Solid oxide fuel cell system and method for operating same

Abstract

The invention relates to a solid oxide fuel cell system and an operation method thereof. The solid oxide fuel cell system comprises a supporting piece, a working medium auxiliary processing module and a plurality of electric pile units. The working medium auxiliary processing module is arranged on the supporting piece; the multiple electric pile units surround the peripheral side of the working medium auxiliary processing module, each electric pile unit comprises at least two electric piles, and each electric pile unit is connected with the supporting piece through a corresponding fastening mechanism. The galvanic pile unit is arranged on the periphery of the working medium auxiliary processing module, and galvanic piles are convenient to replace. And each electric pile unit is connected with the supporting piece through the corresponding fastening mechanism, so that when a certain electric pile is damaged, the fastening mechanism corresponding to the electric pile unit where the electric pile is located can be directly disassembled under the condition of minimum influence, and the damaged electric pile can be quickly replaced.

Description

Technical Field

[0001] The present application relates to the technical field of solid oxide fuel cells, and in particular to a solid oxide fuel cell system and an operating method thereof. Background Art

[0002] Solid Oxide Fuel Cell (SOFC) belongs to the third generation of fuel cells. It is an all-solid-state chemical power generation device that directly converts the chemical energy stored in fuel and oxidant into electrical energy in an efficient and environmentally friendly manner at medium and high temperatures. The solid oxide fuel cell system requires three working fluids: water, air and fuel. The hot zone auxiliary part of the solid oxide fuel cell system is responsible for converting the three working fluids of fuel, air and water into the components and environment required for the stack subsystem to generate electricity. The stack subsystem directly converts the chemical energy in the converted working fluid into electrical energy under the conditions of temperature, catalyst, etc., and generates a certain amount of heat.

[0003] In related technologies, SOFC stacks usually use ceramic materials as the main material for battery cells, and the battery cells are prone to deformation when they are enlarged, which makes it difficult for SOFC stacks to be made into high-power stacks. In actual application scenarios, except for the distributed household scenario load requirements at the kilowatt level, other industrial application scenarios require loads of tens of kilowatts, hundreds of kilowatts or even megawatts. Usually, the requirements of these scale scenarios are composed of modular system units. Modular system units can be 20 kilowatts, 50 kilowatts or 100 kilowatts, etc.

[0004] However, when a modular system unit fails and the fuel cell stack needs to be repaired, practical problems such as difficulty and inconvenience in maintenance are faced. Summary of the invention

[0005] Based on this, it is necessary to provide a solid oxide fuel cell system and its operation method to address the problem of difficulty in maintenance of modular system units.

[0006] A solid oxide fuel cell system, comprising:

[0007] Supports;

[0008] A working medium auxiliary processing module, arranged on the support member;

[0009] A plurality of battery stack units are enclosed on the peripheral side of the working medium auxiliary processing module, each of the battery stack units includes at least two battery stacks, and each of the battery stack units is connected to the support member through a corresponding fastening mechanism.

[0010] In one embodiment, the solid oxide fuel cell system includes a gas distribution platform, the fuel cell stack is arranged on the gas distribution platform, a gas distribution channel is opened in the gas distribution platform, at least one working fluid inlet and at least one gas distribution port are opened on the gas distribution platform, the gas distribution channel is connected to the working fluid auxiliary processing module through the working fluid inlet, and the gas distribution channel is connected to the fuel cell stack through the gas distribution port.

[0011] In one embodiment, the gas distribution channel includes a first gas distribution channel and a second gas distribution channel, and the first gas distribution channel and the second gas distribution channel are both closed structures connected end to end;

[0012] The gas distribution platform is also provided with a working fluid outlet and a gas return port. The working fluid inlet is communicated with the gas distribution port through the first gas distribution channel, and the gas return port is communicated with the working fluid outlet through the second gas distribution channel.

[0013] In one of the embodiments, a seal is provided on the gas distribution platform, and at least two through holes are opened on the seal. The gas distribution port is connected with the air inlet of the fuel cell stack through the through holes, and the air outlet of the fuel cell stack is connected with the air return port through the through holes. The fastening mechanism is used to make the fuel cell stack sealed and connected with the gas distribution platform through the seal.

