The national and international situation for the definition of integrated systems for the treatment and the final destination of solid wastes presents, today, a significant affirmation of separate collection system aimed to the creation of processes and plants for the reuse and production of secondary materials. Downstream of this, there is, anyway, an important flow of waste that is collected without differentiation; to this flux the rejects deriving from the recycle operations must necessarily be added, and for this resulting flux it is necessary to individuate suitable prospects for disposal. This obtained flow in comparison with the gross waste production is a large percentage; from the point of view of quality, it has a composition deprived of the fractions that more easily can be recovered (metal, glass, organic waste find an appropriate valorization after upstream pre - selection), and it can be considered as constituted of a dry combustible fraction, a wet organic fraction and a substantially inert mineral fraction. In account of the composition and also of the ever increasing interest for the production of energy from non fossil sources, this fraction must be sent to an energetic valorization (by using direct combustion systems, in traditional incineration, or by using innovative systems of gasification); the purpose of this destination relies in the possibility, together with a convenient disposal, to simultaneously produce sustainable energy to be used in the individuated area. On the basis of this general perspective the aim of this work is a careful analysis of the thermal treatment systems for municipal solid wastes, but also for other matrices such as, in particular, biomasses (chiefly wood biomasses) and sludges deriving from wastewater treatment plant, that can also be considered for thermal use. The study is aimed to the analysis both of conventional thermal treatments (direct combustion in incineration plant) and also innovative solutions (especially gasification plants). For this purpose, after a thorough analysis of the scientific literature that allowed the reconstruction of a solid theoretical and technological reference base, and also a careful analysis of the practical real scale implementation state of the art, the different technologies for thermal treatment have been were analyzed in detail, both from an analytical and from an experimental point of view. From the point of view of the conventional, more diffused, thermal technologies we evaluated the performances and environmental effects of these treatments on the three different types of materials. In order to define plant conditions, effects on the quality of receiving context and environmental impact, an analysis of each realization has been performed from the operating scheme until to the environmental effects: the used tools were, in succession, the mass and energy balances to define the plant operating conditions, the tool of externalities and the application of different pollutant dispersion models (ISC3 Short Term and SPRAY) to establish air quality modifications. For a correct mass balance definition, in some cases a deeper knowledge of the original treated material was required, and in these cases it has been necessary to perform laboratory tests (by using analysis instruments as the Mahler bomb calorimeter, the ionic spectrophotometer and more in general by using the instrument of titration). A different approach was required to study innovative technologies, gasification in particular. In this case, in the lack of enough informations about the process parameters, we developed a predictive calculation model, that is based on the evaluation of the mass and energy balances and the chemical homogeneous gas phase equilibria able to regulate the development of the process. This model allows to estimate the quantitative and qualitative production of the syngas, and from this the energy yield of the process. We tested the model by considering a feed composed by MSW (municipal solid waste) and an RDF (refuse derived fuel) alimentation. We also evaluated the effects on results of different qualities of gasifying agent (air, air enriched with oxygen, air enriched with carbon dioxide and air enriched with steam). On the basis of the calculated results and also taking into account the general informations about the more consolidated conventional technologies we have also conducted a comparison, from energetic, environmental and economic point of view, between traditional and innovative thermal treatments. By taking also in account the real possibilities of implementation of these systems, in the final chapter we conducted a comparison among scenarios of waste management dedicated to residual wastes with and without a specific downstream separation stage that, with a mechanical separation, is able to produce three flows: a dry combustible flow, a wet organic flow and an inert flow, with different destinations. On the basis of the so indicated general scheme of the thesis, in the following we report the most important aspects of the obtained results: • through the reconstructed study of performances and a careful literature analysis, it was possible to arrive to a general and full bibliographic review concerning thermal treatments; • from a point of view of the more conventional incineration processes: o a preliminary and operative scheme has been defined as concerns the choice and the verification of the correct technology for thermal treatment of MSW; o it has been constructed and assessed an evaluation procedure able to define the environmental compatibility of biomass and other plants; o a laboratory system of definition of the characteristics of the treated waste in some cases has been considered as convenient and propositive (as for example the definition of the chlorine content in sewage sludge); this aspect can be considered as an important step in the definition of planning the plant scheme. • from a point of view of the innovative processes (in particular gasification) we developed and verified a predictive calculation model for the gasification process; • from a point of view of the comparison between traditional and innovative processes the main differences among the systems have been estimated by analyzed analytical laboratory tests and mass and energy balances; • from the point of view of the comparison between completely thermal scenarios for waste management and scenarios where also MBT procedures are considered it was individuated a procedure for the evaluation and the comparison of these scenarios from the point of view of the environmental impact and also with the aim of the evaluation of the economic aspects.

