JPH11507416A - Improved organic solvent pulping - Google Patents

Abstract

(57) Abstract: A method and apparatus for producing pulp (95) from fibrous plant material (10). The method comprises pulping fibrous material with a lower aliphatic alcohol cooking solvent and an additive mixture comprising at least one additive selected from the group consisting of sulfites, bisulfites and caustic (100). Consists of

Description

Description of the Related Art Improved Organic Solvent Pulping Background Art In recent years, environmental concerns have increased and the production of low kappa number pulp has been directed toward reducing the amount of bleaching chemicals used in bleaching pulp. Was. Kraft hardwood pulp has a kappa number in the range of about 12 to 20. Meanwhile, U.S. Pat. S. U.S. Pat. No. 4,764,596 or Diebold et al. S. In organic solvent pulp obtained by an autocatalytic organic solvent pulping method such as the ALCELLR method described in Patent 4,100,016, about 50% maple wood, 35% birch wood and 15% poplar wood are used. In the case of pulping of a mixture of hardwoods of North America made of wood, the kappa number usually ranges from about 20 to 30. In general, the bleachability of organic solvent pulp is excellent, especially because of the structure of the residual lignin and the low metal content of the pulp. The low metal content results in a highly selective response to delignification by alkaline extraction and / or oxygen and other bleaching agents. As a result, the Kappa number is reduced and the gloss is increased without significant strength loss. However, for some wood species and raw materials, the strength may be reduced depending on the conditions necessary to obtain a bleachable Kappa number. As a result, selective delignification and glossing may be performed, but the pulp strength properties of the final bleached product may be less than optimal. In the case of autocatalytic organic pulping of dense hardwoods such as maple wood, the cooking conditions that result in a Kappa number of 40 to 50 are relatively harsh. Such steaming conditions generally cause deterioration of pulp strength. Similarly, softwoods such as pine and fir can achieve similar kappa numbers under more severe conditions than dense hardwoods, and the resulting bleachable pulp has a higher pulp strength. Lower. For example, when pulping sugarcane squeezed grains using autocatalytic organic solvent pulping, pulping is stopped at a Kappa number above 50 to prevent fiber degradation, followed by alkaline extraction to a Kappa number. To a bleachable level of about 15 to about 35. Schroeter et al. Propose a two-stage organic solvent pulping method in Tappi Journal, pp. 197-200 (1991), "Possible Reactions to Lignin in Organic Tissue Pulping Methods". The first stage is the acid stage, and the second stage adds more than 20% by weight caustic to the wood. This two-stage organic solvent pulping process has not found practicality in continuous industrial scale operation. (Tappi Pulping Minutes, Orlando, Florida, November 1991) Morton et al., PCT Int. In application WO 8,201,568, softness with improved properties compared to pulp made using soda or alcohol alone, using ethanol for the alkaline pulping of 20% by weight NaOH on wood. A method for producing wood pulp is proposed. These ethanol pulps were inferior in strength and delignification to soft wood kraft pulp. Valladares et al., Progress Report No. 15 Tappei Press, pp. 23-28 (1984), "Pulping of sugarcane crushed grains with a mixed solution of ethanol and water in the presence of sodium hydroxide and anthraquinone" using sugarcane crushed grains as crude material. Suggest adding a small amount of sodium hydroxide to a mixture of about 60% to 40% ethanol / water and a small amount of anthraquinone. Ahmed et al. In the "Steam Explosion Steaming of Poplar Pretreated with Methanol-Water / Alkaline Water" at the San Francisco, 1989, 1989 / Chicago Symposium on Forest Products Symposium, 1989/1990. It proposes the application of a steam explosion pulping method involving pretreatment of poplar chips with a solution of methanol-water / alkaline water containing sodium hydroxide. The kappa number of the pulp produced is high and the pulp is similar to chemically processed hot pulp and is not sufficiently bleachable. Patt et al. In the 6th ISWPC pp. 609-617, "Reaction of Alkali Sulfite, Anthraquinone, Methanol Lignin and Carbohydrate in Pulping", in a solvent containing 15% methanol, containing more than 5% It is proposed to use more than% sulfite and a catalytic amount of anthraquinone. The resulting pulp is excellent in physical properties such as quality, yield and bleachability, but