Methane gradient utilization system based on SOFC (solid oxide fuel cell) and copper-chlorine circulation

Abstract

The invention relates to the technical field of energy systems, in particular to a methane gradient utilization system based on SOFC (solid oxide fuel cell) and copper chloride circulation, comprising a methane reforming and SOFC power generation unit for converting methane fuel into electric energy and combusting anode tail gas to generate high-temperature flue gas; the copper-chlorine circulating hydrogen production unit is connected with a high-temperature flue gas pipeline of the methane reforming and SOFC power generation unit, heat energy of the high-temperature flue gas is used for driving a copper-chlorine thermochemical circulating reaction, and hydrogen is prepared by taking water as a raw material; and the waste heat power generation and recovery unit is connected with a cathode tail gas pipeline of the methane reforming and SOFC power generation unit and a tail gas outlet pipeline of the copper chloride circulation hydrogen production unit, and is used for carrying out power generation and heat supply on waste heat in a cascade recovery system. According to the system, grade alignment and gradient utilization of energy are achieved, high-temperature waste gas of the SOFC system is sequentially used for driving copper-chlorine hydrogen production, ORC power generation and hot water supply, and the comprehensive utilization efficiency of energy is remarkably improved.

Description

Technical Field

[0001] This application relates to the field of energy system technology, and in particular to a methane cascade utilization system based on SOFC and copper-chlorine cycle. Background Technology

[0002] Solid oxide fuel cells (SOFCs), as highly efficient energy conversion devices, can directly convert the chemical energy of fuel into electrical energy. Methane-fueled SOFC systems typically integrate steam reforming processes, but their high-temperature exhaust gases (including anode and cathode exhaust gases) contain a significant amount of underutilized energy. Specifically, the anode exhaust gas contains unreacted fuel components (such as H2 and CO), whose chemical energy is not effectively recovered. Simultaneously, the high-quality sensible heat carried by the exhaust gas is often only partially utilized or directly emitted, resulting in a need to improve the overall energy efficiency of the system. Existing waste heat recovery technologies, such as the Organic Rankine Cycle (ORC), can recover some low- and medium-temperature heat energy for power generation, but their function is limited, failing to achieve co-production of high-value-added products and failing to solve the problem of recovering the chemical energy from the anode exhaust gas.

[0003] On the other hand, copper-chlorine (Cu-Cl) thermochemical cycle hydrogen production is a highly promising low-carbon hydrogen production technology, but its large-scale application is limited by the high cost of external heating. If the high-temperature, high-quality exhaust gas generated by SOFC systems can be used as a heat source for the Cu-Cl cycle, then the energy can be utilized effectively and costs can be balanced.

[0004] Therefore, there is an urgent need in this field for an innovative system that can effectively integrate power generation, hydrogen production, and waste heat recovery to achieve cascaded energy utilization and diversified product output. Summary of the Invention

[0005] Therefore, it is necessary to provide a methane cascade utilization system based on SOFC and copper-chlorine cycle to solve the problems of low comprehensive energy utilization efficiency, lack of deep cascade utilization of tail gas energy, single system function, and high cost of independent hydrogen production system in existing methane SOFC power generation systems.

[0006] A methane cascade utilization system based on SOFC and copper-chlorine cycle includes: The methane reforming and SOFC power generation unit is used to convert methane fuel into electrical energy and generate high-temperature flue gas by burning the anode tail gas. The copper-chlorine cycle hydrogen production unit is connected to the high-temperature flue gas pipeline of the methane reforming and SOFC power generation unit. The thermal energy of the high-temperature flue gas is used to drive the copper-chlorine thermochemical cycle reaction to produce hydrogen from water. The waste heat power generation and recovery unit is connected to the cathode tail gas pipeline of the methane reforming and SOFC power generation unit and the tail gas outlet pipeline of the copper chlorine cycle hydrogen production unit, and is used to generate electricity and provide heat from the waste heat in the cascade recovery system.

