FI61813B - SKIV- ELLER ROERFILTER FOER ATT AVSKILJA FASTA PARTIKLAR ELLER FOER ATT FOERDELA GAS I FINFOERDELADE BLAOSOR - Google Patents

Description

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1 J 'UTLÄGGN I NGSSKRI FT O I O i O

***? 3 ^ υ »c (45) Patent granted on 11 October 1982

Patent meddelat> * S v (51) Kv.ik3 / int.ci3 B 01 D 29/00, 29/10 SUOM I —FI N LAND (21) P * t «nttlhakemu * - Patentansökning 800170 (22) Hakemlapilvi— Ansöknlngsdag 21.01.80 (23) Initial cloud— Giltlghetsdag 21.01.80 (41) Become public - Blivit offentlig 22.07.8l

National Board of Patents and Registration (44) Date of deafening of Nihtivikiipino and others. - 30.0β. 82

Patent and registration authorities Ansökan utlagd och utl.skrlften publlcerad (32) (33) (31) Pyydetty etuoikeus — Begird prloritet (71) (72) Gustaf F.W. Cabell, Riitankuja 1-3 C 28, 008i * 0 Helsinki 8U,

Suomi-Finland (FI) (9h) Plate or tube filter for the separation of solid particles or the division of gas into fine bubbles

The invention relates to a filter for use in oxidizing wastewater in biological water treatment, to filter water-mixed oil, mining dust, electrically charged electrolytes (accumulator spacers). Usually difficult to filter for purposes where the risk of clogging is high.

As is known, the filters are very different and are made, for example, from the following materials: paper, fabric, fibers, metal meshes, open-cell plastics, etc.

Examples of plastic filters, especially polyethylene and polyurethane, are CU- [lat. 829305 wherein a sintering process has provided a filter that filters electrolytes. FR-pa exam no. No. 1333,963 makes cellourine open-celled by 11a cell walls. This creates a porous foam for use as a filter. Inviroteck Co. In the US method, the gas is mixed with the liquid by means of rotating impellers using γ-cavitation. Although this method does not cause clogging, the disadvantage of the method is that in wastewater treatment, dirt droplets fly into the environment for a long time as a fine mist, which is not hygienically recommended.

2,61817) According to the present invention, the filter is made of closed-cell foamed polyethylene cross-linked. The invention also does not exclude other closed cell elastic plastics or rubbers, such as polypropylene, polyvinyl chloride, urethane, styrene butadiene. However, closed-cell polyethylene has proven to be f) an expensive material.

The filter must have sufficient surface area to maximize its accumulation capacity. For this purpose, e.g. paper filters are often - as is known - corrected to increase the surface area. According to the present invention, the polyethylene foam sheet is not corrugated, but longitudinal cracks are cut side by side. This cut achieves a considerable increase in surface area and results in fine gaps in the filter.

The disadvantage of filters is usually that they clog easily, depending, of course, on the substance to be filtered, the oil and water content and so on. As a result, the pressure against the filter increases.

(If the filter is not cleaned or replaced now, it will tear, especially if there is no effective monitoring method. A broken filter can cause great damage, especially in industry.

According to the present invention, a filter can be made in which these disadvantages are eliminated. The characteristic features of the device according to the invention are given in the appended claims.

The invention is described in more detail in the drawings, which illustrate the operation of the filter.

Figure 1 shows a section of a PE foam sheet, in which, for example, the upper and lower edges are left uncut. This closed part acts as a seal. The cut according to the invention gives a seal.

Figure 2 shows a cut PE foam sheet stretched in a plane.

Figure 2a is bent tubularly into an arc.

Figure 3 shows how the cracks open as the pressure increases.

Figure k shows a tube filter with a protective net as filter gain.

Figure 3 shows, for example, a water aeration (oxidation) plate filter 3 61815

Figure 6 shows, for example, a water aeration (oxidation) plate filter which is cross-sectioned.

Figure 7 shows the formation of a bubble when compressed air is passed through a filter into the water

Figure 8 shows the mean pressure resistance in mm / H £ <3 / ^

According to Figure 1, a closed-cell polyethylene sheet cross-linked and cut in a certain way is bent into an arc or a tube or stretched in a plane. According to Figure 2, a filter is created which separates the solid particles or divides the gas into fine bubbles in the liquid.

