Dispersed phase holdup and drop size distributions in reciprocating plate columns

Abstract

AbstractThe paper covers an experimental and theoretical investigation of the dispersed phase holdup and drop size distribution for gas‐liquid and liquid‐liquid counter‐current flow in reciprocating plate columns provided with plates having small hole size and free area. The response of the reciprocating plate column is similar to that of liquid‐pulsed columns exhibiting mixer‐settler and emulsion regions. The dispersed phase holdup depends on the dispersed phase flow rate, the vibrating speed of the plate stack, the plate geometry and the number of plates: it was found to be minimum at the transition between the mixer‐settler and emulsion regions.The dispersed phase holdup is modeled incorporating apparent interstitial liquid velocity and the slip velocity to account for the non‐descriptive flow pattern between the phases.The drop size distribution is satisfactorily represented on a Rosin–Rammler Chart. Sauter mean diameter, calculated from the distributions, indicated an advantage in the drop size‐power consumption relation when plates having small hole size and free area are used.Equipment used for fluid‐fluid contacting is often broadly classified as either stagewise or differential contactors. The classification is further sub‐divided as gravity, mechanically‐agitated and pulse‐agitated, depending on the method adopted for interdispersing the phases. Pulse‐agitation involves the use of either reciprocating perforated plates moving vertically up and down the column, or pulsing a phase hydraulically keeping the internal structure of the column stationary.The literature on reciprocating plate columns (RPC) primarily is concerned with the study of liquid‐liquid systems using perforated plates having large hole size and free area. This paper presents the dispersed phase holdup and drop size distributions for gas‐liquid and liquid‐liquid systems in reciprocating plate columns with small perforation diameter and free area for the plate.