Experimental investigation on the oxy-fuel co-combustion behavior of anthracite coal and spent coffee grounds

The combustion behaviors of anthracite coal/spent coffee grounds under oxy-fuel condition were assessed by a thermal analysis technique. At heating rates of 10–40 K min−1, the ignition temperatures and burnout temperatures of all anthracite coal/spent coffee grounds blends decreased with increasing the blending ratios of biomass or oxygen contents in O2/CO2 atmospheres. The ignition temperatures of all samples at the similar oxygen content in oxy-fuel with that of air were higher than that in air atmosphere. In 30 % O2/70 % CO2 atmosphere, the average ignition and comprehensive performance indices of anthracite coal/spent coffee grounds at 40 K min−1 were about 4 times and 18 times more than that at 10 K min−1, respectively. At heating rate of 20 K min−1, the comprehensive performance indices of all samples in 30 % O2/70 % CO2 were very close to those in air. In air and O2/CO2 (21–40 % oxygen contents) atmospheres, the activation energies of release and combustion for volatile matters in the blends ranged from 33.66 to 147.32 kJ mol−1. Activation energies of char combustion in the blends ranged from 21.06 to 109.49 kJ mol−1. There were more significant synergistic effects between anthracite coal and spent coffee grounds during co-combustion in air and oxy-fuel atmospheres at 40 K min−1.