A Review on Particle Emissions from Small Scale Biomass Combustion

Abstract

Combustion of biomass fuels in small scale heating appliances is an important source of particle emissions. Majority of the particles is less than 1 µm (micrometer) and emitted directly to the ambient air from the combustion devices . There is a growing concern worldwide about particle emissions from biomass combustion. This review paper has been conducted based on the research articles published in the journals, conference proceedings, and technical reports from the research institutions between the periods from 2000 to 2010. Types of particles, formation mechanisms, their characteristics and available measurement techniques are discussed at the beginning . Particle emission characteristics on small scale biomass combustion from the literature have been discussed in order to provide in depth knowledge as assistance to readers interested in this research field. Finally, the literature data has been summarized into three categories to show how combustion appliances and fuel affect the mass concentrations, number concentrations, corresponding size distributions and chemical compositions. Mass concentrations of particles in the flue gas from small scale combustion appliances reported in the literature to be in the range of 7-67 mg/Nm 3 , while particle number concentrations in the range of 0.8 x 10 7 - 5.5 x 10 9 particles/cm 3 . The dominating chemical compositions of the particle emissions in the fine mode were potassium fraction followed by sulphur, chlorine and sodium and consequently dominating chemical compounds were K 2 SO 4 and KCl. From the literature it is clear that particle emissions from biomass combustion are closely related not only to the fuel properties but also to the combustion conditions and combustion appliances.