GB2137521A

GB2137521A - Recovery of floaters from pulverized fuel ash

Info

Publication number: GB2137521A
Application number: GB08320953A
Authority: GB
Inventors: David Oakey
Original assignee: MATERIAL RESOURCES Ltd
Current assignee: MATERIAL RESOURCES Ltd
Priority date: 1983-03-11
Filing date: 1983-08-03
Publication date: 1984-10-10
Also published as: GB8320953D0; GB2137521B

Abstract

Floating fuel ash is removed from the surface of water in a lagoon 1 by a device comprising a plastics sheet 11, which is spaced above the water surface by a series of floating partitions 12, thereby defining a series of parallel chambers, each having an inlet A at one end, into which floating ash is driven by the wind, and means, such as a suction extractor 20, for removing the ash at the other end. <IMAGE>

Description

SPECIFICATION Recovery of floaters from pulverized fuel ash At power stations for combusting solid fuel, pulverised fuel 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 overnight 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 the wind and be an environmental problem.

A first aspect of the present invention provides a method of recovering floaters from a lagoon of water, said method comprising: providing said lagoon with at least one cover spaced apart from the surface of lagoon water so as to provide clearance for constituting at least one chamber, said at least one 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 at least partly impelled by external wind into said at least one inlet; and removing said received floaters from said at least one chamber.

A second aspect of the present invention provides apparatus for recovering floaters from a lagoon of water, said apparatus being suitable for carrying out said method of the first aspect of the invention, said apparatus comprising: at least one cover for being spaced apart from the surface of lagoon water so as to provide clearance for constituting at least one chamber, said at least one 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 at least partly impellable by external wind into said at least one chamber.

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

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

Said at least one cover can be constituted in any suitable manner(s). Any said cover can be continuous or discontinuous, e.g. have at least one aperture for enabling at least a portion of wind to enter and/or exit from at least one said chamber, that wind optionally having a drying action on at least some floaters in at least one said chamber. At least a portion of any said cover can be self-supporting or non-self-supporting. Any said cover can be made of any suitable material(s), e.g. of plastics, for instance a plastics membrane or sheet.

At least one said cover can be supported by at least one optional support means whether or not that at least one said cover is self-supporting or non-self-supporting. Said at least one support means can be constituted in any suitable manner(s).

One example of a said support means floats in said lagoon, for instance at least one floating partition between adjacent said chambers. Another example of a said support means extends rigidly upwardly from the bed of the lagoon. At least a portion of at least one said cover can rest on at least one said support means (e.g. at least one wall) and/or be connected thereto, e.g. be integral therewith or be fastened thereto. A further example of a said support means comprises an onshore anchorage, e.g. earth piled onto a cover's margin when that margin is on an earth bank constituting an edge of the lagoon.A preferred support means is floatable and has two floating walls spaced apart and downwardly directed from opposite portions of an interconnecting bight portion, the bight portion optionally being able to support at least one said cover, the walls being at least portions of opposite sides of a said compartment.

Said at least one chamber can be constituted in any suitable manner(s) utilising said at least one cover in vertical cross section, any said chamber can have any suitable shape, e.g. have any suitable aspect ratio interconnecting at least two of its dimensions. For example, the ratio of free height (i.e.

clearance) (H) to width (W) of a said cross section can be H/W = (2.0 to 2.5 metres)/(0.15 to 0.75 metre).

At least one optional partition can separate adjacent chambers. Said at least one partition can be constituted in any suitable manner(s). Any said partition can be continuous or discontinuous, e.g. have at least one aperture for enabling communication between adjacent chambers. A said partition can be at least partly flexible and/or at least partly rigid. At least one said partition can be a portion of at least one said support means or not be a portion thereof.

One example of a said partition floats in said lagoon, for instance at least one said floating wall. Preferably, at least one said chamber is longitudinally extending from at least one said inlet. Preferably, said at least one chamber has at least one outlet for removing floaters from said at least one chamber.

