Dust control system

Abstract

A method and an apparatus for reducing dust is disclosed for use with a working machine which is adapted to fragment material from a working surface and includes at least one partially confined space in which dust occurs. A liquid capable of binding dust is provided and the liquid is sprayed into the partially confined space to trap dust particles generated during fragmentation of the material form the working surface.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to the field of dust control, and more particularly to a method and apparatus for controlling dust generated by a working machine such as a cold planer.

BACKGROUND

[0002] Industrial working machines often produce finely fragmented material or dust as an unwanted byproduct of the working process. For example, road working machines commonly known as cold planers or road scarifiers comprise a working device, e.g. a milling drum to remove, for example, a surface layer from a road to be repaired. The material to be removed is fragmented or broken up into small pieces by the working device and then transported to another location for collection and/or for reuse. During this fragmentation and transport process the broken up material generates large amounts of dust particles. This dust is an undesirable byproduct of the road working process.

[0003] EP 0 971 075 A1 discloses one attempt to handle dust developed during grinding of road surfaces, by providing, on a scarifier, a dust handling device. The dust handling device comprises a housing at least partially enclosing the milling drum and defining a suction area, a suction fan and a suction duct connecting said suction area and said suction fan. The suction fan discharges the dust containing air sucked away from the working space above the milling drum through a filter. The filtered air is then discharged and the collected dust powder is discharged to a different location. This system has the disadvantage of being complex, large in size, and expensive to implement. It also generates additional noise, reduces available machine working horsepower because of power consumed by the fan, and requires frequent maintenance of the air filter.

[0004] U.S. Pat. No. 4,325,580 is generally directed to a roadway planning apparatus, and discloses a water spray system used for cleaning a road mill and also for controlling dust. Water is alternatively directed either to cleanup hoses or to spray bars disposed within planing and reclaiming assemblies. Specifically, water is sprayed downward on a cutter drum to cause dirt and dust generated by the cutting process to coalesce. Water is also sprayed on the inner or non-transport surface of transport conveyor belts to wash dirt and dust from the belts that might otherwise accumulate around the belt rollers. This system uses only water as a sprayed agent which is not particularly effective at binding dust particles, and this system fails to address areas of a road mill where a large amount of dust is generated, in particular, the transport surfaces of the conveyor belts.

[0005] In the mining industry, it is known to spray the mined material with water to avoid the generation of dust while processing and transporting the mined material, e.g. coal. There are also suggestions to add an agent to the sprayed water to reduce the surface tension of the water so it may form smaller droplets during spraying, thus increasing the sprayed surface area. As disclosed in U.S. Pat. No. 6,124,366, examples for such agents available on the market are Dustcon™ and Dustclean™ produced by NALCO Chemical Company, Naperville, Ill., USA. Dustcon™ and Dustclean™ are so called dust binding agents having an organic lemon or citrus fruit basis and are both biodegradable and not harmful to the environment. In application in coal mines, the dust binding agent is mixed with the water being sprayed on the mined coal to reduce the generation of dust. The amount of required spray water may be remarkably reduced upon addition of the dust binding agent.

[0006] The instant invention is directed toward providing an improved dust control system and overcoming one or more of the problems set forth above.

SUMMARY OF THE INVENTION

[0007] The present invention provides a method and an apparatus for reducing dust during operation of a road working machine like a cold planer. In accordance with the method and the apparatus of the invention, the dust produced by the generation and transport of fragmented material in the road working machine is effectively trapped and removed from the air.

[0008] In one aspect of the invention, a method of reducing dust produced by a work machine which is adapted to fragment material from a working surface and includes at least one partially confined space in which said dust occurs, includes the steps of providing a liquid including a dust binding agent and spraying the liquid into the partially confined space.

[0009] The invention also provides a road working machine having a working device adapted to fragment a working surface. The road working machine includes a water source connected to a pump which in turn is connected to at least one outlet. The water source includes a dust binding agent, and the outlet is directed at the fragmented material from the working device.

