CA2221619A1 - Modified organosolv pulping - Google Patents
Modified organosolv pulping Download PDFInfo
- Publication number
- CA2221619A1 CA2221619A1 CA002221619A CA2221619A CA2221619A1 CA 2221619 A1 CA2221619 A1 CA 2221619A1 CA 002221619 A CA002221619 A CA 002221619A CA 2221619 A CA2221619 A CA 2221619A CA 2221619 A1 CA2221619 A1 CA 2221619A1
- Authority
- CA
- Canada
- Prior art keywords
- pulp
- cooking
- alcohol
- pulping
- plant materials
- 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.)
- Abandoned
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/20—Pulping cellulose-containing materials with organic solvents or in solvent environment
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
- D21C3/222—Use of compounds accelerating the pulping processes
Abstract
A method and apparatus for producing pulp (95) from fibrous plant materials (10). The method comprises the step of pulping (100) the fibrous material with a cooking solvent of a lower aliphatic alcohol and an additive mixture comprising at least one additive selective from the group consisting of sulfite salts, bisulfite salts and caustic.
Description
CA 02221619 1997-12-0~
W096/41052 PCTAUS~6/09~12 MODIFIED ORGANOSOLV PULPING
~ BACKGROUND OF 1~ INVENTION
Current envir~nm~nt~l concerns dictate the production of pulp with a low kappa number with a re-sulting decrease in the amount of bleaching chemicals used to bleach the pulp. In the case of kraft hardwood pulps, kappa numbers are obt~in~ in the range of from about 12 to 20. Alternatively, in the case of organosolv pulps obt~;n~ with an autocatalyzed organosolv pulping process such as the ALCELLR process as described in Lora et al. in U.S. Patent No. 4,764,596 or Diebold et al.
in U.S. Patent No. 4,100,016, kappa numbers are obt~;n~
typically in the range of from about 20 to 30 with pulping of mixtures of North American hardwoods of about 50~ maple, 35~ birch and 15~ poplar. Generally, organosolv pulps have superior bleachability due, among other reasons, to the structure of residual lignin and the low metal content of the pulp which results in a highly selective response to alkaline extraction and/or oxygen delignification and other bleaching chemicals.
This results in a reduction o~ kappa number and brightening without significant subsequent strength losses. For certain wood species and feedstocks, however, the conditions needed for achievlng bleachable level kappa numbers may lead to a decrease in strength.
As a result even though selective delignification and brightening are performed, the pulp strength properties of the final bleached product may be lower than optimum.
In the case of autocatalyzed organosolv pulping o~ dense hardwoods such as, for example, maple, the cooking conditions resulting in kappa numbers in the range of ~rom about 40 to 50 are relatively severe. Such -CA 0222l6l9 l997-l2-0~
W O 96/41052 PCT~US~6/0~912 --2~
cooking conditions generally can cause deterioration of pulp strength. Similarly, with softwoods such, as ~or ~mr~e, pine or spruce, similar kappa numbers are obt~; n~ under more severe conditions than with dense hardwoods and bleachable pulps with lower pulp strength are obt~; n~, When for example sugarcane bagasse is pulped using autocatalyzed organosolv pulping, pulping can be stopped at a kappa number above 50 to prevent fiber degradation. Pulping is then followed by alkaline extraction in order for the kappa number to reach a bleachable level at a kappa number o~ from about 15 to about 35.
Schroeter et al. in "Possible Lignin Reactions in the Organoceil Pulping Process", Tappi Journal, pages 197-200, 1991 propose a two stage organosolv pulping process in which the first stage is an acid stage and in excess of 20~ caustic by weight on wood is added in the second stage. This two stage organosolv pulping process was found to be impractical in cont;n~lous, industrial scale operations. (Tappi Pulping Conference Proceedings, Orlando, Florida, November 1991).
Marton et al. in PCT Int. App. No. WO 82 01,568 propose the use of ethanol in alkaline pulping at 20~ NaOH by weight on wood, thus producing soi~twood pulps with improved properties as compared with pulps produced using soda or alcohol pulping separately.
These ethanol pulps were poor compared with softwood kraft pulps in terms of strength and deligni~ication.
Valladares et al. in "Pulping of Sugarcane Bagasse with a mixture of Ethanol-Water Solution in Presence of Sodium Hydroxide and Anthra~; none", Progress Report No. 15, Tappi Press, pp. 23-28 (1984) _ CA 02221619 1997-12-0~
W O96/41052 PCT~US36/0~9~2 propose the addition of small quantities of sodium hy-droxide to a mixture o~ about 60~ to 40~ ethanol-water by weight and the addition of a small amount of anthra~l;n~n~ using sugarcane bagasse as raw material.
Ahmed et al. in "Steam Explosion Cooking of Aspen Pretreated with Methanol-Water/Alkaline Water", Forest Product Symposium, 1989 San Francisco 1989/1990 Chicago propose the use of steam explosion pulping process including the pretreatment of aspen chips with methanol-water/alkaline water solution cont~;ning ~rom about 0~ to 8~ sodium hydroxide. High kappa number pulps are produced that resemble chemithermomechanical pulps and are not fully bleachable.
Patt et al. in "Lignin and Carbohydrate Reac-tions in Alkaline Sulfite, Anthra~l;non~, Methanol Pulp-ing", 6th ISWPC, pages 609-617 propose the use of more than 5~ caustic, more than 30~ sulfite and catalytic amounts of anthra~l;n~ in a solvent with 15~ methanol.
The pulps produced have good physical properties such as ~uality, yield and bleachability. However, the multitude of chemicals used necessitates the use of elaborate processes for chemical and solvent recovery.
Bublitz et al. in "The role of Methanol in a Methanol Acid Sulfite Pulping Process", Pulping Confer-ence, pp. 423-427, 1983, propose the addition of methanol to an acid sul~ite pulping process. The total pulping time is reduced from 5 to 6 hours to 1 hour or less. The wood carbohydrates are less degraded which re-sults in high pulp yields of about 60~ to about 65~.
The fiber strength obtained was lower than that of kraft pulps. Furthermore, very high levels of -SO2 were consumed in the process.
-CA 02221619 l997-l2-0~
W096/41052 PCTAUS~6/09~12 MODIFIED ORGANOSOLV PULPING
~ BACKGROUND OF 1~ INVENTION
Current envir~nm~nt~l concerns dictate the production of pulp with a low kappa number with a re-sulting decrease in the amount of bleaching chemicals used to bleach the pulp. In the case of kraft hardwood pulps, kappa numbers are obt~in~ in the range of from about 12 to 20. Alternatively, in the case of organosolv pulps obt~;n~ with an autocatalyzed organosolv pulping process such as the ALCELLR process as described in Lora et al. in U.S. Patent No. 4,764,596 or Diebold et al.
in U.S. Patent No. 4,100,016, kappa numbers are obt~;n~
typically in the range of from about 20 to 30 with pulping of mixtures of North American hardwoods of about 50~ maple, 35~ birch and 15~ poplar. Generally, organosolv pulps have superior bleachability due, among other reasons, to the structure of residual lignin and the low metal content of the pulp which results in a highly selective response to alkaline extraction and/or oxygen delignification and other bleaching chemicals.
This results in a reduction o~ kappa number and brightening without significant subsequent strength losses. For certain wood species and feedstocks, however, the conditions needed for achievlng bleachable level kappa numbers may lead to a decrease in strength.
As a result even though selective delignification and brightening are performed, the pulp strength properties of the final bleached product may be lower than optimum.
In the case of autocatalyzed organosolv pulping o~ dense hardwoods such as, for example, maple, the cooking conditions resulting in kappa numbers in the range of ~rom about 40 to 50 are relatively severe. Such -CA 0222l6l9 l997-l2-0~
W O 96/41052 PCT~US~6/0~912 --2~
cooking conditions generally can cause deterioration of pulp strength. Similarly, with softwoods such, as ~or ~mr~e, pine or spruce, similar kappa numbers are obt~; n~ under more severe conditions than with dense hardwoods and bleachable pulps with lower pulp strength are obt~; n~, When for example sugarcane bagasse is pulped using autocatalyzed organosolv pulping, pulping can be stopped at a kappa number above 50 to prevent fiber degradation. Pulping is then followed by alkaline extraction in order for the kappa number to reach a bleachable level at a kappa number o~ from about 15 to about 35.
Schroeter et al. in "Possible Lignin Reactions in the Organoceil Pulping Process", Tappi Journal, pages 197-200, 1991 propose a two stage organosolv pulping process in which the first stage is an acid stage and in excess of 20~ caustic by weight on wood is added in the second stage. This two stage organosolv pulping process was found to be impractical in cont;n~lous, industrial scale operations. (Tappi Pulping Conference Proceedings, Orlando, Florida, November 1991).
Marton et al. in PCT Int. App. No. WO 82 01,568 propose the use of ethanol in alkaline pulping at 20~ NaOH by weight on wood, thus producing soi~twood pulps with improved properties as compared with pulps produced using soda or alcohol pulping separately.
These ethanol pulps were poor compared with softwood kraft pulps in terms of strength and deligni~ication.
Valladares et al. in "Pulping of Sugarcane Bagasse with a mixture of Ethanol-Water Solution in Presence of Sodium Hydroxide and Anthra~; none", Progress Report No. 15, Tappi Press, pp. 23-28 (1984) _ CA 02221619 1997-12-0~
W O96/41052 PCT~US36/0~9~2 propose the addition of small quantities of sodium hy-droxide to a mixture o~ about 60~ to 40~ ethanol-water by weight and the addition of a small amount of anthra~l;n~n~ using sugarcane bagasse as raw material.
Ahmed et al. in "Steam Explosion Cooking of Aspen Pretreated with Methanol-Water/Alkaline Water", Forest Product Symposium, 1989 San Francisco 1989/1990 Chicago propose the use of steam explosion pulping process including the pretreatment of aspen chips with methanol-water/alkaline water solution cont~;ning ~rom about 0~ to 8~ sodium hydroxide. High kappa number pulps are produced that resemble chemithermomechanical pulps and are not fully bleachable.
Patt et al. in "Lignin and Carbohydrate Reac-tions in Alkaline Sulfite, Anthra~l;non~, Methanol Pulp-ing", 6th ISWPC, pages 609-617 propose the use of more than 5~ caustic, more than 30~ sulfite and catalytic amounts of anthra~l;n~ in a solvent with 15~ methanol.
The pulps produced have good physical properties such as ~uality, yield and bleachability. However, the multitude of chemicals used necessitates the use of elaborate processes for chemical and solvent recovery.
Bublitz et al. in "The role of Methanol in a Methanol Acid Sulfite Pulping Process", Pulping Confer-ence, pp. 423-427, 1983, propose the addition of methanol to an acid sul~ite pulping process. The total pulping time is reduced from 5 to 6 hours to 1 hour or less. The wood carbohydrates are less degraded which re-sults in high pulp yields of about 60~ to about 65~.
The fiber strength obtained was lower than that of kraft pulps. Furthermore, very high levels of -SO2 were consumed in the process.
-CA 02221619 l997-l2-0~
2 PCTAUS~6~'ug~12 Chen et al. in "Pulp Characteristics and Mill Economics for a Conc~ptual SO2-Ethanol-Water Mill~
Solvent Pulping Conference, pages 663-671, 1990, propose the use of an alkali pretreatment of wood prior to the SO2-ethanol-water pulping. The pretreatment process was a vacuum impregnation of wood chips in aqueous ethanol with the presence o~ sodium hydroxide. The two-stage organosolv process produced softwood pulps with about 6~
to about 10~ higher yield than kraft and single-stage organosolv pulps. The pretreatment process also caused a reduction of kappa number by around 6 units as compared to the single-stage organosolv pulping. The pulps have lower strength than kraft pulps, particularly in regard to tear strength.
