Supercritical carbon dioxide photo-thermal power generation system utilizing terrestrial heat and operation method

Abstract

The invention discloses a supercritical carbon dioxide photo-thermal power generation system utilizing terrestrial heat and an operation method. The supercritical carbon dioxide photo-thermal power generation system comprises a tower type photo-thermal system, a terrestrial heat utilization system, a supercritical carbon dioxide power generation system and a fused salt heat storage system. Wherein the tower type photo-thermal system and the fused salt heat storage system are used for absorbing and storing photo-thermal, and the terrestrial heat utilization system and the supercritical carbon dioxide power generation system are used for utilizing terrestrial heat and photo-thermal. Supercritical carbon dioxide photo-thermal power generation and geothermal power generation are integrated, and medium and low temperature geothermal energy and high temperature photo-thermal energy are fully utilized; supercritical carbon dioxide is used as a heat-carrying medium of the geothermal system, and the problems existing when water is used as the heat-carrying medium of a traditional geothermal system are solved.

Description

Technical Field

[0001] The present invention relates to a solar thermal power generation system, and in particular to a supercritical carbon dioxide thermal power generation system utilizing geothermal energy and an operation method thereof. Background Art

[0002] The supercritical carbon dioxide solar thermal power generation system is an efficient and environmentally friendly power generation technology that uses supercritical carbon dioxide (S-CO2) as a working medium to generate electricity through photothermal conversion and thermodynamic cycle processes. The entire system consists of a concentrating and collecting system, a heat storage and heat exchange system, and a power cycle system. The concentrating and collecting system converts solar energy into thermal energy, the heat storage and heat exchange system transfers thermal energy to the working medium, and the power cycle system converts thermal energy into mechanical energy, and finally drives the generator to generate electricity.

[0003] Supercritical carbon dioxide solar thermal power generation system has broad application prospects, especially in areas with abundant solar energy resources and strict environmental requirements. The system can be widely used in large-scale solar thermal power stations, distributed solar thermal power generation systems, and combined power generation with other energy systems (such as nuclear power, thermal power, etc.). In addition, with the continuous advancement of technology and the reduction of costs, supercritical carbon dioxide solar thermal power generation system is expected to become one of the important development directions in the field of renewable energy power generation in the future.

[0004] There are two main sources of geothermal energy: one is the residual heat from the early formation of the earth, and the other is the heat generated by the decay of radioactive elements inside the earth. This heat is transferred to the surface through heat conduction and convection, forming geothermal energy that can be developed and utilized by humans. Geothermal resources have the characteristics of large reserves, wide distribution, clean and environmentally friendly, stable and reliable.

[0005] Geothermal energy is a clean, low-carbon renewable energy source. Compared with other renewable energy sources, it has the advantages of continuous stability, low cost, and large reserves. As the world's attention to renewable energy continues to increase, driven by the dual carbon goals, the efficient use of my country's abundant geothermal resources is of great significance. The Organic Rankine Cycle (ORC) uses low-boiling point organic matter as a working fluid, which expands and works in an expander (turbine) to drive a generator to generate electricity. my country's geothermal resources are mainly medium and low temperature geothermal, with a low grade of heat source. It is usually matched with an organic Rankine cycle to realize the conversion of thermal energy into electrical energy. This makes the traditional medium and low temperature geothermal power generation system less efficient and geothermal resources difficult to be fully utilized. Summary of the invention

[0006] In order to overcome the problem that geothermal energy cannot be fully utilized in the prior art, the present invention provides a supercritical carbon dioxide solar thermal power generation system and operation method utilizing geothermal energy, which fully utilizes medium-low temperature geothermal energy and medium-high temperature solar thermal energy, and also avoids the problem of using water as a heat carrier medium when utilizing geothermal energy.

