Hydrogen energy type carnot cell system and working method thereof

Abstract

The application provides a working method of a hydrogen energy type Carnot battery system. In a power storage mode, residual energy enters a hydrogen energy system for water hydrolysis to produce hydrogen; hydrogen-containing fuel gas and oxygen are stored; in a power supply mode, in a Brayton cycle, rare gas working medium enters a compressor to be compressed into high-pressure gas, the high-pressure gas, oxygen and fuel gas are mixed to obtain mixed gas and are combusted in a combustion chamber, the mixed working medium enters a turbine to do work and generate electricity, enters a waste heat boiler to isobarically release heat, and separated rare gas working medium enters the compressor again; in a Rankine cycle, liquid working medium enters the waste heat boiler to become steam, the steam is superheated and then enters a steam turbine to adiabatically expand to do work and generate electricity, enters a condenser to condense into liquid, is adiabatically compressed by a working medium pump, enters the waste heat boiler to repeat the above process. The application also provides a battery system. The method of the application realizes hydrogen energy storage of excess electricity by water electrolysis to produce hydrogen, and converts hydrogen energy into electricity by using a Brayton Rankine cycle.

Description

Technical Field

[0001] This invention relates to a hydrogen-powered Carnot battery system and its operating method. Background Technology

[0002] Green energy, represented by solar, wind, and hydropower, boasts advantages such as environmental friendliness and inexhaustibility. However, due to the influence of weather, seasons, and sunlight, it is difficult to provide stable energy output, making it challenging to match the power grid's output. Therefore, employing energy storage technologies to trade space for time is a better solution. Electrolysis or thermochemical hydrogen production is an advanced energy storage method that effectively utilizes excess electricity and heat. Hydrogen energy is a chemical energy storage method. Compared to lithium batteries, hydrogen combustion produces only water, making it a zero-carbon energy source. Methane is a low-carbon energy source, and hydrogen fuel cells offer advantages such as high energy density and low environmental pollution, providing a stable and green power supply to the grid.

[0003] The applicant's prior patent application (Heat Pump-Hydrogen Composite Energy Storage and Power Generation Method and Device 202110804742.X) discloses an energy storage method and device for a hydrogen composite energy system. It utilizes a reversible Brayton cycle as the energy storage and power generation principle, employing a reverse Brayton cycle for energy storage and a Brayton cycle for power generation. In this process, superheated gas from the compressor outlet is used to heat hydrogen produced through electrolysis. The high-temperature gas then heats molten salt, completing molten salt energy storage, which is a physical energy storage and power generation solution. The disadvantage of this technical solution is that molten salt energy storage requires large-scale production to reduce costs, and it necessitates large, corrosion-resistant, high-temperature insulated molten salt storage tanks, lacking portability. Summary of the Invention

[0004] The purpose of this invention is to provide a hydrogen-powered Carnot battery system and its operating method to overcome the disadvantages of traditional fuel cells, such as high cost and small scale, while solving the problems of wind curtailment and solar curtailment in photovoltaic and wind power generation.

[0005] To achieve the above objectives, the present invention provides a method for operating a hydrogen-powered Carnot battery system, characterized in that it includes the following modes:

[0006] (1) Hydrogen production and energy storage mode: The surplus energy enters the hydrogen energy system to produce hydrogen by hydrolysis, and the water is decomposed into hydrogen and oxygen; based on the hydrogen, hydrogen-containing fuel gas is obtained or it is directly used as hydrogen-containing fuel gas, and the hydrogen-containing fuel gas and oxygen are respectively pressurized and stored in the energy storage system.

[0007] (2) Power supply modes: including Brayton cycle and Rankine cycle;

[0008] In the Brayton cycle, the gaseous working fluid enters the compressor and is compressed into high-pressure gas. The high-pressure gas, oxygen, and hydrogen-containing fuel gas are mixed in a gas mixing device to obtain a mixed gas. The mixed gas is burned in the combustion chamber to raise the temperature at isobaric pressure, obtaining a mixed working fluid. The mixed working fluid enters the turbine to generate electricity, and then enters the waste heat boiler to release heat at isobaric pressure. The gaseous working fluid obtained by separating the mixed working fluid then enters the compressor again, and the cycle repeats. The water obtained by separating the mixed working fluid through a gas-water separator enters the hydrogen energy system.

[0009] In the Rankine cycle, liquid phase change working fluid enters the waste heat boiler to absorb heat and become steam. After being superheated, the steam phase change working fluid enters the turbine for adiabatic expansion to generate electricity. Then, it enters the condenser for isobaric heat release, causing the steam phase change working fluid to condense into liquid. Subsequently, it is adiabatic compressed by the working fluid pump, and the liquid phase change working fluid re-enters the waste heat boiler to repeat the above process.

