Low-load denitrification-deep peak shaving system based on molten salt thermal storage and its working method

Abstract

This invention discloses a low-load denitrification-deep peak-shaving system based on molten salt thermal energy storage and its operating method. The system includes a coal-fired power generation system and a molten salt thermal energy storage system. The coal-fired power generation system includes a boiler, a denitrification device, a deaerator, and an industrial steam header. The molten salt thermal energy storage system includes a first flue gas heating path, a second flue gas heating path, and a molten salt thermal energy storage path. The coal-fired power generation system provides electricity to the molten salt thermal energy storage path, high-temperature molten salt provides a heat source for the first flue gas heating path, and high-temperature steam provides a heat source for the second flue gas heating path. The high-temperature steam is obtained by heating condensate with high-temperature molten salt. This invention adds two methods of heating flue gas for energy release: high-temperature molten salt and high-temperature steam. This avoids the imbalance between the input and output energy of the molten salt thermal energy storage system when the steam demand is insufficient, and reduces the cost of the thermal energy storage molten salt and investment. This invention uses molten salt energy storage to increase the flue gas temperature, ensuring the denitrification capability of the unit during low-load operation.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, and in particular to a low-load denitrification-deep peak shaving system based on molten salt thermal storage and its operating method. Background Technology

[0002] Molten salt thermal energy storage, as a safe, reliable, and inexpensive energy storage technology, is suitable for large-scale and frequent storage and release scenarios. It can improve the frequency regulation and peak shaving performance of coal-fired power units without affecting their operating economy and lifespan, and make up for their shortcomings of low ramp rate, slow response speed, and extremely low load operation. It contributes to the transformation of coal-fired power units from the main power source to a supporting and regulating power source.

[0003] There are numerous coupling methods between molten salt thermal energy storage and coal-fired power units, primarily including two energy storage methods: extraction-based thermal energy storage and electric heating thermal energy storage; and two energy release methods: returning energy to the main unit for power generation and industrial steam supply. Among these, the coupling method of electric heating energy storage and releasing energy to supplement industrial steam supply is suitable for addressing the challenges of high-parameter steam supply, strong thermoelectric coupling, and difficulties in frequency regulation and peak shaving in coal-fired power units. However, the released energy power largely depends on the steam demand. When the steam demand is low and the unit is undergoing deep peak shaving, the thermal storage capacity increases due to the imbalance between input and output energy, increasing the system's investment cost. Furthermore, when coal-fired power units operate at extremely low loads, the minimum load is largely limited by the flue gas temperature not falling below the minimum temperature required for denitrification. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a low-load denitrification-deep peak shaving system based on molten salt thermal storage and its operating method.

[0006] On the one hand, this invention proposes a low-load denitrification-deep peak-shaving system based on molten salt thermal storage, comprising:

[0007] A coal-fired power generation system, comprising a boiler, a denitrification device, a deaerator, and an industrial steam header, wherein the boiler has a flue, the inlet of the denitrification device is connected to the outlet of the flue, and the flue is divided into a front flue and a rear flue;

[0008] A molten salt thermal energy storage system includes a first flue gas heating passage, a second flue gas heating passage, and a molten salt thermal energy storage passage. The coal-fired power generation system provides electrical energy to the molten salt thermal energy storage passage. High-temperature molten salt provides a heat source for the first flue gas heating passage, and high-temperature steam provides a heat source for the second flue gas heating passage. The high-temperature steam is obtained by heating condensate with the high-temperature molten salt.

[0009] In some embodiments, a low-temperature molten salt storage tank, a molten salt electric heater, and a high-temperature molten salt storage tank are sequentially arranged on the molten salt storage passage. The low-temperature molten salt flowing out of the outlet end of the low-temperature molten salt storage tank is heated by the molten salt electric heater and then stored in the high-temperature molten salt storage tank.

[0010] In some embodiments, the coal-fired power generation system further includes a generator and a high-voltage transformer, wherein the generator's output port is connected to the molten salt electric heater's inlet port via the high-voltage transformer.

