Dry hot rock geothermal energy and low-melting-point fused salt heat storage coupled composite clean heat supply system

Abstract

The invention relates to the field of clean heat supply, in particular to a hot dry rock geothermal energy and low-melting-point fused salt heat storage coupled composite clean heat supply system which comprises a low-melting-point fused salt heat storage and release module, a hot dry rock geothermal energy and low-melting-point fused salt heat storage and release module and a hot dry rock geothermal energy and low-melting-point fused salt heat storage and release module. The hot dry rock geothermal module is used for absorbing geothermal energy to heat fused salt and (or) hot water of a heat supply network; the heat supply network hot water circulation module is used for heating heat supply network hot water through geothermal energy and (or) fused salt; the composite clean heat supply system comprises a hot dry rock geothermal water circulation unit, a heat supply network hot water circulation unit and a low-melting-point fused salt heat storage and release circulation unit, the hot dry rock geothermal water circulation unit is mainly used for geothermal water source circulation treatment through valve switching, and geothermal water is pressurized through a circulation pump to enter a geothermal heat exchanger. And the geothermal water is used as a heat source to directly heat molten salt after being heated, or is used as a heat source to directly heat hot water of a heat supply network through an absorption heat pump and (or) a plate heat exchanger after being heated.

Description

Technical Field

[0001] The present invention belongs to the field of clean heating technology, and specifically is a composite clean heating system that couples hot dry rock geothermal energy with low-melting-point molten salt heat storage. Background Art

[0002] Currently, hot rock geothermal development worldwide is still in the field trial and R&D phase. my country possesses vast reserves of hot rock geothermal resources. Existing projects utilizing hot rock thermal energy utilize it solely as a direct heat source, typically through plate heat exchangers or a combination of plate heat exchangers and water-source heat pumps. This approach is relatively simple, and the reliability of a single heat source is low, necessitating the development of other heat sources as supplementary sources. Molten salt thermal storage is a recently emerging thermal storage technology. It utilizes electricity from nighttime, low-price periods, to heat molten salt. When heating is needed during peak-price periods, the stored heat in the molten salt is released, using a heat exchanger to heat hot water and provide heat. The low-temperature molten salt, after releasing the heat, is then stored in tanks and heated during off-peak periods, allowing for repeated reuse. This not only shifts peak demand but also allows for the integration of renewable energy generation, ensuring stable grid operation and reducing emissions. However, the thermal storage process consumes significant amounts of electricity.

[0003] A patent with publication number CN115076750A discloses a composite heat pump heating system of a heat exchange station based on the complementarity of multiple clean energy sources. When the system is used to provide heating to users of the secondary network during the heating season, the water supply of the primary network is used to drive the absorption heat pump during the day to extract low-grade thermal energy produced by the geothermal complementary clean energy heating system composed of solar collectors and geothermal wells. At night, only the low-grade thermal energy produced by the geothermal wells is extracted, and the heat produced by the absorption heat pump is used to heat the circulating water of the secondary network to provide heating to users; in the non-heating season, solar collectors are used to recharge heat to the geothermal wells to ensure soil temperature balance and enable the system to operate stably throughout the year; full use is made of clean energy for heating, the temperature difference between the high and low temperature heat sources of the absorption heat pump is reduced, the performance coefficient of the heat pump is improved, and the utilization rate of clean energy and the heating capacity of the system are improved.

[0004] In the current existing technology, hot dry rock thermal energy is utilized, but the utilization method is relatively simple, and the reliability of heating from a single heat source is low, so other heat sources need to be built; molten salt heat storage is an emerging heat storage technology in recent years. It uses electricity during the night-time low electricity price period to heat molten salt. When heating is needed during the peak electricity price period, the heat stored in the molten salt is released, and hot water is heated through a heat exchanger to achieve heating; the low-temperature molten salt after heat release is stored in a storage tank again, and is heated when the electricity price is low, and is repeatedly recycled. It not only realizes peak shifting and valley filling, but also can absorb new energy power generation, provide guarantee for the stable operation of the power grid, and can reduce emissions to a certain extent, but a large amount of electricity is required in the heat storage process.

