CA1269806A - Method of enhancing the cooking of wood chips for pulp production - Google Patents
Method of enhancing the cooking of wood chips for pulp productionInfo
- Publication number
- CA1269806A CA1269806A CA000504578A CA504578A CA1269806A CA 1269806 A CA1269806 A CA 1269806A CA 000504578 A CA000504578 A CA 000504578A CA 504578 A CA504578 A CA 504578A CA 1269806 A CA1269806 A CA 1269806A
- Authority
- CA
- Canada
- Prior art keywords
- chips
- compound
- liquor
- pulp
- added
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention is directed to the use of certain ethoxylated compounds to increase the yield of chemical pulping processes, the compound have the following structures:
The present invention is directed to the use of certain ethoxylated compounds to increase the yield of chemical pulping processes, the compound have the following structures:
Description
METHOD OF ENHANCING TUE COOKING
_ OF WOOD CHIPS FOR PULP PRODUCTION
Back round of the Invention The present invention relates to the production of woo~ pulp by the sulfate pulp process. The technology and objectives of the present invention are described in detail in U.S. Patent 3,909,34 The '345 patent discusses and claims t~e ~se of surface active agents having the general formula R~(C2H40)n (C3H6o)m)]y as additives to sulfate cooking liquor aids for the purpose of obtaining higher yields of pulp from a given wood chip charge.
The agents permit a greater effectiveness of the cooking process relative to chips which prior to that invention were considered rejects and not pulpable.
As the patent describes, wood chips derived primarily from coniferous (cypress, balsam, firs of various varieties, pines, etc.) are charged to a cooking vessel on a dry-weight ~, basis and cooked for a predetermined time with a cooking liquor in a prescribed wood to liquor ratio (see Col. 2 of '345 patent).
The cooking liquor is composed of various concentrations (depending on the wood comprising the chips and type pulp to be made) of sodium hydroxide and sodium sulfide.
The "cook" takes place at elevated pressures and temperatures (200 - 500F) for periods ranging 1/2 to 10 hours.
The Present Invention While there is a great deal of similarity between the invention o~ the earliér referred to patent and that of the present inventors, the similarities cease as regards to the type surface active utilized.
The present invention utilizes surface active agents having the general structure HO(CH2CH20)a (CHCH20)b (CH2CH20)CH
wherein a, b, and c are at least 1 but are such to produce an agent having a molecular weight of 500 to 30,000 with those having a molecular weight of 1,000 to 10,000 being preferred.
As with the '345 patent, the present surface active agents or combination thereof may be added to the liquor prior to contact of such with the chips in an amount of 0.05 to 1%
(pref. 0.1 to 0O5%~ based upon the dry weight of the wood chips. The surface active agents used in accordance with the present invention are available from BASF Wyandotte Corp. under trade n~me~ such as Pluronic L-62, L-92 and F-108. The surface active agents have been found quite successful in cooking processes utilizing Southern Pine chips where a reject level S (i.e., pulp cannot be produced from the chips) of 5% or higher ~based on dry wood basis) is commonly experienced.
A product comprised of 10% Pluronic L-62 and 10% of Pluron;c F-108 was previously sold for the purpose (more than 1 year prior to the present inven~ion). Trials, however, - 10 u~ilizing this product were not successful for various reasons and accordingly discontinued. No benefits from the use of the product were observed. It was determined by the present inventors that while the concep~ had merit, it was improperly applied, i.e.~ it was applied to a cooking process utilizing chips where reject levels were not a problem since most, if not all, of chips were converted to pulp without difficulty.
~ t was not until the present inventors again arrived at the concept of utilizlng the technology in troublesome cooks that the benefits and advantages were experienced.
The present invention is particularly suitable in high yield pulp production (Kraft) utilizing Southern Pine chips.
This unbleached pulp is commonly used to produce grocery sacks and liner board. From the available literature re the Pluronics, it was determined that L-62 had a molecular weight composed of approximately 20% (CH2CH20) and approximately 80% (CH2CH20) and equaling approximately 2,188, æ~
-L-92 percentages were respectively about 20% and 80%
with mw of 3,440;
and F-108 had percentages of 80% and 20% with a molecular weight of 16,250.
