An MILP model for the simultaneous design of mass and heat networks of a collaborative eco-industrial park

摘要

Process integration methodologies have greatly addressed the issue of designing optimal heat and mass recovery networks at the process scale. Lately, with the advent of the concept of industrial ecology, the interest for exploring untapped synergies between industrial sites has arisen; aiming at reducing their resources consumption and the operating costs; thus, forming an eco-industrial park (EIP). In such structure, sharing resources can be done either directly or indirectly through intermediate networks for economic or safety reasons. In this perspective, a new model has been developed to design heat and mass recovery networks between industrial sites on a territorial scale. Based on an MILP model (Ghazouani et al., 2017) optimizing recovery networks at a process scale, specific concepts are added enabling exchanges between companies (sites, clusters, and intermediate mass and heat networks). The purpose is to find a collaborative partnership denned by a global economic objective without taking into account individual economic strategies. A case study is developed based on a virtual industrial zone containing three independent processes found in the literature. In addition, potential interactions with urban water and heat networks are considered in this case study. Finally, an additional opportunity to use low grade heat locally via a thermal membrane distillation unit and to transform it into fresh water is introduced. A sequentialmethodology is proposed consisting of first optimizing individual cluster. Then, the remaining requirements met by external utilities as well as the wastes not recovered internally in each cluster are made available to others through the intermediate networks. Overall, despite the sharp increase in capital costs, the optimal EIP manages to be profitable in many considered scenarios. The cooling utility savings are very important in all the cases (more than 80% of the operating costs). The marginal heat and water costs for the urban networks are very competitive. This suggests that, in this case of a cooperative relationship between industrial sites, the sharing and selling of resources and wastes can be profitable.