Atomization of coal-water slurry using twin-fluid jet atomizer

Abstract

This paper presents both experimental and modelling results of airblast atomization of coal-water mixtures or slurries (CWMs) using a twin-fluid jet atomizer. Specifically, the mass median diameter (MMD) of atomized droplets is related to the slurry properties and atomization conditions through its power dependencies on the Weber number ( We), the Ohnesorge number ( Z) and liquid or fuel-to-air mass ratio ( W F W A ), namely, MMD D F = (A · We −x + B · Z 2x) (1 + W F W A ) y , where D F = the diameter of the fuel passage and A, B, x and y are constants determined by the least square method. The coal particle size and size distribution has substantial effects on both the droplet sizes and the exponents x and y. In addition, the presence of hydrophobic coal particles shifts the fundamental mechanisms of airblast atomization to the predominance of the fuel viscosity included in Z over the liquid surface tension included in We. Other factors such as particle packing efficiency also make significant contributions.