ATOMIZATION OF COAL-WATER FUELS BY A PNEUMATIC NOZZLE - CHARACTERISTICS OF THE SPRAY

摘要

The main characteristics of CWF (coal-water fuel) sprays produced by an internal mixing twin fluid atomizer are analyzed. Drop size and concentration have been determined by a laser light diffraction method (Malvern) and a high-speed photographic technique. The combined use of different experimental methods, along with the numerical inversion of line-of-sight measurements, allows a reliable characterization of the spray structure along radial and axial coordinates. The mean drop size depends essentially on the dynamic head of the atomizing air, the surface tension, and the coal particle size distribution of the slurry fuel. No clear effect of the CWF's apparent viscosity has been detected. The equation developed to correlate mean drop size takes all relevant factors into account and was derived for a nozzle operating with sonic flow in the exit ports.\udThe main characteristics of CWF (coal-water fuel) sprays produced by an internal mixing twin fluid atomizer are analyzed. Drop size and concentration have been determined by a laser light diffraction method (Malvern) and a high-speed photographic technique. The combined use of different experimental methods, along with the numerical inversion of line-of-sight measurements, allows a reliable characterization of the spray structure along radial and axial coordinates. The mean drop size depends essentially on the dynamic head of the atomizing air, the surface tension, and the coal particle size distribution of the slurry fuel. No clear effect of the CWF's apparent viscosity has been detected. The equation developed to correlate mean drop size takes all relevant factors into account and was derived for a nozzle operating with sonic flow in the exit ports.