A thermal battery energy storage system coupled with a coal-fired generator set and an operation method thereof

Abstract

A thermal battery energy storage system coupled with a coal-fired generator set and its operation method, including a coal-fired generator set system and a heat pump energy storage system coupled with molten salt heat storage; the coal-fired generator set system includes a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, a high-pressure heater, and a boiler; the invention uses the exhaust steam of the low-pressure cylinder as a heat source to preheat the circulating working fluid in the thermal battery heat pump system, so that the total efficiency and COP of the system are increased, and the exhaust steam recovery and utilization capacity is enhanced. At the same time, the output load of the coal-fired unit is reduced, the peak-shaving range of the unit is expanded, and the peak-shaving depth is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of coal-fired power generation and energy storage, and in particular to a thermal battery energy storage system coupled with a coal-fired power generation unit and an operation method thereof. Background Art

[0002] With the continuous growth of energy demand and the proposal of the dual-carbon strategy, the proportion of new energy in my country's energy system is gradually increasing. The use of renewable energy such as wind energy and solar energy has become an important direction for future energy development and will gradually become the main body of power supply in the future. However, renewable energy generation is generally intermittent and highly volatile. Its large-scale grid connection will seriously affect the safety, stability and power supply quality of the power grid, and will lead to more serious problems of wind and solar power abandonment.

[0003] In addition, when wind and solar power generation fluctuates greatly, the grid's reliance on peak-shaving capabilities increases significantly, requiring coal-fired power generating units to shift from the main power source to the supporting and regulating power source, and to undertake more peak-shaving and frequency-regulating services. Among them, how to further reduce the load of coal-fired units while ensuring safety, expand the peak-shaving range of units, and achieve efficient and flexible coordination are key core issues that need to be urgently addressed in the development of my country's power industry.

[0004] Thermal batteries include three parts: electricity-to-heat, heat storage, and heat-to-electricity. The electricity-to-heat part stores heat in a heat storage medium through electric heating or a reverse Brayton cycle. In the heat-to-electricity part, the heat storage medium acts as a heat source to heat water step by step into superheated steam, which then enters the steam turbine system to generate power. Coupling a thermal battery energy storage system with a traditional thermal power unit can greatly improve the peak-shaving capacity of the power station, thereby effectively responding to rapid fluctuations in the grid load and improving the flexibility and stability of the power system; at the same time, the system can utilize the electricity generated by abandoned wind and solar power to increase the access rate of renewable energy to the grid, thereby being vigorously developed.

[0005] In the evaluation of thermal battery systems, the COP of the electric-to-heat part is an important evaluation indicator. Traditional thermal battery electric-to-heat systems usually use 15°C methanol as the heat source of the cold source heat exchanger. Although it can preheat the circulating working fluid, there is still a large temperature difference between the preheated circulating working fluid and the regenerative heater, which will increase the heat exchange loss of the regenerative heat exchanger. At the same time, the circulating working fluid temperature at the outlet of the regenerative heat exchanger will also affect the power generation of the auxiliary steam turbine. Therefore, the COP range of the electric-to-heat part is mostly between 1.2 and 1.3. Coupling the thermal battery energy storage system with the traditional thermal power unit is expected to further improve the COP of the thermal battery electric-to-heat part while reducing the cold end exhaust loss of the coal-fired power generation unit. However, there is currently a lack of design and operation control methods for the configuration of the thermal battery energy storage system coupled with the coal-fired power generation unit. Summary of the invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a thermal battery energy storage system coupled with a coal-fired power generation unit and an operation method thereof, which uses the exhaust steam of the low-pressure cylinder as a heat source to preheat the circulating working fluid in the thermal battery heat pump system, thereby increasing the overall efficiency and COP of the system and enhancing the exhaust steam recovery and utilization capacity. At the same time, the output load of the coal-fired unit is reduced, the peak regulation range of the unit is expanded, and the peak regulation depth is improved.

