Thermal analysis on combustion characteristics of predried dyeing sludge

Abstract

The combustion characteristics of predried dyeing sludge (PDS) is studied on a simultaneous thermal analyzer, and compared with that of Xilinhot lignite (XL) and an industrial biomass char (BC). A new method is proposed to determine the ignition and burnout temperatures based on DSC-dDSC curves. The combustion process of PDS shows earlier weight loss than that of XL and BC, and can be divided into four stages. With the increase of oxygen concentration, the TG/DTG curves of PDS move to lower temperature zone, and combustion indices increase. With the increase of heating rate, the combustion indices also increase while the weight loss curves move oppositely. Increasing oxygen concentration and heating rate are beneficial to combustion performance. Kinetic analysis on PDS combustion is performed using Coats-Redfern method. As oxygen concentration increasing, kinetics parameters of the devolatilization and char combustion increase. With the increase of heating rate, the apparent activation energy of the devolatilization changes slightly, while the pre-exponential factor increases. The kinetics parameters of char combustion both decrease with the increasing heating rate. Oxygen concentration and heating rate have great influence on the kinetics of char combustion. Compensation effect exists between kinetics parameters and the corresponding mechanism is discussed.