Generalized retrofit design of multiproduct batch plants

The problem of a generalized retrofit design of multiproduct batch plants i s considered in this paper. Unlike previous research on this topic, which c oncerns only the ways to add a new unit which will be operated in-phase or out-of-phase with the existing units, we get a better result by altering th e existing operating mode between existing units (or between new units). Di sposing of the useless existing units and replacing outworn equipment with new are also considered. We present a new generalized superstructure with a concept of 'group', a collection of units operated in-phase, then formulat e it as an MINLP problem with an implicit or explicit group expression. Fiv e examples will verify the effectiveness of this method. (C) 1999 Elsevier Science Ltd. All rights reserved.