IGCC precombustion CO₂ capture using K₂CO₃ solvent and utilizing the intercooling heat recovered from CO₂ compressors for CO₂ regeneration

CO₂ capture (CC) using hot K₂CO₃ solvent in integrated gasification combined cycle (IGCC) plant is a promising technology for CO₂ emission reduction. Based on pilot scale trials, an innovative IGCC system with CC using hot K₂CO₃ solvent is proposed, in which the intercooling heat between CO₂ compressors is recovered for CO₂ regeneration (IGCC+CC+HR). Thermodynamic performance and exergy and energy utilization diagram (EUD) analysis are presented. Results show that recovery of the intercooling heat between CO₂ compressors reduces the steam extraction requirement from turbines for CO₂ regeneration by around 18% and enhances the efficiency of IGCC with CO₂ capture (IGCC+CC) plant by 0.3-0.7 percentage points. With 90% CC, the efficiency of the IGCC+CC+HR plant is around 35.4% which is higher than IGCC+CC plant using Selexol technology. Compared to IGCC, the energy penalty for CC in IGCC+CC+HR plant is mainly caused by the exergy losses in CO₂ separation (45.2%), water gas shift (WGS) (28.5%), combined cycle (20.7%) and CO₂ compression units (5.6%). EUD analysis shows that the IGCC+CC+HR plant realizes good match of the energy levels between the intercooling heat and the recovered steam for CO₂ regeneration, thereby obviously reducing the exergy losses in CO₂ compression and separation units and improving the plant efficiency. The results presented in this paper confirm the sources causing the energy penalty for CC in IGCC power plant and the new IGCC+CC+HR system helps to reduce the energy penalty for CC in IGCC power plant based on solvent technologies.