Design of hollow fibre membrane modules for soluble gas removal

Asymmetric PVDF hollow fibre modules coupled with a concentrated alkaline solution were investigated both experimentally and theoretically for soluble gas removal such as H2S or SO2 from gas streams. Each of the modules used consisted of a bundle of hollow fibres having a skin layer at the outer edge of the hollow fibre. A gas mixture containing either 17.2 ppm H2S or 3000 ppb SO2 in balance of N-2 was fed into the fibre lumen and was in countercurrent contact with a 10% NaOH solution fed in the shell side of the modules. Laminar parabolic velocity profile was adopted to characterize the flow of the gas mixture in the hollow fibre lumen. Effects of membrane pore structure parameters such as pore size, pore size distribution and effective surface porosity on the membrane's coefficient were examined theoretically. Subsequently, studies on the module performance and design analysis were also carried out with consideration of the membrane pore structure parameters and the predicted values agreed very well with the experimental data in most cases. Finally, a graphic method is outlined, which enables a quick estimate of the design parameters of such systems for soluble gas removal. (C) 2000 Elsevier Science Ltd. All rights reserved.