[0007] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the methane reforming and SOFC power generation unit includes a methane compressor, a steam compressor, a mixer, a fuel preheater, a reformer, a solid oxide fuel cell, a burner, a first air compressor, a second air compressor, and an air preheater. The outlets of the methane compressor and the steam compressor are respectively connected to the inlet of the mixer. The outlet of the mixer is connected to the reactant inlet of the reformer via a fuel preheater. The syngas outlet of the reformer is connected to the anode inlet of the solid oxide fuel cell. The outlet of the second air compressor is connected to the cathode inlet of the solid oxide fuel cell via an air preheater; The anode outlet of the solid oxide fuel cell is connected to the fuel inlet of the burner, the outlet of the first air compressor is connected to the air inlet of the burner, and the high-temperature flue gas outlet of the burner is connected in sequence to the heating channel of the reformer and the heating channel of the fuel preheater, and then leads to the copper chlorine cycle hydrogen production unit.

[0008] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the cathode outlet of the solid oxide fuel cell is connected to the heating side inlet of the air preheater, and the heating side outlet of the air preheater is connected to the waste heat power generation and recovery unit.

[0009] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the operating temperature of the reformer is 650-750℃.

[0010] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the copper-chlorine cycle hydrogen production unit includes a hydrolysis reactor, a separator, a second heater, a pyrolysis reactor gas separator, an electrolysis reactor, a drying heat exchanger, and a first heater. The heating side of the hydrolysis reactor is connected to the high-temperature flue gas pipeline from the methane reforming and SOFC power generation unit. Its solid phase inlet is used to introduce solid CuCl2, its gas phase inlet is used to introduce water vapor, and its outlet is connected to the inlet of the separator. The solid phase outlet of the separator is connected to the inlet of the pyrolysis reactor via a second heater; the gas phase outlet of the pyrolysis reactor is connected to the inlet of the gas separator, the oxygen outlet of the gas separator is open to the atmosphere, and its solid phase outlet is connected to the first inlet of the electrolysis reactor via a cooling pipe. The gas phase outlet of the separator is connected to the second inlet of the electrolytic reactor via a cooling pipeline; The hydrogen outlet of the electrolysis reactor is connected to a hydrogen storage device, and its solution outlet is connected to the solid inlet of the hydrolysis reactor via a drying heat exchanger and a first heater.

[0011] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the copper-chlorine cycle hydrogen production unit further includes an ammonia heat pump circuit, which includes a heat exchanger, an ammonia compressor, and a throttling valve. The heat exchanger’s heating side is connected in series in the cooling pipe between the gas phase outlet of the separator and the electrolysis reactor, and its cooling side is connected to the ammonia heat pump circuit. The inlet of the ammonia compressor is connected to the cooling side outlet of the heat exchanger, and its outlet is connected to the heating side inlet of the dryer heat exchanger. The heating side outlet of the dryer heat exchanger is connected to the cooling side inlet of the regenerative heat exchanger via a throttling valve.

[0012] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the heating side of the pyrolysis reactor, the heating side of the second heater, and the heating side of the first heater are all connected to the high-temperature flue gas pipeline from the methane reforming and SOFC power generation unit.

[0013] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the waste heat power generation and recovery unit includes an air turbine, a first waste heat exchanger, a third waste heat exchanger, a fourth waste heat exchanger, and an organic Rankine cycle power generation system. The air turbine inlet is connected to the cathode tail gas pipeline of the methane reforming and SOFC power generation unit, and its outlet is connected to the heating side of the first waste heat exchanger. The heating side of the third waste heat exchanger is connected to the tail gas pipeline from the copper-chlorine cycle hydrogen production unit, and its cooling side is connected to the cooling side outlet of the first waste heat exchanger; the heating side of the fourth waste heat exchanger is connected to the heating side outlet of the third waste heat exchanger, and its cooling side is connected to the organic Rankine cycle power generation system.

