Solid oxide fuel cell tail gas heat energy gradient utilization treatment system

Abstract

The invention relates to the technical field of solid oxide fuel cells, in particular to a solid oxide fuel cell tail gas heat energy gradient utilization treatment system. Anode tail gas of a solid oxide fuel cell is divided into one part of anode tail gas and the other part of anode tail gas, the other part of anode tail gas is combusted to obtain combustion gas to preheat water in a water preheating system, and then the combustion gas obtained after heat exchange between the combustion gas and the water enters a fuel gas pretreatment system; a hydrocarbon fuel and water in a fuel gas conveying system are subjected to heat exchange to obtain mixed gas, the mixed gas and a part of anode tail gas are reformed to obtain reformed gas, the reformed gas is recycled and then subjected to heat exchange with a part of anode tail gas and combustion gas in the conveying process, then the reformed gas is conveyed to an anode, waste heat of the anode tail gas is recycled, and preheating of the fuel gas and water is achieved; the conversion utilization efficiency of hydrocarbon fuel is improved, the reforming gas is preheated by the anode tail gas and the combustion gas, the temperature of the reforming gas is gradually increased, and gradient utilization of waste heat of the high-temperature anode tail gas is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cells, and in particular to a solid oxide fuel cell tail gas thermal energy cascade utilization and processing system. Background Art

[0002] Solid oxide fuel cells (SOFCs) are fuel cells that use a solid oxide electrolyte and operate at high temperatures. They typically use a solid ceramic electrolyte such as yttria-stabilized zirconia. Their operating temperature ranges from 800°C to 1000°C.

[0003] Solid oxide fuel cells (SOFCs), known as the third generation of fuel cells, utilize a solid, porous metal oxide electrolyte, where oxygen ions shuttle through the electrolyte to transport ions. The technology has reached maturity, but because only a few materials can operate at high temperatures and are expensive, development is moving toward intermediate-temperature batteries.

[0004] The most suitable application of solid oxide fuel cells is to form a combined cycle power generation system with coal gasification and gas turbines, steam turbines, etc., to build central power stations or distributed energy stations. This can not only improve energy utilization but also reduce environmental pollution.

[0005] Solid oxide fuel cells produce exhaust gas during operation. The anode of the solid oxide fuel cell produces hydrogen, carbon monoxide, methane, water vapor or carbon dioxide, and the cathode produces oxygen, nitrogen and nitrogen oxides. Currently, in the process of treating these exhaust gases, combustion, catalytic treatment, adsorption, chemical solvent spraying and other treatment methods are generally used. Although they can reduce the impact of exhaust gas on the environment to a certain extent, they do not make reasonable use of the waste heat resources of the exhaust gas, resulting in waste of waste heat resources and heat energy loss. Summary of the Invention

[0006] In order to solve the above technical problems, an embodiment of the present invention provides a solid oxide fuel cell tail gas thermal energy cascade utilization and processing system.

[0007] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions: The present invention provides a solid oxide fuel cell tail gas thermal energy cascade utilization and processing system, comprising a solid oxide fuel cell, a water preheating system, an anode tail gas treatment system, a fuel gas delivery system, and a fuel gas pretreatment system. The solid oxide fuel cell is used to generate anode tail gas and cathode tail gas. The water preheating system is used to preheat water. The anode tail gas treatment system is connected to the solid oxide fuel cell and is used to receive the anode tail gas to separate the anode tail gas into a portion of anode tail gas and another portion of anode tail gas. The water preheating system is connected to the anode tail gas treatment system, and the anode tail gas treatment system processes the other portion of the anode tail gas to obtain combustion gas for heat exchange with the water preheating system. The fuel gas delivery system is connected to the anode tail gas treatment system and is used to receive hydrocarbon fuel and water. The fuel gas pretreatment system is respectively connected to the water preheating system and the fuel gas delivery system, and is used to receive the combustion gas after heat exchange in the water preheating system, so as to heat exchange the hydrocarbon fuel and water received by the fuel gas delivery system to obtain a mixed gas, and then merge it with a part of the anode tail gas in the anode tail gas treatment system and reform it to obtain reformed gas, which is then delivered to the anode of the solid oxide fuel cell after heat exchange with a part of the anode tail gas and the combustion gas.

[0008] Compared with the prior art, the beneficial effect of the present invention is that the present invention divides the anode tail gas of the solid oxide fuel cell into a part of the anode tail gas and another part of the anode tail gas through the anode tail gas treatment system, and the other part of the anode tail gas is burned to obtain combustion gas, and the water in the water preheating system is preheated to meet the user's water needs. Then, the combustion gas after heat exchange with water enters the fuel gas pretreatment system, and the hydrocarbon fuel and water in the fuel gas transmission system are heat exchanged. The hydrocarbon fuel and water are evaporated into a mixed gas, and a part of the anode tail gas is merged with the mixed gas and then reformed to obtain reformed gas, which is recycled and then heat exchanged with a part of the anode tail gas and combustion gas in the transmission process and then transported to the anode of the solid oxide fuel cell to achieve a step-by-step temperature increase of the reformed gas before entering the anode.

[0009] It should be further explained that the purpose of dividing the anode off-gas into a portion and another portion is to: A portion of the anode off-gas is not burned, and the waste heat of the anode off-gas is directly utilized to preheat the reformed gas. This is then recycled back into the anode of the solid oxide fuel cell to participate in the reaction, thereby improving the conversion efficiency of the fuel gas (hydrocarbon fuel and water). Simultaneously, the other portion of the anode off-gas is burned in the burner to further increase its calorific value. Subsequently, the reformed gas is passed through a second heat exchanger to achieve a secondary temperature increase, thereby maximizing the conversion efficiency of the fuel gas (hydrocarbon fuel and water). Simultaneously, to further utilize the waste heat of the other portion of the anode off-gas, the remaining waste heat of the combustion gas is used to heat cold water for heat users. The waste heat of the combustion gas is received by the fuel gas pretreatment system, and the hydrocarbon fuel and water are directly or indirectly initially heated to form a mixed gas. The mixed gas is then combined with a portion of the anode off-gas and reformed into reformed gas, repeating the cycle as described above. Through this process, the calorific value of the anode off-gas is fully utilized at each stage of its temperature decrease from high to low, thereby achieving cascaded utilization of waste heat from the off-gas.

