Combustion Behavior of Coals in Rotary Kiln and Their Interaction on Co-combustion

In order to clearly reveal coal combustion behaviors and quantitatively evaluate using coal in a rotary kiln, combustion behaviors of four coals (C-13, C-23, C-32, and C-6 coals) and their blended coals were investigated. Meanwhile, their interactions and combustion kinetics were analyzed. The results showed that C-13 and C-23 coals having combustion characteristics of high heating value, suitable ignition temperature, burnout time and kinetic parameters (E-alpha and n) conform to the requirement of a rotary kiln. The partial substitution of C-23 coal for C-13 coal in the production is feasible, while the replacement of C-32 and C-6 coals for C-13 coal will affect coal combustion and result in production fluctuation because C-32 and C-6 coals have an effect on C-13 coal combustion. The blended coals have the similar characteristics of proximate analysis and heating value contrasting to C-13 coal, but they show different combustion behaviors that cannot be calculated in an additive manner. Their combustion behaviors show multiple combustion peaks and complex combustion kinetics if they are composed of different combustion behavior coals.