Bioslurry for Stationary Applications: Particulate Matter Emission during Combustion under Air and Oxyfuel Conditions

As a new type of fuel, bioslurry is prepared from mixing bio-oil and biochar produced from biomass fast pyrolysis and is suitable for stationary combustion applications. This study reports the emission of particulate matter (PM) from bioslurry combustion in a lab-scaled drop-tube furnace at 1400 degrees C under various atmospheres, including air, 20% O-2/80% CO2, and 30% O-2/70% CO2. Similar to biomass combustion, the particle size distribution (PSD) of PM with an aerodynamic diameter of less than 10 mu m (i.e., PM10) during bioslurry combustion also follows a bimodal distribution. Increasing the char loading level in bioslurry leads to an increase in the emission of PM10, especially PM1-10, as a result of the high contents of inorganic species in biochar. Emissions of PM1 and PM1-10 during bioslurry combustion under 20% O-2/80% CO2 conditions are lower than those under air conditions, apparently attributed to the lower char combustion temperature. However, under 30% O-2/70% CO2 conditions, emission of PM10 during bioslurry combustion is higher than that under air conditions. Such an increase in PM10 is mainly contributed by increasing PM1, which appears to be a result of enhanced sulfation of alkali species at an increased oxygen concentration. The PM10 emission performance during the combustion of bioslurry was also benchmarked against those during the combustion of solid fuels, such as coal, biomass, or biochar, under similar conditions. The results show that the combustion of bioslurry emits considerably lower PM10 than that of coal, biomass, or biochar on the basis of the same energy input, which is normally the case when bioslurry is used to replace solid fuels. The results suggest that, from the PM emission point of view, bioslurry is a competitive candidate for substituting other solid fuels in stationary combustion applications.