Industrial steam supply peak shaving system and method based on molten salt heat storage and back pressure turbine coupling

Abstract

The application discloses an industrial steam supply peak shaving system and method based on molten salt heat storage and back pressure machine coupling, relates to the flexible reconstruction technical field of thermal power generating units, and comprises a molten salt heat storage subsystem and a back pressure machine power generation subsystem; the molten salt heat storage subsystem forms a heat storage route through a low-temperature molten salt tank, a molten salt electric heater and a high-temperature molten salt tank; a heat release route is formed through the high-temperature molten salt tank, a molten salt steam heat exchanger, a molten salt feed water heat exchanger, a molten salt condensate water heat exchanger and the low-temperature molten salt tank; the back pressure machine power generation subsystem comprises a back pressure machine and a back pressure machine generator; a steam inlet of the back pressure machine is connected to a main steam pipeline in front of a high-pressure cylinder of a steam turbine through a main steam extraction pipeline, and a steam outlet of the back pressure machine is connected to a steam inlet of the molten salt steam heat exchanger; the application can supply stable parameter industrial steam to the outside while greatly reducing power generation output, and breaks through the operation limitation of 'determining power by heat'.

Description

Technical Field

[0001] This invention relates to the field of thermal power generating unit flexibility retrofitting technology, and in particular to an industrial steam supply peak shaving system and method based on molten salt thermal storage coupled with a back pressure turbine. Background Technology

[0002] A green and low-carbon transformation of the energy structure is the only way to achieve the "dual carbon" goals. With the rapid increase in installed capacity of renewable energy sources such as wind and solar power, the intermittency and volatility of their output pose a severe challenge to the stable operation of the power grid. Thermal power units, especially coal-fired units, which are currently the ballast of the power system, are gradually shifting from being the main source of electricity supply to a regulating and guaranteeing power source. Therefore, improving the deep peak-shaving capacity of thermal power units, especially combined heat and power (CHP) units, has become a key technological path to improve the grid's renewable energy absorption capacity.

[0003] However, for thermal power units that both generate electricity and supply high-parameter, high-flow-rate industrial steam to surrounding industrial parks, their peak-shaving capacity is severely constrained. To ensure stable steam supply parameters, the units typically need to maintain high load operation, making it difficult to respond to the grid's deep peak-shaving demands. This "thermal-electric coupling" contradiction is particularly prominent in areas with concentrated industrial heating demand. Although many flexible retrofit technologies exist, such as low-pressure cylinder cut-off, electric boilers, and thermal storage tanks, they generally suffer from limited peak-shaving depth, high investment costs, low energy efficiency, or impacts on main unit safety. Specifically, low-pressure cylinder cut-off technology may threaten the safety of the turbine's last-stage blades under harsh operating conditions; electric boiler solutions directly convert high-grade electrical energy into low-grade thermal energy, resulting in significant energy loss and low energy efficiency; conventional thermal storage solutions face problems such as limited peak-shaving depth, system complexity, and high investment costs, making it difficult to balance deep peak-shaving, efficient steam supply, and main unit safety. Summary of the Invention

[0004] The purpose of this invention is to provide an industrial steam supply peak-shaving system and method based on molten salt thermal storage and back-pressure turbine coupling, so as to solve the problems existing in the prior art, and realize the ability to supply industrial steam with stable parameters while significantly reducing power generation output, thus breaking through the "heat-determined power generation" operation limitation.

[0005] To achieve the above objectives, the present invention provides the following solution: This invention provides an industrial steam supply and peak shaving system based on molten salt thermal storage coupled with a back pressure turbine, including a molten salt thermal storage subsystem and a back pressure turbine power generation system; The molten salt thermal storage subsystem includes a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt electric heater, a molten salt steam heat exchanger, a molten salt feedwater heat exchanger, and a molten salt condensate heat exchanger. The low-temperature molten salt tank, the molten salt electric heater, and the high-temperature molten salt tank form a thermal storage route. The outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the molten salt electric heater via a molten salt pump, and the molten salt outlet of the molten salt electric heater is connected to the inlet of the high-temperature molten salt tank. The high-temperature molten salt tank, the molten salt steam heat exchanger, the molten salt feedwater heat exchanger, the molten salt condensate heat exchanger, and the low-temperature molten salt tank form a heat release route. The outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the molten salt steam heat exchanger, the molten salt outlet of the molten salt steam heat exchanger is connected to the molten salt inlet of the molten salt feedwater heat exchanger, the molten salt outlet of the molten salt feedwater heat exchanger is connected to the molten salt inlet of the molten salt condensate heat exchanger, and the molten salt outlet of the molten salt condensate heat exchanger is connected to the inlet of the low-temperature molten salt tank. The back pressure generator power system includes a back pressure generator and a back pressure generator; the steam inlet of the back pressure generator is connected to the main steam pipeline in front of the high-pressure cylinder of the steam turbine through the main steam extraction pipeline, and the steam outlet of the back pressure generator is connected to the steam inlet of the molten salt steam heat exchanger; the back pressure generator and the back pressure generator are connected by a drive.

