Residence time distribution analysis by the modified combined model for the design of continuous refining vessel

Flow analyses with RTD experiments have been made for the fundamental design of continuous refining vessels of metallurgical gas injection systems. The modified combined model is suggested for the analysis of various kinds of RTD shapes and it is very effective for the treatment of tail-data. The plug flow fraction tau(p), which is statistically obtained by the present model as a characteristic parameter of the RTD curve, is very much reliable regardless of the cut-off position of data. The effects of various design parameters such as the gas blowing position, the gas flow rate, the divided blowing with multiple lances, the supplementary bottom blowing, and the installation of dams are examined by means of this model for obtaining design concepts of the vessel. The plug flow fraction tau(p) could be increased by the cell effect of the divided blowing, the minimization of dead zone by the supplementary bottom blowing, and the proper placement of dams.