Kinetic modeling of low-temperature oxidation of coal

A kinetic model has been developed for determining the rate of oxygen consumption and production of carbon oxides during the oxidation of coal at low temperatures (i.e.<100degreesC), based on current understanding of the mechanism of coal oxidation. The chemical reactions considered in the model include two parallel sequences consuming oxygen and two thermal decomposition pathways producing carbon oxides. The resulting rate expressions reflect the contributions of various reactions consuming oxygen and producing carbon oxides and predict the effects of temperature, oxidation time and [O-2] in-the gas phase. The general form of the rate expressions confirms that chemisorption is relatively fast, only playing an important role at the early stage of coal oxidation. With the formation of stable and unreactive oxygenated complexes in a coal's structure, the oxidation of coal is dominated by thermal decomposition of oxygenated complexes. (C) 2002 by The Combustion Institute.