[0006] In some embodiments, the molten salt used in the molten salt thermal storage subsystem is a binary nitrate, with an operating temperature range of 290°C to 565°C.

[0007] In some embodiments, a pressure reducing valve is provided before the steam inlet of the back pressure compressor to adjust the steam inlet pressure of the back pressure compressor according to the main steam pressure under different load conditions, the exhaust pressure matches the industrial steam supply pressure demand, and the steam flow rate matches the industrial steam supply flow rate demand.

[0008] In some embodiments, the molten salt electric heater uses electrical energy from a generator or plant power.

[0009] Based on the above-mentioned industrial steam supply peak shaving system based on molten salt thermal storage and back pressure turbine coupling, the present invention also provides an industrial steam supply peak shaving method based on molten salt thermal storage and back pressure turbine coupling, including thermal storage mode and thermal release mode. The thermal storage mode is carried out when the unit's electrical load is greater than the grid load demand: the low-temperature molten salt in the low-temperature molten salt tank is sent to the molten salt electric heater, and the low-temperature molten salt is heated into high-temperature molten salt and stored in the high-temperature molten salt tank by the molten salt electric heater, while steam is continuously drawn from the heat reheat pipeline to supply industrial steam to the outside. The heat release mode is implemented when the power grid requires the unit to perform deep peak shaving to low load: main steam is drawn from the main steam pipeline and sent to the back compressor to do work, driving the back compressor generator to generate electricity. The exhaust steam from the back compressor is sent to the molten salt steam heat exchanger to exchange heat with the high-temperature molten salt from the high-temperature molten salt tank. After being heated to the rated parameters, it is supplied to the outside as industrial steam. The molten salt after exchanging heat with the steam flows sequentially through the molten salt feedwater heat exchanger and the molten salt condensate heat exchanger to heat the feedwater and condensate respectively, and finally returns to the low-temperature molten salt tank.

[0010] In some implementations, the residual heat from the molten salt after heating the exhaust steam of the back pressure turbine is used to heat the feedwater and condensate through a molten salt feedwater heat exchanger and a molten salt condensate heat exchanger.

[0011] In some implementations, by controlling the main steam extraction flow rate and the high-temperature molten salt flow rate, the unit load can be reduced to below 30% of the rated load while maintaining stable industrial steam supply parameters.