[0010] According to another aspect of the invention, an apparatus for reducing dust is provided. The apparatus is adapted to be mounted on a road working machine having a working device adapted to fragment a working surface. The apparatus includes a water source connected to a pump which in turn is connected to at least one outlet. The water source includes a dust binding agent and the outlet is adapted to be mounted to a portion of the working machine so as to be directed at the fragmented material from the working device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 shows a schematic side view of a road working machine;

[0012] FIG. 2a shows a schematic arrangement of parts of an embodiment of an apparatus for reducing dust in a road working machine in accordance with the invention;

[0013] FIG. 2b shows a detail of a part of the apparatus of FIG. 2a in a different view.

[0014] FIG. 3 shows another part of an apparatus for reducing dust in a road working machine.

DETAILED DESCRIPTION

[0015] FIG. 1 shows schematically a road working machine 1 in a side view. The road working machine 1 includes a machine frame 2 and traction supports 3 for supporting the machine frame 2 and moving it along the driving direction. A driver's seat 4 or operator's station is located generally above a working device 5 supported at a central position on the machine frame 2 and schematically indicated by dashed lines.

[0016] The working device 5 is adapted to remove material from a working surface 6 and may be a milling drum equipped with grinding tools (not shown) which fragment the surface layer of the working surface 6 when they come in contact therewith. Around the working device 5, there is provided a housing 7 defining a working space 8 of the working device 5. Dust and other debris material generated during the removal of the surface material, i.e. the fragmentation of the working surface, are generally confined in the working space 8 by the housing 7.

[0017] During operation, the working device 5 gets hot and needs to be cooled. Cooling is typically achieved by spraying cooling water supplied from a water tank 9 carried by the working machine 1 onto the working device 5, e.g. the milling drum. To this end, a spraying means (not shown) is provided inside the housing 7 of the working device. Generally, this spraying means comprises nozzles which are adapted to generate a fan shaped cooling water jet which is directed onto the working device 5.

[0018] In a typical embodiment, conveyor means 10 in front of the working device 5 are provided to transport the fragmented material produced during operation of the working device 5 away from the working space 8 and to a collecting location, e.g. to a loading platform of a truck (not shown) driving in front of the working machine 1. The conveyor means 10 may consist of a lower conveyor belt 11 and an upper conveyor belt 12. As indicated in FIG. 1, the upper conveyor belt 12 may be moved or pivoted relative to the lower conveyor belt 11 in a vertical and horizontal direction so as to properly adjust the conveyor means 10 with regard to the collection location (not shown). Preferably, the upper conveyor 12 may also be foldable so as to reduce its total length during transportation of the working machine 1.

[0019] The upper conveyor belt 12 may be also moved towards the lower conveyor belt 11 so as to properly load the transported material from the lower conveyor belt 11 onto the upper conveyor belt 12. Preferably, the conveyor means 10 are covered by a hood structure 13 on the upper conveyor belt 12 and a cover structure (not shown) connected to the machine frame 2 in the area of the lower conveyor belt 11. The hood structure 13 joins to the cover structure of the lower conveyor belt 11 when a lower end 14 of the upper conveyor belt 12 is moved towards an upper end 15 of the lower conveyor belt 11 and positioned above the same.

[0020] FIGS. 2a and 2b show schematically a detail of the conveyor means 10 in the area of the upper end 15 of the lower conveyor belt 11 and the lower end 14 of the upper conveyor belt 12. The hood structure 13, the machine frame 2 and the cover structure of the lower conveyor belt 11 form a space 20 more or less confined to prevent the dust generated by the fragmented material from immediately escaping to the surrounding environment.

[0021] In a preferred embodiment, in the area of the partially confined space 20, a dust handling apparatus 30 is installed on the working machine 1 at the upper end 15 of the lower conveyor belt 11 and at the lower end 14 of the upper conveyor belt 12. The dust handling apparatus 30 includes a liquid supply system 32 and a plurality of outlets 141, 142. The liquid supply system 32 supplies a liquid under pressure to the outlets 141, 142.

