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Abstract

A method for recovering turpentine and heat in a TMP process in which woodchips are heated in a preheater and the vent vapors from the preheater are passed to the condensing vapor zone of an evaporator condenser-reboiler having a condensing vapor zone and a boiling liquid zone. A major portion of the vent vapors are condensed so as to produce a turpentine-lean condensate and turpentine-rich vapor phase. The turpentine-rich vapor phase is withdrawn from the evaporator and passed to a turpentine condenser where it is cooled by indirect heat exchange contact with a cooling liquid to produce a condensate containing immiscible turpentine and aqueous phases. The turpentine and the aqueous phases are separated. The aqueous phase and the condensate produced when vent vapors from the preheater are condensed are passed to the boiling liquid zone of the evaporator and brought into indirect heat exchange contact with the vent vapors from the preheater while maintaining a lower pressure in the boiling liquid zone than in the condensing vapor zone whereby a turpentine-lean vapor is produced. The turpentine-lean is used to presteam the woodchips before they are supplied to the heater.

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First Claim