[0010] The hydrogen-containing fuel gas is hydrogen, or the fuel gas is methane produced from hydrogen through a methanation reaction in a hydrogen production and storage mode.

[0011] The hydrogen-containing fuel gas is hydrogen, and the hydrogen storage method includes one of the direct hydrogen storage methods such as high-pressure gaseous hydrogen storage, low-temperature / organic liquid hydrogen storage, and solid material hydrogen storage.

[0012] The hydrogen-containing fuel gas is methane, and the mixed working fluid is further separated to obtain carbon dioxide, which is then used in a methanation reaction to produce methane under a hydrogen production and energy storage mode.

[0013] The working gaseous medium of the Brayton cycle includes air, argon, nitrogen, helium, neon, krypton, xenon, radon, or carbon dioxide.

[0014] The hydrogen energy system includes one of a water electrolysis hydrogen production system and a thermochemical water electrolysis hydrogen production system, wherein the thermochemical water electrolysis hydrogen production system is one of an alkaline electrolysis system, a solid polymer electrolyte electrolysis system, or a solid oxide electrolysis cell system.

[0015] On the other hand, the present invention provides a hydrogen-powered Carnot battery system, comprising:

[0016] A hydrogen production and energy storage system includes: a hydrogen energy system and an energy storage system connected to the hydrogen energy system; the hydrogen energy system is configured to produce hydrogen by water electrolysis, and the energy storage system is configured to obtain hydrogen-containing fuel gas from hydrogen or directly use it as hydrogen-containing fuel gas, and store hydrogen-containing fuel gas and oxygen.

[0017] The power supply system includes the Brayton cycle system and the Rankine cycle system;

[0018] The Brayton cycle system is configured to realize the Brayton cycle of the working fluid, including a compressor, a gas mixing device, a combustion chamber, a turbine, a waste heat boiler, and a gas-liquid separator connected in series along the direction of the working fluid in the Brayton cycle to form a loop. The gas mixing device is connected to the oxygen and hydrogen-containing fuel gas of the energy storage system through other inlets respectively. The gas-liquid separator is connected to the waste heat boiler through its inlet, connected to the compressor through its gas phase outlet, and connected to the hydrogen energy system through its liquid phase outlet.

[0019] The Rankine cycle system is configured to realize a Rankine cycle with a phase change working fluid, including the waste heat boiler, superheater, steam turbine, condenser and working fluid pump connected in series along the direction of the phase change working fluid of the Rankine cycle to form a loop.

[0020] The hydrogen-containing fuel gas is hydrogen, and the hydrogen storage system of the energy storage system is directly connected to the hydrogen outlet of the hydrogen energy system.

[0021] The hydrogen-containing fuel gas is methane produced by the methanation reaction of hydrogen. The methane storage system of the energy storage system is connected to the hydrogen outlet of the hydrogen energy system through the methanation reactor. A carbon dioxide separator is provided between the compressor and the gas-water separator.

[0022] The hydrogen-powered Carnot battery system also includes a heat exchanger, the tube side of which is connected between the working fluid pump and the waste heat boiler, and the shell side of which is connected between the steam turbine and the condenser.

[0023] The hydrogen-powered Carnot battery system of this invention directly utilizes electrolysis to produce hydrogen for energy storage. It converts electrical energy into the chemical energy of hydrogen and then uses the principle of a gas turbine to generate electricity. It is a technology that combines chemical energy storage with physical power generation.

[0024] Compared to existing physical energy storage and power generation technologies that utilize molten salt for energy storage, this invention uses excess electrical energy for hydrogen electrolysis. Since hydrogen energy is a storable intermediate medium, hydrogen energy production and storage are easily miniaturized. Hydrogen or methane storage tanks are also easily miniaturized and mobile. Multiple energy storage centers can be connected together via gas pipelines for power generation. This energy storage method also has the advantages of high efficiency and high energy density, facilitating the construction of large-scale energy storage devices. Hydrogen electrolysis can achieve a near 100% electrical-to-chemical energy conversion efficiency at certain temperatures. High energy storage density can be achieved after hydrogen is pressurized and liquefied. The process of using hydrogen for direct energy storage and generating electricity as a hydrogen-containing gas was discussed. The process of producing natural gas (methane) from hydrogen and storing it, and then using methane as a hydrogen-containing gas for power generation was also considered. During power generation, hydrogen or methane is used as a gas, and power generation is carried out using the principle of gas turbine. The conversion of chemical energy to mechanical energy (electric energy) is achieved through thermodynamic cycle. Large-scale and efficient electrical energy-chemical energy-electric energy conversion can be achieved through Brayton Rankine cycle, which solves the problems of low power and high cost of fuel cells.

