Power generation system coupled with two-stage steam ejector and thermal storage and method of operation

Abstract

The present application relates to coal-fired power generation technology field, disclose a kind of power generation system and operating method coupled two-stage steam ejector and heat storage, the present application is when the load reduction of power generation system, using high-pressure steam tank and low-pressure steam tank respectively extracts main steam and reheat steam to store, quickly reduce the steam amount of entering steam turbine, realize the rapid load reduction of power generation system.When the load increase of power generation system, steam in steam tank is used as the power steam source of steam ejector, using steam ejector to inject steam cylinder exhaust, the actual pressure of steam ejector outlet steam is higher than the steam pressure corresponding to the current load of boiler, and can greatly increase the steam amount of entering middle-pressure cylinder and low-pressure cylinder, so as to quickly increase the load of power generation system.The present application stores and stores steam by steam tank and uses steam ejector to inject steam cylinder exhaust, improves the load variation rate of power generation system, and realizes the operation of power generation system at very low load.

Description

Technical Field

[0001] This invention relates to the field of coal-fired power generation technology, specifically to a power generation system and operating method that couples a two-stage steam ejector and thermal storage, in order to improve the operational flexibility of the power generation system. Background Technology

[0002] In recent decades, electricity has become the world's fastest-growing form of energy consumption. Electricity demand fluctuates frequently across different seasons and even at different times of day. Furthermore, due to the rapid development of renewable energy generation technologies such as wind, solar, and biomass, electricity supply continues to exhibit unpredictable fluctuations. Renewable energy is difficult to predict and control due to climate and weather conditions. This problem can be mitigated by using fossil fuel power plants, particularly in China where over 70% of electricity is currently supplied by coal-fired power systems. These systems are forced to frequently participate in load shifting to balance electricity demand and supply. Therefore, improving the operational flexibility of coal-fired power systems is a significant challenge for my country's energy industry. Summary of the Invention

[0003] In order to overcome the problems existing in the prior art, the purpose of this invention is to provide a power generation system and operating method that couples a two-stage steam ejector and thermal storage, which enables the power generation system to operate at a lower load and increase the rate of load change, thereby improving the flexibility of the power generation system.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A power generation system coupling a two-stage steam ejector and thermal storage includes a coal-fired system and a steam thermal storage system. The coal-fired system includes a coal-fired boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a deaerator 6, a high-pressure heater 7, a low-pressure heater 8, a condenser 9, a condensate pump P1, a feedwater pump P2, a sixth valve V6, and an eighth valve V8. The main steam outlet of the coal-fired boiler 1 is connected to the inlet of the high-pressure cylinder 2; the reheat steam outlet of the coal-fired boiler 1 is connected to the inlet of the intermediate-pressure cylinder 3; the exhaust outlet of the high-pressure cylinder 2 is connected to the cold end inlet of the reheat steam of the coal-fired boiler 1 via the eighth valve V8; the extraction steam outlet of the high-pressure cylinder 2 is connected to the hot end inlet of the high-pressure heater 7; the exhaust outlet of the intermediate-pressure cylinder 3 is connected to the inlet of the low-pressure cylinder 4 via the sixth valve V6; and the extraction steam outlet of the intermediate-pressure cylinder 3 is connected to the hot end inlet of the high-pressure heater 7. The hot end inlet is connected; the steam extraction outlet of the intermediate pressure cylinder 3 is connected to the inlet of the deaerator 6; the outlet of the deaerator 6 is connected to the inlet of the feedwater pump P2; the outlet of the feedwater pump P2 is connected to the cold end inlet of the high pressure heater 7; the cold end outlet of the high pressure heater 7 is connected to the feedwater inlet of the coal-fired boiler 1; the steam extraction outlet of the low pressure cylinder 4 is connected to the hot end inlet of the low pressure heater 8; the exhaust outlet of the low pressure cylinder 4 is connected to the inlet of the condenser 9; the outlet of the condenser 9 is connected to the inlet of the condensate pump P1; the outlet of the condensate pump P1 is connected to the cold end inlet of the low pressure heater 8; the cold end outlet of the low pressure heater 8 is connected to the inlet of the deaerator 6; the high pressure cylinder 2, intermediate pressure cylinder 3, low pressure cylinder 4 and generator 5 share a common bearing connection;

