Although it is typically a simple benchtop application, crystallizing poses challenges when designing a continuous processing system. Our systems typically begin with a Solidaire paddle dryer equipped with multiple jacketed zones. The first jacketed zone is heated with hot oil or steam, which heats the feed solution to a super-saturated state. Then a transition begins into one or more cooling zones to crash the crystals out of the heated solution. The resultant output of solids and the remaining liquid solution moves to a filtering and washing step, followed by a final drying step to remove and recover any residual solvents from the crystallized solids.
The unique design of the Solidaire paddle dryer enables it to work through the difficult transition phase, making continuous crystallizing operations possible. We’ve utilized this approach to crystallize sugars, salts, and low molecular weight polymers.