Estimating a target price to regenerate bio‐oils post hydrogen sulfide removal

Bio‐oils such as conventional soybean, high‐oleic soybean, canola, and sunflower are valuable as bio‐solvents for removing hydrogen sulfide (H2S) from natural gas. Preceding bench‐scale studies indicate that more than 90% of H2S can be removed from a gas stream; economic analysis of such a process is necessary to determine the solvent regenerative power required and cost constraints on a to‐be‐determined solvent regeneration scheme. With the goal of processing 1000 kmol·h–1 of sour gas and removing 99.9% of H2S from gas streams with various feed concentrations, the design of an absorption unit to process natural gas using bio‐oils as the absorbing solvent was carried out through equilibrium stage analysis. A graphical method combined with the Kremser method found that a trayed tower with 14 stages, a 2 m diameter, and 8.5 m height could meet these goals successfully with a bio‐solvent flow rate of 120 kmol·h–1. Capital costs were centered on the price of an extraction column designed to meet the desired throughput. Comparison with conventional amine gas treatment was used to set a limit for the cost of treating a unit of gas, and sensitivity analysis explored the relationship between solvent recycle and cost of treating the gas. This study found that the economic viability of using bio‐oils as gas‐sweetening agents depended on developing a solvent regeneration scheme capable of recycling more than 98% of the bio‐oil bio‐solvent. The development of such a scheme is unlikely, and the overall process of using bio‐oils to sweeten sour gas is likely not economically viable. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.