公开(公告)号：US3378236A

公开(公告)日：1968-04-16

申请号：US58989066

申请日：1966-10-27

Applicant: TSUKISHIMA KIKAI CO

Inventor： TATUSI KASAI

IPC: B01D9/00

CPC classification number: B01D9/0018 ,  B01D9/0036

Abstract: 1,161,474. Growing crystals. TSUKISHIMA KIKAI CO. Ltd. 26 Oct., 1966 [27 Oct., 1965], No. 47996/66. Headings BIB, B1C, B1D and BIG. A crystallizer comprises a tube having a fixed lower part 2, and a rotatable upper part 3 carrying inner impeller blades 4 and outer blades 7 creating a circulation through the tube. When crystal have .grown to a predetermined size they separate from the circulating flow, fall into the classifying leg 9 and are withdrawn at 10, while the liquid from which they have been removed moves upwardly outside the baffle 11 and is discharged at 12 for re-heating and re-cycling through inlet 1. Solvent vapour leaves at 13 to waste or recovery. The impeller blades are so pitched and dimensioned that the mass flow rate of the magma is the same up the tube and downward outside it, and the impeller is driven so that the crystals fall faster than the descending liquid while the inner impeller 4 assist the upward flow only sufficiently to compensate for the .resistance of .the tube support; in consequence wear of the crystals is much reduced. In another embodiment (Fig. 3, not shown) the draft tube has three parts of which the middle (22) rotates and overlaps the lowest (21) which is smaller in diameter and may contain an additional impeller (24). The outer impeller (7) in this case has a greater mass flow than the inner (4) so that part of the liquid containing the smaller crystals circulates through the annular gap between the tube portions (21), (22) while part ascends through k the lowest tube portion (21) depositing in the bottom of the apparatus crystals which have reached a predetermined uniform size.