[0014] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper chlorine cycle described in this invention, the organic Rankine cycle power generation system includes a turbine, a regenerator, a fourth condenser, and a pump. The turbine inlet is connected to the cooling side outlet of the fourth waste heat exchanger, and its outlet is connected to the heating side inlet of the regenerator. The heat supply side outlet of the regenerator is connected to the pump inlet via the fourth condenser; The pump outlet is connected to the cooling side inlet of the regenerator, and the cooling side outlet of the regenerator is connected to the cooling side inlet of the fourth waste heat exchanger.

[0015] As a preferred embodiment of the methane cascade utilization system based on SOFC and copper-chlorine cycle described in this invention, the working fluid used in the organic Rankine cycle electron generating system is R123.

[0016] The beneficial effects of this invention are: This invention achieves energy grade matching and cascade utilization, sequentially using the high-temperature waste gas from the SOFC system to drive copper-chlorine hydrogen production, ORC power generation, and hot water supply, significantly improving the overall energy utilization efficiency; it integrates multiple functions such as power generation, hydrogen production, and heating into one unit, forming diversified product output, enhancing the system's economy and application flexibility; it provides a stable and low-cost heat source for the copper-chlorine hydrogen production system, reducing hydrogen production costs and promoting the development and application of this technology. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the system structure according to an embodiment of this application; Explanation of reference numerals in the attached figures: 1. Methane compressor; 2. Steam compressor; 3. Mixer; 4. Fuel preheater; 5. Reformer; 6. Solid oxide fuel cell; 7. Combustor; 8. First air compressor; 9. Second air compressor; 10. Air preheater; 11. Air turbine; 12. First waste heat exchanger; 13. Pyrolysis reactor; 14. Gas separator; 15. Oxygen condenser; 16. First condenser; 17. Humidifier; 18. Second condenser; 19. 20. Electrolysis reactor; 21. Four-stage compressor; 22. Hydrogen storage tank; 23. Drying heat exchanger; 24. First heater; 25. Hydrolysis reactor; 26. Separator; 27. Second heater; 28. Heat exchanger; 29. ​​Ammonia compressor; 30. Throttling valve; 31. Third condenser; 32. Second waste heat exchanger; 33. Third waste heat exchanger; 34. Fourth waste heat exchanger; 35. Turbine; 36. Pump; 37. Fourth condenser; 38. Regenerator. Detailed Implementation

[0019] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0020] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0021] Furthermore, 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0022] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0023] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0024] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0025] According to one aspect of this application, embodiments of this application provide a methane cascade utilization system based on SOFC and copper-chlorine cycle. Please refer to [link to relevant documentation]. Figure 1 The methane cascade utilization system based on SOFC and copper-chlorine cycle includes a methane reforming and SOFC power generation unit, a chlorine cycle hydrogen production unit, and a waste heat power generation and recovery unit. The methane reforming and SOFC power generation unit converts methane fuel into electrical energy and generates high-temperature flue gas by burning the anode tail gas. The chlorine cycle hydrogen production unit is connected to the high-temperature flue gas pipeline of the methane reforming and SOFC power generation unit, and uses the heat energy of the high-temperature flue gas to drive the copper-chlorine thermochemical cycle reaction to produce hydrogen from water. The waste heat power generation and recovery unit is connected to the cathode tail gas pipeline of the methane reforming and SOFC power generation unit and the tail gas outlet pipeline of the copper-chlorine cycle hydrogen production unit, and uses the waste heat in the cascade recovery system for power generation and heating.

[0026] In this embodiment, the methane cascade utilization system based on SOFC and copper-chlorine cycle includes a methane reforming and SOFC power generation unit, a chlorine cycle hydrogen production unit, and a waste heat power generation and recovery unit. The methane reforming and SOFC power generation unit generates electricity through reforming and electrochemical reactions, and produces high-temperature flue gas. The copper-chlorine cycle hydrogen production unit uses the heat energy of the high-temperature flue gas to drive the copper-chlorine thermochemical cycle reaction to produce hydrogen. The waste heat power generation and recovery unit recovers waste heat in the cascade system for power generation and heating.

