Desert tower type solar CO2 power generation and impurity removal system and use method thereof

Abstract

The invention provides a desert tower type solar CO2 power generation and impurity removal system which comprises a heliostat field and a heat absorber arranged on a heat absorption tower, the heat absorber is connected with a fused salt heat storage subsystem, the fused salt heat storage subsystem is connected with a CO2 power generation subsystem through a heater, and the CO2 power generation subsystem is connected with a CO2 power generation system. The CO2 power generation subsystem is connected with the lithium bromide solution absorption type refrigerating unit through a high-temperature cooler and a low-temperature cooler, and an impurity removal system loop is arranged in the CO2 power generation subsystem. The lithium bromide solution absorption type refrigerating unit is driven by waste heat of expanded CO2 to produce cold energy, so that CO2 is cooled to be close to a critical point or condensed into liquid to adapt to the temperature change of the desert environment; the gas-liquid separator is adopted to separate impurity gas in liquid CO2, so that the CO2 purity of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar power generation, and in particular to a desert tower type solar CO2 power generation and impurity removal system and a use method thereof. Background Art

[0002] Due to the instability of solar energy, molten salt heat storage is usually used to stabilize the system's power output and support the system's nighttime operation. As the most promising power generation cycle in the future, the supercritical CO2 cycle has been widely used in solar thermal power generation. For the supercritical CO2 power generation cycle, its high efficiency is mainly due to the fact that the compressor significantly reduces the compression power consumption when compressing near the critical point of CO2. When the external ambient temperature is significantly higher than the critical point, the efficiency of the supercritical CO2 power generation system will drop significantly. At present, areas with relatively rich solar thermal resources are mostly located in deserts and other arid and severely water-scarce areas, where the ambient temperature is relatively high. For example, in the Sahara Desert, the temperature can reach above 50°C during the day, while the temperature can drop to below -10°C at night. The huge temperature difference poses significant challenges to the operation of the system.

[0003] Comparative document CN111749862A discloses a supercritical Brayton cycle solar thermal power generation system and a power generation method using a mixture working fluid, and the protected claim is "including a solar thermal heat source input subsystem and a supercritical CO2 and SF6 mixture working fluid power cycle power generation subsystem; the present invention uses a supercritical CO2 and SF6 mixture as the working fluid, and when the working fluid temperature at the inlet of the main compressor in the solar thermal power generation system deviates greatly from the critical temperature of supercritical CO2, the power generation efficiency of the solar thermal power generation system can be significantly improved. In addition, during the operation of the circulation system, the flow rate of the working fluid entering the particle-sCO2 heat exchanger is adjusted by a shunt control valve, which can effectively solve the problem of controlling the turbine inlet working fluid temperature by the particle-sCO2 heat exchanger in the system, and significantly improve the operating efficiency and peak-shaving flexibility of the entire solar thermal power generation system." However, the proportion of the mixture during operation is difficult to control, and the cost of SF6 is higher than that of CO2, making it difficult to apply in actual engineering; how to effectively solve the effective cooling of CO2 in desert areas is the main problem currently faced. In addition, the CO2 power generation system will inevitably be mixed with impurity gases such as N2 and O2. How to remove impurities during operation to ensure system efficiency is also an urgent issue to be solved.

[0004] Therefore, there is an urgent need to propose a desert tower solar CO2 power generation and impurity removal system and a method of using the system to solve the above problems. Summary of the invention

[0005] The present invention proposes a tower solar CO2 power generation system for deserts, which includes a tower concentrating heat collection subsystem, a molten salt heat storage subsystem, a CO2 power cycle and an absorption refrigeration cycle. When the temperature in the desert is high during the day, the waste heat of CO2 after work is used to drive a lithium bromide solution absorption refrigeration unit to produce cold capacity, so as to further cool the CO2 and reduce its temperature to near the critical point to improve the system efficiency. When the temperature in the desert is low at night, the CO2 can be condensed into a liquid phase, and the CO2 power cycle operates transcritically. At the same time, when the CO2 purity of the system is measured to be low, a gas-liquid separator is used to separate the liquid CO2 from the impurity gas, so as to exclude the impurities from the system. A desert tower solar CO2 power generation and impurity removal system and a method of using the same are hereby provided to solve the problems raised in the background technology.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a desert tower solar CO2 power generation and impurity removal system, including a heliostat field and a heat absorber arranged on the heat absorption tower, the heat absorber is connected to a molten salt heat storage subsystem, the molten salt heat storage subsystem is connected to a CO2 power generation subsystem through a heater, the CO2 power generation subsystem is connected through a high-temperature cooler, a low-temperature cooler and a lithium bromide solution absorption refrigeration unit, and the CO2 power generation subsystem is provided with an impurity removal system loop.

