Shaft seal steam supply system with standby steam source

Abstract

The utility model provides a shaft seal steam supply system with a standby steam source, which belongs to the field of steam supply systems and comprises a water feed pump turbine, a steam feed pump, a gearbox and a booster pump, the steam turbine steam supply pipeline, the auxiliary steam supply pipeline and the shaft seal steam return pipeline are respectively connected with the water feeding pump steam turbine; the steam feed pump is respectively connected with the booster pump and the high-pressure heater through a boiler water supply pipeline; the auxiliary steam supply pipeline is further connected with a standby steam source supply pipeline; the standby steam source steam supply pipeline is used for providing a standby steam source for the auxiliary steam supply pipeline. The steam supply of the shaft seal is changed from a single steam source to double steam sources, so that the stability and reliability of the steam sources are ensured, and the condition of splitting maintenance of the auxiliary steam header is met.

Description

Technical Field

[0001] The utility model relates to the field of steam supply systems, in particular to a shaft seal steam supply system with a spare steam source. Background Art

[0002] The steam source for the small steam turbine shaft seal system is taken from the auxiliary steam manifold to the manual steam supply door for the large turbine shaft seal. During normal operation of the unit, the steam source for the small steam turbine shaft seal is supplied by the auxiliary steam manifold. Because there is only this steam source, the auxiliary steam manifold cannot be decoupled for maintenance during unit operation. When the auxiliary steam manifold is abnormally decoupled, the small steam turbine shaft seal loses its steam source, causing unplanned shutdown of the unit. Utility Model Content

[0003] In order to overcome the deficiencies of the prior art, the purpose of the utility model is to provide a shaft seal steam supply system with a backup steam source, so that the shaft seal steam supply is changed from a single steam source to a dual steam source steam supply, which not only ensures the stability and reliability of the steam source, but also meets the conditions for de-energizing the auxiliary steam manifold for maintenance.

[0004] To achieve the above purpose, the utility model provides the following solutions:

[0005] A shaft seal steam supply system with a backup steam source, comprising: a feedwater pump turbine, a steam-driven feedwater pump and a gearbox connected to the feedwater pump turbine, a pre-pump connected to the gearbox, and a turbine steam supply pipeline, an auxiliary steam supply pipeline and a shaft seal return steam pipeline respectively connected to the feedwater pump turbine; the steam-driven feedwater pump is respectively connected to the pre-pump and the high-pressure heater through a boiler feedwater pipeline; the auxiliary steam supply pipeline is also connected to a backup steam source supply pipeline;

[0006] The feedwater pump turbine is used to provide a power source for the steam-driven feedwater pump and the pre-pump; the steam-driven feedwater pump is used to drive the feedwater in the boiler feedwater pipe to transport the feedwater to the high-pressure heater; the gearbox is used to reduce the power provided by the feedwater pump turbine to the pre-pump; the pre-pump is used to increase the pressure at the inlet of the steam-driven feedwater pump to prevent cavitation of the steam-driven feedwater pump; the high-pressure heater is used to heat the feedwater to increase the feedwater temperature; the boiler feedwater pipeline is used to carry the feedwater; the turbine steam supply pipeline is used to provide a power steam source for the feedwater pump turbine; the auxiliary steam supply pipeline is used to provide a shaft seal steam source for the feedwater pump turbine; the shaft seal return steam pipeline is used to transport the exhaust steam of the feedwater pump turbine; the standby steam source supply pipeline is used to provide a standby steam source for the auxiliary steam supply pipeline.

[0007] Preferably, the steam-driven water feed pump is a steam-driven water feed pump with 1×100% BMCR.

[0008] Preferably, the steam-driven feedwater pump and the pre-pump are coaxially connected, and the steam-driven feedwater pump and the pre-pump share the feedwater pump turbine.

[0009] Preferably, the shaft seal return steam pipeline is also connected to a condenser, and the condenser is used to cool the exhaust steam.

[0010] Preferably, a small steam turbine is arranged inside the feedwater pump steam turbine; the small steam turbine is equipped with a shaft end steam seal; the shaft end steam seal is used to reduce steam leakage at the high-pressure end and air leakage at the low-pressure end.

