JP2001137628A - Filter medium of filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To micronize the opening of a screen and to provide a strong filter medium by combining several kinds of mesh screens having a different mesh opening, with respect to a metallic filter medium used in a filter. SOLUTION: A plurality of metallic mesh screens 2, 3 and 4 are successively placed on a supporting plate 1 having many slit through-holes 1a each having a wedge-shaped section, and the opening of the respective screens 2, 3 and 4 is made smaller than that of the one below. The coarse-mesh screen 2 is laid on the supporting plate 1, the medium-mesh screen 3 is laid thereon as the intermediate layer, and the fine-mesh screen 4 is laid thereon as a surface layer to constitute a filter medium to be used. Consequently, microfiltration is realized, and the strength of the medium is also increased. Since the screen mesh opening of the metallic screen is made gradually larger downward, the filtrate passed through the medium of the surface layer is excellently discharged. Further, as the filter medium is metallic, the medium is easily cleaned, and the medium reinforced by the lamination is never deformed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal filter medium used for a filter, and more particularly to a filter medium for a filter in which a filter is combined to form a fine screen.

[0002]

2. Description of the Related Art It is well known that a filter cloth is used as a filter material in a filter press or a vacuum dehydrator. As a filter medium used for the filter press, a filter medium in which a metal mesh is laid on a filter bed of a filter plate with punched metal has been proposed by, for example, Japanese Utility Model Registration No. 2527922.

[0003]

However, in the case of using the filter cloth as the conventional filter medium, the cake attached to the filter cloth is difficult to peel off, and it is difficult to remove the cake of the clogged filter cloth. there were. For this purpose, a filter cloth used for a filter press or a vacuum dehydrator is run or vibrated in order to peel the cake. Then, the filter cloth is soft, and it is difficult to return the clogged and deformed filter cloth to its original shape, causing wrinkling. Further, in the filter medium using a metal mesh, the cake has good releasability. However, in the case of concentrated sludge such as sewage sludge, when the mesh of the screen is about 1 m / mφ, the particles are not easily removed from the mesh of the screen. 70% recovery rate
It is extremely bad at -80%, and in order to increase the recovery rate, the eyes are easily clogged when the eyes are made small, and there is a possibility that the eyes may be damaged when high pressure is applied. The present invention provides a filter medium having a fine mesh and a strong filter medium by combining several types of mesh screens having different filtration meshes.

[0004]

The gist of the present invention is that a plurality of metal mesh screens are superposed on a support plate having a large number of through holes, and the superimposed screen has a finer mesh as the upper surface layer. The screen is made finer by laminating filter media, the filter media strength is increased, and the screen mesh is sequentially made finer to facilitate backwashing. Specifically, a coarse screen is laid on the support plate as a slit having a wedge-shaped cross-sectional area in the through hole of the support plate. The fine screen is stretched, and the medium screen interposed in the intermediate layer may be used as the fine screen, or the coarse screen laid on the support plate may be used as the medium screen.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus according to the present invention is constructed as described above. The screen of the present invention has a finer screen than a conventional metal screen, and captures small particles to increase the recovery rate. Can be. Then, a plurality of metal screens supported by the support plate are superimposed to withstand a high pressure and can cope with a high dehydration operation. When the metal screen is clogged and washed, backwashing with high-pressure water or compressed air from the back surface of the filtering surface can remove the clogged material from the metal screen having good releasability.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The filter medium of the filter according to the present invention will be described in detail with reference to the drawings. First, in FIG. 1, reference numeral 1 denotes a support plate, and the cross section of the support plate 1 expands from the top surface to the bottom surface. Have a large number of open wedge-shaped through-holes 1a, and the through-holes 1a have a slit shape when viewed from a plane. A plurality of metal screens are stretched on the support plate 1, and a coarse screen 2 is laid on the upper surface of the support plate 1. The fine screen 4 is stretched. Then, by combining screens having different hole diameters, the mesh of the filter medium becomes finer, and the filter medium strength is complemented by overlapping the filter media.
If the support plate 1 has insufficient strength, it may be reinforced with a punching metal 5.

When the particles of the target undiluted solution are fine, as shown in FIG. 2, if the fine mesh screen 3 interposed in the intermediate layer is replaced with the fine mesh screen 4, the size of the combined filter media becomes smaller and fine filtration can be performed. Things. Then, when the combined filter media is clogged, the metal mesh screens 2, 3, and 4 are excellent in releasability by backwashing the back surface of the support plate 1 of the filter media laminated with air or water. Clogged clogs can be easily washed away. The coarse screen 2 laid on the support plate 1 may be used as the middle screen 3. The mesh size of these screens can be changed according to the difficulty of filtration of the target stock solution or the particle size of the solid material. 0.5 mm, the middle screen 3 of the upper intermediate layer has a range of 100 μm to 1.0 mm, and the fine screen 4 of the surface layer has a range of 20 μm to 0.5 mm. What is necessary is just to combine a metal mesh.

[0008]

As described above, according to the filter medium of the present invention, a plurality of metal mesh screens are superposed on a support plate having a large number of through holes, and a screen having a finer mesh as the upper surface layer is superposed. Therefore, as compared with a filter medium using a conventional metal screen alone, by overlapping the filter medium, the mesh of the screen becomes finer, precision filtration becomes possible, and the filter medium strength is increased. And, since the mesh of the screen becomes larger in the lower layer of the metal screen, the filtrate passing through the filter medium of the surface layer is discharged well. Also,
Conventional clogged filter cloths are difficult to wash, and soft filter cloths are deformed in shape.However, since the filter medium of the present invention is a metal screen, it is easy to clean and is reinforced by laying. The filter medium does not deform.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view showing a metal screen on which a filter medium of a filter according to the present invention is superposed.

FIG. 2 is a longitudinal sectional side view showing another embodiment of the filter medium according to the present invention.

FIG. 3 is a vertical sectional side view showing another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Support plate 1a Through-hole 2 Rough screen 3 Medium screen 4 Fine screen

Claims (5)

[Claims] 1. A plurality of metallic mesh screens (2, 2) are provided on a support plate (1) having a large number of through holes (1a ...).
Screens (2, 3, 4) on which layers 3 and 4) are stacked
A filter medium for a filter, characterized in that the eyes of the filter are made finer as the upper layer. 2. The superposed mesh screen is constructed by laying a coarse screen (2) on a support plate (1), interposing a middle screen (3) on an intermediate layer above the mesh screen, and forming a surface layer on the intermediate layer. 2. A filter medium for a filter according to claim 1, wherein a fine screen (4) is stretched. 3. The filter medium for a filter according to claim 2, wherein the intermediate screen (3) interposed in the intermediate layer is a fine screen (4). 4. The filter medium according to claim 2, wherein the coarse screen (2) laid on the support plate (1) is a medium screen (3). 5. The filter medium according to claim 1, wherein the through hole (1a) of the support plate (1) is a slit having a wedge-shaped cross-sectional area.