A high efficiency planar SOFC stack system coupled with an ammonia cracking device

Abstract

This invention discloses a high-efficiency planar SOFC stack system coupled with an ammonia cracking device, comprising an upper current collector, a lower current collector, and a stacked structure. The lower current collector has a first input unit, and the upper current collector has a second input unit, a first outlet pipe, and a second outlet pipe. The anode first input pipe and the anode second input pipe are both connected to the first outlet pipe, and the cathode first input pipe and the cathode second input pipe are both connected to the second outlet pipe. This invention employs a dual-flow air intake method, allowing fuel and air to flow into each individual cell group from opposite ends of the stack, achieving a balanced distribution of reactant concentrations, effectively reducing the internal temperature gradient of the stack, and improving operational stability and material utilization. The integrated ammonia cracking device is located below the stack, utilizing the high-temperature exhaust gas from the stack to provide a heat source for the ammonia cracking reaction, achieving cascaded heat utilization, avoiding difficulties in hydrogen storage and transportation, and reducing system costs.

Description

Technical Field

[0001] This invention relates to the field of fuel cells, and in particular to a high-efficiency planar SOFC stack system coupled with an ammonia cracking unit. Background Technology

[0002] As an important branch of fuel cell technology, solid oxide fuel cells (SOFCs), due to their unique working principle and structural design, achieve a theoretical efficiency of 50% or higher compared to the thermodynamic efficiency of traditional internal combustion engines, which is typically below 40%. Furthermore, they can maintain high efficiency even under partial load, significantly improving energy utilization. Because of their high energy conversion efficiency and environmental friendliness, SOFCs are considered one of the forward-looking technologies leading the future energy revolution and building low-carbon or even zero-carbon energy systems.

[0003] SOFCs (Steam-Powered Fuel Cells) exhibit outstanding fuel adaptability due to their high operating temperatures, enabling them to directly utilize hydrocarbon fuels such as ammonia and methane. These fuels can be converted into hydrogen in situ through high-temperature cracking reactions before entering the battery, providing the necessary power for power generation. However, the high-temperature cracking process absorbs a significant amount of heat. If this heat relies entirely on an external heat source or the fuel's own chemical energy conversion, the system's thermal efficiency will be significantly reduced. A waste heat recovery mechanism is employed, utilizing the high-temperature exhaust gas from the fuel cell stack as a heat source to provide the necessary heat for the fuel cracking process. This design not only achieves cascaded energy utilization but also solves the problem of reduced thermal efficiency caused by additional heating.

[0004] Planar SOFC stacks are assembled from multiple planar single-cell packs, featuring a compact structure and allowing for flexible adjustment of the stack's output voltage by varying the number of stacked cells. Planar SOFC stacks typically employ a unidirectional gas supply method. Because the gas is gradually consumed along the flow direction within the channel, this unidirectional supply leads to uneven distribution of reactant gas concentration along the flow direction, resulting in excessively large internal temperature gradients. This can severely impact the stack's operational stability due to thermal stress imbalance; furthermore, the uneven temperature exacerbates the performance degradation differences between individual cell packs, leading to a significant mismatch in their lifespans. This not only reduces power generation efficiency but also results in substantial material waste. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a high-efficiency planar SOFC stack system coupled with an ammonia cracking unit. A bidirectional air intake method and optimized flow channel structure are employed to address the aforementioned problems to a certain extent.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-efficiency flat-plate SOFC stack system coupled with an ammonia cracking unit includes a first input unit, a second input unit, a first outlet pipeline, and a second outlet pipeline. The first input unit includes an anode first input pipeline, a cathode first input pipeline, and a fuel distribution pipeline. The second input unit includes an anode second input pipeline and a cathode second input pipeline. In terms of connection, the ends of the anode first input pipeline and the anode second input pipeline are both connected to the first outlet pipeline; the ends of the cathode first input pipeline and the cathode second input pipeline are both connected to the second outlet pipeline; and the fuel distribution pipeline is connected to the anode second input pipeline. Furthermore, the first anode input pipe and the first cathode input pipe are arranged side by side and have the same flow direction, and the second anode input pipe and the second cathode input pipe are arranged side by side and have the same flow direction; or the first anode input pipe and the first cathode input pipe are arranged side by side and have opposite flow directions, and the second anode input pipe and the second cathode input pipe are arranged side by side and have opposite flow directions.

[0007] Furthermore, the first input unit and the second input unit are arranged symmetrically to each other. The first input unit and the second input unit are the same size, but the outer wall of the anode first input pipe in the first input unit can be removed to facilitate gas flow. The anode first input pipe and the cathode second input pipe are arranged symmetrically to each other, and the anode second input pipe and the cathode first input pipe are arranged symmetrically to each other. The first outlet pipe and the second outlet pipe are arranged symmetrically to each other. The first input unit, the second input unit, the first outlet pipe, and the second outlet pipe together form a symmetrical structure. The first input unit is arranged on the lower manifold, and the second input unit, the first outlet pipe, and the second outlet pipe are arranged on the upper manifold.

