The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 15, 2012
Filed:
May. 02, 2007
Fumiya Zaima, Okayama, JP;
Nirou Hoshishima, Okayama, JP;
Fumiya Zaima, Okayama, JP;
Nirou Hoshishima, Okayama, JP;
Mitsubishi Gas Chemical Company, Inc., Tokyo, JP;
Toyobo Co., Ltd., Osaka, JP;
Mizushima Aroma Company, Ltd., Okayama, JP;
Abstract
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.