Based on(lecarburizah(m math model for RH process

the decarburization behavior of a 210 t RH unit has been studied to analyze the effect of vacuum

lifting gas flow rate and up-leg inner diameter on decarburizing process. At condition of natural decarburization

according to results of sampling analysis to calculate de('arburization rate constant K

c

it was found that the whole (lecarburization process was divided into two phases: quick decarburization phase ami decarburization stagnated phase. The results showed that with increasing vacuum

the decarburizing rate increased and end [C

]

decreased ;with increasing gas flow rate the increase of decarburizing rate was not outstanding; using suitable up-leg imier diameter was available to get larger decarburizing rate ； and the decarburizing rate constant could be up to 0. 287 min

-1

at quick dec'arburization phase.