[0008] Furthermore, the flow direction of the first anode input pipe is opposite to that of the second anode input pipe; the flow direction of the first cathode input pipe is opposite to that of the second cathode input pipe.

[0009] Furthermore, the first and second air outlet pipes have the same flow direction, which is upward.

[0010] Furthermore, the gas input-output device also includes a gas flow channel device, which includes an anode gas flow channel plate, a thermally conductive support, and a cathode gas flow channel plate; both the anode gas flow channel plate and the cathode gas flow channel plate are provided with a first gas inlet, a second gas inlet, a reaction zone inlet, and a gas outlet; the first gas inlet and the second gas inlet are connected end-to-end to the reaction zone inlet, and the gas outlet is connected end-to-end to the reaction zone inlet through the flow channel to achieve countercurrent heat exchange.

[0011] Furthermore, for the anode gas flow channel plate, its anode first gas inlet is connected to the anode first input pipeline, its anode second gas inlet is connected to the anode second input pipeline, and its anode gas outlet is connected to the first outlet pipeline; for the cathode gas flow channel plate, its cathode first gas inlet is connected to the cathode first input pipeline, its cathode second gas inlet is connected to the cathode second input pipeline, and its cathode gas outlet is connected to the second outlet pipeline.

[0012] Furthermore, other components of the fuel cell stack from the upper current collector to the lower current collector have gas channels at corresponding positions of the anode gas outlet, cathode gas outlet, anode second gas inlet, and cathode second gas inlet, which connect and respectively form the first gas outlet pipe, the second gas outlet pipe, the anode second input pipe, and the cathode second input pipe; other components of the fuel cell stack from the lower current collector to the upper current collector have gas channels at corresponding positions of the anode first gas inlet and the cathode first gas inlet, which connect and respectively form the anode first input pipe and the cathode first input pipe.

[0013] Furthermore, for the anode gas flow channel plate or the cathode gas flow channel plate, the gas flowing into each of the first gas inlet and the second gas inlet is mixed outside the reaction zone of the battery before being introduced into the reaction zone inlet; the flow channels for gas mixing are arranged symmetrically along the diagonal axis of the gas flow channel plate.

[0014] Furthermore, the anode gas flow channel plate is identical to the cathode gas flow channel plate and is arranged symmetrically on both sides of the thermally conductive support. This symmetrical arrangement can be either with the anode gas flow channel plate on top and the cathode gas flow channel plate on the bottom, or vice versa. The thermally conductive support serves both a thermal conductivity function and a structural support function.

[0015] Furthermore, the anode gas flow channel plate and the cathode gas flow channel plate adopt a single flow channel structure, and the reaction zone inlet and the gas outlet are connected by a single-line spiral flow channel.

[0016] Another objective of this invention is to provide an integrated ammonia cracking device for a flat-plate SOFC fuel cell stack, comprising a plate-fin heat exchanger, a high-temperature exhaust gas inlet, a low-temperature exhaust gas outlet, an ammonia inlet, a fuel outlet, a wire guide trough, a high-temperature exhaust gas diversion zone, a low-temperature exhaust gas convergence zone, an ammonia diversion zone, and a fuel convergence zone. The device is rectangular in shape and positioned below the fuel cell stack. It is installed by attaching the fuel cell stack base to the top cover of the cracking device and inserting a first input unit through a notch. The exhaust gas inlet is connected to the first and second exhaust gas pipelines. The first fuel outlet is connected to the first anode input pipeline. The second fuel outlet is connected to the fuel distribution pipeline.

[0017] Furthermore, the high-temperature exhaust gas diversion zone is connected to the exhaust gas inlet; the low-temperature exhaust gas confluence zone is connected to the exhaust gas outlet; the ammonia gas diversion zone is connected to the ammonia gas inlet; and the fuel confluence zone is connected to the fuel distribution pipeline inlet and the anode first input pipeline inlet.

[0018] Furthermore, the plate-fin heat exchanger employs corrugated fins and includes independent exhaust gas side channels and fuel side channels. The exhaust gas side channels and fuel side channels are separated by a thermally conductive baffle, and heat exchange occurs through the thermally conductive baffle. The high-temperature exhaust gas diversion zone and the low-temperature exhaust gas convergence zone are located on both sides of the exhaust gas side channels, and the flow direction of the exhaust gas side channels is set to horizontal. The ammonia gas diversion zone and the fuel convergence zone are located on both sides of the fuel side channels, and the flow direction of the fuel side channels is set to upward.