[0012] The present invention achieves the following technical effects compared to the prior art: The industrial steam supply peak-shaving system and method based on molten salt thermal storage and back-pressure turbine coupling in this invention sets up two independent paths for thermal storage and thermal release. In thermal storage mode, electrical energy is converted into molten salt thermal energy by a molten salt electric heater for storage. In thermal release mode, the main steam is extracted from the front of the high-pressure cylinder, first expanded by the back-pressure turbine to generate electricity, and then the exhaust steam is sent to the molten salt steam heat exchanger to exchange heat with high-temperature molten salt, thereby decoupling the strong thermoelectric coupling relationship. The molten salt steam heat exchanger is used to heat the exhaust steam of the back-pressure turbine to the rated steam supply parameters, ensuring the stability of industrial steam supply temperature and pressure when the unit is operating at low load. Meanwhile, the back-pressure turbine operates independently of the steam turbine, avoiding potential safety risks to the last-stage blades of the main unit from a system architecture perspective. During the heat release process, the waste heat from the molten salt is used to heat the feedwater and condensate in stages through molten salt feedwater heat exchangers and molten salt condensate heat exchangers, replacing part of the regenerative extraction steam. This allows more steam to expand and do work in the low-pressure cylinder, reducing unit heat consumption while improving cycle efficiency, thereby improving the ability to recover retrofit costs. This application integrates a novel peak-shaving and steam supply coordination scheme that combines electrically heated molten salt thermal storage with the cascade utilization of main steam via the back-pressure turbine. By converting electrical energy into molten salt thermal energy for storage when the load is high, and releasing the thermal energy and coupling it to the back-pressure turbine to do work when the load is low, it is possible to supply stable industrial steam parameters while significantly reducing power generation output. This breaks through the "heat-driven power generation" operation limitation and has the advantages of low investment cost, high energy efficiency, and guaranteed main unit safety. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of the industrial steam supply and peak shaving system based on the coupling of molten salt thermal storage and back pressure turbine in this invention. In the diagram: 1. High-temperature molten salt tank; 2. Low-temperature molten salt tank; 3. Molten salt electric heater; 4. Molten salt steam heat exchanger; 5. Molten salt feedwater heat exchanger; 6. Molten salt condensate heat exchanger; 7. Molten salt pump; 8. Back pressure machine; 9. Back pressure machine generator; 10. Main steam pipeline; 11. Main steam extraction pipeline. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] The purpose of this invention is to provide an industrial steam supply peak-shaving system and method based on molten salt thermal storage coupled with a back-pressure turbine, so as to solve the problems existing in the prior art.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The industrial steam supply and peak-shaving system based on the coupling of molten salt thermal storage and back pressure turbine in this embodiment, such as Figure 1 As shown, it includes a molten salt thermal storage subsystem and a back pressure generator electronic system; The molten salt thermal storage subsystem includes a high-temperature molten salt tank 1, a low-temperature molten salt tank 2, a molten salt electric heater 3, a molten salt steam heat exchanger 4, a molten salt feedwater heat exchanger 5, and a molten salt condensate heat exchanger 6. The low-temperature molten salt tank 2, the molten salt electric heater 3, and the high-temperature molten salt tank 1 form a thermal storage route. The outlet of the low-temperature molten salt tank 2 is connected to the molten salt inlet of the molten salt electric heater 3 via a molten salt pump 7, and the molten salt outlet of the molten salt electric heater 3 is connected to the inlet of the high-temperature molten salt tank 1. The high-temperature molten salt tank 1, molten salt… Steam heat exchanger 4, molten salt feedwater heat exchanger 5, molten salt condensate heat exchanger 6, and low-temperature molten salt tank 2 form a heat release route. The outlet of high-temperature molten salt tank 1 is connected to the molten salt inlet of molten salt steam heat exchanger 4, the molten salt outlet of molten salt steam heat exchanger 4 is connected to the molten salt inlet of molten salt feedwater heat exchanger 5, the molten salt outlet of molten salt feedwater heat exchanger 5 is connected to the molten salt inlet of molten salt condensate heat exchanger 6, and the molten salt outlet of molten salt condensate heat exchanger 6 is connected to the inlet of low-temperature molten salt tank 2. The back pressure generator 8 electronic system includes a back pressure generator 8 and a back pressure generator 9; the steam inlet of the back pressure generator 8 is connected to the main steam pipeline 10 in front of the high pressure cylinder of the steam turbine through the main steam extraction pipeline 11, and the steam outlet of the back pressure generator 8 is connected to the steam inlet of the molten salt steam heat exchanger 4; the back pressure generator 8 and the back pressure generator 9 are connected by a drive.

[0019] In some implementations, the molten salt used in the molten salt thermal storage subsystem is a binary nitrate with an operating temperature range of 290℃ to 565℃. This temperature range can be well matched with the temperature parameters of the power plant's reheat steam and feedwater, and it has comprehensive advantages such as moderate melting point, good thermal stability, low corrosivity, and relatively low cost.

[0020] In some implementations, the back pressure unit 8 is selected based on the thermal boundary of the system under different operating conditions. A pressure reducing valve is installed before the steam inlet to adjust the steam inlet pressure of the back pressure unit 8 according to the main steam pressure under different load conditions. The exhaust pressure matches the industrial steam supply pressure demand, and the steam flow rate matches the industrial steam supply flow rate demand.

[0021] In some implementations, the back pressure unit 8 is selected based on the thermal boundary of the system under different operating conditions. A pressure reducing valve is installed before the steam inlet to adjust the steam inlet pressure of the back pressure unit 8 according to the main steam pressure under different load conditions. The exhaust pressure matches the industrial steam supply pressure demand, and the steam flow rate matches the industrial steam supply flow rate demand.

[0022] In some implementations, the molten salt electric heater 3 utilizes electrical energy from the generator or plant power supply, directly reducing the unit's net output power, which is equivalent to creating additional peak-shaving capacity on top of the original load, resulting in a more significant peak-shaving effect.

