WO2001019541A1

WO2001019541A1 - Method and apparatus for cryogenic blast cleaning

Info

Publication number: WO2001019541A1
Application number: PCT/GB2000/003524
Authority: WO
Inventors: John Pridmore; Harry Sneddon Miller
Original assignee: John Pridmore; Harry Sneddon Miller
Priority date: 1999-09-14
Filing date: 2000-09-14
Publication date: 2001-03-22
Also published as: AU7031100A; GB2370494A; GB0207548D0; GB9921524D0; GB2370494B

Abstract

A hand-held device (2) is utilised for the cryogenic removal and vaccum collection of substances stuck to a surface (18), such as chewing gum (16) stuck to a pavement, walkway or road. A control box (8) is actuated to deliver a blast of dry-ice pellets/air mixture from a central pipe (4) onto the substance to be removed. The substance consequently freezes and becomes hard and brittle, breaking up into smaller fragments. The control box (8) is also actuated to induce suction in pipe(s) (6) simultaneously with the blasting of the substance, so that the fragmented substance is sucked up into the device (2). The device (2) is attached to an engineered skid package (32) mounted in a motor vehicle (24).

Description

METHOD AND APPARATUS FOR CRYOGENIC BLAST CLEANING

This invention relates to a method and apparatus, particularly for the removal of undesirably present material. Until now there has been no fully satisfactory method of totally removing waste chewing gum from pavements and other walkways. Known methods include water jetting and blasting via blast nozzles, steam cleaning and flame lances. Water blasting, water jetting and steam cleaning are relatively expensive operations. Moreover, with a water process, the gum is normally moved to another area where it again hardens to the paving, whilst the removal medium, i.e. water, has to be collected and disposed of with the permission of the relevant governmental environmental body. In addition, water blasting of paved areas causes contaminated water spray which covers adjacent structures and passing pedestrians and the water causes pavements to move and creates a safety hazard. Flame lances use a high temperature flame, are therefore not intrinsically safe and cannot be used on all surfaces.

Various methods of chewing gum removal including use of a freezing agent are also known.

GB-A-2122833 discloses apparatus for cleaning carpets comprising a hub which is rotated at high speed and which carries a plurality of flexible fingers which are made to impinge on the area of the carpet being cleaned. The apparatus may be supported on wheels and may be provided with a handle, a scraper blade, and a nozzle for applying a freezing agent to chewing gum and the like to assist in its removal .

According to JP-A-10-323307, when matter, such as chewing gum, adhered to a floor is to be removed, the adhered matter is covered by a hood for cooling, a predetermined amount of coolant, such as liquid nitrogen or low temperature carbon dioxide gas, is supplied to a coolant discharging nozzle from a coolant storage container of a cooling means through a supply amount regulator to discharge the coolant into the hood through the nozzle to cool and harden the matter so as to bring the matter into an easily crushable condition. Next, a crushing cutter detachably mounted on a crushing cutter holder on a lower end of an elevating and rotatable shaft is rotated to crush the matter. The crushed matter is, after that, sucked by a suction blower to convey the crushed matter into a bag for recovery. In JP-A-8-20923, in order effectively to remove chewing gum from a surface such as a floor surface of a building, pedestrian streets of an underground market and station platforms, an apparatus is provided comprised of a cover with an opening at its lower end for covering chewing gum adhered to the surface, the cover being provided at the lower end of a vertical cylindrical main body. A nozzle for injecting cooling gas downwards is provided at the upper part of the central section of the cover, and a power-driven crusher having a large number of crushing devices moving back-and- forth towards the chewing gum is provided at the inside of the cover. A suction port for sucking the crushed chewing gum is provided, a cooling gas cylinder is provided inside the main body, and an exhaust duct connected to the suction port is connected to a suction port of a vacuum cleaner via a flexible hose.

