A heat storage system based on gas turbine and working method

Abstract

The present invention discloses a heat storage system and working method based on a gas turbine, wherein the heat storage system comprises a first molten salt heat storage passage, a second molten salt heat storage passage and a first molten salt heat release passage arranged between a low-temperature molten salt storage tank and a high-temperature molten salt storage tank, wherein a first heat exchanger is arranged on the first molten salt heat storage passage, and the two ends of the cold side thereof are respectively connected to the low-temperature molten salt storage tank and the high-temperature molten salt storage tank; an electric heating element for heating the low-temperature molten salt is arranged on the second molten salt heat storage passage; and a second heat exchanger is arranged on the first molten salt heat release passage, which is used to supply steam by heat exchange of feed water on its cold side after passing through the high-temperature molten salt. The present invention can realize the continuous steam supply requirement when the gas turbine is working intermittently by storing all the available heat of the high-temperature flue gas generated when the gas turbine is working into the molten salt heat storage system. Compared with the natural gas boiler, the present invention generates electricity first by the gas turbine, and supplies steam with the waste heat, which effectively reduces the production cost of steam.

Description

Technical Field

[0001] The present invention relates to the field of heat storage technology, and in particular to a heat storage system based on a gas turbine and a working method. Background Art

[0002] In recent years, the installed capacity of new energy power generation such as photovoltaic and wind power in the power system has increased year by year, but photovoltaic and wind power have volatility and intermittency problems, which affect the stable operation of the power system. Gas turbine power generation has the advantages of fast start and stop speed and high load rate, and can play the role of peak load regulation and frequency regulation in the power system. For gas-steam combined cycle power generation systems with heating demand, the stability of heating cannot be guaranteed because gas turbines participate in peak load regulation, frequency regulation and frequent start and stop.

[0003] In order to reduce pollution and carbon emissions, many small coal-fired boilers have been shut down and replaced with gas. For example, factories that need industrial steam, such as papermaking and chemical industries, use natural gas boilers to produce steam, which increases steam costs and fails to fully utilize the high-quality thermal energy of natural gas. Summary of the invention

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

[0005] To this end, an embodiment of the present invention proposes a gas turbine-based heat storage system and a working method. The gas turbine-based heat storage system of the present invention produces industrial steam through cogeneration, reduces energy costs, and solves the problem that the gas turbine cannot stably supply heat when participating in peak load regulation and frequency regulation.

[0006] In one aspect, the present invention provides a heat storage system based on a gas turbine, comprising:

[0007] A first molten salt heat storage passage, a second molten salt heat storage passage and a first molten salt heat release passage are arranged between the low-temperature molten salt storage tank and the high-temperature molten salt storage tank;

[0008] A first heat exchanger is arranged on the first molten salt heat storage passage, and the two ends of the cold side are respectively connected to the low-temperature molten salt storage tank and the high-temperature molten salt storage tank; the hot side of the first heat exchanger is passed through high-temperature flue gas to exchange heat with the low-temperature molten salt on its cold side;

[0009] An electric heating element is provided on the second molten salt heat storage passage for heating the low-temperature molten salt in the low-temperature molten salt storage tank;

[0010] A second heat exchanger is arranged on the first molten salt heat release passage, and the two ends of the hot side of the second heat exchanger are respectively connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank, and the high-temperature molten salt is used to heat the feed water on the cold side of the second heat exchanger to supply steam.

[0011] In some embodiments, a nitrogen supply unit is further included, wherein the nitrogen supply unit is respectively connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank for filling nitrogen.

[0012] In some embodiments, the nitrogen supply component further includes a first gas connecting pipe, and the first gas connecting pipe is used to connect the high-temperature molten salt storage tank and the low-temperature molten salt storage tank to achieve internal gas circulation between the two.

[0013] In some embodiments, a molten salt buffer tank is further provided on the first molten salt heat storage passage, and in the molten salt flow direction, the molten salt buffer tank is provided upstream of the first heat exchanger.

[0014] In some embodiments, the molten salt buffer tank is connected to the nitrogen supply component, and the nitrogen supply component fills nitrogen into the molten salt buffer tank.

[0015] In some embodiments, the nitrogen supply member includes a second gas connecting pipe, one end of the second gas connecting pipe is connected to the molten salt buffer tank, and the other end of the second gas connecting pipe is connected to the first gas connecting pipe.

[0016] In some embodiments, the high-temperature flue gas is selected from exhaust gas in a gas turbine power generation process.