[0010] That is, the present invention realizes preheating of fuel gas (hydrocarbon fuel and water) and user water by recycling the waste heat resources of the anode tail gas, which can improve the conversion and utilization efficiency of hydrocarbon fuels. By preheating the reformed gas with a part of the anode tail gas and the combustion gas, the temperature of the reformed gas is gradually increased, and the cascade utilization of the waste heat of the high-temperature anode tail gas is fully realized.

[0011] In some embodiments, the anode tail gas treatment system includes a splitter, a first heat exchanger, a combiner, a reformer, a burner, and a second heat exchanger. The splitter is used to receive the anode tail gas generated by the solid oxide fuel cell and to separate the anode tail gas into a portion of anode tail gas and another portion of anode tail gas. The first heat exchanger has a first inlet, a second inlet, a first outlet, and a second outlet. The first inlet of the first heat exchanger is used to receive a portion of the anode tail gas discharged from the splitter. The combiner is used to receive a portion of the anode tail gas discharged from the first outlet of the first heat exchanger and a mixed gas discharged from the fuel gas delivery system to merge the two to produce a combined gas. The reformer is used to receive the combined gas discharged from the combiner and to reform it in the reformer to produce reformed gas. The second inlet of the first heat exchanger is used to receive the reformed gas discharged from the reformer so that a portion of the anode tail gas preheats the reformed gas and discharges it through the second outlet of the first heat exchanger. The burner is used to receive the other portion of the anode tail gas discharged from the splitter and to burn it in the burner to produce combustion gas. The second heat exchanger has a first inlet, a second inlet, a first outlet and a second outlet. The first inlet of the second heat exchanger is used to receive the combustion gas discharged from the burner. The second inlet of the second heat exchanger is used to receive the reformed gas discharged from the second outlet of the first heat exchanger, so that the combustion gas preheats the reformed gas in the second heat exchanger. The second outlet of the second heat exchanger discharges the reformed gas into the anode of the solid oxide fuel cell. The water preheating system is used to receive the combustion gas discharged from the first outlet of the second heat exchanger.

[0012] In some embodiments, the water preheating system includes a water tank, a water pump, and a third heat exchanger. The water tank is used to store water. The water pump is used to receive water from the water tank. The third heat exchanger has a first inlet, a second inlet, a first outlet, and a second outlet. The second inlet of the third heat exchanger is used to receive the combustion gas discharged from the first outlet of the second heat exchanger, and the first inlet of the third heat exchanger is used to receive water pumped by the water pump, so that the water is preheated by the combustion gas in the third heat exchanger and then discharged to the user through the first outlet of the third heat exchanger. The fuel gas pretreatment system is used to receive the combustion gas discharged from the second outlet of the third heat exchanger after heat exchange.

[0013] In some embodiments, the water preheating system further includes a third solenoid valve and a third one-way valve. The inlet of the third solenoid valve is connected to the first outlet of the second heat exchanger, and the outlet of the third solenoid valve is connected to the second inlet of the third heat exchanger. The inlet of the third one-way valve is connected to the first outlet of the second heat exchanger. The fuel gas pretreatment system is configured to receive the heat-exchanged combustion gas discharged from the outlet of the third one-way valve, or to receive the heat-exchanged combustion gas discharged from the outlet of the third one-way valve and the heat-exchanged combustion gas discharged from the second outlet of the third heat exchanger.

[0014] In some embodiments, the fuel gas pretreatment system includes a cold molten salt storage tank, a cold molten salt pump, a first solenoid valve, a fourth heat exchanger, a first one-way valve, a hot molten salt storage tank, and a hot molten salt pump. The cold molten salt storage tank is used to store cold molten salt. The cold molten salt pump is used to receive the cold molten salt from the cold molten salt storage tank. The inlet of the first solenoid valve is used to receive the cold molten salt pumped in by the cold molten salt pump. The fourth heat exchanger has a first inlet, a first outlet, a second inlet, and a second outlet. The first inlet of the fourth heat exchanger is used to receive the cold molten salt discharged from the outlet of the first solenoid valve. The second inlet of the fourth heat exchanger is used to receive the combustion gas discharged after heat exchange at the outlet of the third one-way valve, or to receive the combustion gas discharged from the outlet of the third one-way valve and the combustion gas discharged from the second outlet of the third heat exchanger. The cold molten salt is preheated by the combustion gas in the fourth heat exchanger to produce hot molten salt, which is then discharged through the first outlet of the fourth heat exchanger. The combustion gas, after heat exchange with the cold molten salt, is discharged through the second outlet of the fourth heat exchanger. The first one-way valve is configured to receive the molten salt discharged from the first outlet of the fourth heat exchanger. The inlet of the molten salt storage tank is configured to receive the molten salt discharged from the outlet of the first one-way valve. The inlet of the molten salt pump is configured to receive the molten salt discharged from the outlet of the molten salt storage tank. The fuel gas delivery system is configured to receive the molten salt discharged from the outlet of the molten salt pump to preheat the hydrocarbon fuel and water to form a mixed gas.

[0015] In some embodiments, the fuel gas pretreatment system further includes a second solenoid valve, a solar thermal collector, and a second one-way valve. The inlet of the second solenoid valve is configured to receive cold molten salt discharged from the outlet of the cold molten salt pump. The inlet of the solar thermal collector is configured to receive cold molten salt discharged from the outlet of the second solenoid valve, thereby preheating the cold molten salt to produce hot molten salt. The inlet of the second one-way valve is configured to receive hot molten salt discharged from the outlet of the solar thermal collector, and the hot molten salt storage tank is configured to receive the hot molten salt discharged from the outlet of the second one-way valve.

