CN203835469U - Turbine low-pressure shaft seal steam supply system - Google Patents

Abstract

The utility model relates to steam power engineering, in particular to a steam turbine low-pressure shaft seal steam supply system, characterized in that the system includes a shaft seal steam supply header and at least one low-pressure shaft seal steam supply cooling device, wherein: the shaft The seal supply steam header is connected with the steam leakage pipeline of the rear steam seal of the high pressure cylinder and the steam leakage pipeline of the rear steam seal of the medium pressure cylinder; The steam exhaust chamber of the shaft seal is connected through the steam supply valve of the first shaft seal header; the at least one low-pressure shaft seal steam supply cooling device is used to cool the gas in the exhaust steam chamber. The utility model mainly uses the low-pressure shaft seal steam supply cooling device arranged in the exhaust chamber of the low-pressure cylinder so that the system can reduce the leakage steam temperature of the shaft seal to the required level by the exhaust steam of the steam turbine, ensuring the stability of the low-pressure shaft seal steam supply temperature , Improve the safety and economy of unit operation.

Description

Steam Turbine Low Pressure Shaft Seal Steam Supply System

technical field

The utility model relates to steam power engineering, in particular to a steam turbine low-pressure shaft seal steam supply system.

Background technique

A steam turbine is a rotating power machine powered by steam and converts the thermal energy of steam into mechanical work. It is the most widely used prime mover in modern thermal power plants. It has the advantages of large single machine power, high efficiency, and long life. It is mainly used as a prime mover for power generation, and can also directly drive various pumps, fans, compressors, and ship propellers. It can also use the exhaust steam of the steam turbine or intermediate pumping Steam meets the heating needs of production and life.

Usually, the low-pressure end of the steam turbine is equipped with a shaft-end steam seal, which can reduce steam leakage or air leakage, but the steam leakage phenomenon cannot be completely eliminated. In order to prevent and reduce this kind of steam leakage, ensure the normal start-stop and operation of the unit, recover the leaked steam and utilize the energy of the leaked steam, and reduce the loss of working medium and heat of the system, at present, large steam turbines mostly use high and medium pressure cylinder shaft seals. The method of sealing the low-pressure end after the leaked steam is cooled by spraying water.

However, in addition to a certain impact on the economical efficiency of the unit, if the water spray desuperheating is not properly controlled, it will cause a large change in the temperature of the low-pressure steam supply, which will cause the friction and vibration of the low-pressure rotor of the steam turbine, which will threaten the safe operation of the unit. The unit stops running. At present, the shaft seal clearance of most thermal power units is too large, and the amount of steam leakage is too large. When the amount of cooling water spray is insufficient, the high-temperature shaft seal leakage steam will enter the oil system, causing water to be carried in the turbine oil, and the turbine oil will be emulsified and deteriorated; When the amount of warm sprayed water is too large, the shaft seal will be supplied with water, which is not conducive to the safe operation of the unit.

Utility model content

(1) Solved technical problems

Aiming at the deficiencies of the prior art, the utility model provides a steam turbine low-pressure shaft seal steam supply system, which mainly uses a low-pressure shaft seal steam supply cooling device arranged in the exhaust chamber of the low-pressure cylinder so that the system can leak the shaft seal due to the exhaust steam of the steam turbine. The steam temperature is reduced to the required level, which ensures the stability of the steam supply temperature of the low-pressure shaft seal, and improves the safety and economy of the unit operation.

(2) Technical solution

In order to achieve the above object, the utility model is realized through the following technical solutions:

A steam turbine low-pressure shaft seal steam supply system, characterized in that the system includes a shaft seal steam supply header and at least one low-pressure shaft seal steam supply cooling device, wherein:

The shaft seal is connected to the steam header and the steam leakage pipeline of the rear steam seal of the high-pressure cylinder and the steam leakage pipeline of the rear steam seal of the medium-pressure cylinder;

The steam outlet of the shaft seal steam supply header is connected with the exhaust chamber of the low pressure cylinder front shaft seal and the low pressure cylinder rear shaft seal through the first shaft seal header steam supply valve;

The at least one low-pressure shaft seal supply steam cooling device is used for cooling the gas in the steam exhaust chamber.

Preferably, the shaft seal steam supply header is in communication with a main steam supply shaft seal pipeline, and a main steam supply shaft seal valve is arranged on the main steam supply shaft seal pipeline.

Preferably, the shaft seal steam supply header is in communication with the reheat cold end shaft seal pipeline, and a reheat cold end shaft seal valve is arranged on the reheat cold end shaft seal pipeline.

Preferably, the shaft seal steam supply header communicates with an auxiliary steam supply shaft seal pipeline, and an auxiliary steam supply shaft seal valve is arranged on the auxiliary steam supply shaft seal pipeline.