At least one optional gate means can be provided for gating at least one said inlet so that receivable floaters can enter said at least one gated inlet but not return outwardly. Said at least one 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 first guide means can be provided for directing into and/or towards at least one said chamber inlet floaters to be received by that inlet from outside said at least one inlet. Said at least one first guide means can be embodied in any suitable manner(s). At least one said first guide means can be adapted to converge into and/or towards at least one said inlet at least a portion of said receivable floaters. One example of a said first guide means comprises at least one suitably oriented abutment on the surface of the lagoon, for instance a floating boom, or a suspended chain, or a wall extending rigidly upwardly from the bed of the lagoon.

At least one optional second guide means can be provided for directing into and/or towards at least one said chamber outlet floaters to be received by that outlet from the interior of at least one said chamber. Said at least one second guide means can be embodied 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 receiver floaters at least partly to rise towards at least one corresponding said outlet. For example, at least one said second guide means can comprise at least one suitably oriented abutment, e.g. a ramp. The rising of floaters can aid drainage of water from them so that floaters removed will have less water.

At least one optional dryer means can be provided for removing in at least one said chamber at least a portion of water from at least some said received floaters. Said at least one dryer means can be embodied in any suitable manner(s). One example of said dryer means is a said ramp for rising of said received floaters. Another example of said dryer means comprises means for causing an artificial wind in at least one said chamber (e.g. by means of a suction extractor mentioned below).

At least one optional extractor means can be provided for aiding or enabling discharge of floaters from at least one said chamber outlet. Said at least one extractor means can be embodied in any suitable manner(s). For example, at least one said extractor means can be adapted to blow or suck from at least one said outlet at least some said received floaters. Preferably, at least one said extractor provides a suction wind in at least one said chamber.

Preferably, at least some floaters undergo wind and/or other drying in at least one said chamber so that e.g. a bulk purchaser has less water to contend with and thereby can reduce his costs. Thus, at least some floaters can be caused to undergo at least some drying in said chamber, thereby aiding or enabling discaking (if caking has occurred) of floaters in said chamber, and preventing or resisting of caking of floaters in said chamber. That drying can be provided in any suitable manner(s) -see said optional dryer means as one example of that provision. Afurther example of providing at least some said drying is to allow and/or enable gravitational drainage of floaters in a said chamber.Gravitational drainage can be aided or enabled by providing at least one said chamber with adjustable buoyancy so as to raise above the level of the lagoon the floaters in that chamber, the drainage water being suitably removed therefrom, preferably via at least one drainage port that will have become raised above the level of the lagoon, as a result of said adjustable buoyancy. Thus, at least one said chamber can be provided with at least one adjustable buoyancy means (e.g. suitable said support means) for aiding or enabling said adjustable buoyancy; and provided with at least one drainage means (e.g.

drainage port) for discharging drainage water from said chamber. Some examples of adjustable buoyancy means comprise or cooperate with at least one means chosen from at least one of any of: optional bottom(s) and/or optional floor(s), optionally adjustable in disposition; optional partition(s), optionally adjustable in disposition; and wall(s), optionally adjustable in disposition. A said adjustable buoyancy means can be independent of the boundary wall(s) of a said chamber, so as to be elevatable relative to those walls. Preferably, a said buoyancy means cooperates with said boundary wall(s), so as to be elevatable with them, and preferably thereby elevate said chamber.Buoyancy of said adjustable buoyancy means can be adjusted 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) when e.g. a said chamber is inherently sufficiently floatable. Said adjustable buoyancy means can be at least partly rigid and/or at least partly resilient. Preferably, said adjustable buoyancy means comprises at least one vessel (e.g.

a compartment and/or a container), for receiving and/or discharging gas and/or liquid and/or solid, for providing adjustment in buoyancy. An example of a said vessel is a ballast water compartment. Another example of a said vessel is an inflatable chamber.

