Distillation process for making pure acetic acid

Claim 1

PROCESS FOR THE MANUFACTURE OF ACETIC ACID IN A STATE OF HIGH PURITY FROM A CRUDE ACETIC ACID MIXTURE CONTAINING VOLATILE, EASILY OXIDIZABLE IMPURITIES BOILING NEAR THE BOILING POINT OF PURE ACETIC ACID, THE COMPRISES INTRODUCING THE CRUDE ACID WHILE IN LIQUID PHASE INTO AN INTERMEDIATE BUT UPPER FIRST ZONE OF A VERTICAL FRACTIONATING COLUMN WHILE MAINTAINING THE INTERNAL PRESSURE OF THE COLUMN AT A SUBATMOSPHERIC PRESSURE; MAINTAINING WITHIN SECOND ZONE WITHIN THE COLUMN, LOCATED IMMEDIATELY BELOW AND IN COMMUNICATION WITH THE FIRST ZONE, AT A CONTROLLED TEMPERATURE SUBSTANTIALL EQUALLING THE BOILING POINT OF PURE ACETIC ACID AT THE PRESSURE MAINTAINED WITHIN THE COLUMN; WITHDRAWING SUBSTANTIALLY PURE ACETIC ACID IN VAPOR PHASE FROM THE LOWER PORTION OF THE CONTROLLED TEMPERATURE ZONE NEAR THE MIDDLE OF THE COLUMN; WITHDRAWING LOW BOILING COMPONENTS FROM THE TOP OF THE COLUMN; AND DISCHARGING HIGHER BOILING AND NON-VOLATILE COMPONENTS IN LIQUID PHASE FROM THE BASE OF THE COLUMN.