GB2583165A

GB2583165A - Apparatus and method for capturing airborne contaminants

Info

Publication number: GB2583165A
Application number: GB2001134.2A
Authority: GB
Inventors: Perry Brian; Martyn Melling Charles; White Andrew; Thomas Cottage Michael
Original assignee: AQUATEN Ltd
Current assignee: AQUATEN Ltd
Priority date: 2019-01-25
Filing date: 2020-01-27
Publication date: 2020-10-21
Also published as: GB202001134D0; GB201901082D0

Abstract

A filter for capturing airborne contaminants comprises a rigid frame (12, figure 1) and a filter cartridge 14. The cartridge 14 comprises a sheet of activated carbon 30 between two perforated supporting panels 32, e.g. a grill or woven or welded mesh. The sheet of activated carbon 30 may be non-woven fabric made up of strands of activated carbon and may also include granulated or powdered carbon; it may also comprise a fire retardant scrim layer. The supporting panels 32 may be corrugated and the peaks may face each other, pinching the sheet of activated carbon 30. The frame 12 may comprise tamper-proof fasteners 42 and mounting members 24. Multiple frames 12 may be mounted by tamperproof fasteners onto roadside barriers, railings or fences in built up areas, to help provide cleaner air. Dirty cartridges 14 may be removed from the frame 12 for regeneration e.g. by heating and/or washing.

Description

APPARATUS AND METHOD FOR CAPTURING AIRBORNE CONTAMINANTS

FIELD OF THE INVENTION

The invention relates to an apparatus and method for capturing airborne contaminants.

The invention is expected to find its greatest utility in relation to the capturing of to airborne pollution such as chemicals and particulate matter in built-up areas and the following description will relate primarily to those applications. The invention is nevertheless not limited to those applications.

Notwithstanding that the apparatus and method are intended for capturing airborne contaminants, it is recognised that some airborne contaminants might initially be captured by rain drops; if those rain drops subsequently fall onto the apparatus at least some of the contaminants will be deposited and captured by the apparatus. The apparatus is therefore expected to be useful primarily for extracting contaminants directly from the air, but is also useful for extracting contaminants indirectly from the air by way of raindrops or other moisture.

BACKGROUND TO THE INVENTION

Airborne pollution is a widespread concern, particularly in built-up areas. Motor vehicles are a major cause of airborne pollution, but factories, other industrial sites and household wood-burning stoves are also known to be significant sources of airborne pollution. These sources are all more likely to be present and/or are present in greater densities in built-up areas and the problem of poor air quality which the present invention seeks to address is therefore more acute in those areas.

Airborne pollution is particularly dangerous as is it generally invisible and the polluting chemicals and particulates are often breathed directly into the lungs. Prolonged or repeated exposure to airborne pollution is often required before the harmful effects are noticeable, and the harmful effects may by then be irreversible.

Bronchial and respiratory illnesses are known to be caused by and/or exacerbated by airborne pollution -a study by King's College London in 2015 found that nearly 9,500 people die each year in London alone because of airborne pollution.

The contaminants of particular concern are identified as PM2.5 and PM10, i.e. particles with an average size of 2.5pm and 10pm respectively. Particulates of this size are known to be created by the engines of motor vehicles, the brakes and tyres of motor vehicles, wood burning stoves and construction sites for

is example.

Activated carbon is known to be useful in trapping contaminants, including polluting contaminants, the contaminants being adsorbed onto the surface of the activated carbon by way of electrostatic attraction and thereby being removed from the air or other carrier. One of the reasons why activated carbon is so beneficial is that it has a very large internal surface area, in some examples between 1,000 and 1,200 square metres per gram. Activated carbon is available from many manufacturers and is commonly made from nutshells, coconut husk or coir.

Another advantage of activated carbon is that it is a "passive" contaminant collector, i.e. power is not required to create the electrostatic charge by which the contaminants are captured, and it is not necessary to create a flow of contaminants past or through the activated carbon.

