Co-combustion behavior, kinetic and ash melting characteristics analysis of clean coal and biomass pellet

In this study, the co-combustion characteristics and ash fusion temperatures of clean coal, biomass pellet and their blends were investigated by thermal analyzer and ash-melting point analyzer, respectively. Kinetic parameters were calculated by using the multistage reaction random pore model, which could be very consistent with the combustion law of the samples. The results show that the combustion characteristics of biomass pellet are better than those of clean coal, mainly influenced by the chemical structure. After mixing the two fuels, the flammability and comprehensive combustion performance were gradually improved, and there was an obvious synergistic effect. The best effect was when the biomass pellet mixing ratio was 60%. The increase of heating rate could promote synergy. The various activation energies of the solid carbon combustion stage decreased with the increase of biomass pellet ratio, and the change rule was similar to the synergistic effect. By detecting the shrinkage rate of ash and analyzing the phase composition and transformation, it is determined that the biomass blending ratio of 40–60% was most conducive to efficient utilization of the two fuels.