The filter works according to the following principle:

The closed-cell closed-cell foam polyethylene sheet (1) bent in the longitudinal section, which is cut according to Fig. 1, is elastic and does not function as a filter without stretching. It is only when it is bent to a certain radius or stretched in a plane that small cracks appear in the plate: According to Figure 3, on a convex surface, larger cracks are reduced evenly towards the concave surface. The bending radius can thus be used to control the size of the cut slits. This only happens if the PE sheet is a suitable thickness of 55 mm. Because the PE foam board is a highly static material, it helps the particles to be filtered to stick to the surfaces of the slits and clean air (gas) can pass through: f oily substances are also absorbed on all surfaces of the board.

Therefore, since PE can absorb at least twice the amount of oil by its weight, the filter can also be used as an oil filter. Impurities in the oil also adhere very willingly to the surfaces of the PL foam board and only clean oil passes through the small cracks.

When enough filtrate has entered the cutting slits (2), the pressure starts to rise as in other filters, but according to the present invention - due to the elastic properties of the PE foam and the slit cutting according to Fig. J - these small narrow slits (2) automatically open just as much that the pressure equalizes and the filter continues to operate and no clogging occurs. The same happens if gas is introduced into the liquid as bubbles. Even if contaminants algae, etc. accumulate on the upper surface of the filter, the slits (2) open as needed. This feature can be used especially in wastewater treatment plants (oxidation) where clogging is a very difficult problem.

61613 In the filter according to the present invention, it cannot happen that air does not pass through the filter, because the gaps open as the pressure increases. The filter only operates at a slightly higher pressure than required by the hydrostatic pressure. Consequently, the energy savings are also considerable. In many cases, cheap compressed air fans can be used instead of air compressors.

The filter according to the invention also acts as an airborne sound absorbing agent. There are filtering sites where sound attenuation is necessary.

It is known that an open-cell plastic foam with a weight of 30 kg / m 2 and a Rayleigh number (rayl / cm) of 80-240 Rayl / d (d = thickness) has an optimal attenuation. The distance between the cut slits of the filter according to the present invention is stretched to just the appropriate optimal range of the Rayleigh number, whereby optimum sound attenuation is obtained. In this area, the filter acts as a fine filter.

The filter is also used by passing a gas, e.g., air in fine particle, into the water. The main object is biological water purification (oxidation) Fig. 7 shows the formation of a bubble when air is blown through the filter. Figure 5 shows a plate aerator. Figure 6 shows a disc aerator in which foam polyethylene is cross-cut, in this aerator a star pattern is formed due to the cut when the compressed air presses the plate aerator slightly convex. Excessive convexity due to upward pressure is prevented by a sparse copper mesh mounted on the plate. The copper mesh also prevents the growth of bacteria on the surface of the aerator.

The biggest problem with known aerators is clogging, due to bacteria, sedimentation, etc., impurities that are always present in wastewater.

As a filter (aerator) according to the present invention, this drawback has been eliminated due to the structure of the aerator. Due to the cut on the foam plate - either longitudinal or cross - section - and the elastic nature of the material, compressed air opens the cut slits just as much as the back pressure needs at any given time. As contaminants begin to accumulate on the aerator, the cracks open more and at the same time the contaminants adhering to it are removed. Once these have infiltrated, the back pressure decreases and the cracks decrease correspondingly again. Since the material according to the invention is elastic, it is possible to increase or decrease the gaps.

Claims (3)

5 61 81 3 A filter for separating difficult-to-filter substances with a high risk of clogging, characterized in that longitudinal slits (2) are cut in the closed porous, soft or semi-hard foam-polyethylene or similar e 1 as 1. O. sealing plate (1) or arc (3) if the plate is not tensioned. Under pressure, the slits (2) open and the microcracks act as filters. Filter according to Claim 1, characterized in that the straight or bent foam plate (1,3) with slots acts as a filter so that when the pressure increases inside or outside, the longitudinal slots (2) open automatically according to the pressure. Filter according to Claim 1.2, characterized in that the slits (2) can be reduced or enlarged by reducing or increasing the pressure.