[0011] In some embodiments, a flue gas molten salt heat exchanger is provided on the first flue gas heating passage. The hot-side inlet end of the flue gas molten salt heat exchanger is connected to the outlet end of the high-temperature molten salt heat storage tank, the hot-side outlet end of the flue gas molten salt heat exchanger is connected to the inlet end of the low-temperature molten salt heat storage tank, the cold-side inlet end of the flue gas molten salt heat exchanger is connected to the front flue of the flue, and the cold-side outlet end of the flue gas molten salt heat exchanger is connected to the rear flue of the flue.

[0012] In some embodiments, a first flue gas bypass valve is provided between the cold-side inlet end of the flue gas molten salt heat exchanger and the cold-side outlet end of the flue gas molten salt heat exchanger.

[0013] In some embodiments, a molten salt steam heat exchanger is provided between the deaerator and the industrial steam supply manifold. The hot-side inlet of the molten salt steam heat exchanger is connected to the outlet of the high-temperature molten salt storage tank, the hot-side outlet of the molten salt steam heat exchanger is connected to the inlet of the low-temperature molten salt storage tank, the cold-side inlet of the molten salt steam heat exchanger is connected to the outlet of the deaerator, and the cold-side outlet of the molten salt steam heat exchanger is connected to the inlet of the industrial steam supply manifold.

[0014] In some embodiments, a flue gas steam heat exchanger is provided on the second flue gas heating passage. The hot-side inlet end of the flue gas steam heat exchanger is connected to the cold-side outlet end of the molten salt steam heat exchanger, the hot-side outlet end of the flue gas steam heat exchanger is connected to the cold-side inlet end of the molten salt steam heat exchanger, the cold-side inlet end of the flue gas steam heat exchanger is connected to the front flue of the flue, and the cold-side outlet end of the flue gas steam heat exchanger is connected to the rear flue of the flue.

[0015] In some embodiments, a second flue gas bypass valve is provided between the cold-side inlet end of the flue gas steam heat exchanger and the cold-side outlet end of the flue gas steam heat exchanger.

[0016] In some embodiments, an induced draft fan is installed on the front flue outlet pipeline of the flue.

[0017] On the other hand, this invention proposes a working method for a low-load denitrification-deep peak-shaving system based on molten salt thermal storage, comprising the following processes:

[0018] Using high-temperature molten salt to heat flue gas: When the coal-fired power generation system needs deep peak shaving, the molten salt electric heater is started. The low-temperature molten salt in the low-temperature molten salt heat storage tank is heated and then stored in the high-temperature molten salt heat storage tank. Part of the high-temperature molten salt enters the flue gas molten salt heat exchanger to heat the flue gas, and the other part of the high-temperature molten salt enters the molten salt steam heat exchanger to heat the condensate and generate high-temperature steam.

[0019] High-temperature steam heating of flue gas: When the coal-fired power generation system needs deep peak shaving, the molten salt electric heater is started. The low-temperature molten salt in the low-temperature molten salt storage tank is heated and then stored in the high-temperature molten salt storage tank. The high-temperature molten salt enters the molten salt steam heat exchanger to heat the condensate and generate high-temperature steam. Part of the high-temperature steam enters the industrial steam supply header, and the other part of the high-temperature steam enters the flue gas steam heat exchanger to heat the flue gas.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention adds two methods for heating flue gas to release energy: high-temperature molten salt and high-temperature steam. This avoids the imbalance between the input and output energy of the molten salt thermal storage system when the steam supply demand is insufficient, and reduces the cost of thermal storage molten salt and investment.