SUMMARY OF THE INVENTION

The inventors have sought to provide an apparatus and method for capturing airborne contaminants which can readily be used in built-up areas, including adjacent to particularly vulnerable locations such as schools and the like. The inventors make use of existing structures such as roadside barriers, railings, fences and the like to mount the apparatus in the chosen location.

According to the invention there is provided an apparatus for capturing airborne to contaminants comprising a substantially rigid frame, a cartridge removably mounted to the frame, the cartridge comprising a sheet of activated carbon sandwiched between two perforated supporting panels.

The rigid frame is designed to be substantially permanently mounted at the is location of use (for example upon fencing between a school and a road). A dirty or contaminated cartridge can be removed from the frame at periodic intervals and replaced by a clean or decontaminated cartridge, the removed cartridge being taken to a specialised facility for removal of the contaminants. The contaminants can typically be removed by heating the sheet of activated carbon and/or by washing the contaminants out of the sheet.

It is recognised that a sheet of activated carbon can be cleaned and reused many times, the captured contaminants ideally being safely disposed of at the specialised facility.

The inventors therefore provide the activated carbon in a sheet form, the sheet being relatively thin and having a relatively large external surface area. The sheet is ideally a non-woven fabric made up of strands of activated carbon. The inventors recognise that a sheet of relatively thin activated carbon is not self-supporting. By sandwiching the activated carbon sheet between two supporting panels the whole cartridge becomes self-supporting and can be installed into and removed from the frame relatively quickly and easily and without significant distortion. The supporting panels are perforated to permit the air surrounding the apparatus to engage the activated carbon sheet so that airborne contaminants can be captured by the activated carbon.

The capacity of the cartridge can be varied to suit the application, for example by adjusting the level of carbon in the sheet. For example, a particular manufacturer can provide activated carbon sheets with 120 grams of carbon per square meter or 240 grams of carbon per meter as required. Also, the capacity can be varied by utilising granulated carbon or powdered carbon.

to One supplier of the activated carbon sheet is Lantor UK, of 73 St. Helens Road, Bolton, BL3 3PR, UK.

Preferably the frame is of metal. Preferably also the frame comprises a general U-shape with two side edges and a bottom edge. The bottom edge and side edges are ideally of channel section with the channel being open towards the centre of the frame so that the edges can accommodate the peripheral lip at the bottom and sides of the cartridge.

Desirably the cartridge is secured to the frame by way of a top edge of the apparatus. The cartridge preferably includes the top edge, i.e. the top edge of the apparatus is integral with one or both of the supporting panels. Alternatively, the top edge of the apparatus is a separate component, which can be fitted to the frame to secure the cartridge; ideally the top edge is a channel section with the channel open towards the cartridge whereby to accommodate the peripheral lip at the top of the cartridge.

Ideally the top edge of the apparatus is temporarily securable to the side edges. Preferably, releasable fasteners are used to secure the top edge of the apparatus; desirably the releasable fasteners are tamper-proof or otherwise require specialised tools for removal. It is therefore intended that only authorised personnel will be able to remove the top edge and therefore remove and replace the cartridge.

Desirably the supporting panels are of metal or plastic. Desirably the proportion of material to open space in the supporting panels is between around 35% and around 65%. The supporting panels may comprise a grill in which the perforations are provided by punched or otherwise formed holes through the material. Alternatively, the supporting panels may comprise a mesh, perhaps a woven or welded mesh. The term "perforated" is used herein to embrace the alternative structures in which the supporting panels comprise a combination of material and openings.

io The supporting panels may be corrugated or otherwise formed with creases and/or folds, it being recognised that a corrugated or otherwise deformed panel is usually more rigid than a flat panel made from the same material. Corrugated or otherwise deformed supporting panels can therefore be used to reduce the weight of the cartridge.

With corrugated supporting panels the wavelength and amplitude of the corrugations of both supporting panels are preferably the same. Desirably the two supporting panels are identically formed. This reduces the number of different components which are required to manufacture the apparatus. Preferably also, the peaks of the corrugations of one of the supporting panels preferably face the peaks of the corrugations of the other supporting panel (and the troughs are similarly aligned). This results in a cartridge in which the activated carbon sheet is engaged by both of the supporting panels along the peaks of the corrugations, and not being engaged by the supporting panels at the troughs.