[0006] The steam thermal storage system includes a high-pressure steam storage tank 10, a primary steam ejector 11, a low-pressure steam storage tank 12, a secondary steam ejector 13, a first valve V1, a second valve V2, a third valve V3, a fourth valve V4, a fifth valve V5, and a seventh valve V7. The main steam outlet of the coal-fired boiler 1 is connected to the inlet of the high-pressure steam storage tank 10 via the first valve V1. The outlet of the high-pressure steam storage tank 10 is connected to the power steam inlet of the primary steam ejector 11 via the third valve V3. The exhaust outlet of the high-pressure cylinder 2 is connected to the primary steam ejector 11 via the fourth valve V4. The first-stage steam ejector 11 is connected to the extraction end of the steam; the steam outlet of the first-stage steam ejector 11 is connected to the inlet of the intermediate-pressure cylinder 3; the reheat steam outlet of the coal-fired boiler 1 is connected to the inlet of the low-pressure steam storage tank 12 through the second valve V2; the outlet of the low-pressure steam storage tank 12 is connected to the power steam inlet of the second-stage steam ejector 13 through the fifth valve V5; the exhaust port of the intermediate-pressure cylinder 3 is connected to the extraction end of the second-stage steam ejector 13 through the seventh valve V7; and the steam outlet of the second-stage steam ejector 13 is connected to the inlet of the low-pressure cylinder 4.

[0007] A main steam distributor F1 is installed between the main steam outlet of the coal-fired boiler 1 and the inlet of the high-pressure steam storage tank 10 and the inlet of the high-pressure cylinder 2; a reheat steam distributor F2 is installed between the reheat steam outlet of the coal-fired boiler 1 and the inlet of the low-pressure steam storage tank 12 and the inlet of the intermediate-pressure cylinder 3; a high-pressure steam distributor F3 is installed between the exhaust end of the high-pressure cylinder 2 and the ejector end of the first-stage steam ejector 11 and the reheat steam cold end inlet of the coal-fired boiler 1; a low-pressure steam distributor F4 is installed between the exhaust end of the intermediate-pressure cylinder 3 and the ejector end of the second-stage steam ejector 13 and the inlet end of the low-pressure cylinder 4; a high-pressure steam combiner M1 is installed between the inlet end of the intermediate-pressure cylinder 3 and the steam outlet end of the first-stage steam ejector 11 and the reheat steam outlet of the coal-fired boiler 1; and a low-pressure steam combiner M2 is installed between the inlet end of the low-pressure cylinder 4 and the steam outlet end of the second-stage steam ejector 13 and the exhaust end of the intermediate-pressure cylinder 3.

[0008] The primary steam ejector 11 is powered by main steam, with a temperature range of 550–600℃ and a pressure greater than 10 MPa. The secondary steam ejector 13 is powered by reheat steam, with a temperature range of 550–600℃ and a pressure greater than 2 MPa.

[0009] The induced steam source for the first-stage steam ejector 11 is the exhaust steam from the high-pressure cylinder 2. The exhaust steam temperature range of the high-pressure cylinder 2 is 320-380℃, and the pressure is greater than 2MPa. The induced steam source for the second-stage steam ejector 13 is the exhaust steam from the intermediate-pressure cylinder 3. The exhaust steam temperature range of the intermediate-pressure cylinder 3 is 290-330℃, and the pressure is greater than 0.3MPa.

[0010] When the steam thermal storage system is in operation, the pressure of the main steam is adjusted by regulating the first valve V1 to keep the main steam within the safe operating range of the high-pressure steam storage tank, and the pressure of the reheat steam is adjusted by regulating the second valve V2 to keep the reheat steam within the safe operating range of the low-pressure steam storage tank.

