CN107100807B - Direct contact heat exchange tower solar thermal power plant system and its working method - Google Patents

Abstract

The invention discloses a direct contact heat exchange tower type solar thermal power station system and a working method thereof, belonging to the field of solar thermal utilization. The system includes heliostat field, heat absorber, molten salt heat storage and heat release subsystem, turbine, generator, preheater, cooler, and compressor. The solar light is reflected into the heat absorber by the heliostat field. After the gas is compressed, high-temperature and high-pressure gas is generated through the heat absorber to drive the turbine to generate power. According to the intensity of solar energy, combined with the molten salt heat storage and heat release subsystem Adjust working methods. The invention utilizes the characteristics of low vapor pressure of molten salt and wide operating temperature range, adopts the direct contact heat exchange mode between gas and molten salt, replaces the traditional partition heat exchange, can improve the heat exchange efficiency, reduce the heat exchange temperature difference, and at the same time, the gas is the working The medium avoids the large-scale flow of molten salt in the pipeline, corrosion and freezing blockage; at the same time, it can realize continuous and stable operation under different solar intensities, and provide stable high-quality electric energy.

Description

Direct contact heat exchange tower solar thermal power plant system and its working method

technical field

The invention designs a direct contact heat exchange tower type solar thermal power station system and its working method, belonging to the field of solar thermal utilization.

Background technique

In today's energy crisis and increasingly serious environmental problems, the development and utilization of pollution-free renewable energy is imminent. Solar energy is a safe, clean and renewable green energy. The utilization of solar energy mainly includes photothermal conversion and photoelectric conversion. Among them, solar thermal power generation refers to the use of large-scale heliostats to collect solar thermal energy, generate steam through heat exchange devices, and combine traditional power generation processes to generate electricity. Due to the intermittent nature of solar energy, the existing solar thermal power plant system is also equipped with a low-cost large-scale thermal storage system to provide stable and high-quality electrical energy. Molten salt is widely used in heat storage systems due to its wide temperature range, large heat capacity, low vapor pressure, service life and price, which are superior to other heat storage media such as heat transfer oil.

Direct contact heat exchange means that the two media participating in the heat exchange exchange heat in a direct contact manner, which can be the same medium or different, but the two media must be easily separated. Compared with the traditional heat exchange method, direct contact heat exchange has high heat exchange efficiency, small heat transfer temperature difference, and is not easy to corrode and scale. Therefore, it is widely used in seawater desalination, geothermal power generation, medium and low temperature heat source recovery, and wastewater treatment.

In the existing solar thermal power stations, molten salt is mostly used as heat collection and storage medium, combined with steam power cycle to generate electricity, and the heat exchange device adopts a partitioned heat exchanger, but the heat transfer resistance is large and the heat transfer efficiency is not high, and Corrosion and freezing will occur when molten salt flows in the pipeline in a large area. How to solve the low heat transfer efficiency and avoid the safety hazards in the use of molten salt is an urgent problem to be solved in solar thermal power generation technology.

Contents of the invention

The invention utilizes the characteristics of low vapor pressure of molten salt and wide operating temperature range, adopts the direct contact heat exchange mode between gas and molten salt, replaces the traditional partition heat exchange, can improve the heat exchange efficiency, reduce the heat exchange temperature difference, and at the same time, the gas is the working The medium avoids the phenomenon of molten salt flowing in the pipeline in a large range, corrosion and freezing. The gas can be air, nitrogen and carbon dioxide, etc., which are easy to obtain and non-corrosive.

A direct contact heat exchange tower type solar thermal power station system, characterized in that the system includes a heliostat field, a heat absorber, a molten salt heat storage and heat release subsystem, a turbine, a generator, a preheater, a cooling Heat storage and release subsystem of molten salt includes high temperature direct contact heat exchanger, heat storage high temperature salt pump, heat release high temperature salt pump, heat storage low temperature salt pump I, heat release low temperature salt pump, high temperature salt tank , low temperature salt tank, medium temperature salt tank, heat storage medium temperature salt pump, heat storage low temperature salt pump II and medium temperature direct contact heat exchanger;

The preheater includes cold side inlet, cold side outlet, hot side inlet and hot side outlet, high temperature direct contact heat exchanger includes lower gas inlet, lower molten salt opening, upper gas outlet and upper molten salt opening, medium temperature direct contact heat exchange The cooler includes a lower gas inlet, a lower molten salt inlet, an upper gas outlet and an upper molten salt outlet, and the cooler includes a cold side inlet, a cold side outlet, a hot side inlet and a hot side outlet;

