Membrane condenser heat exchanger for conditioning of humid gases

Abstract

Here we propose combined process for gas streams dehumidification using porous polypropylene membrane contactor heat-exchanger with liquid coolant absorbent and report the results on its operation performance. The technique enables effective removal of condensable components of gas mixtures to ultimate residual pressures by a synergetic contribution of two effects – suppression of the equilibrium water vapor pressure at low temperatures and water vapor removal by hygroscopic absorbent. The method is examined in the process of air stream dehumidification with ethylene glycol-water absorbents. Experimental data on the process performance at different gas fluxes (0.3–12 m3(STP)·m−2·h−1), pressures (2.5 – 9 bar), chilled absorbent temperatures (−30 ÷ 3 °C) and absorbent compositions (0–100 wt% of ethylene glycol) is reported. It is revealed the performance of contactor is mostly limited by viscosity of the cooling absorbent, allowing to achieve dew point temperature of the processed gas down to −30 °C with a water vapors stage cut over 90% at gas flux over 10 m3(STP)·m−2·h−1 and packing density of hollow fiber membrane up to 3000 m2/m3 with 35%:65% (wt.) water-ethylene-glycol absorbent. A technical scheme for industrial dehumidification setup is proposed and the results of the model setup performance are evaluated in comparison with traditional desiccant, wheel adsorbent and refrigeration processes. It is shown the proposed technique provides much wider range of acceptable gas dew point temperatures as compared to conventional refrigerant process and more preferred energetically compared to desiccant and wheel dehumidification.