Distribution of activation energy model applied to the rapid pyrolysis of coal blends

Abstract

A multiple reaction model (MRM) was used to characterize the kinetics of pyrolysis of single coals and binary blends; the MRM represents the kinetics through a continuous distribution of the activation energies of the individual reactions (DAEM). Kinetic parameters were assessed from experiments performed in a drop-tube reactor at high temperatures (1000-1300degreesC) and low residence times (60-320 ms). Results are given for three single coals and two binary blends. Volatile yields are generally greater than the ASTM standard values due to fewer secondary reactions under the experimental conditions. The proposed model satisfactorily reproduces devolatilization curves as a function of activation energy distribution and a parameter that depends on the liptinite, vitrinite and ash content of the coal or blend. A defined "Pyrolysis Yield Index" (PYI) that combines the maceral composition and ash content, appears to correlate well with a parameter of the kinetic model. Blends constituted by petrographically similar coals show no significant deviation from the expected weighted average of the single coals. (C) 2003 Elsevier B.V. All rights reserved.