Gas Injection Lance

A lance for injecting gas into a vessel, including:

• a gas flow duct extending from a rear end to a forward end from which to discharge gas from the duct;
• an elongate central structure extending within the gas flow duct from its rear end to its forward end;
• a plurality of flow directing vanes disposed about the central structure adjacent the forward end of the duct to impart swirl to a gas flow through the forward end of the duct;
• cooling water supply and return passages extending through the wall of the gas flow duct and extending from the rear end to the forward end of the gas flow duct for supply and return of cooling water to the forward end of the duct;
• and
• an annular duct tip disposed at the forward end of the duct and having an internal cooling water passage connecting with the cooling water supply and return passages so as to receive and return a flow of cooling water to internally cool the duct tip;
• wherein the lance is made of three modules releasably fastened together by releasable fasteners, said modules comprising:
• 1) a main duct module forming the gas flow duct throughout a major part of the length of that duct and including said water supply and return passages and said annular duct tip,
• 2) a gas inlet module including a tubular body releasably fastened by a first set of said fasteners to a rear end of the main duct module such that its interior connects with the interior of the duct module and a branch tube branching laterally from the tubular body to serve as a gas inlet for inlet of gas to the tubular body and thence to the interior of the main gas module, and
• 3) a central module forming said elongate central structure and said flow directing vanes and releasably fastened by a second set of said fasteners to a rear end of the tubular body of the gas inlet module.