Method and apparatus to isolate the cold in cryogenic equipment

Abstract

An apparatus and a method are provided for spraying a cryogenic fluid ( 2 ) to a work piece ( 1 ) which includes a cryogen feed line ( 3 ), at least one delivery nozzle ( 4 ) for delivering the cryogenic fluid ( 2 ), a shroud ( 6 ) which surrounds at least part of said delivery nozzle ( 4 ) and which has a front face with an opening which is directed to the workpiece. The shroud ( 6 ) and the work piece ( 1 ) are movable relative to each other between a working configuration and a maintenance configuration, In the maintenance configuration the shroud ( 6 ) comprises a barrier which prevents or minimizes ambient air from entering the shroud ( 6 ).

1 - 11 . (canceled) 
     
     
         12 . An apparatus for spraying a cryogenic fluid ( 2 ) to a work piece, comprising:
 a cryogen feed line ( 3 );   at least one delivery nozzle ( 4 ) for delivering the cryogenic fluid ( 2 );   a shroud ( 6 ) which surrounds at least part of said delivery nozzle ( 4 ) and which includes a front face having an opening directed to the work piece, said shroud and said work piece being movable relative to each other between a working configuration and a maintenance configuration, wherein in said maintenance configuration the front face is not completely covered by the work piece, and wherein in said working configuration said shroud ( 6 ) is arranged to coact with the work piece ( 1 ) to form an essentially closed space together with the work piece ( 1 );   said maintenance configuration of said shroud comprising a barrier which at least minimizes ambient air from entering the shroud, and said barrier comprises at least one physical cover arrangeable to cover said opening.   
     
     
         13 . The apparatus according to  claim 12 , wherein said at least one physical cover is rotatably engagable with said shroud or optionally slidably engageable with said shroud. 
     
     
         14 . The apparatus according to  claim 12 , wherein a position of the at least one physical cover relative to the shroud is controllable with respect to the position of the shroud relative to the work piece. 
     
     
         15 . The apparatus according to  claim 12 , wherein the at least one cover is moveable into the shroud. 
     
     
         16 . The apparatus according to  claim 12 , wherein said shroud further comprises a gas blowing means positioned close to the opening of the shroud for blowing an inert gas in a direction selected from the group consisting of parallel to said opening, and in a direction from inside the shroud to outside of the shroud, to suppress intrusion of ambient air into the shroud. 
     
     
         17 . The apparatus according to  claim 12 , wherein said shroud further comprises an adjusting mechanism which maintains the gap between the at least one physical cover and the work piece during retraction of the shroud from the work piece. 
     
     
         18 . A method for spraying a cryogenic fluid to a work piece, comprising:
 spraying said cryogenic fluid with at least one delivery nozzle;   providing a shroud for surrounding at least part of said delivery nozzle, said shroud opening toward the workpiece;   arranging said shroud and said workpiece in a working configuration, wherein said shroud and said workpiece are coacting for forming an essentially closed space of said work piece;   arranging said shroud and said workpiece in a maintenance configuration, wherein said opening is not sealed by the work piece;   sealing the opening in said maintenance configuration with a barrier for at least one of preventing ambient air from entering the shroud, and minimizing ambient air from entering the shroud, wherein said barrier comprises at least one cover arranged to cover said opening in said maintenance configuration.   
     
     
         19 . The method according to  claim 18 , further comprising controlling a position of the at least one cover relative to the shroud with respect to a position of the shroud relative to the work piece. 
     
     
         20 . The method according to  claim 18 , further comprising at least partly moving the at least one cover into the shroud during said maintenance configuration. 
     
     
         21 . The method according to  claim 18 , further comprising purging the at least one cover with an inert gas or optionally portions of the at least one cover with an inert gas. 
     
     
         22 . The method according to  claim 18 , further comprising blowing an inert gas in a direction selected from the group consisting of parallel to said shroud opening for suppressing intrusion of ambient air into the shroud, and in a direction from inside the shroud to outside the shroud for suppressing intrusion of ambient air into the shroud.