In this paper the authors present a simplified 0D-3D approach for modelling operating conditions of a waste-to-energy plant This innovative methodology combines a 0D lumped parameters model, able to describe the processes of solid and gaseous combustion and the heat transfer within the first radiant channel, with a detailed 3D CFD simulation of the thermo-fluid-dynamic field within the plant combustion chamber. Besides, results from the 0D model allow the definition of input data and boundary conditions for detailed 3D CFD simulation of the thermo-fluid-dynamic field within the plant combustion chamber. In this way, the T2S temperature can be determined using a more efficient and complete methodology. The developed numerical tool, does not employ correlations based on empiric observations or on experimental data regressions and, being phenomenological, is generally applicable to any waste-to-energy plant, and is here applied for the characterization of different operating conditions of an Italian WTE. The analysis allows the verification of the constraints imposed by the European legislation on the temperature of the combustion products and the identification of any issues related to the plant operation. Input parameters are determined from measurements and the obtained numerical results are validated against experiments showing a good agreement.

Municipal solid waste incineration (MSWI) is one of the leading technologies for municipal solid waste (MSW) treatment in Europe. Incineration bottom ash (IBA) is the main solid residue from MSWI, and its annual European production is about 20 million tons. The composition of IBA depends on the composition of the incinerated waste; therefore, it may contain significant amounts of ferrous and non-ferrous (NFe) metals as well as glass that can be recovered. Technologies for NFe metals recovery have emerged in IBA treatment since the 1990s and became common practice in many developed countries. Although the principles and used apparatus are nearly the same in all treatment trains, the differences in technological approaches to recovery of valuable components from IBA - with a special focus on NFe metals recovery - are summarized in this paper.

The gasification of biomass and waste is a potentially high efficiency process for energy generation. However, the appropriate cleaning of the produced fuel gas is a major issue, in particular for tar removal. This study investigates the performance of three new-generation activated carbons, which are able to adsorb a wide spectrum of tars at high temperature, from 750 degrees C up to 900 degrees C. For this purpose, a laboratory-scale hot gas filtration apparatus was designed and set-up. Experimental tests were carried out with naphthalene as the reference tar compound. The selected activated carbons were tested under different conditions of temperature, test duration and naphthalene concentration. The procedure allows evaluating the contributions of adsorption and cracking phenomena on the overall tar removal efficiency. Complete naphthalene removal was obtained with two of the selected activated carbons, at 850 degrees C and 900 degrees C respectively. Simultaneously, a partial reforming of adsorbed naphthalene was observed, and molecular hydrogen was detected in the gas phase. Results were correlated to the differences in porosimetry and chemical surface of the selected activated carbons, as well as to those highlighted by Scanning Electronic Microscopy and X-ray analyses. Finally, a procedure for activated carbon regeneration by carbon dioxide is reported, together with results from preliminary tests. (C) 2016 Elsevier B.V. All rights reserved.

Purpose - The purpose of this paper is to optimize the performance of an incinerator plant in terms of NO emissions and temperature of particles 2 s after the last air injection, which must be above 850°C as established from the Directive 2000/76/EC of the European Parliament and of the Council - December 4, 2000 on dioxins formation in waste incineration plants. Design/methodology/approach - Investigation ismade by coupling proper models developed within three commercial software environments: FLUENT, to reproduce the thermodynamic field inside the combustion chamber of the incinerator plant taken into account, MATLAB, to evaluate the position and temperatures of the particles 2 s after the last air injection, MODEFRONTIER, to change both the secondary air mass flow rate and the equivalent heat transfer coefficient of the refractory walls to fulfill the conflicting objectives of reducing the NO formation and increasing the mean gases temperature as required by the Directive. Findings - The investigations suggest that it is possible to create the conditions allowing the reduction of NO emissions and the fulfilment of the European limits. In particular, the obtained results suggest that increasing the overall mass flow rate of the secondary air and using a different refractory material on the walls, the environmental performance of the incinerator plant can be improved. Research limitations/implications - Many other parameters could be optimized and, at the same time, more detailed models could be used for the Computational Fluid Dynamics simulations. Moreover, also the energy generated at the plant would need a better investigation in order to understand if optimal conditions can be really achieved. Originality/value - The work covers new aspects of Waste-to-Energy (WtE) systems, since it deals with an optimization study of plant design and operating parameters. This kind of investigation allows not only to improve already existing technologies for WtE systems, but also to develop new ones.