A supercritical carbon dioxide heat storage and power generation integrated system and operation method

Abstract

The present invention discloses an integrated system for supercritical carbon dioxide energy storage and power generation and an operation method thereof. The system adopts a supercritical carbon dioxide recompression and reheating cycle, and also includes a heat storage system composed of high- and low-temperature molten salt storage tanks, a No. 2 molten salt heat exchanger, a molten salt-flue gas heat exchanger, a split turbine, and an intermediate temperature recuperator, and a heat release system composed of high- and low-temperature molten salt storage tanks and a No. 1 molten salt heat exchanger. During heat storage, on the premise of maintaining the minimum stable combustion load of the boiler, part of the flue gas and turbine working medium are diverted to heat the molten salt, so as to reduce the working medium flow rate on the circulation side to further reduce the unit output power, and at the same time store the high-temperature heat in the molten salt storage tank; during heat release, the heat stored in the molten salt tank is released to heat part of the working medium diverted at the inlet of the high-temperature recuperator, and then flows into the high-pressure turbine, which can increase the unit output power without changing the boiler load. The present invention can broaden the operation load range of coal-fired units, improve the flexibility of the system, and enhance the ability to assist the power grid in peak shaving and frequency modulation.

Description

Technical Field

[0001] The present invention belongs to the technical field of power generation, and particularly relates to a supercritical carbon dioxide energy storage and power generation integrated system and an operation method thereof. Background Art

[0002] At present, most coal-fired power generation systems adopt the steam Rankine cycle. According to the Rankine cycle principle, increasing the steam parameters can effectively improve the power generation efficiency. However, the production cost of nickel-based superalloys that can withstand high temperatures and pressures is relatively high, resulting in a large initial investment in coal-fired power plants, a long investment payback period, and poor technical economy. The supercritical carbon dioxide power cycle based on the Brayton cycle principle is a new cycle with great potential for use in coal-fired power generation, having advantages such as high efficiency and compactness.

[0003] With the proposal of the "dual carbon" strategic goal, higher requirements have been put forward for the flexibility of coal-fired power generation systems in China to adapt to the continuously increasing proportion of renewable energy power generation. The flexibility of coal-fired units mainly includes the variable load range, variable load rate, start-stop time, etc. However, for supercritical carbon dioxide coal-fired power generation systems, they are also restricted by the minimum stable combustion load of the boiler, the energy flow coupling of the boiler-turbine, and have insufficient operation flexibility. Summary of the Invention

[0004] In order to further reduce the minimum operating load of coal-fired units, broaden the variable load range, and increase the variable load rate, the present invention proposes a supercritical carbon dioxide energy storage and power generation integrated system and an operation method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A supercritical carbon dioxide energy storage and power generation integrated system, comprising a recompression and reheating power generation system, an energy storage system, and a heat release system;

[0007] The recompression and reheating power generation system includes a high-pressure turbine 7, a low-pressure turbine 8, a recompressor 10, a main compressor 11, a cooler 12, a low-temperature recuperator 13, a high-temperature recuperator 15, and a boiler 16; the outlet of the main compressor 11 is connected to the inlet of the cold side of the low-temperature recuperator 13, the outlet of the cold side of the low-temperature recuperator 13 is connected to the inlet of the cold side of the high-temperature recuperator 15, the outlet of the cold side of the high-temperature recuperator 15 is connected to the boiler 16, the working medium at the outlet of the boiler 16 is connected to the high-pressure turbine 7, the reheated working medium at the outlet of the high-pressure turbine 7 is connected to the boiler 16, the reheated working medium at the outlet of the boiler 16 is connected to the low-pressure turbine 8, the outlet of the low-pressure turbine 8 is sequentially connected to the hot side of the high-temperature recuperator 15 and the hot side of the low-temperature recuperator 13, the outlet of the hot side of the low-temperature recuperator 13 is respectively connected to the inlet of the recompressor 10 and the inlet of the cooler 12, the outlet of the recompressor 10 is connected to the outlet of the cold side of the low-temperature recuperator 13, and the outlet of the cooler 12 is connected to the inlet of the main compressor 11; the inlet of the cold side of the high-temperature recuperator 15 is further connected to the inlet of the tail of the boiler 16, and the working medium at the outlet of the tail of the boiler 16 is connected to the outlet of the cold side of the high-temperature recuperator 15;

