Pyrolysis characteristics of cattle manures using a discrete distributed activation energy model

•A discrete DAEM for the pyrolysis process of cattle manures is established.•The pyrolysis process can be accurately characterized by 27 dominating reactions.•Complex interaction phenomenon among the constituents of cattle manures is revealed.•Kinetic parameters for each constituent during the pyrolysis process are obtained.•Two quantitative relationships are proposed with increasing the heating rate. The pyrolysis characteristics of cattle manures were conducted using a discrete distributed activation energy model (DAEM) coupled with the thermogravimetric analysis. The results showed that the pyrolysis process can be accurately characterized by 27 dominating reactions, and the dominating reactions form four groups to represent respectively the decomposition processes of the different constituents of cattle manures. Moreover, the devolatilization kinetics under the heating rate changing from 0.1Kmin−1 to 10,000Kmin−1 were predicted with the discrete DAEM. Prediction results demonstrated that with increasing the heating rate, the main decomposition regions of individual constituent become more and more concentration and their interactions are more and more complex. Particularly, it was interesting to discover that the peak decomposition rate is perfectly proportional to the heating rate, and the peak, starting and ending decomposition temperatures satisfy a relationship of quadratic function with the common logarithm of the heating rate.