System and method for reducing start-up time of a unit using waste heat from a gas turbine cooling system

Abstract

The application discloses a system and method for shortening the starting time of a unit by utilizing waste heat of a gas turbine cooling system, and belongs to the technical field of energy-saving reconstruction of gas turbines. The outlet of a low-temperature economizer of a waste heat boiler is divided into two paths. One path is connected with the heat-releasing side of a natural gas preheater through a first electric valve, a low-flow medium-pressure feed water pump and the heat-absorbing side of a first turbine cooler. The other path is connected with the heat-absorbing side inlet of a second turbine cooler through a second electric valve, the heat-absorbing side outlet of the second turbine cooler is connected with the inlet of an electric heater, the outlet of an auxiliary steam header is connected with the inlet of the electric heater through a third electric valve, the outlet of the electric heater is connected with the outlet of a medium-pressure cylinder through a medium-pressure cylinder pre-warming valve, and the outlet of the electric heater is connected with the outlet of a high-pressure cylinder through a high-pressure cylinder pre-warming valve. The system and method can shorten the starting time of the unit and avoid the consumption of additional natural gas.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gas turbine energy-saving reconstruction, and relates to a system and method for shortening the starting time of a unit by using waste heat of a gas turbine cooling system. BACKGROUND

[0002] In a power generation system of a gas turbine combined with a steam turbine, the steam turbine can be directly connected to a grid and the load is increased only after the main steam and the reheated steam reach the requirements for rotation.

[0003] Publication No. CN110847984A discloses a supercritical carbon dioxide cycle coal-fired power generation system integrated with low-temperature waste heat recovery and an operation method, which comprises two-stage main compressors, an inter-stage cooler, a re-compressor, a pre-cooler, three-stage regenerators, a boiler, a high-pressure turbine, a medium-pressure turbine and a low-pressure turbine. The overheat gas cold wall and the primary reheater arranged in the furnace of the boiler jointly bear the radiation heat load of the furnace to prevent the overheat supercritical carbon dioxide from overheating. Part of the supercritical carbon dioxide working medium from the outlet of the medium-temperature regenerator is introduced into the boiler to absorb the heat of the high-temperature flue gas in the rear flue, and part of the supercritical carbon dioxide working medium from the outlet of the second-stage main compressor is introduced into the low-temperature economizer of the boiler tail to absorb the heat of the low-temperature flue gas.

[0004] The above prior art only recovers low-temperature waste heat, but the steam turbine needs to be preheated during the starting process. The preheating time of the steam turbine during the starting of the gas turbine is long, thereby prolonging the starting time of the unit and consuming additional natural gas. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a system and method for shortening the starting time of a unit by using waste heat of a gas turbine cooling system, which can shorten the starting time of the unit and avoid the consumption of additional natural gas.

[0006] To achieve the above purpose, the present application discloses a system for shortening the starting time of a unit by using waste heat of a gas turbine cooling system, which comprises a waste heat boiler, a natural gas preheater, a second turbine cooler, an electric heater, an auxiliary steam header, a medium-pressure cylinder and a high-pressure cylinder.

[0007] The outlet of the low-temperature economizer of the waste heat boiler is divided into two paths. One path is connected to the heat-absorbing side of the first turbine cooler and the heat-releasing side of the natural gas preheater through a first electric valve and a small-flow medium-pressure feed water pump. The other path is connected to the heat-absorbing side inlet of the second turbine cooler through a second electric valve, the heat-absorbing side outlet of the second turbine cooler is connected to the inlet of the electric heater, the outlet of the electric heater is connected to the outlet of the medium-pressure cylinder through a medium-pressure cylinder preheating valve, and the outlet of the electric heater is connected to the outlet of the high-pressure cylinder through a high-pressure cylinder preheating valve.

[0008] Further, the natural gas input pipeline, the combustion chamber, the turbine and the compressor are further included.

[0009] The natural gas input pipeline is connected with the inlet of the combustion chamber through the heat absorption side of the natural gas preheater, the outlet of the combustion chamber is connected with the inlet of the turbine, the outlet of the compressor is connected with the inlet of the combustion chamber, the exhaust port of the compressor is divided into three paths, wherein the first path is connected with the inlet of the turbine through the fourth electric valve and the heat release side of the first turbine cooler, the second path is connected with the inlet of the turbine through the fifth electric valve and the heat release side of the second turbine cooler, the third path is connected with the inlet of the turbine through the sixth electric valve, and the flue gas outlet of the turbine is connected with the flue gas inlet of the waste heat boiler.

