Method of crystallization

The present invention relates to a multi-stage crystallization process which comprises the steps of feeding a solution of terephthalic acid or a slurry (raw slurry) containing terephthalic acid partially precipitated to a first crystallization vessel to precipitate the terephthalic acid therein; and...

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Bibliographic Details
Main Authors Zaima, Fumiya, Hoshishima, Nirou
Format Patent
LanguageEnglish
Published 15.05.2012
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Summary:The present invention relates to a multi-stage crystallization process which comprises the steps of feeding a solution of terephthalic acid or a slurry (raw slurry) containing terephthalic acid partially precipitated to a first crystallization vessel to precipitate the terephthalic acid therein; and feeding a slurry (crystallization slurry) containing the thus precipitated terephthalic acid sequentially to second and subsequent crystallization vessels, wherein while continuously supplying a cleaning solvent to a delivery conduit connecting the former-stage crystallization vessel and the next latter-stage crystallization vessel to each other, the crystallization slurry is fed through the delivery conduit. There is provided a multi-stage crystallization process using a solution of terephthalic acid or a slurry containing terephthalic acid partially precipitated as a raw material in which even when the process is operated for a period as long as several months, the delivery conduit is free from occurrence of clogging.