Steam turbine side low-grade heat energy recovery and multi-medium energy storage Carnot battery system and method

Abstract

The invention discloses a steam turbine side low-grade heat energy recovery and multi-medium energy storage Carnot battery system which comprises a steam Rankine cycle unit, the steam Rankine cycle unit is sequentially connected with a double-salt multi-tank heat storage unit and a Brayton heat pump cycle unit, the steam Rankine cycle unit is further connected with a power generator, and the Brayton heat pump cycle unit is connected with a steam generator. The system further comprises a low-pressure heater set, a medium-pressure heater set and a high-pressure heater set, the steam Rankine cycle unit is connected to the low-pressure heater set, the medium-pressure heater set and the high-pressure heater set, the heat storage water tank set is connected to the medium-pressure heater set, and the high-pressure heater set is connected to the high-pressure heater set. The invention further discloses a control method of the system. The Brayton heat pump circulation efficiency is higher, heat pump side heat storage is subjected to multi-stage compression series connection change, more heat is generated, the Brayton heat pump circulation efficiency is higher, and the overall system efficiency is improved.

Description

Technical Field

[0001] The present invention relates to a Carnot battery system and method for recovering low-grade thermal energy on a steam turbine side and storing multi-medium energy, belonging to the technical field of Carnot battery systems. Background Art

[0002] In the industrial field, there is a large amount of low-grade waste heat in steam turbine systems that is not effectively utilized. Traditional waste heat recovery technologies mainly achieve heat energy conversion through heat exchangers or organic Rankine cycles (ORC), but there are the following problems:

[0003] Mismatch between waste heat quality and utilization scenarios: Low-grade waste heat cannot be directly used for high-parameter power generation or industrial steam needs, and the temperature needs to be raised through supplementary combustion boilers, resulting in additional carbon emissions and increased costs.

[0004] Single heat storage medium: Existing technologies often use a single heat storage medium, making them incapable of tiered storage of waste heat across multiple temperature zones. For example, while molten salt heat storage is suitable for high-temperature zones, it is inefficient for storing medium- and low-temperature waste heat, and molten salt electric heaters are expensive to operate at low temperatures.

[0005] Insufficient system integration: Waste heat recovery and heat storage systems are often designed independently, lacking a dynamic energy matching mechanism. For example, low-grade waste heat power generation systems and heat storage systems are not synergistically optimized, resulting in insufficient waste heat utilization. Summary of the Invention

[0006] The purpose of the present invention is to provide a Carnot battery system for recovering low-grade thermal energy on the turbine side and storing energy in multiple media, and also to provide a control method for the Carnot battery system for recovering low-grade thermal energy on the turbine side and storing energy in multiple media. The present invention makes the Brayton heat pump cycle more efficient, performs multi-stage compression series changes on the heat storage on the heat pump side, generates more heat, makes the Brayton heat pump cycle more efficient, and increases the overall system efficiency.

[0007] To solve the above technical problems, the present invention adopts the following technical solution: a Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, including a steam Rankine cycle unit, to which a dual-salt multi-tank heat storage unit and a Brayton heat pump circulation unit are sequentially connected, the steam Rankine cycle unit is also connected to a generator, and the Brayton heat pump circulation unit is connected to a hot water storage tank group. The system also includes a low-pressure heater group, a medium-pressure heater group and a high-pressure heater group, the steam Rankine cycle unit is respectively connected to the low-pressure heater group, the medium-pressure heater group and the high-pressure heater group, and the hot water storage tank group is connected to the medium-pressure heater group.

[0008] The aforementioned Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, the steam Rankine cycle unit includes a turbine high-pressure cylinder, a turbine intermediate-pressure cylinder and a turbine low-pressure cylinder connected in sequence, a low-pressure heater group connected to the turbine low-pressure cylinder, an intermediate-pressure heater group connected to the turbine intermediate-pressure cylinder, a high-pressure heater group connected to the turbine high-pressure cylinder, and the turbine low-pressure cylinder is also connected to a generator.

[0009] The aforementioned Carnot battery system with low-grade heat recovery and multi-media energy storage on the turbine side, the steam Rankine cycle unit also includes a superheater, an evaporator, a preheater, and a reheater. The superheater, evaporator, and preheater are connected in sequence, and the reheater is respectively connected to the high-pressure cylinder and the intermediate-pressure cylinder of the turbine.

[0010] The aforementioned Carnot battery system with low-grade heat recovery and multi-media energy storage on the turbine side, the steam Rankine cycle unit also includes a deaerator and a condenser, the deaerator is respectively connected to the turbine intermediate pressure cylinder, low pressure heater group, and high pressure heater group, and the condenser is respectively connected to the turbine low pressure cylinder and low pressure heater group.

[0011] The aforementioned Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, the dual-salt multi-tank heat storage unit includes a solar salt molten salt high-temperature heat storage tank, a solar salt molten salt low-temperature heat storage tank, a Hitec salt molten salt high-temperature heat storage tank, a Hitec salt molten salt medium-temperature heat storage tank and a Hitec salt molten salt low-temperature heat storage tank. The solar salt molten salt high-temperature heat storage tank, the solar salt molten salt low-temperature heat storage tank, the Hitec salt molten salt high-temperature heat storage tank, the Hitec salt molten salt medium-temperature heat storage tank and the Hitec salt molten salt low-temperature heat storage tank are all connected to the Brayton heat pump circulation unit, the solar salt molten salt high-temperature heat storage tank is connected to the evaporator, the solar salt molten salt low-temperature heat storage tank is respectively connected to the superheater and the reheater, the Hitec salt molten salt high-temperature heat storage tank is respectively connected to the superheater and the reheater, the Hitec salt molten salt medium-temperature heat storage tank is respectively connected to the evaporator and the preheater, and the Hitec salt molten salt low-temperature heat storage tank is connected to the preheater.

[0012] The aforementioned Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, the Brayton heat pump circulation unit includes a first-stage compressor, an air-molten salt heat exchanger A, a second-stage compressor, an air-molten salt heat exchanger B, an air-molten salt heat exchanger C, and an air-molten salt heat exchanger D connected in sequence, the air-molten salt heat exchanger A is also connected to the solar salt molten salt high-temperature heat storage tank, the air-molten salt heat exchanger B is also respectively connected to the solar salt molten salt low-temperature heat storage tank and the Hitec salt molten salt high-temperature heat storage tank, the air-molten salt heat exchanger C is also respectively connected to the solar salt molten salt high-temperature heat storage tank and the Hitec salt molten salt medium-temperature heat storage tank, and the air-molten salt heat exchanger D is also respectively connected to the Hitec salt molten salt medium-temperature heat storage tank and the Hitec salt molten salt low-temperature heat storage tank.

[0013] The aforementioned Carnot battery system with low-grade heat energy recovery on the turbine side and multi-media energy storage, the D air-molten salt heat exchanger is also connected in sequence to an air-air heat exchanger and an air-water heat exchanger, and the air-water heat exchanger is connected to the hot water tank group.

[0014] In the aforementioned Carnot battery system with low-grade heat recovery on the turbine side and multi-media energy storage, an expander is further connected between the air-air heat exchanger and the air-water heat exchanger.