[0022] This invention uses molten salt energy storage to increase flue gas temperature, thus ensuring the denitrification capability of the unit during low-load operation. Attached Figure Description

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0024] Figure 1 This is a schematic diagram of the low-load denitrification-deep peak-shaving system based on molten salt thermal storage of the present invention;

[0025] Explanation of reference numerals in the attached figures:

[0026] 1. Boiler; 2. Denitrification device; 3. Deaerator; 4. Industrial steam supply manifold; 5. Generator; 6. High-temperature molten salt heat storage tank; 7. Low-temperature molten salt heat storage tank; 8. Molten salt electric heater; 9. Molten salt steam heat exchanger; 10. High-temperature molten salt pump; 11. Low-temperature molten salt pump; 12. Flue gas molten salt heat exchanger; 13. Flue gas steam heat exchanger; 14. Feed water pump; 15. Exhaust fan; 16. First flue gas bypass valve; 17. Second flue gas bypass valve; 18. Molten salt regulating valve; 19. Steam regulating valve; 20. First flue gas valve; 21. Second flue gas valve; 22. Flue; 23. Detailed Implementation

[0027] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0028] The following description, with reference to the accompanying drawings, describes a low-load denitrification-deep peak-shaving system based on molten salt thermal storage and its operating method according to an embodiment of the present invention.

[0029] like Figure 1 As shown, the low-load denitrification-deep peak shaving system based on molten salt thermal storage of the present invention includes a coal-fired power generation system and a molten salt thermal storage system.

[0030] The coal-fired power generation system includes a boiler 1, a denitrification device 2, a deaerator 3, an industrial steam supply header 4, a generator 5, and a high-voltage transformer 6. The boiler 1 has a flue 23. The inlet of the denitrification device 2 is connected to the outlet of the flue 23. The flue 23 is divided into a front flue and a rear flue. An induced draft fan 16 is installed on the outlet pipeline of the front flue. The induced draft fan 16 is used to introduce the flue gas in the front flue into the flue gas molten salt heat exchanger 13 or the flue gas steam heat exchanger 14 under low-load denitrification conditions.

[0031] The molten salt thermal storage system includes a first flue gas heating passage, a second flue gas heating passage, and a molten salt thermal storage passage. The coal-fired power generation system provides electricity to the molten salt thermal storage passage. The high-temperature molten salt provides a heat source for the first flue gas heating passage, and the high-temperature steam provides a heat source for the second flue gas heating passage. The high-temperature steam is obtained by heating condensate with high-temperature molten salt.

[0032] A low-temperature molten salt storage tank 8, a molten salt electric heater 9, and a high-temperature molten salt storage tank 7 are sequentially installed on the molten salt storage passage. The low-temperature molten salt flowing out of the outlet of the low-temperature molten salt storage tank 8 is heated by the molten salt electric heater 9 and stored in the high-temperature molten salt storage tank 7. The outlet of the generator 5 is connected to the inlet of the molten salt electric heater 9 through the high-voltage transformer 6.

[0033] Specifically, the low-temperature molten salt storage tank 8 is used to store low-temperature molten salt, the high-temperature molten salt storage tank 7 is used to store high-temperature molten salt, and the molten salt electric heater 9 is installed between the low-temperature molten salt storage tank 8 and the high-temperature molten salt storage tank 7. The outlet end of the low-temperature molten salt storage tank 8 is connected to the inlet end of the molten salt electric heater 9, and the outlet end of the molten salt electric heater 9 is connected to the inlet end of the high-temperature molten salt storage tank 7. The molten salt electric heater 9 is used to heat the low-temperature molten salt into high-temperature molten salt using electrical energy. The electrical energy generated by the generator 5 is transformed by the high-voltage transformer 6 and then supplied to the molten salt electric heater 9. A low-temperature molten salt pump 12 is installed on the outlet pipeline of the low-temperature molten salt storage tank 8. When it is necessary to heat the low-temperature molten salt in the low-temperature molten salt storage tank 8, the low-temperature molten salt pump 12 and the molten salt electric heater 9 are started. Under the action of the low-temperature molten salt pump 12, the low-temperature molten salt in the low-temperature molten salt storage tank 8 flows out of the low-temperature molten salt storage tank 8, enters the molten salt electric heater 9 for heating, and then enters the high-temperature molten salt storage tank 7 from the inlet end for storage. A high-temperature molten salt pump 11 is installed on the outlet pipeline of the high-temperature molten salt storage tank 7. When it is necessary to use the high-temperature molten salt in the high-temperature molten salt storage tank 7, the high-temperature molten salt pump 11 is started, so that the high-temperature molten salt flows out from the outlet end of the high-temperature molten salt storage tank 7.

