Mathematic And Physical Simulation On Top And Bottom Combined Blown Technology In CISC

The top and bottom combined blown smelting technology has been carried out since seventies in the last century. It has the advantage of strong stirring to achieve balance for the reaction in bath and to reduce loss of Fe and of controlling forming slag easily. So it has both of top blown's and bottom blown's advantages. Because of the better technological and economic effects, the combined technology leads to the converter's developmental orientation since eighties in the last century.After hot metal preprocessing and secondary refining technology achieved, long life combined blown converter had been developed in order to ensure high quality and low cost molten steel. It can reduce refining periodic time and improve rhythmic production. The key to implement combined blowing technology is how to insure life-span of bottom nozzle as long as campaign of converter. It is likelihood that converter has long campaign by using slag splashing and slag-metal mushroom nozzle technology. In this paper considering converter equipment and steel category characteristics, study on bottom blowing flowrate, the best time of N2 switching to Ar, the operating parameters of combined blowing were carried out by the numerical, physical and trail experiments. In order to make full use of combined blowing advantages it is provided theoretical and practical basis for combined blown converter in Chongqing Iron and Steel Company (CISC).The mathematic model of heat transfer between bottom blown gas and molten steel is established. The minimal flowrate of N2 and Ar which is critical to form mushroom is provided under different bottom blown patterns.The mathematic model of [N] component in molten steel is established too. The relationship between [N] component in molten steel and refining time and the switch point of N2-Ar are obtained by the model.The fluid flow behavior of steel bath in combined blown converter under different operating parameters is calculated respectively by employing the finite volume software FLUENT. And the fluid flow behavior is studied and compared under different blown ways.The process parameters (top lance levels,top blown flux and bottom blown flux) of top blown and combined blown are estimated by water model simulation experiment. And the optimizative patterns are further provided.The trail experiment shows that [C]×[O],the content (FeO) of final slag and decreased under the same of end-point control after the technology of combined blown...