GB2067087A

GB2067087A - A filter

Info

Publication number: GB2067087A
Application number: GB8100934A
Authority: GB
Original assignee: SWINNEY ENG
Current assignee: SWINNEY ENG
Priority date: 1980-01-14
Filing date: 1981-01-13
Publication date: 1981-07-22
Also published as: GB2067087B

Abstract

A filter has a plurality of cylindrical filter elements (3) supported over respective holes (14) in a stationary hollow supporting filter cage (4). The holes are arranged in axial rows and each row of filter elements (3) is held in position by a releasable clamping bar (6) or a pair of such bars (Fig. 6 not shown). In order to clean the filter elements a rotatable backwash pipe (2) is disposed axially and nozzles (16) in the pipe are arranged to register with each hole in succession to backwash the filter elements. <IMAGE>

Description

SPECIFICATION Automatic filter This invention relates to filters.

In our prior British Patent Specification No.

1091933 there is described and claimed a filter comprising a plurality of filter elements disposed exteriorly of a stationary hollow supporting member, a rotatable backwash pipe disposed axially of the member, ducts in the pipe arranged to register with apertures in the member and leading to the filter elements and means for intermittently rotating the backwash pipe so that ducts are brought into registration in turn with the apertures and are caused to dwell to permit the backwashing of the filter element in sequence. In that arrangement we preferred to include plate filters but an improvement in this design is to make the filter material such as wire mesh into small cylindrical filter elements which are disposed about the tube. This is a known method in itself but hitherto these filter elements have been screwed into place or each one retained by a circlip.

Thus the removal of all these elements is a slow process as there are typically 100 to 300 filter elements in a unit. Moreover, they are usually made of stainless steel, as is the tube into which they are screwed, making removal difficult and sometimes impossible.

An object of the present invention is to provide an improved filter.

According to the present invention there is provided a filter comprising a plurality of filter elements covering respective holes in a filter cage, and common releasable retaining means operative to hold the elements in position against displacement, or, on release, to allow simple removal of the elements from the cage.

More particularly the invention includes a filter comprising a plurality of filter elements supported exteriorly over holes in a hollow filter cage, a backwash pipe disposed axially of the filter cage, ducts in the pipe arranged to register with the holes in the filter cage, means for effecting relative rotation between the backwash pipe and the filter cage so that ducts are brought into registration in turn with the holes to permit backwashing of the filter elements, and at least one common releasable retainer member arranged, in a first position, to cooperate with the filter cage so as to hold the filter elements firmly over their respective holes and, in a second, released position, arranged to allow removal of the filter elements solely by manipulation of the filter elements themselves.

Preferably the filter elements are cylindrical, disposed over respective holes of a plurality of vertical rows of holes in a cylindrical filter cage. In one embodiment there is preferably a retainer member for each vertical row of holes comprising a retainer bar hinged to the filter cage. In another embodiment there are two bars for each row.

The invention will now be described by way of example with reference to the accompanying draw ings in which: Figure 1 is a side elevation of a preferred embodi ment of filter in accordance with the invention; Figure 2 is an enlarged view of the filter element mounting; Figure 3 shows an alternative arrangement; Figure 4 is a side elevation of a second preferred embodiment of filter in accordance with the inven tion; Figure 5 is a side elevation of a further embodi mentoffiltersimilartothatshown in figure 4; and Figures 6a and 6b show the claimping arrange ment of the embodiments of figures 4 and 5 in side elevation and plan respectively.

Referring to figures 1 and 2 a filter body has an inlet pipe 13 through which the liquid to be filtered normally flows. The inlet pipe communicates with the interior of a filter cage 4 having a plurality of holes 14 which define flow spaces for the liquid to be filtered. In each hole 14 is fixed a projecting portion of a filter element 3 of cylindrical shape having a wore mesh filter media. As an alternative each filter element may comprise any other filter media, for example, a perforated sheet, gauze or sintered material. Alternatively the element may be of a type containing loose filtering media such as sand, or activated carbon, suitably housed and disposed. The elements are arranged in a plurality of vertical rows as shown.

A liquid to be filtered flows into the filter by way of the pipe 13, as indicated by the arrowAthroughthe filter element and is discharged through the outlet pipe 15.

Axially of the filter cage 4 is a backwash pipe 2 having eight backwash ducts 16 which align in turn with each of the holes 14 when the backwash pipe is caused to rotate by means of a drive unit 17.

The present invention provides that the filter elements 3 are simply located in the holes 14 provided in the filter cage and not screwed or held in position by means of individual retaining rings. For filters providing fine filtration, for instance below 100 microns, sealing '0' rings will be provided about the projecting portion, as shown at 5, so as to seal against the inside of the respective opening.

As shown, particularly in figure 2, the filter elements 3 are retained by bars 6 hinged at 7 or otherwise located at the bottom and fixed in position against the filter elements 3 by means of a screw or screws 8 or other locking mechanism. These bars cover a vertical row or a number of rows and trap the filter elements 3 against the filter cage 4 preventing lateral or axial displacement. When the need occurs to clean or replace elements the top cover 9, which may be retained by swing bolts 10, is released and lifted, the bars 6 protecting the filter elements 3 against damage. When the cover is removed the bars can be released and hinged back to free all the filter elements which can then be immediately removed.

In the cases where low headroom precludes lifting The drawing(s) originally filed were informal and the print here reproduced is taken from a later filed formal copy.

of the cover or when lifting means is not available a cover plate 11 is provided which is bolted to the filter top cover 9 - see figure 3. When the retaining bolts 10 have been released the cover is raised slightly by screwing down the tap bolt 12 which lifts the cover off the sealing '0' ring and enables the cover to be progressively rotated. Leakage being prevented by the provision of a bolted cover 19 over the tap bolt.

