Batch cooling crystallization study based on in-line measurement of supersaturation and crystal size distribution

Abstract

The in-line information of supersaturation and crystal size distribution is very important for the controlling and optimization of batch cooling crystallizations. Based on the in-line measurements of supersaturation with an attenuated total reflectance-Fourier transform infrared spectrophotometer and chord length distribution with an MTS laser reflection analyzer, the batch cooling crystallization of an organic compound, labeled as C15 is studied in this work. The crystal size distribution of the final product was also analyzed with a laser diffraction analyzer to verify the data obtained from the in-line instrument. Various cooling modes are tested, and the seeding policy is applied to improve the final crystal size distribution. The effects of the cooling modes and seeding are analyzed based on the obtained in-line supersaturation and off-line crystal size distribution data. Improved operation conditions are proposed in terms of large mean crystal size and narrow crystal size distribution. The result of this work shows that the spectrophotometer gave accurate solution concentration results with high resolution; the MTS in-line analyzer can be used to monitor chord length distribution and count rate trends.