[0007] Preferably, the molten salt heat storage subsystem mainly includes a molten salt hot tank and a molten salt cold tank, the heat absorber outlet is connected to the molten salt hot tank inlet, the molten salt hot tank outlet is connected to the heater heat medium side inlet, the heater heat medium side outlet is connected to the No. 1 pump inlet, the No. 1 pump outlet is connected to the molten salt cold tank inlet, the molten salt cold tank outlet is connected to the No. 2 pump inlet, and the No. 2 pump outlet is connected to the heat absorber inlet.

[0008] Preferably, a first valve is provided between the outlet of the heat absorber and the inlet of the molten salt hot tank, a second valve is provided between the outlet of the heater on the heat medium side and the inlet of the first pump, and a third valve is provided between the outlet of the molten salt cold tank and the inlet of the second pump.

[0009] Preferably, the CO2 power generation subsystem includes a turbine, the turbine outlet is connected to the high temperature medium side inlet of the regenerator, the high temperature medium side outlet of the regenerator is connected to the high temperature medium side inlet of the high temperature cooler, the high temperature medium side outlet of the high temperature cooler is connected to the inlet of the air cooler, and the air cooler outlet is connected to the heat medium side inlet of the low temperature cooler.

[0010] Preferably, the outlet on the heat medium side of the low-temperature cooler is provided with a tee which is divided into passage one and passage two, the passage one is connected to the compressor inlet, the compressor outlet is connected to the inlet on the cold fluid side of the regenerator, the outlet on the cold fluid side of the regenerator is connected to the inlet on the heat absorption medium side of the heater, the outlet on the heat absorption medium side of the heater is connected to the turbine inlet, the passage two is connected to the inlet of the impurity removal system loop, the outlet of the impurity removal system loop is connected to the inlet on the cold fluid side of the regenerator, a fourth valve is provided on the pipeline between the compressor outlet and the inlet on the cold fluid side of the regenerator, and the pipeline position between the outlet end of the fourth valve and the inlet on the cold fluid side of the regenerator is connected to the outlet of the impurity removal system loop.

[0011] Preferably, the impurity removal system loop includes a gas-liquid separator, the outlet of the gas-liquid separator is connected to the inlet of the CO2 storage tank, the outlet of the CO2 storage tank is connected to the inlet of the No. 3 pump, the outlet of the No. 3 pump is connected to the pipeline at the inlet of the cold fluid side of the regenerator through the fifth valve, and an exhaust valve for releasing non-condensable impurity gas is provided on one side of the gas-liquid separator.

[0012] Preferably, the lithium bromide solution absorption refrigeration unit includes a solution heat exchanger, the hot fluid side inlet of the solution heat exchanger is connected to the cold fluid side outlet of the high-temperature cooler, the hot fluid side outlet of the solution heat exchanger is connected to the absorber inlet through a first throttle valve, the absorber outlet is connected to the cold fluid side inlet of the solution heat exchanger through a No. 4 pump, and the cold fluid side outlet of the solution heat exchanger is connected to the cold fluid side inlet of the high-temperature cooler.

[0013] Preferably, the water vapor formed by evaporation in the high-temperature cooler enters the condenser through the condenser inlet, the condenser outlet is connected to the second throttle valve inlet, the condensed water flows into the cold fluid side of the low-temperature cooler through the second throttle valve to release cold energy to further cool the CO2, and the cold fluid side of the low-temperature cooler transfers the water vapor generated by absorption of heat to the absorber to release heat and dissipate it to the environment through the air.

