Simulation and Optimisation of Water and Energy Integration Systems (WEIS): An Innovative Approach for Process Industries

The improvement of water and energy use is an important concern to diminish economic issues and the total environmental burden produced by the activities of end-us sectors. Industry is one of the main contributors of the final energy consumption, associated GHG emissions, freshwater consumption and wastewater discharges. The concept of water-energy nexus has been introduced to analyse the interdependencies between water and energy use. In its turn, the methodology of process integration has been introduced to exploit the benefits of the interdependencies between several resources. In this work, two innovative assets are introduced: the concept of Water and Energy Integration Systems (WEIS) and a computation tool created for the purpose to assist on Engineering projects related to the installation of these systems designated as ThermWatt (developed with the Modelica and Python languages). Two case-studies are analysed and assessed. For respectively case-studies 1 and 2, it was assessed an 8.80% and 7.92% total energy consumption reduction, a 23.71% and 38.57% total water consumption reduction in the studied water system have been estimated. It has been assessed a payback time of 22 months for case-study 1 and 34 months for case-study 2. It has also been assessed a 2.42 and 1.76 kton CO2,eq/year for case-studies 1 and 2, respectively. The results for final assessment indicators proved that the conceptualized WEIS projects are robust in terms of eco-efficiency, circular economy potential and strategic objective achievement potential, with a 6.46% and 4.00% improvement for the aggregated eco-efficiency indicator having been obtained for respectively case-studies 1 and 2, a null water discharge for both case-studies and a level of 8.58% and 6.69% of recirculated heat over total energy consumption.