JPH06313504A - Strainer cleaner - Google Patents

Abstract

PURPOSE:To eliminate an exchange of a strainer by making it possible that the strainer is automatically cleaned. CONSTITUTION:A main pipe is branched into at least two systems in the upstream of a pump 101, one for a present use and the other as a spare, and a strainer 102 and 103 is provided at each of the branch pipe. An opening and closing valve 104 to 107 is provided on inlet side and outlet side of each of the strainers 102 and 103, and a blowline 111 and 112 to discharge fluid in the pipe to the external of the system and an opening and closing valve 113 and 114 to open and close the blowline is provided between the opening and closing valve on the inlet side of each of the strainers and the inlet side of the strainer in each of the branch pipes. The outlet sides of the strainers are connected by a bypass pipe and the middle part of the bypass pipe is connected to the downsteam side of the pump by a pipe to form a reverse wash line 108. In addition, a further opening and closing valve 109 and 110 is provided in the bypass pipe between the outlet side of each of the strainers and a connection point of the reverse wash line 108.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a strainer cleaning device installed at a pump inlet for removing suspended impurities in a condensate / water supply system of steam turbine equipment for power generation, for example.

[0002]

2. Description of the Related Art In the system configuration of a thermal power plant, first, steam is generated by a boiler, and the steam thus generated rotates a steam turbine of a generator to generate electric power. The steam that has passed through the steam turbine is returned to water by a condenser, then desalted and sent to a water storage tank. After that, the water in the water storage tank is sent to the boiler again, vaporized, and the steam turbine is rotated to repeat the circulation operation.

By the way, in such a condensate / water supply system of a steam turbine facility for power generation, a condensate pump, a boiler feed water pump (hereinafter referred to as BFP), a BFP booster pump, etc. are provided and circulated. Although the liquid phase is sent out, a strainer, which is a device for filtering the liquid phase, is provided at the inlet of each of these pumps in order to remove suspended impurities in the liquid phase (water) to be circulated. Then, clean water is supplied by passing through this strainer.

By the way, when the strainer for removing suspended impurities is clogged, it becomes difficult for water to pass through, and thus the strainer must be immediately replaced. for that reason,
If the active strainer is blocked and the active strainer is clogged, the circulation path is changed by first switching the circulation path from the active strainer side to the standby strainer side. Later, the strainer of the clogged system is being replaced.

[0005]

As described above, when the strainer in the condensate / water supply system of the steam turbine facility for power generation or the like becomes clogged, the strainer is replaced, but the work and the time required for the replacement are required. This was a heavy burden on the power station staff. That is, in the above-mentioned condensate / water supply system, at least the strainer installation section has multiple pipelines, and normally one of them is used to filter water, but the current system used for the filtration. If is clogged, switch the system from the active system to the standby system, then tighten the valve of the clogged system, remove the clogged strainer, and replace it.

After the replacement, this is put on standby as a standby system. In the case of such a conventional system, it is necessary to remove and replace the strainer, which is a very troublesome work, which requires manpower and time and leads to an increase in maintenance cost. Therefore, there is a strong demand for the development of a system that can eliminate such work.

Therefore, the object of the present invention is to
In the condensate / water supply system of steam turbine equipment for power generation, etc., the strainer installed at the pump inlet for removing suspended impurities can be automatically cleaned, and the strainer need not be replaced at all, facilitating maintenance management. An object of the present invention is to provide a strainer cleaning device that can be used.

[0008]

In order to achieve the above object, the present invention is configured as follows. That is, the present system branches the upstream side of the pump in the main pipeline into at least two systems to provide working and standby branch pipelines, and to each strainer, a strainer is provided, and an inlet side and an outlet side of each strainer are provided. An on-off valve is provided for each of the branch lines, and a blow line for discharging the line fluid to the outside of the system between the on-off valve on the inlet side of the strainer and the inlet side of the strainer in each branch line, and the blow line is opened and closed. An on-off valve is provided, and furthermore, the outlet side of each strainer is connected by a bypass line, and the intermediate part and the downstream side of the pump are connected by a line to form a backwash line,
Further, the bypass pipes are each provided with an on-off valve between the outlet side of each strainer and the connection point of the backwash line.

