Particulate Matter Emissions and Size Distribution at a Wood Log Stove Dependent on Measurement Position and Application of an Electrostatic Precipitator

Particulate matter emissions for assessment of small-scale biomass combustion systems are mainly characterized gravimetrically. An in-depth characterization of particle number and particle size distribution under various practical operating conditions can contribute to describe the changes that occur as the particles travel through the chimney into the environment or the influence of emission reduction measures such as an electrostatic precipitator more precisely and help to evaluate toxicity effects. The results described here, obtained from measurements taken after a wood log stove with different operating conditions and measurement positions, show particle number decreases significantly 25-90 % along the flue gas pipe up to the chimney outlet dependent on chimney length and combustion conditions. The number of ultrafine particles below 100 nm can be one order of magnitude higher directly after the wood log stove, than at the chimney outlet. Accordingly, the particle size distribution at applied precipitators is dependent on the position in the flue gas section (either close to the wood log stove or at the roof). Nevertheless, precipitators can reduce particle mass and number. The tested precipitator reduced particle mass by 50-60 % and particle number 30-65 % about 6 m after the wood log stove.