[0017] In some embodiments, the molten salt buffer tank is arranged at a higher position than the first heat exchanger.

[0018] In some embodiments, the first heat exchanger is a shell and tube structure, the high-temperature flue gas flows from bottom to top on the shell side of the shell and tube structure, and the molten salt flows from top to bottom on the tube side of the shell and tube structure.

[0019] On the other hand, the present invention provides a working method of a heat storage system based on a gas turbine, comprising the following steps:

[0020] When the first molten salt heat storage path starts to store heat, the low-temperature molten salt in the low-temperature molten salt storage tank enters the first heat exchanger to exchange heat with the high-temperature flue gas. The low-temperature molten salt is heated by the high-temperature flue gas to become high-temperature molten salt, and then enters the high-temperature molten salt storage tank for storage;

[0021] When the second molten salt passage starts to store heat, the low-temperature molten salt in the low-temperature molten salt storage tank enters the electric heating element, and the low-temperature molten salt is heated by the electric heating element to become high-temperature molten salt, and then enters the high-temperature molten salt storage tank for storage;

[0022] When the first molten salt heat release passage supplies steam to the outside, the high-temperature molten salt in the high-temperature molten salt storage tank enters the second heat exchanger, heats the feed water to make it steam or superheated steam for external supply, and the high-temperature molten salt after heat release becomes low-temperature molten salt, and then enters the low-temperature molten salt storage tank for storage.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] The present invention stores all the available heat of the high-temperature flue gas generated when the gas turbine is working into the molten salt heat storage system, so that the need for continuous steam supply can be met when the gas turbine is working intermittently. Compared with natural gas boilers, the present invention generates electricity first by the gas turbine and uses the waste heat to supply steam, effectively reducing the production cost of steam.

[0025] The present invention configures an electric heating element to heat the molten salt during periods of low electricity prices or when there is a demand for peak load regulation. While achieving low-cost energy storage, it can also participate in peak load regulation services and improve the flexibility of the power grid.

[0026] When the steam load changes, the present invention only needs to adjust the evaporation amount of the molten salt steam generator without adjusting the working state of the gas turbine, so that the gas turbine can operate in a range with higher power generation efficiency, thereby improving system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 This is a schematic structural diagram of a heat storage system according to an embodiment of the present invention;

[0029] Figure 2 A schematic structural diagram of a heat storage system according to another embodiment of the present invention;

[0030] Figure 3 A schematic structural diagram of a heat storage system according to another embodiment of the present invention;

[0031] Description of reference numerals:

[0032] Gas turbine power generation system 1, a first heat exchanger 2, a molten salt buffer tank 3, a low-temperature molten salt storage tank 4, a high-temperature molten salt storage tank 5, a low-temperature molten salt pump 6, a high-temperature molten salt pump 7, a first valve 8, a second valve 9, a third valve 10, a fourth valve 11, an electric heating element 12, a second heat exchanger 13, a feed water inlet 14, a steam outlet 15, a first gas connecting pipe 16, and a second gas connecting pipe 17. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0034] A gas turbine-based heat storage system according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0035] like Figure 1 As shown, the gas turbine-based heat storage system of the present invention includes a first molten salt heat storage passage, a second molten salt heat storage passage and a first molten salt heat release passage, and the first molten salt heat storage passage, the second molten salt heat storage passage and the first molten salt heat release passage are all arranged between the low-temperature molten salt storage tank 4 and the high-temperature molten salt storage tank 5.

[0036] A first heat exchanger 2 is arranged on the first molten salt heat storage passage, and its two ends on the cold side are respectively connected to a low-temperature molten salt storage tank 4 and a high-temperature molten salt storage tank 5; high-temperature flue gas is introduced into the hot side of the first heat exchanger 2 to exchange heat with the low-temperature molten salt on its cold side.

[0037] Specifically, the first heat exchanger 2 is arranged on the first molten salt heat storage passage, and the first heat exchanger 2 has a cold side and a hot side, wherein the inlet end of the cold side of the first heat exchanger 2 is connected to the low-temperature molten salt storage tank 4, and the outlet end of the cold side of the first heat exchanger 2 is connected to the high-temperature molten salt storage tank 5, and the high-temperature flue gas enters from the hot side inlet of the first heat exchanger 2. In the first heat exchanger 2, the high-temperature flue gas on the hot side heats the low-temperature molten salt on its cold side, and the heated low-temperature molten salt is stored in the high-temperature molten salt storage tank 5. The high-temperature flue gas after heat exchange is discharged through the hot side outlet of the first heat exchanger 2.

