CN111927566A - Shaft seal system for large back pressure steam turbine - Google Patents
Shaft seal system for large back pressure steam turbine Download PDFInfo
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- CN111927566A CN111927566A CN202010630388.9A CN202010630388A CN111927566A CN 111927566 A CN111927566 A CN 111927566A CN 202010630388 A CN202010630388 A CN 202010630388A CN 111927566 A CN111927566 A CN 111927566A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
- F01D11/02—Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type
- F01D11/04—Preventing or minimising internal leakage of working-fluid, e.g. between stages by non-contact sealings, e.g. of labyrinth type using sealing fluid, e.g. steam
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/08—Cooling; Heating; Heat-insulation
- F01D25/10—Heating, e.g. warming-up before starting
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D25/00—Component parts, details, or accessories, not provided for in, or of interest apart from, other groups
- F01D25/08—Cooling; Heating; Heat-insulation
- F01D25/12—Cooling
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
The invention discloses a shaft seal system for a large back pressure turbine, and relates to the technical field of design of turbine shaft seal systems; the device comprises a shaft seal steam leakage system and a shaft seal steam supply system; the shaft seal steam supply system comprises a steam supply main pipe, an overflow pipeline, an auxiliary steam supply pipeline and a main steam supply pipeline, wherein the steam supply main pipe is communicated with a front and rear shaft seal steam supply branch pipe of the high-pressure cylinder and a front and rear shaft seal steam supply branch pipe of the intermediate pressure cylinder; through implementing this technical scheme, can start, operate, shut down under the various operating modes at back pressure steam turbine, for cylinder tip bearing seal provides suitable vapour source, prevent that the air from passing through the axle head and getting into the steam turbine, reach simultaneously and let the quick warm-up of steam turbine, reduce the purpose of thermal shock.
Description
Technical Field
The invention relates to the technical field of design of a steam turbine shaft seal system, in particular to a shaft seal system for a large back pressure steam turbine.
Background
The steam turbine shaft seal system is arranged at the position where the rotor of the steam turbine penetrates out of the cylinder, because the rotor of the steam turbine must penetrate through the cylinder and is supported on the bearing, and a gap is needed when the rotor penetrates out of the cylinder, when the steam turbine shaft seal system operates normally, for the two ends of the high-pressure cylinder and the medium-pressure cylinder, the steam pressure in the cylinder is greater than the external environmental pressure, part of steam leaks out from the gap, so that working medium and energy loss is caused, and the leaked steam can enter a steam turbine bearing box to influence the quality of lubricating oil and the normal operation of the; therefore, the steam turbine shaft seal system has the functions of preventing air from entering the cylinder or preventing steam from leaking out of the cylinder, recovering the gland seal leakage steam of the steam turbine, heating partial condensed water by using the heat of the gland seal system, and simultaneously extracting a mixture of the steam turbine shaft seal system to prevent the steam from leaking into a machine room and an oil system.
However, for some high-parameter, large-capacity and back pressure units with steam discharge parameters close to the large steam pressure, the existing back pressure unit shaft seal system cannot ensure different start-stop working conditions, the steam turbine can quickly and effectively achieve the warming-up effect, and it cannot be ensured that no air enters the steam turbine under all working conditions to cause safety accidents.
Disclosure of Invention
In order to solve the technical problem that the design of the existing backpressure turbine unit shaft seal system can not meet the operation requirement of a backpressure turbine with high parameter, large capacity and steam exhaust parameter close to atmospheric pressure, the invention aims to provide the shaft seal system for the large backpressure turbine, and aims to provide a proper steam source for the shaft seal at the end part of a cylinder under various working conditions of starting, running and stopping of the backpressure turbine, prevent air from entering the turbine through the shaft end, simultaneously achieve the purposes of quickly warming up the turbine and reducing thermal shock, and have good popularization and use performance.
