Apparatus and method for particle radiation by frozen gas particles

Abstract

The invention relates to a device for pressure blasting by means of a mixed jet made of particles of a frozen gas and a carrier gas, comprising a nozzle housing, which encloses an outer cavity and an inner cavity, wherein the inner cavity forms an expansion space, which comprises an inlet at its upstream longitudinal end for inducting a liquefied gas into the expansion space, and comprises an outlet opening at its downstream longitudinal end, wherein the outlet opening comprises a much larger cross section than the inlet, and wherein the outer cavity envelops the inner cavity at least partially in the portion of the outlet opening, at least one liquid gas supply, which is connected to the inlet of the expansion space, a support gas supply, which is connected with the outer cavity, and an acceleration nozzle having a nozzle outlet downstream of the outlet opening of the expansion space, the acceleration nozzle initially contracts in flow direction, wherein a carrier gas defined laterally from the outlet opening and has cross section which is variably adjustable.

1 . A device for pressure blasting by means of a mixed jet made of particles of a frozen gas and a carrier gas, comprising:
 a nozzle housing, which encloses an outer cavity and an inner cavity,   wherein the inner cavity forms an expansion space, which comprises an inlet at its upstream longitudinal end for inducting a liquefied gas into the expansion space, and comprises an outlet opening at its downstream longitudinal end, wherein the outlet opening comprises a much larger cross section than the inlet, and   wherein the outer cavity envelops the inner cavity at least partially in the portion of the outlet opening,   at least one liquid gas supply connected to the inlet of the expansion space,   a carrier gas supply connected with the outer cavity; and   an acceleration nozzle having a nozzle outlet downstream of the outlet opening of the expansion space, the acceleration nozzle initially contracts in flow direction, wherein a carrier gas inlet is defined laterally from the outlet opening and has a cross section which is variably adjustable.   
     
     
         2 . A device according to  claim 1 , wherein the cross-sectional area of the carrier gas inlet can be varied through relative movement of the inner cavity with respect to the acceleration nozzle. 
     
     
         3 . A device according to  claim 2 , wherein moving the expansion space is performed in axial direction with reference to the longitudinal axis of the acceleration nozzle. 
     
     
         4 . A device according to  claim 1 , wherein the inner diameter of the expansion space continuously expands in flow direction from its upstream longitudinal end to its downstream longitudinal end. 
     
     
         5 . A device according to  claim 1 , wherein the outer cavity and the inner cavity have substantially circular cross sections. 
     
     
         6 . A device according to  claim 1 , further comprising a dosing device having an inner diameter defining the inlet into the expansion space, the dosing device is an expansion nozzle with a substantially smaller diameter than the inner diameter of the expansion space. 
     
     
         7 . A device according to  claim 1 , wherein the carrier gas inlet comprises a variably adjustable distance between 0 mm and 2 mm, transversal to the longitudinal axis of the device between the outer edge of the outlet opening of the inner cavity and the inner wall of the outer cavity or of the acceleration nozzle. 
     
     
         8 . A device according to  claim 1 , wherein the expansion space comprises an inner diameter of the outlet opening between 5 mm and 70 mm. 
     
     
         9 . A device according to  claim 1 , wherein the volume flow of the liquefied gas and also of the carrier gas can be varied. 
     
     
         10 . A device according to  claim 1 , comprising a variably adjustable volume of the expansion space. 
     
     
         11 . A device according to  claim 10 , wherein the volume of the expansion space is configured variably adjustable by moving the dosage device, which is disposed in the transition portion between the supply of the liquefied gas and the expansion space, in the transition portion and parallel to the flow direction, so that the length or the volume of the expansion space changes. 
     
     
         12 . A method for cleaning or treating surfaces comprising the steps of:
 (a) providing a device for pressure blasting by means of a mixed jet made of particles of a frozen gas and a carrier gas, comprising:   a nozzle housing, which encloses an outer cavity and an inner cavity,   wherein the inner cavity forms an expansion space, which comprises an inlet at its upstream longitudinal end for inducting a liquefied gas into the expansion space, and comprises an outlet opening at its downstream longitudinal end, wherein the outlet opening comprises a much larger cross section than the inlet, and   wherein the outer cavity envelops the inner cavity at least partially in the portion of the outlet opening,   at least one liquid gas supply connected to the inlet of the expansion space,   a carrier gas supply connected with the outer cavity; and   an acceleration nozzle having a nozzle outlet downstream of the outlet opening of the expansion space, the acceleration nozzle initially contracts in flow direction, wherein a carrier gas inlet is defined laterally from the outlet opening and has a cross section which is variably adjustable;   (b) generating a mixed jet made of frozen CO 2  particles and a carrier gas using the device; and   (c) cleaning or treating at least one surface with the mixed jet.