduit 308C. The water may be evaporated by the high-temperature first portion of the anode exhaust. The injection hole 162A may be configured to generate a stream or droplets of water that can evaporate instantaneously or within seconds of emerging from the injector ring 162. The injector ring 162 can be sized to provide a substantially uniform circumferential flow of water internally while minimizing pressure drop in the anode exhaust flowing to the side.

[0033] The shroud 166 can be a cylinder surrounding the injector ring 162. The shroud 166 can be configured to separate water from a second portion of the anode exhaust that flows into the ATO 500 through the splitter 550. In particular, the second portion of the anode exhaust flowing outside the shroud 166 can be directed radially outward by the splitter 550 towards the anode exhaust conduit 308D and the ATO 500, while the first portion of the anode exhaust flowing inside the shroud 166 can be directed upward by the splitter 550 towards the injector ring 162 in the anode exhaust conduit 308C. Thus, the shroud 166 can be configured to prevent or reduce the amount of water and / or the amount of the first portion of the anode exhaust humidified by the injected water being injected into the ATO 500 by the splitter 550. In other words, the shroud 166 is configured so that substantially all of the water and the humidified first portion of the anode exhaust are directed towards the anode exhaust cooler 140.

[0034] The ATO500 can surround the anode reconverter 110, and the catalysts 112, 114, and 116 can be located within the inner plenum surrounded by the anode reconverter 110. This is similar to the configuration described in U.S. Patent No. 9,287,572 issued March 15, 2016, which is incorporated herein by reference in its entirety.

[0035] The ATO500 may include a catalytic ring 510 positioned within an annular chamber formed between an outer cylinder 502 and an inner cylinder 504. In particular, the catalytic ring 510 may be positioned at a distance from the splitter 550 such that a large portion of the oxidation of the fuel exhaust occurs before the exhaust enters the catalytic ring 510. In other words, the distance may be set so that the non-catalytic oxidation of the exhaust, e.g., oxidation of hydrogen to form water and / or oxidation of carbon monoxide to form carbon dioxide, is completed or more than 50% completed before the exhaust enters the catalytic ring 510.

[0036] The catalyst ring 510 can be configured to catalyze the oxidation of oxidizing species remaining in the catalytic exhaust after non-catalytic oxidation. For example, the catalyst ring 510 may include a catalyst or a mixture of catalysts configured to catalyze the oxidation of carbon monoxide and / or fuel (e.g., hydrogen, or hydrocarbon fuels such as natural gas or methane) remaining in the exhaust.

[0037] Figure 5A is a photograph showing an exemplary central column 400 with the outer cylinder 502 of the ATO 500 removed, according to various embodiments of the present disclosure; Figure 5B is a photograph showing a top perspective view of the catalyst ring 510 of the ATO 500; and Figure 5C is a photograph showing an enlarged view of a portion of the top surface of the catalyst ring 510.

[0038] Referring to Figures 5A to 5C, the catalyst ring 510 may comprise an outer wall 512, an inner wall 514, and a matrix 515 positioned between the outer wall 512 and the inner wall 514. In some embodiments, the catalyst ring 510 may be formed from a high-temperature stable material such as metal, for example, stainless steel or Inconel (i.e., a high-temperature nickel alloy), or a ceramic material such as alumina. For example, the outer wall 512 may be metal, and the matrix 515 may be ceramic coated with a catalyst metal. In some embodiments, the outer wall 512 and the inner wall 514 may be cylindrical when viewed from above. However, other ring shapes, such as rectangular or hexagonal ring shapes, may be used instead. The outer wall 512 may concentrically surround the inner wall 514. The inner wall 514 may be attached to the inner cylinder 504 of the ATO 500. The matrix 515 is attached to the inner wall 514 and the outer wall 512 by brazing or another preferred method.

[0039] The matrix 515 may have a honeycomb structure including channels 516. The channels 516 can have any shape, as long as they are configured to allow fluid to flow through the catalyst ring 510 from the top surface of the catalyst ring 510 to the opposite bottom surface. For example, the channels 516 may be straight or curved. In some embodiments, the channels 516 may extend in a direction substantially perpendicular to the plane of the top and / or bottom surfaces of the catalyst ring 510.

[0040] In some embodiments, the channels 516 can be arranged in a concentric ring shape surrounding the inner wall 514. For example, at least three channels 516 can be arranged in a concentric ring shape, e.g., at least five, at least ten, or at least fifteen. In other embodiments, the channels 516 can be arranged in an irregular configuration. For example, the channels 516 can have any configuration as long as at least three channels 516 can be arranged in a radial (i.e., horizontal) direction A (see Figure 5C) extending between the outer wall 512 and the inner wall 514. Radial direction A can be perpendicular to the axial direction (i.e., vertical direction) of the fluid (i.e., fuel and air exhaust) flow through the catalyst ring 510.