[0023] Based on the above-mentioned industrial steam supply peak shaving system coupled with molten salt thermal storage and back pressure turbine 8, this embodiment also provides an industrial steam supply peak shaving system coupled with molten salt thermal storage and back pressure turbine 8, including thermal storage mode and thermal release mode. The thermal storage mode is carried out when the unit's electrical load is greater than the grid load demand: the low-temperature molten salt in the low-temperature molten salt tank 2 is sent to the molten salt electric heater 3, and the low-temperature molten salt is heated into high-temperature molten salt by the molten salt electric heater 3 and stored in the high-temperature molten salt tank 1. At the same time, steam is drawn from the heat reheat pipeline to supply industrial steam to the outside. The heat release mode is implemented when the power grid requires the unit to perform deep peak shaving to low load: main steam is drawn from the main steam pipeline 10 and sent to the back pressure turbine 8 to do work, driving the back pressure turbine generator 9 to generate electricity. The exhaust steam from the back pressure turbine 8 is sent to the molten salt steam heat exchanger 4 to exchange heat with the high-temperature molten salt from the high-temperature molten salt tank 1. After being heated to the rated parameters, it is supplied to the outside as industrial steam. The molten salt after exchanging heat with the steam flows through the molten salt feedwater heat exchanger 5 and the molten salt condensate heat exchanger 6 in sequence to heat the feedwater and condensate respectively, and finally returns to the low-temperature molten salt tank 2.

[0024] In some implementations, the molten salt retains residual heat after heating the exhaust steam of the back-pressure turbine 8. This residual heat is used to heat the feedwater and condensate through the molten salt feedwater heat exchanger 5 and the molten salt condensate heat exchanger 6, replacing some of the steam that would otherwise need to be extracted from the turbine. This allows more steam to enter the low-pressure cylinder to expand and perform work, thereby improving the overall unit's cycle efficiency under low load and reducing heat consumption. In some implementations, by controlling the main steam extraction flow rate and the high-temperature molten salt flow rate, the unit load can be reduced to below 30% of the rated load while maintaining stable industrial steam supply parameters.

[0025] This embodiment takes a 1000MW ultra-supercritical heating unit in a power plant as an example. Its industrial steam supply parameters are required to be 4.25MPa, 475℃, and a maximum of 600t / h.

[0026] The core of this invention lies in the specific process flow of the heat release stage. Through a synergistic mechanism of "primary steam energy cascade utilization + molten salt quality improvement + deep waste heat recovery," it achieves efficient and stable steam supply under deep peak shaving. The specific steps are as follows: 1) Cascaded Utilization of Main Steam Energy: A first regulating valve is installed on the main steam pipeline 10 between the boiler and the high-pressure cylinder inlet of the turbine. When the unit responds to the grid dispatch command and enters a deep peak-shaving state (such as when the load drops below 65% THA), the control system first gradually closes the turbine high-pressure cylinder inlet regulating valve, and at the same time opens the first regulating valve on the main steam pipeline 10. At this time, the main steam with a pressure of approximately 15-19 MPa (corresponding to a temperature of 590-610℃) does not all enter the high-pressure cylinder, but is partially diverted into the main steam extraction pipeline according to the steam supply flow requirement (approximately 600 t / h).

[0027] A pressure reducing valve is installed on the main steam pipeline 10 to precisely regulate the main steam pressure to the design inlet pressure of the back pressure compressor 8 (approximately 11.7 MPa). The steam then enters the back pressure compressor 8. Within the back pressure compressor 8, the steam expands and performs work, driving the back pressure compressor generator 9 to generate electricity, converting the internal energy of the high-grade steam into electrical energy, with an output power of approximately 47 MW. The steam is depressurized in the back pressure compressor 8 to 4.25 MPa, matching the industrial steam supply pressure, but its temperature drops to approximately 380°C after performing work.

[0028] 2) Molten Salt Quality Improvement: The exhaust port of the back pressure unit 8 is connected to the first steam pipeline, which is equipped with a flow regulating valve to control the steam flow rate entering the molten salt steam heat exchanger 4. The steam flow rate is adjusted to the design value (approximately 600 t / h) by the flow regulating valve, and the steam enters the cold side inlet of the molten salt steam heat exchanger 4.

[0029] Meanwhile, a second regulating valve (i.e., a high-temperature molten salt flow regulating valve) is installed on the outlet pipe of the high-temperature molten salt tank 1. The high-temperature molten salt flow rate is regulated by the second regulating valve, and the high-temperature molten salt with a temperature of about 550-565℃ is transported to the hot side inlet of the molten salt steam heat exchanger 4.

