US4192708A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for controlling the addition of active chemical for delignifying and/or bleaching cellulose pulp suspended in a liquor containing chemicals reactive with the delignifying and/or bleaching chemical
Assignee: Mo och Domsjo AB
•
Filing: 1977-02-09
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Granted: 1980-03-11
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Expires: 1997-02-09
Abstract
Abstract A method is provided for controlling the addition of active chemical for delignifying and/or bleaching cellulose pulp suspended in an aqueous liquor containing at least one chemical reactive with such active chemical, which comprises determining the amount of active chemical consumed by the chemical reactive with the active chemical in the liquor; adding the active chemical to the cellulose pulp suspension; and then after a predetermined time interval determining the amount of active chemical consumed by the chemical and cellulose pulp reactive with the active chemical in the liquor; from these determinations determining the amount of active chemical consumed by the pulp; and then carrying out the delignification and/or bleaching with an amount of active chemical adjusted according to the amount of active chemical consumed by the pulp.
Inventors
- 👤 John R. Bergstrom
- 👤 Bengt G. Hultman
- 👤 Astrid T. P. Dalborg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:09
CPC Classifications
D; D21; D21C; D21C3/00; D21C3/22; D21C3/228; D21C9/00; D21C9/10; D21C9/1026; Y; Y10; Y10S; Y10S162/00; Y10S162/09; Y10S162/10
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
168 words
A process for controlling the addition of delignifying chemical for delignifying cellulose pulp suspended in an aqueous liquor containing spent chemical other than the cellulose pulp that is reactive with such delignifying chemical, which comprises determining firstly prior to the addition of delignifying chemical the amount of delignifying chemical consumed by the chemical reactive with the delignifying chemical in the liquor in the absence of the cellulose pulp; adding a known amount of the delignifying chemical to the cellulose pulp suspension, and then, during the delignification after a predetermined time interval following addition of the delignifying chemical to the cellulose pulp suspension, determining secondly in the absence of cellulose pulp fibers the residual amount of delignifying chemical in the liquor; from these first and second determinations and the known amount of delignifying chemical determining the amount of delignifying chemical consumed by the pulp; and then adding an amount of delignifying chemical adjusted according to the amount of delignifying chemical consumed by the pulp, and carrying out the delignification.
Claim 2
Dependent Claim
168 words
A process for controlling the addition of delignifying chemical for delignifying cellulose pulp suspended in an aqueous liquor containing spent chemical other than the cellulose pulp that is reactive with such delignifying chemical, which comprises determining firstly prior to the addition of delignifying chemical the amount of delignifying chemical consumed by the chemical reactive with the delignifying chemical in the liquor in the absence of the cellulose pulp; adding a known amount of the delignifying chemical to the cellulose pulp suspension, and then, during the delignification after a predetermined time interval following addition of the delignifying chemical to the cellulose pulp suspension, determining secondly in the absence of cellulose pulp fibers the residual amount of delignifying chemical in the liquor; from these first and second determinations and the known amount of delignifying chemical determining the amount of delignifying chemical consumed by the pulp; and then adding an amount of delignifying chemical adjusted according to the amount of delignifying chemical consumed by the pulp, and carrying out the delignification.
Claim 3
Dependent Claim
18 words
A process according to claim 1 in which each determination is made on samples of the suspending liquor.
Claim 4
Dependent Claim
43 words
A process according to claim 2 in which a sample of the suspending liquor is taken within a few seconds after addition of the delignifying chemical thereto, for the determination of the amount of delignifying chemical consumed by the chemical and cellulose pulp.
Claim 5
Dependent Claim
41 words
A process according to claim 2 in which a sample of the suspending liquor is taken a predetermined time interval within the range from a few seconds to about 10 hours after the delignifying chemical has been added to the liquor.
Claim 6
Dependent Claim
23 words
A process according to claim 4 in which the time interval is within the range from about 30 seconds to about 10 hours.
Claim 7
Dependent Claim
23 words
A process according to claim 2 in which a sample of the suspending liquor is taken at the conclusion of a delignification stage.
Claim 8
Dependent Claim
35 words
A process according to claim 1 in which the results of the determination are used to adjust the amount of delignifying chemical in the delignification stage in which the first and second determinations are made.
Claim 9
Dependent Claim
41 words
A process according to claim 1 in which the results of the determination are used to adjust the amount of delignifying chemical in any of the subsequent delignification stages following the stage in which the first and second determinations are made.
Claim 10
Dependent Claim
23 words
A process according to claim 1, in which at least one delignifying chemical is added to the pulp, and permitted to react therewith.
Claim 11
Dependent Claim
22 words
A process according to claim 1, in which an aqueous alkali is added to the pulp, to dissolve lignin from the pulp.
Claim 12
Dependent Claim
42 words
A process according to claim 1, in which the cellulose pulp is a chemical pulp from wood which has been digested by means of a chemical process selected from the group consisting of sulphite, sulphate, oxygen gas-alkali, bisulphite and soda cooking processes.
Claim 13
Dependent Claim
29 words
A process according to claim 11, in which the chemical pulp has a lignin content corresponding to a Kappa number within the range from about 100 to about 5.
Claim 14
Dependent Claim
23 words
A process according to claim 1, in which the cellulose pulp is selected from the group consisting of semichemical, mechanical, and thermomechanical pulps.
