Coupling fused salt energy storage coal-fired power generation system and method based on energy matching principle

Abstract

The invention discloses a coupling fused salt energy storage coal-fired power generation system and method based on an energy matching principle, and the method comprises the steps: in a heat storage stage of a coal-fired power generation unit, heating fused salt through latent heat of main steam and sensible heat of reheat steam, and storing heat; the fused salt is stored in a plurality of storage tanks and is divided into first-temperature fused salt, second-temperature fused salt and third-temperature fused salt according to the temperature from high to low; the third-temperature fused salt is pumped to a main steam condensation supercooling heat exchanger and is converted into second-temperature fused salt after absorbing main steam and releasing latent heat, one part of the third-temperature fused salt is stored in a storage tank corresponding to the second-temperature fused salt, and the other part of the third-temperature fused salt is further heated through a main steam sensible heat exchanger, a reheat steam heat exchanger and a fused salt electric heater; when the temperature reaches the upper limit of the fused salt utilization interval, converting into first-temperature fused salt; and in the heat release stage of the coal-fired power generation unit, steam is generated through the first-temperature fused salt to be externally supplied or merged into a steam turbine to do work for power generation, and water is heated through the second-temperature fused salt to release heat.

Description

Technical Field

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

[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. It is urgent to improve the operational flexibility of the power system to mitigate the impact of future renewable energy. This places higher demands on the load range and rapid load change capabilities of coal-fired power generation units. New coal-fired power units with integrated molten salt energy storage can achieve machine-boiler decoupling, which is of great significance to improving the unit's ultra-low load operation flexibility and rapid load change operation flexibility.

[0003] Among various molten salt heat storage technology routes, using main steam or hot resteam condensation to release a large amount of latent heat to heat molten salt can extract the least steam flow while keeping the heat storage capacity constant, thereby reducing the impact on boilers and steam turbines. It is a more ideal molten salt heat storage technology route.

[0004] However, since the temperature of steam remains unchanged during the condensation and heat release process, the maximum temperature of the molten salt during the heat absorption process is lower than the steam condensation temperature. This temperature point is located in the lower middle position of the molten salt energy storage available range (taking binary molten salt as an example, the molten salt energy storage temperature range is 290-560℃). Due to the low pressure of hot re-steam, the steam condensation temperature is lower than the main steam condensation temperature. The effect is more obvious, making the actual temperature utilization range of the molten salt far less than the ideal temperature utilization range. Under certain heat storage conditions, a large amount of molten salt is required to absorb the heat released by steam condensation. The ratio of molten salt to steam may even reach 100:1. This not only requires a huge molten salt storage tank to hold the required molten salt, but also increases the investment cost of the entire system, losing the economic efficiency of molten salt heat storage in energy storage technology. At the same time, only a very small part of the molten salt is used in the range above the steam condensation temperature, and a large amount of molten salt heat storage space is wasted, which negates the normal pressure and wide temperature range heat storage characteristics of the molten salt itself. This makes this technical route not feasible in actual implementation.

[0005] Among the various molten salt heat release routes, the maximum temperature requirements for molten salt are different. When heating feed water is selected as the heat release route, the maximum temperature only needs to be higher than the outlet temperature of the heated feed water. Molten salt that absorbs the heat of steam condensation can also meet this temperature requirement. However, under conditions where there is a demand for external steam supply or the need to generate high-temperature and high-pressure steam to be incorporated into a steam turbine for power generation, the maximum temperature of the molten salt that absorbs the heat of steam condensation cannot meet the demand for generating high-temperature and high-pressure steam. This greatly limits the application scenarios of this technology, and it cannot contribute corresponding capabilities to the wide load regulation and rapid load change of coal-fired units. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a coupled molten salt energy storage coal-fired power generation system and method based on the energy matching principle. In the heat storage stage of the coal-fired power generation unit at the low power generation valley, the main steam latent heat and the reheated steam sensible heat are fully utilized to heat the molten salt, and the maximum heat is stored under the condition of a constant steam flow. In order to avoid the problem of excessive molten salt, the molten salt storage tank adopts a three-tank design, which is divided into a first temperature molten salt storage tank, a second temperature molten salt storage tank and a third temperature molten salt storage tank. The molten salt that absorbs the latent heat of the main steam is designed as a second temperature molten salt; the main steam sensible heat, the reheated steam sensible heat and the molten salt electric heater are used for heating, and the second temperature molten salt is converted into the first temperature molten salt as much as possible, so that the molten salt usage is in a more reasonable range. At the same time, based on the energy matching principle, in the heat release stage of the coal-fired power generation unit, the first temperature molten salt is used to generate the first temperature steam for external supply or merged into the turbine inlet for power generation, thereby improving the unit's variable load rate; the second temperature molten salt is used to heat the feed water, perform stable heat release, reduce the steam extraction of the turbine, so that more steam enters the turbine for power generation, and improves the power generation efficiency of the unit. In addition, molten salt electric heaters are used to absorb the remaining electrical load except for the necessary factory electricity, and ultimately the unit can be connected to the grid with zero output, which greatly widens the unit's deep load adjustment range and leaves more space for the grid to absorb new energy electricity. At the same time, the unit can remain online at any time and can quickly increase the load when encountering a sudden drop in new energy output to make up for the new energy gap, truly realizing the transformation of coal-fired power generation units from the main energy source to guaranteed energy, supporting energy and peak-shaving energy.