Further, the differential pressure detecting means for detecting the differential pressure between the inlet and outlet of each strainer and detecting the differential pressure when it reaches a set value, and the differential pressure detecting means responding to the detection output,
A control device that closes the open / close valve of the current system and opens the open / close valve of the spare system to switch the system, and opens the target open / close valve for at least a predetermined time to open the backwash line of the old active system. Provide and configure.

[0010]

In such a structure, normally, by opening only the inlet and outlet side opening / closing valves of the strainer in one of the branch lines of the two systems and driving the pump, the branch lines of the two systems are normally provided. One of the lines is used to pass a line liquid flow, and a strainer in the line removes suspended impurities while ensuring a liquid flow in the main line.

When the strainer is clogged, the opening and closing valves on the inlet side and the outlet side of the strainer of the other system are opened to secure a liquid flow passage to the main pipeline, and the strainer that has been clogged. The on-off and on-off valves on the side of the pump are closed, and among the on-off valves of the bypass pipeline and external blow line, the on-off valve on the side of the strainer that has clogged is opened to prevent the flow of liquid Part of the solution is made to flow through the backwash line, bypass line and external blow line, and the flow of liquid is made to flow backward through the strainer that has been clogged to remove suspended impurities, and then discharged outside the system. The on-off valve of the path for cleaning by the backflow is closed to return to the flow path of only the main pipeline.

Since the path for backwashing (washing by backflow) when the strainer becomes clogged can be secured only by operating the valve, it is not necessary to replace it even if the strainer becomes clogged. Therefore, maintenance management becomes extremely easy.

Further, by providing the differential pressure detecting means and the control device, the differential pressure detecting means detects the differential pressure between the inlet and outlet of each strainer, and when the differential pressure reaches the set value, this is detected. In response to the detection output of this differential pressure detection means, the on-off valve of the current system is closed, the on-off valve of the backup system is opened to switch the system, and the backwash line of the old current system is opened. Control is performed to open the target on-off valve for at least a predetermined time.

As a result, in a system in which the strainers provided at the inlets of the pumps are multiplexed in parallel (for example, doubled), one strainer is used by the backwash line connected from the pump downstream side to the downstream side of each strainer. The other strainer can be washed by backflow of water, and the strainer that has become clogged can be washed (backwashed) by backflow of water, eliminating the need to replace the strainer itself. Become.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The present invention provides a backwash line and a blow line in the strainer, and when the strainer is clogged during plant operation, this backwash line causes water to flow backward from the downstream side to the upstream side of the strainer (reverse flow). The backwashing process eliminates clogging of the strainer and eliminates the need for strainer replacement work, and the details thereof will be described.

(First Embodiment) FIG. 1 shows the basic configuration of the device of the present invention. FIG. 1 shows a normal state in a basic system that enables backwashing of the strainer, and FIG. 2 shows a backwashing state in the configuration of FIG.

In this basic system, the main pipe is branched on the inlet side of the pump 101 to make it dual. That is, the pump 101
The entrance side of A is branched into A and B pipelines.
An inlet valve 104, a strainer 102, and an outlet valve 106 are sequentially provided in the pipeline of the system.

Further, an inlet valve 105, a strainer 103 and an outlet valve 107 are provided in this order in the pipeline of the B system.
Each of these systems has an inlet valve 104, 105, an outlet valve 106,
By opening and closing 107, it is possible to cut off or open.

An external blow line 111 for connecting the pipeline of the A system to the outside of the system is provided between the strainer 102 and the inlet valve 104, and the B system of the B system is provided between the strainer 103 and the inlet valve 105. An outside-system blow line 112 that connects the pipeline and the outside of the system is provided. And the blow line 111 outside the system
The external blow valve 113 is provided in the external blow line 113, and the external blow valve 114 is provided in the external blow line 112.

