Simplified design and control of an ideal heat-integrated distillation column (ideal HIDiC)

Abstract

Three kinds of process simplification are derived for an ideal heat-integrated distillation column (ideal HIDiC: S–0) using three heat exchangers between its rectifying and stripping sections. These include one with the heat exchangers located in the top, middle, and bottom of the ideal HIDiC, respectively (S–1), one with the vapor flows from the rectifying section and compressor as hot flows in the three heat exchangers (S–2), and one with the vapor flow from the rectifying section as sole hot flows in the three heat exchangers (S–3). The impact of process simplification is examined in terms of the separation of a binary mixture of ethylene and ethane. The S–1 appears inferior to the S–0 in thermodynamic efficiency, but with comparable dynamic behaviors. The S–2 and S–3 need lower capital investment and operating cost than the S–1, but with a sharp degradation in process dynamics and controllability. Although the augment of heat transfer areas leads to a reduction in operating cost, almost no favorable effect is identified on process operation. To derive a feasible design of the ideal HIDiC, one must therefore exercise a careful trade-off between design and operation via the locations of these heat exchangers. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.