WO1992013625A1

WO1992013625A1 - A unit for the filtration of fluids, with at least one rotatable, flat, circular filter wheel in an open-top container

Info

Publication number: WO1992013625A1
Application number: PCT/NO1992/000022
Authority: WO
Inventors: Øystein FÆSTØ; Osmo Leirivaara
Original assignee: Faestoe Oeystein; Osmo Leirivaara
Priority date: 1991-02-06
Filing date: 1992-02-06
Publication date: 1992-08-20
Also published as: NO172626B; NO910453D0; NO910453L; NO172626C; AU1190992A

Abstract

A unit for the filtration of fluids, with an open-top container (1), at least one flat, circular filter wheel (20) comprising a frame (21) and a filter (22), provided in the container, and a drive mechanism for rotation of the filter wheel. Fluid flows in the container's longitudinal direction through filter sections which are successively lowered into the fluid during the rotation. According to the invention an open, principally transverse track (10) is arranged inside the container, the track being arranged to sealingly support frame (21) during rotation. The projection in the container's longitudinal direction of that section of the filter (22) which is arranged below the level of fluid in the container, is at least as large as that container cross section which is defined by the container and the fluid surface when the frame is located in the track.

Description

A UNIT FOR THE FILTRATION OF FLUIDS, WITH AT LEAST ONE ROTATABLE, FLAT, CIRCULAR FILTER WHEEL IN AN OPEN-TOP CONTAINER.

The invention concerns a unit for the filtration of fluids, comprising an open-top container, at least one flat, circular filter wheel and a drive mechanism for rotation of the filter wheel, the container having a casing shaped approximately like a half cylinder, two end walls, with an inlet pipe and an outlet pipe provided in the respective end walls, and the filter wheel comprises a circular frame and a filter which extends in the frame plane and is attached to the frame, where the filter wheel can be rotated around an axis which extends through the centre of the frame and perpendicular to the plane in which the frame extends, and the filter wheel is provided in the container in a manner which allows the fluid which flows in the container's longitudinal direction from the inlet opening to the the outlet opening and principally fills the container to an operational level, to flow through the filter sections which are successively lowered into the fluid during the rotation of the filter wheel.

There is a previously known unit of the above-mentioned type, in which the outer diameter of the filter wheel's frame is smaller than the container's inner diameter, i.e. the frame projects radially into-the container, and where the filter wheel extends perpendicular to the container's longitudinal axis.

In the first place, the area of the filter thereby becomes smaller than the container cross section which is bounded by the casing, thus necessitating the relatively frequent replacement of the filter, and because the frame projects into the container it forms a threshold which generates dead water areas in which those particles which have to be filtered out collect and are prevented from flowing onwards, a fact which reduces the unit's efficiency and can result in a breakdown and necessitate expensive and demanding cleaning operations.

In the second place, this reduces the extent to which heavy particles stick to the filter and are removed from the fluid when the filter wheel is rotating, a significant number of these particles accumulating in front of the lower section of the frame.

The container in known units is manufactured in one piece. Thus it cannot be easily shortened or extended in order to change the number of filter wheels as a result of altered operational conditions, and since the filter wheel is rotated by means of a belt via an overhead driving roller, the wheel has to be pushed downward in order to tighten the belt by means of overhead support rollers, against which the peripheral sections of the wheel can abut. Thus, in order to remove the filter wheels it is necessary to also remove the support rollers, which is cumbersome.

In known units, fluid which flows between the frame and the container and which is therefore not filtered, cannot be collected and pumped back to the container chamber whence it came for filtering. Thus the fine filters provided in the downstream can become blocked by particles which should have been collected by coarser filters provided in the upstream, a fact which is not expedient and increases the cost.

The object of the invention is to provide a unit of the type mentioned in the introduction, and which is not encumbered by the above-mentioned disadvantages.

The characteristics of the invention are illustrated by the features in the claims presented.

In the following section the invention will be described in more detail with reference to the drawings which illustrate schematically embodiments of the unit according to the invention.

Fig. 1 is a perspective view of a first embodiment of an open- top container and a filter wheel provided therein for a unit according to the invention, where the filter wheel's drive shaft is shown in section. Fig. 2 is a plan view of the container and the filter wheel illustrated in fig. 1, a motor also being illustrated for the driving wheel.

Fig. 3 is a cross section after line III-III in fig. 2.

Fig. 4 is a section on a larger scale after line IV-IV in fig. 2 and of the lower section of the container, sections of the container and the filter wheel being cut away.

Fig. 5 is a similar section to that illustrated in fig. 4, but of another embodiment of the track.

Fig. 6 is a section after line VI-VI in fig. 2, but for a unit which comprises a container with a differently shaped track and a filter wheel which is supported by means of rollers provided in the track.