The technical scheme adopted by the invention is as follows:
a shaft seal system for a large back pressure steam turbine comprises a shaft seal steam leakage system and a shaft seal steam supply system; the shaft seal steam supply system comprises
The steam supply main pipe is communicated with a high-pressure cylinder front shaft seal steam supply branch pipe, a high-pressure cylinder rear shaft seal steam supply branch pipe, a middle-pressure cylinder front shaft seal steam supply branch pipe and a middle-pressure cylinder rear shaft seal steam supply branch pipe of the steam turbine;
the overflow pipeline is connected to the steam supply main pipe, an overflow station regulating valve is arranged on the overflow pipeline, and the overflow station regulating valve is used for controlling the pressure of the steam supply main pipe to meet the design requirement;
the auxiliary steam supply pipeline is communicated with the steam supply main pipe, so that when the unit is started, external steam is supplied to the high-pressure cylinder and the intermediate-pressure cylinder through the auxiliary steam supply pipeline;
and the main steam supply pipeline is communicated with the steam supply main pipe so as to supply external steam to the high-pressure cylinder and the intermediate-pressure cylinder shaft seal through the main steam supply pipeline when the auxiliary steam parameters do not meet the requirements when the unit is started in a hot state.
The working principle is as follows: the technical scheme is that the shaft seal system is a self-sealing steam seal system, when a unit normally operates, shaft seals of all sections of a high-pressure cylinder and a medium-pressure cylinder of a steam turbine are in a steam leakage state, a rear shaft seal of the medium-pressure cylinder of the steam turbine in part of working conditions needs a small amount of steam, the steam is supplied by the front shaft seal of the high-pressure cylinder, the rear shaft seal of the high-pressure cylinder and the front shaft seal of the medium-pressure cylinder, and the surplus steam leaks and flows out through an overflow; according to the inventor of the application, the existing shaft seal system of the backpressure turbine set is only provided with a shaft seal steam leakage system but not a shaft seal steam supply system, and cannot meet the operation requirements of the backpressure turbine with high parameters, large capacity and steam exhaust parameters close to atmospheric pressure.
As a preferred scheme, an auxiliary steam station regulating valve is configured on the auxiliary steam supply pipeline, and the auxiliary steam station regulating valve is used for controlling parameters of steam supply to the high-pressure cylinder and the intermediate-pressure cylinder shaft seal through the auxiliary steam supply pipeline to meet design requirements.
As a preferred scheme, a main steam station regulating valve is arranged on the main steam supply pipeline and used for controlling parameters of steam supply to the high-pressure cylinder and the intermediate-pressure cylinder shaft seal through the main steam supply pipeline to meet design requirements.
Preferably, the overflow pipeline is connected with a steam recoverer, so that redundant leaked steam of the shaft seals of the high-pressure cylinder and the intermediate-pressure cylinder flows to the steam recoverer through the adjusting valve of the overflow station.
Preferably, an overflow station water spraying desuperheater is further arranged on the overflow pipeline, and the overflow station water spraying desuperheater is located in the downstream direction of the overflow station adjusting valve; the overflow station water spraying desuperheater is connected with a first water supply pipeline, and an overflow station desuperheating water spraying valve is arranged on the first water supply pipeline, so that overflow steam in the overflow pipeline is desuperheated to be within an acceptable range of the steam recoverer.
Preferably, a steam supply and water spray desuperheater is arranged on a pipeline from the steam supply main pipe to the rear shaft seal steam supply branch pipe of the intermediate pressure cylinder, the steam supply and water spray desuperheater is connected with a second water supply pipeline, and a water spray regulating valve is arranged on the second water supply pipeline, so that the temperature of steam supplied to the rear shaft seal steam supply branch pipe of the intermediate pressure cylinder through the steam supply main pipe is controlled within a design requirement range.
Preferably, a steam-water separator is arranged in the downstream direction of the steam supply and water spray desuperheater and used for separating water which is not fully vaporized after the water is sprayed by the steam supply and water spray desuperheater, so that the water which is not fully vaporized after the water is sprayed is separated out, and the problem that the safe operation of the steam turbine is influenced due to the fact that water enters a rear shaft seal of the intermediate pressure cylinder is avoided.
