US3881986A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing homogeneously delignified pulp from fibrous material, containing lignocellulose, in a digester partially filled with liquor
Assignee: Svenska Cellulosa AB
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Filing: 1971-06-04
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Granted: 1975-05-06
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Expires: 1991-06-04
Abstract
Abstract AN improved method is disclosed for impregnating lignocellulosic fibrous material in the cooking of pulp from wood chips in a digester partially filled with cooking liquor which is circulated through the digester for the purpose of obtaining a homogeneous delignification of the entire charge of chips within the digester, the improvement comprising conveying cooking liquor to the top of the digester, distributing the liquor substantially uniformly over substantially the entire cross-sectional area of the digester by means of at least one centrifugal pressure nozzle and subjecting the charge to pressure-impregnation by means of steam, the pressure being applied during the period in which the mixture is brought to cooking temperature but after the chips present at the top of the digester have been brought into contact with the cooking liquor, the circulation of the cooking liquor being stopped during the pressure-impregnation phase.
Inventors
- 👤 Sture Olof Erik Backlund
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 05:05
CPC Classifications
D; D21; D21C; D21C1/00; D21C1/10
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
23 words
IN A METHOD OF IMPREGNATING LIGNOCELLULOSE FIBROUS MATERIAL IN THE COOKING OF PULP FROM WOOD CHIPS IN A DIGESTER, THE IMPROVEMENT WHICH COMPRISES
Claim 2
Dependent Claim
23 words
IN A METHOD OF IMPREGNATING LIGNOCELLULOSE FIBROUS MATERIAL IN THE COOKING OF PULP FROM WOOD CHIPS IN A DIGESTER, THE IMPROVEMENT WHICH COMPRISES
Claim 3
Dependent Claim
33 words
INTRODUCING WOOD CHIPS AND A COOKING LIQUOR INTO A DIGESTER WITH THE VOLUME OF COOKING LIQUOR BEING LESS THAN THE VOLUME OF THE DIGESTER WHEREBY THERE IS A VAPOR SPACE ABOVE THE LIQUOR;
Claim 4
Dependent Claim
33 words
INTRODUCING WOOD CHIPS AND A COOKING LIQUOR INTO A DIGESTER WITH THE VOLUME OF COOKING LIQUOR BEING LESS THAN THE VOLUME OF THE DIGESTER WHEREBY THERE IS A VAPOR SPACE ABOVE THE LIQUOR;
Claim 5
Dependent Claim
36 words
CIRCULATING LIQUOR FROM THE BOTTOM OF THE DIGESTER TO THE TOP THEREOF AND THROUGH AT LEAST ONE CENTRIFUGAL NOZZLE THEREBY SPRAYING LIQUOR SUBSTANTIALLY UNIFORMLY OVER THE CHIPS THROUGHOUT SUBSTANTIALLY THE ENTIRE CROSS-SECTIONAL AREA OF THE DIGESTER;
Claim 6
Dependent Claim
36 words
CIRCULATING LIQUOR FROM THE BOTTOM OF THE DIGESTER TO THE TOP THEREOF AND THROUGH AT LEAST ONE CENTRIFUGAL NOZZLE THEREBY SPRAYING LIQUOR SUBSTANTIALLY UNIFORMLY OVER THE CHIPS THROUGHOUT SUBSTANTIALLY THE ENTIRE CROSS-SECTIONAL AREA OF THE DIGESTER;
Claim 7
Dependent Claim
36 words
circulating liquor from the bottom of the digester to the top thereof and through at least one centrifugal nozzle thereby spraying liquor substantially uniformly over the chips throughout substantially the entire cross-sectional area of the digester;
Claim 8
Dependent Claim
36 words
circulating liquor from the bottom of the digester to the top thereof and through at least one centrifugal nozzle thereby spraying liquor substantially uniformly over the chips throughout substantially the entire cross-sectional area of the digester;
Claim 9
Dependent Claim
21 words
A method according to claim 1, characterized in that the pressure-impregnation is carried out at the beginning of the cooking cycle.
Claim 10
Dependent Claim
5 words
stopping circulation of liquor; and
Claim 11
Dependent Claim
5 words
stopping circulation of liquor; and
Claim 12
Dependent Claim
5 words
STOPPING CIRCULATION OF LIQUOR; AND
Claim 13
Dependent Claim
5 words
STOPPING CIRCULATION OF LIQUOR; AND
Claim 14
Dependent Claim
50 words
A method according to claim 1, characterized in that only part of the required cooking liquor is conveyed to the top of the digester to the charge of chips through at least one centrifugal pressure nozzle, and separately introducing the rest of the cooking liquor to the charge of chips.
Claim 15
Dependent Claim
41 words
A method according to claim 3, characterized in that the cooking liquor supplied to the charge of chips through a centrifugal pressure nozzle is caused to leave the nozzle in a spray having an angle of spread of at least 50*.
Claim 16
Dependent Claim
43 words
THEREAFTER INTRODUCING STEAM INTO THE SPACE ABOVE THE LIQUOR AND CHIPS WHILE THE DIGESTER IS CLOSED THEREBY ELEVATING THE PRESSURE IN THE DIGESTER ABOVE ATMOSPHERIC PRESSURE WHILE SIMULTANEOUSLY HEATING THE CHIPS AND LIQUOR TO COOKING TEMPERATURE THEREBY IMPREGNATING LIQUOR WET CHIPS WITH LIQUOR.
Claim 17
Dependent Claim
43 words
THEREAFTER INTRODUCING STEAM INTO THE SPACE ABOVE THE LIQUOR AND CHIPS WHILE THE DIGESTER IS CLOSED THEREBY ELEVATING THE PRESSURE IN THE DIGESTER ABOVE ATMOSPHERIC PRESSURE WHILE SIMULTANEOUSLY HEATING THE CHIPS AND LIQUOR TO COOKING TEMPERATURE THEREBY IMPREGNATING LIQUOR WET CHIPS WITH LIQUOR.
Claim 18
Dependent Claim
43 words
thereafter introducing steam into the space above the liquor and chips while the digester is closed thereby elevating the pressure in the digester above atmospheric pressure while simultaneously heating the chips and liquor to cooking temperature thereby impregnating liquor wet chips with liquor.
Claim 19
Dependent Claim
43 words
thereafter introducing steam into the space above the liquor and chips while the digester is closed thereby elevating the pressure in the digester above atmospheric pressure while simultaneously heating the chips and liquor to cooking temperature thereby impregnating liquor wet chips with liquor.
Claim 20
Dependent Claim
22 words
A method according to claim 1, characterized in that the pressure-impregnation is carried out a plurality of times during the cooking cycle.
Claim 21
Dependent Claim
42 words
A method according to claim 1, characterized in that vapor present within the digester is heated up to such a high temperature as will generate a pressure exceeding the pressure produced by the prevailing average temperature of the contents of the digester.
Claim 22
Dependent Claim
44 words
A method according to claim 1, characterized in that the pressure-impregnation is carried out at an increase of presssure amounting to 0.1 - 10 kg/cm2, and that the impregnation is caused to take place for a period of time of up to 6 hours.
Claim 23
Dependent Claim
44 words
A method according to claim 1, characterized in that the pressure-impregnation is carried out at an increase of pressure amounting to 1-6 kg/cm2, and that the impregnation is caused to take place for a period of time of about 10 minutes to 1 hour.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-05 | 1978-11-04 | 1979-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-05 | 1982-11-04 | 1983-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-05 | 1986-11-04 | 1987-05-06 | $7700.00 | Window Closed / Lapsed |