Particulate matter formation mechanism during pressurized air-and oxy-coal combustion in a 10kWth fluidized bed

Pressurized fluidized bed oxy-fuel combustion is believed to be a promising clean coal technology for power plants to achieve economically efficient CO2 capture. However, studies on the particulate matter (PM) formation mechanism under pressurized conditions were very limited. In this work, a 10 kWth pressurized oxy-fuel fluidized bed combustor (POFBC) was used, and 0.1/0.3/0.5 MPa were conducted for both air- and oxy-coal combustion. The effects of combustion atmosphere and pressure on particle size distribution (PSD) and size segregated composition of PM were explored. The results indicated that the concentration of PM1 generated in oxy-fuel combustion was higher than that in air combustion regardless of pressure, but this difference decreased with the increase of pressure, and the influence of combustion atmosphere on the concentration of PM1-10 was not obvious. In oxy-fuel combustion, the elevated pressure reduced the concentration of PM1 but increased the concentration of PM1-10. Moreover, elevated pressure can decease the yield of most elements in submicron particles. Specifically, it appeared that the effect of pressure on the yields of volatile species (Na, K, and S) in PM1 were not significant, but the yields of refractory species (Fe and Si) in PM1 were obviously smaller at elevated pressures. •More PM1 is generated in oxy-fuel combustion, but this is less significant when pressure increases.•PM1 mass concentration was diminished at elevated pressure, but increasing pressure can promote PM1+ formation•Elevated pressure can decease the yield of most elements in PM1, especially for the refractory species.