[0016] In some embodiments, the fuel gas delivery system includes a fuel pump and an evaporator. The fuel pump is configured to receive the hydrocarbon fuel and water. The evaporator has a first inlet, a first outlet, a second inlet, and a second outlet. The second inlet of the evaporator is configured to receive the hydrocarbon fuel and water pumped in by the fuel pump. The first inlet of the evaporator is configured to receive the molten salt pumped in by the molten salt pump to preheat the hydrocarbon fuel and water and evaporate them to produce a mixed gas. The mixed gas is discharged into the combiner through the second outlet of the evaporator. The cold molten salt storage tank is configured to receive the cold molten salt discharged from the first outlet of the evaporator.

[0017] In some embodiments, a solid oxide fuel cell exhaust gas thermal energy cascade utilization and processing system further includes an air treatment system, wherein the air treatment system includes an air compressor, an air preheater and an electric heater. The inlet of the air compressor is used to compress the received air. The air preheater has a first inlet, a first outlet, a second inlet and a second outlet. The first inlet of the air preheater is used to receive the air compressed by the air compressor, the second inlet of the air preheater is used to receive the cathode exhaust gas to preheat the air and discharge it through the first outlet of the air preheater, and the second outlet of the air preheater is used to discharge the cathode exhaust gas after heat exchange. The inlet of the electric heater is used to receive the air discharged from the first outlet of the air preheater to heat it, and the outlet of the electric heater is used to discharge the heated air to the cathode of the solid oxide fuel cell.

[0018] In some embodiments, the fourth heat exchanger also has a third inlet and a third outlet. The third inlet of the fourth heat exchanger is used to receive the cathode exhaust gas discharged from the second outlet of the air preheater to preheat the cold molten salt, and the third outlet of the fourth heat exchanger is used to discharge the cathode exhaust gas after heat exchange. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a module structure of a solid oxide fuel cell tail gas thermal energy cascade utilization and processing system provided in an embodiment of the present application; Figure 2 This is another schematic diagram of the module structure of a solid oxide fuel cell tail gas thermal energy cascade utilization and processing system provided in an embodiment of the present application; Figure 3 This is another module structure schematic diagram of a solid oxide fuel cell exhaust heat energy cascade utilization and processing system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0020] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0021] In the description of this application, it should be understood that the terms "upper", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0022] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. Throughout this application, unless otherwise specified, "plurality" means two or more.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to direct connections, indirect connections through an intermediate medium, or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances. Example

[0024] In the embodiments of the present application, it should be noted that the connection can be direct or indirect. The two connected subsystems do not need to be in full contact. They can also be directly connected through pipelines. For example, the anode tail gas treatment system can be directly connected to the solid oxide fuel cell 1 through explosion-proof pipelines.

[0025] Furthermore, the inlets and outlets of devices or apparatuses can be connected directly or indirectly, and the two connected devices or apparatuses do not need to be in full contact. Alternatively, they can be directly connected via pipes. For example, the inlet of diverter 2 is connected to the anode exhaust gas outlet of solid oxide fuel cell 1 via explosion-proof piping. The connection of explosion-proof piping to the inlets and outlets of the corresponding devices or apparatuses, as well as requirements for connection sealing, are all state-of-the-art and are not specifically required in the present embodiments. These requirements may be determined based on actual needs or standards.

[0026] Unless otherwise specified, the devices or apparatuses used in the embodiments of the present application are conventional devices or apparatuses in the art.

[0027] like Figure 1As shown, the present invention provides a solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system, including a solid oxide fuel cell 1, a water preheating system, an anode tail gas treatment system, a fuel gas delivery system and a fuel gas pretreatment system. The solid oxide fuel cell 1 is used to generate anode tail gas and cathode tail gas, and the electric energy generated by the solid oxide fuel cell 1 is sent to the electricity user. The water preheating system is used to preheat water. The anode tail gas treatment system is connected to the solid oxide fuel cell 1 and is used to receive the anode tail gas to divide the anode tail gas into a part of the anode tail gas and another part of the anode tail gas. The water preheating system is connected to the anode tail gas treatment system, and the anode tail gas treatment system processes the other part of the anode tail gas to obtain combustion gas for heat exchange with the water preheating system. The fuel gas delivery system is connected to the anode tail gas treatment system and is used to receive hydrocarbon fuel and water. The fuel gas pretreatment system is connected to the water preheating system and the fuel gas delivery system respectively, and is used to receive the combustion gas after heat exchange in the water preheating system, so as to heat exchange the hydrocarbon fuel received by the fuel gas delivery system with water to obtain a mixed gas, and then merge it with a part of the anode tail gas in the anode tail gas treatment system and then reform it to obtain reformed gas, which is then delivered to the anode of the solid oxide fuel cell 1 after heat exchange with a part of the anode tail gas and the combustion gas.

[0028] Based on the above foundation, the present invention divides the solid oxide fuel cell anode tail gas into one part of anode tail gas and another part of anode tail gas through the anode tail gas treatment system. The other part of the anode tail gas is burned to obtain combustion gas, and the water in the water preheating system is preheated to meet the user's water needs. Then the combustion gas after heat exchange with water enters the fuel gas pretreatment system, and the hydrocarbon fuel and water in the fuel gas delivery system are heat exchanged. The hydrocarbon fuel and water are evaporated into a mixed gas. A part of the anode tail gas is merged with the mixed gas and then reformed to obtain reformed gas. It is recycled and then heat exchanged with a part of the anode tail gas and combustion gas in the delivery process and then delivered to the anode of the solid oxide fuel cell, so as to achieve a step-by-step temperature increase of the reformed gas before entering the anode.

