Co-combustion behaviors of municipal solid waste and low-rank coal semi-coke in air or oxygen/carbon dioxide atmospheres

Co-combustion characteristics and interactions of municipal solid waste (MSW) and low-rank coal semi-coke (LCSC) in O2/CO2 or air atmosphere are investigated by the thermogravimetric method, including analyses of thermodynamic, kinetic parameters and reaction mechanism function. Results indicated that addition of MSW and higher oxygen concentration improve the co-combustion performance of blends. There are three distinct peaks for co-combustion of blends in air atmosphere, while only two peaks in 30O2/70CO2 atmosphere. It indicates that the presence of CO2 in oxy-fuel atmosphere is conducive to semi-char burnout. Interactions of MSW and LCSC mainly occur between 260 °C and 650 °C, and the synergetic interaction is very obvious around the second peak region of combustion process. The average activation energies Ea show an upward trend with the increase in oxygen concentration, and the minimum value of Ea is obtained when the blend ratio of MSW is 50% which might be an optimal option for co-combustion of blends. Activation energy, enthalpy changes, Gibbs function and entropy changes for 50MSW50LCSC in 30O2/70CO2 atmosphere are 140.86 kJ mol−1, 138.33 kJ mol−1, 161.94 kJ mol−1 and − 41.44 J mol−1 K−1, respectively. In O2/CO2 atmospheres, F6 and F1 functions are more suitable to describe the starting and subsequent process of entail reaction. The results can provide a theoretical and practical guidance for the harmless disposal and resource utilization of MSW and LCSC.