[0007] Specifically, the technical solution adopted by the present invention is as follows:

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

[0009] In the heat storage stage of the coal-fired power generation unit, the molten salt is heated by the latent heat of the main steam and the sensible heat of the reheated 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 condensation subcooling heat exchanger, and is converted into the second temperature molten salt after absorbing the latent heat released by the main steam, a part of which is stored in the storage tank corresponding to the second temperature molten salt, and the other part is further heated by the main steam sensible heat exchanger, the reheated steam heat exchanger and the molten salt electric heater, and the temperature reaches the upper limit of the molten salt utilization range, and is converted into the first temperature molten salt;

[0010] During the heat release stage of the coal-fired power generation unit, the first temperature molten salt is used to generate steam for external supply or to be incorporated into the steam turbine for power generation, and the second temperature molten salt is used to heat the feed water for heat release, thereby reducing the steam extraction amount of the steam turbine and allowing more steam to enter the steam turbine for power generation.

[0011] A coupled molten salt energy storage coal-fired power generation system based on the energy matching principle, comprising a boiler, a steam turbine, a condenser, a condensate pump, a third pressure heater group, a deaerator, a feed water pump, a first pressure heater group, a main steam sensible heat exchanger, an ejector, a main steam condensation subcooling heat exchanger, a booster water 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 feed water 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, wherein the boiler is respectively connected to the steam turbine, the first pressure heater group, the main steam sensible heat exchanger, the ejector, the booster water pump and the reheat steam heat exchanger, and the steam turbine, the condenser, the condenser, the The water pump, the third pressure heater group, the deaerator, the feed water pump and the first pressure heater group are connected in sequence, the main steam sensible heat exchanger is respectively connected to the first temperature molten salt storage tank, the second temperature molten salt storage tank and the main steam condensation subcooling heat exchanger, the ejector is respectively connected to the main steam sensible heat exchanger and the reheat steam heat exchanger, the main steam condensation subcooling heat exchanger, the third temperature molten salt pump and the third temperature molten salt storage tank are connected in sequence, the preheater, the evaporator, the steam drum and the superheater are connected in sequence, the reheater is connected in parallel with the superheater on the molten salt side, the molten salt feed water 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 comprises 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 respectively 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, comprising:

[0014] During the lowest steady-fire load stage of the coal-fired power generating unit, the molten salt is heated by the latent heat of the main steam: a part of the main steam is extracted into the main steam sensible heat exchanger and the main steam condensation subcooling heat exchanger for sensible heat storage and condensation heat storage; the main steam is converted into undersaturated water at the first pressure after condensation and subcooling, and is pressurized by the booster water pump and returned to the boiler feed water inlet to realize the steam-water circulation of the boiler system; the other part of the main steam that passes through the main steam sensible heat exchanger is ejected by the ejector as the reheated steam after sensible heat storage.

[0015] During the lowest steady-fire load stage of the coal-fired power generating unit, the molten salt is heated by the sensible heat of the reheated steam: a portion of the reheated steam is extracted into the reheated steam heat exchanger for sensible heat storage, a portion of the reheated steam is used as the steam source for the first pressure heater group and the deaerator, and the remaining reheated steam is ejected by the main steam after the sensible heat is released and returned to the boiler cold reheat steam pipeline.