Each strainer 1 is installed in the pipelines of A system and B system.
Bypass pipes are provided at positions downstream of 02 and 103, and backwash valves 109 and 110 are provided in the bypass pipes. Then, the backwash valves 109 and 110 of the bypass pipelines
A backwash line 108, which is a pipe line connected to a position on the downstream side of the pump 101 in the main pipe line, is provided between the installation positions.

By providing the backwash line 108 and the external blow lines 111 and 112, the liquid flow delivered from the pump 101 is routed through the strainer 102 or 103 by opening and closing each valve to set the pipeline. It becomes possible to form a reverse flow path that can flow to the outer blow line.

The backwash line is a line for washing a part of the forward liquid flow flowing through the main pipe line by backflowing it to the strainer, and the backwashing in this invention is a backwashing process. I am calling.

Next, the operation of the basic system having such a configuration will be described. Now, the inlet valve 104 and the outlet valve 102 in FIG.
Open only and keep all other valves closed.
It is assumed that the pipeline of the system is used as the active system and the pipeline of the system B is used as the standby system and is not used. In this case, by operating the pump 101, water will flow through the main pipeline, but this water will follow the pipeline of system A. Then, the strainer 102 in the pipeline of the system A captures and removes the suspended impurities contained in the water.

When the strainer 102 becomes clogged,
It becomes difficult for water to flow through the A line. So in this case,
The inlet valve 105 and the outlet valve 107 are opened, and the inlet valve 104 and the outlet valve 102 are closed. As a result, the flow path is changed from the A system pipeline to the B system pipeline.

At this time, as shown in FIG. 2, the backwash valve 109 and the outside blow valve 113 of the A system are opened. Then, a part of the water which flows through the pipeline of the B system and is sent out from the pump 101 is located downstream of the backwash valve 109 side of the bypass pipeline from the main pipeline and downstream of the A strainer 102, outside the A strainer 102, and outside the system. A flow is created in the route that follows the blow line 113 through the blow valve 113 and the blow line 111 outside the A system, whereby the strainer 102 of the A system generates a reverse water flow.
The suspended impurities clogging the eyes are removed and sent to the blow-out line 111 outside the A system.

That is, by opening the backwash valve 109 of the A system and the external blow valve 113, the pipeline of the A system flows through the pipeline of the B system and a part of the water sent from the pump 101 to the main pipeline. It becomes possible to secure a route for backflowing the A strainer 102 to the A system strainer 102, and by disposing the external blow line 111 as a drainage route to the outside of the main pipeline, the dirty water washed by the A system strainer 102 by the backflow is discarded to the outside. The strainer 102 can be cleaned only by operating the valve.

In this state, water is also sent to the main pipeline using the pipeline of system B, so that the strainer can be cleaned while continuing the water feeding. As a result, the suspended impurities that have caused the clogging of the A system strainer 102 are thrown out of the system through the outside system blow line 111, and the A system strainer 102 can be returned to normal operation without replacement work. It will be possible.

Once the strainer 102 has been cleaned,
The backwash valve 109 and the outside blow valve 113 of the A system are closed.
As a result, the bypass line is closed, and the blow line 111 outside the A system is also closed, so that the strainer 102 of the A system is closed.
There is no water flow to. As a result, the water flows only in the pipeline of the B system.

The B strainer 103 can be washed in the same manner. That is, when the B system is clogged, the inlet valve 104 of the A system strainer 102
And the outlet valve 106 is opened and the others are closed. As a result, the A-system pipeline is opened and the B-system pipeline is closed to form a flow path by the A-system pipeline.

The water flowing through the A system pipeline is sent from the pump 101 to the main pipeline. At this time, the backwash valve 110 and the outside blow valve 114 of the B system are opened. Then B
A part of the water that flows through the pipeline of the system and is sent out from the pump 101 flows from the main pipeline to the downstream side of the backwash valve 110 side of the bypass pipeline to the B strainer 103, the B strainer 103, and the external blow valve 114. To create a flow in the route that follows the B line outside system B blow line 112.
As a result, the B system strainer 103 removes the suspended impurities clogging by the reverse water flow and sends the suspended impurities to the B system outside blow line 112.

