Characterization of Submicrometer Particles From Biomass-Coal Co-Firing in a Drop-Tube Furnace

Pulverized coal combustion is widely used in coal-fired power plants and other industry boilers.  To reduce its CO₂ emissions, a promising method is to co-fire coal with carbon-neutral fuels, such as biomass.  Few studies have reported characterization of particulate matter emissions from biomass-coal co-firing.  We investigate both physical and chemical properties of particles from a co-firing system: biomass-coal blends (saw dust and Powder River Basin coal) were combusted in a drop-tube furnace.  Size distributions of particles with diameter smaller than 500 nm were measured by a Scanning Mobility Particle Sizer.  The effect of biomass/coal ratio was examined.  The formation mechanisms of these particles were proposed based on the experimental data.  Carbonaceous particle emission is an anther important concern due to its effects on human health and climate.  Organic composition of co-firing aerosols were determined using a high resolution aerosol mass spectrometer (HR-Tof-AMS) and a thermal desorption aerosol gas chromatograph (TAG).  Many organic species, such as polycyclic aromatic hydrocarbons (PAHs), were found and their emission factors were determined.  Detailed formation mechanism of organic aerosols and their relations with formation of black carbon aerosols are proposed and will be discussed.