Primakov et al. in IlProcessing of Liquors after Pulping with Water-Alcohol Solutions", Khim. Drev.
(4) 23-5, 1982 propose the cooking of birchwood with SO2 in a 1:1 saturated alcohol-water mixture cont~in;ng 40 to 75~ spent sulfite liquor with a Kappa number of 20.8 to 25 and a breaking length of 4900 m to 5500 m The addition of spent liquor reduces the consumption of alcohol in cooking.
Sakai in "Organosolv Deligni~ication", Shipa Gikyo Shi, Vol. 48, No. 8, pp. 11-20 (1994) discloses the addition of bisulfite to the isopropyl alcohol-water solvent system. Large amounts of additive are used, for example 18~ magnesium bisulfite, at 165~C for cooking times o~ an hour. They have obtained pulps with high kappa numbers and their product is a semichemical pulp rather than a ~ully bleachable chemical pulp.
CA 02221619 1997-12-0~
W 096/41052 PCT/U~ 12 SUMMARY ON THE INVENTION
It is an object of this invention to provide for a process for manufacturing pulp by pulping with a cooking solvent comprising an aqueous solution o~ a lower aliphatic alcohol and one or more additive. The additive is added in such small amounts that separate procesess for the recovery or regeneration of the additives are not required. One e~ample o~ such additives are bisulfite salts added with maple and mixed hardwoods in a range of from about 0.05~ to about 6~.
Another example are sulfite salts added to maple and mixed hardwoods in a range o~ ~rom about 0.05~ to about 6~. Sul~ite salts can be added singly to bagasse and jute in a range of from about 2~ to about 4~ or in combination with sodium hydroxide which can be added in a range of from about 1.3~ to 4~.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1, 2 and 3 are flow diagrams of the process of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention provides for a process of improving the selectivity of delignification and increasing the rate of delignification beyond that which is obt~; n~ with the autocatalyzed organosolv pulping process. Selectivity can be ~nh~nced by the addition of additives such sodium hydroxide, sodium sulfite, ;um and magnesium bisulfite, and sodium bisulfite to the cooking solvent. The cooking solvent can be ~ comprised of from about 30~ to about 92~ (by weight) of a water miscible lower aliphatic alcohol of 1 to 4 carbon atoms (e.g., methanol, ethanol, isopropanol or tert-butanol) and from about 8 to about 70~ water. The CA 0222l6l9 l997-l2-0~
W O 96/410~2 PCT~US~Gi~12 cooking solvent can be further comprised of recovered alcohol and alcohol/water filtrate from the process and if needed, a small amount of a strong water soluble acid, such as a mineral acid (e.g., hydrochloric, sul~uric, phosphoric or nitric acid) or an organic acid (e.g., oxalic acid, preferably acetic, formic or peroxy acids), or a small amount of a mineral salt. The resulting cooking liquor can be used to pulp a wide range of raw materials such as for example sugarcane bagasse, sugarcane rind chips, hardwood such as maple, birch, poplar, oak, ash, basswood as single species or in combination, jute, ~lax, straw, kenaf, reed, and so~twoods such as spruce and balsam ~ir mixtures.
Ble~h~hle pulps can be obtained with low kappa number, high pulp strength and high yields.
Improved pulping selectivity can be obt~;n~
with the additives of the invention. We believe that bisulfite additive may be causing partial sulfonation of the lignin present in the feedstock. Generally, sulfonation can block re~nn~n~ation reactions which are believed to interfere with the pulp reaching a very low kappa number. Additionally, the products o~ sulfonation are believed to act as surfactant and as such contribute to the ~ l~vdl of the organosolv lignin.
Furthermore, oxidation-reduction side reactions in the presence o~ sulfite and bisul~ite additives are believed to create a catalytic ef~ect. Generally, additives such as sulfite can cause the pH to rise with the net result that hydrolysis of the cellulose fraction can occur at a lower acidity and a higher retention o~ hemicellulose as evidenced by the higher viscosity and higher hemicellulose content of the pulp which is produced.
Generally, sul~ite and bisulfite can be added as sodium, magnesium or ~mmnn;um sulfites and bisulfites salts to a wide range of fibrous plant materials such as CA 02221619 1997-12-0~
W O 96/41052 PCT~US~6/09~2 softwoods, maple, flax, wheat straw and a mixture of hardwoods. Caustic can also be added singly or in combination with any of the sulfite or bisulfite salts.
The fibrous plant materials can be pulped in accordance with Diebold or as shown in Figure 1. With the addition of additives to the cooking solvent, more uni~orm pulp cooking can be obt~in~ with lower pulp screening rejects and pulp with a lower kappa number.
For P~m~le, bisulfite salts can be added to maple and mixed hardwoods, sugarcane residues such as sugarcane bagasse at a level of from about 0.05~ to about 6~ by weight on fibrous plant materials.
Bisulfites can be added to the cooking solvent comprising alcohol and water in a weight percent of from about 30~ to about 92~, preferably from about 40~ to about 55~. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1. With the Diebold process, primary extraction times can be of from about 45 minutes to about 210 minutes and at a temperature o~ ~rom about 190~C to about 200~C, from about 100~C to about 155~C for a secondary extraction and ~rom about 100~C to about 124~C for a tertiary extraction. The pH of the cooking li~uor during primary extraction is from about 5 to about 5.4. The resulting pulp obt~lne~ had a low kappa number and a high yield of deligni~ication.
In another preferred embodiment, sulfite addi-tives can be used in the pulping of jute, flax, reed, sugarcane residues, wheat straw, maple and mixed hardwoods. When maple and mixed hardwoods are pulped, the level of sulfite used is from about 0.05~ to about 6~ on a weight basis on feedstock. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1. With the Diebold CA 0222l6l9 l997-l2-0~
W O96/41052 PCT~US9G/09912 process, the sulfite can be added to the cooking solvent described above at the primary extraction stage. The duration of the primary extraction is from about 60 minutes to about 180 minutes and at a temperature of from about 175~C to about 204~C. The pH of the cooking liquor during extraction is from about 4.4 to about 6.3.
In another preferred embodiment, sulfite addi-tives alone or in combination with NaOH can be used in the pulping of bagasse. When used alone, the level of sulfite is from about 2~ to about 4~ on a weight basis on bagasse. When used alone, the level of caustic is from about 1.3~ to about 2.6~ on a weight basis on bagasse. Sulfite and caustic can be used in combination.
When the two additives are used in combination, the level of sulfite is from about 2~ to about 4~ and the level of caustic is from about 1.3~ to about 4~ and the level of each additive can be adjusted such that the pH
of the cooking liquor during the preheating step is in the alkaline range. The pH reaches a level of from about 6 to about 8 as the cooking liquor temperature reaches its m~ ml~m and becomes slightly acidic as the primary extraction progresses. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1.
Alternatively, sulfite additives alone or in combination with caustic can be used in the pulping o~
jute. When used alone, the level o~ sulfite is from about 2~ to about 4~ on a weight basis on jute. When used alone, the level of caustic is from about 1.3~ to about 2.6~ on a weight basis on jute. Sulfite and caustic can be used in combination. When the two additives are used in combination, the level of sul~ite is from about 2~ to about 4~ and the level of caustic is from about 1.3~ to about 4~ and the level of each CA 02221619 1997-12-0~
_g _ additive can be adjusted such that the pH of the cooking liquor during the preheating step is in the alkaline range. The pH re~ches a level of from about 6 to about 8 as the cooking liquor temperature reaches its m~; mllm and becomes slightly acidic as the primary extraction progresses. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1.
In another preferred embodiment, caustic can be used in the pulping of sugarcane residues, maple and mixed hardwoods in a range of from about 1.3~ to 2.6~.
The ~ibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1. With the Diebold process, the pH reaches a level of from about 5 to about 7.
The process of this invention is schematically shown in Figure 1. Fibrous plant materials 10 having a moisture level o~ from about 5~ to about 60~ can be steamed by ~eeding steam 20 into the plant materials in steaming equipment 15 to a temperature o~ in the range ~rom ambient to about 120~C. The materials are steamed ~or from about 0.5 minute to about 120 minutes to heat the materials and to remove any air which may be trapped therein.
Following steaming, the steamed materials are wetted with cooking solvent 30 described above and in-troduced in ~eeder 25. The materials in feeder 25 can be pressurized to ~rom about atmospheric to the pressure in impregnation vessel 45 or alternatively to the pressure in extractor 100.
Following ~eeding, the materials can be im-pregnated in impregnation vessel 45 with additives CA 02221619 1997-12-0~
W O 96/41052 PCTnU596/0~9~2 mixture 40. Additives mixture 40 can comprise cooking solvent 30 and any of the additives mentioned above mixed therein at the appropriate concentration level depending on the fibrous plant material being pulped. A
slurry can be obt~;ne~. The impregnation time is from about 1 minute to about 120 minutes and the materials are simultaneously heated to ~rom about 50~C to about 170~C. During the impregnation time, the slurry can be pressurized to the pressure in extractor 100.
The fibrous plant materials slurry from im-pregnation vessel 45 can be ~ed into extractor 100 and the slurry which typically comprises from about 5~ to about 20~ solids is pulped for from about 45 minutes to about 6 hours. The temperature in extractor 100 is from about the temperature in impregnation vessel 45 to about 205~C.
During pulping, a stream of spent li~uor 71 and a pulp slurry 75 can be withdrawn from extractor 100. Spent liquor 71 can be processed in liquor recovery e~lipmPnt 85 to yield lignin, co-products and alcohol.
Pulp slurry 75 can be processed in pulp recovery e~l;pmPnt 95 to yield pulp and alcohol.
The invention can be applied to both batch and continuous cooks. In the case of batch cooks, the steaming and feeding steps described above can be practiced in accordance with Diebold. A c~nt; nllOUS
process can be practiced in accordance with Figure 2 where steaming e~uipment 15 can be comprised o~ metering screw 32, ~irst rotary valve feeder 33, second rotary valve feeder 34 and chip sluice tank 65. In one embodiment, the fibrous plant materials can be pre-steamed in steaming bin 31 by injection of steam at atmospheric pressure. The plant materials are wetted and CA 02221619 1997-12-0~
W O96/41052 PCT~US96/09942 passed into metering screw 32 which can be positioned at an angle. The excess water ~rom the steam con~n.~ates in metering screw 32 can be L~.luved and the wet ~ibrous plant materials can be passed through a ~irst rotary valve feeder 33, heated in line 46 by direct steam injection at a temperature o~ from about 50~C to about 130~C and at a pressure o~ ~rom about 30 to about 100 psig. Line 46 can be equipped with a steam barrier which helps prevent backup o~ alcohol-cont~;n;ng vapors into rotary valve ~eeder 33. The steamed ~ibrous plant materials are passed through a second rotary valve ~eeder 34. The ~ibrous plant materials in chip sluice tank 65 can be mixed with cooking solvent 30 and recycle solvent 50 from impregnation vessel 45.