Provision of said adjustable buoyancy can enable said chamber have any suitable adjustable levels relative to the surface of the lagoon. Provision of said adjustable buoyany can aid or enable control of drainage of water from floaters in said chamber.

That control could control drainage period and/or profile of raise of floaters in a said chamber, e.g. said control could provide a notional ramp to aid exit of floaters from said chamber. The present invention can comprise at least one optional control means for controlling at least a portion of adjustment of buoyancy of said adjustable buoyancy means.

When the underneath of at least one said adjustable buoyancy means can receive floaters from the lagoon (e.g. when a said chamber has risen to allow that), that buoyancy means and/or said chamber can comprise at least one optional abutment to prevent that reception. Some examples of that abutment (which can be at least partly resilient and/or at least partly rigid) are an apron, gate, or skirt, optionally adjustable in disposition (e,g, by hinging and/or resiliency of said abutment).

In general, said apparatus of the present invention can be constituted in any suitable manner(s). Any said chamber and/or any said cover can have any suitable shape(s), configuration(s), or size(s). A said chamber can have any suitable capacity(s) for receiving floaters. A said capacity can be fixed or adjustable (e.g. by utilising said adjustable buoyancy). At least one portion of any said chamber and/or of any said cover can be at least partly submersible (or submersed) in lagoon water, e.g. by utilising said adjustable buoyancy. It is optional for said apparatus to be disposable wholly above, or wholly under, or partly in ,lagoon water, when said apparatus is not in use.

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

Figure 2 shows some adjacent partitions for providing chambers in the apparatus of Figure 1.

Figures 3, 4 show the apparatus of Figures 1,2 when provided with adjustable buoyancy/drainage for floaters in chambers of that apparatus.

In Figure 1, a right angled lagoon 1 has an entry pipe 2 for pumping into the lagoon water containing pulverised fuel ash including floaters. At an end portion of the lagoon is recovery apparatus 10 for recovering floaters. That apparatus contains a roof 11 of continuous plastics membrane betwen banks of the lagoon. Roof 11 is spaced apart from the water of the lagoon. The resulting clearance is partitioned into longitudinal chambers or channels (Figures 1,2, 3, 4) constituted by partitions 12 and the roof 11 that rests on those partitions. Each partition extends longitudinally from the inlets A of the chambers to outlets B of the chambers.In vertical cross section, adjacent chambers have adjacent partitions 12 as shown in Figure 2, each partition 12 respectively containing two walls 13, 14 spaced apart and downwardly directed from opposite portions of an interconnecting bight 15, wall 13 rising upwardly from a float 16, wall 14 rising upwardly from a float 17. Outside the inlet ends A of the chambers are two floating or otherwise provided optional booms 18, 19 providing a converging path forfloatersto enter the inlets A. Optional weirs 20 are provided on the inner sides of the inlet ends A so as to prevent floaters inside said chambers passing out of the inlets A.Optional ramps 21 are provided on the inner sides of outlets B of the chambers so that floaters inside the chambers can rise up and undergo some draining before being extracted by suction extractor 20 (e.g. a SUPERSUCKER apparatus) which can be connected to any one of the outlets B so as to suck floaters out of the corresponding chambers. Floaters on the lagoon water outside the recovery apparatus 10 can be blown by external wind into the inlets A, and be sucked out of the outlet ends B by suction extractor 20. The passage of air through any chamber can produce some drying of fioaters in that chamber. SUPERSUCKER is a trade name.

There could be a plurality of roofs 11 instead of a single roof 11. The roof or roofs can be disposed in any suitable manner(s) relative to e.g. water level and/or water movement. The roof or roofs can extend any convenient distance(s) between opposite banks of the lagoon, e.g. a single roof 11 can be spaced apart from those banks so as to leave open water W (Figure 1). Any said roof can be constituted in any suitable manner(s), e.g. by a continuous plastics or rubber or rubberised membrane or sheet, for instance a membrane or sheet comprising polyvinylchloride or any other suitable polymeric material(s). At least two adjacent roofs could touch each other or be interconnected (e.g. so as to be articulatable relative to each other and/or water level and/or water movement). At least one partition wall 13 or 14 could be a flap or the like connected (e.g. integral with) a roof.Any partition 12 can be at least partly flexible and/or at least partly rigid. A floatable partition can be provided with buoyancy(s) in any suitable manner(s), e.g. comprise at least one floatation means inside and/or outside a said chamber, for instance be at the bottom and/or at a side of a said floating wall 13 or 14.

