GB2157583A

GB2157583A - Recovery of floaters from pulverised fuel ash

Info

Publication number: GB2157583A
Application number: GB08409364A
Authority: GB
Inventors: David Oakey
Original assignee: MATERIAL RESOURCES Ltd
Current assignee: MATERIAL RESOURCES Ltd
Priority date: 1984-04-11
Filing date: 1984-04-11
Publication date: 1985-10-30
Also published as: GB8409364D0; GB2157583B

Abstract

Pulverised fuel ash is discharged into a lagoon so that a proportion thereof floats on the surface, from which it is removed by apparatus comprising a submersible floor 14 suspended between two floats 21, 31. After floating ash has entered the space above submerged floor 14 through inlet 11, possibly by wind action, the buoyancy of the floats is increased to lift floor 14 clear of the water. Roof 17 allows the sun's rays to dry the ash on floor 14, and also the floor may be porous enabling water to drain therethrough. The floor may be constructed as an endless filter belt, so that the dried ash an be discharged through outlet 13 by advancing the belt. <IMAGE>

Description

SPECIFICATION Recovery of floaters from pulverized fuel ash At power stations for combusting solid fuel, pulverized fueld ash is produced and discharged into lagoons of water. A proportion of that ash floats on the lagoon. This proportion called "floaters" is useful material sold under the trade name CENOS- PHERES. While on lagoon water, at least some floaters are subjected to drying by wind, with the result that sufficiently dried floaters can be blown away by wind and be an environmental problem.

Wind can cause floaters to change location on the lagoon water. The changes of location mean that shifting floaters may have to be chased by apparatus for their recovery. One method of recovery of floaters comprises scooping from the surface of the lagoon amounts of floaters with some water.

Another method of recovery of floaters comprises pumping from the lagoon amounts of floaters with some water. Water removed with floaters can be a substantial proportion (e.g. as much as 60% weight/weight) of the combined weights of removed floaters and removed water. Separation of water from removed floaters can be done by a separation method comprising pumping into drainage trailer vehicles the removed floaters/water, the vehicles having drainage apertures through which can drain some water. Drainage lasts usually over night and results in floaters blocking drainage apertures. The following morning, the vehicles having blocked drainage apertures are moved to other location(s), e.g. a distance of 0.5 to 2.0 km.

During that removal, drainage aperture(s) can become unblocked, thereby allowing floaters and/or residual water to deposit on the ground (e.g. road surface), and be an environmental problem. The economics of recovering floaters requires large amounts of floaters to be removed from lagoons. It is customary for those amounts to be sold to purchasers who buy in bulk. A problem of bulk purchase is that those purchasers stock large piles of floaters containing some water. Action of wind on such a pile can cause sufficient drying of floaters that at least some can be blown about by wind and be an environmental problem.

A first aspect of the present invention provides apparatus for recovering floaters from a lagoon of water, said apparatus comprising: (a) at least one collection chamber having at least one inlet for receiving floaters from outside said at least one inlet, at least a portion of those receivable floaters being optionally impellable by external wind into said chamber, said chamber optionally having at least one outlet for removing floaters from said chamber, wherein said chamber comprises a submersible floor, said floor being raisable above the level of lagoon water so as to raise and support above that level at least some of the said floaters which have entered said chamber;; (b) first and second floatation means between which is located said chamber, said first and second floatation means having adjustable buoyancy so as to enable said floor to become submerged or raised above the level of lagoon water.

A second aspect of the present invention provides a method for recovering floaters from a lagoon of water, said method comprising utilising apparatus according to said first aspect of the present invention.

A third aspect of the present invention provides floaters recovered by apparatus according to said first aspect of the invention, or recovered by a method according to said second aspect of the invention.

The dirnensions and shape of said lagoon will depend on local circumstances, e.g. expected directions and strengths of external wind(s). Said lagoon can have at least one component of direction to aid passage of floaters into said inlet. For example, the surface of the lagoon can at least partly converge towards said inlet. The present invention is applicable to suitable existing lagoons, or to lagoons predesigned for use with the present invention.