requires a sophisticated process for recovery of chemicals and solvents due to the large amount of chemicals used. Bublitz et al. In the 1983 Pulping Conference, pp. 423-427, "Methanol, the Role of Methanol in the Acid Sulphite Pulping Process", proposes the addition of methanol to the acid sulphite pulping process. The overall pulping time is reduced from 5-6 hours to 1 hour or less. The low degree of wood carbohydrate decomposition results in high pulp yields of about 60% to about 65%. The strength of the resulting fibers is lower than the strength of the kraft pulp, plus very high levels of SO _Two Are consumed in this process. Chen et al., 1990 Conclusion of Solvent Pulping, pp. 663-671, "Conceptual SO. _Two -Ethanol-water Pulp properties for mills and economics of mills _Two Proposes the application of an alkaline pretreatment of the wood before pulping with ethanol-water. As a pretreatment step, vacuum impregnation of wood chips in aqueous ethanol containing sodium hydroxide is employed. This two-stage organic solvent method produces soft wood pulp with a higher yield of about 6% to about 10% than kraft pulp and single-stage organic solvent pulp. This pretreatment step also reduces the Kappa number by about 6 units as compared to one-step organic solvent pulping. The strength of this pulp, especially the tear strength, is lower than kraft pulp. Primakov et al., Khim. Drev. In "Treatment of the liquid after pulping with a water-alcohol solution" on page 23-5 (1982) of (4), in a 1: 1 saturated alcohol-water mixture containing 40% to 75% spent sulfurous acid solution, the SO _Two And a method of obtaining a result having a kappa number of 20.8 to 25 and a breaking length of 4900 to 5500 m. The addition of waste liquid reduces the consumption of alcohol during cooking. Sakai is described in Shipa Gykyo, Vol. 48, no. 8 (1994), "Delignification of Organic Solvents" on page 11-20, discloses a method of adding bisulfite to an isopropyl alcohol-water solvent system. Large amounts of additives such as 18% magnesium bisulfite are used at a cooking time of 1 hour at 165 ° C. The resulting pulp has a high kappa number and the product is a semi-chemical pulp rather than a fully bleachable chemical pulp. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing pulp by pulping with a cooking solvent comprising an aqueous solution of a lower aliphatic alcohol and one or more additives. Additives are added in small amounts that do not require a separate process for their recovery or regeneration. One example of an additive is bisulfite, which is added to maple wood and mixed hardwood in a range from about 0.05% to about 6%. Another example is sulfite, which is added to maple wood and mixed hardwood in the range of about 0.05% to about 6%. Sulphite may be added to the pomace and jute alone in the range of about 2% to about 4%, or in combination with sodium hydroxide in the range of about 1.3% to about 4%. BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1, 2 and 3 are flow charts of the process of the present invention. DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for improving the selectivity of delignification and increasing the rate of delignification over that obtained in an autocatalytic organic solvent pulping step. Additives such as sodium hydroxide, sodium sulfite, ammonium and magnesium bisulfite, and sodium bisulfite can be used to improve selectivity. The cooking solvent may comprise from about 30% (by weight) to about 92% of a water-miscible lower aliphatic alcohol of 1-4 carbon atoms (eg, methanol, ethanol, isopropanol or tertiary butanol) and from about 8% to about 92%. It may consist of up to 70% water. The cooking solvent may further comprise the alcohol and alcohol / water filtrate recovered from the process, optionally with a small amount of a water-soluble strong or organic acid such as a small amount of an inorganic acid (eg, hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid). (Eg, oxalic acid, preferably acetic acid, formic acid or peracid), or a minor amount of an inorganic salt. The resulting steamed solution can be a single species or combination of hardwoods such as sugarcane bagasse, sugarcane hull chips, maple, hippo, poplar, oak, ash, linden, jute, flax, straw, kenaf, reed, and e.g., spruce and Soft wood, such as balsam fir mixtures, can be used to pulverize a wide range of raw materials. Bleaching pulp can be obtained with low kappa number, high pulp strength and high yield. By using the additives of the present invention, improved pulping selectivity can be obtained. It is believed that the bisulfite additive results in partial sulfonation of lignin present in the feed. Sulfonation can generally