| WO/2002/089952 | DEVICE FOR CLEANING BAND FILTERS |
| WO/2008/157707 | MODULAR FILTER AND VACUUM HEAD ASSEMBLY FOR A FILTERING APPARATUS |
| WO/1990/006800 | PROCESS AND DEVICE FOR THE SEPARATION OF SUBSTANCES FROM MIXTURES |
RALVERT, Åke (Harvvägen 4, Hässleholm, S-281 33, SE)
| CLAIMS 1. Device for cleaning filter cloth (4) arranged on at least one filter element (3), which at least one filter element (3) forms a rotary disc filter (1), comprising at least one spray nozzle (5) for distribution of cleaning fluid on the filter cloth (4), characterised in that said at least one spray nozzle (5) is moveable in at least the longitudinal direction (L) of the disc filter (1) between predefined distances from the filter cloth (4). 2. The device according to claim 1 , comprising several spray nozzles (5). 3. The device according to any of the previous claims, wherein at least one spray nozzle (5) is moveable within an area which being defined by the circumference of the filter element (3). 4. The device according to any of the previous claims, wherein at least one spray nozzle (5) is arranged on at least one flush pipe (6), characterised in that the at least one flush pipe (6) is moveable in at least the longitudinal direction (L) of the disc filter (1) between predefined distances from the filter cloth (4). 5. The device according to claim 4, wherein at least one flush pipe (6) is moveable within an area which being defined by the circumference of the filter element (3). 6. The device according to any of the claims 4-5, wherein at least one flush pipe (6) is arranged on a flushing ramp (7), wherein the flushing ramp (7) and/or the disc filter (1) is movable, in relation to each other, in the longitudinal direction (L) of the disc filter (1). 7. The device according to claim 6, wherein said flush pipe (6) is rotatable arranged on the flushing ramp (7). 8. The device according to any of the previous claims, wherein the cleaning fluid is distributed at a pressure lower than 15 bar, preferably a pressure between 6-10 bar. 9. The device according to any of the previously claims, wherein the disc filter (1) comprising several filter elements (3). 10. The device according to claim 9, wherein the distance between two adjacent filter element (3) is less than 16 cm, preferably 12 cm. 11. The device according to any of the previously claims, wherein said spray nozzle (5) being moved in longitudinal direction, over the predefined distance, between preferably 4 and 8 cm from the filter cloth (4) 12. The device according to any of the previously claims, wherein the flow of cleaning fluid from the spray nozzle (5) embrace a larger portion of the area of the filter cloth (4) and have a less concentrated liquid jet at the larger distance from the filter cloth (4), and embrace a minor portion of the area of the filter cloth (4) and have a more concentrated liquid jet at the shortest distance from the filter element. 13. Method for cleaning filter cloth (4) arranged on at least one filter element (3), which at least one filter element (3) forms a rotary disc filter (1), comprising at least one spray nozzle (5) for distribution of cleaning fluid on the filter cloth (4), characterised in that said at least one spray nozzle (5) being moved in at least the longitudinal direction (L) of the disc filter (1) between predefined distances from the filter cloth (4). 14. Method according to claim 13, wherein the at least one spray nozzle (5) is moveable within an area which being defined by the circumference of the filter element (3). 15. Method according to any of the claims 13-14, wherein the at least one spray nozzle (5) is arranged on at least one flush pipe (6), characterised in that the at least one flush pipe (6) being moved in at least the longitudinal direction (L) of the disc filter (1) between predefined distances from the filter cloth (4). 16. Method according to claim 15, wherein at least one flush pipe (6) is moveable within an area which being defined by the circumference of the filter element (3). 17. Method according to any of the claims 15-16, wherein the at least one flush pipe (6) is arranged on a flushing ramp (7), wherein the flushing ramp (7) and/or the disc filter (1) being moved, in relation to each other, in the longitudinal direction (L) of the disc filter (1). 18. Method according to claim 17, wherein said flush pipe (6) may rotate in relation to the flushing ramp (7). 19. Method according to any of the claims 13-18, wherein the cleaning fluid is distributed at a pressure lower than 15 bar, preferably a pressure between 6-10 bar. 20. Method according to any of the claims 13-19, wherein the spray nozzle (5) being moved in longitudinal direction, over the predefined distance, preferably between 4 and 8 cm from the filter element (3). |
Field of the Invention
The present invention relates to a device for cleaning filter cloth arranged on at least one filter element, which at least one filter element forms a rotary disc filter, comprising at least one spray nozzle for distribution of cleaning fluid on the filter cloth. The invention also relates to a method for cleaning the filter cloth on at least one filter element.