In other words, by opening the backwash valve 110 and the external blow valve 114 of the B system, the pipeline of the B system flows through the pipeline of the A system and a part of the water sent from the pump 101 to the main pipeline. Since it is possible to secure a route for backflowing the B system strainer 103 to the B system strainer 103, it is possible to wash the B system strainer 103 by the backflow by setting the external blow line 112 as a drainage route to the outside of the main pipeline, and as a result, to clean the contaminated water. Can be discarded to the outside, and the strainer 103 can be cleaned only by operating the valve.

In this state, water is also sent to the main pipeline using the pipeline of system A, so that the strainer can be washed while continuing the water feeding. After cleaning the strainer 103, the backwash valve 11 of the B system
0 and the external blow valve 114 are closed. As a result, the bypass line is closed, and the B-system outside blow line 112 is also closed, so that the flow of water to the B-system strainer 103 disappears. As a result, the water will flow only to the A system pipeline.

As described above, in the present system, the upstream side of the pump in the main pipeline is branched into two systems to provide working and standby branch pipelines, each branch pipeline is provided with a strainer, and the inlet of each strainer is provided. Side and outlet sides are respectively provided with open / close valves, and between the open / close valves on the inlet side of the strainer and the inlet side of the strainer in each branch pipeline, a blow line for discharging the pipeline fluid to the outside of the system, and An on-off valve that opens and closes the blow line is provided.Furthermore, the outlet side of each strainer is connected by a bypass line, and the intermediate part and the downstream side of the pump are connected by a line to form a backwash line. In addition, the bypass pipes are provided with opening / closing valves respectively between the outlet side of each strainer and the connection point of the backwash line.

Normally, by opening only the inlet and outlet side opening / closing valves of the strainer in one of the two branch lines, and driving the pump, the two branch lines are usually One of them is used to pass the pipeline fluid flow, and the strainer in the pipeline removes suspended impurities while ensuring the fluid flow in the main pipeline.When the strainer becomes clogged, the strainer of the other system is used. Open the inlet and outlet side on-off valves to secure the liquid flow passage to the main pipeline, close the inlet and outlet side on-off valves of the strainer that caused the clogging, and close the bypass pipeline and external blow line. Among the on-off valves, open the on-off valve on the side of the strainer that has caused the clogging, so that part of the liquid flow from the outlet side of the pump can be removed from the backwash line, bypass line and external blow line. Flow through the strainer that caused the clogging to remove the suspended impurities by removing the suspended impurities from the system, and after cleaning, close the on-off valve in the path for cleaning with this back flow. It is designed to return to the main flow path only.

By making it possible to secure the path for this backwashing when the strainer is clogged only by operating the valve, even if the strainer is clogged, its replacement is not necessary and maintenance management is possible. It will be extremely easy.

(Second Embodiment) FIG. 3 shows the construction of an automatic strainer cleaning apparatus having a strainer backwash function according to the present invention.

Although the basic piping structure and valve arrangement structure are the same as those in the first embodiment, the following structure is added in the second embodiment so that automatic cleaning can be performed. That is,
In this device, a pipe for pressure detection is connected to the inlet side and the outlet side of the A-system strainer 102, and a differential pressure switch 116a is provided to detect an internal pressure difference between the pipes. Also,
Similarly, a pipe for pressure detection is connected to the inlet side and the outlet side of the B system strainer 103, and a differential pressure switch 116b is provided to detect the internal pressure difference between the both pipes. Also,
Each valve 104, 105, 106, 107, 109, 11
Reference numerals 0, 113, and 114 are electromotive valves such as solenoid valves, which enable the opening / closing of the valves to be performed by an open / close drive signal.

When the differential pressure reaches a set value, the differential pressure switches 116a and 116b operate to detect clogging of the A system strainer 102 and the B system strainer 103, and switch the system to secure a flow path. In addition to doing this, secure a backwash route for the strainer of the system that caused the clogging, clean the clogging strainer using this backwash route, and then close the route for the backwash after completion, and use only one system for normal flow. A sequence control device 117 for performing a sequence control operation of returning to the secured state is provided, and each valve 10 is driven by a drive signal of the sequence control device 117.
4, 105, 106, 107, 109, 110, 11
3, 114 is configured to be controlled to be opened / closed so as to achieve a desired sequence operation.