prevent recondensation reactions that would prevent the pulp from reaching very low Kappa numbers. It is also believed that the sulfonated products act as surfactants and contribute to the removal of the organic solvent lignin. Further, it is believed that the redox side reactions in the presence of sulfite and bisulfite additives provide a catalytic effect. In general, additives such as sulfites increase the pH and the cellulose fraction at low acidity and high hemicellulose retention, as evidenced by the higher viscosity and higher hemicellulose content of the resulting pulp. ) Can occur. In general, sulfites and bisulfites can be added as sodium, magnesium or ammonium sulfites and bisulfites to a wide range of fibrous plant materials such as soft wood, maple, flax, straw and hardwood mixtures. . Alkali can likewise be added alone or in combination with either sulfites or bisulfites. The fibrous plant material can be pulped according to the description of Diebold or as shown in FIG. By adding this additive to the cooking solvent, a uniform pulp cooking can be obtained, in which case the pulp sorting rejection is lower and the pulp kappa number is lower. For example, bisulfite can be added to sugar cane residues such as maple and mixed hardwood, sugar cane bagasse at levels from about 0.05% to about 6% by weight of fibrous plant material. The bisulfite can be added to the cooking solvent consisting of alcohol and water at a weight percent of about 30% to about 92%, preferably about 40% to about 55%. The fibrous plant material can be pulped according to the teachings of Diebold or using the process shown in FIG. Using the Diebold process, the primary extraction time is from about 45 minutes to about 210 minutes, from about 190 ° C. to about 200 ° C., from about 100 ° C. to about 155 ° C. for the secondary extraction, and For the third extraction, it is from about 100 ° C to about 124 ° C. The pH of the cooking solution during the primary extraction is from about 5 to about 5.4. The resulting product pulp had low kappa number and high yield delignification. In another preferred form, the sulfite additive can be used for pulping jute, flax, reed, sugar cane residue, straw, maple and mixed hardwood. When pulping maple and mixed hardwood, the amount of sulfite used is from about 0.05% to about 6% by weight of the raw material. The fibrous plant material can be pulped according to the teachings of Diebold or using the process shown in FIG. Using the Diebold process, sulfites can be added to the cooking solvent described above in the primary extraction step. The time for the primary extraction is from about 60 minutes to about 180 minutes, at a temperature from about 175 ° C to about 204 ° C. The pH of the cooking solution during the extraction is from about 4.4 to about 6.3. In another preferred form, sulfite additives, alone or in combination with NaOH, can be used for bagasse pulping. When used alone, the amount of sulfite is from about 2% to about 4% by weight of bagasse. When used alone, the amount of alkali is from about 1.3% to about 2.6% by weight of bagasse. Sulfites and alkalis can be used in combination. When the two additives are used in combination, the amount of sulfite is from about 2% to about 4% and the amount of alkali is about 1. From 3% to about 4%, and the amount of each additive can be adjusted so that the pH of the cooking solution during the preheating stage is in the alkaline range. When the temperature of the cooking solution reaches its maximum, the pH reaches a level of about 6 to about 8 and becomes slightly acidic as the primary extraction proceeds. The fibrous plant material can be pulped according to the teachings of Diebold or using the process shown in FIG. On the other hand, sulfite additives, alone or in combination with alkalis, can be used for jute pulping. When used alone, the amount of sulfite is from about 2% to about 4% by weight of the jute. When used alone, the amount of alkali is from about 1.3% to about 2.6% by weight of the jute. A combination of a sulfite and an alkali can also be used. When the two additives are used in combination, the amount of sulfite is from about 2% to about 4%, the amount of alkali is from about 1.3% to about 4%, and the amount of each additive is The pH of the cooking solution during the preheating stage can be adjusted to be in the alkaline range. As the temperature of the cooking solution reaches its maximum, the pH reaches a level of about 6 to about 8 and becomes slightly acidic as the primary extraction proceeds. The fibrous plant material can be pulped according to the teachings of Diebold or using the process shown in FIG. In another preferred form, the