GB760810A - Improvements in and relating to processes and installations for crystallizing substances from solutions - Google Patents

Abstract

<PICT:0760810/III/1> <PICT:0760810/III/2> <PICT:0760810/III/3> A crystallizing apparatus comprises means for producing supersaturation in a liquid (a heater and an evaporator or a cooler or a heater only) and a crystallizer arranged in two circuits, the circuit containing the crystallizer forming a shunt to the circuit containing the supersaturator and the flow through the shunt circuit being smaller than that through the primary circuit. By this means more efficient use may be made of the supersaturating system. The crystallizer may be of the type in which crystals are maintained in suspension until they grow to the required size. Entrained small crystals may be wholly or partially separated from the liquor returning from the crystallizer to the primary circuit. As described, Fig. 1, liquor is circulated from an evaporator B via pumps F and G to heater A and back to evaporator B while liquor is also taken from B to crystallizer H and then by overflow K back to the primary circuit. In Fig. 2 liquor is circulated by pump F through heater A and evaporator B, liquor also being taken from the evaporator at M to crystallizer H from which it is returned by pump G to the evaporator. In Fig. 3 liquor is circulated by pump F from evaporator B through heater A back to the evaporator. A secondary flow is also maintained by pump G from evaporator B crystallizer H and separator N which removes entrained crystals and returns them at P to the crystallizer. In all arrangements fresh liquor is introduced at E.