Influence of fuel-bed temperatures on CO and condensed matter emissions from packed-bed residential coal combustion

Abstract

In this paper, the influence of fire-ignition methods (which determine the progression of the pyrolytic zone) and combustion temperatures on CO and condensed matter (smoke) emissions during fixed-bed coal combustion were investigated in a typical informal brazier/imbaula. Particle and gaseous samples were drawn from the exhaust through a rapid dilution sampling system (the SeTAR dilution system) before being channelled to respective gas and particle analysers. Particle morphologies and chemical composition of the particles were investigated by a VEGA3 SEM unit with EDS. Results showed that the propagation of bed temperatures in fixed-bed residential combustion has an influence on the characteristics of CO and PM10 emissions. Temperature stratification was found to depend on the fire-ignition methods. The top-lit up-draft (TLUD) fire-ignition method produced less emissions compared to bottom-lit up-draft (BLUD) fire-ignition method. Bed temperatures and the propagation front have an impact on aerosol formation and can highlight differences in the morphology of the emitted particles and the modes of formation. Increasing combustion temperature yields a decrease in emissions liquid “tarry” substances and super-aggregates (>10 µm) but also leads to an increase in emissions of sub-micron soot particles. This work is significant in that there is still scarce information available in literature on fuel-bed temperature profiles/stratification for packed-bed residential coal-burning devices.