alkali can be used in the pulping of sugarcane residue, maple and mixed hardwood in a range from about 1.3% to about 2.6%. The fibrous plant material can be pulped according to the teachings of Diebold or using the process shown in FIG. Using the Diebold process, the pH reaches a level of about 5 to about 7. The process of the present invention is schematically illustrated in FIG. A fibrous plant material 10 having a moisture content of about 5% to about 60% is steamed to a temperature ranging from ambient temperature to about 120 ° C. by supplying steam 20 to the plant material in the steaming device 15. be able to. The material is cooked for about 0.5 to about 120 minutes to heat the material and remove any air trapped therein. Subsequent to the steaming, the steamed material is wetted with the above-mentioned steaming solvent 30 and introduced into a feeder (feeding device) 25. The material in the feed device 25 can be pressurized from ambient pressure to the pressure in the impregnation vessel 45 or the pressure in the extractor 100. Following the material feed, the material is impregnated with the additive mixture 40 in the impregnation vessel 45. The additive 40 comprises the cooking solvent 30 and any of the above additives mixed therein at the appropriate concentration level depending on the fibrous plant material to be pulped. There, a slurry is obtained. The impregnation time is from about 1 minute to about 120 minutes, and the material is simultaneously heated to about 50 ° C to about 170 ° C. During the impregnation, the slurry can be pressurized to the pressure in the extractor 100. The fibrous plant material slurry from the impregnation vessel 45 is fed to the extractor 100, and a slurry typically comprising about 5% to about 20% solids is pulped in about 45 minutes to about 6 hours. The temperature in the extractor 100 is from about the temperature in the impregnation vessel 45 to about 205 ° C. During pulping, the stream of waste liquid 71 and the pulp slurry 75 can be removed from the extractor 100. The waste liquid 71 can be treated in the liquid recovery device 85 to obtain lignin, co-products and alcohol. The pulp slurry 75 is processed in the pulp collecting device 95 to obtain pulp and alcohol. The invention can be applied to both batch and continuous cooking. In the case of batch cooking, the cooking and feeding steps described above can be carried out according to the teachings of Diebold. The continuous process can be performed according to the structure shown in FIG. 2 in which the steaming device 15 includes the measuring screw 32, the first rotary valve feeder 33, the second rotary valve feeder 34, and the chip gutter tube tank 65. In one embodiment, the fibrous plant material can be pre-steamed in the cooking box 31 by injecting steam at atmospheric pressure. The fibrous plant material is wetted and sent to a metering screw 32 mounted at an angle. Excess water from the steam condensate can be removed in the metering screw 32, and the wet fibrous plant material is sent through a first rotary valve feeder 33, at a temperature from about 50 ° C to about 130 ° C and from about 30 to about 130 ° C. Heating in line 46 by direct steam injection at pressures up to about 100 psig. Line 46 may include a water vapor barrier to prevent alcohol-containing vapors from stagnating in rotary valve feeder 33. The steamed fibrous plant material passes through a second rotary valve feeder 34. The fibrous plant material in the chip trough 65 can be mixed with the steaming solvent 30 and the circulating solvent 50 from the impregnation vessel 45. Following the feed, the additive mixture 40 can be added and the fibrous plant material can be impregnated in the impregnation vessel 45. Within the impregnation vessel 45, the slurry can be pressurized to the operating pressure of the extractor 100. The slurry, which is treated as a cooked mixture, enters the extractor 100 through the inlet 38, while the liquid separator 101 regulates the flow of the mixture entering the extractor 100. Excess cooking mixture liquid overflows from extractor 100 at outlet 39, is circulated through line 57, and is pumped back to impregnation vessel 45. In a preferred embodiment, the above-described liquid separation is performed using a mechanical separation device 101. The slurry of the fibrous plant material is conveyed to the extractor 100 using the mechanical separation device 101 so that the free flowing of the excess steamed mixture liquid is maintained. In addition, the mechanical separation device 101 may include a screen within the separation device 101 within and relative to the top of the extractor 100, as desired in view of the fiber