A super-transcritical carbon dioxide hydrogen power cogeneration system and method

Abstract

The present invention discloses a super-transcritical carbon dioxide hydrogen-electricity cogeneration system and method, which includes 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. By heating and upgrading low-temperature industrial waste heat, the required thermal energy is provided for methanol cracking cycle hydrogen production, which not only fully utilizes industrial waste heat and compression heat energy, but also converts low-grade thermal energy into high-grade free-state chemical energy output through methanol cracking reaction; hydrogen separation and synthesis gas combustion 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, improves the thermoelectric conversion efficiency, and realizes the efficient cascade utilization of thermal energy.

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 annually. The three major fossil fuels—coal, oil, and natural gas—have consistently accounted for over 80% of total energy consumption and continue to dominate the world's energy system. General industrial production activities (such as steel, cement, and chemical production) consume traditional primary energy sources and generate large amounts of industrial waste heat. Of this, medium- and low-temperature industrial waste heat (below 200°C) accounts for over 50%. This significant amount of low- and medium-temperature waste heat remains unused and is discharged into the environment, resulting in not only thermal energy losses and reduced system efficiency, but also a serious ecological and environmental crisis.

[0003] Currently, the main technologies for utilizing medium- and low-temperature industrial waste heat include heat pump technology, organic Rankine cycle power generation technology, and Kalina cycle power generation technology. Heat pump technology can be divided into two types based on user needs: Type I heat pumps convert a small amount of high-temperature heat into a large amount of low-temperature thermal energy, while Type II heat pumps heat and upgrade a large amount of low-temperature thermal energy into a small amount of high-temperature thermal energy, thereby increasing the potential for thermal energy utilization. However, these technologies inherently degrade high-quality electrical energy into low-quality thermal energy, failing to improve energy quality. Among thermoelectric conversion technologies, Organic Rankine cycle power generation technology and Kalina cycle power generation technology have been widely researched and applied due to their wide applicability, high stability, and simple structure. However, due to the low thermal quality of low-temperature waste heat, these technologies suffer from low thermoelectric conversion efficiency under current technical conditions. 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 existing technology, which has low thermoelectric conversion efficiency.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] In the first aspect, a super-transcritical carbon dioxide hydrogen-power cogeneration system is provided, comprising 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;

[0007] 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;

[0008] 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 generated 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.

[0009] Furthermore, the methanol cracking cyclic hydrogen production device includes a methanol storage tank, a methanol booster pump, a methanol recuperator, a methanol carbon dioxide heat exchanger, a methanol cracking reactor and a first drive 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;

[0010] 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.

[0011] 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 switching 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 in sequence.

[0012] 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 via a pipeline in sequence.

[0013] Furthermore, the hydrogen separation and synthesis gas combustion device includes a gas-liquid separator, a synthesis gas pressure reducing valve, a blower, a combustion chamber, a hydrogen separation switch valve and a third drive 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.

[0014] 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.

[0015] Furthermore, the transcritical CO2 Rankine cycle power generation device includes a CO2 pump, a second CO2 regenerator, a flue gas CO2 heat exchanger, a second CO2 turbine, a CO2 condenser, a first low-temperature water on / off valve, a first generator, and a fourth drive motor. The outlet of the CO2 pump is connected to the cold-end inlet and outlet of the second CO2 regenerator and the cold-end inlet of the flue gas CO2 heat exchanger via a pipeline, and the cold-end outlet of the flue gas CO2 heat exchanger is connected to the inlet of the second CO2 turbine via a pipeline.

[0016] 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.

[0017] 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.

[0018] Furthermore, the Rankine cycle power generation device includes 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 on-off valve, a fifth drive motor, and a second generator. 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;

[0019] 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.