[0015] The control method of the aforementioned Carnot battery system with low-grade heat recovery on the turbine side and multi-media energy storage,

[0016] When the power consumption of the power grid is low, the heat pump side passage and the heat exchange passage between the molten salt side and the heat pump side are opened at the same time, and the Brayton heat pump circulation unit uses low-cost electricity to act on the first-stage compressor and the second-stage compressor, so that the first-stage compressor and the second-stage compressor work to pressurize the low-temperature and low-pressure air into high-pressure and high-temperature gas, and then the high-pressure and high-temperature gas passes through the high-pressure heater group and the low-pressure heater group, and the high-temperature heat is stored in the solar salt molten salt high-temperature heat storage tank and the solar salt molten salt low-temperature heat storage tank, and the low-temperature heat is stored in the Hitec salt molten salt high-temperature heat storage tank, the Hitec salt molten salt medium-temperature heat storage tank and the Hitec salt molten salt low-temperature heat storage tank, and then after expansion and environmental heating, it enters the first-stage compressor and the second-stage compressor for circulation. At this time, the coal-fired power generation unit stops working;

[0017] When the power grid is at its peak, the turbine side passage and the heat exchange passages between the molten salt side and the heat pump side are opened at the same time. Heat is released through the molten salt, and steam is used to pass through the superheater, reheater, evaporator, and preheater to heat the working fluid in the steam Rankine cycle unit, so that the turbine high-pressure cylinder, turbine intermediate-pressure cylinder, and turbine low-pressure cylinder work to generate electricity. At this time, the Brayton heat pump cycle unit stops working.

[0018] The control method of the Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the aforementioned turbine side, when the Brayton heat pump circulation unit is working, the air passes through the first-stage compressor and then passes through the A air-molten salt heat exchanger and the Hitec salt molten salt medium-temperature heat storage tank for heat exchange to enter the second-stage compressor, and then the air passes through the B air-molten salt heat exchanger and the hot side of the solar salt molten salt high-temperature heat storage tank for heat exchange, the C air-molten salt heat exchanger and the Hitec salt molten salt medium-temperature heat storage tank for heat exchange, the D air-molten salt heat exchanger and the Hitec salt molten salt low-temperature heat storage tank for heat exchange, the hot side of the air-air heat exchanger and then connected to the expander inlet, and after passing through the expander, the air is connected to the first-stage compressor inlet through the cold side of the air-water heat exchanger; the hot water storage tank group includes a hot water storage tank and a cold water storage tank, the working medium air on the heat pump side exchanges heat with the hot water in the hot water storage tank, and then the water flows into the cold water storage tank;

[0019] When the steam Rankine cycle unit is working, the steam comes out of the superheater and passes through the high-pressure cylinder of the steam turbine, the intermediate-pressure cylinder of the steam turbine and the low-pressure cylinder of the steam turbine in sequence to generate electricity. The steam coming out of the high-pressure cylinder of the steam turbine passes through the reheater to the intermediate-pressure cylinder of the steam turbine, and then part of it enters the low-pressure cylinder of the steam turbine. After doing work, it passes through the condenser and the low-pressure heater group and then enters the deaerator. After passing through the deaerator, part of it enters the heat exchanger, evaporator, and superheater in sequence to exchange heat with the double molten salt double salt tank heat storage unit;

[0020] When the dual-salt multi-tank heat storage unit is working, the air comes out from the cold side of the heat exchange between the air-molten salt heat exchanger A and the solar salt molten salt high-temperature heat storage tank, and then stores heat in the solar salt molten salt high-temperature heat storage tank. At peak times, the air passes through the superheater and the reheater in sequence, releases the stored heat into the steam Rankine cycle unit, and then enters the solar salt molten salt low-temperature heat storage tank; the air comes out from the cold side of the heat exchange between the air-molten salt heat exchanger B and the Hitec salt molten salt high-temperature heat storage tank, and then stores heat in the Hitec salt molten salt high-temperature heat storage tank. At peak times, the air passes through the evaporator, releases the stored heat into the steam Rankine cycle unit, and then enters the Hitec salt molten salt medium-temperature heat storage tank; the air comes out from the cold side of the heat exchange between the air-molten salt heat exchanger C and the Hitec salt molten salt medium-temperature heat storage tank, and then stores heat in the Hitec salt molten salt medium-temperature heat storage tank. At peak times, the air passes through the evaporator, releases the stored heat into the steam Rankine cycle unit, and then enters the Hitec salt molten salt low-temperature heat storage tank.

[0021] Compared with the prior art, the present invention is beneficial in that:

[0022] 1. The present invention adds a hot water storage tank and uses the exhaust steam from the coal-fired unit in a cascaded manner to store heat in the hot water storage tank. The hot water in the tank heats the air cooling source on the heat pump side, so that less electricity is consumed to obtain the same amount of heat, resulting in a greatly improved efficiency on the heat pump side and the overall system round-trip efficiency.

[0023] 2. The heat storage system of the present invention adopts a dual-salt multi-molten salt storage tank of solar salt molten salt and Hitec molten salt, which expands the temperature range of heat storage and better matches the high-temperature heat and low-temperature heat generated by the heat pump side, making the temperature zone matching better and the heat storage efficiency higher.

[0024] 3. The heat pump side of the present invention uses a multi-stage compression series method to convert electricity into heat. Under the condition of the same electricity consumption, the heat generated is increased, which increases the efficiency of the Brayton heat pump cycle and the overall round-trip efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention;

[0026] Figure 2This is a diagram of the connection relationship between the steam Rankine cycle unit, the dual-salt multi-tank heat storage unit, the Brayton heat pump cycle unit, and the generator in the present invention.

[0027] Figure 1: 1-steam Rankine cycle unit, 2-dual salt multi-tank heat storage unit, 3-Brayton heat pump circulation unit, 4-generator, 5-heat storage tank group, 6-low pressure heater group, 7-medium pressure heater group, 8-high pressure heater group, 9-steam turbine high pressure cylinder, 10-steam turbine medium pressure cylinder, 11-steam turbine low pressure cylinder, 12-superheater, 13-evaporator, 14-preheater, 15-reheater, 16-deaerator, 17-condenser, 18-solar salt molten salt high temperature heat storage tank, 19-solar salt molten Salt low-temperature heat storage tank, 20-Hitec salt molten salt high-temperature heat storage tank, 21-Hitec salt molten salt medium-temperature heat storage tank, 22-Hitec salt molten salt low-temperature heat storage tank, 23-first-stage compressor, 24-A air-molten salt heat exchanger, 25-second-stage compressor, 26-B air-molten salt heat exchanger, 27-C air-molten salt heat exchanger, 28-D air-molten salt heat exchanger, 29-air-air heat exchanger, 30-air-water heat exchanger, 31-expander, 32-hot water storage tank, 33-cold water storage tank.