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

[0017] Furthermore, in the lowest stable combustion load stage of the coal-fired power generation unit, the molten salt in the third temperature molten salt storage tank is pumped to the main steam condensation subcooling heat exchanger by the third temperature molten salt pump, and is converted into second temperature molten salt after absorbing the latent heat released by the main steam, a part of which is stored in the second temperature molten salt storage tank; the other part is further heated through the main steam sensible heat exchanger, the reheat steam heat exchanger and the molten salt electric heater, and 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, 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, comprising:

[0019] During the load-raising stage of the coal-fired power generating unit, the first-temperature molten salt releases heat through the steam generating system to heat the deaerator feed water, generate first-temperature steam, and enter the inlet of the first pressure cylinder and the second pressure cylinder of the steam turbine to generate power. After the feed water of the molten salt steam generating system is taken from the deaerator, it first enters the preheater to be heated by the molten salt, and then enters the evaporator in a state close to saturated water to be heated by the molten salt to generate saturated steam. Steam and water are separated in the steam drum, and the saturated water enters the evaporator through natural circulation to generate saturated steam again. The saturated steam enters the superheater and is further heated by the molten salt to become superheated steam, which is then merged into the inlet of the first pressure cylinder to generate power.

[0020] During the load-raising stage of the coal-fired power generating unit, cold reheat steam is drawn from the cold reheat steam pipeline and enters the reheater to be heated by molten salt into reheat steam, and then merged into the inlet of the second pressure cylinder to generate power; the molten salt is pumped out from the first temperature molten salt storage tank by the first temperature molten salt pump, passes through the superheater, evaporator and preheater in sequence, transfers the heat to the feed water, and then returns to the third temperature molten salt storage tank, ready for the next cycle.

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

[0022] During the stable load stage of the coal-fired power generation unit, the second temperature molten salt is used to heat part of the deaerator feed water through the molten salt feed water heater, reducing the steam extraction amount of each stage of the first pressure heater group, so that more steam can enter the first pressure cylinder and the second pressure cylinder to generate power; the second temperature molten salt after heat exchange is converted into third temperature molten salt and returns to the third temperature molten salt storage tank for the next cycle.

[0023] The beneficial effects of the present invention are:

[0024] 1) The present invention utilizes the latent heat of steam by supercooling and condensing the main steam to store heat, and can store the most heat under the condition of a certain steam flow rate.

[0025] 2) The three-tank system designed in the present invention is based on the energy matching principle. In the heat storage stage, the second temperature molten salt bears a large amount of latent heat released by steam, and the main steam sensible heat and reheated steam sensible heat and molten salt electric heater convert part of the second temperature molten salt into the first temperature molten salt, making full use of the molten salt temperature range and optimizing the configuration of the molten salt amount in the molten salt energy storage system using latent heat. In the heat release stage, the first temperature molten salt corresponds to the first temperature steam, and the second temperature molten salt corresponds to the heating feed water, which rationally utilizes the stored heat and increases the choice of heat release technology routes.

[0026] 3) During the load increase stage, the coal-fired power generation unit coupled with the molten salt energy storage coal-fired power generation system of the present invention can generate additional steam or reduce steam extraction at various stages through a steam generation system and heating feed water, thereby ultimately increasing the flow of working steam in the first and second pressure cylinders of the steam turbine, and effectively improving the load increase rate of the unit.

[0027] 4) The present invention utilizes molten salt electric heaters to absorb excess electrical loads other than necessary plant electricity, and realizes zero-output access to the grid while ensuring the minimum stable combustion load of the boiler, greatly broadening the deep adjustment load range of the unit, leaving more space for the grid to absorb new energy electricity. At the same time, the unit can remain online at any time, and can quickly increase the load when encountering a sudden drop in new energy output, thereby ensuring the safety and economy of the unit and the grid operation. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 2 It 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 DESCRIPTION

[0030] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific implementation methods of the present invention are now described. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work 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] In the heat storage stage of the coal-fired power generation unit, the molten salt is heated by the latent heat of the main steam and the sensible heat of the reheated 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 condensation subcooling heat exchanger, and is converted into the second temperature molten salt after absorbing the latent heat released by the main steam, a part of which is stored in the storage tank corresponding to the second temperature molten salt, and the other part is further heated by the main steam sensible heat exchanger, the reheated steam heat exchanger and the molten salt electric heater, and the temperature reaches the upper limit of the molten salt utilization range, and is converted into the first temperature molten salt;

[0033] During the heat release stage of the coal-fired power generation unit, the first temperature molten salt is used to generate steam for external supply or to be incorporated into the steam turbine for power generation, and the second temperature molten salt is used to heat the feed water for heat release, thereby reducing the steam extraction amount of the steam turbine and allowing more steam to enter the steam turbine for power generation.

