Ultra-transcritical carbon dioxide hydrogen-electricity co-production system and method

Abstract

The system comprises a supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device, a methanol cracking cycle hydrogen production device, a hydrogen separation and synthesis gas combustion device, a transcritical carbon dioxide Rankine cycle power generation device and an organic Rankine cycle power generation device. The low-temperature industrial waste heat is heated and upgraded, heat energy required by methanol cracking circulation hydrogen production is provided, the industrial waste heat and compression heat energy are fully utilized, and low-grade heat energy is converted into high-grade free-state chemical energy through methanol cracking reaction to be output; hydrogen is separated in the hydrogen separation and synthesis gas combustion process, so that clean hydrogen energy can be obtained, the combustion temperature of synthesis gas is reduced, and the cost of a combustion chamber is reduced; the coupling of the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle effectively recovers the flue gas waste heat of the combustion chamber and generates power, so that the thermoelectric conversion efficiency is improved, and the efficient gradient utilization of heat energy is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-temperature waste heat utilization and power generation, and specifically relates to a super-transcritical carbon dioxide hydrogen power cogeneration system and method. Background Art

[0002] With the rapid development of global industrialization, global primary energy consumption has increased year by year. The three major fossil energy sources of coal, oil and natural gas have always accounted for more than 80% of energy consumption and still occupy a dominant position in the world energy system. General industrial production activities (such as steel, cement, chemical production, etc.) consume traditional primary energy to generate a large amount of industrial waste heat, of which medium and low temperature industrial waste heat (below 200℃) accounts for more than 50%. A large amount of medium and low temperature industrial waste heat is not utilized and discharged into the environment, which not only causes heat energy loss and reduced system efficiency, but also causes a serious ecological and environmental crisis.

[0003] At present, the main technologies for utilizing medium and low temperature industrial waste heat include heat pump technology, organic Rankine cycle power generation technology, Kalina cycle power generation technology, etc. Heat pump technology can be divided into the first type of heat pump and the second type of heat pump technology according to user needs. The first type of heat pump converts a small amount of high-temperature heat source into a large amount of low-temperature thermal energy, while the second type of heat pump heats up and upgrades a large amount of low-temperature thermal energy into a small amount of high-temperature thermal energy to improve the utilization potential of thermal energy. However, it has the problem of downgrading high-grade electrical energy to low-grade thermal energy and cannot improve the energy grade. Among the thermoelectric conversion technologies, organic Rankine cycle power generation technology and Kalina cycle power generation technology have been widely studied and applied due to their wide range of applications, high stability and simple structure. However, due to the low thermal quality of low-temperature waste heat, under current technical conditions, the above-mentioned low-temperature waste heat power generation technology has the problem of low thermoelectric conversion efficiency. Summary of the invention

[0004] The object of the present invention is to provide a super transcritical carbon dioxide hydrogen power cogeneration system and method to solve the technical defect of low temperature waste heat power generation technology in the prior art that the thermoelectric conversion efficiency is low.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In the first aspect, a super transcritical carbon dioxide hydrogen-electricity cogeneration system is provided, including a supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device, a methanol cracking cycle hydrogen production device, a hydrogen separation and synthesis gas combustion device, a transcritical carbon dioxide Rankine cycle power generation device, and an organic Rankine cycle power generation device; The supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device is connected to the methanol cracking cycle hydrogen production device, the methanol cracking cycle hydrogen production device is connected to the hydrogen separation and synthesis gas combustion device, and the hydrogen separation and synthesis gas combustion device is connected to the transcritical carbon dioxide Rankine cycle power generation device and the organic Rankine cycle power generation device; Among them, the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device and the methanol cracking cycle hydrogen production unit constitute the system top cycle, the transcritical carbon dioxide Rankine cycle power generation device and the organic Rankine cycle power generation device constitute the system bottom cycle, and the hydrogen separation and synthesis gas combustion device is used to separate the hydrogen produced in the system top cycle from the synthesis gas, and burn the remaining carbon monoxide synthesis gas to provide high-temperature thermal energy for the system bottom cycle power generation, so as to convert medium and low temperature industrial waste heat into high-grade chemical energy.

[0006] Furthermore, the methanol cracking cycle hydrogen production device comprises a methanol storage tank, a methanol booster pump, a methanol recuperator, a methanol carbon dioxide heat exchanger, a methanol cracking reactor and a first driving motor, the inlet of the methanol booster pump is connected to the outlet of the methanol storage tank through a pipeline, and the outlet of the methanol booster pump is connected to the cold end inlet of the methanol recuperator through a pipeline; The cold end outlet of the methanol recuperator is connected to the cold end inlet of the methanol carbon dioxide heat exchanger via a pipeline, the cold end outlet of the methanol carbon dioxide heat exchanger is connected to the cold end inlet of the methanol cracking reactor via a pipeline, the cold end outlet of the methanol cracking reactor is connected to the hot end inlet of the methanol recuperator via a pipeline, and the hot end outlet of the methanol recuperator is connected to the hydrogen separation and synthesis gas combustion device via a pipeline.

