Abstract

MUNERA, Jennifer Laverde-; ALVARADO-TORRES, Pedro Nel  and  MACHADO, Wilson Ruiz-. Effect of oxygen and methane on the oxidation kinetics of coal char. Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2017, vol.41, n.159, pp.221-229. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.452.

In this work we evaluated the effect of adding methane during the oxidation process of a coal char with low oxygen concentration. We analyzed the effect from a kinetic point of view and we determined the activation energy (Ea) and the pre-exponential factor (A) with different oxygen concentrations and oxygen and methane mixtures. We used a coal char from a highly volatile bituminous coal with particle size of 75 to 150 μm; the kinetic parameters were determined by thermogravimetric method (TGA) with the high-velocity model; oxygen concentration variations were studied with 5, 8 and 21% of oxygen, as well as the effect of adding methane (5,10 and 14%) when oxidation occurred with 5% of oxygen. The results showed that the Ea decreased when oxygen concentration increased, and that adding 5% of methane to the total mixture enhanced the effect. Instead, when we increased the methane percentage, the Ea increased due to the rapid reaction of oxygen and methane in the homogeneous phase as compared with the heterogenous reaction of oxygen and coal char. With 5% oxygen the Ea value was 122.9 kJ/mol and with 21%, it was 90.69 kJ/mol; when methane was added at 5%, the Ea value was 110.7 kJ/mol, and it increased to 170.8 kJ/mol when there was 14% of methane in the mixture. © 2017. Acad. Colomb. Cienc. Ex. Fis. Nat.

Keywords : Kinetic parameters; Pulverized coal char; Methane content; Oxygen content.

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