GB2556085A

GB2556085A - Screening apparatus

Info

Publication number: GB2556085A
Application number: GB1619539.8A
Authority: GB
Inventors: James Bradley William
Original assignee: Bp Mckeefry
Current assignee: Bp Mckeefry
Priority date: 2016-11-18
Filing date: 2016-11-18
Publication date: 2018-05-23
Anticipated expiration: 2036-11-18
Also published as: GB201619539D0; GB2556085B

Abstract

A screening apparatus for removing plastic, paper, textile materials, vegetation and fat from waste water comprising a trough shaped screen 4 with a plurality of arcuate screening bars 6 equally spaced apart, a support bar 16 mounted to traverse the screen in a reciprocating motion, a plurality of fingers or tines extending from the support bar so the fingers or tines extend through the spaces 8 between the bars to sweep oversize material into a first 12 and second 14 collection region, where the collection regions are located either side of the trough shaped screen. Preferably the fingers or tines are detachably mounted on the support bar such that they can be replaced. Ideally the screening apparatus further comprises one or more water outlets wherein the water outlets may be mounted on the support bar. Preferably a sump is defined below the screen, wherein the sump may communicate with a pump for pumping waste water to a subsequent process or collection region. Ideally the collection regions include a conveying device for dewatering and compacting the waste, wherein the device may be a screw conveyor. Preferably the apparatus is mounted on a trailer with a power supply also mounted thereon.

Description

(71) Applicant(s):

BP McKeefry

114 Grove Road, Swatragh, County Londonderry, BT45 5QZ, United Kingdom (56) Documents Cited:

GB 2242372 A WO 2001/075240 A1 JPH03217525

WO 2008/035990 A WO 1998/033603 A1 (72) Inventor(s):

William James Bradley (58) Field of Search:

INT CL B01D, B07B, C02F, E03F Other: WPI, EPODOC (74) Agent and/or Address for Service:

FRKelly

Mount Charles, BELFAST, Northern Ireland, BT7 1NZ, United Kingdom (54) Title of the Invention: Screening apparatus Abstract Title: Screening apparatus (57) A screening apparatus for removing plastic, paper, textile materials, vegetation and fat from waste water comprising a trough shaped screen 4 with a plurality of arcuate screening bars 6 equally spaced apart, a support bar 16 mounted to traverse the screen in a reciprocating motion, a plurality of fingers or tines extending from the support bar so the fingers or tines extend through the spaces 8 between the bars to sweep oversize material into a first 12 and second 14 collection region, where the collection regions are located either side of the trough shaped screen. Preferably the fingers or tines are detachably mounted on the support bar such that they can be replaced. Ideally the screening apparatus further comprises one or more water outlets wherein the water outlets may be mounted on the support bar. Preferably a sump is defined below the screen, wherein the sump may communicate with a pump for pumping waste water to a subsequent process or collection region. Ideally the collection regions include a conveying device for dewatering and compacting the waste, wherein the device may be a screw conveyor. Preferably the apparatus is mounted on a trailer with a power supply also mounted thereon.

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Screening Apparatus

FIELD OF THE INVENTION

This invention relates to a screening apparatus for removing plastic sheeting, paper, textile materials, vegetation, fat and other oversize solid waste from waste water.

BACKGROUND OF THE INVENTION

Waste water, particularly in sewage works, is frequently contaminated with plastic sheeting and bags, paper and fabric materials, such as nappies, wipes, clothing, and other solid waste products that may enter into the sewage system, for example by being flushed down a toilet. Such materials, hereinafter collectively referred to as “rag”, can cause blockages in the pipework of a sewage handling system and can cause the failure of pumps, valves or other mechanical devices in the sewage handling system. It is therefore desirable to remove such rag from the waste water.

