Energy and exergy analysis of a waste to energy plant and its R1 energy recovery efficiency evaluation

In the present study, in the first part, the energy and exergy analysis have been presented for Silea S.p.A. waste-to-energy plant, located in Valmadrera (LC). The energy analysis has been developed by applying energy balances to all the main components of the power cycle, so that the values of thermodynamic, electrical and boiler efficiency have been determined. The exergy efficiency, moreover, has been performed in order to find the all the losses sources in the plant, identified by the loss of second law efficiency produced by each component. It has been determined, as it was predictable, that the highest exergy destruction rate occurs in the boiler, due to combustion reaction and heat exchange, followed by turbine and condenser. In the second part, the R1 energy recovery efficiency of Silea S.p.A. waste-to-energy plant has been evaluated. The values results above the limit defined by Directive 2008/08/EC on waste and so the waste-to-energy plant can be qualified as a recovery operation system rather than a disposal one. Moreover, two possible solutions to increase its value has been analysed: nominal maximum capacity operating conditions and a cogeneration with district heating plant improvement, showing an effective R1 increase.