As earlier intimated, in chemical pulping, the cooking is usually terminated when the amount of rejects in the pulp is reduced to an acceptable level. Substantial yield and quality advantages can be obtained when chips are cooked to a higher liquid content. As a result, an increase in Kappa No. target by the use of thinner chips can achieve a substantial cost savings.
However the thickness of chips produced on commercial scale is always quite variable3 and a major portion of the total rejects frequently originate from a relatively small fraction of the chips having the greatest thickness.
The obJective then of the present invention is to achieve a lower ratio of rejects by the addition of the subject surface active agents to the cooking liquor to enhance the uniform distribution of the cooking chemical and/or the removal of degraded materlals from within the chips, resulting in lower rejects and higher yields.
Experimental The following laboratory and mill studies and results demonstrate the effectiveness of certain surfactan~s and blends thereof as pulping additlves to cooking liquor.
" .
;9~6 Mill Study A product comprised on an active basis of an aqueous solution containing lO~ Pluronic L-62 and 7 l/2% Pluronic F-lOB
was tested. The mill produced Kraft pulp utilizing Southern Pine chips being cooked (pulped) at the following conditions Active Alkali = 1570 as Na20 in cooking liquor Sulfidi~y = 25% in cooking liquor Liquor/Wood Ratio = 7/l ~oven-dried chip weight basis) Cooking Tèmperature = 170~C
Time to 170C = 90 minutes Time at 170C = 36 minutes The procedure generally entails taking a sample of the wood chips to be cooked and oven drying such to determine its moisture content. The wood chips are fed to the cook (digester) on the bas~s of its dry weight. The wood chips are cooked with the liquor at the temperatures indicated in a closed vessel.
After the cook the pressure is released and the cooked pulp is screened and the percentage rejects determined (i.e., material retained on screen). Rejects percentage is determlned by first drying the material reta1ned on the screen and utiliz-ing that weight In conjunct~on with ~he dry weight of chips added to establish the percentage of material rejected.
Screened yield is determined in a like fashion.
The results of the mill study utilizing a dosage level of 0.10% product on oven-dried chip weight basis were as follows:
~ 6 9~3~
Treatment % Rejects Kappa No.*
Untreated (Pretrial) 12.4 92 Trea~ed 8.3 92 *Indicates equivalent cooking conditions during both the pretrial and trial studies.
Laboratory Studies The condition and procedures (were laboratory modifiers) of the Kraft pulp;ng process utilized in the foregoing mill study were repeated in ~he laboratory.
STUDY I: The pulping additive formulation was composed of an aqueous solution of 7.5% Pluronic L-62 and 7.5%
Pluronic F-108.
Dosage Level = 0.50% of formulation on oven-dr~ed (O.D.) chip weiyht basis.
Screened Yie1d Rejects Results(% of OD Chips) (% of OD Chips) Untreated 39.6 20.5 Treated 45.6 15.7 -~69~306 Study II:
Pulping Addi~ive: 100% Pluronic L-92 Dosage Level: 0.075% 90D chip weight basis) % Screened Yield % Rejects Results As in S~udy I As In Study I
Untreated 46.2 9,4 Treated 48.9. 4.0 Whereas we have shown and described herein certain embodiments of the present invention, it is intended that there be covered as well any change or modification therein which may be made without departing from the spirit and scope of the invention.
,
_ OF WOOD CHIPS FOR PULP PRODUCTION
Back round of the Invention The present invention relates to the production of woo~ pulp by the sulfate pulp process. The technology and objectives of the present invention are described in detail in U.S. Patent 3,909,34 The '345 patent discusses and claims t~e ~se of surface active agents having the general formula R~(C2H40)n (C3H6o)m)]y as additives to sulfate cooking liquor aids for the purpose of obtaining higher yields of pulp from a given wood chip charge.
The agents permit a greater effectiveness of the cooking process relative to chips which prior to that invention were considered rejects and not pulpable.
As the patent describes, wood chips derived primarily from coniferous (cypress, balsam, firs of various varieties, pines, etc.) are charged to a cooking vessel on a dry-weight ~, basis and cooked for a predetermined time with a cooking liquor in a prescribed wood to liquor ratio (see Col. 2 of '345 patent).
The cooking liquor is composed of various concentrations (depending on the wood comprising the chips and type pulp to be made) of sodium hydroxide and sodium sulfide.
The "cook" takes place at elevated pressures and temperatures (200 - 500F) for periods ranging 1/2 to 10 hours.
