Rigorous simulation of energy integrated and thermally coupled distillation schemes for ternary mixture

Sharp (99% purity) separation of a ternary mixture, characterised by near u niformly distributed volatility, by direct separation sequence without, wit h forward, and with backward energy integration, by indirect separation seq uence without, with forward, and with backward energy integration, by slopp y separation sequence with forward and with backward energy integration, an d by thermally coupled sloppy separation sequence (Petlyuk system) is rigor ously modelled and optimised. Three feed compositions, namely (Case 1) equi molar A/C ratio with 10% B, (Case 2) equimolar feed, and (Case 3) equimolar A/C ratio with 80% B are compared. Comparison is based on total annual cos ts (TACs) using European and American price systems. The savings in TAC of Petlyuk are uniformly about 28-33% in all the three cases, while the saving s of the energy integrated systems increases together with increasing ratio of B in the feed. In Case 1, Petlyuk system is the winner, with 33% saving s, but a conventional energy-integrated system is handicapped by just a ver y few percent. In Cases 2 and 3, Petlyuk system is not amongst the best str uctures. In Case 2, either the conventional energy-integrated systems or th e energy-integrated sloppy structures win with 35-41%; while Case 3, the en ergy-integrated sloppy structures are the best with about 51% savings. (C) 2001 Elsevier Science Ltd. All rights reserved.