METHOD AND APPARATUS FOR FILTRATION OF POLLUTED LIQUID

Abstract

Method and apparatus for filtration of polluted liquid in a single upright filtration tank, comprising feeding of fresh filter material via a fresh filter material inlet in a lower part of the filtration tank, feeding of polluted liquid via a liquid inlet in an upper part of the filtration tank, mixing of the filter material and the polluted liquid in the single upright filtration tank to filter the polluted liquid by conveying filter material from the lower part of the filtration tank to the upper part of the filtration tank, and discharge of used filter material through an upper used filter material outlet in the upper part of the filtration tank, and discharge of clean liquid from the filtration tank through a lower clean liquid outlet in the lower part of the filtration tank.

Claims

1.-16. (canceled)

17. A method for filtration of polluted liquid in a single upright filtration tank, comprising the steps: feeding of fresh filter material through a fresh filter material inlet in a lower part of the filtration tank, feeding of polluted liquid through a liquid inlet in an upper part of the filtration tank, mixing of the filter material and the polluted liquid in the single upright filtration tank and filtering the polluted liquid by conveying filter material from the lower part of the filtration tank to the upper part of the filtration tank, discharge of used filter material through an upper used filter material outlet in the upper part of the filtration tank, and discharge of clean liquid from the filtration tank through a lower clean liquid outlet in the lower part of the filtration tank.

18. The method according to claim 17, comprising the steps: continuously conveying filter material from the lower part of the filtration tank to the upper part of the filtration tank using a screw conveyer, and pumping polluted liquid in through the liquid inlet in the upper part of the filtration tank at a temperature that together with the filter material ends up at desired filtration temperature in the filtration tank.

19. The method according to claim 17, comprising the steps: semi-continuously conveying filter material from the lower part of the filtration tank to the upper part of the filtration tank, wherein filter material for a complete batch is feed into the filtration tank, conveying filter material up in the filtration tank using a screw conveyer, and pumping polluted liquid in through the liquid inlet in the upper part of the filtration tank at a temperature that together with the filter material ends up at desired filtration temperature in the filtration tank.

20. The method according to claim 17, wherein the time to convey the filter material from the lower part of the filtration tank to the upper part of the filtration tank is set to approximately 60-500 minutes.

21. The method according to claim 17, comprising the steps: circulating polluted liquid from the lower part of the filtration tank to the upper part of the filtration tank in a sparging loop comprising a circulation pump.

22. The method according to claim 21, comprising the steps: heating or maintaining heat in the polluted liquid in the sparging loop using a heat exchanger.

23. The method according to claim 17, comprising the steps: discharging used filter material through the upper used filter material outlet when the filter material is saturated.

24. The method according to claim 17, wherein fresh filter material feed via the filter material inlet to the filtration tank is at least one of: clay, activated charcoal, moss, sand, sintered glass, or ceramic filter material.

25. A filtration apparatus for filtration of polluted liquid, comprising: a single upright filtration tank holding filter material and polluted liquid, said filtration tank having a lower part with a lower fresh filter material inlet and a lower clean liquid outlet, an upper part with an upper used filter material outlet and an upper liquid inlet for polluted liquid, wherein said single upright filtration tank further comprises an internal conveyer feeding filter material from the lower part of the filtration tank to the upper part of the filtration tank.

26. The filtration apparatus according to claim 25, wherein said conveyer is a screw conveyer.

27. The filtration apparatus according to claim 25, wherein said filtration tank is an upright circular-cylindrical cylinder, and the conveyer is a vertical screw conveyer located inside the filtration tank.

28. The filtration apparatus according to claim 25, wherein the lower part of the filtration tank comprises a first feed screw conveyer feeding filter material from the fresh filter material inlet to the interior of the filtration tank.

29. The filtration apparatus according to claim 28, wherein a filter material hopper is located above the first feed screw conveyer in the fresh filter material inlet.

30. The filtration apparatus according to claim 25, wherein the upper part of the filtration tank comprises a second feed screw conveyer feeding used filter material from the interior of the filtration tank to the used filter material outlet.

31. The filtration apparatus according to claim 25, wherein the filtration tank comprises a circulation pump creating a sparging loop, wherein the polluted liquid is circulated from the lower part of the filtration tank to the upper part of the filtration tank.

32. The filtration apparatus according to claim 31, wherein a heat exchanger to heat or maintain heat in the polluted liquid during the filtration process is included in the sparging loop.

Description

DESCRIPTION OF THE DIAGRAMS

[0038] Embodiments of the present invention will now be described, by way of example only, with reference to the following diagrams wherein:

[0039] FIG. 1 shows a first embodiment of a filtration apparatus according to the invention.