[0038] See also Figure 1 In the specific working process, along the flow direction of the molten salt, a low-temperature molten salt pump 6, a first valve 8, a first heat exchanger 2 and a third valve 10 are sequentially arranged on the first molten salt heat storage passage. The low-temperature molten salt pump 6 is arranged on the bottom outlet pipeline of the low-temperature molten salt storage tank 4. The low-temperature molten salt pump 6 pumps the low-temperature molten salt in the low-temperature molten salt storage tank 4 into the cold side inlet of the first heat exchanger 2 through the first valve 8. The low-temperature molten salt exchanges heat with the high-temperature flue gas on the hot side in the first heat exchanger 2 and flows out from the cold side outlet of the first heat exchanger 2, and flows into the high-temperature molten salt storage tank 5 through the third valve 10 for storage.

[0039] In some embodiments, the first heat exchanger 2 is a shell and tube structure, the high-temperature flue gas flows from bottom to top on the shell side of the shell and tube structure, and the molten salt flows from top to bottom on the tube side of the shell and tube structure.

[0040] Specifically, high-temperature flue gas and low-temperature molten salt exchange heat in a shell and tube structure. The high-temperature flue gas flows from bottom to top on the shell side, and the molten salt flows from top to bottom on the tube side of the shell and tube structure. The flow direction of the high-temperature flue gas is opposite to that of the molten salt, thereby enabling better heat exchange and improving heat exchange efficiency.

[0041] An electric heating element 12 is provided on the second molten salt heat storage passage, which is used to heat the low-temperature molten salt in the low-temperature molten salt storage tank 4. The first molten salt heat storage passage and the second molten salt heat storage passage are two independent heat storage passages. The low-temperature molten salt is heated by high-temperature flue gas in the first molten salt heat storage passage, and the low-temperature molten salt is heated by electric energy in the second molten salt heat storage passage. The low-temperature molten salt in the low-temperature molten salt storage tank 4 is heated by the electric heating element 12 and stored in the high-temperature molten salt storage tank 5. It can be understood that when the demand for steam increases and the high-temperature molten salt produced by the first molten salt heat storage passage alone cannot meet the demand, the first molten salt heat storage passage and the second molten salt heat storage passage are put into operation at the same time to increase the output of high-temperature molten salt to meet the needs of the second heat exchanger 13.

[0042] The first molten salt heat storage passage and the second molten salt heat storage passage both heat the low-temperature molten salt in the low-temperature molten salt storage tank 4 and store it in the high-temperature molten salt storage tank 5. The two can share the low-temperature molten salt pump 6 arranged on the outlet pipeline at the bottom of the low-temperature molten salt storage tank 4. In the specific working process, along the flow direction of the molten salt, the low-temperature molten salt pump 6, the second valve 9, the electric heater 12 and the fourth valve 11 are arranged in sequence on the second molten salt heat storage passage. In the time period of low electricity price or peak demand, the electric heater 12 is turned on, and the low-temperature molten salt is heated in the electric heater 12 to become high-temperature molten salt, and the high-temperature molten salt enters the high-temperature molten salt storage tank 5 through the fourth valve 11. It can be understood that the low-temperature molten salt is heated to high-temperature molten salt by the electric heater 12 during the low electricity price period to achieve low-cost energy storage; in the time period with peak demand, the demand for high-temperature molten salt can be maintained by heating the low-temperature molten salt by the electric heater 12.

[0043] A second heat exchanger 13 is arranged on the first molten salt heat release passage, and both ends of the hot side of the second heat exchanger 13 are respectively connected to the high-temperature molten salt storage tank 5 and the low-temperature molten salt storage tank 4, and the high-temperature molten salt is used to heat the feed water on the cold side of the second heat exchanger 13 to supply steam.

[0044] Specifically, the second heat exchanger 13 is arranged on the first molten salt heat release passage, and the second heat exchanger 13 has a cold side and a hot side, wherein the inlet end of the hot side of the second heat exchanger 13 is connected to the high-temperature molten salt storage tank 5, and the outlet end of the hot side of the second heat exchanger 13 is connected to the low-temperature molten salt storage tank 4, and the high-temperature molten salt in the high-temperature molten salt storage tank 5 enters the second heat exchanger 13 from the hot side inlet of the second heat exchanger 13, and the high-temperature molten salt on the hot side of the second heat exchanger 13 heats the feed water on its cold side. After the feed water is heated by the high-temperature molten salt, steam or superheated steam is generated for use. The high-temperature molten salt after heat exchange flows out from the hot side outlet of the second heat exchanger 13 and is stored in the low-temperature molten salt storage tank 4.

