Long-time energy storage type carbon dioxide geothermal energy power generation system and operation method

Abstract

The long-time energy storage type carbon dioxide geothermal energy power generation system comprises a power generator, the output end of the power generator is sequentially connected with a medium-low pressure turbine and a high-pressure turbine through shafts, and an air inlet of the high-pressure turbine is further connected with a production well through a pipeline A; an exhaust port of the high-pressure turbine and an air inlet of the medium-low-pressure turbine are jointly connected with a heat exchanger through pipelines, and the heat exchanger is further connected with a solar heat collector through a pipeline to form a circulation loop. And an exhaust port of the medium-low pressure turbine is sequentially connected with a first group of soil heat exchangers arranged underground, a compressor, a second group of soil heat exchangers arranged underground and a reinjection well through pipelines. According to the method, the power generation efficiency is effectively improved, certain operation adjusting capacity is achieved, meanwhile, stored heat is merged into the middle-low-pressure turbine for power generation conversion in the power utilization peak period of high electricity price through long-time heat storage and power grid interaction, and the economical efficiency is improved. The invention further discloses an operation method of the long-time energy storage type carbon dioxide geothermal energy power generation system.

Description

Technical Field

[0001] The present invention belongs to the technical field of geothermal power generation equipment, and relates to a long-term energy storage type carbon dioxide geothermal power generation system. The present invention also relates to an operating method of the long-term energy storage type carbon dioxide geothermal power generation system. Background Art

[0002] Geothermal energy refers to thermal energy found in the Earth's rock, soil, fluids, and magma, which can be developed and utilized by humans. It is generally categorized as shallow, medium-deep, and deep geothermal energy, and is a zero-carbon energy source. In recent years, with the advancement of the "dual carbon" goals, the development of geothermal heating technology has been gradually accelerated. Shallow geothermal heating technology has become relatively mature in the field of building heating and has been widely used in the construction of zero-carbon parks and zero-carbon buildings. Medium-deep geothermal heating is in the demonstration stage, while deep geothermal energy utilization is still in the research stage. Geothermal power generation in China has been slow to develop due to factors such as low power generation efficiency and high power generation costs.

[0003] Currently, geothermal energy utilization in my country is primarily focused on heating, with over 93GW of installed capacity for heating and cooling services already built. However, geothermal power generation accounts for a relatively small proportion and is still in its early stages. Commercial applications have long stagnated, with an installed capacity of only around 50MW. This is primarily limited by factors such as low efficiency, high costs, and a lack of detailed resource distribution data. Geothermal power generation technology typically uses water as the working fluid. CO2, a corresponding working fluid, has advantages such as low viscosity, low density, good compressibility, and a low critical point. CO2 geothermal power generation improves efficiency, reduces costs, and reduces equipment size and footprint. It avoids the problems associated with long-term geothermal water extraction, such as geological structural changes, groundwater resource degradation, and land subsidence. Furthermore, a portion of the CO2 can be stored underground during the extraction process, reducing the cost of CO2 geological storage and enabling the simultaneous integration of geothermal resource development and carbon emission reduction.

[0004] Carbon dioxide geothermal power generation was first proposed by Brown in the United States in 2000. It uses CO2 instead of water as a heat extractor to extract heat from deep strata to generate electricity. Heat extraction depths typically exceed 3 km, with temperatures above 150°C at the bottom of the thermal reservoir. Coal-fired CO2 cycle power generation technology has developed rapidly, with China building the world's first 5MW demonstration unit. However, compared with coal-fired supercritical CO2 cycle power generation technology, CO2 geothermal power generation systems are limited by the temperature of deep underground thermal reservoirs, resulting in lower initial power generation parameters and low system cycle efficiency. This technology is still in the research phase, with no engineering demonstration projects. Research on CO2 geothermal power generation systems has primarily focused on physical properties, injection parameters, and rock formations. Operational models are often based on full-load, year-round operation. There is a lack of research on the interaction between CO2 geothermal power generation systems and the power grid, particularly on how to adapt to the fluctuating requirements of large-scale renewable energy grid integration. A significant factor contributing to the long-term stagnation of geothermal power generation in my country is the lack of policy support, such as subsidized electricity prices, which has led to long-term losses for power plants and an unsustainable business model. With the large-scale construction of wind and solar energy and the continuous improvement of the electricity trading market in my country, geothermal power generation systems, while further improving power generation efficiency, also need to have certain operational adjustment capabilities to adapt to the grid dispatching and operation requirements and the electricity spot market trading mechanism, obtain profits by participating in the market-based trading of grid-connected electricity, establish a sustainable business development model, and promote the geothermal power generation industry to gradually mature. Summary of the Invention

