JP2005118746A - Lateral flow type moving bed type filtration device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the anti-clogging performance of a lateral flow type moving bed type filtration device. <P>SOLUTION: A water catchment strainer (4) comprises two steps consisting of a high-aperture-ratio strainer (4a) and a flow regulating plate (4b). The high-aperture-ratio strainer (4a) is a wedge wire screen (S) with a slit-shaped opening set in the vertical direction, and has a high aperture ratio of 4% or more. The flow regulating plate (4b) is a sieve plate (M) perforated with small holes (h) spaced at regular intervals and has a smaller aperture ratio than that of the high-aperture-ratio strainer (4a). Thereby, clogging can be controlled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cross-flow type moving bed filtration device, and more particularly, to a cross-flow type moving bed filtration device that can suppress clogging of a water collection strainer due to a filter medium and can greatly extend the time until the water collection strainer is blocked. .

  Conventionally, a filter tank in which the filter medium for adhering and capturing turbid components in the raw water is deposited at the bottom, an inflow chamber installed on the lower side wall of the filter tank to supply the raw water to the filter tank, and the opposite side of the inflow chamber There is known a cross-flow type moving bed filtration device having an outflow chamber for discharging treated water through a water collection strainer, which is installed on the lower side wall of the filtration tank (see, for example, Patent Documents 1 to 3). .

Special Table 2000-516135 JP 2002-331205 A JP 2003-053110 A

In the conventional cross-flow type moving bed type filtration apparatus, a nozzle type strainer 500 as shown in FIG. 7 is used as a water collection strainer.
The nozzle strainer 500 is a circle having a diameter of 70 mm, and has 36 slits radially having a width of 0.35 mm and a length of 10 mm.
However, when the fine particle component of the filter medium enters the slit 501 of the nozzle strainer 500 and clogs during use, the accumulation of the filter medium and the turbid component in the vicinity proceeds, and finally There was a problem that the water collection strainer was clogged and filtration could not be continued.
Therefore, an object of the present invention is to provide a cross-flow type moving bed type filtration device that can suppress clogging of the water collection strainer due to the filter medium and can significantly extend the time until the water collection strainer is blocked.

In the first aspect, the present invention provides a filter tank (1) in which a filter medium (10) for adhering and capturing turbid components in raw water is deposited in the lower part, and a raw water installed on the lower side wall of the filter tank (1). The inflow chamber (2) for supplying water to the filtration tank (1) and the lower side wall of the filtration tank (1) on the opposite side of the inflow chamber (2) receive treated water via a water collection strainer (4). A cross-flow type moving bed type filtration device having an outflow chamber (3) for discharging, wherein the water collection strainer (4) comprises a large aperture ratio strainer (4a) having an aperture ratio of 4% or more, a small hole ( h) is provided in a regular arrangement, and the flow rate plate (4b) having an opening ratio smaller than the large opening ratio strainer (4a) is provided. .
In the above configuration, the “aperture ratio” refers to the ratio of the total area of all the openings to the area of the polygon having the smallest area and including all the openings and having an inner angle of 180 ° or less.
In the cross-flow type moving bed type filtration device (100) according to the first aspect, the water collection strainer (4) has at least two stages of a large aperture ratio strainer (4a) and a current plate (4b). Then, the aperture ratio of the large aperture ratio strainer (4a) is increased to 4% or more. Thereby, time until clogging progresses and a water collection strainer (4) obstruct | occludes can be extended. However, if the aperture ratio of the water collection strainer (4) is simply increased, the filtered water will not flow evenly, so a rectifying plate (4b) having a small aperture ratio and a rectifying action is provided. Thereby, filtrate water comes to flow uniformly.
According to the experiment by the present inventor, the aperture ratio of the large aperture ratio strainer (4a) is preferably 6% to 19%, and the aperture ratio of the rectifying plate (4b) is preferably 0.6% to 1.4%. I found out.

