Hydrogen energy and natural gas differential pressure power generation combined cycle energy utilization system

Abstract

The invention discloses a hydrogen energy and natural gas differential pressure power generation combined cycle energy utilization system, and relates to the technical field of natural gas excess pressure recycling and hydrogen energy. The hydrogen energy and natural gas differential pressure power generation combined cycle energy utilization system comprises a natural gas differential pressure power generation unit, high-pressure natural gas is converted into low-temperature and low-pressure natural gas after being subjected to power generation through the natural gas differential pressure power generation unit, and electric energy generated by the natural gas differential pressure power generation unit supplies power to a hydrogen production unit; a circulating medium is arranged in an equipment pipeline of the intermediate circulating unit, and cold energy of the low-temperature and low-pressure natural gas is used for providing cold energy for hydrogen storage through the intermediate circulating unit. The natural gas differential pressure power generation technology and the hydrogen energy industry chain are fully combined, and the advantage of achieving gradient utilization of energy is achieved.

Description

Technical Field

[0001] The present invention relates to the field of natural gas excess pressure recovery and utilization and hydrogen energy technology, and in particular to a hydrogen energy and natural gas pressure difference power generation combined cycle energy utilization system. Background Art

[0002] With the growth of global energy demand and the improvement of environmental protection awareness, the development and utilization of clean energy has received more and more attention. As a clean and efficient energy source, the proportion of natural gas in the energy structure has increased year by year. Natural gas is usually transported through pipelines at high pressure. In order to meet the needs of different uses, it must be decompressed at specific stations. The traditional decompression process is often accompanied by a large loss of pressure energy. In the decompression process of natural gas transportation, if the pressure energy is not effectively utilized, it will be wasted. Natural gas pressure difference power generation technology provides a way to recover this energy. The technology can be connected in parallel with the existing natural gas transmission network without the need for large-scale transformation of existing facilities.

[0003] As a clean, efficient and renewable energy, hydrogen energy is regarded as an important part of the future energy system. Hydrogen can be produced in many ways, including water electrolysis, natural gas reforming, biomass conversion, etc. Among them, water electrolysis is one of the cleanest methods. Water electrolysis is the process of producing hydrogen and oxygen by electrolyzing water molecules. This process requires electricity. Water electrolysis hydrogen production technologies include alkaline electrolysis (AWE), proton exchange membrane electrolysis (PEM electrolysis) and solid oxide electrolysis (SOEC). Different types of electrolysis technologies are suitable for different application scenarios.

[0004] Based on this, how to fully combine natural gas pressure difference power generation technology with the hydrogen energy industry chain to achieve cascade utilization of energy is an urgent problem to be solved by technical personnel in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a combined cycle energy utilization system that fully combines natural gas pressure difference power generation technology with the hydrogen energy industry chain.

[0006] To achieve this goal, on the one hand, the hydrogen energy and natural gas pressure difference power generation combined cycle energy utilization system includes a natural gas pressure difference power generation unit, and the high-pressure natural gas is converted into low-temperature and low-pressure natural gas after power generation by the natural gas pressure difference power generation unit. The electric energy generated by the natural gas pressure difference power generation unit supplies power to the hydrogen production unit; it also includes an intermediate circulation unit with a circulating medium inside the equipment pipeline, and the coldness of the low-temperature and low-pressure natural gas is used by the intermediate circulation unit to provide coldness for hydrogen storage.

[0007] Furthermore, it is characterized in that the heat of the high-temperature lubricating oil used by the mechanical equipment is utilized through the intermediate circulation unit to provide heat for releasing hydrogen.

[0008] Furthermore, the intermediate circulation unit includes a cold energy recovery heat exchanger and a hydrogen storage heat exchanger, one side of the cold energy recovery heat exchanger is the low-temperature and low-pressure natural gas, and the other side is the circulating medium flowing out of the liquid storage tank, and the circulating medium is cooled by the low-temperature and low-pressure natural gas through the cold energy recovery heat exchanger; the cooled low-temperature circulating medium enters one side of the hydrogen storage heat exchanger, and the other side of the hydrogen storage heat exchanger is the hydrogen flowing out of the hydrogen production unit; the hydrogen flowing out of the hydrogen production unit is cooled by the low-temperature circulating medium through the hydrogen storage heat exchanger.

