阅读说明：本技术 一种汽轮机循环冷却水系统及其运行方法 (Circulating cooling water system of steam turbine and operation method thereof ) 是由 徐易 庞继勇 陈振超 刘春雷 李现周 于 2019-10-15 设计创作，主要内容包括：本发明公开了一种汽轮机循环冷却水系统及其运行方法,它解决了现有技术中循环水系统冷却的排汽过少、冷却水系统运行存在安全隐患的问题,在低真空方式下凝汽器不需要原有循环冷却水时采用临机供水或旁路循环泵,可以有效降低原有循环水系统压力,保护系统安全。其技术方案为：包括凝汽器、冷水塔和前池,凝汽器与前池通过第一循环管路相连,凝汽器与冷水塔通过第二循环管路相连；第一循环管路与前池之间并联一个或多个旁路循环泵,旁路循环泵的两侧分别安装手动阀I、电动阀V,且旁路循环泵与电动阀V之间安装逆止阀；第一循环管路连接有用于临机辅机循环冷却水流入的回水支路I；第二循环管路连接有用于辅机冷却水至临机前池的连接支路III。(The invention discloses a turbine circulating cooling water system and an operation method thereof, which solve the problems of low exhaust steam of cooling of a circulating water system and potential safety hazard in the operation of the cooling water system in the prior art, and adopt an on-line water supply or bypass circulating pump when a condenser does not need original circulating cooling water in a low vacuum mode, thereby effectively reducing the pressure of the original circulating water system and protecting the safety of the system. The technical scheme is as follows: the system comprises a condenser, a cooling tower and a forebay, wherein the condenser is connected with the forebay through a first circulating pipeline, and the condenser is connected with the cooling tower through a second circulating pipeline; one or more bypass circulating pumps are connected in parallel between the first circulating pipeline and the forebay, a manual valve I and an electric valve V are respectively arranged on two sides of the bypass circulating pump, and a check valve is arranged between the bypass circulating pump and the electric valve V; the first circulating pipeline is connected with a water return branch I for circulating cooling water of the temporary auxiliary machine to flow in; the second circulating pipeline is connected with a connecting branch III which is used for cooling water of the auxiliary machine to reach the machine-approaching forebay.)

1. A turbine circulating cooling water system comprises a condenser, a cooling tower and a forebay, and is characterized in that the condenser is connected with the forebay through a first circulating pipeline, and the condenser is connected with the cooling tower through a second circulating pipeline;

one or more bypass circulating pumps are connected in parallel between the first circulating pipeline and the front pool, a manual valve I and an electric valve V are respectively installed on two sides of each bypass circulating pump, and a check valve is installed between each bypass circulating pump and the electric valve V; the first circulating pipeline is connected with a water return branch I for circulating cooling water of the auxiliary machinery before the aircraft to flow in;

and the second circulating pipeline is connected with a connecting branch III which is used for cooling water of the auxiliary machine to reach a machine-approaching forebay.

2. The steam turbine recirculating cooling water system of claim 1, wherein the first circulating line comprises a connecting branch I, and the connecting branch I is connected with a circulating pump I and a circulating pump II which are connected in parallel with each other;

the bypass circulating pump is connected with the circulating pump I and the circulating pump II in parallel, the return water branch I is connected with the connecting branch I, and a manual valve II is arranged between the return water branch I and the connecting branch I.

3. The steam turbine recirculating cooling water system of claim 2, wherein the head of the bypass circulating pump is not less than circulating pump II and not more than circulating pump I.

4. The steam turbine circulating cooling water system as claimed in claim 2, wherein the second circulating pipeline comprises a connecting branch II connected between the condenser and the cooling tower, and one side of the connecting branch II is connected to the cooling tower through a connecting branch VI;

the other side of the connecting branch II is connected with a connecting branch III through a connecting branch IV, the connecting branch III is connected with the return water branch II between the connecting branch IV, and the connecting branch III is connected with the cooling water tower through a connecting branch V between the connecting branch IV.

5. The turbine recirculating cooling water system as claimed in claim 4, wherein a manual valve IV is arranged on the connecting branch IV, an electric valve V is arranged on the connecting branch I, an electric valve I is arranged between the circulating pump I and the forebay, and an electric valve II is arranged between the circulating pump I and the connecting branch I; an electric valve III is arranged between the circulating pump II and the forebay, and an electric valve IV is arranged between the circulating pump II and the connecting branch I;

an electric valve VI is arranged on the connecting branch II, and an electric valve VII is arranged on the connecting branch VI; and a manual valve V is arranged on the connecting branch V, and a manual valve III is arranged on the connecting branch III.

