Spray dryer designed to recover 95% of particles

Researchers from the ARC Training Centre for the Australian Food Processing Industry in the 21st Century at the University of Sydney have developed a new pilot-scale spray dryer that is designed to recover 95% of particles. The technology could improve efficiencies, cost savings and product quality for food and medicine businesses.

Spray dryers use hot gas to convert liquid to powders and are therefore crucial for the development of products such as powdered milk, instant coffee and cereal in the food industry, and pharmaceutical products such as antibiotics.

“We have only tested the new spray dryer with salt so far, but all foods and pharmaceuticals will potentially benefit from this new design. Many waste products will also be treatable in ways that current designs cannot do,” said Professor Timothy Langrish, who is leading the research with his PhD candidate Harry Huang.

However, a disadvantage of spray dryers is the fact that sediment and particles often settle onto the inner surface of the dryer. The new spray dryer aims to combat this problem by using a stable air flow.

“The new design features of this spray dryer have created a stable air flow, which reduces the likelihood of particles colliding with the wall, thereby reducing the amount of deposition and improving product recovery,” Langrish stated.

While standard dryers have over 30% wall deposition, the new system reduced this number to only 5% of solid materials remaining in the drying chamber.

“This outcome means almost all of the dried particles can be recovered from the system without being exposed to high temperatures for a long period of time,” said Huang.

The spray drying system is therefore particularly useful for products such as foods, pharmaceuticals and bioactives as it reduces the degradation of heat-sensitive compounds.

Langrish suggested they plan to further develop the system in order to dry materials at a higher capacity, and the design feature which reduces pressure fluctuations is also currently being patented.