Apparatus for abrasive cleaning

Abstract

An apparatus for abrasive cleaning includes an abrasive media storage vessel for storing a supply of abrasive media at ambient pressure. The storage vessel has an outlet for supplying abrasive media into a first gas stream at a first gas pressure in a first flow passage, the first flow passage supplying a mixture of gas and abrasive media to an outlet nozzle. A main gas stream communicates with the outlet nozzle via a second flow passage at a second gas pressure, the second gas pressure being higher than the first gas pressure. The mixture of gas and abrasive media from the first flow passage is entrained into the main gas stream from the second flow passage in or downstream of the outlet nozzle.

1 . An apparatus for abrasive cleaning comprising an abrasive media storage vessel for storing a supply of abrasive media at ambient pressure, said storage vessel having an outlet supplying abrasive media into a first gas stream at a first gas pressure in a first flow passage, said first flow passage supplying a mixture of gas and abrasive media to an outlet nozzle, a main gas stream communicating with said outlet nozzle via a second flow passage at a second gas pressure, the second gas pressure being higher than the first gas pressure, whereby the mixture of gas and abrasive media from said first flow passage is entrained into the main gas stream from said second flow passage in or downstream of said outlet nozzle. 
     
     
         2 . The apparatus of  claim 1 , wherein the mixture of gas and abrasive media from said first flow passage is entrained into the main gas stream from said second flow passage within said outlet nozzle. 
     
     
         3 . The apparatus of  claim 1 , further comprising a first venturi in said first flow passage adjacent an outlet of said storage vessel whereby abrasive media from said storage vessel is entrained into the first gas stream. 
     
     
         4 . The apparatus of  claim 3 , wherein abrasive media from said storage vessel passes into a throat of said first venturi under gravity. 
     
     
         5 . The apparatus of  claim 4 , further comprising a control valve for controlling the flow of abrasive media from said storage vessel into said throat of said first venturi. 
     
     
         6 . The apparatus of  claim 1 , further comprising a second venturi located in or upstream of said outlet nozzle, wherein the mixture of gas and abrasive media from said first flow passage is entrained into the main gas stream from said second flow passage in said second venturi. 
     
     
         7 . The apparatus of  claim 1 , further comprising a pressure regulator for controlling the first and second gas pressures, wherein the first and main gas streams are supplied from a common source of compressed gas. 
     
     
         8 . The apparatus of  claim 7 , wherein the first and main gas streams comprise air streams from a common source of compressed air. 
     
     
         9 . The apparatus of  claim 1 , further comprising a water source for selectively adding water into the main gas flow. 
     
     
         10 . The apparatus of  claim 9 , wherein said outlet nozzle comprises one or more water injection ports, and wherein water is selectively added to the main gas flow in said outlet nozzle from a water supply via said one or more water injection ports. 
     
     
         11 . The apparatus of  claim 10 , further comprising a water control valve for controlling the supply of water to said one or more water injection ports. 
     
     
         12 . The apparatus of  claim 10 , wherein said one or more water injection ports are associated with a non-return valve. 
     
     
         13 . The apparatus of  claim 1 , wherein said storage vessel includes a flow control valve in an outlet at a lower end of said storage vessel, said flow control valve for controlling the passage of abrasive media into the first flow passage. 
     
     
         14 . The apparatus of  claim 13 , wherein said flow control valve comprises a normally open pinch valve. 
     
     
         15 . The apparatus of  claim 1 , further comprising one or more gas vents at outlet nozzle for venting excess pressure from the first gas stream as it enters the main gas stream. 
     
     
         16 . The apparatus of  claim 15 , wherein said one or more gas vents communicate with an outlet passage of said outlet nozzle downstream of said one or more gas vents.