[0007] To achieve the above object, the present invention adopts the following technical solutions: A thermal battery energy storage system coupled with a coal-fired generator set, comprising a coal-fired generator set system, a heat pump energy storage system coupled with molten salt heat storage; The coal-fired power generation system includes a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a generator, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feed water pump, a high-pressure heater, and a boiler; the superheated steam outlets of the molten salt superheater and the boiler are connected to the inlet of the high-pressure cylinder; the feed water working medium inlet of the boiler is connected to the feed water outlet of the high-pressure heater; the intermediate steam extraction outlet of the high-pressure cylinder is connected to the steam inlet of the high-pressure heater through a pipeline, and the steam outlet of the high-pressure cylinder is respectively connected to the reheat steam inlet of the boiler, the steam inlet of the high-pressure heater, and the steam inlet of the molten salt auxiliary superheater The fourth valve is connected to the pipeline between the steam outlet of the high-pressure cylinder and the steam inlet of the molten salt auxiliary superheater; the steam outlet of the molten salt auxiliary superheater and the reheat steam outlet of the boiler are connected to the steam inlet of the medium-pressure cylinder; the first-stage extraction steam outlet of the medium-pressure cylinder is connected to the steam inlet of the high-pressure heater, the second-stage extraction steam outlet is connected to the steam inlet of the deaerator, the steam outlet is respectively connected to the steam inlet of the low-pressure cylinder, the low-pressure heater and the driving steam inlet of the absorption heat pump, and the second valve is connected between the steam outlet of the medium-pressure cylinder and the driving steam inlet of the absorption heat pump The drain outlet of the high-pressure heater is connected to the drain inlet of the deaerator; the intermediate steam extraction outlet of the low-pressure cylinder is connected to the steam inlet of the low-pressure heater, the steam outlet is connected to the steam inlet of the condenser and the low-temperature heat source inlet of the absorption heat pump, and the third valve is connected to the pipeline between the steam outlet of the low-pressure cylinder and the low-temperature heat source inlet of the absorption heat pump; the drain outlet of the low-pressure heater is connected to the drain inlet of the condenser; the condensate outlet of the condenser is connected to the condensate inlet of the low-pressure heater through the condensate pump; the condensate outlet of the low-pressure heater is connected to the deaerator The condensate inlet of the deaerator is connected; the feed water outlet of the deaerator is connected to the feed water inlet of the high-pressure heater through a feed water pump; the feed water outlet of the high-pressure heater is respectively connected to the feed water working medium inlet of the boiler and the cold source inlet of the molten salt preheater, and the first valve is connected to the pipeline between the feed water outlet of the high-pressure heater and the cold source inlet of the molten salt preheater; the cold source outlet of the molten salt preheater is connected to the cold source inlet of the molten salt steam generator, and the steam outlet of the molten salt steam generator is connected to the cold source inlet of the molten salt superheater; the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder are connected to the generator through a transmission shaft; The heat pump energy storage system coupled with molten salt heat storage includes an electric motor, a multi-stage compressor, a molten salt-working fluid heat exchanger, a regenerator, a charging expander, an absorption heat pump, a high-temperature molten salt storage tank, a high-temperature molten salt pump, a low-temperature molten salt storage tank, a low-temperature molten salt pump, a molten salt preheater, a molten salt steam generator, a molten salt superheater and a molten salt auxiliary superheater; the working fluid outlet of the multi-stage compressor is connected to the working fluid inlet of the molten salt-working fluid heat exchanger; the working fluid outlet of the molten salt-working fluid heat exchanger is connected to the high-temperature working fluid inlet of the regenerator; the high-temperature working fluid outlet of the regenerator is connected to the working fluid inlet of the charging expander; the working fluid outlet of the charging expander is connected to the high-temperature heat source inlet of the absorption heat pump; the high-temperature heat source outlet of the absorption heat pump is connected to the low-temperature working fluid inlet of the regenerator; the low-temperature working fluid outlet of the regenerator is connected to The working fluid inlet of the multi-stage compressor is connected; the low-temperature heat source outlet of the absorption heat pump is connected to the hot well of the condenser; the molten salt outlet of the low-temperature molten salt storage tank is connected to the molten salt inlet of the molten salt-working fluid heat exchanger through a low-temperature molten salt pump; the molten salt outlet of the molten salt-working fluid heat exchanger is connected to the molten salt inlet of the high-temperature molten salt storage tank; the molten salt outlet of the high-temperature molten salt storage tank is connected to the molten salt inlet of the molten salt superheater and the molten salt auxiliary superheater through a high-temperature molten salt pump, the molten salt outlets of the molten salt superheater and the molten salt auxiliary superheater are connected to the molten salt inlet of the molten salt steam generator, the molten salt outlet of the molten salt steam generator is connected to the molten salt inlet of the molten salt preheater, and the molten salt outlet of the molten salt preheater is connected to the molten salt inlet of the low-temperature molten salt storage tank; the motor, the multi-stage compressor, and the charging expander are connected in sequence through a transmission shaft.