Preferably, the system further includes a low-pressure heater located at the outlet of the condensate pump, and the low-pressure heater communicates with the shaft seal steam header.

Preferably, a shaft seal steam supply overflow valve is provided between the shaft seal steam supply header and the low-pressure heater.

Preferably, the system further includes a spray desuperheater; the steam outlet of the shaft seal steam supply header is also connected to the spray water desuperheater through a second shaft seal header steam supply valve, and its outlet The steam is supplied to the front shaft seal of the low pressure cylinder and the rear shaft seal of the low pressure cylinder.

Preferably, the spray desuperheater communicates with a condensate desuperheating water pipeline, and a condensate water spray valve is arranged on the condensate desuperheating water pipeline.

(3) Beneficial effects

The utility model has at least the following beneficial effects:

The steam turbine low-pressure shaft seal steam supply system proposed by the utility model includes a low-pressure shaft seal steam supply cooling device. For high and medium pressure combined cylinder units, the leakage steam from the rear seal of the high pressure cylinder of the steam turbine and the rear seal of the medium pressure cylinder is mixed and then enters the shaft seal to supply the steam header. During normal operation, the shaft seal steam supply can be lowered to the required temperature from the header through the shaft seal steam supply cooling device, and then supplied to the front shaft seal of the low-pressure cylinder and the rear shaft seal of the low-pressure cylinder, so as to achieve the purpose of sealing.

Compared with the existing technology, the use of the low-pressure shaft seal steam supply cooling device can reduce the leakage steam temperature of the shaft seal to the required level due to the exhaust steam of the steam turbine, ensuring the stability of the low-pressure shaft seal steam supply temperature; moreover, due to the normal operation There is no need to spray water to reduce the temperature, so the utility model improves the economical efficiency of unit operation.

Generally speaking, the utility model has a simple structure, is economical and practical, and can be transformed from the existing low-pressure shaft seal steam supply system, and can also be used in the design of new steam turbine units, which can effectively ensure the safety of the low-pressure shaft seal steam supply of the steam turbine unit , Economical and reliable operation.

Of course, any product implementing the present utility model does not necessarily need to achieve all the above-mentioned advantages at the same time.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, a brief introduction will be given below to the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings show some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without creative work.

Fig. 1 is a structural diagram of a steam turbine low-pressure shaft seal steam supply system in an embodiment of the present invention.

In the figure, 1—high pressure cylinder, 2—medium pressure cylinder, 3—low pressure cylinder, 4—rear shaft seal of high pressure cylinder, 5—rear shaft seal of medium pressure cylinder, 6—front shaft seal of low pressure cylinder, 7——low pressure cylinder rear shaft seal, 8—shaft seal steam supply header, 9—low pressure front shaft seal steam supply cooling device, 10—low pressure rear shaft seal steam supply cooling device, 11—main steam supply shaft Sealing pipeline, 12—reheating and cold end supply shaft sealing pipeline, 13—auxiliary steam supplying shaft sealing pipeline, 14—main steam supplying shaft sealing valve, 15—reheating and cold end supplying shaft sealing valve, 16—auxiliary steam supply shaft seal valve, 17—steam supply valve for the first shaft seal header, 18—steam supply valve for the second shaft seal header, 19—water spray desuperheater, 20—condensed water Spray valve, 21 - condensate desuperheating water pipeline, 22 - shaft seal steam supply overflow valve, 23 - low pressure heater at the outlet of condensate pump.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the utility model more clear, the technical solutions in the embodiments of the utility model will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the utility model. Obviously, the described The embodiments are some embodiments of the present utility model, but not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present utility model.

The embodiment of the utility model proposes a low-pressure shaft seal steam supply system for a steam turbine. Referring to FIG. 1, the system includes a shaft seal steam supply header 8 and at least one low-pressure shaft seal steam supply cooling device (9, 10, only Take two as an example), where:

The shaft seal steam header 8 communicates with the steam leakage pipeline of the high pressure cylinder rear steam seal 4 and the steam leakage pipeline of the medium pressure cylinder rear steam seal 5; the steam outlet of the shaft seal steam header 8 is connected with the low pressure cylinder The exhaust chambers of the front shaft seal 6 and the rear shaft seal 7 of the low-pressure cylinder are connected through the first shaft seal header steam supply valve 17; the at least one low-pressure shaft seal steam supply cooling device 9 is used to cool the exhaust chamber. gas.

The low-pressure shaft seal steam supply system including the above-mentioned structure can make the leakage steam from the rear gland seal of the high-pressure cylinder of the steam turbine and the rear gland seal of the medium-pressure cylinder mix and then enter the shaft seal steam supply header, and the shaft seal steam supply can be supplied from during normal operation. After the header is cooled to the required temperature by the shaft seal steam supply cooling device, it is supplied to the front shaft seal of the low-pressure cylinder and the rear shaft seal of the low-pressure cylinder, so as to achieve the purpose of sealing.

