Effect of blending ratio on combustion performance in blends of biomass and coals of different ranks

Combustion measurements were conducted to investigate the combustion characteristics of blends of biomass and coals of different ranks. A laboratory-scale slit burner, which more accurately represents the conditions for a practical flame with a high heating rate and jet velocity, was adopted in the present work based on thermal analytical results. The results of a thermogravimetric analysis revealed that the great amount of volatile matter in the biomass and the rapid emission of this volatile matter under low temperature, which contribute to the accelerated ignition at a lower temperature, increased the particle surface temperature and enhanced the reactivity on the surface of a low-rank coal. The combustion performance of a low-rank coal could be improved with a biomass addition, while the biomass addition had no apparent impact on the combustion performance of a high-rank coal. In addition, combustion characteristics such as the mean flame temperature and reaction region were investigated using a laboratory-scale slit burner. Adding 10% biomass to the blends improved the combustion efficiency of a low-rank coal. In the co-combustion of a low-rank coal and biomass, this 10% biomass addition enhanced the ignition and promoted reactivity in the volatile reaction region through a synergetic effect between the low-rank coal and biomass.

► A laboratory-scale burner was used to study combustion characteristics via TGA.
► Combustion index of the blends increased with increasing biomass blending ratio.
► Combustion regions of the blends were evaluated by chemiluminescence intensities.
► A 10% biomass addition improved the combustion performance of the low-rank coal.
► There was no relationship between the ignition temperature and preheating region.