[0034] Specifically, Figure 1 and Figure 2 As shown, this embodiment provides a coupled molten salt energy storage coal-fired power generation system based on the energy matching principle, 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 feed water pump 7, a first pressure heater group 8, a main steam sensible heat exchanger 9, an ejector 10, a main steam condensation subcooling heat exchanger 11, a booster water 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 feed water 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. 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, when the coal-fired power generation unit is in the low power generation valley, the boiler 1 operates at the lowest stable combustion load, extracts part of the reheated steam into the reheated steam heat exchanger 13 for sensible heat storage, and a small part is used as the first pressure heater group 8, the deaerator 6 and the steam source for the small machine. The remaining reheated steam is ejected by the main steam after releasing the sensible heat through the ejector 10 and returned to the boiler cold reheated steam pipeline. At the same time, a part of the main steam is extracted into the main steam sensible heat exchanger 9 and the main steam condensation subcooling heat exchanger 11 for sensible heat storage and condensation heat storage. The main steam becomes the first pressure undersaturated water after condensation and subcooling, and is pressurized by the booster water pump 12 and returned to the boiler feed water inlet to realize the steam-water circulation of the boiler system; the other part of the main steam after passing through the main steam sensible heat exchanger ejects the reheated steam after sensible heat storage. The remaining steam generated by the boiler 1 generates power after entering the steam turbine 2. Except for the necessary plant power load, the remaining power load is absorbed by the molten salt electric heater 14, so that the unit can achieve zero output access to the grid (and does not withdraw from the grid, with the ability to increase load at any time).

[0036] Among them, the molten salt in the third temperature molten salt storage tank 21 is sent to the main steam condensation subcooling heat exchanger 11 by the third temperature molten salt pump 22 to absorb the latent heat released by the main steam and become the second temperature molten salt, which is 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, and the temperature reaches the upper limit of the molten salt utilization range (taking binary salt as an example, the upper limit of the temperature range is 560°C), and becomes the first temperature molten salt, which is stored in the first temperature molten salt storage tank 25, completing the molten salt heat storage process.

[0037] like Figure 2As shown, when the coal-fired power generation unit is in the peak power generation (load increase) stage, the first temperature molten salt releases heat through the steam generation system, heats the feed water of the deaerator 6, so that it produces the first temperature and the first pressure, heats the cold pipe to extract steam, so that it becomes the first temperature and the second pressure steam, and enters the first pressure cylinder 2.1 and the second pressure cylinder 2.2 of the steam turbine 2 to generate power, which can help the unit to achieve rapid load change in a wide load range, improve the load change rate, and improve the power generation efficiency. After the feed water of the molten salt steam generation system is taken from the deaerator 6, it first enters the preheater 15 to be heated by the molten salt, and then enters the evaporator 16 in a state close to saturated water to be heated by the molten salt to generate saturated steam, and steam and water are separated in the steam drum 17. The saturated water enters the evaporator 16 through natural circulation to generate saturated steam again, and the saturated steam enters the superheater 18 to be further heated by the molten salt to become superheated steam, and is merged into the inlet of the first pressure cylinder 2.1 to generate power. At the same time, cold reheat steam is extracted from the cold reheat steam pipeline and enters the reheater 19 to be heated by molten salt to become reheat steam, and then enters the inlet of the second pressure cylinder 2.2 to generate power. The molten salt is pumped out from the first temperature molten salt storage tank 25 by the first temperature molten salt pump 26, passes through the superheater 18 (reheater 19), evaporator 16 and preheater 15 in sequence, transfers heat to the feed water, and then returns to the third temperature molten salt storage tank 21 to prepare for the next cycle.

[0038] When the coal-fired power generation unit is in the stable load stage, the second temperature molten salt heats part of the deaerator 6 feed water through the molten salt feed water heater 20, reducing the steam extraction of part of the first pressure heater group 8 at each level, so that more steam enters the first pressure cylinder 2.1 and the second pressure cylinder 2.2 to do work, thereby improving the power generation efficiency. The second temperature molten salt after heat exchange becomes the third temperature molten salt and returns to the third temperature molten salt storage tank 21 for the next cycle. Preferably, the heat release route can also be carried out simultaneously with the molten salt steam generation system during the load increase stage. On the one hand, the steam generation system generates steam, and on the other hand, it heats the feed water, reduces the steam extraction at each level, and jointly increases the amount of steam entering the cylinder to do work, thereby assisting in improving the variable load rate.