Background Art
In EP-A-1 961 475 a disc filter is described, where water is conveyed into one end of a central, rotatable drum and forward through openings in the circumference of the drum radially outwards to at least one filter element. Each filter element comprising a filter body which is covered by filter cloth. The disc filter comprising also a flushing ramp which extends parallely with the centre line of the disc filter, outside the outer edge of the filter element. The flushing ramp is movable in the longitudinal direction of the disc filter by a driving device, wherein the flushing ramp being moved gradually or linear to different sides of a filter element or between several different filter elements. From the flushing ramp a minor number, preferably between one and four, smaller flush pipes extends outwardly in radial direction, where the flush pipes are arranged alongside the surface of the filter element. Pressurised cleaning fluid is spread via the flushing ramp and the flush pipe out through at least one spray nozzle onto the surface of the filter cloth, in opposite direction to the direction of filtration, to wash away any possible deposit from the filter cloth. The deposit being flushed back into the filter element and conveyed to a channel which drain off the deposits.
A flushing device according this type requires the use of cleaning fluid having an energy-intensive high pressure, since a lower pressure will not give a sufficient cleaning effect, especially on more clogged areas of the filter cloth.
Possibilities to adjust the pressure locally is also lacking for the filter element presently being cleaned.
In addition, a solution with a smaller amount of nozzles results in longer cleaning intervals, as no more than two filter elements can be cleaned simultaneously, neither can the whole surface of each filter element be cleaned simultaneously or during maximum one rotation of the filter element.
Summary of the Invention
One purpose with the present invention is to achieve a flushing device for a disc filter which does not require the use of an energy-intensive high pressure, and which at least cleaning a majority of the filter cloth of the disc filter at one and the same moment or during maximum one rotation of the filter element. It is also desirably that the pressure can be adjusted locally, and that cleaning can be performed continually without time-consuming interruption such as movement of the flushing device.
According one embodiment of the invention these and other purposes are obtained by a device for cleaning filter cloth arranged on at least one filter element, which at least one filter element forms a rotary disc filter, comprising at least one spray nozzle for distribution of cleaning fluid on the filter cloth, characterised in that at least one spray nozzle is moveable in at least the longitudinal direction of the disc filter, between predefined distances from the filter cloth.
Since the spray nozzle is moveable in the longitudinal direction of the disc filter the use of high pressure is not required, as the cleaning pressure on the filter cloth being increased, as required, by the movement itself.
The device comprising several spray nozzles, which results in that several filter cloths alternatively a larger portion of a filter cloth may be cleaned simultaneously.
At least one spray nozzle is moveable within an area which being defined by the circumference of the filter element, which facilitate cleaning of a large portion of at least one filter cloth with only one or a few spray nozzles.
At least one spray nozzle is arranged on at least one flush pipe, wherein at least one flush pipe is moveable in at least the longitudinal direction of the disc filter, between predefined distances from the filter cloth.
Since the flush pipe is moveable in the longitudinal direction of the disc filter, high pressure is not necessary to use, when the cleaning pressure on the filter cloth being increased, as required, by the movement.
At least one flush pipe is moveable within an area which being defined by the circumference of the filter element, which facilitate cleaning of a large portion of at least one filter cloth with only one or a few flush pipes. At least one flush pipe is arranged on a flushing ramp, wherein the flushing ramp and/or the disc filter is movable, in relation to each other, in the longitudinal direction of the disc filter.
When the flushing ramp and/or the disc filter is movable in the longitudinal direction of the disc filter, high pressure is not necessary to use, since the cleaning pressure on the filter cloth being increased, as required, by the movement itself.
The flush pipe is rotatable arranged on the flushing ramp, which result in decreased number of components, as two opposite filter cloths may be cleaned via one and the same flush pipe.
The cleaning fluid in the device is distributed at a pressure lower than 15 bar, preferably a pressure between 6-10 bar. A lower applicable pressure result in that less effect is required for driving the device during cleaning.
The disc filter comprising several filter elements, which provide a more effective disc filter since a larger volume of fluid may be filtrated at one and the same moment.
