An elevated-pressure cryogenic air separation unit based on self-heat recuperation technology for integrated gasification combined cycle systems

An advanced elevated-pressure cryogenic ASU (air separation unit) for IGCC (Integrated gasification combined cycle) system was proposed based on self-heat recuperation technology. In the proposed ASU, only one distillation column was used against the double columns in a conventional ASU. The N-2 gas drawn from the top of the distillation column is first compressed to elevate the boiling temperature, and then undergo heat exchange with the liquid O-2 stream from the bottom of the distillation column. Both the latent and the sensible heat of the process steams are recuperated in the proposed process, resulting in a large reduction of the energy requirement in ASU. We compared four different cryogenic air separation processes for IGCC systems: conventional low-pressure ASU, conventional elevated-pressure ASU, proposed low-pressure and elevated-pressure ASU based on self-heat recuperation technology. The simulation results show that the energy requirement of the proposed elevated-pressure ASU is the most suitable choice for IGCC systems, which was reduced by approximately 11.1% comparing with the conventional low-pressure ASU when only nitrogen injection is integrated with IGCC systems. (C) 2016 Published by Elsevier Ltd.