Thermogravimetric analysis of solid biomass fuels and corresponding emission of fine particles

Highlights: • The size of fine combustion particles is crucial for the human health. • The total absence of oxygen doubles the mass of emitted fine particles. • The most combustion particles were identified in the size range 100–130 nm. • Up to 3% of the biomass sample mass converts to particles less than 500 nm. A significant problem of biofuel combustion is the emerging emissions of particulate matter. This paper deals with the experimental determination of the particulate matter emission characteristics of 27 different types of conventional and less traditional solid biofuels. Thermogravimetric analysis is used for the controlled heating of all tested samples from 25 °C to 650 °C with a 10 °C·min⁻¹ heating rate. The analysis is performed for two atmosphere compositions, namely 21 % O₂ and 0 % O₂. The resulting flue gas is fed to an instrument allowing fine particles' detection ranging from 18 to 545 nm in diameter. The relation between the temperature of fuel samples and the number and mass of the generated particles is investigated. The percentage of the original sample mass converted to particles is determined. Subsequently, particulate matter emission is expressed as a relation to sample ash content and sample volatile matter content. The specific particulate matter emissions range of all tested samples are expressed per megajoule of higher heating value (HHV): 1.02–2.67·10¹⁵ ·MJ⁻¹ and 694–2844 mg MJ⁻¹ in the atmosphere with 21 % of O₂ and 1.11–3.29·10¹⁵ ·MJ⁻¹ and 898–6823 mg MJ⁻¹ in the atmosphere without oxygen (pyrolysis).