JPH11156114A - Parallel flow type cartridge filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop an unwoven cloth filter whose filtration flow rate and filtration life can freely be set and to provide a cartridge filter unnecessary to be combined with different types of filter materials and not requiring a troublesome process such as a heating process or an assembling process. SOLUTION: This cartridge filter comprises an overlaid body of a large number of filtration sheets 6 having a high density region in the permeated side and a lower density region in the supply side and filtration sheets 6 are closely stuck to one another in the high density region in the permeated side or installed through spacers 7. A liquid to be filtered flows in parallel from the supply side toward the permeated side along the filtration sheets 6. The density of the high density region can be adjusted by a fastening means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cartridge filter having a filter sheet which can be used in a wide range of fields such as the electronics industry, the food industry, the pharmaceutical industry, the cosmetics industry, and the automobile industry. The present invention relates to a cartridge filter having a filter sheet used for removal, injection, lotion, shampoo, alcoholic beverage, soft drink, and the like.

[0002]

2. Description of the Related Art Conventionally, many proposals have been made to use a nonwoven fabric as a filter.
Improvement proposals have been made to prevent clogging. For example, according to Japanese Patent Application Laid-Open No. 61-278319, a cartridge filter is proposed in which a cloth and a non-woven fabric having a basis weight of 100 to 650 g / m ² are spirally wound around a cylindrical core so that they alternately form layers. ing. According to Japanese Patent Application Laid-Open No. Sho 62-155912, the separation efficiency is not improved only by stacking a plurality of non-woven fabrics made of polypropylene. It is proposed to use a filter material that is integrated by passing through a heating roll. Furthermore, according to Japanese Patent Application Laid-Open No. 1-297113, a nonwoven fabric wound laminated cartridge filter formed by winding a plurality of nonwoven fabrics configured such that the average fiber diameter and the average pore diameter become larger as the outer side of the cylinder to be wound is increased. is suggesting.
Alternatively, according to JP-A-3-278810, 2
Cartridge filters have been proposed in which different types of nonwoven layers, ie, dense layers having smaller average pore sizes and diffusion layers having larger sizes are alternately present. However, in any of the proposals, complicated steps are required in the production, processing, and assembly of the nonwoven fabric, and auxiliary materials used simultaneously with the nonwoven fabric may be indispensable. It is necessary to have a variety of filters having various filtration performances corresponding to the requirements.

[0003]

Under the above-mentioned technical situation, it is possible to freely set a filtration flow rate and a filtration life as well as to trap a particle having a predetermined filtration performance, that is, a particle having a required minimum particle diameter. Aiming at the development of a nonwoven fabric filter to obtain the same, and in achieving such an object, a proposal of a cartridge filter which does not require cumbersome processing such as a combination of different types of filter media and heat treatment of the filter media as disclosed in the prior art and an assembling process. Was an issue.

[0004]

As a result of various investigations based on the above-mentioned problems, a force for compressing a substantially homogeneous low-density nonwoven fabric filtration sheet industrially produced with good reproducibility is applied to the nonwoven fabric filtration sheet to apply a density. The inventors of the present invention have conceived of making a change, that is, forming at least a high-density region and using this as a filter material to constitute a cartridge filter, and have completed the present invention. More specifically, as the diameter of the particles to be captured is smaller, the above-described compression force for capturing the particles is increased, and in order to secure a large filtration flow rate, the thickness of the nonwoven fabric filtration sheet is increased or the nonwoven fabric is taken as a nonwoven fabric. By increasing the number of superimposed filter sheets to increase the filtration area, the pre-filter effect of capturing large-diameter particles more upstream so that the high-density region functions exclusively for filtering the smallest particles to be captured. By providing the filter sheet length (flow path distance) up to the high-density area as much as possible, it is possible to convert the raw material, a nearly homogeneous low-density nonwoven fabric filter sheet, into a filter material with many functions as described above. The present invention has found that a cartridge filter equipped with this achieves a predetermined performance.