[0014] In addition, the present invention also discloses a method for using a desert tower solar CO2 power generation and impurity removal system, which includes the following process: S1: The solar rays are reflected to the absorber on the heat absorption tower through the heliostat field, thereby converting the solar energy into heat energy; S2: The absorber absorbs solar energy and converts it into heat energy. The third valve is opened, and the low-temperature molten salt flowing out of the molten salt cold tank enters the absorber through the second pump; S3: The low-temperature molten salt absorbs heat energy in the heat absorber and becomes high-temperature molten salt. The first valve is opened, and part of the high-temperature molten salt is stored in the molten salt hot tank, while the other part of the high-temperature molten salt flows through the heater to release heat and become low-temperature molten salt. S4: After passing through the second valve, part of the low-temperature molten salt is stored in the molten salt cold tank, and part of it enters the absorber again through the second pump; S5: CO2 absorbs the heat of high-temperature molten salt through the heater, then expands through the turbine to generate electricity, then flows through the regenerator and high-temperature cooler to release heat, and then cools through the air cooler; S6: The waste heat of CO2 absorbed from the high-temperature cooler drives the lithium bromide solution absorption refrigeration unit to produce cold energy, so that the CO2 in the low-temperature cooler is further cooled; S7: When the ambient temperature is high and CO2 cannot be condensed into a liquid state from the cryocooler, CO2 comes out of the cryocooler and directly enters the compressor through passage 1 for pressure boosting, then enters the regenerator to absorb heat, and then flows into the heater to form a supercritical CO2 power cycle; S8: When the ambient temperature is low, the temperature of CO2 at the outlet of the air cooler is relatively low, so that the lithium bromide solution absorption refrigeration unit can condense CO2 into liquid. At this time, the fourth valve is closed, and the liquid CO2 enters the gas-liquid separator through the second passage. If the CO2 contains impurities, the gas-liquid separator can be used to remove impurities and discharge non-condensable gas impurities through the exhaust valve; S9: The liquid CO2 in the gas-liquid separator enters the CO2 storage tank, and after being pressurized by the No. 3 pump, the fifth valve is opened to enter the regenerator and heater, thereby forming a transcritical CO2 power cycle.

[0015] Furthermore, the specific method steps of the lithium bromide solution absorption refrigeration unit in S6 in the system are: S6.1: The dilute lithium bromide solution absorbs the heat of CO2 in the high-temperature cooler and becomes a concentrated lithium bromide solution, which then enters the solution heat exchanger to exchange heat with the dilute lithium bromide solution to reduce the temperature; S6.2: After passing through the first throttle valve, it enters the absorber, absorbs the water vapor from the low-temperature cooler to form a dilute lithium bromide solution and releases heat. The dilute lithium bromide solution is pressurized by the No. 4 pump and enters the solution heat exchanger, and finally enters the high-temperature cooler to complete the solution circulation loop; S6.3: In the high temperature cooler, water vapor evaporated from the dilute lithium bromide solution enters the condenser and condenses to form liquid water; S6.4: Liquid water passes through the second throttle valve, undergoes pressure reduction and temperature reduction, and finally enters the low-temperature cooler to evaporate and release cold energy, further cooling the CO2 to form a complete water vapor circulation loop.

[0016] The present invention has the following beneficial effects: 1. The present invention is aimed at the solar thermal CO2 power generation system in desert areas, which can use the waste heat of expanded CO2 to produce cold energy to achieve the cooling or condensation of CO2, thereby ensuring the power generation efficiency of the system; 2. After condensing CO2, the present invention uses a gas-liquid separator to remove impurity gases from the system, thereby improving the purity of CO2 in the system circulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the circulation system structure of the present invention; Figure 2 It is a structural schematic diagram of the lithium bromide solution absorption refrigeration unit in the present invention. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: See also Figure 1 to Figure 2 A desert tower solar CO2 power generation and impurity removal system includes a heliostat field 1 and a heat absorber 3 arranged on a heat absorption tower 2, wherein the heat absorber 3 is connected to a molten salt heat storage subsystem 4, wherein the molten salt heat storage subsystem is connected to a CO2 power generation subsystem 6 through a heater 5, wherein the CO2 power generation subsystem 6 is connected to a lithium bromide solution absorption refrigeration unit 9 through a high-temperature cooler 7, a low-temperature cooler 8, and a CO2 power generation subsystem 6. An impurity removal system loop 10 is provided in the CO2 power generation subsystem 6. When the sunlight is sufficient during the day, in the tower-type concentrating heat collection subsystem, the heliostat field 1 reflects the sunlight onto the heat absorber 3, thereby converting the solar energy into heat energy.

