GB2168266A

GB2168266A - Dust suppression method & apparatus

Info

Publication number: GB2168266A
Application number: GB08529773A
Authority: GB
Inventors: Keith Maddison; Eric Arthur Jackson
Original assignee: PERARD TORQUE TENSION Ltd
Current assignee: PERARD TORQUE TENSION Ltd
Priority date: 1984-12-04
Filing date: 1985-12-03
Publication date: 1986-06-18
Also published as: GB8529773D0; GB8430609D0; GB2168266B

Abstract

The apparatus produces a mist under pressure which can be used for cleaning out drill holes whilst suppressing dust usually formed by such an operation. Liquid under pressure is fed along an inner conduit (11) into a mixing chamber (23). Gas under pressure is fed along an annular passage (15) around the inner conduit to the mixing chamber. A turbulence creating member (24) creates turbulence in the gas just prior to the gas entering the mixing chamber, so that a fine mist is emitted from a nozzle (25) communicating with the chamber. The turbulence creating member is a cylindrical member having angularly spaced axial grooves (31) through which the gas is directed to create the turbulence. <IMAGE>

Description

SPECIFICATION Dust suppression method and apparatus This invention relates to dust suppression apparatus and to a method of suppressing dust.

Creation of dust is a common industrial problem and it is well known to use suction devices for drawing air, near the source of dust, through a filtering device. It is also well known to spray water in the region where dust is created, e.g. in cutting and drilling operations and the water may also serve as a lubricating agent and assist in clearing away debris from a drill hole.

In many circumstances, it is not possible to use water in this fashion, e.g. when drilling into gypsum, and substantially dry drilling is necessary. Air under pressure is used to remove the debris, but this increases the dust problem. It has been proposed to use an air/water mixture for removing the debris to reduce the problem, but apparatus for this purpose has not generally operated satisfactorily.

The present invention provides dust suppression apparatus comprising a mist producing head having an inlet for liquid under pressure surrounded by an inlet for gas under pressure, an outlet for liquid opening into a mixing chamber and surrounded by an outlet for gas also opening into the mixing chamber, and turbulence creating means in the outlet for gas, and a nozzle in communication with the chamber for producing a gas/liquid mist.

The mixing chamber preferably comprises a portion axially aligned with the outlet nozzles and reducing in cross-sectional area from a position adjacent the nozzles, to an outlet portion provided with said outlet. It is also preferred that the inlets are axially aligned with the outlet nozzles.

The invention also resides in a method of suppressing dust whilst removing debris from a drill hole, comprising using apparatus as defined above, locating the outlet adjacent a hole being drilled, feeding liquid and gas under pressure to the respective inlets and directing the mist produced from the outlet into the hole during the drilling operation.

Preferably, conduits connected to the head are electrically conducting and are earthed, so as to remove any static charge built-up or during build-up in the drill hole.

Control of the gas/liquid mixture is, preferably, by means of a valve in the gas or liquid flow to said inlets and, advantageously, by valves in both the gas and liquid flows. The valves may be remotely controlled, so as to be controllable from adjacent the drill hole.

Reference is now made to the accompanying drawings, wherein: Figure 1 shows in perspective, dust suppression apparatus according to the invention; Figure 2 shows an enlarged sectional view of a mist producing head of the apparatus; Figure 3 shows in perspective, a turbulence creating member, of the mist producing head; and Figure 4 shows a sectional view similar to Figure 2 which represents an alternative embodiment of the invention.

Referring to Figures 1 to 3 the dust suppression apparatus shown comprises an inner conduit 11 coaxially secured within an outer conduit 14, so to form an annular passage 15 therebetween. The annular passage 15 is closed at one end 17, and the inner conduit 11 defines a first inlet 13 at this end. A Junction 18 between the ends of the outer conduit 14 defines a second inlet 16 for delivering gas to the annular passage 15. A mist producing head 12 is mounted at the opposite end of the apparatus to the closed end 17. The head includes a turbulence creating member 24 which defines a first outlet 21 for liquid fed from the inner conduit 11 and a second outlet 22 for gas, the second outlet surrounding the first outlet 21. These outlets open into a mixing chamber 23 having an outlet nozzle 25 for gas/liquid mixture.

The mist producing head 12 includes a sleeve 27 fixed to a hollow spigot 33 formed with a ridged outer surface. A peripheral flange 52 and an adjacent peripheral groove 35 separate the sleeve from the spigot. The end section 50 of the outer conduit 14, opposite to the closed end 17, has a rebate 40 forming a radially enlarged end to the annular passage 15. An inner recessed portion 53 of the outer conduit 14 is formed adjacent the rebate and the spigot 33 is push-fitted in the annular passage 15 so as to engage in the recess with the flange 52 engaged in the rebate 40. The bore of the spigot 33 forms a continuation of the bore of the outer conduit 14 so that a constant section annular passage is formed from the inlet 18 to the sleeve 27.