[0005] In other words, the filtration sheet has a high-density region on the permeate side and a low-density region on the upstream supply side in the filtration, and is preferably a multi-layered body thereof, at least the above-mentioned The present invention relates to a cartridge filter in which a filtration sheet is formed close to a high-density region, and a liquid to be filtered flows in parallel from the upstream supply side to the permeation side along the filtration sheet. Here, the substantially homogeneous low-density nonwoven fabric filtration sheet may be a commercially available nonwoven fabric whose use is indicated as a filter, medical hygiene material, clothing material, industrial material or agricultural material, and preferably does not depend on an adhesive. Those manufactured by heat fusion are preferred. As a specific production method, a melt blown method and a spun bond method can be said to be preferable methods. Normal commercial products are thin and have no problem in applying to the present application, but especially in the case of a thick nonwoven fabric, when the force is applied by the above-described compression, both ends are easily compressed in the thickness direction, but the central portion is Tends to be difficult to compress. Therefore, when uniform compression is desired, it is desirable to use thin nonwoven fabrics one on top of the other.

[0006] In the compression, usually, various types of pressing plates for holding the filter sheet are applied with a force via a supporting plate. In order to drive the support plate, a force may be applied by a spring to apply a compressive force other than by rotating the holding nut, and the method is not limited. The size of the holding plate may be a size enough to cover the area of the nonwoven fabric to which pressure is applied, and may be a size that covers the entire surface of the nonwoven fabric in some cases. In particular, when a density change or a gradient is imparted to the nonwoven fabric, it can be easily achieved by giving a depression, a curved surface, or a slope corresponding to the density change or the gradient to the side of the holding plate that is in contact with the nonwoven fabric. Thus, the most compressed sites are compressed to capture the particles of the required minimum particle size, and those that are not so compressed or those that are not compressed at all are dependent on the particle composition of the filtration material, as well as the pre-filter effect. Is expected and the degree and the length to be compressed are determined.

The above-mentioned nonwoven fabric filter sheet has a relatively small thickness, and in the use of the filter medium of the present invention for guiding a raw material flow substantially parallel to the surface of the filter sheet, the filtrate outlet surface is the side surface of the filter sheet and the area of the permeate side of the filter sheet surface, that is, It is difficult to ensure a large filtrate outflow area, and the filtrate exit area per sheet is generally small. Even if a filter sheet with a large thickness is selected, there is a limit in securing the area, and the adoption of a thick filter sheet makes it difficult to uniformly transmit the compressive force,
In order to increase the area on the permeation side, it is preferable to overlap the filter sheets. Further, if the permeate side when the filter sheets are overlapped and formed into a cylindrical shape is the center support cylinder side, the outer diameter of the support cylinder may be increased to secure the permeate side area. Of course, increasing the number of superimposed filter sheets is limited in terms of the propagation of compressive force, and should be appropriately selected in consideration of a desired filtering operation.

If the particle size distribution of the solids in the raw material to be filtered is narrow, the entire area may be a high-density region for capturing the particles over the entire length of the filter sheet. However, in the case of showing a wide distribution, the nonwoven fabric filter sheet located close to the supply side captures large-diameter solid particles and gradually captures small-diameter solid particles toward the permeate side so that the filter sheet can function normally. The compression specification of the filtration sheet is determined so that the length of the high-density region and the length of the low-density region match the particle distribution in the target filtration material.

Thus, a cartridge filter is constructed by stacking the filter sheets in multiple stages, and the high-density region and the low-density region can be adjusted by the fastening means, and the filtration area can be increased as much as possible. Capture solids in order from the raw material side of the filtration sheet,
The idea is that the entire filter surface is used efficiently and efficiently to the filtrate side, and the filtration life is prolonged. Therefore, by applying the permeation side tightening force of the superimposed body of the filter sheets to form a cartridge filter having a dense / dense structure, the liquid is caused to flow in a direction parallel to the filter sheet, and the entire filter sheet is effectively used. It is an object of the present invention to provide a cartridge filter in which a required filtration flow rate and a required capture rate can be freely obtained and filtration efficiency and filtration life are improved.

[0010]

More specifically, the present invention relates to a stack of a number of filtration sheets having a high-density region on the permeate side and a low-density region on the supply side, wherein Provided is a cartridge filter in which a liquid to be filtered is formed in close contact with a filter sheet in a high-density region and flows in parallel from the supply side along the filter sheet toward the permeation side. Here, the high-density region is desirably formed by providing a fastening means to the cartridge filter, but also includes a filter sheet having a high-density region formed before or after stacking the filter sheets.

