Thermogravimetric analysis of the co-combustion of coal and sewage sludge

Combustion of three different sewage sludge samples (B, F and S), one bituminous coal and sludge–coal blends were studied by TG dynamic runs carried out at 10 °C/min in the temperature range 25–800 °C. The sludge is mainly formed by two organic fractions with different reactivity; the less reactive fraction decomposes and burns at temperatures closer to those of coal, although, in general, slightly lower. For coal–sludge blends, no interactions between the components were detected. rhenius kinetic parameters were calculated from the experimental results, considering the process as a series of consecutive first order reactions. Coal reactivity is scarcely modified as a consequence of a low addition of sludge (10 wt% blends). The 50 wt% blends show two different regions of reactivity. In the lower temperature region (about T<350 °C), the blend reactivity is similar to that of sludge, while in the higher temperature region (T>350 °C), it is similar to that of coal.