Ideally the wavelength of the corrugations is around 15 cm. Ideally also the corrugations are substantially horizontal in use (i.e. the peaks are substantially aligned with the bottom edge of the frame). In such embodiments the activated carbon sheet is directly supported at 15 cm intervals up the cartridge. Clearly, in alternative embodiments the corrugations could be vertical in use, or at an angle between horizontal and vertical, as desired. Also, the wavelength can be varied depending upon the inherent rigidity of the activated carbon sheet used in a particular cartridge.

Accordingly, in preferred embodiments the activated carbon sheet is held substantially flat between the supporting panels, with a significant proportion of the activated carbon sheet not being directly engaged or supported (i.e. a significant proportion lies freely between facing troughs of the supporting panels). The facing troughs of the supporting panels therefore create an open volume adjacent to the activated carbon sheet within which air can move and circulate (perhaps due to ambient wind or the draught of passing traffic), increasing the likelihood that airborne contaminants will be captured by the activated carbon.

Preferably, there is at least one mounting member fixed to the frame, and ideally there are two similar mounting members fixed to the frame. Preferably the mounting members are fixed to both of the side edges of the frame and span the width of the frame. Desirably, the mounting member(s) are cranked adjacent their is ends. The provision of cranked mounting member(s) allows the installed cartridge to be spaced from the article to which the frame is mounted. This can be advantageous in practice because the article to which the apparatus will be mounted might be railings or the like with an overhanging handrail. The cranked mounting member(s) cause the cartridge to be out of alignment with the overhanging handrail and thereby avoid the cartridge fouling the handrail as it is removed and inserted into the frame.

Preferably, an elongated mounting bar is adapted for fixing to the or each mounting member. The provision of an elongated mounting bar, together with a mounting member which spans the distance between the side edges of the frame, results in a very adjustable mounting means for the frame, adaptable to a wide variety of mounting locations. For example, if the frame is to be mounted to an existing fence an elongated (horizontal) mounting bar and elongated (horizontal) mounting member permit the secure mounting of the frame largely regardless of the spacing between the (vertical) fence members.

There is also provided a method of capturing airborne contaminants comprising the following steps: {4 procuring an apparatus as herein defined; {ii} mounting the frame at a chosen location and inserting a cartridge into the frame; {iii} after a chosen interval removing the cartridge and replacing it with a fresh cartridge; {iv} taking the removed cartridge to a facility to remove the captured contaminants; {v} repeating steps {iii} and {iv} at periodic intervals.

io The removal intervals for contaminated cartridges are preferably determined by the degree to which the activated carbon becomes contaminated. Ideally the activated carbon sheet should be removed before it becomes sufficiently loaded with contaminants that its performance drops significantly. The time taken for that will depend upon the capacity of the cartridge and the location of use and can be determined either by calculation or by experiment.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will now be described in more detail, by way of example, with reference to the accompanying schematic drawings, in which: Fig.1 shows a front perspective view of the apparatus of the invention; Fig.2 shows a rear perspective view of the apparatus of the invention; and Fig.3 shows an enlarged vertical cross-section through the apparatus.

DETAILED DESCRIPTION

The apparatus 10 for capturing airborne contaminants comprises a substantially rigid frame 12 into which a cartridge 14 is removably mounted.

The frame comprises a first side edge 16, a second side edge 18 and a bottom edge 20. The side and bottom edges 16, 18, 20 are metallic channel sections and are substantially rigid. The side and bottom edges 16, 18, 20 together form a substantial U-shape in use, and it is intended that the frame 12 in use be oriented as shown in the drawings, i.e. with the side edges 16 and 18 substantially vertical and the bottom edge 20 substantially horizontal (although the orientation is not important to the performance of the invention).

io The channel sections forming the side and bottom edges 16, 18, 20 are all open towards the cartridge 14, so that as seen in Fig.3 the bottom edge 20 provides an upwardly open channel into which the peripheral lip 22 at the bottom edge of the cartridge 14 can rest. Though not shown in the drawings, it will be understood that the side edges 16 and 18 are similarly channels which are open towards the is peripheral lip at the respective side edges of the cartridge 14. The side edges 16 and 18 act as guides during the insertion and removal of the cartridge 14 from the frame 12, and also act to retain the peripheral lip at the sides of the inserted cartridge.

