Steam turbine shaft seal steam supply system

Abstract

The steam turbine shaft seal steam supply system comprises a pressure equalizing box, a temperature reducing assembly and an overflow pipe, the pressure equalizing box is connected with a first pipeline and a second pipeline, and the first pipeline and the second pipeline communicate with a high-pressure shaft seal and a low-pressure shaft seal of a steam turbine correspondingly; the temperature reduction assembly comprises an atomization nozzle installed on the second pipeline, a third pipeline connected with the atomization nozzle and used for conveying temperature reduction water and a temperature reduction water adjusting valve installed on the third pipeline, one end of an overflow pipe is connected to the top of the pressure equalizing box, the overflow pipe is provided with an overflow adjusting valve, and the overflow adjusting valve is provided with the minimum opening degree. And the through-flow capacity of the overflow pipe at the minimum opening degree is greater than the maximum water spraying amount of the atomizing nozzle. When a large amount of desuperheating water enters the pressure equalizing box due to the fact that the desuperheating water regulating valve is abnormal or a worker operates mistakenly, accumulated water in the pressure equalizing box can be discharged along the overflow pipe, the accumulated water in the pressure equalizing box can be only discharged along the overflow pipe under extreme conditions and cannot flow back to the sealing position of the large-shaft high-pressure shaft seal, and intrinsic safety is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbine shaft seal supply, and in particular to a steam turbine shaft seal steam supply system. Background Art

[0002] Under various operating conditions of the steam turbine, as an important supporting system of the steam turbine unit, the shaft seal system should provide sealing steam that meets the requirements, involving high-pressure shaft seal steam supply and low-pressure shaft seal steam supply. The steam is supplied to the low-pressure shaft seal after temperature and pressure adjustment in the pressure equalizing box. Since the low-pressure shaft seal requires a lower steam supply temperature, a temperature reduction device needs to be installed in the pressure equalizing box to spray condensate to reduce the steam temperature of the low-pressure shaft seal steam supply.

[0003] If the cooling water regulating valve malfunctions or personnel make operating errors, causing a large amount of cooling water to enter the pressure equalizing tank, the accumulated water in the pressure equalizing tank cannot be discharged in time, and the low-temperature cooling water flows back along the high-pressure shaft seal pipeline to the high-pressure shaft seal of the main shaft, causing local sudden cooling of the high-pressure shaft seal. Local sudden cooling can cause deformation of the cylinder and rotor, and there is a problem of local sudden cooling of high-temperature components. Summary of the invention

[0004] In order to solve the above problems, the present application provides a steam turbine shaft seal steam supply system.

[0005] The present application provides a steam supply system for a steam turbine shaft seal, comprising a pressure equalizing box, a temperature reduction component and an overflow pipe, wherein the pressure equalizing box is connected to a first pipeline and a second pipeline, the first pipeline and the second pipeline are respectively connected to a high-pressure shaft seal and a low-pressure shaft seal of the steam turbine, the temperature reduction component comprises an atomizing nozzle installed on the second pipeline, a third pipeline connected to the atomizing nozzle and used for conveying temperature reduction water, and a temperature reduction water regulating valve installed on the third pipeline, one end of the overflow pipe is connected to the top of the pressure equalizing box, the overflow pipe is installed with an overflow regulating valve, the overflow regulating valve is provided with a minimum opening, and the flow capacity of the overflow pipe at the minimum opening is greater than the maximum water spraying amount of the atomizing nozzle.

[0006] In some embodiments, the steam supply system for the steam turbine shaft seal includes a condenser, which is located below the steam turbine and is connected to an end of the overflow pipe away from the pressure equalizing tank.

[0007] In some embodiments, the second pipeline is equipped with a steam-water separation tank, which is farther away from the pressure equalizing tank than the atomizing nozzle along the second pipeline. The steam-water separation tank is connected to the first drain pipeline, and the first drain pipeline is equipped with a steam trap.

[0008] In some embodiments, the pressure equalizing tank is connected to a second drain pipe, the second drain pipe is connected to the bottom of the pressure equalizing tank, and a drain trap is installed in the second drain pipe.

