Integration of SEWGS for carbon capture in Natural Gas Combined Cycle. Part B: Reference case comparison

This two part-paper investigates the performance of different integration possibilities in a Natural Gas Combined Cycle of an innovative reactor for CO2 capture named SEWGS (Sorption Enhanced Water Gas Shift). This activity is carried out under the FP7 project CAESAR financed by the EU community. In part A, several plant layouts starting from completely decoupled hydrogen island and power section up to very tight integration are investigated in order to show the different advantages and performance differences. A sensitivity analysis on main parameters is also carried out. Part B presents three reference cases selected for electricity production: without carbon capture, with post-combustion carbon capture by MEA and with pre-combustion carbon capture by MDEA. These cases are compared with three different SEWGS plants presented in part A. A tight integration between power and hydrogen island allows SEWGS to achieve a lower efficiency penalty than MEA and MDEA (7.5% for SEWGS, 8.4% for MEA and 8.0% for MDEA) with a higher CO2 avoided (95.2% for SEWGS, 90.2% for MEA and 91.0% for MDEA). Decoupling the hydrogen and power islands brings about higher efficiency penalty (12.5%) with 95.3% of CO2 avoided. Finally, an exergy comparison among all the cases is carried out in order to explain the performance differences, outlining the main advantages of SEWGS in high temperature CO2 separation with limited energy consumption.