The heliostat field is arranged on the ground around the heat absorber;

The outlet of the compressor is connected with the inlet of the cold side of the preheater, and the outlet of the cold side of the preheater is divided into two routes, one of which is connected with the lower gas inlet of the high-temperature direct contact heat exchanger, and the upper gas outlet of the high-temperature direct contact heat exchanger is divided into two routes, one of which is connected with the gas inlet of the upper part of the high-temperature direct contact heat exchanger The inlet of the turbine is connected, the other is connected with the inlet of the heat absorber, the outlet of the heat absorber is divided into two, one is connected with the inlet of the turbine, and the other is connected with the gas inlet of the lower part of the high-temperature direct contact heat exchanger, and the turbine is coaxial with the generator At the same time, the outlet of the turbine is divided into two paths, one is connected to the gas inlet of the lower part of the medium temperature direct contact heat exchanger, the other is connected to the hot side inlet of the preheater, and the gas outlet of the upper part of the medium temperature direct contact heat exchanger is connected to the hot side inlet of the cooler , the outlet on the hot side of the preheater is connected to the inlet on the hot side of the cooler, and the outlet on the hot side of the cooler is connected to the inlet of the compressor;

The high-temperature salt tank and the medium-temperature salt tank are respectively connected to the upper molten salt opening of the high-temperature direct contact heat exchanger through a parallel thermal storage high-temperature salt pump and an exothermic high-temperature salt pump, and the lower molten salt opening of the high-temperature direct contact heat exchanger is connected through a parallel heat storage The low-temperature salt pump I and the exothermic low-temperature salt pump are connected with the low-temperature salt tank, and the low-temperature salt tank is also connected with the molten salt inlet at the lower part of the medium temperature direct contact heat exchanger through the heat storage low temperature salt pump II, and the medium temperature direct contact with the molten salt outlet at the upper part of the heat exchanger It is connected to the medium temperature salt tank through the heat storage medium temperature salt pump;

The high-temperature salt tank is connected to the first end of the high-temperature molten salt three-way valve, the second end of the high-temperature molten salt three-way valve passes through the heat storage high-temperature salt pump, and the third end of the high-temperature molten salt three-way valve passes through the exothermic high-temperature salt pump, and the heat storage high-temperature The salt pump is connected in parallel with the exothermic high-temperature salt pump and then connected to the upper molten salt opening of the high-temperature direct contact heat exchanger. The low-temperature salt tank opening is connected to the first end of the low-temperature molten salt three-way valve, and the second end of the low-temperature molten salt three-way valve Heat low-temperature salt pump Ⅰ, low-temperature molten salt three-way valve The third end passes through the exothermic low-temperature salt pump, and the heat-storage low-temperature salt pump I (6) is connected in parallel with the exothermic low-temperature salt pump and directly contacts the molten salt opening at the lower part of the heat exchanger connected;

The main loop gas regulating valve Ⅰ is set between the cold side outlet of the above preheater and the heat absorber inlet, and the main loop gas regulating valve Ⅱ is set between the heat absorber outlet and the turbine. The high temperature directly contacts the gas inlet at the lower part of the heat exchanger. There are two paths, one is provided with a heat storage gas inlet valve between one path and the outlet of the cold side of the preheater, and the other path is equipped with an exothermic gas inlet valve between the outlet of the heat absorber, and the high temperature directly contacts the upper part of the heat exchanger. There is an exothermic gas outlet valve between one road and the inlet of the heat absorber, a heat storage gas outlet valve between the other road and the turbine inlet, and a gas inlet between the turbine outlet and the gas inlet directly contacting the lower part of the medium temperature heat exchanger. There is a regenerating gas regulating valve, a high-temperature molten salt regulating valve is set between the opening of the high-temperature salt tank and the high-temperature molten salt three-way valve, and a medium-temperature molten salt regulating valve is also set between the high-temperature molten salt three-way valve and the medium-temperature salt tank.