[0005] The purpose of the present invention is to provide a long-term energy storage type carbon dioxide geothermal power generation system, which effectively improves power generation efficiency and has a certain operational adjustment capability. At the same time, through long-term heat storage and grid interaction, it can integrate the stored heat into medium and low pressure turbines for power generation conversion during peak electricity consumption periods when electricity prices are high, thereby improving economic efficiency.

[0006] Another object of the present invention is to provide an operating method for a long-term energy storage type carbon dioxide geothermal power generation system.

[0007] The technical solution adopted by the present invention is a long-term energy storage type carbon dioxide geothermal power generation system, including a generator, the output end of the generator is connected to the medium and low pressure turbines and the high pressure turbine in sequence through a shaft, the air inlet of the high pressure turbine is also connected to the production well through pipeline A, the exhaust port of the high pressure turbine and the air inlet of the medium and low pressure turbines are connected to a heat exchanger through a pipeline, the heat exchanger is also connected to a solar collector through a pipeline to form a circulation loop, and the exhaust port of the medium and low pressure turbines is connected to a first group of soil heat exchangers, a compressor, a second group of soil heat exchangers and a reinjection well arranged underground through pipelines.

[0008] Preferably, a separator is further provided on pipeline A between the high-pressure turbine and the production well.

[0009] Preferably, the side of pipeline A located at the separator outlet is also connected to the inlet of the CO2 storage tank through pipeline B, and the outlet of the CO2 storage tank is connected to the air inlet of the medium and low pressure turbine through pipeline C.

[0010] Preferably, pipeline B is further provided with an air storage tank inlet valve, and pipeline C is provided with an air storage tank outlet valve.

[0011] Preferably, it also includes a thermal power plant, and the CO2 generated by the thermal power plant is connected to the air supply compressor and the mineralization reactor through pipeline D and pipeline E respectively. The fly ash generated by the thermal power plant also enters the mineralization reactor through the pipeline. It also includes a mineralized fly ash layer located at the top of the formation, and the outlet of the mineralization reactor is connected to the mineralized fly ash layer.

[0012] Preferably, a parallel bypass is provided on the pipeline between the second group of soil heat exchangers and the reinjection well, and a cooling tower is provided on the bypass.

[0013] Preferably, the heat exchanger is connected to the inlet of the solar collector through a pipe F, and the heat exchanger is connected to the outlet of the solar collector through a pipe G. A bypass is also provided on the pipe F in parallel therewith, and a cold water tank inlet valve, a cold water tank, and a cold water tank outlet valve are sequentially provided on the bypass in the direction from the heat exchanger to the inlet of the solar collector; A bypass is also provided on the pipe G in parallel therewith, and a hot water tank outlet valve, a hot water tank, and a hot water tank inlet valve are sequentially provided on the bypass in the direction from the heat exchanger to the outlet of the solar collector.

[0014] The second technical solution adopted by the present invention is a method for operating a long-term energy storage type carbon dioxide geothermal power generation system, using the above-mentioned long-term energy storage type carbon dioxide geothermal power generation system, specifically implemented according to the following steps: Step 1: Set the low electricity price C0, the high electricity price C1 and the reinjection temperature T0; Step 2: After the CO2 is injected into the reinjection well and absorbs heat deep in the formation, high-temperature and high-pressure CO2 is produced from the production well. At this time: If the electricity price C is lower than the set low electricity price C0, the CO2 enters the CO2 storage tank through pipeline B for storage. When the electricity price rises to the set high electricity price C1, the CO2 enters the medium and low pressure turbines from the CO2 storage tank to generate electricity. Otherwise, CO2 enters the high-pressure turbine through pipeline A to generate power.

