Coupled molten salt energy storage coal-fired power generation system and method based on energy matching principle

Abstract

This invention discloses a coupled molten salt energy storage coal-fired power generation system and method based on the principle of energy matching. The method includes: in the heat storage stage of the coal-fired power generation unit, molten salt is heated by the latent heat of main steam and the sensible heat of reheat steam to store heat; the molten salt is stored in multiple storage tanks and divided into first-temperature molten salt, second-temperature molten salt and third-temperature molten salt according to the temperature from high to low; the third-temperature molten salt is pumped to the main steam condensing subcooling heat exchanger, absorbs the latent heat released by the main steam and is converted into second-temperature molten salt, part of which is stored in the corresponding storage tank of second-temperature molten salt, and the other part is further heated by the main steam sensible heat exchanger, the reheat steam heat exchanger and the molten salt electric heater until the temperature reaches the upper limit of the molten salt utilization range and is converted into first-temperature molten salt; in the heat release stage of the coal-fired power generation unit, steam is generated by the first-temperature molten salt and supplied externally or connected to the steam turbine to generate electricity, and the feedwater is heated by the second-temperature molten salt to release heat.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, and in particular to a coupled molten salt energy storage coal-fired power generation system and method based on the principle of energy matching. Background Technology

[0002] As the proportion of renewable energy in new power systems continues to increase, the volatility and time-varying characteristics of renewable energy are increasingly impacting the safe and stable operation of the power grid. There is an urgent need to improve the operational flexibility of the power system to mitigate the future impact of renewable energy. This places higher demands on the variable load range and rapid load change capabilities of coal-fired power generating units. New coal-fired power generating units integrating molten salt energy storage can achieve decoupling of the boiler and turbine, which is of great significance for improving the flexibility of units operating under ultra-low loads and rapid load changes.

[0003] Among various molten salt thermal storage technologies, using the condensation of main steam or hot resteam to release a large amount of latent heat to heat molten salt is a relatively ideal molten salt thermal storage technology route, which can extract the minimum steam flow rate and reduce the impact on boilers and turbines under a certain thermal storage capacity.

[0004] However, because the temperature of steam remains constant during condensation and heat release, the highest temperature of molten salt during heat absorption is lower than the steam condensation temperature. This temperature point is located in the lower middle of the usable temperature range for molten salt energy storage (taking binary molten salt as an example, the molten salt energy storage temperature range is 290-560℃). Furthermore, due to its lower pressure, the reheat steam condenses at an even lower temperature than the main steam, making this effect more pronounced. This results in the actual usable temperature range of molten salt being far smaller than the ideal temperature range. Given a fixed amount of stored heat, a large amount of molten salt is needed to absorb the heat released by steam condensation; the ratio of molten salt to steam can even reach 100:1. This not only requires huge molten salt storage tanks to hold the required amount of molten salt but also increases the overall system investment cost, negating the inherent economic viability of molten salt thermal energy storage technology. Simultaneously, only a small portion of the molten salt is utilized in the temperature range above the steam condensation temperature, wasting a significant amount of its thermal storage capacity and negating the inherent wide-temperature-range thermal storage characteristics of molten salt at atmospheric pressure. Therefore, this technical approach is not feasible in practice.

[0005] Among various molten salt exothermic pathways, the maximum temperature requirements for the molten salt differ. When heating feedwater is chosen as the exothermic pathway, the maximum temperature only needs to be higher than the outlet temperature of the heated feedwater; molten salt absorbing the heat of steam condensation can also meet this temperature requirement. However, in operating conditions where there is a need to supply steam externally or where high-temperature, high-pressure steam needs to be generated and fed into the turbine for power generation, the maximum temperature of the molten salt absorbing the heat of steam condensation cannot meet the requirements for generating high-temperature, high-pressure steam. This significantly limits the application scenarios of this technology and prevents it from contributing corresponding capabilities to the wide-load regulation and rapid load change of coal-fired units. Summary of the Invention

