Mathematic Simulation Of Nitrogen Release Rule During Coal Pyrolysis

Due to the complexity of nitrogen released reaction in coal and the lack of effective experimental methods, there is less sound understanding for the formation and release of precursors of NOx, which are HCN and NH3, during coal pyrolysis. In this paper, a mathematic model that describes the reaction route and mechanism of nitrogen and predicts the formation of HCN and NH3 by kinetics during coal pyrolysis has been developed based on the CPD model. By comparing simulation of HCN and NH3 values with experimental data, the nitrogen release rule during coal pyrolysis is discussed.The conclusions are as following:The successful predict of HCN formation indicates that HCN result from the thermal cracking of N-containing heteroaromatic ring during second pyrolysis of tar, and H radicals take a important part in HCN formation.The disagree simulation of NH3 formation show that the reaction route of nitrogen described in the model is different from the actual ,or the factor influencing NH3 formation are not enough to describe NH3 release in the model.The yield of NH3 vary irregularly with coal rank, the coals withsimilar rank release diferrent yield of NH3, which indicate coal rank that has a strong relation with the amount of volatiles in coal is not the decisive factor influencing NH3 formation, and proves that not all of NH3 come from volatile matters.With the the amount of volatiles increasing ,the yield of HCN increases.The yields of HCN and NH3 increase with increasing temperature.