[0015] Preferably, after the CO2 enters the high-pressure turbine to generate electricity, the exhaust gas of the high-pressure turbine is heated by a heat exchanger, and after the temperature is increased, it enters the medium- and low-pressure turbines to generate electricity. The exhaust gas of the medium- and low-pressure turbines then passes through the first set of soil heat exchangers, the compressor, and the second set of soil heat exchangers in sequence and is injected into the reinjection well to absorb heat; The principle of the heat exchanger heating the exhaust gas of the high-pressure turbine is as follows: During the day, solar collectors are used to heat water. Part of the hot water enters the heat exchanger to heat CO2, and part enters the hot water tank for storage. At night, the heat stored in the hot water tank during the day is released into the heat exchanger to heat CO2, achieving long-term heating throughout the day.

[0016] Preferably, the exhaust gas from the medium and low pressure turbine power generation is cooled in sequence through the first set of soil heat exchangers, the compressor, and the second set of soil heat exchangers. If the CO2 temperature at the outlet of the second set of soil heat exchangers is lower than the reinjection temperature T0, it is injected into the reinjection well to absorb heat; if the CO2 temperature at the outlet of the second set of soil heat exchangers is higher than the reinjection temperature T0, it enters the bypass cooling tower for further cooling, and after cooling to a temperature lower than the reinjection temperature T0, it is injected into the reinjection well to absorb heat.

[0017] Preferably, before the long-term energy storage type carbon dioxide geothermal power generation system is put into operation, the mineralization reactor is started, and the CO2 from the thermal power plant and the fly ash undergo a mineralization carbon fixation reaction, and the product is used to lay the mineralized fly ash layer; During the operation of the long-term energy storage type carbon dioxide geothermal power generation system, the air supply compressor is turned on regularly to allow the CO2 generated by the thermal power plant to enter the air supply compressor to replenish the circulating medium CO2 in the long-term energy storage type carbon dioxide geothermal power generation system.

[0018] The beneficial effects of the present invention are: (1) Using shallow soil to cool the carbon dioxide discharged from the turbines and compressors of geothermal power generation systems not only reduces the power consumption of cooling towers and improves power generation efficiency, but also stores the cooling heat in the soil for long-term heat storage. By integrating shallow geothermal energy with deep geothermal energy, a three-dimensional development of geothermal energy can be achieved. At the same time, the modified solid waste after fly ash mineralization is covered on the top of the shallow heat storage soil, which is beneficial for fixing carbon dioxide and solving the problem of fly ash disposal, and also helps to improve the heat storage characteristics of shallow soil.

[0019] (2) Due to the temperature limit of deep geothermal heat reservoirs, the initial temperature of geothermal power generation itself is relatively low. After turbine power generation, both the pressure and temperature are reduced. In order to improve power generation efficiency, the power generation turbines are set in stages, and solar energy is used to heat carbon dioxide in the middle section to increase the temperature, thereby improving subsequent power generation parameters and improving the overall power generation efficiency of the system.

[0020] (3) Considering the volatility brought about by the large-scale integration of new energy sources into the power grid and the fluctuations in electricity prices in the spot market, a portion of the high-temperature carbon dioxide produced by geothermal production wells can be stored in tanks and then fed into medium- and low-pressure turbines for power generation during peak periods when electricity prices are high. This can not only improve the load response speed of the power generation system, but also help improve the economic efficiency of the project through electricity spot trading. During the power generation process, a portion of the carbon dioxide will be permanently sealed in the underground rock formation. While reducing carbon emissions, it can also generate revenue through carbon market trading, further improving the overall economic efficiency of the project. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of the long-term energy storage carbon dioxide geothermal power generation system of the present invention; Figure 2 It is a flow chart of the operation method of the long-term energy storage type carbon dioxide geothermal power generation system of the present invention.