[0009] Furthermore, it includes a heat recovery heat exchanger, one side of which is connected to one side of the hydrogen storage heat exchanger, and the circulating medium flowing out of the hydrogen storage heat exchanger enters the heat recovery heat exchanger; the other side of the heat recovery heat exchanger is high-temperature lubricating oil used by mechanical equipment, and the circulating medium flowing out of the hydrogen storage heat exchanger is used to reheat the lubricating oil.

[0010] Furthermore, the intermediate circulation unit includes a heat recovery heat exchanger and a hydrogen release heat exchanger; one side of the heat recovery heat exchanger is the circulating medium flowing out of the liquid storage tank, and the other side of the heat recovery heat exchanger is the high-temperature lubricating oil used by the mechanical equipment. The circulating medium is heated by the high-temperature lubricating oil through the heat recovery heat exchanger, and the heated circulating medium enters one side of the hydrogen release heat exchanger, and the other side of the hydrogen release heat exchanger is low-temperature hydrogen.

[0011] Furthermore, the medium-high temperature circulating medium flowing out of the hydrogen release heat exchanger enters one side of the cold energy recovery heat exchanger through a pipeline, and the other side of the cold energy recovery heat exchanger is the low-pressure natural gas at the outlet of the expander, and the medium-high temperature circulating medium is used to reheat the low-pressure natural gas.

[0012] Furthermore, the intermediate circulation unit includes a circulation pump and a switching valve group. The circulation pump is a one-way pump, and the flow direction of the circulating medium is switched by the switching valve group.

[0013] Furthermore, the intermediate circulation unit comprises a circulation pump, and the circulation pump is a bidirectional pump.

[0014] Furthermore, it also includes an intake air heating heat exchanger, one side of which is connected to the hydrogen pipeline at the outlet of the hydrogen production unit, and the other side of which is connected to the natural gas high-pressure pipeline network before the inlet of the expander, and the high-pressure natural gas at the inlet of the expander is heated by the heat of the hydrogen produced by the hydrogen production unit through the intake air heating heat exchanger. Furthermore, the circulating medium is ethylene glycol aqueous solution or halogenated alkane.

[0015] One of the above technical solutions has the following advantages or beneficial effects: This solution fully combines the natural gas pressure difference power generation technology with the hydrogen energy industry chain, and uses the electricity generated by the natural gas pressure difference power generation technology to produce hydrogen, which improves the system benefits and reduces the cost of hydrogen production. It also uses the coldness of the low-temperature natural gas exported by the natural gas pressure difference power generation system to store hydrogen, which reduces the energy consumption in the hydrogen storage link compared with the existing technology.

[0016] Furthermore, the heat of the high-temperature lubricating oil used by the mechanical equipment in the system is used to provide heat for hydrogen release, which reduces the energy consumption in the hydrogen release link compared with the prior art. Furthermore, the intermediate circulation unit can be used to reheat the low-temperature and low-pressure natural gas at the outlet of the natural gas pressure difference power generation system, which avoids ice blockage of the outlet natural gas compared with the prior art. Furthermore, the intermediate circulation unit and the lubricating oil circulation unit can be used to cool the lubricating oil of the mechanical equipment in the system, which eliminates the cooling water system for reheating the lubricating oil compared with the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of a hydrogen and natural gas pressure difference power generation combined cycle energy utilization system; Figure 2 It is a flow chart of a hydrogen energy and natural gas pressure difference power generation combined cycle energy utilization system using a bidirectional pump in the intermediate cycle.

[0018] In the figure: 1-inlet regulating valve; 2-expander; 3-cold energy recovery heat exchanger; 4-outlet check valve; 5-circulation pump; 6, 7, 8, 9, 17, 20, 21, 22-control valves; 10-heat energy recovery heat exchanger; 11-transmission; 12-generator; 13-lubricating oil station; 14-hydrogen production unit; 15-valve; 16-hydrogen storage heat exchanger; 18-hydrogen release heat exchanger; 19-hydrogen storage device. DETAILED DESCRIPTION

[0019] In order to make the technical problems solved by the present invention, the technical solutions adopted and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0020] The present embodiment provides a hydrogen energy and natural gas pressure difference power generation combined cycle energy utilization system (hereinafter referred to as the system), which couples the hydrogen production, storage and release processes with the natural gas pressure difference power generation unit, efficiently utilizes energy and reduces the cost of hydrogen use.

