Laboratory and Analytical Study of Shattering Jelly Roll Smelt

During kraft chemical recovery, smelt created in a recovery boiler is shattered into droplets before falling into a dissolving tank. Although a rare occurrence, highly viscous smelt is created when the smelt temperature is close to the smelt freezing temperature, so-called jelly roll smelt. The viscosity of jelly roll smelt is estimated as between 10^4 to 10^5 cP. In this research, a laboratory study was conducted and an analytical model was developed to study the shattering of such highly viscous smelt. The study shows that an increasing viscosity undermines the shattering effectiveness by delaying the complete breakup of the liquid stream, and creating large droplets. The analytical model is based on the physics of co-axial atomization, and is shown to fit the lab scale droplet size distribution very well. Given the shattering conditions, the model appears able to estimate the droplet size distribution and maximum shatterable viscosity.M.A.S