Laminar Burning Velocities of Atmospheric Coal Air Mixtures

Abstract

The mechanism for laminar dust flame propagation can only be elucidated from a comprehensive mathematical model which incorporates conduction and radiation, as well as the chemical kinetics of particle devolatilization and gas phase and char reaction. The mathematical model for a flat, laminar, premixed coal-air flame is applied to the atmospheric coal-air mixtures studied by Smoot and co-workers, and comparisons are made with their measurements and predictions. Here the principal parameter for comparison is the laminar burning velocity. The studies of Smoot and co-workers are first reviewed and compared with those predicted by the present model. The effects of inlet temperature and devolatilization rate constants on the burning velocities are studied with the present model, and compared with their measurements and predictions. Their measured burning velocities are approximately predicted with the present model at relatively high coal concentrations, with a somewhat increased inlet temperature. From the comparisons, their model might over-estimate particle temperature and rates of devolatilization. This would enable coal-air mixtures to be burned without any form of preheat and would tend to increase their computed values of burning velocity.

Modeling heat transfer in gas-particle mixtures: Calculation of the macro-scale heat exchange in Eulerian–Lagrangian approaches using spatial averaging

“…Our global strategy follows the ones proposed in e.g., Cannevière (2003) and Neophytou and Mastorakos (2009) for liquid fuel droplets or in Cloney et al (2018) and Park and Park (2016) for coal particles. The idea is to use detailed numer-ical simulations to analyze the flame structure and calculate the laminar burning velocity that is then used in a second step to determine the turbulent flame velocity (see for instance Proust, 2017;Silvestrini et al, 2008 ).…”