[0014] In one of the embodiments, the gas distribution platform is arranged on the support member, a cavity is opened inside the gas distribution platform, the working fluid auxiliary processing module is located in the cavity, a first thermal insulation member is arranged in the cavity, and the first thermal insulation member separates the fuel cell stack and the gas distribution platform from the working fluid auxiliary processing module.

[0015] In one of the embodiments, the gas distribution platforms are arranged on the support member at intervals;

[0016] The solid oxide fuel cell system further includes a shell, and the shell is spaced apart from the outer periphery of the gas distribution platform.

[0017] In one of the embodiments, the fastening mechanism includes a pressure-bearing member and an elastic fastening assembly. The pressure-bearing member is simultaneously pressed onto all the battery stacks in the same battery stack unit. One end of the elastic fastening assembly is connected to the pressure-bearing member, and the other end is connected to the support member.

[0018] In one embodiment, the elastic fastening assembly includes a bolt, a locking nut and an elastic member, one end of the bolt is connected to the pressure-bearing member, and the other end passes through the support member to be threadedly connected to the locking nut. The elastic member is sleeved on the bolt, one end of the elastic member abuts against the locking nut, and the other end abuts against the support member.

[0019] In one of the embodiments, the elastic fastening assembly includes an insulating sleeve, which is sleeved outside the bolt, one end of the insulating sleeve extends into the battery stack unit, and the other end extends to abut against the elastic member.

[0020] A method for operating a solid oxide fuel cell system, wherein the working medium auxiliary processing module comprises a first heat exchanger, a second heat exchanger, a third heat exchanger, a burner and a reformer, and the working medium processed in the working medium auxiliary processing module comprises water, gas and air, and the operating method comprises:

[0021] The air enters the fuel cell stack after being preheated by the third heat exchanger;

[0022] The water is evaporated into water vapor through the first heat exchanger and then enters the reformer, the fuel gas is preheated through the second heat exchanger and then enters the reformer, the fuel gas and the water vapor react in the reformer and then enter the fuel cell stack and react with the air in the fuel cell stack;

[0023] The mixed gas discharged from the gas outlet of the fuel cell stack enters the burner and is burned, and the heat generated during the combustion process is used as the heat source of the first heat exchanger, the second heat exchanger and the third heat exchanger respectively.

[0024] In the above-mentioned solid oxide fuel cell system and its operation method, the stack unit is arranged on the periphery of the working fluid auxiliary processing module, which is convenient for the replacement of the stack. And each stack unit is connected to the support through a corresponding fastening mechanism. When a certain stack is damaged, the fastening mechanism corresponding to the stack unit where the stack is located can be directly disassembled with minimal impact, and the damaged stack can be quickly replaced. In addition, the entire working fluid auxiliary processing module is arranged on the inner side of the stack, so that the solid oxide fuel cell system has a higher thermal chaos effect, which reduces the thermal fluctuations in the solid oxide fuel cell system and improves the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 is a schematic structural diagram of a solid oxide fuel cell system from one perspective in one embodiment.

[0026] FIG. 2 is a schematic structural diagram of a solid oxide fuel cell system from another perspective in one embodiment.

[0027] FIG. 3 is a schematic diagram of the structure inside the gas distribution platform in one embodiment.

[0028] FIG. 4 is a schematic structural diagram of a working medium auxiliary processing module in an embodiment.

[0029] : 100, support member; 110, second thermal insulation member; 200, working fluid auxiliary processing module; 210, reformer; 220, first heat exchanger; 230, second heat exchanger; 240, third heat exchanger; 250, burner; 300, fuel cell unit; 310, fuel cell; 400, gas distribution platform; 410, first group of gas distribution channels; 420, second group of gas distribution channels; 411, first gas distribution channels; 412, second gas distribution channels; 430, working fluid inlet; 500, first thermal insulation member; 600, fastening mechanism; 610, bolt; 620, locking nut; 630, insulating sleeve; 640, elastic member; 650, pressure-bearing member; 660, first abutment member; 670, second abutment member. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0031] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0032] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0033] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0034] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0035] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0036] Referring to FIGS. 1 to 4 , a solid oxide fuel cell system provided in one embodiment of the present application includes a support 100, a working fluid auxiliary processing module 200, and a plurality of stack units 300. The working fluid auxiliary processing module 200 is disposed on the support 100; the plurality of stack units 300 are surrounded by the peripheral side of the working fluid auxiliary processing module 200, each stack unit 300 includes at least two stacks 310, and each stack unit 300 is connected to the support 100 through a corresponding fastening mechanism 600.