[0040] FIG. 2 shows a second embodiment of a filtration apparatus according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0041] FIG. 1 shows a filtration apparatus 10 with a single upright filtration tank 12 in the form of a cylinder with a lower part 14a and an upper part 14b. The lower part 14a comprises a lower fresh filter material inlet 16 and a lower clean liquid outlet 20. The lower filter material inlet 16 may further comprise a horizontal screw conveyer 26 for conveying fresh filter material from a filter hopper 30 to the lower part 14a of the filtration tank 12. The upper part 14b of the filtration tank 12 may comprise an upper liquid inlet 22 for polluted liquid and an upper used filter material outlet 18. The upper part 14b of the filtration tank 12 may further comprise a horizontal screw conveyer 28 for conveying used filter material to the upper used filter material outlet 18.

[0042] The upright filtration tank 12 further comprises an internally and vertically placed conveyer, preferable a screw conveyer 24, for transport of filter material, and liquid, vertically in the filtration tank 12.

[0043] FIG. 2 shows a second embodiment of the filtration apparatus 10 according to the invention. The filtering apparatus 10 is similar to the first embodiment shown in FIG. 1, but may include a sparging loop 36. The sparging loop can include a pump 32 for pumping liquid from the lower part 14a of the filtration tank 12 to the upper part 14b of the filtration tank 12. The sparging loop 36 may further include a heat exchanger 34 heating or maintaining heat in the liquids in the loop 36.

[0044] Each screw conveyer 24,26,28 are preferable driven by an adjoining drive motor (not shown), and connected to a control system. The filter material inlet 16 can also be connected to the same control system. The same applies to the clean liquid outlet 20 and used filter material outlet 18. All parts of the apparatus 10 may be connected to said control system, thus providing an automatic filtration process.

[0045] The method according to the invention may include two filtration processes.

[0046] A first idea of the present invention is to have a continuous filtration process instead of batch process. This is done by feeding the fresh filter material into the lower part 14a of the cylindrical upright filtration tank 12, where the transport screw 24 is located inside. The time to move the filter material, by the screw 24, from the bottom 14a of the filtration tank 12 to the top outlet 18 for used filter material in the upper part 14b of the filtration tank 12, is preferable equal to the time for saturating the filter material (normally 60-500 minutes). In the upper part 14b of the single upright filtration tank 12 the polluted liquid will be pumped in through the liquid inlet 22 at a temperature that together with the filter material ends up at the ideal filtration temperature in the filtration tank 12. The outside of the filtration tank 12 can be heat traced if required. When the filter material, injected in the bottom 14a of the filtration tank 12, meets the polluted liquid it will filter the pollution in the liquid. In the bottom the filter material will have the maximum ability to absorb pollutions and in the top, near the exit, it will have the minimum ability to absorb pollutions. The liquid will have its maximum pollution in the top of the tank 12 and its minimum pollution in the bottom of the tank 12, near the exit. The volumetric flow and the filter material vs. the volumetric flow of the polluted liquid will give the efficiency of the filtration. If required the apparatus 10 can be equipped with the sparging loop 36 where the polluted liquid can be circulated from the bottom of the filtration tank 12 to the top of the filtration tank. If required this loop can pass the heat exchanger 34 to heat or maintain heat during the filtration process. The cleaned liquid will be taken out in the bottom of the filtration tank 12 through the clean liquid outlet 20 and the used filter material will be discharged in the top of the filtration tank 12 through the used filter material outlet 18.

[0047] A second idea of the present invention is to have a semi-continuous filtration process instead of a batch process. This is done by feeding the fresh filter material into the lower part 14a of the single upright filtration tank 12, where the transport screw 24 is located inside. The filter material for a complete filtration batch will then be screwed up to a level in the filtration tank 12. In the top of the filtration tank 12 the polluted liquid will be pumped in through the liquid inlet 22 at a temperature that together with the filter material ends up at the ideal filtration temperature in the filtration tank 12. The outside of the filtration tank 12 can be heat traced if required. If required the apparatus 10 can be equipped with the sparging loop 36 where the liquid can be circulated from the bottom 14a of the filtration tank 12 to the top 14b of the filtration tank 12. If required this loop 36 can pass the heat exchanger 34 to heat or maintain heat during the filtration process. When the filtration batch is completed the clean liquid is drained out in the bottom 14a of the apparatus 10, through the clean liquid outlet 20, and the used filter material is discharged at the top 14b through the used filter material outlet 18.

[0048] Fresh filter material feed via the filter material inlet 16 to the filtration tank 12 can for instance be picked from a group of: clay, activated charcoal, moss, sand, sintered glass, or ceramic filter material. The filter material can be at least one of said materials, or a combination of materials. Other filter material may also be used.