Following ~eeding, additive mixture 40 can be added and the fibrous plant materials can be impregnated in impregnation vessel 45. The slurry can be pressurized in impregnation vessel 45 to the operating pressure of extractor 100. The slurry now re~erred to as cooking mixture can enter extractor 100 at inlet 38, a liquid separator 101 regulates the ~low o~ the mixture into extractor 100. Excess cooking mixture liquid over~lows extractor 100 at outlet 39, is recycled through line 57 and pumped back into impregnation vessel 45. In a pre~erred embo~;m~nt, a mechanical separator 101 is uti-lized to accomplish the liquid separation as described above. Additionally, mechanical separator 101 is utilized to convey the slurry o~ ~ibrous plant materials into extractor 100 in a m~nn~ which maintains the ~ree ~low o~ excess cooking mixture liquid. Further, mechanical separator 101 comprises movable screens to allow the adjustment o~ the position o~ such screens in mechanical separator 101 inside and relative to the top o~ extractor 100, as may be desirable, in view o~ the , CA 0222l6l9 l997-l2-0~
W O96/41052 PCT~US~6/09912 ~ibrous materials to be pulped and the pulping conditions in extractor 100.
Alternatively, as the excess cooking mixture liquid over~lows extractor 100 at outlet 39, it is re-cycled through line 57. The cooking mixture liquid passes through liquid surge tank 68. Liquid surge tank 68 is equipped with a level indicator and controls the over~low level o~ the cooking mixture liquid. Liquid surge tank 68 can separate any noncon~n~able gases ~rom the cooking mixture and can be equipped with a vent which can be connected to a heat exchanger, ~or example a cold water cnn~n.~er. Any excess vapor ~rom liquid surge tank 68 can be con~n~ed and recycled to solvent recovery tower 14 and recycled ~or reuse with the solvent. Line 57 can be equipped with a heat exchanger 69 which can operate to reduce the temperature o~ the cooking mixture to a level such that the liquid in the cooking mixture does not flash when the cooking mixture passes through pressure reduction device 70 (e.g. a pressure reducing valve or a turbine). The cooking mixture can be recycled through impregnation vessel 45 and pressure reduction device 70 can operate to reduce the pressure o~ the cooking mixture in line 55, namely to ~rom 650 psig to about 20 to 650 psig. In a pre~erred embodiment, chip sluice tank 65 can be within the pressure range o~ extractor 100, namely o~ ~rom about 150 to 650 psig.
The impregnated ~ibrous plant materials can enter extractor 100 and can be digested and extracted with solvent 36 which can be ~ed into extractor 100 at inlets 52 and 53. Solvent 36 can comprise appropriate quantities o~ cooking solvent 30, with recovered alcohol ~rom the alcohol and co-products recovery system introduced at 7 and with alcohol/water ~iltrate from countercurrent washing equipment 77. The solvent CA 0222l6l9 l997-l2-0~
WO 96/41052 PCTAUS9CI~312 cont~;ne~l in line 36 can be heated in pulp W~h; ng equipment 77 by heat ~h~nge with the pulp leaving extractor 100 at outlet 41.
The type o~ extractor used is not critical, however it should be adaptable to the continuous pulping of the cooking mixture. Typical extractor ~;m~n~ions de-pend on the required capacity o~ the extractor. As shown in Figure 3, extractor 100 can be operated in a continuous cocurrent/countercurrent mode and at a pressure range o~ ~rom about 150 to about 650 psig. Such an extractor is comprised o~ sequential reaction zones and means to add and remove solvent. The latter can be in the ~orm o~ liquor extraction screens equipped with wipers or other cleaning devices that prevent screen plugging such as steam injectors. The cooking mixture passes through extractor 100 and is exposed sequentially to six reaction zones. With this particular extractor configuration, ~urther alcohol impregnation o~
the ~ibrous plant materials occurs at a constant temperature o~ ~rom about 50~C to 170~C in separation zone (a) ~or about 2 to about 20 minutes. In separation zone (a), a vapor head space is maint~;n~ with the level o~ the solvent in the cooking mixture higher than the level of the ~ibrous plant materials. Any excess solvent is L~lll~v~d through outlet 39 and recycled as described above. The temperature o~ the cooking mixture is elevated as the cooking mixture passes into preheating zone (b) and is preheated to ~rom about 150~
to 180~C in about 50 minutes. The heating o~ the cooking mixture in preheating zone (b) is achieved by circulating the cooking solvent countercurrently through a heat ~h~nger (typically of the tube and shell type) which is heated with steam. The heat ~h~nger temperature is m~;nt~;ned at a level su~icient to cause the cooking mixture in preheating zone (b) to heat to CA 02221619 1997-12-0~
from about 150~ to 180~ C. The preheated cooking mixture is further heated in primary extraction zone (c) to from about 175~C to 205~C and subjected to digestion and extraction for about 70 minutes to about 180 minutes.
The cooking m; ~tllre is heated in primary extraction zone (c) by circulating the cooking solvent cocurrently through a heat P~h~nger as described above. In zone (c), a hot ethanol/water extract or black liquor is produced during the digestion and extraction process.
The hot black liquor which cont~; n~ lignin, hemicellulose, other saccharides and extractives (e.g.
resins, organic acids, phenols and tAnn;n.~) and the spent additive can be separated from the cooking mixture through line 71 and subsequently treated to recover the lignin and other co-products o~ the pulping process. In general, the level of additive used in the process is low enough such that there is no need for separate recovery and regeneration steps to recover the additive.
The cooking mixture is further digested and extracted ~or about 60 minutes in secondary extraction zone (d) at a temperature o~ from about 100~ to 190~C.
The temperature is cooled in secondary extraction zone (d) by recirculating the cooking solvent in a heat P~h~nger as described above. The heat p~h~nger temperature is maintained at a level sufficient to achieve the cooling of the cooking mixture to m~;nt~;n a temperature of from about 100~ to 155~ C in secondary extraction zone (d). The cooking mixture is further digested and extracted for about 45 minutes in tertiary extraction zone (e) and the mixture is cooled to a temperature of from about 100~C to 125~C by recirculating the cooking solvent cocurrently through a heat exchanger as described above. The cooking mixture is ~urther cooled to from a~out 70~ to 100~C in cooling zone (f) CA 02221619 1997-12-0~
WO 96/41052 PCT~US9G/'~12 for about 22 minutes and broken up into pulp with mixer 102. Cooling of the cooking mixture in cooling zone (f) is achieved by mixing the mixture with the solvent introduced at inlet 52 in a countercurrent fashion and at inlet 53 in a cocurrent fashion. The solvent mixture consists of makeup alcohol, recycled alcohol from the alcohol and co-product recovery and alcohol/water filtrate from washing equipment 77. The pulp exits extractor 100 through line 41 and is processed through pulp recovery equipment 95 which can be comprised holding tank 74, washing equipment 77, holding tank 9 and pulp screen 10.
As shown in Figure 2, the pulp can be trans-ferred to holding tank 74 which is at pressure sufficient to preserve pulp strength, and where possible such pressure is atmospheric. The pulp can be washed on washing equipment 77 with recycled alcohol through line 7 with cooking solvent 30 and cooled to a temperature below 80~C while simultaneously additional lignin is removed and recycled through line 36. The pulp can be further washed on washing equipment 77 by water introduction through line 35 and cooled to a temperature of from about 40~ to 70~C.
After washing of the pulp, the pulp can be sent to holding tank 9 and pumped through a pulp screen 10. The pulp can then be suitably subjected to conventional pulp handling, bleaching and papermaking procedures.
In one bleaching technique, the pulp now re-ferred to as brownstock can be delignified by treating in an oxygen delignification step or an alkaline extraction step. Filtrates 110 thus obtained can be recycled into the additives mixture 40 and mixed with ~ ~ - ~
CA 02221619 1997-12-0~
W O 96/41052 PCTAJS~G~ 2 -cooking solvent 30. In this way, the sodium which is typically present in filtrate 110 can be combined with sulfur dioxide to form sodium bisulfite and/or sodium sulfite and can thus be used in pulping. In one embo~;m~n~, oxygen delignification of pulp can be carried out by first mixing a pulp slurry at ~rom about 9 to 15~ consistency by weight of pulp solids with a solution of sodium hydroxide (caustic) and further mixing at high shear with oxygen gas. The amount of caustic added can preferably be from about 2 to 8~, more preferably from about 3 to 6~ based on (~) w/w of oven dry (o.d.) pulp. The temperature of the reaction mixture can be between about 60~C and 110~C, more preferably between about 70~C and 90~C, and oxygen pressure in the bleaching vessel can preferably be maint~;ne~ at from about 40 to 110 psig, more preferably at ~rom about 80 to 100 psig for oxygen delignification and at from about 32 to 60 psig for delignification using oxidative extraction. The reaction time with oxygen can preferably be from about 6 to 60 minutes, more pre~erably from about 40 to 50 minutes. Filtrates 110 ~rom oxygen delignification can be subjected to treatment with S02 gas prior to mixing with additives mixture 40. If ne~ , any excess water can be removed from filtrates 110 using processes known in the art.
Black liquor 71 can be obtained ~rom extractor 100 and the lignin, co-products and alcohol can be re-covered in li~uor recovery equipment 85 as described by Lora.
The invention may be further illustrated by the following examples.
CA 0222l6l9 l997-l2-0~
WO96/41052 PCTAUS96~12 Example 1 In this example, sugarcane bagasse is cooked with additions o~ sodium hydroxide, sodium sul~ite singly and in combination. The concentration o~ the cooking solvent was 60~ by weight o~ ethanol, at 175~C
and at I0:1 liquor to bagasse ratio. Conditions are sum-marized in Table 1. The results obt~;ne~ show that higher pulping yields and pulp viscosity are obt~ne~
with the additives ~or a same kappa number or autocatalyzed organosolv pulping.
Table 1 Additive Time E~ Yield Kappa Viscosity Kappa (~) (hr) (extracted) None 0.75 4.57 66.9 74.2 25.1 ---None 1 4.44 61.36 82.4 22.9 ---None 1.75 4.25 55.14 58.7 17.4 ---NaOH
1.3 4 5.34 73.23 69.05 28.38 39.4 2.6 4 6.13 71.5 38.58 37.13 27.13 Na~SO3 2 2 4.92 72.96 79.66 29.55 36 2 4 4.68 66.15 61.16 26.39 23.67 4 3 5.15 69.98 53.41 27.15 22.06 NaOH/Na~SO3 1.3/2 3 5.61 71.39 52.69 --- 32.56 2.6/2 3 6.23 70.2 32.83 --- 28.34 CA 0222l6l9 l997-l2-0~
WO 96/41052 PCTAUS~6/0~12 Example 2 Sugarcane bagasse was pulped in a pilot plant using the conventional autocatalyzed organosolv process and by addition of sodium hydroxide and sodium sul~ite.
Table 2 summarizes the results obt~;ne~l in both cases.
The pilot plant data con~irms the results obt~;ne~ at the bench level. The modi~ied process results in higher pulp yields and lower kappa numbers than the con-ventional process. Furthermore it was observed that in-creasing the severity o~ cooking conditions when using additives increased the viscosity. This unexpected phPnomPnon is perhaps the result o~ the pre~erential Vdl 0~ hemicelluloses with a molecular weight lower than cellulose as the cooking severity increases.