[0027] In one embodiment, the methane reforming and SOFC power generation unit includes a methane compressor 1, a steam compressor 2, a mixer 3, a fuel preheater 4, a reformer 5, a solid oxide fuel cell 6, a burner 7, a first air compressor 8, a second air compressor 9, and an air preheater 10. The outlets of the methane compressor 1 and the steam compressor 2 are connected to the inlet of the mixer 3, respectively. The outlet of the mixer 3 is connected to the reactant inlet of the reformer 5 via the fuel preheater 4. The syngas outlet of the reformer 5 is connected to the anode inlet of the solid oxide fuel cell 6. The outlet of the second air compressor 9 is connected to the cathode inlet of the solid oxide fuel cell 6 via the air preheater 10. The anode outlet of the solid oxide fuel cell 6 is connected to the fuel inlet of the burner 7. The outlet of the first air compressor 8 is connected to the air inlet of the burner 7. The high-temperature flue gas outlet of the burner 7 is sequentially connected to the heating channel of the reformer 5 and the heating channel of the fuel preheater 4, and then leads to the copper-chlorine cycle hydrogen production unit.

[0028] In one embodiment, the cathode outlet of the solid oxide fuel cell 6 is connected to the heating side inlet of the air preheater 10, and the heating side outlet of the air preheater 10 is connected to the waste heat power generation and recovery unit. The exhaust gas discharged from the cathode of the solid oxide fuel cell 6, which still has a high temperature of 600-700°C, is primarily used to flow through the heating side of the air preheater 10 to heat the air that is about to enter the cathode of the solid oxide fuel cell 6. After completing the task of preheating the air, this initially cooled cathode exhaust gas is then directed to the waste heat power generation and recovery unit for further utilization. Using the high-temperature cathode exhaust gas to preheat the inlet air reduces the external energy input required to heat the air to the operating temperature, thereby reducing the system's self-consumption and improving the net efficiency of the SOFC power generation unit and even the entire system.

[0029] In one embodiment, the operating temperature of the reformer 5 is 650-750°C. The methane steam reforming reaction is a strongly endothermic reaction, and its reaction rate, methane conversion rate, and the proportion of product syngas are highly dependent on temperature. Within this temperature range, it can be ensured that the reforming reaction can proceed at a sufficiently high rate and conversion rate, while avoiding damage to the catalyst and reactor materials due to excessively high temperatures, or triggering unnecessary side reactions. At the same time, this temperature range is matched with the grade of the high-temperature flue gas from the burner 7. After the flue gas is heated by the reforming reaction at this temperature, the temperature will drop to a reasonable level for the next stage of energy utilization.

[0030] Methane fuel is first pressurized to 0.5-2.0 MPa by methane compressor 1, while steam is simultaneously pressurized to the same pressure level by steam compressor 2. The pressurized methane and steam then enter mixer 3 for thorough mixing, forming a methane-steam mixture with a water-to-carbon ratio controlled at 2.5-3.5. This mixture then enters fuel preheater 4, where it is heated to 300-400°C before being sent to reformer 5. Reformer 5 conducts a methane steam reforming reaction at an operating temperature of 700°C, with the reaction equation: CH4 + 2H2O → CO2 + 4H2, generating syngas rich in hydrogen and carbon monoxide. This syngas enters the anode side of solid oxide fuel cell 6. Meanwhile, ambient air is pressurized to 0.3-0.8 MPa by the second air compressor 9, then enters the air preheater 10 and is heated to 600-700°C. Finally, it is introduced into the cathode side of the solid oxide fuel cell 6. Inside the solid oxide fuel cell 6, the synthesis gas at the anode and the oxygen at the cathode undergo an electrochemical reaction to generate electricity, and the operating temperature is maintained at 750-850°C. The anode exhaust gas after the reaction enters the burner 7, which contains 15-25% unreacted fuel. It mixes with pressurized air from the first air compressor 8 and is completely combusted, producing high-temperature flue gas at 800-950°C. This high-temperature flue gas first flows through the heating channel of the reformer 5 to provide the necessary heat for the reforming reaction, and the flue gas temperature drops to 700-800°C. Then it enters the heating channel of the fuel preheater 4 to preheat the methane-steam mixture to the required temperature, and the flue gas temperature drops further to 600-700°C. Finally, this part of the flue gas, which still has a relatively high grade, is sent to the copper chlorine cycle hydrogen production unit as the main heat source. The cathode exhaust gas discharged from the solid oxide fuel cell 6 has a temperature of about 800-900°C. It first enters the heating side of the air preheater 10 to preheat the air entering the cathode to the required temperature, and then is sent to the waste heat power generation and recovery unit.