[0019] Furthermore, the high-temperature exhaust gas inlet and the low-temperature exhaust gas outlet are arranged coaxially and parallel to each other. The high-temperature exhaust gas inlet can be arranged at the center of any outer plate around the cracking unit, while the low-temperature exhaust gas outlet is arranged at the center of the opposite outer plate; the ammonia inlet is located at the center of the lower outer plate of the cracking unit.

[0020] Compared with the prior art, the beneficial effects of the present invention are: By directing the gas flow into the fuel cell stack in a dual-direction manner, the fuel and air concentrations flowing into each cell are made more even, avoiding the concentration gradient differences caused by gas consumption along the flow path in traditional unidirectional layouts. This creates more consistent air intake conditions among the cells. Furthermore, this flow field arrangement helps improve the uniformity of temperature distribution within the stack. As the concentration distribution of fuel and air becomes more consistent, the electrochemical reaction rates in each cell region are more balanced, reducing local overheating or overcooling and effectively minimizing the temperature gradient within the stack. This reduced temperature gradient not only improves the thermal stability of the stack and reduces the risk of thermal stress damage to ceramic seals and connectors, but also further ensures the reliability of the stack during long-term operation.

[0021] Meanwhile, the balanced distribution of concentration and temperature makes the working state of each cell more consistent, and the current density and fuel utilization rate of each cell during operation are roughly the same. This balanced use helps to delay the premature degradation of individual cells due to overload, and makes the degradation rate of the entire stack more synchronized, thereby extending the overall service life of the stack, effectively reducing the maintenance frequency and replacement cost caused by uneven local losses, and thus improving the economic efficiency of the system.

[0022] By integrating an ammonia cracking unit and using the high-temperature exhaust gas from the fuel cell stack as a heat source, the required thermal energy for the ammonia cracking reaction is provided through heat transfer, thereby significantly improving the overall thermal efficiency of the fuel cell stack while fully utilizing the waste heat of the exhaust gas. The high-temperature exhaust gas is rich in unused thermal energy after the fuel cell stack reaction; recovering and using it in the ammonia cracking process not only achieves cascade utilization of heat but also reduces the demand for external heat sources. At the same time, this technical solution effectively avoids the technical bottlenecks and safety risks in the storage and transportation of hydrogen. By using ammonia as a hydrogen carrier, the hydrogen required by the fuel cell stack is produced in situ through the cracking process, avoiding the high energy consumption and equipment costs associated with hydrogen compression or liquefaction. Furthermore, ammonia is an industrially readily prepared, stored, and transported chemical raw material with a mature supply chain, low storage and transportation costs, and high energy density. Adopting the ammonia cracking hydrogen supply route can significantly reduce the overall cost of the fuel supply system and improve the economic efficiency and reliability of system operation. Attached Figure Description

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0025] Figure 2 This is a schematic diagram of the overall structure of the fuel cell stack according to an embodiment of the present invention. To facilitate observation of the internal structure of the fuel cell stack, one of the fuel cell stack's constant temperature insulating outer plates is made transparent, and the arrows indicate the direction of gas flow.

[0026] Figure 3 This is a schematic diagram of the bottom structure of the fuel cell stack according to an embodiment of the present invention. The arrows indicate the direction of gas flow.

[0027] Figure 4 This is a schematic diagram of the exploded structure of the fuel cell stack according to an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of the fuel cell stack explosion structure according to an embodiment of the present invention. The arrows indicate the direction of gas flow.

[0029] Figure 6 This is a schematic diagram of the exploded structure of a gas flow channel device including cathode and anode flow channels according to an embodiment of the present invention.

[0030] Figure 7 This is a schematic diagram of the anode gas flow channel plate and anode flow channel structure according to an embodiment of the present invention.

[0031] Figure 8 This is a schematic diagram of the integrated ammonia cracking device in an embodiment of the present invention. The arrows indicate the direction of gas flow.

[0032] Figure 9This is a cross-sectional view of the integrated ammonia cracking device according to an embodiment of the present invention. To facilitate observation of the internal structure, part of the outer plate of the cracking device has been cut off. The gray ring is only used as an auxiliary illustrative area and does not represent any structure.

[0033] Figure 10 This is a schematic diagram of the exploded structure of a plate-fin heat exchanger according to an embodiment of the present invention. The arrows indicate the direction of gas flow.

