| JP10025707 | SINGLE TIP RIPPER |
| JP2002188910 | TRAVELING TYPE ROAD SURFACE SHAPE MEASURING DEVICE |
| JP2002081016 | DUST RESTRAINING TYPE CUTTER |
HOGENES, Martinus (Van Brakelstraat 11, AS Alphen aan den Rijn, NL-2404, NL)
CLAIMS
1. A method for preventing dust formation and the release of polyaromatic hydrocarbons, quartz particles and asbestos particles, among other substances, during demolition work, wherein at least part of an object, such as the upper layer of a road surface is fragmented into small pieces by means of a working device and discharged, characterised in that a mist is created by means of a liquid at least around and above the point of contact between the working device and the object, with the mist droplets having a diameter of less than 30 μm.
2. A method according to claim 1, wherein said mist is at least partially created in a dome that is disposed above the working device.
3. A method according to claim 1 or 2, wherein the working device is mounted in a mobile device.
4. A method according to claim 1, 2 or 3, wherein said working device is a cutter drum.
5. A method according to any one of the preceding claims 1 - 4, wherein the fragmented pieces of the object are discharged by conveying means, such as a conveyor belt.
6. A method according to claims 2 and 5, wherein the dome in which the mist is created extends to above the conveying means.
7. A method according to any one of the preceding claims 1 - 6, wherein said liquid comprises water and an additive.
8. A method according to claim 7, wherein said additive comprises a binding agent.
9. A method according to claim 8, wherein said liquid contains at least 0.2 ml of binding agent per litre of water .
10. A method according to any one of the preceding claims 1 - 9, wherein said dome encloses a space having a volume of 4 - 10 m 3 .
11. A method according to any one of the preceding claims 1 - 10, wherein said liquid is atomised by means of atomising nozzles.
12. A method according to claim 11, wherein said liquid is atomised by means of at least 6 atomising nozzles.
13. A method according to claim 11 or 12, wherein said atomising nozzles are hydraulic atomising nozzles having a nominal capacity of 2 - 6 I/hour at a pressure of 2 bar.
14. A method according to claim 11, 12 or 13, wherein said liquid is pumped through the atomising nozzles under a pressure of 50 - 200 bar.
15. A method according to any one of the preceding claims 1 - 14 and claim 2, wherein at least 0.3 1, preferably at least 0.7 1 of liquid per cubic metre of dome volume is atomised per minute.
16. A method according to any one of the preceding claims 1 - 15, wherein liquid may be additionally sprayed near the point of contact to form droplets having a size of more than 30 μm.
17. A device for carrying out demolition work, comprising a working device for fragmenting at least part of an object, such as the upper layer of a road surface, into small pieces, characterised in that the device comprises means for creating a mist by means of a liquid at least around and above the point of contact between the working device and the object, with the mist droplets having a diameter of less than 30 μm.
18. A device according to claim 17, wherein the device comprises a dome disposed above the working device, in which a mist can be created.
19. A device according to claim 17 or 18, wherein said device is a mobile device.
20. A device according to claim 17, 18 or 19, wherein said working device is a cutter drum.
21. A device according to any one of the preceding claims 17 - 20, wherein the device comprises conveying means, such as a conveyor belt, for discharging the fragmented pieces of the object.
22. A device according to claims 18 and 21, wherein the dome in which the mist is created extends to above the conveying means .
23. A device according to any one of the preceding claims 17 - 20 and claim 18, wherein said dome encloses a space having a volume of 4 - 10 m 3 .
24. A device according to any one of the preceding claims 17 - 23, wherein the means for creating said mist comprise atomising nozzles.
25. A device according to claim 24, wherein said device comprises at least 6 atomising nozzles.
26. A device according to claim 24 or 25, wherein said atomising nozzles comprise hydraulic atomising nozzles having a nominal capacity of 2 - 6 I/hour at a pressure of 2 bar.
27. A device according to any one of the preceding claims 17 - 26, wherein the device comprises additional spray nozzles near the point of contact, by means of which liquid can be sprayed to form droplets having a diameter of more than 30 μm. |
METHOD AND DEVICE FOR PREVENTING DUST FORMATION DURING DEMOLITION WORK
The invention relates to a method for preventing dust formation and the release of polyaromatic hydrocarbons (in particular up to EPA16) , quartz particles and asbestos particles, among other substances, during demolition work, wherein at least part of an object, such as the upper layer of a road surface is fragmented into small pieces by means of a working device and discharged. Such a method and a device for carrying out such a method are described in EP 1 367 176.
In the known method, nozzles spray a liquid comprising water and a binding agent onto the working device and the area surrounding the working device. The liquid droplets bind at least part of the dust that is released during the work and subsequently precipitate.