[0022] In the figure: 1. High-pressure turbine, 2. Medium- and low-pressure turbines, 3. Generator, 4. Heat exchanger, 5. First set of soil heat exchangers, 6. Compressor, 7. Second set of soil heat exchangers, 8. Cooling tower, 9. Recharge well, 10. Production well, 11. Separator, 12. CO2 storage tank, 13. Gas storage tank inlet valve, 14. Gas storage tank outlet valve, 15. Pressurized cold water tank, 16. Solar collector, 17. Pressurized hot water tank, 18. Cold water tank inlet valve, 19. Cold water tank outlet valve, 20. Hot water tank inlet valve, 19. Hot water tank outlet valve, 22. Air supply compressor, 23. Thermal power plant, 24. Mineralization reactor, 25. Mineralized fly ash layer, 26. Stratum. DETAILED DESCRIPTION

[0023] The following describes it in detail with reference to specific implementation methods.

[0024] Example 1 The long-term energy storage type carbon dioxide geothermal power generation system of the present invention has the following structure: Figure 1 As shown, it includes a generator 3, the output end of the generator 3 is connected to the medium and low pressure turbine 2 and the high pressure turbine 1 in sequence through a shaft, the air inlet of the high pressure turbine 1 is also connected to the production well 10 through a pipeline A, the exhaust port of the high pressure turbine 1 and the air inlet of the medium and low pressure turbine 2 are commonly connected to the heat exchanger 4 through a pipeline, the heat exchanger 4 is also connected to the solar collector 16 through a pipeline to form a circulation loop, and the exhaust port of the medium and low pressure turbine 2 is connected to a first group of soil heat exchangers 5, a compressor 6, a second group of soil heat exchangers 7 and a reinjection well 9 arranged underground through pipelines.

[0025] Example 2 The long-term energy storage type carbon dioxide geothermal power generation system of the present invention has the following structure: Figure 1 As shown, it includes a generator 3, the output end of the generator 3 is connected to the medium and low pressure turbine 2 and the high pressure turbine 1 in sequence through a shaft, the air inlet of the high pressure turbine 1 is also connected to the production well 10 through a pipeline A, the exhaust port of the high pressure turbine 1 and the air inlet of the medium and low pressure turbine 2 are commonly connected to the heat exchanger 4 through a pipeline, the heat exchanger 4 is also connected to the solar collector 16 through a pipeline to form a circulation loop, and the exhaust port of the medium and low pressure turbine 2 is connected to a first group of soil heat exchangers 5, a compressor 6, a second group of soil heat exchangers 7 and a reinjection well 9 arranged underground through pipelines.

[0026] A separator 11 is also provided on the pipeline A between the high-pressure turbine 1 and the production well 10 .

[0027] The side of the pipe A located at the outlet of the separator 11 is also connected to the inlet of the CO2 storage tank 12 through the pipe B, and the outlet of the CO2 storage tank 12 is connected to the air inlet of the medium and low pressure turbine 2 through the pipe C.

[0028] The pipeline B is also provided with an air storage tank inlet valve 13, and the pipeline C is provided with an air storage tank outlet valve 14.

[0029] Example 3 The long-term energy storage type carbon dioxide geothermal power generation system of the present invention has the following structure: Figure 1 As shown, it includes a generator 3, the output end of the generator 3 is connected to the medium and low pressure turbine 2 and the high pressure turbine 1 in sequence through a shaft, the air inlet of the high pressure turbine 1 is also connected to the production well 10 through a pipeline A, the exhaust port of the high pressure turbine 1 and the air inlet of the medium and low pressure turbine 2 are commonly connected to the heat exchanger 4 through a pipeline, the heat exchanger 4 is also connected to the solar collector 16 through a pipeline to form a circulation loop, and the exhaust port of the medium and low pressure turbine 2 is connected to a first group of soil heat exchangers 5, a compressor 6, a second group of soil heat exchangers 7 and a reinjection well 9 arranged underground through pipelines.