[0008] The heat storage system includes a low-temperature molten salt tank 2, a high-temperature molten salt tank 3, a No. 2 molten salt heat exchanger 4, a bypass turbine 9, and a medium-temperature recuperator 14; the inlet of the hot side of the No. 2 molten salt heat exchanger 4 is connected to the inlet of the high-pressure turbine 7, the outlet of the hot side of the No. 2 molten salt heat exchanger 4 is connected to the inlet of the bypass turbine 9, the outlet of the bypass turbine 9 is connected to the inlet of the hot side of the medium-temperature recuperator 14, the outlet of the hot side of the medium-temperature recuperator 14 is connected to the inlet of the hot side of the low-temperature recuperator 13, the inlet of the cold side of the medium-temperature recuperator 14 is connected to the outlet of the cold side of the low-temperature recuperator 13, and the outlet of the cold side of the medium-temperature recuperator 14 is connected to the inlet of the working medium at the tail of the boiler 16; the inlet of the cold side of the No. 2 molten salt heat exchanger 4 is connected to the outlet of the low-temperature molten salt tank 2, and the outlet of the cold side of the No. 2 molten salt heat exchanger 4 is connected to the inlet of the high-temperature molten salt tank 3;

[0009] The heat release system includes a No. 1 molten salt heat exchanger 1, the inlet of the hot side of the No. 1 molten salt heat exchanger 1 is connected to the outlet of the high-temperature molten salt tank 3, and the outlet of the hot side of the No. 1 molten salt heat exchanger 1 is connected to the inlet of the low-temperature molten salt tank 2; the inlet of the cold side of the No. 1 molten salt heat exchanger 1 is connected to the outlet of the working medium at the tail of the boiler 16, and the outlet of the cold side of the No. 1 molten salt heat exchanger 1 is connected to the inlet of the high-pressure turbine 7.

[0010] A molten salt-gas heat exchanger 5 is arranged in the boiler 16, the molten salt inlet of the molten salt-gas heat exchanger 5 is connected to the outlet of the low-temperature molten salt tank 2, and the molten salt outlet of the molten salt-gas heat exchanger 5 is connected to the inlet of the high-temperature molten salt tank 3.

[0011] A bypass flue baffle 6 is arranged in the boiler 16 to realize a flue bypass, and a gas-molten salt heat exchanger 5 is arranged in the bypass flue.

[0012] A first valve 171 is provided on the connecting pipeline between the high-temperature molten salt tank 3 and the No. 1 molten salt heat exchanger 1. A second valve 172 is provided on the connecting pipeline between the low-temperature molten salt tank 2 and the molten salt-flue gas heat exchanger 5. A third valve 173 is provided on the connecting pipeline between the No. 2 molten salt heat exchanger 4 and the high-pressure turbine 7. A fourth valve 174 is provided on the connecting pipeline between the tail outlet of the boiler 16 and the No. 1 molten salt heat exchanger 1. A fifth valve 175 is provided on the connecting pipeline between the tail outlet of the boiler 16 and the cold-side outlet of the high-temperature recuperator 15. A sixth valve 176 is provided on the connecting pipeline between the tail inlet of the boiler 16 and the cold-side inlet of the high-temperature recuperator 15. A seventh valve 177 is provided on the connecting pipeline between the cold-side outlet of the low-temperature recuperator 13 and the cold-side inlet of the medium-temperature recuperator 14.

[0013] The inlet temperature of the main compressor 11 is 32 - 42 °C.

[0014] The inlet pressure of the main compressor 11 is 7.5 - 9.0 MPa.

[0015] An operation method of a supercritical carbon dioxide heat storage power generation integrated system includes a normal operation mode, a heat storage operation mode, and a heat release operation mode;

