PRODUCTION OF AROMATIC POLYCARBOXYLIC ACIDS

摘要

MOTHER LIQUOR, DERIVED FROM A PRIMARY SOLIDS-LIQUID SEPARATION PROCESS (18) FOR SEPARATING AROMATIC CARBOXYLIC ACID CRYSTALS FROM A SLURRY THEREOF IN THE MOTHER LIQUOR, IS SPLIT INTO A RECYCLE FRACTION (30) AND A PURGE FRACTION (32) THE RECYCLE FRACTION (30) IS RETURNED TO A REACTOR (10) IN WHICH THE AROMATIC CARBOXYLIC ACID IS FORMED BY LIQUID PHASE OXIDATION OF A PRECURSOR THEREOF. THE PURGE FRACTION (32) IS CONCENTRATED IN EVAPORATOR (42) TO RECOVER SOLVENT AND PRODUCE A RESIDUE FOR DISPOSAL OR FURTHER TREATMENT. BEFORE CONCENTRATION THE PURGE FRACTION (32), IT IS SUBJECTED TO SOLIDS-LIQUID SEPARATION IN FILTRATION UNIT (34) TO REMOVE FINE SOLIDS THEREBY REDUCING THE LOAD ON THE EVAPORATOR (42) AND FACILITATING THE RECOVERY OF GREATER AMOUNTS OF THE SOLVENT ALONG WITH RECOVERY OF AROMATIC CARBOXYLIC ACID FINES, E.G. FOR RECYCLE TO THE REACTOR (10).