Chapter 9 - Optimal control process of heat exchanger networks

Abstract

The conceptions of feasibility, flexibility, and controllability are explained. The flexibility index and flexibility factor are introduced. Both are calculated for an example of a heat exchanger network. Then, synthesis and retrofit design of flexible and controllable heat exchanger networks as well as the operation under uncertainty are discussed. Further, the dynamic control of heat exchanger networks is explained. The traditional feedback control method reacts on measured deviations of output data from their target values. The disadvantageous possible time delay can be avoided with the model predictive forward control method. The deviations of input data are measured, and the expected outlet responses are calculated using distributed parameter approach and analytical or numerical solutions for the dynamic behavior of the heat exchanger network. In this way, the controller can react earlier than in the feedback method.