[0022] The outlets 141, 142 are realized as nozzles mounted on wall structures around the conveyor belts 11, 12. The wall structures may include side walls extending from the conveyor belts, parts of the cover structure of the lower conveyor belt 11, parts of the hood structure 13 of the upper conveyor belt 12, and/or parts of the machine frame 2. As indicated in FIG. 2a, the outlets 141, 142 direct the liquid onto the fragmented material conveyed on the lower and upper conveyor belts 11 and 12 preferably in the form of a widely dispersed spray, which is, more preferably, conically shaped. The liquid in the preferred TM embodiment includes water mixed with a dust binding agent, e.g. Dustcon, in a predetermined mixture ratio. Appropriate mixture ratios are recommended by the manufacturer of the dust binding agent.

[0023] The liquid supply system 32 comprises a plurality of hoses or tubings 201 to 210, 216, 219 and 220 forming a network including a first and a second distributor means 211 and 221, a plurality of couplings 315 to 318, and a plurality of T-connectors 314. Hoses 203 and 207 are connected to the first distributor means 211 receiving the water mixed with the dust binding agent as indicated by the arrow 212. The hose 203 distributes the liquid via couplings 316, 315 and T-connectors 314 to the hoses 201, 202 and 204 wherein in turn the hose 201 is connected to an upper one of the outlets 141, the hose 202 is connected to a middle one of the outlets 141 and the hose 204 is connected to a lower one of the outlets 141 in FIG. 2a. The outlets 141 direct the conically shaped spray of the water mixed with the dust binding agent onto the fragmented material transported on the lower conveyor belt 11.

[0024] The hoses 207 connect the first distributor 211 with the second distributor 221 to which they are coupled on a side surface of the second distributor 221 by couplings 318. On an opposite side surface of the second distributor 221 hoses 205, 216, 219, and 220 are coupled to the second distributor 221 via couplings 317 and T-connectors 314. The hoses 206 and 208 are coupled to the remaining side surfaces of the second distributor 221, and, as shown in FIG. 2b, the hoses 209 and 210 are coupled to a bottom surface of the second distributor 221 by respective couplings 317. The upper surface of the second distributor 221 is mounted to a part of the machine frame 2.

[0025] The hoses 205, 216 and the hoses 206, 209 direct the liquid to respective outlets 142 in the form of nozzles mounted on opposite sides of the lower conveyor belt 11. The hoses 208, 210 provide respective outlets 142 at the upper end 15 of the lower conveyor belt 11 with the liquid consisting of water mixed with the dust binding agent, and the hoses 219, 220 supply this mixture to respective outlets 142 mounted in the area of the lower end 14 of the upper conveyor belt 12. Thus, the water mixed with the dust binding agent is sprayed onto the fragmented material in the area where it is discharged from the lower conveyor belt 11 onto the upper conveyor belt 12, whereby the outlets or nozzles 142 form a conically shaped sprayed mist of fine water droplets which act to trap the dust particles generated by the fragmented material.

[0026] FIG. 3 shows an embodiment of a part of the supply system 32 (also called water source) which provides the water mixed with the dust binding agent pressurized to the first distributor 211 in FIG. 2a. In this embodiment, the water is directly mixed with the dust binding agent, and this mixture is stored in the water tank 9 of FIG. 1.

[0027] The water tank 9 is provided with an outlet port (not shown) which is connected via a shut off tap or valve 426 and a supply line 423 to a filter 422. The filter 423 in turn is connected via another line 428 to a pump 438. The pump 438 pressurizes the liquid received on the line 428. An outlet (not shown) of the pump 438 is connected via line 437 with the first distributor 211, as indicated by the arrow 212.

[0028] The pump 438 is hydraulically driven and to this end the pump 438 is supplied with hydraulic fluid via hydraulic lines 439. The pump 438 is cooled by the liquid being passed therethrough and a bypass line 440 directs the liquid back to the tank 9 in case it is disconnected or shut off from the first distributor 211.