The working method of the direct contact heat exchange tower type solar thermal power station system is characterized in that it includes the following process:

When the solar energy is sufficient, open the main circuit gas regulating valve I, exothermic gas inlet valve, main circuit gas regulating valve II, exothermic gas outlet valve, high temperature molten salt regulating valve, reheating gas regulating valve, and close the regenerative gas inlet valve , regenerative gas outlet valve and medium-temperature molten salt regulating valve, through the low-temperature molten salt three-way valve to connect the low-temperature salt tank, heat-storage low-temperature salt pump I and the high-temperature direct contact molten salt opening passage at the lower part of the heat exchanger, through the high-temperature molten salt three-way valve The through valve and the high temperature molten salt regulating valve are connected to the high temperature and directly contact the upper molten salt opening of the heat exchanger, the heat storage high temperature salt pump and the high temperature salt tank passage, and the air at the compressor outlet is preheated by the preheater and enters the heat absorber Heat, the high-temperature and high-pressure gas at the outlet is divided into two paths, one path directly contacts the low-temperature molten salt through the high-temperature direct contact heat exchanger, and transfers heat to the low-temperature molten salt, and the exothermic gas returns to the heat absorber to absorb heat, and after heating The high-temperature molten salt enters the high-temperature salt tank through the heat-storage high-temperature salt pump, and the other way enters the turbine to generate power. The gas after heat release and work is divided into two ways. The low-temperature molten salt pumped by the salt pump II directly contacts the heat storage, and the exothermic gas enters the cooler for cooling, and the other way enters the hot side inlet of the preheater to preheat the gas at the compressor outlet, and then enters the cooler for cooling. The gas enters the compressor to be recompressed, and the medium-temperature molten salt after heat storage enters the medium-temperature salt tank through the heat-storage medium-temperature salt pump;

When the solar energy is weak, but the high-temperature and high-pressure gas at the outlet of the heat absorber can still drive the turbine to generate power, open the main circuit gas regulating valve I, the main circuit gas regulating valve II and the regenerating gas regulating valve, and close the exothermic gas inlet valve , exothermic gas outlet valve, heat storage gas inlet valve, heat storage gas outlet valve, high temperature molten salt regulating valve and low temperature molten salt regulating valve, close the high temperature molten salt three-way valve and low temperature molten salt three-way valve, the outlet of the compressor After the air is preheated by the preheater, it enters the heat absorber to absorb heat, and the high-temperature and high-pressure gas at the outlet enters the turbine to do power generation. The low-temperature molten salt pumped through the heat storage low-temperature salt pump II directly contacts the heat storage, and the gas after heat release enters the cooler for cooling, and the other way enters the hot side inlet of the preheater to preheat the gas at the outlet of the compressor, and then enters the cooler for cooling , the cooled gas enters the compressor for recompression, and the heat-storage medium-temperature molten salt enters the medium-temperature salt tank through the heat-storage medium-temperature salt pump;

When the solar energy is poor and the high-temperature and high-pressure gas at the outlet of the heat absorber is not enough to drive the turbine to generate power, open the main circuit gas regulating valve I, the main circuit gas regulating valve II, the regenerative gas inlet valve, the regenerative gas outlet valve and the medium-temperature Molten salt regulating valve, close the exothermic gas inlet valve, exothermic gas outlet valve, high-temperature molten salt regulating valve and reheating gas regulating valve, connect the medium-temperature salt tank through the high-temperature molten salt three-way valve and the medium-temperature molten salt regulating valve, and discharge The hot high temperature salt pump and the high temperature directly contact the upper molten salt opening passage of the heat exchanger, and connect the high temperature directly contacting the lower molten salt opening of the heat exchanger, the exothermic low temperature salt pump and the low temperature salt tank passage through the low temperature molten salt three-way valve, and the compressor The outlet air is preheated by the preheater and divided into two paths, one path enters the heat absorber to absorb heat, and the other path directly contacts the heat exchanger with a high temperature to absorb heat directly with the medium temperature molten salt, and the gas after absorbing heat enters the turbine to generate power , after exothermic work, it enters the hot side inlet of the preheater to preheat the gas at the outlet of the compressor, and then enters the cooler to cool, and the cooled gas enters the compressor for recompression, and the exothermic low temperature molten salt enters the low temperature through the exothermic low temperature salt pump. salt shaker;