[0007] In order to achieve the above object, the present invention adopts the following technical scheme:

[0008] A supercritical carbon dioxide photothermal power generation system utilizing geothermal energy, comprising a tower photothermal system, a geothermal utilization system, a supercritical carbon dioxide power generation system and a molten salt heat storage system;

[0009] The geothermal utilization system includes an injection well and a recovery well arranged in the geothermal layer;

[0010] The supercritical carbon dioxide power generation system includes a molten salt-supercritical carbon dioxide heat exchanger, a regenerator, a turbine, a precooler and a compressor;

[0011] The tower-type photothermal system is connected to a molten salt heat storage system, and the molten salt heat storage system is connected to the molten salt side of the molten salt-supercritical carbon dioxide heat exchanger;

[0012] The recovery well outlet is connected to the low-temperature side inlet of the regenerator, the low-temperature side outlet of the regenerator is connected to the supercritical carbon dioxide side inlet of the molten salt-supercritical carbon dioxide heat exchanger, the supercritical carbon dioxide side outlet of the molten salt-supercritical carbon dioxide heat exchanger is connected to the turbine inlet, the turbine outlet is connected to the high-temperature side inlet of the regenerator, the high-temperature side outlet of the regenerator is connected to the high-temperature side inlet of the precooler, the high-temperature side outlet of the precooler is connected to the compressor inlet, and the compressor outlet is connected to the injection well inlet.

[0013] A further improvement of the present invention is that the tower photothermal system is connected to a molten salt heat storage system, the molten salt heat storage system is connected to the molten salt side inlet of the molten salt-supercritical carbon dioxide heat exchanger, and the molten salt side outlet of the molten salt-supercritical carbon dioxide heat exchanger is connected to the tower photothermal system via the molten salt heat storage system.

[0014] A further improvement of the present invention is that a filter is provided between the recovery well and the regenerator.

[0015] A further improvement of the present invention is that the injection well and the recovery well are arranged concentrically, the inner layer is the recovery well, the outer layer is the injection well, and the bottoms of the injection well and the recovery well are connected.

[0016] A further improvement of the present invention is that a heat insulation layer is provided between the injection well and the recovery well.

[0017] A further improvement of the present invention is that a heat absorption layer is provided between the injection well and the geothermal layer.

[0018] A further improvement of the present invention is that the tower-type solar thermal system includes a heliostat field, a heat absorption tower and a heat absorber; the heliostat field is arranged on the ground, the heat absorber is located at the top of the heat absorption tower, and the heat absorber outlet is connected to the molten salt heat storage system.

[0019] A further improvement of the present invention is that the molten salt heat storage system includes a high-temperature molten salt tank, a high-temperature molten salt pump, a low-temperature molten salt tank and a low-temperature molten salt pump; the tower-type solar thermal system is connected to the inlet of the high-temperature molten salt tank, the outlet of the high-temperature molten salt tank is connected to the inlet of the high-temperature molten salt pump, the outlet of the high-temperature molten salt pump is connected to the molten salt side inlet of the molten salt-supercritical carbon dioxide heat exchanger, the molten salt side outlet of the molten salt-supercritical carbon dioxide heat exchanger is connected to the inlet of the low-temperature molten salt tank, and the outlet of the low-temperature molten salt tank is connected to the inlet of the absorber via the low-temperature molten salt pump.

[0020] A further improvement of the present invention is that a high-temperature molten salt regulating valve is provided between the high-temperature molten salt pump outlet and the molten salt side inlet of the molten salt-supercritical carbon dioxide heat exchanger; and a low-temperature molten salt regulating valve is provided between the low-temperature molten salt pump outlet and the absorber inlet.

[0021] A method for operating a supercritical carbon dioxide solar thermal power generation system using geothermal energy comprises the following steps:

[0022] When there is sufficient sunlight, the low-temperature molten salt absorbs the light and heat through the tower-type solar thermal system and heats up to high-temperature molten salt, which then enters the high-temperature molten salt tank to store the light and heat.

[0023] When the sunlight is insufficient, the high-temperature molten salt enters the molten salt side of the molten salt-supercritical carbon dioxide heat exchanger from the high-temperature molten salt tank, and transfers the heat energy to the supercritical carbon dioxide on the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger, thus realizing the transfer of heat energy;

[0024] The pressurized supercritical carbon dioxide flows into the injection well, absorbs geothermal heat from the geothermal layer for preheating while flowing downward, and flows upward along the recovery well after reaching the bottom of the injection well. After being filtered, it enters the low-temperature side of the regenerator, and then enters the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger, completing the entire heat absorption process. After absorbing heat, the high-temperature and high-pressure supercritical carbon dioxide expands in the turbine and does work to drive the generator to generate electricity. It flows through the high-temperature side of the regenerator and the high-temperature side of the precooler in turn, and enters the compressor, completing the supercritical carbon dioxide power generation cycle.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention integrates supercritical carbon dioxide solar thermal power generation with geothermal power generation, making full use of medium and low temperature geothermal energy and high temperature solar thermal energy; using supercritical carbon dioxide as the heat carrier medium of the geothermal system solves the problems existing in the traditional geothermal system using water as the heat carrier medium.