[0010] Further, the main steam outlet of the waste heat boiler is connected with the inlet of the high-pressure cylinder through the high-pressure main valve, the outlet of the high-pressure cylinder is connected with the reheating side inlet of the waste heat boiler through the high-pressure exhaust check valve, the reheating side outlet of the waste heat boiler is connected with the inlet of the medium-pressure cylinder through the medium-pressure main valve, the outlet of the medium-pressure cylinder is connected with the inlet of the low-pressure cylinder through the low-pressure main valve, and the outlet of the low-pressure cylinder is connected with the feed water inlet of the waste heat boiler through the condenser and the condensate pump.

[0011] Further, the main steam outlet of the waste heat boiler is connected with the reheating side inlet through the high-pressure by-pass hydraulic valve.

[0012] Further, the superheated steam outlet of the waste heat boiler is connected with the inlet of the condenser through the medium-pressure by-pass hydraulic valve.

[0013] Further, the outlet of the medium-pressure cylinder is connected with the inlet of the condenser through the low-pressure by-pass hydraulic valve.

[0014] Further, the drain outlet of the low-pressure cylinder is provided with a low-pressure cylinder drain valve, the drain outlet of the medium-pressure cylinder is provided with a medium-pressure cylinder drain valve, and the drain outlet of the high-pressure cylinder is provided with a high-pressure cylinder drain valve.

[0015] Further, the compressor, the turbine and the first generator are coaxially arranged.

[0016] Further, the low-pressure cylinder, the medium-pressure cylinder, the high-pressure cylinder and the second generator are coaxially arranged.

[0017] The application discloses a method for shortening the starting time of a unit by utilizing the waste heat of a gas turbine cooling system.

[0018] Open the second, fifth, and sixth electric valves. The feedwater output from the low-pressure economizer absorbs heat and evaporates into superheated steam in the second turbine cooler. Open the third electric valve to supplement steam through the auxiliary steam header to ensure cylinder preheating requirements. In the initial stage of gas turbine startup, when steam temperature is insufficient, the electric heater is activated. After gas turbine startup, open the high-pressure bypass hydraulic valve, intermediate-pressure bypass hydraulic valve, and low-pressure bypass hydraulic valve to send steam that has not yet reached the turbine start-up parameters into the condenser. Open the high-pressure cylinder reverse warming valve, intermediate-pressure cylinder preheating valve, high-pressure cylinder drain valve, intermediate-pressure cylinder drain valve, and low-pressure cylinder drain valve in advance to confirm high pressure. The main steam valve and intermediate pressure main steam valve are closed, and the high-pressure cylinder and intermediate pressure cylinder reverse heating is performed to allow warm-up steam to enter the high-pressure cylinder and intermediate pressure cylinder. The condensate discharged from the high-pressure cylinder, intermediate pressure cylinder and low-pressure cylinder enters the condenser. When the cylinder body of the high-pressure cylinder and intermediate pressure cylinder is preheated to the preset temperature, reverse heating is stopped, and the high-pressure cylinder reverse heating valve and intermediate pressure cylinder preheating valve are closed. After the parameters of the superheated steam generated by the waste heat boiler meet the turbine start-up parameters, the high-pressure main steam valve and intermediate pressure main steam valve are opened for warm-state start-up, and then connected to the grid. As the load increases, the high-pressure bypass hydraulic valve, intermediate bypass hydraulic valve and low-pressure bypass hydraulic valve are gradually closed.

[0019] The present invention has the following beneficial effects:

[0020] The system and method for shortening unit start-up time by utilizing waste heat from the gas turbine cooling system, as described in this invention, involves arranging a second turbine cooler in parallel near the existing turbine cooler to produce low-pressure steam for turbine preheating. This allows for preheating of the turbine before restarting, so that once the gas turbine starts and is under load, it can be directly connected to the grid and increase load as long as the main steam and reheat steam meet the start-up requirements, reducing natural gas consumption. After preheating, the system switches to a dual-turbine cooler shared mode to recover exhaust heat. This modification effectively improves combined cycle performance and features strong operability, flexible operation, and significant energy-saving effects. Attached Figure Description

[0021] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0022] Figure 1 This is a structural diagram of the present invention.