[0020] In a second aspect, a super transcritical carbon dioxide hydrogen power cogeneration method is provided, wherein the method is performed using the system described above, comprising:

[0021] When industrial production generates medium and low temperature industrial waste heat, start the system top cycle and system bottom cycle;

[0022] After starting the system top circulation and the system bottom circulation, opening each switch valve and the synthesis gas pressure reducing valve in sequence;

[0023] The activated system top cycle is used to obtain synthesis gas of hydrogen, carbon monoxide and methanol vapor, and to preheat the methanol liquid, realizing the conversion of medium and low temperature industrial waste heat into high-grade chemical energy;

[0024] Through the medium and low temperature industrial flue gas fluid, heat energy is provided to the supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device to complete the supercritical carbon dioxide reverse Brayton cycle;

[0025] 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 converted into fuel and fully burned. The combustion product is used as the driving heat source for the transcritical CO2 Rankine cycle and the organic Rankine cycle;

[0026] By utilizing the activated system bottom cycle, the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle are completed in sequence to achieve waste heat recovery.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This system uses a supercritical carbon dioxide reverse Brayton cycle to heat and upgrade low-temperature industrial waste heat, thereby increasing its thermal energy potential. 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 produce synthesis gas. This process converts low-grade thermal energy into the chemical energy of high-grade hydrogen and other synthesis gases through the methanol cracking chemical reaction, allowing low-temperature industrial waste heat and compression heat to be fully and efficiently utilized. Furthermore, through the hydrogen separation and synthesis gas combustion unit, synthesis gases such as hydrogen, unreacted methanol, and carbon monoxide are separated, not only obtaining clean hydrogen energy but also reducing the combustion temperature of the synthesis gas in the combustion unit, thereby reducing the cost of the combustion chamber. Finally, the transcritical carbon dioxide Rankine cycle coupled with the organic Rankine cycle is used to recover the waste heat from the flue gas at the combustor outlet and generate electricity, which not only increases the net electrical power output of the system but also improves the thermoelectric conversion efficiency, achieving efficient cascade recovery and utilization of thermal energy.

[0029] 2. 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, low-grade thermal energy can be converted into chemical energy of high-grade hydrogen and other synthesis gas through the methanol cracking chemical reaction, so that low-temperature industrial waste heat and compression heat energy can be fully and efficiently utilized.

[0030] 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.

[0031] 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.

[0032] 5. The hydrogen separation and synthesis gas combustion unit separates hydrogen, unreacted methanol, carbon monoxide and other synthesis gases, 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.

[0033] 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

[0034] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the super transcritical carbon dioxide hydrogen power cogeneration system provided by the present invention;

[0036] Figure 2 A flow chart of the super-transcritical carbon dioxide hydrogen power cogeneration method provided by the present invention;

[0037] The following are the components: 1. Methanol storage tank; 2. Methanol booster pump; 3. Methanol recuperator; 4. Methanol-CO2 heat exchanger; 5. Methanol cracking reactor; 6. Gas-liquid separator; 7. Syngas pressure reducing valve; 8. Fan; 9. Combustion chamber; 10. CO2 compressor; 11. First CO2 turbine; 12. Industrial waste heat exchanger; 13. First CO2 regenerator; 14. CO2 pump; 15. Second CO2 regenerator; 16. Flue gas-CO2 heat exchanger; 17. Second CO2 turbine 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

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0039] 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 as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0040] 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, it does not need to be further defined or explained in subsequent drawings.

[0041] In the description of the embodiments of the present invention, it should be noted that if the terms "upper," "lower," "horizontal," "inner," etc. appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the inventive product is typically placed when in use. These terms are merely for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first," "second," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0042] 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", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0043] Currently, the main technologies for utilizing medium- and low-temperature industrial waste heat include heat pump technology, organic Rankine cycle power generation technology, and Kalina cycle power generation technology. Heat pump technology can be divided into two types based on user needs: Type I heat pumps convert a small amount of high-temperature heat into a large amount of low-temperature thermal energy, while Type II heat pumps heat and upgrade a large amount of low-temperature thermal energy into a small amount of high-temperature thermal energy, thereby increasing the potential for thermal energy utilization. However, these technologies inherently degrade high-quality electrical energy into low-quality thermal energy, failing to improve energy quality. Among thermoelectric conversion technologies, Organic Rankine cycle power generation technology and Kalina cycle power generation technology have been widely researched and applied due to their wide applicability, high stability, and simple structure. However, due to the low thermal quality of low-temperature waste heat, these technologies suffer from low thermoelectric conversion efficiency under current technical conditions.

[0044] In order to solve the above technical defects, the inventors provide a super transcritical carbon dioxide hydrogen power cogeneration system and method.

