CN216113996U

CN216113996U - Feedwater recirculation system

Info

Publication number: CN216113996U
Application number: CN202122357423.7U
Authority: CN
Inventors: 吴志祥; 宁志; 杜继臻; 姜保米; 曹善贵; 周权; 崔志坚; 陈永龙
Original assignee: Guoneng Shenwan Anqing Power Generation Co ltd
Current assignee: Guoneng Shenwan Anqing Power Generation Co ltd
Priority date: 2021-09-27
Filing date: 2021-09-27
Publication date: 2022-03-22
Anticipated expiration: 2031-09-27

Abstract

The application discloses feedwater recirculation system includes: minimum flow valve, first isolation door, second isolation door, water-feeding pump, oxygen-eliminating device and ball valve, wherein, the entry of first isolation door with the first export of water-feeding pump links to each other, the entry of ball valve with the export of first isolation door links to each other, the export of ball valve with the entry of minimum flow valve links to each other, the export of minimum flow valve with the entry of second isolation door links to each other, the export of second isolation door with the entry of oxygen-eliminating device links to each other.

Description

Feedwater recirculation system

Technical Field

The application relates to the technical field of thermal power generating units, in particular to a water supply recirculation system.

Background

In a power plant, in order to meet the requirement of minimum flow of a feed pump in a unit, a feed water recirculation system is usually arranged at the outlet of the feed pump, when the feed water flow is smaller than the minimum flow, a minimum flow valve is automatically opened, and a part of feed water flows back to a deaerator, so that the working flow of the feed pump is not lower than the minimum flow, and the normal operation of the feed pump is protected.

In the actual operation process, the manual isolation doors before and behind the minimum flow valve are in a normally open state, so that the difference between the pressure borne by the valve of the minimum flow valve and the pressure borne by the valve of the minimum flow valve is large, the valve inner assembly of the minimum flow regulating valve is in a seriously-scoured working condition for a long time, the valve inner assembly is seriously damaged, the sealing surface is seriously eroded along with the increase of the service time until the sealing surface fails, and the valve is seriously leaked, so that the safety operation of a unit is seriously influenced.

SUMMERY OF THE UTILITY MODEL

The application discloses feedwater recirculation system to solve the too big problem that leads to the unit operation unsafe before present minimum flow valve's the valve, behind the valve pressure differential.

In order to solve the above problems, the following technical solutions are adopted in the present application:

the embodiment of the application discloses feedwater recirculation system includes: minimum flow valve, first isolation door, second isolation door, water-feeding pump, oxygen-eliminating device and ball valve, wherein, the entry of first isolation door with the first export of water-feeding pump links to each other, the entry of ball valve with the export of first isolation door links to each other, the export of ball valve with the entry of minimum flow valve links to each other, the export of minimum flow valve with the entry of second isolation door links to each other, the export of second isolation door with the entry of oxygen-eliminating device links to each other.

The technical scheme adopted by the application can achieve the following beneficial effects:

the embodiment of the application discloses feedwater recirculation system links to each other through the export with the entry and the first isolation door of ball valve, and the export of ball valve links to each other with minimum flow valve's entry for under feedwater recirculation system satisfies the condition of minimum flow, open the ball valve after, open minimum flow valve, minimum flow valve normally works. And when the minimum flow rate is not met by the feedwater recirculation system, the minimum flow valve stops working, the ball valve is closed after the minimum flow valve is closed, and the flushing of the feedwater on the minimum flow valve is cut off through the ball valve, so that the pressure is not borne before the valve of the minimum flow valve, and the pressure difference between the front part and the rear part of the valve of the minimum flow valve is small. Therefore, the ball valve can avoid flushing and damage to the minimum flow valve when the feed water flow is in a low-opening area. Therefore, the problem that the minimum flow valve is seriously washed to influence the safety of the unit due to the fact that the first isolation door and the second isolation door are in a normally open state can be avoided, namely, the water supply recirculation system disclosed by the embodiment of the application can solve the problem that the unit is unsafe to operate due to the fact that the pressure difference between the front valve and the rear valve of the current minimum flow valve is too large.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic structural diagram of a feedwater recirculation system disclosed in an embodiment of the present application.