[0009] In some embodiments, the pressure equalizing tank is connected to a fourth pipeline, the fourth pipeline is used to transport auxiliary steam, the fourth pipeline is installed with a fourth stop valve, the pipe body of the fourth pipeline is connected to the third drain pipe and is connected to the side of the fourth stop valve away from the pressure equalizing tank, and the third drain pipe is installed with a drain.

[0010] In some embodiments, the second pipeline is equipped with a steam-water separation tank, the steam-water separation tank is farther away from the pressure equalizing tank than the atomizing nozzle along the second pipeline, the steam-water separation tank is connected to the first drain pipeline, and the first drain pipeline is equipped with a steam trap;

[0011] The pressure equalizing box is connected to a second drain pipe, the second drain pipe is connected to the bottom of the pressure equalizing box, and a drain trap is installed in the second drain pipe;

[0012] The pressure equalizing tank is connected to a fourth pipeline, the fourth pipeline is used to transport auxiliary steam, the fourth pipeline is installed with a fourth stop valve, the pipe body of the fourth pipeline is connected to the third drain pipeline and connected to the side of the fourth stop valve away from the pressure equalizing tank, and the third drain pipeline is installed with a steam trap;

[0013] The steam supply system for the steam turbine shaft seal includes a condenser and a drain main pipe. The condenser is connected to the drain main pipe and the overflow pipe. The drain main pipe is connected to the first drain pipe, the second drain pipe and the third drain pipe.

[0014] In some embodiments, the connection point between the overflow pipe and the condenser is higher than the connection point between the drain main pipe and the condenser.

[0015] In some embodiments, the pressure equalizing tank is connected to a first pressure gauge, a first temperature gauge, and a safety valve.

[0016] In some embodiments, a second temperature gauge is connected to the second pipeline.

[0017] In some embodiments, the overflow pipe is below the lower casing of the steam turbine.

[0018] The beneficial effects of the present application are as follows: a steam supply system for a steam turbine shaft seal is provided, including a pressure equalizing box, a temperature reduction component and an overflow pipe, steam is sent to a low-pressure shaft seal through a second pipe, and the temperature of the steam entering the low-pressure shaft seal is reduced by the temperature reduction component. In this system, the atomizing nozzle of the temperature reduction component is installed in the second pipe, and the temperature reduction component only acts on the second pipe, which can reduce the amount of temperature reduction water used. The steam and the water mist sprayed from the atomizing nozzle are mixed and flow only to the low-pressure shaft seal, thereby reducing the possibility of the pressure equalizing box being full of water; the pressure equalizing box is connected to the overflow pipe, and the pressure equalizing box is in a state of normal operation of the steam turbine unit. Excess steam is discharged from the overflow pipe. When the cooling water regulating valve is abnormal or the operator makes an operating error, causing a large amount of cooling water to enter the equalizing pressure tank, the accumulated water in the equalizing pressure tank will be discharged along the overflow pipe. In this system, the minimum opening of the overflow regulating valve on the overflow pipe is set. The flow capacity of the overflow pipe at the minimum opening is greater than the maximum water spraying volume of the atomizing nozzle. In extreme cases, the accumulated water in the equalizing pressure tank will only be discharged along the overflow pipe and will not be reversed to the high-pressure shaft seal of the main shaft, avoiding the problem of local sudden cooling causing deformation of the cylinder and rotor, thereby achieving inherent safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for describing the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention.

[0020] Figure 1 A schematic block diagram of a steam turbine shaft seal steam supply system provided in this application.

[0021] The attached drawings are marked with: 1-steam turbine, 2-condenser, 3-high-pressure shaft seal, 4-low-pressure shaft seal, 5-first pipeline, 6-pressure equalizing box, 7-first pressure gauge, 8-first thermometer, 9-safety valve, 10-second drain pipeline, 11-second pipeline, 12-atomizing nozzle, 13-steam-water separation tank, 14-first drain pipeline, 15-second thermometer, 16-third pipeline, 17-third stop valve, 18-cooling water regulating valve, 19-fourth pipeline, 20-fourth stop valve, 21-third drain pipeline, 22-auxiliary steam regulating valve, 23-overflow pipe, 24-overflow regulating valve, 25-overflow stop valve, 26-drain device, 27-drain main pipe. DETAILED DESCRIPTION

[0022] The shaft seal system is an important supporting system of the steam turbine unit. Under various operating conditions of the steam turbine, the shaft seal system should provide sealing steam that meets the requirements, reasonably recycle and utilize the energy of the steam working medium, prevent leakage of high-pressure steam, and ensure the normal operation of the steam turbine. The shaft seal system is generally designed as a self-sealing shaft seal steam system, which is equipped with a pressure equalizing box, a shaft seal cooler, a pressure regulating device, etc.