Said collection chamber can be constituted in any suitable manner(s). Said chamber can have any suitable shape, e.g. have any suitable aspect ratio interconnecting at least two dimensions. For example, the ratio of maximum free height (i.e.

clearance above the level of lagoon water (H) to width (W) of a cross section of said chamber can be H W = (2.0 to 2.5 meters)/(0.15 to 0.75 meters), or any other suitable values. If desired, said chamber can be partitioned, e.g. to provide at least one compartment having an appropriate portion of said floor. A partition for that purpose can be continuous or discontinuous, e.g. be apertured to enable communication between adjacent said compartments. Preferably, said chamber is longitudinal between said inlet and said outlet thereof.

At least one optional first guide means can be provided for directing into andlor towards said inlet, floaters for entry into said chamber. Said first guide means can be constituted in any suitable manner(s). At least one said first guide means can be adapted to converge into and1 our towards said inlet at least a portion of said receivable floaters.

One example of a said first guide means comprises at least one suitably orientated abutment on the surface of the lagoon, for instance a floating boom, or a suspended chain, or a wall extending suitably upwardly from the bed of the lagoon.

At least one optional gate means can be provided for gating said inlet so that receivable floaters can enter said inlet but not return outwardly.

Said gate means can be constituted in any suitable manner(s). Some examples of said gate means are flap(s), sluice(s), or wier(s).

At least one optional second guide means can be provided for directing into and our towards said outlet, floaters to be discharged via that outlet. Said second guide means can be constituted in any suitable manner(s). At least one said second guide means can be adapted to aid or enable at least a portion of said received floaters at least partly to rise towards said outlet. For example, at least one said second guide means can comprise at least one suitably orientated abutment, e.g. a ramp.

Said floor will ascend or descend according to ascent or descent of said first and second floatation means. Said floor can be constituted in any suitable manner(s). Said floor can be movable in at least one conveyor direction for said supported floaters, i.e. a direction in which those floaters can be conveyed in providing their discharge from said chamber. Thus, optionally said floor is a conveyor, e.g. a conveyor web having opposite ends or being endless, for instance a suitable conveyor belt. At least one of those ends can be coiled or otherwise folded for providing a store of that web, said store being decreasable or increasable in accordance with appropriate motion of that web. Optionally, said web is apertured for gravitational drainage of water from said supported floaters. Said floor can be provided with at least one support means for supporting said floor.Said floor when a conveyor can be provided with at least one guide means for guiding conveyor motion of that floor.

Any said floatation means can be constituted in any suitable manner(s). Any said floatation means can be at least partly resilient and'or at least partly rigid. Adjustable buoyancy of any said floatation means can be provided in any suitable manner(s), e.g. by utilising gas(es), for instance air; liquid(s), for instance ballast water, which can be lagoon water; solid(s), for instance removable weight(s).

Preferably, any said floatation means comprises a respective floatation chamber, e.g. an inflatable floatation chamber, or a ballast water chamber from which ballast water can be discharged or into which ballast water can be charged, preferably by adjustment of a volume of gas (e.g. air) in that chamber, as when for instance that chamber is bottomless, i.e. has an open bottom for immersion in the lagoon. The adjustable buoyancy can enable said floor to have any suitable levei(s). Control of the adjustable buoyancy can control drainage period for the supported floaters andior profile of raise of said supported floaters. Said control can provide an optional ramp to aid exit of floaters from said outlet and/or aid drainage from said supported floaters.Preferably, said first and second floatation means are respectively attached to and/ or constitute corresponding portions of said collection chamber.

Said apparatus of the first aspect of the present invention can comprise (c) a roof adapted to admit radiation into said chamber so as to provide heat for evaporating at least a portion of water from said supported floaters. Said roof can be embodied in any suitable manner(s). Said roof can be permanently or removably located, e.g. suitably attached to said first and second floatation means. If desired, a said removable roof can be adapted to be sprung into location. Preferably, said roof is shaped to aid or enable motion of water condensed onto the underneath of that roof, e.g. enable that motion to deliver at least a portion of said condensed water to at least one predetermined location, for instance an optional drainage means, e.g. a gutter. Examples of that shape are an upward pitch provided by a ridge or dome.Said roof can be continuous or discontinuous, e.g. be apertured for enabling at least a portion of wind to enter and/or exit from said collection chamber, that wind optionally having a drying action on at least some said supported floaters in that chamber. Said roof can be self supporting or non-self-supporting.

