DISTRIBUTION AND BURNING MODES OF CHAR PARTICLES DURING COMBUSTION

The distribution and burning modes of various types of char produced f rom typical Chinese coals in a one dimensional combustibility evaluati on furnace were investigated. The results suggest that the char types formed in the devolatilization zone represent the initial distribution , with no significant combustion taking place. Corpohuminite and texti nite in lignite appear to have thermal behaviour similar to inertinite during pyrolysis. Highly vesiculated cenospheres are rarely developed in lignite and semianthracite, due to their poor thermoplasticity. Th e percentages of different char types generally decrease during combus tion although the different reaction rates, further fragmentation and internal burning may also result in the reverse change in some cases. The burning modes of various char particles are associated with the ch anges in external morphology and internal structure, cenospheres usual ly burn in a constant-diameter mode, while fragments tend to burn in a constant-density mode. Solid char shows two different burning modes: constant density and mixed modes. Solid char burning in the mixed mode is considered to be depleted more quickly than that burning in the co nstant-density mode. Copyright (C) 1996 Elsevier Science Ltd.