Fuel cell circulation system and circulation method

Abstract

The present application discloses a fuel cell circulation system and a circulation method, wherein the fuel cell circulation system is applied to a solid oxide fuel cell system; the fuel cell circulation system comprises: a circulation device, a fuel input path, a compression device, a distribution device, a reforming device and a fuel cell stack, wherein the fuel input path is connected to the reforming device, the reforming device is respectively connected to the circulation device and the fuel cell stack, the circulation device is respectively connected to the compression device, the distribution device and the fuel cell stack, the compression device is connected to the distribution device, and the distribution device is connected to the fuel cell stack; the hydrogen-containing tail gas generated by the fuel cell stack is circulated through the circulation device and introduced into the reforming device, and after the reforming reaction, it enters the fuel cell stack for secondary utilization, thereby solving the problem that the existing solid oxide fuel cell cannot effectively utilize the fuel cell stack anode tail gas with a high hydrogen concentration generated by the fuel cell stack anode during operation, resulting in a low fuel utilization rate of the entire SOFC system.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a fuel cell circulation system and circulation method. Background Art

[0002] Solid oxide fuel cells (SOFCs) can usually reform and decompose fuels in the form of hydrocarbons to power the stack. The oxygen and water vapor required in the fuel reforming process are generally provided by designing matching evaporation devices and gas channels in the system, and the system is usually more complex. The tail gas generated by the anode of the stack can generally be burned through the tail gas burner to generate heat. The heat generated keeps the stack and reformer in the required high-temperature working environment, but this often leads to low power generation efficiency of the system due to the combustion of too much hydrogen-containing tail gas, and excessively high temperatures will have an adverse effect on the tail gas burner.

[0003] During operation, existing solid oxide fuel cells are unable to effectively utilize the anode tail gas containing a high concentration of hydrogen generated by the anode of the stack, resulting in a low fuel utilization rate of the entire SOFC system. Summary of the invention

[0004] The main purpose of the present application is to provide a fuel cell circulation system and circulation method, aiming to solve the problem that the existing solid oxide fuel cell cannot effectively utilize the stack anode tail gas with a high hydrogen concentration generated by the stack anode during operation, resulting in low fuel utilization of the entire SOFC system.

[0005] To achieve the above-mentioned object, the present application provides a fuel cell circulation system, which is applied to a solid oxide fuel cell system; wherein the solid oxide fuel cell system is used for fuel power generation, comprising:

[0006] A circulation device, a fuel input path, a compression device, a distribution device, a reforming device and a fuel cell stack, wherein the fuel input path is in communication with the reforming device, the reforming device is in communication with the circulation device and the fuel cell stack respectively, the circulation device is in communication with the compression device, the distribution device and the fuel cell stack respectively, the compression device is in communication with the distribution device, and the distribution device is in communication with the fuel cell stack;

[0007] Among them, the circulation device is used to introduce the hydrogen-containing exhaust gas generated by the fuel cell stack into the reforming device; the fuel input path is used to provide fuel to the reforming device; the compression device is used to introduce air outside the system into the distribution device; the distribution device is used to distribute air in proportion, and introduce the proportionally distributed air into the circulation device and the fuel cell stack respectively; the reforming device is used to reform the fuel and air, and introduce the gas generated by the reforming reaction into the fuel cell stack.

[0008] Optionally, it also includes a first passage, a second passage, a circulation passage, a third passage, a fourth passage, a fifth passage and a sixth passage, wherein the two ends of the first passage are respectively connected to the circulation device and the distribution device; the two ends of the second passage are respectively connected to the reforming device and the fuel cell stack; the two ends of the circulation passage are respectively connected to the circulation device and the fuel cell stack; the two ends of the third passage are respectively connected to the circulation device and the reforming device; the two ends of the fourth passage are respectively connected to the distribution device and the fuel cell stack; the two ends of the fifth passage are respectively connected to the circulation device and the compression device; the two ends of the sixth passage are respectively connected to the distribution device and the circulation passage.

