Energetic recovery from wastes incineration: an Italian example

The actual attention to the necessity to improve innovative systems of energy recovery, together with the positive trend of increase, both from the qualitative and from the quantitative point of view, of the wastes, leads to the need for today to consider, for the wastes disposal, systems of disposal/treatment that allow a volumes reduction and at the same time an energy and also, if it is possible, a materials recovery. The incineration is absolutely a system that offers both the mentioned opportunities (volume reduction and energy recovery). In fact the incineration is a rather developed system for the wastes elimination based on their energetic characteristics; in these years we have assisted to a considerable improvement both as concerns the efficiency of the plant, and also with reference to the environmental impact containment. The aim of this work is to analyze the wastes incineration plant under construction in Turin (Piedmont, North Italy). This incineration will be able to treat 421.000 t/y of wastes with a LHV = 11 MJ/kg so the thermal power will be 206 MWth. The technology will be a grate combustor, the flue gas treatment will be constituted by an electro filter for the dust reduction, a dry scrubber for the acid gases absorption, injection of CaOH for the reduction of inorganic and organic components and a SCR system for the NOx reduction; the energy recovery will be obtained by a boiler and a stream turbine. In this work we evaluate, in particular, the energetic recovery system. We have analyzed two different kinds of energy recovery: from one side a recovery of electric energy only (electrical configuration) and on the other side a recovery both of electric and thermal energy (cogenerative configuration). The possibilities of substitution of existing energy generating systems are obviously different. These two different kinds of energy recovery are analyzed used the following tools: mass and energy balance in order to obtain information concerning the advantages or disadvantages deriving from the two different energetic recovery configuration as concerns emissive fluxes environmental balance and externalities balance.