material being pulped and the pulping conditions within the extractor 100. It consists of a mobile screen whose position can be adjusted. On the other hand, if excess cooking mixture liquid overflows the extractor 100 at outlet 39, it is circulated through line 57. The cooked mixture liquid passes through a liquid surge tank 68. The liquid surge tank 68 is equipped with a level gauge and controls the overflow level of the cooking mixture liquid. The liquid surge tank 68 is capable of separating non-condensable gases from the cooked mixture and may include a vent connected to a heat exchanger, for example, a cold water condenser. Any excess vapor from the liquid surge tank 68 is condensed and can be circulated to the solvent recovery column 14 and circulated with the solvent for reuse. Line 57 includes a heat exchanger 69 that can operate by lowering the temperature of the cooked mixture to a level such that the liquid in the cooked mixture does not flash as the cooked mixture passes through a pressure reducing device 70 (eg, a pressure reducing valve or turbine). be able to. The cooking mixture can be circulated through the impregnation vessel 45, and the vacuum 70 can be operated to reduce the pressure of the cooking mixture in the line 55, ie, from 650 psig to about 20-650 psig. In a preferred embodiment, the pressure in the tip trough 65 can be within the extractor 100 pressure, ie, in the range of about 150 to 650 psig. The impregnated fibrous plant material enters the extractor 100 and can be extracted by steaming with the solvent 36 supplied to the extractor 100 through the inlets 52 and 53. The solvent 36 consists of an appropriate amount of the cooking solvent 30, together with the alcohol introduced in 7 and the alcohol recovered from the co-product recovery system and the alcohol / water filtrate from the countercurrent washing device 77. The solvent contained in the line 36, together with the pulp exiting the extractor 100 at the outlet 41, can be heated in the pulp washing device 77 by heat exchange. The type of extractor used is not critical, but should be applicable to continuous pulping of the cooked mixture. The size of a typical extractor depends on the required capacity of the extractor. As shown in FIG. 3, extractor 100 can operate in a continuous co-current / counter-current mode and at a pressure range of about 150 to about 650 psig. Such an extractor consists of a sequence reaction zone and means for adding and removing solvent. The latter may be in the form of a liquid extraction screen with a wiper or other cleaning device to prevent clogging of the screen, for example a steam press. The cooked mixture passes through extractor 100 and is sequentially exposed to six reaction zones. By using this special extractor arrangement, further alcohol impregnation of the fibrous plant material takes place in the separation zone (a) at a constant temperature of about 50 ° C. to 170 ° C. for about 2 to about 20 minutes. In separation zone (a), the steam headspace is kept above the level of the fibrous plant material at the level of the solvent in the cooking mixture. Excess solvent is removed through outlet 39 and circulated as described above. As the cooked mixture passes through preheat zone (b) and is heated from about 150 ° C. to 180 ° C. for about 50 minutes, the temperature of the cooked mixture increases. Heating of the cooking mixture in the preheating zone (b) is achieved by circulating the cooking solvent countercurrently through a steam-heated heat exchanger (typically of the tube and shell type). The temperature of the heat exchanger is maintained at a high enough temperature to heat the cooked mixture from about 150 ° C to 180 ° C in the preheating zone (b). The preheated cooking mixture is further heated in the primary extraction zone (c) to about 175 ° C to 205 ° C and is subjected to cooking and extraction conditions for about 70 minutes to about 180 minutes. The cooking mixture is heated in the primary extraction zone (c) by circulating the cooking solvent co-currently through the heat exchanger as described above. In zone (c), a hot ethanol / water extract or black liquid is formed during the cooking and extraction process. The hot black liquid containing lignin, hemicellulose, other carbohydrates and extracts (eg, resins, organic acids, phenols and tannins) and spent additives can be separated from the cooked mixture through line 71 and subsequently Processed to recover lignin and co-products of the pulping process. The amount of additive used in this step is generally low enough so that separate recovery and regeneration steps for recovering the additive are not required. The cooked mixture is