EFFECTS OF INERTINITE CONTENT IN COAL ON CHAR STRUCTURE AND COMBUSTION

This paper reports data on the combustion characteristics of seven hig h-volatile bituminous coals (VRr approximate to 0.65%) with increasing inertinite contents (10-68%). Structural parameters of pyrolysis char s are compared with the maceral compositions and distributions of mace ral reflectances in the parent coals and with their combustion efficie ncies. The microscopic study of pyrolysis chars obtained at 1000 degre es C reveals that inertinite-rich coal chars are much denser than thos e of inertinite-lean coals. The reactivity of these chars at low tempe ratures (500 degrees C) decreases with the increase of inertinite cont ent of the parent coals, this being attributed to the highly cross-lin ked structure of the inertinites. However, at higher temperatures (110 0 degrees C) the burnout levels of the inertinite-richest coals were d early higher than those of medium-to-low inertinite coals. This cannot be explained from the assumption of a diffusional control of the comb ustion process. Thus, a chemical control of the process is suggested w here the mechanism governing the overall reaction rate at 1100 degrees C would be the active site concentration in time molecular structure of pyrolysis chars, which, in turn, would depend on the aromaticity an d degree of molecular ordering in the parent maceral structure.