JPH0957016A - Automatic backwashing type strainer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve backwashing capacity and to smoothly continue operation even when large rubbish flows in. SOLUTION: This strainer is provided with a filter screen 30 in which plural groove-shaped pockets 31 extending in the up and down directions are formed on the inner periphery at a prescribed pitch and hollow arms 80, 90 for rotating suction ports 83, 93 and port seals 84, 94 projecting from both sides thereof facing the inner surface of the filter screen 30. Rubbish caught in each pocket 31 is ducked into the suction ports 83, 93 of the backwashing arms 80, 90 together with water to be treated to backwash the filter screen 30. Plural pairs of partitions 32 extending in the up and down directions at prescribed intervals are provided projectingly on the inner periphery of the filter screen 30 at a prescribed pitch. An extended pocket 34 communicating with the pocket 31 is formed between each pair of partitions 32, 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic backwashing strainer, and more specifically, it can improve the backwashing ability of a filtering screen, and can continue its operation smoothly even if dust such as an empty can flows in. The present invention relates to an automatic backwash strainer which has been improved so that it can be used.

[0002]

2. Description of the Related Art An automatic backwash strainer having an automatic cleaning function of a filter element has been generally known as a filter device for dust removal installed in an intake channel for various industrial waters and a drainage channel for industrial wastewater (actually, (See Japanese Patent Publication No. 5-10883).

The automatic backwash strainer described in the above publication has a filter screen arranged in a cylindrical or arcuate shape in a main body having a raw water inlet and a treated water outlet so that raw water containing dust flows from the inside to the outside. A hollow backwash arm that rotates with the suction port facing the inner periphery of the filter screen is mainly configured. Here, the filter screen is a perforated plate processed into a corrugated cross section, and a plurality of groove-shaped pockets extending in the vertical direction are formed at a predetermined pitch on the inner periphery thereof. Further, the backwash arm is a hollow wing-shaped one that is fixed to a hollow shaft vertically installed in the center of the main body and rotates slowly, and the suction port facing the inner circumference of the filter screen is located at a predetermined position facing each pocket. A port seal having a vertically long width and having arcuate surfaces along the inner circumference of the filter screen projects on both left and right sides of the suction port.

In this automatic backwash strainer,
The raw water containing dust passes through the filter screen from the inner side to the outer side, so that the dust is trapped in a plurality of groove-shaped pockets formed on the inner side of the filter screen, and on the outer side of the filter screen. Treated water from which dust is removed is obtained. In addition, as the backwash arm rotates, its suction port sequentially faces each pocket on the inner circumference of the filtration screen, and its port seals sequentially face the inner circumference of the filtration screen on both the left and right sides of each pocket. The atmospheric pressure acts on each pocket, and the dust trapped in the pocket is sucked into the suction port of the backwash arm together with the treated water on the outer peripheral side of the filter screen, and thus the filter screen is backwashed. .

Such an automatic backwash strainer has a relatively large capacity because the movable part is only the backwash arm and there are few troubles and the filtration screen is formed in a corrugated cross section so that the filtration area is large. It tends to be frequently used for water intake. For example, recently, in the intake channels for liquefied natural gas evaporator seawater at liquefied natural gas power plants and turbine condenser cooling seawater, primary dust removers such as bar screens and traveling screens that remove coarse dust particles are used. Installed in the latter stage to remove relatively small dust 2
It is widely used as the next dust remover.

[0006]

If the automatic backwash strainer is installed as a secondary dust remover after the primary dust remover such as a bar screen or a traveling screen as described above, the primary dust remover is used. Coarse dust, including empty cans, may flow into the automatic backwash strainer due to machine trouble. Here, among the coarse dust particles, the heavy dust particles are separated and settled on the inner bottom portion of the main body of the automatic backwash strainer. However, since each pocket of the filter screen that captures dust does not have enough space to accommodate an empty can, the empty can and the like are eventually captured in a state of protruding from the inside of each pocket. Therefore, as the backwash arm rotates, dust such as an empty can is trapped between the port seal and the filtration screen to prevent the backwash arm from rotating, thus overloading the backwash arm drive system. There are problems such as the occurrence of such a phenomenon and, in an extreme case, the rotation of the backwash arm is stopped.

