INTERNALLY STAGED PERMEATOR PREPARED FROM ANNULAR HOLLOW FIBERS FOR GAS SEPARATION

A polysulfone/polyethersulfone annular hollow-fiber (cube) membrane wa s prepared using a phase-inversion process, which is useful for furthe r preparation of an internally staged permeator (ISP) for gas separati on. This study focused on the techniques of fabricating the polysulfon e/polyethersulfone annular-hollow-fiber membranes and its membrane per meators for gas enrichment. Two homogeneous polymer solutions comprisi ng polysulfone/DMAc and polyethersulfone/NMP/water, respectively, were prepared and extruded with a triple-orifice spinneret into an annular -hollow-fiber membrane that possesses two distinct skin layers and is capable of providing two separation stages internally for gas separati on. The performance of the ISP fabricated from the prepared annular ho llow-fiber membrane was evaluated theoretically and experimentally und er co/countercurrent and countercurrent flow patterns for various bina ry gas mixtures. The mathematical models generally describe satisfacto rily the observed experimental results. A parametric study reveals tha t while, in general, better separation is available at lower values of overall stage cuts, highly purified permeate products could be achiev ed at higher values of overall stage cuts if the concentration of a pe rmeating component in the feed stock is relatively high.