Unformatted text preview: mmon method employs a series of countercurrent vacuum drum washers to provide the displacement of the liquor with minimum dilution. Aim is to: minimize black liquor carryover recover dissolved solids
8 Brown Stock Washing
Rotary vacuum washers Drum washers with wire-mesh covered cylinder Drop leg of pipe supplies the washer with a vacuum As the drum contacts the slurry, a vacuum is applied to thicken the stock Typical configuration: 3-4 washers Continuous, wire countercurrent washer
9 Fibers After Pulping & Washing 10 Chemical Nomenclature
Delignification: breaking down the chemical structure of lignin Kappa number: measure of the lignin content in the pulp Pulp viscosity: measure of the average chain length of cellulose (DP- degree of polymerization) Fiber Liberation Point: (130-180C) occurs when sufficient lignin has been removed during pulping- chips are broken apart into fibers with little or no mechanical action. Full chemical...
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- Fall '08
- lignin, Pulp and paper industry, Papermaking, Kraft process, Brown Stock Washing