[0008] The exhaust steam from the intermediate pressure cylinder is used as driving steam, and the exhaust steam from the coal-fired generator set is used as the low-temperature heat source of the heat pump energy storage system by using an absorption heat pump.

[0009] The circulating working fluid used in the heat pump energy storage system is carbon dioxide, and the circulation form adopts the Brayton cycle. The maximum operating temperature is 565°C and the minimum operating temperature is 18°C.

[0010] The electric motor, the multi-stage compressor and the charging expander are coaxially connected, and the work done by the charging expander offsets part of the power consumption of the multi-stage compressor.

[0011] The high-temperature molten salt storage tank and the low-temperature molten salt storage tank use binary molten salt (40% KNO3+60% NaNO3) as heat storage medium, and the operating temperature range is 290-565°C.

[0012] The high-temperature molten salt medium flows out from the high-temperature molten salt storage tank and serves as the heat source of the molten salt auxiliary superheater and the molten salt superheater, the molten salt steam generator and the molten salt preheater in turn, heating the feed water of the coal-fired power generation unit to generate superheated steam and reheated steam.

[0013] The input source of the electric motor in the heat pump energy storage system comes from the electricity output by the coal-fired unit, or the abandoned electricity of the new energy station or the off-peak electricity of the power grid.

[0014] An operating method using the system, when in a low electricity consumption period, most of the electric energy output by the coal-fired power generation unit through the generator is used as the input source of the motor in the heat pump energy storage system coupled with molten salt heat storage, and at the same time, a part of the exhaust steam at the outlet of the medium-pressure cylinder and a part of the exhaust steam at the outlet of the low-pressure cylinder are used as the driving steam and low-temperature heat source of the absorption heat pump respectively to heat the working medium, and the heat pump energy storage system coupled with molten salt heat storage converts the excess electric energy and a part of the heat energy of the exhaust steam into the heat energy of molten salt for storage; specifically, the valve on the branch line of the feed water bypass entering the molten salt preheater is closed, and the high temperature Molten salt pump, start the low-temperature molten salt pump, open the valve on the medium-pressure cylinder outlet to the absorption heat pump branch, and open the valve on the low-pressure cylinder outlet to the absorption heat pump branch; the amount of coal entering the boiler of the coal-fired generator set does not change, and the turbine operating conditions only fluctuate slightly, ensuring power generation efficiency; the electric motor in the heat pump energy storage system drives the multi-stage compressor to work, and at the same time, the working fluid at the outlet of the charging expander enters the absorption heat pump to absorb heat, converting the excess electric energy of the coal-fired generator set coupled to the heat pump energy storage system and part of the heat energy of the exhaust steam into the heat energy of molten salt, and finally storing it in the high-temperature molten salt storage tank; When electricity consumption is at its peak, open the valve on the feed water bypass entering the molten salt preheater branch, start the high-temperature molten salt pump, stop the low-temperature molten salt pump, close the valve on the medium-pressure cylinder outlet to the absorption heat pump branch, and close the valve on the low-pressure cylinder outlet to the absorption heat pump branch; at this time, part of the feed water of the coal-fired power generation unit enters the molten salt preheater, molten salt steam generator, and molten salt superheater in turn to absorb heat, and the superheated steam generated enters the high-pressure cylinder to further do work, and part of the exhaust steam of the high-pressure cylinder enters the molten salt auxiliary superheater to absorb heat, and the reheated steam generated enters the medium-pressure cylinder to further do work, increasing the turbine output, thereby significantly increasing the turbine power generation.

[0015] Compared with the prior art, the present invention has the following beneficial effects: the invention provides a thermal battery energy storage system coupled with a coal-fired power generation unit and an operation method thereof, which uses the exhaust steam of the low-pressure cylinder as a heat source to preheat the circulating working fluid in the thermal battery heat pump system, thereby increasing the overall efficiency and COP of the system and enhancing the exhaust steam recovery and utilization capacity. At the same time, the output load of the coal-fired unit is reduced, the peak regulation range of the unit is expanded, and the peak regulation depth is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the present invention. DETAILED DESCRIPTION

[0017] The present invention is not limited by the following embodiments, and specific implementation methods can be determined based on the technical solution of the present invention and actual conditions.

[0018] like Figure 1As shown, a thermal battery energy storage system coupled with a coal-fired power generation unit is characterized in that it includes a coal-fired power generation unit system and a heat pump energy storage system coupled with molten salt heat storage.

