JPH06511043A - Pulping of lignocellulosic raw materials and recovery of generated by-products - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Pulping of lignocellulose raw materials and recovery of generated by-products Cross-reference to related applications This application is filed on August 15, 1988, in the United States Patent Application entitled "Lignin Recovery." This is a partial continuation of Application No. 07/232298, filed on December 1, 1986. Titled “Lignin Recovery,” filed on the 1st and currently U.S. Patent No. 4,764,596. is a divisional application of U.S. Patent Application No. 06/940,460 filed in 1985. The U.S. patent application entitled “Lignin Recovery Process” filed on November 5, 2017 and now abandoned. This is a continuation-in-part of patent no. 06/795069.

Background of the invention The present invention generally relates to the pulping of lignocellulosic raw materials and the pulping process. related to the recovery of produced by-products. More specifically, the present invention provides water-miscible organic solvents ( pulping of lignocellulosic raw materials in (e.g. lower aliphatic alcohols); organic solvents as well as various by-products of the pulping process (e.g. cellulose, lignin, This is related to the recovery and recycling of furfural hemicellulose (and sugar). Ru. The pulping of lignocellulosic raw materials and the recovery of the resulting by-products are continuous processes. Alternatively, it can be carried out in either a batch process.

Wood is treated with organic solvents such as alcohol to remove lignin and hemicellulose from the wood. Processes for separating sugar, sugar, and cellulose fractions are now well known.

See, for example, Kleinert et al., U.S. Pat. No. 1,856,567; See US Pat. No. 3,585,104 to t. Such a solvent pulping process is Processes such as kraft pulping and sulfite pulping that require relatively high capital investment and It appears to be an attractive alternative to the conventional chemical pulping process, which has harmful issues. It will be done.

One solvent pulp disclosed in U.S. Pat. No. 4,100,016 to Diebold et al. The oxidation process removes alcohol without significant air or water contamination or solid waste problems. recovery of cellulose solvents, separation of cellulose and lignin fractions from wood, and cell Particularly attractive in that it provides a very efficient recovery of loin pulp. It is considered to be a thing. This patented process also produces kraft pulp and Yield, kappa number, viscosity, and fiber strength equal to or better than sulfite hardwood pulp and a hardwood pulp with bleaching properties.

However, the solvent pulping of Diebold et al., U.S. Pat. No. 4,100,016 Recovers lignin and other by-products from the alcohol/water black liquor produced by the process. control was relatively inadequate and difficult to control. This US patent The lignin is extracted from the black liquor by first recovering the alcohol from the black liquor (preferably by vacuum stripping). The precipitated lignin is then removed from the bottom or rear of the recovery column (preferably The solids are separated (by sedimentation and concentration and centrifugation of the sedimented solids from the bottom of the recovery tower). It is recovered by However, some of the lignin is inside the recovery tower. It tends to settle out as a sticky tar or gum on surfaces, thereby It contaminates the recovery tower and reduces its efficiency in recovering alcohol from black liquor. rig Nin also tends to precipitate from the bottom of the recovery tower as a sticky amorphous mass; This is difficult to handle and converts this lignin salt into powder. requires considerable grinding.

As a result, solutions such as those disclosed in U.S. Pat. No. 4,100,016 to Diebold et al. Removal of lignin and other by-products from black liquor produced by medium pulping process There is a need for more efficient means to do so.

One method is to remove the rig from the alcohol/water black liquor by diluting it with water. It is accompanied by the precipitation of nin. Rydholm's "Pulping Process J pp. , 672-673. Interscience Publishers, N See York (1971). However, this method This results in a very slow settling rate of lignin, and in some cases very low lignin sedimentation. A stable colloidal suspension is formed, making filtration or centrifugation difficult. Therefore , extracting lignin and other by-products from alcohol/water black liquor in high yield and at high speed. and a relatively simple method for recovery in an easy-to-handle and useful form. There remains a need for a method. Furthermore, the solvent pulping process is superior in strength, whiteness, and cleanliness to kraft paper produced from the same wood species. It produces hardwood pulp comparable to pulp, but such pulping operations The pulp obtained by this method has more residual lignin contained in the pulp. follow Therefore, the pulp obtained from the solvent pulping process is generally measured by the pulp kappa number. In particular, to produce satisfactory bleached pulp with a high residual lignin content determined requires large amounts of bleaching chemicals. Bulk bleaching using conventional bleaching techniques The increased use of chemicals for industrial use means that the treatment or recycling of such chemicals is creating a need to devise new bleaching methods and/or systems for . Additionally, the solvent pulping process produces furfural as a byproduct, which It accumulates in the pulping solvent and interferes with delignification. Therefore, lignocellulose Energy efficiency for pulping raw materials and recovering by-products of the pulping process. methods, apparatus and methods that provide a method, apparatus and /or A significant need exists for the system.

U.S. Pat. No. 4,764,596 to Lora et al. addresses some of the above problems. ing. In the Lora patent, lignin and other by-products of the pulping process are Wood or other lignocellulosic raw materials are treated with water-miscible organic solvents (e.g. ethanol/ It is recovered from the "black liquor" produced when it comes into contact with a water solvent) at high temperature and pressure. Lo The ra process removes a large amount of lignin, including most of the lignin released during pulping. making it possible to successfully recover the organism. Also described herein, Lor Through the improvement of the above-mentioned patent of A et al. By-products can also be recovered, while at the same time reducing the overall energy efficiency of the process. increases, reduces the consumption of solvent required throughout the system, and reduces It has been found that environmentally undesirable waste fluids are significantly reduced or eliminated.

The invention described herein includes the improvements described above and additionally includes black liquor delignification. allows for the recovery of additional by-products and fluids from the pulping process. Make it. The present invention provides a method for removing residual black liquor filtrate produced during lignin recovery. It is possible to not only recover Ruflal, but also to recycle it into the system. This method is used to recover low molecular weight lignin. Furthermore, the specification The book covers not only new bleaching techniques but also Provides recycling of bleach waste filtrate to accelerate delignification and reduce contamination. It is a system that harmonizes.

Summary of the invention The present invention aims to recover lignin and other properties from the pulping of fibrous raw materials. It is something that brings. According to the invention, the solvent and filtrate are recovered and recycled. and reused. This results in considerable solvent and energy savings.

According to the invention, the filtrate from the pulp bleaching and delignification of the invention is continuously Recycling for reuse in pulping, separation and recovery of lignin and other by-products be crushed. As a result of reusing bleach filtrate, delignification is accelerated and operational efficiency is increased. do. The end result is considerable savings in energy, and typically associated with bleaching. It is the elimination or mitigation of pollution caused by pollution.

According to the present invention, lignin includes lignin, hemicellulose, and a water-miscible organic solvent. A diluted black liquor supernatant and a tarry lignin precipitate are formed from a black liquor consisting of a solution of Under conditions which form a diluted residual black liquor containing no precipitated lignin solids , the lignin solids are precipitated by diluting the black liquor with water and acid; Lignin is removed by separating the lignin solids from the residual black liquor supernatant. By collecting, it is recovered.

