Simulation and energy performance assessment of CO2 removal from crude synthetic natural gas via physical absorption process

Abstract

The paper presents an energy performance assessment of CO₂ removal for crude synthetic natural gas (SNG) upgrade by Selexol absorption process. A simplified process simulation of the Selexol process concerning power requirement and separation performance was developed. The assessment indicates that less pressure difference between crude SNG and absorption pressure favors the energy performance of CO₂ removal process. When both crude SNG and absorption pressures are 20 bar, CO₂ removal process has the best energy performance. The optimal specific power consumption of the CO₂ removal process is 566 kJ/kgCO₂. The sensitivity analysis shows that the CO₂ removal efficiency would significantly influence the total power consumption of the removal process, as well as higher heating value (HHV) and CO₂ content in SNG. However, the specific power consumption excluding crude SNG and SNG compressions changes little with the variance of CO₂ removal efficiency. If by-product CO₂ is compressed for CO₂ capture, the process would turn into a CO₂-sink for the atmosphere. Correspondingly, an increase of 281 kJ/kg_CO2 in specific power consumption is required for compressing the separated CO₂.