Preferably, a steam discharge pipe is connected to the steam supply branch pipe of the rear shaft seal of the intermediate pressure cylinder, which is close to the steam supply end of the rear shaft seal of the intermediate pressure cylinder, and is connected to the steam recoverer, and a throttle orifice plate is arranged on the steam discharge pipe, so that steam leakage of the rear shaft seal of the intermediate pressure cylinder flows to the steam recoverer through the throttle orifice plate under the condition of medium pressure cylinder exhaust overpressure. This technical scheme is provided with at the pipeline that supplies vapour mother pipe to intermediate pressure cylinder rear shaft seal to supply vapour branch pipe to last technical scheme and supplies vapour water spray desuperheater, it is palirrhea to the high-pressure cylinder section and will supply the water spray area on the vapour pipeline to high-pressure cylinder section bearing seal to prevent that intermediate pressure cylinder rear shaft seal from leaking vapour, influence high-pressure cylinder section bearing seal temperature, the bearing seal steam supply system that this technical scheme provided from this includes that it connects to the steam recovery ware to establish the throttle orifice plate at intermediate pressure cylinder rear shaft seal steam supply end, be used for guaranteeing that intermediate pressure cylinder rear shaft seal leaks vapour and does not flow backwards, so that under intermediate pressure cylinder steam exhaust superpressure operating mode, when the steam leakage quantity is more behind the intermediate pressure cylinder, be unlikely to make intermediate pressure cylinder rear shaft seal leak vapour and will supply the water spray area on the vapour mother pipe to high-pressure cylinder before the high-pressure cylinder, influence high-pressure cylinder front shaft seal.
Preferably, a safety valve is further arranged on the steam supply main pipe, and the safety valve is mounted on the steam supply main pipe and used for preventing the shaft seal system from overpressure.
Preferably, the shaft seal steam leakage system comprises a shaft seal heater, a shaft seal steam leakage pipeline and a steam drainage pipeline corresponding to the shaft seal steam leakage pipeline, and steam leakage at the tail end of the shaft seal of the high-pressure cylinder and the shaft seal of the intermediate-pressure cylinder of the steam turbine flows to the shaft seal heater through the shaft seal steam leakage pipeline so as to enable the shaft seal heater to always keep micro-negative pressure operation.
As described above, the present invention has at least the following advantages over the prior art:
1. the shaft seal system is provided with the shaft seal steam supply system, is combined with the shaft seal steam leakage system, can effectively solve the technical problem that the design of the shaft seal system of the existing backpressure unit can not meet the operation requirement of a backpressure steam turbine with high parameter, large capacity and steam exhaust parameter close to large steam pressure, can provide a proper steam source for the shaft seal at the end part of a cylinder under various working conditions of starting, running and stopping of the backpressure steam turbine, prevents air from entering the steam turbine through the shaft end, simultaneously achieves the purposes of quickly warming up the steam turbine and reducing thermal shock, and has good popularization and use performance.
2. The shaft seal system is provided with an auxiliary steam supply pipeline connected with a steam supply main pipe, so that when a unit is started in a hot state, parameters of supplying steam to the shaft seal of a high-pressure cylinder and a medium-pressure cylinder through the auxiliary steam supply pipeline are controlled to meet design requirements by using an auxiliary steam station regulating valve configured on the unit; meanwhile, a main steam supply pipeline is designed, so that when the unit is started in a hot state or an extremely hot state, steam supply for the shaft seal is provided by the main steam supply pipeline, and parameters of supplying steam to the shaft seal of the high-pressure cylinder and the intermediate-pressure cylinder through the main steam supply pipeline are controlled to meet design requirements by utilizing a main steam station regulating valve configured on the main steam station regulating valve.
3. According to the shaft seal system, the overflow pipeline is arranged on the steam supply main pipe, and the design of the overflow station regulating valve on the overflow pipeline can control the pressure of the steam supply main pipe to meet the design requirement; and the design that the overflow pipeline is connected with the steam recoverer ensures that redundant leaked steam of the shaft seal of the high-pressure cylinder and the intermediate-pressure cylinder is recovered to the steam recoverer; meanwhile, the design of the water spraying desuperheater of the overflow station on the overflow pipeline can desuperheat the overflow steam in the overflow pipeline to the acceptable range of the steam recoverer.