[0007] Furthermore, the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device includes a carbon dioxide compressor, a coaxial first carbon dioxide turbine, an industrial waste heat exchanger, a first carbon dioxide regenerator, a second drive motor and an industrial waste heat switch valve. The carbon dioxide compressor and the first carbon dioxide regenerator are connected to the methanol cracking cycle hydrogen production device, the hot end outlet of the first carbon dioxide regenerator is connected to the inlet of the first carbon dioxide turbine via a pipeline, and the first carbon dioxide turbine outlet is connected to the cold end inlet and outlet of the industrial waste heat exchanger and the cold end inlet of the first carbon dioxide regenerator via a pipeline.

[0008] Furthermore, the cold end outlet of the first carbon dioxide regenerator is connected to the inlet of the carbon dioxide compressor via a pipeline, and the industrial waste heat switch valve is connected to the hot end inlet and outlet of the industrial waste heat exchanger in sequence via a pipeline.

[0009] Furthermore, the hydrogen separation and synthesis gas combustion device includes a gas-liquid separator, a synthesis gas pressure reducing valve, a fan, a combustion chamber, a hydrogen separation switch valve and a third driving motor. The upper inlet of the gas-liquid separator is connected to the methanol cracking cycle hydrogen production device through a pipeline, the upper right outlet of the gas-liquid separator is connected to the hydrogen separation switch valve through a pipeline, and the lower right outlet of the gas-liquid separator is connected to the inlet of the synthesis gas pressure reducing valve through a pipeline.

[0010] Furthermore, the inlet of the fan is connected to the atmosphere, the outlet of the fan is connected to the left inlet of the combustion chamber via a pipeline, the lower inlet of the combustion chamber is connected to the outlet of the synthesis gas pressure reducing valve via a pipeline, and the upper outlet of the combustion chamber is connected to the system bottom circulation via a pipeline.

[0011] Further, the transcritical carbon dioxide Rankine cycle power generation device includes a carbon dioxide pump, a second carbon dioxide regenerator, a flue gas carbon dioxide heat exchanger, a second carbon dioxide turbine, a carbon dioxide condenser, a first low-temperature water switch valve, a first generator and a fourth drive motor, the outlet of the carbon dioxide pump is connected to the cold end inlet and outlet of the second carbon dioxide regenerator and the cold end inlet of the flue gas carbon dioxide heat exchanger in sequence through a pipeline, and the cold end outlet of the flue gas carbon dioxide heat exchanger is connected to the inlet of the second carbon dioxide turbine through a pipeline; The outlet of the second carbon dioxide turbine is connected to the hot end inlet and outlet of the second carbon dioxide regenerator and the hot end inlet of the carbon dioxide condenser in sequence through pipelines.

[0012] Furthermore, the hot end outlet of the carbon dioxide condenser is connected to the inlet of the carbon dioxide pump via a pipeline, and the first low-temperature water switch valve is connected to the cold end inlet and outlet of the carbon dioxide condenser in sequence via a pipeline; the hot end inlet and outlet of the flue gas carbon dioxide heat exchanger are respectively connected to the hydrogen separation and synthesis gas combustion device and the machine Rankine cycle power generation device via pipelines.

[0013] Furthermore, the Rankine cycle power generation device comprises an organic working fluid pump, a flue gas organic working fluid heat exchanger, an organic working fluid turbine, an organic working fluid condenser, a second low-temperature water switch valve, a fifth drive motor and a second generator, and the outlet of the organic working fluid pump is connected to the cold end inlet and outlet of the flue gas organic working fluid heat exchanger and the inlet of the organic working fluid turbine in sequence through a pipeline; The outlet of the organic working fluid turbine is connected to the hot end inlet and outlet of the organic working fluid condenser and the inlet of the organic working fluid pump in sequence through a pipeline. The hot end inlet and outlet of the flue gas organic working fluid heat exchanger are respectively connected to the transcritical carbon dioxide Rankine cycle power generation device and the atmospheric environment. The second low-temperature water switch valve is connected to the cold end inlet and outlet of the organic working fluid condenser in sequence through a pipeline.

[0014] In a second aspect, a super transcritical carbon dioxide hydrogen power cogeneration method is provided, the method being performed using the system as described above, comprising: When industrial production generates medium and low temperature industrial waste heat, start the system top cycle and system bottom cycle; After starting the system top cycle and the system bottom cycle, opening each switch valve and the synthesis gas pressure reducing valve in sequence; By utilizing the activated top cycle of the system, synthesis gas of hydrogen, carbon monoxide and methanol vapor is obtained, and methanol liquid is preheated to realize the conversion of medium and low temperature industrial waste heat into high-grade chemical energy; Through the medium and low temperature industrial flue gas fluid, thermal energy is provided to the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device to complete the supercritical carbon dioxide reverse Brayton cycle; Based on the methanol cracking cycle hydrogen production device, the low-temperature and high-pressure synthesis gas mixture is separated into gas and liquid, the generated hydrogen is used for transportation or sale, and the remaining synthesis gas is formed into fuel and fully burned. The combustion product is used as the driving heat source for the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle; By utilizing the started system bottom cycle, the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle are completed in sequence to achieve waste heat recovery.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. Through this system, industrial low-temperature waste heat is heated and improved through a supercritical carbon dioxide reverse Brayton cycle, thereby increasing the thermal energy potential of low-temperature industrial waste heat; secondly, the obtained medium- and high-temperature thermal energy is used to provide the required thermal energy for the methanol cracking hydrogen production cycle to prepare synthesis gas. This process converts low-grade thermal energy into chemical energy of high-grade hydrogen and other synthesis gases through the chemical reaction of methanol cracking, so that low-temperature industrial waste heat and compression heat are fully and efficiently utilized; and through the hydrogen separation and synthesis gas combustion unit, hydrogen, unreacted methanol and carbon monoxide and other synthesis gases are separated, which not only obtains clean hydrogen energy, but also reduces the combustion temperature of the synthesis gas in the combustion unit, thereby reducing the cost of the combustion chamber; finally, the flue gas waste heat at the combustion chamber outlet is recovered and generated electricity through the transcritical carbon dioxide Rankine cycle coupled with the organic Rankine cycle, which not only improves the net electrical power output of the system, but also improves the thermoelectric conversion efficiency, and realizes the efficient cascade recovery and utilization of thermal energy.