[0025] In addition, the method of the present invention utilizes the Brayton cycle to convert the heat of hydrogen combustion into mechanical work and generate electricity during the chemical energy to electrical energy conversion process, achieving efficient heat-work conversion. Then, the waste heat boiler is used to convert the waste heat from the turbine outlet into mechanical work and generate electricity again through the Rankine cycle, which can effectively recover and utilize low-temperature heat energy and generate electricity, further improving the power generation efficiency.

[0026] Furthermore, this invention selects rare gases with monatomic molecules, such as argon, helium, neon, krypton, xenon, and radon, as the working fluid, and transforms the original open-cycle gas turbine into a closed-cycle. The original gas turbine uses air as the working fluid, and the turbine exhaust gas can be directly discharged into the environment. The patent uses rare gases (such as argon) as the working fluid, which is more expensive and therefore needs to be recycled. The gas molecules of these rare gases have low degrees of freedom, so the average molecular energy is lower at the same temperature, resulting in a higher adiabatic index, which is beneficial for us to obtain higher heat-work conversion efficiency. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a hydrogen-powered Carnot battery system (hydrogen type) according to a first embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram of a hydrogen-powered Carnot battery system (methane type) according to a second embodiment of the present invention.

[0029] Figure label:

[0030] 101. Hydrogen production system by water electrolysis; 102. Oxygen storage system; 103. Hydrogen storage system; 104. Methane storage system; 105. Methanation reactor; 1. Compressor; 2. Gas mixing device; 3. Gas mixing device; 4. Combustion chamber; 5. Turbine; 6. Waste heat boiler; 7. Superheater; 8. Steam turbine; 9. Heat exchanger; 10. Condenser; 11. Feed water pump; 12. Gas-water separator; 13. Carbon dioxide separator. Detailed Implementation

[0031] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.

[0032] First embodiment: Hydrogen-based Carnot battery system (hydrogen type) and its working method

[0033] Figure 1 This is a schematic diagram of a hydrogen-powered Carnot battery system according to a first embodiment of the present invention.

[0034] based on Figure 1 The hydrogen-powered Carnot battery system shown includes a hydrogen production and storage mode and a power supply mode.

[0035] (1) In the hydrogen production and energy storage mode, the remaining energy enters the hydrogen energy system to hydrolyze hydrogen, decompose water into oxygen and hydrogen, use hydrogen as hydrogen-containing fuel gas, and store hydrogen-containing fuel gas and oxygen separately under pressure in the energy storage system.

[0036] The energy storage system consists of an oxygen storage system 102 and a hydrogen storage system 103. The oxygen storage system 102 is used to store oxygen, and the hydrogen storage system 103 is used to store hydrogen. The oxygen storage is achieved through pressurization, including gaseous and liquid storage, at a pressure ratio of 10-20.

[0037] The hydrogen storage includes direct hydrogen storage methods such as high-pressure gaseous hydrogen storage, low-temperature / organic liquid hydrogen storage, and solid material hydrogen storage, as well as indirect hydrogen storage methods such as reacting with carbon dioxide to form synthetic natural gas (methane) for storage (see the second embodiment below for details).

[0038] The surplus energy comes from the curtailment of renewable energy or surplus energy from the power grid. The hydrogen energy system includes one of two types: a water electrolysis hydrogen production system and a thermochemical water electrolysis hydrogen production system. The water electrolysis hydrogen production system utilizes surplus energy in the form of electricity, while the thermochemical water electrolysis hydrogen production system directly utilizes surplus energy in the form of heat, such as solar energy or industrial waste heat. The thermochemical water electrolysis hydrogen production system is one of an alkaline electrolysis system, a solid polymer electrolyte electrolysis system, or a solid oxide electrolyzer system. In this embodiment, the hydrogen energy system is an electrically driven water electrolysis hydrogen production system 101, connected to the surplus energy source via a cable for introducing the surplus energy. The water electrolysis hydrogen production system 101 can be an SOEC (solid oxide electrolyzer) system.

[0039] (2) The power supply modes include the Brayton cycle and the Rankine cycle.

[0040] In the Brayton cycle, the rare gas working fluid enters compressor 1 and is compressed into high-pressure gas. This high-pressure gas then combines with stored high-pressure oxygen in the first gas mixing unit 2, and then with hydrogen in the second gas mixing unit 3 to obtain a mixed gas, which enters combustion chamber 4. The mixed gas is burned in combustion chamber 4, causing it to heat up at isobaric pressure. Hydrogen combines with oxygen to produce water, forming a mixed working fluid. This mixed working fluid then enters turbine 5 to perform work and generate electricity. The mixed working fluid exiting turbine 5 enters waste heat boiler 6 to release heat at isobaric pressure. The mixed working fluid then passes through gas-water separator 12 to separate the rare gas working fluid and condensate. The rare gas working fluid re-enters compressor 1 to repeat the above process, thus cyclically repeating the cycle. The condensate, possessing low-temperature waste heat, can be used for heating and enters water electrolysis to produce hydrogen 101. The work performed in the Brayton cycle is used to generate electricity. The work performed in the Brayton cycle includes the difference between the work performed by turbine 5 and the work performed by compressor 1 on the rare gas working fluid; therefore, turbine 5 and compressor 1 are connected to generator G.

