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Title:
ABRASIVE BLASTING SYSTEM
Document Type and Number:
WIPO Patent Application WO/2022/117236
Kind Code:
A1
Abstract:
An abrasive blasting system comprising a vessel having an interior for storing particulate abrasive material, the vessel having an inlet opening in an upper end thereof for introducing particulate abrasive material into said interior, a valve 5member adapted to selectively close said inlet opening to permit the interior of the vessel to the pressurised, a gas inlet in a lower end of the vessel for introducing a stream of pressurised gas into the vessel along a path, a gas pipe being located within the vessel and being arranged in alignment with said path such that said stream of pressurised gas passes into said gas pipe, a venturi jet being located 0within said gas inlet, whereby abrasive material within the vessel is entrained into said stream of pressurised gas downstream of the venture jet as it passes into said gas pipe, wherein said gas pipe communicates with an outlet pipe extending out of said vessel, whereby said outlet pipe can supply a mixture of pressurised gas and abrasive material to a discharge hose terminating in a discharge nozzle.5

Inventors:
MCKENNA JASON (GB)
Application Number:
PCT/EP2021/067439
Publication Date:
June 09, 2022
Filing Date:
June 24, 2021
Export Citation:
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Assignee:
FLOWTECH INTERNATIONAL LTD (GB)
International Classes:
B24C7/00; B24C3/06
Foreign References:
CN107116483A2017-09-01
US2261565A1941-11-04
US4487582A1984-12-11
US20080287039A12008-11-20
US10569386B22020-02-25
US20190038380A12019-02-07
Attorney, Agent or Firm:
FRKELLY (IE)
Download PDF:
Claims:
CLAIMS

1 . An abrasive blasting system comprising a vessel having an interior for storing particulate abrasive material, the vessel having an inlet opening in an upper end thereof for introducing particulate abrasive material into said interior, a valve member adapted to selectively close said inlet opening to permit the interior of the vessel to the pressurised, a gas inlet in a lower end of the vessel adapted to communicate with a source of pressurised gas for introducing a stream of said pressurised gas into the vessel along a path, a gas pipe being located within the vessel and being arranged in alignment with said path such that said stream of pressurised gas passes into said gas pipe, a venturi jet being located within said gas inlet, whereby abrasive material within the vessel is entrained into said stream of pressurised gas downstream of the venturi jet as it passes into said gas pipe, wherein said gas pipe communicates with an outlet pipe extending out of said vessel, whereby said outlet pipe can supply a mixture of pressurised gas and abrasive material to a discharge hose terminating in a discharge nozzle.

2. A system as claimed in claim 1 , wherein said outlet pipe extend substantially horizontally out of a side wall of the vessel.

3. A system as claimed in claim 1 or claim 2, wherein the venturi jet is adjustably mounted within said gas inlet to facilitate adjustment of the distance between a downstream end of said venturi jet and an upstream end of said gas pipe to thereby adjust the rate at which abrasive material is entrained into said stream of pressurised gas.

4. A system as claimed in claim 3, wherein said venturi jet is mounted in a holder to be vertically displaceable within the holder to facilitate adjustment of the position of the venturi jet with respect to the upstream end of the gas pipe.

5. A system as claimed in claim 4, wherein said venturi jet is displaceable with respect to the holder between a first position, wherein a downstream end of said venturi jet engages the upstream end of the gas pipe thereby preventing abrasive material from entering the gas pipe, and a second position, wherein said downstream end of said venturi jet is spaced from said upstream end of said gas pipe.

6. A system as claimed in claim 5, wherein the venturi jet is biased towards said first position by biasing means and is urged towards said second position, against said biasing means, under the action said pressurised gas.

7. A system as claimed in claim 5 or claim 6, wherein at least a portion of said holder defines a cylinder, at least a portion of said venturi jet defining a piston slideably mounted in said cylinder, wherein said source of pressurised gas selectively communicates with said cylinder to urge said venturi jet towards said second position.

