Patent GB-1366170-A (GB)
Title: Processes and apparatus for effecting exchange crystallisation and co mponent separation
IPC: B01D9/00
Filed: 1971-10-15
Abstract: 1366170 Exchange crystallization; centrifugal separators E-C CORP 15 Oct 1971 47972/71 Headings B1G and B2P [Also in Division C1] A process of effecting exchange crystallization and component separation from a mixture of non-gaseous materials which includes a first material which undergoes an increase in melting point upon being subjected to an increase of pressure and a second material of density different from the first material and which undergoes a decrease in melting point upon being subjected to the same increase in pressure by first bringing the temperature and pressure on mixture to such a level as to cause melting of the first material and solidification of the second material. Then transferring this mixture to a curvolinear chamber which rotates about a vertical axis and includes a linear part extending radially outward from the neck portion which receives the mixture, and passes into a confining chamber wherein pressure is developed on the mixture which causes freezing of the first material and melting of the second material, separating the so formed materials by density difference by deflecting each material into a separate annular passageway mounted coaxially with the chamber and recovering the materials. The process is preferably used for recovering fresh water from brackenish water or sea water by mixing the water with a heat-exchange medium such has a hydrocarbon to form an ice hydrocarbon slurry, feeding this mixture under pressure into the ourvolinear chamber and recovering therefrom fresh water and a slurry containing the hydrocarbon medium. Centrifugal separators. The centrifugal separator and exchange crystallizer comprises a curvolinear chamber which is supported symmetrically about a vertical axis and includes a linear part extending transversely of the axis and merging into an arcuate part, a feed neck coaxial with the axis of the chamber and leading to the linear portion of the chamber, deflecting means associated withthe arcuate part of the chamber for the separationby density difference the components of the exchange crystallized material via passageways which turn towards the axis of the chamber on either side of the deflector, means for recovering the separated components and rotational drive means for the chamber. As shown in Fig. 1, chamber 10, includes an inner housing 12, and an outer housing 14, between which is passageway 16, which is increased in radial dimensions by an inwardly directed shoulder on the inner housing 12 and shoulder 20 on the outer housing 14. Positioned within this enlarged space is an arcuate deflector 22, which separates this space into a pair of individual annular passageways of which the inner is designated by 24, and the outer by 26. The passageways merge into concentric tubular outlets 50 and 52 respectively and dual take-off pipes 60 and 64. The mixture to be separated is introduced via pump 40 to duct 30 and around the neck of this duct is attached a drive gear 36 which rotates 10. The exchange crystallization of the accelerating mixture passing through conduit portion 16a is effected at 16b by contact with the wall 14a which functions as a barrier wall. In another embodiment shown in Fig. 2, the mixture is charged to chamber 70 through axially disposed conduit 72 into intake duct 74, and spreads in a radial direction through passageway 104 to annular confining chamber 106 disposed near the radially outer extremity of the housing 78 where exchange crystallization takes place. The chamber is rotated at a high speed by motor 92 via gears 94, 96, 98, and 82, and the exchanged crystallized mixture separated into two parts by deflector 102, which forms with the intake duct and housing 78 two passageways 108 and 110 from which via take-off piping 120 and 122, the desired components of the mixture are recovered.