[0009] Optionally, one end of the sixth passage is connected to the distribution device, and the other end of the sixth passage is connected to the circulation air inlet of the circulation device, and the circulation air inlet is the connection point between the circulation passage and the circulation device.

[0010] Optionally, the circulation device comprises: a first housing, a frame, a stator, a rotor, an impeller, a first fan blade and a second housing, wherein the stator and the rotor are mounted on the frame, the first housing is mounted on the outside of the frame, the impeller is connected to the tail end of the rotor, the second housing cover is arranged on the outside of the impeller, the second housing is connected to the frame to form a gas mixing chamber, and the first fan blade is mounted on the front of the impeller;

[0011] The rotor is provided with a first air inlet duct along the axial direction, and the first air inlet duct is connected to the distribution device; the impeller and the frame form a confluence channel; the confluence channel is connected to the first air inlet duct, and the confluence channel is connected to the gas mixing chamber; a second air inlet duct is provided on the side of the frame, and the two ends of the second air inlet duct are respectively connected to the distribution device and the confluence channel; a hot gas input port and a mixed gas outlet are provided on the second shell, and the hot gas input port and the mixed gas outlet are both connected to the gas mixing chamber.

[0012] Optionally, a total air cavity is formed between the first shell and the frame, a total air inlet of the total air cavity is connected to external air, and a total air outlet of the total air cavity is connected to the compression device.

[0013] Optionally, a branch passage is opened on the side of the tail end of the rotor, and two ends of the branch passage are respectively connected to the first air inlet passage and the confluence channel.

[0014] Optionally, there are a plurality of bronchial passages, and the plurality of bronchial passages are evenly distributed in the radial direction of the tail end of the rotor.

[0015] Optionally, there are a plurality of second air inlet passages, and the plurality of second air inlet passages are evenly distributed in the radial direction of the frame.

[0016] Optionally, it also includes a second fan blade, which is mounted on the impeller and is located in the confluence channel.

[0017] In addition, to achieve the above-mentioned purpose, the present application also provides a circulation method based on the fuel cell circulation system, comprising:

[0018] The total air required by the solid oxide fuel cell system enters through the total air inlet of the circulation device, the total air flows through the total air cavity of the circulation device and is introduced into the compression device through the total air outlet of the circulation device, and the compression device introduces the total air into the distribution device;

[0019] After the distribution device distributes the air, the distributed air is respectively introduced into the first air inlet and the second air inlet of the circulation device through the first passage, and the air flowing in through the first air inlet and the second air inlet merges in the converging channel and flows into the gas mixing chamber;

[0020] The hydrogen-containing tail gas generated by the fuel cell stack is introduced into the circulation device through the circulation passage, and the air prepared by the distribution device is introduced into the circulation passage through the sixth passage to cool the hydrogen-containing tail gas;

[0021] The hydrogen-containing tail gas after cooling enters the gas mixing chamber through the hot gas input port and mixes with the air flowing into the converging channel;

[0022] The impeller is driven to rotate by the rotation of the rotor to suck the hydrogen-containing tail gas into the gas mixing chamber, and the air and the hydrogen-containing tail gas entering the gas mixing chamber are compressed and evenly mixed through the first blade on the impeller;

[0023] The compressed and evenly mixed gas flows out of the circulation device through the mixed gas outlet and is introduced into the reforming device through the third passage.

[0024] A fuel cell circulation system and circulation method are proposed in the embodiments of the present application, wherein the fuel cell circulation system is applied to a solid oxide fuel cell system; wherein the solid oxide fuel cell system is used for fuel power generation, and the circulation method is applied to a circulation device of the fuel cell circulation system; the fuel cell circulation system comprises: a circulation device, a fuel input path, a compression device, a distribution device, a reforming device and a fuel cell stack, wherein the fuel input path is connected to the reforming device, the reforming device is respectively connected to the circulation device and the fuel cell stack, the circulation device is respectively connected to the compression device, the distribution device and the fuel cell stack, the compression device is connected to the distribution device, and the distribution device is connected to the fuel cell stack; wherein the circulation device is used to convert the fuel generated by the fuel cell stack into Hydrogen tail gas is introduced into the reforming device; the fuel input path is used to provide fuel to the reforming device; the compression device is used to introduce air outside the system into the distribution device; the distribution device is used to distribute air in proportion, and introduce the air distributed in proportion into the circulation device and the fuel cell stack respectively; the reforming device is used to reform the fuel and the air, and introduce the gas generated by the reforming reaction into the fuel cell stack; the hydrogen-containing tail gas generated by the fuel cell stack is circulated and introduced into the reforming device through the circulation device, and after the reforming reaction, it enters the fuel cell stack for secondary utilization, so as to solve the problem that the existing solid oxide fuel cell cannot effectively utilize the fuel cell stack anode tail gas with a high hydrogen concentration generated by the fuel cell stack anode during operation, resulting in a low fuel utilization rate of the entire SOFC system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic diagram of the structure of a fuel cell circulation system according to an embodiment of the present application;