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0029] Embodiment 1 of the present invention: A Carnot battery system with low-grade thermal energy recovery and multi-media energy storage on the turbine side includes a steam Rankine cycle unit 1, to which a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump circulation unit 3 are sequentially connected. The steam Rankine cycle unit 1 is also connected to a generator 4, and the Brayton heat pump circulation unit 3 is connected to a hot water storage tank group 5. The system also includes a low-pressure heater group 6, a medium-pressure heater group 7 and a high-pressure heater group 8. The steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7 and the high-pressure heater group 8, and the hot water storage tank group 5 is connected to the medium-pressure heater group 7.

[0030] Embodiment 2 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, to which a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump circulation unit 3 are sequentially connected. The steam Rankine cycle unit 1 is also connected to a generator 4, and the Brayton heat pump circulation unit 3 is connected to a hot water storage tank group 5. The system also includes a low-pressure heater group 6, a medium-pressure heater group 7, and a high-pressure heater group 8. The steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7, and the high-pressure heater group 8, and the hot water storage tank group 5 is connected to the medium-pressure heater group 7; the steam Rankine cycle unit 1 includes a turbine high-pressure cylinder 9, a turbine intermediate-pressure cylinder 10, and a turbine low-pressure cylinder 11 connected in sequence, the low-pressure heater group 6 is connected to the turbine low-pressure cylinder 11, the medium-pressure heater group 7 is connected to the turbine intermediate-pressure cylinder 10, the high-pressure heater group 8 is connected to the turbine high-pressure cylinder 9, and the turbine low-pressure cylinder 11 is also connected to the generator 4.

[0031] Embodiment 3 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, wherein the steam Rankine cycle unit 1 is sequentially connected to a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump cycle unit 3, the steam Rankine cycle unit 1 is further connected to a generator 4, and the Brayton heat pump cycle unit 3 is connected to a hot water storage tank group 5. The system further comprises a low-pressure heater group 6, a medium-pressure heater group 7, and a high-pressure heater group 8. The steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7, and the high-pressure heater group 8, and the hot water storage tank group 5 is connected to the medium-pressure heater Group 7; the steam Rankine cycle unit 1 includes a steam turbine high-pressure cylinder 9, a steam turbine intermediate-pressure cylinder 10 and a steam turbine low-pressure cylinder 11 connected in sequence, the low-pressure heater group 6 is connected to the steam turbine low-pressure cylinder 11, the intermediate-pressure heater group 7 is connected to the steam turbine intermediate-pressure cylinder 10, the high-pressure heater group 8 is connected to the steam turbine high-pressure cylinder 9, and the steam turbine low-pressure cylinder 11 is also connected to the generator 4; the steam Rankine cycle unit 1 also includes a superheater 12, an evaporator 13, a preheater 14, and a reheater 15. The superheater 12, the evaporator 13, and the preheater 14 are connected in sequence, and the reheater 15 is respectively connected to the steam turbine high-pressure cylinder 9 and the steam turbine intermediate-pressure cylinder 10.

[0032] Embodiment 4 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, wherein the steam Rankine cycle unit 1 is sequentially connected to a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump circulation unit 3, the steam Rankine cycle unit 1 is also connected to a generator 4, and the Brayton heat pump circulation unit 3 is connected to a hot water storage tank group 5. The system also includes a low-pressure heater group 6, a medium-pressure heater group 7, and a high-pressure heater group 8. The steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7, and the high-pressure heater group 8, and the hot water storage tank group 5 is connected to the medium-pressure heater group 7; the steam Rankine cycle unit 1 includes a steam turbine high-pressure cylinder 9, a steam turbine medium-pressure cylinder 10, and a steam turbine low-pressure cylinder connected in sequence. 11, the low-pressure heater group 6 is connected to the low-pressure cylinder 11 of the steam turbine, the medium-pressure heater group 7 is connected to the medium-pressure cylinder 10 of the steam turbine, the high-pressure heater group 8 is connected to the high-pressure cylinder 9 of the steam turbine, and the low-pressure cylinder 11 of the steam turbine is also connected to the generator 4; the steam Rankine cycle unit 1 also includes a superheater 12, an evaporator 13, a preheater 14, and a reheater 15, the superheater 12, the evaporator 13, and the preheater 14 are connected in sequence, and the reheater 15 is respectively connected to the high-pressure cylinder 9 and the medium-pressure cylinder 10 of the steam turbine; the steam Rankine cycle unit 1 also includes a deaerator 16 and a condenser 17, the deaerator 16 is respectively connected to the medium-pressure cylinder 10 of the steam turbine, the low-pressure heater group 6, and the high-pressure heater group 8, and the condenser 17 is respectively connected to the low-pressure cylinder 11 of the steam turbine and the low-pressure heater group 6.

[0033] Embodiment 5 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, wherein the steam Rankine cycle unit 1 is sequentially connected to a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump cycle unit 3, the steam Rankine cycle unit 1 is further connected to a generator 4, the Brayton heat pump cycle unit 3 is connected to a hot water storage tank group 5, the system further comprises a low-pressure heater group 6, a medium-pressure heater group 7 and a high-pressure heater group 8, the steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7 and the high-pressure heater group 8, the hot water storage tank group 5 is connected to the medium-pressure Heater group 7; the steam Rankine cycle unit 1 includes a steam turbine high-pressure cylinder 9, a steam turbine intermediate-pressure cylinder 10 and a steam turbine low-pressure cylinder 11 connected in sequence, the low-pressure heater group 6 is connected to the steam turbine low-pressure cylinder 11, the intermediate-pressure heater group 7 is connected to the steam turbine intermediate-pressure cylinder 10, the high-pressure heater group 8 is connected to the steam turbine high-pressure cylinder 9, and the steam turbine low-pressure cylinder 11 is also connected to the generator 4; the steam Rankine cycle unit 1 also includes a superheater 12, an evaporator 13, a preheater 14, and a reheater 15. The superheater 12, the evaporator 13, and the preheater 14 are connected in sequence, and the reheater 15 is respectively connected to the steam turbine high-pressure cylinder 9, the steam turbine The intermediate pressure cylinder 10; the steam Rankine cycle unit 1 also includes a deaerator 16 and a condenser 17, the deaerator 16 is respectively connected to the intermediate pressure cylinder 10 of the steam turbine, the low pressure heater group 6, and the high pressure heater group 8, and the condenser 17 is respectively connected to the low pressure cylinder 11 of the steam turbine and the low pressure heater group 6; the dual salt multi-tank heat storage unit 2 includes a solar salt molten salt high temperature heat storage tank 18, a solar salt molten salt low temperature heat storage tank 19, a Hitec salt molten salt high temperature heat storage tank 20, a Hitec salt molten salt medium temperature heat storage tank 21 and a Hitec salt molten salt low temperature heat storage tank 22, the solar salt molten salt high temperature heat storage tank 18, the solar salt molten salt low temperature heat storage tank Tank 19, Hitec salt molten salt high temperature heat storage tank 20, Hitec salt molten salt medium temperature heat storage tank 21 and Hitec salt molten salt low temperature heat storage tank 22 are all connected to the Brayton heat pump circulation unit 3, the solar salt molten salt high temperature heat storage tank 18 is connected to the evaporator 13, the solar salt molten salt low temperature heat storage tank 19 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt high temperature heat storage tank 20 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt medium temperature heat storage tank 21 is respectively connected to the evaporator 13 and the preheater 14, and the Hitec salt molten salt low temperature heat storage tank 22 is connected to the preheater 14.

