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

International audienceProcess integration methodologies have greatly addressed the issue of designing optimalheat and mass recovery networks at the process scale. Lately, with the advent of theIndustrial Ecology concept, the interest for exploring untapped synergies between industrialsites has arisen to reduce their resources consumption and the operating costs; thus,forming an eco-industrial park. In such structure, sharing resources can be realized eitherdirectly or indirectly. Companies sometimes choose to integrate streams provided directlyfrom neighboring industrial partners. Sometimes, for safety reasons or distance betweencompanies, exchanges must go through intermediate networks.In this perspective, a new model is presented to design heat and mass recovery networksbetween 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 introducedenabling modeling direct and indirect exchanges between companies (sites, clusters, andintermediate mass and heat networks). The purpose is to find a collaborative partnershipdefined by a global economic objective without taking into account individual economicstrategies.A case study is developed based on a virtual industrial zone containing three independentprocesses found in the literature. In addition, potential interactions with urban water andheat networks are considered in this case study. Finally, an additional opportunity to uselow grade heat locally via a thermal membrane distillation unit and to transform it intofresh water is introduced. Since it is cheaper to transport water than heat through intermediatenetworks, the model is dealing with a competition for the use of heat and water.A sequential methodology is proposed consisting of first optimizing individual cluster.Then, the remaining requirements met by external utilities as well as the wastes not recoveredinternally in each cluster are made available to others through the intermediatenetworks. These networks are put in competition with local utilities. Overall, despite thesharp increase in capital costs, the optimal EIP manage to be profitable in many consideredscenarios. The cooling 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 arevery competitive. This suggests that, in this case of a cooperative relationship betweenindustrial sites, the sharing and selling of resources and wastes can be profitable