SYNTHESIS OF COMBINED HEAT AND REACTIVE MASS-EXCHANGE NETWORKS

In this work we introduce the problem of synthesizing combined heat an d reactive mass exchange networks ''CHARMENs''. The synthesis task inv olves the preferential transfer of a certain species from a set of ric h streams to a set of lean streams and at the same time accomplish a s pecified heat transfer task in a cost effective manner. The economic o bjectives of mass exchange and heat recovery are in general incompatib le and need to be addressed simultaneously. The proposed work introduc es a systematic and generally applicable procedure to trade-off the tw o objectives and synthesize a CHARMEN. First, we derive a number of im portant properties of the problem. Based on these characteristics, a t wo-stage targeting procedure is developed. In the first stage, the min imum operating cost ''MOC'' of the network is identified via a mixed-i nteger nonlinear program ''MINLP''. A shortcut linear formulation is a lso devised to identify a near-optimum MOC solution which may be used as an initial guess for the MINLP. The optimum solution to the MOC pro blem results in a natural decomposition of the original CHARMEN proble m into two independent subproblems that may be solved to identify the minimum number of heat and reactive mass exchangers. The applicability of the synthesis procedure is demonstrated by tackling a case study o n the desulfurization of gaseous wastes with simultaneous heat recover y.