[0011] When the steam storage system is releasing heat, the steam flow rate of the outlet steam of the first-stage steam ejector 11 can be adjusted by the third valve V3, and the actual pressure of the reheat steam entering the intermediate-pressure cylinder 3 should be higher than the reheat steam pressure corresponding to the current load of the boiler; the steam flow rate of the outlet steam of the second-stage steam ejector 13 can be adjusted by the fifth valve V5, and the actual pressure of the steam entering the low-pressure cylinder 4 should be higher than the steam pressure corresponding to the current load of the boiler.

[0012] The flow rate of exhaust steam from the high-pressure cylinder 2 into the extraction end of the first-stage steam ejector 11 is adjusted by regulating the opening of the fourth valve V4 and the eighth valve V8. The flow rate of exhaust steam from the intermediate-pressure cylinder 3 into the extraction end of the second-stage steam ejector 13 is adjusted by regulating the opening of the sixth valve V6 and the seventh valve V7, so that the pressure and temperature of the steam at the outlet of the first-stage steam ejector 11 and the second-stage steam ejector 13 are within the safe operating range of the cylinder.

[0013] When the power generation system needs to reduce load, the appropriate load reduction rate can be selected by choosing to open the second valve V2 and the first valve V1 sequentially or simultaneously, depending on the actual operating conditions. When the power generation system needs to increase load, the appropriate load increase rate can be selected by choosing to open the fifth valve V5, the seventh valve V7, the third valve V3, and the fourth valve V4 sequentially or simultaneously, depending on the actual operating conditions.

[0014] The operation method of the power generation system that couples two-stage steam ejectors and thermal storage is as follows: when the power generation system needs to be running normally and stably, only the coal-fired system is running, the thermal storage system is not running, and the first valve V1, the second valve V2, the third valve V3, the fourth valve V4 and the fifth valve V5 are closed, while the sixth valve V6 and the eighth valve V8 are opened.

[0015] When the power generation system needs to reduce load, the second valve V2 is opened first, and the reheat steam in the coal-fired boiler 1 enters the low-pressure steam storage tank 12 for storage through the second valve V2. If it is necessary to continue to reduce load, the first valve V1 is opened, and the main steam in the coal-fired boiler 1 enters the high-pressure steam storage tank 10 for storage through the first valve V1. During this operation, the third valve V3, the fourth valve V4 and the fifth valve V5 are all closed, and the sixth valve V6 and the eighth valve V8 are open.

[0016] When the power generation system needs to increase its load, firstly, open the fifth valve V5 and the seventh valve V7, and reduce the opening of the sixth valve V6. Low-pressure steam is released from the low-pressure steam storage tank 12 and enters the power steam inlet of the secondary steam ejector 13. Steam from the intermediate-pressure cylinder 3 is discharged into the ejector extraction end of the secondary steam ejector 13, and the outlet steam enters the low-pressure cylinder 4 to do work. If the power generation system needs to continue to increase its load, open the third valve V3 and the fourth valve V4, and reduce the opening of the eighth valve V8. High-pressure steam is released from the high-pressure steam storage tank 10 and enters the power steam inlet of the primary steam ejector 11. Steam from the high-pressure cylinder 2 is discharged into the ejector extraction end of the primary steam ejector 11, and the outlet steam enters the intermediate-pressure cylinder 3 to do work. This can significantly increase the amount of steam entering the intermediate-pressure cylinder 3 and the low-pressure cylinder 4, thereby rapidly increasing the load of the power generation system.

[0017] Compared with existing technologies, this invention has the following advantages: This invention adds a steam storage tank and a two-stage steam ejector. During load reduction operation of the power generation system, the high-pressure steam storage tank 10 and the low-pressure steam storage tank 12 respectively extract and store main steam and reheat steam, rapidly reducing the amount of steam entering the turbine and achieving rapid load reduction of the power generation system. During load increase of the power generation system, the steam in the steam storage tank is used as the power steam source for the steam ejector. The steam ejector is used to expel steam from the cylinder. The actual outlet steam pressure of the steam ejector is higher than the steam pressure corresponding to the current boiler load, and it can significantly increase the amount of steam entering the intermediate-pressure cylinder 3 and the low-pressure cylinder 4, thereby rapidly increasing the load of the power generation system. This invention improves the load change rate of the power generation system by storing and releasing steam in the steam storage tank and using the steam ejector to expel steam from the cylinder, and enables the power generation system to operate under extremely low load conditions. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the power generation system of the present invention, which couples a two-stage steam ejector and thermal storage.