As the floaters in the chamber(s) pass towards the outlets of the chambers, the layer(s) of floaters on chamber water can increase in depth towards those outlet(s). At least one said wall 13 and/or 14 could increase in depth so as to enable partition 12 to allow for an expected increase in thickness or depth of layer(s) of floaters. Floaters that have risen towards at least one said chamber outlet and are on e.g. said ramp(s) 21 can be sucked off and out of the chamber(s). Sucked off floaters can be in a drained state or be with some chamber water. Suction extractor 20 can be connected to at least one chamber outlet B for at least one period of time. The charging/discharging of water and/or air into or from compartment 19 can be provided in any suitable manner(s), e.g. via at least one circuit (not shown) thereto, comprising any suitable means, e.g. at least one flow way (e.g. a hose ortube), at least one optional compressor, at least one optional pump, and at least one optional valve.

In general, apparatus of the present invention can be embodied in any suitable manner(s), and comprise any optional means suitable for providing a useful function. Various options are described earlier above. A further option is at least one fastener means for fastening at least one said cover into at least one configuration and/or shape (e.g. which can be predetermined). One example of said fastener means comprises a post or the like having at least one tie (e.g. a line or strut) for connection or connected to at least one inlet end portion of at least one said cover. The chamber inlet(s) could be provided with e.g. sluice gate(s) or flap valve(s).

Float 17 could be adjustable in buoyancy.

Figures 3,4 show one example of providing adjustable buoyancy/drainage for aiding or enabling drainage of water from floaters F in the chambers or channels 12. Each of those chambers is provided in Figures 3,4 with a respective floor 18 above a respective adjustable buoyancy compartment 19, which compartment can be resilient and/or rigid.

Floor 18 can be the roof of compartment 19 or abut the top of that roof. Floor 18 can be elevated together with walls 13, 14 secured thereto, when the buoyancy of compartment 19 is suitably adjusted by charged or discharge of ballast water 20 thereto or therefrom, e.g. via an optional port (not shown). The ballast water is lagoon water, and at least a portion thereof can be replaced by air from any suitable source (not shown). The rising of floor 18 (from Figure 3 to Figure 4) with walls 13, 14 causes drainage ports 21 in the walls 13, 14 to rise above the level of the surrounding lagoon 1, whereby water from the floaters in chamber 12 can drain into the lagoon 1 so as to enable at least some drying of those floaters.

Claims

1. Apparatus for recovering floaters from a lagoon of water, said apparatus comprising: at least one cover spaced from the surface of lagoon water so as to provide clearance for constituting at least one chamber, said at least one 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 at least partly impellable by external wind into said at least one inlet, said at least one chamber optionally having at least one outlet for removing floaters from said at least one chamber; and means for removing received floaters from said at least one chamber.

2. Apparatus as claimed in claim 1, wherein at least a portion of at least one said cover comprises a membrane, optionally of plastics or other polymeric material.

3. Apparatus as claimed in claim 1, wherein at least a portion of at least one said cover comprises a sheet, optionally of plastics or other polymeric material.

4. Apparatus as claimed in any one of claims 1 to 3, comprising at least one support means supporting at least one said cover.

5. Apparatus as claimed in claim 4, wherein at least one said support means is floatable in said lagoon.

6. Apparatus as claimed in claim 5, wherein at least one said floatable support means comprises at least one floatable partition between adjacent said chambers.