[0016] In the normal operation mode, all valves and the shunt flue damper 6 are in the default closed state. The high-temperature and high-pressure carbon dioxide working medium at the outlet of the boiler 16 enters the high-pressure turbine 7 to do work. The working medium at the outlet of the high-pressure turbine 7 is reheated by the boiler 16 and then enters the low-pressure turbine 8 to do work. The working medium at the outlet of the low-pressure turbine 8 is sequentially released heat through the high-temperature recuperator 15 and the low-temperature recuperator 13 and is divided into two parts: one part is compressed and boosted by the recompressor 10; the other part is cooled by the cooler 12 and then enters the main compressor 11 to be compressed and boosted. The working medium at the outlet of the main compressor 11 enters the low-temperature recuperator 13 for heating. The working medium at the cold-side outlet of the low-temperature recuperator 13 converges with the working medium at the outlet of the recompressor 10, is heated by the high-temperature recuperator 15, and then enters the boiler; the fifth valve 175 and the sixth valve 176 are opened to form a shunt before the cold-side inlet of the high-temperature recuperator 15, and a part of the working medium is shunted to enter the tail of the boiler 16 to absorb the heat of the medium- and low-temperature flue gas and converges at the connection between the cold-side outlet of the high-temperature recuperator 15 and the boiler 16;

[0017] In the heat storage operation mode, based on the normal operation mode, the shunt flue damper 6 is opened, the second valve 172, the third valve 173, and the seventh valve 177 are opened, and the sixth valve 176 is closed; a bypass flue is formed inside the boiler 16 to shunt part of the flue gas to heat the molten salt from the low-temperature molten salt tank 2. The molten salt is heated to a high temperature state and stored in the high-temperature molten salt tank 3; similarly, a part of the working medium at the inlet of the high-pressure turbine 7 is shunted to heat the molten salt from the low-temperature molten salt tank 2 in the No. 2 molten salt heat exchanger 4. The molten salt is heated to a high temperature state and stored in the high-temperature molten salt tank 3;

[0018] In the heat release operation mode, based on the conventional operation mode, the fifth valve 175 is closed, and the first valve 171 and the fourth valve 174 are opened; the high-temperature molten salt stored in the high-temperature molten salt tank 3 is released into the first molten salt heat exchanger 1 to heat the working medium from the tail outlet of the boiler 16. After heat release, the low-temperature molten salt returns to be stored in the low-temperature molten salt tank 2, and the working medium heated in the first molten salt heat exchanger 1 flows into the inlet of the high-pressure turbine 7.

[0019] In the heat storage operation mode, the carbon dioxide working medium at the outlet of the second molten salt heat exchanger 4 enters the split turbine 9 to expand and do work, while reducing the pressure. The working medium at the outlet of the split turbine 9 heats the split working medium at the cold side outlet of the low-temperature recuperator 13 in the intermediate-temperature recuperator 14. After the working medium at the cold side outlet of the intermediate-temperature recuperator 14 absorbs heat at the tail of the boiler 16, it flows into the cold side outlet of the high-temperature recuperator 15, and the working medium at the hot side outlet of the intermediate-temperature recuperator 14 flows into the hot side inlet of the low-temperature recuperator 13.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) The present invention is based on the supercritical carbon dioxide Brayton recompression cycle, which can improve the efficiency of coal-fired power generation units.

[0022] 2) The present invention integrates a heat storage system, which can reduce the working medium on the power generation side of the cycle through heat storage, thereby reducing the minimum operating load of the coal-fired power generation unit. Or, it can increase the output power of the unit without changing the boiler load by heat release, and broaden the variable load range of the unit.

[0023] 3) The present invention can quickly reduce the flow rate entering the high- and low-pressure turbines when the unit reduces the load, and improve the variable load rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the supercritical carbon dioxide heat storage power generation integrated system of the present invention.

[0025] FIG. 2(a) is a schematic diagram of the conventional operation mode of the supercritical carbon dioxide heat storage power generation integrated system.

[0026] FIG. 2(b) is a schematic diagram of the heat storage operation mode of the supercritical carbon dioxide heat storage power generation integrated system.

