Thermal and kinetic characteristics of combustion of coal sludge

The combustion characteristics of coal sludge were investigated with thermogravimetric analysis at different heating rates (10, 20, 30, 40 A degrees C min(-1)). The influences of heating rates on the combustion behavior of coal sludge were studied. The research found that the value of general combustion parameters for Taiyuan coal sludge (TY) is the lowest, for Shuozhou coal sludge (SZ) is the highest, and for Jincheng coal sludge (JC) is in middle at any heating rate. The experimental results indicated that a higher heating rate is useful for the combustion performance of coal sludge in this study. Kinetic parameters of the coal sludge samples were evaluated with the Ozawa-Flynn-Wall (OFW) and distributed activation energy model (DAEM) method. The activation energy values obtained from the DAEM method are a little lower than the ones obtained from the OFW method for every kind of coal sludge. The activation energy values of JC were 119.62 and 113.63 kJ mol(-1) obtained by OFW and DAEM methods, respectively, and were lower than corresponding values of TY and SZ. Higher amounts of alkaline metal (Na and K), alkaline earth metals (Ca and Mg), Fe and Ti in JC may play a major role in lowering the activation energy values. The present results have important significance for understanding the characteristics of combustion of coal sludge.