4. The shaft seal system is provided with a steam supply water spray desuperheater on a pipeline for a steam main pipe to flow to a steam supply branch pipe of the rear shaft seal of the intermediate pressure cylinder aiming at matching the rear shaft seal temperature of the intermediate pressure cylinder, so that the steam supply temperature of the rear shaft seal of the intermediate pressure cylinder through the steam supply main pipe is controlled within a design requirement range; and a steam-water separator is arranged in the downstream direction of the steam supply and water spray desuperheater, so that water which is not fully vaporized after water spray is separated out, and the influence on the safe operation of the steam turbine caused by water inflow of a rear shaft seal of the intermediate pressure cylinder is prevented.
5. According to the shaft seal system, the steam discharge pipe is connected to the steam supply branch pipe of the rear shaft seal of the intermediate pressure cylinder, which is close to the steam supply end of the rear shaft seal of the intermediate pressure cylinder, and the throttling orifice plate is designed on the steam discharge pipe and connected to the steam recoverer, so that the phenomenon that the steam leakage of the rear shaft seal of the intermediate pressure cylinder flows back to the high pressure cylinder section to spray water on a steam supply pipeline to the shaft seal of the high pressure cylinder section can be effectively prevented, the temperature of the shaft seal of the high pressure cylinder section is influenced, and the steam leakage.
Drawings
The invention will be described by way of specific embodiments and with reference to the accompanying drawings, in which
FIG. 1 is a schematic view of a shaft seal system for a large back pressure turbine according to an embodiment of the present invention.
Description of reference numerals: 1-steam supply main pipe; 2-a steam supply branch pipe of the front shaft seal of the high-pressure cylinder; 3-a steam supply branch pipe of the rear shaft seal of the high-pressure cylinder; 4-sealing a steam supply branch pipe at the front shaft of the intermediate pressure cylinder; 5-sealing a steam supply branch pipe of the rear shaft of the intermediate pressure cylinder; 6-an overflow pipe; 7-overflow station regulating valve; 8-auxiliary steam supply pipeline; 9-main steam supply pipeline; 10-auxiliary steam station regulating valve; 11-main station regulating valve; 12-a steam recoverer; 13-a water spraying desuperheater of the overflow station; 14-a first water supply conduit; 15-a temperature-reducing water spray valve of the overflow station; 16-steam supply and water spraying desuperheater; 17-a second water supply conduit; 18-water spray regulating valve; 19-a steam-water separator; 20-a steam discharge pipe; 22-orifice plate; 23-a shut-off valve; 24-a safety valve; 25-high pressure cylinder; 26-a medium pressure cylinder; 27-a shaft seal heater; 28-shaft seal steam leakage pipeline; 29-hydrophobic pipeline.
Detailed Description
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
Any feature disclosed in this specification (including any accompanying claims, abstract) may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
Example one
One embodiment is substantially as shown in FIG. 1: the embodiment provides a shaft seal system for a large-scale back pressure turbine, which aims at solving the technical problem that the design of the shaft seal system of the existing back pressure turbine set cannot meet the operation requirement of the back pressure turbine with high parameters, large capacity and steam exhaust parameters close to the large steam pressure, and comprises a shaft seal steam leakage system and a shaft seal steam supply system; specifically, the shaft seal supplies vapour system including supplying female pipe 1 of vapour, overflow pipe 6, supplementary steam supplies vapour pipeline 8 and main steam to supply vapour pipeline 9, wherein, supply female pipe 1 of vapour and the high-pressure cylinder 25 front shaft seal of steam turbine to supply vapour branch pipe 2, high-pressure cylinder 25 back shaft seal supplies vapour branch pipe 3 and intermediate pressure cylinder 26 front shaft seal to supply vapour branch pipe 4 and intermediate pressure cylinder 26 back shaft seal to supply vapour branch pipe 5 to communicate, overflow pipe 6 connects on supplying female pipe 1 of vapour, dispose overflow station governing valve 7 on the overflow pipe 6, overflow station governing valve 7 is used for controlling and supplies female pipe 1 pressure of vapour to satisfy the designing requirement.
The auxiliary steam supply pipeline 8 provided by the embodiment is communicated with the steam supply main pipe 1, so that when the unit is started in a cold state, shaft seal steam supply is provided by the auxiliary steam supply pipeline 8, and external steam is provided for the shaft seals of the high-pressure cylinder 25 and the medium-pressure cylinder 26 through the auxiliary steam supply pipeline 8; and an auxiliary steam station regulating valve 10 is arranged on the auxiliary steam supply pipeline 8, and the auxiliary steam station regulating valve 10 is used for controlling parameters of steam supply to the high-pressure cylinder 25 and the medium-pressure cylinder 26 through the auxiliary steam supply pipeline 8 to meet design requirements.