According to FR-A-266751, sticky substances e.g. chewing gum, or gum arabic, are removed from fabrics by rapid cooling and removal by brushing, sweeping or vacuuming. Cooling is achieved by spraying a refrigerant e.g. (iso-) butane, (iso)- propane, methane (ethane) fluorohalides of boiling point less than 25°C at 1 atmosphere in solution at no higher than 20°C. The proportion of solvent (boiling point less than 130°C) is 0-80% by weight, preferably not greater than 10% at boiling point less than 60°C for 100-20% refrigerant. JP-A-8-107869 discloses that to achieve higher waste collection efficiency, chewing gum is frozen instantaneously so that the gum can be peeled away more easily to be vacuumed away. A liquid nitrogen cylinder and a cartridge-type waste collection bag are carried on a hand truck for transportation. Chewing gum is frozen by the liquid nitrogen, and is vacuumed away to be disposed of.

According to a first aspect of the present invention, there is provided a cleaning method comprising blasting with a cold substance a material undesirably present at a fixed surface and thereby rendering brittle and fragmenting said material so as to render said material easier to remove, said substance comprising solid pellets of a coolant. According to a second aspect of the present invention, there is provided apparatus comprising duct means for applying to a material undesirably present at a surface a blasting jet of cold substance comprised of solid pellets of coolant to render brittle and fragment said material, and pellets-supplying means arranged to supply said pellets to said duct means.

The fixed surface may carry traffic, for example be a road for motor traffic or a pavement for pedestrian traffic, or may be a wall, for example a wall of a building or bounding land, or may be a moving surface, for example a conveyor in a food-production plant, e.g. a bakery, whilst the material may be chewing gum or graffiti paint or chalk for example.

It is particularly advantageous to employ suction to carry away the fragmented material, so that the material need not remain at or adjacent to the surface.

According to a third aspect of the present invention, there is provided in combination, a motor vehicle, power- supplying means of said vehicle, and a unit mounted on said vehicle and comprising a supporting base and power-driven equipment supported by said base, said equipment being connectible to said power-supplying means, and said unit being demountable from said vehicle.

According to a fourth aspect of the present invention, there is provided a method comprising mounting on a motor vehicle a unit comprising a supporting base and power-driven equipment supported by said base, and connecting said equipment to power-supplying means of said vehicle.

Owing to these aspects of the invention, considerable flexibility in use and maintenance of the equipment is possible. Because it is transportable in a motor vehicle, it can be transferred quickly from place to place and either operated from a power supply of the vehicle while mounted on the vehicle, for example while mounted on the floor of a van, or removed from the vehicle and operated from either a power supply of the vehicle or from an independent power supply. In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which :-

Figure 1 is a side view of a hand-held device for applying a cold substance to a surface and constituting part of cleaning apparatus, and Figure 2 is a plan view of a unitary skid package mounted in the rear of a motor vehicle and constituting another part of the cleaning apparatus.

Referring to Figure 1, the hand-held device 2 comprises a central duct in the form of a pipe 4, one or more suction ducts in the form of one or more pipes 6 arranged around the central pipe 4, and a control box 8 connected at one end to adjacent ends of the pipes 4 and 6. The pipes 4 and 6 are fixed together and made of any suitable material such as mild steel or aluminium. At its opposite end the control box 8 is connected to a hose 10 for the delivery of a mixture of compressed air and of frozen carbon dioxide pellets at -110°F (dry ice), to the central pipe 4, and a hose 12 for use in inducing suction in the suction pipe (s) 6. The control box 8 also incorporates an on/off switch 14, a plastics handle (not shown) , and separate switches (not shown) for controlling, by way of respective flow control valves in the box 8, the delivery of the cold substance to the central pipe 4 and the inducing of suction in the pipe(s) 6.