According to another aspect of the invention, novel lignin is precipitated by the process of the invention.

Preferred lignins have a number average molecular weight of about 800 to 1500 grams per mole and a molecular weight of about 4 due to its low polydispersity and methoxyl content approximately equal to that of natural lignin. It is characterized by

According to another aspect of the invention, novel low molecular weight lignins are obtained.

Preferred lignins have number average molecular weights in the range of less than 500 g/mole. , with a glass transition in the range of about 24° to 60°C, especially when it comes to hardwoods. It is characterized by a molar ratio of syringaldehyde to vanillin of approximately 5.3:1. Can be attached. It is expected that more soluble lignin with a novel structure will be produced. be done.

According to another aspect of the invention, purified furfural product is recovered. This furuf The Ral product contains about 95 to 9896 furfural and about 0. 1 to 059 6% ethanol and approximately 0.1 to 2% water. .

Other aspects of the invention may be found in the remaining portions of the specification, including the drawings and claims. This will become clearer.

Brief description of the drawing Figure 1 shows that cellulose pulp is produced from wood by treating the wood with an alcohol aqueous solution. and recover lignin and other by-products from alcohol/water black liquor. It is a flowchart of the process for.

Figure 2 Precipitates lignin from alcohol/water black liquor from steps in Figures 1.3 and 4. 1 is a schematic cross-sectional view of an example of an apparatus for

Figures 3 and 4 show that cellulose is removed from wood by treating the wood with an alcohol aqueous solution. - from the alcohol/water black liquor produced in the pulping process. 1 shows a flowchart of sequential steps for recovering lignin and other by-products.

Figure 5 shows the production of crude furfurer by liquid/liquid cross-flow extraction followed by pervaporation. 1 is a schematic diagram showing the quality improvement and purification of

Figure 6 shows the crude furfural produced by liquid/liquid countercurrent extraction followed by pervaporation. FIG. 2 is a schematic diagram showing the quality improvement and purification of

FIG. 7 is a flowchart for recovery of low molecular weight lignin.

Figure 8 shows a continuous co-current/counter-current extractor used in the steps of Figures 3 and 4. It is a schematic diagram.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The process shown in Figure 1 begins with the loading of wood chips from hopper 1 into extractor 2. Concerning pulping batches of other fibrous materials. The extractor 2 is a Die At high temperatures (e.g., from about 180° to 210°C) and high pressure (e.g. about 20 to 35 atmospheres) and in the presence of a solvent. It operates with. The solvent has about 40 to 8096 (by volume) carbon atoms and is water miscible. lower aliphatic alcohols (e.g. methanol, ethanol, isopropanol, tert-butanol), 20 to 60% water, and, if necessary, an inorganic acid. (e.g. hydrochloric acid, sulfuric acid, phosphoric acid, or nitric acid) or an organic acid (e.g. oxalic acid, preferably It consists of small amounts of strong water-soluble acids such as acetic acid, formic acid, or peroxyacids).

Preferably, the wood chips in the extractor 2 are preheated with low pressure steam and then used twice. 60% ethanol/40% water, i.e. the primary solvent from primary solvent accumulator 3. The medium contacts the wood chips in the extractor 2. This second solvent is extracted from extractor 2 and the top. The load (e.g. steam heating) is quickly recirculated through the heat exchanger 4 and the temperature of the wood chips is temperature from about 1900 to 200°C in a few minutes (preferably no more than about 5 minutes). let Alternatively, for operations in large plants, times of approximately 5 to 60 minutes Needed. After this first pulping stage is completed, the obtained in extractor 2 The extract, or “black liquor,” is a single-use 60% ethanol/40% water, i.e., secondary solution. Secondary solvent from medium accumulator 6 (preferably heated to 190° to 200°C) ) and enters the recovery feed accumulator 5. lignin, hemicell Other sugars and extracts from loin, wood and ethanol (e.g. resins, organic acids, The black liquor containing phenol and tannins is collected and sent to an accumulator 5. at a temperature of about 180° to 210°C under a pressure of about 20 to 35 atmospheres at and collected. At the end of the black liquor displacement, the secondary solvent in extractor 2 is replaced with fresh solvent. Fresh solvent of 6096 ethanol/40% water from medium accumulator 7 (preferably (heated from 190° to 200°C) to Enter Murator 3. This fresh solvent in extractor 2 is then transferred to the secondary solvent accumulator 6. Once the spill has taken place, extractor 2 is evacuated and this extractor The alcohol-rich vapors are condensed in a water-cooled (“C,W,”) condenser 8; The resulting ethanol/water mixture from condenser 8 is transferred to a new solvent accumulator. 7 is recycled. After extractor 2 is vented, the residual alcohol in the pulp in the extractor is removed. The coal is recovered with low pressure steam and the resulting alcohol/water vapor is It is condensed and collected. After steam recovery, the pulp in extractor 2 is transported by water. Flowed, sent to holding tank 9 and forced out through pulp screen 10 Ru. In that case, the pulp is subjected to conventional pulp processing, bleaching, and papermaking processes. It is suitable. Extractor 2 contains another bag of wood chips from hopper 1. The wood chips can be loaded into the accumulator as described above. 3, 6, and 7 can be contacted with the primary, secondary, and new solvents.

Alternatively, a continuous pulping process is shown in Figures 3 and 4.

First, wood chips (50% moisture) and other fibrous raw materials are placed in a steaming bin 31. Pre-steam heated. Saturated steam is injected into the steaming bin 31 at atmospheric pressure. . The chips are moistened and passed through an angled metering screw 32. . Excess moisture and wet chips from the steam condensate in the metering screw 32 is passed through a first low pressure sluice 33 from about 270°F to about 330°F (13 0° to 170°C) and about 30 to about 100 psig (210 to 69 0 kPa) in line 46 by direct steam injection. Rai The chamber 46 is equipped with a vapor barrier which allows the alcohol-containing vapor to pass through the low pressure sluice 3. 3. Helps prevent a retreat into 3. Steamed wood chips are second low is passed through pressure sluice 34 and mixed in line 45 with the solvent from line 36. will be combined. This solvent is mixed with the chip in a high pressure sluice 35 and the chip is separated. Impregnate in portions. The slurry produced is passed through line 37 and enters inlet 38 and enters the extractor 100. This cooking mixture enters extractor 100 through inlet 38. During this, a liquid separator 101 regulates the flow of the mixture into the extractor 100. Out Excess cooking mixture liquid overflowing from extractor 100 at port 39 is routed via line 57. It is then recycled and sent back to the high pressure sluice 35. High voltage sluice 35? This excess cooking liquor is fed via line 58 into surge tank 50. It is recycled and returned. The cooking mixture in surge tank 50 is routed through line 51. and mixed internally. Any overflow cooking mixture from the surge tank 50 will is fed to line 37 via channel 54.