[0030] In the molten salt steam heat exchanger 4, steam and molten salt exchange heat countercurrently. The steam is reheated to the industrial steam supply requirement of 475-480°C, and then supplied to the outside world as industrial steam through the steam supply header (S2). The temperature of the molten salt after heating drops to about 300-330°C.

[0031] 3) Deep recovery of molten salt waste heat: The medium-temperature molten salt (approximately 300-330℃) flowing from the cold side outlet of the molten salt steam heat exchanger 4 flows sequentially through the molten salt feedwater heat exchanger 5 and the molten salt condensate heat exchanger 6 via molten salt pipes. In the molten salt feedwater heat exchanger 5, the molten salt exchanges heat with the feedwater from the high-pressure heater system, heating the feedwater from 140-160℃ to 190-210℃. This process replaces the portion of reheated steam that originally needed to be extracted from the intermediate-pressure cylinder of the turbine, allowing more steam to continue expanding and doing work in the intermediate and low-pressure cylinders of the turbine.

[0032] Subsequently, the molten salt enters the molten salt condensate heat exchanger 6, where it exchanges heat with the condensate from the condensate system, heating the condensate from approximately 35-45°C to approximately 85-95°C. This process replaces the portion of the regenerated steam (pressure 0.3-0.8 MPa, temperature 200-300°C) that originally needed to be drawn from the turbine's low-pressure cylinder, further increasing the flow rate through the low-pressure cylinder.

[0033] Through the two-stage waste heat recovery process described above, the regenerated steam is used to continue expanding and generating electricity within the turbine, thereby significantly improving the unit's cycle efficiency under low load and reducing power generation heat consumption. After completing the cascade heat release, the molten salt temperature drops to 280-300℃ and finally returns to the low-temperature molten salt tank 2, completing the entire heat release cycle.

[0034] Through the above-mentioned coordinated control, the system can flexibly adjust the unit load within the range of 300MW to 400MW, while keeping the industrial steam supply parameters stable within the qualified range of 475℃±5℃, 4.25MPa±0.1MPa, and flow rate of 600t / h±10t / h.

[0035] The molten salt used in the molten salt thermal storage subsystem is a binary nitrate, with an operating temperature range of 290℃ to 565℃, which can well match the temperature parameters of the power plant's reheat steam and feedwater.

[0036] The selection of the back pressure turbine 8 in this embodiment is determined based on the boundary conditions of the aforementioned heat release process. The main steam pressure (approximately 11.7 MPa) at the lowest operating load (30% THA) is used as the design benchmark for the inlet steam pressure of the back pressure turbine 8, and a steam flow rate of 600 t / h and an exhaust steam pressure of 4.25 MPa are matched. Simultaneously, a pressure reducing valve is installed before the back pressure turbine 8 to accommodate changes in main steam pressure under different loads such as 50% THA and 40% THA, ensuring that the back pressure turbine 8 can operate safely and stably under different operating conditions.

[0037] In this embodiment, when the unit is operating at a load higher than 75% THA and the power grid requires the unit to reduce the load, the system activates the thermal storage mode.

[0038] The thermal storage process specifically includes: (1) starting the low-temperature molten salt pump 7, controlling the molten salt flow rate through the third regulating valve, and releasing the molten salt in the low-temperature molten salt tank 2 (approximately 290°C) into the molten salt electric heater 3. (2) using electrical energy from the generator or plant power supply, the electric heater uniformly heats the molten salt to the target temperature (565°C in this embodiment). (3) the heated high-temperature molten salt is transported to the high-temperature molten salt tank 1 for storage via the fourth regulating valve. During the thermal storage stage, the unit still draws steam from the heat reheat pipeline to supply industrial steam.

[0039] In this embodiment, when the power grid requires the unit to perform deep peak shaving to below 65% THA load, the system switches to heat release mode. The unit no longer extracts steam from the heat source, but instead switches to the aforementioned core heat release process. By controlling the main steam extraction rate (e.g., 500-600 t / h) and the high-temperature molten salt flow rate, the unit's power generation capacity is reduced to 400MW or even 300MW, while simultaneously providing a stable supply of industrial steam at 475℃.