[0029] It should be further explained that the purpose of dividing the anode off-gas into a portion and another portion is to: A portion of the anode off-gas is not burned, and the waste heat of the anode off-gas is directly used to preheat the reformed gas. This is then recycled back into the anode of the solid oxide fuel cell to participate in the reaction, thereby improving the conversion efficiency of the fuel gas. Meanwhile, the other portion of the off-gas is burned in the burner to further increase its calorific value. Subsequently, the reformed gas is passed through a second heat exchanger to achieve a secondary temperature increase, thereby maximizing the conversion efficiency of the fuel gas (hydrocarbon fuel and water). At the same time, to further utilize the waste heat resource of the other portion of the anode off-gas, the remaining waste heat of the combustion gas is used to heat cold water for heat users. The combustion gas then passes through a fuel gas pretreatment system to initially heat the hydrocarbon fuel and water at room temperature to form a mixed gas. This mixed gas is then combined with a portion of the anode off-gas and reformed into reformed gas, repeating the cycle above. Through this process, the calorific value of the anode off-gas is fully utilized at each stage of its temperature decrease from high to low, thereby achieving a cascaded utilization of the waste heat of the off-gas.

[0030] That is, the present invention realizes preheating of fuel gas (hydrocarbon fuel and water) and user water by recycling the waste heat resources of the anode tail gas, which can improve the conversion and utilization efficiency of hydrocarbon fuels. By preheating the reformed gas with a part of the anode tail gas and the combustion gas, the temperature of the reformed gas is gradually increased, and the cascade utilization of the waste heat of the high-temperature anode tail gas is fully realized.

[0031] In some embodiments, the anode tail gas treatment system includes a splitter 2, a first heat exchanger 3, a combiner 10, a reformer 9, a burner 4, and a second heat exchanger 5. The splitter 2 is used to receive the anode tail gas generated by the solid oxide fuel cell 1 to divide the anode tail gas into a portion of the anode tail gas and another portion of the anode tail gas. The first heat exchanger 3 has a first inlet, a second inlet, a first outlet, and a second outlet. The first inlet of the first heat exchanger 3 is used to receive a portion of the anode tail gas discharged from the splitter 2. The combiner 10 is used to receive the anode tail gas discharged from the first outlet of the first heat exchanger 3 and the mixed gas discharged from the fuel gas delivery system to merge to obtain a combined gas. The reformer 9 is used to receive the combined gas discharged from the combiner 10 to reform it in the reformer 9 to obtain a reformed gas. The second inlet of the first heat exchanger 3 is used to receive the reformed gas discharged from the reformer 9 to preheat the reformed gas with a portion of the anode tail gas and discharge it through the second outlet of the first heat exchanger 3. The burner 4 is used to receive another portion of the anode tail gas discharged from the splitter 2, and burn it in the burner 4 to obtain combustion gas. The second heat exchanger 5 has a first inlet, a second inlet, a first outlet, and a second outlet. The first inlet of the second heat exchanger 5 is used to receive the combustion gas discharged from the burner 4. The second inlet of the second heat exchanger 5 is used to receive the reformed gas discharged from the second outlet of the first heat exchanger 3, so that the combustion gas preheats the reformed gas in the second heat exchanger 5. The second outlet of the second heat exchanger 5 discharges the reformed gas into the anode of the solid oxide fuel cell 1. The water preheating system is used to receive the combustion gas discharged from the first outlet of the second heat exchanger 5.

[0032] Based on the above, the anode of the solid oxide fuel cell 1 produces an anode tail gas, the main components of which are hydrogen, carbon monoxide, methane, water vapor or carbon dioxide, etc., and the diversion of the diverter 2 forms a part of the anode tail gas and another part of the anode tail gas. The other part of the anode tail gas is burned in the burner 4 to obtain combustion gas, and the combustion gas mainly becomes water vapor, carbon dioxide, etc. The combustion gas enters the second heat exchanger 5 through the first inlet of the second heat exchanger 5, and a part of the anode tail gas enters the first heat exchanger 3 through the first inlet of the first heat exchanger 3, and then is discharged to the combiner 10 through the first outlet of the first heat exchanger 3 to merge with the mixed gas discharged from the fuel gas delivery system to obtain a combined gas. It is then reformed into reformed gas in the reformer 9, and the reformed gas undergoes heat exchange with a portion of the anode tail gas entering the first heat exchanger 3 to preheat the reformed gas. The preheated reformed gas is discharged through the second outlet of the first heat exchanger 3, and passes through the second inlet of the second heat exchanger 5 for heat exchange with the combustion gas. After the combustion gas has completed preheating the reformed gas, the reformed gas is discharged through the second outlet of the second heat exchanger 5 to the anode of the solid oxide fuel cell 1 to achieve the recycling of the waste heat resources of the anode tail gas.

[0033] In some embodiments, the water preheating system includes a water tank 8, a water pump 7, and a third heat exchanger 6. The water tank 8 is used to store water. The water pump 7 is used to receive water from the water tank 8. The third heat exchanger 6 has a first inlet, a second inlet, a first outlet, and a second outlet. The second inlet of the third heat exchanger 6 is used to receive the combustion gas discharged from the first outlet of the second heat exchanger 5, and the first inlet of the third heat exchanger 6 is used to receive water pumped into the water pump 7, so that the water is preheated by the combustion gas in the third heat exchanger 6 and then discharged to the user through the first outlet of the third heat exchanger 6. The fuel gas pretreatment system is used to receive the combustion gas discharged after heat exchange at the second outlet of the third heat exchanger 6.