[0041] In one embodiment shown in Figure 5C, the matrix 515 can be formed from concentric cylindrical walls 517 (e.g., three or more concentric walls 517) separated from each other by cylindrical and corrugated spacers 518. In some embodiments, the cylindrical walls 517, spacers 518, and / or the outer wall 512 and inner wall 514 can be attached to each other, for example, by brazing or welding. The channel 516 may have a trapezoidal horizontal cross-sectional shape, where, viewed from above, the parallel short and long sides of the trapezoid alternate in the angular direction (i.e., clockwise or counterclockwise).

[0042] In the alternative embodiment shown in Figure 5D, the cylindrical walls 517 can be omitted from the matrix 515. In this embodiment, the corrugated spacers 518 are attached to each other rather than to pairs of adjacent cylindrical walls 517. In this embodiment, the channels 516 may have a hexagonal horizontal cross-sectional shape when viewed from above. The channels 516 form a close-packed hexagonal arrangement when viewed from above.

[0043] Matrix 515 can be loaded with an oxidation catalyst (i.e., the surface of the channels can be coated). In particular, the honeycomb structure of Matrix 515 can provide a large surface area for loading the catalyst. A suitable oxidation catalyst can be configured to catalyze the oxidation of carbon monoxide to carbon dioxide and / or to oxidize fuel remaining in the exhaust. For example, a suitable oxidation catalyst can include catalytic metals such as platinum (Pt), palladium (Pd), rhodium (Rh), iridium (Ir), osmium (Os), ruthenium (Ru), tantalum (Ta), nickel (Ni), copper (Cu), their oxides, their alloys, and combinations thereof. In some embodiments, the oxidation catalyst can include palladium. The oxidation catalyst can be applied to Matrix 515 using any suitable process, for example, by a wash-coat process.

[0044] Figure 6 is a schematic diagram of alternative ATO500A according to various embodiments of this disclosure. The ATO500A may be similar to the ATO500. Therefore, only the differences from the ATO500 will be described in detail.

[0045] Referring to Figure 6, the ATO500A may have two or more catalyst rings 510. For example, as shown in Figure 6, the ATO500A may have three catalyst rings 510, where the first ring is positioned above the second ring, and the second ring is positioned above the third ring. However, this disclosure is not limited to a specific number of catalyst rings 510. For example, the number of catalyst rings 510 may be selected based on the composition of the exhaust gas configured to be received by the ATO500A.

[0046] The catalyst rings 510 can be positioned between the outer cylinder 502 and the inner cylinder 504 so that exhaust gases flowing through the ATO 500A pass through each catalyst ring 510 (for example, between the outer cylinder 502 and the inner cylinder 504). In some embodiments, the catalyst rings 510 can be positioned at the bottom of the ATO 500A so that the non-catalytic oxidation of the exhaust gases can be substantially completed before the exhaust gases enter the catalyst rings 510. The catalyst rings 510 can be spaced apart from each other in the axial direction (i.e., vertical direction), or they can be in direct contact with each other, as shown in Figure 6. For example, the catalyst rings 510 can be spaced apart from each other by a distance ranging from 0 cm to about 10 cm, for example, 0.5 cm to 5 cm, or 1 cm to 2 cm, in the exhaust gas flow direction indicated by the exhaust gas flow arrows in Figure 6.

[0047] In some embodiments, the catalyst ring 510 may be filled with the same oxidation catalyst and / or have the same catalyst filling amount. In other embodiments, the catalyst ring 510 may contain different catalysts and / or have different catalyst filling amounts.

[0048] The inventors have found that an ATO (Automated Catalyst Oven) equipped with the catalyst ring described herein can offer a variety of unexpected benefits compared to conventional ATO designs. For example, the catalyst ring can increase the surface area for catalyst packing, thereby increasing the active area for oxidation compared to conventional designs. In addition, the catalyst ring can have a longer service life and can be manufactured at a lower cost compared to conventional designs.

[0049] The above-described embodiments of the disclosure are provided to enable those skilled in the art to practice 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 can be applied to other embodiments without departing from the scope of the invention. Accordingly, the present invention is not intended to be limited to the embodiments shown herein, but rather to be given the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. 1. An anode tail gas oxidizer (ATO), comprising: an ATO inner wall, an ATO outer wall, and a first catalyst ring disposed in a chamber formed between the ATO inner wall and the ATO outer wall; The first catalyst ring comprises: an inner wall in contact with the ATO inner wall; An outer wall in contact with the ATO outer wall; a matrix extending from the inner wall to the outer wall and including channels extending from a top surface to an opposite bottom surface of the first catalyst ring, the channels being filled with an oxidation catalyst; an anode tail gas oxidizer comprising:

2. The anode tail gas oxidizer configured to flow a fluid axially through the chamber; The anode tail gas oxidizer of claim 1 , wherein the channels extend longitudinally along the axial direction.

