Wall to bed mass transfer in a three phase fluidized bed in the presence of hourglass promoter

Abstract

newline Three phase fluidized beds are found to have wide applications in process newlinendustries. The present investigation is carried out to investigate the extent of newlineenhancement in mass transfer coefficients occurred due to the presence of newlinehourglass promoter in a three-phase fluidized bed. Enhancement of mass transfer newlinecoefficients contributes to the cost effectiveness of the process equipment. Gas newlineholdup, liquid holdup and bed porosity data are also recorded along with the mass newlineransfer data. The holdup data are calculated from the bed expansion and pressure newlinedrop measurements. The mass transfer coefficient is computed from measured newlineimiting currents at the electrodes fixed flush with the inner surface of the perspex newlineube wall which acted as test section. An equimolar potassium ferrocyanide and newlinepotassium ferricyanide solution in the presence of sodium hydroxide supporting newlineelectrolyte is used as the liquid phase. Glass spheres of different sizes are newlineemployed as fluidizing solids and nitrogen is used as the inert gas phase. newlineHourglasses are arranged concentrically on a central rod with different sizes newline(characteristic length) and pitches placed coaxially in the test section is used as newlineurbulent promoter. The holdup data and mass transfer data are obtained by newlinevarying the geometric variables of turbulent promoter assembly like characteristic newlineength of hourglass, rod diameter, pitch etc and dynamic variables like superficial newlineiquid velocity and superficial gas velocity. newlineThe improvements in the limiting current due to the introduction of the newlinehourglass promoter internal in a three-phase fluidized bed are up to a maximum of newlineseventy percent at lower liquid velocity end and up to twenty percent at higher