270782 Preliminary Studies of CO2 Removal From Simulated Pre-Combustion Syngas Via a Pressure Swing Membrane Absorption Process
In a conventional integrated gasification combined cycle (IGCC) for coal as a solid fuel, pre-combustion CO2 capture from post-shift reactor synthesis gas is of significant interest since CO2 (~40% of the dry gas) is present at a much higher partial pressure. The low temperature water gas shift reactor product stream is likely to be available at ~20 atm and around 150-2000C. In a conventional IGCC plant the post-shift reactor synthesis gas is cooled, humidified and expanded to recover some electrical energy and then sent to Claus and Selexol units for H2S and CO2 separation and a purified H2 stream. The object of this research is to carry out CO2 absorption at a high temperature and pressure to purify the hydrogen and obtain simultaneously a purified CO2 stream. Helium was used here as an inert surrogate for H2.
Laboratory-based preliminary experiments were carried out via an advanced pressure swing absorption-based device and a cyclic process to produce purified helium at a high pressure and simultaneously obtain a purified CO2 stream useful for subsequent sequestration steps. The device employed was a hydrophobized porous membrane absorber containing a CO2-selective high-temperature stable absorbent on one side and a simulated post-shift reactor synthesis gas introduced periodically on the other side. We will illustrate the nature of the cyclic process and the usefulness of various steps in producing the desired level of purification.