A sealing ring 28 is housed in the groove 35 and within the rebate and the groove is enclosed by a radial flange 51 of a cylindrical retaining member 29 secured around the outer periphery of the outer conduit 14.

The sleeve 27 has a tapered bore portion 41 leading from the bóre of the spigot 33 to a main bore portion 42 of greater diameter than the bore of the spigot. The sleeve surrounds an end portion 46 of the inner conduit 11 so as to define an annular chamber 44. The outer periphery of the sleeve carries screw th reads 54.

The turbulence creating member 24 has a cylindrical body 55 and a radially enlarged end portion 31. The member 24 has angularly spaced axial grooves 32 in its outer peripheral surface running the full length of the member. The cylindrical body 55 has an axial bore leading through a tapered bore portion 57 to a constricted portion in the enlarged end portion 31 and defining the first outlet 21. The cylindrical body 55 is slidably received in the annular chamber 44, with the axial bore closely receiving the end portion of the inner conduit 11 and the outer peripheral surface being closely received in the bore of the sleeve 27. The enlarged end portion 31 butts against the free end of the inner conduit 11. The peripheral edge at the free end of the enlarged portion 31 has a bevel 30.

A hollow member 26 has internal screw threads by which the member is screw-engaged with the threads 54 of the sleeve. The member has a conical portion 58 defining the nozzle 25 at its apex. A conical inner surface 59 adjacent the nozzle 25 engages the bevel 30 of the sleeve 27 to captivate the turbulence creating member and secure it in position. The conical inner surface 59 defines with the end face of the enlarged portion 31 of the turbulence creating member a mixing chamber 23.

The axial grooves 32 open into the mixing chamber to define the outlet 22.

In use, water under pressure is fed to the first inlet 13 and air under pressure is fed to the second inlet 18. Liquid is fed through the inner conduit 11 and jetted into the mixing chamber 23 through the first outlet 21. The air is fed through the annular passage 15 to be jetted into the mixing chamber from the grooves 32 in the turbulence creating member. The turbulent gas and liquid are mixed in the mixing.

chamber to emerge from the nozzle 25 as a pressurised fine mist. The device can be used in the same way as an air gun to clear debris from a drill hole, but the fine mist substantially reduces the spread of dust.

An alternative embodiment is shown in Figure. 4.

This embodiment has the same construction as the embodiment of Figures 1 to 3, except that the hollow member 126 is constructed differently. The hollow member is screw-engaged with the threads 54 of the sleeve 27 as previously. The member comrpises, however a nozzle 125 of much greater diameter than that of the previous embodiment, the nozzle 125 being defined by a cylindrical outlet port 126. The port 128 has external peripheral screw threads 127.

In use, the outlet port 126 can be screw-engaged with a housing around a drill for feeding mist under pressure along the drill during a drilling operation.

Claims

1. Dust suppression apparatus comprising a mist producing head having an inlet for liquid under pressure surrounded by an inlet for gas under pressure, an outlet for liquid opening into a mixing chamber and surrounded by an outlet for gas also opening into the mixing chamber, and turbulence creating means in the outlet for gas, and a nozzle in communication with the chamber for producing a gas/liquid mist.

2. Dust suppression apparatus according to Claim 1, wherein the mixing chamber comprises a portion axially aligned with the outlet nozzles and reducing in cross-sectional area from a position adjacent the outlets to the nozzle.

3. Dust suppression apparatus according to Claim 2, wherein the gas and liquid inlets are axially aligned with the outlets.

4. Dust suppression apparatus according to Claim 1,2 or 3, wherein the turbulence creating means has a portion defining the outlet for liquid.

5. Dust suppression apparatus according to Claim 4, wherein the turbulence creating means comprises a member having an annular body and a relatively radially enlarged end portion, the annular body being slidably received in the outlet for gas on a conduit defining a passage between the inlet and outlet for liquid, axial slots being provided in the member to provide communication between the outlet for gas and the mixing chamber, said end portion being provided with the outlet for liquid;

6. Dust suppression apparatus according to any preceding claim, wherein the mixing chamber and the nozzle are defined by a hollow member releasably secured to a body of the mist producing head and serving to retain the turbulence creating means in position.

7. Dust suppression apparatus substantially as herein described with reference to Figures 1 to 3, or Figures 3 and 4 of the accompanying drawings.

8. A method of suppressing dust whilst removing debris from a drill hole, the method comprising using apparatus according to any preceding claim, by inserting the mist producing head in a drill hole and feeding liquid and gas under pressure to the respective inlets.

9. A method of suppressing dust whilst removing debris from a drill hole, the method comprising using apparatus according to any preceding claim, by locating the outlet adjacent a hole being drilled, feeding liquid and gas under pressure to the respective inlets and directing the mist produced from the outlet into the hole during the drilling operation.

10. A method according to Claim 8 or 9, comprising remotely controlling valves in the liquid and gas flow lines to the respective inlets so as to control the proportions of the gas/liquid mixture.