[0045] A high-temperature molten salt pump 7 is arranged on the first molten salt heat release passage, and the high-temperature molten salt pump 7 is arranged on the bottom outlet pipeline of the high-temperature molten salt storage tank 5. The high-temperature molten salt pump 7 pumps the high-temperature molten salt in the high-temperature molten salt storage tank 5 into the hot side inlet end of the second heat exchanger 13 to heat the feed water.

[0046] The feed water enters the second heat exchanger 13 through the cold side inlet of the second heat exchanger 13, and the steam generated by heating the feed water is discharged through the cold side outlet of the second heat exchanger 13, wherein the cold side inlet and the cold side outlet of the second heat exchanger 13 correspond to the feed water inlet 14 and the steam outlet 15 respectively, the feed water inlet 14 is arranged at the lower part of the second heat exchanger 13, and the steam outlet 15 is arranged above the feed water inlet 14. The high temperature molten salt pump 7 pumps the high temperature molten salt into the hot side inlet of the second heat exchanger 13, and in the second heat exchanger 13, the high temperature molten salt exchanges heat with the feed water entering the second heat exchanger 13 from the feed water inlet 14. After the feed water absorbs the heat of the high temperature molten salt, steam or superheated steam is generated, and the steam or superheated steam is discharged from the steam outlet 15 for use. After the high temperature molten salt is heat exchanged, it becomes low temperature molten salt, and the low temperature molten salt enters the low temperature molten salt storage tank 4 for storage. It can be understood that, according to the needs, the feed water absorbs heat in the second heat exchanger 13 to generate steam or superheated steam.

[0047] The second heat exchanger 13 of the present invention is used to heat feed water to generate steam, that is, the second heat exchanger 13 is the steam generator of the present invention.

[0048] In some embodiments, the heat storage system further includes a nitrogen supply part, which is respectively connected to the high-temperature molten salt storage tank 5 and the low-temperature molten salt storage tank 4 for filling with nitrogen. It is understandable that when the liquid level in the high-temperature molten salt storage tank 5 or the low-temperature molten salt storage tank 4 drops, a negative pressure is generated in the molten salt storage tank, and there is a risk that the molten salt storage tank is crushed. Nitrogen is supplied to the molten salt storage tank in time using a nitrogen supply part to avoid negative pressure in the molten salt storage tank. In addition, when the liquid level in the molten salt storage tank rises and a positive pressure occurs, it can be connected to the atmosphere through an opening on the molten salt storage tank, and some gas is discharged, thereby maintaining the air pressure in the molten salt storage tank consistent with the atmospheric pressure.

[0049] In some embodiments, the nitrogen supply component includes a first gas connecting pipe 16, and the first gas connecting pipe 16 is used to connect the high-temperature molten salt storage tank 5 and the low-temperature molten salt storage tank 4 to achieve internal gas circulation between the two.

[0050] Specifically, the first gas connecting pipe 16 is a one-inlet and multiple-outlet pipeline structure. The air inlet end of the first gas connecting pipe 16 is connected to the nitrogen supply part, and the air outlet end of the first gas connecting pipe 16 is respectively connected to the high-temperature molten salt storage tank 5 and the low-temperature molten salt storage tank 4, so that the nitrogen is circulated between the high-temperature molten salt storage tank 5 and the low-temperature molten salt storage tank 4 to maintain the gas pressure, which can reduce the consumption of nitrogen and reduce costs.

[0051] In some embodiments, a molten salt buffer tank 3 is provided on the first molten salt heat storage passage, and the molten salt buffer tank 3 is provided upstream of the first heat exchanger 2 in the molten salt flow direction.

[0052] For details, see Figure 2The outlet end of the molten salt buffer tank 3 is connected to the cold side inlet of the first heat exchanger 2. The low-temperature molten salt pump 6 pumps the low-temperature molten salt in the low-temperature molten salt storage tank 4 into the molten salt buffer tank 3 through the first valve 8. The low-temperature molten salt in the molten salt buffer tank 3 flows into the first heat exchanger 2, so that the low-temperature molten salt and the high-temperature flue gas are heat exchanged.

