Numerical Simulation On Molten Steel Flow In Rh Vacuum Degassing Process

For the purpose of further increasing the decarburization rate and circulation flow rate of molten steel during RH decarburizing process for extra-low carbon steel production, a three-dimensional double-fluid mathematical model is developed, based on a specific 300t real plant RH-MFB characteristics. The commercial software package Phoenics Version 2006 is utilized for the solutions of the mathematic model for the simulations of flow pattern and circulation flow rate upon three main issues: the impacts of RH process parameters on molten steel flow and circulation flow rate; only bottom-blow of Argon, instead of up-snorkel blowing Ar and combined blowing process(with bottom-blow).The result shows that: there is a saturated value of Ar flow rate which is 4000 NL/min for the target RH process. The well known empirical equation is not suitable when Ar flow rate exceeds the saturated value. In later decarburization period, circulation flow rate can increase 12~15t/min while Ar flow rate increases from 3200~3400NL/min to 4000NL/min; two-layer nozzles is better than one and three layers; interleaving two-layer nozzles is better than alignment arrangement; sixteen nozzles is the best version for current equipment. The circulation flow rate can reach max value when spacing interval of two layers reducing from 200 to 150mm; it is better to increase immersion depth to 600mm, which can help circulation flow rate upto 234t/min under 3000NL/min of Ar flow rate.For investigating the feasibility of combined blowing with subsidiary bottom blowing Ar in RH process, which is based on current equipment, and that the only bottom blowing Ar plan has been simulated firstly. The result shows that the fluctuation of molten steel free surface while only bottom blowing Ar is the bottle-neck for the application of only bottom blowing instead of up-snorkel blowing Ar. Flow rate of Ar must be controlled to avoid reoxidization.Numercal simulations and tentative real heat test show that circulation flow rate and later decarburization rate can be increased by appending the bottom blowing. Numercal simulations shows that flow field is better after append bottom blowing Ar and the real heat test shows that carbon content after decarburization can be controlled under 8×10?6while append bottom blowing Ar; bottom blowing Ar flow rate has a little effect on the increasement of circulation flow rate, but the free surface fluctuation is strengthened with the increasment of bottom blowing. The position and size of bottom blowing component, which have great influence on flow field pattern and circulation flow rate, should be 800mm away from ladle center and 150~200mm in diameter.