To study the simultaneous impacts of distillation column sequencing and heat integration on the Methanol to Propylene

plant’s economy, diff erent distillation sequences for three components separation have been examined. In this study, optimization

has been done by considering Total Annual Cost, TAC, as an objective function and the independent variables,

including the number of trays, distillation column pressure, and temperature levels of refrigeration cycles, by using the

Genetic Algorithm, GA. In order to provide an insight into heat integration’s detrimental eff ects on TAC, optimization has

been performed with and without heat integration. Analysis of the optimization results indicates that heat integration can

reduce the TAC of the separation unit by nearly 50%. Also, scrutinized interpretation of confi gurations over the optimization

results leads to the proposition that the thermal coupling of the direct sequence, with TAC of 238,000$ would exhibit

the utmost performance for light gas separations, which would be more than 10% improvement compared with the simple

direct. Furthermore, the application of the proposed 4-component separation unit reduces TAC by around 10% compared

with the industrial plant. In this regard, an optimization framework has been presented for the systematic design of integrated

below-ambient temperature separation units.

Distillation sequencing · Refrigeration cycles · Heat integration · Economic analysis · Optimization

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