In such a structure, when the strainer is clogged, the pressure between the inlet and the outlet becomes large in the strainer in which the strainer is clogged. Each strainer 102, 103 is provided with a differential pressure switch 116a, 116b in order to detect the clogging, and therefore,
When the strainer of the system currently in use is clogged and it becomes difficult for the liquid flow to pass, a pressure difference occurs, and when the pressure difference reaches a set value, the differential pressure switch of the strainer operates.

Now, the active system is the A system, and the backup system is the B system.
It is assumed that the pipeline is closed for the backup system. When the A-system strainer 102 is clogged, the differential pressure switch 116a for the A-system strainer 102 operates at the stage when the differential pressure reaches a predetermined set value, whereby the sequence controller 117 causes the A-system strainer 1 to operate.
02 Occurrence of clogging is detected, and B system inlet valve 10
5, output the opening drive signal of the outlet valve 107, the inlet valve 10
5. The outlet valve 107 is controlled to open, while the closing drive signal for the inlet valve 104 and the outlet valve 106 of the A system is output.
The inlet valve 104 and outlet valve 106 of the system are closed. As a result, the flow path is changed from the A system pipeline to the B system pipeline.

Next, the sequence controller 117 outputs an open drive signal for the backwash valve 109 and the outside blow valve 113 of the A system, and controls the backwash valve 109 and the outside blow valve 113 to open. Then, the pump 101 flows through the pipeline of the B system.
A part of the water sent out from the main pipeline is passed from the backwash valve 109 side of the bypass pipeline to the downstream side of the A strainer 102, the A strainer 102, and the external blow valve 113, and the A external blow line 111. This will create a flow on the route that follows the
In the case of 02, the reverse water flow removes the suspended impurities that have clogged and is sent out to the blow-out line 111 outside the A system.

In this state, the sequence controller 117 continues backwashing for a specified time (preset time), checks the state of the differential pressure switch 116a when the specified time has elapsed, and checks the differential pressure switch 116a. Is operating, cleaning by backwashing is continued until the differential pressure switch 116a stops operating.

As a result of checking the state of the differential pressure switch 116a, if it is not in the operating state, the backwash valve 109 and the outside blow valve 113 of the A system are closed. As a result, the bypass line is closed, and the A-system outside blow line 111 is also closed, so that the flow of water to the A-system strainer 102 disappears. As a result, the water flows only in the pipeline of the B system.

If clogging occurs during use of the strain A strainer 102 as described above, the differential pressure switch 116a automatically detects and a part of the liquid flow is blocked.
After the cleaning is completed, the backwash line can be closed and the water can be returned to the normal main route only.

The B system strainer 103 can be cleaned automatically in the same manner when clogging occurs. (Third Embodiment) Next, a system configuration in which the present invention is applied to a thermal power plant and automatic strainer cleaning and manual cleaning can be performed will be described as a third embodiment. FIG. 4 shows the system configuration, and FIGS. 5 to 8 show the sequence logic. However, FIG. 5 is an overall view, and FIGS. 6 to 8 are partially enlarged views of FIG.

In FIG. 4, 1 is a boiler, 2 is a steam turbine, 3 is a generator, and 4 is a condenser. The boiler 1 is for generating steam, and the steam turbine 2 is rotated by the steam generated by the boiler 1 to operate the generator 3. The condenser 4 is for returning the steam that has been used through the steam turbine 2 to water.

The water returned by the condenser 4 is returned to the condensate pump 5
The condensate pump 5 has a plurality of systems and is connected in parallel so that two of the condensate pumps 5 are used in the normal operation state. A strainer 17 is provided on the inlet side of each condensate pump 5, and an electric valve is provided on the outlet side of each condensate pump 5.