[0037] In this embodiment, the stack unit 300 is arranged at the periphery of the working fluid auxiliary processing module 200, so as to facilitate the replacement of the stack 310. Each stack unit 300 is connected to the support member 100 through a corresponding fastening mechanism 600. When a stack 310 is damaged, the fastening mechanism 600 corresponding to the stack unit 300 where the stack 310 is located can be directly disassembled with minimal impact, so as to quickly replace the damaged stack 310.

[0038] In addition, the entire working fluid auxiliary processing module 200 is arranged inside the fuel cell stack 310, so that the inside of the solid oxide fuel cell system has a higher thermal chaos effect, which reduces the thermal fluctuations in the solid oxide fuel cell system and improves the stability of the system.

[0039] In some embodiments, the solid oxide fuel cell system includes a gas distribution platform 400, the fuel cell stack 310 is arranged on the gas distribution platform 400, a gas distribution channel is opened in the gas distribution platform 400, at least one working fluid inlet and at least one gas distribution port are opened on the gas distribution platform 400, the gas distribution channel is connected to the working fluid auxiliary processing module 200 through the working fluid inlet, and the gas distribution channel is connected to the fuel cell stack 310 through the gas distribution port.

[0040] In this embodiment, the working fluid enters the gas distribution channel from at least one working fluid inlet for buffering, and then enters the fuel cell stack 310 through at least one gas distribution port. Through the buffering effect of the gas distribution channel, the gas can be evenly distributed in the gas distribution channel, and then the amount of gas entering the fuel cell stack 310 from each gas distribution port is made the same, which greatly improves the uniformity of gas distribution in the fuel cell stack 310.

[0041] Furthermore, the gas distribution channel includes a first gas distribution channel 411 and a second gas distribution channel 412. The first gas distribution channel 411 and the second gas distribution channel 412 are both closed structures connected end to end. A working fluid outlet and a return air port are also opened on the gas distribution platform 400. The working fluid inlet 430 is connected to the gas distribution port through the first gas distribution channel 411, and the return air port is connected to the working fluid outlet through the second gas distribution channel 412.

[0042] In this embodiment, an air inlet and an air outlet are provided at the bottom of the battery stack 310, the air inlet is connected to the air distribution port, and the air outlet is connected to the air return port. After the working medium is pre-treated in the working medium auxiliary processing module 200, it enters the first air distribution channel 411 from the working medium inlet 430, and then enters the corresponding battery stack 310 through the air distribution port on the first air distribution channel 411. The working medium that is completely reacted or not completely reacted in the battery stack 310 enters the second air distribution channel 412 through the air return port, and finally returns to the working medium auxiliary processing module 200 through the working medium outlet connected to the second air distribution channel 412. The medium is fuel or air.

[0043] It should be noted that there are multiple working fluid inlets, which are evenly distributed on the first gas distribution channel 411. The working fluid auxiliary processing module 200 is connected to the corresponding working fluid inlets through multiple branch pipes, so that the first gas distribution channel 411 can be quickly and evenly filled with working fluid. The corresponding multiple battery stacks 310 are arranged in sequence on the gas distribution platform 400, and each battery stack 310 is provided with an air inlet at the bottom. The air inlet and the gas distribution port are connected one by one, so as to achieve uniform gas distribution for each battery stack 310.

[0044] In addition, the first gas distribution channel 411 is a closed structure that is connected end to end, which makes it easier to make the working medium in the first gas distribution channel 411 more uniform, thereby achieving uniform gas distribution to different fuel cell stacks 310 .