further cooked and extracted in the secondary extraction zone (d) at a temperature of about 100 ° C to 190 ° C for about 60 minutes. By recirculating the cooking solvent in the heat exchanger as described above, the temperature of the secondary extraction zone (d) is cooled. The steamed mixture is cooled and the temperature of the heat exchanger is maintained at a level sufficient to maintain the temperature of the secondary extraction zone (d) at about 100 ° C to 155 ° C. The cooked mixture is further cooked and extracted in the tertiary extraction zone (e) for about 45 minutes and the mixture is heated to about 100 to 120 ° C. by recirculating the cooking solvent cocurrently through the heat exchanger as described above. Cool to temperature. The steamed mixture is further cooled in a cooling zone (f) from about 70 ° C. to 100 ° C. for about 22 minutes and ground into pulp in mixing apparatus 102. Cooling of the cooked mixture in cooling zone (f) is achieved by mixing the mixture with the solvent introduced countercurrently at inlet 52 and cocurrently at inlet 53. The solvent mixture consists of make-up alcohol, the regenerated alcohol from the alcohol and co-product recovery step and the alcohol / water filtrate from the washing unit 77. The pulp exits the extractor 100 via line 41 and is processed through a pulp collector 95 consisting of a storage tank 74, a washing device 77, a storage tank 9 and a pulp sieve 10. As shown in FIG. 2, the pulp is transferred to a storage tank 74 at a pressure sufficient to maintain the pulp strength, which may be atmospheric. Using the alcohol recovered through line 7 with the cooking solvent 30, the pulp can be washed in a washer 77 and cooled to a temperature below 80 ° C. while simultaneously removing and regenerating additional lignin through line 36. The pulp can be further washed in the washer 77 with water introduced through line 35 and cooled to a temperature of about 40 ° C to 70 ° C. After washing the pulp, the pulp can be sent to storage tank 9 and pumped through pulp screen 10. The pulp is then processed appropriately for normal pulp operations, bleaching and papermaking procedures. In one bleaching technique, pulp, referred to as brown stock at this stage, is delignified by treatment in an oxygen delignification stage or an alkaline extraction stage. The resulting filtrate 110 can be recycled to the additive mixture 40 and mixed with the cooking solvent 30. In this way, the sodium typically present in filtrate 110 can be mixed with sulfur dioxide to produce sodium bisulfite and / or sodium sulfite, and used for pulping. In one embodiment, the oxygen delignification of the pulp is accomplished by first mixing the pulp slurry with a sodium hydroxide (alkaline) solution at a concentration of about 9 to 15% by weight of the pulp solids, and further mixing with oxygen gas under high shear. It can be performed by mixing. The amount of alkali added is preferably from about 2 to 8%, more preferably from about 3 to 6%, based on% (w / w) of absolutely dry (od) pulp. The temperature of the reaction mixture is between about 60C and 110C, more preferably between about 70C and 90C. Also, the oxygen pressure in the bleaching vessel is preferably maintained at about 40 to 110 psig for oxygen delignification, more preferably about 80 to 100 psig, and about 32 to 60 psig for delignification using oxidative extraction. The reaction time with oxygen is preferably from about 6 to 60 minutes, more preferably from about 40 to 50 minutes. The filtrate 110 from the oxygen delignification is mixed with the SO 4 prior to mixing with the additive mixture 40. _Two Can be treated with gas. If necessary, excess water can be removed from filtrate 110 using methods known to those skilled in the art. Extractor 100 provides a black liquor 71 from which lignin, co-products and alcohol can be recovered in liquid recovery device 85 as described by Lora. The present invention is further described by the following examples. Example 1 In this embodiment, sugarcane bagasse is steamed using a method of adding sodium hydroxide and sodium sulfite alone and in combination. The concentration of the cooking solvent was 60% by weight ethanol at 175 ° C. and at a liquid / bagasse ratio of 10: 1. The conditions are summarized in Table 1. The results obtained indicated that, for the same kappa number or autocatalytic organic solvent pulp, the additive provided a high pulping yield and pulp viscosity. Example 2 Sugarcane bagasse was pulped in a pilot plant using a conventional autocatalytic organic solvent process and by addition of sodium hydroxide and sodium sulfite. Table 2 summarizes the results obtained in both cases. The pilot