A new structural design procedure for fully thermally coupled distillation columns (FTCDC) utilizing semi-rigorous material balances is proposed and applied to the design of example systems of butanol, BTX and hexane-heptane mixtures. The structural design can be directly incorporated in the design of commercial design software, giving basic information which is required at the beginning of simulation. The performance of the proposed design evaluated from the application to the three example systems with three different feed compositions indicates that the new procedure gives useful design information for the commercial simulation software. It is shown that the proposed procedure provides a comparable result to an existing rigorous structural design method. (c) 2004 Elsevier Ltd. All rights reserved.