The device 2 is utilised for the cryogenic removal and vacuum collection of chewing gum 16 from a surface 18, such as a pavement, walkway or road. The control box 8 is actuated to deliver a blast of dry-ice pellets/air mixture from the outer end 20 of the central pipe 4 onto the chewing gum 16. The chewing gum consequently freezes and becomes hard and brittle, breaking up into smaller fragments, the breaking-up being promoted by the impact of the pellets onto the increasingly brittle chewing gum. The control box 8 is also actuated to induce suction at the outer ends 22 of the pipe(s) 6 simultaneously with blasting of the chewing gum. The fragmented chewing gum, which owing to cryogenics has particulated and broken away from the surface 18, is sucked up into the pipe(s) 6 and transported to a waste removal set 36 (see Figure 2) via the suction hose 12. Although the ends 20 and 22 are shown as being perpendicular to the longitudinal axes of the pipes 4 and 6, they may instead be at any oblique angle thereto suited to their pressure-and suction-applying functions. Referring to Figure 2, a 35-tonne commercial motor vehicle 24 comprises an outer shell 26, slidable side doors 28, rear doors indicated partially open at 30, and an engineered skid package 32 mounted inside the vehicle 24. The skid package 32 comprises a base 34, a waste removal set 36, a device 38 for mixing the dry ice into the compressed air, and a dry-ice pellet store 40. At its rear, the base 34 contains sockets for receiving the fork prongs of a fork-lift truck. The device 38 includes a pot from which the dry-ice pellets are fed via a filter to a blast unit of the device 38. The store 40 is in the form of a cooler chest for the dry-ice pellets to be loaded into the pot of the mixing device 38. The skid package 32 is introduced into the vehicle 24 through the opened rear doors 30 and mounted onto the floor 46 of the vehicle. The power required to energise the skid package is provided by the vehicle 24. The vehicle is fitted with a mechanical power take-off 41 from a splitter box from the vehicle gearbox. The take-off 41 drives a 40hp (maximum output) oil-injected rotary screw air compressor 42 and a lOkva electrical generator 44. Both the compressor 42 and the generator 44 are attached to the chassis of the vehicle 24 and located under the floor 46 of the vehicle and respectively pneumatically and electrically connected to quick-release couplings 48, which allows the skid package 32 to be readily removed from the van 24 for ease of service. The generator 44 is connected to a vacuum pump (not shown) in the waste removal set 36 via the appropriate one of the quick-release couplings 48 and via an electrical power supply line 50 in order, via the hose 12 and the pipe(s) 6, to induce suction at the nozzle 22 under the control of the box 8. The waste removal set 36 also includes a receptacle for containing a disposable bag. The compressor 42 is connected to the device 38 via the other quick-release coupling 48 and via a compressed air supply line 52. The van 24 is fitted with fire extinguishers, work lights, beacons, and emergency stop buttons, as required. The hand-held device 2 with the hoses 10 and 12 are releasably mounted on the inside of the nearside wall of the van 24 for ease of handling.

Prior to operation, dry-ice pellets are transferred from the dry-ice store 40 to the device 38. The dry-ice pellets are filter fed from the pot of the device 38 into the blast unit thereof where they enter a compressed air stream delivered by the supply line 52. By actuation of the control box 8 the dry-ice pellets are conveyed by the compressed air from the hose 10 into the pipe 4 of the device 2 in Figure 1 to produce a jet or blast of dry-ice pellets/air mixture from the nozzle 20 onto the chewing gum 16. The chewing gum 16 particularizes owing to the blast and the cryogenic action and is then sucked up into the pipe(s) 6 and conveyed along the hose 12 into a disposable bag in the receptacle of the waste removal set 36. The use of frozen carbon dioxide in pellet form is particularly advantageous in the removal of undesirably present material in comparison with previous methods in that there is virtually no risk of damage to the surface on which the material is located, irrespective of the type of surface or age of the material. Other benefits of using carbon dioxide for the purpose of material removal are that it is a natural substance, environmentally safe, non-explosive, non- toxic, non-corrosive, non-conductive, non-polluting, a dry gas media, and inexpensive. Frozen carbon dioxide also converts into an invisible gas at the normal range of atmospheric temperatures, produces no waste stream (as is the case with water jets) and avoids the use of large amounts of valuable water. In addition, the apparatus can easily be handled and operated by one person without the need for special equipment and training.