At least one support means can be provided for said roof. Examples of material(s) for said roof are plastics or other polymeric material, e.g. in the form of a membrane or other sheet. it will be appreciated that said roof can be embodied to aid solar radiation and/or other radiation to provide said evaporation; said roof can be suitably transparent.

At least one optional dryer means can be provided for removing in said collection chamber at least a portion of water from said supported floaters. One example of said dryer means is when said roof comprises at least one aperture constituting dryer means for enabling at least a portion of wind to enter andior exit from said collection chamber. At least one said dryer means can be adapted for providing an artifical wind in said collection chamber, optionally by suction using a suction extracter. At least one said dryer means can comprise gravitational dryer means for aiding gravitational drainage of said supported floaters, e.g. at least one aperture that can be provided in said floor, when such an aperture is required. Another example of said gravitational dryer means comprises a guide means (e.g. abutment) for enabling a differential level of said supported floaters.

A further example of said gravitational dryer means comprises at least one drainage aperture for said collection chamber, which aperture becomes raised above the level of said lagoon as a result of suitable adjustment in buoyancy of said first and or second floatation means and our ascent of said floor. In general, said extractor means can be embodied in any suitable manner(s).

At least one optional extractor means can be provided for aiding or enabling extraction via said outlet of said supported floaters. Said extractor means can be embodied in any suitable manner(s).

For example, at least one suction extractor can be adapted to blow or suck at least some said supported floaters. Furthermore, at least one portion of said floor can be adapted to be utilised as said extractor means, e.g. when that floor portion passes out of said outlet, when said floor is required to exit from said outlet.

It should be noted that said floor can extend out of said inlet and/or out of said outlet, when required. For example, when said floor is a conveyor belt, drive means for that belt can be located outside said collection chamber.

In the accompanying drawings, which are given by way of schematic example of the present invention: Figure 1 shows one embodiment of recovery apparatus for recovering floaters.

Figure 2 is a sectional view showing a lowered mode of apparatus of Figure 1.

Figure 3 is a sectional view showing a raised mode of apparatus of Figure 1.

Figure 4 is a detail of a floor in apparatus of Figure 1.

Figure 5 is a detail of an alternative floor of apparatus of Figure 1.

Figure 6 is a sectional view of an alternative roof of apparatus of Figure 1.

In Figure 1 a lagoon 1 (e.g. a right angled lagoon) has an entry pipe 2 for pumping into the lagoon, water containing pulverised fuel ash including floaters 3. At an end or other portion of the lagoon is recovery apparatus 10 for recovering floaters. That apparatus contains a longitudinal collection chamber 11 having an inlet 12 for receiving floaters from outside inlet 12, the other end of chamber 11 having an outlet 13 for allowing discharge of floaters from chamber 11. At opposite sides of chamber 11 are respectively floatation chamber 21 and floatation chamber 31. Both of chambers 21, 31 are bottomless and have their lower portions immersed in lagoon water, so as to contain ballast water which can be discharged suitably from those chambers by charging sufficient air into the upper portions of those chambers. This air can be controlled in any suitable manner(s) not shown.Chambers 21, 31 are respectively attached to or constitute opposite side walls of collection chamber 11, such that when chambers 21, 31 are sufficiently submerged they will lower collection chamber 11, e.g. to a location as shown in Figure 2, sufficient to enable floor 14 in collection chamber 11 to be submerged and under floaters that have entered collection chamber 11 via inlet 12.

Sufficient ascent of chambers 21, 31 by admission of air thereinto raises floor 14 above the level of the lagoon, e.g. to a location as shown in Figure 3, such that said entered floaters become supported on said raised floor 14 and undergo gravitational drainage of at least part of their water content.

Floor 14 is movable to convey said supported floaters to and/or out of inlet 13, for discharge of those floaters. Floor 14 can be a conveyor belt having opposite ends, or an endless conveyor (Figure 4).

Floor 14 is on rollers 15 (Figure 4) or on a grid or platform 16 (Figure 5).