Table 2 Conv Conv Conv Mod Mod * * ** * *
NaOH (~) 0 0 0 3.86 3.86 Na2SO3 (~) 0 0 0 2.98 2.98 20 Primary (120 min) 185~C 180~C 193~C 193~C 193~C
Secondary (30 min) 160~C 150~C 180~C 150~C 150~C
Tertiary (30 min) 160~C 120~C 180~C 100~C 100~C
Yield (~) (cooked) 59. 4 62. 5 55.2 77.6 76 CA 02221619 1997-12-0~
WO 96/41052 PCTAUS96/~12 Kappa (w/o wash)41.2 73.0 34.6 17.0 32.2 Kappa (washed) 39.8 63.9 31.9 15.0 30.9 Kappa (a~ter E) 26.1 35.1 --- 15.3 26.9 Viscosity 24.6 31.4 32.4 33.0 59.2 *: Conventional or modified process with di~fusion bagasse **: Conventional process with crushed bagasse m~l e 3 Table 3 compares the properties o~ sugarcane bagasse pulps produced by the conventional autocatalyzed ALCELLR process and with pulping in the presence o~
sodium sul~ite and sodium hydroxide. The data indicates that the unbleached pulps obt~; nP~ by the modi~ied process have higher tear index, breaking length and burst index than pulps obtained by the conventional process.
CA 02221619 1997-12-0~
W O96/410S2 PCT~US96/09912 Table 3 Raw Material Di~usion Baqasse Crushed Bagasse Process Conv Mod Conv Mod Yield (~) 59.4 77.7 60-70 76 Kappa (washed) 39.8 17 40-80 30.9 Bulk 1.5 1.77 1.8-1.9 1.70 (cm3/g) ~
.
Tear Index 3.3 5.8 4.2-4.5 7.2 (rr~m2 /g) Burst Index 3.3 4.1 2.-2.5 2.9 (KPam2/g) Breaking Length (Km) 6.4 7.1 3.9-4.6 5.7 Revs. (300 CSF) 1000 1900 1400-2500 3400 Example 4 In this example, maple is cooked with additions o~ sodium hydroxide, sodium sul~ite singly and in combination. The temperature was 195~C and the liquor to wood ratio was 8:1. Conditions are summarized in Table 4. The results obt~;n~ show that sodium sul~ite improved deligni~ication o~ the pulp as measured by the kappa number.
CA 02221619 1997-12-0~
W O96/41052 PCT~US96/~9~12 Table 4 Alc/H20 Time pH Yield Kappa Viscosity (hr) No additives 70:30 1.5 4.41 55.97 74.75 ---60:40 1.0 4.51 54.88 73.46 51.36 60:40 2.0 4.1 53.52 43.27 15.81 60:40 2.5 4.09 52.42 43.9 12.96 50:50 1.5 3.86 54.26 56.49 14.43 50:50 2.5 3.91 49.45 31.53 5.4 40:60 1.5 3.69 51.66 62.53 6.38 Na~S03 (~) 70:30 2 1 4.88 65.53 75.21 ---70:30 2 2 4.96 63.06 61.62 ---70:30 2 3 5 55.74 49.54 ---70:30 4 1.5 5.45 62.2 68.24 ---70:30 4 2 5.52 59.86 62.82 ---60:40 2 1 4.59 57.95 63.6 69.85 60:40 2 2 4.68 57.14 49.93 48.36 60:40 2 3 4.71 53.23 43.63 33.58 60:40 3 1 4.79 54.17 64.37 53.52 60:40 3 2 4.84 53.15 45.81 54.99 60:40 3 3 4.88 50.82 38.45 37.41 60:40 4 1 5.35 58.3 60.46 69.01 60:40 4 2 5.11 56.15 45.69 54.11 60:40 4 3 5.1 51.84 36.05 38 60:40 6 1 5.72 61.53 59.2 ---50:50 4 1.5 4.71 55.12 49.76 45.76 50:50 4 2.5 4.87 49.01 33.29 23.99 40:60 4 1.5 4.37 53.42 51.26 28.11 CA 0222l6l9 l997-l2-0~
WO 96/410~2 PCTnUS96/09942 NaOH (~) 60:40 1.3 1 5.19 64.84 60.94 ---60:40 2.6 1 5.52 65.31 66.97 ---Example 5 In this example, maple is cooked with sodium carbonate as an additive to a 60: 40 ethanol/water cooking liquor and in an 8:1 cooking liquor to wood ratio. The temperature is about 195~C and the cooking time is about 2.5 hours. Sodium carbonate is added as an additive o~ ~rom about 0~ to about 6~ on a weight basis on wood. The results obt~;n~ are compared with results obt~;ne~ using sodium sul~ite as an additive.
Table 5 shows that the pulp obt~;n~ with about 4~ sodium sul~ite has a i~inal pH in the same range as the pulp obtained using about 2~ sodium carbonate as the additive. Yields are in the same range for both pulps, and the pulp obtained using sodium sul~ite has a kappa number about 20 units lower than the pulp obtained using sodium carbonate. Results in Table 5 show that in this case, the presence of~ additive rather than any pH
adjustment caused by the additive is responsible ~or the enhanced deligni~ication.
Table 5 Additive ~ Kappa Yield (~) (~) ., Na2Co3 0 4.09 43.9 52.42 2 5.21 61.87 57.37 CA 0222l6l9 l997-l2-0~
W 096/410S2 PCT/U~5G~9512 3 5.39 61.07 59 4 5.55 62.38 60.54 5.79 60.49 60.78 6 5.91 66.58 61.9 Na~SO~
0 4.09 43.9 52.42 3 4.84 41.96 51.99 4 5.1 40.4 55.78 Example 6 10In this example, mixed hardwoods comprising about 50~ maple, about 35~ birch and about 15~ poplar are pulped with about 4~ sodium sulfite as an additive to a 60:40 alcohol/water cooking liquor and a liquor to wood ratio of 8:1. The temperature is about 195~C.
15Conditions are summarized in Table 6 and the results obtained show a higher pulp viscosity at a given kappa number.
Table 6 Time E~ Kappa Viscosity (min) (cps) No Additive 4.29 58.63 46.49 4.2 44.6 36.79 4.23 46.62 31.77 4.14 41.68 36.65 120 4.16 37.64 25.97 150 3.99 35.22 18.9 CA 0222l6l9 Is97-l2-o~
Na~SO~ (4~) 5.1 46.52 60.44 5.06 47.29 47.03 120 5.14 35.62 41.73 150 5.07 30.87 41.73 180 5.05 25.57 32.62 Example 7 In this example, maple is pulped with about 4~
sodium sulfite as an additive to a 60:40 ethanol/water cooking liquor and a liquor to wood ratio of about 8:1.
The temperature is about 195~C and the cooking time is about 3 hours. The pulp obt~; n~ has a kappa number o:E
about 31, a viscosity of about 65 cps, a Pulmac strength index o:E about 83 and a Kajaani weighted average ~iber length o~ about 0. 71 mm. The pulp is beaten and its physical properties were measured. The physical properties o~ the resulting pulp are compared with a commercial kraft pulp obt~ nP~ ~rom maple. Results in Table 7 ~l~mnn~trate that the pulp has superior physical properties than unmodified organosolv pulp and that its physical properties such as breaking length are better than kra~t pulp.
Table 7 Alcohol/ Alcohol Kraft Sulfite PFI mill revolutions 4300 4000 2500 Bulk, mL/g 1. 45 1.42 .46 CA 02221619 1997-12-0~
WO 96/41052 PCT~US96iO9~2 Tear Index 6.1 4.9 6 .2 (mNm2 /g) Burst index 2.95 2.3 2.95 (kPam2/g) Breaking Length 5. 6 4.8 5.2 (km) Example 8 In this ~mrle, jute was pulped with sodium sulfite. Table 8 shows the results obt~;nP~ when pulping jute in alcohol/water with and without sodium sulfite present at 195~C. As can be observed the presence of the additive resulted in higher viscosity and lower kappa numbers, i.e. improved selectivity is achieved.
Table 8 also shows the strength properties of bleached and unbleached jute pulps at 300 CSF. The use of additives significantly ilLL~oved the pulp strength o~
both the unbleached and bleached pulps. Table 9 shows the bleaching conditions used ~or jute and the results show that when an additive was used, a lesser amount o~
bleaching chemicals can be used.
Table 8 No additive 4~ N~2S03 Alcohol 70 60 (~) (v/v) ,, Pulp yield 68.8 66.7 (~) Kappa No. 35.0 18.4 Viscosity 33.2 72.5 (cps) Unbleached Burst index 2 5.5 (kPam2/g) Tear Index 5.8 19.4 (mNm2 /g) Breaking Length 4.2 7.9 (km) Bleached Burst index 1.7 5. 2 (kPam2/g) Tear Index 6.7 18.0 (mNm2/g) Breaking Length 3.8 7.2 (km) Table 9 Stage Consistencv Time Temp Charge (~) (~) (hr) (~C) * **
E (NaOH) 10 0.5 70 3 3 D1 (Cl02) 12 3 70 2.88 1.93 E (NaOH) 12 2 70 2 1.8 D2 (Cl02) 12 3 70 0.8 0.8 CA 02221619 1997-12-0~
Final Brightness 88. 7 88.5 I
Brightness after D1 60 65 *: pulped without additive **: pulped with additive Example 9 In this example, additives were used to pulp seed flax whole stalks. The seed ~lax whole stalks were separated into core and bast fractions by grinding in a blender in a dry state. As a result of this grinding and of the centrifugal forces due to the blender action, the core and bast fractions were separated, with the core forming a lower layer and the bast a top layer. The conditions used for pulping and the results obtained for bast and core fractions are presented in Table 10 The data shows that high selectivity (high viscosity, low kappa number) for core and bast pulping was achieved when sodium bisulfite is used. No acceptable pulp could be obt~;ne~ ~rom the core without the use of additives.
Table 10 Bast Bast Core Sodium Bisulfite (~) 0 3 3 Temperature (~C) 195 195 185 ~ 25 Time (min) 60 30 120 Ethanol:Water 60:40 60:40 40:60 Yield (~) 64 69 46 Kappa No. 63 30 64 CA 0222l6l9 l997-l2-05 W O 96/41052 -28- PCT~US96/09942 Pulps produced in the presence o~ sodium bisul~ite were bleached by EoDED using conditions in Table 11. A ~inal bri~htness o~ 83 1 and viscosity o~
30.2 cps was obt~;n~ ~or the core. For the bast, 84.5 brightn~Fs and 32.6 cps was obt~;n~. The strength properties obt~; n~ are shown in Table 12.
Table 11 Stage Temp Consistency Time Char~e (~) (~C) (~) (min) Core Bast Eo 70 12 30 3 3 D1 70 12 180 5.9 5 9 D2 70 12 180 1. 2 1.2 Table 12 Core Bast (mls) Bulk 1.33 2.04 (cm3/g) Burst index 3.3 3 9 (kPam2 /g) Tear Index 4 5 15.1 (mNm2 /g) -CA 0222l6l9 1997-l2-0~
W O96/41052 PCT~US961'~3312 Breaking Length 7.0 6.3 (km) Example 10 A mixture o~ spruce and balsam ~ir was pulped using alcohol water in the presence o~ sodium bisul~ite.
Processing conditions used per batch were as follows: 30 grams of wood (oven dried basis), 240 mL o~ solvent (made up o~ SDA-1 alcohol and water in a ratio o~ 60:40 v/v and taking into account the water present as moisture in the wood) and 1.2 grams o~ sodium bisul~ite were put together in a Parr bomb (Parr Company, Moline, Illinois) and were heated to 195~C i~or 120 minutes.