[0045] The present invention is described in further detail below with reference to the accompanying drawings:

[0046] like Figure 1 As shown, in a first aspect of an embodiment of the present invention, a super-transcritical carbon dioxide hydrogen-power cogeneration system is provided, comprising 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, The supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device is used as the second type of heat pump to heat and upgrade industrial low-temperature waste heat, providing medium and high temperature thermal energy for methanol cracking and 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-grade 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.

[0047] The supercritical carbon dioxide reverse Brayton cycle waste heat upgrading device includes 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 on-off valve V2. The outlet of the carbon dioxide compressor 10 is connected to the hot end inlet of the methanol cracking reactor 5 via a pipeline. 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 via pipelines. The carbon dioxide compressor 10 and the first carbon dioxide regenerator 13 are connected to the 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 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 via pipelines. 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. The industrial waste heat on-off valve V2 is sequentially connected to the hot end inlet and outlet of the industrial waste heat exchanger 12 via pipelines. 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 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.

[0048] The hydrogen separation and synthesis gas combustion device includes a gas-liquid separator 6, a synthesis gas pressure reducing valve 7, a blower 8, a combustion chamber 9, a hydrogen separation on-off 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, specifically to the hot end outlet of the methanol recuperator 3. The left outlet of the gas-liquid separator 6 is connected to the inlet of the methanol storage tank 1 via a pipeline. The upper right outlet of the gas-liquid separator 6 is connected to the hydrogen separation on-off valve V1 via a pipeline. 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. The inlet of the blower 8 is connected to the atmosphere, the outlet of the blower 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 loop via 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, ensuring that the combustion chamber 9 can obtain sufficient air supply, ensuring that the flame in the combustion chamber 9 burns stably, reducing fluctuations and unstable factors in the combustion process, and thus improving the stability of the entire system.

[0049] The transcritical CO2 Rankine cycle power generation device includes a CO2 pump 14, a second CO2 regenerator 15, a flue gas CO2 heat exchanger 16, a second CO2 turbine 17, a CO2 condenser 18, a first low-temperature water on / off valve V3, a first generator 26, and a fourth drive motor 27. The outlet of the CO2 pump 14 is connected to the cold-end inlet and outlet of the second CO2 regenerator 15 and the cold-end inlet of the flue gas CO2 heat exchanger 16 via a pipeline. The cold-end outlet of the flue gas CO2 heat exchanger 16 is connected to the inlet of the second CO2 turbine 17 via a pipeline. The outlet of the second CO2 turbine 17 is connected to the hot-end inlet and outlet of the second CO2 regenerator 15 and the hot-end inlet of the CO2 condenser 18 via a pipeline. The hot-end outlet of the CO2 condenser 18 is connected to the inlet of the CO2 pump 14 via a pipeline. The first low-temperature water on / off valve V3 is connected to the cold-end inlet and outlet of the CO2 condenser 18 via pipelines. The hot-end inlet and outlet of the flue gas CO2 heat exchanger 16 are connected to the upper outlet of the combustion chamber 9 and the organic Rankine power generation device, respectively, via 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 on-off 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 via a pipeline in sequence; 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 via a pipeline in sequence. The hot end inlet and outlet of the flue gas-organic working fluid heat exchanger 20 are connected to the transcritical carbon dioxide Rankine cycle power generation device and the atmospheric environment, respectively. The second low-temperature water on-off valve V4 is connected to the cold end inlet and outlet of the organic working fluid condenser 22 via a pipeline in sequence. First, 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 the 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 transcritical carbon dioxide Rankine cycle is coupled with the organic Rankine cycle to recover the waste heat of the flue gas at the combustion chamber outlet and generate electricity, 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.

[0050] In a second aspect, an embodiment of the present invention provides a super-transcritical carbon dioxide hydrogen cogeneration method, the method being performed using the system described above, comprising:

[0051] S101. When industrial production generates medium- and low-temperature industrial waste heat, start the system top cycle and the system bottom cycle; for example, when industrial production generates medium- and low-temperature industrial waste heat, 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 first, and then the system bottom cycle consisting of the hydrogen separation and synthesis gas combustion device, the transcritical carbon dioxide Rankine cycle power generation device and the organic Rankine cycle power generation device is started in sequence.

[0052] 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; for example, 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.

