Simulation of the semicontinuous supercritical antisolvent recrystallization process

A model is developed for simulating semicontinuous supercritical antisolven t recrystallization processes. Thermodynamics, hydrodynamics, and mass-tran sfer issues are addressed. The model makes it possible to calculate the com position and flow-rate profiles of the vapor and liquid phases and the amou nt of the solid product along the precipitator. The effect of the operating variables is discussed. With reference to a CO2-toluene-naphthalene-phenan threne system, it is shown that the dissolution of the antisolvent in the l iquid phase is usually faster than the evaporation of the solvent, that the two solutes may behave in completely different ways at the same process co nditions (for example, phenanthrene can be easily precipitated, while for n aphthalene a higher gas-to-liquid flow-rate ratio is needed, to force solve nt evaporation), and that under proper operating conditions it is possible to selectively precipitate phenanthrene from a phenanthrene + naphthalene s olution.