[0006] To address the aforementioned issues, this invention proposes a coupled molten salt energy storage coal-fired power generation system and method based on the energy matching principle. During the heat storage phase of a coal-fired power plant's low-power generation period, the latent heat of the main steam and the sensible heat of the reheat steam are fully utilized to heat the molten salt, maximizing heat storage under a given steam flow rate. To avoid excessive molten salt volume, a three-tank design is adopted, consisting of a first-temperature molten salt tank, a second-temperature molten salt tank, and a third-temperature molten salt tank. Molten salt absorbing the latent heat of the main steam is designed as second-temperature molten salt. The sensible heat of the main steam, the sensible heat of the reheat steam, and the molten salt electric heater are used to heat the molten salt, converting the second-temperature molten salt into first-temperature molten salt as much as possible, ensuring a reasonable molten salt usage range. Simultaneously, based on the energy matching principle, during the heat release phase of the coal-fired power plant, the first-temperature molten salt is used to generate first-temperature steam for external supply or to be incorporated into the turbine inlet for power generation, improving the unit's load change rate. The second-temperature molten salt is used to heat feedwater for stable heat release, reducing the amount of steam extracted from the turbine, allowing more steam to enter the turbine for power generation, thus improving the unit's power generation efficiency. In addition, the use of molten salt electric heaters to absorb the surplus electrical load other than the necessary plant power consumption ultimately achieves zero-output grid connection of the unit, which greatly expands the deep load range of the unit and leaves more room for the grid to absorb new energy power. At the same time, the unit is always on the grid and can quickly increase the load to make up for the new energy gap when encountering a sudden drop in new energy output. This truly realizes the transformation of coal-fired power generation units from the main energy source to a guaranteed energy source, a supporting energy source, and a peak-shaving energy source.

[0007] Specifically, the technical solution adopted in this invention is as follows:

[0008] A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle includes:

[0009] During the heat storage phase of the coal-fired power generation unit, molten salt is heated by the latent heat of the main steam and the sensible heat of the reheat steam to store heat. The molten salt is stored in multiple storage tanks and is divided into first-temperature molten salt, second-temperature molten salt, and third-temperature molten salt according to the temperature from high to low. The third-temperature molten salt is pumped to the main steam condensing subcooling heat exchanger, where it absorbs the latent heat released by the main steam and is converted into second-temperature molten salt. A portion of the second-temperature molten salt is stored in the corresponding storage tank, while the other portion is further heated by the main steam sensible heat exchanger, the reheat steam heat exchanger, and the molten salt electric heater until the temperature reaches the upper limit of the molten salt utilization range, and is then converted into first-temperature molten salt.

[0010] During the heat release phase of a coal-fired power generation unit, steam is generated by molten salt at the first temperature and supplied externally or incorporated into the turbine to generate electricity. The feedwater is heated by molten salt at the second temperature to release heat, reducing the amount of steam extracted from the turbine and allowing more steam to enter the turbine to generate electricity.

[0011] A coupled molten salt energy storage coal-fired power generation system based on the principle of energy matching includes a boiler, a steam turbine, a condenser, a condensate pump, a third pressure heater group, a deaerator, a feedwater pump, a first pressure heater group, a main steam sensible heat exchanger, an ejector, a main steam condensing subcooling heat exchanger, a booster pump, a reheat steam heat exchanger, a molten salt electric heater, a preheater, an evaporator, a steam drum, a superheater, a reheater, a molten salt feedwater heater, a third-temperature molten salt storage tank, a third-temperature molten salt pump, a second-temperature molten salt storage tank, a second-temperature molten salt pump, a first-temperature molten salt storage tank, and a first-temperature molten salt pump. The boiler is connected to the steam turbine, the first pressure heater group, the main steam sensible heat exchanger, the ejector, the booster pump, and the reheat steam heat exchanger. The steam turbine, condenser, and condensate pump are connected to the first pressure heater group. The water pump, the third pressure heater group, the deaerator, the feedwater pump, and the first pressure heater group are connected in sequence. The main steam sensible heat exchanger is connected to the first temperature molten salt storage tank, the second temperature molten salt storage tank, and the main steam condensing subcooling heat exchanger. The ejector is connected to the main steam sensible heat exchanger and the reheat steam heat exchanger. The main steam condensing subcooling heat exchanger, the third temperature molten salt pump, and the third temperature molten salt storage tank are connected in sequence. The preheater, evaporator, steam drum, and superheater are connected in sequence. The reheater is connected in parallel with the superheater on the molten salt side. The molten salt feedwater heater, the second temperature molten salt pump, and the second temperature molten salt storage tank are connected in sequence. The temperature values ​​of the first temperature, the second temperature, and the third temperature decrease successively, and the pressure values ​​of the first pressure, the second pressure, and the third pressure decrease successively.