[0019] Preferably, the molten salt heat storage subsystem 4 mainly includes a molten salt hot tank 4.1 and a molten salt cold tank 4.2, the outlet of the heat absorber 3 is connected to the inlet of the molten salt hot tank 4.1, the outlet of the molten salt hot tank 4.1 is connected to the inlet of the heat medium side of the heater 5, the outlet of the heat medium side of the heater 5 is connected to the inlet of pump No. 1 4.3, the outlet of pump No. 1 4.3 is connected to the inlet of the molten salt cold tank 4.2, the outlet of the molten salt cold tank 4.2 is connected to the inlet of pump No. 2 4.4, and the outlet of pump No. 2 4.4 is connected to the inlet of the heat absorber 3. In the molten salt heat storage subsystem 4, the absorber 3 absorbs solar energy and converts it into thermal energy. The low-temperature molten salt flowing out of the molten salt cold tank 4.2 enters the absorber 3 through a pump, absorbs thermal energy and becomes high-temperature molten salt. Part of the high-temperature molten salt is stored in the molten salt hot tank 4.1, and the other part of the high-temperature molten salt flows through the heater 5 to release heat. Part of the low-temperature molten salt is stored in the molten salt cold tank 4.2, and the other part is pumped into the absorber 3 again to absorb heat; at night, the high-temperature molten salt stored in the molten salt heat storage subsystem 4 provides heat to the CO2 power cycle.

[0020] Preferably, a first valve 4.5 is provided between the outlet of the heat absorber 3 and the inlet of the molten salt hot tank 4.1, a second valve 4.6 is provided between the outlet of the heat medium side of the heater 5 and the inlet of the first pump 4.3, and a third valve 4.7 is provided between the outlet of the molten salt cold tank 4.2 and the inlet of the second pump 4.4.

[0021] Preferably, the CO2 power generation subsystem 6 includes a turbine 6.1, the outlet of the turbine 6.1 is connected to the inlet of the high temperature medium side of the heat regenerator 6.2, the outlet of the high temperature medium side of the heat regenerator 6.2 is connected to the inlet of the high temperature medium side of the high temperature cooler 7, the outlet of the high temperature medium side of the high temperature cooler 7 is connected to the inlet of the air cooler 6.3, and the outlet of the air cooler 6.3 is connected to the inlet of the hot medium side of the low temperature cooler 8.

[0022] Preferably, the outlet on the heat medium side of the low-temperature cooler 8 is provided with a three-way connection divided into a passage one 6.4 and a passage two 6.5, the passage one 6.4 is connected to the inlet of the compressor 6.6, the outlet of the compressor 6.6 is connected to the inlet on the cold fluid side of the heat regenerator 6.2, the outlet on the cold fluid side of the heat regenerator 6.2 is connected to the inlet on the heat absorption medium side of the heater 5, the outlet on the heat absorption medium side of the heater 5 is connected to the inlet of the turbine 6.1, the passage two 6.5 is connected to the inlet of the impurity removal system loop 10, the outlet of the impurity removal system loop 10 is connected to the inlet on the cold fluid side of the heat regenerator 6.2, a fourth valve 6.7 is provided on the pipeline between the outlet of the compressor 6.6 and the inlet on the cold fluid side of the heat regenerator 6.2, and the pipeline position between the outlet end of the fourth valve 6.7 and the inlet on the cold fluid side of the heat regenerator 6.2 is connected to the outlet of the impurity removal system loop 10.