[0026] Figure 2 This is a schematic diagram of the cross-sectional structure of a circulation device according to an embodiment of the present application;

[0027] Figure 3 for Figure 2 A schematic diagram of the partially enlarged structure at center A;

[0028] Figure 4 A schematic diagram of a circulation method flow chart of an embodiment of the present application;

[0029] Legend: 1-circulation device, 101-first shell, 102-frame, 103-stator, 104-rotor body, 105-rotating shaft, 106-first bearing, 107-second bearing, 108-connecting component, 109-impeller, 110-first fan blade, 111-second shell, 112-hot air input port, 113-first air inlet, 114-total air outlet, 115-second air inlet, 116-branch duct, 117-mixed gas outlet, 118-total air inlet, 119-convergence channel, 120-second fan blade, 2-first passage, 3-fuel input passage, 4-second passage, 5-circulation passage, 6-third passage, 7-fourth passage, 8-compression device, 9-distribution device, 10-fifth passage, 11-reforming device, 12-fuel stack, 13-sixth passage.

[0030] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0033] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral 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 the present invention can be understood according to specific circumstances.

[0034] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] Embodiment 1

[0036] Reference Figure 1 , a fuel cell circulation system, the fuel cell circulation system is applied to a solid oxide fuel cell system; wherein the solid oxide fuel cell system is used for fuel power generation, comprising: a circulation device 1, a fuel input path 3, a compression device 8, a distribution device 9, a reforming device 11, a fuel stack 12, a first passage 2, a second passage 4, a circulation passage 5, a third passage 6, a fourth passage 7, a fifth passage 10 and a sixth passage 13, the fuel input path 3 is connected to the reforming device 11, the reforming device 11 is respectively connected to the circulation device 1 and the fuel stack 12, the circulation device 1 is respectively connected to the compression device 8, the distribution device 9 and the fuel stack 12, the compression device 8 is connected to the distribution device 9 The distribution device 9 is connected to the fuel cell stack 12; wherein the circulation device 1 is used to introduce the hydrogen-containing tail gas generated by the fuel cell stack 12 into the reforming device 11; the fuel input path 3 is used to provide fuel to the reforming device 11; the compression device 8 is used to introduce the air outside the system into the distribution device 9; the distribution device 9 is used to distribute the air in proportion, and introduce the proportionally distributed air into the circulation device 1 and the fuel cell stack 12 respectively; the reforming device 11 is used to reform the fuel and the air, and introduce the gas generated by the reforming reaction into the fuel cell stack 12; in this embodiment, the compression device 8 is an air compressor, the distribution device 9 is an air distributor, and the reforming device 11 is a reformer;

[0037] The two ends of the first passage 2 are respectively connected to the circulation device 1 and the distribution device 9; the two ends of the second passage 4 are respectively connected to the reforming device 11 and the battery stack 12; the two ends of the circulation passage 5 are respectively connected to the circulation device 1 and the battery stack 12; the two ends of the third passage 6 are respectively connected to the circulation device 1 and the reforming device 11; the two ends of the fourth passage 7 are respectively connected to the distribution device 9 and the battery stack 12; the two ends of the fifth passage 10 are respectively connected to the circulation device 1 and the compression device 8; the two ends of the sixth passage 13 are respectively connected to the distribution device 9 and the circulation passage 5;

