Development of water gas shift/membrane hybrid system for pre-combustion CO2 capture in a coal gasification process

In this study, a 2l/min water gas shift/membrane hybrid system for pre-combustion CO2 capture has been developed. To control the concentration of major components such as H-2, CO, and CO2, MFCs were used in experimental apparatus. The gas concentration in these experiments was equal with syngas concentration from dry coal gasifiers (H-2: 25-35, CO: 60-65, CO2: 5-15 vol%). The operation conditions of WGS/membrane hybrid system were 200-400 degrees C, 1-15bar. Steam/Carbon ratios were between 2.0 and 5.0. To separate hydrogen from mixed gas stream, the palladium membrane will be adopted. As steam/carbon ratio increased, the conversion in the HTS reactor increased from 85% to 91% at the condition of 350 degrees C, 1,000ml/min, CO: 65, H-2: 30, CO2: 5%. However the conversion decreased with increasing of gas flow. In WGS experiments, the conversion reached 99.5% at the condition of 1,000ml/min and CO: 65, H-2: 30, CO2: 5%. In the experiments of WGS with membrane reactor, the gas concentration before membrane reactor was H-2: 56.28, CO2: 43.48, CO: 0.24%. The gas concentration of retentate flow was H-2: 35.74, CO2: 63.27, CO: 0.99%. (C) 2011 Published by Elsevier Ltd.