[0023] Among them, 1 is the compressor, 2 is the combustion chamber, 3 is the natural gas preheater, 4 is the turbine, 5 is the first generator, 6 is the small-flow medium-pressure feedwater pump, 7 is the first turbine cooler, 8 is the second turbine cooler, 9 is the electric heater, 10 is the low-pressure cylinder, 11 is the medium-pressure cylinder, 12 is the high-pressure cylinder, 13 is the second generator, 14 is the waste heat boiler, 15 is the condenser, 16 is the condensate pump, 17 is the high-pressure main steam valve, 18 is the high-pressure cylinder drain valve, and 19 is the medium-pressure cylinder drain valve. 20 is the main steam valve, 21 is the intermediate pressure cylinder drain valve, 22 is the low pressure main steam valve, 23 is the intermediate pressure cylinder preheating valve, 24 is the low pressure bypass hydraulic valve, 25 is the auxiliary steam header, 26 is the high pressure exhaust check valve, 27 is the intermediate bypass hydraulic valve, 28 is the high pressure bypass hydraulic valve, 29 is the first electric valve, 30 is the second electric valve, 31 is the third electric valve, 32 is the fourth electric valve, 33 is the fifth electric valve, 34 is the sixth electric valve, and 35 is the high pressure cylinder reverse warming valve. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0026] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0027] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0028] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0029] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0031] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0032] Example 1

[0033] refer to Figure 1The system for shortening unit start-up time by utilizing waste heat from a gas turbine cooling system, as described in this invention, includes a compressor 1, a combustion chamber 2, a natural gas preheater 3, a turbine 4, a first generator 5, a small-flow medium-pressure feedwater pump 6, a first turbine cooler 7, a second turbine cooler 8, an electric heater 9, a low-pressure cylinder 10, a medium-pressure cylinder 11, a high-pressure cylinder 12, a second generator 13, a waste heat boiler 14, a condenser 15, a condensate pump 16, a high-pressure main steam valve 17, and a high-pressure... 18. Pressure cylinder drain valve, 19. Intermediate pressure main steam valve, 20. Intermediate pressure cylinder drain valve, 21. Low pressure main steam valve, 22. Low pressure cylinder drain valve, 23. Intermediate pressure cylinder preheating valve, 24. Low pressure bypass hydraulic valve, 25. Auxiliary steam header, 26. High pressure exhaust check valve, 27. Intermediate pressure bypass hydraulic valve, 28. High pressure bypass hydraulic valve, 29. First electric valve, 30. Second electric valve, 31. Third electric valve, 32. Fourth electric valve, 33. Fifth electric valve, 34. Sixth electric valve, and 35. High pressure cylinder reverse warming valve;

[0034] The natural gas input pipeline is connected to the inlet of combustion chamber 2 via the heat absorption side of natural gas preheater 3. The outlet of combustion chamber 2 is connected to the inlet of turbine 4. The outlet of compressor 1 is connected to the inlet of combustion chamber 2. The exhaust port of compressor 1 is divided into three paths. The first path is connected to the inlet of turbine 4 via the heat release side of the fourth electric valve 32 and the first turbine cooler 7. The second path is connected to the inlet of turbine 4 via the heat release side of the fifth electric valve 33 and the second turbine cooler 8. The third path is connected to the inlet of turbine 4 via the sixth electric valve 34. The flue gas outlet of turbine 4 is connected to the flue gas inlet of waste heat boiler 14.

[0035] The main steam outlet of the waste heat boiler 14 is connected to the inlet of the high-pressure cylinder 12 via the high-pressure main steam valve 17. The outlet of the high-pressure cylinder 12 is connected to the reheat side inlet of the waste heat boiler 14 via the high-pressure exhaust check valve 26. The reheat side outlet of the waste heat boiler 14 is connected to the inlet of the intermediate-pressure cylinder 11 via the intermediate-pressure main steam valve 19. The outlet of the intermediate-pressure cylinder 11 is connected to the inlet of the low-pressure cylinder 10 via the low-pressure main steam valve 21. The outlet of the low-pressure cylinder 10 is connected to the feedwater inlet of the waste heat boiler 14 via the condenser 15 and the condensate pump 16.

[0036] The main steam outlet of the waste heat boiler 14 is connected to the reheat side inlet via a high-pressure bypass hydraulic valve 28. The superheated steam outlet of the waste heat boiler 14 is connected to the inlet of the condenser 15 via a medium-pressure bypass hydraulic valve 27. The outlet of the intermediate-pressure cylinder 11 is connected to the inlet of the condenser 15 via a low-pressure bypass hydraulic valve 24.