The main steam supply pipeline 9 provided by the embodiment is communicated with the steam supply main pipe 1, so that when the unit is started in a hot state or an extremely hot state, shaft seal steam supply is provided by the main steam supply pipeline 9, external steam is provided for the shaft seals of the high-pressure cylinder 25 and the medium-pressure cylinder 26 through the main steam supply pipeline 9, and the steam temperature provided by the main steam supply pipeline 9 is higher than that provided by the auxiliary steam supply pipeline 8; and a main steam station regulating valve 11 is arranged on the main steam supply pipeline 9, and the main steam station regulating valve 11 is used for controlling parameters of steam supply to the high-pressure cylinder 25 and the intermediate-pressure cylinder 26 through the main steam supply pipeline 9 to meet design requirements.
The working principle of the technical scheme is as follows: the shaft seal system provided by the embodiment is a self-sealing steam seal system, when the unit normally operates, shaft seals of each section of a high-pressure cylinder 25 and a middle-pressure cylinder 26 of a steam turbine are in a steam leakage state, a small amount of steam is required to be supplied to a rear shaft seal of the middle-pressure cylinder 26 of the steam turbine under partial working conditions, the steam is supplied by the front shaft seal of the high-pressure cylinder 25, the rear shaft seal of the high-pressure cylinder 25 and the front shaft seal of the middle-pressure cylinder 26, and redundant air leakage flows out and is; research shows that the design of the shaft seal system of the existing backpressure turbine unit can not meet the operation requirements of the backpressure turbine with high parameters, large capacity and steam exhaust parameters close to atmospheric pressure, and only a shaft seal air leakage system is designed without a shaft seal air supply system, the key point of the shaft seal steam supply system provided by the embodiment is that at the unit starting or low-load operation stage, an auxiliary steam supply pipeline 8 or a main steam supply pipeline 9 is used for supplying external steam for steam seal steam supply of a bearing system, the steam seal system is operated from unit starting to full load, the whole process can be automatically switched according to the steam seal steam supply requirements of the unit, and particularly: when the unit is started in a cold state, shaft seal steam supply is provided by the auxiliary steam supply pipeline 8, and external steam is provided for the shaft seals of the high-pressure cylinder 25 and the medium-pressure cylinder 26 through the main steam supply pipeline 9; when the unit is started in a hot state or an extremely hot state, shaft seal steam supply is provided by a main steam supply pipeline 9, and external steam is provided for the shaft seals of the high-pressure cylinder 25 and the medium-pressure cylinder 26 through the main steam supply pipeline 9; through the implementation of above-mentioned scheme, under various operating modes of back pressure steam turbine start-up, operation, shut down, can provide suitable vapour source for cylinder tip bearing seal, prevent that the air from passing through the axle head and getting into the steam turbine, reach simultaneously and let the quick warm-up of steam turbine to reduce the purpose of thermal shock.
As a preferred option of this embodiment, the overflow pipe 6 provided in this embodiment is connected to a steam recovery device 12, so that the excess leakage steam of the shaft seals of the high pressure cylinder 25 and the medium pressure cylinder 26 flows to the steam recovery device 12 through the overflow station regulating valve 7, and the excess leakage steam is recovered by the steam recovery device 12, which is simple in design but ingenious and reasonable; meanwhile, an overflow station water spraying desuperheater 13 is further arranged on the overflow pipeline 6, the overflow station water spraying desuperheater 13 is located in the downstream direction of the overflow station adjusting valve 7, the overflow station water spraying desuperheater 13 is connected with a first water supply pipeline 14, and an overflow station temperature reducing water spraying valve 15 is arranged on the first water supply pipeline 14, so that overflowing steam in the overflow pipeline 6 is cooled to a range capable of being accepted by the steam recoverer 12.