[0030] A separator 11 is also provided on the pipeline A between the high-pressure turbine 1 and the production well 10 .

[0031] The side of the pipe A located at the outlet of the separator 11 is also connected to the inlet of the CO2 storage tank 12 through the pipe B, and the outlet of the CO2 storage tank 12 is connected to the air inlet of the medium and low pressure turbine 2 through the pipe C.

[0032] The pipeline B is also provided with an air storage tank inlet valve 13, and the pipeline C is provided with an air storage tank outlet valve 14.

[0033] The system also includes a thermal power plant 23. The CO2 produced by the thermal power plant 23 is connected to the air supply compressor 22 and the mineralization reactor 24 through pipelines D and E respectively. The fly ash produced by the thermal power plant 23 also enters the mineralization reactor 24 through pipelines. The system also includes a mineralized fly ash layer 25 located on the top of the stratum 26. The outlet of the mineralization reactor 24 is connected to the mineralized fly ash layer 25.

[0034] The first group of soil heat exchangers 5 and the second group of soil heat exchangers 7 are both located in the mineralized fly ash layer 25 , and the bottoms of the first group of soil heat exchangers 5 and the second group of soil heat exchangers 7 are located in the stratum 26 .

[0035] Example 4 The long-term energy storage type carbon dioxide geothermal power generation system of the present invention has the following structure: Figure 1As shown, it includes a generator 3, the output end of the generator 3 is connected to the medium and low pressure turbine 2 and the high pressure turbine 1 in sequence through a shaft, the air inlet of the high pressure turbine 1 is also connected to the production well 10 through a pipeline A, the exhaust port of the high pressure turbine 1 and the air inlet of the medium and low pressure turbine 2 are commonly connected to the heat exchanger 4 through a pipeline, the heat exchanger 4 is also connected to the solar collector 16 through a pipeline to form a circulation loop, and the exhaust port of the medium and low pressure turbine 2 is connected to a first group of soil heat exchangers 5, a compressor 6, a second group of soil heat exchangers 7 and a reinjection well 9 arranged underground through pipelines.

[0036] A separator 11 is also provided on the pipeline A between the high-pressure turbine 1 and the production well 10 .

[0037] The side of the pipe A located at the outlet of the separator 11 is also connected to the inlet of the CO2 storage tank 12 through the pipe B, and the outlet of the CO2 storage tank 12 is connected to the air inlet of the medium and low pressure turbine 2 through the pipe C.

[0038] The pipeline B is also provided with an air storage tank inlet valve 13, and the pipeline C is provided with an air storage tank outlet valve 14.

[0039] The system also includes a thermal power plant 23. The CO2 produced by the thermal power plant 23 is connected to the air supply compressor 22 and the mineralization reactor 24 through pipelines D and E respectively. The fly ash produced by the thermal power plant 23 also enters the mineralization reactor 24 through pipelines. The system also includes a mineralized fly ash layer 25 located on the top of the stratum 26. The outlet of the mineralization reactor 24 is connected to the mineralized fly ash layer 25.

[0040] A parallel bypass is also provided on the pipeline between the second group of soil heat exchangers 7 and the reinjection well 9, and a cooling tower 8 is provided on the bypass.

[0041] Example 5 The long-term energy storage type carbon dioxide geothermal power generation system of the present invention has the following structure: Figure 1 As shown, it includes a generator 3, the output end of the generator 3 is connected to the medium and low pressure turbine 2 and the high pressure turbine 1 in sequence through a shaft, the air inlet of the high pressure turbine 1 is also connected to the production well 10 through a pipeline A, the exhaust port of the high pressure turbine 1 and the air inlet of the medium and low pressure turbine 2 are commonly connected to the heat exchanger 4 through a pipeline, the heat exchanger 4 is also connected to the solar collector 16 through a pipeline to form a circulation loop, and the exhaust port of the medium and low pressure turbine 2 is connected to a first group of soil heat exchangers 5, a compressor 6, a second group of soil heat exchangers 7 and a reinjection well 9 arranged underground through pipelines.