Fig. 7 is a side view on a larger scale of the filter wheel illustrated in fig. 1 and a driving mechanism for this.

Fig. 8 is a side view of a container with an angled filter wheel whose wheel plane extends perpendicular to the container's plane of symmetry, where sections of the container are cut away.

Fig. 9 is a plan view of a container with a vertically extending filter wheel, which is at an angle to the container's longitudinal axis, where sections of the container are cut away.

Fig. 10 is a perspective view of another embodiment of a container comprising a curved distance piece and two end modules, these parts being separated from each other.

Fig. 11 is a perspective view of a central module which can be used together with the end modules illustrated in fig. 10. Fig. 12 is a section corresponding to that illustrated in fig. 4, through a track provided between two modules of the type illustrated in figs. 10 or 11, the filter wheel being removed.

In the following section, the terms upper and lower refer to the relative location of sections etc. of the unit when it is installed in its operational position, i.e. with the container's opening facing vertically upwards, e.g. as illustrated in fig. 1.

As illustrated in fig. 1, the unit comprises an open-top container 1 which comprises a casing 2 principally in the shape of a half, circular cylinder, and two end walls 3,4. The end wall 3 has an inlet pipe 5 for the fluid which has to be filtered, and the end wall 4 has an outlet pipe 6 for the filtered fluid. During operation, the fluid level in the container is regulated so that the fluid surface is maintained at the horizontal container diameter 15 illustrated in fig. 3.

The container is supported by suitable brackets 14.

A central section of the casing 2 is provided with two flanges 7, 8 which extend in respective transverse planes, from one upper, longitudinal edge of the casing to the other. Between the periphery of the flanges there extends a flat profile 9, and the section of the casing between the flanges 7,8 is removed, the flanges and the profile thus together defining an open track 10 inside the container 1.

The connection between the end walls and the casing, between the casing and the flanges and between the flanges and the profile is watertight.

As illustrated in fig. 3, a lower section 11 of the casing's cross section is shaped like a semi-circle, the ends of which are extended upwards, two parallel casing sections 12, 13 being connected with the lower casing section 11. The diameter of this 15 and the container's plane of symmetry 16 are illustrated by a dash-dot line.

In the track 10 there has been inserted a flat filter wheel 20 comprising a circular frame 21, on which is stretched a circular filter cloth 22, hereinafter called a filter. The plane in which the filter wheel extends is referred to here as the wheel plane.

In order to secure the filter 22 the frame 21 can, e.g., comprise two ring parts, in one of which is provided, e.g., a V-shaped, circular track and in the other is provided a circular bead whose cross section is adapted to suit the cross section of the track, this track and the bead extending coaxially in relation to the frame. In order to fasten the filter to the frame, the letter's peripheral section is placed between the ring parts, thus causing a ring-shaped section of the filter to be pushed into the track by means of the bead when the ring parts are joined, and the filter is thereby tightened and secured.

The section of the frame 20 which is arranged for introduction into the track 10 comprises two lateral surfaces 23, 24 (see fig. 4) which extend parallel to the wheel plane. The clearance between these lateral surfaces and the respective overhead lateral surfaces 27, 28 of the track when the frame is in the track, are selected so as to enable the filter wheel to be easily rotated, but so that thereby only a minimum leakage of fluid occurs from one side of the filter wheel to the other via this slit when the fluid flows from the inlet opening 5 to the outlet opening 6. During the rotation, the periphery of the filter wheel can slide against the profile 9 of the track 10 and the frame's lateral surfaces 23, 24 can slide against the opposite lateral surfaces 27, 28 of the track 10. It is therefore advantageous that the materials of which the track and the frame are made are of such a kind that their mutual sliding friction coefficient is low. Thus the track can be made of stainless steel with minimal surface roughness, and those frame sections which are arranged to abut against the track can be made of a suitable plastic material, or vice versa.

For continuous cleaning of the filter in units of this type, a device (not shown) can be provided whereby, during the rotation of the filter wheel, the filter sections, which are successively removed from the fluid in the container, are washed by a cleaning fluid which flows through these filter sections in the opposite direction to the direction of flow for the fluid being filtered. The cleaning fluid with the flushed out particles is collected in channels provided on the front of the filter wheel.

If the fluid has a high degree of pollution, and if particles of different sizes appear, etc. , the container can be arranged to incorporate more than one filter wheel, the container being provided with several tracks similar to track 10.

If the above-mentioned sealing between the track 10 and the frame 21 should be insufficient, there can be provided between one track side 28 and a respective overhead frame side 24 a sealing strip 25 which is provided in a groove in one of the flanges, and which extends along the track 10.

It is particularly advantageous for the opposite lateral surfaces 27, 28 of the track 10 to have respective grooves for sealing strips 25, 26 of the above-mentioned type, as illustrated in fig. 5.