[0012] Furthermore, the steam turbine includes a first pressure cylinder, a second pressure cylinder, and a third pressure cylinder. The first pressure cylinder is connected to the boiler, the second pressure cylinder is connected to the boiler, the third pressure cylinder, and the deaerator, and the third pressure cylinder is also connected to the condenser.

[0013] A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle includes:

[0014] During the lowest stable combustion load stage of the coal-fired power generation unit, molten salt is heated by the latent heat of the main steam: a portion of the main steam is extracted into the main steam sensible heat exchanger and the main steam condensing subcooling heat exchanger for sensible heat storage and condensing heat storage; after condensing and subcooling, the main steam becomes undersaturated water at the first pressure, which is then pressurized by the booster pump and returned to the boiler feedwater inlet to realize the steam-water circulation of the boiler system; another portion of the main steam that has passed through the main steam sensible heat exchanger is ejected by the ejector to generate reheated steam after sensible heat storage.

[0015] During the lowest stable combustion load stage of the coal-fired power generation unit, molten salt is heated by the sensible heat of reheat steam: a portion of the reheat steam is extracted into the reheat steam heat exchanger for sensible heat storage, a portion of the reheat steam is used as the steam source for the first pressure heater group and the deaerator, and the remaining reheat steam is injected back to the boiler cold reheat steam pipeline by the main steam after the release of sensible heat.

[0016] Furthermore, during the lowest stable combustion load stage of the coal-fired power generation unit, the residual steam generated by the boiler enters the turbine to generate electricity, so that the turbine operates at the lowest safe operating load. Except for the necessary plant power load, the remaining electrical load is absorbed by the molten salt electric heater, so that the coal-fired power generation unit can achieve zero output to the grid.

[0017] Furthermore, during the lowest stable combustion load phase of the coal-fired power generating unit, the molten salt in the third-temperature molten salt storage tank is pumped to the main steam condensing subcooling heat exchanger. After absorbing the latent heat released by the main steam, it is converted into second-temperature molten salt. Part of it is stored in the second-temperature molten salt storage tank; the other part is further heated by the main steam sensible heat exchanger, reheat steam heat exchanger and molten salt electric heater until the temperature reaches the upper limit of the molten salt utilization range, and is converted into first-temperature molten salt, which is stored in the first-temperature molten salt storage tank, thus completing the molten salt heat storage process.

[0018] A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle includes:

[0019] During the load ramp-up phase of a coal-fired power generating unit, molten salt at the first temperature releases heat through the steam generation system to heat the feedwater in the deaerator, generating steam at the first temperature. This steam then enters the inlet of the first and second pressure cylinders of the turbine to generate electricity. The feedwater in the molten salt steam generation system is taken from the deaerator, first enters the preheater to be heated by the molten salt, and then enters the evaporator in a near-saturated state to be heated by the molten salt, generating saturated steam. Steam and water separation takes place in the steam drum, and the saturated water enters the evaporator through natural circulation to regenerate saturated steam. The saturated steam then enters the superheater to be further heated by the molten salt to become superheated steam, which enters the inlet of the first pressure cylinder to generate electricity.

[0020] During the load ramp-up phase of the coal-fired power generation unit, cold reheat steam is drawn from the cold reheat steam pipeline and enters the reheater where it is heated into reheat steam by molten salt. This reheat steam then enters the inlet of the second pressure cylinder to generate electricity. Molten salt is pumped out of the first temperature molten salt storage tank by the first temperature molten salt pump and passes through the superheater, evaporator, and preheater in sequence. After transferring heat to the feedwater, it returns to the third temperature molten salt storage tank to prepare for the next cycle.

[0021] A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle includes:

[0022] During the stable load phase of the coal-fired power generation unit, the second-temperature molten salt heats part of the deaerator feedwater through the molten salt feedwater heater, reducing the steam extraction volume of each stage of the first pressure heater group, so that more steam enters the first and second pressure cylinders to generate electricity; after heat exchange, the second-temperature molten salt is converted into third-temperature molten salt and returned to the third-temperature molten salt storage tank for the next cycle.

[0023] The beneficial effects of this invention are as follows:

[0024] 1) This invention utilizes the latent heat of steam by condensing and subcooling the main steam to store heat, thus maximizing the storage of heat under a given steam flow rate.