The rear of the frame 12 has two mounting members 24. In this embodiment the mounting members 24 are identically formed and are therefore given the same reference numeral. Each mounting member 24 has three fastener holes 26 formed therethrough.

The apparatus 10 also includes two linear mounting bars 28 (of which only one is shown in Fig.2) which are long enough to span all of the fastener holes of a respective mounting member 24. Each mounting bar 28 has corresponding fastener holes 26 formed therethrough.

The frame 12 can be secured to a structure at the location of use, suitably a securely fixed railing, fence or the like. A railing or fence will typically have a number of uprights at intervals therealong (for example metal fence members spaced at 12 cm intervals). It will be understood that the mounting members 26 can be placed to one side of the uprights and the mounting bar 28 to the other side of the uprights. Suitable fastenings can pass through the respective fastener holes 26 and tightened to securely sandwich the uprights between the mounting members 26 and the mounting bars 28, and thereby secure the frame 12 in position upon the railing or fence.

In this embodiment the overall distance between the endmost fastener holes 26 is around 1 metre. The mounting members 24 and mounting bars 28 therefore span many uprights and substantial adjustment is available in the precise positioning of in the frame 12 relative to the uprights. It is expected to be relatively easy to ensure that the positioning is such that a fastening can be passed through each pair of fastener holes 26 without fouling an upright.

It will be understood that the alternative embodiments could utilise only one 15 mounting member, and other embodiments could utilise three or more mounting members. Two mounting members are, however, preferred, as this is believed to provide the best compromise between security and cost.

The mounting members 24 are cranked so that the region with the fastener holes 26 is spaced from the plane of the side and bottom edges 16, 18, 20. The primary purpose of this is to move the cartridge 14 away from the fence or railing to which the frame is mounted, and thereby to move the cartridge out of alignment with any overhanging handrail or the like.

It will be understood that the cranked mounting members also permit the frame 12 to be secured to a solid structure such as a wall, the cranked mounting members ensuring that there is an air gap behind the cartridge 14 when installed. The provision of an air gap behind the cartridge is expected to be beneficial in many applications, but is not essential (and indeed the activated carbon sheet could in some circumstances be affixed directly to a surface, perhaps by adhesive for example). In one alternative, a modified frame without the mounting members 24 could be secured directly to a flat surface such as a wall if necessary or desired for a particular application and such mounting will not reduce the adsorbent capacity of the cartridge. It is nevertheless desired to mount the frame 12 to an open structure such as railings or a fence so as to maximise the airflow at the front and rear of the cartridge.

The cartridge 14 comprises a sheet of activated carbon 30 sandwiched between two perforated supporting panels 32. In this embodiment the supporting panels 32 are identical and so are given the same reference number, but in alternative embodiments the supporting panels are not identical.

io As best seen in Fig.3, each supporting panel is corrugated. In this embodiment the corrugations are horizontal, i.e. they are substantially aligned with the bottom edge 20 of the frame 10, but in other embodiments the corrugations are vertical.

The peaks of the corrugations of one of the supporting panels 32 face the peaks is of the corrugations of the other supporting panel 32. The sheet of activated carbon 30 is substantially flat and is "pinched" between the supporting panels at the summits of each of the peaks. The clamping force upon the sheet of activated carbon 30 is small and does not significantly distort the sheet. The clamping force need be sufficient only to ensure that the sheet 30 away from the peaks of the corrugations (i.e. where it is not directly supported) does not collapse under its own weight (even if it should become wet through rainfall).