[0038] One end of the sixth passage 13 is connected to the distribution device 9, and the other end of the sixth passage 13 is connected to the circulation air inlet of the circulation device 1, and the circulation air inlet is the connection point between the circulation passage 5 and the circulation device 1; the hydrogen-containing exhaust gas generated by the anode of the fuel cell stack 12 itself has a very high temperature. When the hydrogen-containing exhaust gas reaches the hot gas input port 112 of the circulation device 1, it still has a high temperature of 700°C. The air in the sixth passage 13 is used to cool the hydrogen-containing exhaust gas entering the circulation passage 5 to reduce its temperature to less than 450°C, thereby achieving a pre-cooling effect and meeting system requirements.

[0039] Embodiment 2

[0040] It is understandable that the circulation device 1 in the first embodiment can be an existing air compressor. Figure 2 , Figure 3The circulation device 1 of this embodiment includes: a first shell 101, a frame 102, a stator 103, a rotor, an impeller 109, a first fan blade 110 and a second shell 111, wherein the stator 103 and the rotor are mounted on the frame 102, the first shell 101 is mounted on the outside of the frame 102, the impeller 109 is connected to the tail end of the rotor, the second shell 111 is covered on the outside of the impeller 109, the second shell 111 is connected to the frame 102 to form a gas mixing chamber, and the first fan blade 110 is mounted on the front of the impeller 109; the rotor is provided with a first air inlet 113 along the axial direction, and the first air inlet 113 is connected to the splitter The impeller 109 and the frame 102 form a confluence channel 119; a branch airway 116 is provided on the side of the tail end of the rotating shaft 105, and the two ends of the branch airway 116 are respectively connected to the first air inlet 113 and the confluence channel 119, and the confluence channel 119 is connected to the gas mixing chamber; a second air inlet 115 is provided on the side of the frame 102, and the two ends of the second air inlet 115 are respectively connected to the distribution device 9 and the confluence channel 119; a hot air input port 112 and a mixed gas outlet 117 are provided on the second shell 111, and the hot air input port 112 and the mixed gas outlet 117 are both connected to the gas mixing chamber.

[0041] In this embodiment, a first bearing 106 and a second bearing 107 are respectively disposed at both ends of the rotating shaft 105 , and the first bearing 106 and the second bearing 107 are both fixedly mounted on the frame 102 .

[0042] In this embodiment, the air input into the circulation device 1 through the first passage 2 is divided into two paths: the first path is to enter through the first air inlet 113. After the air flows into the first air inlet 113, it enters the confluence channel 119 through the branch 116 on the side of the tail end of the shaft 105. The air flowing through the first air inlet 113 can cool the shaft 105 on the one hand, and on the other hand, after flowing out at a high speed through the branch 116, it will form a relatively high pressure in the confluence channel 119, which cooperates with the air-sealing serrated structure on the left side of the branch 116 (the air-sealing serrated structure on the left side of the branch 116 is not shown in the figure), which can effectively prevent the high-temperature hydrogen-containing gas in the gas mixing chamber from flowing out. The exhaust gas flows back into the converging channel 119, which effectively protects heat-sensitive components such as the first bearing 106 and the second bearing 107, thereby ensuring that lubrication failure caused by high temperature will not occur when low-cost ball bearings are used, thereby reducing manufacturing costs; the second path enters through the second air inlet 115, and the air flows into the second air inlet 115 and then flows into the converging channel 119; the air in the two paths converges in the converging channel 119 and flows into the gas mixing chamber, and is mixed with the hydrogen-containing exhaust gas entering through the hot gas inlet 112 in the gas mixing chamber. The air flowing through can cool the frame 102 to prevent the frame 102 from being overheated.

[0043] In this embodiment, a total air cavity is formed between the first shell 101 and the frame 102, and the total air inlet 118 of the total air cavity is connected to the external air, and the total air outlet 114 of the total air cavity is connected to the compression device 8; when the air enters the total air cavity from the total air inlet 118 and enters the compression device 8 from the total air outlet 114, the heat conducted from the high-temperature end of the circulation device 1 to the stator 103 can be taken away by the incoming air, thereby optimizing the higher temperature gradient of the circulation device 1 along its axial direction, and at the same time, the incoming air can be preheated, thereby minimizing energy loss and further improving the overall efficiency of the system.

