A Novel Method for Heat Integration of Natural Gas Sweetening Process

The natural gas sweetening unit usually involves an absorption column and a distillation column. The absorption column completely removes H2S and CO2 from natural gas, and the distillation column is used to recover the solvent. The main problem is high energy consumption in the gas sweetening process, particularly in the distillation column, necessitating energy optimization of this process. A novel method was used in this study for heat integration of the natural gas sweetening process. To this end, liquid and vapor streams leaving the absorption column entered the top and bottom of the distillation column, respectively. The feed entering the distillation column was preheated by the bottom product. The liquid and vapor streams reduced the cold and hot utilities of the distillation column, and feed preheating reduced the heat duty of the reboiler. The recycled solvent was then pre-cooled by the sweetened gas. According to the results, the proposed method reduced energy consumption by 67%. Moreover, the proposed process could reduce the total annual cost (TAC) of the base process to the maximum value of 66.7%. This reduction in TAC is due to the reduction of operating cost and capital cost by 66.77 and 66.64%, respectively.