[0034] Embodiment 6 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, wherein the steam Rankine cycle unit 1 is sequentially connected to a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump cycle unit 3, the steam Rankine cycle unit 1 is further connected to a generator 4, the Brayton heat pump cycle unit 3 is connected to a hot water storage tank group 5, the system further comprises a low-pressure heater group 6, a medium-pressure heater group 7 and a high-pressure heater group 8, the steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7 and the high-pressure heater group 8, the hot water storage tank group 5 is connected to the medium-pressure Heater group 7; the steam Rankine cycle unit 1 includes a steam turbine high-pressure cylinder 9, a steam turbine intermediate-pressure cylinder 10 and a steam turbine low-pressure cylinder 11 connected in sequence, the low-pressure heater group 6 is connected to the steam turbine low-pressure cylinder 11, the intermediate-pressure heater group 7 is connected to the steam turbine intermediate-pressure cylinder 10, the high-pressure heater group 8 is connected to the steam turbine high-pressure cylinder 9, and the steam turbine low-pressure cylinder 11 is also connected to the generator 4; the steam Rankine cycle unit 1 also includes a superheater 12, an evaporator 13, a preheater 14, and a reheater 15. The superheater 12, the evaporator 13, and the preheater 14 are connected in sequence, and the reheater 15 is respectively connected to the steam turbine high-pressure cylinder 9, the steam turbine The intermediate pressure cylinder 10; the steam Rankine cycle unit 1 also includes a deaerator 16 and a condenser 17, the deaerator 16 is respectively connected to the intermediate pressure cylinder 10 of the steam turbine, the low pressure heater group 6, and the high pressure heater group 8, and the condenser 17 is respectively connected to the low pressure cylinder 11 of the steam turbine and the low pressure heater group 6; the dual salt multi-tank heat storage unit 2 includes a solar salt molten salt high temperature heat storage tank 18, a solar salt molten salt low temperature heat storage tank 19, a Hitec salt molten salt high temperature heat storage tank 20, a Hitec salt molten salt medium temperature heat storage tank 21 and a Hitec salt molten salt low temperature heat storage tank 22, the solar salt molten salt high temperature heat storage tank 18, the solar salt molten salt low temperature heat storage tank Tank 19, Hitec salt molten salt high temperature heat storage tank 20, Hitec salt molten salt medium temperature heat storage tank 21 and Hitec salt molten salt low temperature heat storage tank 22 are all connected to the Brayton heat pump circulation unit 3, the solar salt molten salt high temperature heat storage tank 18 is connected to the evaporator 13, the solar salt molten salt low temperature heat storage tank 19 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt high temperature heat storage tank 20 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt medium temperature heat storage tank 21 is respectively connected to the evaporator 13 and the preheater 14, and the Hitec salt molten salt low temperature heat storage tank 22 is connected to the preheater 14;The Brayton heat pump circulation unit 3 includes a primary compressor 23, an air-molten salt heat exchanger A 24, a secondary compressor 25, an air-molten salt heat exchanger B 26, an air-molten salt heat exchanger C 27, and an air-molten salt heat exchanger D 28, which are connected in sequence. The air-molten salt heat exchanger A 24 is further connected to the solar salt molten salt high-temperature heat storage tank 18, the air-molten salt heat exchanger B 26 is further connected to the solar salt molten salt low-temperature heat storage tank 19 and the Hitec salt molten salt high-temperature heat storage tank 20, the air-molten salt heat exchanger C 27 is further connected to the solar salt molten salt high-temperature heat storage tank 18 and the Hitec salt molten salt medium-temperature heat storage tank 21, and the air-molten salt heat exchanger D 28 is further connected to the Hitec salt molten salt medium-temperature heat storage tank 21 and the Hitec salt molten salt low-temperature heat storage tank 22.

[0035] Embodiment 7 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, wherein the steam Rankine cycle unit 1 is sequentially connected to a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump cycle unit 3, the steam Rankine cycle unit 1 is further connected to a generator 4, the Brayton heat pump cycle unit 3 is connected to a hot water storage tank group 5, the system further comprises a low-pressure heater group 6, a medium-pressure heater group 7 and a high-pressure heater group 8, the steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7 and the high-pressure heater group 8, the hot water storage tank group 5 is connected to the medium-pressure Heater group 7; the steam Rankine cycle unit 1 includes a steam turbine high-pressure cylinder 9, a steam turbine intermediate-pressure cylinder 10 and a steam turbine low-pressure cylinder 11 connected in sequence, the low-pressure heater group 6 is connected to the steam turbine low-pressure cylinder 11, the intermediate-pressure heater group 7 is connected to the steam turbine intermediate-pressure cylinder 10, the high-pressure heater group 8 is connected to the steam turbine high-pressure cylinder 9, and the steam turbine low-pressure cylinder 11 is also connected to the generator 4; the steam Rankine cycle unit 1 also includes a superheater 12, an evaporator 13, a preheater 14, and a reheater 15. The superheater 12, the evaporator 13, and the preheater 14 are connected in sequence, and the reheater 15 is respectively connected to the steam turbine high-pressure cylinder 9, the steam turbine The intermediate pressure cylinder 10; the steam Rankine cycle unit 1 also includes a deaerator 16 and a condenser 17, the deaerator 16 is respectively connected to the intermediate pressure cylinder 10 of the steam turbine, the low pressure heater group 6, and the high pressure heater group 8, and the condenser 17 is respectively connected to the low pressure cylinder 11 of the steam turbine and the low pressure heater group 6; the dual salt multi-tank heat storage unit 2 includes a solar salt molten salt high temperature heat storage tank 18, a solar salt molten salt low temperature heat storage tank 19, a Hitec salt molten salt high temperature heat storage tank 20, a Hitec salt molten salt medium temperature heat storage tank 21 and a Hitec salt molten salt low temperature heat storage tank 22, the solar salt molten salt high temperature heat storage tank 18, the solar salt molten salt low temperature heat storage tank Tank 19, Hitec salt molten salt high temperature heat storage tank 20, Hitec salt molten salt medium temperature heat storage tank 21 and Hitec salt molten salt low temperature heat storage tank 22 are all connected to the Brayton heat pump circulation unit 3, the solar salt molten salt high temperature heat storage tank 18 is connected to the evaporator 13, the solar salt molten salt low temperature heat storage tank 19 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt high temperature heat storage tank 20 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt medium temperature heat storage tank 21 is respectively connected to the evaporator 13 and the preheater 14, and the Hitec salt molten salt low temperature heat storage tank 22 is connected to the preheater 14;The Brayton heat pump circulation unit 3 includes a primary compressor 23, an air-molten salt heat exchanger A 24, a secondary compressor 25, an air-molten salt heat exchanger B 26, an air-molten salt heat exchanger C 27, and an air-molten salt heat exchanger D 28, which are connected in sequence. The air-molten salt heat exchanger A 24 is also connected to a solar salt molten salt high-temperature heat storage tank 18, and the air-molten salt heat exchanger B 26 is also connected to a solar salt molten salt low-temperature heat storage tank 19 and a Hitec salt molten salt high-temperature heat storage tank 20. Air-molten salt heat exchanger C 27 is further connected to solar salt molten salt high-temperature heat storage tank 18 and Hitec salt molten salt medium-temperature heat storage tank 21, respectively. Air-molten salt heat exchanger D 28 is further further connected to Hitec salt molten salt medium-temperature heat storage tank 21 and Hitec salt molten salt low-temperature heat storage tank 22, respectively. Air-molten salt heat exchanger D 28 is further connected in sequence to air-air heat exchanger 29 and air-water heat exchanger 30, and air-water heat exchanger 30 is connected to hot water storage tank group 5.