100-minimum flow valve, 200-first isolation door, 300-second isolation door, 400-feed water pump, 500-deaerator, 600-ball valve, 700-flow detection device, 800-pre-pump, 900-feed water pump inlet door, 1000-pre-pump inlet door.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be described in detail and completely with reference to the following specific embodiments of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

Technical solutions disclosed in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a feedwater recirculation system, and as shown in fig. 1, a feedwater recirculation system disclosed in an embodiment of the present application includes: a minimum flow valve 100, a first isolation door 200, a second isolation door 300, a feedwater pump 400, a deaerator 500, and a ball valve 600, wherein,

the entry of first isolation door 200 links to each other with the first export of feedwater pump 400, and the export of first isolation door 200 links to each other with the entry of ball valve 600, and the export of ball valve 600 links to each other with minimum flow valve 100's entry, and minimum flow valve 100's export links to each other with the entry of second isolation door 300, and the export of second isolation door 300 links to each other with the entry of oxygen-eliminating device 500.

The minimum flow valve 100 is a device for meeting the minimum flow in the feedwater recirculation system, wherein, when the effective cavitation allowance of the feedwater pump 400 is equal to the required cavitation allowance, the corresponding flow is the minimum flow, when the feedwater flow is smaller than the minimum flow, the minimum flow valve 100 is automatically opened, and a part of water flows back to the deaerator 500, so as to ensure that the working flow of the feedwater pump 400 is not lower than the minimum flow, and in order to ensure the normal operation of the feedwater recirculation system, it is required to meet the requirement that the effective cavitation allowance of the feedwater pump 400 is not lower than the required cavitation allowance under any working condition. It should be noted that different units correspond to different minimum flows.

And a feed water pump 400 for supplying the feed water treated by the deaerator 500 to the boiler after increasing the pressure, so as to satisfy the requirement of the boiler water. The deaerator 500 is a deaerator for removing dissolved oxygen and other gases in the feed water of the system to prevent corrosion of the feed water pump 400, the boiler, and the like.

The ball valve 600 is provided on a pipe between the outlet of the first isolation door 200 and the inlet of the minimum flow valve 100, and the pressure before the minimum flow valve 100 can be adjusted by the ball valve 600. When the effective cavitation margin is equal to the required cavitation margin, the feed water flow rate of the feed water pump 400 is the minimum flow rate, and at this time, the minimum flow valve 100 is in the operating state, and the ball valve 600 is opened before the minimum flow valve 100 is opened, so that the feed water can pass through the ball valve 600 and be treated by the minimum flow valve 100. In the case where the effective cavitation margin is larger than the necessary cavitation margin, the feedwater recirculation system operates normally, the ball valve 600 is in a closed state, the minimum flow valve 100 is in a closed state, and after the minimum flow valve 100 is closed, the ball valve 600 is closed, so that flushing of the minimum flow valve 100 by the feedwater can be blocked, in which case, the inlet of the minimum flow valve 100 is not subjected to pressure, and the front-rear pressure difference of the minimum flow valve 100 is minimum.

The ball valve 600 may be of various types, such as a hydraulic ball valve, a pneumatic ball valve, etc., and the embodiment of the present application is not particularly limited thereto.

In an implementation manner, taking a 1000MW unit as an example, under the condition that the minimum flow valve 100 does not work, the first isolation door 200 and the second isolation door 300 are normally open, at this time, the pressure borne by the front valve of the minimum flow valve 100 is 14 to 34MPa, and the pressure borne by the rear valve of the minimum flow valve 100 is 0.4 to 1MPa, so that the pressure difference between the front and the rear of the minimum flow valve 100 is the largest, the minimum flow valve 100 is seriously washed, and the components in the valve are seriously damaged. Through installing ball valve 600 additional for minimum flow valve 100 is closing the back, closes ball valve 600, and then ball valve 600 can cut off feedwater and to minimum flow valve 100's washing, thereby can prolong minimum flow valve 100's life.