Moreover, compared with the prior art, the use of the low-pressure shaft seal steam supply cooling device can reduce the leakage steam temperature of the shaft seal to the required level due to the exhaust steam of the steam turbine, ensuring the stability of the steam supply temperature of the low-pressure shaft seal; moreover, due to normal operation It is not necessary to spray water to reduce the temperature, so the utility model improves the economy of unit operation.

Preferably, the shaft seal steam supply header 8 communicates with a main steam supply shaft seal pipeline 11 , and a main steam supply shaft seal valve 14 is arranged on the main steam supply shaft seal pipeline 11 .

Preferably, the shaft seal steam supply header 8 communicates with the reheat cold end shaft seal pipeline 12, and a reheat cold end shaft seal valve 15 is arranged on the reheat cold end shaft seal pipeline 12 .

Preferably, the shaft seal steam supply header 8 communicates with an auxiliary steam supply shaft seal pipeline 13 , and an auxiliary steam supply shaft seal valve 16 is arranged on the auxiliary steam supply shaft seal pipeline 13 .

The above three shaft seal pipelines can supply steam to the shaft seal with main steam, reheat steam cold end and auxiliary steam respectively during the start-up or low load period of the steam turbine unit. When the steam supply temperature cannot meet the requirements, the main steam, Reheat steam, auxiliary steam and other steam sources increase the steam supply temperature, further ensuring the shaft seal steam supply temperature and reliability.

Preferably, the system further includes a low-pressure heater 23 located at the outlet of the condensate pump, and the low-pressure heater 23 communicates with the shaft seal supply header 8 . More preferably, a shaft seal steam supply overflow valve 22 is provided between the shaft seal steam supply header 8 and the low pressure heater 23 . The above-mentioned structure can make the excess steam supplied by the shaft seal overflow into the low-pressure heater 23 through which the condensed water flows when the steam supplied by the shaft seal is too large, so that part of the heat can be recovered, energy is saved, and energy utilization efficiency is improved.

Preferably, the system also includes a water injection desuperheater 19; the steam outlet of the shaft seal steam supply header 8 is also connected to the water spray desuperheater 19 through the second shaft seal header steam supply valve 18. Connected, its outlet steam is supplied to the front shaft seal 6 of the low-pressure cylinder and the rear shaft seal 7 of the low-pressure cylinder. More preferably, the spray desuperheater 19 communicates with a condensate desuperheating water pipeline 21 , and a condensate water spray valve 20 is arranged on the condensate desuperheating water pipeline 21 . This structure is suitable for the situation when the steam supply temperature cannot meet the requirements under specific working conditions, that is to say, when the steam supply temperature is too high, the overspray water cooling system can be turned on to adjust the temperature to ensure the steam supply of the shaft seal. temperature reliability.

The steam turbine low-pressure shaft seal steam supply system under all the above-mentioned optimal conditions corresponds to the labels in Figure 1, including high-pressure cylinder 1, medium-pressure cylinder 2, low-pressure cylinder 3, high-pressure cylinder rear shaft seal 4, and medium-pressure cylinder rear shaft seal 5. Low pressure cylinder front shaft seal 6, low pressure cylinder rear shaft seal 7, shaft seal steam supply header 8, low pressure front shaft seal steam supply cooling device 9, low pressure rear shaft seal steam supply cooling device 10, water spray desuperheater 19 and the low-pressure heater 23 at the outlet of the condensate pump. The specific working principle of the system is as follows:

During unit start-up or low load, when the leaked steam from the rear shaft seal 4 of the high-pressure cylinder and the rear shaft seal 5 of the medium-pressure cylinder cannot meet the steam supply temperature requirements of the low-pressure shaft seal, the main steam supply shaft seal valve 14 can be opened in good time to reheat Cold end supply shaft seal valve 15, auxiliary steam supply shaft seal valve 16, first shaft seal header steam supply valve 17, shaft seal steam supply overflow valve 22, the main steam supply shaft seal pipeline 11 or the reheated cold end The shaft seal supply pipeline 12 or the auxiliary steam supply shaft seal pipeline 13 communicates with the shaft seal steam supply header 8. After the shaft seal steam supply passes through the second shaft seal header steam supply valve 18 and the water spray desuperheater 19, the other The outlet steam is respectively supplied to the front shaft seal 6 of the low-pressure cylinder and the rear shaft seal 7 of the low-pressure cylinder. The excess steam supplied by the shaft seal can enter the low-pressure heater 23 at the outlet of the condensate pump through the overflow valve 22 to recover part of the heat.