[0034] A molten salt steam heat exchanger 10 is installed between the deaerator 3 and the industrial steam supply manifold 4. The hot side inlet of the molten salt steam heat exchanger 10 is connected to the outlet of the high-temperature molten salt heat storage tank 7, the hot side outlet of the molten salt steam heat exchanger 10 is connected to the inlet of the low-temperature molten salt heat storage tank 8, the cold side inlet of the molten salt steam heat exchanger 10 is connected to the outlet of the deaerator 3, and the cold side outlet of the molten salt steam heat exchanger 10 is connected to the inlet of the industrial steam supply manifold 4.

[0035] Specifically, a molten salt steam heat exchanger 10 is installed between the deaerator 3 and the industrial steam supply header 4. In the molten salt steam heat exchanger 10, high-temperature molten salt heats the condensate at the outlet of the deaerator 3 into high-temperature steam. A feedwater pump 15 is installed on the pipeline between the outlet of the deaerator 3 and the cold-side inlet of the molten salt steam heat exchanger 10. When the feedwater pump 15 is started, the condensate at the outlet of the deaerator 3 flows into the cold-side inlet of the molten salt steam heat exchanger 10, while the high-temperature molten salt flows into the hot-side inlet of the molten salt steam heat exchanger 10. In the molten salt steam heat exchanger 10, the high-temperature molten salt heats the condensate, and the heated condensate becomes high-temperature steam, flowing out from the cold-side outlet of the molten salt steam heat exchanger 10 and into the industrial steam supply header 4 for use. After releasing heat energy, the high-temperature molten salt becomes low-temperature molten salt, flowing out from the hot-side outlet of the molten salt steam heat exchanger 10 and entering the low-temperature molten salt storage tank 8 for storage.

[0036] A flue gas molten salt heat exchanger 13 is installed in the first flue gas heating passage. The hot-side inlet of the flue gas molten salt heat exchanger 13 is connected to the outlet of the high-temperature molten salt heat storage tank 7, and the hot-side outlet of the flue gas molten salt heat exchanger 13 is connected to the inlet of the low-temperature molten salt heat storage tank 8. The cold-side inlet of the flue gas molten salt heat exchanger 13 is connected to the front flue of the flue duct 23, and the cold-side outlet of the flue gas molten salt heat exchanger 13 is connected to the rear flue of the flue duct 23. A first flue gas bypass valve 17 is installed between the cold-side inlet and cold-side outlet of the flue gas molten salt heat exchanger 13.

[0037] Specifically, in the flue gas molten salt heat exchanger 13, the high-temperature molten salt on the hot side exchanges heat with the flue gas on the cold side. A first flue gas valve 21 is installed on the cold side inlet pipeline of the flue gas molten salt heat exchanger 13, a first flue gas bypass valve 17 is installed on the pipeline between the cold side inlet end and the cold side outlet end of the flue gas molten salt heat exchanger 13, and a molten salt regulating valve 19 is installed on the pipeline between the high-temperature molten salt pump 11 on the outlet pipeline of the high-temperature molten salt heat storage tank 7 and the hot side inlet end of the flue gas molten salt heat exchanger 13. Understandably, when it is necessary to use the flue gas molten salt heat exchanger 13 to heat the flue gas, the molten salt regulating valve 19 and the first flue gas valve 21 are opened, and the first flue gas bypass valve 17 is closed. High-temperature molten salt flows into the hot-side inlet of the flue gas molten salt heat exchanger 13 through the molten salt regulating valve 19. The flue gas from the front flue, under the action of the induced draft fan 16, flows into the cold-side inlet of the flue gas molten salt heat exchanger 13 through the first flue gas valve 21. In the flue gas molten salt heat exchanger 13, the high-temperature molten salt on the hot side heats the flue gas on the cold side. After being heated, the flue gas flows out from the cold side outlet of the flue gas molten salt heat exchanger 13 and enters the flue through the pipeline of the rear flue, and finally enters the denitrification device 2. The high-temperature molten salt after heat exchange becomes low-temperature molten salt and flows out from the hot side outlet of the flue gas molten salt heat exchanger 13 and enters the low-temperature molten salt heat storage tank 8 for storage. When it is not necessary to use the flue gas molten salt heat exchanger 13 to heat the flue gas, the first flue gas bypass valve 17 is opened and the molten salt regulating valve 19 and the first flue gas valve 21 are closed, so that the flue gas flows through the first flue gas bypass valve 17.