Collection chamber 11 has a pitched roof which can be ridged roof 17 (Figure 1) or domed roof 18 (Figure 6). Roof 17 is permanently or removably attached to floatation chambers 21, 31. Roof 18 is resiliently sprung into location between and abutting floatation chambers 21, 31. Roof 17 or roof 18 is sufficiently transparent to admit to chamber 11 some solar radiation which can be utilised to evaporate at least a portion of the water content of said supported floaters. Optional guttering 19 is provided (Figure 1) for discharging condensed water that has collected therein from the underneath of roof 17. Similar guttering 20 is provided (Figure 2) for roof 18 by optionally inwardly turning of the lower ends of roof 18.

Optional sucker extractor 40 (e.g. a SUPER SUCKER apparatus; SUPERSUCKER is a trade name) is coupled to outlet 13 so as to create suction for extracting at least a portion of said supported floaters, and also providing at least some drying of said supported floaters.

The apparatus of the accompanying drawings can be embodied in any suitable manner(s) utilising the disclosures given above before the first reference to the accompanying drawings.

The present invention can utilise, to any extent that is appropriate, the contents of our UK patent application 8320953, all of whose contents are to be regarded as being imported into the above description.

Claims

1. Apparatus for recovering floaters from a lagoon of water, said apparatus comprising: (a) at least one collection chamber having at least one inlet for receiving floaters from outside said at least one inlet, at least a portion of those receivable floaters being optionally impellable by external wind into said chamber, said chamber optionally having at least one outlet for removing floaters from said chamber, wherein said chamber comprises a submersible floor, said floor being raisable above the level of lagoon water so as to raise and support above that level at least some of said floaters which have entered said chamber; (b) first and second floatation means between which is located said chamber, said first and second floatation means having adjustable buoyancy so as to enable said floor to become submerged or raised above the level of lagoon water.

2. Apparatus as claimed in claim 1, wherein the ratio of maximum free height H to width W of a cross section of said chamber is HiW = (2.0 to 2.5 metres)/(0.15 to 0.75 metres).

3. Apparatus as claimed in claim 1 or 2, wherein said chamber is not partitioned.

4. Apparatus as claimed in claim 1 or 2, wherein said chamber is partitioned.

5. Apparatus as claimed in claim 4, wherein said chamber is partitioned to provide at least one compartment having an appropriate portion of said floor.

6. Apparatus as claimed in claim 5, wherein said chamber has a continuous partition.

7. Apparatus as claimed in claim 5 or 6, wherein said chamber has a discontinuous partition.

8. Apparatus as claimed in claim 7, wherein said discontinuous partition is apertured to enable communication between adjacent said compartments.

9. Apparatus as claimed in any one of claims 1 to 8, wherein said chamber has at least one said inlet and at least one said outlet.

10. Apparatus as claimed in claim 9, wherein said chamber has a said inlet and a said outlet, and is longitudinal between said inlet and said outlet thereof.

11. Apparatus as claimed in any one of claims 1 to 10, comprising at least one first guide means, for directing into and/or towards said inlet, floaters for entry into said chamber.

12. Apparatus as claimed in claim 11, wherein at least one said first guide means is adapted to converge into and/or towards said inlet at least a portion of said receivable floaters.

13. Apparatus as claimed in claim 11 or 12, wherein a said first guide means comprises at least one suitably orientated abutment on the surface of the lagoon.

14. Apparatus as claimed in claim 13, wherein a said first guide means comprises a floating boom, or a suspended chain, or a wail extending suitably upwardly from the bed of the lagoon.

15. Apparatus as claimed in any one of claims 1 to 14, comprising at least one gate means for gating said inlet so that receivable floaters can enter said inlet but not return outwardly.

16. Apparatus as claimed in claim 15, wherein said gate means comprises flap(s), sluice(s), or weir(s).

17. Apparatus as claimed in any one of claims 1 to 16, comprising at least one second guide means, for directing into and/or towards said outlet, floaters to be discharged via that outlet.

18. Apparatus as claimed in claim 17, wherein at least one said second guide means is adapted to aid or enable at least a portion of said received floaters at least partly to rise towards said outlet.

19. Apparatus as claimed in claim 18, wherein at least one said second guide means comprises at least one suitably oriented abutment.

20. Apparatus as claimed in claim 19, wherein at least one said second guide means comprises a ramp.

21. Apparatus as claimed in any one of claims 1 to 20, wherein said floor is movable in at least one conveyor direction for said supported floaters.