[0042] A separator 11 is also provided on the pipeline A between the high-pressure turbine 1 and the production well 10 .

[0043] The side of the pipe A located at the outlet of the separator 11 is also connected to the inlet of the CO2 storage tank 12 through the pipe B, and the outlet of the CO2 storage tank 12 is connected to the air inlet of the medium and low pressure turbine 2 through the pipe C.

[0044] The pipeline B is also provided with an air storage tank inlet valve 13, and the pipeline C is provided with an air storage tank outlet valve 14.

[0045] The system also includes a thermal power plant 23. The CO2 produced by the thermal power plant 23 is connected to the air supply compressor 22 and the mineralization reactor 24 through pipelines D and E respectively. The fly ash produced by the thermal power plant 23 also enters the mineralization reactor 24 through pipelines. The system also includes a mineralized fly ash layer 25 located on the top of the stratum 26. The outlet of the mineralization reactor 24 is connected to the mineralized fly ash layer 25.

[0046] A parallel bypass is also provided on the pipeline between the second group of soil heat exchangers 7 and the reinjection well 9, and a cooling tower 8 is provided on the bypass.

[0047] The heat exchanger 4 is connected to the inlet of the solar collector 16 through a pipe F, and the heat exchanger 4 is connected to the outlet of the solar collector 16 through a pipe G. A bypass is also provided on the pipe F in parallel therewith. On the bypass, a cold water tank inlet valve 18, a cold water tank 15, and a cold water tank outlet valve 19 are sequentially provided in the direction from the heat exchanger 4 to the inlet of the solar collector 16; A bypass is also provided on the pipe G in parallel therewith. On the bypass, a hot water tank outlet valve 20, a hot water tank 17 and a hot water tank inlet valve 21 are provided in sequence in the direction from the heat exchanger 4 to the outlet of the solar collector 16.

[0048] Example 6 The operation method of the long-term energy storage type carbon dioxide geothermal power generation system of the present invention uses the long-term energy storage type carbon dioxide geothermal power generation system of Example 5, and its process is as follows: Figure 2 As shown, the specific steps are as follows: Step 1: Set the low electricity price C0, the high electricity price C1 and the reinjection temperature T0; Step 2: After the CO2 is injected into the reinjection well 9 and absorbs heat deep in the formation 26, high-temperature and high-pressure CO2 is produced from the production well 10. At this time: If the electricity price C is lower than the set low electricity price C0, the CO2 enters the CO2 storage tank 12 through the pipeline B for storage. When the electricity price rises to the set high electricity price C1, the CO2 enters the medium and low pressure turbine 2 from the CO2 storage tank 12 to generate electricity. By responding to the high and low electricity prices in the electricity market, the economic benefits of the project can be greatly improved. The CO2 energy storage is used to regulate the CO2 flow entering the power turbine in the geothermal power generation system, and then adjust the power generation power, so that the CO2 is fully generated when the electricity price is high, and more storage and less generation when the electricity price is low.

[0049] Otherwise, CO2 enters the high-pressure turbine 1 through pipeline A to generate power. After the CO2 enters the high-pressure turbine 1 to generate power, the exhaust gas of the high-pressure turbine 1 is heated by the heat exchanger 4. After the temperature is increased, the exhaust gas of the medium- and low-pressure turbine 2 is heated. The exhaust gas of the medium- and low-pressure turbine 2 is then injected into the reinjection well 9 to absorb heat through the first set of soil heat exchangers 5, the compressor 6, and the second set of soil heat exchangers 7. The principle of the heat exchanger 4 heating the exhaust gas of the high-pressure turbine 1 is as follows: During the day, solar collectors 16 are used to heat water. Part of the hot water enters the heat exchanger 4 to heat the CO2, and part enters the hot water tank 17 for storage. At night, the heat stored in the hot water tank 17 during the day is released into the heat exchanger 4 to heat the CO2, thereby achieving long-term heating throughout the day. Through all-weather heating, the initial parameters of the CO2 entering the medium and low pressure turbines for power generation are improved, thereby improving the overall power generation efficiency of the system.

