Process for distilling tall oil

Claim 1

IN A PROCESS FOR SEPARATING A MIXTURE OF TALL OIL FATTY ACIDS, ROSIN ACIDS, VOLATILE UNSAPONIFIABLES, AND PITCH INTO ITS COMPONENTS WHEREIN THE MIXTURE IS SUBJECTED TO FRACTIONAL DISTILLATION IN A FRACTIONATING COLUMN UNDER REDUCED PRESSURE AND IN THE PRESENCE OF STEAM, SAID COLUMN PROVIDING VERTICALLY-SPACED ZONES EACH CONTAINING A POOL OF LIQUID, THE METHOD OF OBTAINING A ROSIN ACID FRACTION HAVING A LOW CONTENT OF VOLATILE UNSAPONIFIABLES AND PITCH CHARACTERIZED BY THE STEPS OF INTRODUCING A MIXTURE INCLUDING TALL OIL FATTY ACIDS AND ROSIN ACIDS INTO AN INTERMEDIATE ZONE OF SAID COLUMN, THE ZONES IN THE UPPER PORTION OF SAID COLUMN BEING MAINTAINED AT LOWER PRESSURES THAN THE ZONES IN THE LOWER PORTION OF SAID COLUMN, WITHDRAWING A FATTY ACID FRACTION ABOVE SAID INTERMEDIATE ZONE, WITHDRAWING A LIQUID MIXTURE INCLUDING ROSIN ACIDS AND PITCH BELOW SAID INTERMEDIATE ZONE, FLASHING THE WITHDRAWN ROSIN ACIDS AND PITCH MIXTURE INTO A FLASH ZONE MAINTAINED AT A SUBSTANTIALLY LOWER PRESSURE THAN SAID COLUMN AT THE POINT OF WITHDRAWAL OF SAID ROSIN AND PITCH MIXTURE, THEREBY AT LEAST PARTIALLY VAPORIZING THE ROSIN ACIDS IN SAID ROSIN ACID AND PITCH MIXTURE, SUBJECTING THE UNVAPORIZED PORTION OF SAID ROSIN ACID AND PITCH MIXTURE TO THE STRIPPING ACTION OF STEAM TO VAPORIZE ADDITIONAL QUANTITIES OF ROSIN ACIDS, AND WITHDRAWING A VAPORIZED ROSIN ACID FRACTION FROM SAID FLASH ZONE HAVING A LOW CONTENT OF VOLATILE UNSAPONIFIABLES AND PITCH.