8. A system as claimed in claim 7 when dependent upon claim 6, wherein said biasing means comprises a compression spring located within said cylinder to act against a first side of said piston to bias the venturi jet towards its first position, said cylinder including an inlet port communicating with said source of pressurised gas such that said pressurised gas acts against a second side of the piston when supplied to said inlet port, opposite said first side, to selectively displace the venturi jet towards its second position, thereby adjusting the ratio of pressurised gas and abrasive material supplied to the discharge hose as a function of the gas pressure of said pressurised gas.

9. A system as claimed in claim 4, wherein said holder incorporates a threaded coupling whereby said adjustment of the venturi jet with respect to the upstream end of the gas pipe is achieved by rotating the holder with respect to the gas inlet of the vessel.

10. A system as claimed in claim 9, wherein said adjustable coupling is provided with locking means.

11. A system as claimed in any of claims 4 to 10, wherein the downstream end of the venturi jet is tapered and is adapted to enter into the upstream end of the gas pipe such that the rate at which abrasive material is entrained into said stream of 14 pressurised gas is a function of the distance by which the tapered downstream end of the venturi enters the upstream end of the gas pipe.

12. A system as claimed in any preceding claim, wherein at least a lower portion of said gas pipe is arranged substantially vertically within the vessel, said venturi jet being arranged coaxially with said gas pipe.

13. A system as claimed in any preceding claim, wherein the vessel comprises a generally cylindrical midsection, a generally hemispherical or inverted dish shaped upper portion and a generally conical lower section, at least a lower portion of said gas pipe being arranged within said conical lower section and coaxially with said cylindrical midsection.

14. A system as claimed in claim 13, wherein said outlet pipe exits said midsection of the vessel.

15. A system as claimed in claim 14, wherein said outlet pipe and said gas pipe are arranged substantially perpendicular to one another and are coupled together by means of a curved link pipe located within said vessel.

16. A system as claimed in claim 15, wherein said curved link pipe is replaceable, an access door being provided in a side wall of the vessel to permit replacement of the link pipe.

17. A system as claimed in any preceding claim, wherein said outlet pipe is associated with a flow control valve for controlling the flow of pressurised air and abrasive material therethrough.

18. A system as claimed in claim 17 wherein said flow control valve comprises a pinch valve.

19. A system as claimed in claim 17 or claim 18, wherein said flow control valve is pneumatically operated. 15

20. A system as claimed in any preceding claim, further comprising a control system adapted to control the supply of said stream of pressurised gas to said gas inlet, to operate the valve member to close said inlet opening and to pressurise the vessel.

21. A system as claimed in claim 20 when dependent upon claim 19, wherein said control system is adapted to control said flow control valve.

22. A system as claimed in any preceding claim, wherein said vessel is mounted on a wheel support frame.

Description:
Abrasive Blasting System

FIELD OF THE INVENTION

This invention relates to an abrasive blasting system for use in surface treatment or preparation.

BACKGROUND OF THE INVENTION

It is known to provide abrasive blasting equipment for blasting operations whereby an operator can direct a particulate abrasive material carried in a flow of pressurised air against a surface to be treated, such that the abrasive material cleans and removes paint, dirt and corrosion from such surface.

A known abrasive blasting equipment comprises a vessel containing a particulate abrasive material, the vessel having an outlet at its base opening into a delivery hose through which pressurised air is passed, whereby abrasive material passing through the outlet of the vessel, typically via a metering valve, is carried into said flow of pressurised air and delivered to an outlet nozzle at a distal end of the delivery hose. Typically, the vessel is pressurised to prevent the back flow of air into the vessel through the outlet. A filling opening is typically provided in an upper end of the vessel to allow the vessel to be filled with abrasive, said filling opening typically being closed by a pneumatically operated closure valve adapted to automatically close the filling opening when the vessel is pressurised.

A problem with such known abrasive blasting equipment is that the outlet in the bottom of the vessel can become clogged, particularly if the abrasive material becomes contaminated with water.