[0019] The coal-fired power generation unit system includes a high-pressure cylinder 1, a medium-pressure cylinder 2, a low-pressure cylinder 3, a generator 4, a condenser 5, a condensate pump 19, a low-pressure heater 6, a deaerator 7, a feed water pump 20, a high-pressure heater 8 and a boiler 9.

[0020] The superheated steam outlets of the molten salt superheater 10-3 and the boiler 9 are connected to the inlet of the high-pressure cylinder 1; the feed water inlet of the boiler 9 is connected to the feed water outlet of the high-pressure heater 8; the intermediate steam extraction outlet of the high-pressure cylinder 1 is connected to the steam inlet of the high-pressure heater 8 through a pipeline, and the steam outlet of the high-pressure cylinder 1 is respectively connected to the reheat steam inlet of the boiler 1, the steam inlet of the high-pressure heater 8 and the steam inlet of the molten salt auxiliary superheater 10-4, and the fourth valve 24 is connected to the pipeline between the steam outlet of the high-pressure cylinder 1 and the steam inlet of the molten salt auxiliary superheater 10-4; the molten salt auxiliary superheater 10 -4 steam outlet and the reheat steam outlet of boiler 1 are connected to the steam inlet of medium pressure cylinder 2; the first stage extraction steam outlet of medium pressure cylinder 2 is connected to the steam inlet of high pressure heater 8, the second stage extraction steam outlet is connected to the steam inlet of deaerator 7, the steam outlet is respectively connected to the steam inlet of low pressure cylinder 3, low pressure heater 6 and the driving steam inlet of absorption heat pump 11, the second valve 22 is connected to the pipeline between the steam outlet of medium pressure cylinder 2 and the driving steam inlet of absorption heat pump 11; the drain outlet of high pressure heater 8 is connected to the drain inlet of deaerator 7; the intermediate extraction steam outlet of low pressure cylinder 3 is connected to the steam inlet of low pressure heater 6 ... second valve 22 is connected to the pipeline between the steam outlet of medium pressure cylinder 2 and the driving steam inlet of absorption heat pump 11; the drain outlet of high pressure heater 8 is connected to the drain inlet of deaerator 7; the intermediate extraction steam outlet of low pressure cylinder 3 is connected to the steam inlet of deaerator 7; the steam inlet of low pressure cylinder 3 is connected to the steam inlet of low pressure heater 6 and the driving steam inlet of absorption heat pump 11; the steam inlet of high pressure heater 8 is connected to the steam inlet of deaerator 7; the steam inlet of low pressure cylinder 3 is connected to the steam inlet of deaerator 7; the steam inlet of low pressure cylinder 3 is connected to the steam inlet of deaerator 7; the steam inlet of low pressure cylinder 3 is connected to the steam inlet of deaerator 7; the steam inlet of low pressure cylinder 3 is connected to the steam inlet of deaerator 7; the steam in The steam outlet is connected to the steam inlet of the low-pressure heater 6, the steam outlet is connected to the steam inlet of the condenser 5 and the low-temperature heat source inlet of the absorption heat pump 11, and the third valve 23 is connected to the pipeline between the steam outlet of the low-pressure cylinder 3 and the low-temperature heat source inlet of the absorption heat pump 11; the drain outlet of the low-pressure heater 6 is connected to the drain inlet of the condenser 5; the condensate outlet of the condenser 5 is connected to the condensate inlet of the low-pressure heater 6 through the condensate pump 19; the condensate outlet of the low-pressure heater 6 is connected to the condensate inlet of the deaerator 7; the feed water outlet of the deaerator 7 is connected to the high-pressure The high-pressure heater 8 is connected to the water supply inlet; the water supply outlet of the high-pressure heater 8 is respectively connected to the water supply inlet of the boiler 9 and the cold source inlet of the molten salt preheater 10-1, and the first valve 21 is connected to the pipeline between the water supply outlet of the high-pressure heater 8 and the cold source inlet of the molten salt preheater 10-1; the cold source outlet of the molten salt preheater 10-1 is connected to the cold source inlet of the molten salt steam generator 10-2, and the steam outlet of the molten salt steam generator 10-2 is connected to the cold source inlet of the molten salt superheater 10-3; the high-pressure cylinder 1, the medium-pressure cylinder 2 and the low-pressure cylinder 3 are connected to the generator 4 through a transmission shaft.