[0011] Preferably, the front pump is also connected to a deaerator water tank; the deaerator water tank is used to store feed water and provide water to the boiler feed water pipeline.

[0012] According to the specific embodiments provided by the utility model, the utility model discloses the following technical effects:

[0013] The utility model provides a shaft seal steam supply system with a spare steam source, which belongs to the field of steam supply systems, and includes: a feedwater pump turbine, a steam-driven feedwater pump and a gearbox connected to the feedwater pump turbine, a pre-pump connected to the gearbox, and a turbine steam supply pipeline, an auxiliary steam supply pipeline and a shaft seal return steam pipeline respectively connected to the feedwater pump turbine; the steam-driven feedwater pump is respectively connected to the pre-pump and the high-pressure heater through the boiler feedwater pipeline; the auxiliary steam supply pipeline is also connected to the spare steam source steam supply pipeline; the spare steam source steam supply pipeline is used to provide a spare steam source for the auxiliary steam supply pipeline. The utility model changes the shaft seal steam supply from a single steam source to a dual steam source steam supply, which not only ensures the stability and reliability of the steam source, but also meets the conditions for the auxiliary steam header to be disconnected for maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 A structural diagram of a shaft seal steam supply system provided in an embodiment of the utility model;

[0016] Description of reference numerals:

[0017] 1- feedwater pump turbine, 2- steam-driven feedwater pump, 3- fore pump, 4- high-pressure heater, 5- auxiliary steam supply pipeline, 6- standby steam source supply pipeline, 7- boiler feedwater pipeline, 8- turbine steam supply pipeline, 9- shaft seal return steam pipeline, 10- deaerator water tank, 11- gearbox, 12- check valve A, 13- check valve B. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0019] The utility model aims to provide a shaft seal steam supply system with a spare steam source, which changes the shaft seal steam supply from a single steam source to a dual steam source steam supply, thereby ensuring the stability and reliability of the steam source and meeting the conditions for decoupling the auxiliary steam header for maintenance.

[0020] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] Figure 1 This is the structural diagram of the shaft seal steam supply system, such as Figure 1 As shown, the utility model provides a shaft seal steam supply system with a backup steam source, comprising: a feedwater pump turbine 1, a steam-driven feedwater pump 2 and a gearbox 11 connected to the feedwater pump turbine 1, a pre-pump 3 connected to the gearbox 11, and a turbine steam supply pipeline 8, an auxiliary steam supply pipeline 5 and a shaft seal steam return pipeline 9 respectively connected to the feedwater pump turbine 1; the steam-driven feedwater pump 2 is respectively connected to the pre-pump 3 and the high-pressure heater 4 through a boiler feedwater pipeline 7; the auxiliary steam supply pipeline 5 is also connected to a backup steam source steam supply pipeline 6;

[0022] The feedwater pump turbine 1 is used to provide a power source for the steam-driven feedwater pump 2 and the pre-pump 3; the steam-driven feedwater pump 2 is used to drive the feedwater in the boiler feedwater pipe to transport the feedwater to the high-pressure heater 4; the gearbox 11 is used to reduce the power provided by the feedwater pump turbine 1 to the pre-pump 3; the pre-pump 3 is used to increase the pressure at the inlet of the steam-driven feedwater pump 2 to prevent cavitation of the steam-driven feedwater pump 2; the high-pressure heater 4 is used to heat the feedwater to increase the feedwater temperature; the boiler feedwater pipeline 7 is used to carry the feedwater; the turbine steam supply pipeline 8 is used to provide a power steam source for the feedwater pump turbine 1; the auxiliary steam supply pipeline 5 is used to provide a shaft seal steam source for the feedwater pump turbine 1; the shaft seal return steam pipeline 9 is used to transport the exhaust steam of the feedwater pump turbine 1; the standby steam source supply pipeline 6 is used to provide a standby steam source for the auxiliary steam supply pipeline 5.

[0023] In addition, the check valve A12 and the check valve B13 are both used to prevent the auxiliary steam supply pipeline and the backup steam source supply pipeline from cross-flowing with each other.