[0016] 2. In the methanol cracking cycle hydrogen production device, by utilizing the thermal energy after the supercritical carbon dioxide reverse Brayton cycle is heated, the low-grade thermal energy can be converted into the chemical energy of high-grade hydrogen and other synthetic gases through the methanol cracking chemical reaction, so that the low-temperature industrial waste heat and compression heat energy can be fully and efficiently utilized.

[0017] 3. The thermal energy potential of low-temperature industrial waste heat is increased by using the supercritical carbon dioxide reverse Brayton cycle to increase the temperature and quality of the waste heat.

[0018] 4. The carbon dioxide regenerator can recover the high-temperature waste heat of the carbon dioxide at the outlet of the air cooler and transfer it to the low-temperature carbon dioxide coming from the outlet of the evaporator. The low-temperature carbon dioxide is preheated before entering the compressor, thereby increasing the inlet temperature of the compressor.

[0019] 5. By separating hydrogen, unreacted methanol and carbon monoxide and other synthesis gases through hydrogen separation and synthesis gas combustion units, not only clean hydrogen energy is obtained, but also the combustion temperature of the synthesis gas in the combustion unit is reduced, thereby reducing the cost of the combustion chamber.

[0020] 6. The inlet of the fan is connected to the atmosphere, ensuring that the combustion chamber can obtain sufficient air supply, which can ensure the stable combustion of the flame in the combustion chamber, reduce fluctuations and unstable factors in the combustion process, and thus improve the stability of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0022] Figure 1 A schematic diagram of a super transcritical carbon dioxide hydrogen power cogeneration system provided by the present invention; Figure 2 A flow chart of the super transcritical carbon dioxide hydrogen power cogeneration method provided by the present invention; Among them: 1. Methanol storage tank; 2. Methanol booster pump; 3. Methanol recuperator; 4. Methanol carbon dioxide heat exchanger; 5. Methanol cracking reactor; 6. Gas-liquid separator; 7. Syngas pressure reducing valve; 8. Fan; 9. Combustion chamber; 10. Carbon dioxide compressor; 11. First carbon dioxide turbine; 12. Industrial waste heat exchanger; 13. First carbon dioxide regenerator; 14. Carbon dioxide pump; 15. Second carbon dioxide regenerator; 16. Flue gas carbon dioxide heat exchanger; 17. Second carbon dioxide turbine 1. level; 18. carbon dioxide condenser; 19. organic working fluid pump; 20. flue gas organic working fluid heat exchanger; 21. organic working fluid turbine; 22. organic working fluid condenser; 23. first drive motor; 24. second drive motor; 25. third drive motor; 26. first generator; 27. fourth drive motor; 28. fifth drive motor; 29. ​​second generator; V1. hydrogen separation switch valve; V2. industrial waste heat switch valve; V3. first low-temperature water switch valve; V4. second low-temperature water switch valve. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0026] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0027] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0028] At present, the main technologies for utilizing medium and low temperature industrial waste heat include heat pump technology, organic Rankine cycle power generation technology, Kalina cycle power generation technology, etc. Heat pump technology can be divided into the first type of heat pump and the second type of heat pump technology according to user needs. The first type of heat pump converts a small amount of high-temperature heat source into a large amount of low-temperature thermal energy, while the second type of heat pump heats up and upgrades a large amount of low-temperature thermal energy into a small amount of high-temperature thermal energy to improve the utilization potential of thermal energy. However, it has the problem of downgrading high-grade electrical energy to low-grade thermal energy and cannot improve the energy grade. Among the thermoelectric conversion technologies, organic Rankine cycle power generation technology and Kalina cycle power generation technology have been widely studied and applied due to their wide range of applications, high stability and simple structure. However, due to the low thermal quality of low-temperature waste heat, under current technical conditions, the above-mentioned low-temperature waste heat power generation technology has the problem of low thermoelectric conversion efficiency.

[0029] In order to solve the above technical defects, the inventor provides a super transcritical carbon dioxide hydrogen power cogeneration system and method.