[0029] As mentioned above, the spraying system provided in the housing 7 around the working device 5 (see FIG. 1) for cooling the working device 5 is connected to the water tank 9 containing the mixture of water and dust binding agent. Thus, in this embodiment, the cooling water sprayed onto the working device 5 has also an improved dust capture capability and helps to reduce the amount of dust generated in the working space 8.

[0030] In a different embodiment, the water and the liquid dust binding agent are stored at separated storing locations, i.e. the water is stored in the tank 9 and the dust binding agent is stored in a dust agent container (not shown). The dust binding agent container is provided with an outlet which is connected to a liquid supply line coming from the water tank 9. This connection can be made wherever convenient, for example just after the filter, or just before the pump 438 or even after the pump 438. Preferably, the dust binding agent is fed into the liquid supply line by a metering device (not shown) to control the amount of dust binding agent mixed in the water supplied on the supply line. This arrangement helps to better control the consumption of the dust binding agent and to apply it only to selected locations, e.g., the area where the outlets 141 and 142 of the dust handling apparatus 30 are mounted on the working machine 1.

[0031] It is to be understood that the housing 7 of the working device 5 may be equipped with nozzles connected to the supply system for the water and dust binding agent mixture and capable of generating a widely dispersed spray of the liquid to more effectively trap the dust generated by the fragmentation of material by the working device 5 directly in the working space 8.

INDUSTRIAL APPLICABILITY

[0032] In operation of the working machine 1, the material of the working surface 6 is fragmented by the working device 5 and is accompanied by the generation of a high amount of dust particles and smoke. This dust and smoke which is more or less contained in the housing 7 around the working device 5 moves up the lower conveyor belt 11. In case no preventive measure is taken, the dust may just escape to the environment surrounding the working machine 1.

[0033] The liquid mixture of water and dust binding agent sprayed onto the fragmented material has a high capability of entrapping dust particles generated by the fragmented material produced by the milling operation of the working device 5 on the working surface 6. In the preferred embodiments described above, the occurrence of dust is significantly reduced either in the working space 8, or in the area of the lower conveyor belt 11 where the fragmented material is loaded on the upper conveyor belt 12, or at both locations.

[0034] The widely dispersed spray pattern, which is in the preferred embodiment a conically shaped spray, helps to increase the sprayed area and to generate a fine mist of droplets of the dust binding agent mixture.

[0035] Thus, eventually the dust emerging from the working machine 1, especially at the discharge end of the conveyor means 10, is remarkably reduced and is less of a problem for the operators working on and around the machine 1. The dust binding agent used is preferably biodegradable and environmentally not harmful.

[0036] In accordance with the invention an improvement of the dust handling is achieved by, generally speaking, spraying generated dust as possible or practical. This is best realized by spraying the mixture onto the fragmented material at a location where the dust can not easily escape to the surrounding environment. In this respect, the meaning of confined space is to be understood as an at least partially confined space or a space in which the dust is channeled. Also, the exact choice of where the outlets or spray heads are located and how many are utilized depends on the particular configuration of the working machine which might vary from case to case and is not necessarily limited to the configuration of the working machine 1 of FIG. 1.

[0037] Further, the existing spray system for cooling the working device 5 may be also used to spray the water and dust binding agent mixture into the working space 8. In this case, and for an improved dust handling, it is sufficient to simply add the dust binding agent to the water tank 9 of the working machine 1.

[0038] It is clear, that upon reading the foregoing specification, many alternatives, modifications and changes may be realized by the man skilled in the art. Therefore, the scope of the present invention is not intended to be limited by the embodiments described above in somewhat detail, but it is to be defined by the appended claims and the equivalents thereof.

Claims

1. A method of reducing dust produced by a working machine adapted to fragment material from a working surface, said working machine including a tank for holding a liquid, an associated liquid supply system, and at least one partially confined space in which said dust occurs, comprising the steps of:

providing a liquid including a dust binding agent, and

spraying said liquid into said at least one partially confined space.

2. The method of claim 1, including the step of combining said dust binding agent with water.

3. The method of claim 2 wherein said dust binding agent is adapted to lower the surface tension of water.

4. The method of claim 3, wherein said dust binding agent is based on an organic citrus ingredient and is biodegradable.

5. The method of claim 2, wherein said water is supplied from said tank via said liquid supply system, and said combining step includes the step of controllably adding said dust binding agent to said water at a selected location along said liquid supply system.

