Characterization of Spray-Drying Nozzles at Industrially Relevant Conditions

Executive Summary

This project seeks to develop physically realistic models for atomization processes relevant to particle production, such as in spray-drying processes, with a focus on high viscosity and non-Newtonian fluid atomization. The goals of this work are to generate a spray database and to develop understanding and correlations for the accurate pilot-to-production scaleups. We have divided the work to focus on two nozzle types: pressure-swirl, and two-fluid nozzles. The followings are achieved in the present reporting period.

Pressure‐swirl:

• Completed testing of Fine Spray nozzles with several different fluids with varying viscosities. The droplet size distributions, closeup images of the atomization zone, and other statistics are obtained and reported.
• A correlation for SMD has been found using pressure-based Weber number and Reynolds number.
• The above correlation does not work well for sprays formed by small orifice nozzles using high viscosity fluid (60 cps). This was found to be due to change in the atomization mechanism for such cases. Atomizing very high viscosity fluid (60 cps) with small orifice nozzles may result in very large SMD, indicating a poor atomization quality. This is due to significant pressure loss across small orifices using high viscosity liquids.
• The above correlation has also been tested with experimental data by other researchers that have used different nozzle designs.