[0005] To this end, the present invention provides a composite clean heating system that couples hot dry rock geothermal energy with low-melting-point molten salt heat storage. Summary of the Invention

[0006] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0007] The technical solution adopted by the present invention to solve the technical problem is: the composite clean heating system of the present invention, which couples hot dry rock geothermal energy with low-melting-point molten salt heat storage, comprises:

[0008] Molten salt heat storage module, used for storage and heat release of geothermal sources;

[0009] Hot dry rock geothermal module, used for absorbing and preheating thermal energy;

[0010] The hot water circulation module of the heat network is used to circulate heat to the stored heat source;

[0011] The hot water circulation module of the heat network includes a hot dry rock geothermal water circulation unit, a heat supply unit and a low melting point molten salt heat storage and heat release circulation unit. The hot dry rock geothermal water circulation unit is mainly used for geothermal water source circulation processing through valve switching;

[0012] The low-melting-point molten salt heat storage and release cycle unit is used for heat storage and release cycle processing.

[0013] Preferably, the hot dry rock geothermal water circulation unit is mainly composed of a geothermal heat exchanger, a circulation pump, valve one, valve two, a molten salt preheater, valve three, valve four, valve five, an absorption heat pump, valve six, valve seven, valve eight, valve nine and a plate heat exchanger.

[0014] Preferably, the hot dry rock geothermal water circulation unit is used to allow geothermal water to enter the interior of the geothermal heat exchanger through the pressure of a circulation pump, and to be preheated by the geothermal water, and then the molten salt is heated through valve two and a molten salt preheater. The driving heat source generated when the hot molten salt is cooled enters the interior of the absorption heat pump through valves four and five for heating and concentration into a lithium bromide solution. The absorption heat pump is further cooled in the evaporator and then returns to the interior of the circulation pump through valve seven for recycling.

[0015] Preferably, the hot dry rock geothermal water circulation unit is used to heat the geothermal water after it is pressurized by the circulation pump and then enter the geothermal heat exchanger for heating and heating, and then heat the molten salt through valve 2 and the molten salt preheater. After the hot molten salt is cooled for the first time, it enters the plate heat exchanger through valves 4 and 6 to directly heat the hot water in the hot network. When the hot molten salt is cooled for the second time, it returns to the circulation pump through valve 9 for recycling.

[0016] Preferably, the hot dry rock geothermal water circulation unit is used to pressurize the geothermal water through a circulation pump, so that the geothermal water enters the geothermal heat exchanger for heating and temperature increase. The heated heat source serves as a driving heat source and passes through valve one and valve five in sequence to enter the absorption heat pump and heat and concentrate the lithium bromide solution through the generator. When the concentrated lithium bromide solution is cooled, the hot water will directly enter the plate heat exchanger and heat the hot water in the heat network. After the concentrated lithium bromide solution is cooled for the second time, it returns to the absorption heat pump and returns to the circulation pump through valve seven for recycling.

[0017] Preferably, the hot dry rock geothermal water circulation unit is used to pressurize geothermal water through a circulation pump and enter the interior of a geothermal heat exchanger for heating and then enter the plate heat exchanger through valve one and valve six to heat the hot water in the heat network. After the geothermal water cools down, it returns to the interior of the circulation pump through valve nine for recycling and treatment.

[0018] Preferably, the low-melting-point molten salt heat storage and release circulation unit is used to form a closed loop mainly composed of a molten salt preheater, a molten salt heater, a low-temperature molten salt tank, a high-temperature molten salt tank, a molten salt-water heat exchanger, a molten salt heating pump, a molten salt heat release pump, valve 11, valve 12 and valve 13, and hot water circulation treatment is carried out by switching the valves and starting and stopping the pump.

[0019] Preferably, the low-melting-point molten salt heat storage and heat release circulation unit is used for the molten salt heat pump in the low-temperature molten salt tank to heat the molten salt through valve 11, molten salt preheater, valve 13, and molten salt heater after pressurization, and send the heated molten salt to the inside of the high-temperature molten salt tank;

[0020] The molten salt in the low-temperature molten salt tank is pressurized by the molten salt heating pump and then heated through valve 12 and the molten salt heater, and the heated molten salt is sent to the interior of the high-temperature molten salt tank;

[0021] The molten salt inside the high-temperature molten salt tank is pressurized by the molten salt heat release pump and then transported into the molten salt-water heat exchanger, where it is cooled by the hot water from the heating network, and the cooled molten salt is transported into the low-temperature molten salt tank for collection and treatment.