The Present Invention While there is a great deal of similarity between the invention o~ the earliér referred to patent and that of the present inventors, the similarities cease as regards to the type surface active utilized.
The present invention utilizes surface active agents having the general structure HO(CH2CH20)a (CHCH20)b (CH2CH20)CH
wherein a, b, and c are at least 1 but are such to produce an agent having a molecular weight of 500 to 30,000 with those having a molecular weight of 1,000 to 10,000 being preferred.
As with the '345 patent, the present surface active agents or combination thereof may be added to the liquor prior to contact of such with the chips in an amount of 0.05 to 1%
(pref. 0.1 to 0O5%~ based upon the dry weight of the wood chips. The surface active agents used in accordance with the present invention are available from BASF Wyandotte Corp. under trade n~me~ such as Pluronic L-62, L-92 and F-108. The surface active agents have been found quite successful in cooking processes utilizing Southern Pine chips where a reject level S (i.e., pulp cannot be produced from the chips) of 5% or higher ~based on dry wood basis) is commonly experienced.
A product comprised of 10% Pluronic L-62 and 10% of Pluron;c F-108 was previously sold for the purpose (more than 1 year prior to the present inven~ion). Trials, however, - 10 u~ilizing this product were not successful for various reasons and accordingly discontinued. No benefits from the use of the product were observed. It was determined by the present inventors that while the concep~ had merit, it was improperly applied, i.e.~ it was applied to a cooking process utilizing chips where reject levels were not a problem since most, if not all, of chips were converted to pulp without difficulty.
~ t was not until the present inventors again arrived at the concept of utilizlng the technology in troublesome cooks that the benefits and advantages were experienced.
The present invention is particularly suitable in high yield pulp production (Kraft) utilizing Southern Pine chips.
This unbleached pulp is commonly used to produce grocery sacks and liner board. From the available literature re the Pluronics, it was determined that L-62 had a molecular weight composed of approximately 20% (CH2CH20) and approximately 80% (CH2CH20) and equaling approximately 2,188, æ~
-L-92 percentages were respectively about 20% and 80%
with mw of 3,440;
and F-108 had percentages of 80% and 20% with a molecular weight of 16,250.
As earlier intimated, in chemical pulping, the cooking is usually terminated when the amount of rejects in the pulp is reduced to an acceptable level. Substantial yield and quality advantages can be obtained when chips are cooked to a higher liquid content. As a result, an increase in Kappa No. target by the use of thinner chips can achieve a substantial cost savings.
However the thickness of chips produced on commercial scale is always quite variable3 and a major portion of the total rejects frequently originate from a relatively small fraction of the chips having the greatest thickness.
The obJective then of the present invention is to achieve a lower ratio of rejects by the addition of the subject surface active agents to the cooking liquor to enhance the uniform distribution of the cooking chemical and/or the removal of degraded materlals from within the chips, resulting in lower rejects and higher yields.
Experimental The following laboratory and mill studies and results demonstrate the effectiveness of certain surfactan~s and blends thereof as pulping additlves to cooking liquor.
" .
;9~6 Mill Study A product comprised on an active basis of an aqueous solution containing lO~ Pluronic L-62 and 7 l/2% Pluronic F-lOB
was tested. The mill produced Kraft pulp utilizing Southern Pine chips being cooked (pulped) at the following conditions Active Alkali = 1570 as Na20 in cooking liquor Sulfidi~y = 25% in cooking liquor Liquor/Wood Ratio = 7/l ~oven-dried chip weight basis) Cooking Tèmperature = 170~C
Time to 170C = 90 minutes Time at 170C = 36 minutes The procedure generally entails taking a sample of the wood chips to be cooked and oven drying such to determine its moisture content. The wood chips are fed to the cook (digester) on the bas~s of its dry weight. The wood chips are cooked with the liquor at the temperatures indicated in a closed vessel.
After the cook the pressure is released and the cooked pulp is screened and the percentage rejects determined (i.e., material retained on screen). Rejects percentage is determlned by first drying the material reta1ned on the screen and utiliz-ing that weight In conjunct~on with ~he dry weight of chips added to establish the percentage of material rejected.
Screened yield is determined in a like fashion.
