STUDYING THE MECHANISMS OF IGNITION OF COAL PARTICLES BY TG-DTA

The mechanisms of ignition of coal of different quality, such as anthr acite, bituminous coal and lignite, were studied by thermogravimetry ( TG) and differential thermal analysis (DTA). Experiments on coal ignit ion were carried out at a low heating rate (10 K min(-1)) with particl e sizes ranging from 37 to 4000 mu m. It is concluded from this experi mental work that (1) ignition measurement by TG-DTA is an excellent me thod for accurate determination of the ignition temperature of coal pa rticles; (2) with increasing coal quality from lignite through bitumin ous coal to anthracite, the type of ignition changes from homogeneous ignition through hetero-homogeneous ignition to heterogeneous ignition , and the ignition temperatures also increase; (3) with increasing coa l particle size, the type of ignition of Kaipin bituminous coal change s from hetero-homogeneous to homogeneous ignition, and ignition of the char separates from that of the volatile matter and shifts to a highe r temperature, whereas both types of ignition of Loy Yang lignite coal and Hongay anthracite coal are not effected by particle size.