The distance between two adjacent filter elements is less than 16 cm, preferably 12 cm.
16 cm is a standard distance between filter elements in the disc filter. With this device the distance between the filter elements may be reduced, which give a smaller disc filter by volume, but with the same capacity.
The spray nozzle may be moved in the longitudinal direction, over the predefined distance, between preferably 4 and 8 cm from the filter cloth, which results in that both the pressure of the fluid and the area of distribution may vary.
The flow of cleaning fluid from said spray nozzle embrace a larger portion of the area of the filter cloth and have a less concentrated liquid jet at the larger distance from the filter cloth, and embrace a minor portion of the area of the filter cloth and have a more concentrated liquid jet at the shortest distance from the filter cloth.
This provide huge freedom regarding the desired effect of the cleaning fluid.
With the method according to the invention for cleaning filter cloth arranged on at least one filter element, which at least one filter element forms a rotary disc filter, comprising at least one spray nozzle for distribution of cleaning fluid on the filter cloth, at least one spray nozzle being moved in at least the longitudinal direction of the disc filter, between predefined distances from the filter cloth.
Since the spray nozzle is moveable in the longitudinal direction of the disc filter high pressure need not be used, when the cleaning pressure on the filter cloth is increased as required by the movement itself.
At least one spray nozzle is moveable within an area which being defined by the circumference of the filter element, which facilitate cleaning of a large portion of at least one filter cloth with only one or a few spray nozzles.
At least one spray nozzle is arranged on at least one flush pipe, wherein the at least one flush pipe being moved in at least the longitudinal direction of the disc filter between predefined distances from the filter cloth.
Since the flush pipe is moveable in the longitudinal direction of the disc filter high pressure need not be used, as the cleaning pressure on the filter cloth increasing as required by the movement.
At least one flush pipe is moveable within an area which being defined by the circumference of the filter element, which facilitate cleaning of a large portion of at least one filter cloth with only one or a few spray nozzles.
At least one flush pipe is arranged on a flushing ramp, wherein the flushing ramp and/or the disc filter being moved, in relation to each other, in the longitudinal direction of the disc filter.
As the flushing ramp and/or the disc filter is movable, in relation to each other, in the longitudinal direction of the disc filter high pressure need not be used, as the cleaning pressure on the filter element increasing as required by the movement.
The flush pipe is rotatable arranged on the flushing ramp, which provide a reduced number of components when two opposite filter cloths may be cleaned via one and the same flush pipe.
The cleaning fluid in the device is distributed at a pressure lower than 15 bar, preferably a pressure between 6-10 bar. A lower working pressure result in that less effect is required for driving the device during cleaning.
The spray nozzle being moved in longitudinal direction, over the predefined distance, preferably between 4 and 8 cm from the filter element, which result in that both the pressure of the fluid and the area of distribution may vary. Brief Description of the Drawings
The invention will in the following be described in more detail with reference to the accompanying schematic drawings which by way of example illustrate preferred embodiments of the invention.
Figure 1 is a view in perspective which schematically show the principle of a disc filter and a preferred embodiment of the cleaning device according to the invention.
Figure 2 is a view in perspective which schematically show several spray nozzles arranged on one side of a flush pipe, according to a preferred embodiment of the cleaning device according to the invention, and the spreading of cleaning fluid from the spray nozzles on an area at two different distances.
Figure 3 is a view in perspective which schematically show several spray nozzles arranged on two sides of a flush pipe, according to a preferred embodiment of the cleaning device according to the invention, and the spreading of cleaning fluid from the spray nozzles on an area at two different distances.
Detailed Description of a Preferred Embodiment
The principle for the structure of a disc filter 1 and a cleaning device 2 according to the invention will be explained with reference to figure 1.
The basic principle for a disc filter 1 is that the fluid which will be filtrated is conducted through one end of a central, rotatable drum and further through openings in the circumference of the drum radially outwards to at least one filter element 3. The filter element 3 consist of a frame on which a filter cloth 4 is arranged. Wherefrom the fluid is conducted in one direction of filtration out through the filter cloth 4. Possible particles in the fluid fasten on the interior of the filter cloth 4.
