A Study of the In-situ Indirect Freezing Process

摘要

It has been demonstrated that high degree separations of aqueous and organic mixtures can be accomplished and an energy saving can be realized by the In Situ indirect freezing process conducted in a small conduit freezer-melter. The process has two versions: the first version, denoted as the dendritic deposit approach, is useful in accomplishing a high degree separation of a concentrated solution and the second version, denoted as the smooth deposit approach, is useful in a high degree purification of a dilute solution. A pressure-induced nucleation approach and a seeded feed approach with ultrasonic nucleation have been introduced to initiate a freezing step uniformly; a pressure-programmed supersaturation approach has been introduced to obtain a close control for heat transfer and a close control of the morphology of the deposited solid phase. Products containing less than 350 ppm NaCl were obtained from feeds containing 40,000 ppm and 5000 ppm respectively by the two approaches.