Electro Winning from Dilute Solutions at Enhanced Rates using Three-Phase Flow Reactor

Abstract

Enhancement of mass transfer coefficient is highly desirable for economic design of process equipment. The present study is essentially carried out to know the effect of flow variables such as gas and liquid velocities and geometric parameters of the internal on mass transfer coefficients in a three phase fluidized bed. The mass transfer coefficient data were obtained using a string of cones internal in a three-phase fluidized bed electrochemical reactor. The flow system investigated was nitrogen, a fluid electrolyte and spherical glass beads as gas, liquid and solid phases respectively. Limiting current technique was employed to obtain mass transfer data. The internal comprises of a string of cones arranged concentrically on a central rod which is placed coaxially in a three phase fluidized bed. The presence of internal in three phase fluidized beds augmented the mass transfer coefficient significantly. In the present investigation it was found that the effect of gas velocity, liquid velocity, rod diameter and cone diameter was only marginal. However, the influence of pitch, half apex angle of cone and particle diameter was found to be significant. Correlations were developed based on least squares regression analysis for the prediction of mass transfer coefficient in terms of pertinent variables.