[0027] FIG. 2(c) is a schematic diagram of the heat release operation mode of the supercritical carbon dioxide heat storage power generation integrated system. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0029] As Figure 1A supercritical carbon dioxide heat storage and power generation integrated system shown in the figure includes a recompression and reheating power generation system, a heat storage system, and a heat release system; the recompression and reheating power generation system includes a high-pressure turbine 7, a low-pressure turbine 8, a recompressor 10, a main compressor 11, a cooler 12, a low-temperature recuperator 13, a high-temperature recuperator 15, and a boiler 16; the outlet of the main compressor 11 is connected to the cold-side inlet of the low-temperature recuperator 13, the cold-side outlet of the low-temperature recuperator 13 is connected to the cold-side inlet of the high-temperature recuperator 15, the cold-side outlet of the high-temperature recuperator 15 is connected to the boiler 16, the working medium at the outlet of the boiler 16 is connected to the high-pressure turbine 7, the reheated working medium at the outlet of the high-pressure turbine 7 is connected to the boiler 16, the reheated working medium at the outlet of the boiler 16 is connected to the low-pressure turbine 8, the outlet of the low-pressure turbine 8 is sequentially connected to the hot side of the high-temperature recuperator 15 and the hot side of the low-temperature recuperator 13, the hot-side outlet of the low-temperature recuperator 13 is respectively connected to the inlet of the recompressor 10 and the inlet of the cooler 12, the outlet of the recompressor 10 is connected to the cold-side outlet of the low-temperature recuperator 13, and the outlet of the cooler 12 is connected to the inlet of the main compressor 11; the cold-side inlet of the high-temperature recuperator 15 is also connected to the inlet at the tail of the boiler 16, and the outlet at the tail of the boiler 16 is connected to the cold-side outlet of the high-temperature recuperator 15;

[0030] The heat storage system includes a low-temperature molten salt tank 2, a high-temperature molten salt tank 3, a No. 2 molten salt heat exchanger 4, a bypass turbine 9, and a medium-temperature recuperator 14; a molten salt-gas heat exchanger 5 is arranged in the boiler 16, and the molten salt inlet of the molten salt-gas heat exchanger 5 is connected to the outlet of the low-temperature molten salt tank 2, and the molten salt outlet of the molten salt-gas heat exchanger 5 is connected to the inlet of the high-temperature molten salt tank 3; the outlet of the low-temperature molten salt tank 2 is also connected to the cold-side inlet of the No. 2 molten salt heat exchanger 4, the inlet of the high-temperature molten salt tank 3 is also connected to the cold-side outlet of the No. 2 molten salt heat exchanger 4, the hot-side inlet of the No. 2 molten salt heat exchanger 4 is connected to the inlet of the high-pressure turbine 7, the hot-side outlet of the No. 2 molten salt heat exchanger 4 is connected to the inlet of the bypass turbine 9, the outlet of the bypass turbine 9 is connected to the hot-side inlet of the medium-temperature recuperator 14, the hot-side outlet of the medium-temperature recuperator 14 is connected to the hot-side inlet of the low-temperature recuperator 13, the cold-side inlet of the medium-temperature recuperator 14 is connected to the cold-side outlet of the low-temperature recuperator 13, and the cold-side outlet of the medium-temperature recuperator 14 is connected to the working medium inlet at the tail of the boiler 16;

[0031] The heat release system includes a No. 1 molten salt heat exchanger 1, the hot-side inlet of the No. 1 molten salt heat exchanger 1 is connected to the outlet of the high-temperature molten salt tank 3, and the hot-side outlet of the No. 1 molten salt heat exchanger 1 is connected to the inlet of the low-temperature molten salt tank 2; the cold-side inlet of the No. 1 molten salt heat exchanger 1 is connected to the working medium outlet at the tail of the boiler 16, and the cold-side outlet of the No. 1 molten salt heat exchanger 1 is connected to the inlet of the high-pressure turbine 7.

[0032] A bypass flue baffle 6 is arranged in the boiler 16 to realize a flue bypass, and a gas-molten salt heat exchanger 5 is arranged in the bypass flue.

[0033] A first valve 171 is provided on the connecting pipeline between the high-temperature molten salt tank 3 and the No. 1 molten salt heat exchanger 1. A second valve 172 is provided on the connecting pipeline between the low-temperature molten salt tank 2 and the molten salt-flue gas heat exchanger 5. A third valve 173 is provided on the connecting pipeline between the No. 2 molten salt heat exchanger 4 and the high-pressure turbine 7. A fourth valve 174 is provided on the connecting pipeline between the tail outlet of the boiler 16 and the No. 1 molten salt heat exchanger 1. A fifth valve 175 is provided on the connecting pipeline between the tail outlet of the boiler 16 and the cold-side outlet of the high-temperature recuperator 15. A sixth valve 176 is provided on the connecting pipeline between the tail inlet of the boiler 16 and the cold-side inlet of the high-temperature recuperator 15. A seventh valve 177 is provided on the connecting pipeline between the cold-side outlet of the low-temperature recuperator 13 and the cold-side inlet of the medium-temperature recuperator 14.

