Comparison of Particle Size Evolution during Pulverized Coal Combustion in O₂/CO₂ and O₂/N₂ Atmospheres

Abstract

The present work was aimed at investigating particle size evolution during pulverized coal combustion in an O2/CO2 atmosphere in comparison to that in an O2/N2 atmosphere. Two narrow size fractions of a bituminous coal were devolatilized in N2 and CO2 and burned in O2/N2 and O2/CO2 atmospheres in a high-temperature drop-tube furnace. The resulting chars and residual ashes as well as the parent coals were characterized with scanning-electron-microscopy-based image analysis to quantify particle size distributions, which were systematically compared. The results show that devolatilization in CO2 produces finer char particles than that in N2. It may have a consequence on particle size evolution and ash particle formation during char conversion. Combustion in an O2/CO2 atmosphere generally generates more fine ash particles than burning in an O2/N2 atmosphere at the same oxygen level. Increasing the O2 concentration decreases the amount of the fine ash particles in both atmospheres. The results also show that changing gas atmospheres has a greater influence on the evolution of the particle size distribution during the combustion of the larger coal size fraction.

A Comprehensive Review of Ash Issues in Oxyfuel Combustion of Coal and Biomass: Mineral Matter Transformation, Ash Formation, and Deposition

“…The decrease in char temperature in O 2 /CO 2 combustion reduced not only ash vaporization but also particle fragmentation, accounting for the reduction of both types of particles. Similar results have also been observed by other studies with different fuels. ,,− …”

Effect of coal particle size on distribution and thermal behavior of pyrite during pyrolysis

“…Chen [25] also found that excluded pyrite presented to be more in coal particles of 50-75 lm than in ones of 75-90 lm.…”

Experimental study of ash formation under O2/CO2 combustion

“…According to the literature, increasing the O 2 concentration decreased the content of the fine ash particles under both Oxy and Air conditions. The effect of oxygen concentration on the concentration of major and trace elements in ash was studied by Oboirien et al .…”

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