[0019] In the diagram: 1. Coal-fired boiler; 2. High-pressure cylinder; 3. Medium-pressure cylinder; 4. Low-pressure cylinder; 5. Generator; 6. Deaerator; 7. High-pressure heater; 8. Low-pressure heater; 9. Condenser; 10. High-pressure steam storage tank; 11. First-stage steam ejector; 12. Low-pressure steam storage tank; 13. Second-stage steam ejector; P1. Condensate pump; P2. Feedwater pump; V1-V8. Valves; M1. High-pressure steam combiner; M2. Low-pressure steam combiner; F1. Main steam distributor; F2. Reheat steam distributor; F3. High-pressure steam distributor; F4. Low-pressure steam distributor. Detailed Implementation

[0020] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. The solutions in the embodiments are not intended to limit the scope of protection of the present invention. All equivalent implementations or modifications that do not depart from the present invention are included within the scope of protection of the present invention.

[0021] like Figure 1As shown, the present invention relates to a power generation system coupling a two-stage steam ejector and thermal storage, comprising a coal-fired system and a steam thermal storage system. The coal-fired system includes a coal-fired boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a deaerator 6, a high-pressure heater 7, a low-pressure heater 8, a condenser 9, a condensate pump P1, a feedwater pump P2, a sixth valve V6, and an eighth valve V8. The main steam outlet of the coal-fired boiler 1 is connected to the inlet of the high-pressure cylinder 2; the reheat steam outlet of the coal-fired boiler 1 is connected to the inlet of the intermediate-pressure cylinder 3; the exhaust outlet of the high-pressure cylinder 2 is connected to the cold end inlet of the reheat steam of the coal-fired boiler 1 via the eighth valve V8; the extraction steam outlet of the high-pressure cylinder 2 is connected to the hot end inlet of the high-pressure heater 7; the exhaust outlet of the intermediate-pressure cylinder 3 is connected to the inlet of the low-pressure cylinder 4 via the sixth valve V6; and the extraction steam outlet of the intermediate-pressure cylinder 3 is connected to the hot end inlet of the high-pressure heater 7. The hot end inlet is connected; the steam extraction outlet of the intermediate pressure cylinder 3 is connected to the inlet of the deaerator 6; the outlet of the deaerator 6 is connected to the inlet of the feedwater pump P2; the outlet of the feedwater pump P2 is connected to the cold end inlet of the high pressure heater 7; the cold end outlet of the high pressure heater 7 is connected to the feedwater inlet of the coal-fired boiler 1; the steam extraction outlet of the low pressure cylinder 4 is connected to the hot end inlet of the low pressure heater 8; the exhaust outlet of the low pressure cylinder 4 is connected to the inlet of the condenser 9; the outlet of the condenser 9 is connected to the inlet of the condensate pump P1; the outlet of the condensate pump P1 is connected to the cold end inlet of the low pressure heater 8; the cold end outlet of the low pressure heater 8 is connected to the inlet of the deaerator 6; the high pressure cylinder 2, intermediate pressure cylinder 3, low pressure cylinder 4 and generator 5 share a common bearing connection;

[0022] The steam thermal storage system includes a high-pressure steam storage tank 10, a primary steam ejector 11, a low-pressure steam storage tank 12, a secondary steam ejector 13, a first valve V1, a second valve V2, a third valve V3, a fourth valve V4, a fifth valve V5, and a seventh valve V7. The main steam outlet of the coal-fired boiler 1 is connected to the inlet of the high-pressure steam storage tank 10 via the first valve V1. The outlet of the high-pressure steam storage tank 10 is connected to the power steam inlet of the primary steam ejector 11 via the third valve V3. The exhaust outlet of the high-pressure cylinder 2 is connected to the primary steam ejector 11 via the fourth valve V4. The first-stage steam ejector 11 is connected to the extraction end of the steam; the steam outlet of the first-stage steam ejector 11 is connected to the inlet of the intermediate-pressure cylinder 3; the reheat steam outlet of the coal-fired boiler 1 is connected to the inlet of the low-pressure steam storage tank 12 through the second valve V2; the outlet of the low-pressure steam storage tank 12 is connected to the power steam inlet of the second-stage steam ejector 13 through the fifth valve V5; the exhaust port of the intermediate-pressure cylinder 3 is connected to the extraction end of the second-stage steam ejector 13 through the seventh valve V7; and the steam outlet of the second-stage steam ejector 13 is connected to the inlet of the low-pressure cylinder 4.