Further, a gland steam condenser is provided on the outlet side of the condensate pump 5 in the circulation conduit, which is the main conduit, and is further desalted by the condensate demineralizer 7,
The circulation pipe is sent to the low-pressure feed water heater 9 side by the condensate booster pump 8 and is heated there.

Then, hot water is deaerated by the deaerator 10 and stored in the deaerator water storage tank 11. The hot water stored in the deaerator water storage tank 11 passes through the booster pump 12 for the electric motor driven water supply pump and the electric motor driven water supply pump 13 to become high pressure hot water, which is sent to the high pressure water heater 16 to be heated and then heated by the boiler. It constitutes a circulation route that is said to be sent to the first unit.

Booster pump 1 for electric motor driven water supply pump
In the serial connection portion of the motor 2 and the electric motor driven water supply pump 13, the upstream side is shunted into two systems, and strainers 17 are provided in each of them. Further, the strainer 17, the electric motor-driven feed water pump booster pump 12 and the electric motor-driven feed water pump 13 are connected in series in parallel with the strainer 17, the electric motor-driven feed water pump 13 and the turbine-driven feed water pump booster pump 14 connected in series. It is provided for the system.

In this way, in the actual power plant, strainers are provided at the downstream side of the condenser, the inlet side of the pump arranged at the upstream side of the high-pressure feed water heater, etc. to remove suspended impurities. The pipeline is for multiple systems,
If they are arranged side by side, one is used as the current one and the other is used as the spare, and the spare is put on standby, so if the strainer used as the current is clogged, clean it to eliminate the clogging. You need to do it.

Therefore, a pipe for backwashing, as described in the first and second embodiments, is provided between the downstream side of the line portion where the strainer 17 is arranged and the outlet side of the pump. A system and a control facility shall be provided so that the system can be switched and the clogging strainer can be cleaned by opening and closing the valve.

Then, the sequence control device 117 is made to be able to execute the control logic as shown in FIG. The operation of the sequence controller 117 having the control logic as shown in FIG. 5 will be described below. In the following, the configuration of FIG. 3 will be described as an example.

This system is provided with a manual cleaning command button PB for strainers for A system / B system, and by manually operating this button, the target strainer can be cleaned by backwashing. If the differential pressure switch operates during operation, system switching and automatic cleaning of the clogging strainer can be performed.

Further, this system is provided with a system switching command button PB for A system / B system, and by operating this, system switching between A system / B system can be performed.

Now, if the manual cleaning command button PB is operated (S1) or the differential pressure switch is operated (S2).
7) The command is generated under the condition that the strainer of the commanded system or the system in which the differential pressure switch has operated is operating (S2) and the strainer of the other system is not operating (S3). (S4) If the strainer cleaning is not completed (S28), the inlet valve and the outlet valve of the strainer of the other system are fully opened (S9, S1).
0). Then, the inlet valve and the outlet valve of the strainer of the currently used system are fully closed (S11-
S14). Then, in this state, the strainer of the other system is in use and the fact that the system is in use is registered (S15, S16).

Further, after the system switching and the system registration are completed in this way, the closed system, that is, the strainer backwash valve on the side of the clogging strainer is fully opened, and after delaying for a predetermined time. The outside blow valve on the clogging strainer side is fully opened to secure a backwash path for the clogging strainer (S17 to S20).

After maintaining this state for a predetermined time, the strainer backwash valve on the side of the clogging strainer is fully closed, and the outside blow valve on the side of the clogging strainer is fully closed to remove the clogging strainer. The backwash route is closed (S2
1 to S25).

Then, the inlet valve and the outlet valve of the system of the clogging strainer for which the backwashing has been completed are fully opened (S26, S2).
(9, S30, S31), and thereafter, the inlet valve and the outlet valve of the strainer of the other system that has been in service are fully closed, and the strainer cleaning is completed (S32 to S36).

When the button for switching the strainer is pressed (S37), the inlet valve and the outlet valve of the strainer of the other system (spare system) are fully opened (S3).
8, S39, S8 to S10). Then, the inlet valve and the outlet valve of the strainer of the currently used system are fully closed (S11 to S14). Then, in this state, the strainer of the other system is in use and the fact that the system is in use is registered (S15, S16). As a result, the operation for switching the spare operation to the current operation is completed.

