A gas injection lance

摘要

A lance for injecting a pre-heated oxygen-containing gas into a vessel containing a bath of molten material is disclosed. The lance (26) includes an elongate gas flow duct (31) from which to discharge gas from the duct. The duct includes (i) inner and outer concentric carbon steel tubes (37, 39) which provide major structural support for the duct, (ii) cooling water supply and return passage means (43, 44) extending through the duct wall from the rear end to the forward end of the duct for supply and return of cooling water to the forward end of the duct, and (iii) a mechanical means in the form of lands (136) on the exterior surface of the duct adapted to hold a layer of frozen slag on the duct. The lance also includes a gas inlet (32) for introducing hot gas into the rear end of the duct. The lance also includes a tip means (36) joined to the concentric tubes at the forward end of the duct. The lance also includes a protective lining formed from a refractory or other material that is capable of protecting the duct from exposure to gas flow at 800-1400 °C through the duct. The lining is a non-metallic material with heat insulating properties when compared to the steel tubes. The lance also includes a swirl means (34) located in the duct for imparting swirl to gas flow through the forward end of the duct.