[0037] The outlet of the low-temperature economizer in the waste heat boiler 14 is divided into two paths. One path is connected to the heat-releasing side of the natural gas preheater 3 via the first electric valve 29, the small-flow medium-pressure feedwater pump 6, and the heat-absorbing side of the first turbine cooler 7. The other path is connected to the heat-absorbing side inlet of the second turbine cooler 8 via the second electric valve 30. The heat-absorbing side outlet of the second turbine cooler 8 is connected to the inlet of the electric heater 9. The outlet of the auxiliary steam header 25 is connected to the inlet of the electric heater 9 via the third electric valve 31. The outlet of the electric heater 9 is connected to the outlet of the medium-pressure cylinder 11 via the medium-pressure cylinder preheating valve 23. The outlet of the electric heater 9 is connected to the outlet of the high-pressure cylinder 12 via the high-pressure cylinder reheating valve 35.

[0038] A low-pressure cylinder drain valve 22 is provided at the drain outlet of the low-pressure cylinder 10, a medium-pressure cylinder drain valve 20 is provided at the drain port of the medium-pressure cylinder 11, and a high-pressure cylinder drain valve 18 is provided at the drain port of the high-pressure cylinder 12.

[0039] The compressor 1, turbine 4 and first generator 5 are arranged coaxially.

[0040] The low-pressure cylinder 10, the intermediate-pressure cylinder 11, the high-pressure cylinder 12, and the second generator 13 are arranged coaxially.

[0041] During operation, the air output from compressor 1 enters combustion chamber 2, and the natural gas output from the natural gas input pipeline enters natural gas preheater 3 to absorb heat, and then enters combustion chamber 2 to burn and produce high-temperature flue gas. The high-temperature flue gas enters turbine 4 to do work, and the flue gas discharged from turbine 4 enters waste heat boiler 14. The air extraction from compressor 1 is divided into three paths: the first path enters the first turbine cooler 7 to release heat, and then enters turbine 4; the second path enters the second turbine cooler 8 to release heat, and then enters turbine 4; and the third path directly enters turbine 4.

[0042] The main steam output from the waste heat boiler 14 enters the high-pressure cylinder 12. The exhaust steam from the high-pressure cylinder 12 enters the waste heat boiler 14 for reheating, and then enters the intermediate-pressure cylinder 11. The exhaust steam from the high-pressure cylinder 11 enters the low-pressure cylinder 10. The exhaust steam from the low-pressure cylinder 10 enters the condenser 15 for cooling. The condensate output from the condenser 15 enters the waste heat boiler 14.

[0043] The superheated steam output from the waste heat boiler enters the condenser 15. The exhaust steam from the intermediate pressure cylinder 11 enters the condenser 15. The steam output from the low-pressure economizer in the waste heat boiler 14 is divided into two paths. One path enters the first turbine cooler 7 to absorb heat and then enters the natural gas preheater to release heat. The other path enters the second turbine cooler 8 to absorb heat and then enters the electric heater 9 for heating. The steam output from the auxiliary steam header 25 enters the electric heater 9 for heating. The steam output from the electric heater 9 is divided into two paths. One path enters the low-pressure cylinder 10, and the other path enters the reheat side of the waste heat boiler 14.

[0044] In addition, based on actual operating conditions, the following valves are controlled: high-pressure main steam valve 17, high-pressure cylinder drain valve 18, intermediate-pressure main steam valve 19, intermediate-pressure cylinder drain valve 20, low-pressure main steam valve 21, low-pressure cylinder drain valve 22, intermediate-pressure cylinder preheating valve 23, low-pressure bypass hydraulic valve 24, auxiliary steam header 25, high-pressure exhaust check valve 26, intermediate bypass hydraulic valve 27, high-pressure bypass hydraulic valve 28, first electric valve 29, second electric valve 30, third electric valve 31, fourth electric valve 32, fifth electric valve 33, sixth electric valve 34, and high-pressure cylinder reverse warming valve 35, to meet different operating conditions.

