TOP-BLOW LANCE HAVING EXPANSION CONTROLLED LAVAL NOZZLE

摘要

PROBLEM TO BE SOLVED: To improve blowing efficiency by feeding an optimum oxygen quantity at each blowing step which is achieved by maximizing the pressure range of gaseous oxygen spouted from a Laval nozzle of a top-blow lance for blowing. SOLUTION: In the top-blow lance for blowing metal spouting the gaseous oxygen, part of the Laval nozzle 1 fitted to the tip part of the lance is made to an inserting structural body 2 and a gap 6 is arranged between the lance and the inserting structural body. The one end of the gap is opened into a lance secondary-pressure chamber and the other end of the gap is opened in a small hole existing in the inner surface of the Laval nozzle between a throat hole and a blowing-out hole of the Laval nozzle.