Better solutions for process sustainability through better insight in process energy integration

Increasing process performances and reducing its emissions are two of the major goals of process sustainability. Energy analysis and synthesis techniques allow to stress major elements defining the process integration, not only in terms of energy savings but mainly in terms of rational transformation of energy. This article addresses several results of our experience in the implementation of process energy integration techniques and their contribution to the process sustainability. The method used combines energy integration principles with advanced mixed integer linear programming models and graphical representations to tackle a real life site scale problem. The application, an ammonia production plant, revisits the major rules of the energy integration with the perspective of the overall energy efficiency including combined production of heat and mechanical power for an existing process. With the solutions obtained, our work shows the difficulty of defining process sustainability when cogeneration and process integration with new technologies are considered simultaneously.