Steam Seal Extraction System for Improving Vacuum Degree of Condensing Steam Turbine

Abstract

The utility model discloses a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine, comprising a steam turbine, wherein the positive pressure end and the negative pressure end of the steam turbine are respectively connected with a first steam seal unit and a second steam seal unit, a pressure equalizing box is connected between the first steam seal unit and the second steam seal unit, and the first steam seal unit and the second steam seal unit are respectively connected with an exhaust heater through a first exhaust pipe and a second exhaust pipe. After the utility model performs two steam seals on the negative pressure end seal of the steam turbine, air can be effectively prevented from entering the rear cylinder, thereby avoiding damage to the vacuum degree of the exhaust device and reducing oxygen corrosion, and the pressure of the sealing chamber of the negative pressure end of the condensing steam turbine can be freely controlled to maintain the vacuum degree of the steam turbine outlet during normal operation, thereby effectively improving the operating efficiency of the steam turbine, reducing energy consumption, and effectively reducing the corrosion of air to the flow components of the steam turbine.

Description

Technical Field

[0001] The utility model belongs to the technical field of steam seal equipment of steam turbines, and in particular relates to a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine. Background Art

[0002] The vacuum steam extraction seal system of condensing steam turbine unit mainly consists of five systems: vacuum pump, air cooling island, equalizing pressure box, steam extraction heater and steam seal of unit. The establishment of vacuum (≤-58KpaG) during operation is mainly guaranteed by the rapid cooling of non-condensable steam by air cooling island, vacuum pump, equalizing pressure box steam seal and steam extraction heater system.

[0003] During the operation of the condensing (negative pressure) steam turbine, when the pressure in the equalizing tank is 15KPaG-24KPaG, the air supply to the rear steam seal is insufficient, causing air to enter the exhaust device from the negative pressure end steam seal of the rear cylinder, thereby destroying the establishment of vacuum and causing oxygen corrosion of the turbine's circulation components.

[0004] If the pressure of the pressure equalizing tank is increased to 25KpaG-30KPaG, although it can meet the sealing steam volume requirement of the rear steam seal at the negative pressure end and improve the vacuum degree, the front steam seal at the positive pressure end will leak steam due to the increased pressure in the pressure equalizing tank. The leaked steam enters the lubricating oil system along the front bearing oil seal, causing the lubricating oil to be seriously water-containing and emulsified, threatening the safe operation of the unit.

[0005] The low outlet vacuum of the condensing (negative pressure) steam turbine not only seriously affects the economic benefits of the turbine operation, but also increases the exhaust temperature of the turbine. The rear cylinder and rotor expand due to heat, resulting in an increase in the expansion difference and an increase in the shaft displacement, which can easily cause friction between the dynamic and static systems of the turbine unit and threaten the safe operation of the unit. Utility Model Content

[0006] The utility model aims to provide a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine, which can control the pressure of the sealing cavity at the negative pressure end of the steam turbine to maintain the vacuum degree of the steam turbine outlet during normal operation.

[0007] The technical solution adopted by the utility model is a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine, comprising a steam turbine, wherein the positive pressure end and the negative pressure end of the steam turbine are respectively connected to a first steam seal unit and a second steam seal unit, a pressure equalizing box is connected between the first steam seal unit and the second steam seal unit, and the first steam seal unit and the second steam seal unit are respectively connected to steam extraction heaters through a first exhaust pipe and a second exhaust pipe.

[0008] The utility model is also characterized in that:

[0009] The first steam seal unit includes a previous stage steam seal, which is connected to the positive pressure end of the steam turbine, the end of the previous stage steam seal away from the steam turbine is connected to the previous stage steam seal, the previous stage steam seal is connected to the first exhaust pipe, the end of the first exhaust pipe away from the previous stage steam seal is connected to a connecting pipe, the end of the connecting pipe away from the first exhaust pipe is connected to the steam extraction heater, the previous stage steam seal is connected to the pressure equalizing box through the intake pipe, and the intake valve is connected to the pipe body of the intake pipe.

[0010] The second steam seal unit includes a rear-stage steam seal, which is connected to the negative pressure end of the steam turbine, the end of the rear-stage steam seal away from the steam turbine is connected to the rear-stage steam seal, the rear-stage steam seal is connected to the second exhaust pipe, the end of the second exhaust pipe away from the rear-stage steam seal is connected to the pipe body of the connecting pipe, the rear-stage steam seal is connected to the pressure equalizing box through the outlet pipe, and the pipe body of the outlet pipe is connected to the outlet valve.