On the other hand, since the filter screen in the above-mentioned automatic backwash strainer is a perforated plate processed into a corrugated cross section and arranged in a cylindrical or arc shape, a high roundness is required on the inner peripheral surface thereof. It is originally difficult to do.
Under such circumstances, undulations and local irregularities are also seen on the inner peripheral surface of the filter screen, and the tendency becomes more remarkable as the size of the automatic backwash strainer increases. For this reason, it is difficult to make the port seal of the backwash arm closely face the inner peripheral surface of the filter screen, and a relatively large gap is formed between the port seal and the inner peripheral surface of the filter screen.
Therefore, in order to fill this gap, it has been proposed to attach a brush to the port seal, but just by attaching the brush, the raw water inside the filtration screen will inevitably pass through the brush and be sucked into the suction port of the backwash arm. I will end up. This means that the amount of treated water outside the filtration screen that should be originally sucked into the suction port of the backwash arm is reduced, and the dust removal capability in the pocket, that is, the backwash capability of the filtration screen is reduced. The improvement is strongly demanded.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to improve the backwashing ability of a filter screen and to smoothly perform even if a slightly large dust such as an empty can flows in. An object is to provide an automatic backwash strainer that can continue to operate.

[0009]

As a means for solving the above problems, the present invention has a cylindrical or arcuate cross section having a plurality of vertically extending groove-shaped pockets formed at a predetermined pitch on the inner circumference. Each of the pockets is equipped with a filter screen, a suction port of a predetermined width facing the pocket, and a hollow backwash arm that rotates with port seals projecting to the left and right sides of the filter screen facing the inner circumference of the filter screen. In an automatic backwash strainer for backwashing the filter screen by sucking the captured dust with the treated water on the outer peripheral side of the filter screen into the suction port of the backwash arm, the inner periphery of the filter screen, Plural pairs of partition walls, which extend vertically and are spaced apart from each other, and whose inner edges are adjacent to and facing each other with a gap in the port seals on the left and right sides of the suction port, are provided at a predetermined pitch. , Characterized in that the formation of the wide expansion pocket communicating with the pockets between each pair of partition walls.

[0010]

In the automatic backwash strainer of the present invention, the raw water containing dust passes through the filter screen from the inner peripheral side to the outer peripheral side, whereby the dust in the raw water is filtered by the filter screen and the outer peripheral side of the filter screen. As a result, treated water from which dust is removed can be obtained.

Here, among the dust particles in the raw water, relatively small dust particles are trapped in a plurality of groove-shaped pockets formed on the inner circumference of the filter screen, and are slightly large such as empty cans that cannot fit in the pockets. Dust is also captured in the expansion pocket formed between each pair of partitions. For this reason, the backwash arm pinches dust such as an empty can and rotates smoothly without causing an overload.

With the rotation of the backwash arm, a plurality of pairs of partition walls projecting on the inner circumference of the filter screen are sequentially paired one by one with their inner edges having gaps in the port seals on the left and right sides of the suction port of the backwash arm. And approach each other closely. For this reason, the atmospheric pressure in the suction port reliably acts on the inside of the pocket through the expansion pocket partitioned by the pair of partition walls, and only the treated water on the outer peripheral side of the filtration screen is sucked into the pocket. The dust trapped in the pocket with water is sucked into the suction port of the backwash arm, thus ensuring that the filter screen is backwashed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an automatic backwash strainer according to the present invention will be specifically described below with reference to the drawings. FIG. 1 is a vertical sectional view showing the entire structure of the automatic backwashing strainer, FIG. 2 is a sectional view taken along the line II-II of FIG. 1 showing the main structure of the automatic backwashing strainer, and FIG. 3 is a view of the automatic backwashing strainer. FIG. 4 is an enlarged sectional view of a part III in FIG. 2 showing an enlarged main part structure.
FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3 showing a modified example of the main part structure.

As shown in FIG. 1, an automatic backwash strainer according to one embodiment includes a main body housing (10) composed of a pressure vessel having a closed structure.
In the lower part of 0), a raw water inlet (11) into which raw water containing dust flows in and a treated water outlet (12) from which treated water from which dust has been removed flow out are arranged on the diameter line.

In the main body housing (10), a swash plate (20) having a raw water passage opening (21) in the center is installed so as to deflect the raw water flowing from the raw water inlet (11) upward. Above the swash plate (20), a cage (40) having a filtration screen (30) stretched on the inner surface is arranged in a cylindrical shape so that raw water is filtered from the inside to the outside and passed.