[0040] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An industrial steam supply and peak-shaving system based on molten salt thermal storage coupled with a back-pressure turbine, characterized in that: This includes the molten salt thermal storage subsystem and the back pressure generator electronic system; The molten salt thermal storage subsystem includes a high-temperature molten salt tank, a low-temperature molten salt tank, a molten salt electric heater, a molten salt steam heat exchanger, a molten salt feedwater heat exchanger, and a molten salt condensate heat exchanger. The low-temperature molten salt tank, the molten salt electric heater, and the high-temperature molten salt tank form a thermal storage route. The outlet of the low-temperature molten salt tank is connected to the molten salt inlet of the molten salt electric heater via a molten salt pump, and the molten salt outlet of the molten salt electric heater is connected to the inlet of the high-temperature molten salt tank. The high-temperature molten salt tank, the molten salt steam heat exchanger, the molten salt feedwater heat exchanger, the molten salt condensate heat exchanger, and the low-temperature molten salt tank form a heat release route. The outlet of the high-temperature molten salt tank is connected to the molten salt inlet of the molten salt steam heat exchanger, the molten salt outlet of the molten salt steam heat exchanger is connected to the molten salt inlet of the molten salt feedwater heat exchanger, the molten salt outlet of the molten salt feedwater heat exchanger is connected to the molten salt inlet of the molten salt condensate heat exchanger, and the molten salt outlet of the molten salt condensate heat exchanger is connected to the inlet of the low-temperature molten salt tank. The back pressure generator power system includes a back pressure generator and a back pressure generator; the steam inlet of the back pressure generator is connected to the main steam pipeline in front of the high-pressure cylinder of the steam turbine through the main steam extraction pipeline, and the steam outlet of the back pressure generator is connected to the steam inlet of the molten salt steam heat exchanger; the back pressure generator and the back pressure generator are connected by a drive.

2. The industrial steam supply and peak-shaving system based on molten salt thermal storage and back-pressure turbine coupling as described in claim 1, characterized in that: The molten salt used in the molten salt thermal storage subsystem is a binary nitrate, with an operating temperature range of 290℃ to 565℃.

3. The industrial steam supply and peak-shaving system based on molten salt thermal storage and back-pressure turbine coupling as described in claim 1, characterized in that: A pressure reducing valve is installed before the steam inlet of the back pressure compressor to adjust the steam inlet pressure of the back pressure compressor according to the main steam pressure under different load conditions, match the exhaust pressure to the industrial steam supply pressure demand, and match the steam flow rate to the industrial steam supply flow rate demand.

4. The industrial steam supply and peak-shaving system based on molten salt thermal storage and back-pressure turbine coupling according to claim 1, characterized in that: The molten salt electric heater uses electrical energy from a generator or plant power supply.

5. An industrial steam supply peak-shaving method based on molten salt thermal storage coupled with a back-pressure turbine, characterized in that: The industrial steam supply and peak shaving system based on molten salt thermal storage and back pressure turbine coupling according to any one of claims 1-4 includes a thermal storage mode and a thermal release mode; The thermal storage mode is carried out when the unit's electrical load is greater than the grid load demand: the low-temperature molten salt in the low-temperature molten salt tank is sent to the molten salt electric heater, and the low-temperature molten salt is heated into high-temperature molten salt and stored in the high-temperature molten salt tank by the molten salt electric heater, while steam is continuously drawn from the heat reheat pipeline to supply industrial steam to the outside. The heat release mode is implemented when the power grid requires the unit to perform deep peak shaving to low load: main steam is drawn from the main steam pipeline and sent to the back compressor to do work, driving the back compressor generator to generate electricity. The exhaust steam from the back compressor is sent to the molten salt steam heat exchanger to exchange heat with the high-temperature molten salt from the high-temperature molten salt tank. After being heated to the rated parameters, it is supplied to the outside as industrial steam. The molten salt after exchanging heat with the steam flows sequentially through the molten salt feedwater heat exchanger and the molten salt condensate heat exchanger to heat the feedwater and condensate respectively, and finally returns to the low-temperature molten salt tank.

6. The industrial steam supply peak-shaving method based on molten salt thermal storage and back-pressure turbine coupling as described in claim 5, characterized in that: The residual heat from the molten salt after heating the exhaust steam of the back pressure turbine is used to heat the feedwater and condensate through the molten salt feedwater heat exchanger and the molten salt condensate heat exchanger.

7. The industrial steam supply peak shaving method based on molten salt thermal storage and back pressure turbine coupling according to claim 5, characterized in that: By controlling the main steam extraction flow rate and the high-temperature molten salt flow rate, the unit load can be reduced to below 30% of the rated load, while maintaining stable industrial steam supply parameters.

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