[0025] 2) This invention, based on the principle of energy matching, designs a three-tank system. During the heat storage phase, the second-temperature molten salt absorbs a large amount of latent heat released by the steam. The sensible heat of the main steam and reheat steam, along with the molten salt electric heater, convert a portion of the second-temperature molten salt into first-temperature molten salt, fully utilizing the molten salt temperature range and optimizing the molten salt quantity configuration in the latent heat-utilizing molten salt energy storage system. During the heat release phase, the first-temperature molten salt corresponds one-to-one with the first-temperature steam, and the second-temperature molten salt corresponds one-to-one with the heating feedwater, rationally utilizing the stored heat and increasing the options for heat release technology routes.

[0026] 3) During the load ramping phase, the coal-fired generator unit of the coupled molten salt energy storage coal-fired power generation system of this invention can generate additional steam or reduce the extraction of steam at each stage through various means such as steam generation system and heating feedwater, and finally increase the flow rate of working steam in the first and second pressure cylinders of the turbine, effectively improving the load ramping rate of the unit.

[0027] 4) This invention utilizes molten salt electric heaters to absorb excess electrical loads beyond the necessary plant power. Under the condition of ensuring the minimum stable combustion load of the boiler, it achieves zero-output grid connection of the unit, greatly expanding the deep adjustment load range of the unit and leaving more space for the grid to absorb new energy power. At the same time, the unit is always in grid connection status and can quickly increase the load when encountering a sudden drop in new energy output, ensuring the safety and economy of the unit and grid operation. Attached Figure Description

[0028] Figure 1 This is a flow chart of the thermal storage process of a coupled molten salt energy storage coal-fired power generation system according to an embodiment of the present invention.

[0029] Figure 2 This is a flow chart of the heat release process of the coupled molten salt energy storage coal-fired power generation system according to an embodiment of the present invention. Detailed Implementation

[0030] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention; that is, the described embodiments are only a part of the embodiments of the invention, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] This embodiment provides a coupled molten salt energy storage coal-fired power generation method based on the energy matching principle, including:

[0032] During the heat storage phase of the coal-fired power generation unit, molten salt is heated by the latent heat of the main steam and the sensible heat of the reheat steam to store heat. The molten salt is stored in multiple storage tanks and is divided into first-temperature molten salt, second-temperature molten salt, and third-temperature molten salt according to the temperature from high to low. The third-temperature molten salt is pumped to the main steam condensing subcooling heat exchanger, where it absorbs the latent heat released by the main steam and is converted into second-temperature molten salt. A portion of the second-temperature molten salt is stored in the corresponding storage tank, while the other portion is further heated by the main steam sensible heat exchanger, the reheat steam heat exchanger, and the molten salt electric heater until the temperature reaches the upper limit of the molten salt utilization range, and is then converted into first-temperature molten salt.

[0033] During the heat release phase of a coal-fired power generation unit, steam is generated by molten salt at the first temperature and supplied externally or incorporated into the turbine to generate electricity. The feedwater is heated by molten salt at the second temperature to release heat, reducing the amount of steam extracted from the turbine and allowing more steam to enter the turbine to generate electricity.

[0034] Specifically, such as Figure 1 and Figure 2 As shown, this embodiment provides a coupled molten salt energy storage coal-fired power generation system based on the principle of energy matching, including a boiler 1, a steam turbine 2 (including a first pressure cylinder 2.1, a second pressure cylinder 2.2, and a third pressure cylinder 2.3), a condenser 3, a condensate pump 4, a third pressure heater group 5, a deaerator 6, a feedwater pump 7, a first pressure heater group 8, a main steam sensible heat exchanger 9, an ejector 10, a main steam condensing subcooling heat exchanger 11, a booster pump 12, a reheat steam heat exchanger 13, a molten salt electric heater 14, a preheater 15, an evaporator 16, a steam drum 17, a superheater 18, a reheater 19, a molten salt feedwater heater 20, a third-temperature molten salt storage tank 21, a third-temperature molten salt pump 22, a second-temperature molten salt storage tank 23, a second-temperature molten salt pump 24, a first-temperature molten salt storage tank 25, and a first-temperature molten salt pump 26. Among them, the temperature values ​​of the first temperature, the second temperature and the third temperature decrease successively, and the pressure values ​​of the first pressure, the second pressure and the third pressure decrease successively.