[0023] A main steam distributor F1 is installed between the main steam outlet of the coal-fired boiler 1 and the inlet of the high-pressure steam storage tank 10 and the inlet of the high-pressure cylinder 2; a reheat steam distributor F2 is installed between the reheat steam outlet of the coal-fired boiler 1 and the inlet of the low-pressure steam storage tank 12 and the inlet of the intermediate-pressure cylinder 3; a high-pressure steam distributor F3 is installed between the exhaust end of the high-pressure cylinder 2 and the ejector end of the first-stage steam ejector 11 and the reheat steam cold end inlet of the coal-fired boiler 1; a low-pressure steam distributor F4 is installed between the exhaust end of the intermediate-pressure cylinder 3 and the ejector end of the second-stage steam ejector 13 and the inlet end of the low-pressure cylinder 4; a high-pressure steam combiner M1 is installed between the inlet end of the intermediate-pressure cylinder 3 and the steam outlet end of the first-stage steam ejector 11 and the reheat steam outlet of the coal-fired boiler 1; and a low-pressure steam combiner M2 is installed between the inlet end of the low-pressure cylinder 4 and the steam outlet end of the second-stage steam ejector 13 and the exhaust end of the intermediate-pressure cylinder 3.

[0024] The primary steam ejector 11 is powered by main steam, with a temperature range of 550–600℃ and a pressure greater than 10 MPa. The secondary steam ejector 13 is powered by reheat steam, with a temperature range of 550–600℃ and a pressure greater than 2 MPa.

[0025] The induced steam source for the first-stage steam ejector 11 is the exhaust steam from the high-pressure cylinder 2. The exhaust steam temperature range of the high-pressure cylinder 2 is 320-380℃, and the pressure is greater than 2MPa. The induced steam source for the second-stage steam ejector 13 is the exhaust steam from the intermediate-pressure cylinder 3. The exhaust steam temperature range of the intermediate-pressure cylinder 3 is 290-330℃, and the pressure is greater than 0.3MPa.

[0026] When the steam thermal storage system is in operation, the pressure of the main steam is adjusted by regulating the first valve V1 to keep the main steam within the safe operating range of the high-pressure steam storage tank, and the pressure of the reheat steam is adjusted by regulating the second valve V2 to keep the reheat steam within the safe operating range of the low-pressure steam storage tank.

[0027] When the steam storage system is releasing heat, the steam flow rate of the outlet steam of the first-stage steam ejector 11 can be adjusted by the third valve V3, and the actual pressure of the reheat steam entering the intermediate-pressure cylinder 3 should be higher than the reheat steam pressure corresponding to the current load of the boiler; the steam flow rate of the outlet steam of the second-stage steam ejector 13 can be adjusted by the fifth valve V5, and the actual pressure of the steam entering the low-pressure cylinder 4 should be higher than the steam pressure corresponding to the current load of the boiler.

[0028] The flow rate of exhaust steam from the high-pressure cylinder 2 into the extraction end of the first-stage steam ejector 11 is adjusted by regulating the opening of the fourth valve V4 and the eighth valve V8. The flow rate of exhaust steam from the intermediate-pressure cylinder 3 into the extraction end of the second-stage steam ejector 13 is adjusted by regulating the opening of the sixth valve V6 and the seventh valve V7, so that the pressure and temperature of the steam at the outlet of the first-stage steam ejector 11 and the second-stage steam ejector 13 are within the safe operating range of the cylinder.

