Tod S Sloan

US Patent:

48865761, Dec 12, 1989

Filed:

Dec 16, 1987

Appl. No.:

7/134209

Inventors:

Tod H. Sloan - Battle Ground WA

Assignee:

Boise Cascade Corporation - Boise ID

International Classification:

D21B 114
D21C 712
D21D 130

US Classification:

162 49

Abstract:

A method and apparatus for producing uniform pulp yields, wherein at least a refiner is controlled in accordance with the UV absorbance of the lignin dissolved in the digester cooking liquor, thereby to produce for a given quantity of wood chips a uniform pulp yield. A backflow control valve is automatically adjusted to maintain uniform flow of a sample of the digester cooking liquor through a UV analyzer, and a flushing arrangement is provided for flushing out contaminates such as sulphur dioxide from the system. Preferably the refiner is of the two-stage type, the first stage being automatically adjusted as a function of the UV absorbance of the digester cooking liquor, and the second stage being automatically adjusted as a function of the freeness of the output fiber slurry. Also, one or more of the cooking parameters is controlled by the UV analyzer to control the fiber yield.