When there is no solar energy, close the main circuit gas regulating valve I, main circuit gas regulating valve II, exothermic gas inlet valve, exothermic gas outlet valve, high temperature molten salt regulating valve, medium temperature molten salt regulating valve and reheating gas regulating valve, Open the regenerative gas inlet valve and the regenerative gas outlet valve, and connect the high-temperature salt tank, the exothermic high-temperature salt pump and the high-temperature direct-contact molten salt opening passage on the upper part of the heat exchanger through the high-temperature molten salt three-way valve and the high-temperature molten salt regulating valve. Through the low-temperature molten salt three-way valve, the high-temperature direct contact heat exchanger lower molten salt opening, the exothermic low-temperature salt pump and the low-temperature salt tank are connected, and the air at the outlet of the compressor is preheated by the preheater and then directly contacts the heat exchanger through high temperature. Direct contact with hot molten salt to absorb heat, the gas after heat absorption enters the turbine to do power generation, after heat release and work, it enters the hot side inlet of the preheater to preheat the gas at the outlet of the compressor, and then enters the cooler to cool, and the cooled gas enters the compressor The machine is recompressed, and the exothermic low-temperature molten salt enters the low-temperature salt tank through the exothermic low-temperature molten salt.

The present invention sets four working modes for different situations of solar energy. When the solar energy is sufficient, the excess heat is stored with molten salt while the solar energy is used to generate electricity, and the waste heat of the turbine outlet gas is recovered; when the solar energy is slightly weak When the solar energy is used to generate electricity, and the waste heat of the turbine outlet gas is recovered; when the solar energy is poor, the solar energy and the medium-temperature molten salt are used to simultaneously drive the turbine to generate power; when there is no solar energy, the heat stored in the molten salt is released to generate electricity . This system can realize continuous and stable operation under different solar intensities, reduce the impact on the power grid, and provide stable high-quality electric energy. At the same time, it adopts a two-stage heat storage subsystem to improve the effective utilization rate of heat.

Description of drawings

Fig. 1 System diagram of a tower solar thermal power station in which gas and molten salt are in direct contact with each other for heat exchange;

The schematic diagram of direct contact heat exchanger described in Fig. 2;

When the solar energy is sufficient as described in Fig. 3, the system working process diagram;

When the solar energy is slightly weaker as described in Fig. 4, the system working process diagram;

When the solar energy is poor as described in Fig. 5, the system working process diagram;

When there is no solar energy, the system working process diagram is described in Fig. 6;

Label names in the figure: 1-heliostat field; 2-heat absorber; 3-high-temperature direct contact heat exchanger; 4-heat storage high-temperature salt pump; 5-exothermic high-temperature salt pump; 6-heat storage low-temperature salt pump Ⅰ; 7-exothermic low temperature salt pump; 8-high temperature salt tank; 9-low temperature salt tank; 10-medium temperature salt tank; 11-heat storage medium temperature salt pump; Heat exchanger; 14-turbine; 15-generator; 16-preheater; 17-cooler; 18-compressor; 191-main circuit gas regulating valve Ⅰ; 192-exothermic gas inlet valve; 193-main Circuit gas regulating valve II; 194-exothermic gas outlet valve; 195-regenerative gas outlet valve; 196-regenerative gas inlet valve; 197-high temperature molten salt regulating valve; 198-medium temperature molten salt regulating valve; 199-reheat Gas regulating valve; 201-high temperature molten salt three-way valve; 202-low temperature molten salt three-way valve; 2-1-gas outlet; 2-2-mist trap; 2-3-liquid inlet; 2-4-filler; 2-5-support grid; 2-6-gas inlet; 2-7-liquid outlet.

Specific implementation method

Fig. 1 is a system diagram of the direct contact heat exchange tower type solar thermal power station proposed by the present invention, and the working process of the system will be described below with reference to Fig. 1 .