[0035] like Figure 1As shown, during off-peak power generation, boiler 1 operates at its lowest stable combustion load. A portion of the reheat steam is extracted and enters the reheat steam heat exchanger 13 for sensible heat storage. A small portion serves as the steam source for the first pressure heater group 8, deaerator 6, and small turbine. The remaining reheat steam, after releasing sensible heat, is ejected back to the boiler's cold reheat steam pipeline via ejector 10. Simultaneously, a portion of the main steam is extracted and enters the main steam sensible heat exchanger 9 and the main steam condensing subcooling heat exchanger 11 for sensible heat storage and condensing heat storage. After condensing and subcooling, the main steam becomes first-pressure undersaturated water, which is then pressurized by booster pump 12 and returned to the boiler feedwater inlet, achieving steam-water circulation in the boiler system. Another portion, after passing through the main steam sensible heat exchanger, is ejected as reheat steam after sensible heat storage. The surplus steam generated by boiler 1 enters turbine 2 to generate electricity. Except for necessary plant power loads, the remaining electrical load is absorbed by molten salt electric heater 14, enabling the unit to achieve zero-output grid connection (without being disconnected from the grid, possessing the ability to increase load at any time).

[0036] In this process, the molten salt in the third-temperature molten salt storage tank 21 is pumped by the third-temperature molten salt pump 22 to the main steam condensing subcooling heat exchanger 11 to absorb the latent heat released by the main steam and become second-temperature molten salt, which is then stored in the second-temperature molten salt storage tank 23. Part of the second-temperature molten salt is further heated by the main steam sensible heat exchanger 9, the reheat steam heat exchanger 13, and the molten salt electric heater 14 until the temperature reaches the upper limit of the molten salt utilization range (for binary salts, the upper limit of the temperature range is 560℃), becoming first-temperature molten salt, which is then stored in the first-temperature molten salt storage tank 25, completing the molten salt heat storage process.

[0037] like Figure 2As shown, during peak power generation (load increase) phases, the coal-fired power generating unit releases heat through the steam generation system using molten salt at a first temperature to heat the feedwater in the deaerator 6, generating steam at a first temperature and first pressure. This steam then heats the extracted steam in the cooling pipeline, making it steam at a second pressure and a first temperature. This steam then enters the inlet of the first pressure cylinder 2.1 and the second pressure cylinder 2.2 of the turbine 2 to generate electricity. This process helps the unit achieve rapid load changes over a wide load range, improving the load change rate and power generation efficiency. The feedwater in the molten salt steam generation system, taken from the deaerator 6, first enters the preheater 15 and is heated by molten salt. It then enters the evaporator 16 in a near-saturated state to be heated by molten salt, generating saturated steam. Steam-water separation occurs in the steam drum 17, and the saturated water recirculates back into the evaporator 16 to regenerate saturated steam. This saturated steam then enters the superheater 18 and is further heated by molten salt to become superheated steam, which is then fed into the inlet of the first pressure cylinder 2.1 to generate electricity. Simultaneously, cold reheat steam is drawn from the cold reheat steam pipeline and enters the reheater 19, where it is heated into reheat steam by molten salt and then fed into the inlet of the second pressure cylinder 2.2 to generate electricity. Molten salt is pumped from the first temperature molten salt storage tank 25 by the first temperature molten salt pump 26, passing sequentially through the superheater 18 (reheater 19), evaporator 16, and preheater 15, transferring heat to the feedwater before returning to the third temperature molten salt storage tank 21, ready for the next cycle.

[0038] During the stable load phase of the coal-fired power generation unit, molten salt at a second temperature heats the feedwater in part of the deaerator 6 via molten salt feedwater heater 20, reducing the amount of steam extracted at each stage of the first pressure heater group 8. This allows more steam to enter the first pressure cylinder 2.1 and the second pressure cylinder 2.2 to perform work, improving power generation efficiency. After heat exchange, the molten salt at the second temperature becomes molten salt at a third temperature and returns to the third temperature molten salt storage tank 21 for the next cycle. Preferably, this heat release route can also be carried out simultaneously with the molten salt steam generation system during the load increase phase. On the one hand, the steam generation system generates steam, and on the other hand, it heats the feedwater, reducing the amount of steam extracted at each stage, thus jointly increasing the amount of steam entering the cylinders to perform work and assisting in increasing the load change rate.

[0039] In summary, the coupled molten salt energy storage coal-fired power generation system and method based on the energy matching principle in this embodiment has the following characteristics:

[0040] 1. A three-tank system designed based on the principle of energy matching, wherein the second-temperature molten salt mainly absorbs the latent heat released by the condensation and subcooling of the steam generated by the boiler, and the first-temperature molten salt absorbs the sensible heat of the steam generated by the boiler and the heat generated by the molten salt electric heater consuming the remaining electrical load.