The disc filter 1 also comprising a cleaning device 2. Through the cleaning device 2 pressurised cleaning fluid is conveyed, which thereafter being flushed, in opposite direction to the direction of filtration, on the filter cloth 4 of the filter element 3 to wash away possible deposits from said surface. The deposits being flushed back into the filter element 3 and being conveyed to a channel which drain off the deposits.
The cleaning device 2 consists, according to a preferred embodiment, of at least one spray nozzle 5. One or several spray nozzles 5 may be arranged on one or several flush pipes 6, wherein the spray nozzles 5 may be directed towards the same or against different directions depending on the need at the present moment, see figure 2 and figure 3.
The spray nozzle 5 may, in one embodiment, be freely moved within the radial surface of the filter element 3, thus within the area whose outer edge being defined by the circumference of the filter element 3.
The spray nozzle 5 may be moved in the longitudinal direction L of the disc filter 1 towards and/or away from one, or two, filter cloth 4 of the filter elements 3. The movement may be executed linear or gradually, and the spray nozzle 5 stops at predefined distances from the filter cloth 4. The movement may be executed in the same or opposite direction to the flow of cleaning fluid.
The spray nozzle 5 may preferably be moved in the longitudinal direction between 4 and 8 cm from the filter cloth 4. The flow of cleaning fluid from the spray nozzle 5 embrace a larger portion of the area of the filter cloth 4 and has a less concentrated liquid jet at the largest distance from the filter cloth, and embrace a minor portion of the area of the filter element and has a more concentrated liquid jet at the smallest distance from the filter cloth.
The flush pipe 6 in its turn is arranged on a flushing ramp 7. The flushing ramp 7 extends parallely with the centre line C of the disc filter 1 , outside the circumference of said at least one filter element 3. At least one flush pipe 6 extends from the flushing ramp 7 on a level with the surface of the filter cloth 4. The flush pipe 6 is fasten or rotatable arranged, depending on the requirements. The expression rotatable, also refer to the rotation around the attachment of the flushing pipe 6 in the flushing ramp 7, in both x-, y-, and z-coordinate.
The filter element of a disc filter is usually arranged with a spacing of 16 cm. According to a preferred embodiment this distance has been reduced to preferably 12 cm.
The flush pipe 6 may, in one embodiment, be freely moved within the radial surface of the filter element 3, thus within the area whose outer edge being defined by the circumference of the filter element 3. It may also be moved in the longitudinal direction L of the disc filter towards and/or away from one, or two, filter cloth 4 of the filter elements 3. The movement may be executed linear or gradually, and the flush pipe 6, or the thereto arranged spray nozzle 5, stops at predefined distances from the filter cloth 4.
Also the flushing ramp 7 may be moved in the longitudinal direction L of the disc filter 3. The movement may be executed linear or gradually, and movement of the flushing ramp 7 is adjusted such that the spray nozzle 5 stops at predefined distances from the filter cloth 4.
In an additional embodiment the flushing ramp 7 is stationary while the disc filter 1 being moved in the longitudinal direction L of the disc filter. Still another alternative is that both the flushing ramp 7 and the disc filter 1 being movable, in relation to each other, in the longitudinal direction L.
The cleaning fluid being flushed through the flushing ramp 7 and the flush pipe 6 out through the spray nozzle 5. Only the cleaning fluid which being flushed out of the spray nozzle 5 meet the filter cloth 4, whereby the filter cloth 4 become cleaned.
The parameters which being used to calculate the liquid flow and the different movement of the components in the longitudinal direction L are e.g. the pressure of the fluid, the spreading of the fluid, the rotation velocity of the filter element 3 and the direction and velocity of movement of the cleaning device 2.
The pressure of the fluid remains below 15 bar, and lying preferably within an interval between 6-10 bar.
It is realized that several modifications of the herein described embodiments of the invention is possible within the frame of the invention, which being defined in the following patent claims. The cleaning device 2 may be produced in alternative ways and i.e. consist of other components than the flushing ramp 7 and the flush pipe 6. The cleaning device 2 may be of a smaller sized than stated, and may only embrace a minor portion of the disc filter 1 at each time. The parameters which being used to calculate the distance between the spray nozzle 5 and the filter cloth 4 may be other than those mentioned here. Different parts of the device, such as the flushing ramp 7 or the flush pipe 6 may be movable, both in separate parts or in several combinations, with each other. Additionally, the cleaning device 2 may be used for cleaning other devices than a disc filter 1.