[0038] A flue gas steam heat exchanger 14 is installed in the second flue gas heating passage. The hot-side inlet of the flue gas steam heat exchanger 14 is connected to the cold-side outlet of the molten salt steam heat exchanger 10, and the hot-side outlet of the flue gas steam heat exchanger 14 is connected to the cold-side inlet of the molten salt steam heat exchanger 10. The cold-side inlet of the flue gas steam heat exchanger 14 is connected to the front flue of the flue, and the cold-side outlet of the flue gas steam heat exchanger 14 is connected to the rear flue. A second flue gas bypass valve 18 is installed between the cold-side inlet and cold-side outlet of the flue gas steam heat exchanger 14.

[0039] Specifically, in the flue gas steam heat exchanger 14, high-temperature steam on the hot side exchanges heat with flue gas on the cold side. A second flue gas valve 22 is installed on the cold-side inlet pipeline of the flue gas steam heat exchanger 14, and a second flue gas bypass valve 18 is installed on the pipeline between the cold-side inlet and outlet ends of the flue gas steam heat exchanger 14. A steam regulating valve 20 is installed on the pipeline between the cold-side outlet end of the molten salt steam heat exchanger 10 and the hot-side inlet end of the flue gas steam heat exchanger 14. It can be understood that when the flue gas steam heat exchanger 14 needs to be used to heat the flue gas, the steam regulating valve 20 and the second flue gas valve 22 are opened, and the second flue gas bypass valve 18 is closed. High-temperature steam flows into the hot-side inlet end of the flue gas steam heat exchanger 14 through the steam regulating valve 20. The flue gas in the front flue, under the action of the induced draft fan 16, flows into the cold-side inlet end of the flue gas steam heat exchanger 14 through the second flue gas valve 22. In the flue gas steam heat exchanger 14, the high-temperature steam on the hot side heats the flue gas on the cold side. The heated flue gas flows out from the cold side outlet of the flue gas steam heat exchanger 14 and enters the flue through the pipeline of the rear flue, and finally enters the denitrification device 2. The high-temperature steam after heat exchange becomes condensate and enters the molten salt steam heat exchanger 10 from the cold side inlet. When it is not necessary to use the flue gas steam heat exchanger 14 to heat the flue gas, the second flue gas bypass valve 18 is opened and the steam regulating valve 20 and the second flue gas valve 22 are closed, so that the flue gas flows through the second flue gas bypass valve 18.

[0040] In some embodiments, the high-temperature steam after heat exchange in the flue gas steam heat exchanger 14 becomes condensate and enters the deaerator 3 from the inlet end of the deaerator 3 for use.

[0041] In addition, the flue gas molten salt heat exchanger 13 and the flue gas steam heat exchanger 14 can be used interchangeably. That is, when the flue gas molten salt heat exchanger 13 is used to exchange heat with the flue gas, the flue gas steam heat exchanger 14 is turned off; when the flue gas steam heat exchanger 14 is used to exchange heat with the flue gas, the flue gas molten salt heat exchanger 13 is turned off.