When the solar energy is sufficient, open the main circuit gas regulating valve I191, the exothermic gas inlet valve 192, the main circuit gas regulating valve II193, the exothermic gas outlet valve 194, the high temperature molten salt regulating valve 197, the reheating gas regulating valve 199, and close the accumulator The hot gas inlet valve 196, the heat storage gas outlet valve 195 and the medium temperature molten salt regulating valve 198 are connected to the low temperature salt tank 9, the heat storage low temperature salt pump I6 and the lower part of the high temperature direct contact heat exchanger 3 through the low temperature molten salt three-way valve 202 The molten salt opening passage is connected to the high-temperature direct contact heat exchanger 3 upper molten salt opening, heat storage high-temperature salt pump 4 and high-temperature salt tank 8 passages through the high-temperature molten salt three-way valve 201 and the high-temperature molten salt regulating valve 197, and the compressor 18 After being preheated by the preheater 16, the air at the outlet enters the heat absorber 2 to absorb heat. The high temperature and high pressure gas at the outlet is divided into two paths, one path passes through the high temperature direct contact heat exchanger 3 and directly contacts the low temperature molten salt, and transfers the heat to the low temperature Molten salt, the exothermic gas returns to the heat absorber 2 to absorb heat, and the heated high-temperature molten salt enters the high-temperature salt tank 8 through the heat-storage high-temperature salt pump 4, and enters the turbine 14 to generate power through the other way. The gas is divided into two paths, one path enters the medium temperature and directly contacts the heat exchanger 13, and directly contacts the low-temperature molten salt pumped by the low-temperature salt 9 through the heat-storage low-temperature salt pump II 12 for heat storage, and the exothermic gas enters the cooler 17 for cooling, and the other All the way into the hot side inlet of the preheater 16 to preheat the gas at the outlet of the compressor 18, and then enter the cooler 17 to cool, and the cooled gas enters the compressor 18 for recompression, and the heat-stored medium-temperature molten salt passes through the heat-stored medium-temperature salt pump 11 Enter the middle temperature salt tank 10;

When the solar energy is slightly weak, but the high-temperature and high-pressure gas at the outlet of the heat absorber 2 can still drive the turbine 14 to generate power, open the main circuit gas regulating valve I191, the main circuit gas regulating valve II193 and the reheating gas regulating valve 199, and close the heat release Gas inlet valve 192, exothermic gas outlet valve 194, heat storage gas inlet valve 196, heat storage gas outlet valve 195, high temperature molten salt regulating valve 197 and medium temperature molten salt regulating valve 198, close the high temperature molten salt three-way valve 201 and the low temperature The molten salt three-way valve 202, the air at the outlet of the compressor 18 is preheated by the preheater 16, and then enters the heat absorber 2 to absorb heat, and the high-temperature and high-pressure gas at the outlet enters the turbine 14 to generate power, and the gas after heat release and work is divided into two One way enters the medium temperature directly contacting the heat exchanger 13, and directly contacts the heat storage with the low-temperature molten salt pumped by the low-temperature salt tank 9 through the heat storage low-temperature salt pump II12. The hot side inlet of the heater 16 preheats the gas at the outlet of the compressor 18, and then enters the cooler 17 for cooling, and the cooled gas enters the compressor 18 for recompression, and the heat-storage medium-temperature molten salt enters the medium-temperature salt through the heat-storage medium-temperature salt pump 11 tank 10;

When the solar energy is poor and the high-temperature and high-pressure gas at the outlet of the heat absorber 2 is not enough to drive the turbine 14 to generate power, open the main circuit gas regulating valve I191, the main circuit gas regulating valve II193, the regenerative gas inlet valve 196, and the regenerative gas outlet valve 195 and medium temperature molten salt regulating valve 198, close the exothermic gas inlet valve 192, exothermic gas outlet valve 194, high temperature molten salt regulating valve 197 and reheating gas regulating valve 199, through the high temperature molten salt three-way valve 201 and the medium temperature melting The salt regulating valve 198 is connected to the medium-temperature salt tank 10, the exothermic high-temperature salt pump 5, and the upper part of the high-temperature direct contact heat exchanger 3. The salt opening, the exothermic low-temperature salt pump 7 and the low-temperature salt tank 9 passages, the air at the outlet of the compressor 18 is preheated by the preheater 16 and then divided into two paths, one path enters the heat absorber 2 to absorb heat, and the other path passes through high-temperature direct contact exchange. Heater 3 is in direct contact with the medium-temperature molten salt to absorb heat, and the gas after absorbing heat enters turbine 14 to perform power generation. After releasing heat and performing work, it enters the hot side inlet of preheater 16 to preheat the gas at the outlet of compressor 18, and then enters cooler 17 for cooling. , the cooled gas enters the compressor 18 for recompression, and the exothermic low-temperature molten salt enters the low-temperature salt tank 9 through the exothermic low-temperature salt pump 7;