[0022] Preferably, the hot water circulation unit of the heating network is composed of an absorption heat pump, a plate heat exchanger, a molten salt-water heat exchanger, a heat user, a molten salt heating circulation pump, an absorption heat pump heating circulation pump, a plate heat exchanger heating circulation pump, valve fourteen, valve fifteen, valve sixteen, valve seventeen, valve eighteen and valve nineteen, thereby allowing the hot water in the heating network to be circulated.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. The composite clean heating system of the present invention, which couples hot dry rock geothermal energy with low-melting-point molten salt heat storage, is characterized in that the geothermal water is first pressurized by a circulation pump and enters the interior of the geothermal heat exchanger and is heated by heating. Then, it passes through a valve and a molten salt preheater in sequence to heat the molten salt. After the first cooling, it serves as a driving heat source and enters the generator of the absorption heat pump through valves and valves to heat and concentrate the lithium bromide solution. After the second cooling, the hot water enters the plate heat exchanger to directly heat the hot water in the heating network. After the third cooling, the hot water returns to the absorption heat pump as a low-level heat source, and is further cooled in the absorption heat pump evaporator before finally returning to the circulation pump through a valve. Through different circulation combinations and coupled energy supply, different heat storage and heating operating conditions can be achieved, effectively improving the reliability of the heating supply. At the same time, the molten salt is preheated by hot dry rock geothermal energy, reducing power consumption, improving the economy of the heating system, and achieving peak heating.

[0025] 2. The composite clean heating system of the present invention, which couples hot dry rock geothermal energy with low-melting-point molten salt heat storage, pressurizes geothermal water through a circulation pump and enters the geothermal heat exchanger, where it is heated and heated. As a driving heat source, it passes through valves, valves, and enters the generator of the absorption heat pump to heat and concentrate the lithium bromide solution. After the first cooling, the hot water enters the plate heat exchanger to directly heat the hot water in the heating network. After the second cooling, the hot water returns to the absorption heat pump as a low-level heat source, is further cooled in the absorption heat pump evaporator, and finally returns to the circulation pump through the valve. Different circulation functions are achieved by switching the valve and starting and stopping the pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the accompanying drawings.

[0027] Figure 1 It is a schematic flow diagram of the present invention.

[0028] In the figure: 1. Geothermal heat exchanger; 2. Circulation pump; 3. Valve 1; 4. Valve 2; 5. Molten salt preheater; 6. Valve 3; 7. Valve 4; 8. Valve 5; 9. Absorption heat pump; 10. Valve 6; 11. Valve 7; 12. Valve 8; 13. Valve 9; 15. Low-temperature molten salt tank; 16. Molten salt heating pump; 17. Valve 11; 18. Valve 12; 19. Valve 13; 20. Molten salt heater; 21. High-temperature molten salt tank; 22. Molten salt heat release pump; 23. Molten salt-water heat exchanger; 24. Valve 14; 25. Molten salt heating circulation pump; 26. Valve 15; 27. Valve 16; 28. Absorption heat pump heating circulation pump; 29. ​​Valve 17; 30. Valve 18; 31. Plate heat exchanger heating circulation pump; 32. Valve 19; 33. Heat user; 14. Plate heat exchanger. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0030] like Figure 1 As shown, the composite clean heating system of the embodiment of the present invention, which couples hot dry rock geothermal energy with low-melting-point molten salt heat storage, includes:

[0031] Molten salt heat storage module, used for heating, storing and releasing heat energy;

[0032] Hot dry rock geothermal module, used to absorb geothermal energy to heat molten salt and / or hot water in the heating network;

[0033] The hot water circulation module of the heat network is used to circulate heat to the stored heat source;

[0034] The hot water circulation module of the heat network includes a hot dry rock geothermal water circulation unit, a heat supply unit and a low melting point molten salt heat storage and heat release circulation unit. The hot dry rock geothermal water circulation unit is mainly used for geothermal water source circulation processing through valve switching;

[0035] The low-melting-point molten salt heat storage and release cycle unit is used for heat storage and release cycle processing.

[0036] like Figure 1 As shown, the hot dry rock geothermal water circulation unit is used for a closed circulation system consisting of a geothermal heat exchanger 1, a circulation pump 2, a valve 1 3, a valve 2 4, a molten salt preheater 5, a valve 3 6, a valve 4 7, a valve 5 8, an absorption heat pump 9, a valve 6 10, a valve 7 11, a valve 8 12, a valve 9 13 and a plate heat exchanger 14. The geothermal water temperature of the hot dry rock geothermal water circulation unit and the working conditions of the heating system are circulated by switching the valves.