In this case, if one or more spacer sheets are interposed in the high-density region, it becomes easy to form a high-density region by applying a tightening force, and the overall shape of the cartridge filter can be shaped. It will be easier. In the high-density area, a plurality of filter sheets having the same density stacked in a plurality of layers are preferably clamped by a clamping means. In order to adjust the filtration performance as desired, preferably the tightening means is adjustable.

In a usual case, the cartridge filter is formed in a cylindrical shape, and the supply side of the solid-liquid mixture (stock solution) to be filtered is on the outside, the permeate side is on the inside, and the permeate side has porosity. A central support cylinder is provided, and an airtight outer cylinder having a supply port for the liquid to be filtered is provided on the supply side. In some cases, the cartridge filter may be formed in a cylindrical shape, with the transmission side on the outside and the supply side on the inside. In some cases, the cartridge filter is formed in a rectangular parallelepiped shape,
The transmission side and the supply side may be provided in parallel with each other.

The present invention also relates to a method for manufacturing these novel cartridge filters, wherein a plurality of filter sheets are stacked and a high-density region is formed by applying a clamping force to the permeation side. Provide a way. In this case, a plurality of filtration sheets and one or more spacer sheets provided on the permeation side are stacked,
By applying a tightening force to one side of the spacer sheet to form a high-density region, the tightening force can be easily applied, and the overall shape of the cartridge filter can be easily formed.

According to the above structure of the present invention, particles having a size larger than a target particle size are filtered and separated, and in a low-density region up to a high-density region, the filter functions as a pre-filter. Since the filtration area is provided, the filtration area per unit volume can be remarkably improved. For example, an extremely large film area can be obtained as compared with a conventional pleated structure, and a long life can be achieved.

In the present invention, a cartridge filter having a large effective filtration area can be constructed by stacking filter sheets of any thickness (from thin to thick) in multiple stages. When a thick filter sheet is used, a slit may be formed in the outer peripheral portion. Also, in order to secure a wider filtration area, it is possible to obtain an appropriate superimposed height by compressing it and repeatedly laminating it. It is easy to manufacture a cartridge filter as long as 20 inches (50 cm) or 30 inches (75 cm).

Examples of the material of the filter sheet used in the present invention include natural materials such as cotton, wool and paper; synthetic fibers such as fluororesin, nylon, polyester, polypropylene, aramid and acrylic; and regenerated fibers such as rayon. Sheets woven or non-woven from metal fibers such as stainless steel, glass, carbon, alumina, inorganic fibers such as silica, etc.
Further, a continuous porous sheet made of a polymer resin such as rubber, urethane, and acrylic can be used. The average fiber diameter of the nonwoven fabric can be 10 to 500 μm, and the thickness can be about 0.1 mm to several cm. The average pore diameter is selected according to the purpose.

The shape of the cartridge filter can be any shape other than the columnar shape. For example, a square, rectangular, elliptical, or any other free-form filter sheet can be stacked. Also, the size of the filter sheet can be freely changed from a small one to a large one.

By gradually increasing the cross-sectional shape of the spacer (wedge shape) toward the inside of the cartridge (toward the filter sheet core), a density gradient is further imparted to the filter sheet, so that fine particles having different particle diameters are more likely to be present in the liquid to be filtered. It is also possible to efficiently capture. The outer diameter of the spacer can be freely changed from a small one to the same as the outer diameter of the filter sheet, and can be set according to the particle size distribution.

Next, as a method of manufacturing a cartridge,
The cartridge can be easily manufactured by stacking and stacking the filter sheets, then tightening the required amount, and welding and fixing only the upper and lower portions or welding and fixing. It is also possible to put packings on the upper and lower sides and fix them using bolts and nuts. The plastic material of the inner cylinder of the cartridge filter and the fastening means is PE, PP,
Although all resins such as PTFE, PFA, FEP, and ECTFE are possible, it is preferable to select a material having the same material as the filtration sheet and having a small amount of extract.

The cartridge filter of the present invention can be manufactured as a single unit or as a disposable filter assembly. Further, a cartridge filter in which only the content of the filtration sheet is replaceable is also possible. Further, the punched filter sheet can be mounted on a jig that can freely control the tightening force, and can be used as a replaceable cartridge capable of producing simple and free filter sheet characteristics that can be assembled.