plant data confirmed the results obtained on a bench scale. This improved process gave higher pulp yields and lower kappa numbers than the normal process. Further, it was observed that increasing the severity of the cooking conditions when using additives increased the viscosity. This unexpected phenomenon is probably the result of preferential removal of lower molecular weight hemicellulose than cellulose as the severity of the cooking increases. *: Normal or improved process using diffusion bagasse **: Normal process using milled bagasse Example 3 Table 3 compares the properties of sugarcane bagasse pulp produced by the conventional autocatalytic ALCELLR process and pulped in the presence of sodium sulfite and sodium hydroxide. The data showed that the unbleached pulp obtained by the modified process had a higher tear index, breaking length and specific tear strength than the pulp obtained by the conventional process. . Example 4 In this example, maple is cooked by adding sodium hydroxide and sodium sulfite alone and in combination. The temperature was 195 ° C. and the liquid / wood ratio was 8: 1. The conditions are summarized in Table 4. The results obtained indicate that sodium sulfite improved pulp delignification as measured by Kappa number. Example 5 In this example, maple was steamed using sodium carbonate as an additive for a 60:40 ethanol / water cooking liquor and an 8: 1 cooking liquor / wood ratio. The temperature is about 195 ° C. and the cooking time is about 2.5 hours. Sodium carbonate was added as an additive from about 0% to about 6% by weight of the wood. The results obtained were compared with those obtained using sodium sulfite as an additive. Table 5 shows that the pulp obtained with about 4% sodium sulfite has a final pH in the same range as the pulp obtained with about 2% sodium carbonate as an additive. The yields are in the same range for both pulps, and the pulp obtained with sodium sulfite has a Kappa number about 20 units lower than the pulp obtained with sodium carbonate. The results in Table 5 show that in this case, the presence of the additive was the cause of delignification rather than the pH adjustment caused by the additive. Example 6 In this example, a mixed hardwood consisting of about 50% maple, about 35% birch and about 15% poplar was combined with a 60:40 alcohol / water cook and an 8: 1 cook / wood ratio. In contrast, pulping was carried out using about 4% sodium sulfite as an additive. The temperature is about 195 ° C. The conditions are summarized in Table 6 and the results obtained show high pulp viscosity at a given kappa number. Example 7 In this example, maple was pulped using a cooking liquor of 60:40 ethanol / water and about 4% sodium sulfite as an additive for a cooking liquor / wood ratio of 8: 1. The temperature is about 195 ° C. and the cooking time is about 3 hours. The resulting pulp has a Kappa number of about 31, a viscosity of about 65 cps, a Pulmac strength index of about 83, and a Kajaani weight average fiber length of about 0.71. The pulp was beaten and its physical properties were measured. The physical properties of the pulp obtained were compared with commercial kraft pulp obtained from maple. The results in Table 7 indicate that the pulp has better physical properties than the unmodified organocatalytic pulp and that its physical properties, such as break length, are better than kraft pulp. Example 8 In this example, the jute was pulped with sodium sulfite. Table 8 shows the results obtained when pulping jute in alcohol / water at 195 ° C. in the presence and absence of sodium sulfite. As can be observed, the presence of the additive resulted in high viscosity and low Kappa number, ie, improved selectivity was achieved. Table 8 also shows the strength properties of bleached and unbleached jute pulp at 300 CSF. The use of additives significantly improved the pulp strength of both bleached and unbleached pulp. Table 9 shows the bleaching conditions used for the jute, and the results show that less bleaching chemicals can be used when additives are used. *: Pulping without additives **: Pulping with additives Example 9 In this example, seed flax whole stalks were pulped using additives. The whole seed stalk was separated into a core and a bast fraction by crushing in a dry state in a mixer. As a result of this milling and centrifugal force due to the action of the mixer, the core formed the lower layer and the bast formed the top layer, and the core and bast fractions were separated. Table 10 shows the conditions used for pulping and the results obtained for the core and bast fractions. The data show that high selectivity of the core and bast fractions (high viscosity, low kappa number) was achieved when using sodium bisulfite. Without additives, no satisfactory pulp was obtained from the core. Pulp produced in the presence of sodium bisulfite was E ₀ Bleached by DED. For the wick a final brightness of 83.1 and a viscosity of 30.2 cps was obtained. For bast, a lightness of 84.5 and a viscosity of 32.6 cps were obtained. Table 12 shows the strength characteristics. Example 10 The mixture of spruce and balsam fir was pulped using alcoholic water in the presence of sodium bisulfite. The processing conditions used per batch are as follows. 