[0034] 1. Upper current collector plate; 2. Upper current collector plate wire; 3. Second input unit; 4. Anode second input pipe inlet; 5. Cathode second input pipe inlet; 6. Second fuel inflow direction; 7. Second air inflow direction; 8. First gas outlet pipe; 9. First gas outlet pipe outlet; 10. First exhaust gas outflow direction; 11. Second gas outlet pipe; 12. Second gas outlet pipe outlet; 13. Second exhaust gas outflow direction; 14. Stack thermostatic insulating outer plate; 15. Cathode gas sealing gasket; 16. Single cell; 17. Single cell support frame; 18. Anode gas sealing gasket; 19. Gas flow channel device. 20. Lower collector plate; 21. Lower collector plate wire; 22. First input unit; 23. Anode first input pipeline inlet; 24. Fuel distribution pipeline inlet; 25. Cathode first input pipeline inlet; 26. First fuel inflow direction; 27. Distribution fuel inflow direction; 28. First air inflow direction; 29. ​​First flow direction of anode gas in the fuel cell stack; 30. Second flow direction of anode gas in the fuel cell stack; 31. First flow direction of cathode gas in the fuel cell stack; 32. Second flow direction of cathode gas in the fuel cell stack; 33. Anode tail gas outflow direction; 34. Cathode tail gas outflow direction.

[0035] 35. Anode gas flow channel plate; 36. Thermally conductive support; 37. Cathode gas flow channel plate; 38. Anode gas confluence channel; 39. Anode gas reaction channel; 40. Cathode gas confluence channel; 41. Cathode gas reaction channel; 42. Anode gas outlet; 43. Cathode gas outlet; 44. Anode first gas inlet; 45. Anode second gas inlet; 46. Anode reaction zone inlet; 47. Cathode first gas inlet; 48. Cathode second gas inlet; 49. Anode gas flow direction.

[0036] 50. Cracking unit outer plate; 51. Wire guide trough; 52. High-temperature tail gas inlet; 53. Low-temperature tail gas outlet; 54. Ammonia inlet; 55. High-temperature tail gas inflow direction; 56. Low-temperature tail gas outflow direction; 57. Ammonia inflow direction; 58. Plate-fin heat exchanger; 59. High-temperature tail gas diversion zone; 60. Low-temperature tail gas confluence zone; 61. Ammonia diversion zone; 62. Fuel confluence zone; 63. Zone partition; 64. Tail gas side fins; 65. Thermally conductive partition; 66. Ammonia side fins; 67. Fuel side gas flow direction; 68. Tail gas side gas flow direction. Detailed Implementation

[0037] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples.

[0038] In this invention, "upper" and "lower" are both used in the context of... Figure 1 The indicated position shall prevail.

[0039] See Figure 1 , Figure 2 , Figure 3 and Figure 8 , Figure 1 The overall structure of the embodiment is shown, and the relative positions of the fuel cell stack and the integrated ammonia cracking device after installation are shown. The specific installation method is as follows: the lower current collector 20 is attached to the outer plate 50 of the cracking device above the cracking device, the lower current collector wire 21 is placed in the wire groove 51, and the first input unit 22 is inserted into the gap of the outer plate 50 of the cracking device above the cracking device.

[0040] See Figure 2 and Figure 3 The planar SOFC stack of this invention mainly comprises an upper current collector 1, a lower current collector 20, and a stacked structure between the upper current collector 1 and the lower current collector 20. All four sides of the stacked structure are covered by a thermostatic insulating outer plate 14. The upper current collector 1 is provided with an upper current collector conductor 2, a second input unit 3, a first exhaust pipe 8, and a second exhaust pipe 11. The second input unit 3 has an anode second input pipe inlet 4 and a cathode second input pipe inlet 5. Figure 2 The flow directions of fuel and air entering the fuel cell stack from the upper current collector 1 are marked, namely the second fuel inflow direction 6 and the second air inflow direction 7. A second exhaust outlet 9 is provided on the first exhaust pipe 8. Figure 2 The flow direction of the anode exhaust gas leaving the fuel cell stack from the upper current collector 1 is marked, i.e., the first exhaust gas outflow direction 10. A second exhaust outlet 12 is provided on the second exhaust pipe 11. Figure 2 The direction of cathode exhaust gas flow from the upper current collector 1 away from the fuel cell stack is marked, i.e., the first exhaust gas outflow direction 13.

[0041] The lower collector plate 20 is provided with a first input unit 22 and a lower collector plate wire 21. The first input unit 22 has an anode first input pipeline inlet 23 and a cathode first input pipeline inlet 25, which are respectively connected to the anode first input pipeline and the cathode first input pipeline. Figure 3 The flow directions of fuel and air entering the stack from the lower collector plate 20 are marked, namely the first fuel inflow direction 26 and the first air inflow direction 28.

