| 摘要 |
A generally cylindrical lance is fitted with a nozzle block, extending into a recess formed at the downstream end of the lance. Within the lance are formed concentric gas feed tubes, which are placed in individual fluid communication with flow passages through the nozzle block. The nozzle block is sealingly connected to the open downstream ends of the gas feed tubes such that the mixture of gases from the respective tubes within the lance is prevented. The nozzle block is provided with an interchangeable jet nozzle element to provide a high-speed central gas flow. Located about the central nozzle, preferably in a concentric fashion, are outer nozzle means through which gas or gas mixtures pass at a relatively slower speed. Gases emerging from the nozzle block flow in a parallel fashion, such that the gases may mix or combine at the point of incidence on a molten bath surface. A flow change-over arrangement enables a different gas to be passed through at least one nozzle means as desired. |