[0045] Example 2

[0046] This invention discloses a method for shortening the start-up time of a gas turbine unit by utilizing waste heat from a gas turbine cooling system. The method is based on a system for shortening the start-up time of a gas turbine unit by utilizing waste heat from a gas turbine cooling system. This system includes a compressor 1, a combustion chamber 2, a natural gas preheater 3, a turbine 4, a first generator 5, a small-flow medium-pressure feedwater pump 6, a first turbine cooler 7, a second turbine cooler 8, an electric heater 9, a low-pressure cylinder 10, a medium-pressure cylinder 11, a high-pressure cylinder 12, and a second generator. 13. Waste heat boiler; 14. Condenser; 15. Condensate pump; 16. High-pressure main steam valve; 17. High-pressure cylinder drain valve; 18. Medium-pressure main steam valve; 19. Medium-pressure cylinder drain valve; 20. Low-pressure main steam valve; 21. Low-pressure cylinder drain valve; 22. Medium-pressure cylinder preheating valve; 23. Low-pressure bypass hydraulic valve; 24. Auxiliary steam header; 25. High-pressure exhaust check valve; 26. Medium-pressure bypass hydraulic valve; 27. High-pressure bypass hydraulic valve; 28. First electric valve; 29. ​​Second electric valve; 30. Third electric valve; 31. Fourth electric valve; 32. Fifth electric valve; 33. Sixth electric valve; and 34. High-pressure cylinder reverse heating valve; 35. The specific connection method is as shown in Example 1.

[0047] The method for shortening unit start-up time by utilizing waste heat from the gas turbine cooling system includes the following steps:

[0048] The compressed air output from compressor 1 and natural gas are burned in combustion chamber 2 to produce high-temperature flue gas. The high-temperature flue gas enters turbine 4 to expand and do work. The exhaust gas from turbine 4 enters waste heat boiler 14 to heat boiler feedwater to form main steam with different pressure parameters. The main steam enters steam turbine unit to expand and do work. The exhaust steam from steam turbine enters condenser 15 to form condensate. The condensate is then pressurized by condensate pump 16 and fed to waste heat boiler 14 to form steam-water circulation. The heat of condenser 15 is carried away by the circulating water.

[0049] The turbine cooler is an air / water heat exchanger. The low-pressure feedwater output from the low-pressure economizer flows into the turbine cooler. The modified gas turbine cooling system has a more flexible operating mode compared to the original system.

[0050] After the gas turbine starts up, it simultaneously uses waste heat from the air to preheat the turbine cylinder. The preheating method is as follows: open the second electric valve 30, the fifth electric valve 33 and the sixth electric valve 34. The feedwater output from the low-pressure economizer absorbs heat and evaporates into superheated steam in the second turbine cooler 8. The steam pressure is about 0.6 MPa. Open the third electric valve 31 and supplement the steam volume through the auxiliary steam header 25 to ensure the cylinder preheating requirements. In the early stage of gas turbine startup, the steam temperature is insufficient. The electric heater 9 is put into operation to ensure that the temperature of the steam used for cylinder preheating reaches above 300℃. After the gas turbine starts up, open the high-pressure bypass hydraulic valve 28, the medium-pressure bypass hydraulic valve 27 and the low-pressure bypass hydraulic valve 24 to send the steam that has not reached the turbine start-up parameters into the condenser 15. Open the high-pressure cylinder preheating valve 35, the intermediate-pressure cylinder preheating valve 23, the high-pressure cylinder drain valve 18, the intermediate-pressure cylinder drain valve 20, and the low-pressure cylinder drain valve 22 in advance. Confirm that the high-pressure main steam valve 17 and the intermediate-pressure main steam valve 19 are closed. Perform preheating of the high-pressure cylinder 12 and the intermediate-pressure cylinder 11, allowing warm-up steam to enter the high-pressure cylinder 12 and the intermediate-pressure cylinder 11. The drains discharged from the high-pressure cylinder 12, the intermediate-pressure cylinder 11, and the low-pressure cylinder 10 enter the condenser 15, thus preheating the cylinder bodies of the high-pressure cylinder 12 and the intermediate-pressure cylinder 11. When the temperature reaches around 240℃, reverse heating is stopped, and the high-pressure cylinder reverse heating valve 35 and the intermediate-pressure cylinder preheating valve 23 are closed. After the parameters of the superheated steam generated by the waste heat boiler 14 meet the turbine start-up parameters, the high-pressure main steam valve 17 and the intermediate-pressure main steam valve 19 are opened to perform a warm-state start-up, so that the turbine can start up to 3000r / min in a shorter time and then be connected to the grid. As the load increases, the high-pressure bypass hydraulic valve 28, the intermediate-pressure bypass hydraulic valve 27 and the low-pressure bypass hydraulic valve 24 are gradually closed.