[0034] The inlet temperature of the main compressor 11 is 32 - 42 °C; the inlet pressure of the main compressor 11 is 7.5 - 9.0 MPa.

[0035] An operation method of a supercritical carbon dioxide heat storage power generation integrated system: mainly including a normal operation mode, a heat storage operation mode and a heat release operation mode;

[0036] Normal operation mode: All valves and the shunt flue damper 6 are in the default closed state. The high-temperature and high-pressure carbon dioxide working medium at the outlet of the boiler 16 enters the high-pressure turbine 7 to do work. The working medium at the outlet of the high-pressure turbine 7 is reheated by the boiler 16 and then enters the low-pressure turbine 8 to do work. The working medium at the outlet of the low-pressure turbine 8 is divided into two parts after releasing heat through the high-temperature recuperator 15 and the low-temperature recuperator 13 in sequence: one part is compressed and boosted by the recompressor 10; the other part is cooled by the cooler 12 and then enters the main compressor 11 for compression and boosting. The working medium at the outlet of the main compressor 11 enters the low-temperature recuperator 13 for heating. The working medium at the cold-side outlet of the low-temperature recuperator 13 converges with the working medium at the outlet of the recompressor 10 and enters the boiler after being heated by the high-temperature recuperator 15. Open the fifth valve 175 and the sixth valve 176 to form a shunt before the cold-side inlet of the high-temperature recuperator 15, and divert a part of the working medium to enter the tail of the boiler 16 to absorb the heat of the medium- and low-temperature flue gas, and converge at the connection between the cold-side outlet of the high-temperature recuperator 15 and the boiler 16; The normal operation mode is shown in Figure 2(a);

[0037] Heat storage operation mode: On the basis of the conventional operation mode, open the bypass flue damper 6, open the second valve 172, the third valve 173 and the seventh valve 177, and close the sixth valve 176; form a bypass flue inside the boiler 16 to divert part of the flue gas to heat the molten salt from the low-temperature molten salt tank 2, and the molten salt is heated to a high temperature state and then stored in the high-temperature molten salt tank 3; similarly, divert part of the working medium at the inlet of the high-pressure turbine 7 to heat the molten salt from the low-temperature molten salt tank 2 in the 2nd molten salt heat exchanger 4, and the molten salt is heated to a high temperature state and then stored in the high-temperature molten salt tank 3. The carbon dioxide working medium at the outlet of the 2nd molten salt heat exchanger 4 enters the bypass turbine 9 to expand and do work, while reducing the pressure. The working medium at the outlet of the bypass turbine 9 heats the diverted working medium at the cold side outlet of the low-temperature regenerator 13 in the medium-temperature regenerator 14. After the working medium at the cold side outlet of the medium-temperature regenerator 14 absorbs heat at the tail of the boiler 16, it merges into the cold side outlet of the high-temperature regenerator 15, and the working medium at the hot side outlet of the medium-temperature regenerator 14 merges into the hot side inlet of the low-temperature regenerator 13; The heat storage operation mode is shown in Figure 2(b);

[0038] Heat release operation mode: On the basis of the conventional operation mode, close the fifth valve 175 and open the first valve 171 and the fourth valve 174; release the high-temperature molten salt stored in the high-temperature molten salt tank 3 to heat the working medium from the tail outlet of the boiler 16 in the 1st molten salt heat exchanger 1. The low-temperature molten salt after heat release returns to be stored in the low-temperature molten salt tank 2, and the working medium heated in the 1st molten salt heat exchanger 1 merges into the inlet of the high-pressure turbine 7; The heat release operation mode is shown in Figure 2(c).