[0041] In general, the compression ratio of a gas turbine is around 5-20, while that of an advanced gas turbine compressor is above 25. Here, rare gas is used as the working fluid. Since rare gas is a monatomic gas molecule with a high adiabatic index, the compression ratio of compressor 1 can be controlled within 10 in this invention.

[0042] During this process, the temperature of the high-pressure gas rises after exiting the compressor 1 outlet. κ is the adiabatic index, and π is the compression ratio. During combustion, the temperature of the gas mixture in combustion chamber 4 increases from... Rise to The temperature of the mixed working fluid at the outlet of turbine 5 decreases to The temperature of the mixed working fluid at the outlet of waste heat boiler 6 decreases from T1 to T0.

[0043] In this embodiment, the rare gas working medium of the Brayton cycle is argon, and the mixed working medium is argon containing water. In other embodiments, the working medium of the Brayton cycle includes at least one of air, argon, nitrogen, helium, neon, krypton, xenon, radon, or carbon dioxide.

[0044] To ensure complete combustion of hydrogen, an appropriate excess of oxygen is allowed. After combustion, in addition to water, there is still a small amount of oxygen. Therefore, the molar ratio of the working fluid, hydrogen, and oxygen in the Brayton cycle of the mixed gas entering combustion chamber 4 is maintained at approximately 8:1:0.5.

[0045] The Rankine cycle includes at least a waste heat boiler 6. In the Rankine cycle, liquid phase change fluid enters the waste heat boiler 6 to absorb heat and become steam. After being superheated by the heat exchanger 7, the steam-form phase change fluid enters the turbine 8 for adiabatic expansion to generate electricity. It then enters the condenser 10 to release heat at isobaric pressure, causing the steam-form phase change fluid to condense into liquid. Subsequently, it is adiabaticly compressed by the working fluid pump 11, and the liquid phase change fluid returns to the waste heat boiler 6 to repeat the process, thus continuously cycling. The work done in the Brayton cycle is used to generate electricity. The work done in the Brayton cycle includes the work done by the turbine 8; therefore, the turbine 8 is connected to the generator G.

[0046] In this system, the phase change working fluid in the Rankine cycle is water. After being superheated by heat exchanger 7, the temperature of the phase change working fluid in steam form reaches the steam operating temperature of the thermal power unit (400-600 degrees Celsius, 3-20 MPa).

[0047] In this process, the steam-form phase change working fluid at the outlet of the steam turbine 8 and the liquid phase change working fluid at the outlet of the working fluid pump 11 exchange heat through a heat exchanger 9, thereby reheating the liquid phase change working fluid at the outlet of the working fluid pump 11.

[0048] Accordingly, hydrogen-powered Carnot battery systems include:

[0049] A hydrogen production and energy storage system, which includes a hydrogen energy system and an energy storage system connected to the hydrogen energy system.

[0050] The hydrogen energy system is configured to produce hydrogen through water electrolysis, and the energy storage system is configured to obtain hydrogen-containing fuel gas from hydrogen or directly use it as hydrogen-containing fuel gas, storing the fuel gas and oxygen. In this embodiment, the hydrogen-containing fuel gas is hydrogen, and the hydrogen storage system of the energy storage system is directly connected to the hydrogen outlet of the hydrogen energy system.

[0051] In this embodiment, the hydrogen energy system is a water electrolysis hydrogen production system 101, which can be an SOEC (solid oxide electrolyzer) system. The energy storage system consists of an oxygen storage system 102 and a hydrogen storage system 103.

[0052] The power supply system includes the Brayton cycle system and the Rankine cycle system.

[0053] The Brayton cycle system is configured to realize the Brayton cycle of the working fluid, including a compressor 1, gas mixing devices 2 and 3, a combustion chamber 4, a turbine 5, a waste heat boiler 6, and a gas-liquid separator 12, which are connected in series along the direction of the working fluid in the Brayton cycle to form a loop. One inlet of each of the gas mixing devices 2 and 3 is connected to the compressor 1, and the other inlets are connected to the energy storage system. In this embodiment, the other inlets of the gas mixing devices 2 and 3 are connected to the oxygen storage system 102 and the hydrogen storage system 103, respectively. The gas-liquid separator 12 has one inlet, one gas phase outlet, and one liquid phase outlet. In this embodiment, the gas-liquid separator 12 is connected to the waste heat boiler 6 through its inlet, to the compressor 1 through its gas phase outlet, and to the hydrogen energy system through its liquid phase outlet. Thus, the Brayton cycle of the working fluid is realized.