In order to ensure the accuracy of opening the ball valve 600, in one possible implementation, the feedwater recirculation system may further include: and a flow rate detection device 700, wherein the flow rate detection device 700 is arranged at the position of the inlet of the feed water pump 400, detects the flow rate value of the inlet of the feed water pump 400, and transmits the flow rate value to the controller of the feed water recirculation system. The flow rate value of the feedwater flowing into the feedwater pump 400 can be detected by the flow rate detection device 700 and transmitted to the controller of the feedwater recirculation system, so that the controller can control the components in the feedwater recirculation system to perform corresponding operations according to the flow rate value detected by the flow rate detection device 700. In this way, the opening or closing of the ball valve 600 can be accurately controlled. The flow rate detecting device 700 may be a flow meter, a welding type flow rate detecting device, or the like, and the embodiment of the present application is not particularly limited thereto.

Specifically, the controller may control the opening or closing of the ball valve 600. Under the condition that the flow detection device 700 detects that the inlet flow of the water feed pump 400 is reduced to a first preset value, the controller can control the ball valve 600 to be opened; in the case where the flow rate detection device 700 detects that the inlet flow rate of the feed water pump 400 exceeds the second preset value, the controller controls the ball valve 600 to close. The first preset value and the second preset value are preset values corresponding to the units, and different units correspond to different first preset values and different second preset values. In this way, the opening or closing of the ball valve 600 can be automatically controlled, so that the automatic operation of the feedwater recirculation system can be realized.

In one implementation, the ball valve 600 may be a pneumatic ball valve. The pneumatic ball valve can meet the requirement of being opened quickly and closed tightly under the ultrahigh pressure of the feed water, so that the feed water recirculation system can be closed tightly, and the sealing performance of the feed water recirculation system is improved.

The pneumatic ball valve may include: and a pneumatic actuator which can perform an opening operation of the pneumatic ball valve or a closing operation of the pneumatic ball valve. Specifically, when the flow rate detection device 700 detects that the inlet flow rate of the feed water pump 400 is reduced to a preset value, the controller of the feed water recirculation system sends an opening instruction, the opening instruction triggers the pneumatic actuator, and the pneumatic actuator performs the opening operation of the pneumatic ball valve after receiving the opening instruction of the controller, wherein at this time, the opening operation of the pneumatic ball valve can be completed within 5 s. Through the mode, the pneumatic ball valve can carry out logic association control through the pneumatic actuator, and the opening operation of the pneumatic ball valve or the closing operation of the pneumatic ball valve are controlled, so that the matching linkage with the minimum flow valve 100 can be quickly realized, and the action of quickly opening or closing the pneumatic ball valve of the water supply recirculation system is realized.

In addition, the pneumatic ball valve may further include: and (4) a manual device. By means of a manual device, the operator can manually open or close the pneumatic ball valve when the water supply of the circulating system is in an emergency. There are many types of emergency situations, such as a failure to respond to a command from the controller, a failure of a solenoid valve in the feedwater recirculation system, etc. The manual device has a plurality of types, and may be a manual air cylinder, a hydraulic cylinder, or the like, and this is not particularly limited in the embodiments of the present application.

In order to ensure the sealing performance of the feedwater recirculation system, the pneumatic ball valve may be a metal hard seal ball valve. The metal hard sealing ball valve is a zero-leakage pneumatic ball valve and is specially used for working conditions of high temperature, high pressure and severe erosion abrasion, and when the pneumatic ball valve is closed, the water supply recirculation system can be guaranteed to be tightly closed, the minimum flow valve 100 is protected, and therefore energy consumption loss caused by poor sealing of the minimum flow regulating valve 100 can be reduced.

