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[摘要]：An empirical model was established based on measurements of devolatilization characteristics of coal particles (18.7%, 32.7% and 43.0% VM; 0.14, 0.20, and 0.30 mm, respectively) heated at a heating rate of 10(3)-10(4) K/s by it well-controlled CO2 laser with double shutters and a high-accuracy two-color pyrometer. The conclusions obtained are as follows: (1) particle temperature (T-p), volatile yield (V), heating rate (HR) and in situ energy density flux (F-ed) during devolatilization can be well-predicted by solving an energy conservation equation and a devolatilization rate equation with two competing reaction rates; (2) the pre-exponential factor and activation energy of the two reactions are A(1) = (1.7249-1.8936) x 10(2) s(-1), E-1 = (2.6248-3.5447) x 10(4) J/mol, A(2) = 2,6 x 10(6) s(-1). and E-2 = 1.6740 x 10(5) J/mol, respectively, which are obtained by fitting our experiment data; (3) the final volatile yield (V-r) is dependent oil the laser intensity (Q(L)), the particle size (D-n), and the proximate volatile matter content (V-0), and it can be well-predicted by a regressive equation of V-r with Q(L), D-n, and V-0; (4) a modified Merrick's heat capacity correlation can be used to predict the temperature history of coal particles heated at a rate of 10(3)-10(4) K/s with excellent agreement; (5) the heats of devolatilization, which are given as -0.5244, -0.6629, and -0.7348 MJ/kg for the three coals used in this study, are suitable values for predictions (6) the sum of the heat of devolatilization (Delta H-d) and energy loss per unit Mass volatile yield (Delta H-v1) which can be represented as Delta H-d + Delta H-v1 = -0.01046 MJ/kg, is a suitable value for predicting particle temperatures and volatile yields for all three coals, (7) the measured histories of weight loss are imperative for predicting the temperature and the devolatilization kinetics of coal particles heated at a high heating rated and (8) the swelling-shrinking ratios, absorptivity, emissivity, thermal capacity, and beat of devolatilization of coal particles at high heating rates should be measured for better predictions. |
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