[0034] Based on the above, the waste heat in the combustion gas exchanges heat with liquid water in the third heat exchanger 6 to preheat the liquid water and produce hot water for user use. The first inlet and second inlet of the first heat exchanger 3 are located on the same side of the first heat exchanger 3, and the first and second outlets of the first heat exchanger 3 are located on the other side of the first heat exchanger 3. The first inlet and second inlet of the second heat exchanger 5 are located on the same side of the second heat exchanger 5, and the first and second outlets of the second heat exchanger 5 are located on the other side of the second heat exchanger 5. The first inlet and second outlet of the third heat exchanger 6 are located on the same side of the third heat exchanger 6, and the first and second outlets of the third heat exchanger 6 are located on the other side of the third heat exchanger 6.

[0035] In some embodiments, as Figure 2 As shown, the water preheating system further includes a third solenoid valve 26 and a third one-way valve 27. The inlet of the third solenoid valve 26 is connected to the first outlet of the second heat exchanger 5, and the outlet of the third solenoid valve 26 is connected to the second inlet of the third heat exchanger 6. The inlet of the third one-way valve 27 is connected to the first outlet of the second heat exchanger 5. The fuel gas pretreatment system is configured to receive the heat-exchanged combustion gas discharged from the outlet of the third one-way valve 27 or to receive the heat-exchanged combustion gas discharged from both the outlet of the third one-way valve 27 and the second outlet of the third heat exchanger 6.

[0036] Based on the above, the third solenoid valve 26 is used to control whether the combustion gas discharged from the first outlet of the second heat exchanger 5 flows directly into the fuel gas pretreatment system through the third one-way valve 27 or the fuel gas flows into the fuel gas pretreatment system and the third heat exchanger 6 respectively.

[0037] In some embodiments, the fuel gas pretreatment system includes a cold molten salt storage tank 16, a cold molten salt pump 15, a first solenoid valve 18, a fourth heat exchanger 14, a first one-way valve 20, a hot molten salt storage tank 11, and a hot molten salt pump 12. The cold molten salt storage tank 16 is used to store cold molten salt. The cold molten salt pump 15 is used to receive cold molten salt from the cold molten salt storage tank 16. The inlet of the first solenoid valve 18 is used to receive cold molten salt pumped into the cold molten salt pump 15. The fourth heat exchanger 14 has a first inlet, a first outlet, a second inlet, and a second outlet. The first inlet of the fourth heat exchanger 14 is used to receive the cold molten salt discharged from the outlet of the first solenoid valve 18. The second inlet of the fourth heat exchanger 14 is used to receive the heat-exchanged combustion gas discharged from the outlet of the third one-way valve 27, or to receive the heat-exchanged combustion gas discharged from the outlet of the third one-way valve 27 and the heat-exchanged combustion gas discharged from the second outlet of the third heat exchanger 6. The cold molten salt is preheated by the combustion gas in the fourth heat exchanger 14 to produce hot molten salt, which is then discharged through the first outlet of the fourth heat exchanger 14. After heat exchange with the cold molten salt, the combustion gas is discharged through the second outlet of the fourth heat exchanger 14. The first one-way valve 20 is used to receive the hot molten salt discharged from the first outlet of the fourth heat exchanger 14. The inlet of the hot molten salt storage tank 11 is used to receive the hot molten salt discharged from the outlet of the first one-way valve 20. The inlet of the hot molten salt pump 12 is used to receive the hot molten salt discharged from the outlet of the hot molten salt storage tank 11. The fuel gas delivery system is used to receive the hot molten salt discharged from the outlet of the hot molten salt pump 12 to preheat the hydrocarbon fuel and water to form a mixed gas.

[0038] Based on the above, the first inlet and the second outlet of the fourth heat exchanger 14 are located on the same side of the fourth heat exchanger 14 , and the first outlet and the second inlet of the fourth heat exchanger 14 are located on the other side of the fourth heat exchanger 14 .

[0039] In some embodiments, the fuel gas pretreatment system further includes a second solenoid valve 17, a solar thermal collector 13, and a second one-way valve 19. The inlet of the second solenoid valve 17 is configured to receive cold molten salt discharged from the outlet of the cold molten salt pump 15. The inlet of the solar thermal collector 13 is configured to receive cold molten salt discharged from the outlet of the second solenoid valve 17 to preheat the cold molten salt to produce hot molten salt. The inlet of the second one-way valve 19 is configured to receive hot molten salt discharged from the outlet of the solar thermal collector 13. The hot molten salt storage tank 11 is configured to receive the hot molten salt discharged from the outlet of the second one-way valve 19.

[0040] In some embodiments, the fuel gas delivery system includes a fuel pump 22 and an evaporator 21. The fuel pump 22 is used to receive hydrocarbon fuel and water. The evaporator 21 has a first inlet, a first outlet, a second inlet, and a second outlet. The second inlet of the evaporator 21 is used to receive the hydrocarbon fuel and water pumped by the fuel pump 22. The first inlet of the evaporator 21 is used to receive molten salt pumped by the molten salt pump 12 to preheat the hydrocarbon fuel and water and evaporate them to produce a mixed gas. The mixed gas is discharged into the combiner 10 through the second outlet of the evaporator 21. The cold molten salt storage tank 16 is used to receive the cold molten salt discharged from the first outlet of the evaporator 21.

[0041] In some embodiments, a solid oxide fuel cell 1 tail gas thermal energy cascade utilization processing system also includes an air treatment system, and the air treatment system includes an air compressor 25, an air preheater 24 and an electric heater 23. The inlet of the air compressor 25 is used to compress the received air. The air preheater 24 has a first inlet, a first outlet, a second inlet and a second outlet. The first inlet of the air preheater 24 is used to receive the air compressed by the air compressor 25, and the second inlet of the air preheater 24 is used to receive the cathode tail gas to preheat the air and discharge it through the first outlet of the air preheater 24. The second outlet of the air preheater 24 is used to discharge the cathode tail gas after heat exchange. The inlet of the electric heater 23 is used to receive the air discharged from the first outlet of the air preheater 24 to heat it, and the outlet of the electric heater 23 is used to discharge the heated air to the cathode of the solid oxide fuel cell 1.