[0021] The heat pump energy storage system coupled with molten salt heat storage comprises a motor 16, a multi-stage compressor 14, a molten salt-working fluid heat exchanger 17, a regenerator 18, a charging expander 15, an absorption heat pump 11, a high-temperature molten salt storage tank 12, a high-temperature molten salt pump 25, a low-temperature molten salt storage tank 13, a low-temperature molten salt pump 26, a molten salt preheater 10-1, a molten salt steam generator 10-2, a molten salt superheater 10-3 and a molten salt auxiliary superheater 10-4; the working fluid output of the multi-stage compressor 14 The outlet of the molten salt-working fluid heat exchanger 17 is connected to the working fluid inlet of the regenerator 18; the working fluid outlet of the regenerator 18 is connected to the working fluid inlet of the charging expander 15; the working fluid outlet of the charging expander 15 is connected to the high-temperature heat source inlet of the absorption heat pump 11; the high-temperature heat source outlet of the absorption heat pump 11 is connected to the low-temperature working fluid inlet of the regenerator 18; the low-temperature working fluid outlet of the regenerator 18 is connected to the multi- The working fluid inlet of the first stage compressor 14 is connected; the low-temperature heat source outlet of the absorption heat pump 11 is connected to the hot well of the condenser 5; the molten salt outlet of the low-temperature molten salt storage tank 13 is connected to the molten salt inlet of the molten salt-working fluid heat exchanger 17 through a low-temperature molten salt pump 26; the molten salt outlet of the molten salt-working fluid heat exchanger 17 is connected to the molten salt inlet of the high-temperature molten salt storage tank 12; the molten salt outlet of the high-temperature molten salt storage tank 12 is connected to the molten salt superheater 10-3 and the molten salt auxiliary superheater 1 through a high-temperature molten salt pump 25. The molten salt inlet of 0-4 is connected, the molten salt outlets of the molten salt superheater 10-3 and the molten salt auxiliary superheater 10-4 are connected to the molten salt inlet of the molten salt steam generator 10-2, the molten salt outlet of the molten salt steam generator 10-2 is connected to the molten salt inlet of the molten salt preheater 10-1, and the molten salt outlet of the molten salt preheater 10-1 is connected to the molten salt inlet of the low-temperature molten salt storage tank 13; the motor 16, the multi-stage compressor 14, and the charging expander 15 are connected in sequence through the transmission shaft.

[0022] The exhaust steam of the intermediate pressure cylinder 2 is used as driving steam, and the exhaust steam of the coal-fired power generation unit is used as the low-temperature heat source of the heat pump energy storage system by using the absorption heat pump 11.

[0023] The circulating working fluid used in the heat pump energy storage system is carbon dioxide, and the circulation form adopts the Brayton cycle. The maximum operating temperature is 565°C and the minimum operating temperature is 18°C.

[0024] The electric motor 16 , the multi-stage compressor 14 and the charging expander 15 are coaxially connected, and the work done by the charging expander 15 offsets part of the power consumed by the multi-stage compressor 14 .

[0025] The high-temperature molten salt storage tank 12 and the low-temperature molten salt storage tank 13 use binary molten salt (40% KNO3+60% NaNO3) as heat storage medium, and the operating temperature range is 290-565°C.

[0026] The high-temperature molten salt medium flows out from the high-temperature molten salt storage tank 12 and serves as the heat source for the molten salt auxiliary superheater 10-4 and the molten salt superheater 10-3, the molten salt steam generator 10-2 and the molten salt preheater 10-1 in turn, heating the feed water of the coal-fired power generation unit to generate superheated steam and reheated steam.

[0027] The input source of the motor 16 in the heat pump energy storage system may be the electricity output by the coal-fired unit, or the abandoned electricity of the new energy station or the off-peak electricity of the power grid.

