HOLLOW-FIBER MEMBRANE-BASED RAPID PRESSURE SWING ABSORPTION

A novel gas purification technique called rapid pressure swing absorpt ion (RAPSAB) was developed by integrating the best features of membran e contacting, gas-liquid absorption, and pressure swing adsorption (PS A). In this cyclic separation process, a well-packed microporous hydro phobic hollow-fiber module was used to achieve nondispersive gas absor ption from a high-pressure feed gas into a stationary absorbent liquid on the module shelf side during a certain part of the cycle followed by desorption of absorbed gases from the liquid in the rest of the cyc le. The total cycle time varies between 20 s and upwards. Separation o f mixtures of N-2 and CO2 (around 10%) where CO2 is the impurity to be removed was studied using absorbent liquid; such as pure water and a 19.5% aqueous solution of diethanolamine (DEA). Three RAPSAB cycles st udied differ in the absorption part. Virtually pure N-2 streams were o btained with DEA as absorbent demonstrating the capability of bulk sep aration to very high levels of purification. Numerical models develope d predict the extent of purification for pure wafer and the DEA soluti on for one of the simpler cycles. Model simulations describe the obser ved behavior well.