[0031] In one embodiment, the copper-chlorine cycle hydrogen production unit includes a hydrolysis reactor 24, a separator 25, a second heater 26, a pyrolysis reactor 13, a gas separator 14, an electrolysis reactor 19, a drying heat exchanger 22, and a first heater 23. The heating side of the hydrolysis reactor 24 is connected to a high-temperature flue gas pipeline from a methane reforming and SOFC power generation unit. Its solid phase inlet is used to introduce solid CuCl2, its gas phase inlet is used to introduce water vapor, and its outlet is connected to the inlet of the separator 25. The solid phase outlet of the separator 25 is connected to the inlet of the pyrolysis reactor 13 via the second heater 26. The gas phase outlet of the pyrolysis reactor 13 is connected to the inlet of the gas separator 14. The oxygen outlet of the gas separator 14 is open to the atmosphere, and its solid phase outlet is connected to the first inlet of the electrolysis reactor 19 via a cooling pipeline. The gas phase outlet of the separator 25 is connected to the second inlet of the electrolysis reactor 19 via a cooling pipeline. The hydrogen outlet of the electrolysis reactor 19 is connected to a hydrogen storage device, and its solution outlet is connected to the solid phase inlet of the hydrolysis reactor 24 via the drying heat exchanger 22 and the first heater 23.

[0032] In one embodiment, the copper-chlorine cycle hydrogen production unit further includes an ammonia heat pump circuit, which includes a heat exchanger 27, an ammonia compressor 28, and a throttling valve 29. The heating side of the heat exchanger 27 is connected in series on the cooling pipeline between the gas phase outlet of the separator 25 and the electrolysis reactor 19, and its cooling side is connected to the ammonia heat pump circuit. The inlet of the ammonia compressor 28 is connected to the cooling side outlet of the heat exchanger 27, and its outlet is connected to the heating side inlet of the dry heat exchanger 22. The heating side outlet of the dry heat exchanger 22 is connected to the cooling side inlet of the regenerative heat exchanger 27 via the throttling valve 29.

[0033] In one embodiment, the heating side of the pyrolysis reactor 13, the heating side of the first heater 23, and the heating side of the first heater 23 are all connected to the high-temperature flue gas pipeline from the methane reforming and SOFC power generation unit. The methane reforming and SOFC power generation unit is the pyrolysis reactor 13. The pyrolysis reactor 13 and the first heater 23 are the three heating devices in this system that require all the heat. The copper-chlorine cycle hydrogen production unit does not require any independent external heat source. The medium and high temperature heat required by it is completely met by the "waste heat" of the methane reforming and SOFC power generation unit, so as to reduce the cost of hydrogen production.

