This paper proposes the definitions for intrinsic and extrinsic exergy losses based on a two-level idealization concept, i.e. the reversible operation and the thermodynamic equilibrium operation. The definitions and analysis steps for the plate type simple distillation operation both on the overall column level and on the individual stage level are provided. The analysis of a de-ethanizer column demonstrates the quantitative results of the exergy loss profiles as well as the effects of design modifications based on the information provided by these profiles.