Targeting Intermediate Fluid Flow in Batch Heat Exchanger Networks

Batch processes have been extensively used in the process industries due to their appropriateness for small volume scale productions, high value-added products, as well as their adjustability to rapid market changes. Heat integration in a batch process can be carried out in two ways directly or indirectly. Direct heat integration is straight transfer of heat from hot to cold stream through heat exchanger, while for indirect heat integration, an intermediate fluid is involved which carries heat from hot to cold stream. In batch process, transfer of heat from one interval to another interval requires intermediate fluid. The usage of intermediate fluid needs pumping, piping, capital investment, and space. These are important aspects for any process while considering space limitation and capital investment. Minimizing intermediate fluid provides reduction in all these important fronts. In this paper, a graphical algorithm is developed to determine minimum requirement of intermediate fluid flow among time intervals while satisfying the minimum utility targets. The proposed algorithm is proved to be optimum rigorously and illustrated via examples.