The partially impregnated chips in extractor 100 are transferred to extractor 1 from inlets 52 and 53. It is digested and extracted with a solvent fed into the 00.

Preferably, this solvent is similar to the solvent used in the process shown in Figure 1. . The concentration of alcohol in the solvent is determined by the appropriate amount of make-up alcohol introduced at step 49. alcohol and vices recovered from this alcohol introduced in step 7. to mix with the alcohol/water source liquid from the biorecovery system as well as the countercurrent washer 44. Therefore, it is adjusted. The solvent contained in line 36 is transferred to extractor 10 at outlet 41. It is heated in the pressure diffuser 47 by heat exchange with the pulp leaving the pulp.

The type of extractor used is not critical, however, it It must be compatible with continuous pulping. Typical extractor size depends on the required capacity of the extractor. For example, the extractor 100 has approximately 20 In the pressure range from 0 to approximately 650 psig (14 to 4,5 MPa) , operating in continuous co-current/counter-current mode. Such an extractor and means for adding and removing solvent. The latter is a liquid extraction screen. It can take the form of a wiper or other screen, such as a steam jet. A cleaning device is provided to prevent blockage of the drain.

In one particular extractor configuration, shown in FIG. The cooking mixture containing 596 chips is passed through the extractor 100 into six reaction zones. They are exposed sequentially. For this particular extractor configuration, approximately 100 Further heating of the chip for about 2 to about 20 minutes at a constant temperature of 130 °C to 130 °C Alcohol impregnation occurs. In the separation area (a), the cooking temperature is lower than the level of the chips. A vapor headspace is maintained with a high level of solvent in the mixture. Somehow Excess solvent is removed through outlet 39 and recycled as described above. . The temperature of the cooking mixture chips is such that the cooking mixture passes into the preheating zone (b). and preheated from about 150° to 180° C. in about 50 minutes. Forecast Heating of the cooking mixture in the preheating zone (b) is carried out by means of a steam-heated heat exchanger (typically by circulating the cooking solvent countercurrently through a tube or shell type). achieved. The temperature of the heat exchanger is approximately 1 It is maintained at a level sufficient to cause heating from 50° to 180°C. This reserve The heated cooking mixture is heated from about 160° to 205°C in the second extraction zone (C). The mixture is further heated to a temperature of 50% and subjected to cooking and extraction for approximately 70 minutes. cooking mixture by cocurrently circulating the cooking solvent through a heat exchanger as described above. , - is heated in the extraction region (c). In region (c), hot ethano A coal/water extract, or "black liquor", is produced during the cooking and extraction process. Ligni hemicelluloses, other sugars and extracts (e.g. resins, organic acids, phenols, This hot black liquor containing (and tannins) is removed from the cooking mixture via line 40. to separate and then recover lignin and other pulping process by-products. It is processed.

The cooking mixture is brought to a temperature of approximately 150° to 180°C in the secondary extraction zone (d). The mixture is then further digested and extracted for about 60 minutes. This temperature is applied to the secondary extraction zone (d). cooling by recycling the cooking solvent in a heat exchanger as described above. It is what was done. The temperature of this heat exchanger is approximately 15 Sufficient to achieve cooling of the cooking mixture such that it maintains a temperature between 0° and 180°C maintained at a certain level. The cooking mixture is allowed to stand in the tertiary extraction zone (e) for approximately 45 minutes. The cooking mixture is then co-currently recirculated through a heat exchanger as described above. By ringing, the mixture is cooled to a temperature of about 130° to 160°C. child The cooking mixture is heated from about 70° to 100°C for about 22 minutes in the cooling zone (f). It is further cooled and defibrated into pulp by mixer 102. Cooling area (f) The cooling of the cooking mixture at the inlet 52 involves introducing this mixture countercurrently through the inlet 52. , by mixing with a solvent introduced cocurrently through inlet 53.

This solvent mixture consists of make-up alcohol, recycled alcohol from this alcohol, from the coal and recovered byproducts and the alcohol/water source liquid from the countercurrent washer 44. Become.

The pulp is separated from the cooking mixture and exits the extractor 100 via line 41. child The pulp of is recycled through line 7 in pressure diffuser 47. washed with alcohol and cooled to a temperature below 80°C, while at the same time Additional lignin is removed and recycled via line 36, resulting in a kappa number of Reduced to bleachable grade. When the pulp passes through the pressure reducing valve 42 As a result, further defibrillation occurs. The pressure reducing valve 42 is preferably made of blow pulp. Ru. The pulp is washed in a multi-stage counter-current washer by introducing water via line 43. It is further washed at 44 and cooled to a temperature of about 400 to 70°C. Countercurrent washing The purifier 44 replaces conventional steam recovery methods, which are less energy efficient. From about 50 to about 90% of the additional alcohol is removed from the pulp. After washing with water, The pulp is passed to tank 9 and fed through pulp screen 10. this place If the pulp is suitable for undergoing conventional pulp processing, bleaching, and papermaking processes. It has become.

In one bleaching technique, this condition, called brown stock, is The pulp is pretreated with a peroxy compound such as peracetic acid or hydrogen peroxide. In combination with oxygen treatment, delignification can be achieved by treatment with oxygen. can be done. The filtrate thus obtained under acidic conditions was It can be recycled as cleaning water for cleaning the tank. These filtrates are the inlet 43 and mixed with water to become part of the solvent in line 36 . Since the rate of delignification is directly proportional to the acidity of the solvent, these acidic filtrates is believed to accelerate the rate of delignification. In addition, lignin in the filtrate The presence of organic acids such as sodium ignate can cause delignification. It is thought to accelerate the speed. The result of such acid-catalyzed delignification , the operating temperature and pressure in the extractor 100 would be lower. Also, how many If treatment with such peroxy compounds is used continuously, the countercurrent filtrate should be resuscitated. It can be cycled. Alternatively, p)1 conditioning is followed by alkaline oxygen deligation. Filtrate from garlic can also be used.

For example, pulp delignification with oxygen initially reduces the solid pulp weight by about 9 to 15%. Mix consistency pulp slurry with sodium hydroxide solution (caustic) However, it can also be carried out by mixing with oxygen gas at higher shear. addition The amount of caustic produced is %wt/wt of oven-dried (o, d, ) pulp. On a basis, it may preferably be about 2 to 8%, more preferably about 3 to 6%.