[0027] Furthermore, the injection well and the recovery well are arranged concentrically, and a coaxial single-well geothermal well is adopted, which integrates the geothermal well into the bottom of the heat absorption tower of the solar thermal power generation system. The system has a high degree of integration and reduces the construction area and cost.

[0028] Furthermore, in the present invention, by setting a low-temperature molten salt regulating valve and adjusting the opening of the low-temperature molten salt regulating valve, the heat absorption and heat storage can be regulated. By setting a high-temperature molten salt regulating valve and adjusting the opening of the high-temperature molten salt regulating valve, the heat release can be regulated.

[0029] Furthermore, the present invention uses natural geothermal layers as pressure vessels for supercritical carbon dioxide storage and flow regulation.

[0030] Furthermore, in the present invention, by providing a heat insulating layer, it is ensured that the supercritical carbon dioxide after preheating in the recovery well and the supercritical carbon dioxide during preheating in the injection well do not exchange heat.

[0031] Furthermore, in the present invention, a heat absorption layer is provided between the injection well and the geothermal layer, and supercritical carbon dioxide pressurized by a compressor flows into the injection well, and the heat absorption layer absorbs the geothermal heat of the geothermal layer, thereby achieving the purpose of fully utilizing the geothermal heat.

[0032] When the system of the present invention is in operation, when there is sufficient light, the low-temperature molten salt absorbs light and heat through the tower-type photothermal system and heats up to high-temperature molten salt, and enters the high-temperature molten salt tank to achieve the storage of light and heat; when there is insufficient light, the high-temperature molten salt enters the molten salt side of the molten salt-supercritical carbon dioxide heat exchanger from the high-temperature molten salt tank, and transfers the heat energy to the supercritical carbon dioxide on the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger, so as to achieve the transfer of heat energy. The supercritical carbon dioxide after the boost flows into the injection well, and absorbs the geothermal heat of the geothermal layer while flowing downward for preheating. After the preheated supercritical carbon dioxide reaches the bottom of the injection well, it flows upward along the recovery well, enters the low-temperature side of the regenerator after filtration, and then enters the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger to complete the entire heat absorption process. The high-temperature and high-pressure supercritical carbon dioxide after heat absorption expands in the turbine to drive the generator to generate electricity, flows through the high-temperature side of the regenerator and the high-temperature side of the precooler in turn, and enters the compressor to complete the entire supercritical carbon dioxide power generation cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. The following drawings are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute a limitation of the present invention. In the drawings:

[0034] Figure 1 This is a schematic diagram of a supercritical carbon dioxide solar thermal power generation system that uses geothermal energy.

[0035] Figure 1 In the figure, 1 is the heliostat field, 2 is the absorption tower, 3 is the absorber, 4 is the high-temperature molten salt tank, 5 is the high-temperature molten salt pump, 6 is the high-temperature molten salt regulating valve, 7 is the molten salt-supercritical carbon dioxide heat exchanger, 8 is the low-temperature molten salt tank, 9 is the low-temperature molten salt pump, 10 is the low-temperature molten salt regulating valve, 11 is the filter, 12 is the regenerator, 13 is the turbine, 14 is the precooler, 15 is the compressor, 16 is the injection well, 17 is the recovery well, 18 is the insulation layer, 19 is the geothermal layer, and 20 is the absorption layer. DETAILED DESCRIPTION

[0036] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0037] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0038] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like 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, an electrical connection, or a communication; 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.

[0040] 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 above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0041] Tower solar thermal power generation is a solar thermal power generation technology with high technical maturity and wide application. It is matched with efficient and compact supercritical carbon dioxide cycle and molten salt heat storage suitable for medium and high temperature heat sources, and is expected to play an important role in the power system with new energy as the main body.