[0041] 2. Various molten salt energy storage and heat release technology routes designed based on the principle of energy matching include: molten salt at the first temperature enters the steam generation system to generate steam at the first temperature for external supply or to be connected to the turbine inlet to generate electricity; molten salt at the second temperature heats part of the feedwater to reduce the extraction of steam at each stage of the turbine and increase the load increase rate, etc.

[0042] 3. By utilizing various molten salt steam heat exchangers and molten salt electric heaters, the boiler is kept at the minimum stable combustion load, the steam turbine is kept at a safe operating load, and the unit achieves zero-output grid connection, thereby expanding the unit's variable load range and absorbing new energy power.

[0043] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for coupled molten salt energy storage and coal-fired power generation based on the principle of energy matching, characterized in that, include: During the heat storage phase of the coal-fired power generation unit, molten salt is heated by the latent heat of the main steam and the sensible heat of the reheat steam to store heat. The molten salt is stored in multiple storage tanks and is divided into first-temperature molten salt, second-temperature molten salt, and third-temperature molten salt according to the temperature from high to low. The third-temperature molten salt is pumped to the main steam condensing subcooling heat exchanger, where it absorbs the latent heat released by the main steam and is converted into second-temperature molten salt. A portion of the second-temperature molten salt is stored in the corresponding storage tank, while the other portion is further heated by the main steam sensible heat exchanger, the reheat steam heat exchanger, and the molten salt electric heater until the temperature reaches the upper limit of the molten salt utilization range, and is then converted into first-temperature molten salt. During the heat release phase of a coal-fired power generation unit, steam is generated by molten salt at the first temperature and supplied externally or incorporated into the turbine to generate electricity. The feedwater is heated by molten salt at the second temperature to release heat, reducing the amount of steam extracted from the turbine and allowing more steam to enter the turbine to generate electricity.

2. A coupled molten salt energy storage coal-fired power generation system based on the principle of energy matching, characterized in that, This includes a boiler, steam turbine, condenser, condensate pump, third pressure heater group, deaerator, feedwater pump, first pressure heater group, main steam sensible heat exchanger, ejector, main steam condensing subcooling heat exchanger, booster pump, reheat steam heat exchanger, molten salt electric heater, preheater, evaporator, steam drum, superheater, reheater, molten salt feedwater heater, third-temperature molten salt storage tank, third-temperature molten salt pump, second-temperature molten salt storage tank, second-temperature molten salt pump, first-temperature molten salt storage tank, and first-temperature molten salt pump, wherein: The boiler is connected to a steam turbine, a first pressure heater group, a main steam sensible heat exchanger, an ejector, a booster water pump, and a reheat steam heat exchanger. The steam turbine, condenser, condensate pump, third pressure heater group, deaerator, feedwater pump, and first pressure heater group are connected sequentially. The main steam sensible heat exchanger is connected to a first-temperature molten salt storage tank, a second-temperature molten salt storage tank, and a main steam condensing subcooling heat exchanger. The ejector is connected to both the main steam sensible heat exchanger and the reheat steam heat exchanger. The condensing subcooling heat exchanger, the third-temperature molten salt pump, and the third-temperature molten salt storage tank are connected in sequence. The preheater, evaporator, steam drum, and superheater are connected in sequence. The reheater is connected in parallel with the superheater on the molten salt side. The molten salt feedwater heater, the second-temperature molten salt pump, and the second-temperature molten salt storage tank are connected in sequence. The temperature values ​​of the first, second, and third temperatures decrease sequentially, and the pressure values ​​of the first, second, and third pressures decrease sequentially. The main steam condensing subcooling heat exchanger is connected to the second-temperature molten salt storage tank.

3. The coupled molten salt energy storage coal-fired power generation system based on the energy matching principle according to claim 2, characterized in that, The steam turbine includes a first pressure cylinder, a second pressure cylinder, and a third pressure cylinder. The first pressure cylinder is connected to the boiler, the second pressure cylinder is connected to the boiler, the third pressure cylinder, and the deaerator, and the third pressure cylinder is also connected to the condenser.

