EFFECTS OF THE SWIRL MOTION OF BUBBLING J ET ON THE TRANSPORT PHENOMENA IN A BOTTOM BLOWN BATH

A bubbling jet in a cylindrical bath subject to centric bottom gas inj ection rotated around the vessel axis under a certain blowing conditio n. There exist two kinds of swirl motions: one is closely related to t he so-called sloshing and the other is induced by hydrodynamic instabi lity of a large scale ring vortex enclosing the bubbling jet. Conditio ns describing the occurrence and cessation of the swirl motions have b een studied by many researchers. However, the bubble characteristics, liquid flow characteristics, mass transfer from a solid body immersed in the bath, and mixing time of the bath have not been clarified under swirl motions. This study was made to investigate the effects of the swirl motions on the above mentioned transport phenomena using a high- speed video camera, an electroresistivity probe, a laser Doppler veloc imeter, an electrochemical sensor, and an electric conductivity probe. In order to stop the swirl motion, a cylindrical pipe was brought int o contact with the bath surface. The swirl motion was found to enhance the mass transfer coefficient and reduce the mixing time significantl y. This fact allows us to develop new metallurgical processes using sw irl motion. It should be kept in mind, however, that the errosion of v essel wall also is enhanced by swirl motion.