Catalytic Effect of Iron on the Carbon Gasification Reaction and Its Rate Constants in Iron-Carbon Composite Pellet
Fanming MENG, Yoshiaki IGUCHI, Shoji HAYASHI
The rate of the gasification reaction of coal char- and graphite-electrolytic iron composite pellets were gravimetrically measured in CO-CO2 mixtures from 850 to 1000°C. The gasification curves of high accuracy were obtained by a combination of weight loss measurements and carbon analysis by combustion method for reacted pellets. By applying the integrated first-order reaction rate equation to the curves, the apparent gasification rate, k', was estimated. Based on the relation between effectiveness factor and Thiele modulus for the Langmuir-Hinshelwood type catalytic reaction in a spherical catalyst, the straight line relation between (1/k')2 versus R2 was extrapolated to zero R2 to obtain the intrinsic gasification rate. By comparing the intrinsic gasification rates for carbon-electrolytic iron, the catalytic effect of electrolytic iron on the gasification is to increase the rates by the factors of 1.54.9 and 14.3 times respectively. The gasification rate parameters of the rate equation, k=(k0PCO2)/(1+k1PCO+k2PCO2), were evaluated from the two series experiments in the following conditions. Series A: PCO+PCO2=101325 Pa, PCO2=(0.10.2)×101325 Pa. Series B: PCO/PCO2 =4, PCO +PCO2+PN2 =101325 Pa, PCO2=(0.10.2)×101325 Pa. The catalytic effect of the electrolytic iron was in good agreement with that of the iron reduced from a hematite ore, and the results obtained in this study are applicable to the reduction of the iron ore-coal char composite pellet.
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