[0029] When the power generation system needs to reduce load, the appropriate load reduction rate can be selected by choosing to open the second valve V2 and the first valve V1 sequentially or simultaneously, depending on the actual operating conditions. When the power generation system needs to increase load, the appropriate load increase rate can be selected by choosing to open the fifth valve V5, the seventh valve V7, the third valve V3, and the fourth valve V4 sequentially or simultaneously, depending on the actual operating conditions.

[0030] When the power generation system needs to operate normally and stably, only the coal-fired system is in operation, the thermal storage system is not in operation, and the first valve V1, the second valve V2, the third valve V3, the fourth valve V4 and the fifth valve V5 are closed, while the sixth valve V6 and the eighth valve V8 are opened.

[0031] When the power generation system needs to reduce load, the second valve V2 is opened first, and the reheat steam in the coal-fired boiler 1 enters the low-pressure steam storage tank 12 for storage through the second valve V2. If it is necessary to continue to reduce load, the first valve V1 is opened, and the main steam in the coal-fired boiler 1 enters the high-pressure steam storage tank 10 for storage through the first valve V1. During this operation, the third valve V3, the fourth valve V4 and the fifth valve V5 are all closed, and the sixth valve V6 and the eighth valve V8 are open.

[0032] When the power generation system needs to increase its load, firstly, open valves V5 and V7, and reduce the opening of valve V6. Low-pressure steam is released from low-pressure storage tank 12 and enters the power steam inlet of the secondary steam ejector 13. Steam from intermediate-pressure cylinder 3 is discharged into the ejector extraction end of the secondary steam ejector 13, and the outlet steam enters low-pressure cylinder 4 to perform work. If the power generation system needs to continue increasing its load, open valves V3 and V4, and reduce the opening of valve V8. High-pressure steam is released from high-pressure storage tank 10 and enters the power steam inlet of the primary steam ejector 11. Steam from high-pressure cylinder 2 is discharged into the ejector extraction end of the primary steam ejector 11, and the outlet steam enters intermediate-pressure cylinder 3 to perform work. By following these steps, the amount of steam entering intermediate-pressure cylinder 3 and low-pressure cylinder 4 can be significantly increased, thereby rapidly increasing the load of the power generation system.

Claims

1. A power generation system coupling a two-stage steam ejector and thermal storage, characterized in that, Including coal-fired systems and steam thermal storage systems; The coal-fired system includes a coal-fired boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), a generator (5), a deaerator (6), a high-pressure heater (7), a low-pressure heater (8), a condenser (9), a condensate pump (P1), a feedwater pump (P2), a sixth valve (V6), and an eighth valve (V8). The main steam outlet of the coal-fired boiler (1) is connected to the inlet of the high-pressure cylinder (2). The reheat steam outlet of the coal-fired boiler (1) is connected to the inlet of the medium-pressure cylinder (3). The exhaust outlet of the high-pressure cylinder (2) is connected to the cold end inlet of the reheat steam of the coal-fired boiler (1) through the eighth valve (V8). The extraction steam outlet of the high-pressure cylinder (2) is connected to the hot end inlet of the high-pressure heater (7). The exhaust steam outlet of the medium-pressure cylinder (3) is connected to the inlet of the low-pressure cylinder (4) through the sixth valve (V6). The extraction steam outlet of the medium-pressure cylinder (3) is connected to the high-pressure heater. The hot end inlet of the generator (7) is connected; the extraction outlet of the intermediate pressure cylinder (3) is connected to the inlet of the deaerator (6); the outlet of the deaerator (6) is connected to the inlet of the feed water pump (P2); the outlet of the feed water pump (P2) is connected to the cold end inlet of the high pressure heater (7); the cold end outlet of the high pressure heater (7) is connected to the feed water inlet of the coal-fired boiler (1); the extraction outlet of the low pressure cylinder (4) is connected to the hot end inlet of the low pressure heater (8); the exhaust outlet of the low pressure cylinder (4) is connected to the inlet of the condenser (9); the outlet of the condenser (9) is connected to the inlet of the condensate pump (P1); the outlet of the condensate pump (P1) is connected to the cold end inlet of the low pressure heater (8); the cold end outlet of the low pressure heater (8) is connected to the inlet of the deaerator (6); the high pressure cylinder (2), the intermediate pressure cylinder (3), the low pressure cylinder (4) and the generator (5) share a common bearing connection; The steam thermal storage system includes a high-pressure steam tank (10), a primary steam ejector (11), a low-pressure steam tank (12), a secondary steam ejector (13), a first valve (V1), a second valve (V2), a third valve (V3), a fourth valve (V4), a fifth valve (V5), and a seventh valve (V7). The main steam outlet of the coal-fired boiler (1) is connected to the inlet of the high-pressure steam tank (10) through the first valve (V1); the outlet of the high-pressure steam tank (10) is connected to the power steam inlet of the primary steam ejector (11) through the third valve (V3); the exhaust outlet of the high-pressure cylinder (2) is connected to the fourth valve (V7). 4) Connected to the ejector end of the first-stage steam ejector (11); the steam outlet end of the first-stage steam ejector (11) is connected to the inlet of the intermediate-pressure cylinder (3); the reheat steam outlet end of the coal-fired boiler (1) is connected to the inlet of the low-pressure steam storage tank (12) through the second valve (V2); the outlet of the low-pressure steam storage tank (12) is connected to the power steam inlet end of the second-stage steam ejector (13) through the fifth valve (V5); the exhaust port of the intermediate-pressure cylinder (3) is connected to the ejector end of the second-stage steam ejector (13) through the seventh valve (V7); the steam outlet end of the second-stage steam ejector (13) is connected to the inlet of the low-pressure cylinder (4).