[0042] According to the flow resistance theory in fluid mechanics, in a fuel cell stack structure employing a unidirectional air intake, the flow path length and local resistance differ significantly when gas is distributed to each cell layer via a common channel. Specifically, cells closer to the air intake have shorter flow paths and lower local resistance coefficients, allowing gas to pass preferentially and resulting in a higher flow rate distribution. Conversely, cells farther from the air intake require gas to flow through longer manifold channels, leading to increased friction loss and local resistance losses, forming a significant flow pressure drop gradient. As the number of stack layers increases, the pressure drop accumulation effect within the manifold intensifies, further deteriorating the uniformity of flow rate distribution among the cells. This uneven flow rate distribution due to differences in flow channel configuration directly causes a non-uniform distribution of reactant concentrations at the inlet of each cell, posing a technical hazard to the consistency of subsequent electrochemical reactions and the uniformity of the stack's temperature field.

[0043] According to the principles of electrochemical kinetics, the electrochemical reaction rate of a single cell is positively correlated with the concentration of reactants it contacts. In a unidirectional gas inlet layout, the differences in fuel and oxygen concentrations among the individual cells lead to significant unevenness in their electrochemical reaction rates and corresponding heat generation rates. Specifically, in areas with higher reactant concentrations, the electrochemical reaction is more vigorous, the current density increases, and local heat generation concentrates, forming high-temperature hotspots; while in areas with lower reactant concentrations, the reaction rate is limited, heat generation decreases, and relatively low-temperature regions are formed. This results in a significant temperature gradient along the gas flow direction within the stack. Therefore, to ensure a more uniform fuel concentration entering each cell, during long-term operation, the material degradation rate of cells in the high-temperature region is significantly higher than that in the low-temperature region. This leads to a divergence in the lifespan of each cell, manifested as premature failure of some cells and inconsistent degradation rates across the entire stack, ultimately limiting the overall lifespan and material utilization of the stack. Therefore, to ensure a more uniform fuel concentration entering each cell, fuel also enters the fuel distribution pipe along the fuel flow direction 27, eventually reaching the anode second input pipe inlet 4 and then entering the stack along the second fuel flow direction 6. In order to make the oxygen concentration entering each cell more uniform, air at the same flow rate enters the stack along the first air inflow direction 28 and the second air inflow direction 7, respectively.

[0044] The first exhaust pipe 8 and the second exhaust pipe 11 are centrally symmetrical about the upper current collector plate with the upper current collector plate conductor 2 as the center. The first input unit 22 and the second input unit 3 are centrally symmetrical about the center of the fuel cell stack. Although the first input unit 22 and the second input unit 3 are not completely identical, this central symmetry means that the anode first input pipe and the cathode second input pipe are arranged centrally symmetrically about the center of the fuel cell stack, and the anode second input pipe and the cathode first input pipe are arranged centrally symmetrically about the center of the fuel cell stack. In addition, the first input unit 22, the second input unit 3, the first exhaust pipe 8, and the second exhaust pipe 11 as a whole are centrally symmetrical about the center of the fuel cell stack.

[0045] See Figure 4 , Figure 5 , Figure 6 and Figure 7 In this embodiment, the stacked structure between the upper current collector 1 and the lower current collector 20 contains four individual cells and three thermally conductive supports 36 for connecting the individual cells. The stacked structure is arranged from top to bottom as follows: cathode gas channel plate 37, cathode gas sealing gasket 15, cell, anode gas sealing gasket 18, gas channel device 19, cathode gas sealing gasket 15, cell, anode gas sealing gasket 18, gas channel device 19, cathode gas sealing gasket 15, cell, anode gas sealing gasket 18, gas channel device 19, cathode gas sealing gasket 15, cell, anode gas sealing gasket 18, anode gas channel plate 35.

[0046] The solar cell comprises a single cell 16 and a single cell support frame 17. The single cell 16 is fixed in the middle of the single cell support frame 17. From top to bottom, the single cell 16 consists of a porous anode, a solid oxide electrolyte, and a porous cathode. The single cell support frame 17 serves a sealing and structural support function.

[0047] The gas flow channel device 19 includes an anode gas flow channel plate 35, a thermally conductive support 36, and a cathode gas flow channel plate 37. The thermally conductive support 36 serves to connect and conduct heat, control the temperature uniformity of the single-cell packs on both sides, and reduce the temperature gradient inside the stack.

