Comparison of vapor recompression and bottom flashing methods in energy optimization of natural gas sweetening process

The sweetening of sour gas by amine solvent has attracted a lot of attention due to the high abilityof amines to remove acidic compounds from natural gas. In this process, an adsorption column and adistillation column are used to recover the amine. The operating costs of the conventional sour gassweetening process are very high due to the high energy consumption in the solvent recovery column.Therefore, process energy optimization is very essential. In this research, first, the conventional gassweetening process was subjected to heat integration (HI) so instead of using utility in supplying processenergy, the energy of process flows has been used. Then, the amine recovery column is thermallyintegrated into this process by Vapor Recompression (VRC) and Bottom Flashing (BF) methods. Theresults showed that the HI, VRC, and BF processes reduced energy consumption compared to theconventional process about ۲۵%, ۸۸%, and ۹۰%, respectively. Although the compressor consumptionof the VRC and BF processes is almost the same, the reduction in hot and cold utility consumption inBF is ۳۳% higher than in VRC. So, the BF process performs better than the VRC process.

Keywords:

Sour gas sweetening , Heat integration , Vapor recompression , Bottom flashing