2. The power generation system coupling a two-stage steam ejector and thermal storage according to claim 1, characterized in that, A main steam splitter (F1) is installed between the main steam outlet of the coal-fired boiler (1) and the inlet of the high-pressure steam storage tank (10) and the inlet of the high-pressure cylinder (2); a reheat steam splitter (F2) is installed between the reheat steam outlet of the coal-fired boiler (1) and the inlet of the low-pressure steam storage tank (12) and the inlet of the intermediate-pressure cylinder (3); a high-pressure steam splitter (F3) is installed between the exhaust end of the high-pressure cylinder (2) and the ejector steam extraction end of the first-stage steam ejector (11) and the reheat steam cold end inlet of the coal-fired boiler (1); A low-pressure steam separator (F4) is installed between the exhaust end of the pressure cylinder (3), the extraction end of the secondary steam ejector (13), and the inlet end of the low-pressure cylinder (4); a high-pressure steam combiner (M1) is installed between the inlet end of the intermediate-pressure cylinder (3), the steam outlet end of the primary steam ejector (11), and the reheat steam outlet of the coal-fired boiler (1); and a low-pressure steam combiner (M2) is installed between the inlet end of the low-pressure cylinder (4), the steam outlet end of the secondary steam ejector (13), and the exhaust end of the intermediate-pressure cylinder (3).

3. The power generation system coupling a two-stage steam ejector and thermal storage according to claim 1, characterized in that, The primary steam ejector (11) is powered by main steam, with a temperature range of 550-600℃ and a pressure greater than 10MPa. The secondary steam ejector (13) is powered by reheat steam, with a temperature range of 550-600℃ and a pressure greater than 2MPa.

4. The power generation system coupling a two-stage steam ejector and thermal storage according to claim 1, characterized in that, The source of the ejector steam for the first-stage steam ejector (11) is the exhaust steam from the high-pressure cylinder (2). The exhaust steam temperature range of the high-pressure cylinder (2) is 320-380℃ and the pressure is greater than 2MPa. The source of the ejector steam for the second-stage steam ejector (13) is the exhaust steam from the medium-pressure cylinder (3). The exhaust steam temperature range of the medium-pressure cylinder (3) is 290-330℃ and the pressure is greater than 0.3MPa.

