Pilot-plant and laboratory studies on vapor permeation removal of VOCs from waste gas using silicone-coated hollow fibers

In a recent bench-scale study the vapor permeation-based removal of individ ual volatile organic compounds (VOCs), e.g. methanol, toluene from an N-2 s tream was studied using microporous polypropylene hollow fibers having a pl asma polymerized silicone coating on the outside surface of the fiber, The novel vapor permeation process employed bore-side feed flow and vacuum on t he shell-side. The observed separation behavior was described successfully by an analytical solution of a simpler model and by a numerical solution of a more extensive set of model equations based on experimentally-determined behavior of concentration-dependent VOC permeance. The remarkably high sep aration performance achieved in that study on a bench-scale has led to pilo t-plant studies using a larger module. Results of pilot-plant studies using streams containing high concentrations of VOCs, (e.g. 1-8% of methanal, an d 0.3-1.3% of toluene) as well as low concentrations of VOCs (e.g. 0.1% or less of methanol, toluene, ethanol, iz-butanol, tetrahydrofuran, methylene chloride and acetone together) for a hollow fiber module containing 1000 fi bers are reported here. The results for methanol removal from highly concen trated streams have been compared with the results obtained from simulation s of theoretical models developed earlier. Model simulation results describ e the observed pilot plant separation behavior well. These successes have p rompted additional bench-scale laboratory studies with other VOCs (e.g. met hylene chloride), results of which are also reported here; these results ha ve also been compared with the predictions from the models developed earlie r. (C) 2000 Elsevier Science B.V. All rights reserved.