Pre‐combustion carbon dioxide capture: A thermo‐economic comparison for dual‐stage Selexol process and combined Sulfinol‐Selexol process

Summary The emission of greenhouse gases from fossil‐fueled power plants is a major concern in power generation sector. Carbon dioxide (CO2) emissions constitute the major portion of the greenhouse gases. Among several opportunities available to reduce CO2, carbon capture and sequestration (CCS) is considered to be a possible option for CO2 mitigation. However, implementation of CCS increases the cost of power generation significantly. The main effort of this study is to explore the technical and economic aspects of a dual‐stage Selexol process and a proposed process named combined Sulfinol‐Selexol process, for pre‐combustion capture. The combined CO2 capture process utilizes Sulfinol‐M solvent‐based process for the selective capture of hydrogen sulfide and dimethyl ether of polyethylene glycol solvent‐based Selexol process for CO2 capture. The performance of both processes is assessed and compared in terms of energy consumptions, operating cost, and capital cost by simulating in Aspen HYSYS V.11. Sensitivity analysis for lean solvent inlet temperature, pressures of multi‐flash system and number of stages of the absorption columns is performed to improve both processes. The proposed combined process is 5.8% more economical than the baseline dual‐stage Selexol process as well as its overall process is simpler. However, after sensitivity analysis, both processes improved, and the dual‐stage Selexol process is found to be 3.31% more economical than the combined Sulfinol‐Selexol process. This study compares and optimizes the dual‐stage Selexol process (DSSP) and a new process configuration named combined Sulfinol‐Selexol process (CSSP) for capturing 99.9% H2S and 90% CO2 from IGCC Power Plant. Results show that the base case of CSSP is more economical than DSSP, while optimized DSSP is more cost effective than CSSP. Optimization of key operating parameters resulted in 25.63% and 18.34% savings in terms of total annual cost for DSSP and CSSP, respectively.