DISTILLATION COLUMN TARGETS

This paper relates to the design of distillation columns. In particular, it relates to the optimisation of a base case design. Column optimisation involves options such as different reflux ratios, pressures, side condensing/reboiling and feed preheating/cooling. We need to establish heat loads and temperature levels for such modifications and identify the best combined options. The paper presents a methodology based on a combination of thermodynamics and practical aspects of column modification. The methodology gives the engineer targets for design options ahead of design. In addition, it provides targets for the best combination of options. Alongside heat load and temperature targets, the methodology clarifies the effect of design modifications on column capital cost, also ahead of design. The methodology is applicable to nonideal multicomponent systems and complex distillation configurations. There are downstream applications involving distillation column integration in the overall processes and column sequencing. The methodology has been tested in industrial applications involving ethylene, LNG and refinery columns.