When there is no solar energy, close the main circuit gas regulating valve I191, main circuit gas regulating valve II193, exothermic gas inlet valve 192, exothermic gas outlet valve 194, high temperature molten salt regulating valve 197, medium temperature molten salt regulating valve 198 and heat recovery Gas regulating valve 199, open heat storage gas inlet valve 196 and heat storage gas outlet valve 195, connect high temperature salt tank 8, exothermic high temperature salt pump 5 and high temperature through high temperature molten salt three-way valve 201 and high temperature molten salt regulating valve 197 Direct contact heat exchanger 3 upper molten salt opening passage, through low-temperature molten salt three-way valve 202 to connect high temperature direct contact heat exchanger 3 lower molten salt opening, exothermic low-temperature salt pump 7 and low-temperature salt tank 9 passages, compressor 18 The air at the outlet is preheated by the preheater 16 and then directly contacts the heat exchanger 3 to absorb heat through the high temperature direct contact with the hot molten salt. The inlet preheats the gas at the outlet of the compressor 18, and then enters the cooler 17 for cooling. The cooled gas enters the compressor 18 for recompression, and the exothermic low-temperature molten salt enters the low-temperature salt tank 9 through the exothermic low-temperature molten salt 7 .

Claims (2)

1. A direct contact heat exchange tower type solar thermal power station system, characterized in that the system includes a heliostat field (1), a heat absorber (2), a molten salt heat storage and release subsystem, a turbine ( 14), generator (15), preheater (16), cooler (17) and compressor (18), wherein the molten salt heat storage and release subsystem includes high temperature direct contact heat exchanger (3), heat storage High temperature salt pump (4), exothermic high temperature salt pump (5), heat storage low temperature salt pump I (6), exothermic low temperature salt pump (7), high temperature salt tank (8), low temperature salt tank (9), medium temperature Salt tank (10), heat storage medium temperature salt pump (11), heat storage low temperature salt pump II (12) and medium temperature direct contact heat exchanger (13); The preheater (16) includes a cold side inlet, cold side outlet, hot side inlet and hot side outlet, and the high temperature direct contact heat exchanger (3) includes a lower gas inlet, a lower molten salt opening, an upper gas outlet and an upper molten salt opening , the medium temperature direct contact heat exchanger (13) includes a lower gas inlet, a lower molten salt inlet, an upper gas outlet and an upper molten salt outlet, and the cooler (17) includes a cold side inlet, a cold side outlet, a hot side inlet and a hot side outlet ; The heliostat field (1) is arranged on the ground around the heat absorber (2); The outlet of the compressor (18) is connected to the inlet of the cold side of the preheater (16). The gas outlet on the upper part of the heat exchanger (3) is divided into two paths, one path is connected to the inlet of the turbine (14), the other path is connected to the inlet of the heat absorber (2), and the outlet of the heat absorber (2) is divided into two paths, one path is connected to the inlet of the turbine (14). (14) is connected to the inlet, the other is connected to the gas inlet of the lower part of the high-temperature direct contact heat exchanger (3), the turbine (14) is coaxially connected to the generator (15), and the outlet of the turbine (14) is divided into two channels, one It is connected to the lower gas inlet of the medium temperature direct contact heat exchanger (13), the other is connected to the hot side inlet of the preheater (16), and the upper gas outlet of the medium temperature direct contact heat exchanger (13) is connected to the hot side inlet of the cooler (17). connected, the outlet on the hot side of the preheater (16) is connected to the inlet on the hot side of the cooler (17), and the outlet on the hot side of the cooler (17) is connected to the inlet of the compressor (18); The high-temperature salt tank (8) and the low-temperature salt tank (10) are respectively connected to the upper molten salt opening of the high-temperature direct contact heat exchanger (3) through parallel heat storage high-temperature salt pumps (4) and exothermic high-temperature salt pumps (5). The molten salt opening at the lower part of the high-temperature direct contact heat exchanger (3) is connected to the low-temperature salt tank (9) through the parallel heat storage low-temperature salt pump I (6) and the exothermic low-temperature salt pump (7), and the low-temperature salt tank (9) also The heat storage low temperature salt pump II (12) is connected to the lower molten salt inlet of the medium temperature direct contact heat exchanger (13), and the upper molten salt outlet of the medium temperature direct contact heat exchanger (13) is connected to the medium temperature through the heat storage medium temperature salt pump (11) The salt tank (10) is connected; The high-temperature salt tank (8) is connected to the first end of the