Innovative Heat Integration Using Bottom Flashing Method: Energy, Exergy, Economic, and Environmental Evaluations of Natural Gas Sweetening Process

The process of sour gas sweetening by amine has found extensive applications in the chemical industries. This process is typically associated with significant CO2 emissions and energy consumption due to the use of absorption and distillation columns. In this regard, the heat integration of the process is essential to reduce the costs and environmental consequences. A heat exchanger is used in most gas refineries between the two columns which can decrease the consumption utility. The energy consumption of the process is still high due to the presence of a reboiler and a condenser in the solvent recovery column. In this research, vapor recompression (VRC) and bottom flashing (BF) were employed for heat integration. To compare the proposed methods with the conventional approaches, four different procedures were accurately simulated and their energy consumption, total annual cost (TAC), exergy efficiency, exergy loss, and CO2 emissions were compared. The results indicated that BF heat integration outperformed the conventional methods by significantly reducing energy consumption, TAC, exergy loss, and CO2 emissions, while enhancing exergy efficiency, primarily due to the reduction of the need for hot and cold utilities in the recovery column.