Claim 15
Dependent Claim
13 words
A process according to claim 1, in which the delignifying chemical is chlorine.
Claim 16
Dependent Claim
14 words
A process according to claim 1, in which the delignifying chemical is chlorine dioxide.
Claim 17
Dependent Claim
19 words
A process according to claim 1, in which the delignifying chemical is a mixture of chlorine and chlorine dioxide.
Claim 18
Dependent Claim
21 words
A process according to claim 16, in which chlorine and chlorine dioxide are added in a sequential manner in either order.
Claim 19
Dependent Claim
20 words
A process according to claim 1, in which the determination of the amount of delignifying chemical consumed is made calorimetrically.
Claim 20
Dependent Claim
168 words
A process for controlling the addition of bleaching chemical for bleaching cellulose pulp suspended in an aqueous liquor containing spent chemical other than the cellulose pulp that is reactive with such bleaching chemical, which comprises determining firstly prior to the addition of the delignifying chemical the amount of bleaching chemical consumed by the chemical reactive with the bleaching chemical in the liquor in the absence of the cellulose pulp; adding a known amount of bleaching chemical to the cellulose pulp suspension; and then, during the delignification after a predetermined time interval following addition of the bleaching chemical to the cellulose pulp suspension, determining secondly in the absence of cellulose pulp fibers the residual amount of bleaching chemical in the liquor; from these first and second determinations and the known amount of bleaching chemical determining the amount of bleaching chemical consumed by the pulp; and then adding an amount of bleaching chemical adjusted according to the amount of bleaching chemical consumed by the pulp, and carrying out the bleaching.
Claim 21
Dependent Claim
168 words
A process for controlling the addition of bleaching chemical for bleaching cellulose pulp suspended in an aqueous liquor containing spent chemical other than the cellulose pulp that is reactive with such bleaching chemical, which comprises determining firstly prior to the addition of the delignifying chemical the amount of bleaching chemical consumed by the chemical reactive with the bleaching chemical in the liquor in the absence of the cellulose pulp; adding a known amount of bleaching chemical to the cellulose pulp suspension; and then, during the delignification after a predetermined time interval following addition of the bleaching chemical to the cellulose pulp suspension, determining secondly in the absence of cellulose pulp fibers the residual amount of bleaching chemical in the liquor; from these first and second determinations and the known amount of bleaching chemical determining the amount of bleaching chemical consumed by the pulp; and then adding an amount of bleaching chemical adjusted according to the amount of bleaching chemical consumed by the pulp, and carrying out the bleaching.
Claim 22
Dependent Claim
18 words
A process according to claim 19 in which each determination is made on samples of the suspending liquor.
Claim 23
Dependent Claim
43 words
A process according to claim 20 in which a sample of the suspending liquor is taken within a few seconds after addition of the bleaching chemical thereto, for the determination of the amount of bleaching chemical consumed by the chemical and cellulose pulp.
Claim 24
Dependent Claim
41 words
A process according to claim 20 in which a sample of the suspending liquor is taken a predetermined time interval within the range from a few seconds to about 10 hours after the bleaching chemical has been added to the liquor.
Claim 25
Dependent Claim
35 words
A process according to claim 19 in which the results of the determination are used to adjust the amount of bleaching chemical in the bleaching stage in which the first and second determinations are made.
Claim 26
Dependent Claim
41 words
A process according to claim 19 in which the results of the determination are used to adjust the amount of bleaching chemical in any of the subsequent bleaching stages following the stage in which the first and second determinations are made.
Claim 27
Dependent Claim
23 words
A process according to claim 19 in which at least one bleaching chemical is added to the pulp, and permitted to react therewith.
Claim 28
Dependent Claim
22 words
A process according to claim 19 in which an aqueous alkali is added to the pulp, to dissolve lignin from the pulp.
Claim 29
Dependent Claim
42 words
A process according to claim 19 in which the cellulose pulp is a chemical pulp from wood which has been digested by means of a chemical process selected from the group consisting of sulphite, sulphate, oxygen gas-alkali, bisulphite and soda cooking processes.
Claim 30
Dependent Claim
29 words
A process according to claim 27 in which the chemical pulp has a lignin content corresponding to a Kappa number within the range from about 100 to about 5.
Claim 31
Dependent Claim
23 words
A process according to claim 19 in which the cellulose pulp is selected from the group consisting of semichemical, mechanical, and thermomechanical pulps.
Claim 32
Dependent Claim
13 words
A process according to claim 19, in which the bleaching chemical is chlorine.
Claim 33
Dependent Claim
14 words
A process according to claim 19 in which the bleaching chemical is chlorine dioxide.
Claim 34
Dependent Claim
19 words
A process according to claim 19 in which the bleaching chemical is a mixture of chlorine and chlorine dioxide.
Claim 35
Dependent Claim
21 words
A process according to claim 32 in which chlorine and chlorine dioxide are added in a sequential manner, in either order.
Claim 36
Dependent Claim
20 words
A process according to claim 19 in which the determination of the amount of bleaching chemical consumed is made calorimetrically.
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) | 1983-03-11 | 1983-09-10 | 1984-03-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-03-11 | 1987-09-10 | 1988-03-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-03-11 | 1991-09-10 | 1992-03-11 | $7700.00 | Window Closed / Lapsed |