The apparatus and method described with reference to the drawings provide for the complete removal and collection of undesirably present waste, such as chewing gum, in a safe, environmentally friendly and cost-effective manner.

Claims

1. A cleaning method comprising blasting with a cold substance a material undesirably present at a fixed surface and thereby rendering brittle and fragmenting said material so as to render said material easier to remove, said substance comprising solid pellets of a coolant.

2. A method according to claim 1, wherein said surface is a traffic-carrying surface.

3. A method according to claim 1 or 2, wherein said material is chewing gum, paint or chalk.

4. A method according to any preceding claim, wherein said substance includes a gaseous medium as a carrier for said pellets .

5. A method according to claim 4, wherein said pellets comprise frozen atmospheric gas.

6. A method according to claim 5, wherein said pellets comprise frozen carbon dioxide gas.

7. A method according to any preceding claim and further comprising employing suction to carry away fragmented said material.

8. A method according to claim 7, wherein said suction is applied to said material simultaneously with said blasting.

9. A method according to claim 7 or 8, wherein said blasting is preceded by mounting on a motor vehicle a unit comprising a supporting base and power-driven equipment supported by said base, connecting said equipment to power supplying means of said vehicle, and energising said equipment to cause said equipment to induce said suction.

10. Apparatus comprising duct means for applying to a material undesirably present at a surface a blasting jet of cold substance comprised of solid pellets of coolant to render brittle and fragment said material, and pellets- supplying means arranged to supply said pellets to said duct means .

11. Apparatus according to claim 10 and further comprising second duct means arranged to apply suction to a region at which said jet is intended to be applied, and inducing means arranged to induce suction in said second duct means.

12. Apparatus according to claim 10 or 11, wherein said supplying means comprises mixing means arranged to mix a gaseous medium with said pellets to provide a mixture which constitutes said substance.

13. Apparatus according to claim 12, wherein said supplying means further comprises storing means for storing said pellets prior to mixing thereof with said medium.

14. Apparatus according to any one of claims 10 to 13 and further comprising a motor vehicle, power-supplying means of said vehicle, and a unit comprised of a supporting base and said pellets-supplying means supported by said base, said pellets-supplying means being connectible to said power- supplying means, and said unit being mounted on and demountable from said vehicle.

15. Apparatus according to claim 14 as appended to claim 11, wherein said inducing means is supported by said base and is connectible to said power-supplying means.

16. Apparatus according to claim 15, wherein said power- supplying means comprises a mechanical drive device, an electrical generator driven by said device and connectible to said inducing means for energising said inducing means.

17. Apparatus according to claim 11 as appended to claim 12, wherein said power-supplying means further comprises a compressor for said gaseous medium and driven by said device and connectible to said mixing means for delivering compressed said gaseous medium to said mixing means.

18. Apparatus according to claim 11 or 15, or claim 12, 13, 14, 16 or 17 as appended to claim 11, wherein said second duct means extends at respective opposite sides of the first- mentioned duct means.

19. Apparatus according to any one of claims 10 to 18, and further comprising a handle from which the duct means extends .

20. Apparatus according to claim 19 and further comprising, in the region of said handle, control means for controlling flow of said substance (and inducing of said suction) .

21. In combination, a motor vehicle, power-supplying means of said vehicle, and a unit mounted on said vehicle and comprising a supporting base and power-driven equipment supported by said base, said equipment being connectible to said power-supplying means, and said unit being demountable from said vehicle.

22. A combination according to claim 21, wherein said power- driven equipment comprises suction-inducing means and mixing means .

23. A combination according to claim 21 or 22, wherein said power-supplying means comprises a mechanical drive device, an electrical generator driven by said device, and a compressor for a gaseous medium and driven by said device.

24. A method comprising mounting on a motor vehicle a unit comprising a supporting base and power-driven equipment supported by said base, and connecting said equipment to power-supplying means of said vehicle.

25. A cleaning method, substantially as hereinbefore described with reference to the accompanying drawings.

26. Cleaning apparatus, substantially as hereinbefore described with reference to the accompanying drawings.