Device and method for protecting an optical observation opening

Abstract

The invention relates to a diaphragm device ( 38 ) and to a method for protecting an optical observation opening ( 39 ), in particular for protecting the observation opening against contaminants from a dirty atmosphere ( 35 ) in a blast furnace or the like, having a nozzle unit and a purging gas chamber ( 43 ), wherein the nozzle unit forms a diaphragm aperture ( 26 ) for the observation opening and is used to form a purging gas flow, wherein the purging gas chamber is formed between an optical surface ( 41 ) of the observation opening and the diaphragm aperture. A purging gas is applied to the purging gas chamber and purging gas can be led through the diaphragm aperture into the dirty atmosphere, wherein the nozzle unit has a flow guiding device ( 31, 49 ) which effects guidance of the flow of purging gas escaping into the dirty atmosphere.

1 . A diaphragm device for protecting an optical observation opening, in particular for protecting the observation opening against contaminants from a dirty atmosphere in a blast furnace or the like, said diaphragm device comprising:
 nozzle unit forming a diaphragm aperture for an observation opening and a purging gas flow;   a purging gas chamber formed between an optical surface of the observation opening and the diaphragm aperture, wherein a purging gas is applied to the purging gas chamber; and   a flow guiding device forming part of the nozzle unit and guiding the purging gas from the purging gas chamber through the diaphragm and into a dirty atmosphere.   
     
     
         2 . The diaphragm device according to  claim 1 , in which the purging gas chamber is conical, tapering in an opening direction of the diaphragm aperture. 
     
     
         3 . The diaphragm device according to  claim 1 , in which the diaphragm aperture is conical, widening in an opening direction of the diaphragm aperture. 
     
     
         4 . The diaphragm device according to  claim 1 , in which the diaphragm device includes an annular duct through which purging gas can be supplied to the nozzle unit. 
     
     
         5 . The diaphragm device according to  claim 1 , in which the flow guiding device is rotationally symmetric relative to a longitudinal axis of the diaphragm aperture. 
     
     
         6 . The diaphragm device according to  claim 1 , in which the nozzle unit includes an internal flow guiding device inducing a helical motion of the purging gas around a longitudinal axis of the diaphragm aperture. 
     
     
         7 . The diaphragm device according to  claim 6 , in which the internal flow guiding device is arranged between an annular duct and the purging gas chamber. 
     
     
         8 . The diaphragm device according to  claim 6 , in which the internal flow guiding device is arranged between an annular duct and the diaphragm aperture. 
     
     
         9 . The diaphragm device according to  claim 6 , in which the internal flow guiding device is arranged between an annular duct and a transition area between the purging gas chamber and the diaphragm aperture. 
     
     
         10 . The diaphragm device according to  claim 6 , in which the internal flow guiding device forms flow ducts whose longitudinal duct axes run transverse relative to a longitudinal axis of the diaphragm aperture, respectively, without intersecting the longitudinal axis. 
     
     
         11 . The diaphragm device according to  claim 10 , in which the flow ducts are formed of drill holes or lamellas. 
     
     
         12 . The diaphragm device according to  claim 1 , in which the nozzle unit comprises an external flow guiding device forming an annular gap surrounding the diaphragm aperture from which purging gas can escape in the shape of a ring. 
     
     
         13 . The diaphragm device according to  claim 12 , in which the annular gap is formed between an inner and an outer diaphragm ring of the nozzle unit. 
     
     
         14 . The diaphragm device according to  claim 12 , in which the annular gap is directly connected to an annular duct. 
     
     
         15 . The diaphragm device according to  claim 12 , in which the annular gap is conical, tapering in the opening direction of the diaphragm aperture. 
     
     
         16 . The diaphragm device according to  claim 12 , in which a gap duct of the annular gap is formed tapering in an opening direction of the diaphragm aperture. 
     
     
         17 . The diaphragm device according to  claim 12 , in which the annular gap is arranged directly on an outer diameter (d) of the diaphragm aperture. 
     
     
         18 . A method for protecting an optical observation opening, in particular for protecting the observation opening against contaminants from a dirty atmosphere in a blast furnace or the like, said method comprising:
 forming a purging gas flow using a nozzle unit, wherein the nozzle unit forms a diaphragm aperture for an observation opening;   applying the purging gas to a purging gas chamber between an optical surface) of the observation opening and the diaphragm aperture; and   guiding the purging gas from the purging gas chamber into a dirty atmosphere using a flow guiding device forming part of the nozzle unit.