JPS5820290B2 - Strainer cleaning method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for cleaning a strainer disposed in a condensate outlet system, and particularly to a condensate pump suction side of a condensate outlet system in a condenser of a nuclear power generation or thermal power plant. The present invention relates to a cleaning method and apparatus suitable for cleaning a strainer installed in a machine.

Generally, in nuclear power generation or thermal power plants, high-temperature, high-pressure steam produced by a steam generator is used to perform work in a turbine, and then either remains as steam or is condensed and collected in the condenser 1 shown in Figure 1. Ru.

The steam or condensed water recovered in the body of the condenser 1 is cooled by seawater or fresh water introduced into the water chamber of the condenser, and becomes condensed water (hereinafter referred to as condensate) with a lower temperature.

This condensate is returned to the steam generator via the condensate outlet system A by the condensate pump 2.

A strainer 3 for removing crud is provided on the suction side of the condensate pump 2, and the condensate is cleaned by this strainer 3.

That is, when condensate is sucked out from the condenser 1 by the condensate pump 2, the condensate is contaminated with crud that has adhered to equipment, piping, valves, etc. in each system, and especially in plants. Since a large amount of crud is mixed in at the beginning of operation, the strainer 3 removes the crud to prevent the condensate pump 2 from malfunctioning.

Therefore, if the plant is operated for more than a certain period of time from the start of operation, the amount of crud that adheres to the mesh filter 3a of the strainer 3 increases over time, causing so-called clogging, which reduces the area of the condensate flow path in the strainer. As a result, the suction pressure of the condensate pump 2 decreases.

As a result, pump cavitation may be induced.

However, the condensate outlet system A is provided with a differential pressure gauge 4 that measures the pressure difference between the inlet side and the outlet side of the strainer 3, and when the differential pressure becomes large, a differential pressure gauge 4 is installed in parallel with the condensate outlet system A. The condensate pump 2' of the condensate outlet system N is started, and the condensate pump 2 and the condensate pump 2' are operated together so that the amount of circulating condensate does not decrease.

Next, after confirming that the condensate pump 1 is operating normally, the condensate pump 2 on the strainer side where the clogging has occurred is stopped, and the inlet valve 5 and outlet valve 6 of the condensate pump 2 are fully closed to restart the condensate pump. Isolate the water pump 2 from the condensate outlet system A.

Thereafter, the drain valve 7 and the vent valve 8 are fully opened to replace the strainer 3 and the condensate between the inlet of the strainer 3 and the inlet valve 5 with air.

That is, condensate is discharged from the drain system B by atmospheric pressure.

After that, the large mouth valve 9 of the cleaning water supply system C connected to the strainer 3 is gradually opened, and the cleaning water is continuously injected into the strainer 3 from the system C, and the water pressure adheres to the mesh filter 3a of the strainer 3. The crud is removed and is discharged from the drain system B via the drain valve 7 together with the cleaning water.

However, the conventional strainer cleaning method and device have the following drawbacks.

First, when the condensate pump 2 is stopped and the strainer 3 and the condensate between the strainer 3 and the large mouth valve 5 are naturally discharged by atmospheric pressure, the condensate is completely discharged from the drain system B. This means that it takes a very long time.

Secondly, the effect of cleaning the strainer cannot be sufficiently achieved by only spraying the cleaning water, and since the cleaning water is continuously sprayed, a large amount of water is required, which increases the amount of waste to be treated.

Regarding the first drawback, it is a problem that must be solved as soon as possible, especially in nuclear power plants, because the problem is not so much the radioactivity contained in the condensate, but rather the working time is limited.

As a way to shorten the time required to drain condensate,
One possible method is to increase the condensate discharge amount per unit time by increasing the diameter of the drain system B piping, but since the condensate is taken out from the bottom of the condensate outlet system A piping, space must be secured for the piping. This is difficult to realize due to problems such as high equipment costs.

The object of the present invention is to provide a strainer cleaning method and apparatus that eliminate the above-mentioned drawbacks.

Hereinafter, one embodiment of the present invention will be described based on FIG. 2.

FIG. 2 shows a strainer cleaning device according to this embodiment, and this cleaning device includes feeding pumps 23, 23'.
, a strainer 24, 24' installed on the suction side of the pump 23, 23', and the strainer 24, 24'.
Drain system 28 for discharging the crud removed from the
, 28', the strainer 24
, 24', and a dressing system 28, which discharges the crud removed from the strainers 24, 24'. 2B' is a drain pipe and valves 29 and 2 for discharging the accumulated water in the strainer 24 24' and the pump suction pipe to the outside of the system.
9'.

Using this device, in this embodiment, compressed air is force-fed to the strainers 24 and 24'.
, 24' and pump suction piping are discharged from the drain systems 28, 28' as described above, and then cleaning water is intermittently injected into the strainer while compressed air is fed to the strainer. A cleaning method is implemented in which the crud adhering to the pipe is removed and the crud is discharged from the above-mentioned drain system.

This example will be described in more detail below.

In the figure, 21 is a condenser, and 22 is a condensate outlet system that sends condensate from the condenser 21 to a steam generator (not shown).

23 is the above-mentioned feeding pump, but in this example, this is a condensate pump installed in the condensate outlet system 22, so
This will be explained below as the condensate pump 23.

As mentioned above, 24 is a crud removal strainer installed on the suction side of the condensate pump 23.

In this example, a mesh filter 24a is provided inside.

25 is a differential pressure gauge that measures the pressure difference between the inlet side and the outlet side of the strainer 24, 26 is a condensate pump artificial valve 1 provided on the inlet side of the strainer 24, and 27 is a condensate pump outlet valve.

