BATCH CRYSTALLIZATION OF A PHOTOCHEMICAL - MODELING, CONTROL, AND FILTRATION

Model identification and control were studied for the seeded batch cry stallization of an organic, industrial photochemical. The growth and n ucleation kinetics are described by empirical power-law expressions in relative supersaturation, and an additional model describing crystal shape dynamics is proposed. The parameters in the kinetic models are e stimated from on-line measurements of solute concentration and transmi ttance. Parameter uncertainty is assessed, and optimal experimental de sign techniques are used to construct experiments to diminish uncertai nty. Given the identified model, optimal open-loop temperature schedul es are designed to improve the filtration of final-time slurries. The profiles minimize the mass of nucleated crystal relative to seed cryst al mass, subject to supersaturation and yield constraints. Filtration improvements are verified using constant pressure filtration tests to determine the flow resistance of the filter cake. The best control exp eriment gives a cake resistance 25% lower than the best identification experiment.