Simulations on Pyrolysis of Different Coals by the Boltzmann–Monte Carlo Percolation (BMCP) Model

The modeling researches on coal pyrolysis either make predictions with empirical parameters under limited conditions or simulate reactions occurs on a nanosecond scale that cannot be compared with experimental data due to the complexity of pyrolysis. The Boltzmann-Monte Carlo percolation (BMCP) model from a covalent bond perspective followed the "dissociation-coupling" mechanism can provide both products' distribution and bonds' population qualitatively. In this work, by introducing a universal method for calculating the average molecular weight of radicals and a correlation method between cycles and the actual residence time, the results of the BMCP model can be used for comparison with actual experimental data. The BMCP model with different assumptions on coupling of radicals is used to simulate pyrolysis with different coals under different temperatures and different pressures. The results of the BMCP model accord well with experimental data not only on a microscale for bonds but also on a macroscale for products under various conditions; the quantitative prediction ability of the BMCP model has been proved, and this indicates that the "dissociation coupling" mechanism can reflect some chemical nature of coal pyrolysis. Furthermore, although apparent activation energies seemed to be different under different assumptions, the minor deviations in various conditions indicate that assumptions on the "coupling" step can hardly affect simulation results and the bond "dissociation" step may be the rate-determining step in the dissociation-coupling mechanism.