high-temperature molten salt three-way valve (201), the second end of the high-temperature molten salt three-way valve (201) passes through the heat storage high-temperature salt pump (4), and the high-temperature molten salt three-way valve ( 201) The third end passes through the exothermic high-temperature salt pump (5), the heat-storage high-temperature salt pump (4) is connected in parallel with the exothermic high-temperature salt pump (5), and then connected to the upper molten salt opening of the high-temperature direct contact heat exchanger (3), The opening of the low-temperature salt tank (9) is connected to the first end of the low-temperature molten salt three-way valve (202), the second end of the low-temperature molten salt three-way valve (202) passes through the heat storage low-temperature salt pump I (6), and the low-temperature molten salt three-way valve The third end of the valve (202) passes through the exothermic low-temperature salt pump (7), and the heat-storage low-temperature salt pump I (6) is connected in parallel with the exothermic low-temperature salt pump (7) and then directly contacts the molten salt at the lower part of the high-temperature heat exchanger (3) opening connected; A main loop gas regulating valve I (191) is provided between the cold side outlet of the above-mentioned preheater (16) and the inlet of the heat absorber (2), and a main circuit valve I (191) is provided between the outlet of the heat absorber (2) and the turbine (14). Loop gas regulating valve II (193), there are two gas inlets at the lower part of the high-temperature direct contact heat exchanger (3), and there is a heat storage gas inlet valve (196) between one path and the cold side outlet of the preheater (16). An exothermic gas inlet valve (192) is provided between one channel and the outlet of the heat absorber (2). There is an exothermic gas outlet valve (194), and a regenerative gas outlet valve (195) is provided between the other channel and the inlet of the turbine (14). The outlet of the turbine (14) directly contacts the gas at the lower part of the heat exchanger (13) at medium temperature. A reheating gas regulating valve (199) is provided between the inlets, a high-temperature molten salt regulating valve (197) is provided between the opening of the high-temperature salt tank (8) and the high-temperature molten salt three-way valve (201), and the high-temperature molten salt three-way valve (201) is also provided with a medium temperature molten salt regulating valve (198) between the medium temperature salt tank (10). 2. The working method of the direct contact heat exchange tower type solar thermal power station system according to claim 1, characterized in that, comprising the following process: When the solar energy is sufficient, open the main circuit gas regulating valve I (191), the exothermic gas inlet valve (192), the main circuit gas regulating valve II (193), the exothermic gas outlet valve (194), the high temperature molten salt regulating valve ( 197), regenerative gas regulating valve (199), close the regenerative gas inlet valve (196), regenerative gas outlet valve (195) and medium temperature molten salt regulating valve (198), and pass through the low temperature molten salt three-way valve (202) Connect the low-temperature salt tank (9), the thermal storage low-temperature salt pump I (6) and the high-temperature direct-contact heat exchanger (3) lower part of the molten salt opening passage, through the high-temperature molten salt three-way valve (201) and the high-temperature molten salt regulating valve (197) Connect the high-temperature direct contact heat exchanger (3) upper molten salt opening, heat storage high-temperature salt pump (4) and high-temperature salt tank (8) pathway, and the air at the outlet of the compressor (18) passes through the preheater (16 ) After preheating, it enters the heat absorber (2) to absorb heat, and the high-temperature and high-pressure gas at the outlet is divided into two paths, one path passes through the high-temperature direct contact heat exchanger (3) and directly contacts the low-temperature molten salt, and transfers heat to the low-temperature molten salt. The exothermic gas returns to the heat absorber (2) to absorb heat, and the heated high-temperature molten salt enters the high-temperature salt tank (8) through the heat storage high-temperature salt pump (4), and the other way enters the turbine (14) to generate power , the gas after exothermic work is divided into two paths, one path enters the medium-temperature direct contact heat exchanger (13), and directly contacts the low-temperature molten salt pumped by the low-temperature salt tank (9) through the heat-storage low-temperature salt pump II (12) for heat storage , the exothermic gas enters the cooler (17) for cooling, and the other way enters the hot side inlet of the preheater (16) to preheat the gas at the outlet of the compressor (18), and then enters the cooler (17) for cooling, and the cooled gas Enter the compressor (18) for recompression, and the medium-temperature molten salt after heat storage enters the medium-temperature salt tank (10) through the heat-storage