The temperature of the reaction mixture is preferably between about 60°C and 110°C, more preferably is between about 70°C and 90°C. And the pressure of oxygen in the bleach container is Preferably about 40 to 110 psig (280 to 7 60 kPa), more preferably about 80 to 100 psig (55 0 to 690 kPa), and for delignification using oxidative extracts approximately 32 to 60 psig (220 to 410 kPa). Reaction time with oxygen is preferably about 6 to 60 minutes, more preferably about 40 to 50 minutes. . Further chemical additives that may be added to help retain strength properties include , 05% to 1% magnesium sulfate, 0.5% diethylenetriaminepenta Contains acetic acid (DTPA) and up to 3% sodium silicate. For example, pulp The peroxy treatment involves applying peracetic acid to the pulp at a pH of about 2 to about 10. Oven drying, (approximately 96 Q per weight of peracetic acid per weight of 5 to 4 parts by weight) This can be achieved by mixing. What is the consistency of the pulp? However, it is preferably between about 10 and 12% by weight of solid pulp. Delicious. The reaction time is preferably about 20 minutes at a temperature of about 40°C to 90°C. It takes about 3 hours from Or 1. The peroxy treatment of hydrogen peroxide at a pH of from about 0.05 to about 4%. ) can be achieved by mixing it into a lump. What is the consistency of the pulp? However, with a solid pulp weight of 96, between about 10 and 12 Preferably, the reaction temperature can be maintained at about 40° to 90°C. pa Magnesium sulfate is added at about 0.05% to 10.06% to protect the viscosity of the liquid. peroxides with metal ions such as manganese, copper, and iron In order to prevent catalytic decomposition of DTPA, the concentration of DTPA is about 0. 5% can be added can.

As shown in Figures 1.3 and 4, the black liquor is flushed into the flash tank 11. A portion of the ethanol is recovered.

The flash tank 11 can be at atmospheric pressure for simplicity of operation; Alternatively, vacuum may be applied to further cool the black liquor to increase alcohol recovery.

The reduced pressure in the flash tank 11 causes partial evaporation of the ethanol and Flush residual black liquor with a tanol content of 30 to 45%, preferably about 35 to 40%. Leave it in the tank. This residual black liquor is brought to a temperature below about 95°C during this step. , preferably from about 80° to 92°C, in the flash tank 11. In order to avoid premature precipitation of lignin in the water, temperatures are not allowed to drop below 70°C. black The liquid is steam-injected or indirectly heated before flushing in the flash tank 11. can be heated by, thereby evaporating more ethanol , the ethanol concentration in the black liquor was reduced from about 25 to 3496, and the ethanol concentration required for precipitation was reduced. Reduce the amount of dilution water used by about 20 to 70%. Steam injection or indirect heating also Can be used in the flash tank 11 or in series with the flash tank 11. It can be introduced directly into any flash tank that can be used. A that can be obtained The alcohol/water vapor is concentrated in the condenser 8 and the make-up ethanol, water and/or It is recycled along with the acid and used to process subsequent batches of wood chips. It will be done.

Alternatively, in a continuous process as shown in Figures 3 and 4, a flash tank 11 (or a flash tank directly connected to flash tank 11) The ethanol/water vapor can be recycled in the reboiler 24. , thereby providing energy for distillation in the solvent recovery column 14. solvent times The collection column 14 is connected to a further solvent recovery column and a rib arranged in series with the solvent recovery column 14. Solvent recovery can be further enhanced by interfacing with Wear.

According to the present invention, from the residual black liquor discharged from the flash tank 11, Gunin is separated. At this stage, when leaving the flash tank 11, water and diluting the residual black liquor with acetic acid and preferably cooling to form a diluted residual black liquor; Therefore, it is executed. In this case, a) alcohol content of less than 30% (by volume); Preferably about 10 to 25%, especially about 12 to 21%, with an alkali of about 896 The coal content is the minimum practical for economical recovery of alcohol at a later stage. and b) the temperature is below about 75°C, preferably below about 60°C, especially from about 35°C. 55°C, and c) the pH is less than about 3, preferably less than about 2.5, especially about 15 to 2. It is 5. At this stage, increasing the temperature in dilute residual black liquor generally The settling rate of lignin increases, producing darker lignin and decreasing yield. However, no particular temperature is critical. Approximately 75℃ is the temperature is the maximum temperature to avoid the formation of roll-like lignin precipitates, and is the maximum temperature at which ambient temperatures (e.g. (approximately 20°C) is the practical minimum.

However, if slower settling rates can be tolerated, lower temperatures (e.g. (up to 0°C) can also be used. Temperatures below about 65°C, especially below 60°C, are resulting in a brightly colored lignin precipitate.

or in large plant operations to avoid the formation of tarry lignin precipitates. For this purpose, approximately 30°C is the minimum temperature. Also, the specific p of diluted residual black liquor H is not critical at this stage, but the lower pH allows dilute residual black liquor to The use of diluted residual black liquor at higher temperatures increases the yield of lignin precipitation. make it possible. However, lowering the pH to less than about 1 results in little or no yield. Although it is possible to use a lower pH because there is no improvement at all, A pH of about 1 is a practical minimum. At a pH below about 3, lignin is precipitated as a fine solid from dilute residual black liquor in high yield and at high speed. Ru. These lignin solids are then stripped of any remaining residual dilution by conventional methods. It can be separated from the supernatant of black liquor. Preferably, the lignin solids are native as a paste of about 6 to 12% (by weight) in a clarifier or settling tank 12. This lignin solid paste is then concentrated in a conventional centrifuge. Shrink to form a wet cake of approximately 30 to 40% solids, and this wet cake It is separated by drying to form a fine, uniform, free-flowing powder.

Alternatively, in large-scale plant operations, the lignin solids are preferably Large filters (e.g. belt filters) that allow easy cleaning of the lignin cake separation by using a drum filter and a filter press, preferably a drum filter). be done.

The residual black liquor from flash tank 11 is diluted with water and acid to precipitate the lignin. in which the diluted residue has a pH of less than about 3.0, preferably less than about 2.50. Any conventional water-soluble acid that yields black liquor can be used. For example, strong Strong inorganic acids (e.g. hydrochloric, nitric, sulfuric, or phosphoric) or strong organic acids (e.g. sulfuric acid) Uric acid, preferably acetic acid, formic acid, or peroxyacid) can be used. Or The filtrate from the bleaching step can also be used, as shown in Figures 3 and 4. I can do it. These can be added to the water in line 43, alternatively , can also be added to the mixing tank 20. Furthermore, the oxygen delignification filtrate has a pH of After adjustment, about 3. At a pH above 0, preferably about 35 to about 40 In the meantime, the lignin can be precipitated.

Preferably, the water and acid are mixed together before being used to dilute the residual black liquor. this A particularly preferred mixture of acid and water is derived from a previous batch of wood chips. a) the residual black liquor supernatant from a previous batch of wood chips; from the lignin solids in the sedimentation tank 12 and the centrifugal separator 13 or b) Al in this supernatant is separated in a large-scale filter 63 as shown in After the coal content has been recovered in a conventional solvent condenser 15 as described below. , is recycled and used to dilute the residual black liquor from flash tank 11. This is what is being done. Recycled residual black liquor supernatant, i.e. effluent from the recovery tower is used to dilute residual black liquor from flash tank 11. Higher yields of lignin solids precipitated in the downfall tank 12 and centrifuge 13 yielding higher rates and faster settling.