Prior art attempts to remove rag from waste water have generally involved the use of screening devices, wherein the waste water is passed through a sieve or screen which traps the rag and other oversize solid waste. A commonly used design is a bar screen, wherein the waste water passes between closely spaced parallel bars, the bars trapping the rag and other oversize solid material However, a problem with such known screening devices is that the bars rapidly become clogged with rag, requiring frequent, time consuming and costly maintenance to remove such material from the bars. Other solutions are to use macerators to chop up the rag. However, such macerators are costly to run and require frequent maintenance and even when chopped up the rag can still cause problems for downstream processes with the sewage handling system. It is also known to use vibratory screens to remove solid material from waste water. Again, rag in particular is a problem, causing blockage of the relatively small screening apertures in such vibratory screens. It is desirable to remove course rag from waste water before treating the waste water on a vibrating screen to remove finer material (e.g. grit, bone, sand, silt) therefrom.

SUMMARY OF THE INVENTION

According to the present invention there is provided a screening apparatus for removing plastic, paper, textile materials, vegetation and fat from waste water, said apparatus comprising an elongate trough shaped screen defined by a plurality of spaced apart parallel arcuate transversely extending screening bars having screening slots defined therebetween, wherein water and undersize solid material may pass through the screening slots between said screening bars while oversize material, including plastic, paper, textile materials, vegetation and fat, is retained upon said screen, an elongate support bar being mounted to traverse the screen from side to side thereof in reciprocating motion, a plurality of fingers or tines extending from said support bar to extend through respective screening slots between respective pairs of screening bars such that said fingers or tines clear said screening slots and sweep oversize material into first and second collection regions on either side of the screen as the support bar traverses the screen.

Preferably the support bar is mounted above the screen, said fingers or tines depending from the support bar to pass through the screening slots. The fingers or tines may be detachably mounted on the support bar to permit replacement of the fingers or tines, if required due to damage or wear.

The fingers or tines preferably remain within the respective slots within which they move at all times, avoiding any risk or misalignment of the fingers or tines with the slots. The range of motion of the fingers or tines is preferably arranged such that a leading edge of each finger or tine extends beyond the end of the respective slot within which it moves as it reaches the end of its travel in each direction so that any material collected within the respective slot is pushed out of the respective slot to the sides of the screen and into the respective collection region by the respective finger or tine.

Preferably said support bar is mounted to move through an arc over the arcuate upper surface of the screen. In a preferred embodiment a centre of said arc about which the support bar moves is coaxial with the upper surfaces of the arcuate screening bars defining the screen.

The apparatus may further comprise one or more water outlets coupled to a water supply provided for adding water to the screen for washing material on the screen. Said water outlets may be mounted on the support bar. Said water outlets may comprise spray nozzles mounted on, or defined in, one or more spray bars mounted on the support bar, said spray bars being coupled to said water supply.

Preferably a sump is defined below the screen. The sump may include or communicates with a pump for pumping waste water to a subsequent process or collection region. In one embodiment the apparatus may comprise an elongate substantially rectangular tank within which said screen is mounted, a region of the tank below the screen defining said sump, said first and second collection regions being defined in or mounted upon lateral sides of the tank. The support bar may be mounted between support arms pivotally mounted at respective ends of the tank, a double acting ram being associated with one or both of the support arms adapted to swing the support arms to traverse the support bar over the screen.

Each of said first and second collection regions may include a conveying device for conveying collected material into a respective dewatering and compacting device. In a preferred embodiment each conveying device comprises a screw conveyor.

Preferably each conveying device slopes upwardly towards the respective dewatering and compacting device. Each dewatering and compacting device may comprise a chamber having a restricted outlet opening whereby material is compacted within said closed chamber by the respective conveying device before being forced out of said restricted opening thereof. Each closed chamber preferably includes a drain for removing water therefrom as the material is compacted therein. The drain of each dewatering and compacting device may communicate with a common sump beneath the screen.

The apparatus may further comprise means for adding water to each closed chamber and/or each of said first and second collection regions for washing material collected therein prior to dewatering and compacting.

