Abstract
Studies of a modified oscillating baffle contactor in which stator rings of different sizes have been introduced are reported. The liquid system being used for the study is carbon-tetrachloride-acetic acid-water for which some equilibrium data obtained previously in our laboratory has been extended. An equation describing the equilibrium distribution of acetic acid between water and carbon tetrachloride has been established with fairly high accuracy. The evalution of the performance of the contactor requires a detailed knowledge of drop sizes and the distribution of drop sizes. A high speed photographic technique has been applied accompanied by a laborious manual counting and sizing of the drops and their sizes. From the analysis the drop size distribution taking a log-normal form has been established and the Sauter mean and maximum drop size for different column operating conditions determined. With the values of hold-up of the drop phase measured by the drainage and manometer methods, the interfacial area 'a' has been found. The longitudinal dispersion which occurs in both phases was investigated by dye injection technique and the dispersion coefficients calculated from Peclet number. The relationship between the true, measured and piston flow values of N.T.U. are established. To do this a modification and development based on Rod's method(67) has been proposed to predict the true concentration profile of the dispersed phase corresponding to measured values of acid content in the continuous phase along the column. The complex relationships existing between efficiency, as represented by H.T.U. values, the Ka, K and 'a' values have been presented graphically to explain the column behaviour. In addition, the measured efficiency of an experimental R.D.C. has also been investigated for the purpose of comparison with the O.B.C. The results indicate that the longitudinal mixing in the O.B.C. is not severe. Under certain circumstances, a slight benifit can be expected on the mass transfer rate due to longitudinal mixing.