If the frame 21 on the radially outward facing peripheral side hereby has a circular hollow 30, and there is provided in the bottom section of the profile 9 a through-going passage 31, fluid which may leak through the sealing strips can be collected in the hollow 30 and pumped back via the passage 31 and a suitable piping system to a point upstream of the leakage site, thus allowing this fluid also to be filtered. When fluid flows with relatively high velocity into the inlet pipe 5, it is advantageous to provide in this an ejector pump which is operated by the inflowing fluid, and whose inlet pipe is connected with the passage 31 via suitable pipes, thus enabling leakage fluid to be led to the unit's inlet pipe.

In order to reduce the power required for rotation of the filter wheel, there can be provided between the two flanges 41 which define the track and at at least two points along the circumference of the track, a shaft extending in the container's longitudinal direction which is attached to the flanges, and on which there are provided respective rotatable bearing wheels 40, arranged to support the filter wheel 20 and permit rotation of this when the frame 21 is provided in the container's track 10, as illustrated in fig. 6, where two bearing wheels 40 are illustrated.

As illustrated, e.g., in fig. 7, for rotation of the filter wheel and along the periphery of the frame 21 there can be arranged teeth 50 which together form a toothed rim. This is arranged to be rotated by a motor 52 via a tooth wheel 51. The motor can be attached, e.g., to the container 1 by means of a suitable holder (not shown) .

As also illustrated in fig. 7, the frame can comprise two rings 53, 54, in which one ring 53 is provided with teeth 50, and the other ring 54, whose diameter is greater than the diameter of the former ring 53, is arranged to abut against the bottom of the track 10 and the bearing wheels 40. The rings can be connected by means of, e.g., screws whose centre lines are indicated by dash-dot lines 55. As illustrated in figs. 4 and 5, the hollow 30 for leakage fluid has been formed as a result of the frame rings 53 and 54 having different diameters. If the filter wheel is operated in another way the hollow can, of course, be formed in another manner.

Instead of having the wheel plane perpendicular to the container's longitudinal axis, it can be provided in such a way that a diametrical line of the filter wheel extending in the container's plane of symmetry extends at an angle to the container's longitudinal axis, as illustrated in fig. 8. Thus the filter wheel extends simultaneously upwards and towards the outlet end of the container. The advantage of this arrangement is that it will enable heavy particles in the fluid to stick more easily to the filter and to be removed from the fluid during the rotation of the filter wheel, as will also be the case for light particles which are floating on the fluid. Moreover, the effective filter area, i.e. the area of the filter cloth which is stretched on the frame and which is permeated by fluid, will be greater than in a filter wheel whose wheel plane extends perpendicular to the longitudinal axis of the container.

An increase in the effective filter area can also be obtained by displacing the angle of the wheel plane around a vertical axis, as illustrated in fig. 9, where a diametrical line of the filter wheel, extending along a plane which is perpendicular to the container's plane of symmetry, and which comprises the container's longitudinal axis, extends at an angle to this axis. _ -. _-^.

Since the filter wheel must remain circular even when at an angle as described above, the shape of the flanges, viewed perpendicular to the plane in which the flanges extend, will be elliptical in the case of a circular cylindrical casing.

Alternatively, the cross section shape of the casing can be altered to make this elliptical with the major axis of the ellipse extending horizontally or vertically, dependent on whether the filter wheel is angled in the former or the latter way.

Instead of manufacturing a container with two chambers in one piece, as shown in fig. 1, a container of this kind can comprise two end modules 61, 62 as illustrated in fig. 10. Each end module comprises a casing section 63, 64 shaped approximately like a half cylinder, one end of which is closed with an end wall 65, 66, and the other end having a principally radially outward projecting flange 67, 68 extending along the end edge of the casing. Furthermore, the container can comprise a curved distance piece 69 whose curve is adapted to fit the shape of the radial outer section of the flanges 67, 68. The flanges and the distance piece can be connected by means of, e.g., screws which are arranged to be inserted in holes which extend in the container's longitudinal direction through the flanges and the distance piece. The longitudinal axis of such a screw is indicated by 71.

Moreover, the container can comprise one or more central modules 80, each of which comprises a casing section 81 shaped approximately like a half cylinder. Each end section of the casing section, calculated in its longitudinal direction, has, extending along the end edge of the casing, a principally radially outward projecting flange 82, 83, which is aranged to be connected with a respective, corresponding flange of a second central module 80 or an end module 61, 62 via a curved distance piece 69 as described above, whose curve is adapated to suit the shape of the radial outer section of the flanges, and which is arranged as a seal between the flanges, thus providing a container with at least two transverse tracks, whose lateral surfaces are formed by the lateral surfaces of adjacent flanges which are facing each other, and where the bottom of the tracks is formed by the respective distance pieces 69.