30 grams of wood (dry basis), 240 mL of solvent (made from SDA-1 alcohol and water at a ratio of 60:40 v / v, taking into account water present as moisture in the wood) and 1.2 grams of sulfurous acid The sodium hydrogen was placed together in a Parr vessel (Parr, Moline, Ill.) And heated to 195 ° C. for 120 minutes. The steamed chips were then deflocculated and then washed with 50:50 alcohol: water. Pulp was obtained in a yield of 57% based on the absolutely dry wood. It had a Kappa number of 73 mL / g and a viscosity of 51 cps. With 4% NaOH and 10% strength based on pulp, the Kappa number could be reduced to 51 mL / g after 2 hours of alkaline extraction. At 532 CSF, the pulp had the properties reported in Table 13. From the foregoing description, the present invention and its many advantages are understood, and various modifications and changes can be made without departing from the spirit and scope of the invention or without sacrificing essential advantages. Obviously, the method described here is merely a preferred embodiment.

────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Winner, Stefan Earl             United States Pennsylvania             19061 Boothwin Mattson Low             C 180 (72) Inventor Goyal, Gopal Sea             United States Minnesota 55720 Black             Khet Twenty Third Street             G 1003

Claims (1)

[Claims] 1. Steaming solvent consisting of aqueous solution of lower aliphatic alcohol, sulfite, sulfite water Additive containing at least one additive selected from the group consisting of sodium salt and caustic From a fibrous plant material having a step of pulping the fibrous plant material with an additive mixture A method for producing pulp. 2. (A) The fibrous plant material is subjected to steam treatment, and the plant material is heated and captured by the plant material. Removing the trapped air;     (B) wet-treating the steam-treated plant material with the cooking solvent;     (C) sending the wet-processed and steam-treated plant material and pressurizing it; About     (D) introducing the wet-treated and steam-treated plant material into an impregnation vessel; Impregnating the mixture with the additive mixture to form a fibrous plant material slurry,     (E) sending the slurry to an extractor and extracting the slurry with the cooking solvent; 2. The method of claim 1, further comprising the step of: Pulp manufacturing method. 3. And (f) removing the pulp and (g) recovering the pulp. The pulp manufacturing method according to claim 2, wherein: 4. And (h) waste containing lignin, co-products and said alcohol from said extractor. The pulp manufacturing method according to claim 3, further comprising a step of taking out a liquid. 5. And (i) recovering the lignin, the co-product and the alcohol. The pulp production method according to claim 4, comprising: 6. Steaming solvent consisting of aqueous solution of lower aliphatic alcohol, sulfite, sulfite water Additive containing at least one additive selected from the group consisting of sodium salt and caustic An apparatus for pulping fibrous plant material with the additive mixture.     (A) adding water vapor and heat to the fibrous plant material to remove air trapped in the plant material; Steam processing equipment to leave,     (B) a delivery device for pressurizing the wetted material;     (C) impregnating the steamed and moistened material with the additive mixture to produce a fiber; An impregnation vessel for forming a porous plant material slurry;     (D) extracting the slurry with the cooking solvent to form the pulp, lignin, An extractor for producing a co-product and a waste liquid containing the alcohol. An apparatus characterized in that: 7. And (e) a pulp collection facility for collecting the pulp. The pulp manufacturing apparatus according to claim 6, wherein 8. Further, the waste liquid and the lignin, co-product and alcohol are recovered ( 8. The pulp manufacturing apparatus according to claim 7, further comprising: f) a liquid recovery facility. . 9. A pulp manufactured based on the pulp manufacturing method according to claim 1.