SUMMARY OF THE INVENTION

According to the present invention there is provided an abrasive blasting system comprising a vessel having an interior for storing particulate abrasive material, the vessel having an inlet opening in an upper end thereof for introducing particulate abrasive material into said interior, a valve member adapted to selectively close said inlet opening to permit the interior of the vessel to the pressurised, a gas inlet in a lower end of the vessel for introducing a stream of pressurised gas into the vessel along a path, a gas pipe being located within the vessel and being arranged in alignment with said path such that said stream of pressurised gas passes into said gas pipe, a venturi jet being located within said gas inlet, whereby abrasive material within the vessel is entrained into said stream of pressurised gas downstream of said venturi jet as it passes into said gas pipe, wherein said gas pipe communicates with an outlet pipe extending out of said vessel, whereby said outlet pipe can supply a mixture of pressurised gas and abrasive material to a discharge hose terminating in a discharge nozzle.

Preferably said outlet pipe extend substantially horizontally out of a side wall of the vessel.

The venturi jet may be adjustably mounted within said gas inlet to facilitate adjustment of the distance between a downstream end of said venturi jet and an upstream end of said gas pipe to thereby adjust the rate at which abrasive material is entrained into said stream of pressurised gas. The venturi jet may be mounted in a holder coupled to said gas inlet by an adjustable coupling, said adjustable coupling being adapted to facilitate adjustment of the position of the holder, and thereby the venturi jet, with respect to the gas inlet of the vessel. In one embodiment said adjustable coupling may comprise a threaded coupling whereby said adjustment of the venturi jet within the gas inlet is achieved by rotating the holder with respect to the gas inlet of the vessel. Preferably the adjustable coupling is provided with locking means.

At least a lower portion of said gas pipe may be arranged substantially vertically within the vessel, said venturi jet being arranged coaxially with said gas pipe.

In one embodiment the vessel may comprise a generally cylindrical midsection, a generally hemispherical or inverted dish shaped upper portion and a generally conical lower section, at least a lower portion of said gas pipe being arranged within said conical lower section and coaxially with said cylindrical midsection. The outlet pipe preferably exits said midsection of the vessel, preferably perpendicular to a side wall of said midsection. The outlet pipe and the gas pipe may be arranged substantially perpendicular to one another and may be coupled together by means of a curved link pipe located within said vessel. The curved link pipe may be replaceable, an access door being provided in a side wall of the vessel to permit replacement of the link pipe.

Preferably the outlet pipe is associated with a flow control valve for controlling the flow of pressurised air and abrasive material therethrough. The flow control valve may comprise a pinch valve. Preferably the flow control valve is pneumatically operated.

A control system may be provided, said control system being adapted to control the supply of said stream of pressurised gas to said gas inlet, to operate the valve member to close said inlet opening and to pressurise the vessel. The control system is preferably also adapted to control said flow control valve associated with the outlet pipe.

The system may further comprise a source of pressurised gas, such as a compressor, adapted to supply said stream of pressurised gas to said gas inlet, to operate said valve member to close the inlet opening of the vessel and to pressurise the vessel. The gas may comprise air or, wherein required, any other suitable gas, for example nitrogen where there is a risk of explosion.

The system may further comprise a flexible blast hose adapted to be coupled to said outlet pipe, said blast hose terminating in a blast nozzle.

In one embodiment the vessel may be mounted on a wheel support frame to allow the system to be readily transported to different locations.

BRIEF DESCRIPTION OF THE DRAWINGS An abrasive blasting system in accordance with an embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which

Figure 1 is a perspective view of an abrasive blasting system in accordance with an embodiment of the present invention;

Figure 2 is a front view of the abrasive blasting system of Figure 1 ;

Figure 3 is a side view of the abrasive blasting system of Figure 1 ;

Figure 4 is a further side view of the abrasive blasting system of Figure 1 ;

Figure 5 is a sectional view through the abrasive blasting system of Figure 1 ;

Figure 6 is a detailed side view of eth system of Figure 1 ;

Figure 7 is a sectional view on line B-B of Figure 6;

Figure 8 is a detailed sectional view of a lower section of the system of Figure 1 with the venturi jet in a closed position;

Figure 9 is a detailed sectional view of a lower section of the system of Figure 1 with the venturi jet in an open position;

Figure 10 is a detailed sectional view through the outlet pipe 24 showing the water injection coupling 50; and

Figure 11 is a schematic view of the control system of the abrasive blasting system of Figure 1 .