In addition, a safety valve 24 is further configured on the steam supply main pipe 1, the safety valve 24 is installed on the steam supply main pipe 1, and the safety valve 24 provided in this embodiment is used for preventing the overpressure of the shaft seal system in the upstream direction of the steam supply main pipe 1, which is located in the front shaft seal steam supply branch pipe 2 of the high-pressure cylinder 25, the rear shaft seal steam supply branch pipe 3 of the high-pressure cylinder 25, the front shaft seal steam supply branch pipe 4 of the intermediate-pressure cylinder 26 and the rear shaft seal steam supply branch pipe 5 of the intermediate-pressure cylinder 26.
The shaft seal steam leakage system provided by this embodiment includes a shaft seal heater 27, a shaft seal steam leakage pipeline 28 and a steam drain pipeline 29 corresponding to the shaft seal steam leakage pipeline 28, and the shaft seal tail-section steam leakage of the high-pressure cylinder 25 and the middle-pressure cylinder 26 of the steam turbine flows to the shaft seal heater 27 through the shaft seal steam leakage pipeline 28, so that the shaft seal heater 27 always keeps micro-negative pressure operation.
Through the implementation of the scheme, the shaft seal system can provide a proper steam source for the shaft seal at the end part of the cylinder under various working conditions of starting, running and stopping of the back pressure type steam turbine, so that air is prevented from entering the steam turbine through the shaft end, and meanwhile, the purposes of quickly warming up the steam turbine and reducing thermal shock are achieved; the steam seal at the shaft end of the steam turbine and the valve rod leakage and steam-gas mixture of the main steam regulating valve of the high pressure cylinder 25 and the intermediate pressure cylinder 26 are guided and recovered, so that the steam is prevented from leaking into a workshop and even entering a bearing box to cause the water in lubricating oil to enter.
Example two
The second embodiment is basically the same as the first embodiment in terms of preferred solutions, and the differences are as follows: the embodiment provides a bearing seal system for large-scale back pressure steam turbine, to at each operating condition, the bearing seal temperature is all lower behind the intermediate pressure jar 26, for matching the bearing seal temperature behind the intermediate pressure jar 26, this embodiment disposes a steam supply water spray desuperheater 16 on supplying main pipe 1 of vapour to the pipeline that intermediate pressure jar 26 back bearing seal supplied branch pipe 5, steam supply water spray desuperheater 16 is connected with second water supply pipe 17, be provided with water spray regulating valve 18 on second water supply pipe 17, so that supply steam temperature control in the design requirement within range to intermediate pressure jar 26 back bearing seal through supplying main pipe 1 of vapour.
Preferably, a steam-water separator 19 is disposed downstream of the steam supply and spray attemperator 16 for separating water that is not sufficiently vaporized after spraying water through the steam supply and spray attemperator 16, so that the water that is not sufficiently vaporized after spraying water is separated, and the water is prevented from entering the rear shaft seal of the intermediate pressure cylinder 26 to affect the safe operation of the steam turbine.
Meanwhile, under the normal operation condition, the exhaust pressure of the intermediate pressure cylinder 26 is lower and is close to the pressure of the steam supply main pipe 1, so that the rear shaft seal steam leakage flow of the intermediate pressure cylinder 26 is low; however, when the unit is started and part of the working conditions are abnormal, a small amount of steam needs to be supplied to the rear shaft seal of the intermediate pressure cylinder 26, and when the intermediate pressure cylinder 26 discharges steam and has overpressure, the shaft seal leakage flow of the intermediate pressure cylinder 26 is large; in the embodiment, a steam discharge pipe 20 is connected to a rear shaft seal steam supply branch pipe 5 of the intermediate pressure cylinder 26 close to a rear shaft seal steam supply end of the intermediate pressure cylinder 26, the steam discharge pipe 20 is connected to the steam recoverer 12, a throttle orifice plate 22 is arranged on the steam discharge pipe 20, a shut-off valve 23 is arranged in the upstream direction of the throttle orifice plate 22, the shut-off valve 23 is in a closed state under a normal working condition, the shut-off valve 23 is opened under the condition of steam discharge overpressure of the intermediate pressure cylinder 26, and steam leakage of the rear shaft seal of the intermediate pressure cylinder 26 flows to the steam recoverer 12 through the throttle orifice plate 22; the design of the throttle orifice plate 22 on the steam discharge pipe 20 and the steam discharge pipe 20 of this embodiment can effectively prevent the back shaft seal leakage steam of the intermediate pressure cylinder 26 from flowing backward to the high pressure cylinder 25 section and bringing the water spray on the steam supply pipeline to the high pressure cylinder 25 section shaft seal, and influence the shaft seal temperature of the high pressure cylinder 25 section, so the shaft seal steam supply system provided by this embodiment includes that the throttle orifice plate 22 is arranged at the back shaft seal steam supply end of the intermediate pressure cylinder 26 and connected to the steam recoverer 12, so as to ensure that the back shaft seal leakage steam of the intermediate pressure cylinder 26 does not flow backward, so that under the medium pressure cylinder exhaust steam overpressure condition, when the shaft seal leakage steam amount of the intermediate pressure cylinder is large, it is unlikely that the back shaft seal leakage steam of the intermediate pressure cylinder will bring the water spray on the steam supply main pipe to the front shaft seal of the high pressure cylinder, the back shaft seal of the high.