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings: like Figure 1 As shown, in a first aspect of an embodiment of the present invention, a super transcritical carbon dioxide hydrogen-electricity cogeneration system is provided, including a supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device, a methanol cracking cycle hydrogen production device, a hydrogen separation and synthesis gas combustion device, a transcritical carbon dioxide Rankine cycle power generation device, and an organic Rankine cycle power generation device; the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device is connected to the methanol cracking cycle hydrogen production device, the methanol cracking cycle hydrogen production device is connected to the hydrogen separation and synthesis gas combustion device, and the hydrogen separation and synthesis gas combustion device is connected to the transcritical carbon dioxide Rankine cycle power generation device and the organic Rankine cycle power generation device; wherein, As the second type of heat pump, the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device is used to heat and upgrade the industrial low-temperature waste heat, providing medium and high temperature thermal energy for methanol cracking hydrogen production. The supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device and the methanol cracking cycle hydrogen production unit constitute the system top cycle; the transcritical carbon dioxide Rankine cycle power generation device and the organic Rankine cycle power generation device constitute the system bottom cycle, and the hydrogen separation and synthesis gas combustion device is used to separate the hydrogen produced in the system top cycle from the synthesis gas, and burn the remaining carbon monoxide synthesis gas to provide high-temperature thermal energy for the system bottom cycle power generation, so as to convert medium and low temperature industrial waste heat into high-quality chemical energy. Figure 1As shown, the methanol cracking cycle hydrogen production device includes a methanol storage tank 1, a methanol booster pump 2, a methanol recuperator 3, a methanol carbon dioxide heat exchanger 4, a methanol cracking reactor 5 and a first drive motor 23, the inlet of the methanol booster pump 2 is connected to the outlet of the methanol storage tank 1 through a pipeline, and the outlet of the methanol booster pump 2 is connected to the cold end inlet of the methanol recuperator 3 through a pipeline; the cold end outlet of the methanol recuperator 3 is connected to the cold end inlet of the methanol carbon dioxide heat exchanger 4 through a pipeline, and the cold end outlet of the methanol carbon dioxide heat exchanger 4 is connected to the methanol The cold end inlet of the cracking reactor 5 is connected, and the cold end outlet of the methanol cracking reactor 5 is connected to the hot end inlet of the methanol recuperator 3 through a pipeline, and the hot end outlet of the methanol recuperator 3 is connected to the hydrogen separation and synthesis gas combustion device through a pipeline; specifically, in the methanol cracking cycle hydrogen production device, by utilizing the thermal energy after the supercritical carbon dioxide is heated by the reverse Brayton cycle, the low-grade thermal energy can be converted into the chemical energy of high-grade hydrogen and other synthesis gas through the methanol cracking chemical reaction, so that the low-temperature industrial waste heat and compression heat energy can be fully and efficiently utilized.

[0031] The supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device comprises a carbon dioxide compressor 10, a coaxial first carbon dioxide turbine 11, an industrial waste heat exchanger 12, a first carbon dioxide regenerator 13, a second drive motor 24 and an industrial waste heat switch valve V2. The outlet of the carbon dioxide compressor 10 is connected to the hot end inlet of the methanol cracking reactor 5 through a pipeline, and the hot end outlet of the methanol cracking reactor 5 is sequentially connected to the hot end inlet and outlet of the methanol carbon dioxide heat exchanger 4 and the hot end inlet of the first carbon dioxide regenerator 13 through a pipeline. The carbon dioxide compressor 10 and the first carbon dioxide regenerator 13 are connected to the methanol cracking cycle hydrogen production device, and the hot end outlet of the first carbon dioxide regenerator 13 is connected to the inlet of the first carbon dioxide turbine 11 through a pipeline. The outlet of the first carbon dioxide turbine 11 is sequentially connected to the cold end inlet and outlet of the industrial waste heat exchanger 12 and the cold end inlet of the first carbon dioxide regenerator 13 through a pipeline. The cold end outlet of the first carbon dioxide regenerator 13 is connected to the inlet of the carbon dioxide compressor 10 through a pipeline, and the industrial waste heat switch valve V2 is sequentially connected to the hot end inlet and outlet of the industrial waste heat exchanger 12 through a pipeline. The supercritical carbon dioxide reverse Brayton cycle is used to heat and improve the quality of industrial low-temperature waste heat, thereby increasing the thermal energy potential of low-temperature industrial waste heat. The carbon dioxide regenerator can recover the high-temperature waste heat of carbon dioxide at the outlet of the air cooler and transfer it to the low-temperature carbon dioxide from the outlet of the evaporator. The low-temperature carbon dioxide is preheated before entering the compressor, thereby increasing the inlet temperature of the compressor.