[0050] The exhaust gas generated by the medium and low pressure turbines 2 is cooled in sequence through the first set of soil heat exchangers 5, the compressor 6, and the second set of soil heat exchangers 7. If the temperature of the CO2 at the outlet of the second set of soil heat exchangers 7 is lower than the reinjection temperature T0, it is injected into the reinjection well 9 to absorb heat; if the temperature of the CO2 at the outlet of the second set of soil heat exchangers 7 is higher than the reinjection temperature T0, it enters the bypass cooling tower 8 for further cooling. After cooling to a temperature lower than the reinjection temperature T0, it is injected into the reinjection well 9 to absorb heat.

[0051] Example 7 On the basis of Example 6, since part of the circulating medium CO2 will be sealed in the deep formation during the operation of the carbon dioxide geothermal power generation system, this causes the CO2 in the system to become less and less. In order to replenish the circulating medium CO2 in the power generation system, it is necessary to start the air supply compressor 22 at intervals to replenish it and maintain the circulating medium flow in the power generation system to meet the operating requirements.

[0052] During the project construction phase, mineralization reactor 24 is activated. CO2 from thermal power plant 23 reacts with fly ash to form a mineralized carbon fixation reaction, and the resulting product is used to lay a mineralized fly ash layer 25. Compared to soil, the mineralized fly ash layer has a higher density and better thermal insulation properties, which facilitates heat storage in the underlying stratum 26. Using the mineralized fly ash layer 25 and soil as thermal storage media lowers the CO2 temperature, saving system cooling power while also storing cooling heat in the mineralized fly ash layer 25 and soil. This heat can then be extracted through heat pumps and other methods to provide external heating.

Claims

1. Long-term energy storage type carbon dioxide geothermal power generation system, characterized by: The invention comprises a generator (3), wherein the output end of the generator (3) is sequentially connected to a medium- and low-pressure turbine (2) and a high-pressure turbine (1) through a shaft, the air inlet of the high-pressure turbine (1) is also connected to a production well (10) through a pipeline A, the exhaust port of the high-pressure turbine (1) and the air inlet of the medium- and low-pressure turbine (2) are commonly connected to a heat exchanger (4) through a pipeline, the heat exchanger (4) is also connected to a solar collector (16) through a pipeline to form a circulation loop, and the exhaust port of the medium- and low-pressure turbine (2) is sequentially connected to a first group of soil heat exchangers (5) arranged underground, a compressor (6), a second group of soil heat exchangers (7) arranged underground, and a reinjection well (9) through a pipeline.

2. The long-term energy storage type carbon dioxide geothermal power generation system according to claim 1 is characterized in that: A separator (11) is also provided on the pipeline A between the high-pressure turbine (1) and the production well (10).

3. The long-term energy storage type carbon dioxide geothermal power generation system according to claim 2 is characterized in that: The side of the pipe A located at the outlet of the separator (11) is also connected to the inlet of the CO2 storage tank (12) through a pipe B, and the outlet of the CO2 storage tank (12) is connected to the air inlet of the medium and low pressure turbine (2) through a pipe C.

4. The long-term energy storage type carbon dioxide geothermal power generation system according to claim 3 is characterized in that: The pipeline B is further provided with an air storage tank inlet valve (13), and the pipeline C is provided with an air storage tank outlet valve (14).

5. The long-term energy storage type carbon dioxide geothermal power generation system according to claim 3 is characterized in that: The invention also includes a thermal power plant (23), wherein the CO2 generated by the thermal power plant (23) is connected to an air supply compressor (22) and a mineralization reactor (24) through a pipeline D and a pipeline E, respectively. The fly ash generated by the thermal power plant (23) also enters the mineralization reactor (24) through a pipeline. The invention also includes a mineralized fly ash layer (25) located at the top of the stratum (26), and the outlet of the mineralization reactor (24) is connected to the mineralized fly ash layer (25).

6. The long-term energy storage type carbon dioxide geothermal power generation system according to claim 5, characterized in that: A parallel bypass is also provided on the pipeline between the second group of soil heat exchangers (7) and the reinjection well (9), and a cooling tower (8) is provided on the bypass.