[0042] The supercritical carbon dioxide photothermal power generation system utilizing geothermal energy in the present invention integrates supercritical carbon dioxide photothermal power generation with geothermal power generation, which not only makes full use of medium and low temperature geothermal energy and high temperature photothermal energy, but also adopts a coaxial single well geothermal well form, and integrates the geothermal well into the bottom of the heat absorption tower, thereby reducing the pipeline system, construction area and cost; using supercritical carbon dioxide as the heat carrier medium of the geothermal system solves the problems existing in the traditional geothermal system using water as the heat carrier medium: serious water leakage, resulting in waste of water resources; water reacts with rock formations to produce mineral precipitation, which blocks the pipeline.

[0043] like Figure 1 As shown, a supercritical carbon dioxide photothermal power generation system utilizing geothermal energy of the present invention comprises a tower photothermal system, a geothermal utilization system, a supercritical carbon dioxide power generation system and a molten salt heat storage system. The tower photothermal system and the molten salt heat storage system realize the absorption and storage of photothermal energy, and the geothermal utilization system and the supercritical carbon dioxide power generation system realize the utilization of geothermal energy and photothermal energy.

[0044] The tower-type solar thermal system includes a heliostat field 1 , a heat absorption tower 2 and a heat absorber 3 ; the geothermal utilization system includes a filter 11 , an injection well 16 , a recovery well 17 and a geothermal layer 19 .

[0045] Specifically, a heat insulating layer 18 is provided between the injection well 16 and the recovery well 17 , and a heat absorbing layer 20 is provided between the injection well 16 and the geothermal layer 19 .

[0046] Furthermore, the injection well 16 and the recovery well 17 are arranged in concentric circular tubes, the inner circular tube is the recovery well 17, and the outer circular tube is the injection well 16, both of which are located at the bottom of the heat absorption tower 2 and deep into the geothermal layer 19, and the injection well 16 is connected to the bottom of the recovery well 17.

[0047] In one embodiment of the present invention, the supercritical carbon dioxide power generation system adopts a simple layout, including a molten salt-supercritical carbon dioxide heat exchanger 7, a regenerator 12, a turbine 13, a precooler 14 and a compressor 15.

[0048] The molten salt heat storage system includes a high-temperature molten salt tank 4 , a high-temperature molten salt pump 5 , a high-temperature molten salt regulating valve 6 , a low-temperature molten salt tank 8 , a low-temperature molten salt pump 9 and a low-temperature molten salt regulating valve 10 .

[0049] In one embodiment of the present invention, the heliostat field 1 is located on the ground, the absorber 3 is located at the top of the absorber tower 2, the outlet of the absorber 3 is connected to the inlet of the high-temperature molten salt tank 4, the outlet of the high-temperature molten salt tank 4 is connected to the inlet of the high-temperature molten salt pump 5, the outlet of the high-temperature molten salt pump 5 is connected to the inlet of the high-temperature molten salt regulating valve 6, the outlet of the high-temperature molten salt regulating valve 6 is connected to the molten salt side inlet of the molten salt-supercritical carbon dioxide heat exchanger 7, the molten salt side outlet of the molten salt-supercritical carbon dioxide heat exchanger 7 is connected to the inlet of the low-temperature molten salt tank 8, the outlet of the low-temperature molten salt tank 8 is connected to the inlet of the low-temperature molten salt pump 9, the outlet of the low-temperature molten salt pump 9 is connected to the inlet of the low-temperature molten salt regulating valve 10, and the outlet of the low-temperature molten salt regulating valve 10 is connected to the inlet of the absorber 3.

[0050] Furthermore, the outlet of the recovery well 17 is connected to the inlet of the filter 11, the outlet of the filter 11 is connected to the low-temperature side inlet of the regenerator 12, the low-temperature side outlet of the regenerator 12 is connected to the supercritical carbon dioxide side inlet of the molten salt-supercritical carbon dioxide heat exchanger 7, the supercritical carbon dioxide side outlet of the molten salt-supercritical carbon dioxide heat exchanger 7 is connected to the inlet of the turbine 13, the outlet of the turbine 13 is connected to the high-temperature side inlet of the regenerator 12, the high-temperature side outlet of the regenerator 12 is connected to the high-temperature side inlet of the precooler 14, the high-temperature side outlet of the precooler 14 is connected to the inlet of the compressor 15, and the outlet of the compressor 15 is connected to the inlet of the injection well 16.