In a second aspect, the present invention relates to a cross-flow type moving bed filtration device (100) having the above-described configuration, wherein the large aperture ratio strainer (4a) is a wedge wire screen (S). A moving bed filtration device (100) is provided.
In the cross-flow type moving bed filtration apparatus (100) according to the second aspect, clogging is less likely to occur due to the cross-sectional shape of the wedge wire screen (S).

In a third aspect, the present invention provides a cross-flow type moving bed characterized in that the slit-like opening of the wedge wire screen (S) is directed in the vertical direction in the cross-flow type moving bed type filtering device (100) having the above-described configuration. A floor filtration apparatus (100) is provided.
In the cross-flow type moving bed type filtration device (100) according to the third aspect, since it is a slit-like opening that is long in the vertical direction, the filter medium (10) and turbidity coincide with the direction of movement due to gravity, thereby reducing the probability of clogging. I can do it.

In a fourth aspect, the present invention relates to an upstream side surface (Sa) of the large aperture ratio strainer (4a) and an inner wall surface of the filtration tank (1) in the cross-flow type moving bed type filtration device (100) configured as described above. Provided is a cross-flow type moving bed filtration device (100) characterized in that there is no step between them.
In the cross-flow type moving bed filtration device (100) according to the fourth aspect, there is no step between the upstream side surface (Sa) of the large aperture ratio strainer (4a) and the inner wall surface of the filtration tank (1). 10) and turbidity move smoothly and clogging is less likely to occur.

  According to the lateral flow type moving bed type filtration device (100) of the present invention, clogging of the water collection strainer (4) by the filter medium (10) can be suppressed, and the time until the water collection strainer (4) is blocked is greatly extended. it can.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is a diagram illustrating the configuration of a cross-flow type moving bed filtration apparatus 100 according to the first embodiment.
This cross-flow type moving bed type filtration apparatus 100 includes a filter tank 1 in which a filter medium (sand) 10 is deposited in the lower part, an inflow chamber 2 installed on the lower side wall of the filter tank 1, and raw water flowing in from the inflow chamber 2. An outflow chamber 3 installed on the opposite side wall of the inflow chamber 2 so as to flow out after passing through 10, a treated water control valve 5 for adjusting the amount of treated water discharged from the outflow chamber 3, and a filtration tank 1 An air lift pump 6 and an air lift pipe 7 for conveying the filter medium 10 near the bottom of the filter together with water to the filter medium cleaner 20 with compressed air, an air control valve 8 for adjusting the amount of compressed air supplied to the air lift pump 6, and a filtration tank A filter medium washer 20 that separates the compressed air, water, and the filter medium 10 that have been installed and transported, and exhausts the compressed air, drains the water, and drops the filter medium 10. A water level gauge 30 for measuring the water level WL, and and a control unit 40 for controlling the operation of the lateral flow moving bed filtration system 100 is constituted.

  The filtration tank 1 has a rectangular cylindrical shape. In order to make it easy to collect the filter medium 10 with the air lift pump 6, the bottom of the filtration tank 1 is tapered.

  Compressed air is supplied to the air lift pump 6 via the air adjustment valve 8. The compressed air moves up the air lift pipe 7 and is exhausted from the filter medium cleaner 20. Water is sucked into the air lift pump 6 so as to be caught in the flow of compressed air, and drained from the filter medium cleaner 20. Then, the filter medium 10 is sucked into the air lift pump 6 so as to be caught in the flow of water, and is conveyed to the filter medium cleaner 20.

  The filter medium cleaner 20 includes an outer cylinder 21, an inner cylinder 22 installed inside the outer cylinder 21, and a cleaning drain pipe 23 that communicates from the inner cylinder 22 to the outside.

  The raw water is widely distributed to the filter medium 10 by the inflow chamber 2, flows laterally through the filter medium 10, and flows out to the outflow chamber 3 through the water collection strainer 4. During this time, the raw water is filtered. The treated water that has flowed out to the outflow chamber 3 flows out to the treated water tank (not shown) through the treated water control valve 5.

