Methodologyforpreselectingheat-integratedmass allocationnetworkslikelytobeassociatedwith costefficientHEN
Résumé
Instead of being discarded to the environment with costly treatments, process effluents can be reused and valued for their mass and heat content. This may result in substantial operating costs reduction but require important capital costs. Based on models developed by Ghazouani et al. (2015a,b), a new methodology is proposed to select mass allocation network designs that can potentially lead to an economically interesting heat exchangers network (HEN) without having to designthelatter. Inthenewobjectivefunction,anestimationoftheassociatedHENcapitalcostsis addedtotheoperatingcosts(freshsourcesandutilitiesconsumption). HENcoststakeintoaccount the number of mass streams requiring heating or cooling and a rough estimation of necessary heat exchange surface. Moreover, mixer units are introduced into the initial superstructure to further reduce the number of mass streams participating in the HEN. The selection of the most cost effective units among infinite possibilities is made easier by the changes done to the model previouslymentionned. Besides,themodelresolutionspeedallowsevaluatingfairlyquicklymany possibilities and selecting the most promising ones. The methodology can be very helpful for sequential or simultaneous models designing mass allocation and heat exchangers networks. In this article, HEN design is done sequentially, using an established linear model (Barbaro and Bagajewicz (2005)). The relevance of the proposed methodology is assessed through a case study detailed in a previous work (Ghazouani et al. (2015a)).