RH degassing vessels having one up-leg and one down-leg have been used for
secondary refining of molten steel. One of the causes that determine their
lives is the melting of the firebrick on the side surface of the lower vess
el, which is induced by the slag infiltration into the brick. To increase t
he life of the vessel, the authors have proposed an RH degassing vessel wit
h arranged four legs on the bottom of the lower vessel. A down-leg is posit
ioned at the center and three up-legs are arranged around the down-leg. Bot
h the circulation characteristics and the floating behavior of the slag hav
e been examined using a water model with four legs (proposed model). The sl
ag behavior was simulated using colored plastic particles. To induce water
circulation, the air was blown into the up-leg. The results were compared w
ith those of a water model with two legs (conventional model). ( 1 ) In the
conventional model, the side surface of the lower vessel restricts the wat
er inlet into the down-leg. In the proposed model, the water flows uniforml
y into the down-leg because of the down-leg position. ( 2 ) The circulation
flux (i.e. the water circulation rate per unit area of the up-leg) in the
proposed model was not less than that in the conventional one. In both mode
ls, the circulation flux is increased as an increase in the blowing air rat
e. ( 3 ) In the proposed model, the slag gathers the central part of the su
rface of the water in the lower vessel.