JP2000140523A - Reverse-washable strainer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable a strainer to be maintained in an operating condition even when some of filtration chambers fails by arranging filtration screen members in the filtration chambers, each of which is formed by demarcating it with a partition and, at the same time, pivotally supporting a reverse wash switching valve on the upstream end part of each of the partitions, and further, providing a reverse wash control valve which is interlocked with the action of the reverse wash switching valve. SOLUTION: An untreated water containing impurities flowing into a housing 1 from an inflow aperture 10 uniformly flows into filtration chamber 3, each of which is formed by demarcating it with each of partitions 2 after the width of the untreated water is enlarged by a reducer part 1a. Further, the impurities are removed by filtration screen members 4 and are discharged from an outflow aperture 11 through a reducer part 1b. Next, the reverse wash is started, the inflow of a water flow into the filtration chambers 3 is stopped by a reverse wash switching valve 5. Interlocked with this stoppage, a reverse wash control valve is opened and, at the same time, a treated water after filtration flows back from the downstream side of the filtration screen members 4, and is drained to the outside of the system from a reverse wash water drainage duct, entrained by the impurities captured by the filtration screen members 4. Thus, the washing of the filtration screen members 4 is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backwashing strainer provided in an intake pipe for removing foreign substances such as dust and automatically backwashing a filtration screen.

[0002]

2. Description of the Related Art Conventionally, a large amount of seawater or river water is taken as cooling water in a power plant, a city gas manufacturing industry, a steel industry, or the like. It contains various foreign substances such as marine organisms such as fish and shellfish.These foreign substances flow into condensers and heat exchangers and cause blockage of cooling pipes. It is removed by a coarse dust removing device such as a bar screen or traveling screen installed.However, fine dust that cannot be captured by the screen and organisms attached and propagated after the dust removing device are present. A strainer having a filter screen capable of removing dust is provided as a secondary dust removing device.

[0003] In the above-mentioned strainer, a backwashing type strainer (hereinafter simply referred to as a strainer) having a backwashing mechanism for automatically washing and removing contaminants captured by a filtration screen by backflowing treated water. Is often used. Tokuhei 5-
In the conventional strainer described in Japanese Patent No. 10883 and Japanese Patent Application Laid-Open No. 9-57016, a cylindrical or arc-shaped filter screen having a corrugated cross section is provided in a housing.
With the suction port facing the inner peripheral surface of the
A hollow backwash arm for discharging backwash water is provided.

In the above-mentioned strainer, a filtration screen is used.
The raw water is circulated from the inside to the outside to remove impurities by filtration.However, in the part where the suction port of the backwashing arm that rotates at a constant speed is located, the treated water after the filtration flows from the outside to the inside. The filter screen is backwashed by backflow, and trapped impurities are discharged from a backwash water discharge line of the backwash arm connected to the suction port.

[0005] A circular filtration screen having a plurality of filtration chambers formed by partitioning the upstream side with a partition wall is disposed at right angles to the water flow, and is rotatably provided in the housing. An upstream side is provided with a backwash water discharge pipe facing a suction port facing one of the filtration chambers. In one chamber where a suction port of a filtration screen rotating at a constant speed is located, the inside is from outside to inside. There is also known a strainer having a structure in which treated water after filtration flows backward to backwash the filtration screen and discharges trapped impurities from a backwash water discharge line.

[0006]

In the conventional strainers, the mechanism for backwashing and discharging the trapped foreign substances is a single suction port or a backwash water discharge line.
If trouble occurs in the backwash water discharge mechanism,
It is necessary to stop the operation of the computer and solve the problem. Therefore, when arranging directly in a single intake line,
There is a problem that the water intake is stopped, which has a great effect on the power generation equipment body at the subsequent stage. Therefore, usually, a bypass flow path is provided in the intake pipe and arranged in one of the intake pipe or the bypass flow path. When the operation is stopped due to trouble, the intake pipe or the bypass flow path is opened to take water. Although it is configured or placed in both the intake channel and the bypass channel, the former arrangement requires an excessively large installation area for the device and also requires the piping to be routed. There is a problem that the equipment cost also increases. Furthermore, when it takes a long time to solve the trouble, since the water stream containing the impurities is supplied as it is to the heat exchanger for a long time, the accumulation of the impurities in the apparatus and the blockage of the pipes and the like are caused. There is a problem, and the latter arrangement has a problem that the equipment cost increases.