[0032] The hydrogen separation and synthesis gas combustion device comprises a gas-liquid separator 6, a synthesis gas pressure reducing valve 7, a blower 8, a combustion chamber 9, a hydrogen separation switch valve V1 and a third driving motor 25. The upper inlet of the gas-liquid separator 6 is connected to the methanol cracking cycle hydrogen production device through a pipeline, specifically connected to the hot end outlet of the methanol recuperator 3, the left end outlet of the gas-liquid separator 6 is connected to the inlet of the methanol storage tank 1 through a pipeline, the upper right end outlet of the gas-liquid separator 6 is connected to the hydrogen separation switch valve V1 through a pipeline, and the lower right end outlet of the gas-liquid separator 6 is connected to the inlet of the synthesis gas pressure reducing valve 7 through a pipeline. The inlet of the blower 8 is connected to the atmosphere, the outlet of the blower 8 is connected to the left end inlet of the combustion chamber 9 through a pipeline, the lower end inlet of the combustion chamber 9 is connected to the outlet of the synthesis gas pressure reducing valve 7 through a pipeline, and the upper end outlet of the combustion chamber 9 is connected to the system bottom circulation through a pipeline. By separating hydrogen, unreacted methanol, carbon monoxide and other synthesis gases through the hydrogen separation and synthesis gas combustion device, not only clean hydrogen energy is obtained, but also the combustion temperature of the synthesis gas in the combustion unit is reduced, thereby reducing the cost of the combustion chamber 9. The inlet of the fan 8 is connected to the atmosphere, which ensures that the combustion chamber 9 can obtain sufficient air supply, ensures that the flame in the combustion chamber 9 burns stably, reduces fluctuations and unstable factors in the combustion process, and thus improves the stability of the entire system.

[0033] The transcritical carbon dioxide Rankine cycle power generation device includes a carbon dioxide pump 14, a second carbon dioxide regenerator 15, a flue gas carbon dioxide heat exchanger 16, a second carbon dioxide turbine 17, a carbon dioxide condenser 18, a first low-temperature water switch valve V3, a first generator 26 and a fourth drive motor 27. The outlet of the carbon dioxide pump 14 is connected to the cold end inlet and outlet of the second carbon dioxide regenerator 15 and the cold end inlet of the flue gas carbon dioxide heat exchanger 16 through a pipeline in sequence, and the cold end outlet of the flue gas carbon dioxide heat exchanger 16 is connected to the inlet of the second carbon dioxide turbine 17 through a pipeline; the outlet of the second carbon dioxide turbine 17 is connected to the hot end inlet and outlet of the second carbon dioxide regenerator 15 and the hot end inlet of the carbon dioxide condenser 18 through a pipeline in sequence. The hot end outlet of the carbon dioxide condenser 18 is connected to the inlet of the carbon dioxide pump 14 through a pipeline, and the first low-temperature water switch valve V3 is connected to the cold end inlet and outlet of the carbon dioxide condenser 18 through a pipeline in sequence; the hot end inlet and outlet of the flue gas carbon dioxide heat exchanger 16 are respectively connected to the upper end outlet of the combustion chamber 9 and the organic Rankine power generation device through pipelines. The Rankine cycle power generation device includes an organic working fluid pump 19, a flue gas organic working fluid heat exchanger 20, an organic working fluid turbine 21, an organic working fluid condenser 22, a second low-temperature water switch valve V4, a fifth drive motor 28 and a second generator 29. The outlet of the organic working fluid pump 19 is connected to the cold end inlet and outlet of the flue gas organic working fluid heat exchanger 20 and the inlet of the organic working fluid turbine 21 in sequence through a pipeline; the outlet of the organic working fluid turbine 21 is connected to the hot end inlet and outlet of the organic working fluid condenser 22 and the inlet of the organic working fluid pump 19 in sequence through a pipeline, the hot end inlet and outlet of the flue gas organic working fluid heat exchanger 20 are respectively connected to the transcritical carbon dioxide Rankine cycle power generation device and the atmospheric environment, and the second low-temperature water switch valve V4 is connected to the cold end inlet and outlet of the organic working fluid condenser 22 in sequence through a pipeline. Firstly, the industrial low-temperature waste heat is heated and improved through the supercritical carbon dioxide reverse Brayton cycle, thereby increasing the thermal energy potential of the low-temperature industrial waste heat; secondly, the obtained medium- and high-temperature thermal energy is used to provide the required thermal energy for the methanol cracking hydrogen production cycle to prepare synthesis gas. This process converts low-grade thermal energy into chemical energy of high-grade hydrogen and other synthesis gases through the methanol cracking chemical reaction, so that the low-temperature industrial waste heat and compression heat energy are fully and efficiently utilized; and through the hydrogen separation and synthesis gas combustion unit, hydrogen, unreacted methanol and carbon monoxide and other synthesis gases are separated, which not only obtains clean hydrogen energy, but also reduces the combustion temperature of the synthesis gas in the combustion unit, thereby reducing the cost of the combustion chamber; finally, the flue gas waste heat at the combustion chamber outlet is recovered and generated electricity through the transcritical carbon dioxide Rankine cycle coupled with the organic Rankine cycle, which not only improves the net electrical power output of the system, but also improves the thermoelectric conversion efficiency, and realizes the efficient cascade recovery and utilization of thermal energy.

[0034] In a second aspect, an embodiment of the present invention provides a super transcritical carbon dioxide hydrogen power cogeneration method, the method is performed using the system as described above, and includes: S101. When industrial production generates medium- and low-temperature industrial waste heat, start the system top cycle and the system bottom cycle; illustratively, when industrial production generates medium- and low-temperature industrial waste heat, the system top cycle consisting of a supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device and a methanol cracking cycle hydrogen production device is started first, and then the system bottom cycle consisting of a hydrogen separation and synthesis gas combustion device, a transcritical carbon dioxide Rankine cycle power generation device and an organic Rankine cycle power generation device is started in sequence.

