Laboratory study of the self-heating tendency of coals and their pyrolysis chars

Laboratory experiments were performed to examine the self-heating tendencies of bituminous coals and lignite as compared to chars prepared by their pyrolysis. The effects of oxygen, moisture, initial temperature, volatile matter content, and rank of coal were studied. The primary role of moisture was to supply an initial heat of adsorption which raised the temperature to a point where the oxidation reactions were self-sustaining. The pyrolysis chars were found to have no greater tendency toward self-heating than their parent coals, and in particular, the lignite char was found to be much more stable than the lignite from which it was prepared.