(284e) Modeling and Design of a Spray Dryer for the Manufacture of Hollow Micro-Particles

Spray drying technology is used in a wide range of processes ranging from the manufacture of food products to pharmaceuticals. More recently, spray drying has also been explored to make hollow micro-particles. These particles are useful for drug delivery lightweight composites applications [1]. In spite of such varied applications, the design of spray drying equipment has largely been an empirical process. The difficulty with a more fundamental approach is mainly due to modeling the particle and fluid flow patterns in the spray drying chamber. The advent of computational fluid dynamics (CFD) has allowed for more accurate model of these processes but CFD models typically require large run-times and parameters that are difficult to measure and generalize.

In this work, the rate-based method by Gauvin and Katta [2] is used to design a spray-dryer that manufactures hollow polymeric micro-particles [3]. The design is based on the type of atomizer used, the product specifications, the energy requirements, etc. The gas and particle flows are modeled using a mixed Eulerian-Lagrangian approach; and the heat transfer and mass transfer between the droplets and the gas are represented by the model of Shabde et. al [3]. An initial chamber size is chosen and the models are solved iteratively until the desired product specifications are obtained.

An advantage of using the rate-based method to model the spray dryer is that such models can capture the complexity of the process while at the same time remain computationally tractable. These features are attractive for control system design or process optimization.

The design specifications obtained from the rate-based model will be compared to data obtained from an experimental spray-dryer unit. This work will also investigate the sensitivity of product quality to changes in operating conditions such as feed rate, feed temperature, and drying gas flow rate.

References

[1] Wilcox, D.L., Berg, M.(eds) (1995) Materials Research Soc. Symp. Proc., 372.

[2] Gauvin, W.H., Katta S., (1976) AIChE J, 22.

[3] Shabde, V.S., Emets, S.V., Mann, U., Hoo, K.A., Gladysz, G.M., and Carlson, N.N. (2005) to appear in Compt. & Chem. Engng.