Then the cooked chips were de~iberized and then washed using 50:50 alcohol:water. Pulp was obt~neA with a yield o~ 57~ on oven dried wood. It had a kappa number o:E 73 mL/g and a viscosity o~ 51 cps. The kappa number could be reduced to 51 mL/g a~ter a 2 hour alkali extraction at 70~C using 4~ NaOH on pulp and a 10 consistency. At 532 CSF the pulp had the properties reported in Table 13.
Table 13 Bulk 1.45 (cm3/g) Burst index 6.9 (kPam2/g) Tear Index 13. 5 (mNm2/g) Breaking Length 9.8 (km) W O 96/41052 PCTnUS96/099~2 This invention and many o~ its attendant ad-vantages will be understood ~rom the foregoing descrip-tion, and it will be apparent that various modi~ications and changes can be made without departing ~rom the spirit and scope of the invention or sacri~icing all o~
its material advantages, the processes herein~e~ore described being merely pre~erred embo~;m~nts.
Solvent Pulping Conference, pages 663-671, 1990, propose the use of an alkali pretreatment of wood prior to the SO2-ethanol-water pulping. The pretreatment process was a vacuum impregnation of wood chips in aqueous ethanol with the presence o~ sodium hydroxide. The two-stage organosolv process produced softwood pulps with about 6~
to about 10~ higher yield than kraft and single-stage organosolv pulps. The pretreatment process also caused a reduction of kappa number by around 6 units as compared to the single-stage organosolv pulping. The pulps have lower strength than kraft pulps, particularly in regard to tear strength.
Primakov et al. in IlProcessing of Liquors after Pulping with Water-Alcohol Solutions", Khim. Drev.
(4) 23-5, 1982 propose the cooking of birchwood with SO2 in a 1:1 saturated alcohol-water mixture cont~in;ng 40 to 75~ spent sulfite liquor with a Kappa number of 20.8 to 25 and a breaking length of 4900 m to 5500 m The addition of spent liquor reduces the consumption of alcohol in cooking.
Sakai in "Organosolv Deligni~ication", Shipa Gikyo Shi, Vol. 48, No. 8, pp. 11-20 (1994) discloses the addition of bisulfite to the isopropyl alcohol-water solvent system. Large amounts of additive are used, for example 18~ magnesium bisulfite, at 165~C for cooking times o~ an hour. They have obtained pulps with high kappa numbers and their product is a semichemical pulp rather than a ~ully bleachable chemical pulp.
CA 02221619 1997-12-0~
W 096/41052 PCT/U~ 12 SUMMARY ON THE INVENTION
It is an object of this invention to provide for a process for manufacturing pulp by pulping with a cooking solvent comprising an aqueous solution o~ a lower aliphatic alcohol and one or more additive. The additive is added in such small amounts that separate procesess for the recovery or regeneration of the additives are not required. One e~ample o~ such additives are bisulfite salts added with maple and mixed hardwoods in a range of from about 0.05~ to about 6~.
Another example are sulfite salts added to maple and mixed hardwoods in a range o~ ~rom about 0.05~ to about 6~. Sul~ite salts can be added singly to bagasse and jute in a range of from about 2~ to about 4~ or in combination with sodium hydroxide which can be added in a range of from about 1.3~ to 4~.
BRIEF DESCRIPTION OF THE DRAWINGS
Figures 1, 2 and 3 are flow diagrams of the process of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
This invention provides for a process of improving the selectivity of delignification and increasing the rate of delignification beyond that which is obt~; n~ with the autocatalyzed organosolv pulping process. Selectivity can be ~nh~nced by the addition of additives such sodium hydroxide, sodium sulfite, ;um and magnesium bisulfite, and sodium bisulfite to the cooking solvent. The cooking solvent can be ~ comprised of from about 30~ to about 92~ (by weight) of a water miscible lower aliphatic alcohol of 1 to 4 carbon atoms (e.g., methanol, ethanol, isopropanol or tert-butanol) and from about 8 to about 70~ water. The CA 0222l6l9 l997-l2-0~
W O 96/410~2 PCT~US~Gi~12 cooking solvent can be further comprised of recovered alcohol and alcohol/water filtrate from the process and if needed, a small amount of a strong water soluble acid, such as a mineral acid (e.g., hydrochloric, sul~uric, phosphoric or nitric acid) or an organic acid (e.g., oxalic acid, preferably acetic, formic or peroxy acids), or a small amount of a mineral salt. The resulting cooking liquor can be used to pulp a wide range of raw materials such as for example sugarcane bagasse, sugarcane rind chips, hardwood such as maple, birch, poplar, oak, ash, basswood as single species or in combination, jute, ~lax, straw, kenaf, reed, and so~twoods such as spruce and balsam ~ir mixtures.
Ble~h~hle pulps can be obtained with low kappa number, high pulp strength and high yields.
Improved pulping selectivity can be obt~;n~
with the additives of the invention. We believe that bisulfite additive may be causing partial sulfonation of the lignin present in the feedstock. Generally, sulfonation can block re~nn~n~ation reactions which are believed to interfere with the pulp reaching a very low kappa number. Additionally, the products o~ sulfonation are believed to act as surfactant and as such contribute to the ~ l~vdl of the organosolv lignin.
Furthermore, oxidation-reduction side reactions in the presence o~ sulfite and bisul~ite additives are believed to create a catalytic ef~ect. Generally, additives such as sulfite can cause the pH to rise with the net result that hydrolysis of the cellulose fraction can occur at a lower acidity and a higher retention o~ hemicellulose as evidenced by the higher viscosity and higher hemicellulose content of the pulp which is produced.
Generally, sul~ite and bisulfite can be added as sodium, magnesium or ~mmnn;um sulfites and bisulfites salts to a wide range of fibrous plant materials such as CA 02221619 1997-12-0~
W O 96/41052 PCT~US~6/09~2 softwoods, maple, flax, wheat straw and a mixture of hardwoods. Caustic can also be added singly or in combination with any of the sulfite or bisulfite salts.
The fibrous plant materials can be pulped in accordance with Diebold or as shown in Figure 1. With the addition of additives to the cooking solvent, more uni~orm pulp cooking can be obt~in~ with lower pulp screening rejects and pulp with a lower kappa number.
For P~m~le, bisulfite salts can be added to maple and mixed hardwoods, sugarcane residues such as sugarcane bagasse at a level of from about 0.05~ to about 6~ by weight on fibrous plant materials.
Bisulfites can be added to the cooking solvent comprising alcohol and water in a weight percent of from about 30~ to about 92~, preferably from about 40~ to about 55~. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1. With the Diebold process, primary extraction times can be of from about 45 minutes to about 210 minutes and at a temperature o~ ~rom about 190~C to about 200~C, from about 100~C to about 155~C for a secondary extraction and ~rom about 100~C to about 124~C for a tertiary extraction. The pH of the cooking li~uor during primary extraction is from about 5 to about 5.4. The resulting pulp obt~lne~ had a low kappa number and a high yield of deligni~ication.
In another preferred embodiment, sulfite addi-tives can be used in the pulping of jute, flax, reed, sugarcane residues, wheat straw, maple and mixed hardwoods. When maple and mixed hardwoods are pulped, the level of sulfite used is from about 0.05~ to about 6~ on a weight basis on feedstock. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1. With the Diebold CA 0222l6l9 l997-l2-0~
W O96/41052 PCT~US9G/09912 process, the sulfite can be added to the cooking solvent described above at the primary extraction stage. The duration of the primary extraction is from about 60 minutes to about 180 minutes and at a temperature of from about 175~C to about 204~C. The pH of the cooking liquor during extraction is from about 4.4 to about 6.3.
In another preferred embodiment, sulfite addi-tives alone or in combination with NaOH can be used in the pulping of bagasse. When used alone, the level of sulfite is from about 2~ to about 4~ on a weight basis on bagasse. When used alone, the level of caustic is from about 1.3~ to about 2.6~ on a weight basis on bagasse. Sulfite and caustic can be used in combination.
When the two additives are used in combination, the level of sulfite is from about 2~ to about 4~ and the level of caustic is from about 1.3~ to about 4~ and the level of each additive can be adjusted such that the pH
of the cooking liquor during the preheating step is in the alkaline range. The pH reaches a level of from about 6 to about 8 as the cooking liquor temperature reaches its m~ ml~m and becomes slightly acidic as the primary extraction progresses. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1.
Alternatively, sulfite additives alone or in combination with caustic can be used in the pulping o~
jute. When used alone, the level o~ sulfite is from about 2~ to about 4~ on a weight basis on jute. When used alone, the level of caustic is from about 1.3~ to about 2.6~ on a weight basis on jute. Sulfite and caustic can be used in combination. When the two additives are used in combination, the level of sul~ite is from about 2~ to about 4~ and the level of caustic is from about 1.3~ to about 4~ and the level of each CA 02221619 1997-12-0~
_g _ additive can be adjusted such that the pH of the cooking liquor during the preheating step is in the alkaline range. The pH re~ches a level of from about 6 to about 8 as the cooking liquor temperature reaches its m~; mllm and becomes slightly acidic as the primary extraction progresses. The fibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1.
In another preferred embodiment, caustic can be used in the pulping of sugarcane residues, maple and mixed hardwoods in a range of from about 1.3~ to 2.6~.
The ~ibrous plant materials can be pulped as taught by Diebold or using the process shown in Figure 1. With the Diebold process, the pH reaches a level of from about 5 to about 7.
The process of this invention is schematically shown in Figure 1. Fibrous plant materials 10 having a moisture level o~ from about 5~ to about 60~ can be steamed by ~eeding steam 20 into the plant materials in steaming equipment 15 to a temperature o~ in the range ~rom ambient to about 120~C. The materials are steamed ~or from about 0.5 minute to about 120 minutes to heat the materials and to remove any air which may be trapped therein.
Following steaming, the steamed materials are wetted with cooking solvent 30 described above and in-troduced in ~eeder 25. The materials in feeder 25 can be pressurized to ~rom about atmospheric to the pressure in impregnation vessel 45 or alternatively to the pressure in extractor 100.
Following ~eeding, the materials can be im-pregnated in impregnation vessel 45 with additives CA 02221619 1997-12-0~
W O 96/41052 PCTnU596/0~9~2 mixture 40. Additives mixture 40 can comprise cooking solvent 30 and any of the additives mentioned above mixed therein at the appropriate concentration level depending on the fibrous plant material being pulped. A
slurry can be obt~;ne~. The impregnation time is from about 1 minute to about 120 minutes and the materials are simultaneously heated to ~rom about 50~C to about 170~C. During the impregnation time, the slurry can be pressurized to the pressure in extractor 100.
The fibrous plant materials slurry from im-pregnation vessel 45 can be ~ed into extractor 100 and the slurry which typically comprises from about 5~ to about 20~ solids is pulped for from about 45 minutes to about 6 hours. The temperature in extractor 100 is from about the temperature in impregnation vessel 45 to about 205~C.
During pulping, a stream of spent li~uor 71 and a pulp slurry 75 can be withdrawn from extractor 100. Spent liquor 71 can be processed in liquor recovery e~lipmPnt 85 to yield lignin, co-products and alcohol.
Pulp slurry 75 can be processed in pulp recovery e~l;pmPnt 95 to yield pulp and alcohol.
