Real-time control of microcrystal formation with inline process microscopy

Abstract

The control of microcrystal formation during crystallization is necessary to ensure good separation of crystals and molasses without adding excessive wash water. This paper presents an automatic inline process microscope measurement of sugar crystals and how its results are utilized in a real-time process control. The system captures high-precision transilluminated images of sugar crystals flowing through a 10-mm wide gap in the evaporating crystallizer. It automatically analyses the sugar crystals in size range from 10 µm to 4 mm visible in images. System reports the number of detected microcrystals (10–30 µm) and crystals (>30 µm), mean aperture of crystals (MA), co-efficient of variation in size (CV), crystal growth rate and volume fractions of the specified crystal size classes in real time. The performance of the control and monitoring approach is highlighted with the results of example strikes.