Research on the suitability of selected types of waste for their thermal treatment

Wood waste is a very important group of waste, interesting for its potential in material recycling as well as energy recovery. In this large quantitatively and varied qualitatively group of waste, two main types of waste are distinguished: wooden waste and post-consumer wood. The analysis of suitability of post-consumer wood for thermal conversion covered selected wood waste: boxed wood furniture made of wood-based panels and internal door waste, made of MDF. Wastes were not contaminated with chemicals pollutants, without chloro organic compounds in the coating and without wood preservatives, however due to its elementary composition (e.g. high nitrogen content) requires more supervision in the thermal process of their treatment. Under the legislation in force, such waste may be subjected to thermal conversion by combustion only in specially adapted devices. The organization of the combustion process consists on obtaining the best possible ecological and energy effects, while maintaining the economic profitability of the project. The article presents research on the mechanism of formation of nitric oxides during the combustion of wood waste in a grate furnace. Concentrations of the formed nitric oxides have been evaluated depending on the parameters of the combustion process and the size of the combusted grain. The source of nitrogen in tested wastes is urea-formaldehyde resin used as a binder, which in the product does not exceed 10% by weight, but still may be a nitric oxides emission hazard during thermal conversion. Research has shown that the dominant mechanism is the fuel mechanism of nitric oxide formation. The limitation of this mechanism is possible by original methods, which directly interfere with the combustion process in the chamber (observance of the temperature regime, granulation and humidity of the waste, mixing intensity of the waste, primary air flow adjusted quantitatively to the combustion phase on the grate). The article specifies main recommendations for optimizing the combustion process of the analyzed waste on the grate and minimizing the formation of NOx fuels.