[0054] The Rankine cycle system is configured to realize a Rankine cycle of phase change working fluid, including a waste heat boiler 6, a superheater 7, a steam turbine 8, a condenser 10, and a working fluid pump 11 connected in series along the direction of the phase change working fluid of the Rankine cycle to form a loop, so as to realize a Rankine cycle of phase change working fluid.

[0055] In addition, the Rankine cycle system may also include a heat exchanger 9, the tube side of which is connected between the working fluid pump 11 and the waste heat boiler 6, and the shell side of which is connected between the steam turbine 8 and the condenser 10.

[0056] Second embodiment: Hydrogen-based Carnot battery system (methane type)

[0057] Figure 2 This is a schematic diagram of a hydrogen-powered Carnot battery system according to a second embodiment of the present invention. The method includes a hydrogen production and storage mode and a power supply mode.

[0058] (1) In the hydrogen production and energy storage mode, the remaining energy enters the hydrogen energy system to hydrolyze hydrogen, decompose water into hydrogen and oxygen, and produce methane through methanation reaction. Then, the methane is used as hydrogen-containing fuel gas, and the oxygen and methane are stored under pressure in the energy storage system consisting of an oxygen storage system and a methane storage system.

[0059] Methanation is a reaction in which hydrogen reduces carbon monoxide and carbon dioxide to produce methane and water in the presence of a catalyst. Because methanation is a strongly exothermic reaction, actual production requires temperature control to balance reaction rate and chemical equilibrium, thus demanding relatively little external energy. Furthermore, after electrolytic hydrogen production, the small molecular weight of hydrogen makes it difficult to store, while methanation facilitates liquefaction and storage. Therefore, using methane as a hydrogen-containing fuel gas is not contradictory to hydrogen production via electrolysis.

[0060] The surplus energy comes from surplus renewable energy or surplus energy from the power grid. The hydrogen energy system includes one of a water electrolysis hydrogen production system and a thermochemical water electrolysis hydrogen production system. The thermochemical water electrolysis hydrogen production system is one of an alkaline electrolysis system, a solid polymer electrolyte electrolysis system, or a solid oxide electrolyzer system. In this embodiment, the hydrogen energy system is an electrically driven electrolysis hydrogen production system, connected to the surplus energy source via a cable for introducing the surplus energy. The water electrolysis hydrogen production system can be an SOEC (solid oxide electrolyzer) system.

[0061] (2) The power supply modes include the Brayton cycle and the Rankine cycle.

[0062] In the Brayton cycle, the rare gas working fluid of the Brayton cycle enters compressor 1 and is compressed into high-pressure gas. Then, the high-pressure gas combines with stored high-pressure oxygen in the first gas mixing device 2, and then mixes with methane in the second gas mixing device 3 before entering the combustion chamber. The mixed gas is burned in the combustion chamber 4, causing the mixed working fluid gas to be heated at isobaric pressure. Methane combines with oxygen to produce water and carbon dioxide, thus obtaining the mixed working fluid. The mixed working fluid then enters turbine 5 to generate electricity. The mixed working fluid at the outlet of turbine 5 enters waste heat boiler 6 to release heat at isobaric pressure. Then, the mixed working fluid passes through gas-water separator 12 and carbon dioxide separator 13 to separate the rare gas working fluid, carbon dioxide, and condensate of the Brayton cycle. The rare gas working fluid obtained from the separation of the mixed working fluid enters compressor 1 again to repeat the above process, thus repeating the cycle in sequence. The water obtained from the separation of the mixed working fluid by the gas-water separator has low-temperature waste heat and can be used for heating. The water enters the water electrolysis hydrogen production system 101. The carbon dioxide obtained from the separation of the mixed working fluid by the carbon dioxide separator 13 is used for the methanation reaction of hydrogen in the hydrogen production and energy storage mode.

[0063] The work done in the Brayton cycle includes the difference between the work done by turbine 5 and the work done by compressor 1 on the rare gas working fluid. Therefore, turbine 5 and compressor 1 are connected to generator G.

[0064] During this process, the temperature of the high-pressure gas rises after exiting the compressor 1 outlet. κ is the adiabatic index, and π is the compression ratio. During combustion, the temperature of the gas mixture in combustion chamber 4 increases from... Rise to The temperature of the mixed working fluid at the outlet of turbine 5 decreases to The temperature of the mixed working fluid at the outlet of waste heat boiler 6 decreases from T1 to T0.

[0065] To ensure complete combustion of hydrogen, an appropriate excess of oxygen is allowed. After combustion, in addition to water, there is still a small amount of oxygen. Therefore, the molar ratio of the working fluid, methane, and oxygen in the Brayton cycle mixture entering combustion chamber 4 is maintained at approximately 8:1:1.