[0037] The hot dry rock geothermal water circulation unit is used to pressurize geothermal water through the circulation pump 2 and enter the interior of the geothermal heat exchanger 1, where it is preheated by the geothermal water. The molten salt is then heated through the valve 2 4 and the molten salt preheater 5. The driving heat source generated when the hot molten salt is cooled enters the absorption heat pump 9 through the valve 4 7 and the valve 5 8 for heating and concentration into a lithium bromide solution. After further cooling in the evaporator of the absorption heat pump 9, it returns to the circulation pump 2 through the valve 7 11 for recycling.

[0038] The hot dry rock geothermal water circulation unit also includes the following steps:

[0039] After being pressurized by the circulation pump 2, the geothermal water enters the geothermal heat exchanger 1 for heating and then passes through the valve 2 4 and the molten salt preheater 5 to heat the molten salt. After the hot molten salt cools down for the first time, it passes through the valve 4 7 and the valve 6 10 to enter the plate heat exchanger 14 to directly heat the hot water in the hot water network. After the hot molten salt cools down for the second time, it passes through the valve 9 13 and returns to the circulation pump 2 for recycling.

[0040] The hot dry rock geothermal water circulation unit is used to heat geothermal water after it is pressurized by the circulation pump 2, allowing the geothermal water to enter the geothermal heat exchanger 1 for heating and raising its temperature. The heated heat source serves as a driving heat source and passes through valve 1 3 and valve 5 8, entering the absorption heat pump 9 and heating and concentrating the lithium bromide solution through the generator. When the concentrated lithium bromide solution cools down, the hot water directly enters the plate heat exchanger 14 and heats the hot water in the heating network. When the concentrated lithium bromide solution cools down for the second time, it returns to the absorption heat pump 9 and returns to the circulation pump 2 through valve 7 11 for recycling.

[0041] The hot dry rock geothermal water circulation unit is used to pressurize geothermal water through the circulation pump 2 and enter the geothermal heat exchanger 1 for heating and then pass through valve 1 3, valve 6 10, enter the plate heat exchanger 14 and heat the hot water in the heat network. After the geothermal water cools down, it returns to the inside of the circulation pump 2 through valve 9 13 for recycling.

[0042] The geothermal water is first pressurized by the circulation pump and enters the geothermal heat exchanger and is heated. It then passes through the valve and molten salt preheater in sequence to heat the molten salt. After the first cooling, it serves as a driving heat source and enters the generator of the absorption heat pump through valves and valves to heat and concentrate the lithium bromide solution. After the second cooling, the hot water enters the plate heat exchanger to directly heat the hot water in the heating network. After the third cooling, the hot water returns to the absorption heat pump as a low-level heat source. After further cooling in the absorption heat pump evaporator, it finally returns to the circulation pump through the valve. Through different circulation combinations and coupled energy supply, different heat storage and heating conditions can be achieved, which effectively improves the reliability of heating. At the same time, the molten salt is preheated by dry hot rock geothermal energy, which reduces power consumption, improves the economy of the heating system, and realizes peak heating.

[0043] like Figure 1 As shown, the low-melting-point molten salt heat storage and heat release circulation unit is used to mainly consist of a molten salt preheater 5, a molten salt heater 20, a low-temperature molten salt tank 15, a high-temperature molten salt tank 21, a molten salt-water heat exchanger 23, a molten salt heating pump 16, a molten salt heat release pump 22, a valve 11 17, a valve 12 18 and a valve 13 19 to form a closed loop, and hot water circulation treatment is performed by switching the valves and starting and stopping the pumps; the low-melting-point molten salt heat storage and heat release circulation unit is used for S1, the molten salt heating pump 16 in the low-temperature molten salt tank 15 is heated through the valve 11 17, the molten salt preheater 5, the valve 13 19 and the molten salt heater 20 after pressurization, and the heated molten salt is sent to the inside of the high-temperature molten salt tank 21;

[0044] S2, the molten salt in the low-temperature molten salt tank 15 is pressurized by the molten salt heating pump 16 and heated through the valve 12 18 and the molten salt heater 20, and the heated molten salt is sent to the inside of the high-temperature molten salt tank 21;

[0045] S3: The molten salt in the high-temperature molten salt tank 21 is pressurized by the molten salt heat release pump 22 and transported to the inside of the molten salt-water heat exchanger 23, where it is cooled by heating the hot water from the heat network. The cooled molten salt is then transported to the inside of the low-temperature molten salt tank 15 for collection and treatment.

