In this paper, the synthesis of all the functionally distinct thermally coupled distillation schemes for an n-component mixture has been studied. The concept of the intended individual splits has been proposed with which all the inherent distinct separation sequences can be generated for a multicomponent distillation. The first splits of the feed mixture have been used to calculate the total number of the functionally distinct thermally coupled schemes for an n-component mixture. 22 functionally distinct thermally coupled schemes for a four-component mixture, and 719 for a five-component mixture, have been identified. A simple and easy-to-use procedure is presented to draw all the functionally distinct thermally coupled distillation schemes for separating an n-component mixture into its pure components. The procedure can generate all the thermally coupled schemes included in the available superstructures for an n-component mixture. Moreover, some new feasible thermally coupled distillation configurations have been found which are not included in the known superstructures. This guarantees that the global optimum thermally coupled configuration for a multicomponent distillation can be obtained by the optimisation methods.
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