Application of energy-direction factor diagram for exergy analysis of a distillation column.

Abstract

An energy-direction factor diagram elucidating both the exergy required for distillation and the irreversible exergy loss in a distillation column is proposed. For this purpose the concept of a reversible distillation column with interstage heat exchangers is introduced and the energy exchange between the energy-donating processes and the energy-accepting ones is discussed. Although it is composed of a finite number of stages, this reversible column may theoretically perform separation without exergy loss. By comparing a real distillation column with the corresponding reversible one with the same number of stages, the irreversible exergy loss in the distillation column can be obtained, facilitating a visual grasp of its thermodynamic characteristics.