Analysis of the errors associated with typical pulverized coal char combustion modeling assumptions for oxy-fuel combustion

被引:56
作者
Hecht, Ethan S. [1 ,2 ]
Shaddix, Christopher R. [2 ]
Lighty, JoAnn S. [1 ]
机构
[1] Univ Utah, Dept Chem Engn, Salt Lake City, UT 84112 USA
[2] Sandia Natl Labs, Combust Res Facil, Livermore, CA 94550 USA
关键词
Coal combustion; Gasification; Oxy-fuel; ENTRAINED FLOW REACTOR; SUB-BITUMINOUS COAL; IRREGULAR PARTICLES; STEAM GASIFICATION; REACTION-KINETICS; CARBON PARTICLE; SHAPE FACTORS; CO2; REACTIVITY; OXIDATION;
D O I
10.1016/j.combustflame.2013.02.015
中图分类号
O414.1 [热力学];
学科分类号
摘要
In CFD models of pulverized coal combustion, which often have complex, turbulent flows with millions of coal particles reacting, the char combustion sub-model needs to be computationally efficient. There are several common assumptions that are made in char combustion models that allow for a compact, computationally efficient model. In this work, oft used single- and double-film simplified models are described, and the temperature and carbon combustion rates predicted from these models are compared against a more accurate continuous-film model. Both the single- and double-film models include a description of the heterogeneous reactions of carbon with O-2, CO2, and H2O, along with a Thiele based description of reactant penetration. As compared to the continuous-film model, the double-film model predicts higher temperatures and carbon consumption rates, while the single-film model gives more accurate results. A single-film model is therefore preferred to a double-film model for a simplified, yet fairly accurate description of char combustion. For particles from 65 to 135 mu m, in O-2 concentrations ranging from 12 to 60 vol.%, with either CO2 or N-2 as a diluent, particle temperatures from the single-film model are expected to be accurate within 270 K, and carbon consumption rate predictions should be within 16%, with greater accuracies for a CO2 diluent and at lower bulk oxygen concentrations. A single-film model that accounts for reactant penetration and both oxidation and gasification reactions is suggested as a computationally efficient sub-model for coal char combustion that is reasonably accurate over a wide range of gas environments. (C) 2013 The Combustion Institute. Published by Elsevier Inc. All rights reserved.
引用
收藏
页码:1499 / 1509
页数:11
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