6. The steam turbine circulating cooling water system as claimed in claim 2, wherein the second circulating pipeline comprises a connecting branch II connected between the condenser and the cooling tower, and one side of the connecting branch II is connected to the cooling tower through a connecting branch VI;

the cooling tower is connected with a connecting branch V, the connecting branch V is connected with a return water branch II, and the connecting branch V is connected with the return water branch II and the connecting branch III.

7. The turbine recirculating cooling water system of claim 6, wherein an electric valve V is arranged on the connecting branch I, an electric valve I is arranged between the circulating pump I and the forebay, and an electric valve II is arranged between the circulating pump I and the connecting branch I; an electric valve III is arranged between the circulating pump II and the forebay, and an electric valve IV is arranged between the circulating pump II and the connecting branch I;

an electric valve VI is arranged on the connecting branch II, and an electric valve VII is arranged on the connecting branch VI; and a manual valve V is arranged on the connecting branch V, and a manual valve III is arranged on the connecting branch III.

8. The operating method of a turbine recirculating cooling water system as claimed in claim 5, wherein when the unit is operated in the low vacuum mode during the heating period, the electric valve V and the electric valve VI are closed, and the following operating modes can be selected:

1) the water return branch I and the connection branch III are used for ensuring that the unit runs, the electric valve I, the electric valve II, the electric valve III and the electric valve IV are closed, the bypass circulating pump is in hot standby, the manual valve I is opened, and the electric valve V is in a closed state in a live-line switching interlocking mode; the manual valve II and the manual valve III are opened, the manual valve IV and the manual valve V are closed, part of the auxiliary machine cooling water is consumed, and part of the auxiliary machine cooling water returns to the front pool of the next machine through the water return branch II and the connecting branch III;

2) when the water return branch I and the connecting branch III are not used, the bypass circulating pump normally operates during low vacuum operation, the circulating pump I and the circulating pump II are powered off, the electric valve I, the electric valve II, the electric valve III and the electric valve IV are closed, the manual valve I, the electric valve V and the manual valve V are opened, the manual valve IV is closed, part of cooling water of the auxiliary machine is consumed and used, and the other part of the cooling water returns to the water pool of the cooling water tower through the water return branch II and the connecting branch V.

9. The method of claim 7, wherein when the turbine cycle cooling water system is operated in the high back pressure mode during the heating period of the turbine, the electric valve V and the electric valve VI are opened, and the following operation modes can be selected:

1) the water return branch I and the connection branch III are used for ensuring that the unit runs, the circulating pump I and the circulating pump II are electrically heated for standby, the electric valve I and the electric valve III are opened, and the electric valve II and the electric valve IV are electrically switched and interlocked in a closed state; the bypass circulating pump is in hot standby, the manual valve I is opened, and the electric valve V is closed in an electrified way; the manual valve II and the manual valve III are opened, the manual valve V is closed, part of the auxiliary machine cooling water is consumed and used, and the other part of the auxiliary machine cooling water returns to the pre-machine pool through the water return branch II and the connecting branch III;

2) when the water return branch I and the connecting branch III are not used, the bypass circulating pump normally operates, the electric valve I, the electric valve III, the manual valve I, the electric valve V and the manual valve V are opened, the circulating pump I and the circulating pump II are in hot standby, and the electric valve II and the electric valve IV are closed in a linkage manner in an electrified manner; and part of the cooling water of the auxiliary machine is consumed and used, and the other part of the cooling water returns to the water pool of the cooling tower through the water return branch II and the connecting branch V.

10. The method for operating a steam turbine recirculating cooling water system as claimed in claim 8 or 9, wherein the water temperature is controlled by adjusting the amount of the upper flow of the water cooling tower using a power door VII; when bypass circulating pump trouble, start the circulating pump II that drops into hot reserve, when circulating pump II trouble, drop into circulating pump I, when circulating pump I trouble no available circulating water again, the unit is opened a floodgate and is shut down.

Technical Field

The invention relates to a circulating water cooling system of a thermal power plant, in particular to a circulating water cooling system of a steam turbine and an operation method thereof.

Background

At present, along with higher living standard and larger urban scale, the heating demand is also increased year by year, and more pure condensing units are used for heating transformation. In the heating period, even if the condensing unit is used, the steam discharge amount of the low-pressure cylinder is greatly reduced, and if the condensing unit is transformed into a high-back-pressure unit, the steam discharge amount which needs to be cooled by the original circulating cooling system is less. Although the circulating pump motor changes the wiring mode, the rotating speed is reduced, and the water quantity is reduced, more service power is still wasted.

