Retrofit of the acid gas sweetening process for the refinery based on exergy analysis method

Although the acid gas sweetening process in the petrochemical and natural gas industries has continually improved over the past few decades, the energy consumption and process optimization remain a challenge. In this study, based on the process simulation and exergy analysis, the bottlenecks of a typical acid gas sweetening process for the refinery was analyzed using Aspen HYSYS, and the optimization strategies were discussed and proposed. First, a novel low temperature absorption with a lean solvent temperature of 15 °C was developed coupled with the recovery of cold energy of sweet gas, which improved the absorption efficiency and reduced the circulation rate of lean solvent. Then a modified heat pump distillation combining split flow feeding technology was developed. After optimization of the novel process developed, the results indicated that operating cost and overall energy consumption was dramatically reduced by 14% and 22% for the absorption process respectively, and combined with the modified regeneration process, the energy recovery efficiency was further improved. The operating cost, the comprehensive energy consumption and the TAC were totally reduced by 19.3%, 30%, and 13.1%, respectively. Finally, the primary investment analysis indicates that the retrofits are feasible, which provides an alternative for the acid gas sweetening.