Abstract An improved system for the production of digested pulp from wood chips and knots which includes a separating apparatus, connected to the digester output, capable of separating knots from partially cooked wood chips and fibers at the digester pressure and consistency. The separated fibers and fiber bundles pass to a refiner where the fiber bundles are mechanically reduced to fibers in a liquid environment at a high consistency and at the digester pressure. The knots are then re-cycled to the digester or other processes. The process of digesting wood chips according to the present invention comprises immersing the wood chips and knots in a digesting liquor under a pressure of from about 150-250 PSIG in order to chemically reduce at least some of the wood chips to the constituent fibers. The wood chips and knots are washed then with water in order to separate the partially reduced wood chips fibers and knots from the digesting liquor and to form a pulp having a solid consistency of about 10-15 percent.
Inventors
👤 Oliver A Laakso
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-10-24 06:40
CPC Classifications
D; D21; D21D; D21D5/00; D21D5/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
126 words
A METHOD FOR DIGESTING WOOD CHIPS AND KNOTS COMPRISING: A. IMMERSING THE WOOD CHIPS AND KNOTS IN A DIGESTING LIQUOR UNDER PRESSURE OF FROM ABOUT 150-250 PSIG TO CHEMICALLY REDUCE AT LEAST SOME OF THE WOOD CHIPS TO THEIR CONSTITUENT FIBERS; B. WASHING THE WOOD CHIPS AND KNOTS WITH WATER TO SEPARATE THE PARTIALLY REDUCED WOOD CHIPS, FIBERS AND KNOTS FROM THE DIGESTING LIQUOR AND TO FORM A PRESSURIZED PULP COMPRISING WATER AND PARTIALLY REDUCED WOOD CHIPS, FIBERS AND KNOTS HAVING A SOLIDS CONSISTENCY OF ABOUT 10-15 PERCENT; C. SEPARATING THE PARTIALLY REDUCED WOOD CHIPS AND AT LEAST MOST OF THE FIBERS FROM THE KNOTS AT A SOLIDS CONSISTENCY OF ABOUT 10-15 PERCENT, AND D. PASSING THE PARTIALLY REDUCED WOOD CHIPS AND FIBERS TO SUBSEQUENT TREATMENT.
Claim 2
Independent Claim
126 words
A METHOD FOR DIGESTING WOOD CHIPS AND KNOTS COMPRISING: A. IMMERSING THE WOOD CHIPS AND KNOTS IN A DIGESTING LIQUOR UNDER PRESSURE OF FROM ABOUT 150-250 PSIG TO CHEMICALLY REDUCE AT LEAST SOME OF THE WOOD CHIPS TO THEIR CONSTITUENT FIBERS; B. WASHING THE WOOD CHIPS AND KNOTS WITH WATER TO SEPARATE THE PARTIALLY REDUCED WOOD CHIPS, FIBERS AND KNOTS FROM THE DIGESTING LIQUOR AND TO FORM A PRESSURIZED PULP COMPRISING WATER AND PARTIALLY REDUCED WOOD CHIPS, FIBERS AND KNOTS HAVING A SOLIDS CONSISTENCY OF ABOUT 10-15 PERCENT; C. SEPARATING THE PARTIALLY REDUCED WOOD CHIPS AND AT LEAST MOST OF THE FIBERS FROM THE KNOTS AT A SOLIDS CONSISTENCY OF ABOUT 10-15 PERCENT, AND D. PASSING THE PARTIALLY REDUCED WOOD CHIPS AND FIBERS TO SUBSEQUENT TREATMENT.
Claim 3
Dependent Claim
34 words
The method as recited in claim 1 wherein the subsequent treatment includes the step of mechanically reducing the partially reduced wood chips to their constituent fibers at a solids consistency of about 10-15 percent.
Claim 4
Dependent Claim
35 words
The method as recited in claim 1 further including the step of re-immersing the knots which have been separated in step c) in said digesting liquor to chemically reduce the knots to their constituent fibers.
Claim 5
Dependent Claim
48 words
The method as recited in claim 1 further including the steps of diluting the knots and fibers which have been separated from the partially reduced wood chips and fibers in step c) to a solids concentration less than 7 percent and then separating the knots from the fibers.
Claim 6
Dependent Claim
29 words
The method as recited in claim 4 further including the step of re-immersing the separated knots in the digesting liquor to chemically reduce the knots to their constituent fibers.
Claim 7
Dependent Claim
23 words
The method as recited in claim 5 further including the step of adding the separated fibers to the pulp formed in step b).
Claim 8
Dependent Claim
23 words
The method as recited in claim 1 wherein the steps a) through c) are carried out at a pressure of about 150-250 psig.