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    Separation by crystallization
    3.
    发明授权
    Separation by crystallization 失效
    通过结晶分离

    公开(公告)号：US2835598A

    公开(公告)日：1958-05-20

    申请号：US47868854

    申请日：1954-12-30

    Applicant: PHILLIPS PETROLEUM CO

    Inventor： KOLNER SAMUEL J

    IPC: B01D9/00 ,  C07C7/14

    CPC classification number: B01D9/0013 ,  B01D9/004 ,  B01D9/0063 ,  C07C7/14 ,  C07C29/78 ,  C07C45/81 ,  C07C46/10 ,  C07C67/52 ,  C07C255/00 ,  C07C15/08 ,  C07C31/08 ,  C07C31/12 ,  C07C49/08 ,  C07C49/10 ,  C07C50/04 ,  C07C69/24 ,  C07C69/54 ,  C07C69/80

    Abstract: In a process for fractional crystallization wherein a crystal mass is introduced into a purification zone and moved to a heated portion of the zone so that a first portion of resulting melt is caused to be displaced counter-currently through at least a portion of the crystal mass, a mother liquor stream being removed from the system and a second portion of the melt being removed from the system as product, the temperature differential existing between the crystals introduced to the purification zone and the mother liquor removed from the purification zone is determined, and the rate of product removal is increased when the temperature differential reaches a predetermined maximum value and decreased when the temperature differential reaches a predetermined minimum value. A mixture of material is cooled to crystallize at least a portion of the constituent to be separated, and the slurry is filtered to remove some of the mother liquor. The crystal mass containing some mother liquor is fed by a conveyer 12 (Fig. 1) to a purification column 11, where a piston 14 compacts the crystal mass and forces the compacted mass towards a heater 15, mother liquor being removed by a filter 16 and a line 17. The heater 15 melts the crystals, a portion of the melt being displaced counter-currently through the crystal mass to displace occluded impurities from the mass approaching the heater 15, and substantially pure molten product is removed by a line 18. The temperature of the feed to the column 11 is determined by an element 21, such as a thermocouple, and the temperature of the mother liquor leaving the column by line 17 is determined by another element 22. Elements 21 and 22 are connected to a temperature controller 24 which controls a valve 23 in line 18. Controller 24 is adjusted to maintain the temperature of the mother liquor in line 17 within a predetermined range higher than the temperature of the feed, by opening valve 23 when the temperature in line 17 rises above the predetermined range so that product is removed at a higher rate and so reduces the temperature in line 17, and by closing valve 23 when the temperature in line 17 falls below the predetermined range so reducing the rate of product removal and thus reducing the removal of heat from the column. By controlling the temperature differential between the mother liquor in line 17 and the feed, the effectiveness of the washing action of the counter-currently-flowing melt is controlled. When the temperature of the feed is constant element 21 may be omitted. In an example, para-xylene is separated from a mixture containing ortho-, meta- and para-xylenes, ethylbenzene and toluene. A list of compounds which may be separated from mixtures containing them, is given.

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