A waste water outlet may be provided above the screen for delivering waste water to be screened onto the screen. The waste water outlet may comprise a lower wall, an upper wall and diverging side walls to define a fan shaped outlet opening. An adjustable deflector plate may be provided adjacent the waste water outlet for controlling flow rate of waste water from the waste water outlet. The deflector plate may be pivotally mounted on the upper wall of the waste water outlet.

In one embodiment the apparatus may be mounted on a trailer to permit it to be transported between sites. A power supply may be mounted on the trailer for powering the apparatus such that the apparatus comprises a self contained unit.

BRIEF DESCRIPTION OF THE DRAWINGS

A screening apparatus in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which :15

Figure 1 is a side view of a screening apparatus according to an embodiment of the present invention;

Figure 2 is an end view of the apparatus of Figure 1 with hidden detail shown for 20 clarity;

Figure 3 is a perspective view of an upper part of the apparatus of Figure 1;

Figure 4 is a detailed perspective view of part of the apparatus of Figure 1;

Figure 5 is a detailed perspective view of the underside of the screen of the apparatus of Figure 1 viewed through a maintenance and inspection hatch; and

Figure 6 is a detailed perspective view of an end portion of the apparatus of Figure 30 1.

DETAILED DESCRIPTION OF THE DRAWINGS

A screening apparatus for removing rag from waste water comprises an elongate substantially rectangular tank 2 within which is mounted an elongate trough shaped screen 4 defined by a plurality of spaced apart parallel arcuate transversely extending screening bars 6 having screening slots 8 defined therebetween, wherein water and undersize solid material may pass through the screening slots 8 between said screening bars 6 while rag and oversize material, including plastic, paper, textile materials, vegetation and fat, is retained upon said screen 4. A region of the tank 2 below the screen 4 defines a sump 10. First and second rag collection channels 12,14 are defined in or mounted upon lateral sides of the tank 2 below and on on either side of the screen 4 for receiving rag, as will be described below in more detail. The sump 10 may include or may communicate with a pump for pumping waste water to a subsequent process or collection region.

A support bar 16 is mounted between support arms 18,20 pivotally mounted at respective ends of the tank 2 such that the support bar 16 can traverse the screen 4 from side to side thereof in reciprocating motion. A plurality of fingers 22 depend from the support bar 16 to extend through screening slots 8 between respective pairs of screening bars 6 such that said fingers 22 can clear the screening slots 8 of rag and solid debris while sweeping oversize material into the first and second rag collection channels 12,14 on either side of the screen 4 as the support bar 16 traverses the screen 4. A double acting ram 24,26 is coupled to each support arm 18,20 which can be powered to swing the support arms 18,20 and traverse the support bar 16 over the screen 4. The support bar 16 is mounted to move through an arc over the arcuate upper surface of the screen 4. In a preferred embodiment a centre of said arc about which the support bar 26 moves is coaxial with the upper surface of the screen 4.

The fingers 22 may be detachably mounted on the support bar 16, for example by means of a removable locating pin, to permit replacement of the fingers 22, if required due to damage or wear.

The range of motion of the support bar 16 is such that fingers 22 remain within the respective slots 8 within which they move at all times, avoiding any risk or misalignment of the fingers 2 with the screening slots 8. The range of motion of the fingers 22 is such that a leading edge of each finger 22 extends just beyond the end of the respective slot 8 within which it moves as it reaches the end of its travel in each direction so that any material collected within the respective slot 8 is pushed out of the slot to the sides of the screen and into the respective collection channel

12,14.

A waste water outlet 28 is provided above the screen 4 for delivering waste water containing rag onto the screen 4. The waste water outlet 28 comprises a fan shaped outlet defined by lower wall, an upper wall and diverging side walls to spread the waste water along the length of the screen. An adjustable deflector plate 30 may be provided adjacent the opening of the waste water outlet 28 for controlling the flow rate of waste water onto the screen 4 and/or for spreading in waste water across the screen while minimising splash. The deflector plate 30 is preferably pivotally mounted on the upper wall of the waste water outlet 28, as illustrated best in Figure

2.

