Estimating the Combustibility of Various Coals by TG-DTA

Abstract

To estimate the combustibility of 12 different coals involving anthracite, bituminous, and lignite, experiments of the coal combustion were carried out by using thermogravimetry (TG) and differential thermal analysis (DTA). High-reactivity combustibles region and low-reactivity combustibles region were observed during coal char combustion process. Also, two reaction rate constants (k 1 and k 2 ) for these two combustibles were determined. The value of the reaction rate constant of the low-reactivity combustibles (k 2 ) is much smaller than that of the high-reactivity combustibles (k 1 ) in each coal and also k 2 shows lower temperature dependence. These are reasons why 5-10% unburned carbon remains in the ash discharged from moat of the coal-fired power plants. The ignition temperature increases with decreasing volatile matter content of coal. Three ranks of coals as anthracite, bituminous, and lignite show the different ignition ways