3. 10. The anode tail gas oxidizer of claim 1, wherein the matrix comprises concentric cylindrical walls and cylindrical, corrugated spacers disposed between the cylindrical walls.

4. The anode tail gas oxidizer of claim 3 , wherein the cylindrical wall and the spacer are brazed to each other to form the matrix.

5. 4. The anode tail gas oxidizer of claim 3, wherein the matrix comprises at least three concentric cylindrical walls separated by cylindrical and corrugated spacers.

6. The anode tail gas oxidizer of claim 3 , wherein the channel is at least partially defined by the cylindrical wall and the spacer.

7. 7. The anode tail gas oxidizer of claim 6, wherein the channels have a trapezoidal horizontal cross-sectional shape with parallel short and long sides of the trapezoid alternating angularly.

8. The anode tail gas oxidizer of claim 1 , wherein the channel has a hexagonal horizontal cross-sectional shape.

9. 2. The anode tail gas oxidizer of claim 1, wherein the matrix comprises at least 10 of the channels in a radial direction perpendicular to an axial direction of fluid flow through the first catalyst ring.

10. The anode tail gas oxidizer of claim 1 , wherein the matrix comprises alumina.

11. An anode tail gas oxidizer (ATO), comprising: an ATO inner wall, an ATO outer wall, and a first catalyst ring disposed in a chamber formed between the ATO inner wall and the ATO outer wall; the first catalyst ring comprises an inner wall, an outer wall, and a matrix disposed between the inner wall and the outer wall and filled with an oxidation catalyst; a second catalyst ring positioned within the chamber below the first catalyst ring; The second catalyst ring comprises an inner wall, an outer wall, and a matrix disposed between the inner wall and the outer wall and loaded with an oxidation catalyst.

12. 12. The anode tail gas oxidizer of claim 11, wherein the first catalyst ring and the second catalyst ring are in direct contact with each other or spaced apart within the chamber.

13. 12. The anode tail gas oxidizer of claim 11, further comprising a third catalyst ring disposed within the chamber below the second catalyst ring, the third catalyst ring comprising an inner wall, an outer wall, and a matrix disposed between the inner wall and the outer wall and filled with an oxidation catalyst.

14. 10. A fuel cell system comprising: a fuel cell stack; a central column; and the anode tail gas oxidizer of claim 1 located between the fuel cell stack and the central column.

15. the anode tail gas oxidizer is cylindrical and surrounds the central column; 15. The fuel cell system of claim 14, wherein the fuel cell stack surrounds the anode tail gas oxidizer.

16. The central column is an anode recuperator configured to utilize anode exhaust from the fuel cell stack to heat fuel supplied to the fuel cell stack; an anode exhaust cooler configured to utilize the anode exhaust from the anode recuperator to heat air supplied to the fuel cell stack; 16. The fuel cell system of claim 15, comprising:

17. 17. The fuel cell system of claim 16, further comprising a splitter configured to supply a first portion of the anode exhaust gas from the anode recuperator to the anode tail gas oxidizer and to supply a second portion of the anode exhaust gas from the anode recuperator to the anode exhaust cooler.

18. 20. The fuel cell system of claim 17, further comprising a vortex generator including vanes located above the splitter and configured to swirl and add cathode exhaust from the fuel cell stack to the first portion of the anode exhaust flowing from the splitter through the chamber and to the first catalyst ring.

19. 18. The fuel cell system of claim 17, wherein the anode tail gas oxidizer surrounds the anode recuperator.

20. the cathode exhaust oxidizes a majority of the first portion of the anode exhaust in the chamber before the anode exhaust enters the first catalyst ring; 20. The fuel cell system of claim 17, wherein the first catalytic ring is configured to oxidize a remaining portion of the first portion of the anode exhaust.

21. A fuel cell system comprising: a fuel cell stack; a central column including an anode recuperator configured to use anode exhaust from the fuel cell stack to heat fuel supplied to the fuel cell stack, and an anode exhaust cooler configured to use the anode exhaust from the anode recuperator to heat air supplied to the fuel cell stack; an anode tail gas oxidizer (ATO) located between the fuel cell stack and the central column; a splitter configured to supply a first portion of the anode exhaust gas from the anode recuperator to the anode tail gas oxidizer and to supply a second portion of the anode exhaust gas from the anode recuperator to the anode exhaust cooler; a vortex generator including vanes positioned above the splitter; Equipped with the anode tail gas oxidizer comprises an ATO inner wall, an ATO outer wall, and a first catalyst ring disposed in a chamber formed between the ATO inner wall and the ATO outer wall; the first catalyst ring comprises an inner wall, an outer wall, and a matrix disposed between the inner wall and the outer wall and filled with an oxidation catalyst; the vortex generator is configured to swirl and add cathode exhaust from the fuel cell stack to the first portion of the anode exhaust flowing from the splitter through the chamber to the first catalyst ring. Fuel cell system.

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