28 is a drain system connected to the condensate outlet system 22 on the inlet side of the strainer 24 described above;
Reference numeral 8 includes a drain valve and a discharge pipe for discharging accumulated water in the strainer 24 and the pump suction pipe to the outside of the system.

30 is a system connected to the strainer 24, 31 is a system 30
A cleaning water supply system 32 is connected to the system 30, and a compressed air supply system 32 is connected to the system 30.

33 is an inlet valve provided in the wash water supply system 31, and 34 is an inlet valve provided in the compressed air supply system 32.

Note that the wash water supply system 31 is connected to a wash water supply source, such as a suitable feed pump, and the compressed air supply system 32 is connected to a compressor.

The compressed air discharged from the compressor is
The pressure is higher than the water pressure of the washing water.

Further, the drain system 28 is provided with a cladding monitoring net 35.

In this embodiment, a condensate outlet system 22' is provided in parallel with the condensate outlet system 22.
On the side, there is a condensate pump 2 which serves as a feeding pump similarly to the condensate outlet system 22, a strainer 24', and a mesh filter 24'a.
1 differential pressure gauge 25', condensate pump population valve 26', condensate pump outlet valve 27', drain system 28', drain valve 29', system 30', wash water supply system 31', compressed air supply system 3
2', a wash water supply valve 33', a compressed air supply valve 34', and a net 35' provided in the drain system 28'. ' are connected to a cleaning water supply system 31 and a compressed air supply system 32, respectively.

In the strainer cleaning device having such a configuration, as soon as the differential pressure gauge 25 detects that the strainer 24 is clogged, the condensate pump 23' is started and the condensate pump 23' is activated.
The large mouth valve 26' and the outlet valve 27' at 3' are fully opened, and the condensate pump 23 and the condensate pump 23' are operated in parallel to prevent the amount of circulating condensate from decreasing.

Next, after confirming that the condensate pump 23' is operating normally, the condensate pump 23 on the strainer side that has become clogged is stopped, and the inlet valve 26 and outlet valve 27 of the condensate pump 23 are fully closed. to isolate the strainer 24 from the condensate outlet system 22.

Thereafter, the drain system 29 is fully opened and the compressed air supply valve 34 is fully opened to force compressed air from the system 30 to the strainer 24, and the strainer 24 and its inlet side are connected to the condensate pump valve 23. The condensate between them is discharged from the drain system 28.

After the condensate has been discharged, the wash water supply valve 33 is intermittently opened and closed while compressed air is being forced into the strainer 24 to feed wash water to the system 30.

The cleaning water fed into the system 30 mixes with compressed air,
The pressure of the compressed air becomes high and the air is injected from the system 30 to the filter 24a of the strainer 24.

As a result, the crud adhering to the filter 24a of the strainer 24 is removed, and the crud is discharged into the drain system 28 along with the cleaning water and compressed air.

The crud discharged into the drain system 28 is captured by a net 35.

When cleaning of the strainer 24 is completed, the cleaning water supply valve 34 is fully closed.

The cleaning status of this strainer 24 is as follows:
This can be known by monitoring the amount of crud captured in step 5, and can also be used as an indication of the completion of cleaning.

It goes without saying that the present invention can also be applied to water systems equipped with strainers other than the embodiments described above.

As explained above, according to the present invention, the following effects can be obtained.

(1) Since compressed air is used to forcefully discharge the water between the strainer and the strainer inlet side and the pump valve, this method is significantly more effective than the conventional method of naturally discharging water using atmospheric pressure. condensate and drain time can be shortened.

Furthermore, since the cleaning water is mixed with compressed air to form high-pressure water and is injected into the strainer, the cleaning effect can be further enhanced, thereby significantly reducing the strainer cleaning time compared to conventional methods.

(2) Cleaning is performed by spraying cleaning water intermittently, so
Compared to the conventional technology in which washing water is continuously sprayed, the amount of washing water can be significantly reduced, and the amount of waste to be treated can also be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a condensate outlet system diagram with a conventional strainer cleaning device, and FIG. 2 is a condensate outlet system diagram with a strainer cleaning device of the present invention. 21...Condenser, 22.22'...Condensate outlet system, 23, 23'...Condensate pump, 2
4, 24'...Strainer, 24a, 24'a
...Mesh filter, 25°25'...
Differential pressure gauge, 26, 26'... Condensate pump population valve,
27, 27'...Condensate pump outlet valve, 28゜2
8'...Drain system, 29,29'...
・Drain valve, 30.30'...System connected to strainer, 31゜31'...Washing water supply system, 32,32'...Compressed air supply system, 33,
33'...Cleaning water supply valve, 34.34'
...Public valve for compressed air supply, 35°35'...
····network.

Claims (1)

[Scope of Claims] 1. In a water system equipped with a feeding pump, a crud removal strainer installed on the suction side of the pump, and a drain system for discharging the crud removed from the crud removal strainer. , compressed air is force-fed to the strainer to discharge accumulated water in the strainer and pump suction piping from the drain system, which is comprised of a discharge pipe and a valve, and then the cleaning water is pumped while compressed air is force-fed to the strainer. A method for cleaning a strainer, comprising intermittently injecting crud into the strainer to remove crud adhering to the inside of the strainer, and discharging the crud from the drain system. 2. In a water system equipped with a feeding pump, a strainer installed on the suction side of the pump, and a drain system for discharging the crud removed from the strainer, a system connected to the strainer and the system The drain system includes a cleaning water supply system and a compressed air supply system connected to the strainer, and a drain system that discharges the crud removed from the strainer, and a drain system that discharges accumulated water in the strainer and pump suction piping to the outside of the system. A strainer cleaning device characterized by comprising pipes and valves.