The effect of multipass arrangement on the performance in a membrane extractor of fixed configuration

The performance of membrane solvent extraction in a parallel-plate module a rranged, by inserting Vertically several impermeable barriers in the flow c hannel, to create a device of multiple passes in the raffinate phase, has b een investigated. Increasing the pass number, as well as decreasing the cro ss-section area of flowing channels, will increase the fluid velocities, th ereby leading to an increased mass-transfer coefficient. Considerable impro vement of mass-transfer rate in a parallel-plate module of fixed dimensions is obtainable for low flow-rate operations if multiple passes, instead of single pass, are arranged in the phase (raffinate phase or extract phase) w here the mass transfer is dominated by its external film and not by the mem brane resistance. It was also found that the increase in operating cost due to increasing pass number may be ignored, for low flow-rate operations. (C ) 2000 Elsevier Science Ltd. All rights reserved.