Combining thermodynamic, operational and energetic criteria for comparative decision-making in acid gas absorption: a study on high- and low- concentration feedstocks

With the growing concerns about the environmental impact related to waste streams discharge and end-use emissions of harmful contaminants, the process and petrochemical industries are increasingly required to treat sour feedstocks while meeting market demand for high-purity products. In this perspective, efficient purification strategies are essential to convert high-contaminated raw materials into clean products. The most common pollutants in acid gas treatment are H 2 S and CO 2 and their effective removal depends on the selection of the most appropriate purification strategies and operating conditions with respect to their content level. Among the available technologies, absorption in liquid solvent can be considered as the most established one. Hence, this research work aims at the definition of an effective pre-design methodology based on thermodynamic, energy and operational criteria for the comparative selection of the most efficient solvent and operating conditions. To prove the general validity of the procedure, a real industrial case of H 2 S and CO 2 removal by means of common industrial amines (MDEA and MEA) was set up in order to discuss quantitative results. The preliminary outcome highlights key trends in solvent consumption and energy requirements, showing how the co-presence of H 2 S and CO 2 substantially affects process performance. Furthermore, sensitivity and comparative analyses allow identification of optimal operating conditions, providing practical guidance for the selection of the most appropriate operational parameters. The study then proves the effectiveness of the proposed methodology, which could represent a valuable decision-making tool for the design of a wide range of acid gas absorption applications in the future. • The methodology requires the minimum information to enable quantitative decisions. • The relative contributions of physical and chemical phenomena are properly estimated. • Interaction between multiple acid species in the gas stream are taken into account. • Different solvents are compared based on selectivity, effectiveness and energy demand.