DETAILED DESCRIPTION OF THE DRAWINGS As illustrated in the drawings, an abrasive blasting system in accordance with an embodiment of the present invention comprises a vessel 2 for containing a particulate abrasive material, the vessel 2 being mounted on a wheeled support frame 3 to allow the system to be readily transported to different locations. Alternatively, it is envisaged that the system may be mounted on a trailer or other vehicle or may be stationary.

A compressor unit (not shown) may be provided to provide a source of compressed gas, more preferably compressed air. The compressor unit may be electrically powered or may be driven by an internal combustion engine and may incorporate a pressurised air storage tank adapted to store compressed air, or other gas, at a high pressure and to maintain a supply of compressed air at said pressure.

In the embodiment shown, the vessel 2 may comprise a generally cylindrical midsection 4, a generally hemispherical or inverted dish shaped upper section 6 and a generally conical lower section 8, to thereby defined a closed tank capable of being pressurised. A filling opening 10 is provided in an upper end of the vessel 2 to permit the vessel to be filled with a particulate abrasive material. As best illustrated in Figure 5, a pneumatically operated closure valve 16 having a vertically displaceable valve member or plug is located within the vessel 2 for selectively closing the filling opening 6 and thereby sealing the vessel 2, as will be described in more detail below. The valve member comprises a pop-up valve adapted to cooperate with an O-ring seal 17 within the filling opening 10.

A dish shaped filling bowl 12 may be mounted on top of the upper section of the vessel 2 to facilitate filling of the vessel 2 with abrasive material. A perforated cover 14 may be located in the base of the filling bowl 12 overlying the filling opening 10 of the vessel 2 to act as a sieve to prevent oversize material and contamination from entering the vessel 2.

An air inlet 18 is provided at a lower end of the vessel adapted to be coupled to said source of compressed air. A venturi jet 20 is located in the air inlet 18, the venturi jet 20 having an axis preferably arranged coaxially with a central axis of the vessel 2. A fixed air pipe 22 is located within a lower region of the vessel 2, arranged coaxially with the venturi jet., In use, a downstream end of the venturi jet is vertically spaced from a lower end of the air pipe 22 whereby abrasive material within a lower region of the vessel 2 is entrained into a flow of pressurised air passing through the venturi jet 20 and into the fixed air pipe 22. The air pipe 22 is mounted within the lower section 8 of the vessel by means of a mounting plate 23, as illustrated in Figure 5. The position of the downstream end of the venturi jet 20 with respect of the upstream end of the air pipe 22 is preferably adjustable to permit adjustment of the ratio of abrasive material and air passing into the air pipe 22. Preferably the position of the venturi jet 20 may be controlled pneumatically, as will be described below in more detail. By entraining the abrasive material into an upwardly flowing stream of pressurised air within the vessel and passing the mixture of pressurised air and abrasive material into said upwardly extending air pipe 22, the blockage problems associated with prior art abrasive blasting systems are avoided.

Pressurised air and entrained abrasive material pass out of the vessel 2 though an outlet pipe 24 extending through a side wall of the midsection 4 of the vessel 2, the outlet pipe 24 communicating with the fixed air pipe 22 via a curved coupling pipe 25 located within the vessel 2. The coupling pipe 25 may be exposed to greater wear from the mixture of abrasive material and pressurised air flowing therethrough due to the change of direction of the flow as it passes through the coupling pipe 25. Therefore, the coupling pipe 25 may be arranged to be periodically replaceable and/or may be made from or lined with a hard wearing material. However, due to the location of the coupling pipe 25 within the vessel 2, unlike prior art systems where the air and abrasive material delivery pipes are all external to the vessel, rupture of the coupling pipe 25 will not lead to a dangerous loss of high pressure abrasive material. The coupling pipe 25 may be coupled to the outlet pipe 24 via a coupling flange 25A, as shown in Figure 5.

An access port having a removable door 32 is provided on a side of the vessel 2 for gaining access to the interior of the vessel 2, and in particular the coupling pipe 25.

A pinch valve 26 is mounted on the outlet pipe 24 on the exterior of the vessel 2 for controlling the flow of pressurised air and abrasive material through the outlet pipe 24. Preferably the pinch valve 26 is pneumatically operated. Alternatively the pinch valve 26 may be hydraulically operated.