The supporting panels 32 are perforated across substantially their full area (Figs. 1 and 2 show only some of the many perforations). In this embodiment the only regions which are not perforated are those at the peripheral lip around the outer edge of the cartridge. In this embodiment the supporting panels 32 are respective sheets of metal which are deformed into a corrugated form and with holes punched or otherwise formed therethrough. In one embodiment the punched holes are around 1 cm in diameter and are arranged in a triangular array with 1.5 cm between adjacent hole centres.

Other embodiments can have larger or smaller holes formed therethrough, the holes can be differently shaped and/or arrayed, and the holes can be closer together or farther apart, as desired. It is desired, however, that the total hole area comprises between around 35% and around 65% of the total surface area of the supporting panels 32, so that air can readily flow through the supporting panels 32 and engage the activated carbon sheet 30.

It will be seen from Fig.3 that the regions between the facing troughs of the corrugations provide a number of open volumes 34 adjacent to the sheet of activated carbon 30. Air within those open volumes can circulate due to air currents caused by the ambient wind or by passing traffic, so that the likelihood of to the air engaging the activated carbon sheet 30 is significant, with the result that the airborne contaminants can be captured. Air can readily flow into and out of the volumes 34 through the perforations in the supporting sheets 32.

In other embodiments the supporting panels comprise a mesh. The mesh can be is formed by woven or welded strands, as desired. The detailed structure and material of the supporting panels is therefore not important, provided that the panels can maintain the desired shape of the activated carbon sheet (even when the sheet is wetted by rainwater and loaded with contaminants). It is also necessary that the panels are sufficiently rigid to provide a self-supporting cartridge 14, i.e. when the cartridge is removed from the frame 12 it should not collapse or distort under its own weight since that could damage the activated carbon sheet 30.

In this preferred embodiment the cartridge 14 includes a top edge 36 of the apparatus 10, i.e. the top edge 36 is securely fixed to the peripheral lip 40 of the cartridge 14. The top edge 36 is secured to the side edges 16, 18 by releasable fastenings 42 (Fig.3); when the fastenings 42 are removed the top edge 36, supporting panels 32 and activated carbon sheet 30 are removed together. This minimises the number of separate parts and is expected to make the removal and replacement of a cartridge easier in practice. In this embodiment the top edge 36 is also of channel section and substantially matches the channel sections of the side and bottom edges 16, 18, 20.

In an alternative embodiment the top edge is separate from the cartridge, for example a separate channel shaped component which can locate and secure the peripheral top edge of the cartridge. In such embodiments the top edge is released from the remainder of the frame and the cartridge is subsequently removed from the frame 12.

When the cartridge is installed as shown in Figs. 1 and 2 the channel sections forming the four edges 16, 18, 20 and 36 together completely surround the activated carbon sheet 30 and the supporting panels 32.

In use it is expected that a number of frames 12 will be installed at a chosen location. For example, ten frames 12 could be mounted along a fence between a school playground and a road. A cartridge 14 is inserted into each frame 12. At periodic intervals the cartridges 14 can be removed and taken to a specialised is facility for cleaning. As a contaminated cartridge is removed a replacement (clean) cartridge can be inserted in its place.

The cartridge 14 will preferably be disassembled at the specialised facility, i.e. the supporting panels 32 will be separated from the activated carbon sheet 30. It is expected that the activated carbon sheet 30 can be more easily and thoroughly cleaned when separated from the supporting panels 32. In one embodiment the supporting panels 32 are clipped together at selected intervals around the peripheral lip, the clips requiring dedicated or specialised tools for removal.

It is desirable that the fastenings 42 for securing the top edge 36 to the side edges 16,18, and also the fastenings for the mounting members 26, are tamper-proof so that the cartridge 14 (and also the frame 12) cannot easily be removed by an unauthorised person.

In a preferred embodiment the cartridge 14 is around 1.5 metres wide by around 1 metre high, but the precise dimensions can be altered as desired. It will be appreciated that the front supporting panel (i.e. opposite to the mounting members 24) provides a surface upon which images and writing can be displayed.

