Patent ID: 7704446

Claim:
Apparatus for injecting gas at a temperature of the order of 1200° C. into a vessel, comprising; a gas flow duct extending from a rear end to a forward end from which to discharge a gas from the duct; a central body within a forward end region of the duct and co-acting therewith to form an annular nozzle for the discharge of gas from the duct; and a plurality of flow directing vanes disposed about the central body to impart swirl to a gas flow through the nozzle; wherein the flow directing vanes have substantially straight leading end portions radiating outwardly from the central body and extending along the duct, substantially helical trailing end portions extending helically about the central body toward the front end of the duct, and transition portions joining the leading end portions to the trailing end portions and shaped so as to merge smoothly with both the leading end portions and the trailing end portions and to smoothly and progressively change shape between them, and wherein each vane rotates through an angle in the range of 80°-120° between its leading edge and trailing edge.