A coupling 28 is provided on a distal end of the outlet pipe 24, downstream of the pinch valve 26, for coupling the outlet pipe 24 to a flexible blast pipe leading to an outlet nozzle (not shown) for delivering a flow of compressed air and entrained abrasive material against a surface to be treated.

Control valves (such as pressure regulators) may be provided for controlling the flow of pressurised air to the closure valve 16, venturi jet 20, pinch valve 26 and to the air inlet 18 of the vessel 2. It is envisaged that one or all of the closure valve 16, venturi jet 20, pinch valve 26 and to the air inlet 18 of the vessel 2 may be operated hydraulically, by means of a supply of pressured hydraulic fluid, or may be operated electrically or mechanically by any other operating means.

In a preferred embodiment the pinch valve 26 may be automatically closed via a pneumatically operated piston or valve member acting against a flexible section 24A of the outlet pipe 24 to close the outlet pipe 24 when the system is pressurised (see Figure 5), thereby sealing the vessel abrasive outlet. Air pressure supplied to the piston of the pinch valve 26 may be controlled via a normally open air solenoid valve, controlled via a deadman handle on the outlet nozzle. Alternatively the pinch valve 26 may be operated hydraulically.

The venturi jet 20 is mounted within a holder 30 coupled to the air inlet of the vessel 2, whereby the holder 30 may be adjusted with respect to the vessel 2 to adjust the vertical spacing between the downstream end of the venturi jet 20 and the lower end of the fixed air pipe 22 to thereby adjust the rate at which abrasive material is entrained into the flow of pressurised air from the venturi jet 20. In one embodiment the venturi jet 20 is slideably mounted within the holder 30 to be axially slideable between a closed position, shown in Figure 5, 7 and 8, wherein the downstream end of the venturi jet 20 enters the upstream end of the air pipe 22, thereby preventing abrasive material from entering the air pipe, and an open position, shown in Figure 9, wherein the downstream end of the venturi jet 20 is spaced from the upstream end of the air pipe 22. The venturi jet 20 may be biased towards its closed position by means of a return spring S and may be urged towards its open position by means of air or hydraulic pressure supplied to an upper region of the holder 30, said pressure acting against a peripheral flange F formed around the venturi jet 20 and acting as a piston slideably mounted within a cylinder defined by the holder 21. The flange F divides the interior of the holder 30 into an upper region, which may be pressurised, and a lower region which is open to ambient pressure. A suitable inlet port may be provided for supplying pressurised air to the upper region of the interior of the holder 30. The return spring S is located in the lower region of the interior of the holder 30, acting on a lower side of the flange F. The flange F may be provided with a peripheral seal acting against the inner wall of the holder 30.

As such, the flow rate of abrasive material entrained into the flow of pressurised air passing through the venturi jet 20 and into the air pipe 22 can be adjusted by varying the air pressure supplied to the venturi jet holder 21 by means of a suitable pressure regulator and/or by adjusting a preload applied to the return spring S, for example by means of a threaded coupling on the holder 30. A sleeve or stop 60 (as shown in Figure 8) may be located in the lower region of the interior of the holder 30 to limit the maximum travel of the venturi jet 20 within the holder.

As best shown in Figures 8 and 9, a downstream end of the venturi jet 20 adapted to enter the upstream end of the air pipe 22 may be tapered such that the ratio of air and abrasive material passing into the air pipe 22 can be accurately metered by adjusting the distance to which the downstream end of the venturi jet 20 extends into the upstream end of the air pipe 22.

In an alternative embodiment the holder 30 and/or venturi jet 20 may be threadedly engaged with the air inlet 18 of the vessel 2 so that the holder 30 may be rotated with respect to the air inlet 18 of the vessel to manually adjust the position of the venturi jet 20 with respect the fixed air pipe 22. Alternatively the movement of the venturi jet 20 within the holder 30 may be controller by an electrical actuator or by any other pneumatic, hydraulic, electrical or mechanical operating means. The venturi jet 20 may also be adapted to be replaceable within the holder 30 to permit the venturi jet 20 to be replaced when worn or to enable the size of the venturi jet 20 to be changed to suit different materials or required flow rates. Preferably the tapered downstream end of the venturi jet 20 may be replaceable, being exposed to the greatest wear from abrasive material, said downstream end being threadedly engaged with the remainder of the venturi jet 20.

