A device for filtering liquids and a filter unit for use in such a device.

(54) (56)

PATENT HOLDER Celleco-Hedemora AB, Box 12109 102 23 Stockholm SE

INVENTOR'S OFFICE

Paul Cameron, Täby SE, Jörgen Larsson, Clivemo I

Saltsjö-Boo SE

NAME Liquid filtration device LISTED PUBLICATIONS:

SEE B 318 859 (BOID 33 / 26B), US A 3 485 376 (210-331) (57) SUMMARY:

An apparatus for filtering liquids has an annular disc (1) having at least one perforated side wall covered by a filter medium. According to the invention, the filter medium comprises separate sections (14) which are attached to respective frames (13), each individual frame together with its associated section of the filter medium forms a separate filter unit (12). Each filter unit is detachably connected to the disk and arranged against the perforated side wall. The filter units can be made light and suitably identical, which facilitates the exchange of filter units with defective sections of filter medium against new filter units.

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The numbers in brackets indicate international identification code, INID code. Letters in clamps indicate international document code.

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The present invention relates to a device for filtering liquids, comprising an annular disc, two opposing side walls spaced apart from the disc, at least one of the side walls being perforated, a filter medium covering the perforated side wall and divided into separate sections, and frames on which respective sections of the filter medium are affixed.

SE-B-318 859 discloses a filtration device of this kind, in which each section of filter medium is applied to a separate portion of the perforated side wall, which is the same size as the section of filter medium. Each such set of a section of filter medium with associated portion of the perforated side wall is inserted into a frame-like holder on the sheet. When replacing a defective section of filter medium, it must first be ejected from the frame-like holder along with its associated side wall portion. Thereafter, the defective section may be removed from its side wall portion. However, mounting a new section of filter medium is relatively complicated, since it usually consists of a flexible material, such as fabric, and can easily be disrupted from its intended position on the side wall portion when the set of the new section of filter medium and its perforated side wall portion is pushed into the frame-like holder.

In conventional conventional disk filter devices, the side walls of the disk include several separate perforated wall portions arranged in series around the center of the disk. The wall portions of one of the sidewalls of the board are positioned opposite the wall portions of the other sidewall of the board, so that pairs of opposite wall portions are formed. Each such pair of wall portions is surrounded by a filter bag formed by the filter medium, the pair of wall portions and the filter bag forming a disc-shaped filter segment disposed detachable from the disc.

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If the filter bag of any filter segment is damaged, the entire filter bag of the filter segment must be replaced with a new filter bag. To allow for such a change of filter bags, the entire filter segment must be removed manually from the disc, which is a disadvantage, since the filter segments of existing conventional devices can weigh up to about 30 kg / pc. Thus, disassembling and assembling such filter segments is a difficult and difficult task. In addition, the work of replacing filter bags is relatively time-consuming, so the downtime costs associated with replacing defective filter bags are relatively high.

The object of the present invention is to provide a filtering device of this type which facilitates and allows rapid replacement of defective parts of the filter medium.

This object is achieved by means of a device of the kind initially indicated, characterized in that the separate sections of the filter medium are attached to the frames, so that each section with its frame forms a single unit formed apart from the perforated side wall, whereby each individual filter unit is removably connected to the disc. This has the advantage that replacing a filter unit with damaged filter medium with a new filter unit becomes easy to carry out manually, since the filter units can be made considerably easier compared to the filter segments described above in the conventional devices. In addition, the replacement of filter units can be carried out in a short time, which reduces downtime costs.

Preferably, the disc is provided with retaining means which hold the filter units in intended positions relative to the disc, the retaining means having separate portions which engage with radially outer ends of the filter units and which are detachably secured to the disc. The holding means are arranged so that the filter units

501 367 are displaceable substantially radially out of the disk when said separate portions of the holding means are detached from the disk.

In a device according to the invention, in which both the side walls are perforated, the filter units are preferably so oriented along the side walls that pairs of opposite filter units are formed. At each pair of filter units, the radially outer ends of the filter units are retained advantageously by one of said detachable parts of the holding means.

The invention is described in greater detail in the following with reference to the accompanying drawing, in which Figure 1 shows a disk of a device according to the invention, Figure 2 shows a filter unit of the disk according to Figure 1, Figure 3 shows a section along the line III-III in Figure 2. Figure 4 shows a detail of the disk of Figure 1 without filter units, Figure 5 shows a section along the line VV in Figure 4, Figure 6 shows the same detail as Figure 4 but with filter units, and Figures 7 and 8 show sections along lines VII-VII and 8, respectively. VIIIVIII in Figure 6.

The disk 1 shown in Figure 1 has twelve similar filter means

2, which is attached to a shaft 3 and is evenly distributed around it. Each filter member 2 has two opposing substantially flat grid walls 4 and 5 which are connected to each other

501 367 by means of connecting means 6, so that the grid walls 4,5 and connecting members 6 form a rigid support unit 7. The connecting means 6 keep the grid walls 4,5 at a distance from one another.

Each support unit 7 is in the shape of a circular sector with the cut off tip and is provided with an elongated holder member 8 which extends along the radially directed edges and radially inner edge of the support unit 7. The holder member 8 is formed with a central groove 9 in which the support unit 7 extends. On either side of the central groove 9, the holder member 8 is formed with groove 10. An elongated holder member 11 having the same cross-section as the holder member 8 extends along the arcuate radially outer edge of the support unit 7 and is releasably attached to the support unit 7, e.g. by screw joints (not shown in the drawing).

Separate identical filter units 12, each comprising a frame 13 having the same outer contour as the grating walls 4,5, and a section 14 of a filter medium covering and attached to the frame 13, are located opposite the respective grating walls 4,5. The radially extending ends and radially inner ends of the filter units 12 are in the grooves 10 of the holding members 8, while the arcuate radially outer ends 15 of the filter units are in the grooves 10 of the holding members 11 (Figs. 6-8).

The sections 14 are preferably formed of metal or plastic screen cloths.

Normally, the device according to the invention has several vertically oriented discs 1 which are arranged parallel to one another and rotatable about a common center axis. During rotation of the disks 1, the filter means 2 pass through the liquid to be filtered so that the filtrate passes through the sections 14 of filter medium and further through the grating walls 4,5 into the

501 367 the support units 7. From the support units 7, the filtrate is discharged via axial tubes (not shown in the drawing) from the device.

If any section 14 of the filter medium should become defective during operation, the device is temporarily stopped and the retaining member 11 holding the filter unit 12 with the defective section 14 is removed. The filter unit 12 with the defective section 14 is radially pulled out and away from the current filter member 2. Then a new filter unit 12 is pushed into place on the filter member 2. by means of the grooves 10 of the holder means 8. Finally, the holder member 11 is mounted.

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