The circulating water cooling system of the existing thermal power plant has large circulating water volume, generally, two circulating water pumps are arranged in each unit, one circulating water volume is slightly smaller, and the other circulating water volume is slightly larger. When the water circulating pump runs in winter, because the environmental temperature is low, the vacuum of the unit is high, the wiring mode of the water circulating pump motor is generally changed, the circulating water quantity is properly reduced, and therefore the station service power is saved.

Because the exhaust steam which needs to be cooled by the original circulating water system is too little or even not, when the original circulating water pump operates, the water temperature is lower, and the water is easy to freeze when the air temperature is lower, thereby threatening the safe operation of the cooling water system. The inventor finds that if the condenser does not need to be filled with original circulating water and only supplies auxiliary cooling water, the outlet pressure of the circulating pump and the pressure of a system pipeline are greatly increased, and the operation safety of an original circulating water system is seriously influenced.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a turbine circulating cooling water system and an operation method thereof.

The invention adopts the following technical scheme:

a turbine circulating cooling water system comprises a condenser, a cooling tower and a forebay, wherein the condenser is connected with the forebay through a first circulating pipeline, and the condenser is connected with the cooling tower through a second circulating pipeline;

one or more bypass circulating pumps are connected in parallel between the first circulating pipeline and the front pool, a manual valve I and an electric valve V are respectively installed on two sides of each bypass circulating pump, and a check valve is installed between each bypass circulating pump and the electric valve V; the first circulating pipeline is connected with a water return branch I for circulating cooling water of the auxiliary machinery before the aircraft to flow in;

and the second circulating pipeline is connected with a connecting branch III which is used for cooling water of the auxiliary machine to reach a machine-approaching forebay.

Further, the first circulation pipeline comprises a connecting branch I, and the connecting branch I is connected with a circulation pump I and a circulation pump II which are connected in parallel;

the bypass circulating pump is connected with the circulating pump I and the circulating pump II in parallel, the return water branch I is connected with the connecting branch I, and a manual valve II is arranged between the return water branch I and the connecting branch I.

Furthermore, the lift of the bypass circulating pump is not less than that of the circulating pump II and not more than that of the circulating pump I.

Further, the second circulation pipeline comprises a connecting branch II connected between the condenser and the cooling tower, and one side of the connecting branch II is connected to the cooling tower through a connecting branch VI;

the other side of the connecting branch II is connected with a connecting branch III through a connecting branch IV, the connecting branch III is connected with the return water branch II between the connecting branch IV, and the connecting branch III is connected with the cooling water tower through a connecting branch V between the connecting branch IV.

Furthermore, a manual valve IV is arranged on the connecting branch IV, an electric valve V is arranged on the connecting branch I, an electric valve I is arranged between the circulating pump I and the front pool, and an electric valve II is arranged between the circulating pump I and the connecting branch I; an electric valve III is arranged between the circulating pump II and the forebay, and an electric valve IV is arranged between the circulating pump II and the connecting branch I;

an electric valve VI is arranged on the connecting branch II, and an electric valve VII is arranged on the connecting branch VI; and a manual valve V is arranged on the connecting branch V, and a manual valve III is arranged on the connecting branch III.

Further, the second circulation pipeline comprises a connecting branch II connected between the condenser and the cooling tower, and one side of the connecting branch II is connected to the cooling tower through a connecting branch VI;

the cooling tower is connected with a connecting branch V, the connecting branch V is connected with a return water branch II, and the connecting branch V is connected with the return water branch II and the connecting branch III.

Further, an electric valve V is arranged on the connecting branch I, an electric valve I is arranged between the circulating pump I and the front pool, and an electric valve II is arranged between the circulating pump I and the connecting branch I; an electric valve III is arranged between the circulating pump II and the forebay, and an electric valve IV is arranged between the circulating pump II and the connecting branch I;

an electric valve VI is arranged on the connecting branch II, and an electric valve VII is arranged on the connecting branch VI; and a manual valve V is arranged on the connecting branch V, and a manual valve III is arranged on the connecting branch III.

