A sequential approach for the synthesis of heat-integrated water networks

摘要: This paper presents a new sequential approach for the design of heat-integrated water networks based on the subsequent solutions of two mixed-integer nonlinear programming models (MINLPs). The first one is a water network (WN) model [1], combined with the model by Duran and Grossmann [2] for simultaneous heatintegration (HI). The goal of this model is to obtain networks with the minimum of freshwater, and heating and cooling utility consumptions. The second model is the stage-wise heat exchanger network (HEN)[3], used in order to sequentially synthesize HENs. The main idea of this solution's approach is to solve the combined WN-HI model with different values of heat-recovery approach temperature (HRAT) and, after the appropriate trade-off between water network and utilities cost is obtained, to perform the synthesis of HEN during the second step. Using this approach, a set of very good locally-optimal solutions for heat-integrated water networks was produced and the best one chosen from amongst them. Both, single and multiple contaminants', problems were used to illustrate the capabilities of the proposed model and solution strategy. The obtained results are close or even better than those reported in the literature, although the sequential approach was used.