[0045] It should also be emphasized that the gas distribution channels include a first group of gas distribution channels 410 and a second group of gas distribution channels 420, and the first group of gas distribution channels 410 and the second group of gas distribution channels 420 are respectively used to distribute different working fluids, for example, the first group of gas distribution channels 410 is used to distribute air, and the second group of gas distribution channels 420 is used to distribute fuel. Each group of gas distribution channels includes at least one first gas distribution channel 411 and at least one second gas distribution channel 412. The positions of the gas distribution channels correspond to the positions of the gas inlet and the gas outlet of the fuel cell stack.

[0046] Specifically, a seal (not shown) is provided on the gas distribution platform 400, and at least two through holes are opened on the seal. The gas distribution port is connected with the air inlet of the fuel cell stack 310 through the through holes, and the air outlet of the fuel cell stack 310 is connected with the air return port through the through holes. The fastening mechanism 600 is used to make the fuel cell stack 310 sealed and connected to the gas distribution platform 400 through the seal.

[0047] In this embodiment, the seal may be a sealing gasket. When the fastening mechanism 600 presses the battery stack 310, the pressing force can make the battery stack 310 and the gas distribution platform 400 sealed and connected. That is, at this time, it is only necessary to align the gas distribution port, the corresponding through hole and the air inlet, align the air outlet, the corresponding through hole and the air return port, and then press the battery stack 310 onto the gas distribution platform 400, so as to achieve a sealed connection between the gas distribution port and the air inlet, and a sealed connection between the air outlet and the air return port.

[0048] The shape of the gas distribution platform 400 can be circular or polygonal, such as a regular quadrilateral.

[0049] In some embodiments, the gas distribution platform 400 is set on the support member 100, a cavity is opened inside the gas distribution platform 400, the working fluid auxiliary processing module 200 is located in the cavity, a first thermal insulation member 500 is set in the cavity, and the fuel cell stack 310 and the gas distribution platform 400 are separated from the working fluid auxiliary processing module 200 by the first thermal insulation member 500.

[0050] The inner side of the fuel cell stack unit 300 is isolated from the working fluid auxiliary processing module 200 by the first thermal insulation component 500. At the same time, the bottom of the fuel cell stack 310 is isolated from the working fluid auxiliary processing module 200 by the gas distribution platform 400, thereby avoiding direct heat radiation or heat conduction between the working fluid auxiliary processing module 200 and the fuel cell stack 310, which may cause local overheating of the fuel cell stack 310, ensuring that the fuel cell stack 310 is not damaged by thermal stress during the temperature rise and fall cycle, thereby improving the operating life of the fuel cell stack 310.

[0051] In addition, the inner side of the gas distribution platform 400 is separated from the working fluid auxiliary processing module 200 by the first thermal insulation component 500, which is convenient for ensuring the uniformity of the temperature of the working fluid in the gas distribution platform 400, achieving the uniformity of thermal radiation and thermal convection of the fuel cell stack 310, thereby assisting in ensuring the uniformity of the operating temperature of the fuel cell stack 310.

[0052] Furthermore, the gas distribution platforms 400 are spaced apart on the support 100 ; the solid oxide fuel cell system further comprises a shell (not shown), and the shell is spaced apart from the periphery of the gas distribution platforms 400 .

[0053] The gas distribution platform 400 is arranged at intervals on the support 100, and the shell and the periphery of the gas distribution platform 400 are arranged at intervals, that is, the hot air in the working fluid auxiliary processing module 200 can flow from the gap between the gas distribution platform 400 and the support 100 to between the gas distribution platform 400 and the shell, and then expand and flow upward to the side of the fuel cell stack 310 due to heat expansion, thereby ensuring the uniformity of thermal radiation and thermal convection of the fuel cell stack 310, and further ensuring the uniformity of the operating conditions and power generation output of each fuel cell stack 310, while avoiding local overheating, ensuring that the fuel cell stack 310 is not damaged by thermal stress during the temperature rise and fall cycle, and improving the operating life of the fuel cell stack 310.

[0054] In some embodiments, the fastening mechanism 600 includes a pressure-bearing member 650 and an elastic fastening assembly. The pressure-bearing member 650 is simultaneously pressed onto all the battery stacks 310 in the same battery stack unit 300. One end of the elastic fastening assembly is connected to the pressure-bearing member 650, and the other end is connected to the support member 100.