Thus, notwithstanding that the surface is perforated, the material between the perforations can be decorated or marked so as to increase the aesthetic appeal of the apparatus, or to carry advertising or the like. Despite the perforations images and writing can be visible, and discernible, from a sufficient distance. The surface 5 might, for example, be decorated with the logo or name of a person or company which pays for the installation and which thereby advertises its involvement. In those embodiments with corrugations, it can be arranged that different parts of the corrugations are decorated differently so that the image changes as the viewer moves relative to the apparatus (which is expected to have greater utility with to embodiments having vertical corrugations).

Alternative embodiments can include a fire retardant scrim layer bonded to the activated carbon sheet 30. Such an additional layer will provide some resistance to fire, and will also provide a layer which can be decorated as by printing. Writing is and images could therefore be printed onto the supporting panel 32 and/or onto the underlying fire retardant layer, as desired, perhaps to form a more continuous and complete image than is available from the supporting panel alone.

Claims

CLAIMS1. An apparatus for capturing airborne contaminants comprising a substantially rigid frame and a cartridge removably mounted to the frame, the cartridge comprising a sheet of activated carbon sandwiched between two perforated supporting panels.
2. An apparatus according to claim 1 in which the sheet of activated carbon is a non-woven fabric made up of strands of activated carbon.
3. An apparatus according to claim 1 or claim 2 in which the sheet of activated carbon has between approximately 120 and 240 grams of carbon per square meter.is
4. An apparatus according to any one of claims 1-3 in which the sheet of activated carbon includes granulated carbon and/or powdered carbon.
5. An apparatus according to any one of claims 1-4 in which the frame is of metal.
6. An apparatus according to any one of claims 1-5 in which each supporting panel comprises a generally continuous sheet of material which is perforated by way of a number of holes formed through the material.
7. An apparatus according to any one of claims 1-6 in which the proportion of material to open space in the supporting panels is between around 35% and around 65% by area.
8. An apparatus according to any one of claims 1-7 in which the supporting panels are corrugated.
9. An apparatus according to claim 8 in which the peaks of the corrugations of one of the supporting panels face the peaks of the corrugations of the other supporting panel.
10. An apparatus according to claim 8 or claim 9 in which the wavelength of the corrugations is around 15 cm.
11. An apparatus according to any one of claims 1-10 in which the two supporting panels are identically formed.
12. An apparatus according to any one of claims 1-11 in which the frame is of a general U-shape with three substantially linear sides.
13. An apparatus according to any one of claims 1-12 in which the frame comprises three channel sections with the channel(s) being open towards the centre of the frame.
14. An apparatus according to any one of claims 1-3 in which the cartridge is secured to the frame by way of a top edge of the apparatus.
15. An apparatus according to claim 14 in which the top edge is a part of the cartridge.
16. An apparatus according to claim 14 in which the top edge is a separate component to the cartridge.
17. An apparatus according to any one of claims 14-16 in which the top edge is a channel section.
18. An apparatus according to any one of claims 14-17 in which the top edge is secured to the frame by way of releasable fasteners.An apparatus according to claim 18 in which the releasable fasteners are designed to be tamper-proof.An apparatus according to any one of claims 1-19 in which there is at least one mounting member fixed to the frame.An apparatus according to claim 20 in which the mounting member(s) spans the width of the frame.An apparatus according to claim 20 or claim 21 in which the mounting member(s) is cranked adjacent its ends.An apparatus according to claim 21 or claim 22 including an elongated mounting bar adapted for fixing to the mounting member.A method of capturing airborne contaminants comprising the following steps: {i} obtaining an apparatus according to any one of claims 1-23; {ii} mounting the frame at a chosen location and inserting a cartridge into the frame; {iii} after a chosen period of time removing the cartridge and replacing it with a fresh cartridge; {iv} taking the removed cartridge to a facility to remove the captured contaminants; {v} repeating steps {iii} and {iv} at periodic intervals. 19. 20. 21. 22. 23. 24.