7. The long-term energy storage type carbon dioxide geothermal power generation system according to claim 6, characterized in that: The heat exchanger (4) is connected to the inlet of the solar thermal collector (16) via a pipe F, and the heat exchanger (4) is connected to the outlet of the solar thermal collector (16) via a pipe G. A bypass is also provided on the pipe F in parallel therewith, and a cold water tank inlet valve (18), a cold water tank (15), and a cold water tank outlet valve (19) are sequentially provided on the bypass in the direction from the heat exchanger (4) to the inlet of the solar thermal collector (16); The pipe G is also provided with a bypass in parallel therewith, and a hot water tank outlet valve (20), a hot water tank (17), and a hot water tank inlet valve (21) are sequentially provided on the bypass in a direction from the heat exchanger (4) to the outlet of the solar collector (16).

8. A method for operating a long-term energy storage carbon dioxide geothermal power generation system, characterized in that: The long-term energy storage carbon dioxide geothermal power generation system according to claim 7 is implemented specifically according to the following steps: Step 1: Set the low electricity price C0, the high electricity price C1 and the reinjection temperature T0; Step 2: After the CO2 is injected into the reinjection well (9) and absorbs heat deep in the formation (26), high-temperature and high-pressure CO2 is produced from the production well (10). At this time: If the electricity price C is lower than the set low electricity price C0, CO2 enters the CO2 storage tank (12) through the pipeline B for storage. When the electricity price rises to the set high electricity price C1, CO2 enters the medium and low pressure turbine (2) from the CO2 storage tank (12) to generate electricity. Otherwise, CO2 enters the high-pressure turbine (1) through pipeline A to generate power.

9. The method for operating a long-term energy storage carbon dioxide geothermal power generation system according to claim 8, characterized in that: After CO2 enters the high-pressure turbine (1) to generate electricity, the exhaust gas of the high-pressure turbine (1) is heated by the heat exchanger (4), and then enters the medium- and low-pressure turbine (2) to generate electricity after the temperature is increased. The exhaust gas of the medium- and low-pressure turbine (2) then passes through the first set of soil heat exchangers (5), the compressor (6), and the second set of soil heat exchangers (7) in sequence and is injected into the reinjection well (9) to absorb heat; The principle of the heat exchanger (4) heating the exhaust gas of the high-pressure turbine (1) is as follows: During the day, the solar collector (16) is used to heat water, part of which enters the heat exchanger (4) to heat CO2, and part of which enters the hot water tank (17) to be stored. At night, the heat stored in the hot water tank (17) during the day is released into the heat exchanger (4) to heat CO2, thereby achieving long-term heating throughout the day. The exhaust gas generated by the medium and low pressure turbine (2) is cooled in sequence through the first set of soil heat exchangers (5), the compressor (6), and the second set of soil heat exchangers (7). If the temperature of the CO2 at the outlet of the second set of soil heat exchangers (7) is lower than the reinjection temperature T0, it is injected into the reinjection well (9) to absorb heat; if the temperature of the CO2 at the outlet of the second set of soil heat exchangers (7) is higher than the reinjection temperature T0, it enters the bypass cooling tower (8) for further cooling. After cooling to a temperature lower than the reinjection temperature T0, it is injected into the reinjection well (9) to absorb heat.

10. The operating method of the long-term energy storage type carbon dioxide geothermal power generation system according to claim 9, characterized in that: Before the long-term energy storage type CO2 geothermal power generation system is put into operation, the mineralization reactor (24) is started, CO2 from the thermal power plant (23) and fly ash undergo a mineralization carbon fixation reaction, and the product is used to lay a mineralized fly ash layer (25); During the operation of the long-term energy storage type carbon dioxide geothermal power generation system, the air supply compressor (22) is periodically turned on to allow the CO2 generated by the thermal power plant (23) to enter the air supply compressor (22) to replenish the circulating medium CO2 in the long-term energy storage type carbon dioxide geothermal power generation system.

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