In one possible implementation, the ball valve 600 is removably connected to the plumbing of the feedwater recirculation system. In this manner, the purpose of online maintenance of the ball valve 600 may be achieved. Specifically, under the condition that a maintainer maintains the ball valve 600, the maintainer can detach the ball valve 600 from the pipeline to replace an in-valve component of the ball valve 600, so that operations such as cutting, welding, heat treatment and the like on the valve can be avoided, the field maintenance work of the maintainer can be simplified, the maintenance cost is reduced, and the safety of the maintainer is protected.

In an implementation manner, the feedwater recirculation system disclosed in the embodiment of the present application may further include: the inlet of the pre-pump 800 is connected with the outlet of the deaerator 500, the outlet of the pre-pump 800 is connected with the inlet of the flow detection device 700 of the water supply recirculation system, the outlet of the flow detection device 700 is connected with the inlet of the water supply pump 400, and the outlet of the water supply pump 400 is connected with the outlet door 900 of the water supply recirculation system. The pressure of the feed water flowing into the feed water pump 400 can be increased by the pre-pump 800, and cavitation of the feed water pump 400 can be prevented.

Further, the feedwater recirculation system may further include: and the pre-pump inlet door 1000, wherein the pre-pump inlet door 1000 is arranged on a pipeline between the outlet of the deaerator 500 and the inlet of the pre-pump 800. By means of the pre-pump inlet door 1000, piping overpressure can be prevented, avoiding that the pre-pump 800 is damaged by too high a pressure of the feed water flowing into the pre-pump 800.

In the embodiments of the present application, the difference between the embodiments is described in detail, and different optimization features between the embodiments can be combined to form a better embodiment as long as the differences are not contradictory, and further description is omitted here in view of brevity of the text.

The above description is only an example of the present application and is not intended to limit the present application. Various modifications and changes may occur to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

Claims

1. A feedwater recirculation system, comprising: a minimum flow valve, a first isolation door, a second isolation door, a feed water pump, a deaerator and a ball valve, wherein,

the entry of first isolation gate with the first export of feedwater pump links to each other, the export of first isolation gate with the entry of ball valve with link to each other, the export of ball valve with minimum flow valve's entry links to each other, minimum flow valve's export with the entry of second isolation gate links to each other, the export of second isolation gate with the entry of oxygen-eliminating device links to each other.

2. The feedwater recirculation system of claim 1, further comprising: and the flow detection device is arranged at the position of the inlet of the feed water pump, detects the flow value of the inlet of the feed water pump, and transmits the flow value to the controller of the feed water recirculation system.

3. The feedwater recirculation system of claim 2, wherein the controller controls opening or closing of the ball valve.

4. The feedwater recirculation system of claim 1, wherein the ball valve is a pneumatic ball valve.

5. The feedwater recirculation system of claim 4, wherein the pneumatic ball valve comprises: a pneumatic actuator that performs an opening operation of the pneumatic ball valve or a closing operation of the pneumatic ball valve.

6. The feedwater recirculation system of claim 5, wherein the pneumatic ball valve further comprises: and (4) a manual device.

7. The feedwater recirculation system of claim 4, wherein the pneumatic ball valve is a metal hard seal ball valve.

8. The feedwater recirculation system of claim 1, wherein the ball valve is removably connected to the piping of the feedwater recirculation system.

9. The feedwater recirculation system of claim 1, further comprising: the inlet of the front pump is connected with the outlet of the deaerator, the outlet of the front pump is connected with the inlet of the flow detection device of the water supply recirculation system, the outlet of the flow detection device is connected with the inlet of the water supply pump, and the second outlet of the water supply pump is connected with the outlet door of the water supply pump of the water supply recirculation system.

10. The feedwater recirculation system of claim 9, further comprising: the pre-pump inlet door is arranged on a pipeline between the outlet of the deaerator and the inlet of the pre-pump.