GB1240668A - Improvements relating to crystallizing apparatus - Google Patents

Abstract

1,240,668. Multi-stage crystallisation. GARRETT RESEARCH & DEVELOPMENT CO. Inc. 27 June, 1968 [2 May, 1968], No. 4873/ 71. Divided out of 1,240,667. Heading B1G. A multi-stage crystalliser comprises a housing divided by vertical partitions into a series of chambers, each partition having two apertures, an upper and a lower, for interconnecting the chambers, these being such that the crystallizing solution (e.g. a brine) can pass through the series of chambers from a first chamber to a final chamber, the lower aperture being for passage of the crystals through the chambers, they settling to the bottom of each chamber, and the upper connections for passage of the solution through the chambers. Each chamber has a heat exchange means associated therewith for cooling the solution and individual pump means for circulating the solution around the heat exchange means. In the embodiment shown each pump 118 pumps the solution around a circuit from the chamber 112 to sprays 120, the heat exchange medium being upwardly flowing atmospheric air circulated by a fan 124, the cooling tower walls being preferably air permeable. Baffles 108 and the heat exchange mechanism and funnel 110 serves to feed the crystals and solution back to the main body of the solution. The upper inter-chamber connections are at the surface level of the crystallizing solution and the lower 114 are at the bottom of the chamber partitions 104. The crystal slurry outlet is pipe 126, the solution inlet being either or both of pipes 118 and 82. A further embodiment (Fig. 3) has the solution pumped around a circuit including heat exchangers (74) in which pipes carry a common flow of cooling fluid in countercurrent to the direction of flow of the crystallizing solution. For certain purposes both embodiments may be in series, the atmospheric heat exchange type following the other.