[0023] Preferably, the impurity removal system loop 10 includes a gas-liquid separator 10.1, the outlet of the gas-liquid separator 10.1 is connected to the inlet of the CO2 storage tank 10.2, the outlet of the CO2 storage tank 10.2 is connected to the inlet of the third pump 10.3, the outlet of the third pump 10.3 is connected to the pipeline at the inlet of the cold fluid side of the regenerator 6.2 through the fifth valve 10.4, and an exhaust valve 10.5 for releasing non-condensable impurity gas is provided on one side of the gas-liquid separator 10.1. When the CO2 purity measured in the gas-liquid separator 10.1 decreases, the exhaust valve 10.5 is opened to discharge the impurity gas, and the liquid CO2 is stored in the CO2 storage tank 10.2.

[0024] Preferably, the lithium bromide solution absorption refrigeration unit 9 includes a solution heat exchanger 9.1, the hot fluid side inlet of the solution heat exchanger 9.1 is connected to the cold fluid side outlet of the high-temperature cooler 7, the hot fluid side outlet of the solution heat exchanger 9.1 is connected to the inlet of the absorber 9.3 through a first throttle valve 9.2, the outlet of the absorber 9.3 is connected to the cold fluid side inlet of the solution heat exchanger 9.1 through a No. 4 pump 9.4, and the cold fluid side outlet of the solution heat exchanger 9.1 is connected to the cold fluid side inlet of the high-temperature cooler 7.

[0025] Preferably, the water vapor formed by evaporation in the high-temperature cooler 7 enters the condenser through the inlet of the condenser 9.5, and the outlet of the condenser 9.5 is connected to the inlet of the second throttle valve 9.6. The condensed water flows into the cold fluid side of the low-temperature cooler 8 through the second throttle valve 9.6 to release cold energy to further cool the CO2. The cold fluid side of the low-temperature cooler 8 transfers the water vapor generated by absorption of heat to the absorber 9.3 to release heat and dissipate it to the environment through the air. The dilute solution absorbs the heat of CO2 in the high-temperature cooler 7 (equivalent to the generator of the refrigeration system) and becomes a concentrated solution, which then enters the solution heat exchanger 9.1 to exchange heat with the dilute solution for cooling, and then enters the absorber 9.3 after passing through the first throttle valve 9.2, and absorbs water vapor from the low-temperature cooler 8 (equivalent to the evaporator of the refrigeration system) to form a dilute solution and release heat. The dilute solution is pressurized by the No. 4 pump 9.4 and enters the solution heat exchanger 9.1, and finally enters the high-temperature cooler 7 to complete the solution circulation loop; in the high-temperature cooler 7, the evaporated water vapor is then condensed by the condenser 9.5 to form liquid water, and then the liquid water passes through the second throttle valve 9.6 to reduce pressure and temperature, and finally enters the low-temperature cooler 8 to evaporate, thereby releasing cold energy, further cooling CO2, and forming a complete water vapor circulation loop.

