Continuous crystallization process

• US 20050159631A1
• Filed: 02/15/2005
• Published: 07/21/2005
• Est. Priority Date: 10/28/2002
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Kimura, Hiroaki, Koga, Yoshio
• Granted Patent: US 7,034,191 B2
• Time in Patent Office: Days
• US Class Current: 568/724
• CPC Class Codes: C07C 37/84 by crystallisation
• CPC Class Codes: C07C 39/16 Bis-(hydroxyphenyl) alkanes; Tris-(hydroxyphenyl)alkanes

Abstract

A continuous crystallization process comprising the steps of supplying a crystallization material containing bisphenol A to a crystallizer to form crystals of an adduct of bisphenol A and phenol or crystals of bisphenol A, subjecting the slurry discharged from the crystallizer to solid/liquid separation, and recovering the crystals, wherein part of the mother liquor is circulated to the crystallizer. According to this process, the heat duty to be removed is reduced, deposition of solids on the inner surfaces of the crystallizer, particularly on the heat transferring surface of the cooler is restrained, and consequently the continuous operating time of the apparatus is prolonged.

Claims

1. An improved continuous crystallization process comprising steps of supplying a crystallization material containing bisphenol A to a crystallizer to form the crystals of an adduct of bisphenol A and phenol or the crystals of bisphenol A, subjecting the slurry discharged from the crystallizer to solid/liquid separation, and recovering the crystals,

part of the mother liquor being circulated to the crystallizer.

2. The process according to claim 1, wherein the amount of the mother liquor circulated to the crystallizer is 5 to 60% by weight of the amount of the slurry discharged.

3. The process according to claim 1, wherein the mother liquor circulated to the crystallizer contains fine crystals in a ratio of 0.01 to 10% by weight.

4. The process according to claim 1, wherein the crystallizer has an external circulation line provided with a cooler, and the mother liquor is passed into this external circulation line for circulation therethrough to the crystallizer.

5. The process according to claim 1, wherein the difference between the outlet temperature of the crystallization material preparation tank and the outlet temperature of the crystallization tank is 5 to 35°

C.