[0055] In this embodiment, the pressure-bearing member 650 is squeezed by the elastic fastening assembly, so that the pressure-bearing member 650 can be pressed and fixed to the battery stack 310. In addition, since the pressure inside the battery stack 310 changes greatly before and after the reaction, the elastic fastening assembly is provided so that the pressing force applied by the elastic fastening assembly on the pressure-bearing fastener is adapted to the pressure inside the battery stack 310. When the pressure inside the battery stack 310 is relatively high, the elastic fastening assembly can provide expansion space for the battery stack 310.

[0056] In some embodiments, the elastic fastening assembly includes a bolt 610, a locking nut 620 and an elastic member 640. One end of the bolt 610 is connected to the pressure-bearing member 650, and the other end passes through the support member 100 to be threadedly connected to the locking nut 620. The elastic member 640 is sleeved on the bolt 610, and one end of the elastic member 640 abuts against the locking nut 620, and the other end abuts against the support member 100.

[0057] In some embodiments, the elastic member 640 may be a spring or an elastic block. A second heat insulating member 110 is provided on the support member 100, so that the side of the support member 100 close to the battery stack 310 is a hot zone, and the side of the support member 100 away from the battery stack 310 is a cold zone. The elastic member 640 is located on the side of the support member 100 away from the battery stack 310, which can prevent the elastic member 640 from failing due to a high temperature environment.

[0058] Specifically, each stack unit 300 includes two stacks 310, the pressure bearing member 650 covers the two stacks 310 at the same time, and the bolt 610 is arranged between the two stacks 310, so that the pressing force on the two stacks 310 is the same. When one of the stacks 310 is damaged, it is only necessary to disassemble the elastic fastening assembly on the stack 310, which is easy to repair and convenient.

[0059] In some other embodiments, the elastic member 640 may also be disposed between the shell and the pressure-bearing member 650 , which can also achieve an elastic fastening effect on the battery stack 310 .

[0060] In some embodiments, the elastic fastening assembly includes an insulating sleeve 630 , which is sleeved outside the bolt 610 , with one end of the insulating sleeve 630 extending into the stack unit 300 , and the other end extending to abut against the elastic member 640 .

[0061] Specifically, since the bolt 610 is a conductor, the bolt 610 needs to pass through the gas distribution platform 400, and the insulating sleeve 630 is sleeved on the bolt 610 to prevent the bolt 610 from directly contacting the gas distribution platform 400, causing the entire support member 100 to be conductive.

[0062] The insulating sleeve 630 is provided with a first abutment member 660 and a second abutment member 670, one end of the insulating sleeve 630 abuts against the pressure-bearing member 650, the other end of the insulating sleeve 630 abuts against the elastic member 640 through the first abutment member 660, and the second abutment member 670 abuts against the support member 100. Alternatively, the sleeve is directly fixedly connected to the support member 100 through the second abutment member 670, and the bolt 610 can move axially in the insulating sleeve 630.

[0063] In some embodiments, the auxiliary working medium processing module 200 includes a first heat exchanger 220, a second heat exchanger 230, a third heat exchanger 240, a burner 250 and a reformer 210. The working medium processed in the auxiliary working medium processing module 200 includes water, gas and air. The operation method includes:

[0064] The air is preheated by the first heat exchanger 220 and then enters the fuel cell stack 310;

[0065] Water is evaporated into water vapor through the second heat exchanger 230 and then enters the reformer 210. The fuel gas is preheated through the third heat exchanger 240 and then enters the reformer 210. The fuel gas and water vapor react in the reformer 210 and then enter the fuel cell stack 310 and react with the air in the fuel cell stack 310 to generate electricity.

[0066] The mixed gas discharged from the gas outlet of the fuel cell stack 310 enters the burner 250 and burns. The heat generated during the combustion process is used as the heat source of the first heat exchanger 220, the second heat exchanger 230 and the third heat exchanger 240 respectively.