[0053] S103. Utilize the started system top cycle to obtain synthesis gas of hydrogen, carbon monoxide and methanol vapor, and preheat the methanol liquid, thereby realizing the conversion of medium and low temperature industrial waste heat into high-grade chemical energy. For example, 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. After absorbing heat, the methanol liquid 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 undergoes a methanol cracking reaction to generate synthesis gas of hydrogen, carbon monoxide and methanol vapor. The synthesis gas passes through the hot end of the methanol recuperator 3 to preheat the methanol liquid at the outlet of the methanol booster pump 2, thereby realizing the conversion of medium and low temperature industrial waste heat into high-grade chemical energy.

[0054] 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, thereby completing the supercritical carbon dioxide reverse Brayton cycle. For example, the medium- and low-temperature industrial flue gas fluid is used as a low-temperature heat source and passes 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 sequence for heat exchange. At the same time, the second drive motor 24 uses electrical 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 sequence 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 heat energy inside the system. Subsequently, the high-pressure supercritical carbon dioxide fluid at a certain temperature enters the first carbon dioxide turbine 11 to perform work, thereby completing the supercritical carbon dioxide reverse Brayton cycle.

[0055] 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, and the generated hydrogen is used for transportation or sale. The remaining synthesis gas forms fuel and is fully burned. The combustion products are used as the driving heat source for the transcritical carbon dioxide Rankine cycle and the organic Rankine cycle. For example, the low-temperature and high-pressure synthesis gas mixture at the hot end outlet of the methanol recuperator 3 is then separated into gas and liquid by the gas-liquid separator 6. The separated methanol liquid enters the methanol storage tank 1 for the methanol cracking cycle process. 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 deliver a certain amount of air into the combustion chamber 9 to ensure that the synthesis gas fuel is fully burned.

[0056] S106. Utilize the started system bottom cycle to sequentially complete the transcritical CO2 Rankine cycle and the organic Rankine cycle to realize waste heat recovery. For example, the high-temperature flue gas at the outlet of the combustion chamber 9 first enters the hot end of the flue gas CO2 heat exchanger 16 to provide heat energy for the transcritical CO2 Rankine cycle power generation device. At the same time, the fourth drive motor 27 drives the CO2 pump 14 to pressurize the CO2 liquid. Subsequently, the high-pressure and low-temperature CO2 liquid sequentially enters the second CO2 regenerator 15 and the cold end of the flue gas CO2 heat exchanger 16 to absorb heat. Subsequently, the high-temperature and high-pressure supercritical CO2 fluid enters the second CO2 turbine 17 to perform work and drive the first generator 26 to generate electricity. The low-pressure and medium-temperature supercritical CO2 fluid at the outlet of the second CO2 turbine 17 enters the hot end of the second CO2 regenerator 15 and the low-temperature and low-pressure supercritical CO2 fluid after heat release. The carbon dioxide condenser 18 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 heat 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. Subsequently, 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. Subsequently, the superheated organic working fluid steam enters the organic working fluid turbine 21 to perform work and drive the second generator 29 to generate electricity. Subsequently, 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, and realizes the efficient cascade utilization of thermal energy.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit its scope of protection. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that after reading the present invention, those skilled in the art may 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 scope of protection of the pending claims of the invention.

Claims

1. A super transcritical carbon dioxide hydrogen power cogeneration system, characterized in that: It includes 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 generated 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, wherein: 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) 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) 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, wherein: 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), wherein 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, and 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, wherein: 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 drive motor (25). The upper inlet of the gas-liquid separator (6) is connected to the methanol cracking cycle hydrogen production device through a pipeline, the upper right outlet of the gas-liquid separator (6) is connected to the hydrogen separation switch valve (V1) through 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) through 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) through a pipeline, the lower 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 outlet of the combustion chamber (9) is connected to the system bottom circulation through a pipeline.

7. The system according to claim 1, wherein: 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, wherein: 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 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. 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 circulation and the system bottom circulation, opening each switch valve and the synthesis gas pressure reducing valve in sequence; The activated system top cycle is used to obtain synthesis gas of hydrogen, carbon monoxide and methanol vapor, and to preheat the methanol liquid, realizing 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, heat 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 converted into fuel and fully burned. The combustion product is used as the driving heat source for the transcritical CO2 Rankine cycle and the organic Rankine cycle; By utilizing the activated 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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