[0026] In addition, the present invention also discloses a method for using a desert tower solar CO2 power generation and impurity removal system, which includes the following process: S1: The solar rays are reflected by the heliostat field 1 to the heat absorber 3 arranged on the heat absorption tower 2, thereby converting the solar energy into heat energy; S2: The heat absorber 3 absorbs solar energy and converts it into heat energy. The third valve 4.7 is opened, and the low-temperature molten salt flowing out of the molten salt cold tank 4.2 enters the heat absorber 3 through the second pump 4.4; S3: The low-temperature molten salt absorbs heat energy in the heat absorber 3 and becomes high-temperature molten salt. The first valve 4.5 is opened, and a part of the high-temperature molten salt is stored in the molten salt hot tank 4.1, and the other part of the high-temperature molten salt flows through the heater 5 to release heat and become low-temperature molten salt; S4: After passing through the second valve 4.6, part of the low-temperature molten salt is stored in the molten salt cold tank 4.2, and part of it enters the heat absorber 3 again through the second pump 4.4; S5: CO2 absorbs heat from the high-temperature molten salt through the heater 5, then expands through the turbine 6.1 to generate electricity, then flows through the regenerator 6.2 and the high-temperature cooler 7 to release heat, and then is cooled through the air cooler 6.3; S6: The waste heat of CO2 absorbed from the high temperature cooler 7 drives the lithium bromide solution absorption refrigeration unit 9 to produce cold energy, so that the CO2 in the low temperature cooler 8 is further cooled; S7: When the ambient temperature is high and CO2 cannot be condensed into a liquid state from the cryocooler 8, CO2 directly enters the compressor 6.6 through the passage 1 6.4 to increase the pressure after coming out of the cryocooler 8, and then enters the regenerator 6.2 to absorb heat, and then flows into the heater 5 to form a supercritical CO2 power cycle; S8: When the ambient temperature is low, the temperature of CO2 at the outlet of the air cooler 6.3 is relatively low, so that the lithium bromide solution absorption refrigeration unit 9 can condense CO2 into liquid. At this time, the fourth valve 6.7 is closed, and the liquid CO2 enters the gas-liquid separator 10.1 through the second passage 6.5. If the CO2 contains impurities, the gas-liquid separator 10.1 can be used to remove impurities and discharge non-condensable gas impurities through the exhaust valve 10.5; S9: The liquid CO2 in the gas-liquid separator 10.1 enters the CO2 storage tank 10.2, and after being pressurized by the No. 3 pump 10.3, the fifth valve 10.4 is opened to enter the regenerator 6.2 and the heater 5, thereby forming a transcritical CO2 power cycle.

[0027] Furthermore, the specific method steps of the lithium bromide solution absorption refrigeration unit 9 in S6 in the system are: S6.1: The dilute lithium bromide solution absorbs the heat of CO2 in the high temperature cooler 7 and becomes a concentrated lithium bromide solution, which then enters the solution heat exchanger 9.1 to exchange heat with the dilute lithium bromide solution to reduce the temperature; S6.2: After passing through the first throttle valve 9.2, it enters the absorber 9.3, absorbs the water vapor from the low-temperature cooler 8 to form a dilute lithium bromide solution and releases heat. The dilute lithium bromide solution is pressurized by the No. 4 pump 9.4 and enters the solution heat exchanger 9.1, and finally enters the high-temperature cooler 7, completing the solution circulation loop; S6.3: In the high temperature cooler 7, water vapor evaporated from the dilute lithium bromide solution enters the condenser 9.5 and condenses to form liquid water; S6.4: Liquid water passes through the second throttle valve 9.6, undergoes pressure reduction and temperature reduction, and finally enters the low-temperature cooler 8 to evaporate and release cold energy, further cooling the CO2, forming a complete water vapor circulation loop.

[0028] The above embodiments are only preferred technical solutions of the present invention and should not be regarded as limiting the present invention. The protection scope of the present invention shall be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A desert tower solar CO2 power generation and impurity removal system, comprising a heliostat field (1) and a heat absorber (3) arranged on a heat absorption tower (2), characterized in that: The heat absorber (3) is connected to a molten salt heat storage subsystem (4), the molten salt heat storage subsystem is connected to a CO2 power generation subsystem (6) via a heater (5), the CO2 power generation subsystem (6) is connected to a lithium bromide solution absorption refrigeration unit (9) via a high-temperature cooler (7), a low-temperature cooler (8), and a CO2 power generation subsystem (6), and a decontamination system loop (10) is provided in the CO2 power generation subsystem (6).

2. The desert tower solar CO2 power generation and impurity removal system according to claim 1 is characterized by: The molten salt heat storage subsystem (4) mainly comprises a molten salt hot tank (4.1) and a molten salt cold tank (4.2); the outlet of the heat absorber (3) is connected to the inlet of the molten salt hot tank (4.1); the outlet of the molten salt hot tank (4.1) is connected to the inlet of the heat medium side of the heater (5); the outlet of the heat medium side of the heater (5) is connected to the inlet of a No. 1 pump (4.3); the outlet of the No. 1 pump (4.3) is connected to the inlet of the molten salt cold tank (4.2); the outlet of the molten salt cold tank (4.2) is connected to the inlet of a No. 2 pump (4.4); and the outlet of the No. 2 pump (4.4) is connected to the inlet of the heat absorber (3).

