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.

Primary soot particle distributions in a combustion field of 4 kW pulverized coal jet burner measured by time resolved laser induced incandescence (TiRe-LII)

“…To avoid these problems, the numerical simulation technology have been developed to predict the combustion characteristics in coal-fired boilers (e.g., Kurose et al, 2004, Hashimoto et al, 2007, Aydin and Durak, 2012. Some new models or methods for coal combustion field, e.g., the new devolatilization model (Hashimoto et al, 2012a, 2012b, Hashimoto et al, 2014, the new char combustion model (Umetsu et al, 2014), the skeletal mechanism for the volatile matter combustion (Ahn et al, 2016), the transported PDF model (Zhao et al, 2014), the velocity-scalar joint filtered density function model (Wen et al, 2015), the new heterogeneous combustion model (Vascellari et al, 2014), the large eddy simulation of coal combustion field (Rabacal et al, 2015, Olenik et al, 2015, have been developed recently. To model the various phenomena in the combustion field for developing the accurate simulation technology, the understandings of coal combustion phenomena are necessary.…”

A Review on Detailed Kinetic Modeling and Computational Fluid Dynamics of Thermochemical Processes of Solid Fuels

“…Although their calculation domain was 60 × 60 × 428 cm 3 large, it took only 66 h on 1024 cores for one case. Another alternative option for the coal combustion with flamelet model is direct closure with the reduced mechanism from the detailed chemistry, such as that described by Ahn et al , …”

“…Although their calculation domain was 60 × 60 × 428 cm 3 large, it took only 66 h on 1024 cores for one case. Another alternative option for the coal combustion with flamelet model is direct closure with the reduced mechanism from the detailed chemistry, such as that described by Ahn et al 140,141 In the original flamelet model, 135 a turbulent flame is assembled by a set of thin, laminar, and one-dimensional counterflow flames. The model describes the chemistry by two…”

Effects of ambient temperature on the combustion processes of single pulverized coal particle

“…Since volatile matter combustion is the first step in pulverized coal combustion and affects its subsequent phenomena. The investigation of the reaction kinetics of coal and optical measurement was conducted in previous studies (Ahn et al, 2016;Hashimoto et al, 2016;Lee et al, 2015). Ahn et al (Ahn et al, 2016) investigated reaction kinetics of the volatile matter from coal particle based on analyses with reduced chemical mechanism.…”

“…The investigation of the reaction kinetics of coal and optical measurement was conducted in previous studies (Ahn et al, 2016;Hashimoto et al, 2016;Lee et al, 2015). Ahn et al (Ahn et al, 2016) investigated reaction kinetics of the volatile matter from coal particle based on analyses with reduced chemical mechanism. They showed that hydrocarbons such as aromatics, methyl and ethyl groups play important role in the ignition and flame propagation processes.…”