[0053] In some embodiments, the molten salt buffer tank 3 is connected to a nitrogen supply, and the nitrogen supply fills nitrogen into the molten salt buffer tank 3. When the liquid level in the molten salt buffer tank 3 drops, the nitrogen supply promptly provides nitrogen to the molten salt buffer tank 3 to avoid negative pressure.

[0054] In some embodiments, the nitrogen supply component includes a second gas connecting pipe 17, one end of the second gas connecting pipe 17 is connected to the molten salt buffer tank 3, and the other end is connected to the first gas connecting pipe 16, so as to realize gas circulation between the high-temperature molten salt storage tank 5, the low-temperature molten salt storage tank 4 and the molten salt buffer tank 3.

[0055] Specifically, when there is a molten salt buffer tank 3 in the heat storage system, the two ends of the second gas connecting pipe 17 are respectively connected to the molten salt buffer tank 3 and the first gas connecting pipe 16, and the high-temperature molten salt storage tank 5, the low-temperature molten salt storage tank 4 and the molten salt buffer tank 3 are connected through the second gas connecting pipe 17, so that nitrogen can be circulated among the three to maintain the gas pressure, which can reduce nitrogen consumption and reduce costs.

[0056] In some embodiments, the molten salt buffer tank 3 is arranged at a higher position than the first heat exchanger 2. Specifically, when the molten salt buffer tank 3 is arranged at a higher position than the first heat exchanger 2, the low-temperature molten salt in the molten salt buffer tank 3 can enter the first heat exchanger 2 under the action of gravity, and when the low-temperature molten salt pump 6 fails, the low-temperature molten salt in the molten salt buffer tank 3 can last for a period of time to prevent the first heat exchanger 2 from overheating.

[0057] In some embodiments, the high temperature flue gas is selected from the exhaust gas of a gas turbine power generation process. Figure 3 The gas turbine power generation system 1 uses natural gas as a raw material to generate electricity, and the power generation process of the gas turbine power generation system 1 generates high-temperature flue gas. The high-temperature flue gas discharged when the gas turbine power generation system 1 is working has a high heat content, and the heat of the high-temperature flue gas is recovered and utilized through the first heat exchanger 2. The heat storage system of the present invention stores the heat of the high-temperature flue gas in high-temperature molten salt. When steam is needed, the high-temperature molten salt is used to heat the feed water in the second heat exchanger 13 to generate steam, thereby realizing the decoupling of power generation and flue gas waste heat utilization in terms of time and steam output.

[0058] The working method of the gas turbine-based heat storage system comprises the following steps:

[0059] When the first molten salt heat storage path starts to store heat, the low-temperature molten salt in the low-temperature molten salt storage tank 4 enters the first heat exchanger 2 to exchange heat with the high-temperature flue gas. The low-temperature molten salt is heated by the high-temperature flue gas to become high-temperature molten salt, and then enters the high-temperature molten salt storage tank 5 for storage;

[0060] When the second molten salt passage starts to store heat, the low-temperature molten salt in the low-temperature molten salt storage tank 4 enters the electric heating element 12, and the low-temperature molten salt is heated by the electric heating element 12 to become high-temperature molten salt, and then enters the high-temperature molten salt storage tank 5 for storage;

[0061] When the first molten salt heat release passage supplies steam to the outside, the high-temperature molten salt in the high-temperature molten salt storage tank 5 enters the second heat exchanger 13, heats the feed water to make it steam or superheated steam for external supply, and the high-temperature molten salt after heat release becomes low-temperature molten salt, and then enters the low-temperature molten salt storage tank 4 for storage.

[0062] by Figure 3 Take the workflow of the present invention as an example:

[0063] The power generation process of the gas turbine power generation system 1 generates high-temperature flue gas, and the first molten salt heat storage passage performs a heat storage process. The first valve 8 and the third valve 10 are opened, and the second valve 9 and the fourth valve 11 are closed. The low-temperature molten salt pump 6 pumps the low-temperature molten salt in the low-temperature molten salt storage tank 4 into the molten salt buffer tank 3, and exchanges heat with the high-temperature flue gas in the first heat exchanger 2. After the low-temperature molten salt is heated by the high-temperature flue gas, high-temperature molten salt is generated and enters the high-temperature molten salt storage tank 5 for storage, completing the heat storage.