Claims

1. An integrated system for supercritical carbon dioxide energy storage and power generation, characterized in that, It includes a recompression reheating power generation system, a heat storage system and a heat release system; The recompression reheating power generation system includes a high-pressure turbine (7), a low-pressure turbine (8), a recompressor (10), a main compressor (11), a cooler (12), a low-temperature recuperator (13), a high-temperature recuperator (15) and a boiler (16); the outlet of the main compressor (11) is connected to the cold-side inlet of the low-temperature recuperator (13), the cold-side outlet of the low-temperature recuperator (13) is connected to the cold-side inlet of the high-temperature recuperator (15), the cold-side outlet of the high-temperature recuperator (15) is connected to the boiler (16), the working medium at the outlet of the boiler (16) is connected to the high-pressure turbine (7), the reheated working medium at the outlet of the high-pressure turbine (7) is connected to the boiler (16), the reheated working medium at the outlet of the boiler (16) is connected to the low-pressure turbine (8), the outlet of the low-pressure turbine (8) is sequentially connected to the hot side of the high-temperature recuperator (15) and the hot side of the low-temperature recuperator (13), the hot-side outlet of the low-temperature recuperator (13) is respectively connected to the inlet of the recompressor (10) and the inlet of the cooler (12), the outlet of the recompressor (10) is connected to the cold-side outlet of the low-temperature recuperator (13), and the outlet of the cooler (12) is connected to the inlet of the main compressor (11); the cold-side inlet of the high-temperature recuperator (15) is also connected to the inlet of the tail part of the boiler (16), and the outlet of the tail part of the boiler (16) is connected to the cold-side outlet of the high-temperature recuperator (15); The heat storage system includes a low-temperature molten salt tank (2), a high-temperature molten salt tank (3), a No. 2 molten salt heat exchanger (4), a shunt turbine (9) and a medium-temperature recuperator (14); the hot-side inlet of the No. 2 molten salt heat exchanger (4) is connected to the inlet of the high-pressure turbine (7), the hot-side outlet of the No. 2 molten salt heat exchanger (4) is connected to the inlet of the shunt turbine (9), the outlet of the shunt turbine (9) is connected to the hot-side inlet of the medium-temperature recuperator (14), the hot-side outlet of the medium-temperature recuperator (14) is connected to the hot-side inlet of the low-temperature recuperator (13), the cold-side inlet of the medium-temperature recuperator (14) is connected to the cold-side outlet of the low-temperature recuperator (13), and the cold-side outlet of the medium-temperature recuperator (14) is connected to the inlet of the working medium at the tail part of the boiler (16); the cold-side inlet of the No. 2 molten salt heat exchanger (4) is connected to the outlet of the low-temperature molten salt tank (2), and the cold-side outlet of the No. 2 molten salt heat exchanger (4) is connected to the inlet of the high-temperature molten salt tank (3); The heat release system includes a No. 1 molten salt heat exchanger (1), the hot-side inlet of the No. 1 molten salt heat exchanger (1) is connected to the outlet of the high-temperature molten salt tank (3), and the hot-side outlet of the No. 1 molten salt heat exchanger (1) is connected to the inlet of the low-temperature molten salt tank (2); the cold-side inlet of the No. 1 molten salt heat exchanger (1) is connected to the outlet of the working medium at the tail part of the boiler (16), and the cold-side outlet of the No. 1 molten salt heat exchanger (1) is connected to the inlet of the high-pressure turbine (7).

2. The integrated supercritical carbon dioxide heat storage and power generation system according to claim 1, wherein A molten salt-gas heat exchanger (5) is arranged in the boiler (16), the molten salt inlet of the molten salt-gas heat exchanger (5) is connected to the outlet of the low-temperature molten salt tank (2), and the molten salt outlet of the molten salt-gas heat exchanger (5) is connected to the inlet of the high-temperature molten salt tank (3).

3. The integrated supercritical carbon dioxide energy storage and power generation system according to claim 2, wherein A shunt flue baffle (6) is arranged in the boiler (16) to realize a flue bypass, and the molten salt-gas heat exchanger (5) is arranged in the bypass flue.

4. A supercritical carbon dioxide heat storage and power generation integrated system according to claim 1, wherein A first valve (171) is provided on the connecting pipeline between the high-temperature molten salt tank (3) and the No. 1 molten salt heat exchanger (1), a second valve (172) is provided on the connecting pipeline between the low-temperature molten salt tank (2) and the molten salt - flue gas heat exchanger (5), a third valve (173) is provided on the connecting pipeline between the No. 2 molten salt heat exchanger (4) and the high-pressure turbine (7), a fourth valve (174) is provided on the connecting pipeline between the tail outlet of the boiler (16) and the No. 1 molten salt heat exchanger (1), a fifth valve (175) is provided on the connecting pipeline between the tail outlet of the boiler (16) and the cold-side outlet of the high-temperature recuperator (15), a sixth valve (176) is provided on the connecting pipeline between the tail inlet of the boiler (16) and the cold-side inlet of the high-temperature recuperator (15), and a seventh valve (177) is provided on the connecting pipeline between the cold-side outlet of the low-temperature recuperator (13) and the cold-side inlet of the medium-temperature recuperator (14).

