Title:
METHOD FOR RECOVERING CRYSTALS FROM A CRYSTALLIZATION SLURRY
Document Type and Number:
WIPO Patent Application WO/2010/119484
Kind Code:
A1
Abstract:
In conventional recovery of pure terephthalic acid crystals, separation while maintaining the final crystallization tank slurry at the highest possible temperature (maximum 205°C) and high pressure is preferred from the point of view of ease of separation of p-toluyl acid, and expensive high temperature and high pressure plant is needed for the separator (filter, centrifuge) and the system therefor (removal of the wet separation cake, separating liquid/washing liquid receiving tanks and pressurized circulation gas system, etc.). Disclosed is an effective method for filtration and washing, which is a method for recovering crystals from a crystallization slurry comprising a solvent and precipitated crystals by pressure filtration, wherein the content of impurities in the recovered crystals is decreased by employing a filter system using comparatively low pressure. In pressure filtration at no more than ca. 6 kg/cm2G, the filtration cake is washed by employing a washing solution superheated until the vapour pressure thereof exceeds the pressure of the filter system, the solution being supplied at least as a steaming washing solution. Washing is carried out by supplying a washing solution superheated until the proportion of vapour produced exceeds ca. 2%, and preferably a washing solution superheated until this proportion is at least ca. 4%.
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Inventors:
HARA, Noriaki (5-2 Higashi-Ikebukuro 4-chome, Toshima-k, Tokyo 66, 17084, JP)
原徳明 (〒66 東京都豊島区東池袋四丁目５番２号株式会社日立プラントテクノロジー内 Tokyo, 17084, JP)
TOYOSHIMA, Hiroyuki (5-2 Higashi-Ikebukuro 4-chome, Toshima-k, Tokyo 66, 17084, JP)
原徳明 (〒66 東京都豊島区東池袋四丁目５番２号株式会社日立プラントテクノロジー内 Tokyo, 17084, JP)
TOYOSHIMA, Hiroyuki (5-2 Higashi-Ikebukuro 4-chome, Toshima-k, Tokyo 66, 17084, JP)
Application Number:
JP2009/001763
Publication Date:
October 21, 2010
Filing Date:
April 16, 2009
Export Citation:
Assignee:
Hitachi Plant Technologies, Ltd. (5-2 Higashi-Ikebukuro 4-chome, Toshima-ku Tokyo, 66, 17084, JP)
株式会社日立プラントテクノロジー (〒66 東京都豊島区東池袋四丁目５番２号 Tokyo, 17084, JP)
HARA, Noriaki (5-2 Higashi-Ikebukuro 4-chome, Toshima-k, Tokyo 66, 17084, JP)
原徳明 (〒66 東京都豊島区東池袋四丁目５番２号株式会社日立プラントテクノロジー内 Tokyo, 17084, JP)
株式会社日立プラントテクノロジー (〒66 東京都豊島区東池袋四丁目５番２号 Tokyo, 17084, JP)
HARA, Noriaki (5-2 Higashi-Ikebukuro 4-chome, Toshima-k, Tokyo 66, 17084, JP)
原徳明 (〒66 東京都豊島区東池袋四丁目５番２号株式会社日立プラントテクノロジー内 Tokyo, 17084, JP)
International Classes:
C07C51/43; B01D9/02; C07C63/26
Attorney, Agent or Firm:
Polaire I.P.C. (7-1 Hatchobori 2-chome, Chuo-ku Tokyo, 32, 10400, JP)
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