[0034] The high-temperature flue gas from the methane reforming and SOFC power generation unit provides all the thermal energy for the copper-chlorine cycle hydrogen production unit. The specific process flow is as follows: In the hydrolysis reactor 24, solid CuCl2 reacts with excess water vapor at 400-450℃ to undergo a hydrolysis reaction: 2CuCl2 + H2O → Cu2OCl2 + HCl, producing solid Cu2OCl2 and a mixed gas of HCl and H2O. The reaction products enter the separator 25 for gas-solid separation. The separated solid Cu2OCl2 enters the second heater 26, where it is heated to 500-550℃ by high-temperature flue gas and then sent to the pyrolysis reactor 13 to undergo a thermal decomposition reaction: Cu2OCl2 → 2CuCl + ½O2, producing CuCl and oxygen. The resulting gas mixture enters gas separator 14. The separated oxygen is cooled to ambient temperature by oxygen condenser 15 and then discharged from the system. The separated solid CuCl is cooled to 80-100℃ by first condenser 16, and water is added in humidifier 17 to form CuCl aqueous solution. It is then cooled to 50-70℃ by second condenser 18 and sent to electrolysis reactor 19. The HCl and H2O mixture separated from separator 25 first enters heat exchanger 27 and is cooled to 80-100℃ by ammonia heat pump circuit. The working process of ammonia heat pump circuit is as follows: liquid ammonia in heat exchanger 27... In step 7, evaporation absorbs heat to form ammonia vapor. The ammonia vapor is compressed to 8.0-10.0 MPa by ammonia compressor 28 and then enters the drying heat exchanger 22 for condensation and heat release. The condensed high-pressure liquid ammonia is depressurized by throttling valve 29 and returns to heat exchanger 27, completing the refrigeration cycle. The initially cooled HCl and H2O mixture is further cooled to 50-70℃ by the third condenser 30 and then sent to electrolysis reactor 19. In electrolysis reactor 19, CuCl aqueous solution and HCl aqueous solution undergo an electrolytic reaction below 40℃: 2CuCl + 2HCl → H2 + 2CuCl2, producing... Hydrogen gas and CuCl2 solution are processed. The generated hydrogen gas is pressurized to 20-35 MPa by a four-stage compressor 20 and stored in a hydrogen storage tank 21. The CuCl2 solution generated by electrolysis enters a drying heat exchanger 22, where it is dried using the heat released from ammonia condensation to obtain solid CuCl2. The water vapor generated during the drying process is heated to 150-200℃ by a second waste heat exchanger 31 and then returned to the hydrolysis reactor 24 for recycling. The dried solid CuCl2 is heated to 300-350℃ by a first heater 23 and then returned to the hydrolysis reactor 24, completing the entire Cu-Cl cycle.

[0035] In one embodiment, the waste heat power generation and recovery unit includes an air turbine 11, a first waste heat exchanger 12, a third waste heat exchanger 32, a fourth waste heat exchanger 33, and an organic Rankine cycle power generation system. The inlet of the air turbine 11 is connected to the cathode exhaust gas pipeline of the methane reforming and SOFC power generation unit, and its outlet is connected to the heating side of the first waste heat exchanger 12. The heating side of the third waste heat exchanger 32 is connected to the exhaust gas pipeline from the copper chlorine cycle hydrogen production unit, and its cooling side is connected to the cooling side outlet of the first waste heat exchanger 12. The heating side of the fourth waste heat exchanger 33 is connected to the heating side outlet of the third waste heat exchanger 32, and its cooling side is connected to the organic Rankine cycle power generation system.

[0036] In one embodiment, the organic Rankine cycle power generation system includes a turbine 34, a regenerator 37, a fourth condenser 36, and a pump 35. The inlet of the turbine 34 is connected to the cooling-side outlet of the fourth waste heat exchanger 33, and its outlet is connected to the heating-side inlet of the regenerator 37. The heating-side outlet of the regenerator 37 is connected to the inlet of the pump 35 via the fourth condenser 36. The outlet of the pump 35 is connected to the cooling-side inlet of the regenerator 37, and the cooling-side outlet of the regenerator 37 is connected back to the cooling-side inlet of the fourth waste heat exchanger 33.