[0036] Embodiment 8 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, wherein the steam Rankine cycle unit 1 is sequentially connected to a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump cycle unit 3, the steam Rankine cycle unit 1 is further connected to a generator 4, the Brayton heat pump cycle unit 3 is connected to a hot water storage tank group 5, the system further comprises a low-pressure heater group 6, a medium-pressure heater group 7 and a high-pressure heater group 8, the steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7 and the high-pressure heater group 8, the hot water storage tank group 5 is connected to the medium-pressure Heater group 7; the steam Rankine cycle unit 1 includes a steam turbine high-pressure cylinder 9, a steam turbine intermediate-pressure cylinder 10 and a steam turbine low-pressure cylinder 11 connected in sequence, the low-pressure heater group 6 is connected to the steam turbine low-pressure cylinder 11, the intermediate-pressure heater group 7 is connected to the steam turbine intermediate-pressure cylinder 10, the high-pressure heater group 8 is connected to the steam turbine high-pressure cylinder 9, and the steam turbine low-pressure cylinder 11 is also connected to the generator 4; the steam Rankine cycle unit 1 also includes a superheater 12, an evaporator 13, a preheater 14, and a reheater 15. The superheater 12, the evaporator 13, and the preheater 14 are connected in sequence, and the reheater 15 is respectively connected to the steam turbine high-pressure cylinder 9, the steam turbine The intermediate pressure cylinder 10; the steam Rankine cycle unit 1 also includes a deaerator 16 and a condenser 17, the deaerator 16 is respectively connected to the intermediate pressure cylinder 10 of the steam turbine, the low pressure heater group 6, and the high pressure heater group 8, and the condenser 17 is respectively connected to the low pressure cylinder 11 of the steam turbine and the low pressure heater group 6; the dual salt multi-tank heat storage unit 2 includes a solar salt molten salt high temperature heat storage tank 18, a solar salt molten salt low temperature heat storage tank 19, a Hitec salt molten salt high temperature heat storage tank 20, a Hitec salt molten salt medium temperature heat storage tank 21 and a Hitec salt molten salt low temperature heat storage tank 22, the solar salt molten salt high temperature heat storage tank 18, the solar salt molten salt low temperature heat storage tank Tank 19, Hitec salt molten salt high temperature heat storage tank 20, Hitec salt molten salt medium temperature heat storage tank 21 and Hitec salt molten salt low temperature heat storage tank 22 are all connected to the Brayton heat pump circulation unit 3, the solar salt molten salt high temperature heat storage tank 18 is connected to the evaporator 13, the solar salt molten salt low temperature heat storage tank 19 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt high temperature heat storage tank 20 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt medium temperature heat storage tank 21 is respectively connected to the evaporator 13 and the preheater 14, and the Hitec salt molten salt low temperature heat storage tank 22 is connected to the preheater 14;The Brayton heat pump circulation unit 3 includes a primary compressor 23, an air-molten salt heat exchanger A 24, a secondary compressor 25, an air-molten salt heat exchanger B 26, an air-molten salt heat exchanger C 27, and an air-molten salt heat exchanger D 28, which are connected in sequence. The air-molten salt heat exchanger A 24 is also connected to a solar salt molten salt high-temperature heat storage tank 18, the air-molten salt heat exchanger B 26 is also respectively connected to a solar salt molten salt low-temperature heat storage tank 19 and a Hitec salt molten salt high-temperature heat storage tank 20, and the air-molten salt heat exchanger C 27 is also respectively connected to In addition to the solar salt molten salt high-temperature heat storage tank 18 and the Hitec salt molten salt medium-temperature heat storage tank 21, the D air-molten salt heat exchanger 28 is also connected to the Hitec salt molten salt medium-temperature heat storage tank 21 and the Hitec salt molten salt low-temperature heat storage tank 22, respectively. The D air-molten salt heat exchanger 28 is also connected in sequence to an air-air heat exchanger 29 and an air-water heat exchanger 30, which is connected to the hot water storage tank group 5. An expander 31 is also connected between the air-air heat exchanger 29 and the air-water heat exchanger 30.