[0048] Both the anode gas flow channel plate 35 and the cathode gas flow channel plate 37 are provided with a first gas inlet, a second gas inlet, a reaction zone inlet, and a gas outlet; wherein each of their first gas inlets and second gas inlets is connected end-to-end to their respective reaction zone inlets, and their respective gas outlets are connected end-to-end to their respective reaction zone inlets through the flow channels to achieve countercurrent heat exchange. Specifically: Taking the anode gas flow channel plate 35 as an example, it has an anode gas confluence flow channel 38, an anode gas reaction flow channel 39, an anode gas outlet 42, a cathode gas outlet 43, an anode first gas inlet 44, an anode second gas inlet 45, an anode reaction zone inlet 46, a cathode first gas inlet 47, and a cathode second gas inlet 48. The flow channels on the anode gas flow channel plate 35 start from the anode first gas inlet 44 and the anode second gas inlet 45, and are arranged symmetrically along a diagonal axis. After mixing outside the reaction zone flow channel, the gas reaches the anode reaction zone inlet 46, and then along the anode gas reaction flow channel 39, reaching the anode gas outlet 42. The flow direction of the anode gas within the anode gas flow channel plate 35 is as follows: Figure 7 As shown, the direction of anode gas flow is 49.

[0049] The anode gas reaction channel 39 in the reaction zone adopts a single-line spiral channel structure, and the anode reaction zone inlet 46 and the anode gas outlet 42 are arranged side by side to form countercurrent heat exchange.

[0050] The anode gas flow channel plate 35 and the cathode gas flow channel plate 37 are arranged symmetrically on the upper and lower sides of the heat-conducting support 36. In essence, the anode gas flow channel plate 35 and the cathode gas flow channel plate 37 are identical, differing only in their positions and functions. In this embodiment, the anode gas flow channel plate 35 is on top, and the cathode gas flow channel plate 37 is on the bottom. The anode gas outlet 42 in the anode gas flow channel plate 35 corresponds to the anode gas outlet on the cathode gas flow channel plate 37, the cathode gas outlet 43 corresponds to the cathode gas outlet on the cathode gas flow channel plate 37, the anode gas confluence channel 38 corresponds to the cathode gas confluence channel 40, the anode gas reaction channel 39 corresponds to the cathode gas reaction channel 41, and so on.

[0051] From the upper current collector plate 1 to the lower current collector plate 20, other components of the fuel cell stack have equally sized circular gas channels at corresponding positions of the anode gas outlet 42, cathode gas outlet 43, anode second gas inlet 45, and cathode second gas inlet 48, which together form the first gas outlet pipe 8, the second gas outlet pipe 11, the anode second input pipe, and the cathode second input pipe. From the lower current collector plate 20 to the upper current collector plate 1, other components of the fuel cell stack have equally sized circular gas channels at corresponding positions of the anode first gas inlet 44 and the cathode first gas inlet 47, which together form the anode first input pipe and the cathode first input pipe. In this embodiment, all holes are circular holes; in other embodiments, they can also be square holes, with the side length being the same as the diameter of the circular hole.

[0052] Fuel flows into the anode gas channel plate 35 from the first and second anode input pipes and then contacts the solid oxide electrolyte on the porous anode of the single cell 16 and participates in the reaction. After flowing out of the anode gas channel plate 35, it becomes high-temperature exhaust gas and flows into the first outlet pipe 8. Air flows into the cathode gas channel plate 37 from the first and second cathode input pipes and then contacts the solid oxide electrolyte on the porous cathode of the single cell 16 and participates in the reaction. After flowing out of the cathode gas channel plate 37, it becomes high-temperature exhaust gas and flows into the second outlet pipe 11.

[0053] In this embodiment, the anode first input pipe and the cathode first input pipe on the first input unit 22 are arranged side by side and have the same flow direction, as shown in the figure. Figure 5 The first flow direction 29 of the anode gas and the first flow direction 31 of the cathode gas within the fuel cell stack are shown; the anode second input pipe and the cathode second input pipe on the second input unit 3 are arranged side by side and have the same flow direction, as shown in the figure. Figure 5 The second flow direction 30 of the anode gas and the second flow direction 32 of the cathode gas within the fuel cell stack are shown. Simultaneously, the first flow direction 29 of the anode gas within the fuel cell stack is opposite to the second flow direction 30; the first flow direction 31 of the cathode gas within the fuel cell stack is opposite to the second flow direction 32. The first outlet pipe 8 and the second outlet pipe 11 have the same flow direction, as shown... Figure 5 The outlet directions of the anode tail gas (33) and cathode tail gas (34) are shown. The first anode input pipe and the second anode input pipe are connected to the first outlet pipe (8) through the flow channel on the anode gas flow channel plate (35); the first cathode input pipe and the second cathode input pipe are connected to the second outlet pipe (11) through the flow channel on the cathode gas flow channel plate (37).

[0054] According to the design principles of planar SOFC stacks, the number of solar cells always exceeds the number of connectors, while the number of seals is twice the number of solar cells. In other embodiments, the total number of connectors and the corresponding number of solar cells and seals can be further increased, depending on the actual voltage required.