In this arrangement the retaining bar 6 is bolted at each end rather than being hinged and aligned with the cover plate 11 when it is removed a vertical row or rows of filters 3 can be withdrawn and cleaned or renewed. In this way all the elements can be removed by progressive rotation of the filter cover 9.

In figure 4 a filter body 21 has an inlet pipe 22 through which liquid to be filtered normally flows.

The inlet pipe communicates with the interior of a filter cage 23 which has a plurality of holes 24 formed therein and arranged in vertical rows. The holes 24 define flow spaces for the liquid to be filtered and disposed over each hole 24 is a filter element 25 of cylindrical or other shape. The filter media is suitably a wire mesh filter media, as in the first embodiment, but may be any other suitable media.

In the first embodiment the filter elements project into the holes in the filter cage and are provided with an '0' ring seal which seals against the inside of the repective holes. However, in the second embodiment the filter elements 25 are simply located on the holes 24 suitably with an '0' ring seal 26 sealing about the mouth of the respective opening. This has the advantage that the filter elements 25 do not have to be so accurately dimensioned.

In order to hold the filter elements in position a plurality of bars 28 are provided which are secured to the filter cage 23 and which engage an annular shoulder 29 on each of the filter elements 25 in a vertical row. The bars 28 are secured to the filter cage 23 by nuts and bolts 30 and have spacers 31 to accommodate the curvature of the filter cage 23 as shown in figure 6b. Once the nuts and bolts 31 are tightened the bars 28 trap the filter elements 25 against the filter cage 23 preventing lateral or axial displacement.

A liquid to be filtered flows into the filter by way of the pipe 22, as indicated by the arrow, passes through the filter elements 25, and is discharged through an outlet pipe 32. Disposed axially of the filter cage is a backwash pipe 33 having backwash ducts 34 which align to turn with each of the holes 24 when the backwash pipe 33 is caused to rotate by means of drive unit 35.

The embodiment of figure 5 is substantially the same as that shown in figure 4 except that the drive unit 35 is positioned on top and the inlet and outlet pipes 22 and 32 are positioned on the same side. In view of the similarity between the two embodiments the same reference numerals have been used for corresponding parts.

When the need occurs to clean or replace ele ments the top cover 36 (figure 4), or flanged lid 37 (figure 5), which may be retained by swing bolts 38 is released and lifted. In order to protect the filter ele ments 25 against damage during lifting fixed bars 39 are provided which extend axially of the filter cege 23 and are positioned between vertical rows of holes 24. When the cover or lid has been removed the retaining bars 28 can be loosened and the filter elements 25 slid axially upor down for removal. Alternatively, the cage 23 can be lifted out and the bars 28 removed, away from the filter body 21.

In use the self-cleaning backwashing filter is arranged to allow flow to continue whilst the cleaning operation is in progress. Contaminated liquid is introduced to within the filter cage 4,23 through the inlet 13,22 and passes to the outlet 15,32 through the filter elements 3. 25. Cleaning is accomplished by rotation of the backwash pipe 2,33 and its radial ducts 16,34 which align briefly with each filterele- ment 3, 25 in turn. The action of the ducts traversing the filter elements induces a reversal of flow of clean liquid back through the filter elements 3,25 causing anydirtto be washed off and conveyed to a backwash discharge 18, 40. The backwashing may be continuous or intermittent and may be controlled electronically by the pressure differential across the filter cage 4,23.

When it is desired to remove one or more filter elements 3,25 for replacement the particular retainer bar 6 or bars 28 is or are released from engagement with the filter elements so that the elements may be simply withdrawn or slid away from respectively registration with holes 14 or 24, by appropriate manipulation.

Although the filter elements are preferably cylindrical in shape they may be of any other suitable shape.

Claims

1. A filter comprising a plurality of filter elements covering respective holes in a filter cage, and common releasable retaining means operative to hold the elements in position against displacement, or, on release, to allow simple removal of the elements from the cage.

2. Afilter according to claim 1 wherein the filter cage is cylindrical and the holes are arranged in axially extending rows about the circumference of the cage.

3. A filter according to claim 1 or 2 wherein the filter elements have a portion which is received in the respective holes in the filter cage.

4. A filter according to claim 3 wherein said portion includes a sealing ring which seals against the inside of the respective hole in the filter cage.

5. Afilter according to claim 1 or 2 wherein the filter elements each include a sealing ring which sealsaboutthe mouth of the respective holes in the filter cage.

6. Afilter according to anyone of claims 2,3 or4 wherein the retaining means comprises one retain ing member for each axially extending row, the retaining members being releasably engageable with the filter cage and, when in position, trapping the filter elements between the respective members and the filter cage.

7. A filter according to claim 2 or 5 wherein the retaining means comprises two retaining members for each axially extending row, the retaining mem bers being releasably engageable with the filter cage and, when in position, engaging a shoulder on each of the filter elements in the respective row to hold the filter elements against the filter cage.

8. A filter comprising a plurality of filter elements supported exteriorly over holes in a hollow filter cage, a backwash pipe disposed axially of the filter cage, ducts in the pipe arranged to register with the holes in the filter cage, means for effecting relative rotation between the backwash pipe and the filter cage so that ducts are brought into registration in turn with the holes to permit backwashing of the filter elements, and at least one common releasable retainer member arranged, in a first position, to cooperate with the filter cage so as to hold the filter elements firming over their respective holes and, in a second, released position, arranged to allow removal of the filter elements solely by manipulation of the filter elements themselves.

9. A filter substantially as hereinbefore described with reference to and as illustrated in the accom panying drawings.