2010 Volume 50 Issue 1 Pages 17-25
The gas stirring and fluid flow characteristics in the bath during the combined side and top blowing AOD refining process of stainless steel were investigated on a water model of a 120 t AOD converter. The geometric similarity ratio of the model to its prototype (including the side tuyeres and the top lances) was 1 : 4. Using the reliably evaluated friction factors of the side tuyeres for the model and its prototype to gas streams, based on the theoretical calculations of the gas flow properties in the tuyeres and the top lances and the modified Froude number, the gas blowing rates utilized for the model were still more reasonably and accurately determined. Thus, sufficiently full kinematic similarity between the model and its prototype was maintained. The influences of the gas flow rates for side and top blowing, the tuyere number and the angle between each tuyere on the characteristics were examined. The results showed that under driving of multiple gas side blowing streams, the liquid in the whole bath was in vigorous agitation and circulatory motion during the blowing process, and there was no evident dead zone in the bath. The gas blowing rate of the main tuyeres possessed a determined role on the gas stirring and liquid flow pattern in the bath. With regard only to the stirring, the larger the gas side blowing rate, the higher the stirring work input, the more vigorous the bath and its liquid surface were. At a given tuyere number and gas side blowing rate, the larger the angle between each tuyere, the more uniform the gas stirring to the bath became. The gas jet from the top lance could change the agitation and liquid flow pattern in the bath caused by the gas side blowing streams, making the liquid turbulence enhance, and the larger the gas top blowing rate, the more obvious the relevant change was. The existing tuyere equipment and arrangement of 7 tuyeres with an angular separation of 18° for the 120 t AOD converter could not provide a perfect stirring and uniform liquid flow pattern in the bath. The agitation power densities of the gas side and top blowing jets to the bath were estimated, respectively.