The holder 30 may be coupled to the air inlet 18 of the vessel 2/holder 30 via a triple seal system comprising an outer dust seal 52 and optionally primary and secondary O-ring seals.

The venturi jet 20 is preferably made from a wear resistant material and may be hard chrome plated for corrosion resistance and further abrasion resistance.

A suitable wiper shaped seal or any suitable abrasive seal made of a composite/rubber like material may be fitted to a top section of the venturi jet, preferably held in place with a seal retainer, to prevent abrasive particles entering the O-ring seals within the venturi jet housing.

An outlet/drain pipe 40 may be provided in a lower end of the vessel 2 having a valve 42 (more preferably a ball valve) to permit the vessel 2 to be emptied of abrasive when required.

An air inlet hose 31 communicates with the holder 30 for introducing pressurised air into the vessel 2 via the venturi jet 20. The air inlet hose 31 may be coupled to the holder 30 via a swivel coupling.

A one way check valve may be provided in the air inlet hose 31 , preferably downstream of a flow control valve/pressure regulator and upstream of the holder 30, to prevent backflow of abrasive when the vessel 2 is pressurised. A pressure regulator 35 may be provided upstream of the air inlet hose 31 for controlling the blasting pressure. A exhaust valve 36 is preferably provided on the vessel 2 for depressurising the vessel 2. The exhaust valve 36 may be provided with a silencer 37 to reduce noise when venting and for added safety. The exhaust valve 36 may be used to depressurise the vessel 2 to permit refilling of the vessel 2. The exhaust valve 36 may incorporate a pressure relief valve for venting excess pressure from the vessel 2. The exhaust valve 36 may be automatically controlled via a deadman switch provided on the outlet nozzle. By providing an automatically operating exhaust valve, controlled also via the deadman handle (operated by the blast operator), pressure within the vessel is automatically dumped and the valve member of the control valve 16 is released each time the deadman or other remote control handle is deactivated, providing auto depressurisation of the vessel. This may allow the vessel to be refilled continuously via an abrasive recovery system from an overhead hopper.

The vessel may also be provided with a pressure relief valve 38 for safety and a pressure gauge 40 for monitoring and setting the pressure within the vessel 2.

Water may be injected into the flow of pressurised air adjacent the coupling 28 at the distal end of the outlet pipe 24 via a water injection coupling 50, as best illustrated in Figure 10. By adding water after abrasive induction water/moisture contamination of the abrasive stored in the vessel 2 is eliminated. An abrasive wear liner 54 may be fitted in the outlet pipe 24 adjacent and downstream of the water injection coupling 50, preferably made of a ceramic or other abrasive resistant material to prevent abrasive wear.

Figure 11 illustrates the pneumatic control circuit of the system of Figure 1

In use, the vessel 2 is filled with a selected abrasive material via the filling opening 10. The respective control valves are operated, preferably under by means of a control unit, such that pressurised air is supplied to the system from said source of compressed air, preferably via the suitable pressure regulator 35, the pressurised air being supplied to the closure valve 16 such that the valve member thereof engages and closes the filling opening 10 of the vessel 2 and pressurised air is supplied to the interior of the vessel 2, thereby pressurising the vessel. At the same time pressurised air is supplied to the venturi jet 20 within the air inlet 18 via the air inlet hose 31 , and a regulated air pressure may be supplied to the upper region of the holder 30 to selectively displace the downstream end of the venturi jet 20 away from the air pipe 22 by a desired amount such that a selected flow rate of abrasive material is entrained into the flow of pressurised air passing from venturi jet 20 into the air pipe 22, the desired mixture of abrasive material and pressurised air subsequently passing through the outlet pipe 24 via the pinch valve 26 and into the blast hose such that the mixture of pressurised air and abrasive material is supplied to the outlet nozzle. If wet blasting is required, water from a water supply is supplied to the water injection coupling 50 adjacent the outlet coupling 28.

The invention is not limited to the embodiment described herein but can be amended or modified without departing from the scope of the present invention as defined by the appended claims.