[0011] The connection point between the rear steam seal and the air outlet pipe is arranged close to the rear second steam seal, and the connection point between the front steam seal and the air inlet pipe is arranged close to the front second steam seal.

[0012] An air supply pipe is connected between the pressure equalizing box and the second air extraction pipe, the pipe body of the air supply pipe is connected with an air supply valve, the pipe body of the second air extraction pipe is connected with an air extraction valve, and the air extraction valve is arranged close to the connecting pipe.

[0013] The top of the extraction steam heater is connected to a waste steam vent pipe, the body of the waste steam vent pipe is connected to a vent valve, the extraction steam heater is also connected to an extraction steam pipe, the body of the extraction steam pipe is connected to a gate valve, the extraction steam heater is also connected to a condensate pipe and a drain pipe, the body of the condensate pipe is connected to a condensate valve, and the body of the drain pipe is connected to a drain valve.

[0014] The pressure equalizing tank is connected with a steam supplementary pipe.

[0015] The beneficial effects of the utility model are:

[0016] The utility model discloses a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine. After performing two steam seals on the negative pressure end seal of the steam turbine, air can be effectively prevented from entering the rear cylinder, thereby avoiding damage to the vacuum degree of the exhaust device and reducing oxygen corrosion. The pressure of the seal cavity at the negative pressure end of the condensing steam turbine can be freely controlled to maintain the vacuum degree of the turbine outlet during normal operation. The utility model can effectively improve the operation efficiency of the steam turbine, reduce energy consumption, and effectively reduce the corrosion of the flow components of the steam turbine by air. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The utility model is a structural schematic diagram of a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine.

[0018] In the figure: 1. steam turbine, 2. equalizing pressure box, 21. steam supply pipe, 3. first exhaust pipe, 4. extraction heater, 41. exhaust steam vent pipe, 411. vent valve, 42. extraction steam pipe, 421. gate valve, 43. condensate pipe, 431. condensate valve, 44. drain pipe, 441. drain valve, 5. front first-stage steam seal, 51. air inlet pipe, 511. air inlet valve, 6. front second-stage steam seal, 7. second exhaust pipe, 71. exhaust valve, 8. connecting pipe, 9. rear first-stage steam seal, 91. outlet pipe, 911. outlet valve, 10. rear second-stage steam seal, 11. supply pipe, 111. supply valve. DETAILED DESCRIPTION

[0019] The utility model is described in detail below with reference to the accompanying drawings and specific implementation modes.

[0020] The utility model is a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine. Figure 1 As shown, it includes a steam turbine 1, the positive pressure end and the negative pressure end of the steam turbine 1 are respectively connected to the first steam seal unit and the second steam seal unit, the first steam seal unit and the second steam seal unit are connected to the equalizing pressure tank 2, and the first steam seal unit and the second steam seal unit are respectively connected to the steam extraction heater 4 through the first exhaust pipe 3 and the second exhaust pipe 7. Under normal working conditions, the steam at the positive pressure end of the steam turbine 1 leaks from the first steam seal unit. In order to prevent the leaked steam from entering the lubricating oil system along the front bearing oil seal, the steam leaked from the first steam seal unit enters the second equalizing pressure tank 2, and then from the equalizing pressure tank 2 to the second steam seal unit for steam sealing, to prevent air from entering the steam turbine 1 from the negative pressure end, the steam extraction heater 4 performs a vacuum operation to ensure the vacuum degree of the steam turbine 1.

[0021] Example 1

[0022] The first steam seal unit includes a first-stage steam seal 5, which is connected to the positive pressure end of the steam turbine 1, and the first-stage steam seal 6 is connected to the end of the first-stage steam seal 5 away from the steam turbine 1, and the first-stage steam seal 6 is connected to the first exhaust pipe 3, and the end of the first exhaust pipe 3 away from the first-stage steam seal 6 is connected to the connecting pipe 8, and the end of the connecting pipe 8 away from the first exhaust pipe 3 is connected to the steam extraction heater 4, and the first-stage steam seal 5 is connected to the pressure equalizing tank 2 through the intake pipe 51, and the pipe body of the intake pipe 51 is connected to the intake valve 511. The steam leaked from the first-stage steam seal 5 enters the pressure equalizing tank 2 through the intake pipe 51. If the leakage at the positive pressure end is too large, the intake pipe 51 does not have time to completely exhaust the steam, and the leaked steam enters the steam extraction heater 4 from the first-stage steam seal 6 through the first exhaust pipe 3 and the connecting pipe 8.