3. The desert tower solar CO2 power generation and impurity removal system according to claim 2 is characterized by: A first valve (4.5) is provided between the outlet of the heat absorber (3) and the inlet of the molten salt hot tank (4.1), a second valve (4.6) is provided between the outlet of the heat medium side of the heater (5) and the inlet of the first pump (4.3), and a third valve (4.7) is provided between the outlet of the molten salt cold tank (4.2) and the inlet of the second pump (4.4).

4. The desert tower solar CO2 power generation and impurity removal system according to claim 1 is characterized by: The CO2 generating subsystem (6) comprises a turbine (6.1), wherein the outlet of the turbine (6.1) is connected to the inlet of the high temperature medium side of the heat regenerator (6.2), the outlet of the high temperature medium side of the heat regenerator (6.2) is connected to the inlet of the high temperature medium side of the high temperature cooler (7), the outlet of the high temperature medium side of the high temperature cooler (7) is connected to the inlet of the air cooler (6.3), and the outlet of the air cooler (6.3) is connected to the inlet of the heat medium side of the low temperature cooler (8).

5. The desert tower solar CO2 power generation and impurity removal system according to claim 4 is characterized by: The outlet of the low-temperature cooler (8) on the hot medium side is provided with a three-way connection divided into a passage 1 (6.4) and a passage 2 (6.5). The passage 1 (6.4) is connected to the inlet of the compressor (6.6). The outlet of the compressor (6.6) is connected to the inlet of the cold fluid side of the regenerator (6.2). The outlet of the cold fluid side of the regenerator (6.2) is connected to the inlet of the heat absorbing medium side of the heater (5). The outlet of the heat absorbing medium side of the heater (5) is connected to the inlet of the turbine (6.1). The passage 2 (6.5) is connected to the inlet of the impurity removal system loop (10). The outlet of the impurity removal system loop (10) is connected to the inlet of the cold fluid side of the regenerator (6.2). A fourth valve (6.7) is provided on the pipeline between the outlet of the compressor (6.6) and the inlet of the cold fluid side of the regenerator (6.2). The pipeline position between the outlet end of the fourth valve (6.7) and the inlet of the cold fluid side of the regenerator (6.2) is connected to the outlet of the impurity removal system loop (10).

6. The desert tower solar CO2 power generation and impurity removal system according to claim 1 is characterized by: The impurity removal system loop (10) comprises a gas-liquid separator (10.1), the outlet of the gas-liquid separator (10.1) is connected to the inlet of a CO2 liquid storage tank (10.2), the outlet of the CO2 liquid storage tank (10.2) is connected to the inlet of a third pump (10.3), the outlet of the third pump (10.3) is connected to a pipeline at the inlet of a cold fluid side of a regenerator (6.2) via a fifth valve (10.4), and an exhaust valve (10.5) for releasing non-condensable impurity gas is provided on one side of the gas-liquid separator (10.1).

7. The desert tower solar CO2 power generation and impurity removal system according to claim 1 is characterized by: The lithium bromide solution absorption refrigeration unit (9) comprises a solution heat exchanger (9.1), wherein the hot fluid side inlet of the solution heat exchanger (9.1) is connected to the cold fluid side outlet of the high-temperature cooler (7), the hot fluid side outlet of the solution heat exchanger (9.1) is connected to the absorber (9.3) inlet via a first throttle valve (9.2), the absorber (9.3) outlet is connected to the cold fluid side inlet of the solution heat exchanger (9.1) via a No. 4 pump (9.4), and the cold fluid side outlet of the solution heat exchanger (9.1) is connected to the cold fluid side inlet of the high-temperature cooler (7).

8. The desert tower solar CO2 power generation and impurity removal system according to claim 7 is characterized by: The water vapor generated by evaporation in the high-temperature cooler (7) enters the condenser through the inlet of the condenser (9.5), and the outlet of the condenser (9.5) is connected to the inlet of the second throttle valve (9.6). The condensed water flows into the cold fluid side of the low-temperature cooler (8) through the second throttle valve (9.6) to release cold energy to further cool the CO2. The cold fluid side of the low-temperature cooler (8) transmits the water vapor generated by absorption of heat to the absorber (9.3) to release heat and dissipate it to the environment through air.