[0021] like Figure 1-Figure 2 As shown, in this embodiment, hydrogen is produced by using the electric energy of the natural gas pressure difference power generation unit. The natural gas pressure difference power generation unit generates electric energy by using the pressure energy of the natural gas in the high-pressure pipeline network. The natural gas pressure difference power generation unit includes an expander 2, and the inlet of the expander 2 has a control valve 1 for adjusting the flow of the high-pressure natural gas at the inlet of the expander. The control valve 1 is opened and adjusted, and the high-pressure natural gas in the high-pressure pipeline network enters the expander 2 for expansion and power generation. The outlet of the expander 2 is connected to the natural gas downstream pipeline network, and the expanded low-pressure natural gas enters the natural gas downstream pipeline network after treatment for downstream use. The output shaft of the expander 2 is connected to the generator 12, and the high-pressure natural gas enters the expander 2 for expansion and decompression, while driving the generator 12 to generate electricity. A transmission 11 is also provided between the output shaft of the expander 2 and the generator 12, and the transmission 11 is used to control the power generation. The input of the transmission 11 is connected to the output shaft of the expander 2, and the output of the transmission 11 is connected to the generator 12. The power generated by the generator 12 can be connected to the grid and can also be used to power electrical equipment. In this embodiment, the power generated by the generator 12 is used to power the hydrogen production unit 14. The hydrogen production unit 14 is used to produce hydrogen. Preferably, the hydrogen production unit 14 is an electrolytic hydrogen production device.

[0022] like Figure 1 As shown, the system also includes an intermediate cycle. The circulating medium in the intermediate circulation unit is ethylene glycol or freon, preferably ethylene glycol aqueous solution. The intermediate circulation unit includes a circulation pump 5 and a liquid storage tank for storing the circulating medium. The circulation pump 5 provides power for the intermediate circulation unit, and the circulation pump 5 is connected to the liquid storage tank. The coldness of low-temperature and low-pressure natural gas is used to provide coldness for hydrogen storage through the intermediate circulation unit.

[0023] like Figure 1 As shown, in one embodiment, the circulation pump 5 is a one-way pump. Open the control valve 21, the control valve 6 and the control valve 8, and close the remaining valves. The intermediate circulation unit includes a cold energy recovery heat exchanger 3. After the expansion, the low-temperature and low-pressure natural gas flows out from the outlet of the expander 2 and enters the first side of the cold energy recovery heat exchanger 3, and the circulating medium flows out from the circulation pump 5 and enters the second side of the cold energy recovery heat exchanger 3. In the cold energy recovery heat exchanger 3, the cold capacity of the low-temperature and low-pressure natural gas after expansion on the first side is used to reduce the temperature of the circulating medium flowing out of the circulation pump 5. The temperature of the natural gas flowing out of the first side of the cold energy recovery heat exchanger 3 increases, and it can directly enter the natural gas downstream pipeline network for use. There is an outlet check valve 4 between the first side of the cold energy recovery heat exchanger 3 and the downstream pipeline network, and the natural gas at normal temperature and low pressure enters the downstream pipeline network through the outlet check valve 4.

[0024] like Figure 1When storing hydrogen, the outlet of the second side of the cold energy recovery heat exchanger 3 is connected to the heat exchange channel in the hydrogen storage heat exchanger 16, and the low-temperature circulating medium flowing out of the second side of the cold energy recovery heat exchanger 3 enters the heat exchange channel in the hydrogen storage heat exchanger 16. The hydrogen produced by the hydrogen production unit 14 enters the hot side of the hydrogen storage heat exchanger 16 through the valve 15. In the hydrogen storage heat exchanger 16, the low-temperature circulating medium flowing out of the second side of the cold energy recovery heat exchanger 3 serves as a cold source of the hydrogen storage heat exchanger 16 to cool the hydrogen on the hot side of the hydrogen storage heat exchanger 16. The cooled hydrogen enters the downstream for storage or utilization through the control valve 17, Figure 1-Figure 2 The embodiment in which the hydrogen after temperature reduction enters the hydrogen storage device 19 for storage is shown. The circulating medium flowing out of the heat exchange flow channel of the hydrogen storage heat exchanger 16 returns to the circulation pump 5. The circulating medium flowing out of the heat exchange flow channel of the hydrogen storage heat exchanger 16 increases in temperature and enters the liquid storage tank through the circulation pump 5 for the next circulation.

