(79b) On the Development of an Innovative and Sustainable Spray Drying Technology

Spray drying is the main process used for producing powders from a liquid feed in food, pharmaceutical and chemical industries. The spray drying process has unique advantages, such as the ability to produce powders with a specific particle size and moisture content, handling heat sensitive products, and possibility of high volume application. In recent years, major focus has been given on understanding and modeling the spray drying process in order to facilitate the choice of operating conditions, which are product dependent, and to optimize energy usage. However, spray drying still remains a complex energy intensive process.

Spray drying is a convective drying method, which has low thermal efficiency. A liquid feed is atomized at the top of a drying chamber into a flow of hot air. For several products, this leads to a rapid reduction of surface moisture, which causes hindrance to moisture content transfer from the inner part of the particles. Consequently, a long drying time is required, which explain the generous height of industrial spray dryer chambers. Large volume of the chamber and long drying time make it difficult to control the morphology of the dry powder, and hence, reduce the quality of final product. Furthermore, a large volume of drying chamber leads to longer warm-up period, and makes the process complex, as a bigger hot air flow needs to be ensured.

Unlike the convective heating, electromagnetic drying is rapid and energy efficient, it promotes expulsion of inner water to the surface, and it allows selective heating of the materials depending on the local water content preventing damage to the surface and to the already dry area.

The goal of this project is to improve thermal efficiency of the spray drying process by combining electromagnetic and convective heating. Such an improvement might aid development of a more flexible and sustainable process for the production of functionalized powders starting from a liquid feed.

In this presentation, a new single-particle electromagnetically assisted drying-kinetics device is shown. It allows acoustic levitation of a single-particle and evaluation of the drying kinetics during combined convective drying and electromagnetic energy. In order to present the potential of this novel methodology, drying-kinetics and dynamic morphological changes of trial food particles in case of pure convective and electromagnetically assisted drying are compared.

Combination of electromagnetic energy and spray drying is a novel technology and it is expected to improve drying efficiency in food, pharmaceutical and chemical industries, and it could contribute to the development of innovative products in the powder form.