A new design method and operation of fully thermally coupled distillation column

•Structural design equations for distillation column are developed.•Multicomponent feed systems are considered for validation of design equations.•The proposed design method provides good initial values for rigorous simulation.•Impact of distillation column structure and column operability is investigated.

From economic point of view, the fully thermally coupled distillation columns have shown benefits in terms of energy and capital cost savings when compared with conventional distillation columns. However, the design of such column systems is a topic of ongoing research because there are more degrees of freedom to deal with during the design phase. In this paper, a design method is presented and used to determine the structures of conventional two-product and Petlyuk columns, and the results show that the proposed design method works well. The steady state models are developed using HYSYS software, and the results show that the proposed design method provides good initial values for rigorous simulation. According to controllability analysis, the steady state models present better theoretical control properties; consistent with controllability results, when the steady state model is studied under closed-loop using PI controllers good dynamic responses for load rejection are obtained.