Effect of minerals and binders on particulate matter emission from biomass pellets combustion

In this study, the effect of minerals and binders on the emission characteristics of particulate matter (PM) from biomass pellets combustion is investigated using a fixed bed combustor combined with a Dekati low pressure impactor (DLPI). It was found that densification reduced PM emission as the pellets hindered the release of alkali metals in comparison to the bulk biomass. The generation of PM1 was mainly due to the homogeneous condensation and heterogeneous coagulation of alkali chlorides and sulfates. Alkaline earth metals and Si played a dominant role in the formation of PM10. Diatomite in mineral additives could effectively reduce the emission of PM1, while the binders showed no inhibitory effect on the PM emission. Composite additives prepared with carboxymethyl cellulose (CMC) and diatomite showed a positive synergistic effect in reducing the emissions of PM1 with the optimum CMC/diatomite ratio of 1:4. The results showed that composite additives of minerals and binders are excellent choices for the industrial production of biomass pellets from the view of increasing pellet quality and reducing PM emission.