[0044] In this embodiment, there are a plurality of first blades 110, and the plurality of first blades 110 are evenly distributed around the circumference of the impeller 109. When the impeller 109 is in high-speed rotation, the input gas can be compressed by the first blades 110. Although the circulation device 1 will perform work on the high-temperature hydrogen-containing exhaust gas entering the interior thereof, due to the limitations of the SOFC (especially the plate-type structure) cell structure, there is no need to provide high-pressure gas for the stack, so the compression work here will not significantly increase the temperature of the compressed gas.

[0045] In the present embodiment, there is a large temperature difference between the front and rear sides of the impeller 109. Ordinary metal materials may deform due to uneven heating or expand greatly due to high temperature, thereby causing problems in the operation of the rotor. Therefore, when manufacturing the impeller 109, a ceramic material with a low expansion coefficient is used. The ceramic material can be a non-metallic ceramic material or a metal ceramic material.

[0046] In this embodiment, the rotor is composed of a rotor body 104 and a rotating shaft 105. The rotor body 104 is sleeved on the rotating shaft 105, and the rotor body 104 and the rotating shaft 105 are interference fit; there are a plurality of bronchial passages 116, and the plurality of bronchial passages 116 are evenly distributed in the radial direction at the tail end of the rotor.

[0047] In this embodiment, there are a plurality of second air inlet passages 115 , and the plurality of second air inlet passages 115 are evenly distributed in the radial direction of the frame 102 . The evenly distributed second air inlet passages 115 can make the circulation device 1 have better overall stability.

[0048] In this embodiment, a second fan blade 120 is also included. The second fan blade 120 is installed on the rear side of the impeller 109, and the second fan blade 120 is located in the confluence channel 119. When the impeller 109 rotates at a high speed, the second fan blade 120 is driven to rotate at a high speed together. The air entering the confluence channel 119 is compressed and sucked in by the second fan blade 120, which can offset the pressure loss in the first air inlet 113 and the second air inlet 115 to a certain extent, and guide the air into the gas mixing chamber.

[0049] In this embodiment, a temperature sensor can be set at a reasonable position of the exhaust gas burner. The exhaust gas burner is connected to the fuel cell stack 12. The exhaust gas burner is not shown in the figure. The exhaust gas burner belongs to the device in the solid oxide fuel cell system. The exhaust gas burner is used to burn the exhaust gas generated by the fuel cell stack 12. The maximum temperature of the exhaust gas burner is controlled by the temperature sensor, and the rotation speed of the rotating shaft 105 is controlled at the same time, so as to realize real-time control of the gas flow in the circulation passage and ensure the stable combustion power of the exhaust gas burner.

[0050] Embodiment 3

[0051] Reference Figure 4 , an embodiment of the present application provides a circulation method based on the fuel cell circulation system; the circulation method is:

[0052] After the solid oxide fuel cell system is started, the total air required by the solid oxide fuel cell system enters through the total air inlet 118 of the circulation device 1, the total air flows through the total air cavity of the circulation device 1 and is introduced into the compression device 8 through the total air outlet 114 of the circulation device 1, and the compression device 8 introduces the total air into the distribution device 9;

[0053] After the distribution device 9 distributes the air, at the beginning, the air is first introduced into the fuel cell stack 12 through the fourth passage 7, and the distributed air is respectively introduced into the first air inlet 113 and the second air inlet 115 of the circulation device 1 through the first passage 2. The air flowing in through the first air inlet 113 and the second air inlet 115 merges in the confluence channel 119 and flows into the gas mixing chamber. The circulation device 1 introduces the air into the reforming device 11, and the required fuel is introduced into the reforming device 11 through the fuel input path 3. The air and the fuel undergo a reforming reaction in the reforming device 11, and the gas after the reforming reaction is introduced into the fuel cell stack 12 through the second passage 4 to provide the required gas for the fuel cell stack 12.