[0037] Embodiment 9 of the present invention: A Carnot battery system with low-grade heat energy recovery and multi-media energy storage on the turbine side, comprising a steam Rankine cycle unit 1, wherein the steam Rankine cycle unit 1 is sequentially connected to a dual-salt multi-tank heat storage unit 2 and a Brayton heat pump cycle unit 3, the steam Rankine cycle unit 1 is further connected to a generator 4, the Brayton heat pump cycle unit 3 is connected to a hot water storage tank group 5, the system further comprises a low-pressure heater group 6, a medium-pressure heater group 7 and a high-pressure heater group 8, the steam Rankine cycle unit 1 is respectively connected to the low-pressure heater group 6, the medium-pressure heater group 7 and the high-pressure heater group 8, the hot water storage tank group 5 is connected to the medium-pressure Heater group 7; the steam Rankine cycle unit 1 includes a steam turbine high-pressure cylinder 9, a steam turbine intermediate-pressure cylinder 10 and a steam turbine low-pressure cylinder 11 connected in sequence, the low-pressure heater group 6 is connected to the steam turbine low-pressure cylinder 11, the intermediate-pressure heater group 7 is connected to the steam turbine intermediate-pressure cylinder 10, the high-pressure heater group 8 is connected to the steam turbine high-pressure cylinder 9, and the steam turbine low-pressure cylinder 11 is also connected to the generator 4; the steam Rankine cycle unit 1 also includes a superheater 12, an evaporator 13, a preheater 14, and a reheater 15. The superheater 12, the evaporator 13, and the preheater 14 are connected in sequence, and the reheater 15 is respectively connected to the steam turbine high-pressure cylinder 9, the steam turbine The intermediate pressure cylinder 10; the steam Rankine cycle unit 1 also includes a deaerator 16 and a condenser 17, the deaerator 16 is respectively connected to the intermediate pressure cylinder 10 of the steam turbine, the low pressure heater group 6, and the high pressure heater group 8, and the condenser 17 is respectively connected to the low pressure cylinder 11 of the steam turbine and the low pressure heater group 6; the dual salt multi-tank heat storage unit 2 includes a solar salt molten salt high temperature heat storage tank 18, a solar salt molten salt low temperature heat storage tank 19, a Hitec salt molten salt high temperature heat storage tank 20, a Hitec salt molten salt medium temperature heat storage tank 21 and a Hitec salt molten salt low temperature heat storage tank 22, the solar salt molten salt high temperature heat storage tank 18, the solar salt molten salt low temperature heat storage tank Tank 19, Hitec salt molten salt high temperature heat storage tank 20, Hitec salt molten salt medium temperature heat storage tank 21 and Hitec salt molten salt low temperature heat storage tank 22 are all connected to the Brayton heat pump circulation unit 3, the solar salt molten salt high temperature heat storage tank 18 is connected to the evaporator 13, the solar salt molten salt low temperature heat storage tank 19 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt high temperature heat storage tank 20 is respectively connected to the superheater 12 and the reheater 15, the Hitec salt molten salt medium temperature heat storage tank 21 is respectively connected to the evaporator 13 and the preheater 14, and the Hitec salt molten salt low temperature heat storage tank 22 is connected to the preheater 14;The Brayton heat pump circulation unit 3 includes a primary compressor 23, an air-molten salt heat exchanger A 24, a secondary compressor 25, an air-molten salt heat exchanger B 26, an air-molten salt heat exchanger C 27, and an air-molten salt heat exchanger D 28, which are connected in sequence. The air-molten salt heat exchanger A 24 is also connected to the solar salt molten salt high-temperature heat storage tank 18, the air-molten salt heat exchanger B 26 is also respectively connected to the solar salt molten salt low-temperature heat storage tank 19 and the Hitec salt molten salt high-temperature heat storage tank 20, the air-molten salt heat exchanger C 27 is also respectively connected to the solar salt molten salt high-temperature heat storage tank 18 and the Hitec salt molten salt medium-temperature heat storage tank 21, and the air-molten salt heat exchanger D 28 is also respectively connected to the Hitec salt molten salt medium-temperature heat storage tank 21 and the Hitec salt molten salt low-temperature heat storage tank 22; the air-molten salt heat exchanger D 28 is also connected in sequence to the air- Heat exchanger 29 and air-water heat exchanger 30 are connected to hot water storage tank group 5; an expander 31 is also connected between the air-air heat exchanger 29 and the air-water heat exchanger 30; wherein, the solar salt molten salt high-temperature heat storage tank 18 contains solar salt at a temperature of 550-588°C, preferably 556°C; the solar salt molten salt low-temperature heat storage tank 19 contains solar salt at a temperature of 380-410°C, preferably 405°C; the Hitec salt molten salt high-temperature heat storage tank 20 contains Hitec salt at a temperature of 390-410°C, preferably 408°C; the Hitec salt molten salt medium-temperature heat storage tank 21 contains Hitec salt at a temperature of 340-360°C, preferably 355°C; and the Hitec salt molten salt low-temperature heat storage tank 22 contains Hitec salt at a temperature of 190-210°C, preferably 207°C.

[0038] Embodiment 10 of the present invention: A control method for a Carnot battery system with low-grade heat recovery on the turbine side and multi-media energy storage,

[0039] When the power consumption of the power grid is low, the heat pump side passage and the heat exchange passage between the molten salt side and the heat pump side are opened at the same time, and the Brayton heat pump circulation unit 3 uses low-cost electricity to act on the first-stage compressor 23 and the second-stage compressor 25, so that the first-stage compressor 23 and the second-stage compressor 25 work to pressurize the low-temperature and low-pressure air to high-pressure and high-temperature gas, and then the high-pressure and high-temperature gas passes through the high-pressure heater group 8 and the low-pressure heater group 6, and the high-temperature heat is stored in the solar salt molten salt high-temperature heat storage tank 18 and the solar salt molten salt low-temperature heat storage tank 19, and the low-temperature heat is stored in the Hitec salt molten salt high-temperature heat storage tank 20, the Hitec salt molten salt medium-temperature heat storage tank 21 and the Hitec salt molten salt low-temperature heat storage tank 22, and then enters the first-stage compressor 23 and the second-stage compressor 25 for circulation after expansion and environmental heating. At this time, the coal-fired power generation unit stops working;

[0040] When the power grid is at its peak, the turbine side passage and the heat exchange passages between the molten salt side and the heat pump side are opened at the same time, heat is released through the molten salt, and steam is used to pass through the superheater 12, the reheater 15, the evaporator 13, and the preheater 14 to heat the working medium in the steam Rankine cycle unit 1, so that the turbine high-pressure cylinder 9, the turbine intermediate-pressure cylinder 10, and the turbine low-pressure cylinder 11 are operated to generate electricity. At this time, the Brayton heat pump circulation unit 3 stops working.

[0041] Embodiment 11 of the present invention: A control method for a Carnot battery system with low-grade heat recovery on the turbine side and multi-media energy storage,

[0042] When the power consumption of the power grid is low, the heat pump side passage and the heat exchange passage between the molten salt side and the heat pump side are opened at the same time, and the Brayton heat pump circulation unit 3 uses low-cost electricity to act on the first-stage compressor 23 and the second-stage compressor 25, so that the first-stage compressor 23 and the second-stage compressor 25 work to pressurize the low-temperature and low-pressure air to high-pressure and high-temperature gas, and then the high-pressure and high-temperature gas passes through the high-pressure heater group 8 and the low-pressure heater group 6, and the high-temperature heat is stored in the solar salt molten salt high-temperature heat storage tank 18 and the solar salt molten salt low-temperature heat storage tank 19, and the low-temperature heat is stored in the Hitec salt molten salt high-temperature heat storage tank 20, the Hitec salt molten salt medium-temperature heat storage tank 21 and the Hitec salt molten salt low-temperature heat storage tank 22, and then enters the first-stage compressor 23 and the second-stage compressor 25 for circulation after expansion and environmental heating. At this time, the coal-fired power generation unit stops working;

[0043] When the power grid is in peak demand, the steam turbine side passage and the heat exchange passages between the molten salt side and the heat pump side are opened simultaneously, and heat is released through the molten salt. Steam is used to pass through the superheater 12, the reheater 15, the evaporator 13, and the preheater 14, so that the working medium in the steam Rankine cycle unit 1 is heated, and the high-pressure cylinder 9, the intermediate-pressure cylinder 10, and the low-pressure cylinder 11 of the steam turbine are operated to generate electricity. At this time, the Brayton heat pump cycle unit 3 stops working.