[0067] In this embodiment, the mixed gas discharged from the outlet of the fuel cell stack 310 includes methane, hydrogen, carbon monoxide, and carbon dioxide. Methane, hydrogen, and carbon monoxide react in the burner 250 to generate heat, which is used to heat water, gas, and air, respectively, thereby improving the conversion efficiency of the fuel cell stack 310 and preventing air pollution after direct discharge.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A solid oxide fuel cell system, characterized in that: The solid oxide fuel cell system comprises: Support members; A working medium auxiliary processing module is provided on the support member; A plurality of fuel cell stack units are enclosed on the peripheral side of the working medium auxiliary processing module, each fuel cell stack unit includes at least two fuel cells, and each fuel cell stack unit is connected to the support member through a corresponding fastening mechanism.

2. The solid oxide fuel cell system according to claim 1, characterized in that The solid oxide fuel cell system includes a gas distribution platform, the fuel cell stack is arranged on the gas distribution platform, a gas distribution channel is opened in the gas distribution platform, at least one working fluid inlet and at least one gas distribution port are opened on the gas distribution platform, the gas distribution channel is connected to the working fluid auxiliary processing module through the working fluid inlet, and the gas distribution channel is connected to the fuel cell stack through the gas distribution port.

3. The solid oxide fuel cell system according to claim 2, characterized in that: The air distribution channel includes a first air distribution channel and a second air distribution channel, and the first air distribution channel and the second air distribution channel are both closed structures connected end to end; The gas distribution platform is further provided with a working fluid outlet and a gas return port. The working fluid inlet is connected to the gas distribution port through the first gas distribution channel, and the gas return port is connected to the working fluid outlet through the second gas distribution channel.

4. The solid oxide fuel cell system according to claim 3, characterized in that A seal is provided on the gas distribution platform, and at least two through holes are opened on the seal. The gas distribution port is connected with the air inlet of the fuel cell stack through the through holes, and the air outlet of the fuel cell stack is connected with the air return port through the through holes. The fastening mechanism is used to make the fuel cell stack sealed and connected to the gas distribution platform through the seal.

5. The solid oxide fuel cell system according to claim 2, wherein: The gas distribution platform is arranged on the support member, a cavity is opened inside the gas distribution platform, the working fluid auxiliary processing module is located in the cavity, a first thermal insulation member is arranged in the cavity, and the first thermal insulation member separates the fuel cell stack and the gas distribution platform from the working fluid auxiliary processing module.

6. The solid oxide fuel cell system according to claim 5, characterized in that: The gas distribution platforms are arranged on the support member at intervals; The solid oxide fuel cell system further includes a shell, which is spaced apart from the periphery of the gas distribution platform.

7. The solid oxide fuel cell system according to claim 1, characterized in that: The fastening mechanism includes a pressure-bearing member and an elastic fastening assembly. The pressure-bearing member is pressed onto all the battery stacks in the same battery stack unit at the same time. One end of the elastic fastening assembly is connected to the pressure-bearing member, and the other end is connected to the support member.

8. The solid oxide fuel cell system according to claim 7, characterized in that: The elastic fastening assembly includes a bolt, a locking nut and an elastic member, one end of the bolt is connected to the pressure-bearing member, and the other end passes through the support member to be threadedly connected to the locking nut. The elastic member is sleeved on the bolt, one end of the elastic member abuts the locking nut, and the other end abuts the support member.

9. The solid oxide fuel cell system according to claim 8, characterized in that: The elastic fastening assembly includes an insulating sleeve, which is sleeved outside the bolt. One end of the insulating sleeve extends into the battery stack unit, and the other end extends to abut against the elastic member.

10. A method for operating a solid oxide fuel cell system according to any one of claims 1 to 9, characterized in that: The auxiliary working medium processing module includes a first heat exchanger, a second heat exchanger, a third heat exchanger, a burner, and a reformer. The working medium processed in the auxiliary working medium processing module includes water, gas, and air. The operating method includes: The air is preheated by the third heat exchanger and then enters the fuel cell stack; The water is evaporated into water vapor through the first heat exchanger and then enters the reformer. The fuel gas is preheated through the second heat exchanger and then enters the reformer. The fuel gas and the water vapor react in the reformer and then enter the fuel cell stack and react with the air in the fuel cell stack. The mixed gas discharged from the gas outlet of the fuel cell stack enters the burner and is burned. The heat generated during the combustion process is used as a heat source for the first heat exchanger, the second heat exchanger, and the third heat exchanger.

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