[0035] S102. After starting the system top circulation and the system bottom circulation, open each switch valve and the synthesis gas pressure reducing valve in sequence; illustratively, the hydrogen separation switch valve V1, the industrial waste heat switch valve V2, the first low-temperature water switch valve V3, the second low-temperature water switch valve V4 and the synthesis gas pressure reducing valve 7 are opened in sequence.

[0036] S103. Utilize the started system top cycle to obtain synthesis gas of hydrogen, carbon monoxide and methanol vapor, and preheat methanol liquid to realize the conversion of medium and low temperature industrial waste heat into high-grade chemical energy. Exemplarily, the system top cycle consisting of the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device and the methanol cracking cycle hydrogen production device is started simultaneously. After the low-temperature and normal-pressure methanol liquid in the methanol storage tank 1 is pressurized by the methanol booster pump 2, the low-temperature and high-pressure methanol liquid enters the cold end of the methanol recuperator 3. The methanol liquid after absorbing heat enters the cold end of the methanol carbon dioxide heat exchanger 4 to further absorb heat. The methanol liquid evaporates into methanol vapor. Subsequently, the methanol vapor enters the methanol cracking reactor 5 to absorb the medium and high temperature heat energy provided by the reverse Brayton cycle waste heat upgrading device, and performs a methanol cracking reaction to generate synthesis gas of hydrogen, carbon monoxide and methanol vapor. The synthesis gas is preheated for the methanol liquid at the outlet of the methanol booster pump 2 through the hot end of the methanol recuperator 3, thereby realizing the conversion of medium and low temperature industrial waste heat into high-grade chemical energy.

[0037] S104. The medium and low temperature industrial flue gas fluid is used to provide thermal energy for the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device, and the supercritical carbon dioxide reverse Brayton cycle is completed. For example, the medium and low temperature industrial flue gas fluid is used as a low temperature heat source through the hot end of the industrial waste heat exchanger 12 to provide thermal energy for the carbon dioxide reverse Brayton cycle. The low temperature and low pressure supercritical carbon dioxide fluid at the outlet of the first carbon dioxide turbine 11 in the reverse Brayton cycle enters the cold end of the industrial waste heat exchanger 12 and the first carbon dioxide regenerator 13 in turn for heat exchange. At the same time, the second drive motor 24 uses electric energy to drive the carbon dioxide compressor 10 to increase the temperature and pressure of the heated low-pressure supercritical carbon dioxide fluid. The high temperature and high pressure carbon dioxide fluid at the outlet of the carbon dioxide compressor 10 enters the hot end of the methanol cracking reactor 5 and the methanol carbon dioxide heat exchanger 4 in turn to provide the required thermal energy for methanol evaporation and cracking. The carbon dioxide fluid at the hot end outlet of the methanol carbon dioxide heat exchanger 4 enters the hot end of the first carbon dioxide regenerator 13 to release heat and recover part of the internal heat energy of the system. Then, the high pressure supercritical carbon dioxide fluid at a certain temperature enters the first carbon dioxide turbine 11 to do work, and the supercritical carbon dioxide reverse Brayton cycle is completed.

[0038] S105. Based on the methanol cracking cycle hydrogen production device, the low-temperature and high-pressure synthesis gas mixture is separated into gas and liquid, the generated hydrogen is used for transportation or sale, the remaining synthesis gas forms fuel and is fully burned, and the combustion product is used as the driving heat source for the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle; illustratively, then, the low-temperature and high-pressure synthesis gas mixture at the hot end outlet of the methanol recuperator 3 is separated into gas and liquid by the gas-liquid separator 6, and the separated methanol liquid enters the methanol storage tank 1 for the methanol cracking cycle process, and the separated hydrogen is transported to downstream users or sold. The separated carbon monoxide and other synthesis gas mixture is reduced in pressure by the synthesis gas pressure reducing valve 7 to stabilize the inlet pressure of the combustion chamber 9, and enters the combustion chamber 9 for combustion. At the same time, the third drive motor 25 drives the fan 8 to transport a certain amount of air into the combustion chamber 9 to ensure that the synthesis gas fuel is fully burned.

