Use of calorimetry model and batch control technique for scale-up of unseeded batch cooling crystallization of poly(hydroxybenzophenone)

A scale-up method to design and implement a cooling profile for unseeded batch cooling crystallization has been investigated. The reduced ratio between the heat-transfer area and the volume during scale-up to a large crystallizer causes an increase in the temperature distribution in the reactor, which can trigger unwanted nucleation around the cold spots of the vessel wall. To address this problem, a method is proposed to designa cooling profile for a scaled-up crystallizer that can replicate the seed-generation stage of a small crystallizer by effectively suppressing the unwanted nucleation. The use of a batch control technique as method ofimplementing the cooling profile in a large crystallizer is also proposed. Experiments were conducted with a 100 mL reactor and a 5 L scaled-up reactor for the unseeded crystallization of poly(hydroxybenzophenone) (PHBP) to verify the performance of the proposed method.