7. A method as claimed in claim 5 or 6, wherein at least one said floatable support means has two floatable walls spaced apart and downwardly directed from opposite portions of an interconnecting bight portion, said bight portion optionally being able to support at least one said cover, said walls being at least portions of opposite sides of a said chamber.

8. A method as claimed in claim 4, wherein at least one said support means extends rigidly upwardly from the bed of said lagoon.

9. A method as claimed in claim 4, wherein at least one said support means comprises an onshore anchorage.

10. Apparatus as claimed in any one of claims 1 to 9, comprising at least one gate means, for gating at least one said inlet so that receivable floaters can enter said at least one gated inlet but not return outwardly.

11. Apparatus as claimed in claim 10, wherein at least one said gate means comprises flap(s), sluice(s), orwier(s).

12. Apparatus as claimed in any one of claims 1 to 11, comprising at least one first guide means, for directing into and/or towards at least one said inlet floaters to be received by that inlet from outside said at least one inlet.

13. Apparatus as claimed in claim 12, wherein at least one said first guide means comprises an oriented abutment for surface of said lagoon, optionally a floating boom, or a suspended chain, or a wall extending rigidly upwardly from the bed of said lagoon.

14. Apparatus as claimed in any one of claims 1 to 13, comprising at least one second guide means, for directing into and/or towards at least one said outlet floaters to be received by that outlet from the interior of at least one said chamber.

15. A method as claimed in claim 14,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 at least one corresponding said outlet.

16. Apparatus as claimed in claim 15, wherein at least one said second guide means comprises an oriented abutment, optionally a ramp.

17. Apparatus as claimed in any one of claims 1 to 16, comprising at least one dryer means, for removing in at least one said chamber at least a portion of water from at least some said received floaters.

18. Apparatus as claimed in claim 17, wherein at least one said cover comprises at least one aperture constituting dryer means for enabling at least a portion of wind to enter and/or exit at least one said chamber and thereby have a drying action on at least some floaters in at least one said chamber.

19. Apparatus as claimed in claim 17 or 18, wherein at least one said dryer means is adapted for providing an artificial wind in at least one said chamber, optionally by a suction extractor.

20. Apparatus as claimed in any one of claims 17 to 19, wherein at least one said dryer means comprises gravitational dryer means, for allowing and/or enabling gravitational drainage of at least some said received floaters.

21. Apparatus as claimed in claim 20, wherein at least one said chamber has a ramp for raising floaters and thereby constitute at least a portion of said gravitational means.

22. Apparatus as claimed in claim 21, wherein at least one said chamber has adjustable buoyancy constituting at least a portion of said gravitational dryer means, so as to be able to raise above the level of said lagoon the floaters in that chamber, water thereby being able to drain from those floaters.

23. Apparatus as claimed in claim 22, wherein at least one said chamber has at least one gravitational drainage port that will become raised above the level of said lagoon as a result of said adjustable buoyancy, said port constituting at least a portion of said gravitational dryer means.

24. Apparatus as claimed in any one of claims 21 to 23, wherein at least one said chamber comprises at least one ballast water compartment constituting at least a portion of said gravitational dryer means.

25. Apparatus as claimed in claim 24, wherein at least one said chamber has a floor over a said ballast water compartment.

26. Apparatus as claimed in any one of claims 1 to 25, comprising at least one extractor means, for aiding or enabling discharge of floaters from at least one said outlet.

27. Apparatus as claimed in claim 26, wherein at least one said extractor means comprises at least one suction extractor.

28. Apparatus as claimed in claim 1, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

29. A method for recovering floaters from a lagoon of water, said method comprising utilising apparatus as claimed in any one of claims 1 to 28.

30. A method as claimed in claim 29, wherein said lagoon has at least one component of direction to aid passage of floaters into at least one said inlet.

31. A method as claimed in claim 29, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

32. Floaters recovered by apparatus as claimed in any one of claims 1 to 29, or recovered by a method as claimed in claim 30 or 31.