A new model and a design procedure for an Oslo-Krystal cooling crystallizer

• A new steady-state model of an Oslo-Krystal cooling crystallizer is presented.
• Bed voidage and crystal size, residence time and production rate can be predicted.
• A design procedure based on the model is also presented.

The operation of the industrial Oslo-Krystal cooling crystallizer is simulated in this work as a continuous fluidized bed crystallizer with liquor recycling, where seed crystals are added at the top of the fluidized bed and product crystals are withdrawn at the bottom of the fluidized bed. It is assumed that the liquid phase moves upward through the bed in plug flow and the solid phase in the fluidized bed is perfectly classified. A model is developed to describe the variations of crystal size, bed voidage, crystal residence time and crystal production rate with the vertical position within the crystallizer. The effects of seed feed rate, feed solute concentration, recycle ratio and height/diameter ratio on the performance of such continuous fluidized bed crystallizer can be elucidated. A procedure based on the model can be used to rapidly design the crystallizer.