[0051] The working process of the above-mentioned supercritical carbon dioxide solar thermal power generation system using geothermal energy is as follows:

[0052] When there is sufficient sunlight, the heliostat field 1 reflects the incident sunlight and converges it on the surface of the absorber 3 at the top of the absorption tower 2. The low-temperature molten salt pump 9 is turned on, and the low-temperature molten salt regulating valve 10 is adjusted to make the low-temperature molten salt flow out of the low-temperature molten salt tank 8, enter the absorber 3 to absorb light heat and heat up to become high-temperature molten salt, and flow into the high-temperature molten salt tank 4 to achieve the storage of light heat; when there is insufficient sunlight, the high-temperature molten salt pump 5 is turned on, and the high-temperature molten salt regulating valve 6 is adjusted to make the high-temperature molten salt flow out of the high-temperature molten salt tank 4, enter the molten salt side of the molten salt-supercritical carbon dioxide heat exchanger 7, and transfer the heat energy to the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger 7 to achieve the transfer of heat energy. The low-temperature molten salt after heat exchange then enters the low-temperature molten salt tank 8.

[0053] The supercritical carbon dioxide after being pressurized by the compressor 15 flows into the injection well 16, absorbs the geothermal heat of the geothermal layer 19 through the heat absorption layer 20, and the preheated supercritical carbon dioxide reaches the bottom of the injection well 16 and flows upward along the recovery well 17. The insulation layer 18 ensures that the supercritical carbon dioxide after preheating in the recovery well 17 does not exchange heat with the supercritical carbon dioxide during preheating in the injection well 16. The supercritical carbon dioxide flowing upward along the recovery well 17 then enters the filter 11 to filter out possible impurity particles, and the filtered supercritical carbon dioxide flows into the low-temperature side of the regenerator 12 to absorb the exhaust gas waste heat from the high-temperature side of the regenerator 12, and then enters the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger 7 to complete the entire heat absorption process. The high-temperature and high-pressure supercritical carbon dioxide expands in the turbine 13 to do work and drives the generator to generate electricity, and flows through the high-temperature side of the regenerator 12 and the high-temperature side of the precooler 14 in turn, and enters the compressor 15 to complete the entire supercritical carbon dioxide power generation cycle. The present invention uses a natural geothermal layer as a pressure vessel for supercritical carbon dioxide storage and flow regulation.

[0054] In the present invention, the heat absorption and heat storage can be regulated by adjusting the opening of the low-temperature molten salt regulating valve 10, and the heat release can be regulated by adjusting the opening of the high-temperature molten salt regulating valve 6.

[0055] When the sunlight is insufficient, the high-temperature molten salt stored in the high-temperature molten salt tank 4 provides a medium- and high-temperature heat source for the supercritical carbon dioxide power generation system for several hours through the molten salt-supercritical carbon dioxide heat exchanger 7.

[0056] The present invention integrates supercritical carbon dioxide solar thermal power generation with geothermal power generation, making full use of medium-low temperature geothermal energy and high temperature solar thermal energy; using supercritical carbon dioxide as the heat carrier of the geothermal system solves the problems existing when water is used as the heat carrier of the traditional geothermal system. In the present invention, an efficient and compact supercritical carbon dioxide power generation system is used to replace the traditional organic working fluid Rankine cycle power generation system, making full use of medium-low temperature and low-grade geothermal energy to preheat supercritical carbon dioxide.

[0057] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

Claims

1. A supercritical carbon dioxide solar thermal power generation system using geothermal energy, characterized in that: Including tower solar thermal system, geothermal utilization system, supercritical carbon dioxide power generation system and molten salt heat storage system; The geothermal utilization system comprises an injection well (16) and a recovery well (17) arranged in a geothermal layer (19); The supercritical carbon dioxide power generation system comprises a molten salt-supercritical carbon dioxide heat exchanger (7), a regenerator (12), a turbine (13), a precooler (14) and a compressor (15); The tower-type photothermal system is connected to a molten salt heat storage system, and the molten salt heat storage system is connected to the molten salt side of a molten salt-supercritical carbon dioxide heat exchanger (7); The outlet of the recovery well (17) is connected to the low temperature side inlet of the regenerator (12), the low temperature side outlet of the regenerator (12) is connected to the supercritical carbon dioxide side inlet of the molten salt-supercritical carbon dioxide heat exchanger (7), the supercritical carbon dioxide side outlet of the molten salt-supercritical carbon dioxide heat exchanger (7) is connected to the inlet of the turbine (13), the outlet of the turbine (13) is connected to the high temperature side inlet of the regenerator (12), the high temperature side outlet of the regenerator (12) is connected to the high temperature side inlet of the precooler (14), the high temperature side outlet of the precooler (14) is connected to the inlet of the compressor (15), and the outlet of the compressor (15) is connected to the inlet of the injection well (16).

2. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 1, characterized in that: The tower photothermal system is connected to a molten salt heat storage system, the molten salt heat storage system is connected to a molten salt side inlet of a molten salt-supercritical carbon dioxide heat exchanger (7), and the molten salt side outlet of the molten salt-supercritical carbon dioxide heat exchanger (7) is connected to the tower photothermal system via the molten salt heat storage system.

3. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 1, characterized in that: A filter (11) is provided between the recovery well (17) and the regenerator (12).

4. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 1, characterized in that: The injection well (16) and the recovery well (17) are arranged concentrically, the inner layer is the recovery well (17), and the outer layer is the injection well (16), and the bottoms of the injection well (16) and the recovery well (17) are connected.

5. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 1, characterized in that: A heat insulation layer (18) is provided between the injection well (16) and the recovery well (17).

6. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 1, characterized in that: A heat absorption layer (20) is provided between the injection well (16) and the geothermal layer (19).

7. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 1, characterized in that: The tower-type solar thermal system comprises a heliostat field (1), a heat absorption tower (2) and a heat absorber (3); the heliostat field (1) is arranged on the ground, the heat absorber (3) is located at the top of the heat absorption tower (2), and the outlet of the heat absorber (3) is connected to the molten salt heat storage system; and the recovery well (17) is arranged at the bottom of the heat absorption tower (2).

8. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 1, characterized in that: The molten salt heat storage system comprises a high-temperature molten salt tank (4), a high-temperature molten salt pump (5), a low-temperature molten salt tank (8) and a low-temperature molten salt pump (9); the tower-type photothermal system is connected to the inlet of the high-temperature molten salt tank (4), the outlet of the high-temperature molten salt tank (4) is connected to the inlet of the high-temperature molten salt pump (5), the outlet of the high-temperature molten salt pump (5) is connected to the inlet of the molten salt side of the molten salt-supercritical carbon dioxide heat exchanger (7), the outlet of the molten salt side of the molten salt-supercritical carbon dioxide heat exchanger (7) is connected to the inlet of the low-temperature molten salt tank (8), and the outlet of the low-temperature molten salt tank (8) is connected to the inlet of the heat absorber (3) via the low-temperature molten salt pump (9).

9. The supercritical carbon dioxide solar thermal power generation system using geothermal energy according to claim 8, characterized in that: A high-temperature molten salt regulating valve (6) is provided between the outlet of the high-temperature molten salt pump (5) and the molten salt side inlet of the molten salt-supercritical carbon dioxide heat exchanger (7); and a low-temperature molten salt regulating valve (10) is provided between the outlet of the low-temperature molten salt pump (9) and the inlet of the heat absorber (3).

10. An operating method of a geothermal supercritical carbon dioxide solar thermal power generation system as claimed in claim 8, characterized in that: The following steps are involved: When there is sufficient sunlight, the low-temperature molten salt absorbs the light and heat through the tower-type photothermal system and heats up to become high-temperature molten salt, which then enters the high-temperature molten salt tank (4) to achieve storage of light and heat. When the sunlight is insufficient, the high-temperature molten salt enters the molten salt side of the molten salt-supercritical carbon dioxide heat exchanger from the high-temperature molten salt tank, and transfers the heat energy to the supercritical carbon dioxide on the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger, thus realizing the transfer of heat energy; The supercritical carbon dioxide after the pressure increase flows into the injection well (16), and while flowing downward, absorbs the geothermal heat of the geothermal layer for preheating. After reaching the bottom of the injection well (16), it flows upward along the recovery well (17), enters the low-temperature side of the regenerator after being filtered, and then enters the supercritical carbon dioxide side of the molten salt-supercritical carbon dioxide heat exchanger (7), completing the entire heat absorption process. The high-temperature and high-pressure supercritical carbon dioxide after absorbing heat expands in the turbine (13) to drive the generator to generate electricity, and flows through the high-temperature side of the regenerator (12) and the high-temperature side of the precooler (14) in turn, and enters the compressor (15), completing the supercritical carbon dioxide power generation cycle.

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