Thereby the length of the container can be increased or reduced as required, and the container supplied with one or more filter wheels.

In order to reduce the friction between the filter wheel and the flanges, sides of adjacent flanges which face each other can be provided with a coating, blocks, tape, etc. against which the frame is arranged to abut when it rotates in the track.

Claims

PATENT CLAIMS

1. A unit for the filtration of fluids, comprising an open- top container (1) , at least one flat, circular filter wheel (20) , and a drive mechanism for rotation of the filter wheel, the container having a casing (2) shaped approximately like a half cylinder, two end walls (3,4), and also an inlet pipe (5) and an outlet pipe (6) provided at the respective end walls, and the filter wheel (20) comprises a radial outer annular, circular frame (21) and a filter (22) which extends in the frame plane and is attached to the frame, where the filter wheel can be rotated around an axis which extends through the centre of the frame and perpendicular to the plane in which the frame extends, hereinafter called the wheel plane, and the filter wheel is provided in the container in such a way that fluid which flows in the container's longitudinal direction from the inlet opening to the outlet opening and principally fills the container to an operating level, can flow through filter sections which are successively lowered into the fluid during the rotation of the filter wheel, characterized in that the casing (2) has an open, principally transverse radial internal track (10,70) in the container, which track extends radially outwards from the internal surface of the container and which is arranged so as to seal and accept and support during rotation a ring section of the filter wheel's frame (21), the ring section being radially outside the internal surface of the container when it is located in the track

2. A unit according to claim 1, characterized in that between at least one track lateral surface (27,28) and a respective overhead frame lateral surface (23,24) there is provided a sealing strip (25,26) which is attached to the casing (2) and which extends along the track (10,70) .

3. A unit according to claim 2, characterized in that to two opposite lateral surfaces (27,28) of the track, calculated in the container's (1) longitudinal direction, there are attached respective sealing strips (25,26) .

4. A unit according to claim 3, characterized in that at a bottom section of the container (1) , the bottom of the track (10,70) has a radially extending, through-going passage (31) via which fluid which may have leaked past the sealing strips (25,26), can be led back to a point located upstream of the leakage site.

5. A unit according to one of the preceding claims, characterized in that the frame (21) of the filter wheel (20) is arranged so as to slide in the track (10) , in that, with its radially outwards facing peripheral surface, it rests against the bottom of the track.

6. A unit according to one of the claims 1-4, characterized in that between two opposite track lateral surfaces which define the track (10,70) in the container's (1) longitudinal direction, and at at least two points along the circumference of the track, there extends a shaft which is attached to the container, and on which there are provided rotatable bearing wheels (40) arranged to support the filter wheel (20) and permit rotation of this when its frame (21) is arranged in the container's (1) track.

7. A unit according to one of the preceding claims, characterized in that the container (1) comprises two end modules (61,62) each of which comprises a casing section (63,64) shaped approximately like a half cylinder, one end of which is closed by one of the end walls (65,66), and the other end has a principally radially outwards projecting flange (67,68) extending along the end edge of the casing, and furthermore the container comprises a curved distance piece (69) whose curve is adapted to suit the shape of the radial arranged so as to be connected with the distance piece (69) provided as a seal between these, thus providing a container with a principally transverse track (70) , whose lateral surfaces are formed by the lateral surfaces of the flanges (67,68) which are facing each other, and where the bottom of the track is formed by the distance piece (69) .

8. A unit according to one of the preceding claims, characterized in that the container comprises at least one central module (80) comprising a casing section (81) shaped approximately like a half cylinder and each end section of the casing section, calculated in the latter's longitudinal direction, has a principally radially outwards projecting flange (82,83) extending along the end edge of the casing, each of the flanges being arranged so as to be connected with a corresponding flange of a second central module (80) or an end module (61,62), and a curved distance piece (69), whose curve is adapted to suit the shape of the radial outer section of the flanges (67,68,82,83), is provided as a seal between the flanges, thus providing a container with at least two trans¬ verse tracks (70) , whose lateral surfaces are formed by the lateral surfaces of adjacent flanges which are facing each other, and where the bottom of the tracks is formed by the respective distance pieces (69) .

9. A unit according to one of the preceding claims, characterized in that the filter wheel's frame (21) has a toothed rim which is arranged so as to be operated via a tooth wheel (51) for rotation of the filter wheel (20) .

10. A unit according to one of the preceding claims, characterized in that a diametrical line of the filter wheel (20) extending in the container's (1) plane of symmetry, extends at an angle to the container's longitudinal axis (17) .

11. A unit according to one of the preceding claims, characterized in that a diametrical line of the filter wheel (20) , extending in a plane which is perpendicular to the container's plane of symmetry (16) and which comprises the container's longitudinal axis (17), extends at an angle to this axis.