[0021]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a cartridge filter according to a preferred embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an inner cylinder provided on the permeation side, which has a permeated liquid outlet 12 which is closed at the bottom and opened at the top. A seal ring 5 is provided around the upper end of the inner cylinder 1 to enable airtight connection to an outer cylinder (not shown) and other mounting locations. A plurality of elongated openings 11 are formed around the inner cylinder 1 at equal intervals in the circumferential direction. An outer thread is cut on the outer periphery of the lower portion of the inner cylinder 1, and the support plate 3 and the holding nut 4 are fixed to the lower end of the inner cylinder by the inner screws, and are sealed by a seal ring 2. Near the upper end of the inner cylinder 1, a flange 13 projects horizontally. On the lower surface of the flange 13 and on the upper surface of the support plate 3, annular pressing plates (packing) 8, 8 are provided, respectively.

Around the portion having the opening 11 of the inner cylinder 1, there are arranged a plurality of filter sheets 6 of the same shape which are stacked in multiple stages and which are constructed according to the present invention. Although several filter sheets are exaggeratedly drawn in the figure for easy understanding, many thin filter sheets are actually used. On the side of the filter sheet 6 which is in contact with the inner cylinder, there is provided a thin annular spacer 7 made of the same material or a different material as the filter sheet. The spacers 7 are provided alternately with the filter sheets 6. The filter sheet 6 is compressed by the spacer 7 to form a high-density region on the side in contact with the inner cylinder. In such a high-density region, the filtration sheet having the high-density region may be alternately stacked around the inner cylinder together with the spacer, and then the support plate 3 and the lock nut 4 may be tightened to make the filtration sheet and the spacer adhere to each other. Preferably, the filter sheet is formed by stacking a filter sheet having a constant density and thickness together with the spacer around the inner cylinder, and then tightening the support plate 3 and the lock nut 4 until the required density is obtained. When the tightening is completed, the inner cylinder and the lock nut 4 are fixed by welding or the like. The number of spacers used is appropriately adjusted. Without spacers, the high-density area is greatly dented,
It is necessary to devise the shape and the like of the presser plates (packing) 8, and the use of spacers eliminates the necessity and is convenient for freely adjusting the tightening force.

FIG. 2 shows a filter sheet 6 having a density gradient by gradually increasing the cross-sectional shape (wedge shape) of the spacer 7 toward the inside of the cartridge (inner cylinder side).
The fine particles having different particle diameters are more efficiently captured by the liquid to be filtered by tightening the holding plates 8 and 8 as described above.

FIG. 4 shows another structure for superimposing the filter sheets 6 in multiple stages and further laminating them, just before tightening. In this example, one spacer 7 is used for each of a plurality of filtration sheets.

Next, the operation of the cartridge filter of the present invention will be described with reference to FIG. The undiluted solution flows from the outer periphery of the filter sheet to the inner cylinder along the surface of the filter sheet. During this time, the solids in the stock solution are captured on the surface of the filter sheet or inside the filter sheet. The liquid then flows through the constricted high-density area in the direction of the face of the filter sheet to the inner cylinder. As is apparent from the figure, the liquid has a long passage along the surface of the filter sheet, so that the liquid is trapped in the filter sheet in order from coarse particles, and fine particles are trapped in the high-density region. Thus, the effective filtration area of the cartridge filter of the present invention is increased, and the capture of solids is improved.

Next, modified examples of the present invention will be described. 5 and 6 show modifications of the present invention. FIG. 5 shows a cylindrical cartridge filter in which the supply side is on the inside, the transmission side is on the outside, a spacer is provided on the transmission side, and a high-density region is provided on the transmission side. FIG. 4 is a cross-sectional view of a cartridge filter having a. FIG. 6 is a sectional view of a rectangular parallelepiped cartridge of a type in which rectangular filter sheets are stacked and which has a high-density region on the transmission side.

