Study On Enhancement Of Gas-Liquid Mass Transfer By Adsorptive Particles In Slurry Bubble Column

The adsorptive particles can enhance the gas-liquid mass transfer, the slurry system of adsorptive particles are widely used in petrol chemical, biochemical industries because of their intensification effect on the processes. This work studies the enhancement of adsorptive particles on the gas-liquid mass transfer.In this paper, Experiments are performed in a bubble column of 30 mm in inner diameter and 600 mm in height at bubble point and atmospheric pressure. The slurry system used are 4A molecular sieve/isopropanol-water and 4A molecular sieve /tert-butanol-water. The experiments investigate the influence of superficial velocities, solid contents and particle sizes.The mathematic model simultaneously considering heat and mass transfer is developed to describe the transport processes in slurry bubble column. The calculated results of model are used to analyze the influence of solid particles on gas-liquid mass transfer.Based on the results of experiments and model calculation, an overall volumetric liquid-side mass transfer coefficient can be correlated as a function of the following eight independent variables such as superficial gas velocities, solid contents, particle sizes, apparent surface tension, apparent viscosity, apparent density and diffusivity of slurry. In order to analyze the enhancement mechanism of adsorptive particles in slurry system, a heterogeneous, instationary one dimensional model is set up, based on the penetration theory of gas-liquid mass transfer and considered the factors of the absorbability, the physical properties after adding the particles, the distance apart from gas-liquid interface, the particle resistance time of staying in the gas-liquid interface, particle sizes, is developed to describe and discuss the effect of adsorptive particles on the gas-liquid mass transfer in slurry system. The calculated results show that the enhancement factor increases with the increase of absorbability of particles. Enhancement factor increases with the increase of particle residence time in the gas-liquid interface zone in the beginning and then decreases with the increase of residence time; the enhancement factor decreases with the increase of particle sizes. Considering the effect of apparent viscosity of slurry on gas-liquid mass transfer, the enhancement factors increases in lower solid contents and decreases with the solid contents in higher solid contents.