When the system switching and the system registration are completed in this way and the switching operation is completed, S37
After the operation of the button in (3) is finished, the other system (standby system) is in use, and the operation after S17 is not performed.

However, if the manual cleaning command button PB is operated (S1) or the differential pressure switch is operated (S1).
27) The above-described operation can be performed to automatically clean the clogging strainer.

As a result of the operation of the sequence controller 117 according to the above operation logic, the strainer is switched from the working system to the backup system, and the old working system strainer that has been clogged is backwashed, and after the backwashing. It is possible to automatically switch to the former working grid strainer.

Further, according to the present invention, even when the strainer is clogged with suspended impurities and needs to be replaced, the standby system strainer is automatically switched to the strainer in which clogging has occurred. As a result of being automatically backwashed, strainer replacement work is unnecessary,
Maintenance work when the strainer becomes clogged can be eliminated almost entirely. The present invention is not limited to the embodiments described above and shown in the drawings, and can be appropriately modified and implemented within the scope of the invention.

[0065]

As described above in detail, according to the present invention, when the strainer is clogged with suspended impurities and needs to be replaced, the standby system can be automatically switched to the strainer. If the strainer is clogged, the backwash route is secured and the backwash is automatically performed.Therefore, strainer replacement work is not required.
The effect that the maintenance work when the strainer is clogged can be almost completely eliminated can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention,
The systematic diagram showing the whole 1st example composition of the present invention.

FIG. 2 is a diagram for explaining an embodiment of the present invention,
The figure which shows the appearance of the system at the time of a backwash operation in 1st Example.

FIG. 3 is a diagram for explaining an embodiment of the present invention,
The systematic diagram which shows the whole structure of the 2nd Example of this invention.

FIG. 4 is a system diagram showing an overall configuration of a thermal power plant to which the present invention is applied.

FIG. 5 is a diagram for explaining an embodiment of the present invention,
The logic sequence diagram of the sequence control apparatus as 3rd Example of this invention.

6 is a partially enlarged view of the logic sequence diagram shown in FIG.

FIG. 7 is a partially enlarged view of the logic sequence diagram shown in FIG.

FIG. 8 is a partially enlarged view of the logic sequence diagram shown in FIG.

[Explanation of symbols]

 102, 103 ... Strainers 104, 105 ... Inlet valves 106, 107 ... Outlet valves 108 ... Backwash lines 109, 110 ... Backwash valves 111, 112 ... External blow lines 113, 114 ... External blow valves 116a, 116b ... Differences Pressure switch 117 ... Sequence control device

Claims (3)

[Claims] 1. An upstream side of the pump in the main pipeline is branched into at least two systems to provide working and standby branch pipelines, and a strainer is provided in each branch pipeline.
On-off valves are provided on the inlet and outlet sides of each strainer, and a blower that discharges pipeline fluid to the outside of the system is provided between the on-off valve on the inlet side of each strainer and the inlet side of the strainer in each branch pipeline. A line and an on-off valve that opens and closes the blow line are provided.Furthermore, the outlet side of each strainer is connected by a bypass line, and the intermediate part and the downstream side of the pump are connected by a line to backwash. A strainer cleaning device characterized in that an opening / closing valve is provided between the outlet side of each strainer and the connection point of the backwash line in the bypass line. 2. A differential pressure detecting means for detecting the differential pressure between the inlet and outlet of each strainer and detecting when the differential pressure reaches a set value, and responding to the detection output of the differential pressure detecting means, A control device that closes the on-off valve of the current system, opens the on-off valve of the standby system to switch the system, and opens the target on-off valve for at least a predetermined time to open the backwash line of the old current system The strainer cleaning device according to claim 1, wherein the strainer cleaning device is configured as follows. 3. The backwash line connecting between the downstream side of the pump and the downstream side of the strainer, so that one strainer can be washed by backflow of water while the other strainer is in use. Strainer cleaning device.