[0042] The operating method of the low-load denitrification-deep peak shaving system based on molten salt thermal storage of the present invention includes the following processes:

[0043] High-temperature molten salt is used to heat flue gas: When the coal-fired power generation system needs deep peak shaving, the molten salt electric heater 9 is started. The low-temperature molten salt in the low-temperature molten salt heat storage tank 8 is heated and stored in the high-temperature molten salt heat storage tank 7. Part of the high-temperature molten salt enters the flue gas molten salt heat exchanger 13 to heat the flue gas, and the other part of the high-temperature molten salt enters the molten salt steam heat exchanger 10 to heat the condensate and generate high-temperature steam.

[0044] High-temperature steam is used to heat flue gas: When the coal-fired power generation system needs deep peak shaving, the molten salt electric heater 9 is started. The low-temperature molten salt in the low-temperature molten salt heat storage tank 8 is heated and stored in the high-temperature molten salt heat storage tank 7. The high-temperature molten salt enters the molten salt steam heat exchanger 10 to heat the condensate and generate high-temperature steam. Part of the high-temperature steam enters the industrial steam supply manifold 4, and the other part of the high-temperature steam enters the flue gas steam heat exchanger 14 to heat the flue gas.

[0045] Specifically, when using high-temperature molten salt to heat flue gas, when the coal-fired power generation system needs deep peak shaving, the molten salt electric heater 9 and the low-temperature molten salt pump 12 are started for energy storage. The low-temperature molten salt in the low-temperature molten salt heat storage tank 8 is heated by the low-temperature molten salt pump 12 and becomes high-temperature molten salt, which is then stored in the high-temperature molten salt heat storage tank 7. The molten salt steam heat exchanger 10 and the high-temperature molten salt pump 11 are started, and the high-temperature molten salt enters the molten salt steam heat exchanger 10 to heat the condensate and generate high-temperature steam to supplement the insufficient steam supply of the unit. The induced draft fan 16 and the flue gas molten salt heat exchanger 13 are started, the second flue gas bypass valve 18, the molten salt regulating valve 19, and the first flue gas valve 21 are opened, and the first flue gas bypass valve 17, the steam regulating valve 20, and the second flue gas valve 22 are closed, so that the high-temperature molten salt enters the flue gas molten salt heat exchanger 13 to heat the flue gas.

[0046] When using high-temperature steam to heat flue gas, and when the coal-fired power generation system requires deep peak shaving, the molten salt electric heater 9 and the low-temperature molten salt pump 12 are started for energy storage. The low-temperature molten salt in the low-temperature molten salt heat storage tank 8 is heated by the low-temperature molten salt pump 12 and becomes high-temperature molten salt, which is then stored in the high-temperature molten salt heat storage tank 7. The molten salt steam heat exchanger 10 and the high-temperature molten salt pump 11 are started, and the high-temperature molten salt enters the molten salt steam heat exchanger 10 to heat the condensate and generate high-temperature steam to supplement the insufficient steam supply of the unit. The induced draft fan 16 and the flue gas steam heat exchanger 14 are started, the first flue gas bypass valve 17, the steam regulating valve 20, and the second flue gas valve 22 are opened, and the second flue gas bypass valve 18, the molten salt regulating valve 19, and the first flue gas valve 21 are closed, so that the high-temperature steam enters the flue gas steam heat exchanger 14 to heat the flue gas.

[0047] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A low-load denitrification-deep peak-shaving system based on molten salt thermal storage, characterized in that, include: A coal-fired power generation system, comprising a boiler, a denitrification device, a deaerator, and an industrial steam header, wherein the boiler has a flue, the inlet of the denitrification device is connected to the outlet of the flue, and the flue is divided into a front flue and a rear flue; A molten salt thermal energy storage system includes a first flue gas heating passage, a second flue gas heating passage, and a molten salt thermal energy storage passage. The coal-fired power generation system provides electrical energy to the molten salt thermal energy storage passage. High-temperature molten salt provides a heat source for the first flue gas heating passage, and high-temperature steam provides a heat source for the second flue gas heating passage. The high-temperature steam is obtained by heating condensate with the high-temperature molten salt.