[0064] During the period of low electricity price or peak load demand, the second molten salt heat storage passage performs the heat storage process, opens the second valve 9 and the fourth valve 11, and part or all of the low-temperature molten salt at the outlet of the low-temperature molten salt pump 6 is heated by the electric heating element 12 and enters the high-temperature molten salt storage tank 5 to complete the heat storage.

[0065] When steam is needed, the first molten salt heat release passage performs the external steam supply process, and the high-temperature molten salt pump 7 pumps the high-temperature molten salt in the high-temperature molten salt storage tank 5 into the second heat exchanger 13. The high-temperature molten salt exchanges heat with the feed water in the second heat exchanger 13 and then enters the low-temperature molten salt storage tank 4 for storage. The feed water absorbs the heat of the high-temperature molten salt to generate steam or superheated steam for use.

[0066] In addition, when the steam demand increases and the high-temperature molten salt produced by the first molten salt heat storage passage alone cannot meet the demand, the first molten salt heat storage passage and the second molten salt heat storage passage are simultaneously subjected to the heat storage process to increase the high-temperature molten salt output and meet the steam supply demand.

[0067] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms may be for different embodiments or examples. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0068] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0069] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A heat storage system based on a gas turbine, characterized in that: include: A first molten salt heat storage passage, a second molten salt heat storage passage and a first molten salt heat release passage are arranged between the low-temperature molten salt storage tank and the high-temperature molten salt storage tank; A first heat exchanger is arranged on the first molten salt heat storage passage, and the two ends of the cold side are respectively connected to the low-temperature molten salt storage tank and the high-temperature molten salt storage tank; the hot side of the first heat exchanger is passed through high-temperature flue gas to exchange heat with the low-temperature molten salt on its cold side; An electric heating element is provided on the second molten salt heat storage passage for heating the low-temperature molten salt in the low-temperature molten salt storage tank; A second heat exchanger is arranged on the first molten salt heat release passage, and both ends of the hot side of the second heat exchanger are connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank respectively, and the high-temperature molten salt is used to heat the feed water on the cold side of the second heat exchanger to supply steam. It also includes a nitrogen supply part, which is connected to the high-temperature molten salt storage tank and the low-temperature molten salt storage tank respectively and is used to fill nitrogen. The nitrogen supply member includes a first gas connecting pipe, and the first gas connecting pipe is used to connect the high-temperature molten salt storage tank and the low-temperature molten salt storage tank to achieve gas flow between the two. A molten salt buffer tank is also provided on the first molten salt heat storage passage. In the molten salt flow direction, the molten salt buffer tank is provided upstream of the first heat exchanger.

2. The heat storage system according to claim 1, characterized in that: The molten salt buffer tank is connected to the nitrogen supply component, and the nitrogen supply component fills nitrogen into the molten salt buffer tank.

3. The heat storage system according to claim 2, characterized in that: The nitrogen supply component further includes a second gas connecting pipe, one end of which is connected to the molten salt buffer tank, and the other end of which is connected to the first gas connecting pipe.

4. The heat storage system according to claim 1, characterized in that: The high-temperature flue gas is selected from the exhaust gas in the gas turbine power generation process.

5. The heat storage system according to claim 3, characterized in that: The molten salt buffer tank is arranged at a higher position than the first heat exchanger.

6. The heat storage system according to claim 1, characterized in that: The first heat exchanger is a shell and tube structure, the high-temperature flue gas flows from bottom to top on the shell side of the shell and tube structure, and the molten salt flows from top to bottom on the tube side of the shell and tube structure.

7. A working method of a heat storage system based on a gas turbine, characterized in that: Using the heat storage system as described in any one of claims 1 to 6, comprising the following steps: When the first molten salt heat storage path starts to store heat, the low-temperature molten salt in the low-temperature molten salt storage tank enters the first heat exchanger to exchange heat with the high-temperature flue gas. The low-temperature molten salt is heated by the high-temperature flue gas to become high-temperature molten salt, and then enters the high-temperature molten salt storage tank for storage; When the second molten salt passage starts to store heat, the low-temperature molten salt in the low-temperature molten salt storage tank enters the electric heating element, and the low-temperature molten salt is heated by the electric heating element to become high-temperature molten salt, and then enters the high-temperature molten salt storage tank for storage; When the first molten salt heat release passage supplies steam to the outside, the high-temperature molten salt in the high-temperature molten salt storage tank enters the second heat exchanger, heats the feed water to make it steam or superheated steam for external supply, and the high-temperature molten salt after heat release becomes low-temperature molten salt, and then enters the low-temperature molten salt storage tank for storage.

Images