[0025] In the prior art, the hydrogen produced by the hydrogen production unit 14 needs to be cooled by an additional cooling device before storage. In this embodiment, the high-temperature hydrogen produced by the hydrogen production unit 14 is cooled by utilizing the coldness of the low-temperature and low-pressure natural gas after expansion through the intermediate circulation, thereby reducing the energy consumption in the hydrogen storage link and improving the energy utilization efficiency. At the same time, the intermediate circulation unit can be used to reheat the low-temperature and low-pressure natural gas at the outlet of the natural gas pressure difference power generation system, thereby avoiding ice blockage of the outlet natural gas.

[0026] Furthermore, in order to improve the heat exchange efficiency, a heating device is provided on the liquid storage tank for heating the circulating medium, and the heated circulating medium is used for the next circulation.

[0027] In order to further improve the energy utilization efficiency of the system, the inventors found that the temperature of the circulating medium flowing out of the heat exchange flow channel of the hydrogen storage heat exchanger 16 can be used to reheat the lubricating oil used by the mechanical equipment in the system. The system of this embodiment also includes a lubricating oil circulation unit, which is coupled to the intermediate circulation, and the lubricating oil in the mechanical equipment in the system is reheated by the circulating medium through the lubricating oil circulation unit. The lubricating oil circulation unit includes a heat recovery heat exchanger 10 and a lubricating oil station 13. The first side of the heat recovery heat exchanger 10 is connected to the heat exchange flow channel of the hydrogen storage heat exchanger 16, and the circulating medium flowing out of the heat exchange flow channel of the hydrogen storage heat exchanger 16 enters the first side of the heat recovery heat exchanger 10. The inlet of the second side of the heat recovery heat exchanger 10 is connected to the lubricating oil outlet of the mechanical equipment. In the heat recovery heat exchanger 10, the circulating medium is used to reheat the used high-temperature lubricating oil. The outlet of the first side of the heat recovery heat exchanger 10 is connected to the storage tank of the circulating medium through the circulating pump 5. The outlet of the second side of the heat recovery heat exchanger 10 is connected to the lubricating oil station 13, and the lubricating oil station 13 is used to store the lubricating oil after reheating. It can be seen that the lubricating oil circulation unit of this embodiment can not only reheat the lubricating oil, but also heat the circulating medium.

[0028] Further, in this embodiment, the mechanical equipment using lubricating oil in the system may be a transmission 11. The oil outlet of the transmission 11 is connected to the second side of the heat recovery heat exchanger 10, and the used high-temperature lubricating oil flows out of the oil outlet of the transmission 11 and enters the second side of the heat recovery heat exchanger 10. The first side of the heat recovery heat exchanger 10 is connected to the heat exchange flow channel of the hydrogen storage heat exchanger 16, and the circulating medium flowing out of the heat exchange flow channel in the hydrogen storage heat exchanger 16 enters the first side of the heat recovery heat exchanger 10. In the heat recovery heat exchanger 10, the circulating medium flowing out of the heat exchange flow channel of the hydrogen storage heat exchanger 16 is used to reheat the high-temperature lubricating oil used by the equipment. The other end of the second side of the heat recovery heat exchanger 10 is connected to the inlet of the lubricating oil station 13, and the outlet of the lubricating oil station 13 is connected to the oil inlet of the transmission 11. A pump is provided in the lubricating oil station 13 to send the reheated lubricating oil into the transmission for use. The other end of the first side of the heat recovery heat exchanger 10 is connected to the circulation pump 5, and the circulating medium after the temperature is increased returns to the initial state and returns to the circulation pump 5 containing the liquid storage tank for the next circulation.

[0029] In this embodiment, the transmission 11 and the lubricating oil station 13, the first side of the heat recovery heat exchanger 10 and the connecting pipeline valve group form a lubricating oil circulation unit, that is, the heat in the system comes from the lubricating oil in the transmission 11, and of course it can also come from other mechanical equipment using lubricating oil in the system. At this time, the lubricating oil inlet of the mechanical equipment is connected to the liquid outlet of the lubricating oil station 13.

[0030] The mechanical equipment using lubricating oil in the system may also be an expander 2, and the lubricating oil circulation unit is used to reheat the lubricating oil in the expander 2. The oil outlet of the expander 2 is connected to the second side of the heat recovery heat exchanger 10, and the used high-temperature lubricating oil flows out of the oil outlet of the expander 2 and enters the second side of the heat recovery heat exchanger 10. The other end of the second side of the heat recovery heat exchanger 10 is connected to the inlet of the lubricating oil station 13, and the outlet of the lubricating oil station 13 is connected to the oil inlet of the expander 2, and the reheated lubricating oil is pumped to the expander for use.

