APPLICATION OF THE GENERALIZED STREAM STRUCTURE IN HEN SYNTHESIS

A systematic procedure is proposed in this paper to incorporate the op tions of merging and/or splitting streams from multiple origins in pro cess synthesis. In particular, design problems associated with the hea t exchanger networks (HENs) are discussed in detail. First, an input-o utput system structure is described to facilitate the derivation of th e modified LP and MILP models for calculating the design targets corre sponding to the operating and capital costs. Next, construction proced ure of a generalized stream structure is presented and the modified NL P model for generating the optimal networks is formulated accordingly. To accelerate the convergence rate of the corresponding iterative sol ution process, an evolutionary short-cut method is provided to produce feasible networks for use as the initial guesses. Two examples are al so presented to demonstrate the effectiveness of the proposed approach . The results show that, without increasing the operating costs, the c apital costs of HENs can be reduced significantly by considering the p roposed stream structure in design.