During the normal operation of the unit, when the leakage steam from the rear shaft seal 4 of the high pressure cylinder and the rear shaft seal 5 of the medium pressure cylinder can meet the steam supply temperature requirements of the low pressure shaft seal, the main steam supply shaft seal valve 14 can be closed, and the reheated cold end shaft seal can be closed. Valve 15, auxiliary steam supply shaft seal valve 16, the steam leakage pipe of the rear shaft seal 4 of the high-pressure cylinder and the steam leakage pipe of the rear shaft seal 5 of the medium-pressure cylinder communicate with the shaft seal steam supply header 8, and the shaft seal steam supply header The steam outlet of 8 is connected with the low-pressure front shaft seal steam supply cooling device 9 and the low-pressure rear shaft seal steam supply cooling device 10 through the first shaft seal header steam supply valve 17, and its outlet steam is respectively supplied to the low-pressure cylinder front shaft seal 6. The shaft seal 7 behind the low-pressure cylinder, the excess steam supplied by the shaft seal can enter the low-pressure heater 23 at the outlet of the condensate pump through the overflow valve 22 to recover part of the heat; when the temperature does not meet the requirements, the second shaft seal header can be opened in due course The steam supply valve 18 and the condensed water spray valve 20 are put into the water spray desuperheater 19.

Compared with the prior art, the beneficial effects produced by the system include:

1) The low-pressure shaft seal steam supply cooling device is used to ensure the stability of the steam supply temperature;

2) No need to spray water to reduce temperature during normal operation, which improves the economy of unit operation;

3) The shaft seal overflow steam is connected to the first low-pressure heater through which the condensed water flows, and part of the heat is recovered to achieve the purpose of energy saving;

Generally speaking, the utility model has a simple structure, is economical and practical, and can be transformed from the existing low-pressure shaft seal steam supply system, and can also be used in the design of new steam turbine units, which can effectively ensure the safety of the low-pressure shaft seal steam supply of the steam turbine unit , Economical and reliable operation.

The utility model is a low-pressure shaft seal steam supply system for a steam turbine, which can be used for the transformation of the existing low-pressure shaft seal steam supply system, and can also be used for newly-built steam turbine units. Safe, economical and reliable operating temperature of steam.

It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is a relationship between these entities or operations. There is no such actual relationship or order between them. Moreover, the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that an article or device comprising a set of elements includes not only those elements but also other elements not expressly listed, Or also include elements inherent in the article or device. Without further limitations, an element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the article or device comprising said element.

The above embodiments are only used to illustrate the technical solutions of the present utility model, and are not intended to limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still be applied to the foregoing embodiments The technical solutions described in the examples are modified, or some of the technical features are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (8)

1. A steam turbine low-pressure shaft seal steam supply system, characterized in that the system includes a shaft seal steam supply header and at least one low-pressure shaft seal steam supply cooling device, wherein: The shaft seal is connected to the steam header and the steam leakage pipeline of the rear steam seal of the high-pressure cylinder and the steam leakage pipeline of the rear steam seal of the medium-pressure cylinder; The steam outlet of the shaft seal steam supply header is connected with the exhaust chamber of the low pressure cylinder front shaft seal and the low pressure cylinder rear shaft seal through the first shaft seal header steam supply valve; The at least one low-pressure shaft seal supply steam cooling device is used for cooling the gas in the steam exhaust chamber. 2. The system according to claim 1, wherein the shaft seal steam supply header is in communication with the main steam supply shaft seal pipeline, and a main steam supply shaft seal is arranged on the main steam supply shaft seal pipeline valve. 3. The system according to claim 1, wherein the shaft seal steam supply header is in communication with the reheat cold end shaft seal supply pipeline, and a reheating cold end shaft seal pipeline is provided on the reheat cold end shaft seal pipeline. The hot and cold ends are for shaft seal valves. 4. The system according to claim 1, wherein the shaft seal steam supply header is in communication with an auxiliary steam supply shaft seal pipeline, and an auxiliary steam supply shaft seal is arranged on the auxiliary steam supply shaft seal pipeline valve. 5 . The system according to claim 1 , further comprising a low-pressure heater located at the outlet of the condensate pump, and the low-pressure heater communicates with the shaft seal steam header. 6 . 6 . The system according to claim 5 , wherein a shaft seal steam supply overflow valve is arranged between the shaft seal steam supply header and the low-pressure heater. 7. The system according to any one of claims 1 to 6, characterized in that, the system also includes a water spray desuperheater; the steam outlet of the shaft seal steam supply header is also connected to the water spray The desuperheater is connected through the steam supply valve of the second shaft seal header, and its outlet steam is supplied to the front shaft seal of the low-pressure cylinder and the rear shaft seal of the low-pressure cylinder. 8 . The system according to claim 7 , wherein the spray desuperheater is in communication with a condensate desuperheating water pipeline, and a condensate water spray valve is arranged on the condensate desuperheating water pipeline.