Influence of stoichiometry on the release of atomic sodium from a burning black liquor droplet in a flat flame with and without boron

The influence of boron on the temporal release of atomic sodium during a burning black liquor droplet has been assessed using planar laser-induced fluorescence (PLIF) technique. Single 10 mg droplets were burned in a flat flame at temperatures ranging from 1600 to 1725 °C with an equivalence ratios of 0.8, 0.9 and 1.25 and excess oxygen concentrations of 3.7, 1.8 and 0 (vol%), respectively. Under these conditions, the magnitude and temporal release of atomic sodium for the liquors with and without boron were not significantly influenced by the boron. However, the addition of boron to the liquor clearly reduced the total atomic sodium released, especially during the char consumption stage.