Research on pyrolysis of typical component of municipal solid waste and release characteristics of NOx precursor

Abstract: The composition of MSW is complex, but nitrogen in MSW mainly exists in kitchen waste, fabric and rubber. The emission of nitrogen oxides from municipal solid waste incineration and the environmental problems caused by incineration can't be ignored. Further study on the formation and mechanism of NOx in MSW incineration process, especially the precipitation and transformation of fuel-N in the pyrolysis process of MSW, is of positive significance for further reducing the emission of NOx in incineration process and guides the development of low-NOx combustion technology and NOx emission control technology. It is generally believed that the main precursors of NOx are NH3, HCN and HNCO. Studying the generation rules of NH3, HCN and HNCO is an important segment in studying the law of NOx formation. There are two main ways to study the law of NH3, HCN and HNCO produced by biomass pyrolysis: Studying biomass itself and related model compounds. Many researchers had studied the formation of NOx precursors in the pyrolysis of protein/amino acid model compounds. Up to now, there has been no report on the precipitation of NOx precursors in the pyrolysis of typical components of MSW. The typical components of three types of MSW with high nitrogen content were selected; the pyrolysis property and NOx precursors' release property of different kinds of typical constituents were studied. The results indicate that the pyrolysis of cloth and rubber show mono peak, but that of the kitchen waste shows two peaks and the pyrolysis temperature appears to be lower for kitchen waste. The main pyrolysis temperature ranges of fabric, rubber and orange peel were 400-500, 350-500 and 150-400 ℃, respectively. The higher the heating rate, the higher the peak value of DTG curve is. The peak of DTG curve moves to the high temperature zone, the wider the peak width of DTG curve, and the temperature range corresponding to the weight loss increases. NH3 is the main NOx precursor for cloth and rubber, and the kitchen waste principally produces HCN and NH3. In conclusion, for different constituents, the selectivities for HCN, NH3 and HNCO are different. With the increase of heating rate, the peak of NOx precursors' release rate increases and the peak moves towards high temperature zone. The decrease of heating rate increases the degradation of the tar-N at high temperature which produces HCN, NH3 and HNCO. The combination of these impacts leads to different results of the NOx precursors' release when heating rate changes.