5. The power generation system coupled with a two-stage steam ejector and thermal storage according to claim 1, characterized in that, When the steam thermal storage system is in operation, the pressure of the main steam is adjusted by adjusting the first valve (V1) to keep the main steam within the safe operating range of the high-pressure steam storage tank, and the pressure of the reheat steam is adjusted by adjusting the second valve (V2) to keep the reheat steam within the safe operating range of the low-pressure steam storage tank (12).

6. The power generation system coupling a two-stage steam ejector and thermal storage according to claim 1, characterized in that, When the steam storage system is running, the steam outlet of the first-stage steam ejector (11) is regulated by the third valve (V3), and the actual pressure of the reheat steam entering the intermediate-pressure cylinder (3) is higher than the reheat steam pressure corresponding to the current load of the coal-fired boiler (1); the steam outlet of the second-stage steam ejector (13) is regulated by the fifth valve (V5), and the actual pressure of the steam entering the low-pressure cylinder (4) is higher than the steam pressure corresponding to the current load of the coal-fired boiler (1).

7. The power generation system coupled with a two-stage steam ejector and thermal storage according to claim 1, characterized in that, The flow rate of exhaust steam from the high-pressure cylinder (2) into the ejector end of the first-stage steam ejector (11) is adjusted by regulating the opening of the fourth valve (V4) and the eighth valve (V8). The flow rate of exhaust steam from the intermediate-pressure cylinder (3) into the ejector end of the second-stage steam ejector (13) is adjusted by regulating the opening of the sixth valve (V6) and the seventh valve (V7). This ensures that the pressure and temperature of the steam at the outlets of the first-stage steam ejector (11) and the second-stage steam ejector (13) are within the safe operating range of the cylinder.

8. The power generation system coupled with a two-stage steam ejector and thermal storage according to claim 1, characterized in that, When the power generation system needs to reduce load, the load reduction rate is selected by choosing to open the second valve (V2) and the first valve (V1) sequentially or simultaneously, depending on the actual operating conditions. When the power generation system needs to increase load, the load increase rate is selected by choosing to open the fifth valve (V5), the seventh valve (V7), the third valve (V3), and the fourth valve (V4) sequentially or simultaneously, depending on the actual operating conditions.

9. The method of operating the power generation system of coupled two-stage steam ejectors and thermal storage as described in any one of claims 1 to 8, characterized in that, When the power generation system needs to operate normally and stably, only the coal-fired system is operated, the steam thermal storage system is not operated, and the first valve (V1), the second valve (V2), the third valve (V3), the fourth valve (V4) and the fifth valve (V5) are closed, while the sixth valve (V6) and the eighth valve (V8) are opened. When the power generation system needs to reduce load, the second valve (V2) is opened first, and the reheat steam in the coal-fired boiler (1) enters the low-pressure steam storage tank (12) through the second valve (V2) for storage. If the load needs to be reduced further, the first valve (V1) is opened, and the main steam in the coal-fired boiler (1) enters the high-pressure steam storage tank (10) through the first valve (V1) for storage. During this operation, the third valve (V3), the fourth valve (V4) and the fifth valve (V5) are all closed, and the sixth valve (V6) and the eighth valve (V8) are open. When the power generation system needs to increase its load, first open the fifth valve (V5) and the seventh valve (V7), and reduce the opening of the sixth valve (V6). Low-pressure steam is released from the low-pressure steam tank (12) and enters the power steam inlet of the secondary steam ejector (13). Steam from the intermediate-pressure cylinder (3) enters the ejector extraction end of the secondary steam ejector (13), and the outlet steam enters the low-pressure cylinder (4) to do work. If the power generation system needs to continue to increase its load, open the third valve (V3) and the fourth valve (V4), and reduce the opening of the eighth valve (V8). High-pressure steam is released from the high-pressure steam tank (10) and enters the power steam inlet of the primary steam ejector (11). Steam from the high-pressure cylinder (2) enters the ejector extraction end of the primary steam ejector (11), and the outlet steam enters the intermediate-pressure cylinder (3) to do work. This can greatly increase the amount of steam entering the intermediate-pressure cylinder (3) and the low-pressure cylinder (4), thereby rapidly increasing the load of the power generation system.

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