  The filter medium 10 at the lower part of the filter tank 1 is conveyed to the filter medium cleaner 20 by the air lift pump 6 and the air lift pipe 7 and falls from the filter medium cleaner 20 to the upper surface of the filter medium 10 deposited at the lower part of the filter tank 1. During this time, the turbid component adhering to the filter medium 10 is peeled off from the filter medium 10. Then, the water mixed with the separated turbid component flows from the orifice 24 into the cleaning drain pipe 23 due to overflow, and is drained.

  The filter medium 10 that has fallen from the filter medium cleaner 20 accumulates in a mountain shape having the apex directly below it. The fallen filter medium 10 rolls on the slope of this mountain, but the filter medium 10 having a larger particle diameter rolls farther. Since the filter medium washer 20 is installed closer to the outflow chamber 3 than the inflow chamber 2, the particle diameter of the filter medium is larger near the inflow chamber 2, and the particle diameter of the filter medium 10 becomes smaller toward the outflow chamber 3. A distribution preferable for filtration in which the particle size of the filter medium 10 is slightly increased in the immediate vicinity of the chamber 3 is naturally formed.

FIG. 2 is a perspective view showing the water collection strainer 4.
The water collection strainer 4 includes a large aperture ratio strainer 4a having an aperture ratio of 4% or more, and a rectifying plate 4b in which small holes h are formed in a regular arrangement and the aperture ratio is smaller than that of the large aperture ratio strainer 4a. The distance between the large aperture ratio strainer 4a and the current plate 4b is 30 mm.

The large aperture ratio strainer 4a is a wedge wire screen S in which slit-like openings are installed in the vertical direction.
The wedge wire screen S has a structure in which 350 wedge wires having a length of 1 m and a width of 2.5 mm are arranged with an opening width of 0.35 mm.
The opening area is (350-1) slit × 1 m × 0.35 mm = 122150 square mm.
The polygonal area including all the openings and having an inner angle of 180 ° or less and the smallest area is (350-2) × 1 m × 2.5 mm + (350-1) slit × 1 m × 0.35 mm = 992150 Square mm.
Therefore, the aperture ratio is 100 × 122150 / 992150≈12.3%.

The rectifying plate 4b is a plastic perforated plate M in which 7 × 7 = 49 small holes h having a radius of 7.5 mm are formed at a pitch of 150 mm.
The opening area is 49 × 7.5 mm × 7.5 mm × 3.14 = 8654.6 square mm.
The area of the polygon that includes all the openings and has an inner angle of 180 ° or less and the smallest area is {150 mm × (7-1) rows + 15 mm} × {150 mm × (7-1) rows + 15 mm} = 83225 square. mm.
Therefore, the aperture ratio is 100 × 8654.6 / 83225225≈1.0%.

  As shown in FIG. 3, there is no step between the upstream side surface Sa of the large aperture ratio strainer 4 a and the inner wall surface 1 s of the filtration tank 1.

[Experimental Example 1]
Injecting 5 mg / L of polyaluminum chloride as a flocculant into river water with an average turbidity of 10 degrees and stirring and mixing with a line mixer as raw water, the cross-flow type moving bed filtration device 100 of Example 1 and the conventional cross-flow type A filtration experiment was carried out for 2 months using a moving bed type filtration device, and the change with time of the differential pressure between the water pressure in the inflow chamber 2 and the water pressure in the outflow chamber 3 was measured. For the filter medium 10, silica sand having an effective diameter of 1.5 mm and a uniformity coefficient of 1.4 was used, and the filtration rate was 240 m / day.
As can be seen from the results shown in FIG. 4, in the cross-flow type moving bed filtration apparatus 100 of Example 1, the differential pressure hardly increases (circled graph), and clogging is suppressed. On the other hand, in the conventional cross-flow type moving bed type filtration device, the differential pressure increases (triangle point graph), and clogging progresses.