[0066] In this embodiment, the rare gas working medium of the Brayton cycle is argon, and the mixed working medium is argon containing water. In other embodiments, the rare gas working medium of the Brayton cycle includes at least one of air, argon, nitrogen, helium, neon, krypton, xenon, or radon.

[0067] In other embodiments, when the working fluid of the Brayton cycle is carbon dioxide, the carbon dioxide separator 13 can be omitted, and only water vapor needs to be separated. Part of the carbon dioxide enters the compressor 1, and the other part is used for the methanation reaction of hydrogen in the hydrogen production and storage mode.

[0068] In addition, in the power supply mode, methane can first be catalytically converted into hydrogen and then used as hydrogen-containing fuel gas to generate electricity in a Brayton cycle. Specifically, the rare gas working fluid of the Brayton cycle enters compressor 1 and is compressed into high-pressure gas. This high-pressure gas then combines with stored high-pressure oxygen in a first gas mixing device 2, and then with hydrogen obtained from methane production in a second gas mixing device 3 to obtain a mixed gas, which enters combustion chamber 4. The mixed gas is burned in combustion chamber 4, causing it to heat up at isobaric pressure. Hydrogen combines with oxygen to produce water, forming a mixed working fluid. This mixed working fluid then enters turbine 5 to generate electricity. The mixed working fluid exiting turbine 5 enters waste heat boiler 6 to release heat at isobaric pressure. The mixed working fluid then passes through gas-water separator 12 to separate the rare gas working fluid and condensate. The rare gas working fluid re-enters compressor 1 to repeat the above process, thus cycling continuously. The condensate, possessing low-temperature waste heat, can be used for heating and enters water electrolysis to produce hydrogen in system 101. The work done in the Brayton cycle is used to generate electricity. The work done in the Brayton cycle includes the difference between the work done by turbine 5 and the work done by compressor 1 on the rare gas working fluid. Therefore, turbine 5 and compressor 1 are connected to generator G.

[0069] The Rankine cycle includes at least a waste heat boiler 6. In the Rankine cycle, liquid phase change fluid enters the waste heat boiler 6 to absorb heat and become steam. After being superheated by the heat exchanger 7, the steam-form phase change fluid enters the turbine 8 for adiabatic expansion to generate electricity. It then enters the condenser 10 to release heat at equal pressure, causing the steam-form phase change fluid to condense into liquid. Subsequently, it is adiabatically compressed by the working fluid pump 11, and the liquid phase change fluid returns to the waste heat boiler 6 to repeat the process, thus continuously cycling. The work done in the Brayton cycle is used to generate electricity. The work done in the Brayton cycle includes the work done by the turbine 8; therefore, the turbine 8 is connected to the generator G.

[0070] In this system, the phase change working fluid in the Rankine cycle is water. After being superheated by heat exchanger 7, the temperature of the phase change working fluid in steam form reaches the steam operating temperature of the thermal power unit (400-600 degrees Celsius, 3-20 MPa).

[0071] In this process, the steam-form phase change working fluid at the outlet of the steam turbine 8 and the liquid phase change working fluid at the outlet of the working fluid pump 11 exchange heat through a heat exchanger 9, thereby reheating the liquid phase change working fluid at the outlet of the working fluid pump 11.

[0072] Accordingly, hydrogen-powered Carnot battery systems include:

[0073] A hydrogen production and energy storage system, which includes a hydrogen energy system and an energy storage system connected to the hydrogen energy system.

[0074] The hydrogen energy system is configured to produce hydrogen through water electrolysis, and the energy storage system is configured to obtain hydrogen-containing fuel gas, i.e., methane, from hydrogen, and store the hydrogen-containing fuel gas and oxygen. In this embodiment, the hydrogen-containing fuel gas is methane produced from hydrogen through a methanation reaction. The energy storage system includes an oxygen storage system 102 and a methane storage system 104. The methane storage system 104 is connected to the hydrogen outlet of the hydrogen energy system through a methanation reactor 105.

[0075] In this embodiment, the hydrogen energy system is a water electrolysis hydrogen production system 101, which can be an SOEC (solid oxide electrolyzer) system.

[0076] The power supply system includes the Brayton cycle system and the Rankine cycle system.

[0077] The Brayton cycle system is configured to realize the Brayton cycle of the working fluid. It includes a compressor 1, gas mixing devices 2 and 3, a combustion chamber 4, a turbine 5, a waste heat boiler 6, a gas-water separator 12, and a carbon dioxide separator 13, which are connected in series along the direction of the working fluid in the Brayton cycle to form a loop. One inlet of each of the gas mixing devices 2 and 3 is connected to the compressor 1, and the other inlets are connected to the energy storage system. In this embodiment, the other inlets of the gas mixing devices 2 and 3 are connected to the oxygen storage system 102 and the methane storage system 104 of the energy storage system, respectively. This realizes the Brayton cycle of the working fluid.

