Parametric study of a novel cryogenic-membrane hybrid system for efficient CO2 separation

Abstract Polyimide hollow fiber membrane module has been tested under low temperature for efficient CO 2 separation. Parametric study was carried out to evaluate separation performance of the designed cryogenic-membrane hybrid system. In detail, the effect of stage cut, feed pressure, operating temperature and CO 2 concentration on gas permeance, CO 2 /N 2 selectivity, CO 2 purity and recovery were investigated. The experimental results indicated that operating temperature played an important role in the separation performance. Reducing stage cut would result in the increase of permeance (up to 302 GPU), CO 2 /N 2 selectivity (up to 20) and CO 2 purity (up to 59%), especially under the low temperature (−20 °C). The variation of gas permeance depended on the competition between the compression and swelling effect of the free volume. When the operating temperature and feed pressure were set at −20 °C and 700 kPa, the CO 2 recovery could be improved to 93%. Although the permeance, CO 2 /N 2 selectivity and recovery adversely decreased with the increase of feed CO 2 concentration, the CO 2 purity could be increased to 40% with the feed pressure of 400 kPa. The cryogenic-membrane hybrid system presented a potential in enhancing the CO 2 removal efficiency.