5. The integrated supercritical carbon dioxide heat storage and power generation system according to claim 1, characterized in that The inlet temperature of the main compressor (11) is 32 - 42 °C.

6. The integrated supercritical carbon dioxide heat storage and power generation system according to claim 1, characterized in that, The inlet pressure of the main compressor (11) is 7.5 - 9.0 MPa.

7. A method for operating an integrated supercritical carbon dioxide heat storage and power generation system according to any one of claims 1 to 6, characterized in that, It includes a normal operation mode, a heat storage operation mode and a heat release operation mode; In the normal operation mode, all valves and the shunt flue damper (6) are in the default closed state. The high-temperature and high-pressure carbon dioxide working medium at the outlet of the boiler (16) enters the high-pressure turbine (7) to do work. After the working medium at the outlet of the high-pressure turbine (7) is reheated by the boiler (16), it enters the low-pressure turbine (8) to do work. The working medium at the outlet of the low-pressure turbine (8) is successively released heat through the high-temperature recuperator (15) and the low-temperature recuperator (13) and is divided into two parts: one part is compressed and boosted by the recompressor (10); The other part is cooled by the cooler (12) and then enters the main compressor (11) to be compressed and boosted. The working medium at the outlet of the main compressor (11) enters the low-temperature recuperator (13) for heating. The working medium at the cold-side outlet of the low-temperature recuperator (13) converges with the working medium at the outlet of the recompressor (10), and after being heated by the high-temperature recuperator (15), it enters the boiler; Open the fifth valve (175) and the sixth valve (176) to form a shunt before the cold-side inlet of the high-temperature recuperator (15), and divert a part of the working medium to enter the tail of the boiler (16) to absorb the heat of the medium- and low-temperature flue gas, and converge at the connection between the cold-side outlet of the high-temperature recuperator (15) and the boiler (16); In the heat storage operation mode, based on the normal operation mode, open the shunt flue damper (6), open the second valve (172), the third valve (173) and the seventh valve (177), and close the sixth valve (176); form a bypass flue inside the boiler (16) to divert part of the flue gas to heat the molten salt from the low-temperature molten salt tank (2). After the molten salt is heated to a high temperature state, it is stored in the high-temperature molten salt tank (3); similarly, divert part of the working medium at the inlet of the high-pressure turbine (7) to heat the molten salt from the low-temperature molten salt tank (2) in the No. 2 molten salt heat exchanger (4). After the molten salt is heated to a high temperature state, it is stored in the high-temperature molten salt tank (3); In the heat release operation mode, based on the conventional operation mode, the fifth valve (175) is closed, and the first valve (171) and the fourth valve (174) are opened; the high-temperature molten salt stored in the high-temperature molten salt tank (3) is released into the No. 1 molten salt heat exchanger (1) to heat the working medium from the tail outlet of the boiler (16). The low-temperature molten salt after heat release returns to the low-temperature molten salt tank (2) for storage, and the working medium heated in the No. 1 molten salt heat exchanger (1) flows into the inlet of the high-pressure turbine (7).

8. The operation method of a supercritical carbon dioxide heat storage and power generation integrated system according to claim 7, characterized in that, In the heat storage operation mode, the carbon dioxide working medium at the outlet of the No. 2 molten salt heat exchanger (4) enters the bypass turbine (9) to expand and do work, while reducing the pressure. The working medium at the outlet of the bypass turbine (9) heats the bypass working medium at the cold side outlet of the low-temperature recuperator (13) in the medium-temperature recuperator (14). After the working medium at the cold side outlet of the medium-temperature recuperator (14) absorbs heat at the tail of the boiler (16), it flows into the cold side outlet of the high-temperature recuperator (15). The working medium at the hot side outlet of the medium-temperature recuperator (14) flows into the hot side inlet of the low-temperature recuperator (13).

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