9. A method for using a desert tower solar CO2 power generation and impurity removal system according to any one of claims 1 to 8, characterized in that: It includes the following processes: S1: The solar rays are reflected by the heliostat field (1) onto a heat absorber (3) disposed on a heat absorption tower (2), thereby converting the solar energy into heat energy; S2: The absorber (3) absorbs solar energy and converts it into heat energy. The third valve (4.7) is opened, and the low-temperature molten salt flowing out of the molten salt cold tank (4.2) enters the absorber (3) through the second pump (4.4); S3: The low-temperature molten salt absorbs heat energy in the heat absorber (3) and becomes high-temperature molten salt. The first valve (4.5) is opened, and a portion of the high-temperature molten salt is stored in the molten salt hot tank (4.1), while the other portion of the high-temperature molten salt flows through the heater (5) and releases heat to become low-temperature molten salt; S4: After passing through the second valve (4.6), part of the low-temperature molten salt is stored in the molten salt cold tank (4.2), and part of it enters the heat absorber (3) again through the second pump (4.4); S5: CO2 absorbs heat from the high-temperature molten salt through the heater (5), then expands through the turbine (6.1) to generate electricity, then flows through the regenerator (6.2) and high-temperature cooler (7) to release heat, and then is cooled through the air cooler (6.3); S6: The waste heat of the CO2 absorbed in the high-temperature cooler (7) drives the lithium bromide solution absorption refrigeration unit (9) to produce cold energy, so that the CO2 in the low-temperature cooler (8) is further cooled; S7: When the ambient temperature is high and CO2 cannot be condensed into a liquid state from the cryocooler (8), CO2 directly enters the compressor (6.6) through the passage 1 (6.4) to increase the pressure after coming out of the cryocooler (8), and then enters the regenerator (6.2) to absorb heat. After absorbing heat, it flows into the heater (5) to form a supercritical CO2 power cycle; S8: When the ambient temperature is low, the temperature of CO2 at the outlet of the air cooler (6.3) is relatively low, so that the lithium bromide solution absorption refrigeration unit (9) can condense CO2 into liquid. At this time, the fourth valve (6.7) is closed, and the liquid CO2 enters the gas-liquid separator (10.1) through the second passage (6.5). If the CO2 contains impurities, the gas-liquid separator (10.1) can be used to remove the impurities and the non-condensable gas impurities can be discharged through the exhaust valve (10.5); S9: The liquid CO2 in the gas-liquid separator (10.1) enters the CO2 storage tank (10.2), and after being pressurized by the No. 3 pump (10.3), the fifth valve (10.4) is opened to enter the regenerator (6.2) and the heater (5), thereby forming a transcritical CO2 power cycle.

10. The method for using a desert tower solar CO2 power generation and impurity removal system according to claim 9, characterized in that: The specific method steps of the lithium bromide solution absorption refrigeration unit (9) in S6 in the system are: S6.1: The dilute lithium bromide solution absorbs the heat of CO2 in the high-temperature cooler (7) to become a concentrated lithium bromide solution, and then enters the solution heat exchanger (9.1) to exchange heat with the dilute lithium bromide solution to reduce the temperature; S6.2: After passing through the first throttle valve (9.2), it enters the absorber (9.3), absorbs the water vapor from the low-temperature cooler (8), forms a dilute lithium bromide solution and releases heat. The dilute lithium bromide solution is pressurized by the No. 4 pump (9.4) and enters the solution heat exchanger (9.1), and finally enters the high-temperature cooler (7), completing the solution circulation loop; S6.3: In the high temperature cooler (7), water vapor evaporated from the dilute lithium bromide solution enters the condenser (9.5) and condenses to form liquid water; S6.4: Liquid water passes through the second throttle valve (9.6) and undergoes pressure reduction and temperature reduction, and finally enters the low-temperature cooler (8) to evaporate and release cold energy, further cooling the CO2, thus forming a complete water vapor circulation loop.

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