4. A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle, applied to the coupled molten salt energy storage coal-fired power generation system as described in claim 2, characterized in that, include: During the lowest stable combustion load stage of the coal-fired power generation unit, molten salt is heated by the latent heat of the main steam: a portion of the main steam is extracted into the main steam sensible heat exchanger and the main steam condensing subcooling heat exchanger for sensible heat storage and condensing heat storage; after condensing and subcooling, the main steam becomes undersaturated water at the first pressure, which is then pressurized by the booster pump and returned to the boiler feedwater inlet to realize the steam-water circulation of the boiler system; another portion of the main steam that has passed through the main steam sensible heat exchanger is ejected by the ejector to generate reheated steam after sensible heat storage.

5. A method for coupled molten salt energy storage and coal-fired power generation based on the energy matching principle according to claim 4, characterized in that, Also includes: During the lowest stable combustion load stage of the coal-fired power generation unit, molten salt is heated by the sensible heat of reheat steam: a portion of the reheat steam is extracted into the reheat steam heat exchanger for sensible heat storage, a portion of the reheat steam is used as the steam source for the first pressure heater group and the deaerator, and the remaining reheat steam is injected back to the boiler cold reheat steam pipeline by the main steam after the release of sensible heat.

6. The method for coupled molten salt energy storage and coal-fired power generation based on the energy matching principle according to claim 5, characterized in that, During the lowest stable combustion load stage of a coal-fired power generation unit, the boiler generates residual steam, which then enters the turbine to generate electricity, allowing the turbine to operate at the lowest safe operating load. Except for the necessary plant power load, the remaining electrical load is absorbed by the molten salt electric heater, enabling the coal-fired power generation unit to achieve zero output to the grid.

7. A method for coupled molten salt energy storage and coal-fired power generation based on the energy matching principle according to claim 5, characterized in that, During the lowest stable combustion load phase of the coal-fired power generating unit, the molten salt in the third-temperature molten salt storage tank is pumped to the main steam condensing subcooling heat exchanger. After absorbing the latent heat released by the main steam, it is converted into second-temperature molten salt. Part of it is stored in the second-temperature molten salt storage tank; the other part is further heated by the main steam sensible heat exchanger, reheat steam heat exchanger and molten salt electric heater until the temperature reaches the upper limit of the molten salt utilization range, and is converted into first-temperature molten salt, which is stored in the first-temperature molten salt storage tank, thus completing the molten salt heat storage process.

8. A method for coupled molten salt energy storage and coal-fired power generation based on the principle of energy matching, applied to the coupled molten salt energy storage and coal-fired power generation system as described in claim 3, characterized in that, include: During the load ramp-up phase of a coal-fired power generating unit, molten salt at the first temperature releases heat through the steam generation system to heat the feedwater in the deaerator, generating steam at the first temperature. This steam then enters the inlet of the first and second pressure cylinders of the turbine to generate electricity. The feedwater in the molten salt steam generation system is taken from the deaerator, first enters the preheater to be heated by the molten salt, and then enters the evaporator in a near-saturated state to be heated by the molten salt, generating saturated steam. Steam and water separation takes place in the steam drum, and the saturated water enters the evaporator through natural circulation to regenerate saturated steam. The saturated steam then enters the superheater to be further heated by the molten salt to become superheated steam, which enters the inlet of the first pressure cylinder to generate electricity.

9. A method for coupled molten salt energy storage and coal-fired power generation based on the energy matching principle according to claim 8, characterized in that, Also includes: During the load ramp-up phase of the coal-fired power generation unit, cold reheat steam is drawn from the cold reheat steam pipeline and enters the reheater where it is heated into reheat steam by molten salt. This reheat steam then enters the inlet of the second pressure cylinder to generate electricity. Molten salt is pumped out of the first temperature molten salt storage tank by the first temperature molten salt pump and passes through the superheater, evaporator, and preheater in sequence. After transferring heat to the feedwater, it returns to the third temperature molten salt storage tank to prepare for the next cycle.

10. A method for coupled molten salt energy storage and coal-fired power generation based on the principle of energy matching, applied to the coupled molten salt energy storage and coal-fired power generation system as described in claim 3, characterized in that, include: During the stable load phase of the coal-fired power generation unit, the second-temperature molten salt heats part of the deaerator feedwater through the molten salt feedwater heater, reducing the steam extraction volume of each stage of the first pressure heater group, so that more steam enters the first and second pressure cylinders to generate electricity; after heat exchange, the second-temperature molten salt is converted into third-temperature molten salt and returned to the third-temperature molten salt storage tank for the next cycle.

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