[0023] Example 2

[0024] The second steam seal unit includes a rear-stage steam seal 9, which is connected to the negative pressure end of the steam turbine 1, and the end of the rear-stage steam seal 9 away from the steam turbine 1 is connected to the rear-stage steam seal 10, which is connected to the second exhaust pipe 7, and the end of the second exhaust pipe 7 away from the rear-stage steam seal 10 is connected to the pipe body of the connecting pipe 8, and the rear-stage steam seal 9 is connected to the pressure equalizing tank 2 through the outlet pipe 91, and the pipe body of the outlet pipe 91 is connected to the outlet valve 911. The steam in the pressure equalizing tank 2 enters the rear-stage steam seal 9 through the outlet pipe 91 to perform steam sealing, so as to prevent air from entering the steam turbine 1 from the negative pressure end. If the steam leaked from the negative pressure end enters the steam extraction heater 4 from the second exhaust pipe 7 through the connecting pipe 8.

[0025] Example 3

[0026] The connection point between the rear steam seal 9 and the outlet pipe 91 is arranged close to the rear secondary steam seal 10, and the connection point between the front steam seal 5 and the inlet pipe 51 is arranged close to the front secondary steam seal 6. The connection point between the rear steam seal 9 and the outlet pipe 91 and the connection point between the front steam seal 5 and the inlet pipe 51 are arranged to ensure that the leaked steam is completely absorbed.

[0027] An air supply pipe 11 is connected between the pressure equalizing box 2 and the second air extraction pipe 7, and an air supply valve 111 is connected to the pipe body of the air supply pipe 11. An air extraction valve 71 is connected to the pipe body of the second air extraction pipe 7, and the air extraction valve 71 is arranged close to the connecting pipe 8. When the air extraction valve 71 is gradually closed, the steam extraction amount of the second steam seal unit can be reduced, and the sealing steam amount of the rear steam seal at the negative pressure end is correspondingly increased. If the sealing steam amount requirement of the rear steam seal at the negative pressure end is still not met after the air extraction valve 71 is completely closed, the air supply valve 111 can be opened appropriately to supply steam, and the steam extraction at the rear steam seal at the negative pressure end is changed to steam supply at the rear steam seal. After two steam seals are performed on the negative pressure end of the steam turbine 1, air can be effectively prevented from entering the rear cylinder, thereby avoiding the destruction of the vacuum degree and reducing oxygen corrosion.

[0028] Example 4

[0029] The top of the steam extraction heater 4 is connected with an exhaust steam vent pipe 41, the pipe body of the exhaust steam vent pipe 41 is connected with a vent valve 411, the steam extraction heater 4 is also connected with an extraction steam pipe 42, the pipe body of the extraction steam pipe 42 is connected with a gate valve 421, the steam extraction heater 4 is also connected with a condensate pipe 43 and a drain pipe 44, the pipe body of the condensate pipe 43 is connected with a condensate valve 431, and the pipe body of the drain pipe 44 is connected with a drain valve 441. The more steam leaked in the first exhaust pipe 3 and the second exhaust pipe 7, the more steam is required in the exhaust steam pipe 42, so that the leaked steam can be completely extracted, the condensate pipe 43 is connected with the steam turbine 1, the condensate in the steam turbine 1 enters the steam extraction heater 4 through the condensate pipe 43, and is discharged from the drain pipe 44 after condensation, and the gas in the steam extraction heater 4 is discharged through the exhaust steam vent pipe 41.

[0030] Example 5

[0031] The pressure equalizing tank 2 is connected to a steam supply pipe 21. If the steam leaked from the positive pressure end of the steam turbine 1 is not enough to seal the negative pressure end, steam is supplied to the pressure equalizing tank 2 through the steam supply pipe 21 to ensure steam sealing of the negative pressure end of the steam turbine 1.

[0032] The working principle of the steam seal exhaust system for improving the vacuum degree of condensing steam turbine of the utility model is as follows:

[0033] The steam leaked from the previous steam seal 5 enters the equalizing box 2 through the air inlet pipe 51. If the leakage at the positive pressure end is too large, the air inlet pipe 51 will not be able to exhaust the steam completely in time. The leaked steam will then enter the steam extraction heater 4 from the previous secondary steam seal 6 through the first exhaust pipe 3 and the connecting pipe 8. The steam in the equalizing box 2 enters the next steam seal 9 through the air outlet pipe 91 to be sealed to prevent air from entering the steam turbine 1 from the negative pressure end. If the steam leaked from the negative pressure end enters the steam extraction heater 4 from the second exhaust pipe 7 through the connecting pipe 8, when the exhaust When valve 71 is gradually closed, the steam extraction amount of the second steam seal unit can be reduced, and the sealing steam amount of the second steam seal unit can be correspondingly increased. When the air extraction valve 71 is completely closed and still cannot meet the sealing steam amount requirement of the rear steam seal at the negative pressure end, the air supply valve 111 can be opened appropriately to supply steam, and the steam extraction at the rear steam seal at the negative pressure end can be changed to steam supply at the rear steam seal. After two steam seals are performed on the negative pressure end of the steam turbine 1, air can be effectively prevented from entering the rear cylinder, thereby avoiding damage to the vacuum and reducing oxygen corrosion.