Example 1 An average fiber diameter of 5 μm, an average pore diameter of 60 μm, and a basis weight of 8 produced by a melt blown method.
Capture efficiency and filtration life of a cartridge filtration sheet obtained by superimposing 7 sheets of non-woven fabric of 0 g / m ² , using hard rubber sheets for upper and lower holding plates (packing), and compressing the inside of the filtration sheet (core side) Was measured and shown in the graph. Here, seven disc-shaped nonwoven fabrics having an inner diameter of 25 mm, an outer diameter of 63 mm and a thickness of 0.80 mm were overlapped and tightened. Three types of cartridge filters having a compression ratio of 30%, 40% and 50% were constructed and subjected to a filtration test. The stock solution was 11 kinds of JISZ8901 test dust, 150P concentration.
The one having the composition of PM was used. The pressure difference (differential pressure) before and after filtration at this time was set to 5.5 × 10 ⁴ Pa. Here, the tightening compression ratio is the filtering sheet before applying the tightening pressure, subtracting the superimposed thickness of the entire filter sheet after applying the tightening pressure from the superimposed thickness of the entire filter sheet before applying the tightening pressure. It is defined as a percentage divided by the overall superimposed thickness. FIG. 7 shows the relationship between the cumulative filtration amount and the trapping ratio. It can be seen that the trapping ratio increases as the filter tightening force (tightening compression ratio) increases for the same cumulative filtration amount. Further, after the measurement was completed, the cartridge filter was disassembled and observed. As a result, it was found that particles were trapped on the surface and the inside of the filter sheet, and that the entire filter sheet exhibited a filtering function.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a cartridge filter according to a preferred embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state before tightening of a filter sheet and a spacer according to another example constituting the cartridge filter of the present invention.

FIG. 3 is a cross-sectional view showing a state after fastening a filter sheet and a spacer according to another example of the cartridge filter of the present invention.

FIG. 4 is a cross-sectional view showing a state before tightening of a filter sheet and a spacer according to still another example of the cartridge filter of the present invention.

FIG. 5 is a cross-sectional view showing a cartridge filter according to the present invention in which the transmission side is on the outside.

FIG. 6 is a sectional view showing a rectangular parallelepiped cartridge filter assembly of the present invention.

FIG. 7 shows the relationship between the cumulative filtration amount and the capture rate of the cartridge filter of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Inner cylinder 11 Opening 12 Permeate outlet 13 Flange 2 Seal ring 3 Support plate 4 Holding nut 5 Seal ring 6 Filtration sheet 7 Spacer 8 Holding plate (packing)

Claims (10)

[Claims] 1. A stacked body of a number of filtration sheets having a high-density region on a permeation side and a low-density region on a supply side, wherein the filtration sheets are formed in close contact with the high-density region on the permeation side. A cartridge filter in which a liquid to be filtered flows in parallel from the supply side to the permeation side along the filtration sheet. 2. A stacked body of a number of filtration sheets having a high-density region on a permeate side and a low-density region on a supply side, wherein one or more spacer sheets are interposed in the high-density region on the permeate side. A cartridge filter, wherein the liquid to be filtered flows in parallel from the supply side toward the permeation side along the filtration sheet, wherein the filtration sheet is formed in close contact with the filtration sheet. 3. A superposed body of a large number of filtration sheets that forms a density gradient from a high-density region to a low-density region in a stepless manner from a permeation side to a supply side, wherein Whether the filter sheet is formed more closely,
In the high-density region on the permeation side, a filtration sheet is formed more closely with one or more spacer sheets interposed therebetween, and the liquid to be filtered is transmitted from the supply side along the filtration sheet along the permeation side. Cartridge filter flowing parallel to. 4. A superposed body of a number of filtration sheets that forms a density gradient from a high-density region to a low-density region in a stepless manner from the permeation side to the middle of the supply side. The filtration sheet is formed more closely in the region, or the filtration sheet is formed more closely in the high-density region on the transmission side with one or more spacer sheets interposed therebetween. A cartridge filter in which liquid to be flowed from said supply side parallel to said permeate side along said filter sheet. 5. The cartridge filter according to claim 1, further comprising fastening means for forming said filter sheet having said high-density region from filter sheets of the same density. 6. The tightening means is adjustable.
Cartridge filter. 7. The supply side is on the outside, the permeation side is on the inside, the permeation side is provided with a porous central support cylinder, and the supply side is provided with an airtight outer cylinder having a supply port for the liquid to be filtered. A cartridge filter according to any one of claims 1 to 6. 8. The cartridge filter according to claim 1, wherein the permeate side is on the outside and the supply side is on the inside. 9. A method for manufacturing a cartridge filter, comprising stacking a plurality of filter sheets and applying a tightening force to form a density gradient or a high-density region. 10. A method of manufacturing a cartridge filter, comprising stacking a plurality of filter sheets and one or more spacer sheets, and applying a clamping force to the entire surface of the spacer sheet to form a density gradient or a high-density region. .