[0051] After preheating, the combined cycle unit is connected to the grid and enters load ramping control. The first turbine cooler 7 is also put into operation. The first electric valve 29 and the fourth electric valve 32 are opened, and the small-flow medium-pressure feedwater pump 6 is started. The medium-pressure feedwater absorbs heat in the first turbine cooler 7 and then enters the natural gas preheater 3 to heat the natural gas, heating the cold natural gas to the target temperature corresponding to the current load of the unit. The cooled medium-pressure feedwater merges with the outlet of the medium-pressure feedwater pump of the waste heat boiler 14. The second turbine cooler 8 continues to be put into operation. The third electric valve 31 is closed, and the electric heater 9 is shut down. After the gas turbine load increases, the medium-pressure cylinder preheating valve 23 is opened again. At this time, the turbine unit is already under load. The steam generated by the second turbine cooler 8 passes through the medium-pressure cylinder preheating valve 23 and enters the low-pressure cylinder 10 together with the exhaust steam of the medium-pressure cylinder 11 to do work. By adjusting the opening of the sixth electric valve 34, the mixed air reaches the target temperature for cooling the blades of the turbine 4.

[0052] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0053] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0054] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A system for shortening unit start-up time by utilizing waste heat from a gas turbine cooling system, characterized in that, It includes a waste heat boiler (14), a natural gas preheater (3), a second turbine cooler (8), an electric heater (9), an auxiliary steam header (25), an intermediate pressure cylinder (11), and a high pressure cylinder (12). The outlet of the low-temperature economizer of the waste heat boiler (14) is divided into two paths. One path is connected to the heat-releasing side of the natural gas preheater (3) via the first electric valve (29), the small flow medium-pressure feed water pump (6), and the heat absorption side of the first turbine cooler (7). The other path is connected to the heat absorption side inlet of the second turbine cooler (8) via the second electric valve (30). The heat absorption side outlet of the second turbine cooler (8) is connected to the inlet of the electric heater (9). The outlet of the auxiliary steam header (25) is connected to the inlet of the electric heater (9) via the third electric valve (31). The outlet of the electric heater (9) is connected to the outlet of the medium-pressure cylinder (11) via the medium-pressure cylinder preheating valve (23). The outlet of the electric heater (9) is connected to the outlet of the high-pressure cylinder (12) via the high-pressure cylinder reheating valve (35). It also includes a natural gas input pipeline, a combustion chamber (2), a turbine (4), and a compressor (1); The natural gas input pipeline is connected to the inlet of the combustion chamber (2) via the heat absorption side of the natural gas preheater (3), the outlet of the combustion chamber (2) is connected to the inlet of the turbine (4), the outlet of the compressor (1) is connected to the inlet of the combustion chamber (2), the exhaust port of the compressor (1) is divided into three paths, of which the first path is connected to the inlet of the turbine (4) via the fourth electric valve (32) and the heat release side of the first turbine cooler (7), the second path is connected to the inlet of the turbine (4) via the fifth electric valve (33) and the heat release side of the second turbine cooler (8), the third path is connected to the inlet of the turbine (4) via the sixth electric valve (34), and the flue gas outlet of the turbine (4) is connected to the flue gas inlet of the waste heat boiler (14). The main steam outlet of the waste heat boiler (14) is connected to the inlet of the high-pressure cylinder (12) via the high-pressure main steam valve (17). The outlet of the high-pressure cylinder (12) is connected to the reheat side inlet of the waste heat boiler (14) via the high-pressure exhaust check valve (26). The reheat side outlet of the waste heat boiler (14) is connected to the inlet of the medium-pressure cylinder (11) via the medium-pressure main steam valve (19). The outlet of the medium-pressure cylinder (11) is connected to the inlet of the low-pressure cylinder (10) via the low-pressure main steam valve (21). The outlet of the low-pressure cylinder (10) is connected to the feedwater inlet of the waste heat boiler (14) via the condenser (15) and the condensate pump (16). The main steam outlet of the waste heat boiler (14) is connected to the reheat side inlet via a high-speed bypass hydraulic valve (28); The superheated steam outlet of the waste heat boiler (14) is connected to the inlet of the condenser (15) via the intermediate bypass hydraulic valve (27); The outlet of the intermediate pressure cylinder (11) is connected to the inlet of the condenser (15) via the low-pressure bypass hydraulic valve (24); The low-pressure cylinder (10) is provided with a low-pressure cylinder drain valve (22) at its drain outlet, the medium-pressure cylinder (11) is provided with a medium-pressure cylinder drain valve (20) at its drain outlet, and the high-pressure cylinder (12) is provided with a high-pressure cylinder drain valve (18) at its drain outlet.