[0078] The gas-liquid separator 12 has one inlet, one gas phase outlet, and one liquid phase outlet. In this embodiment, the gas-liquid separator 12 is connected to the waste heat boiler 6 through its inlet, to the compressor 1 through its gas phase outlet, and to the hydrogen energy system through its liquid phase outlet. The carbon dioxide separator 13 has its carbon dioxide outlet connected to the hydrogen energy system, and its other outlet connected to the compressor 1.

[0079] The Rankine cycle system includes a waste heat boiler 6, a superheater 7, a steam turbine 8, a condenser 10, and a working fluid pump 11 connected in series along the direction of the phase change working fluid of the Rankine cycle to form a loop, so as to realize the Rankine cycle of the phase change working fluid.

[0080] In addition, the Rankine cycle system may also include a heat exchanger 9, the tube side of which is connected between the working fluid pump 11 and the waste heat boiler 6, and the shell side of which is connected between the steam turbine 8 and the condenser 10.

[0081] The hydrogen-powered Carnot battery system of this invention directly utilizes electrolysis to produce hydrogen for energy storage. It converts electrical energy into the chemical energy of hydrogen and then uses the principle of a gas turbine to generate electricity. It is a technology that combines chemical energy storage with physical power generation.

[0082] Compared to existing physical energy storage and power generation technologies that utilize molten salt for energy storage, this invention uses excess electrical energy for hydrogen electrolysis. Since hydrogen energy is a storable intermediate medium, hydrogen energy production and storage are easily miniaturized. Hydrogen or methane storage tanks are also easily miniaturized and mobile. Multiple energy storage centers can be connected together via gas pipelines for power generation. This energy storage method also boasts high efficiency and high energy density, facilitating the construction of large-scale energy storage devices. Hydrogen electrolysis can achieve a near 100% electrical-to-chemical energy conversion efficiency at certain temperatures. High energy storage density can be achieved after hydrogen is pressurized and liquefied. The process of using hydrogen for direct energy storage and generating electricity as a hydrogen-containing gas was discussed. The process of producing natural gas (methane) from hydrogen and storing it, and then using methane as a hydrogen-containing gas for power generation was also considered. During power generation, hydrogen or methane is used as a hydrogen-containing gas, and power is generated using the principle of a gas turbine. The conversion of chemical energy to mechanical energy (electrical energy) is achieved through a thermodynamic cycle. Large-scale and efficient electrical energy-chemical energy-electrical energy conversion can be achieved through the Brayton Rankine cycle, which solves the problems of low power and high cost of fuel cells.

[0083] In addition, the method of the present invention utilizes the Brayton cycle to convert the heat of hydrogen combustion into mechanical work and generate electricity during the chemical energy to electrical energy conversion process, achieving efficient heat-work conversion. Then, the waste heat boiler is used to convert the waste heat from the turbine outlet into mechanical work and generate electricity again through the Rankine cycle, which can effectively recover and utilize low-temperature heat energy and generate electricity, further improving the power generation efficiency.

[0084] Furthermore, this invention selects rare gases with monatomic molecules, such as argon, helium, neon, krypton, xenon, and radon, as the working fluid, and transforms the original open-cycle gas turbine into a closed-cycle. The original gas turbine uses air as the working fluid, and the turbine exhaust gas can be directly discharged into the environment. The patent uses rare gases (such as argon) as the working fluid, which is more expensive and therefore needs to be recycled. The gas molecules of these rare gases have low degrees of freedom, so the average molecular energy is lower at the same temperature, resulting in a higher adiabatic index, which is beneficial for us to obtain higher heat-work conversion efficiency.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A method for operating a hydrogen-powered Carnot battery system, characterized in that, It includes the following modes: (1) Hydrogen production and energy storage mode: The surplus energy enters the hydrogen energy system to produce hydrogen by water electrolysis, and decomposes water into hydrogen and oxygen; hydrogen-containing gas is obtained from hydrogen or it is directly used as hydrogen-containing gas, and the hydrogen-containing gas and oxygen are respectively pressurized and stored in the energy storage system; the surplus energy is the abandoned electricity from renewable energy sources or the surplus energy from the power grid, and the hydrogen energy system is a water electrolysis hydrogen production system. (2) Power supply modes: including Brayton cycle and Rankine cycle; In the Brayton cycle, the rare gas working fluid enters the compressor and is compressed into a high-pressure gas. The high-pressure gas, oxygen, and hydrogen-containing fuel gas are mixed in a gas mixing device to obtain a mixed gas. The mixed gas is burned in the combustion chamber to raise the temperature at isobaric pressure, obtaining a mixed working fluid. The mixed working fluid enters the turbine to perform work and generate electricity, and enters the waste heat boiler to release heat at isobaric pressure. Then, the rare gas working fluid obtained from the separation of the mixed working fluid enters the compressor again to repeat the above process. The water obtained by the gas-water separator of the mixed working fluid enters the hydrogen energy system. The work done in the Brayton cycle includes the difference between the work done by the turbine and the work done by the compressor on the rare gas working fluid. Therefore, the turbine and compressor are connected to the generator. In the Rankine cycle, liquid phase change working fluid enters a waste heat boiler to absorb heat and become steam. After being superheated, the steam enters a turbine for adiabatic expansion to perform work and generate electricity. Then, it enters a condenser to release heat at isobaric pressure, causing the steam to condense back into liquid. Subsequently, it is adiabatically compressed by a working fluid pump, and the liquid working fluid returns to the waste heat boiler to repeat the above process. The work done in the Rankine cycle includes the work done by the turbine, therefore the turbine is connected to the generator.