Analisi analitico sperimentale dei trattamenti termici tradizionali ed innovativi per diverse matrici solide / Panepinto, Deborah. - (2012). [10.6092/polito/porto/2496976]

Analisi analitico sperimentale dei trattamenti termici tradizionali ed innovativi per diverse matrici solide

PANEPINTO, DEBORAH
2012

Abstract

The national and international situation for the definition of integrated systems for the treatment and the final destination of solid wastes presents, today, a significant affirmation of separate collection system aimed to the creation of processes and plants for the reuse and production of secondary materials. Downstream of this, there is, anyway, an important flow of waste that is collected without differentiation; to this flux the rejects deriving from the recycle operations must necessarily be added, and for this resulting flux it is necessary to individuate suitable prospects for disposal. This obtained flow in comparison with the gross waste production is a large percentage; from the point of view of quality, it has a composition deprived of the fractions that more easily can be recovered (metal, glass, organic waste find an appropriate valorization after upstream pre - selection), and it can be considered as constituted of a dry combustible fraction, a wet organic fraction and a substantially inert mineral fraction. In account of the composition and also of the ever increasing interest for the production of energy from non fossil sources, this fraction must be sent to an energetic valorization (by using direct combustion systems, in traditional incineration, or by using innovative systems of gasification); the purpose of this destination relies in the possibility, together with a convenient disposal, to simultaneously produce sustainable energy to be used in the individuated area. On the basis of this general perspective the aim of this work is a careful analysis of the thermal treatment systems for municipal solid wastes, but also for other matrices such as, in particular, biomasses (chiefly wood biomasses) and sludges deriving from wastewater treatment plant, that can also be considered for thermal use. The study is aimed to the analysis both of conventional thermal treatments (direct combustion in incineration plant) and also innovative solutions (especially gasification plants). For this purpose, after a thorough analysis of the scientific literature that allowed the reconstruction of a solid theoretical and technological reference base, and also a careful analysis of the practical real scale implementation state of the art, the different technologies for thermal treatment have been were analyzed in detail, both from an analytical and from an experimental point of view. From the point of view of the conventional, more diffused, thermal technologies we evaluated the performances and environmental effects of these treatments on the three different types of materials. In order to define plant conditions, effects on the quality of receiving context and environmental impact, an analysis of each realization has been performed from the operating scheme until to the environmental effects: the used tools were, in succession, the mass and energy balances to define the plant operating conditions, the tool of externalities and the application of different pollutant dispersion models (ISC3 Short Term and SPRAY) to establish air quality modifications. For a correct mass balance definition, in some cases a deeper knowledge of the original treated material was required, and in these cases it has been necessary to perform laboratory tests (by using analysis instruments as the Mahler bomb calorimeter, the ionic spectrophotometer and more in general by using the instrument of titration). A different approach was required to study innovative technologies, gasification in particular. In this case, in the lack of enough informations about the process parameters, we developed a predictive calculation model, that is based on the evaluation of the mass and energy balances and the chemical homogeneous gas phase equilibria able to regulate the development of the process. This model allows to estimate the quantitative and qualitative production of the syngas, and from this the energy yield of the process. We tested the model by considering a feed composed by MSW (municipal solid waste) and an RDF (refuse derived fuel) alimentation. We also evaluated the effects on results of different qualities of gasifying agent (air, air enriched with oxygen, air enriched with carbon dioxide and air enriched with steam). On the basis of the calculated results and also taking into account the general informations about the more consolidated conventional technologies we have also conducted a comparison, from energetic, environmental and economic point of view, between traditional and innovative thermal treatments. By taking also in account the real possibilities of implementation of these systems, in the final chapter we conducted a comparison among scenarios of waste management dedicated to residual wastes with and without a specific downstream separation stage that, with a mechanical separation, is able to produce three flows: a dry combustible flow, a wet organic flow and an inert flow, with different destinations. On the basis of the so indicated general scheme of the thesis, in the following we report the most important aspects of the obtained results: • through the reconstructed study of performances and a careful literature analysis, it was possible to arrive to a general and full bibliographic review concerning thermal treatments; • from a point of view of the more conventional incineration processes: o a preliminary and operative scheme has been defined as concerns the choice and the verification of the correct technology for thermal treatment of MSW; o it has been constructed and assessed an evaluation procedure able to define the environmental compatibility of biomass and other plants; o a laboratory system of definition of the characteristics of the treated waste in some cases has been considered as convenient and propositive (as for example the definition of the chlorine content in sewage sludge); this aspect can be considered as an important step in the definition of planning the plant scheme. • from a point of view of the innovative processes (in particular gasification) we developed and verified a predictive calculation model for the gasification process; • from a point of view of the comparison between traditional and innovative processes the main differences among the systems have been estimated by analyzed analytical laboratory tests and mass and energy balances; • from the point of view of the comparison between completely thermal scenarios for waste management and scenarios where also MBT procedures are considered it was individuated a procedure for the evaluation and the comparison of these scenarios from the point of view of the environmental impact and also with the aim of the evaluation of the economic aspects.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11583/2496976
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