[0042] Based on the above, the electric heater 23 can be removed and an electric heating wire can be embedded in the air preheater 24.

[0043] In some embodiments, as Figure 3 As shown, the fourth heat exchanger 14 also has a third inlet and a third outlet. The third inlet of the fourth heat exchanger 14 is used to receive the cathode exhaust gas discharged from the second outlet of the air preheater 24 to preheat the cold molten salt. The third outlet of the fourth heat exchanger 14 is used to discharge the cathode exhaust gas after heat exchange.

[0044] Based on the above, the first inlet, second outlet and third outlet of the fourth heat exchanger 14 are located on the same side of the fourth heat exchanger 14 , and the first outlet, second inlet and third inlet of the fourth heat exchanger 14 are located on the other side of the fourth heat exchanger 14 .

[0045] Based on the embodiments of the present application, the specific operation process of the embodiments of the present application is further explained below.

[0046] When the solid oxide fuel cell 1 is started, no high temperature anode tail gas is generated. If the light is strong (i.e. the direct normal solar irradiance (DNI) is greater than 300W / m 2), open the second solenoid valve 17, and close the first solenoid valve 18. Cold molten salt (such as binary nitrate, ternary nitrate, etc., preferably binary nitrate) flows through the second solenoid valve 17 into the solar thermal collector 13. After absorbing heat, the cold molten salt becomes hot molten salt. The hot molten salt flows through the outlet of the solar thermal collector 13, through the second one-way valve 19, and then through the outlet of the second one-way valve 19 into the hot molten salt storage tank 11. The hot molten salt then flows through the outlet of the hot molten salt storage tank 11 and into the inlet of the hot molten salt pump 12. The hot molten salt is pumped by the hot molten salt pump 12 to the evaporator 21, where it fully exchanges heat with the hydrocarbon fuel and water mixture and becomes cold molten salt. Finally, the cold molten salt flows back to the cold molten salt storage tank 16 through the first outlet of the evaporator 21.

[0047] During the operation of the solid oxide battery, if the light is weak (i.e. the direct normal irradiance (DNI) of the sun is less than 300W / m 2 ) or in the absence of light, the second solenoid valve 17 closes and the first solenoid valve 18 opens. The molten salt pump 12 pumps the molten salt, pre-stored in the molten salt storage tank 11, into the evaporator 21. After sufficient heat exchange with the hydrocarbon fuel and water mixture, the resulting cold molten salt flows into the cold molten salt storage tank 16. After the solid oxide fuel cell 1 operates and generates high-temperature anode tail gas, the cold molten salt is pumped from the cold molten salt storage tank 16 into the first solenoid valve 18 via the cold molten salt pump 15. The cold molten salt then flows into the fourth heat exchanger 14, where it undergoes sufficient heat exchange with the combustion gas to become molten salt. The salt then flows into the molten salt storage tank 11 for recirculation and thermal utilization.

[0048] During the operation of the solid oxide battery, if the light is strong (i.e. the direct normal irradiance (DNI) of the sun is greater than 300W / m 2 ), and simultaneously open the first solenoid valve 18 and the second solenoid valve 17. At this point, the cold molten salt is divided into two parts: one part flows to the solar collector 13, where it becomes hot molten salt after heat exchange; the other part flows through the first solenoid valve 18 into the fourth heat exchanger 14, where it fully exchanges heat with the combustion gas and becomes hot molten salt. Subsequently, the hot molten salt flows through the first outlet of the fourth heat exchanger 14 and the inlet of the first one-way valve 20, then through the first one-way valve 20. In the pipeline between the outlet of the first one-way valve 20 and the inlet of the hot molten salt storage tank 11, it merges with the hot molten salt flowing from the direction of the second one-way valve 19 and enters the hot molten salt storage tank 11 through the inlet of the hot molten salt storage tank 11. The subsequent flow direction of the hot molten salt is the same as the flow direction of the hot molten salt after entering the hot molten salt storage tank 11 during startup of the solid oxide fuel cell 1. If the light is weak (i.e., the solar normal direct irradiance (DNI) is less than 300W / m 2 ) or when there is no light, second solenoid valve 17 is closed and first solenoid valve 18 is opened. Cold molten salt flows through the connecting pipeline between the outlet of first solenoid valve 18 and the first inlet of fourth heat exchanger 14, where it fully exchanges heat with the combustion gas. Its subsequent flow direction is the same as that of the cold molten salt flowing into fourth heat exchanger 14.

[0049] Based on the above foundation, the embodiment of the present application adopts a splitter 2 to divide the anode tail gas into a part of the anode tail gas and another part of the anode tail gas, wherein a part of the anode tail gas uses the contained high-temperature waste heat to preheat the reformed gas, and then returns to the combiner 10, and merges with the mixed gas after the evaporation of the hydrocarbon fuel and water mixture to form a combined gas, and then the combined gas enters the reformer 9 for further reforming into a reformed gas; the other part of the anode tail gas is guided to the burner 4, and after sufficient combustion to further increase the air flow temperature, it is fully exchanged with the reformed gas, thereby further increasing the temperature of the reformed gas when it enters the anode of the solid oxide fuel cell 1, so that it can not only improve the conversion and utilization efficiency of the hydrocarbon fuel, but also realize heat exchange through the first heat exchanger 3 and the second heat exchanger 5, gradually increase the reformed gas temperature, and fully realize the cascade utilization of the high-temperature anode tail gas waste heat.