[0031] like Figure 2As shown, when releasing hydrogen, the control valves 7, 9 and 20 in the intermediate circulation are opened, and the valve 21 and the other valves in the figure are closed. Hydrogen is released by the heat of the high-temperature lubricating oil in the intermediate circulation system. The circulation pump 5 is opened, and the circulating medium enters the first side of the heat recovery heat exchanger 10 through the control valve 7. The second side of the heat recovery heat exchanger 10 is still the high-temperature lubricating oil after use by the mechanical equipment in the system. In the heat recovery heat exchanger 10, the heat of the high-temperature lubricating oil is used to heat the circulating medium on the other side. At the same time, the lubricating oil at the outlet of the second side of the heat recovery heat exchanger 10 enters the lubricating oil station 13 through the pipeline for storage, and the circulating medium is used to reheat the lubricating oil. Valve 21 is closed, and the high-temperature circulating medium flowing out of the outlet of the first side of the heat recovery heat exchanger 10 enters the first side of the hydrogen release heat exchanger 18 through the pipeline. When releasing hydrogen, the outlet control valve 22 of the hydrogen storage device 19 is opened, hydrogen enters the second side of the hydrogen release heat exchanger 18, and the high-temperature circulating medium is used to heat the hydrogen in the hydrogen release heat exchanger 18. The outlet of the first side of the hydrogen release heat exchanger 18 is connected to the second side of the cold energy recovery heat exchanger 3 through a pipeline, and the low-temperature and low-pressure natural gas in the first side of the cold energy recovery heat exchanger 3 is used to further cool the circulating medium. At the same time, the high-temperature circulating medium flowing out of the hydrogen release heat exchanger 18 is used to reheat the low-temperature and low-pressure natural gas. The circulating medium flowing out of the cold energy recovery heat exchanger 3 passes through the control valve 9 and the circulating pump 5 and returns to the circulating medium storage tank.

[0032] Further, if Figure 2 , the circulation pump 5 can use a bidirectional pump. When the circulation pump 5 is a bidirectional pump, the control valves 6, 7, 8 and 9 are removed in the middle circulation. The two ends of the circulation pump 5 are connected to the cold energy recovery heat exchanger 3 and the heat energy recovery heat exchanger 10 through pipelines. When storing hydrogen, the circulating medium flows out from the A port of the circulation pump 5 and returns to the B port after circulation. When releasing hydrogen, the circulating medium flows out from the B port of the circulation pump 5 and returns to the A port after circulation.

[0033] In this embodiment, the cold energy heat exchanger 3 and the hot energy heat exchanger 10, the hydrogen storage heat exchanger 16, and the hydrogen release heat exchanger 18 can be shell and tube heat exchangers, plate fin heat exchangers or other forms of heat exchangers.

[0034] In order to further improve the utilization efficiency of energy, the combined cycle energy utilization system provided in this embodiment is also provided with an intake air heating heat exchanger, and the hydrogen production unit 14 is connected to the hydrogen storage heat exchanger 16 through a hydrogen transmission pipeline, and the valve 15 is located on the hydrogen transmission pipeline. One side of the intake air heating heat exchanger is connected to the hydrogen transmission pipeline at the outlet of the hydrogen production unit 14, and the outlet of this side is connected to the inlet of the hydrogen storage device. The inlet on the other side of the intake air heating heat exchanger is connected to the natural gas high-pressure pipeline network before the inlet of the expander, and the outlet of this side is connected to the inlet of the expander 2. Since the hydrogen produced by electrolysis of water has heat, the heat of the hydrogen produced by the hydrogen production unit is used to heat the high-pressure natural gas at the inlet of the expander through the intake air heating heat exchanger, thereby improving the efficiency of the expander. At the same time, the coldness of the high-pressure natural gas is used to reduce the temperature of the high-temperature hydrogen flowing out of the hydrogen production unit.