[0028] A method for operating a thermal battery energy storage system coupled with a coal-fired generator set, When the electricity consumption is low, most of the electric energy output by the coal-fired power generation unit through the generator 4 is used as the input source of the motor 16 in the heat pump energy storage system coupled with molten salt heat storage. At the same time, a part of the exhaust steam at the outlet of the medium-pressure cylinder 2 and a part of the exhaust steam at the outlet of the low-pressure cylinder 3 are used as the driving steam and low-temperature heat source of the absorption heat pump 11 to heat the working medium. The heat pump energy storage system coupled with molten salt heat storage converts the excess electric energy and a part of the heat energy of the exhaust steam into the heat energy of molten salt for storage; specifically, close the first valve 21 on the branch line of the feed water bypass entering the molten salt preheater 10-1, stop the high-temperature molten salt pump 25, and start the low-temperature molten salt pump 2 6. Open the second valve 22 on the branch from the outlet of the medium-pressure cylinder 2 to the absorption heat pump 11, and open the third valve 23 on the branch from the outlet of the low-pressure cylinder 3 to the absorption heat pump 11; the amount of coal entering the boiler 9 of the coal-fired generator set does not change, and the operating condition of the steam turbine also fluctuates slightly, ensuring the power generation efficiency; the motor 16 in the heat pump energy storage system drives the multi-stage compressor 14 to work, and at the same time, the working fluid at the outlet of the charging expander 15 enters the absorption heat pump 11 to absorb heat, and the excess electric energy of the coal-fired generator set coupled to the heat pump energy storage system and a part of the heat energy of the exhaust steam are converted into the heat energy of molten salt, which is finally stored in the high-temperature molten salt storage tank 12; When the power consumption is at a peak, open the first valve 21 on the feed water bypass entering the molten salt preheater 10-1 branch, start the high-temperature molten salt pump 25, stop the low-temperature molten salt pump 26, close the second valve 22 on the branch from the outlet of the medium-pressure cylinder 2 to the absorption heat pump 11, and close the third valve 23 on the branch from the outlet of the low-pressure cylinder 3 to the absorption heat pump 11; at this time, part of the feed water of the coal-fired power generation unit enters the molten salt preheater 10-1, the molten salt steam generator 10-2, and the molten salt superheater 10-3 in turn to absorb heat, and the superheated steam generated enters the high-pressure cylinder 1 to further do work, and part of the exhaust steam of the high-pressure cylinder 1 enters the molten salt auxiliary superheater 10-4 to absorb heat, and the reheated steam generated enters the medium-pressure cylinder 2 to further do work, thereby increasing the turbine output and significantly increasing the turbine power generation.

[0029] The above description is only a preferred embodiment of the present invention and is not a limitation of the technical solution of the present invention. It should be pointed out that those skilled in the art can make further improvements and changes based on the technical solution of the present invention, and these improvements and changes should be covered within the protection scope of the present invention.