2. The operating method of the hydrogen-powered Carnot battery system according to claim 1, characterized in that, The hydrogen-containing fuel gas is hydrogen, or the hydrogen-containing fuel gas is methane produced from hydrogen through a methanation reaction in a hydrogen production and storage mode.

3. The operating method of the hydrogen-powered Carnot battery system according to claim 2, characterized in that, The hydrogen-containing fuel gas is hydrogen, and the hydrogen storage method includes one of the direct hydrogen storage methods such as high-pressure gaseous hydrogen storage, low-temperature / organic liquid hydrogen storage, and solid material hydrogen storage.

4. The operating method of the hydrogen-powered Carnot battery system according to claim 2, characterized in that, The hydrogen-containing fuel gas is methane, and the mixed working fluid is further separated to obtain carbon dioxide, which is then used in a methanation reaction to produce methane under a hydrogen production and energy storage mode.

5. The operating method of the hydrogen-powered Carnot battery system according to claim 1, characterized in that, The rare gas working medium of the Brayton cycle includes argon, helium, neon, krypton, xenon, and radon.

6. A hydrogen-powered Carnot battery system, characterized in that, include: A hydrogen production and storage system, comprising: a hydrogen energy system and an energy storage system connected to the hydrogen energy system; The hydrogen energy system is configured to produce hydrogen through water electrolysis, and the energy storage system is configured to obtain hydrogen-containing fuel gas from hydrogen or directly use it as hydrogen-containing fuel gas, and store the hydrogen-containing fuel gas and oxygen; the surplus energy comes from the abandoned electricity from renewable energy sources or the surplus energy from the power grid, and the hydrogen energy system is a water electrolysis hydrogen production system; The power supply system includes the Brayton cycle system and the Rankine cycle system; The Brayton cycle system is configured to realize the Brayton cycle of the working fluid, including a compressor, a gas mixing device, a combustion chamber, a turbine, a waste heat boiler, and a gas-liquid separator connected in series along the direction of the working fluid in the Brayton cycle to form a loop. The gas mixing device is connected to the oxygen and hydrogen-containing fuel gas of the energy storage system through other inlets, respectively. The gas-liquid separator is connected to the waste heat boiler through its inlet, to the compressor through its gas phase outlet, and to the hydrogen energy system through its liquid phase outlet. The turbine is configured to generate electricity. The work done externally in the Brayton cycle includes the difference between the work done by the turbine and the work done by the compressor on the rare gas working fluid. Therefore, the turbine and compressor are connected to the generator. The Rankine cycle system is configured to realize a Rankine cycle with a phase change working fluid, including a waste heat boiler, a superheater, a steam turbine, a condenser, and a working fluid pump connected in series along the direction of the phase change working fluid in the Rankine cycle to form a loop. The steam turbine is configured to perform work and generate electricity. The work performed externally in the Rankine cycle includes the work performed externally by the steam turbine, therefore the steam turbine is connected to the generator.

7. The hydrogen-powered Carnot battery system according to claim 6, characterized in that, The hydrogen-containing fuel gas is hydrogen, and the hydrogen storage system of the energy storage system is directly connected to the hydrogen outlet of the hydrogen energy system.

8. The hydrogen-powered Carnot battery system according to claim 6, characterized in that, The hydrogen-containing fuel gas is methane prepared from hydrogen through a methanation reaction, and the methane storage system of the energy storage system is connected to the hydrogen outlet of the hydrogen energy system through a methanation reactor. Furthermore, a carbon dioxide separator is provided between the compressor and the gas-water separator.

9. The hydrogen-powered Carnot battery system according to claim 6, characterized in that, It also includes a heat exchanger, the tube side of which is connected between the working fluid pump and the waste heat boiler, and the shell side of which is connected between the steam turbine and the condenser.

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