[0039] S106. Utilize the started system bottom cycle to complete the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle in sequence to realize waste heat recovery; illustratively, the high-temperature flue gas at the outlet of the combustion chamber 9 first enters the hot end of the flue gas carbon dioxide heat exchanger 16 to provide heat energy for the transcritical carbon dioxide Rankine cycle power generation device. At the same time, the fourth drive motor 27 drives the carbon dioxide pump 14 to pressurize the carbon dioxide liquid, and then the high-pressure and low-temperature carbon dioxide liquid enters the second carbon dioxide regenerator 15 and the cold end of the flue gas carbon dioxide heat exchanger 16 in sequence to absorb heat, and then the high-temperature and high-pressure supercritical carbon dioxide fluid enters the second carbon dioxide turbine 17 to do work and drive the first generator 26 to generate electricity, and the low-pressure and medium-temperature supercritical carbon dioxide fluid at the outlet of the second carbon dioxide turbine 17 enters the hot end of the second carbon dioxide regenerator 15 and the low-temperature and low-pressure supercritical carbon dioxide fluid after heat release. The body releases heat and condenses at the hot end of the carbon dioxide condenser 18. At the same time, low-temperature water enters the cold end of the carbon dioxide condenser 18 to absorb the waste heat of the carbon dioxide working fluid, completing the transcritical carbon dioxide Rankine cycle; the medium-temperature flue gas at the hot end outlet of the flue gas carbon dioxide heat exchanger 16 provides thermal energy for the organic Rankine cycle power generation device. At the same time, the fifth drive motor 28 is driven to drive the organic working fluid pump 19 to pressurize the organic working fluid liquid, and then the high-pressure and low-temperature organic working fluid liquid enters the cold end of the flue gas organic working fluid heat exchanger 20 to absorb heat energy for evaporation, and then the superheated organic working fluid steam enters the organic working fluid turbine 21 to do work and drive the second generator 29 to generate electricity, and then the low-pressure and low-temperature organic working fluid gas enters the hot end of the organic working fluid condenser 22 to release heat and condense. At the same time, low-temperature water enters the cold end of the organic working fluid condenser 22 to absorb the waste heat of the organic working fluid, completing the organic Rankine cycle. The carbon dioxide reverse Brayton cycle provides the required thermal energy for the methanol cracking cycle hydrogen production unit by heating and upgrading low-temperature industrial waste heat. It not only makes full use of industrial waste heat and compression heat energy, but also converts low-grade thermal energy into high-grade free chemical energy output through the methanol cracking reaction; the hydrogen separation and synthesis gas combustion unit can not only obtain clean hydrogen energy by separating hydrogen, but also reduce the combustion temperature of synthesis gas and reduce the cost of the combustion chamber; the coupling of the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle effectively recovers the waste heat of the combustion chamber flue gas and generates electricity, which not only improves the net electrical power output of the system, but also improves the thermoelectric conversion efficiency, realizing the efficient cascade utilization of thermal energy.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit its protection scope. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present invention, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the pending claims of the invention.

Claims

1. A super transcritical carbon dioxide hydrogen power cogeneration system, characterized in that: Including supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device, methanol cracking cycle hydrogen production device, hydrogen separation and synthesis gas combustion device, transcritical carbon dioxide Rankine cycle power generation device and organic Rankine cycle power generation device; The supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device is connected to the methanol cracking cycle hydrogen production device, the methanol cracking cycle hydrogen production device is connected to the hydrogen separation and synthesis gas combustion device, and the hydrogen separation and synthesis gas combustion device is connected to the transcritical carbon dioxide Rankine cycle power generation device and the organic Rankine cycle power generation device; Among them, the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device and the methanol cracking cycle hydrogen production unit constitute the system top cycle, the transcritical carbon dioxide Rankine cycle power generation device and the organic Rankine cycle power generation device constitute the system bottom cycle, and the hydrogen separation and synthesis gas combustion device is used to separate the hydrogen produced in the system top cycle from the synthesis gas, and burn the remaining carbon monoxide synthesis gas to provide high-temperature thermal energy for the system bottom cycle power generation, so as to convert medium and low temperature industrial waste heat into high-grade chemical energy.

2. The system according to claim 1, characterized in that The methanol cracking cycle hydrogen production device comprises a methanol storage tank (1), a methanol booster pump (2), a methanol recuperator (3), a methanol carbon dioxide heat exchanger (4), a methanol cracking reactor (5) and a first drive motor (23); the inlet of the methanol booster pump (2) is connected to the outlet of the methanol storage tank (1) via a pipeline, and the outlet of the methanol booster pump (2) is connected to the cold end inlet of the methanol recuperator (3) via a pipeline; The cold end outlet of the methanol recuperator (3) is connected to the cold end inlet of the methanol carbon dioxide heat exchanger (4) via a pipeline, the cold end outlet of the methanol carbon dioxide heat exchanger (4) is connected to the cold end inlet of the methanol cracking reactor (5) via a pipeline, the cold end outlet of the methanol cracking reactor (5) is connected to the hot end inlet of the methanol recuperator (3) via a pipeline, and the hot end outlet of the methanol recuperator (3) is connected to the hydrogen separation and synthesis gas combustion device via a pipeline.

3. The system according to claim 1, characterized in that The supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device comprises a carbon dioxide compressor (10), a coaxial first carbon dioxide turbine (11), an industrial waste heat exchanger (12), a first carbon dioxide regenerator (13), a second drive motor (24) and an industrial waste heat switch valve (V2). The carbon dioxide compressor (10) and the first carbon dioxide regenerator (13) are connected to a methanol cracking cycle hydrogen production device. The hot end outlet of the first carbon dioxide regenerator (13) is connected to the inlet of the first carbon dioxide turbine (11) via a pipeline. The outlet of the first carbon dioxide turbine (11) is connected to the cold end inlet and outlet of the industrial waste heat exchanger (12) and the cold end inlet of the first carbon dioxide regenerator (13) via a pipeline.