Accordingly, the present invention has a structure in which a trouble of the strainer is hardly caused, and it is not necessary to stop the operation of the whole strainer even if a trouble occurs, and the installation area of the apparatus is small. The purpose of the present invention is to provide a backwashing strainer in which the cost of piping equipment is low.

[0008]

The gist of the present invention for achieving the above object is to provide a strainer provided in an intake pipe for removing foreign substances such as dust and the like. A rectangular housing having an inlet for raw water connected to the upstream side of the intake pipe and an outlet for treated water connected to the downstream side, and a plurality of partition walls parallel to the flow direction of the water flow and partitioned into the housing. A plurality of filtration chambers parallel to the formed water flow, and filtration screens disposed in the respective filtration chambers.
Pivotally mounted on the upstream end of the partition member and the partition wall,
A backwash switching valve that is rotated by the rotating means to close the filtration chamber,
A backwash water discharge line connected to the housing side wall on the upstream side of the filtration screen member and communicating with each of the plurality of filtration chambers;
A backwash type strainer provided in a backwash water discharge line and having a backwash control valve for controlling a backwash operation in conjunction with the operation of a backwash switching valve.

Further, in the invention according to claim 2,
The strainer according to claim 1, wherein a backwash switching valve is provided on each of the plurality of partition walls to close the upstream side of a single filtration chamber, respectively. In the invention described in (1), a backwash switching valve is provided at every other one of the plurality of partition walls, and the upstream side of two filtration chambers adjacent to each other across the partition wall is alternately closed. is there.

[0010] The invention described in claim 4 is the first invention.
The filtering screen member according to any one of claims 1 to 3, wherein the filtering screen member is provided so as to be inclined downward with respect to the water flow, and in the invention according to claim 5, A strainer in which a part of the filtration screen member according to any one of claims 1 to 4 has a backwash switching valve structure that can be freely opened and closed.

[0011] With the above-described structure, the filtration part for impurities in the strainer can be formed in a plurality of filtration chambers, and the filtration mechanism and the backwash water discharge mechanism can be made independent for each filtration chamber. However, even if a trouble occurs in some of the filtration chambers or the backwash water discharge line, the entire apparatus can be operated without any problem as only the flow rate of the water flow is slightly reduced or the flow resistance is increased. be able to. Therefore, the need to stop water intake is extremely small, and the water intake pipe can be directly disposed in either the vertical part or the horizontal part, and there is no need to provide a bypass flow path. In addition, since piping is not always necessary, piping equipment costs are reduced.

Further, by making the housing a rectangular body, the filtration area can be made 1.5 times or more larger than the cross-sectional area of the water pipe, so that the filtration speed is reduced and the area for capturing foreign substances is increased. be able to. Furthermore, by providing the filtration screen member inclined downward with respect to the water flow,
Discharge of impurities at the time of back washing can be efficiently performed, and the area for capturing impurities can be further increased.

Further, by providing a backwash switching valve for closing the filtration chamber on each of the plurality of partition walls, each filtration chamber can be independently filtered and backwashed, and a plurality of backwash switching valves can be provided. By alternately closing the upstream sides of two filtration chambers adjacent to each other across the partition wall with a single backwash switching valve, the rotation of the backwash switching valve is provided. The moving device can also be simplified.

Further, by providing an emergency bypass valve having a flap valve structure capable of opening and closing a part of the filtration screen member, a large amount of dust or the like flows in, and the filtration efficiency in the strainer rapidly decreases. Also, by opening the emergency bypass valve to bypass the water flow, a necessary amount of water can be secured.

[0015]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view of a housing portion according to an embodiment of the present invention, and FIG.
FIG. 3 is a configuration diagram showing a part of the entire part in cross section, and FIG.
FIG.

1 is provided with an inlet 10 for raw water connected to the upstream side of the water intake line via a reducer section 1a;
The treated water outlet 11 connected to the downstream side of the intake pipe is a rectangular housing provided via the reducer 1b, and is disposed directly in either the vertical part or the horizontal part of the intake pipe. be able to.