At least one spray bar 32 having spray nozzles 34 is mounted on or formed therein is mounted on the support bar 16, such spray bar 32 being coupled to a water supply for adding water to the screen 4 for washing material on the screen 4. In the embodiment shown, two spray bars 32 are provided, one on each side of the support bar 16. As the support bar 16 traverses the screen, water jets from the leading spray bar 32 acts to wash the rag while water jets from the trailing spray bar 32 wash the screen 4.

Each of the rag collection channels 12,14 comprises an upwardly sloping trough leading to an outlet at a rear end of the tank, each channel 12,14 containing a screw conveyor 36 for conveying rag and other solid material collected therein to the outlet of the respective channel 12,14. A dewatering and compacting device 38 is provided at the outlet of each of the first and second rag collection channels 12,14 comprising a closed chamber having a restricted outlet opening 40, said outlet opening 40 being defined by a wall formed from a resilient material having slots cut therein whereby the wall can be deflected outwardly to permit passage of the rag therethrough, such that material is compacted within the closed chamber of each dewatering and compacting device 38 by the action of the respective screw conveyor 36 before being forced out of said restricted outlet opening 40 thereof. Each dewatering and compacting device 38 includes a drain 42 for removing water therefrom as the material is compacted therein. The drain 42 of each dewatering and compacting device 38 may communicate with the common sump 10 beneath the screen 4. Spray bars 44 may be located in the closed chamber of each dewatering and compacting device for adding water to the chamber for washing material collected therein. As such, the rag exits the rag collection channels 12,14 in a substantially washed, dewatered and compacted form suitable for further processing or disposal, for example for incineration, recycling or disposal in land fill.

The apparatus preferably includes a control panel giving the operator the ability to control the speed of the sump discharge pump, the speed of the helical augers in the rag collection channels and the speed of movement of the support bar 16 as it traverses the screen 4 and also allows control of the water supply to the screen and/or rag collection channels/dewatering and compacting devices. A failsafe may be provided adapted to sound an alarm and deactivate the rams if the support bar 16 stops or does not move between two fixed points in a designated time, indicating jamming of the fingers 22 in the screening slots 8.

As shown in Figure 1, the apparatus may be mounted on a trailer 46 to permit it to be transported between sites. A power supply 48 may be mounted on the trailer 46 for powering the apparatus such that the apparatus comprises a self contained unit. In an alternative embodiment the apparatus may be mounted on a fixed chassis or directly on the ground.

The support bar 16 and the fingers 22 mounted thereon define a mechanical rake acting to separate rag from waste water and to clean the slots 8 of the screen 4 from rag, ensuring that the screen 4 does not blind. The apparatus utilises water sprays to clean removed rag prior to compaction.

The apparatus allows one man (or even fully automated unmanned) operation and can accommodate loads with varying rag content. The cleanliness of the removed solids greatly facilitates subsequent disposal.

The apparatus permits a liquid throughput of 90m³ per hour with up to 60% rag content, giving a rag output of 16 tonnes per hour.

A ventilation system may be provided for ventilating noxious gases from the 5 apparatus.

The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention as defined by the appended claims.

Claims

1. A screening apparatus for removing plastic, paper, textile materials, vegetation

5 and fat from waste water, said apparatus comprising an elongate trough shaped screen defined by a plurality of spaced apart parallel arcuate transversely extending screening bars having screening slots defined therebetween, wherein water and undersize solid material may pass through the screening slots between said screening bars while oversize material, including plastic, paper, textile materials,

10 vegetation and fat, is retained upon said screen, an elongate support bar being mounted to traverse the screen from side to side thereof in reciprocating motion, a plurality of depending fingers or tines extending from said support bar to extend through respective screening slots between respective pairs of screening bars such that said fingers or tines clear said screening slots and sweep oversize material into

15 first and second collection regions on either side of the screen as the support bar traverses the screen.