[0023] During the start-up or low-load stage of the steam turbine unit, if there is no steam leakage from the high-pressure shaft seal or the steam volume is insufficient, steam is supplied from the auxiliary steam pipeline. After temperature and pressure adjustment in the pressure equalizing box, steam is supplied to the high-pressure shaft seal and the low-pressure shaft seal respectively to achieve sealing.

[0024] When the steam turbine unit is operating normally, the leakage steam from the high-pressure shaft seal is supplied to the pressure equalizing box. After the temperature and pressure are adjusted by the pressure equalizing box, steam is supplied to the low-pressure shaft seal to achieve a self-balanced steam seal between the two.

[0025] Since the low-pressure shaft seal requires a lower steam supply temperature, a temperature reduction device needs to be installed in the pressure equalizing tank to spray condensate to reduce the steam temperature of the low-pressure shaft seal supply. To prevent water accumulation, a drain device is installed in the pressure equalizing tank. When the steam turbine unit is started, especially in the warm and hot start-up stages, the high-pressure shaft seal steam supply is supplied by the pressure equalizing tank.

[0026] If the cooling water regulating valve malfunctions or personnel make operating errors, causing a large amount of cooling water to enter the pressure equalizing tank, the accumulated water in the pressure equalizing tank cannot be discharged in time, and the low-temperature cooling water flows back along the high-pressure shaft seal pipeline to the high-pressure shaft seal of the main shaft, causing local sudden cooling of the high-pressure shaft seal. Local sudden cooling can cause deformation of the cylinder and rotor, and there is a problem of local sudden cooling of high-temperature components.

[0027] In order to solve the above problems, the present application provides a steam turbine shaft seal steam supply system, hereinafter referred to as the system, please refer to Figure 1 The system includes a pressure equalizing tank 6, which is connected to a first pipeline 5 and a second pipeline 11. The first pipeline 5 is connected to the high-pressure shaft seal 3 of the steam turbine 1, and the second pipeline 11 is connected to the low-pressure shaft seal 4 of the steam turbine 1. The pressure equalizing tank 6 is connected to a fourth pipeline 19, which is used to transport auxiliary steam to the pressure equalizing tank 6 during the startup or low-load stage of the steam turbine unit. The fourth pipeline 19 is installed with a fourth stop valve 20 and an auxiliary steam regulating valve 22, and the auxiliary steam regulating valve 22 is closer to the pressure equalizing tank 6 than the fourth stop valve 20 along the fourth pipeline 19.

[0028] Please refer to Figure 1 The system includes a cooling component, which includes an atomizing nozzle 12, a third pipeline 16 and a cooling water regulating valve 18. The atomizing nozzle 12 is installed in the second pipeline 11, and the third pipeline 16 is connected to the atomizing nozzle 12. The cooling water is transported to the atomizing nozzle 12 through the third pipeline 16. The cooling water regulating valve 18 is installed in the third pipeline 16, and the flow rate of the cooling water is adjusted by the cooling water regulating valve 18.

[0029] When the steam turbine 1 is started in hot state, auxiliary steam enters the pressure equalizing tank 6 from the fourth pipeline 19, and the pressure equalizing tank 6 supplies steam to the high-pressure shaft seal 3 through the first pipeline 5. The pressure equalizing tank 6 supplies steam to the low-pressure shaft seal 4 through the second pipeline 11 and after being sprayed with water mist by the atomizing nozzle 12 for cooling.