Claims

1. A thermal battery energy storage system coupled with a coal-fired generator set, characterized in that: It includes a coal-fired power generation system and a heat pump energy storage system coupled with molten salt heat storage; The coal-fired power generation system comprises a high-pressure cylinder (1), an intermediate-pressure cylinder (2), a low-pressure cylinder (3), a generator (4), a condenser (5), a condensate pump (19), a low-pressure heater (6), a deaerator (7), a feedwater pump (20), a high-pressure heater (8), and a boiler (9); the superheated steam outlets of the molten salt superheater (10-3) and the boiler (9) are connected to the inlet of the high-pressure cylinder (1); the feedwater inlet of the boiler (9) is connected to the feedwater outlet of the high-pressure heater (8); the intermediate steam extraction outlet of the high-pressure cylinder (1) is connected to the steam inlet of the high-pressure heater (8) through a pipeline, and the steam outlet of the high-pressure cylinder (1) is respectively connected to the reheat steam inlet of the boiler (1), the steam inlet of the high-pressure heater (8) and the molten salt auxiliary superheater ( The steam inlet of the high-pressure cylinder (10-4) is connected; the fourth valve (24) is connected to the pipeline between the steam outlet of the high-pressure cylinder (1) and the steam inlet of the molten salt auxiliary superheater (10-4); the steam outlet of the molten salt auxiliary superheater (10-4) and the reheat steam outlet of the boiler (1) are connected to the steam inlet of the medium-pressure cylinder (2); the first-stage extraction steam outlet of the medium-pressure cylinder (2) is connected to the steam inlet of the high-pressure heater (8), the second-stage extraction steam outlet is connected to the steam inlet of the deaerator (7), and the steam outlet is respectively connected to the steam inlet of the low-pressure cylinder (3), the low-pressure heater (6) and the driving steam inlet of the absorption heat pump (11); the second valve (22) is connected between the steam outlet of the medium-pressure cylinder (2) and the driving steam inlet of the absorption heat pump (11). The pipe between the outlet of the high-pressure heater (8) and the outlet of the deaerator (7) is connected; the drain outlet of the high-pressure heater (8) is connected to the drain inlet of the deaerator (7); the intermediate steam extraction outlet of the low-pressure cylinder (3) is connected to the steam inlet of the low-pressure heater (6), the steam outlet is connected to the steam inlet of the condenser (5) and the low-temperature heat source inlet of the absorption heat pump (11); the third valve (23) is connected to the pipe between the steam outlet of the low-pressure cylinder (3) and the low-temperature heat source inlet of the absorption heat pump (11); the drain outlet of the low-pressure heater (6) is connected to the drain inlet of the condenser (5); the condensate outlet of the condenser (5) is connected to the condensate inlet of the low-pressure heater (6) through the condensate pump (19); the condensate outlet of the low-pressure heater (6) is connected to the condensate inlet of the deaerator (7) The feed water outlet of the deaerator (7) is connected to the feed water inlet of the high-pressure heater (8) through a feed water pump (20); the feed water outlet of the high-pressure heater (8) is respectively connected to the feed water working medium inlet of the boiler (9) and the cold source inlet of the molten salt preheater (10-1), and the first valve (21) is connected to the pipeline between the feed water outlet of the high-pressure heater (8) and the cold source inlet of the molten salt preheater (10-1); the cold source outlet of the molten salt preheater (10-1) is connected to the cold source inlet of the molten salt steam generator (10-2), and the steam outlet of the molten salt steam generator (10-2) is connected to the cold source inlet of the molten salt superheater (10-3); the high-pressure cylinder (1), the medium-pressure cylinder (2) and the low-pressure cylinder (3) are connected to the generator (4) through a transmission shaft; The heat pump energy storage system coupled with molten salt heat storage comprises an electric motor (16), a multi-stage compressor (14), a molten salt-working fluid heat exchanger (17), a regenerator (18), a charging expander (15), an absorption heat pump (11), a high-temperature molten salt storage tank (12), a high-temperature molten salt pump (25), a low-temperature molten salt storage tank (13), a low-temperature molten salt pump (26), a molten salt preheater (10-1), a molten salt steam generator (10-2), a molten salt superheater (10-3) and a molten salt auxiliary superheater (10-4); the multi-stage compressor ( The working fluid outlet of the molten salt-working fluid heat exchanger (14) is connected to the working fluid inlet of the molten salt-working fluid heat exchanger (17); the working fluid outlet of the molten salt-working fluid heat exchanger (17) is connected to the high-temperature working fluid inlet of the regenerator (18); the high-temperature working fluid outlet of the regenerator (18) is connected to the working fluid inlet of the charging expansion machine (15); the working fluid outlet of the charging expansion machine (15) is connected to the high-temperature heat source inlet of the absorption heat pump (11); the high-temperature heat source outlet of the absorption heat pump (11) is connected to the low-temperature working fluid inlet of the regenerator (18); the low-temperature working fluid outlet of the regenerator (18) is connected to the low-temperature working fluid outlet of the regenerator (18). The outlet of the low-temperature molten salt storage tank (13) is connected to the working medium inlet of the multi-stage compressor (14); the low-temperature heat source outlet of the absorption heat pump (11) is connected to the hot well of the condenser (5); the molten salt outlet of the low-temperature molten salt storage tank (13) is connected to the molten salt inlet of the molten salt-working medium heat exchanger (17) through a low-temperature molten salt pump (26); the molten salt outlet of the molten salt-working medium heat exchanger (17) is connected to the molten salt inlet of the high-temperature molten salt storage tank (12); the molten salt outlet of the high-temperature molten salt storage tank (12) is connected to the molten salt superheater (10-3) and the molten salt auxiliary superheater (10-3) through a high-temperature molten salt pump (25). The molten salt outlets of the molten salt superheater (10-3) and the molten salt auxiliary superheater (10-4) are connected to the molten salt inlet of the molten salt steam generator (10-2), the molten salt outlet of the molten salt steam generator (10-2) is connected to the molten salt inlet of the molten salt preheater (10-1), and the molten salt outlet of the molten salt preheater (10-1) is connected to the molten salt inlet of the low-temperature molten salt storage tank (13); the motor (16), the multi-stage compressor (14), and the charging expander (15) are connected in sequence through a transmission shaft.

2. A thermal battery energy storage system coupled with a coal-fired power generation unit according to claim 1, characterized in that: The exhaust steam of the intermediate pressure cylinder (2) is used as driving steam, and the exhaust steam of the coal-fired power generation unit is used as a low-temperature heat source of the heat pump energy storage system by using an absorption heat pump (11).