2. An apparatus as claimed in claim 1, wherein the support bar is mounted above the screen, said fingers or tines depending from the support bar to pass through the

20 screening slots.

3. An apparatus as claimed in claim 1 or claim 2, wherein the fingers or tines are detachably mounted on the support bar to permit replacement of the fingers or tines, if required due to damage or wear.

4. An apparatus as claimed in any preceding claim, wherein said support bar is mounted to move through an arc over the arcuate upper surface of the screen.

5. An apparatus as claimed in claim 4, wherein a centre of said arc about which the

30 support bar moves is coaxial with the upper surfaces of the arcuate screening bars defining the screen.

6. An apparatus as claimed in any preceding claim, further comprising one or more water outlets coupled to a water supply provided for adding water to the screen for washing material on the screen.

5

7. An apparatus as claimed in claim 6, wherein said water outlets mounted on the support bar.

8. An apparatus as claimed in claim 7, wherein said water outlets comprise spray nozzles mounted on, or defined in, one or more spray bars mounted on the support

10 bar, said spray bars being coupled to said water supply.

9. An apparatus as claimed in any preceding claim, wherein a sump is defined below the screen.

15 10. An apparatus as claimed in claim 9, wherein the sump includes or communicates with a pump for pumping waste water to a subsequent process or collection region.

11. An apparatus as claimed in claim 8 or claim 10, comprising an elongate

20 substantially rectangular tank within which said screen is mounted, a region of the tank below the screen defining said sump, said first and second collection regions being defined in or mounted upon lateral sides of the tank.

12. An apparatus as claimed in claim 11, wherein the support bar is mounted

25 between support arms pivotally mounted at respective ends of the tank, a double acting ram being associated with one or both of the support arms adapted to swing the support arms to traverse the support bar over the screen.

13. An apparatus as claimed in any preceding claim, wherein each of said first and

30 second collection regions includes a conveying device for conveying collected material into a respective dewatering and compacting device.

14. An apparatus as claimed in claim 13, wherein each conveying device comprises a screw conveyor.

15. An apparatus as claimed in claim 13 or claim 14, wherein each conveying device slopes upwardly towards the respective dewatering and compacting device.

5 16. An apparatus as claimed in any of claims 13 to 15, wherein each dewatering and compacting device comprises a chamber having a restricted outlet opening whereby material is compacted within said closed chamber by the respective conveying device before being forced out of said restricted opening thereof.

10 17. An apparatus as claimed in claim 16, wherein each closed chamber includes a drain for removing water therefrom as the material is compacted therein.

18. An apparatus as claimed in claim 17, wherein the drain of each dewatering and compacting device communicates with a common sump beneath the screen.

19. An apparatus as claimed in claim 17 or claim 18, further comprising means for adding water to each closed chamber and/or each of said first and second collection regions for washing material collected therein prior to dewatering and compacting.

20 20. An apparatus as claimed in any preceding claim, wherein a waste water outlet is provided above the screen for delivering waste water to be screened onto the screen.

21. An apparatus as claimed in claim 20, wherein the waste water outlet comprises

25 a lower wall, an upper wall and diverging side walls to define a fan shaped outlet opening.

22. An apparatus as claimed in claim 20 or claim 21, wherein an adjustable deflector plate is provided adjacent the waste water outlet for controlling flow rate of

30 waste water from the waste water outlet.

23. An apparatus as claimed in claim 22, when dependent upon claim 21, wherein the deflector plate is pivotally mounted on the upper wall of the waste water outlet.

24. An apparatus as claimed in any preceding claim, wherein the apparatus is mounted on a trailer.

25. An apparatus as claimed in claim 24, wherein a power supply is mounted on 5 the trailer for powering the apparatus.

Intellectual

Property

Office

Application No: GB1619539.8 Examiner: Mr Peter Davies