[0044] When the Brayton heat pump circulation unit 3 is working, the air passes through the first-stage compressor and then passes through the A air-molten salt heat exchanger 24 to exchange heat with the Hitec salt molten salt medium-temperature heat storage tank 21 to enter the second-stage compressor 25. Then, the air passes through the B air-molten salt heat exchanger 26 and the hot side of the solar salt molten salt high-temperature heat storage tank 18, the C air-molten salt heat exchanger 27 and the hot side of the Hitec salt molten salt medium-temperature heat storage tank 21, the D air-molten salt heat exchanger 28 and the hot side of the Hitec salt molten salt low-temperature heat storage tank 22, and the hot side of the air-air heat exchanger 29, and then is connected to the inlet of the expander 31. After passing through the expander 31, the air is connected to the inlet of the first-stage compressor 23 through the cold side of the air-water heat exchanger 30; the hot water storage tank group 5 includes a hot water storage tank 32 and a cold water storage tank 33, and the working medium air on the heat pump side exchanges heat with the hot water in the hot water storage tank 32, and then the water flows into the cold water storage tank 33;

[0045] When the steam Rankine cycle unit is working, the steam comes out of the superheater 12 and passes through the turbine high-pressure cylinder 9, the turbine intermediate-pressure cylinder 10 and the turbine low-pressure cylinder 11 in sequence to generate electricity. The steam coming out of the turbine high-pressure cylinder 9 passes through the reheater 15 to the turbine intermediate-pressure cylinder 10, and then a part of it enters the turbine low-pressure cylinder 11. After doing work, it passes through the condenser 17 and the low-pressure heater group 6 and enters the deaerator 16. After passing through the deaerator 16, a part of it enters the heat exchanger, the evaporator 13, and the superheater 12 in sequence to exchange heat with the double molten salt double salt tank heat storage unit;

[0046] When the dual-salt multi-tank heat storage unit is working, the air comes out from the cold side of the heat exchange between the A air-molten salt heat exchanger 24 and the solar salt molten salt high-temperature heat storage tank 18 and stores the heat in the solar salt molten salt high-temperature heat storage tank 18. At the peak time, the air passes through the superheater 12 and the reheater 15 in sequence, releases the stored heat into the steam Rankine cycle unit 1, and then enters the solar salt molten salt low-temperature heat storage tank 19; the air comes out from the cold side of the heat exchange between the B air-molten salt heat exchanger 26 and the Hitec salt molten salt high-temperature heat storage tank 20 and stores the heat in the Hitec salt molten salt. In the high-temperature heat storage tank 20, at peak times, the stored heat is released into the steam Rankine cycle unit 1 through the evaporator 13, and then enters the Hitec salt molten salt medium-temperature heat storage tank 21; the air comes out from the cold side of the C air-molten salt heat exchanger 27 and the Hitec salt molten salt medium-temperature heat storage tank 21 after heat exchange, and then stores heat in the Hitec salt molten salt medium-temperature heat storage tank 21. At peak times, the air passes through the evaporator 13, releases the stored heat into the steam Rankine cycle unit 1, and then enters the Hitec salt molten salt low-temperature heat storage tank 22.

[0047] The working principle of an embodiment of the present invention is as follows:

[0048] When the present invention works:

[0049] When the power consumption of the power grid is low, the heat pump side passage and the heat exchange passage between the molten salt side and the heat pump side are opened at the same time, and the Brayton heat pump circulation unit 3 uses low-cost electricity to act on the first-stage compressor 23 and the second-stage compressor 25, so that the first-stage compressor 23 and the second-stage compressor 25 work to pressurize the low-temperature and low-pressure air to high-pressure and high-temperature gas, and then the high-pressure and high-temperature gas passes through the high-pressure heater group 8 and the low-pressure heater group 6, and the high-temperature heat is stored in the solar salt molten salt high-temperature heat storage tank 18 and the solar salt molten salt low-temperature heat storage tank 19, and the low-temperature heat is stored in the Hitec salt molten salt high-temperature heat storage tank 20, the Hitec salt molten salt medium-temperature heat storage tank 21 and the Hetic salt molten salt low-temperature heat storage tank 22, and then after expansion and environmental heating, it enters the first-stage compressor 23 and the second-stage compressor 25 for circulation. At this time, the coal-fired power generation unit stops working;

[0050] When the power grid is at its peak, the turbine side passage and the heat exchange passages between the molten salt side and the heat pump side are opened at the same time, heat is released through the molten salt, and steam is used to pass through the superheater 12, the reheater 15, the evaporator 13, and the preheater 14 to heat the working medium in the steam Rankine cycle unit 1, so that the turbine high-pressure cylinder 9, the turbine intermediate-pressure cylinder 10, and the turbine low-pressure cylinder 11 are operated to generate electricity. At this time, the Brayton heat pump circulation unit 3 stops working.

Claims

1. A Carnot battery system for recovering low-grade thermal energy from a steam turbine and storing energy in multiple media, comprising a steam Rankine cycle unit (1), characterized in that: The steam Rankine cycle unit (1) is sequentially connected to a dual-salt multi-tank heat storage unit (2) and a Brayton heat pump cycle unit (3); the steam Rankine cycle unit (1) is also connected to a generator (4); the Brayton heat pump cycle unit (3) is connected to a hot water storage tank group (5); the system further comprises a low-pressure heater group (6), a medium-pressure heater group (7) and a high-pressure heater group (8); the steam Rankine cycle unit (1) is respectively connected to the low-pressure heater group (6), the medium-pressure heater group (7) and the high-pressure heater group (8); and the hot water storage tank group (5) is connected to the medium-pressure heater group (7).

2. The Carnot battery system for recovering low-grade thermal energy from the turbine side and storing energy in multiple media according to claim 1 is characterized in that: The steam Rankine cycle unit (1) comprises a steam turbine high-pressure cylinder (9), a steam turbine intermediate-pressure cylinder (10) and a steam turbine low-pressure cylinder (11) connected in sequence, a low-pressure heater group (6) being connected to the steam turbine low-pressure cylinder (11), an intermediate-pressure heater group (7) being connected to the steam turbine intermediate-pressure cylinder (10), a high-pressure heater group (8) being connected to the steam turbine high-pressure cylinder (9), and the steam turbine low-pressure cylinder (11) being further connected to a generator (4).

3. The Carnot battery system for recovering low-grade thermal energy from the turbine side and storing energy in multiple media according to claim 2 is characterized in that: The steam Rankine cycle unit (1) further comprises a superheater (12), an evaporator (13), a preheater (14), and a reheater (15); the superheater (12), the evaporator (13), and the preheater (14) are connected in sequence, and the reheater (15) is respectively connected to the high-pressure cylinder (9) and the intermediate-pressure cylinder (10) of the steam turbine.

4. The Carnot battery system for recovering low-grade thermal energy from the turbine side and storing energy in multiple media according to claim 2, characterized in that: The steam Rankine cycle unit (1) further comprises a deaerator (16) and a condenser (17), wherein the deaerator (16) is respectively connected to the steam turbine intermediate pressure cylinder (10), the low pressure heater group (6), and the high pressure heater group (8), and the condenser (17) is respectively connected to the steam turbine low pressure cylinder (11) and the low pressure heater group (6).

5. The Carnot battery system for recovering low-grade thermal energy from the turbine side and storing energy in multiple media according to claim 4 is characterized in that: The dual-salt multi-tank heat storage unit (2) comprises a solar salt molten salt high-temperature heat storage tank (18), a solar salt molten salt low-temperature heat storage tank (19), a Hitec salt molten salt high-temperature heat storage tank (20), a Hitec salt molten salt medium-temperature heat storage tank (21) and a Hitec salt molten salt low-temperature heat storage tank (22), and the solar salt molten salt high-temperature heat storage tank (18), the solar salt molten salt low-temperature heat storage tank (19), the Hitec salt molten salt high-temperature heat storage tank (20), the Hitec salt molten salt medium-temperature heat storage tank (21) and the Hitec salt molten salt low-temperature heat storage tank (22 ) are connected to the Brayton heat pump circulation unit (3), the solar salt molten salt high temperature heat storage tank (18) is connected to the evaporator (13), the solar salt molten salt low temperature heat storage tank (19) is respectively connected to the superheater (12) and the reheater (15), the Hitec salt molten salt high temperature heat storage tank (20) is respectively connected to the superheater (12) and the reheater (15), the Hitec salt molten salt medium temperature heat storage tank (21) is respectively connected to the evaporator (13) and the preheater (14), and the Hitec salt molten salt low temperature heat storage tank (22) is connected to the preheater (14).