[0046] The hot water circulation unit of the heating network is mainly composed of an absorption heat pump 9, a plate heat exchanger 14, a molten salt-water heat exchanger 23, a heat user 33, a molten salt heating circulation pump 25, an absorption heat pump heating circulation pump 28, a plate heat exchanger heating circulation pump 31, a valve 14 24, a valve 15 26, a valve 16 27, a valve 17 29, a valve 18 30 and a valve 19 32, thereby circulating the hot water in the heating network.

[0047] When the molten salt needs to be heated and the geothermal water temperature is high, the heating system realizes heat storage and heating through the heat storage and heat release cycle of dry hot rock, low melting point molten salt, and hot water cycle of the heat network;

[0048] When the molten salt needs to be heated and the geothermal water temperature is too low to heat the molten salt or the molten salt preheater fails, the heating system realizes heat storage and heating through the dry hot rock geothermal water circulation, the low melting point molten salt heat storage and heat release circulation, and the heat network hot water circulation;

[0049] When the molten salt needs to be heated, the geothermal water temperature is too low to heat the molten salt, or the molten salt preheater fails or the absorption heat pump fails, the heating system realizes heat storage and heating through the dry hot rock geothermal water circulation, the low melting point molten salt heat storage and heat release circulation, and the heat network hot water circulation;

[0050] When the low-melting-point molten salt heat storage and release system needs to release heat, the heating system realizes heat release and heating through the dry hot rock geothermal water circulation, the low-melting-point molten salt heat storage and release circulation, and the hot water circulation of the heating network;

[0051] When the low-melting-point molten salt heat storage and release system does not need to be operated, the heating system realizes heating through the dry hot rock geothermal water circulation and the hot water circulation of the heating network;

[0052] When the low-melting-point molten salt heat storage and release system does not need to be operated, the absorption heat pump fails, or the geothermal water temperature is low, the heating system realizes heating through the dry hot rock geothermal water circulation and the hot water circulation of the heating network;

[0053] When the local hot water circulation system fails, the heating system provides heating through the low-melting-point molten salt heat storage and release cycle and the heat network hot water circulation.

[0054] Working principle: Geothermal water is first pressurized by a circulation pump and enters the geothermal heat exchanger and is heated by heating. It then passes through the valve and molten salt preheater in sequence to heat the molten salt. After the first cooling, it serves as a driving heat source and enters the generator of the absorption heat pump through valves and valves to heat and concentrate the lithium bromide solution. After the second cooling, the hot water enters the plate heat exchanger to directly heat the hot water in the heating network. After the third cooling, the hot water returns to the absorption heat pump as a low-level heat source. After further cooling in the absorption heat pump evaporator, it finally returns to the circulation pump through the valve. Through different circulation combinations and coupled energy supply, different heat storage and heating conditions can be achieved, which effectively improves the reliability of heating. At the same time, the molten salt is preheated by dry hot rock geothermal energy, which reduces power consumption, improves the economy of the heating system, and realizes peak heating.

[0055] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A composite clean heating system that couples hot dry rock geothermal energy with low-melting-point molten salt heat storage, characterized in that: include: Molten salt heat storage module, used for heating, storing and releasing heat energy; Hot dry rock geothermal module, used to absorb geothermal energy to heat molten salt and / or hot water in the heating network; The hot water circulation module of the heat network is used to circulate heat to the stored heat source; The hot water circulation module of the heating network includes a hot dry rock geothermal water circulation unit, a heating unit and a low-melting-point molten salt heat storage and heat release circulation unit. The hot dry rock geothermal water circulation unit is mainly used for geothermal water source circulation treatment through valve switching; The low melting point molten salt heat storage and release cycle unit is used for heat storage and release cycle processing.

2. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 1 is characterized by: The dry hot rock geothermal water circulation unit is composed of a geothermal heat exchanger (1), a circulation pump (2), a valve one (3), a valve two (4), a molten salt preheater (5), a valve three (6), a valve four (7), a valve five (8), an absorption heat pump (9), a valve six (10), a valve seven (11), a valve eight (12), a valve nine (13) and a plate heat exchanger (14).

3. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 2 is characterized by: The dry hot rock geothermal water circulation unit is used for geothermal water to enter the interior of the geothermal heat exchanger (1) through the pressure of the circulation pump (2), and to be preheated by the geothermal water, and then the molten salt is heated through the valve two (4) and the molten salt preheater (5). The geothermal water is used as a driving heat source after the molten salt is heated and cooled for the first time, and enters the generator inside the absorption heat pump (9) through valve four (7) and valve five (8) to be heated and concentrated into lithium bromide solution. After the second cooling, it enters the heat exchanger (14) to directly heat the hot water in the heat network. After the third cooling, it returns to the absorption heat pump (9) as a low-level heat source, is further cooled in the evaporator, and then returns to the interior of the circulation pump (2) through valve seven (11) for recycling.

4. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 3 is characterized by: The dry hot rock geothermal water circulation unit is used for geothermal water to be pressurized by a circulation pump (2) and then enter the geothermal heat exchanger (1) for heating and temperature increase, and then heat the molten salt through valve two (4) and a molten salt preheater (5). After the hot molten salt is cooled for the first time, it enters the plate heat exchanger (14) through valve four (7) and valve six (10) to directly heat the hot water in the hot network. After the hot molten salt is cooled for the second time, it returns to the inside of the circulation pump (2) through valve nine (13) for recycling.

5. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 4 is characterized by: The hot dry rock geothermal water circulation unit is used for pressurizing geothermal water through a circulation pump (2) so that the geothermal water enters the geothermal heat exchanger (1) for heating and temperature increase. The heated and temperature increased heat source is used as a driving heat source and passes through valve one (3) and valve five (8) successively, enters the interior of the absorption heat pump (9) and is heated and concentrated by the generator to form a lithium bromide solution. After the heated and concentrated lithium bromide solution is cooled, the geothermal water directly enters the interior of the plate heat exchanger (14) and heats the hot water in the heat network. After the second cooling, the geothermal water returns to the internal evaporator of the absorption heat pump (9) for further cooling and then returns to the interior of the circulation pump (2) through valve seven (11) for recycling.

6. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 5 is characterized by: The dry hot rock geothermal water circulation unit is used for geothermal water to be pressurized by a circulation pump (2) and enter the interior of a geothermal heat exchanger (1) for heating and then enter the plate heat exchanger (14) through valve one (3) and valve six (10) to heat the hot water in the heat network. After the geothermal water cools down, it returns to the interior of the circulation pump (2) through valve nine (13) for recycling and treatment.

7. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 6 is characterized by: The low-melting-point molten salt heat storage and heat release circulation unit is used to mainly consist of a molten salt preheater (5), a molten salt heater (20), a low-temperature molten salt tank (15), a high-temperature molten salt tank (21), a molten salt-water heat exchanger (23), a molten salt heating pump (16), a molten salt heat release pump (22), valve 11 (17), valve 12 (18) and valve 13 (19) to form a closed loop, and the molten salt heating and heat release circulation process is carried out by switching the valves and starting and stopping the pumps.

8. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 7 is characterized by: The low melting point molten salt heat storage and heat release circulation unit is used for the molten salt heating pump (16) in the low temperature molten salt tank (15) to heat the molten salt through the valve 11 (17), the molten salt preheater (5), the valve 13 (19), and the molten salt heater (20) after pressurization, and the heated molten salt is sent to the inside of the high temperature molten salt tank (21); The molten salt in the low-temperature molten salt tank (15) is pressurized by the molten salt heating pump (16) and then heated through valve 12 (18) and the molten salt heater (20), and the heated molten salt is sent to the interior of the high-temperature molten salt tank (21); The molten salt inside the high-temperature molten salt tank (21) is pressurized by the molten salt heat release pump (22) and then transported to the inside of the molten salt-water heat exchanger (23), where it is cooled in conjunction with the hot water from the heating network, and the cooled molten salt is transported to the inside of the low-temperature molten salt tank (15) for collection and processing.

9. The composite clean heating system of hot dry rock geothermal energy coupled with low-melting-point molten salt heat storage according to claim 8 is characterized by: The hot water circulation unit of the heat network is composed of an absorption heat pump (9), a plate heat exchanger (14), a molten salt-water heat exchanger (23), a heat user (33), a molten salt heating circulation pump (25), an absorption heat pump heating circulation pump (28), a plate heat exchanger heating circulation pump (31), a valve 14 (24), a valve 15 (26), a valve 16 (27), a valve 17 (29), a valve 18 (30) and a valve 19 (32).

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