medium-temperature salt pump (11); When the solar energy is weak, but the high-temperature and high-pressure gas at the outlet of the heat absorber (2) can still drive the turbine (14) to generate power, open the main circuit gas regulating valve I (191), the main circuit gas regulating valve II (193) and Reheating gas regulating valve (199), closing exothermic gas inlet valve (192), exothermic gas outlet valve (194), regenerative gas inlet valve (196), regenerative gas outlet valve (195), high temperature molten salt regulation valve (197) and medium-temperature molten salt regulating valve (198), close the high-temperature molten salt three-way valve (201) and low-temperature molten salt three-way valve (202), and the air at the outlet of the compressor (18) passes through the preheater (16) After preheating, it enters the heat absorber (2) to absorb heat, and the high-temperature and high-pressure gas at the outlet enters the turbine (14) to generate power. It is in direct contact with the low-temperature molten salt pumped by the low-temperature salt tank (9) through the heat-storage low-temperature salt pump II (12) for heat storage, and the exothermic gas enters the cooler (17) for cooling, and the other path enters the preheater (16) The hot-side inlet preheats the gas at the outlet of the compressor (18), and then enters the cooler (17) for cooling, and the cooled gas enters the compressor (18) for recompression, and the heat-stored medium-temperature molten salt passes through the heat-stored medium-temperature salt pump ( 11) enter the medium temperature salt tank (10); When the solar energy is poor and the high-temperature and high-pressure gas at the outlet of the heat absorber (2) is not enough to drive the turbine (14) to generate power, open the main circuit gas regulating valve I (191), main circuit gas regulating valve II (193), storage Hot gas inlet valve (196), heat storage gas outlet valve (195) and medium temperature molten salt regulating valve (198), close exothermic gas inlet valve (192), exothermic gas outlet valve (194), high temperature molten salt regulating valve (197) and the reheating gas regulating valve (199), through the high-temperature molten salt three-way valve (201) and the medium-temperature molten salt regulating valve (198), connect the medium-temperature salt tank (10), the exothermic high-temperature salt pump (5) and The high temperature direct contact heat exchanger (3) upper molten salt opening passage is connected to the high temperature direct contact heat exchanger (3) lower molten salt opening, exothermic low temperature salt pump (7) and the low temperature molten salt three-way valve (202). The path of the low-temperature salt tank (9), the air at the outlet of the compressor (18) is preheated by the preheater (16), and then divided into two paths, one path enters the heat absorber (2) to absorb heat, and the other path directly contacts the heat exchanger through high temperature (3) Direct contact with the medium-temperature molten salt to absorb heat, and the gas after absorbing heat enters the turbine (14) to do power generation, and after the heat is released to do work, it enters the preheater (16) hot side inlet to preheat the gas at the outlet of the compressor (18), After entering the cooler (17) for cooling, the cooled gas enters the compressor (18) for recompression, and the exothermic low-temperature molten salt enters the low-temperature salt tank (9) through the exothermic low-temperature salt pump (7); When there is no solar energy, close the main circuit gas regulating valve I (191), the main circuit gas regulating valve II (193), the exothermic gas inlet valve (192), the exothermic gas outlet valve (194), the high temperature molten salt regulating valve ( 197), medium temperature molten salt regulating valve (198) and reheating gas regulating valve (199), open the regenerative gas inlet valve (196) and regenerative gas outlet valve (195), and pass through the high temperature molten salt three-way valve (201) and the high-temperature molten salt regulating valve (197) are connected to the high-temperature salt tank (8), exothermic high-temperature salt pump (5) and the high-temperature direct-contact heat exchanger (3) upper molten salt opening passage, through the low-temperature molten salt three-way valve ( 202) Connect the high-temperature direct contact heat exchanger (3) lower molten salt opening, exothermic low-temperature salt pump (7) and low-temperature salt tank (9) passages, and the air at the outlet of the compressor (18) passes through the preheater (16) After preheating, the high-temperature direct contact heat exchanger (3) directly contacts the hot molten salt to absorb heat, and the gas after absorbing heat enters the turbine (14) to do power generation, and after heat release and work, enters the preheater (16) hot side inlet preheating The gas at the outlet of the hot compressor (18) enters the cooler (17) for cooling, and the cooled gas enters the compressor (18) for recompression, and the exothermic low-temperature molten salt enters the low-temperature Salt Shaker (9).

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