[0034] The utility model discloses a steam seal exhaust system for improving the vacuum degree of a condensing steam turbine, which can freely control the pressure of the sealing chamber at the negative pressure end of the condensing steam turbine to maintain the vacuum degree of the turbine outlet during normal operation, effectively improves the operation efficiency of the turbine, reduces energy consumption, and effectively reduces the corrosion of air on the flow components of the turbine.

Claims

1. A steam seal exhaust system for improving the vacuum degree of a condensing steam turbine, characterized in that: The invention comprises a steam turbine (1), wherein the positive pressure end and the negative pressure end of the steam turbine (1) are respectively connected to a first steam seal unit and a second steam seal unit, a pressure equalizing box (2) is connected between the first steam seal unit and the second steam seal unit, and the first steam seal unit and the second steam seal unit are respectively connected to a steam extraction heater (4) via a first exhaust pipe (3) and a second exhaust pipe (7).

2. The steam seal exhaust system for improving the vacuum degree of a condensing steam turbine according to claim 1, characterized in that: The first steam seal unit comprises a first-stage steam seal (5), the first-stage steam seal (5) being connected to the positive pressure end of the steam turbine (1), the first-stage steam seal (5) being connected to a first-stage steam seal (6) at one end away from the steam turbine (1), the first-stage steam seal (6) being connected to a first exhaust pipe (3), the first exhaust pipe (3) being connected to a connecting pipe (8) at one end away from the first-stage steam seal (6), the end of the connecting pipe (8) being away from the first exhaust pipe (3) being connected to an exhaust heater (4), the first-stage steam seal (5) being connected to a pressure equalizing tank (2) via an intake pipe (51), the intake pipe (51) being connected to an intake valve (511).

3. The steam seal exhaust system for improving the vacuum degree of a condensing steam turbine according to claim 1, characterized in that: The second steam seal unit comprises a rear-stage steam seal (9), the rear-stage steam seal (9) is connected to the negative pressure end of the steam turbine (1), the end of the rear-stage steam seal (9) away from the steam turbine (1) is connected to a rear-stage steam seal (10), the rear-stage steam seal (10) is connected to a second exhaust pipe (7), the end of the second exhaust pipe (7) away from the rear-stage steam seal (10) is connected to the pipe body of a connecting pipe (8), the rear-stage steam seal (9) is connected to the pressure equalizing box (2) via an exhaust pipe (91), and the pipe body of the exhaust pipe (91) is connected to an exhaust valve (911).

4. The steam seal exhaust system for improving the vacuum degree of a condensing steam turbine according to claim 3, characterized in that: The connection point between the rear steam seal (9) and the air outlet pipe (91) is arranged close to the rear secondary steam seal (10), and the connection point between the front steam seal (5) and the air inlet pipe (51) is arranged close to the front secondary steam seal (6).

5. The steam seal exhaust system for improving the vacuum degree of a condensing steam turbine according to claim 1, characterized in that: An air supply pipe (11) is connected between the pressure equalizing box (2) and the second air extraction pipe (7); the pipe body of the air supply pipe (11) is connected to an air supply valve (111); the pipe body of the second air extraction pipe (7) is connected to an air extraction valve (71); and the air extraction valve (71) is arranged close to the connecting pipe (8).

6. The steam seal exhaust system for improving the vacuum degree of a condensing steam turbine according to claim 1, characterized in that: The top of the extraction steam heater (4) is connected to a waste steam vent pipe (41), the body of the waste steam vent pipe (41) is connected to a vent valve (411), the extraction steam heater (4) is also connected to an extraction steam pipe (42), the body of the extraction steam pipe (42) is connected to a gate valve (421), the extraction steam heater (4) is also connected to a condensate pipe (43) and a drain pipe (44), the body of the condensate pipe (43) is connected to a condensate valve (431), and the body of the drain pipe (44) is connected to a drain valve (441).

7. The steam seal exhaust system for improving the vacuum degree of a condensing steam turbine according to claim 1, characterized in that: The pressure equalizing tank (2) is connected to a steam supplementary pipe (21).

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