RAPID PYROLYSIS AS A METHOD OF CHARACTERIZING COALS FOR COMBUSTION

Two rapid heating coal pyrolysis techniques have been used to study the effect of different heating rates and maximum temperatures on a range of coals. The two techniques are the electrically heated mesh method and Pyroprobe gas chromatography, both of which have controllable heating rates and final temperatures. The first method gives the total yields of the pyrolytic products and the remaining char. In the second technique, chromatograms are obtained using a staged temperature programme to provide information on the molecular weight distribution of the hydrocarbons evolved; this allows a breakdown of the products into groups corresponding to gas and light and heavy tars, and hence provides information on the structure of the coals and their behaviour during pyrolysis.