4. The system according to claim 3, characterized in that The cold end outlet of the first carbon dioxide regenerator (13) is connected to the inlet of the carbon dioxide compressor (10) via a pipeline, and the industrial waste heat switch valve (V2) is connected to the hot end inlet and outlet of the industrial waste heat exchanger (12) in sequence via a pipeline.

5. The system according to claim 1, characterized in that The hydrogen separation and synthesis gas combustion device comprises a gas-liquid separator (6), a synthesis gas pressure reducing valve (7), a fan (8), a combustion chamber (9), a hydrogen separation switch valve (V1) and a third drive motor (25); the upper inlet of the gas-liquid separator (6) is connected to the methanol cracking cycle hydrogen production device via a pipeline, the upper right outlet of the gas-liquid separator (6) is connected to the hydrogen separation switch valve (V1) via a pipeline, and the lower right outlet of the gas-liquid separator (6) is connected to the inlet of the synthesis gas pressure reducing valve (7) via a pipeline.

6. The system according to claim 5, characterized in that The inlet of the fan (8) is connected to the atmosphere, the outlet of the fan (8) is connected to the left inlet of the combustion chamber (9) via a pipeline, the lower inlet of the combustion chamber (9) is connected to the outlet of the synthesis gas pressure reducing valve (7) via a pipeline, and the upper outlet of the combustion chamber (9) is connected to the system bottom circulation via a pipeline.

7. The system according to claim 1, characterized in that The transcritical carbon dioxide Rankine cycle power generation device comprises a carbon dioxide pump (14), a second carbon dioxide regenerator (15), a flue gas carbon dioxide heat exchanger (16), a second carbon dioxide turbine (17), a carbon dioxide condenser (18), a first low-temperature water switch valve (V3), a first generator (26) and a fourth drive motor (27), wherein the outlet of the carbon dioxide pump (14) is connected to the cold end inlet and outlet of the second carbon dioxide regenerator (15) and the cold end inlet of the flue gas carbon dioxide heat exchanger (16) in sequence through a pipeline, and the cold end outlet of the flue gas carbon dioxide heat exchanger (16) is connected to the inlet of the second carbon dioxide turbine (17) through a pipeline; The outlet of the second carbon dioxide turbine (17) is connected to the hot end inlet and outlet of the second carbon dioxide regenerator (15) and the hot end inlet of the carbon dioxide condenser (18) in sequence through pipelines.

8. The system according to claim 7, characterized in that The hot end outlet of the carbon dioxide condenser (18) is connected to the inlet of the carbon dioxide pump (14) via a pipeline, and the first low-temperature water switch valve (V3) is connected to the cold end inlet and outlet of the carbon dioxide condenser (18) in sequence via a pipeline; the hot end inlet and outlet of the flue gas carbon dioxide heat exchanger (16) are respectively connected to the hydrogen separation and synthesis gas combustion device and the Rankine cycle power generation device via pipelines.

9. The system according to claim 1, characterized in that The Rankine cycle power generation device comprises an organic working fluid pump (19), a flue gas organic working fluid heat exchanger (20), an organic working fluid turbine (21), an organic working fluid condenser (22), a second low-temperature water switch valve (V4), a fifth drive motor (28) and a second generator (29), wherein the outlet of the organic working fluid pump (19) is connected to the cold end inlet and outlet of the flue gas organic working fluid heat exchanger (20) and the inlet of the organic working fluid turbine (21) in sequence through pipelines; The outlet of the organic working fluid turbine (21) is connected to the hot end inlet and outlet of the organic working fluid condenser (22) and the inlet of the organic working fluid pump (19) in sequence through a pipeline; the hot end inlet and outlet of the flue gas organic working fluid heat exchanger (20) are respectively connected to the transcritical carbon dioxide Rankine cycle power generation device and the atmospheric environment; and the second low-temperature water switch valve (V4) is connected to the cold end inlet and outlet of the organic working fluid condenser (22) in sequence through a pipeline.

10. A super transcritical carbon dioxide hydrogen power cogeneration method, characterized in that: The method is performed using the system according to any one of claims 1 to 9, comprising: When industrial production generates medium and low temperature industrial waste heat, start the system top cycle and system bottom cycle; After starting the system top cycle and the system bottom cycle, opening each switch valve and the synthesis gas pressure reducing valve in sequence; By utilizing the activated top cycle of the system, synthesis gas of hydrogen, carbon monoxide and methanol vapor is obtained, and methanol liquid is preheated to realize the conversion of medium and low temperature industrial waste heat into high-grade chemical energy; Through the medium and low temperature industrial flue gas fluid, thermal energy is provided to the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device to complete the supercritical carbon dioxide reverse Brayton cycle; Based on the methanol cracking cycle hydrogen production device, the low-temperature and high-pressure synthesis gas mixture is separated into gas and liquid, the generated hydrogen is used for transportation or sale, and the remaining synthesis gas is formed into fuel and fully burned. The combustion product is used as the driving heat source for the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle; By utilizing the started system bottom cycle, the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle are completed in sequence to achieve waste heat recovery.

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