In conclusion, the shaft seal system provided by the invention is provided with the shaft seal steam supply system, and is combined with the shaft seal steam leakage system, so that the technical problem that the design of the shaft seal system of the existing backpressure turbine set cannot meet the operation requirement of a backpressure turbine with high parameter, large capacity and steam exhaust parameter close to large steam pressure can be effectively solved, a proper steam source can be provided for the shaft seal at the end part of a cylinder under various working conditions of starting, operation and stopping of the backpressure turbine, air is prevented from entering the turbine through the shaft end, meanwhile, the purpose of quickly warming up the turbine and reducing thermal shock is achieved, and the shaft seal system has good popularization and usability.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A shaft seal system for a large back pressure turbine, characterized in that: comprises a shaft seal steam leakage system and a shaft seal steam supply system; the shaft seal steam supply system comprises
The steam supply main pipe is communicated with a high-pressure cylinder front shaft seal steam supply branch pipe, a high-pressure cylinder rear shaft seal steam supply branch pipe, a middle-pressure cylinder front shaft seal steam supply branch pipe and a middle-pressure cylinder rear shaft seal steam supply branch pipe of the steam turbine;
the overflow pipeline is connected to the steam supply main pipe, an overflow station regulating valve is arranged on the overflow pipeline, and the overflow station regulating valve is used for controlling the pressure of the steam supply main pipe to meet the design requirement;
the auxiliary steam supply pipeline is communicated with the steam supply main pipe, so that when the unit is started, external steam is supplied to the high-pressure cylinder and the intermediate-pressure cylinder through the auxiliary steam supply pipeline;
and the main steam supply pipeline is communicated with the steam supply main pipe so as to supply external steam to the high-pressure cylinder and the intermediate-pressure cylinder shaft seal through the main steam supply pipeline when the auxiliary steam parameters do not meet the requirements when the unit is started in a hot state.
2. The shaft seal system for a large back pressure turbine according to claim 1, wherein: an auxiliary steam station regulating valve is arranged on the auxiliary steam supply pipeline and used for controlling parameters of steam supply to the high-pressure cylinder and the intermediate-pressure cylinder shaft seal through the auxiliary steam supply pipeline to meet design requirements.
3. The shaft seal system for a large back pressure turbine according to claim 1, wherein: and a main steam station regulating valve is arranged on the main steam supply pipeline and used for controlling parameters for supplying steam to the high-pressure cylinder and the intermediate-pressure cylinder shaft seal through the main steam supply pipeline to meet the design requirements.
4. The shaft seal system for a large back pressure turbine according to claim 1, wherein: and the overflow pipeline is connected with a steam recoverer so that redundant leaked steam of the shaft seals of the high-pressure cylinder and the intermediate-pressure cylinder flows to the steam recoverer through the adjusting valve of the overflow station.
5. The shaft seal system for a large back pressure turbine according to claim 4, wherein: an overflow station water spraying desuperheater is further arranged on the overflow pipeline and is positioned in the downstream direction of the overflow station adjusting valve; the overflow station water spraying desuperheater is connected with a first water supply pipeline, and an overflow station desuperheating water spraying valve is arranged on the first water supply pipeline, so that overflow steam in the overflow pipeline is desuperheated to be within an acceptable range of the steam recoverer.
