Conceptual design of adsorptive recovery of ethane from residue gas stream using Na-ETS-10

Abstract

This work provides the conceptual design of a pressure/vacuum swing adsorption cycle for recovering ethane from the residue gas stream (a mostly methane stream) using Na-ETS-10 as the adsorbent. The conceptual design for treating a stream with 2.4% ethane (and the rest methane) evolved from a simple 4-step cycle to more complex configurations which were able to simultaneously improve the ethane purity and recovery. Feed temperature played a key role in the cycle performance in terms of purity and recovery. The minimization of the recompression work of the light product (methane) was achieved by proposing a cycle design which includes a heavy reflux step at high pressure and a further pressure equalization step. Purity values up to 88% ethane with recoveries of 95% and productivities higher than 0.4 mol ethane/m3(ads)s were quantified through the optimization of the operating conditions for the reduced energy-cost adsorption cycle suggesting an alternative for ethane recovery in gas processing plants.