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

[0040] 1. The three-tank system is designed based on the energy matching principle, in which the second temperature molten salt mainly absorbs the latent heat released by the condensation 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. A variety of molten salt energy storage and heat release technology routes designed based on the energy matching principle, including the first temperature molten salt entering the steam generation system to generate the first temperature steam for external supply or merging into the turbine inlet to generate power; the second temperature molten salt heats part of the feed water, reduces the steam extraction of each level of the turbine and increases the load rate, etc.;

[0042] 3. Utilize various types of molten salt steam heat exchangers and molten salt electric heaters to keep the boiler at the minimum stable combustion load and the steam turbine at the safe operating load, while the unit can achieve zero output to the grid, increase the unit's variable load range, and absorb new energy electricity.

[0043] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle, characterized in that: include: In the heat storage stage of the coal-fired power generation unit, the molten salt is heated by the latent heat of the main steam and the sensible heat of the reheated 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 condensation subcooling heat exchanger, and is converted into the second temperature molten salt after absorbing the latent heat released by the main steam, a part of which is stored in the storage tank corresponding to the second temperature molten salt, and the other part is further heated by the main steam sensible heat exchanger, the reheated steam heat exchanger and the molten salt electric heater, and the temperature reaches the upper limit of the molten salt utilization range, and is converted into the first temperature molten salt; During the heat release stage of the coal-fired power generation unit, the first temperature molten salt is used to generate steam for external supply or to be incorporated into the steam turbine for power generation, and the second temperature molten salt is used to heat the feed water for heat release, thereby reducing the steam extraction amount of the steam turbine and allowing more steam to enter the steam turbine for power generation.

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

3. The coupled molten salt energy storage coal-fired power generation system based on the energy matching principle according to claim 2 is characterized in that: The steam turbine comprises a first pressure cylinder, a second pressure cylinder and a third pressure cylinder, wherein the first pressure cylinder is connected to a boiler, the second pressure cylinder is respectively connected to the boiler, the third pressure cylinder and a deaerator, and the third pressure cylinder is also connected to a 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 according to claim 2, characterized in that: include: During the lowest steady-fire load stage of the coal-fired power generating unit, the molten salt is heated by the latent heat of the main steam: a part of the main steam is extracted into the main steam sensible heat exchanger and the main steam condensation subcooling heat exchanger for sensible heat storage and condensation heat storage; the main steam is converted into undersaturated water at the first pressure after condensation and subcooling, and is pressurized by the booster water pump and returned to the boiler feed water inlet to realize the steam-water circulation of the boiler system; the other part of the main steam that passes through the main steam sensible heat exchanger is ejected by the ejector as the reheated steam after sensible heat storage.

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

6. A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle according to claim 5, characterized in that: During the lowest stable combustion load stage of the coal-fired power generating unit, the excess steam generated by the boiler enters the steam turbine to generate electricity, making the steam turbine operate at the lowest safe operating load. Except for the necessary plant power load, the remaining power load is absorbed by the molten salt electric heater, allowing the coal-fired power generating unit to achieve zero output grid access.

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

8. 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 according to claim 3, characterized in that: include: During the load-raising stage of the coal-fired power generating unit, the first-temperature molten salt releases heat through the steam generating system to heat the deaerator feed water, generate first-temperature steam, and enter the inlet of the first pressure cylinder and the second pressure cylinder of the steam turbine to generate power. After the feed water of the molten salt steam generating system is taken from the deaerator, it first enters the preheater to be heated by the molten salt, and then enters the evaporator in a state close to saturated water to be heated by the molten salt to generate saturated steam. Steam and water are separated in the steam drum, and the saturated water enters the evaporator through natural circulation to generate saturated steam again. The saturated steam enters the superheater and is further heated by the molten salt to become superheated steam, which is then merged into the inlet of the first pressure cylinder to generate power.

9. A coupled molten salt energy storage coal-fired power generation method based on the energy matching principle according to claim 8, characterized in that: Also includes: During the load-raising stage of the coal-fired power generating unit, cold reheat steam is drawn from the cold reheat steam pipeline and enters the reheater to be heated by molten salt into reheat steam, and then merged into the inlet of the second pressure cylinder to generate power; the molten salt is pumped out from the first temperature molten salt storage tank by the first temperature molten salt pump, passes through the superheater, evaporator and preheater in sequence, transfers the heat to the feed water, and then returns to the third temperature molten salt storage tank, ready for the next cycle.

10. 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 according to claim 3, characterized in that: include: During the stable load stage of the coal-fired power generation unit, the second temperature molten salt is used to heat part of the deaerator feed water through the molten salt feed water heater, reducing the steam extraction amount of each stage of the first pressure heater group, so that more steam can enter the first pressure cylinder and the second pressure cylinder to generate power; the second temperature molten salt after heat exchange is converted into third temperature molten salt and returns to the third temperature molten salt storage tank for the next cycle.

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