[0037] In one embodiment, the working fluid used in the organic Rankine cycle (ORC) power generation system is R123. R123 is a commonly used organic working fluid whose thermophysical properties are well-suited for recovering medium-low temperature waste heat around 150-200°C. Choosing R123 ensures that the ORC subsystem achieves high heat-to-work conversion efficiency under given waste heat temperature conditions.

[0038] The waste heat power generation and recovery unit can achieve three-stage waste heat recovery: First stage: The cathode exhaust gas from the air preheater 10 first drives the air turbine 11 to generate electricity, and the pressure drops to near atmospheric pressure and the temperature drops to 200-250℃; then it enters the first waste heat exchanger 12, which heats the room temperature water from the ambient temperature to 60-80℃, and the exhaust gas temperature drops to 100-150℃ before being discharged into the atmosphere.

[0039] Second stage: Flue gas from the outlet of the second waste heat exchanger 31 of the copper chlorine cycle hydrogen production unit enters the third waste heat exchanger 32, where it exchanges heat with the 60-80℃ hot water from the first waste heat exchanger 12, further heating the hot water to 90-99℃ to produce usable hot water.

[0040] The third stage: The flue gas discharged from the third waste heat exchanger 32 enters the fourth waste heat exchanger 33 to heat the working fluid R123 of the organic Rankine cycle. The specific process of the organic Rankine cycle is as follows: The working fluid R123 is heated and evaporated into steam at 120-150°C in the fourth waste heat exchanger 33, and then enters the turbine 34 to expand and generate electricity; the exhaust gas after doing work enters the regenerator 37 to release heat, and the temperature drops to 60-80°C; then it is pumped by the pump 35 to the fourth condenser 36 to cool to a liquid state of 30-40°C; then it enters the regenerator 37 to absorb heat, and the temperature rises back to 50-70°C before returning to the fourth waste heat exchanger 33 to complete the cycle.

[0041] Through the above three-stage waste heat recovery, the system realizes the tiered utilization of heat energy of different grades, maximizing the overall energy utilization efficiency.

[0042] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A system for the stepwise utilization of methane based on SOFC and copper-chlorine cycle, characterized in that, The application relates to a system for producing hydrogen and electricity from methane, comprising: a methane reforming and SOFC power generation unit for converting methane fuel into electricity and generating high-temperature flue gas by burning anode tail gas; a copper-chlorine cycle hydrogen production unit connected with a high-temperature flue gas pipeline of the methane reforming and SOFC power generation unit, which utilizes the heat energy of the high-temperature flue gas to drive a copper-chlorine thermochemical cycle reaction to produce hydrogen from water as raw material; a waste heat power generation and recovery unit connected with a cathode tail gas pipeline of the methane reforming and SOFC power generation unit and a tail gas outlet pipeline of the copper-chlorine cycle hydrogen production unit, which is used for generating electricity and supplying heat by the waste heat in the system. 2.The system according to claim 1, wherein, The methane reforming and SOFC power generation unit comprises a methane compressor, a steam compressor, a mixer, a fuel preheater, a reformer, a solid oxide fuel cell, a burner, a first air compressor, a second air compressor and an air preheater; the outlets of the methane compressor and the steam compressor are connected with the inlet of the mixer, the outlet of the mixer is connected with the reactant inlet of the reformer through the fuel preheater, and the syngas outlet of the reformer is connected with the anode inlet of the solid oxide fuel cell; the outlet of the second air compressor is connected with the cathode inlet of the solid oxide fuel cell through the air preheater; the anode outlet of the solid oxide fuel cell is connected with the fuel inlet of the burner, the outlet of the first air compressor is connected with the air inlet of the burner, and the high-temperature flue gas outlet of the burner is connected with the heat supply channel of the reformer and the heat supply channel of the fuel preheater in sequence and then leads to the copper-chlorine cycle hydrogen production unit. 3.The system according to claim 2, wherein, the cathode outlet of the solid oxide fuel cell is connected with the heat supply side inlet of the air preheater, and the heat supply side outlet of the air preheater is connected with the waste heat power generation and recovery unit. 4.The system according to claim 2, wherein, The operating temperature of the reformer is 650-750 DEG C.