6. The Carnot battery system for recovering low-grade thermal energy from the turbine side and storing energy in multiple media according to claim 5, characterized in that: The Brayton heat pump circulation unit (3) comprises a primary compressor (23), an air-molten salt heat exchanger (24) A, a secondary compressor (25), an air-molten salt heat exchanger (26) B, an air-molten salt heat exchanger (27) C, and an air-molten salt heat exchanger (28) connected in sequence, wherein the air-molten salt heat exchanger (24) is further connected to a solar salt molten salt high-temperature heat storage tank (18), the air-molten salt heat exchanger (26) is further connected to a solar salt molten salt low-temperature heat storage tank (19) and a Hitec salt molten salt high-temperature heat storage tank (20), the air-molten salt heat exchanger (27) is further connected to a solar salt molten salt high-temperature heat storage tank (18) and a Hitec salt molten salt medium-temperature heat storage tank (21), and the air-molten salt heat exchanger (28) is further connected to a Hitec salt molten salt medium-temperature heat storage tank (21) and a Hitec salt molten salt low-temperature heat storage tank (22).

7. The Carnot battery system for recovering low-grade thermal energy from the turbine side and storing energy in multiple media according to claim 6, characterized in that: The D air-molten salt heat exchanger (28) is also connected in sequence to an air-air heat exchanger (29) and an air-water heat exchanger (30), and the air-water heat exchanger (30) is connected to the hot water storage tank group (5).

8. The Carnot battery system for recovering low-grade thermal energy from the turbine side and storing energy in multiple media according to claim 7, characterized in that: An expander (31) is also connected between the air-air heat exchanger (29) and the air-water heat exchanger (30).

9. A control method for the system according to claim 1-8, characterized in that: When the power consumption of the power grid is low, the heat pump side passage and the heat exchange passage between the molten salt side and the heat pump side are opened at the same time, and the Brayton heat pump circulation unit (3) uses low-cost electricity to act on the first-stage compressor (23) and the second-stage compressor (25), so that the first-stage compressor (23) and the second-stage compressor (25) work to pressurize the low-temperature and low-pressure air into high-pressure and high-temperature gas, and then the high-pressure and high-temperature gas passes through the high-pressure heater group (8) and the low-pressure heater group (6), and the high-temperature heat is stored in the solar salt molten salt high-temperature heat storage tank (18) and the solar salt molten salt low-temperature heat storage tank (19), and the low-temperature heat is stored in the Hitec salt molten salt high-temperature heat storage tank (20), the Hitec salt molten salt medium-temperature heat storage tank (21) and the Hitec salt molten salt low-temperature heat storage tank (22), and then enters the first-stage compressor (23) and the second-stage compressor (25) for circulation after expansion and environmental heating. At this time, the coal-fired power generation unit stops working; When the power grid is at its peak, the steam turbine side passage and the heat exchange passages on the molten salt side and the heat pump side are opened simultaneously, heat is released through the molten salt, and steam is used to pass through the superheater (12), the reheater (15), the evaporator (13), and the preheater (14) to heat the working medium in the steam Rankine cycle unit (1), so that the high-pressure cylinder (9), the intermediate-pressure cylinder (10), and the low-pressure cylinder (11) of the steam turbine are operated to generate electricity. At this time, the Brayton heat pump cycle unit (3) stops working.

10. The control method according to claim 9, characterized in that: When the Brayton heat pump circulation unit (3) is working, the air passes through the first-stage compressor and then sequentially passes through the A air-molten salt heat exchanger (24) and the Hitec salt molten salt medium-temperature heat storage tank (21) for heat exchange and enters the second-stage compressor (25). Then, the air sequentially passes through the B air-molten salt heat exchanger (26) and the hot side of the solar salt molten salt high-temperature heat storage tank (18), the C air-molten salt heat exchanger (27) and the hot side of the Hitec salt molten salt medium-temperature heat storage tank (21), and the D air-molten salt heat exchanger. The heat exchanger (28) exchanges heat with the hot side of the Hitec salt molten salt low-temperature heat storage tank (22), the hot side of the air-air heat exchanger (29), and then communicates with the inlet of the expander (31). After passing through the expander (31), the steam is communicated with the inlet of the first-stage compressor (23) through the cold side of the air-water heat exchanger (30); the hot water storage tank group (5) includes a hot water storage tank (32) and a cold water storage tank (33). The working medium air on the heat pump side exchanges heat with the hot water in the hot water storage tank (32), and then the water flows into the cold water storage tank (33); When the steam Rankine cycle unit is in operation, steam comes out of the superheater (12) and passes through the high-pressure cylinder (9) of the steam turbine, the intermediate-pressure cylinder (10) of the steam turbine and the low-pressure cylinder (11) of the steam turbine in sequence to generate electricity. The steam coming out of the high-pressure cylinder (9) of the steam turbine passes through the reheater (15) to the intermediate-pressure cylinder (10) of the steam turbine, and then a part of it enters the low-pressure cylinder (11) of the steam turbine. After doing work, it passes through the condenser (17) and the low-pressure heater group (6) and then enters the deaerator (16). A part of it passes through the deaerator (16) and then enters the heat exchanger (14), the evaporator (13) and the superheater (12) in sequence to exchange heat with the double molten salt double salt tank heat storage unit (2); When the dual-salt multi-tank heat storage unit is in operation, the air comes out from the cold side of the heat exchange between the A air-molten salt heat exchanger (24) and the solar salt molten salt high-temperature heat storage tank (18), and then stores heat in the solar salt molten salt high-temperature heat storage tank (18). At the peak time, the air passes through the superheater (12) and the reheater (15) in sequence, releases the stored heat into the steam Rankine cycle unit (1), and then enters the solar salt molten salt low-temperature heat storage tank (19); the air comes out from the cold side of the heat exchange between the B air-molten salt heat exchanger (26) and the Hitec salt molten salt high-temperature heat storage tank (20), and then stores heat in the Hitec salt molten salt high-temperature heat storage tank (20). At the peak time, the air passes through the evaporator (13), releases the stored heat into the steam Rankine cycle unit (1), and then enters the Hitec salt molten salt medium-temperature heat storage tank (21); The air comes out from the cold side of the heat exchange between the C air-molten salt heat exchanger (27) and the Hitec salt molten salt medium temperature heat storage tank (21) and stores the heat in the Hitec salt molten salt medium temperature heat storage tank (21). At the peak time, the air passes through the evaporator (13) and releases the stored heat into the steam Rankine cycle unit (1), and then enters the Hitec salt molten salt low temperature heat storage tank (22).

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