[0055] See Figure 8 , Figure 9 and Figure 10 The present invention also provides an integrated ammonia cracking device, which is generally rectangular in shape and located below the fuel cell stack. It includes a fuel distribution pipeline inlet 24, an outer plate 50, a wire guide trough 51, a high-temperature tail gas inlet 52, a low-temperature tail gas outlet 53, and an ammonia inlet 54. Internally, it includes a plate-fin heat exchanger 58, a high-temperature tail gas diversion zone 59, a low-temperature tail gas convergence zone 60, an ammonia diversion zone 61, a fuel convergence zone 62, and zone partitions 63. The integrated ammonia cracking device integrates the functions of tail gas utilization and fuel production.

[0056] The high-temperature exhaust gas diversion zone 59 is connected to the high-temperature exhaust gas inlet 52; the low-temperature exhaust gas confluence zone 60 is connected to the low-temperature exhaust gas outlet 53; the ammonia gas diversion zone 61 is connected to the ammonia gas inlet 54; and the fuel confluence zone 62 is connected to the fuel distribution pipeline inlet 24 and the anode first input pipeline inlet 23.

[0057] The high-temperature exhaust gases from the first exhaust pipe 8 and the second exhaust pipe 11 converge and flow into the high-temperature exhaust gas inlet 52 via the high-temperature exhaust gas inlet direction 55. After passing through the high-temperature exhaust gas diversion zone 59, they are diverted to the various exhaust gas side channels of the plate-fin heat exchanger 58 to begin heat exchange. After heat exchange, they enter the low-temperature exhaust gas confluence zone 60 and then flow out from the low-temperature exhaust gas outlet 53 via the low-temperature exhaust gas outlet direction 56. Simultaneously, ammonia gas flows in from the ammonia inlet 54 via the ammonia inlet direction 57 and is diverted to the various fuel side channels of the plate-fin heat exchanger 58 via the ammonia diversion zone 61 to begin endothermic cracking. After the reaction is complete, it enters the fuel confluence zone 62. Subsequently, a portion of the initially heated fuel flows into the fuel distribution pipe via the fuel distribution pipe inlet 24 via the fuel distribution inlet direction 27, and into the fuel stack via the second fuel inlet direction 6 of the second input unit 3. The other portion flows into the fuel stack via the first fuel inlet direction 26 from the anode first input pipe inlet 23.

[0058] For the plate-fin heat exchanger 58, in this embodiment, the arrangement from front to back is as follows: outer plate 50 of the pyrolysis unit, tail gas side fins 64, thermally conductive baffle 65, ammonia side fins 66, thermally conductive baffle 65, tail gas side fins 64, thermally conductive baffle 65, ammonia side fins 66, thermally conductive baffle 65, tail gas side fins 64, thermally conductive baffle 65, ammonia side fins 66, outer plate 50 of the pyrolysis unit. The arrows in the figure also indicate the gas flow direction 67 on the fuel side and the gas flow direction 68 on the tail gas side.

[0059] In other embodiments, the number and height of the exhaust-side fins 64, the heat-conducting baffles 65, and the ammonia-side fins 66 can be further increased, depending on the actual required fuel consumption rate and amount.

[0060] The above description is merely a preferred embodiment of the present invention, and therefore should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made in accordance with the scope of the patent and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A high efficiency planar SOFC stack system coupled with an ammonia cracking device, characterized in that, It includes a first input unit, a second input unit, a first exhaust pipe, and a second exhaust pipe; The first input unit is provided with an anode first input pipeline, a cathode first input pipeline, and a fuel distribution pipeline; the second input unit is provided with an anode second input pipeline and a cathode second input pipeline; the ends of the anode first input pipeline and the anode second input pipeline are both connected to the first gas outlet pipeline; the ends of the cathode first input pipeline and the cathode second input pipeline are both connected to the second gas outlet pipeline; the fuel distribution pipeline is connected to the anode second input pipeline; The first anode input pipe and the first cathode input pipe are arranged side by side and have the same flow direction, and the second anode input pipe and the second cathode input pipe are arranged side by side and have the same flow direction; or the first anode input pipe and the first cathode input pipe are arranged side by side and have opposite flow directions, and the second anode input pipe and the second cathode input pipe are arranged side by side and have opposite flow directions.

2. The high efficient planar SOFC stack system coupled with ammonia cracking device according to claim 1, wherein, The first input unit is disposed on the lower collector plate, and the second input unit is disposed on the upper collector plate. The first input unit and the second input unit are arranged in a centrally symmetrical manner. The anode first input pipeline and the cathode second input pipeline are arranged in a centrally symmetrical manner, and the anode second input pipeline and the cathode first input pipeline are arranged in a centrally symmetrical manner. The first input unit, the second input unit, the first outlet pipeline and the second outlet pipeline together form a centrally symmetrical structure.

