Process for the production of crystalline adduct of bisphenol A and phenol and apparatus therefor

A process for the production of a crystalline adduct of bisphenol A and phenol, comprising the steps of:

• providing a crystallization zone having an outer cylindrical housing and an inner cylindrical member defining therein an inner passage and coaxially disposed within said outer cylindrical housing to define an annular, outer passage therebetween, said inner passage being in fluid communication with said outer passage only at an upper portion of said inner passage;
• admixing a solution of bisphenol A dissolved in phenol with a cooled slurry to form an admixture;
• feeding said admixture to a lower portion of the outer portion passage of said crystallization zone and passing same to said inner passage so that an adduct of bisphenol A and phenol is crystallized at a first temperature of 45.degree.-70.degree. C. to obtain a slurry containing crystals of the adduct;
• discharging the slurry from the bottom of the inner passage of said crystallization zone;
• cooling a first portion of the slurry discharged from said crystallization zone to a temperature not more than 10.degree. C. less than the first temperature to obtain said cooled slurry;
• heating a second portion of the slurry discharged from said crystallization zone to a temperature 0.5.degree.-5.degree. C. more than the first temperature to dissolve fine crystals contained therein and recycling said heated slurry to said crystallization zone;
• and
• recovering the crystals from the slurry discharged from said crystallization zone,
• each of said admixture and said heated slurry being fed to said outer passage of said crystallization zone such that the slurry in said outer passage forms a vortex flow.

A process for the production of a crystalline adduct of bisphenol A and phenol, comprising the steps of:

• providing a crystallization zone and a plurality of cooling zones connected in parallel with each other and each having a cooling surface adapted to cool a liquid upon contact therewith;
• feeding a solution of bisphenol A dissolved in phenol to said crystallization zone and cooling same to a temperature of 45.degree.-70.degree. C. to crystallize an adduct of bisphenol A and phenol and to obtain a slurry containing crystals of the adduct;
• discharging the slurry from said crystallization zone;
• introducing a portion of the slurry discharged from said crystallization zone to all of said cooling zones except one cooling zone whose cooling surface bears deposits of crystals of the adduct to cool the slurry introduced thereinto with the simultaneous formation of crystals of the adduct on the cooling surfaces thereof;
• recycling the cooled slurry to said crystallization zone so that the slurry in said crystallization zone is cooled;
• recovering the crystals from the slurry discharged from said crystallization zone;
• and
• removing the deposits from the cooling surface of said one cooling zone.

A process for the production of a crystalline adduct of bisphenol A and phenol, comprising:

• (A) a first stage including the steps of:
• (A-a) feeding a solution of bisphenol A dissolved in phenol to a crystallization zone and cooling same to crystallize an adduct of bisphenol A and phenol and to obtain a slurry containing crystals of the adduct, and
• (A-b) discharging said slurry from said crystallization zone and introducing same into a solid-liquid separating zone to separate said slurry into a solid phase containing crystals of the adduct and a liquid phase containing phenol;
• and
• (B) one or more, second to n-th stages following said first stage and each including the steps of:
• (B-a) dissolving the solid phase obtained in the immediately preceding stage into solvent phenol to obtain a solution,
• (B-b) feeding said solution obtained in step (B-a) to a crystallization zone and cooling same to crystallize an adduct of bisphenol A and phenol and to obtain a slurry containing crystals of the adduct, and
• (B-c) discharging said slurry obtained in step (B-b) from said crystallization zone and introducing same into a solid-liquid separating zone to separate said slurry into a solid phase containing crystals of the adduct and a liquid phase containing phenol, said process further comprising the steps of:
• washing the solid phase obtained in the n-th stage with purified phenol to obtain a washed solid product and used phenol,
• recovering the washed solid product,
• recycling at least one of a first part of said used phenol and a first part of said liquid phase obtained in said n-th stage to step (B-a) of the (n-1)th stage as at least part of said solvent phenol,
• washing the solid phase obtained in the (n-1)th stage with at least one of a second part of said used phenol and a second part of said liquid phase obtained in said n-th stage, and
• controlling the purity of the solvent phenol used in each of said second to n-th stages so that the content of impurities in the solvent phenol used in one stage of said second to n-th stages is greater than that of the stage immediately following said one stage.