In precipitating lignin from residual black liquor from flash tank 11, residual As long as the black liquor is rapidly and thoroughly mixed with the acid and water, the residual black liquor can be mixed with the water and the acid. The method of dilution is also not critical. For example, residual black liquor is indicated by a total of 20. Adding it to acid and water in a conventional fixed dispersion mixer or mixing tank and can be diluted appropriately. Residual black liquor is also shown schematically in Fig. 2, for example. A venturi-type device, shown generally at 20, is used to dissolve water and acids. dilution by adding in small streams into a stream of liquid can be done. The residual black liquor from the flash tank 11 in Figures 1.3 and 4 is In the venturi type device 20 shown in FIG. The acid and water solution can be fed through a small diameter nozzle 21 in a tube 22. and can flow to settling tank 12. The residual black liquor is passed through the nozzle 21 to the pipe 2. The residual black liquor is injected into the acid and water solution in tube 22. diluted and cooled quickly.

The lignin rapidly precipitates in tube 22 as fine solids from the resulting diluted residual black liquor. , this solid matter is easily collected and concentrated in the sedimentation tank 12 and centrifugal separator 13. Shrunk. Alternatively, as shown in Figure 4, the residual black liquor exits the mixing tank 20 and is Filter 63 (e.g. belt filter, filter press, preferably drum filter) into a liquid/solid separation system consisting of a filter) and a dryer 66. alcohol and hemi The filtrate with dissolved solids containing cellulose is extracted from the filter 63 and sent to the solvent recovery column. Distilled at 14. The precipitated rinsing cake is discharged from the filter 63. Then, it is dried in a dryer 66 into a powder form.

In precipitating lignin according to the present invention, the yield and sedimentation rate of lignin are In general, a) the type of wood, b) the process conditions used in the extractor 2, c) ( i) residual black liquor from flash tank 11 and (ii) used to dilute it; temperature, pH 1 and solids content of the acid and water present, and d) diluting the black liquor. is a function of the acid used and the ratio of black liquor to water. For example, spruce (spruce Lignin from coniferous trees such as P. ruce can be extracted with acids and a pH of about 1.5 to 2.5. The temperature after dilution with black liquor solution should be about 40° to 60°C, and the residual black liquor should be Preferably, the acid and water to solution ratios are from about 0.5 to about 1.

For hardwoods like aspen, which have a pH of about 12 to 2.2, using an acid and water solution with a temperature of less than about 50°C after dilution. is preferable. What is preferred in this regard is the residual black liquor for acid and water solutions. a) about 0.2 to 0°8 when the temperature after dilution is about 40°C, and b 06 to 1 if the temperature after dilution is less than about 40°C (e.g. up to ambient temperature). It is used as 0. sweetgum (sweetgum) % maple, and o For hardwoods such as oak, the temperature after dilution should be approximately 40° to 60°C, and acid and The pH of the acid and water solution is about 15 to 2.5, and the pH of the acid and water solution is about 15 to 2.5. Preferably, a black liquor ratio of about 0.35 to 0.7 is used.

The clarified residual black liquor filtrate from the lignin solids separation step is Lufural, wood sugars, acetic acid, and low molecular weights not captured during the precipitation process Contains lignin fragments. As shown in Figures 1°3 and 4, The tanol content is preferably recovered in the solvent recovery column 14 and the solvent condenser 15. It will be done. The ethanol content in the supernatant is determined by the amount of ethanol present in the solvent recovery column 14 at atmospheric pressure. can be removed (eg, up to about 200 ppm) in a conventional manner.

Preferably column 14 removes residual ethanol from the pulp in extractor 2. Using low-pressure steam used for It is heated by heating and recycling. Alternatively, the solvent recovery tower 14 If an additional recovery column is used in series, column 14 may be under vacuum or under pressure. can operate. The ethanol/water vapor from column 14 is also is condensed in a water-cooled condenser 15 (or by heat exchange with the removed feed), Then, the condensed ethanol/ Recycled with water mixture. According to the invention, the sedimentation tank 12 and the centrifuge from the separator 13 or alternatively from the large scale filter 63 as shown in FIG. The ethanol content in the supernatant is reduced by the lignin precipitated in the solvent recovery tower 14. even in a simple manner without forming tar-like or rubber-like deposits on the side surfaces. It can be appropriately recovered with high yield.

The clarified residual black liquor filtrate from the lignin solids separation step typically has a ．． 2 to 0.8% furfural, about 10 to 15% alcohol, about 0.5% Contains 10% dissolved solids and water. As shown in Figures 1.3 and 4. Then, the black liquor is fed to the solvent recovery column 14, and the side withdrawal of furfural is removed. It contains about 12 to 30% furfural. This furuf Ral side withdrawal is performed in line 700 on the upper plate of the supply plate. It is taken away. Furfural side withdrawal is indirect heat in heat exchanger 701 The exchange cools down to a temperature of less than about 50°, and in the decanter 71 it cools down to about 60°. The crude furfural layer containing 75% furfural from It separates into an alcohol-rich layer which is returned to the water. Crude furfural is liquid/liquid The quality can be improved from about 85% to 91% furfural using extraction, and It can be further purified to about 95 to 98% furfural using permeation. Ru. Other purification techniques include freeze concentration, dehydration, and the use of desiccant agents.

Typically about 60 to 7596 furfural, about 5 to 1596 ethanol , about 0.05 to 296 methanol, and about 7 to 15% water. The fural layer can be improved using liquid/liquid extraction. crossflow liquid extraction As shown in Figure 5, the crude furfural can be prepared using a mixer. It is mixed with a solvent, preferably water, at 71 using mechanical stirring. crude full When furfural and water are separated in the settler 72, the raffine of furfural is An alcohol-rich aqueous extract is obtained. from one arranged in series Several extraction stages (extraction stage = N in Figure 5) using multiple mixers and settlers can be used. However, the quality improvement of the crude layer is preferably carried out twice or twice. can be satisfactorily achieved by three sequential cross-flow extractions. water and crude oil Lefural has a volume ratio of about 1:1 to 32 and a temperature of about 00 to 50 degrees Celsius. Mix for approximately 30 minutes. As shown in Figure 5, approximately 0.5 to 6% Ethanol, about 0. 2 to 1% methanol and about 6 to 10% furfura The alcoholic extract containing alcohol is returned to the solvent recovery column 14. Furufura Raffinate contains about 89 to 91% furfural and about 0.9% furfural. 1 to 0.　 2% or as shown in Figure 6, crude furfural was extracted using countercurrent extraction. The quality can also be improved. The crude furfural is purified by a solvent, preferably water. , is extracted in a countercurrent extractor 73. Temperatures of about 00 to 50°C are used, and water The ratio of crude furfural to crude furfural is approximately 3:2. Furufura with improved quality Raffinate contains about 85 to 90% furfural and about 0.2 to 1% ether. Tanol and about 4 to 7% water. Typically around 1 to 1296 ethanol, about 0.4 to 1.5% methanol, and about 6% The alcoholic extract containing 10% furfural is returned to the solvent recovery column 14. be done.