[0054] The hydrogen-containing tail gas generated by the battery stack 12 is introduced into the circulation device 1 through the circulation passage 5, and the air distributed by the distribution device 9 is introduced into the circulation passage 5 through the sixth passage 13 to cool the hydrogen-containing tail gas; in this embodiment, one end of the sixth passage 13 is connected to the distribution device 9, and the other end of the sixth passage 13 is connected to the circulation air inlet of the circulation device 1, and the circulation air inlet is the connection point between the circulation passage 5 and the circulation device 1; the hydrogen-containing tail gas generated by the anode of the battery stack 12 itself has a very high temperature. When the hydrogen-containing tail gas reaches the hot air input port 112 of the circulation device 1, it still has a high temperature of 700°C. The hydrogen-containing tail gas entering the circulation passage 5 is cooled by the air in the sixth passage 13 to reduce its temperature to less than 450°C, thereby achieving a pre-cooling effect and meeting system requirements;

[0055] The hydrogen-containing tail gas after cooling enters the gas mixing chamber through the hot gas input port 112 and mixes with the air flowing into the converging channel 119;

[0056] The impeller 109 is driven to rotate by the rotation of the rotor to suck the hydrogen-containing tail gas into the gas mixing chamber, and the air and the hydrogen-containing tail gas entering the gas mixing chamber are compressed and mixed evenly through the first blade 110 on the impeller 109;

[0057] The compressed and evenly mixed gas flows out of the circulation device 1 through the mixed gas outlet 117 and is introduced into the reforming device 11 through the third passage 6. After the reforming reaction occurs in the reforming device 11, the gas enters the fuel cell stack 12 to provide the fuel cell stack 12 with the required gas, thereby effectively utilizing the fuel cell anode tail gas with a high hydrogen concentration generated by the fuel cell anode, improving the fuel utilization rate of the entire SOFC system, and achieving the effect of recycling energy saving.

[0058] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A fuel cell circulation system, characterized in that: The fuel cell circulation system is applied to a solid oxide fuel cell system, and the solid oxide fuel cell system is used for fuel power generation; the fuel cell circulation system comprises: A circulation device (1), a fuel input path (3), a compression device (8), a distribution device (9), a reforming device (11) and a fuel cell stack (12), wherein the fuel input path (3) is in communication with the reforming device (11), the reforming device (11) is in communication with the circulation device (1) and the fuel cell stack (12), the circulation device (1) is in communication with the compression device (8), the distribution device (9) and the fuel cell stack (12), the compression device (8) is in communication with the distribution device (9), and the distribution device (9) is in communication with the fuel cell stack (12); The circulation device (1) is used to introduce the hydrogen-containing tail gas generated by the fuel cell stack (12) into the reforming device (11); the fuel input path (3) is used to provide fuel to the reforming device (11); the compression device (8) is used to introduce air outside the system into the distribution device (9); the distribution device (9) is used to distribute air in proportion, and introduce the air distributed in proportion into the circulation device (1) and the fuel cell stack (12) respectively; the reforming device (11) is used to reform the fuel and the air, and introduce the gas generated by the reforming reaction into the fuel cell stack (12); The circulation device comprises: a first shell (101), a frame (102), a stator (103), a rotor, an impeller (109), a first fan blade (110) and a second shell (111), wherein the stator (103) and the rotor are mounted on the frame (102), the first shell (101) is mounted on the outside of the frame (102), the impeller (109) is connected to the rotor, the second shell (111) is covered on the outside of the impeller (109), the second shell (111) is connected to the frame (102) to form a gas mixing chamber, and the first fan blade (110) is mounted on the impeller (109); The rotor is provided with a first air inlet (113) along the axial direction, and the first air inlet (113) is connected to the distribution device (9); the impeller (109) and the frame (102) form a confluence channel (119); the confluence channel (119) is connected to the first air inlet (113), and the confluence channel (119) is connected to the gas mixing chamber; a second air inlet (115) is provided on the side of the frame (102), and two ends of the second air inlet (115) are respectively connected to the distribution device (9) and the confluence channel (119); the second shell (111) is provided with a hot gas input port (112) and a mixed gas outlet (117), and the hot gas input port (112) and the mixed gas outlet (117) are both connected to the gas mixing chamber.