22. Apparatus as claimed in claim 21, wherein said floor comprises a conveyor web.

23. Apparatus as claimed in claim 22, wherein said web is apertured for gravitational drainage of water from said supported floaters.

24. Apparatus as claimed in any one of claims 1 to 23, comprising at least one support means for supporting said floor.

25. Apparatus as claimed in any one of claims 1 to 24, when according to claim 22 or 23, comprising at least one guide means for guiding conveyor motion of said movable floor.

26. Apparatus as claimed in any one of claims 1 to 25, wherein at least one said floatation means comprises a respective floatation chamber.

27. Apparatus as claimed in claim 26, wherein a said floatation chamber is an inflatable floatation chamber.

28. Apparatus as claimed in claim 26 or 27, wherein a said floatation chamber is a ballast water chamber from which ballast water can be discharged or into which ballast water can be charged.

29. Apparatus as claimed in claim 28, wherein said ballast water chamber has an open bottom for immersion in the lagoon.

30. Apparatus as claimed in any one of claims 1 to 29, wherein said first and second floatation means are respectively attached to and/or constitute corresponding portions of said collection chamber.

31. Apparatus as claimed in any one of claims 1 to 30, comprising (c) a roof adapted to admit ra radiation into said collection chamber so as to provide heat for evaporating at least a portion of water from said supported floaters.

32. Apparatus as claimed in claim 31, wherein said roof is permanently located.

33. Apparatus as claimed in claim 31, wherein said roof is removably located.

34. Apparatus as claimed in claim 33, wherein said removable roof is adapted to be sprung into location.

35. Apparatus as claimed in any one of claims 31 to 34, wherein said roof is attached to said first and second floatation means.

36. Apparatus as claimed in any one of claims 30 to 35, wherein said roof is shaped to aid or enable motion of water condensed onto the underneath of that roof.

37. Apparatus as claimed in claim 36, comprising drainage means for receiving condensed water from the underneath of said roof.

38. Apparatus as claimed in any one of claims 30 to 37, wherein said roof has an upward pitch.

39. Apparatus as claimed in claim 38, wherein said pitch is provided by a ridged roof.

40. Apparatus as claimed in claim 38, wherein said pitch is provided by a domed roof.

41. Apparatus as claimed in any one of claims 30 to 40, wherein said roof in continuous.

42. Apparatus as claimed in any one of claims 1 to 41, wherein said roof is discontinuous.

43. Apparatus as claimed in claim 42, wherein said roof is apertured for enabling at least a portion of wind to enter and/or exit from said collection chamber, that wind optionally having a drying action on at least some said supported floaters in that chamber.

44. Apparatus as claimed in any one of claims 30 to 43, wherein said roof comprises plastics or other polymeric material.

45. Apparatus as claimed in any one of claims 1 to 44, wherein said roof is in the form of a membrane or sheet.

46. Apparatus as claimed in any one of claims 1 to 45, comprising at least one dryer means for removing in said collection chamber at least a portion of water from said supported floaters.

47. Apparatus as claimed in claim 46, wherein said at least one dryer means comprises gravitational dryer means.

48. Apparatus as claimed in any one of claims 1 to 47, comprising at least one extractor means for aiding or enabling extraction via said outlet of said supported floaters.

49. Apparatus as claimed in claim 48, wherein said at least one extractor means comprises at least one suction extractor.

50. Apparatus as claimed in claim 1, substantially as hereinbefore described with reference to and as shown in Figures 1 to 3 of the accompanying drawings.

51. Apparatus as claimed in claim 50, substantially as hereinbefore described with reference to and as shown in Figure 4 of the accompanying drawings.

52. Apparatus as claimed in claim 50, substantially as hereinbefore described with reference to and as shown in Figure 5 of the accompanying drawings.

53. Apparatus as claimed in claim 50, substantially as hereinbefore described with reference to and as shown in Figure 6 of the accompanying drawings.

54. A method for recovering floaters from a lagoon, comprising utilising apparatus according to any one of claims 1 to 53.

55. Floaters, recovered by apparatus according to any one of the claims 1 to 53, or by a method according to claim 54.