The improved furfural raffinate is further purified to remove water (e.g. (e.g. by dehydration or pervaporation). Figures 5 and 6 show the refinement by pervaporation. This is an example of a manufactured product. The pervaporation system 80 is divided into two compartments 81 and 83 by a membrane 82. It consists of cells separated into Membrane 82 is preferably a hydrophilic membrane, such as polyvinyl vinyl. alcohol film. The quality-improved furfural is supplied to section 81. , the water contained in this quality-improved furfural is preferentially removed by the membrane 82. are attracted to. This water passes through membrane 82 and reaches compartment 83. Approximately 0. 8 to 8 psia (preferably about 1 to 2 psia) is maintained within tank 83. water is evaporated. Approximately 95 to 98% furfural, approximately 0.1 to 0.5 % ethanol, and the final furfural product containing approximately 0.1 to 2% water. is obtained and removed from compartment 81.

Alternatively, crude furfural can be improved using conventional distillation. be. An improved furfural distillate is obtained, which contains approximately 95 to 99% containing furfural, about 0.2 to 1% ethanol, and about 0.2 to 1% water. I'm reading. This yields a very pure furfural distillate, but the liquid/ The quality improvement and purification of furfural using liquid extraction and pervaporation is based on this single vaporization. This is a more preferable method than leaving. Because in that case, at least twice the energy This results in ghee savings and the resulting furfural product is ethanol-free. and the water content is smaller.

The Kankawa stream taken out from the solvent recovery tower 14 contains wood sugars, low molecular weight lignin, Contains acetic acid, ash, and a few other ingredients.

A portion of the Kan River stream may be concentrated in a conventional manner, for example in a multi-effect kettle 26. is preferred. At this stage, scaling and contamination of evaporation equipment are important issues. isn't it. This is because high molecular weight lignin is present in the can outflow from the solvent recovery column 14. This is because it is not actually included. The resulting syrup contains hemicellulose. Small amounts of other sugars, extracts, and very low molecular weight lignin (i.e. about 400 g contains submolecular weight of lignin) and loses its value as a fuel through combustion. It can be recovered and used as animal feed, or it can be used in other chemical It can be converted into a product. Alternatively, low molecular weight lignin can be recovered. can. These low molecular weight lignins can be used in the precipitation process due to their low molecular weight and water solubility. Corresponding to the lignin fragments that could not be captured in the Different fractions can be separated. Generally, low molecular weight lignin is low molecular weight fractions in the range below 24°C to 60°C; can be characterized by its transition temperature.

Another feature when pulping hardwoods is that low molecular weight lignin is primarily a syringyl core. It means that it is a model. This is because when oxidized with nitrobenzene, syrin This is because galaldehyde is produced in a molar ratio of approximately 5°31 to vanillin. be. This low molecular weight lignin is used as an extender in phenolic wood adhesives. It can be used as This also applies to applications where water solubility is required during the process. (e.g. glass fiber binders), and syringaldehyde and other chemicals It can also be used as an intermediate for the synthesis of substances.

Figure 7 illustrates the recovery of low molecular weight lignin. taken from the solvent recovery tower 14. A part of the extracted Kang River flow is concentrated in the multi-effect pot 600, and the amount of water is about 10 to 30. % solids content. Adding alkali before concentrating Kanchuanryu The pH of this syrup is optionally raised from about 20 to a pH of about 6.0 by be done.

The low molecular weight lignin fraction is separated as a tarry organic phase 90, which is present in the can effluent. About 30 to 70% of the low molecular weight lignin that was present in the Contains. This tar-like organic phase 90 consists of low molecular weight lignin of about 60 to 9096. 400 to 3000 at a temperature of about 60 to 95°C. It has a viscosity of cps. This organic phase is separated from the aqueous phase in a decanter 91. be separated.

This aqueous phase containing the remaining low molecular weight lignin is converted into solids in an evaporator 92. The organic Extracted with a solvent (preferably in a 1:1 volume ratio). diethyl ether, cyclohe Organic solvents such as xane, furan, and 3-hexanol can be used However, furfural is a particularly preferred solvent. Because furfural is in the aqueous phase More than 70% of the low molecular weight lignin present in the This is because the fibers obtained by quality improvement and purification as shown in Figures 5 and 6. Lufural can also be used to extract low molecular weight lignin as described above. I can do it. The raffinate from column 93 contains about 5 to 20% low molecular weight Nin, containing about 70 to 85% furfural and about 5 to 15% water. .

This raffinate is vacuum distilled in column 94. From column 94 The river contains low molecular weight lignin and essentially contains about 85 to 95% furfural and The condensate from condenser 940, containing approximately 5 to 15% water, is recycled to column 93. It is cycled. The extract from column 93 contains about 6 to 10% furfural, about It contains 4 to 5% sugars and about 50 to 80% water and is Removed from Leflard. The condensate from column 95 in condenser 950 is Decanted in decanter 96 and containing about 85 to 95% furfural and the heavy phase containing approximately 5 to 15% water is recycled to column 93. . The Kan River stream from column 95 contains sugars, mostly xylose, which is an acid It can further be used for the production of furfural by catalytic dehydration.

A separate second portion of the Kan River stream removed from column 14 is preferably an acid and water solution. It is used as a liquid to dilute the residual black liquor from the flash tank 11 to remove lignin. is used to precipitate from it. In this regard, the Kan River from Tower 14 This second portion of the stream is at a temperature of less than about 50°C, preferably about 25° to 40°C ( It is preferable to cool down to about 0°C (the minimum practical limit), and the pH should be adjusted if necessary. , adjusted from about 1.0 to 3.0 by adding a water-soluble strong acid.

This cooled and acidified second part of the Kan River stream (previously known as “recycler”) is then The residual black liquor supernatant) is carefully and quickly mixed with residual black liquor. The residual black liquor is mixed (e.g. in a Venturi-type device 20 of FIG. 2) to dilute and cool to precipitate the lignin.

In the settling tank 12, the diluted residual black liquor is precipitated as fine solids. This very pure lignin is then removed from the centrifuge 13 or alternatively It can be removed from a large-scale filter 63 as shown in FIG. dried (e.g. by spin flash drying) to a fine (e.g. -80 mesh), a homogeneous, free-flowing, water-soluble powder is formed. this rig Nins can be characterized as having the following properties.

About 800 to 1500 g mol, preferably about 900 to 1300 g mol. Relatively low number average molecular weight. Preferably about 100° to 170°C, especially about 130°C Glass transition temperature from ° to 150 °C. However, preferably about 80° to 170°C, especially A glass transition temperature of about 90° to 150° C. is also observed. Narrow molecular weight distribution , i.e. less than about 4, preferably no more than about 3, especially only about 1. From 5 Polydispersity of 2°7. Methoxyl content approximately equal to natural lignin (i.e. (approximately 20% for hardwoods and approximately 14% for conifers). This lignin is also a good preferably has a softening temperature of about 120° to 150°C, especially about 130° to 150°C. do. These properties indicate, inter alia, the purity of the lignin of the present invention and the chemical modification. This is a low degree of This lignin can also be used in e.g. particleboard and plywood. It can be used as an extender for phenol formaldehyde resin in the production of can. This lignin is also used in molding compounds, urethane and epoxy resins, and antioxidants. It can also be used in the manufacture of agents, release control agents, and flow control agents.

