Estimation of crystallization kinetics for an organic fine chemical using a modified continuous cooling mixed suspension mixed product removal (MSMPR) crystallizer

The crystallization kinetics of an important organic fine chemical was determined using a modified laboratory scale continuous cooling mixed suspension mixed product removal (MSMPR) crystallizer with a product recycle loop designed for use with limited quantities of available material. A convenient method of monitoring steady state in the MSMPR using lasentec focussed beam reflectance measurement (FBRM) is also described. The effect of supersaturation, suspension density of the crystallizer content, impeller velocity (turnover time) and configuration on the growth and nucleation rates was studied. An observed deviation from the McCabe ΔL law for small crystal sizes was attributed to either size-dependent growth (SDG) or growth rate dispersion (GRD) mechanisms and hence complicated the estimation of growth and nucleation rates. SDG was successfully modelled using a three-parameter exponential SDG model. Growth rates estimated from the SDG model were compared to a GRD model using discrete growth probability distributions.