Behavior Evaluation of Ash Deposition and Consequent Fine Particle Emissions produced from Combustion of Low-rank Coal Impregnated with Molasses in Drop Tube Furnace

The co-combustion of low-rank coal with biomass is regarded as a prospective technology for reducing CO2 emissions to mitigate the issues related to the excess global warming. However, the ash deposition and fine particle formations problems were severe with the addition of biomass. Therefore, it is vital to investigate ash deposition and fine particle formation to ensure the normal operation of equipment in thermal power plant and improve thermal conversion efficiency as well as protect air environment. In this study, two types of raw coals (Berau coal, Bayan coal) and three types of hybrid coals (Berau coal impregnated with 10 wt%, 20 wt% molasses; and Bayan coal impregnated with 3 wt% molasses) are used as the samples to conduct DTF experiment. The propensity associated with ash deposition and fine particle formation are studied at excess air under combustion temperature of 1300℃. The ash deposits generated at the probe top surface maintained at 800℃, and the fine particles carried by the flue gas were collected by the filter paper. A range of analytical techniques including SEM-EDX and XRD were used to analyze the morphology and elemental distribution of ash deposits and fine particles for clarifying the ash deposits behavior. It is found that the deposition tendency of 3% HCK is lower than other fuels. As far as the fine particle formation is concerned, the contents of Si and Al in coarse particles were apparently higher than those in fine particle. S and K is higher in fine particles.