Integration of SEWGS for carbon capture in natural gas combined cycle. Part A: Thermodynamic performances

This two part-paper investigates the performance of different integration options of an innovative reactor for CO2 capture named SEWGS (Sorption-Enhanced Water Gas Shift) in a natural gas combined cycle. This activity was carried out under the FP7 project CAESAR financed by the EU community. In Part-A, several plant layouts starting from a completely decoupled hydrogen island and power section, up to very tight integration are investigated in order to outline mutual advantages and performances. Decoupling the hydrogen island from the power plant is beneficial to system flexibility but penalizes the net electric efficiency (45.9% with a CO2 capture of 95.3%). The best overall performance is achieved by a tight integration of the two sections that increases efficiency up to 50.9% with a CO2 capture of 95.2%, thanks also to the possibility of expanding the CO2–steam stream from the SEWGS unit. A sensitivity analysis on the main parameters is also carried out. Part B presents three reference cases selected for electricity production with and without CO2 capture in order to benchmark the innovative solution including by exergy analysis.