Simulation of pyrolysis in low rank coal particle by using DAEM kinetics model: Reaction behavior and heat transfer

A comprehensive and systematic study on the fundamental pyrolysis behaviors of a single coal particle was performed in this study. The pyrolysis characteristics of coal was investigated by non-isothermal thermo gravimetric analysis whereas the reaction kinetic parameters were obtained by using the distribute activation energy model (DAEM). As three heating rate profiles were applied (10, 20 and 30 degrees C/min) in TG/DTG experiments with a final pyrolysis temperature of 900 degrees C, the obtained kinetic parameters, i.e., activation energy (E-0), pre-exponential factor (k(0)) and standard deviation (sigma) were 186.5 kJ/mol, 3.96 x 10(10) s(-1) and 39.5 kJ/mol, respectively. When these calculated kinetic parameters were used to predict devolatilization curves, the simulation results were in well agreement with the experimental data. As such, a one-dimensional, time-dependent particle pyrolysis model was proposed to characterize the detailed chemical and physical phenomena occurred within a pyrolyzing coal particle. It is found that this model successfully predicted the mass fraction residue and temperature profiles inside the coal particle. In addition, the effect of particle size on pyrolysis performance was also investigated through simulation. It is expected that such a model can be integrated with CFD simulation to provide useful insight for the design of a practical coal pyrolysis reactor. (C) 2017 Elsevier Ltd. All rights reserved.