[0030] Please refer to Figure 1The system includes an overflow pipe 23, one end of which is connected to the top of the pressure equalizing tank 6. The overflow pipe 23 is installed with an overflow regulating valve 24 and an overflow stop valve 25. The overflow regulating valve 24 is set with a minimum opening. The flow capacity of the overflow pipe 23 at the minimum opening is greater than the maximum water spray volume of the atomizing nozzle 12.

[0031] When the steam turbine 1 operates normally, the steam leaking from the high-pressure shaft seal 3 is supplied to the pressure equalizing tank 6 along the first pipeline 5. After the temperature and pressure are adjusted by the pressure equalizing tank 6, part of the steam flows along the second pipeline 11 and is sprayed with water mist through the atomizing nozzle 12 for cooling, and then supplies steam to the low-pressure shaft seal 4. The excess steam in the pressure equalizing tank 6 is discharged from the overflow pipe 23, thereby realizing a self-balanced steam seal between the two.

[0032] When an abnormality occurs in the cooling water regulating valve 18 or an operating error occurs, causing a large amount of cooling water to enter the equalizing pressure tank 6, the accumulated water in the equalizing pressure tank 6 will be discharged along the overflow pipe 23. Since the minimum opening of the overflow regulating valve 24 on the overflow pipe 23 is set in this system, the flow capacity of the overflow pipe 23 at the minimum opening is greater than the maximum water spray volume of the atomizing nozzle 12. In extreme cases, the accumulated water in the equalizing pressure tank 6 will only be discharged along the overflow pipe 23 and will not flow back to the seal of the main shaft high-pressure shaft seal 3, thereby avoiding the problem of local sudden cooling causing deformation of the cylinder and rotor, thereby achieving inherent safety.

[0033] In this system, the atomizing nozzle 12 of the cooling component is installed in the second pipe 11. The cooling component only acts on the second pipe 11, which can reduce the amount of cooling water. The steam and the water mist sprayed from the atomizing nozzle 12 are mixed and only flow to the low-pressure shaft seal 4, thereby reducing the possibility of the equalizing pressure tank 6 being filled with water.

[0034] The overflow pipe 23 is limited in that one end is connected to the top of the pressure equalizing tank 6 , and the top of the pressure equalizing tank 6 refers to the top of the pressure equalizing tank 6 or a position close to the top of the tank.

[0035] In some embodiments, the overflow pipe 23 is connected to the atmosphere to introduce steam or accumulated water into the atmosphere, but this method is generally not used in actual applications.

[0036] In some embodiments, see Figure 1 The system includes a condenser 2, which is located below the steam turbine 1. The condenser 2 is connected to an end of the overflow pipe 23 that is away from the pressure equalizing tank 6. In this method, the negative pressure condition of the condenser 2 is utilized, and the overflow pipe 23 leads to the condenser 2 in a negative pressure state. When the accumulated water in the pressure equalizing tank 6 is discharged along the overflow pipe 23, the negative pressure state of the condenser 2 is conducive to the accumulated water flowing out of the pressure equalizing tank 6.

[0037] In some embodiments, see Figure 1The second pipeline 11 is equipped with a steam-water separation tank 13 . Along the second pipeline 11 , the steam-water separation tank 13 is farther away from the pressure equalizing tank 6 than the atomizing nozzle 12 . The steam-water separation tank 13 is connected to the first drain pipeline 14 . The first drain pipeline 14 is equipped with a steam trap 26 .

[0038] When an abnormality occurs in the cooling water regulating valve 18 or an operator makes an operational error, causing a large amount of cooling water to enter the pressure equalizing tank 6, part of the accumulated water can be discharged from the pressure equalizing tank 6 along the second pipeline 11, the steam-water separation tank 13, and the first drain pipeline 14, further reducing the possibility of the pressure equalizing tank 6 being full of water; moreover, the water mist that is not fully separated will flow toward the low-pressure shaft seal 4 along the steam supply direction. Since the temperature of the main shaft at the low-pressure shaft seal 4 is low, the low-temperature accumulated water will not cause failure of the main shaft at the low-pressure shaft seal 4 in a short time.