An operation method of a turbine circulating cooling water system is characterized in that when a unit operates in a low-vacuum mode in a heating period, an electric valve V and an electric valve VI are closed, and the following operation modes can be selected:

1) the water return branch I and the connection branch III are used for ensuring that the unit runs, the electric valve I, the electric valve II, the electric valve III and the electric valve IV are closed, the bypass circulating pump is in hot standby, the manual valve I is opened, and the electric valve V is in a closed state in a live-line switching interlocking mode; the manual valve II and the manual valve III are opened, the manual valve IV and the manual valve V are closed, part of the auxiliary machine cooling water is consumed, and part of the auxiliary machine cooling water returns to the front pool of the next machine through the water return branch II and the connecting branch III;

2) when the water return branch I and the connecting branch III are not used, the bypass circulating pump normally operates during low vacuum operation, the circulating pump I and the circulating pump II are powered off, the electric valve I, the electric valve II, the electric valve III and the electric valve IV are closed, the manual valve I, the electric valve V and the manual valve V are opened, the manual valve IV is closed, part of cooling water of the auxiliary machine is consumed and used, and the other part of the cooling water returns to the water pool of the cooling water tower through the water return branch II and the connecting branch V.

An operation method of a turbine circulating cooling water system is characterized in that when a unit operates in a high-backpressure mode in a heating period, an electric valve V and an electric valve VI are opened, and the following operation modes can be selected:

1) the water return branch I and the connection branch III are used for ensuring that the unit runs, the circulating pump I and the circulating pump II are electrically heated for standby, the electric valve I and the electric valve III are opened, and the electric valve II and the electric valve IV are electrically switched and interlocked in a closed state; the bypass circulating pump is in hot standby, the manual valve I is opened, and the electric valve V is closed in an electrified way; the manual valve II and the manual valve III are opened, the manual valve V is closed, part of the auxiliary machine cooling water is consumed and used, and the other part of the auxiliary machine cooling water returns to the pre-machine pool through the water return branch II and the connecting branch III;

2) when the water return branch I and the connecting branch III are not used, the bypass circulating pump normally operates, the electric valve I, the electric valve III, the manual valve I, the electric valve V and the manual valve V are opened, the circulating pump I and the circulating pump II are in hot standby, and the electric valve II and the electric valve IV are closed in a linkage manner in an electrified manner; and part of the cooling water of the auxiliary machine is consumed and used, and the other part of the cooling water returns to the water pool of the cooling tower through the water return branch II and the connecting branch V.

Further, the water temperature is controlled by adjusting the flow quantity of the upper part of the cooling tower by using an electric door VII; when bypass circulating pump trouble, start the circulating pump II that drops into hot reserve, when circulating pump II trouble, drop into circulating pump I, when circulating pump I trouble no available circulating water again, the unit is opened a floodgate and is shut down.

Compared with the prior art, the invention has the beneficial effects that:

(1) in a low-vacuum mode, when the condenser does not need original circulating cooling water, the invention adopts an on-line water supply or bypass circulating pump, so that the pressure of the original circulating water system can be effectively reduced, and the safety of the system is protected; and the power can be saved by adopting the on-machine water supply or the bypass circulating pump;

(2) when the bypass circulating pump is used for standby, the safety coefficient of the machine is increased, and the non-stop probability of the machine set is reduced; the circulating water system can be prevented from being forced to stop due to water loss caused by the fact that a water tower is frozen and a filter screen is blocked when the original circulating pump is operated; can reduce the evaporation consumption of circulating water and save water resources.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the application and, together with the description, serve to explain the application and are not intended to limit the application.

FIG. 1 is a schematic structural diagram according to a first embodiment of the present invention;

FIG. 2 is a schematic structural diagram according to a second embodiment of the present invention;

the system comprises a water supply branch I, a water supply branch 23, a water supply branch I, a water supply branch 24, a water supply branch II, a water return branch 25, a water return branch II, a water return branch 26, a water supply branch III, a water supply branch 27, a water supply branch IV, a water supply branch VI, a water supply branch IV, a water supply branch VI, a water supply branch IV, a water supply branch VI, a water supply branch III, a water supply branch IV, a water supply branch 28, a water supply branch V, a water supply branch 29.

Detailed Description

It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;

for convenience of description, the words "up", "down", "left" and "right" in this application, if any, merely indicate correspondence with the directions of up, down, left and right of the drawings themselves, and do not limit the structure, but merely facilitate the description of the invention and simplify the description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the application.

The terms "mounted", "connected", "fixed", and the like in the present application should be understood broadly, and for example, the terms "mounted", "connected", and "fixed" may be fixedly connected, detachably connected, or integrated; the two components can be connected mechanically or electrically, directly or indirectly through an intermediate medium, or connected internally or in an interaction relationship, and the terms used in the present invention should be understood as having specific meanings to those skilled in the art.

As introduced in the background art, the defects of too little exhaust steam of cooling of a circulating water system and potential safety hazard of running of the cooling water system exist in the prior art, and the invention provides a turbine circulating cooling water system and a running method thereof in order to solve the technical problems.