Coals contain considerable amounts of oxygen in their structures ranging from 30% in brown coal to about 1.5% in anthracites. The distribution of coal oxygen in various functionalities changes drastically with increasing rank. The hetero-atom functionalities in coal and coal products are of importance in the processing of coal. The process of coal conversion relevant to the steam and gas turbine applications are pyrolysis, oxidation and combustion processes. Initial stages of pyrolysis and oxidation (combustion) are the thermal decomposition of the solid coal matrix to free radicals. Oxygen, sulfur, nitrogen and mineral containing free radicals play an important role during combustion thermodynamically. The differences between the coal functionalities in the solid coal matrix contribute to oxidation reactions of first and second order. The first and second order reactions affect the corrosion and deposition rates of the machine components differently.

In this paper functionality differences of various coals with respect to their oxidation characteristics will be discussed.

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