P-Based Additive for Reducing Fine Particulate Matter Emissions during Agricultural Biomass Combustion

To understand the influence of P-containing compounds on particulate matter (PM) emissions from the combustion of agricultural residues, the combustion of cornstalk was performed with the addition of a phosphorus-based additive, namely, ammonium dihydrogen phosphate (NH4H2PO4), in a fixed-bed combustion system. Simultaneously the ash samples, including PM collected by a Dekati low-pressure impactor (DLPI) and residual ash, were analyzed with variant analytical techniques. It was found that NH4H2PO4 addition significantly reduced PM0.1 and PM0.1–1 yields but increased PM1–10 yields. The maximum PM0.1 and PM1 reduction efficiency can reach up to 50% at an optimal P/K molar ratio equal to 1. Meanwhile, the addition of NH4H2PO4 to cornstalk changed the chemical composition of PM1 from being dominated by KCl and KOH/K2CO3 with a small amount of K2SO4 to a system dominated by KPO3 and KCl with a small amount of K2SO4. Simultaneously, the possible PM1 reduction mechanism was proposed. In addition, the residual a...