2. The system for shortening unit start-up time by utilizing waste heat from the gas turbine cooling system according to claim 1, characterized in that, The compressor (1), turbine (4) and first generator (5) are arranged coaxially.

3. The system for shortening unit start-up time by utilizing waste heat from the gas turbine cooling system according to claim 1, characterized in that, The low-pressure cylinder (10), medium-pressure cylinder (11), high-pressure cylinder (12) and the second generator (13) are arranged coaxially.

4. A method for shortening unit start-up time by utilizing waste heat from a gas turbine cooling system, characterized in that, The system for shortening unit start-up time by utilizing waste heat from a gas turbine cooling system as described in claim 1 includes the following steps: Open the second electric valve (30), the fifth electric valve (33), and the sixth electric valve (34). The feedwater output from the low-pressure economizer absorbs heat and evaporates into superheated steam in the second turbine cooler (8). Open the third electric valve (31) to supplement the steam volume through the auxiliary steam header (25) to ensure the preheating requirements of the cylinder. In the early stage of gas turbine startup, the steam temperature is insufficient, so the electric heater (9) is put into operation. After the gas turbine starts, open the high-pressure bypass hydraulic valve (28), the intermediate-pressure bypass hydraulic valve (27), and the low-pressure bypass hydraulic valve (24) to send the steam that has not reached the turbine start-up parameters into the condenser (15). Open the high-pressure cylinder back-warming valve (35), the intermediate-pressure cylinder preheating valve (23), the high-pressure cylinder drain valve (18), the intermediate-pressure cylinder drain valve (20), and the low-pressure cylinder drain valve (22) in advance to confirm the high-pressure main steam valve (17) and the intermediate-pressure cylinder drain valve (22). When the main steam valve (19) is closed, the high-pressure cylinder (12) and intermediate-pressure cylinder (11) are heated back, so that the warm cylinder steam enters the high-pressure cylinder (12) and intermediate-pressure cylinder (11). The condensate discharged from the high-pressure cylinder (12), intermediate-pressure cylinder (11) and low-pressure cylinder (10) enters the condenser (15). When the cylinder bodies of the high-pressure cylinder (12) and intermediate-pressure cylinder (11) are preheated to the preset temperature, the heating back stops, the high-pressure cylinder heating back valve (35) and intermediate-pressure cylinder preheating valve (23) are closed. After the superheated steam parameters generated by the waste heat boiler (14) meet the turbine start-up parameters, the high-pressure main steam valve (17) and intermediate-pressure main steam valve (19) are opened for warm-state start-up. Then, the system is connected to the grid. As the load increases, the high-pressure bypass hydraulic valve (28), intermediate-pressure bypass hydraulic valve (27) and low-pressure bypass hydraulic valve (24) are gradually closed. After the preheating is completed, the combined cycle unit is connected to the grid and enters the load increase control. The first turbine cooler (7) is also put into use. The first electric valve (29) and the fourth electric valve (32) are opened, and the small flow medium-pressure feedwater pump (6) is started. The medium-pressure feedwater absorbs heat in the first turbine cooler (7) and then enters the natural gas preheater (3) to heat the natural gas, heating the cold natural gas to the target temperature corresponding to the current load of the unit. The cooled medium-pressure feedwater merges with the outlet of the medium-pressure feedwater pump of the waste heat boiler (14); the second Turbine cooler (8) continues to be put into use, the third electric valve (31) is closed, the electric heater (9) is stopped, and the intermediate pressure cylinder preheating valve (23) is opened again after the gas turbine load increases. At this time, the turbine unit has been loaded. The steam generated by the second turbine cooler (8) enters the low pressure cylinder (10) together with the exhaust steam of the intermediate pressure cylinder (11) after passing through the intermediate pressure cylinder preheating valve (23) to do work. By adjusting the opening of the sixth electric valve (34), the mixed air reaches the target temperature for cooling the blades in the turbine (4).

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