Experimental investigation on ash deposition of a bituminous coal during oxy-fuel combustion in a bench-scale fluidized bed

• A novel temperature-controlled probe was designed to collect ash deposits.
• The highest deposition propensity appeared under 21% O2/79% CO2 atmosphere.
• PM10 concentration decreased in the order of 30% O2/70% CO2 > 21% O2/79% CO2 > air.

A bituminous coal was burned in a bench-scale fluidized bed to investigate the associated fly ash depositions under both oxy-fuel and air combustion conditions. The results showed that the highest deposition propensity appeared under 21% O2/79% CO2 atmosphere, and only a small difference was observed between 30% O2/70% CO2 and air atmosphere. The chemical compositions and micro-morphologies of ash deposits and fly ash were analyzed by inductively coupled plasma-atomic emission spectrometry and by scanning electron microscopy, while particulate matter with an aerodynamic diameter less than 10 μm (PM10) was measured by electrical low pressure impactor. The results showed that there were no obvious differences in the chemical compositions of fly ash and ash deposits between combustion conditions, except for the slight variations in K, Na and S contents. The concentration of PM10 decreased in the order of 30% O2/70% CO2 > 21% O2/79% CO2 > air.