6. The shaft seal system for a large back pressure turbine according to any one of claims 4 or 5, wherein: and a steam supply and water spray desuperheater is arranged on a pipeline from the steam supply main pipe to the rear shaft seal steam supply branch pipe of the intermediate pressure cylinder, the steam supply and water spray desuperheater is connected with a second water supply pipeline, and a water spray regulating valve is arranged on the second water supply pipeline so as to control the steam supply temperature of the rear shaft seal of the intermediate pressure cylinder within a design requirement range through the steam supply main pipe.
7. The shaft seal system for a large back pressure turbine according to claim 6, wherein: and a steam-water separator is arranged in the downstream direction of the steam supply water spray desuperheater and is used for separating water which is not fully vaporized after being sprayed by the steam supply water spray desuperheater.
8. The shaft seal system for a large back pressure turbine according to claim 6, wherein: and a steam discharge pipe is connected to the steam supply branch pipe of the middle-pressure cylinder rear shaft seal close to the steam supply end of the middle-pressure cylinder rear shaft seal, the steam discharge pipe is connected to a steam recoverer, and a throttling orifice plate is arranged on the steam discharge pipe.
9. The shaft seal system for a large back pressure turbine according to claim 1, wherein: and the safety valve is arranged on the steam supply main pipe and is used for preventing the shaft seal system from overpressure.
10. The shaft seal system for a large back pressure turbine according to claim 1, wherein: the shaft seal steam leakage system comprises a shaft seal heater, a shaft seal steam leakage pipeline and a steam drain pipeline corresponding to the shaft seal steam leakage pipeline, and steam leakage at the tail end of the shaft seal of the high-pressure cylinder and the middle-pressure cylinder of the steam turbine flows to the shaft seal heater through the shaft seal steam leakage pipeline so as to enable the shaft seal heater to always keep micro-negative pressure operation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010630388.9A CN111927566A (en) | 2020-07-03 | 2020-07-03 | Shaft seal system for large back pressure steam turbine |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010630388.9A CN111927566A (en) | 2020-07-03 | 2020-07-03 | Shaft seal system for large back pressure steam turbine |
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| CN111927566A true CN111927566A (en) | 2020-11-13 |
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| CN202010630388.9A Pending CN111927566A (en) | 2020-07-03 | 2020-07-03 | Shaft seal system for large back pressure steam turbine |
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| CN (1) | CN111927566A (en) |
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| CN113404556A (en) * | 2021-06-18 | 2021-09-17 | 东方电气集团东方汽轮机有限公司 | Steam turbine low pressure bearing seal cooling system |
| CN114215613A (en) * | 2021-12-14 | 2022-03-22 | 嘉利特荏原泵业有限公司 | Steam sealing system for condensing steam turbine |
| CN114382556A (en) * | 2021-12-28 | 2022-04-22 | 东方电气集团东方汽轮机有限公司 | Steam supply structure of steam turbine shaft seal system and adjusting method |
| CN114412597A (en) * | 2022-01-21 | 2022-04-29 | 山东核电有限公司 | Multi-steam-source auxiliary steam system of nuclear power unit and control method thereof |
| CN115788606A (en) * | 2022-12-15 | 2023-03-14 | 东方电气集团东方汽轮机有限公司 | Heat accumulating type shaft seal electric heating system and control method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113404556A (en) * | 2021-06-18 | 2021-09-17 | 东方电气集团东方汽轮机有限公司 | Steam turbine low pressure bearing seal cooling system |
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| CN114382556B (en) * | 2021-12-28 | 2023-08-18 | 东方电气集团东方汽轮机有限公司 | Steam supply structure of steam turbine shaft seal system and adjusting method |
| CN114412597A (en) * | 2022-01-21 | 2022-04-29 | 山东核电有限公司 | Multi-steam-source auxiliary steam system of nuclear power unit and control method thereof |
| CN115788606A (en) * | 2022-12-15 | 2023-03-14 | 东方电气集团东方汽轮机有限公司 | Heat accumulating type shaft seal electric heating system and control method |
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