5. The system according to claim 1, wherein, The copper-chlorine cycle hydrogen production unit comprises a hydrolysis reactor, a separator, a second heater, a pyrolysis reactor gas separator, an electrolysis reactor, a drying heat exchanger and a first heater; the heat supply side of the hydrolysis reactor is connected with the high-temperature flue gas pipeline from the methane reforming and SOFC power generation unit, the solid phase inlet is used for feeding solid CuCl2, the gas phase inlet is used for feeding water vapor, and the outlet is connected with the inlet of the separator; the solid phase outlet of the separator is connected with the inlet of the pyrolysis reactor through the second heater; the gas phase outlet of the pyrolysis reactor is connected with the inlet of the gas separator, the oxygen outlet of the gas separator leads to the atmosphere, and the solid phase outlet is connected with the first inlet of the electrolysis reactor through a cooling pipeline; the gas phase outlet of the separator is connected with the second inlet of the electrolysis reactor through a cooling pipeline; the hydrogen outlet of the electrolysis reactor is connected with a hydrogen storage device, and the solution outlet is connected with the solid phase inlet of the hydrolysis reactor through the drying heat exchanger and the first heater.

6. The methane cascade utilization system based on SOFC and copper-chlorine cycle according to claim 5, characterized in that, The copper-chlorine cycle hydrogen production unit further comprises an ammonia heat pump circuit, and the ammonia heat pump circuit comprises a heat exchanger, an ammonia compressor and a throttle valve; the heat supply side of the heat exchanger is connected in series on the cooling pipeline between the gas phase outlet of the separator and the electrolysis reactor, and the cooling side is connected with the ammonia heat pump circuit. The inlet of the ammonia compressor is connected to the cooling side outlet of the heat exchanger, the outlet of which is connected to the heating side inlet of the drying heat exchanger, and the heating side outlet of the drying heat exchanger is connected to the cooling side inlet of the heat exchanger through a throttle valve.

7. The methane cascade utilization system based on SOFC and copper-chlorine cycle according to claim 5, characterized in that, The heating side of the pyrolysis reactor, the heating side of the second heater and the heating side of the first heater are connected to the high-temperature flue gas pipeline from the methane reforming and SOFC power generation unit. 8.The system according to claim 1, wherein, The waste heat power generation and recovery unit comprises an air turbine, a first waste heat exchanger, a third waste heat exchanger, a fourth waste heat exchanger and an organic Rankine cycle power generation subsystem; The inlet of the air turbine is connected to the cathode tail gas pipeline of the methane reforming and SOFC power generation unit, and the outlet thereof is connected to the heating side of the first waste heat exchanger; The heating side of the third waste heat exchanger is connected to the tail gas pipeline from the copper-chlorine cycle hydrogen production unit, and the cooling side thereof is connected to the cooling side outlet of the first waste heat exchanger; The heating side of the fourth waste heat exchanger is connected to the heating side outlet of the third waste heat exchanger, and the cooling side thereof is connected to the organic Rankine cycle power generation subsystem. 9.The system according to claim 8, wherein, The organic Rankine cycle power generation subsystem comprises a turbine, a recuperator, a fourth condenser and a pump; The inlet of the turbine is connected to the cooling side outlet of the fourth waste heat exchanger, and the outlet thereof is connected to the heating side inlet of the recuperator; The heating side outlet of the recuperator is connected to the inlet of the fourth condenser and the pump through the fourth condenser; The outlet of the pump is connected to the cooling side inlet of the recuperator, and the cooling side outlet of the recuperator is connected to the cooling side inlet of the fourth waste heat exchanger.

10. The methane cascade utilization system based on SOFC and copper-chlorine cycle according to claim 9, characterized in that, The working medium used in the organic Rankine cycle power generation subsystem is R123.

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