3. A thermal battery energy storage system coupled with a coal-fired power generation unit according to claim 1, characterized in that: The circulating working fluid used in the heat pump energy storage system is carbon dioxide, and the circulation form adopts the Brayton cycle. The maximum operating temperature is 565°C and the minimum operating temperature is 18°C.

4. A thermal battery energy storage system coupled with a coal-fired power generation unit according to claim 1, characterized in that: The electric motor (16), the multi-stage compressor (14) and the charging expander (15) are coaxially connected, and the work done by the charging expander (15) offsets part of the power consumption of the multi-stage compressor (14).

5. A thermal battery energy storage system coupled with a coal-fired power generation unit according to claim 1, characterized in that: The high-temperature molten salt storage tank (12) and the low-temperature molten salt storage tank (13) use binary molten salt (40% KNO3+60% NaNO3) as heat storage medium, and the operating temperature range is 290 to 565°C.

6. A thermal battery energy storage system coupled with a coal-fired power generation unit according to claim 1, characterized in that: The high-temperature molten salt medium flows out from the high-temperature molten salt storage tank (12) and serves as a heat source for the molten salt auxiliary superheater (10-4) and the molten salt superheater (10-3), the molten salt steam generator (10-2) and the molten salt preheater (10-1) in sequence, heating the feed water of the coal-fired power generation unit to generate superheated steam and reheated steam.

7. A thermal battery energy storage system coupled with a coal-fired power generation unit according to claim 1, characterized in that: The input source of the electric motor (16) in the heat pump energy storage system comes from the electricity output by the coal-fired unit, or the abandoned electricity of the new energy station or the off-peak electricity of the power grid.

8. An operating method using the system according to any one of claims 1 to 7, characterized in that: When the electricity consumption is low, most of the electric energy output by the coal-fired power generation unit through the generator (4) is used as the input source of the motor (16) of the heat pump energy storage system coupled with molten salt heat storage. At the same time, a part of the exhaust steam at the outlet of the medium-pressure cylinder (2) and a part of the exhaust steam at the outlet of the low-pressure cylinder (3) are used as the driving steam and low-temperature heat source of the absorption heat pump (11) to heat the working fluid. The heat pump energy storage system coupled with molten salt heat storage converts the excess electric energy and a part of the heat energy of the exhaust steam into the heat energy of molten salt for storage. Specifically, the feedwater bypass is closed to enter the molten salt. The valve (21) on the salt preheater (10-1) branch is closed, the high-temperature molten salt pump (25) is shut down, the low-temperature molten salt pump (26) is started, the valve (22) on the branch from the outlet of the medium-pressure cylinder (2) to the absorption heat pump (11) is opened, and the valve (23) on the branch from the outlet of the low-pressure cylinder (3) to the absorption heat pump (11) is opened; the amount of coal entering the boiler (9) of the coal-fired power generation unit does not change, and the operating conditions of the steam turbine also fluctuate slightly, thereby ensuring the power generation efficiency; the motor (16) in the heat pump energy storage system drives the multi-stage compressor (14) to work, and at the same time, the working fluid at the outlet of the charging expander (15) enters the absorption heat pump (11) to absorb heat, converting the excess electric energy of the coal-fired power generation unit coupled to the heat pump energy storage system and a part of the heat energy of the exhaust steam into the heat energy of the molten salt, which is finally stored in the high-temperature molten salt storage tank (12); When the power consumption is at a peak, the valve (21) on the branch line of the feed water bypass entering the molten salt preheater (10-1) is opened, the high-temperature molten salt pump (25) is started, the low-temperature molten salt pump (26) is stopped, the valve (22) on the branch line from the outlet of the intermediate pressure cylinder (2) to the absorption heat pump (11) is closed, and the valve (23) on the branch line from the outlet of the low pressure cylinder (3) to the absorption heat pump (11) is closed; at this time, part of the feed water of the coal-fired power generation unit enters the molten salt preheater (10-1), the molten salt steam generator (10-2), and the molten salt superheater (10-3) in sequence to absorb heat, and the generated superheated steam enters the high-pressure cylinder (1) to further perform work, and part of the exhaust steam of the high-pressure cylinder (1) enters the molten salt auxiliary superheater (10-4) to absorb heat, and the generated reheated steam enters the intermediate pressure cylinder (2) to further perform work, thereby increasing the output of the steam turbine and significantly increasing the power generation of the steam turbine.

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