2. The system as described in claim 1, characterized in that, The molten salt thermal storage passage is sequentially provided with a low-temperature molten salt thermal storage tank, a molten salt electric heater, and a high-temperature molten salt thermal storage tank. The low-temperature molten salt flowing out of the outlet end of the low-temperature molten salt thermal storage tank is heated by the molten salt electric heater and then stored in the high-temperature molten salt thermal storage tank.

3. The system as described in claim 2, characterized in that, The coal-fired power generation system also includes a generator and a high-voltage transformer, with the generator's output port connected to the molten salt electric heater's inlet port via the high-voltage transformer.

4. The system as described in claim 2, characterized in that, A flue gas molten salt heat exchanger is provided in the first flue gas heating passage. The hot side inlet end of the flue gas molten salt heat exchanger is connected to the outlet end of the high-temperature molten salt heat storage tank, the hot side outlet end of the flue gas molten salt heat exchanger is connected to the inlet end of the low-temperature molten salt heat storage tank, the cold side inlet end of the flue gas molten salt heat exchanger is connected to the front flue of the flue, and the cold side outlet end of the flue gas molten salt heat exchanger is connected to the rear flue of the flue.

5. The system as described in claim 4, characterized in that, A first flue gas bypass valve is provided between the cold-side inlet end and the cold-side outlet end of the flue gas molten salt heat exchanger.

6. The system as described in claim 2, characterized in that, A molten salt steam heat exchanger is installed between the deaerator and the industrial steam supply manifold. The hot-side inlet of the molten salt steam heat exchanger is connected to the outlet of the high-temperature molten salt storage tank, the hot-side outlet of the molten salt steam heat exchanger is connected to the inlet of the low-temperature molten salt storage tank, the cold-side inlet of the molten salt steam heat exchanger is connected to the outlet of the deaerator, and the cold-side outlet of the molten salt steam heat exchanger is connected to the inlet of the industrial steam supply manifold.

7. The system as described in claim 6, characterized in that, A flue gas steam heat exchanger is provided in the second flue gas heating passage. The hot side inlet end of the flue gas steam heat exchanger is connected to the cold side outlet end of the molten salt steam heat exchanger. The hot side outlet end of the flue gas steam heat exchanger is connected to the cold side inlet end of the molten salt steam heat exchanger. The cold side inlet end of the flue gas steam heat exchanger is connected to the front flue of the flue. The cold side outlet end of the flue gas steam heat exchanger is connected to the rear flue of the flue.

8. The system as described in claim 7, characterized in that, A second flue gas bypass valve is provided between the cold-side inlet end and the cold-side outlet end of the flue gas steam heat exchanger.

9. The system as described in claim 1, characterized in that, An induced draft fan is installed on the outlet pipeline of the front part of the flue.

10. A method for operating a low-load denitrification-deep peak-shaving system based on molten salt thermal storage, characterized in that, The system according to any one of claims 2-8 includes the following process: Using high-temperature molten salt to heat flue gas: When the coal-fired power generation system needs deep peak shaving, the molten salt electric heater is started. The low-temperature molten salt in the low-temperature molten salt heat storage tank is heated and then stored in the high-temperature molten salt heat storage tank. Part of the high-temperature molten salt enters the flue gas molten salt heat exchanger to heat the flue gas, and the other part of the high-temperature molten salt enters the molten salt steam heat exchanger to heat the condensate and generate high-temperature steam. High-temperature steam heating of flue gas: When the coal-fired power generation system needs deep peak shaving, the molten salt electric heater is started. The low-temperature molten salt in the low-temperature molten salt storage tank is heated and then stored in the high-temperature molten salt storage tank. The high-temperature molten salt enters the molten salt steam heat exchanger to heat the condensate and generate high-temperature steam. Part of the high-temperature steam enters the industrial steam supply header, and the other part of the high-temperature steam enters the flue gas steam heat exchanger to heat the flue gas.

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