Numerical investigation of reaction kinetics of coal volatiles with a detailed chemistry and its simplification

Abstract

Reaction kinetics of coal volatile were numerically investigated based on analyses during reaction mechanism reduction procedure in detail in this paper. Computation on a closed homogeneous reactor model was performed to clarify important chemical species and their reaction pathways with evaluating the capability of prediction of ignition delay time and chemical species concentration under a wide range of equivalence ratios and temperatures. The kinetics of large hydrocarbons such as polycyclic aromatic hydrocarbons (PAH) that comprise a large portion of combustion features for complex hydrocarbon materials was focused on in a coal flame. The data computed here was analyzed through the combined process of the directed relation graph with error propagation and sensitivity analysis (DRGEPSA) and the computational singular perturbation (CSP) that can evaluate the roles of each species and reaction pathway respectively in the chemical system. Results show that hydrocarbons such as aromatics, methyl and ethyl groups play important role in the ignition and flame propagation processes. Finally, the skeletal mechanism including 64 species and 150 reactions was derived from the detailed mechanism that consists of 257 species and 1107 reactions within 30% error in the prediction of the ignition delay time and the mole fractions of major species in the propagating flame.

Keywords

• coal combustion
• volatile matter
• reaction kinetics
• mechanism reduction
• skeletal mechanism