[0024] Optionally, the steam-driven water supply pump 2 is a steam-driven water supply pump with a 1×100% BMCR.

[0025] Specifically, the steam-driven feedwater pump 2 and the pre-pump 3 are coaxially connected, and the steam-driven feedwater pump 2 and the pre-pump 3 share the feedwater pump turbine 1 .

[0026] Specifically, the shaft seal return steam pipeline 9 is also connected to a condenser, and the condenser is used to cool the exhaust steam.

[0027] Optionally, a small steam turbine is arranged in the feedwater pump steam turbine 1; the small steam turbine is equipped with a shaft end steam seal; the shaft end steam seal is used to reduce steam leakage at the high-pressure end and air leakage at the low-pressure end.

[0028] Optionally, the front pump 3 is also connected to a deaerator water tank 10 ; the deaerator water tank 10 is used to store feed water and provide water to the boiler feed water pipeline 7 .

[0029] Furthermore, the feedwater system of each unit adopts a steam-driven feedwater pump of 1×100%BMCR, and the steam pump pre-pump 3 is driven by a small steam turbine, that is, the pre-pump 3 and the main pump are coaxially sharing a feedwater pump turbine 1 (feedwater pump turbine 1 has double-sided output, that is, feedwater pump-feedwater pump turbine 1-gearbox 11-pre-pump 3). The two groups of steam-driven feedwater pumps and the pre-pump 3 are coaxially arranged on the operation floor of the steam engine room, and the exhaust steam of the feedwater pump turbine 1 is discharged downward into the main engine condenser, and no butterfly valve is set on the exhaust steam pipeline.

[0030] Specifically, the water supply system process: the water supply from the deaerator water tank 10 drops to the inlet of the pre-pump 3 through a coarse filter, the water supply after being pressurized by the pre-pump 3 enters the inlet of the water supply pump through a fine filter, and the outlet water of the water supply pump converges to the outlet main pipe through an outlet check valve and an electric gate valve, and then enters the high-pressure heater 4 and the high-pressure external steam cooler in turn. An electric gate valve is provided on the water supply pipeline at the inlet of the economizer. In order to meet the regulation of the boiler feed water in the initial stage of the unit startup, the electric gate valve is equipped with a startup bypass with a capacity of 30% BMCR, and a pneumatic regulating valve is provided on the bypass pipeline.

[0031] Furthermore, the function of the feedwater pump and the feedwater pump steam turbine 1 is to drive the small steam turbine to rotate through the steam delivered by the four-stage steam extraction or the auxiliary steam header, and transmit the power to the pre-pump 3 through the coaxially connected reducer, and at the same time transmit the power to the steam-driven feedwater pump 2, ultimately providing high-pressure feedwater.

[0032] Specifically, the role of the shaft seal of a small steam turbine: the feed pump is driven by a small steam turbine. Although small steam turbines are equipped with shaft end steam seals, which can reduce steam leakage (high pressure end) or air leakage (low pressure end), it is still impossible to completely eliminate steam leakage. In order to prevent and reduce this steam leakage, to ensure the normal start and stop and operation of the unit, as well as to recover the leaked steam and utilize the heat of the leaked steam, and to reduce the system's working fluid loss and heat loss, small steam turbines are equipped with a steam seal system consisting of a shaft end steam seal plus pipes, valves and ancillary equipment connected to it.

[0033] Optionally, based on the original steam supply from the auxiliary steam manifold to the small steam turbine shaft seal, a backup steam source is introduced in front of the four-stage exhaust to the small steam turbine check valve (i.e., the four-stage exhaust to the small steam turbine shaft seal steam supply); the steam supply pressure of the backup steam source changes with the four-stage exhaust pressure, so as to meet the steam needs of the small steam turbine shaft seal during normal operation of the unit.