The results of the mill study utilizing a dosage level of 0.10% product on oven-dried chip weight basis were as follows:
~ 6 9~3~
Treatment % Rejects Kappa No.*
Untreated (Pretrial) 12.4 92 Trea~ed 8.3 92 *Indicates equivalent cooking conditions during both the pretrial and trial studies.
Laboratory Studies The condition and procedures (were laboratory modifiers) of the Kraft pulp;ng process utilized in the foregoing mill study were repeated in ~he laboratory.
STUDY I: The pulping additive formulation was composed of an aqueous solution of 7.5% Pluronic L-62 and 7.5%
Pluronic F-108.
Dosage Level = 0.50% of formulation on oven-dr~ed (O.D.) chip weiyht basis.
Screened Yie1d Rejects Results(% of OD Chips) (% of OD Chips) Untreated 39.6 20.5 Treated 45.6 15.7 -~69~306 Study II:
Pulping Addi~ive: 100% Pluronic L-92 Dosage Level: 0.075% 90D chip weight basis) % Screened Yield % Rejects Results As in S~udy I As In Study I
Untreated 46.2 9,4 Treated 48.9. 4.0 Whereas we have shown and described herein certain embodiments of the present invention, it is intended that there be covered as well any change or modification therein which may be made without departing from the spirit and scope of the invention.
,
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of improving the chip cooking process of Southern Pine wood chips to produce unbleached Kraft pulp which ordinarily possesses a relatively high reject level of pulp in the range of 5% and above which comprises adding to the liquor utilized in the cooking process a sufficient amount for the purpose of at least one water soluble compound having the general formula wherein a, b, and c are each at least 1 and are such as to provide the compound with a molecular weight of about 500 or higher.
2. The method according to Claim 1 wherein a, b, and c are such as to provide said compound with a molecular weight of from about 500 to about 30,000.
3. The method according to Claim 2 wherein a, b, and c are such as to provide said compound with a molecular weight of from 1,000 to 10,000.
4. The method according to Claim 1 wherein said compound is added to said liquor prior to contact of said liquor with said chips.
5. The method according to Claim 4 wherein said compound is added in an amount from about 0.05 to 1 percent of the dry weight of said chips.
6. The method according to Claim 5 wherein said compound is added in an amount from about 0.1 to 0.5 percent of the dry weight of said chips.
7. A method of improving the chip cooking process of Southern Pine wood chips to produce unbleached Kraft pulp which ordinarily possesses a relatively high reject level of pulp in the range of 5% and above which comprises adding to the liquor utilized in the cooking process an effective amount of a surface active agent having the formula wherein a, b, and c have values such that said agent has a molecular weight of from about 500 to about 30,000 and such that (CH2CH2O) comprises from about 20 to 80 weight percent of said agent, thereby increasing the pulp yield.
8. The method according to Claim 7 wherein a, b, and c have values such that said agent has a molecular weight of from 1,000 to 10,000.
9. The method according to Claim 7 wherein said agent is added to said liquor prior to contact of said liquor with said chips.
10. The method according to Claim 9 wherein said compound is added in an amount from about 0.05 to 1 percent of the dry weight of said chips.
11. The method according to Claim 10 wherein said compound is added in an amount from about 0.1 to 0.5 percent of the dry weight of said chips.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US745,759 | 1985-06-17 | ||
| US6510387A | 1987-06-26 | 1987-06-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1269806A true CA1269806A (en) | 1990-06-05 |
Family
ID=22060360
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000504578A Expired CA1269806A (en) | 1985-06-17 | 1986-03-20 | Method of enhancing the cooking of wood chips for pulp production |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU624941B2 (en) |
| CA (1) | CA1269806A (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1209352B (en) * | 1980-09-22 | 1989-07-16 | Nardi Franco | PROCESS FOR THE PRODUCTION OF CHEMICAL CELLULOSE AND / OR PAPER PASTES, AS WELL AS THE PLANT AND ITS COMPONENTS FOR THE IMPLEMENTATION OF THE INDICATED PROCESS |
| US5053108A (en) * | 1989-06-28 | 1991-10-01 | Kamyr Ab | High sulfidity cook for paper pulp using black liquor sulfonization of steamed chips |
-
1986
- 1986-03-20 CA CA000504578A patent/CA1269806A/en not_active Expired
-
1990
- 1990-04-18 AU AU53647/90A patent/AU624941B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU5364790A (en) | 1991-10-24 |
| AU624941B2 (en) | 1992-06-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |