Enhancing Flare Gas Treatment: A Systematic Evaluation of Dual-Stage (Amine, CO2 Supercritical) and Hybrid Approaches Using HYSYS

The flaring of associated gas in oil and gas operations contributes significantly to greenhouse gas emissions and represents a loss of valuable hydrocarbon resources. While amine absorption is widely applied for acid gas removal, the use of supercritical carbon dioxide (sc-CO2) for flare gas treatment remains largely unexplored, despite its proven selectivity for hydrocarbons in other industries such as natural product extraction and polymer processing. Conventional flare gas treatment methods face trade-offs: amine absorption achieves high acid gas removal efficiency but offers limited selectivity for heavier hydrocarbons, whereas sc-CO2 extraction enables efficient recovery of higher hydrocarbons but does not fully remove acid gases. This study addresses these gaps by evaluating three two-stage flare gas treatment configurations—dual-stage amine absorption, dual-stage sc-CO2 absorption, and a hybrid of sc-CO2 followed by amine absorption—using Aspen HYSYS V12.1 simulations, with recycling processes considered in each case. The dual-stage sc-CO2 process achieved nearly complete hydrocarbon recovery (100%) and complete H2S removal, but CO2 remained at elevated concentrations in the treated gas. The dual-stage amine process completely removed CO2 and H2S, though with higher energy demand for solvent regeneration. The hybrid configuration combined the advantages of both approaches, achieving complete H2S removal, 100% hexane recovery, 95.02% methane recovery, and a drastic reduction in CO2 concentration (to 0.0012 mole fraction). These results demonstrate that integrating sc-CO2 with amine absorption resolves the trade-off between hydrocarbon selectivity and acid gas removal, establishing a technically viable pathway for flare gas utilization with potential application in gas-to-liquids (GTL) and carbon management strategies