3. The high efficient planar SOFC stack system coupled with ammonia cracking device according to claim 1, wherein, The flow direction of the first anode input pipe is opposite to that of the second anode input pipe; the flow direction of the first cathode input pipe is opposite to that of the second cathode input pipe.

4. The high-efficiency flat-plate SOFC stack system for coupling ammonia cracking unit according to claim 1, characterized in that, The first and second air outlet pipes have the same flow direction, both being set upwards.

5. The high-efficiency flat-plate SOFC stack system coupled with the ammonia cracking unit according to claim 1, characterized in that, The gas input-output device further includes a gas flow channel device; the gas flow channel device includes an anode gas flow channel plate, a thermally conductive support, and a cathode gas flow channel plate; both the anode gas flow channel plate and the cathode gas flow channel plate are provided with a first gas inlet, a second gas inlet, a reaction zone inlet, and a gas outlet; the first gas inlet and the second gas inlet are connected end-to-end to the reaction zone inlet, and the gas outlet is connected end-to-end to the reaction zone inlet through the flow channel to achieve countercurrent heat exchange; For the anode gas flow channel plate, its anode first gas inlet is connected to the anode first input pipeline, its anode second gas inlet is connected to the anode second input pipeline, and its anode gas outlet is connected to the first outlet pipeline; for the cathode gas flow channel plate, its cathode first gas inlet is connected to the cathode first input pipeline, its cathode second gas inlet is connected to the cathode second input pipeline, and its cathode gas outlet is connected to the second outlet pipeline. Gas channels are provided at corresponding positions of the anode gas outlet, cathode gas outlet, anode second gas inlet, and cathode second gas inlet in the other components of the fuel cell stack from the upper current collector to the lower current collector. These channels connect and form the first gas outlet pipe, the second gas outlet pipe, the anode second input pipe, and the cathode second input pipe, respectively. Gas channels are provided at corresponding positions of the anode first gas inlet and the cathode first gas inlet in the other components of the fuel cell stack from the lower current collector to the upper current collector. These channels connect and form the anode first input pipe and the cathode first input pipe, respectively.

6. The high-efficiency flat-plate SOFC stack system for coupling ammonia cracking unit according to claim 5, characterized in that, For the anode gas flow channel plate or the cathode gas flow channel plate, the gas flowing into the first gas inlet and the gas flowing into the second gas inlet of each gas is mixed outside the reaction zone of the battery before being introduced into the reaction zone inlet; the flow channels for gas mixing are arranged symmetrically along the diagonal axis of the corresponding gas flow channel plate.

7. The high-efficiency flat-plate SOFC stack system for coupling ammonia cracking unit according to claim 5, characterized in that, The anode gas flow channel plate is exactly the same as the cathode gas flow channel plate, and is arranged in a centrally symmetrical manner on both sides of the heat-conducting support.

8. The high-efficiency flat-plate SOFC stack system for coupling ammonia cracking unit according to claim 5, characterized in that, The anode gas flow channel plate and the cathode gas flow channel plate adopt a single flow channel structure, and their respective reaction zone inlets and gas outlets are connected by a single-line spiral flow channel.

9. An integrated ammonia cracking unit, employing the high-efficiency flat-plate SOFC stack system coupled with the ammonia cracking unit as described in claim 1, characterized in that, The integrated ammonia cracking unit is rectangular in shape and is located below the flat-plate SOFC stack. It includes a plate-fin heat exchanger, a high-temperature tail gas inlet, a low-temperature tail gas outlet, an ammonia inlet, a wire trough, a high-temperature tail gas diversion zone, a low-temperature tail gas convergence zone, an ammonia diversion zone, and a fuel convergence zone. The tail gas inlet is connected to the first outlet pipeline and the second outlet pipeline. The high-temperature exhaust gas diversion zone is connected to the high-temperature exhaust gas inlet; the low-temperature exhaust gas confluence zone is connected to the low-temperature exhaust gas outlet; the ammonia gas diversion zone is connected to the ammonia gas inlet; and the fuel confluence zone is connected to the fuel distribution pipeline inlet and the anode first input pipeline inlet.

10. The integrated ammonia cracking device according to claim 9, characterized in that, The plate-fin heat exchanger uses corrugated fins and includes independent exhaust gas side channels and fuel side channels. The exhaust gas side channels and fuel side channels are separated by a thermally conductive baffle, and heat exchange occurs through the thermally conductive baffle. The high-temperature exhaust gas diversion zone and the low-temperature exhaust gas convergence zone are located on both sides of the exhaust gas side channels, and the flow direction of the exhaust gas side channels is set to horizontal. The ammonia gas diversion zone and the fuel convergence zone are located on both sides of the fuel side channels, and the flow direction of the fuel side channels is set to upward.

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