[0035] The hydrogen energy and natural gas pressure difference power generation combined cycle energy utilization system of this embodiment has at least the following technical effects: first, it can make full use of the electricity generated by natural gas pressure difference power generation, which can be used to produce hydrogen and connect the surplus electricity to the grid, thereby increasing revenue; second, by using the coldness of the natural gas after cooling and pressure reduction to store hydrogen, it not only avoids ice blockage caused by the export of low-temperature and low-pressure natural gas, but also reduces energy consumption during hydrogen storage. Third, by using the heat generated in the lubricating oil of the mechanical equipment in the system to release hydrogen, it not only avoids the construction of a cooling water system in the system, reduces water consumption, but also reduces energy consumption during hydrogen release.

[0036] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0038] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A hydrogen and natural gas pressure difference power generation combined cycle energy utilization system, characterized in that: It includes a natural gas pressure difference power generation unit, and the high-pressure natural gas is converted into low-temperature and low-pressure natural gas after generating electricity through the natural gas pressure difference power generation unit. The electric energy generated by the natural gas pressure difference power generation unit supplies power to the hydrogen production unit; It also includes an intermediate circulation unit with a circulating medium inside the equipment pipeline, and the intermediate circulation unit uses the cold energy of low-temperature and low-pressure natural gas to provide cold energy for hydrogen storage.

2. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 1 is characterized in that: The intermediate circulation unit utilizes the heat of the high-temperature lubricating oil used by the mechanical equipment to provide heat for releasing hydrogen.

3. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 1 is characterized in that: The intermediate circulation unit includes a cold energy recovery heat exchanger and a hydrogen storage heat exchanger; one side of the cold energy recovery heat exchanger is the low-temperature and low-pressure natural gas, and the other side of the cold energy recovery heat exchanger is the circulating medium flowing out of the liquid storage tank, and the circulating medium is cooled by the low-temperature and low-pressure natural gas through the cold energy recovery heat exchanger; the cooled low-temperature circulating medium enters one side of the hydrogen storage heat exchanger, and the other side of the hydrogen storage heat exchanger is the hydrogen flowing out of the hydrogen production unit, and the hydrogen flowing out of the hydrogen production unit is cooled by the low-temperature circulating medium through the hydrogen storage heat exchanger.

4. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 3 is characterized in that: It includes a heat recovery heat exchanger, one side of which is connected to one side of the hydrogen storage heat exchanger, and the circulating medium flowing out of the hydrogen storage heat exchanger enters the heat recovery heat exchanger; the other side of the heat recovery heat exchanger is high-temperature lubricating oil used by mechanical equipment, and the circulating medium flowing out of the hydrogen storage heat exchanger is used to reheat the lubricating oil.

5. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 2 is characterized in that: The intermediate circulation unit includes a heat recovery heat exchanger and a hydrogen release heat exchanger; one side of the heat recovery heat exchanger is the circulating medium flowing out of the liquid storage tank, and the other side of the heat recovery heat exchanger is the high-temperature lubricating oil used by mechanical equipment. The circulating medium is heated by the high-temperature lubricating oil through the heat recovery heat exchanger, and the heated circulating medium enters one side of the hydrogen release heat exchanger, and the other side of the hydrogen release heat exchanger is low-temperature hydrogen.

6. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 5 is characterized in that: The medium-high temperature circulating medium flowing out of the hydrogen release heat exchanger enters one side of the cold energy recovery heat exchanger through a pipeline. The other side of the cold energy recovery heat exchanger is the low-pressure natural gas at the outlet of the expander. The medium-high temperature circulating medium is used to reheat the low-pressure natural gas.

7. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 1 is characterized in that: The intermediate circulation unit comprises a circulation pump and a switching valve group. The circulation pump is a one-way pump, and the flow direction of the circulation medium is switched by the switching valve group.

8. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 1 is characterized in that: The intermediate circulation unit comprises a circulation pump, and the circulation pump is a bidirectional pump.

9. The hydrogen and natural gas pressure difference power generation combined cycle energy utilization system according to claim 1, characterized in that: It also includes an intake air heating heat exchanger, one side of which is connected to the hydrogen transmission pipeline at the outlet of the hydrogen production unit, and the other side of which is connected to the natural gas high-pressure pipeline network before the inlet of the expander. The heat of the hydrogen produced by the hydrogen production unit is used to heat the high-pressure natural gas at the inlet of the expander through the intake air heating heat exchanger.

10. The hydrogen energy and natural gas pressure difference power generation combined cycle energy utilization system according to any one of claims 1 to 9, characterized in that: The circulating medium is ethylene glycol aqueous solution or halogenated alkane.

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