In addition, the water collection strainer in the conventional cross-flow type moving bed type filtration apparatus has a structure in which 8 × 8 = 64 nozzle strainers 500 are arranged at a pitch of 130 mm. One nozzle type strainer 500 is a mushroom shape having a maximum diameter of 70 mm, and 36 slits having a width of 0.35 mm and a length of 10 mm are radially bored along the circumference inside the circumference of a diameter of 54 mm. It is a structure.
The opening area is 64 × 36 × 0.35 mm × 10 mm = 8064 square mm.
The polygonal area including all the openings and having an inner angle of 180 ° or less and the smallest area is {130 mm × (8-1) rows + 54 mm} × {130 mm × (8-1) rows + 54 mm} = 929296 squares. mm.
Therefore, the aperture ratio is 100 × 8064 / 929296≈0.9%.

[Experiment 2]
The right half of the large aperture ratio strainer 4a in FIG. 2 is changed to a wedge wire screen with the slit-shaped opening oriented in the horizontal direction, and the same raw water filtration experiment as [Experiment 1] is conducted for two months. The closed state of the half (vertical slit) and the right half (horizontal slit) were examined.
As can be seen from the results shown in FIG. 5, the slit-shaped opening may be directed in the horizontal direction, but the effect of suppressing the progress of clogging is greater when the slit-shaped opening is directed in the vertical direction.

[Experiment 3]
In the cross-flow type moving bed type filtration device 100 of Example 1, the opening ratio is changed from 3.4% to 18.9% by changing the wire width of the wedge wire without changing the opening width of the slit-like opening of the wedge wire screen S. Then, the same raw water filtration experiment as [Experiment 1] was conducted for 2 months, and the increase rate of the differential pressure was examined.
As can be seen from the results shown in FIG. 6, when the aperture ratio is 4% or more, the increase in the differential pressure can be suppressed to 5 cm or less (circled graph). On the other hand, in the conventional cross-flow type moving bed type filtration apparatus, the amount of increase in the differential pressure was 20 cm (triangle point graph).

  The cross-flow type moving bed type filtration apparatus of the present invention can be used in the field of water treatment for removing turbidity in raw water.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory view showing a cross-flow type moving bed type filtration apparatus according to a first embodiment. It is a perspective view which shows a water collection strainer. It is a horizontal sectional view showing a water collection strainer. It is an experimental result figure which shows the filtration performance of the crossflow type | mold moving bed type filtration apparatus which concerns on Example 1. FIG. It is an experimental result figure which shows the obstruction | occlusion state of the vertical direction slit and horizontal direction slit of a water collection strainer. It is an experimental result figure which shows the relationship between the aperture ratio of a water collection strainer, and filtration performance. It is the front view and sectional drawing which show the nozzle type strainer used for the conventional water collection strainer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filtration tank 1s Inner wall surface of a filtration tank 2 Inflow chamber 3 Outflow chamber 4 Catchment strainer 4a Large aperture ratio strainer 4b Current plate h Small hole M Porous plate S Wedge wire screen Sa Wedge wire screen upstream side 100 Cross-flow type movable bed type Filtration device

Claims (4)

  A filter tank (1) for adhering and capturing turbid components in the raw water is deposited in the lower part, and is installed on the lower side wall of the filter tank (1) to supply the raw water to the filter tank (1). An inflow chamber (2), and an outflow chamber (3) installed on the lower side wall of the filtration tank (1) on the opposite side of the inflow chamber (2) for discharging treated water through a water collection strainer (4) The water collection strainer (4) has a large aperture ratio strainer (4a) having an aperture ratio of 4% or more and small holes (h) arranged in a regular arrangement. A cross-flow type moving bed filtration device (100), comprising a flow straightening plate (4b) having an opening ratio smaller than the large opening ratio strainer (4a).   The cross-flow type moving bed type filtration apparatus (100) according to claim 1, wherein the large aperture ratio strainer (4a) is a wedge wire screen (S). ).   The crossflow type moving bed type filtration apparatus (100) according to claim 2, wherein the slit-like opening of the wedge wire screen (S) is directed in the vertical direction. .   The cross-flow type moving bed type filtration apparatus (100) according to any one of claims 1 to 3, wherein an upstream side surface (Sa) of the large aperture ratio strainer (4a) and an inner wall surface of the filtration tank (1) are provided. A cross-flow type moving bed type filtration apparatus (100) characterized in that there is no step between them.

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