The invention can be applied to both batch and continuous cooks. In the case of batch cooks, the steaming and feeding steps described above can be practiced in accordance with Diebold. A c~nt; nllOUS
process can be practiced in accordance with Figure 2 where steaming e~uipment 15 can be comprised o~ metering screw 32, ~irst rotary valve feeder 33, second rotary valve feeder 34 and chip sluice tank 65. In one embodiment, the fibrous plant materials can be pre-steamed in steaming bin 31 by injection of steam at atmospheric pressure. The plant materials are wetted and CA 02221619 1997-12-0~
W O96/41052 PCT~US96/09942 passed into metering screw 32 which can be positioned at an angle. The excess water ~rom the steam con~n.~ates in metering screw 32 can be L~.luved and the wet ~ibrous plant materials can be passed through a ~irst rotary valve feeder 33, heated in line 46 by direct steam injection at a temperature o~ from about 50~C to about 130~C and at a pressure o~ ~rom about 30 to about 100 psig. Line 46 can be equipped with a steam barrier which helps prevent backup o~ alcohol-cont~;n;ng vapors into rotary valve ~eeder 33. The steamed ~ibrous plant materials are passed through a second rotary valve ~eeder 34. The ~ibrous plant materials in chip sluice tank 65 can be mixed with cooking solvent 30 and recycle solvent 50 from impregnation vessel 45.
Following ~eeding, additive mixture 40 can be added and the fibrous plant materials can be impregnated in impregnation vessel 45. The slurry can be pressurized in impregnation vessel 45 to the operating pressure of extractor 100. The slurry now re~erred to as cooking mixture can enter extractor 100 at inlet 38, a liquid separator 101 regulates the ~low o~ the mixture into extractor 100. Excess cooking mixture liquid over~lows extractor 100 at outlet 39, is recycled through line 57 and pumped back into impregnation vessel 45. In a pre~erred embo~;m~nt, a mechanical separator 101 is uti-lized to accomplish the liquid separation as described above. Additionally, mechanical separator 101 is utilized to convey the slurry o~ ~ibrous plant materials into extractor 100 in a m~nn~ which maintains the ~ree ~low o~ excess cooking mixture liquid. Further, mechanical separator 101 comprises movable screens to allow the adjustment o~ the position o~ such screens in mechanical separator 101 inside and relative to the top o~ extractor 100, as may be desirable, in view o~ the , CA 0222l6l9 l997-l2-0~
W O96/41052 PCT~US~6/09912 ~ibrous materials to be pulped and the pulping conditions in extractor 100.
Alternatively, as the excess cooking mixture liquid over~lows extractor 100 at outlet 39, it is re-cycled through line 57. The cooking mixture liquid passes through liquid surge tank 68. Liquid surge tank 68 is equipped with a level indicator and controls the over~low level o~ the cooking mixture liquid. Liquid surge tank 68 can separate any noncon~n~able gases ~rom the cooking mixture and can be equipped with a vent which can be connected to a heat exchanger, ~or example a cold water cnn~n.~er. Any excess vapor ~rom liquid surge tank 68 can be con~n~ed and recycled to solvent recovery tower 14 and recycled ~or reuse with the solvent. Line 57 can be equipped with a heat exchanger 69 which can operate to reduce the temperature o~ the cooking mixture to a level such that the liquid in the cooking mixture does not flash when the cooking mixture passes through pressure reduction device 70 (e.g. a pressure reducing valve or a turbine). The cooking mixture can be recycled through impregnation vessel 45 and pressure reduction device 70 can operate to reduce the pressure o~ the cooking mixture in line 55, namely to ~rom 650 psig to about 20 to 650 psig. In a pre~erred embodiment, chip sluice tank 65 can be within the pressure range o~ extractor 100, namely o~ ~rom about 150 to 650 psig.
The impregnated ~ibrous plant materials can enter extractor 100 and can be digested and extracted with solvent 36 which can be ~ed into extractor 100 at inlets 52 and 53. Solvent 36 can comprise appropriate quantities o~ cooking solvent 30, with recovered alcohol ~rom the alcohol and co-products recovery system introduced at 7 and with alcohol/water ~iltrate from countercurrent washing equipment 77. The solvent CA 0222l6l9 l997-l2-0~
WO 96/41052 PCTAUS9CI~312 cont~;ne~l in line 36 can be heated in pulp W~h; ng equipment 77 by heat ~h~nge with the pulp leaving extractor 100 at outlet 41.
The type o~ extractor used is not critical, however it should be adaptable to the continuous pulping of the cooking mixture. Typical extractor ~;m~n~ions de-pend on the required capacity o~ the extractor. As shown in Figure 3, extractor 100 can be operated in a continuous cocurrent/countercurrent mode and at a pressure range o~ ~rom about 150 to about 650 psig. Such an extractor is comprised o~ sequential reaction zones and means to add and remove solvent. The latter can be in the ~orm o~ liquor extraction screens equipped with wipers or other cleaning devices that prevent screen plugging such as steam injectors. The cooking mixture passes through extractor 100 and is exposed sequentially to six reaction zones. With this particular extractor configuration, ~urther alcohol impregnation o~
the ~ibrous plant materials occurs at a constant temperature o~ ~rom about 50~C to 170~C in separation zone (a) ~or about 2 to about 20 minutes. In separation zone (a), a vapor head space is maint~;n~ with the level o~ the solvent in the cooking mixture higher than the level of the ~ibrous plant materials. Any excess solvent is L~lll~v~d through outlet 39 and recycled as described above. The temperature o~ the cooking mixture is elevated as the cooking mixture passes into preheating zone (b) and is preheated to ~rom about 150~
to 180~C in about 50 minutes. The heating o~ the cooking mixture in preheating zone (b) is achieved by circulating the cooking solvent countercurrently through a heat ~h~nger (typically of the tube and shell type) which is heated with steam. The heat ~h~nger temperature is m~;nt~;ned at a level su~icient to cause the cooking mixture in preheating zone (b) to heat to CA 02221619 1997-12-0~
from about 150~ to 180~ C. The preheated cooking mixture is further heated in primary extraction zone (c) to from about 175~C to 205~C and subjected to digestion and extraction for about 70 minutes to about 180 minutes.
The cooking m; ~tllre is heated in primary extraction zone (c) by circulating the cooking solvent cocurrently through a heat P~h~nger as described above. In zone (c), a hot ethanol/water extract or black liquor is produced during the digestion and extraction process.
The hot black liquor which cont~; n~ lignin, hemicellulose, other saccharides and extractives (e.g.
resins, organic acids, phenols and tAnn;n.~) and the spent additive can be separated from the cooking mixture through line 71 and subsequently treated to recover the lignin and other co-products o~ the pulping process. In general, the level of additive used in the process is low enough such that there is no need for separate recovery and regeneration steps to recover the additive.
The cooking mixture is further digested and extracted ~or about 60 minutes in secondary extraction zone (d) at a temperature o~ from about 100~ to 190~C.
The temperature is cooled in secondary extraction zone (d) by recirculating the cooking solvent in a heat P~h~nger as described above. The heat p~h~nger temperature is maintained at a level sufficient to achieve the cooling of the cooking mixture to m~;nt~;n a temperature of from about 100~ to 155~ C in secondary extraction zone (d). The cooking mixture is further digested and extracted for about 45 minutes in tertiary extraction zone (e) and the mixture is cooled to a temperature of from about 100~C to 125~C by recirculating the cooking solvent cocurrently through a heat exchanger as described above. The cooking mixture is ~urther cooled to from a~out 70~ to 100~C in cooling zone (f) CA 02221619 1997-12-0~
WO 96/41052 PCT~US9G/'~12 for about 22 minutes and broken up into pulp with mixer 102. Cooling of the cooking mixture in cooling zone (f) is achieved by mixing the mixture with the solvent introduced at inlet 52 in a countercurrent fashion and at inlet 53 in a cocurrent fashion. The solvent mixture consists of makeup alcohol, recycled alcohol from the alcohol and co-product recovery and alcohol/water filtrate from washing equipment 77. The pulp exits extractor 100 through line 41 and is processed through pulp recovery equipment 95 which can be comprised holding tank 74, washing equipment 77, holding tank 9 and pulp screen 10.
As shown in Figure 2, the pulp can be trans-ferred to holding tank 74 which is at pressure sufficient to preserve pulp strength, and where possible such pressure is atmospheric. The pulp can be washed on washing equipment 77 with recycled alcohol through line 7 with cooking solvent 30 and cooled to a temperature below 80~C while simultaneously additional lignin is removed and recycled through line 36. The pulp can be further washed on washing equipment 77 by water introduction through line 35 and cooled to a temperature of from about 40~ to 70~C.
After washing of the pulp, the pulp can be sent to holding tank 9 and pumped through a pulp screen 10. The pulp can then be suitably subjected to conventional pulp handling, bleaching and papermaking procedures.
In one bleaching technique, the pulp now re-ferred to as brownstock can be delignified by treating in an oxygen delignification step or an alkaline extraction step. Filtrates 110 thus obtained can be recycled into the additives mixture 40 and mixed with ~ ~ - ~
CA 02221619 1997-12-0~
W O 96/41052 PCTAJS~G~ 2 -cooking solvent 30. In this way, the sodium which is typically present in filtrate 110 can be combined with sulfur dioxide to form sodium bisulfite and/or sodium sulfite and can thus be used in pulping. In one embo~;m~n~, oxygen delignification of pulp can be carried out by first mixing a pulp slurry at ~rom about 9 to 15~ consistency by weight of pulp solids with a solution of sodium hydroxide (caustic) and further mixing at high shear with oxygen gas. The amount of caustic added can preferably be from about 2 to 8~, more preferably from about 3 to 6~ based on (~) w/w of oven dry (o.d.) pulp. The temperature of the reaction mixture can be between about 60~C and 110~C, more preferably between about 70~C and 90~C, and oxygen pressure in the bleaching vessel can preferably be maint~;ne~ at from about 40 to 110 psig, more preferably at ~rom about 80 to 100 psig for oxygen delignification and at from about 32 to 60 psig for delignification using oxidative extraction. The reaction time with oxygen can preferably be from about 6 to 60 minutes, more pre~erably from about 40 to 50 minutes. Filtrates 110 ~rom oxygen delignification can be subjected to treatment with S02 gas prior to mixing with additives mixture 40. If ne~ , any excess water can be removed from filtrates 110 using processes known in the art.
Black liquor 71 can be obtained ~rom extractor 100 and the lignin, co-products and alcohol can be re-covered in li~uor recovery equipment 85 as described by Lora.
The invention may be further illustrated by the following examples.
CA 0222l6l9 l997-l2-0~
WO96/41052 PCTAUS96~12 Example 1 In this example, sugarcane bagasse is cooked with additions o~ sodium hydroxide, sodium sul~ite singly and in combination. The concentration o~ the cooking solvent was 60~ by weight o~ ethanol, at 175~C
and at I0:1 liquor to bagasse ratio. Conditions are sum-marized in Table 1. The results obt~;ne~ show that higher pulping yields and pulp viscosity are obt~ne~
with the additives ~or a same kappa number or autocatalyzed organosolv pulping.
Table 1 Additive Time E~ Yield Kappa Viscosity Kappa (~) (hr) (extracted) None 0.75 4.57 66.9 74.2 25.1 ---None 1 4.44 61.36 82.4 22.9 ---None 1.75 4.25 55.14 58.7 17.4 ---NaOH
1.3 4 5.34 73.23 69.05 28.38 39.4 2.6 4 6.13 71.5 38.58 37.13 27.13 Na~SO3 2 2 4.92 72.96 79.66 29.55 36 2 4 4.68 66.15 61.16 26.39 23.67 4 3 5.15 69.98 53.41 27.15 22.06 NaOH/Na~SO3 1.3/2 3 5.61 71.39 52.69 --- 32.56 2.6/2 3 6.23 70.2 32.83 --- 28.34 CA 0222l6l9 l997-l2-0~
WO 96/41052 PCTAUS~6/0~12 Example 2 Sugarcane bagasse was pulped in a pilot plant using the conventional autocatalyzed organosolv process and by addition of sodium hydroxide and sodium sul~ite.