On the other hand, in the center of the cage (40),
A motor (5) installed on the upper surface of the main body housing (10)
0), a hollow shaft (60) is rotatably driven at a slow speed of about 1 to 6 revolutions per minute, and a discharge pipe (70) for releasing the atmosphere has an appropriate sealing member below it. It is connected to allow the rotation of the hollow shaft (60). The hollow shaft (60) is provided with two upper and lower backwash arms (80, 90) each having a hollow wing shape so as to project in opposite directions in the radial direction, and extend along the hollow shaft (60). The base end (81, 91) of each backwash arm (80, 90) extending
Communicate with the hollow shaft (60).

The filter screen (30) has a thickness of 1 to 3 m.
A perforated plate obtained by perforating a large number of holes with a diameter of 5 mm or less on a stainless steel plate of about m is bent into a corrugated cross section as shown in FIGS. 2 and 3, and extends vertically in the inner circumference thereof. A plurality of groove-shaped pockets (31, 31, ...) Are formed at a predetermined pitch.

Correspondingly, the filter screen (30)
At the tip portion (82) of the backwash arm (80) facing the inner peripheral side of the pocket (31), there is provided a vertically long suction port (83) extending vertically with a width substantially corresponding to the opening width of the pocket (31). 31, 31, ...) are sequentially formed to face each other. Then, the back end of the backwash arm (80) (8
Port seals (84) projecting to the left and right sides of the suction port (83) are attached to 2). The peripheral surface (8) of the port seal (84) facing the filter screen (30)
5) is formed in an arc surface centered on the hollow shaft (60).

Although not shown, a similar suction port (93) is formed at the tip portion (92) of the backwash arm (90) facing the inner peripheral side of the filter screen (30), and the same suction port (93) is formed. A port seal (94) having a peripheral surface (95) is attached.

Here, as shown enlarged in FIG. 3, each pocket (31, 31, ...) Of the filtration screen (30).
Has a wide tapered groove shape, and bar-shaped partition walls (32, 32, ...) That extend in the vertical direction are formed on the inner circumferences of the pockets (31, 31, ...). Three
, 31, ...) are welded and fixed at pitch intervals corresponding to the pitch intervals of (1, 31, ...).

Each of the partition walls (32, 32, ...) Overhangs inward along the radial direction of the filter screen (30), and the inner edge (33, 33, ...) Of the backwash arm (80). , 90) of the port seals (84, 94) are machined in advance so as to have an inner diameter dimension that allows close proximity to each other with a gap therebetween. A pair of partition walls (3) located on both sides of each pocket (31, 31, ...).
2, 32), an expansion pocket (34) having a minimum width of 83 mm and a depth of 55 mm that can accommodate an empty can (A) having a diameter of 50 mm and a length of about 80 mm in a lateral direction is inside the pocket (31). Is formed in communication with.

In the automatic backwash strainer thus constructed, raw water containing dust flows from the raw water inlet (11) into the main body housing (10) and flows through the raw water passage opening (21) of the swash plate (20). The filter screen (3) that passes through the cage (40) and rises into the cage (40) above is installed.
0) from inside to outside. In this process, the dust in the raw water is filtered by the filter screen (30), and the treated water on the outer peripheral side of the filter screen (30) from which the dust is removed is discharged from the treated water outlet (12) of the main body housing (10). .

Of the dust particles in the raw water filtered by the filter screen (30), relatively small dust particles are pockets (31, 3) formed on the inner circumference of the filter screen (30).
(1, ...) captured in each pocket (31, 31, ...)
Some large dust such as empty cans (A) that can't fit inside
It is captured in an expansion pocket (34) formed between the pair of partition walls (32, 32). Therefore, the backwash arm (80,
90) does not sandwich an empty can (A) or the like between itself and the filter screen (30), and rotates smoothly without causing overload of the motor (50).

Here, with the rotation of the backwash arm (80, 90), for example, the suction port (83) of the backwash arm (80) is inserted into each pocket (31, 31,) of the filtration screen (30).
...) sequentially facing each other, and at that time, the pair of partition walls (32, 3) located on both the left and right sides of the pocket (31).
In 2), the inner edges (33, 33) closely face and face the peripheral surface (85) of the port seal (84) with a gap. For this reason,
The atmospheric pressure reaching the suction port (83) through the path of the discharge pipe (70), the hollow shaft (60) and the backwash arm (80) surely acts on the inside of the pocket (31) via the expansion pocket (34). Therefore, the treated water on the outer peripheral side of the filtration screen (30) flows into the pocket (31) due to the pressure difference from the atmospheric pressure. At that time, since the raw water inside the filter screen (30) rarely enters the expansion pocket (34) from between the port seal (84) and the partition walls (32, 32), it enters the pocket (31). A large amount of treated water flows in, and the dust trapped in the pocket (31) together with the large amount of treated water is sucked into the suction port (83) of the backwash arm (80), and thus the filtration screen (30) is Definitely backwashed. The filtration screen (30) is reliably backwashed by the same action when the backwash arm (90) is rotated.

FIG. 4 shows a modified example in which the pitch intervals of the pockets (31, 31, ...) Of the filter screen (30) are relatively small.
2, 32, ...) are alternately projected from the inner periphery of the filter screen (30) so that the two pockets (31, 31) are sandwiched therebetween, and are expansion pockets between the pair of partition walls (32, 32). At least 50 mm diameter and 100 length within (34)
An empty can (B) of about mm is placed sideways so that it can be accommodated.

[0026]

As described above, according to the automatic backwash strainer of the present invention, among the dust particles in the raw water, relatively small dust particles are stored in the plurality of groove-shaped pockets formed on the inner circumference of the filter screen. Even larger dust such as empty cans that are trapped in the pockets and cannot fit in the pockets are trapped and accommodated in the expansion pocket formed between each pair of partition walls. For this reason, the backwash arm can rotate smoothly without being overloaded by sandwiching the coarse dust, and the automatic backwash strainer of the present invention can continue the operation smoothly even if the coarse dust flows in. It is possible to prevent a decrease in operating rate.

Particularly, with the rotation of the backwash arm, a plurality of pairs of partition walls projecting on the inner periphery of the filter screen are sequentially paired one by one on the inside edge thereof at the port seals on the left and right sides of the suction port of the backwash arm. Face each other closely. Therefore, the atmospheric pressure in the suction port reliably acts in the pocket through the expansion pocket partitioned by the pair of partition walls. Therefore, only the treated water on the outer peripheral side of the filter screen is sucked into the pocket, and the dust trapped in the pocket together with the treated water is surely sucked into the suction port of the backwash arm. You can improve your ability.

From a structural point of view, it is only costly because it is only necessary to project a plurality of partition walls on the inner circumference of the filter screen and it is not necessary to modify the filter screen itself.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the overall structure of an automatic backwash strainer according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG. 1 showing a main part structure of an automatic backwash strainer according to one embodiment.

FIG. 3 is an enlarged cross-sectional view of a III part in FIG. 2 showing an enlarged main part structure of the automatic backwash strainer according to the embodiment.

FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3 showing a modified example of the main part structure.

[Explanation of symbols]

 10: Main body housing 11: Raw water inlet 12: Treated water outlet 20: Swash plate 21: Raw water passage port 30: Filtration screen 31: Pocket 32: Partition wall 33: Inner edge 34: Expansion pocket 40: Cage 50: Motor 60: Hollow shaft 70: Discharge pipe 80, 90: Backwash arm 81, 91: Base end part 82, 92: Tip part 83, 93: Suction port 84, 94: Port seal A, B: Empty can

Claims (1)

[Claims] 1. A groove-shaped pocket (3) extending vertically.
1) a cylindrical or arcuate filter screen having a corrugated cross-section having a plurality of inner periphery formed at a predetermined pitch, and a suction port (83, 9) having a predetermined width facing the pocket (31).
3) and the port seal (8
4, 94) and a hollow backwash arm (80, 90) which is rotated so as to face the inner circumference of the filter screen (30), and the dust trapped in each pocket (31) is filtered by the filter screen ( An automatic backwash strainer for backwashing the filter screen (30) by sucking it into the suction port (83, 93) of the backwash arm (80, 90) together with the treated water on the outer peripheral side of the filter screen. Along the inner circumference of (30), the inner edges (33) extend in the vertical direction at a predetermined interval from each other, and the inner edge (33) has port seals (84, 9) on both left and right sides of the suction port (83, 93).
4) a plurality of pairs of partition walls (3
2) are projected at a predetermined pitch, and each pair of partition walls (32, 3)
An automatic backwash strainer characterized in that a wide expansion pocket (34) communicating with the pocket (31) is formed between 2).