[0039] In some embodiments, see Figure 1 The pressure equalizing tank 6 is connected to a second drain pipe 10, which is connected to the bottom of the pressure equalizing tank 6 and is equipped with a steam trap 26. The accumulated water in the pressure equalizing tank 6 can be discharged along the second drain pipe 10, further reducing the possibility of the pressure equalizing tank 6 being full of water.

[0040] In some embodiments, see Figure 1 The body of the fourth pipe 19 is connected to the third drain pipe 21 , and the connection between the fourth pipe 19 and the third drain pipe 21 is located on the side of the fourth stop valve 20 away from the pressure equalizing tank 6 , and the third drain pipe 21 is installed with a steam trap 26 .

[0041] When the auxiliary steam in the fourth pipe 19 is not put into use in the steam turbine group 1, the auxiliary steam will condense into water in the fourth pipe 19, and the condensed water will accumulate above the fourth stop valve 20. This part of the condensed water can be discharged from the fourth pipe 19 through the third drain pipe 21, avoiding the possibility of this part of the condensed water entering the high-pressure shaft seal 3.

[0042] The steam trap 26 is installed in the first steam trap pipeline 14, the second steam trap pipeline 10, and the third steam trap pipeline 21. The steam trap 26 can be expanded, for example, a steam trap assembly is installed in the steam trap pipeline, and the steam trap assembly includes a steam trap, a bypass connected in parallel with the steam trap, a stop valve installed in the bypass, and two stop valves installed in the branch where the steam trap is located and located before and after the steam trap. By using the above steam trap assembly, the steam trap can be replaced by the bypass for a short time to support the maintenance of the steam trap.

[0043] In some embodiments, see Figure 1The system includes a condenser 2 and a drain main pipe 27. The condenser 2 is connected to the drain main pipe 27 and the overflow pipe 23. The drain main pipe 27 is connected to the first drain pipe 14, the second drain pipe 10, and the third drain pipe 21. The outlet water of each drain pipe is collected through the drain main pipe 27 and led to the condenser 2.

[0044] In some embodiments, see Figure 1 , Figure 1 The height positions of the overflow pipe 23 and the drain main pipe 27 are shown. The connection point between the overflow pipe 23 and the condenser 2 is higher than the connection point between the drain main pipe 27 and the condenser 2. The drain main pipe 27 is located at the bottom of the elevation of this system, and the overflow pipe 23 is located in the middle of the elevation of this system. The overflow pipe 23 is also lower than the lower cylinder of the turbine 1, thereby achieving the purpose of reliable drainage of accumulated water.

[0045] In some embodiments, see Figure 1 The pressure equalizing tank 6 is connected to a first pressure gauge 7, a first thermometer 8 and a safety valve 9. The first pressure gauge 7 and the first thermometer 8 assist the temperature and pressure regulation of the pressure equalizing tank 6, and the safety valve 9 plays a role of safety protection.

[0046] In some embodiments, see Figure 1 The second pipeline 11 is connected to a second thermometer 15 , and the temperature of the steam flowing through the second pipeline 11 is detected by the second thermometer 15 .

[0047] In summary, the steam turbine shaft seal steam supply system provided by the present application has at least the following beneficial effects:

[0048] The shaft seal system has stronger redundancy in hydrophobic separation, and the pressure equalizing tank 6 is not easily filled with water;

[0049] Only the second pipe 11 connected to the low-pressure shaft seal 4 is provided with a cooling component, so the cooling water consumption is less;

[0050] During the startup process, in the normal state, low-temperature water mist mixes with steam and flows only to the low-pressure shaft seal 4;

[0051] At the same time, a steam-water separation tank 13 and a drain main pipe 27 are provided to improve the redundancy of drain separation. Even if a large amount of cooling water enters the cooling water system abnormally, the pressure equalizing tank 6 is not easily filled with water.

[0052] Reliable drainage of accumulated water is achieved. Even if water accumulates in the pressure equalizing box 6, it will not flow through the high-pressure shaft seal 3 pipeline to the high-temperature section seal of the main shaft;

[0053] The overflow pipe 23 is lower than the elevation of the lower cylinder of the steam turbine 1, and the flow regulating valve is provided with a minimum opening protection. The flow capacity of the overflow pipe 23 at the minimum opening is greater than the maximum water spraying amount of the atomizing nozzle 12. In extreme cases, the accumulated water in the pressure equalizing tank 6 will only be discharged along the overflow pipe 23 and will not flow back to the seal of the main shaft high-pressure shaft seal 3, thereby avoiding the problem of local sudden cooling causing deformation of the cylinder and rotor, and realizing inherent safety.