[0050] In addition, the first solenoid valve 18, the second solenoid valve 17, the first one-way valve 20 and the second one-way valve 19 are combined, and the solar collector 13 and the fourth heat exchanger 14 are arranged in parallel between the cold molten salt storage tank 16 and the hot molten salt storage tank 11, and the cold molten salt pump 15 and the hot molten salt pump 12 are coordinated. Based on the calorific value required for the hydrocarbon fuel and water mixture to evaporate into a mixed gas, the sunshine conditions of the application scenario and the residual waste heat after the cascade utilization of the anode tail gas of the solid oxide fuel cell 1 are comprehensively considered. By controlling the opening and closing of the first solenoid valve 18 and the second solenoid valve 17, it is flexibly selected to use the solar collector 13 alone, the fourth heat exchanger 14 alone, or the solar collector 13 and the fourth heat exchanger 14 at the same time to circulate, heat and store the cold molten salt, thereby continuously and stably supplying heat energy for the hydrocarbon fuel and water mixture to evaporate into a mixed gas. Moreover, even under special operating conditions such as poor sunlight conditions and startup of the solid oxide fuel cell 1, the molten salt stored in the molten salt storage tank 11 can be circulated to provide reliable heat energy for the hydrocarbon fuel and water mixture, ensuring its smooth evaporation into a mixed gas.

[0051] The third solenoid valve 26 allows precise control of the flow direction of the combustion gas after heat exchange. When the residual calorific value of the combustion gas after heat exchange in the second heat exchanger 5 is less than the calorific value of the cold molten salt, the system opens the third solenoid valve 26 and simultaneously closes the first solenoid valve 18, allowing the combustion gas to exchange heat with liquid water before being delivered to the heat user. The cold molten salt is then heat-exchanged only through the solar collector 13, preventing it from exchanging heat with the low-calorific-value combustion gas in the fourth heat exchanger 14, thereby preventing energy and heat loss.

[0052] When the residual calorific value of the combustion gas after heat exchange in the second heat exchanger 5 exceeds the calorific value of the cold molten salt, the system closes the third solenoid valve 26, allowing the combustion gas to pass through the third one-way valve 27 and enter the fourth heat exchanger 14 for heat exchange with the cold molten salt. This effectively raises the temperature of the cold molten salt and transfers heat energy to the hydrocarbon fuel-water mixture, thereby ensuring efficient evaporation of the hydrocarbon fuel-water mixture. If the residual calorific value of the combustion gas after heat exchange with the cold molten salt in the fourth heat exchanger 14 is still sufficient to heat liquid water, the third solenoid valve 26 can be opened before heat exchange with the cold molten salt to heat the liquid water.

[0053] In this way, the present invention achieves the maximum cascade utilization of the residual heat of the anode tail gas while giving priority to ensuring the thermal energy demand of the solid oxide fuel cell 1, thereby significantly improving the energy utilization efficiency of the system.

[0054] Furthermore, by connecting the second outlet of the air preheater 24 to the third inlet of the fourth heat exchanger 14, the residual heat energy of the cathode exhaust gas, after its initial heat exchange with the air, can undergo a secondary heat exchange with the cold molten salt. This fully utilizes the residual heat of the cathode exhaust gas, ensuring the cascaded and maximized utilization of the residual heat and significantly improving the energy efficiency of the entire system.

[0055] In summary, the present embodiment divides the anode tail gas into two parts: one portion undergoes heat exchange with the mixed gas before being reformed in the reformer 9. The resulting reformed gas is then heat exchanged with a subsequent portion of the anode tail gas and the combustion gas from another portion of the anode tail gas. This not only improves the conversion and utilization rate of hydrocarbon fuels, but also fully realizes the cascaded utilization of the high-temperature waste heat of the anode tail gas.

[0056] The molten salt is heated, stored, and recycled using the waste heat from the combustion gas, maximizing the utilization of the waste heat from the high-temperature anode tail gas. Furthermore, the parallel configuration of the solar collector 13 and the fourth heat exchanger 14 allows for flexible adaptation to different application scenarios, ensuring sufficient heat energy is provided to the evaporator 21, significantly improving the system's thermal efficiency and adaptability.

[0057] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0058] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system, characterized in that: include: Solid oxide fuel cells for generating anode tail gas and cathode tail gas; A water preheating system, used for preheating water; an anode tail gas treatment system connected to the solid oxide fuel cell and configured to receive the anode tail gas and separate the anode tail gas into a portion of anode tail gas and another portion of anode tail gas, wherein the water preheating system is connected to the anode tail gas treatment system, and the anode tail gas treatment system processes the other portion of anode tail gas to obtain combustion gas for heat exchange with the water preheating system; A fuel gas delivery system, connected to the anode tail gas treatment system, for receiving hydrocarbon fuel and water; The fuel gas pretreatment system is connected to the water preheating system and the fuel gas delivery system respectively, and is used to receive the combustion gas after heat exchange in the water preheating system, so as to heat exchange the hydrocarbon fuel received by the fuel gas delivery system with water to obtain a mixed gas, and then merge it with a part of the anode tail gas in the anode tail gas treatment system and reform it to obtain reformed gas, which is then delivered to the anode of the solid oxide fuel cell after heat exchange with a part of the anode tail gas and the combustion gas.

2. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to claim 1, characterized in that: The anode tail gas treatment system includes: a splitter for receiving the anode tail gas generated by the solid oxide fuel cell to divide the anode tail gas into a portion of anode tail gas and another portion of anode tail gas; a first heat exchanger having a first inlet, a second inlet, a first outlet, and a second outlet, wherein the first inlet of the first heat exchanger is used to receive a portion of the anode tail gas discharged by the splitter; a combiner for receiving a portion of the anode tail gas discharged from the first outlet of the first heat exchanger and the mixed gas discharged from the fuel gas delivery system to merge them to obtain a combined gas; a reformer for receiving the combined gas discharged from the combiner and reforming it in the reformer to obtain a reformed gas, wherein the second inlet of the first heat exchanger is used to receive the reformed gas discharged from the reformer, so that a portion of the anode tail gas preheats the reformed gas and discharges the reformed gas through the second outlet of the first heat exchanger; a burner, configured to receive another portion of the anode tail gas discharged from the splitter and burn it in the burner to obtain combustion gas; The second heat exchanger has a first inlet, a second inlet, a first outlet and a second outlet. The first inlet of the second heat exchanger is used to receive the combustion gas discharged from the burner. The second inlet of the second heat exchanger is used to receive the reformed gas discharged from the second outlet of the first heat exchanger, so that the combustion gas preheats the reformed gas in the second heat exchanger. The second outlet of the second heat exchanger discharges the reformed gas into the anode of the solid oxide fuel cell. The water preheating system is used to receive the combustion gas discharged from the first outlet of the second heat exchanger.

3. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to claim 2, characterized in that: The water preheating system comprises: Water tank, used to store water; a water pump, configured to receive water from the water tank; The third heat exchanger has a first inlet, a second inlet, a first outlet and a second outlet. The second inlet of the third heat exchanger is used to receive the combustion gas discharged from the first outlet of the second heat exchanger. The first inlet of the third heat exchanger is used to receive water pumped into by the water pump, so that the water is preheated by the combustion gas in the third heat exchanger and then discharged to the user through the first outlet of the third heat exchanger. The fuel gas pretreatment system is used to receive the combustion gas after heat exchange discharged from the second outlet of the third heat exchanger.

4. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to claim 3, characterized in that: The water preheating system also includes: a third solenoid valve, wherein the inlet of the third solenoid valve is connected to the first outlet of the second heat exchanger, and the outlet of the third solenoid valve is connected to the second inlet of the third heat exchanger; A third one-way valve, the inlet of the third one-way valve is connected to the first outlet of the second heat exchanger, and the fuel gas pretreatment system is used to receive the combustion gas after heat exchange discharged from the outlet of the third one-way valve or to receive the combustion gas after heat exchange discharged from the outlet of the third one-way valve and the combustion gas after heat exchange discharged from the second outlet of the third heat exchanger.

5. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to claim 4, characterized in that: The fuel gas pretreatment system comprises: Cold molten salt storage tank, used for storing cold molten salt; A cold molten salt pump, configured to receive the cold molten salt in the cold molten salt storage tank; a first solenoid valve, wherein an inlet of the first solenoid valve is used to receive the cold molten salt pumped in by the cold molten salt pump; a fourth heat exchanger having a first inlet, a first outlet, a second inlet, and a second outlet, wherein the first inlet of the fourth heat exchanger is used to receive the cold molten salt discharged from the outlet of the first solenoid valve, and the second inlet of the fourth heat exchanger is used to receive the combustion gas discharged from the outlet of the third one-way valve after heat exchange, or to receive the combustion gas discharged from the outlet of the third one-way valve after heat exchange and the combustion gas discharged from the second outlet of the third heat exchanger after heat exchange. The cold molten salt is preheated by the combustion gas in the fourth heat exchanger to obtain hot molten salt, and is discharged through the first outlet of the fourth heat exchanger. The combustion gas is discharged through the second outlet of the fourth heat exchanger after heat exchange with the cold molten salt. a first one-way valve, the first one-way valve being used to receive the hot molten salt discharged from the first outlet of the fourth heat exchanger; a molten salt storage tank, wherein the inlet of the molten salt storage tank is used to receive the molten salt discharged from the outlet of the first one-way valve; A molten salt pump, the inlet of the molten salt pump is used to receive the molten salt discharged from the outlet of the molten salt storage tank, and the fuel gas delivery system is used to receive the molten salt discharged from the outlet of the molten salt pump to preheat the hydrocarbon fuel and water to form a mixed gas.

6. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to claim 5, characterized in that: The fuel gas pretreatment system further comprises: a second solenoid valve, wherein the inlet of the second solenoid valve is used to receive the cold molten salt discharged from the outlet of the cold molten salt pump; a solar thermal collector, wherein the inlet of the solar thermal collector is used to receive the cold molten salt discharged from the outlet of the second solenoid valve to preheat the cold molten salt to obtain hot molten salt; A second one-way valve, the inlet of the second one-way valve is used to receive the hot molten salt discharged from the outlet of the solar collector, and the hot molten salt storage tank is used to receive the hot molten salt discharged from the outlet of the second one-way valve.

7. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to claim 6, characterized in that: The fuel gas delivery system comprises: a fuel pump, configured to receive the hydrocarbon fuel and water; The evaporator has a first inlet, a first outlet, a second inlet and a second outlet. The second inlet of the evaporator is used to receive the hydrocarbon fuel and water pumped by the fuel pump. The first inlet of the evaporator is used to receive the hot molten salt pumped by the hot molten salt pump to preheat the hydrocarbon fuel and water and evaporate them to obtain a mixed gas. The mixed gas is discharged into the combiner through the second outlet of the evaporator. The cold molten salt storage tank is used to receive the cold molten salt discharged from the first outlet of the evaporator.

8. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to any one of claims 5 to 7, characterized in that: Also includes: An air handling system, comprising: an air compressor, wherein the inlet of the air compressor is used to compress the received air; an air preheater having a first inlet, a first outlet, a second inlet, and a second outlet, wherein the first inlet of the air preheater is used to receive the air compressed by the air compressor, the second inlet of the air preheater is used to receive the cathode exhaust gas to preheat the air and discharge it through the first outlet of the air preheater, and the second outlet of the air preheater is used to discharge the cathode exhaust gas after heat exchange; An electric heater, wherein the inlet of the electric heater is used to receive the air discharged from the first outlet of the air preheater to heat the air, and the outlet of the electric heater is used to discharge the heated air to the cathode of the solid oxide fuel cell.

9. A solid oxide fuel cell tail gas thermal energy cascade utilization and treatment system according to claim 8, characterized in that: The fourth heat exchanger also has a third inlet and a third outlet. The third inlet of the fourth heat exchanger is used to receive the cathode exhaust gas discharged from the second outlet of the air preheater to preheat the cold molten salt. The third outlet of the fourth heat exchanger is used to discharge the cathode exhaust gas after heat exchange.

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