The present invention and many of its accompanying effects can be understood from the above description. without departing from the spirit and scope of the invention or sacrificing any of its essential advantages. Obviously, various modifications and changes may be made without modification. This is it The steps described above are merely preferred embodiments. for example , the process for precipitating the lignin of the present invention can alternatively be performed in a water-miscible organic solvent. Acid and water are added separately to a lignin solution dissolved in a pH of less than about 3, A dilute aqueous solution having an organic solvent content of less than about 30% and a temperature of less than about 75°C. and precipitating the lignin as a uniform fine solid from this dilute aqueous solution. It is possible to execute by In this regard, it is important to note that - next solvent The black liquor used in the extractor 2 for pulping (extracted from the black liquor in the flash tank 11) Before producing the residual black liquor after removing the tanol, the By adding acid to the primary solvent from meter 3, the acid is It can be added separately to the residual black liquor from the tank 11. In addition, the main The process described above uses water-miscible alcohols other than lower aliphatic alcohols (preferably ethanol). organic solvents, such as acetone, glycol or glycerol, or mixtures of such solvents. It can also be carried out for compounds. In addition, these processes are not limited to wood. It can be carried out using any fibrous plant material such as bamboo, bagasse, kenaf, straw etc. It is possible.

Engraving (no changes to the content) -Us・2 2C・5 J, 6 -Ls, 8 Procedural amendment form) 1. Display of incidents Patent application No. 4-509563 PCT/US92100720 2. Name of the invention Person who performs valving of lignocellulose raw materials and recovery of generated by-products 3. Relationship to the incident: Patent applicant Name: Arcel Chicnolosis Incorporated 4, Agent Address: 1-8-11-5, Nihonbashihoridomecho, Chuo-ku, Tokyo, Date of amendment order May 24, 1994 (shipment date) 6. Subject of correction international search report Continuation of front page (72) Inventor Croneland, Malcolm, Pennsylvania, United States 434 Saddlepluck Circle, Chester Springs 19425 (72) Inventors Wu, Qi, Fae Bow, West Chester, Pennsylvania 19380, United States Urie Drive 1607 (72) Inventor: Gopal, Goyal, Sy., Pennsylvania, United States of America 19453 Mont Claret, Meadowview Rain (72) Inventor Winner , Stephen, Earl Boothwy, Pennsylvania 19061 United States N, Matran Road 180 (72) Inventor Leblanc, Ron Alberta, Canada T2P 3. Calgary, 840-7th Ave. New Southwest, 1720

Claims (67)