The interior of the housing 1 is partitioned by a plurality of partition walls 2 parallel to the flow direction of the water flow, and a plurality of filtration chambers 3 parallel to the water flow are formed. A screen member 4 is stretched over the entire cross section of the water flow, and a backwash switching valve 5 having a flap valve structure for closing the filtration chamber 3 is rotatable at the upstream end of the partition wall 2. It is attached to the shaft.

A plurality of backwash water discharge pipes 7 connected to the side wall of the housing 1 on the upstream side of the filtration screen member 4 and communicating with each of the plurality of filtration chambers 3, and a plurality of backwash water discharge pipes. 7, a backwash control valve 8 for controlling the backwash operation in conjunction with the operation of the backwash switching valve 5 is provided.

As the filtering screen member 4, a member mainly formed of a wire netting, a punching plate or a grid is mainly used, and an appropriate size of the aperture is selected according to the use conditions. . The filtering screen shown in FIG.
In the connection member 4, the mesh is partially omitted. Furthermore,
Providing the filtration screen member 4 inclined downward with respect to the water flow allows efficient discharge of impurities during backwashing, and also increases the area for capturing impurities. Therefore, it is preferable.

Also, by providing an emergency bypass valve 9 having a flap valve structure that can be freely opened and closed in a part of the filtration screen member, a large amount of dust and the like flows in and the filtration efficiency in the strainer sharply decreases. In such cases, it is preferable to open the emergency bypass valve 9 in an emergency when a necessary amount of water has to be secured, so that the water flow can be bypassed.

The backwash switching valve 5 for closing the filtration chamber 3 is provided on each of the plurality of partition walls 2 so that each filtration chamber 3 can be filtered and backwashed in an independent configuration. By alternately closing the upstream sides of two filtration chambers 3 adjacent to each other with the partition wall 2 interposed therebetween by a single backwash switching valve 5, thereby performing backwash switching. This is preferable because the rotating means of the valve 5 can be simplified.

The rotating means for rotating the backwash switching valve 5 includes an actuator which is operated by electric power, hydraulic pressure or pneumatic pressure.
It is preferable that the filter 6 be provided for each of the backwashing switching valves 5 because each of the filtration chambers 3 can have an independent configuration. However, the filter 6 can be rotated by a single driving device by a clutch mechanism. It can also be configured.

Next, a filtering operation for removing contaminants from a water stream using the above-structured strainer will be described below. Raw water containing contaminants flowing into the housing from the intake pipe (not shown) through the inflow port 10 is widened by the reducer 1a and divided by a plurality of partition walls 2 parallel to the flow direction of the water flow. Uniformly flows into the filtration chamber 3.

The raw water flowing into the filtration chambers 3 is filtered by filtration screen members 4 extending over the entire cross section of each filtration chamber 3.
As a result, contaminants are removed, discharged through the outlet 11 from the outlet 11 to the downstream side of the intake pipe (not shown), and supplied to a heat exchanger or the like. In the ordinary filtering operation for removing the above-mentioned contaminants, the backwash switching valve 5 is positioned in parallel with the water flow so as not to cause a flow resistance of the water flow.

Next, the operation of discharging the contaminants captured by the filtration screen member 4 by backwashing will be described below. The backwashing operation is started by a timer starting method for periodically performing the backwashing operation at preset time intervals, and the state of the filtration screen member 4 caused by the accumulation state of impurities in the filtration screen member 4. By detecting the differential pressure on the upstream and downstream sides,
There is a differential pressure activation method in which a backwash operation is performed when a preset differential pressure is reached. Usually, the above two methods are used in combination, but a single method may be used.

When the backwash is started, at least one
The two backwash switching valves 5 are rotated by the actuator 6,
One filtration chamber 3 is closed, and the flow of the water flow into the filtration chamber 3 is stopped. In conjunction with the closing of the filtration chamber 3 by the backwash switching valve 5, the backwash control valve 8 provided in the backwash water discharge line 7 is opened, and at the same time, after the filtration from the downstream side of the filtration screen member 4, The treated water flows backward, and is discharged out of the system through the backwash water discharge line 7 together with the impurities trapped in the filter screen member 4, and the washing of the filter screen member 4 is completed.

In the timer starting method, after the backwash operation is performed for a time set by the timer, the backwash control valve 8 is operated.
Is closed and the backwash switching valve 5 is opened. However, in the differential pressure starting method, the backwash operation is continuously performed until the differential pressure becomes a steady state.

Normally, in order to secure the amount of water at the subsequent stage of the strainer, the above-mentioned backwashing operation is sequentially performed for each of all the filtration chambers 3 so that the filtration efficiency of the entire strainer is restored. However, depending on the conditions, it is possible to simultaneously backwash a plurality of chambers.

Further, even if a large amount of contaminants flows into the strainer for some reason, and the filtration efficiency in the strainer sharply decreases, it is necessary to secure a necessary amount of water in the downstream device. In such an emergency, a necessary amount of water can be secured by opening the emergency bypass valve 9 and forming a bypass flow path.

[0030]

The present invention has the following effects. Storage
Forming a plurality of filtration chambers for the filtration part of impurities in
Since the filtration mechanism and the backwash water discharge mechanism are made independent for each filtration chamber, even if a trouble occurs in a part of the filter chambers or the backwash water discharge pipe, it can be operated without any problem. Therefore, the need to stop water intake is extremely reduced, and since it can be arranged directly on either the vertical part or the horizontal part of the water intake pipe, the installation area of the device is also reduced, and
Since piping management is not always necessary, piping equipment costs are also reduced.

By making the housing a rectangular body, the filtration area can be made 1.5 times or more larger than the cross-sectional area of the water pipe, so that the filtration speed can be reduced and the area for trapping impurities can be increased. it can. In addition, by providing the filtration screen member inclined downward with respect to the water flow, it is possible to efficiently discharge foreign substances during backwashing, and to further increase the area for capturing foreign substances. Can be.

By providing a backwash switching valve for closing the filtration chamber on each of the plurality of partition walls, each filtration chamber can be independently filtered and backwashed, and the backwash switching valve can be divided into a plurality of partitions. Provided at every other wall, the upstream side of two filtration chambers adjacent to each other with the partition wall interposed therebetween is alternately closed by a single backwash switching valve, so that the rotating means of the backwash switching valve is also provided. Can be simplified.

By providing an emergency bypass valve having a flap valve structure capable of opening and closing a part of the filtration screen member, even if a large amount of dust or the like flows in and the filtration efficiency at the strainer is suddenly reduced, an emergency is required. By opening the bypass valve to bypass the water flow, a necessary amount of water can be secured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a housing according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a cross section of a part of the entire strainer according to the embodiment of the present invention;

FIG. 3 is a view as viewed in the direction of arrows AA in FIG. 2;

[Explanation of symbols]

 1: Housing 2: Partition wall 3: Filtration chamber 4: Filtration screen member 5: Backwash switching valve 6: Actuator 7: Backwash water discharge line 8: Backwash control valve 9: Emergency bypass valve 10: Inlet 11: Outlet

Claims (5)

[Claims] 1. A strainer provided in an intake pipe for removing impurities such as dust, wherein an inlet of raw water connected to an upstream side of the intake pipe and an outlet of treated water connected to a downstream side of the intake pipe. A rectangular housing provided; a plurality of filtration chambers parallel to the water flow formed in the housing with a plurality of partition walls parallel to the flow direction of the water flow; and filtration screen members disposed in the respective filtration chambers. And a backwash switching valve rotatably mounted on the upstream end of the partition wall and closed by the rotating means to close the filtration chamber, and connected to the housing side wall on the upstream side of the filtration screen member. A backwash water discharge line communicating with each of the plurality of filtration chambers, and a backwash control valve provided in the backwash water discharge line and controlling the backwash operation in conjunction with the operation of the backwash switching valve. A backwash type strainer characterized by being provided. 2. A backwashing strainer according to claim 1, wherein said backwash switching valve is provided on each of a plurality of partition walls and closes the upstream side of a single filtration chamber. 3. The backwashing type according to claim 1, wherein the backwash switching valve is provided at every other one of the plurality of partition walls, and alternately closes the upstream sides of two filtration chambers adjacent to each other with the partition wall interposed therebetween. Strainer. 4. The backwash type strainer according to claim 1, wherein said filter screen member is provided to be inclined downward with respect to the water flow. 5. The backwashing strainer according to claim 1, wherein a part of said filter screen member has a backwashing switching valve structure which can be opened and closed freely.