6. The method of claim 2, wherein said combining step includes the step of mixing said water and said dust binding agent in said tank.

7. The method of claim 1, wherein said liquid is sprayed in a widely dispersed spray pattern into said partially confined space.

8. The method of claim 1, wherein said partially confined space includes a space above a conveyor adapted to convey the removed material to a collection location.

9. The method of claim 1, wherein said working machine includes a working device adapted to fragment said working surface, and wherein said partially confined space includes a working space around said working device.

10. A road working machine having a working device adapted to fragment a working surface, comprising:

a source of water connected to a pump connected to at least one outlet, said water including a dust binding agent, and said at least one outlet being directed at working surface material fragmented by said working device.

11. A road working machine, as set forth in claim 10, wherein said source of water includes a tank and a liquid supply system adapted to connect said tank and said at least one outlet; and

wherein said source of water further includes a dust binding agent supply means connected to said supply system and adapted to add a dust binding agent to the water supplied by said liquid supply system from said tank.

12. A road working machine, as set forth in claim 11, wherein said dust binding agent supply means includes a metering device adapted to control the amount of said dust binding agent being added to the water.

13. A road working machine, as set forth in claim 10, wherein said source of water includes a tank and a liquid supply system adapted to connect said tank and said at least one outlet, said tank containing water mixed with said dust binding agent.

14. A road working machine, as set forth in claim 10, wherein said dust binding agent lowers the surface tension of water.

15. A road working machine, as set forth in claim 14, wherein said dust binding agent is based on an organic citrus ingredient and is biodegradable.

16. A road working machine, as set forth in claim 10, wherein said at least one outlet is directed into a partially confined space of said working machine containing said fragmented material, said partially confined space including a space above a conveyor adapted to convey the fragmented material to a collection location.

17. A road working machine, as set forth in claim 10, wherein said partially confined space includes a working space around said working device.

18. A road working machine, as set forth in claim 10, wherein said at least one outlet includes at least one nozzle adapted to generate a widely dispersed spray of said water mixed with said dust binding agent and directed onto said fragmented material.

19. An apparatus for reducing dust, said apparatus being adapted to be mounted on a road working machine having a working device adapted to fragment a working surface, comprising:

a water source connected to a pump connected to at least one outlet, said water source including a dust binding agent and said at least one outlet being adapted to be mounted to a portion of said working machine so as to be directed at said fragmented material from said working device.

20. An apparatus, as set forth in claim 19, wherein said water source includes a tank and a supply system adapted to connect said tank and said at least one outlet; and

wherein said water source further includes a dust binding agent supply means connected to said supply system and adapted to add said dust binding agent to the water supplied by said supply system from said tank.

21. An apparatus, as set forth in claim 20, wherein said dust binding agent supply means includes a metering device adapted to control the amount of said dust binding agent being added to the water.

22. An apparatus, as set forth in claim 19, wherein said water source includes a supply system adapted to connect a tank provided on said road working machine and said at least one outlet; said tank containing water mixed with said dust binding agent.

23. An apparatus for reducing dust, said apparatus being adapted to be mounted on a machine having at least one partially confined work space, comprising:

a source of water containing a dust binding agent; and

at least one liquid spray outlet connected to said source and disposed in said work space.

24. An apparatus, as set forth in claim 23, including a tank containing water mixed with said dust binding agent.

25. An apparatus, as set forth in claim 23, including a dust binding agent supply means adapted to combine said dust binding agent with said water, said dust binding agent supply means having a metering device adapted to control the ratio of said dust binding agent to said water.

26. An apparatus, as set forth in claim 23, wherein said machine includes at least one conveyor having a transport surface and said at least one partially confined work space includes a space above said at least one conveyor transport surface; and

wherein said at least one liquid spray outlet is located at a position sufficient to direct said water and dust binding agent onto said at least one conveyor transport surface.