Importance

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Abstract

Low temperature steaming and slurrying of wood chips results in significant improvement in treatment, the chips being maintained at a temperature below 110.degree. C. (more desirably at about 105.degree. C. or less, and most desirably at about 100.degree. C. or less) until actually heated to cooking temperature. Steaming may be accomplished utilizing a vertical chip bin with one dimensional convergence and side relief or a horizontal steaming vessel, the steaming device connected to a high pressure feeder. A pump having an NPSHR less than the NPSHA may be used for drawing slurry into the high pressure feeder from the steaming device, or a pump may be disposed between the steaming device and the high pressure feeder for forcing slurry into the high pressure feeder through a conduit including a radiused elbow. The steaming is practiced at a pressure of 5 psig or less, preferably substantially atmospheric steaming is practiced. The pulp produced typically has strength properties at least about 10% greater than the pulp produced from material where it is steamed and slurried at temperatures in excess of 110.degree. C.

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First Claim