Quartz particles, polyaromatic hydrocarbons, dust and asbestos particles may be released at the location of scarifiers, demolition cranes and road sweepers, for example, and may be carcinogenic in the case of (prolonged) exposure thereto above a particular concentration. Consequently it is desirable to minimise this exposure during the aforesaid demolition work.
A disadvantage of said known method is the fact that it does not function optimally and that relatively much liquid is needed in order to effect a substantial dust reduction. The object of the invention is to provide a method which is more effective and wherein a greater reduction of dust and/or other harmful substances is achieved and/or wherein said reduction is achieved with less liquid.
According to the invention a mist is to that end created by means of a liquid at least around and above the point of contact between the working device and the object, with the mist droplets having a diameter of less than 30 μm. Since mist droplets of that size remain suspended in the air for some time, the contact time with the dust is significantly longer than is the case with liquid being sprayed, where the liquid droplets precipitate immediately. Furthermore the spacing between the droplets is significantly smaller than in the case of liquid being sprayed, so that a blanket that is impenetrable to dust particles is created.
In a preferred embodiment said mist is at least partially created in a dome that is disposed above the working device, said working device preferably being a cutter drum, which is preferably mounted in a mobile device. The dome encloses a space of 4 - 10 m 3 , for example. The fragmented pieces of the object are preferably discharged by conveying means such as a conveyor belt. The dome in which the mist is created preferably extends to above the conveying means.
The liquid preferably comprises water and an additive, which additive preferably comprises a binding agent. The liquid preferably comprises at least 0.2 ml of binding agent (such as Bitfoam™ from Cleandust BV, or Dustaway™ from BMF BV) per litre of water. Said substances are biodegradable and also act as softeners and surface tension reducers. The dust bound to the binding agent generally remains on the ground in bound condition for 4 - 14 days, by the end of which time it will generally be covered with a new layer already.
The liquid is preferably atomised by means of atomising nozzles. With the aforesaid dome volume, the liquid is
atomised by means of, for example, 6 - 20 atomising nozzles. Another way of creating a mist is, for example, evaporating the liquid into steam. The atomising nozzles are preferably hydraulic atomising nozzles having a nominal capacity of 2 - 6 I/hour at a pressure of 2 bar, for example a BEX™ C-series model CL of 3 I/hour at a pressure of 2 bar, or a similar atomising nozzle. The liquid is preferably pumped through the atomising nozzles under a pressure of 50 - 200 bar, which is very high for this kind of atomising nozzles. Preferably at least 0.3 1, more preferably at least 0.7 1 of liquid per cubic metre of dome volume is atomised per minute in that case .
Near the point of contact, liquid may be additionally sprayed to form droplets having size of more than 30 μm, according to EP-A-I 367 176. Said droplets precipitate and soften the road surface and the fragments, so that less dust is generated already at the source.
The invention also relates to a device for carrying out demolition work as described above.
The invention will now be explained in more detail on the basis of an embodiment illustrated in the. figures, in which:
Figure 1 is a schematic side elevation of an asphalt milling machine; and
Figure 2 is a schematic view of the liquid atomising system that is used in the machine shown in figure 1.
Figure 1 very schematically shows an asphalt milling machine. Such a machine is known and is shown (figure 1) and described in more detail in EP-A-I 367 176.
The asphalt milling machine comprises a frame 1 with a driver's cabin 2 and caterpillar tracks 3, by means of which the machine can be moved. A cutter drum 4 is rotatably mounted to the underside of the machine and can be moved up and down for scrape the top layer from an asphalt road and fragment it into small pieces.
A dome 6, which is open at the bottom side, is arranged round said cutter drum 4, which dome comprises a working space in which dust being released upon scarification of the road surface is captured. The working space under the dome has a volume of about 6 m 3 .
The fragmented pieces of the road surface are discharged from the cutter 4 at the front side of the machine to a collecting container (not shown) moving along the machine by a fixed lower conveyor belt 7 and a pivotable upper conveyor belt 8 connecting thereto. The conveyor belt 7 is enclosed by an extension 9 of the dome 6. The conveyor belt 8 is likewise surrounded by a cover (not shown) .
Eight hydraulic atomiser nozzles 10 (see figure 2), BEXTM C- series model CL of 3 I/hour at a pressure of 2 bar, are provided in the dome 6 and the extension 9.
According to figure 2, the mist atomisers 10 are fed from a water reservoir 11 during scarification of an asphalt road surface. A water pump 13 and a hydraulics pump 15 pump the water to the atomisers 10 under a pressure of about 70 bar
via a water filter 12, atomising in total about 4 litres of liquid per minute in the dome 6 and the extension 9 to form mist droplets having a diameter of less than 30 μm. Arranged between the water pump 13 and the hydraulics pump 15 is an injector 14, where about 0.3 - 0.5 ml of a biodegradable additive, such as Bitfoam™ or Dustaway™ from an additive reservoir 16 is added per litre of water. A return line provided with a non-return valve 17 carries back excess water to the water reservoir 11.
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