One of the crucial variables that affects the quality of the powder is its moisture content. Depending on its end use, the powder should contain between approximately 3 to 6 percent moisture. The key to achieving the right moisture level is to control the temperatures of the air entering the tower, the static fluid bed, and the vibrating fluid beds.
In the past, Murray Goulburn operators manually changed these temperature set points to control throughput and moisture content. These decisions were based on the operator’s experience utilizing feedback from moisture samples taken once an hour. The company’s engineers recognized that once an hour was too long an interval, considering the importance of keeping the moisture balance in the powder. Tests on samples taken every hour showed the moisture would often vary by as much as 0.3%. To create a more consistent product, the temperature setpoints would need to be adjusted automatically based on a predictive model of the dryer.
Maintaining temperature and moisture balance was also important for keeping production at its highest possible level. When the moisture in the air exiting the dryer was too high, the dryer could block and shut down, leading to wasted time, wasted resources and – ultimately – reduced yields.
“We knew we needed an automated system to reduce the moisture variability of the powder,” said Geoff Rome, automation and utilities engineer at Murray Goulburn. “Our goal was to find a solution that would help us maintain consistent quality while increasing final product throughput.”