[0034] Specifically, during the normal operation of the unit, the spare steam source for the small steam turbine shaft seal is tested, and the auxiliary steam is disconnected to supply steam to the small steam turbine shaft seal, and the test meets the steam supply requirements for the small steam turbine shaft seal. When the auxiliary steam manifold needs to be disconnected for maintenance during the operation of the unit, the steam supply to the small steam turbine shaft seal is supplied by four-stage air extraction to ensure that the steam supply to the small steam turbine shaft seal is not interrupted and will not cause unplanned shutdown of the unit. The four-stage air extraction to the small steam turbine shaft seal is normally standby during the normal operation of the unit, and the steam supply to the small steam turbine shaft seal is flexibly switched. The probability of unplanned shutdown of the unit is reduced, the number of operating hours of the unit is increased, and the cost of starting and stopping the unit is greatly saved. According to the calculation that each start and shutdown of the unit costs 1 million, a failure can save 1 million.

[0035] The beneficial effects of the utility model are as follows:

[0036] (1) This embodiment changes the steam supply to the shaft seal from a single steam source to a dual steam source, which not only ensures the stability and reliability of the steam source, but also meets the conditions for disconnecting the auxiliary steam manifold for maintenance.

[0037] (2) This embodiment reduces the probability of unplanned shutdown of the unit, increases the number of unit operating hours, and greatly saves the cost of starting and stopping the unit.

[0038] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0039] This article uses specific examples to illustrate the principles and implementation methods of the utility model. The above examples are only used to help understand the method and core ideas of the utility model. At the same time, for those skilled in the art, according to the ideas of the utility model, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the utility model.

Claims

1. A shaft seal steam supply system with a backup steam source, comprising: A feedwater pump turbine, a steam-driven feedwater pump and a gearbox connected to the feedwater pump turbine, a pre-pump connected to the gearbox, and a steam turbine steam supply pipeline, an auxiliary steam supply pipeline and a shaft seal return steam pipeline respectively connected to the feedwater pump turbine; the steam-driven feedwater pump is respectively connected to the pre-pump and the high-pressure heater through a boiler feedwater pipeline, characterized in that the auxiliary steam supply pipeline is also connected to a standby steam source steam supply pipeline; The feedwater pump turbine is used to provide a power source for the steam-driven feedwater pump and the pre-pump; the steam-driven feedwater pump is used to drive the feedwater in the boiler feedwater pipe to transport the feedwater to the high-pressure heater; the gearbox is used to reduce the power provided by the feedwater pump turbine to the pre-pump; the pre-pump is used to increase the pressure at the inlet of the steam-driven feedwater pump to prevent cavitation of the steam-driven feedwater pump; the high-pressure heater is used to heat the feedwater to increase the feedwater temperature; the boiler feedwater pipeline is used to carry the feedwater; the turbine steam supply pipeline is used to provide a power steam source for the feedwater pump turbine; the auxiliary steam supply pipeline is used to provide a shaft seal steam source for the feedwater pump turbine; the shaft seal return steam pipeline is used to transport the exhaust steam of the feedwater pump turbine; the standby steam source supply pipeline is used to provide a standby steam source for the auxiliary steam supply pipeline.

2. A shaft seal steam supply system with a backup steam source according to claim 1, characterized in that: The steam-driven water supply pump is a steam-driven water supply pump with 1×100% BMCR.

3. A shaft seal steam supply system with a backup steam source according to claim 1, characterized in that: The steam-driven feedwater pump and the pre-pump are coaxially connected, and the steam-driven feedwater pump and the pre-pump share the feedwater pump turbine.

4. A shaft seal steam supply system with a backup steam source according to claim 1, characterized in that: The shaft seal return steam pipeline is also connected to a condenser, and the condenser is used to cool the exhaust steam.

5. The shaft seal steam supply system with a backup steam source according to claim 1, characterized in that: A small steam turbine is arranged inside the feedwater pump steam turbine; the small steam turbine is equipped with a shaft end steam seal; the shaft end steam seal is used to reduce the steam leakage at the high pressure end and the air leakage at the low pressure end.

6. A shaft seal steam supply system with a backup steam source according to claim 1, characterized in that: The front pump is also connected to the deaerator water tank; the deaerator water tank is used to store feed water and provide water to the boiler feed water pipeline.

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