Study on pyrolysis mechanism of coal in hydrogen-rich atmosphere based on reactive molecular dynamics simulation.

Due to the co-combustion of hydrogen-rich atmosphere and coal in power plants has a great influence on NO X emission, it has been studied by more and more researchers. Therefore, the study of the effect of hydrogen-rich atmosphere on coal pyrolysis mechanism provides a theoretical basis for subsequent application in power plants. In this paper, reaction molecular dynamics simulation is used to investigate the pyrolysis mechanism of Henan anthracite coal within the temperature range of 300–3600 K. The consistency between the activation energy, TG curve, and gas release characteristics derived from the ReaxFF simulation and the experimental results provides evidence for the validity of this method in investigating the pyrolysis mechanism of coal. Furthermore, the pyrolysis behavior of Henan anthracite coal in N 2 , H 2 , and NH 3 atmospheres with varying temperatures are studied. The pyrolysis of Henan anthracite coal can be categorized into three distinct stages under varying atmospheric conditions, as revealed by the simulation findings. Compared with N 2 pyrolysis atmosphere, H 2 and NH 3 pyrolysis atmospheres can reduce the release of CO, reduce the activation energy, promote the degree of pyrolysis and accelerate the pyrolysis process. NH 3 atmosphere has more obvious influence on the coal pyrolysis process. Also, HCN (NO X precursor) generation reactions during pyrolysis are revealed in N 2 , H 2 and NH 3 atmosphere. H 2 and NH 3 pyrolysis atmospheres can increase the number of HCN generation reactions and change the distribution of HCN generation reactions. The analysis of HCN formation reaction shows that CN and H 2 CN are the main precursors of HCN. • Henan coal pyrolysis is studied via ReaxFF MD. • The macromolecular model of Henan coal has been verified. • In NH 3 atmosphere, the activation energy of Henan coal pyrolysis is reduced. • The HCN generation reaction in different atmosphere is proposed. [ABSTRACT FROM AUTHOR]