High efficiency Trigeneration systems in integrated energy systems

A systematic method has been developed to study the integration of polygeneration systems in industrial processes and/or urban systems. Several aspects are analyzed with a holistic vision. For given system’s boundaries, the energy services and energy requirements are first characterized. This requires the analysis of the different services and production operations needed. In an industrial process, the process requirements are considered by looking at therequirement of the process unit operations. Having identified the possible heat recovery by heat exchange using a pinch analysis, the Grand composite curve defines the energy services to be supplied. This defines a set of energy conversion units that are used to convert the energy resources into useful process energy. The use of mixed integer linear programming techniques based on pinch analysis and mass integration constraints is used to model the optimal integration of the system. It selects the energy conversion unit options, optimizes the value of the flows in the system and optimizes the efficiency of the integrated energy conversion system. This leads to the definition of the overall system balance whose inefficiency is evacuated from the system in the form of heat that could be valorized. Based on an example from the food industry, it is demonstrated how the combination of cogeneration, heat pumping and mechanical vapor compression can be used to increase the energy conversion efficiency of the process.