[0054] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0055] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A steam turbine shaft seal steam supply system, characterized in that: include: A pressure equalizing box is connected to a first pipeline and a second pipeline, wherein the first pipeline and the second pipeline are respectively connected to a high-pressure shaft seal and a low-pressure shaft seal of the steam turbine; A cooling component, comprising an atomizing nozzle installed on the second pipe, a third pipe connected to the atomizing nozzle for conveying cooling water, and a cooling water regulating valve installed on the third pipe; An overflow pipe, one end of which is connected to the top of the pressure equalizing tank, is provided with an overflow regulating valve, and the overflow regulating valve is provided with a minimum opening. When the overflow pipe is at the minimum opening, the flow capacity of the overflow pipe is greater than the maximum water spraying amount of the atomizing nozzle.

2. The steam supply system for steam turbine shaft seal according to claim 1, characterized in that: The steam turbine shaft seal steam supply system comprises: The condenser is located below the steam turbine, and the condenser is connected to an end of the overflow pipe away from the pressure equalizing tank.

3. The steam supply system for steam turbine shaft seal according to claim 1, characterized in that: The second pipeline is equipped with a steam-water separation tank, which is farther away from the pressure equalizing tank than the atomizing nozzle along the second pipeline. The steam-water separation tank is connected to the first drain pipeline, and the first drain pipeline is equipped with a steam trap.

4. The steam supply system for steam turbine shaft seal according to claim 1, characterized in that: The pressure equalizing tank is connected to a second drain pipe, the second drain pipe is connected to the bottom of the pressure equalizing tank, and a drain trap is installed in the second drain pipe.

5. The steam supply system for steam turbine shaft seal according to claim 1, characterized in that: The pressure equalizing tank is connected to a fourth pipeline, the fourth pipeline is used to transport auxiliary steam, the fourth pipeline is installed with a fourth stop valve, the pipe body of the fourth pipeline is connected to a third drain pipeline and is connected to the side of the fourth stop valve away from the pressure equalizing tank, and the third drain pipeline is installed with a drain.

6. The steam supply system for steam turbine shaft seal according to claim 1, characterized in that: The second pipeline is equipped with a steam-water separation tank, which is farther away from the pressure equalizing tank than the atomizing nozzle along the second pipeline, and the steam-water separation tank is connected to the first drain pipeline, and the first drain pipeline is equipped with a steam trap; The pressure equalizing tank is connected to a second drain pipe, the second drain pipe is connected to the bottom of the pressure equalizing tank, and a steam trap is installed in the second drain pipe; The pressure equalizing tank is connected to a fourth pipeline, the fourth pipeline is used to transport auxiliary steam, the fourth pipeline is installed with a fourth stop valve, the pipe body of the fourth pipeline is connected to a third drain pipeline and is connected to a side of the fourth stop valve away from the pressure equalizing tank, and the third drain pipeline is installed with a steam trap; The steam turbine shaft seal steam supply system includes a condenser and a drain main pipe. The condenser is connected to the drain main pipe and the overflow pipe. The drain main pipe is connected to the first drain pipe, the second drain pipe and the third drain pipe.

7. The steam supply system for steam turbine shaft seal according to claim 6, characterized in that: The connection point between the overflow pipe and the condenser is higher than the connection point between the drain main pipe and the condenser.

8. The steam supply system for a steam turbine shaft seal according to any one of claims 1 to 7, characterized in that: The pressure equalizing box is connected with a first pressure gauge, a first temperature gauge and a safety valve.

9. The steam supply system for a steam turbine shaft seal according to any one of claims 1 to 7, characterized in that: The second pipeline is connected to a second temperature meter.

10. The steam supply system for a steam turbine shaft seal according to any one of claims 1 to 7, characterized in that: The overflow pipe is lower than the lower cylinder of the steam turbine.

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