INFLUENCE OF DIFFERENT SCALES OF MIXING IN REACTION CRYSTALLIZATION

摘要

Semi-batch reaction crystallization of benzoic acid is studied experimentally. The conditions in an agitated tank are simulated by a loop reactor by which feed point mixing intensity can be controlled separately from the macroscale circulation rate. Hydrochloric acid and sodium benzoate are mixed and the influence of macromixing, mesomixing and micromixing on the product crystal mean size is evaluated. The results reveal a significant influence from all three levels of mixing. The product mean size increases with increasing circulation rate in the loop, with increasing feed point mixing intensity and with reduced feed pipe diameter. The results cannot be explained simply by the level of the mixing energy dissipation rate at the feed point.