2. The fuel cell circulation system according to claim 1, characterized in that: The invention also comprises a first passage (2), a second passage (4), a circulation passage (5), a third passage (6), a fourth passage (7), a fifth passage (10) and a sixth passage (13); the two ends of the first passage (2) are respectively connected to the circulation device (1) and the distribution device (9); the two ends of the second passage (4) are respectively connected to the reforming device (11) and the fuel cell stack (12); the two ends of the circulation passage (5) are respectively connected to the circulation device (1) and the fuel cell stack (12); the two ends of the third passage (6) are respectively connected to the circulation device (1) and the reforming device (11); the two ends of the fourth passage (7) are respectively connected to the distribution device (9) and the fuel cell stack (12); the two ends of the fifth passage (10) are respectively connected to the circulation device (1) and the compression device (8); and the two ends of the sixth passage (13) are respectively connected to the distribution device (9) and the circulation passage (5).

3. The fuel cell circulation system according to claim 2, characterized in that: One end of the sixth passage (13) is in communication with the distribution device (9), and the other end of the sixth passage (13) is in communication with a circulation air inlet of the circulation device (1), wherein the circulation air inlet is a connection point between the circulation passage (5) and the circulation device (1).

4. The fuel cell circulation system according to claim 3, characterized in that: A total air cavity is formed between the first shell (101) and the frame (102); a total air inlet (118) of the total air cavity is in communication with external air; and a total air outlet (114) of the total air cavity is in communication with the compression device (8).

5. The fuel cell circulation system according to claim 3, characterized in that: A branch passage (116) is provided on the side surface of the tail end of the rotor, and two ends of the branch passage (116) are respectively connected to the first air inlet passage (113) and the converging passage (119).

6. The fuel cell circulation system according to claim 5, characterized in that: There are a plurality of bronchial passages (116), and the plurality of bronchial passages (116) are evenly distributed in the radial direction of the tail end of the rotor.

7. The fuel cell circulation system according to claim 1, characterized in that: There are a plurality of second air inlet passages (115), and the plurality of second air inlet passages (115) are evenly distributed in the radial direction of the frame (102).

8. The fuel cell circulation system according to claim 1, characterized in that: The circulation device further comprises a second fan blade (120), wherein the second fan blade (120) is mounted on the impeller (109), and the second fan blade (120) is located in the converging channel (119).

9. A circulation method based on the fuel cell circulation system according to claim 4, characterized in that: include: The total air required by the solid oxide fuel cell system enters through the total air inlet (118) of the circulation device (1), the total air flows through the total air passage cavity of the circulation device (1) and is introduced into the compression device (8) through the total air outlet (114) of the circulation device (1), and the compression device (8) introduces the total air into the distribution device (9); After the distribution device (9) distributes the air, the distributed air is respectively introduced into the first air inlet (113) and the second air inlet (115) of the circulation device (1) through the first passage (2); the air flowing in through the first air inlet (113) and the second air inlet (115) merges in the converging channel (119) and flows into the gas mixing chamber; The hydrogen-containing tail gas generated by the fuel cell stack (12) is introduced into the circulation device (1) through the circulation passage (5), and the air prepared by the distribution device (9) is introduced into the circulation passage (5) through the sixth passage (13) to cool the hydrogen-containing tail gas; The hydrogen-containing tail gas after being cooled enters the gas mixing chamber through the hot gas input port (112) and mixes with the air flowing into the converging channel (119); The impeller (109) is driven to rotate by the rotation of the rotor to suck the hydrogen-containing tail gas into the gas mixing chamber, and the air and the hydrogen-containing tail gas entering the gas mixing chamber are compressed and evenly mixed by the first blade (110) on the impeller (109); The compressed and evenly mixed gas flows out of the circulation device (1) through the mixed gas outlet (117) and is introduced into the reforming device (11) through the third passage (6).

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