Abstract: The parallel operation mode of depentanizer in the existing unit is introduced. In order to improve product quality, the series operation mode of depentanizer is innovatively put forward. Based on the process simulation, the feeding mode and operation parameters under the series operation mode are optimized, and more details of the modification including feed split, tower shell unchanged, and condenser and reboiler schemes are determined. The economic analysis of the depentanizer with double towers in series shows that the comprehensive energy consumption of this scheme is reduced by 37%, low investment and rapid returns are achieved, and the economic benefit is fairly good.

Key words: depentanizer, double towers in series, feed split, modification, energy saving