Table 2 summarizes the results obt~;ne~l in both cases.
The pilot plant data con~irms the results obt~;ne~ at the bench level. The modi~ied process results in higher pulp yields and lower kappa numbers than the con-ventional process. Furthermore it was observed that in-creasing the severity o~ cooking conditions when using additives increased the viscosity. This unexpected phPnomPnon is perhaps the result o~ the pre~erential Vdl 0~ hemicelluloses with a molecular weight lower than cellulose as the cooking severity increases.
Table 2 Conv Conv Conv Mod Mod * * ** * *
NaOH (~) 0 0 0 3.86 3.86 Na2SO3 (~) 0 0 0 2.98 2.98 20 Primary (120 min) 185~C 180~C 193~C 193~C 193~C
Secondary (30 min) 160~C 150~C 180~C 150~C 150~C
Tertiary (30 min) 160~C 120~C 180~C 100~C 100~C
Yield (~) (cooked) 59. 4 62. 5 55.2 77.6 76 CA 02221619 1997-12-0~
WO 96/41052 PCTAUS96/~12 Kappa (w/o wash)41.2 73.0 34.6 17.0 32.2 Kappa (washed) 39.8 63.9 31.9 15.0 30.9 Kappa (a~ter E) 26.1 35.1 --- 15.3 26.9 Viscosity 24.6 31.4 32.4 33.0 59.2 *: Conventional or modified process with di~fusion bagasse **: Conventional process with crushed bagasse m~l e 3 Table 3 compares the properties o~ sugarcane bagasse pulps produced by the conventional autocatalyzed ALCELLR process and with pulping in the presence o~
sodium sul~ite and sodium hydroxide. The data indicates that the unbleached pulps obt~; nP~ by the modi~ied process have higher tear index, breaking length and burst index than pulps obtained by the conventional process.
CA 02221619 1997-12-0~
W O96/410S2 PCT~US96/09912 Table 3 Raw Material Di~usion Baqasse Crushed Bagasse Process Conv Mod Conv Mod Yield (~) 59.4 77.7 60-70 76 Kappa (washed) 39.8 17 40-80 30.9 Bulk 1.5 1.77 1.8-1.9 1.70 (cm3/g) ~
.
Tear Index 3.3 5.8 4.2-4.5 7.2 (rr~m2 /g) Burst Index 3.3 4.1 2.-2.5 2.9 (KPam2/g) Breaking Length (Km) 6.4 7.1 3.9-4.6 5.7 Revs. (300 CSF) 1000 1900 1400-2500 3400 Example 4 In this example, maple is cooked with additions o~ sodium hydroxide, sodium sul~ite singly and in combination. The temperature was 195~C and the liquor to wood ratio was 8:1. Conditions are summarized in Table 4. The results obt~;n~ show that sodium sul~ite improved deligni~ication o~ the pulp as measured by the kappa number.
CA 02221619 1997-12-0~
W O96/41052 PCT~US96/~9~12 Table 4 Alc/H20 Time pH Yield Kappa Viscosity (hr) No additives 70:30 1.5 4.41 55.97 74.75 ---60:40 1.0 4.51 54.88 73.46 51.36 60:40 2.0 4.1 53.52 43.27 15.81 60:40 2.5 4.09 52.42 43.9 12.96 50:50 1.5 3.86 54.26 56.49 14.43 50:50 2.5 3.91 49.45 31.53 5.4 40:60 1.5 3.69 51.66 62.53 6.38 Na~S03 (~) 70:30 2 1 4.88 65.53 75.21 ---70:30 2 2 4.96 63.06 61.62 ---70:30 2 3 5 55.74 49.54 ---70:30 4 1.5 5.45 62.2 68.24 ---70:30 4 2 5.52 59.86 62.82 ---60:40 2 1 4.59 57.95 63.6 69.85 60:40 2 2 4.68 57.14 49.93 48.36 60:40 2 3 4.71 53.23 43.63 33.58 60:40 3 1 4.79 54.17 64.37 53.52 60:40 3 2 4.84 53.15 45.81 54.99 60:40 3 3 4.88 50.82 38.45 37.41 60:40 4 1 5.35 58.3 60.46 69.01 60:40 4 2 5.11 56.15 45.69 54.11 60:40 4 3 5.1 51.84 36.05 38 60:40 6 1 5.72 61.53 59.2 ---50:50 4 1.5 4.71 55.12 49.76 45.76 50:50 4 2.5 4.87 49.01 33.29 23.99 40:60 4 1.5 4.37 53.42 51.26 28.11 CA 0222l6l9 l997-l2-0~
WO 96/410~2 PCTnUS96/09942 NaOH (~) 60:40 1.3 1 5.19 64.84 60.94 ---60:40 2.6 1 5.52 65.31 66.97 ---Example 5 In this example, maple is cooked with sodium carbonate as an additive to a 60: 40 ethanol/water cooking liquor and in an 8:1 cooking liquor to wood ratio. The temperature is about 195~C and the cooking time is about 2.5 hours. Sodium carbonate is added as an additive o~ ~rom about 0~ to about 6~ on a weight basis on wood. The results obt~;n~ are compared with results obt~;ne~ using sodium sul~ite as an additive.
Table 5 shows that the pulp obt~;n~ with about 4~ sodium sul~ite has a i~inal pH in the same range as the pulp obtained using about 2~ sodium carbonate as the additive. Yields are in the same range for both pulps, and the pulp obtained using sodium sul~ite has a kappa number about 20 units lower than the pulp obtained using sodium carbonate. Results in Table 5 show that in this case, the presence of~ additive rather than any pH
adjustment caused by the additive is responsible ~or the enhanced deligni~ication.
Table 5 Additive ~ Kappa Yield (~) (~) ., Na2Co3 0 4.09 43.9 52.42 2 5.21 61.87 57.37 CA 0222l6l9 l997-l2-0~
W 096/410S2 PCT/U~5G~9512 3 5.39 61.07 59 4 5.55 62.38 60.54 5.79 60.49 60.78 6 5.91 66.58 61.9 Na~SO~
0 4.09 43.9 52.42 3 4.84 41.96 51.99 4 5.1 40.4 55.78 Example 6 10In this example, mixed hardwoods comprising about 50~ maple, about 35~ birch and about 15~ poplar are pulped with about 4~ sodium sulfite as an additive to a 60:40 alcohol/water cooking liquor and a liquor to wood ratio of 8:1. The temperature is about 195~C.
15Conditions are summarized in Table 6 and the results obtained show a higher pulp viscosity at a given kappa number.
Table 6 Time E~ Kappa Viscosity (min) (cps) No Additive 4.29 58.63 46.49 4.2 44.6 36.79 4.23 46.62 31.77 4.14 41.68 36.65 120 4.16 37.64 25.97 150 3.99 35.22 18.9 CA 0222l6l9 Is97-l2-o~
Na~SO~ (4~) 5.1 46.52 60.44 5.06 47.29 47.03 120 5.14 35.62 41.73 150 5.07 30.87 41.73 180 5.05 25.57 32.62 Example 7 In this example, maple is pulped with about 4~
sodium sulfite as an additive to a 60:40 ethanol/water cooking liquor and a liquor to wood ratio of about 8:1.
The temperature is about 195~C and the cooking time is about 3 hours. The pulp obt~; n~ has a kappa number o:E
about 31, a viscosity of about 65 cps, a Pulmac strength index o:E about 83 and a Kajaani weighted average ~iber length o~ about 0. 71 mm. The pulp is beaten and its physical properties were measured. The physical properties o~ the resulting pulp are compared with a commercial kraft pulp obt~ nP~ ~rom maple. Results in Table 7 ~l~mnn~trate that the pulp has superior physical properties than unmodified organosolv pulp and that its physical properties such as breaking length are better than kra~t pulp.
Table 7 Alcohol/ Alcohol Kraft Sulfite PFI mill revolutions 4300 4000 2500 Bulk, mL/g 1. 45 1.42 .46 CA 02221619 1997-12-0~
WO 96/41052 PCT~US96iO9~2 Tear Index 6.1 4.9 6 .2 (mNm2 /g) Burst index 2.95 2.3 2.95 (kPam2/g) Breaking Length 5. 6 4.8 5.2 (km) Example 8 In this ~mrle, jute was pulped with sodium sulfite. Table 8 shows the results obt~;nP~ when pulping jute in alcohol/water with and without sodium sulfite present at 195~C. As can be observed the presence of the additive resulted in higher viscosity and lower kappa numbers, i.e. improved selectivity is achieved.
Table 8 also shows the strength properties of bleached and unbleached jute pulps at 300 CSF. The use of additives significantly ilLL~oved the pulp strength o~
both the unbleached and bleached pulps. Table 9 shows the bleaching conditions used ~or jute and the results show that when an additive was used, a lesser amount o~
bleaching chemicals can be used.
Table 8 No additive 4~ N~2S03 Alcohol 70 60 (~) (v/v) ,, Pulp yield 68.8 66.7 (~) Kappa No. 35.0 18.4 Viscosity 33.2 72.5 (cps) Unbleached Burst index 2 5.5 (kPam2/g) Tear Index 5.8 19.4 (mNm2 /g) Breaking Length 4.2 7.9 (km) Bleached Burst index 1.7 5. 2 (kPam2/g) Tear Index 6.7 18.0 (mNm2/g) Breaking Length 3.8 7.2 (km) Table 9 Stage Consistencv Time Temp Charge (~) (~) (hr) (~C) * **
E (NaOH) 10 0.5 70 3 3 D1 (Cl02) 12 3 70 2.88 1.93 E (NaOH) 12 2 70 2 1.8 D2 (Cl02) 12 3 70 0.8 0.8 CA 02221619 1997-12-0~
Final Brightness 88. 7 88.5 I
Brightness after D1 60 65 *: pulped without additive **: pulped with additive Example 9 In this example, additives were used to pulp seed flax whole stalks. The seed ~lax whole stalks were separated into core and bast fractions by grinding in a blender in a dry state. As a result of this grinding and of the centrifugal forces due to the blender action, the core and bast fractions were separated, with the core forming a lower layer and the bast a top layer. The conditions used for pulping and the results obtained for bast and core fractions are presented in Table 10 The data shows that high selectivity (high viscosity, low kappa number) for core and bast pulping was achieved when sodium bisulfite is used. No acceptable pulp could be obt~;ne~ ~rom the core without the use of additives.
Table 10 Bast Bast Core Sodium Bisulfite (~) 0 3 3 Temperature (~C) 195 195 185 ~ 25 Time (min) 60 30 120 Ethanol:Water 60:40 60:40 40:60 Yield (~) 64 69 46 Kappa No. 63 30 64 CA 0222l6l9 l997-l2-05 W O 96/41052 -28- PCT~US96/09942 Pulps produced in the presence o~ sodium bisul~ite were bleached by EoDED using conditions in Table 11. A ~inal bri~htness o~ 83 1 and viscosity o~
30.2 cps was obt~;n~ ~or the core. For the bast, 84.5 brightn~Fs and 32.6 cps was obt~;n~. The strength properties obt~; n~ are shown in Table 12.
Table 11 Stage Temp Consistency Time Char~e (~) (~C) (~) (min) Core Bast Eo 70 12 30 3 3 D1 70 12 180 5.9 5 9 D2 70 12 180 1. 2 1.2 Table 12 Core Bast (mls) Bulk 1.33 2.04 (cm3/g) Burst index 3.3 3 9 (kPam2 /g) Tear Index 4 5 15.1 (mNm2 /g) -CA 0222l6l9 1997-l2-0~
W O96/41052 PCT~US961'~3312 Breaking Length 7.0 6.3 (km) Example 10 A mixture o~ spruce and balsam ~ir was pulped using alcohol water in the presence o~ sodium bisul~ite.
Processing conditions used per batch were as follows: 30 grams of wood (oven dried basis), 240 mL o~ solvent (made up o~ SDA-1 alcohol and water in a ratio o~ 60:40 v/v and taking into account the water present as moisture in the wood) and 1.2 grams o~ sodium bisul~ite were put together in a Parr bomb (Parr Company, Moline, Illinois) and were heated to 195~C i~or 120 minutes.
Then the cooked chips were de~iberized and then washed using 50:50 alcohol:water. Pulp was obt~neA with a yield o~ 57~ on oven dried wood. It had a kappa number o:E 73 mL/g and a viscosity o~ 51 cps. The kappa number could be reduced to 51 mL/g a~ter a 2 hour alkali extraction at 70~C using 4~ NaOH on pulp and a 10 consistency. At 532 CSF the pulp had the properties reported in Table 13.
Table 13 Bulk 1.45 (cm3/g) Burst index 6.9 (kPam2/g) Tear Index 13. 5 (mNm2/g) Breaking Length 9.8 (km) W O 96/41052 PCTnUS96/099~2 This invention and many o~ its attendant ad-vantages will be understood ~rom the foregoing descrip-tion, and it will be apparent that various modi~ications and changes can be made without departing ~rom the spirit and scope of the invention or sacri~icing all o~
its material advantages, the processes herein~e~ore described being merely pre~erred embo~;m~nts.
Claims
2. The method of claim 1 comprising the steps of:
(a) steaming said fibrous plant materials to heat said materials and to remove any air trapped therein;
(b) wetting said steamed material with said cooking solvent;
(c) feeding said wetted steamed material and pressurizing said wetted material;
(d) introducing said wetted steamed material into an impregnation vessel and impregnating said wetted, steamed material with said additive mixture to form a fibrous plant materials slurry; and (e) feeding said slurry into an extractor and extracting said slurry with said cooking solvent to produce said pulp and spent liquor.
3. The method of claim 2 which further comprises the step of (f) withdrawing said pulp; and (g) recovering said pulp.
4. The method of claim 3 which further comprises the step of (h) withdrawing said spent liquor from said extractor, said spent liquor comprising lignin, co-products and said alcohol.
5. The method of claim 4 which further comprises the step of (i) recovering said lignin, said co-products and said alcohol.
6. An apparatus for pulping fibrous plant materials with a cooking solvent comprising an aqueous solution of a lower aliphatic alcohol and an additive mixture comprising at least one additive selected from the group consisting of sulfite salts, bisulfite salts and caustic, said apparatus comprising:
(a) steaming equipment to steam and heat said fibrous plant materials and to remove any air trapped therein;
(b) a feeder to pressurize said wetted material;
(c) an impregnation vessel to impregnate said wetted and steamed material with said additive mixture to form a fibrous plant materials slurry; and (d) an extractor to extract said slurry with said cooking solvent to produce said pulp and spent liquor comprising lignin, co-products and said alcohol.
7. The apparatus of claim 6 which further comprises (e) pulp recovery equipment to recover said pulp.
8. The apparatus of claim 7 which further comprises (f) liquor recovery equipment to recover said spent liquor, said lignin, co-products and alcohol.
9. A pulp manufactured in accordance with
Claim 1.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US47290995A | 1995-06-07 | 1995-06-07 | |
| US08/472,909 | 1995-06-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2221619A1 true CA2221619A1 (en) | 1996-12-19 |
Family
ID=23877386
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002221619A Abandoned CA2221619A1 (en) | 1995-06-07 | 1996-06-07 | Modified organosolv pulping |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP0830475A4 (en) |
| JP (1) | JPH11507416A (en) |
| AU (1) | AU6270596A (en) |
| BR (1) | BR9609008A (en) |
| CA (1) | CA2221619A1 (en) |
| NO (1) | NO975672L (en) |
| WO (1) | WO1996041052A1 (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI122838B (en) | 2005-03-31 | 2012-07-31 | Metso Paper Inc | A process for making pulp from lignocellulosic material |
| CA2651628C (en) | 2006-05-08 | 2015-01-06 | Biojoule Ltd. | Process for the production of biofuel from plant materials |
| EP2193138A4 (en) | 2007-08-31 | 2010-11-17 | Biojoule Ltd | Lignin and other products isolated from plant material, and methods and compositions therefor |
| US20110104773A1 (en) * | 2008-02-27 | 2011-05-05 | Green Resources Technology Limited | Processing method for fractionally converting pennisetum hydridum into fuel ethanol with co-production of electricity generation and paper pulp |
| ES2862178T3 (en) | 2010-06-26 | 2021-10-07 | Virdia Llc | Sugar mixtures production methods |
| IL206678A0 (en) | 2010-06-28 | 2010-12-30 | Hcl Cleantech Ltd | A method for the production of fermentable sugars |
| IL207329A0 (en) | 2010-08-01 | 2010-12-30 | Robert Jansen | A method for refining a recycle extractant and for processing a lignocellulosic material and for the production of a carbohydrate composition |
| AT510346A1 (en) * | 2010-09-02 | 2012-03-15 | Annikki Gmbh | lignin |
| IL207945A0 (en) | 2010-09-02 | 2010-12-30 | Robert Jansen | Method for the production of carbohydrates |
| AT510812A1 (en) * | 2010-10-29 | 2012-06-15 | Annikki Gmbh | METHOD OF OBTAINING LIGNIN |
| PT106039A (en) | 2010-12-09 | 2012-10-26 | Hcl Cleantech Ltd | PROCESSES AND SYSTEMS FOR PROCESSING LENHOCELLULOSIC MATERIALS AND RELATED COMPOSITIONS |
| GB2505148B8 (en) | 2011-04-07 | 2016-12-07 | Virdia Ltd | Lignocellulose conversion processes and products |
| GB2517338B (en) | 2012-05-03 | 2020-03-25 | Virdia Inc | A method for fractionating a liquid sample |
| US9657146B2 (en) | 2013-03-14 | 2017-05-23 | Virdia, Inc. | Methods for treating lignocellulosic materials |
| CN105358608B (en) | 2013-05-03 | 2018-11-16 | 威尔迪亚公司 | The method for being used to prepare heat-staple lignin fraction |
| EP2992041B1 (en) | 2013-05-03 | 2020-01-08 | Virdia, Inc. | Methods for treating lignocellulosic materials |
| DK3072117T3 (en) | 2013-11-20 | 2019-01-07 | Annikki Gmbh | Method for fractionating lignocelluloses |
| EP3527577A1 (en) | 2014-07-09 | 2019-08-21 | Virdia, Inc. | Methods for separating and refining lignin from black liquor and compositions thereof |
| DE102015108222A1 (en) * | 2015-05-26 | 2016-12-01 | Hochschule Magdeburg-Stendal | Process for the separation of lignin from biomass and substances derived therefrom |
| WO2017029685A2 (en) * | 2015-08-19 | 2017-02-23 | Godavari Biorefineries Limited | A process for producing cellulose with low impurities from sugarcane bagasse |
| FR3049620B1 (en) * | 2016-04-05 | 2020-06-12 | Swm Luxembourg Sarl | PLANT PAPER COMPRISING FIBERS FROM A PLANT |
| FR3121451A1 (en) * | 2021-03-30 | 2022-10-07 | IFP Energies Nouvelles | Ligno-cellulosic biomass treatment process |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB436090A (en) * | 1934-04-04 | 1935-10-04 | British Celanese | Improvements in or relating to the manufacture of cellulose from lignocellulosic materials |
| DE3212767A1 (en) * | 1982-04-06 | 1983-10-06 | Nicolaus Md Verwaltungsges | METHOD AND REACTOR FOR CONTINUOUSLY UNLOCKING PLANT FIBER MATERIAL |
| ZA92566B (en) * | 1991-02-01 | 1993-07-28 | Alcell Tech Inc | Pulping of lignocellulosic materials and recovery of resultant by-products. |
-
1996
- 1996-06-07 AU AU62705/96A patent/AU6270596A/en not_active Abandoned
- 1996-06-07 EP EP96921489A patent/EP0830475A4/en not_active Withdrawn
- 1996-06-07 BR BR9609008-1A patent/BR9609008A/en not_active Application Discontinuation
- 1996-06-07 JP JP9502102A patent/JPH11507416A/en active Pending
- 1996-06-07 CA CA002221619A patent/CA2221619A1/en not_active Abandoned
- 1996-06-07 WO PCT/US1996/009942 patent/WO1996041052A1/en not_active Application Discontinuation
-
1997
- 1997-12-05 NO NO975672A patent/NO975672L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11507416A (en) | 1999-06-29 |
| NO975672L (en) | 1998-02-04 |
| AU6270596A (en) | 1996-12-30 |
| NO975672D0 (en) | 1997-12-05 |
| WO1996041052A1 (en) | 1996-12-19 |
| EP0830475A4 (en) | 1998-08-26 |
| EP0830475A1 (en) | 1998-03-25 |
| BR9609008A (en) | 1999-12-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2221619A1 (en) | Modified organosolv pulping | |
| US4248662A (en) | Oxygen pulping with recycled liquor | |
| US8475627B2 (en) | Process of treating a lignocellulosic material | |
| EP0796367B1 (en) | Production of prehydrolyzed pulp | |
| US4486267A (en) | Chemithermomechanical pulping process employing separate alkali and sulfite treatments | |
| US5041192A (en) | Supercritical delignification of wood | |
| JP3348387B2 (en) | Pulp production by formic acid-added acetic acid. | |
| US4869783A (en) | High-yield chemical pulping | |
| CA2378927C (en) | Preparation of chemical pulp and xylose, utilizing a direct acid hydrolysis on the pulp | |
| US4091749A (en) | Alkaline pulping of lignocellulosic material with amine pretreatment | |
| JP2588495B2 (en) | Method for producing high yield and high bleaching pulp for papermaking | |
| US4826568A (en) | Process for delignification of cellulosic substances by pretreating with a complexing agent followed by peroxide prior to kraft digestion | |
| EP0635080B1 (en) | Method of producing pulp | |
| US4113553A (en) | Sodium sulfide pulping with hydrogen sulfide generation | |
| US6569285B2 (en) | Process for gas phase pretreating of lignocellulosic containing material | |
| US3874991A (en) | Polysulfide impregnation of lignocellulosic materials in a continuous digester | |
| US3520773A (en) | Alkaline pulping processes with chemical pretreatment | |
| MXPA97009857A (en) | Formation of organosolv pulp modific | |
| AU3256001A (en) | Pulping process | |
| US20230265612A1 (en) | A cooking method | |
| CA1309562C (en) | Chemimechanical pulping process employing sodium carbonate and sodium sulphite |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |