Research On Nitrogen Transfer In Typical Municipal Solid Waste Constituents Pyrolysis

With the great development in society and economy, Municipal Solid Waste has increased significantly. MSW Incineration could achieve the goal of reduction, recycle and decontamination, thus it has developed rapidly. However, incineration produces different kinds of pollutants; including nitrogen oxides which may cause acid rain, photochemical smog and do great harm to the environment. MSW has different kinds of constituents and it is quite complicated. The NO_x production pattern and mechanism during MSW pyrolysis and combustion is not clear, especially the NO_x precursors’ release pattern in pyrolysis. Thus, the NO_x precursors’ release characterisitics in the typical MSW constituents’ pyrolysis were studied by using TG-FTIR system; the study provides support and direction for the further mechanism research and technological optimization.Three categories and 5 types of MSW constituents with high nitrogen content were selected, including cloth, rubber and kitchen waste. The pyrolysis property and NO_x precursors’ release property of different kinds of typical constituents were studied. The pyrolysis of cloth and rubber showed mono peak; the kitchen waste showed two and the pyrolysis temperature appeared to be lower for kitchen waste. NH3 is the main NO_x precursor for cloth and rubber, the kitchen waste principally produced HCN and NH3. In conclusion, for different constituents, the selectivity for HCN, NH3 and HNCO varies.The influence of the heating rate to typical constituents’ NO_x precursors’ release property was analysed. With the increase of heating rate, the peak of NO_x 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 NO_x precursors’ release when heating rate changes.The influence of the pyrolysis atmosphere to typical constituents’ NO_x precursors’ release property was also studied. The results show as follows: O2 has little impact on the NO_x precursors’ release of cloth; the impact on rubber and kitchen waste is more significant. Rubber and kitchen waste produce evident NO_x precursors release peak in O2 atmosphere at high temperature. O2 increases the NO_x precursors release for rubber and kitchen waste. However, CO2 restrained the NO_x precursors release for all the typical constituents except for orange peel and the effect of inhibition for HNCO is the most significant.