Incorporation of Scheduling Considerations in Retrofitting Design of Heat Exchange Networks

The objective of this work is to introduce a systematic procedure for incorporating heat integration and process scheduling into the design phase. A hierarchical approach is developed. First, a formulation is developed to account for the anticipated schedules and heat integration during the design phase. Because of the complexity of the formulation for heat integration with varying flows and temperatures, a new targeting approach has been introduced. A linearization approach is adopted by discretizing the searched space for temperatures. Then, integer cuts are added to select the optimal temperatures. This results in a mixed-integer linear programming formulation for the targeting of minimum heating and cooling utilities for the various schedules. In order to synthesize a flexible configuration of the heat integration network, a multiperiod formulation is developed to account for the variations associated with the anticipated schedules.