Gas holdup and volumetric liquid-phase mass transfer coefficient in solid-suspended bubble columns.

Abstract

The effects of column dimensions, gas velocity and the properties of liquid and solid particles on the gas holdup s6 and the volumetric liquid-phase mass transfer coefficient kLain the solid-suspended bubble columnof liquid-solid batch operation were studied experimentally. The presence of suspended solid particles in the bubble column reduces values of sG and kLa, and their reduction by an addition of solid particles to the column is high in the transition regime and low in the heterogeneous flow regime. Based on these observations, empirical equations for % in transition flow and in heterogeneous flow, and an empirical equation for kLa a applicable to the above two flow regimes are proposed.

New Approaches for Theoretical Estimation of Mass Transfer Parameters in Both Gas-Liquid and Slurry Bubble Columns

“…It is worth noting that the predictions of both equations agree with each other very well. Correlations for gas holdup in the transition regime are proposed by Koide et al (1984) and Tsuchiya and Nakanishi (1992). Hughmark (1967), Akita and Yoshida (1973) and Hikita et al (1980) derived gas holdup correlations for the heterogeneous flow regime.…”

“…The effects of alcohols on gas holdup were discussed and the correlations for gas holdups were obtained by Akita (1987a) and Salvacion et al (1995). Koide et al (1984) argues that the addition of inorganic electrolyte to water increases the gas holdup by 20-30 % in a bubble column with a perforated plate as a gas distributor. Akita (1987a) has reported that no increase in gas holdup is recognized when a perforated plate of similar performance to that of a single nozzle is used.…”

“…has proposed a graphical correlation of flow regimes with column diameter and u G . Another attempt has been made to determine the flow regime boundaries in bubble columns by using u G vs. gas holdup curve (Koide et al, 1984). The authors recommended that if the product of column diameter and hole size of the distributor is higher than 2×10 -4 m 2 , the flow regime is assumed to be a heterogeneous flow regime.…”

Gas holdup in a gas-liquid-fiber semi-batch bubble column

“…Kara et al (1982) and Gandhi et al (1999) found that the gas holdup decreased with increasing solid concentration, but the effect was less significant at higher solid concentrations. Koide et al (1984) reported that the effect of solid concentration on gas holdup was larger in the transition flow regime.…”

“…Gas holdup behavior in gas-liquid-solid (GLS) bubble columns, in which the solid material is spherical or irregular like glass beads, sand, or coal particles, has been extensively studied by various investigators (Kara et al, 1982;Kelkar et al, 1984;Koide et al, 1984;Banisi et al, 1995b;De Swart et al, 1996;Krishna et al, 1997;Li and Prakash, 1997;Gandhi et al, 1999). These studies show that the presence of a solid particle in a bubble column decreased gas holdup from that observed in simple gas-liquid (GL) systems.…”