[Claims] 1. The fibrous plant material is pulped in a water-miscible organic solvent, and the water-miscible organic solvent is , lignin, and other by-products resulting from the pulping of the fibrous plant material. a step of wetting the fibrous plant material; heating the fibrous plant material; and converting the heated fibrous plant material into a water-miscible material. impregnating with an organic solvent to form an impregnated fibrous plant material mixture; The soaked fibrous plant material mixture is extracted with the water-miscible organic solvent to obtain a cooking mixture. producing the cooking mixture consisting of cellulose pulp and black liquor; black liquor consists of said lignin and said by-product, and recovering the lignin from the black liquor. 2. further comprising recovering the water-miscible organic solvent and the by-product from the black liquor. 2. The process of claim 1, comprising: 3. The extraction step impregnating the cooking mixture with the water-miscible organic solvent in a separation zone; The cooking mixture produced in the separation zone is heated in a preheating zone. and the step of The cooking mixture produced in the preheating zone is heated in the primary extraction zone. a step of heating; During the heating in the primary extraction zone, the cooking mixture is cooked to produce the black liquor. from the cooking mixture; and during the cooking step, the primary extraction simultaneously extracting the cooking mixture in the region; The cooking mixture produced in the primary extraction zone is transferred to a secondary extraction zone. a step of cooking; cooking the cooking mixture from the secondary extraction zone in a tertiary extraction zone; and, cooling the cooking mixture in the tertiary extraction zone; and cooling the cooking mixture from the tertiary extraction zone in a cooling zone; 3. The process of claim 2, comprising: 4. 4. The process of claim 3 including the step of separating said black liquor from said cooking mixture. 5. The water-miscible organic solvent may be makeup alcohol, recovery alcohol, alcohol/ 5. The process of claim 4, comprising a water filtrate and a bleach filtrate. 6. The claim further comprises separating the cellulose pulp from the cooking mixture. Process of request 5. 7. Reduce the kappa number of the cellulose pulp to form brown stock pulp and the step of The brown stock pulp is washed with a washing medium to produce an alcohol/water filtrate. the stage of achieving bleaching the brown stock pulp to produce a bleach filtrate; combining the alcohol/water filtrate and the bleach filtrate; and recycling the combined alcohol/water filtrate and bleach filtrate; 7. The process of claim 6, further comprising: 8. The cleaning medium is from the recycled alcohol/water filtrate and bleach filtrate. 8. The process of claim 7. 9. removing residues of the water-miscible organic solvent during the washing step; a water-miscible organic solvent comprising residues of said lignin, and For use in the impregnation and extraction steps of claim 1, the water-miscible organic 9. The process of claim 8, including the step of recycling the solvent. 10. The water-miscible organic solvent is circulated countercurrently in the preheating zone. heating the cooking mixture and cocurrently circulating the water-miscible organic solvent. heating the cooking mixture in the primary extraction zone; cooling the cooking mixture in the secondary extraction zone by cocurrently circulating a machine solvent; and circulating the water-miscible organic solvent co-currently in the tertiary extraction zone. cooling the cooking mixture through a first inlet; and directing the cooking mixture from a first inlet. The water-miscible organic solvent introduced flow-wise and the water-miscible organic solvent introduced counter-currently from a second inlet. The water-miscible organic solvent is mixed simultaneously and the cooking mixture is placed in the cooling zone. 4. The process of claim 3, including the step of cooling. 11. flushing the black liquor to form residual black liquor; recovering alcohol from the drinking stage and recycling the recovered alcohol; and combining said recycled recovered alcohol with said water-miscible organic solvent. 11. The process of claim 10, further comprising the step of combining. 12. separating the lignin from the residual black liquor; and from the separating step. producing a residual black liquor filtrate, the residual black liquor filtrate containing furfural. 12. The process of claim 11, comprising: a low molecular weight lignin; and the by-product. 13. The furfural in the black liquor filtrate is converted into furfural from the residual black liquor filtrate. producing a side pull of the lever; Cool the furfural side draw and extract the crude furfural layer and alcohol rich and converting the crude furfural layer into the alcohol-rich layer. a step of separating from the The crude furfural layer was subjected to solvent extraction to obtain furfural raffinate and alcohol. producing a furfural extract; and purifying the furfural raffinate; and producing a fural product. 14. recovering the alcohol from the alcohol-rich layer; recycling the recovered alcohol; and recovering the recycled alcohol. combining an alcohol with the water-miscible organic solvent. Process. 15. 15. The furfural raw material of claim 14, comprising about 95 to 99% furfural. A product. 16. producing a residual black liquor can effluent from the residual black liquor filtrate; the black liquor can effluent comprising the low molecular weight lignin and the by-product; separating a first portion of the can effluent consisting of the low molecular weight lignin; Beauty separating a second portion of the can effluent consisting of the by-product; The process of claim 15. 17. The low molecular weight lignin is The first portion of the residual black liquor can effluent is concentrated, and the residual black liquor can effluent is It contains low molecular weight lignin and forms a tarry organic phase and an aqueous phase from the concentration step. separating the tarry organic phase from the aqueous phase; and separating the aqueous phase from the aqueous phase. a step of concentrating; extracting the concentrated aqueous phase with an organic solvent, the organic solvent being diethyl ether, cyclohexane, furan, 3-hexanol, and furfural. a stage consisting of elements of the group consisting of; producing an aqueous extract and a raffinate; and distilling said raffinate to produce a carbonate. producing a can effluent, the can effluent containing the low molecular weight lignin and the organic lignin; a stage consisting of a condensate consisting of an organic solvent; collecting the can effluent and mixing it with the tarry organic phase; and Separating the low molecular weight lignin contained in the tarry organic phase and the can outflow. 17. The process of claim 16, wherein the process is recovered by the step of: 18. separating the aqueous extract from the organic solvent; recovering the organic solvent from the separation step; and collecting the organic solvent from the recovery step in the evaporator. 18. The process of claim 17, further comprising the step of combining with the organic solvent from the distillation step. Moderate. 19. In the extraction step of claim 16, the recovered organic solvent is recycled. 20. The process of claim 18, comprising the step of using. 20. The organic solvent comprises furfural recovered from the residual black liquor filtrate. The process of claim 19. 21. The low molecular weight of claim 20 having a number average molecular weight of less than 21.500 grams/mol. Lignin. 22. 22. The low molecular weight lignin of claim 21, having a glass transition temperature. 23. 23. The low temperature glass of claim 22, wherein the glass transition temperature is in the range of about 24° to 60°C. Molecular weight lignin. 24. 10. The method of claim 1, further comprising the step of recovering said by-product from a second portion of said can effluent. 15 steps. 25. Black produced in the pulping of fibrous plant materials with water-miscible organic solvents A process for recovering furfural from a liquid, diluting the black liquor to form a residual black liquor; and producing a residual black liquor filtrate from the residual black liquor. the residual black liquor filtrate containing furfural; removing furfural lateral withdrawal from the residual black liquor filtrate; Cool the furfural side draw to form a crude furfural layer and alcohol. forming an alcohol-enriched layer and decanting said alcohol-enriched layer. , separating the crude furfural layer from the alcohol-rich layer; The crude furfural layer was extracted with a solvent, and furfural raffinate and alcohol were extracted. producing a furfural extract; and purifying the furfural raffinate. and producing a lefural product. 26. recovering the alcohol from the alcohol-rich layer; recycling the recovered alcohol; and recovering the recycled alcohol. combining an alcohol with the water-miscible organic solvent. Process. 27. 27. The process of claim 26, wherein the extraction step is a cross-flow solvent extraction. 28. The crude furfural layer and the solvent have a volume ratio of about 1:1 to 3:2. 28. The process of claim 27. 29. 27. The process of claim 26, wherein the extraction step is a countercurrent solvent extraction. 30. The crude furfural layer and the solvent are mixed at a flow rate ratio of about 3:2. , the process of claim 29. 31. 26. The furfural raffinate is purified by pervaporation. process. 32. introducing the furfural raffinate into a first compartment; is separated from the second compartment by a membrane; a stage for separating water contained in the furfural raffinate into the second compartment; floor and evaporating the water in the furfural raffinate; and producing the furfural product from the compartment. Moderate. 33. 33. The furfural production of claim 32, comprising about 95 to 98% furfural. thing. 34. 27. The furfural raffinate of claim 26, wherein the furfural raffinate is purified by distillation. Process. 35. 35. The furfural production of claim 34, comprising about 95 to 99% furfural. thing. 36. Black produced in the pulping of fibrous plant materials with water-miscible organic solvents A process for recovering low molecular weight lignin from a liquid, the process comprising: producing a residual black liquor filtrate from the residual black liquor; and producing a residual black liquor from the residual black liquor filtrate. producing a liquor can effluent, said residual black liquor can effluent comprising said low molecular weight lignin; and a portion of the residual black liquor can effluent containing the low molecular weight lignin is concentrated and tarred. producing a tar-like organic phase and an aqueous phase; and extracting the tar-like organic phase from the aqueous phase; separating the tarry organic phase by decantation; and separating the aqueous phase by decantation. a step of concentrating; The concentrated aqueous phase was dissolved in diethyl ether, cyclohexane, furan, 3-hexane, An organic solvent consisting of an element selected from the group consisting of xanol and furfural a step of producing an aqueous extract and a raffinate; The nate is distilled to contain a concentrate containing the low molecular weight lignin and the organic solvent. generating a can effluent; collecting the can effluent; mixing the can effluent with the tarry organic phase; and and separating the low molecular weight lignin contained in the can effluent. Moderate. 37. separating the aqueous extract from the organic solvent; recovering from the separation stage, and recovering the organic solvent from the separation stage and the distillation. 37. The process of claim 36, further comprising the step of combining said organic solvent from step Moderate. 38. recycling the recovered organic solvent for use in the extraction step; 38. The process of claim 37, comprising the step. 39. The low molecular weight of claim 38 having a number average molecular weight of less than 39.500 grams/mole. Lignin. 40. 40. The low molecular weight lignin of claim 39 having a glass transition temperature. 41. 41. The glass transition temperature of claim 40, wherein the glass transition temperature is within the range of about 24° to 60°C. Low molecular weight lignin. 42. A low molecular weight lignin having a number average molecular weight of less than 500 grams/mol. 43. 43. The low molecular weight lignin of claim 42 having a glass transition temperature. 44. 44. The glass transition temperature of claim 43, wherein the glass transition temperature is within the range of about 24° to 60°C. Low molecular weight lignin. 45. A furfural product consisting of about 95 to 99% furfural. 46. Pulp wood and other fibrous plant materials with water-miscible organic solvents to produce by-products. in an apparatus for producing a black liquor and then recovering a solvent from the black liquor. The lignin is precipitated from the diluted black liquor obtained by diluting it with an acid aqueous solution, and the lignin deficiency is means (a) for leaving a supernatant, and then lignin-depleted supernatant precipitated from the lignin-depleted supernatant; and (b) means for separating the lignin. type device. 47. Pulp fibrous plant materials and recover the pulp and by-products of the pulping process. A device that A method for pulping fibrous plant materials with water-miscible organic solvents to produce pulp and black liquor. Step (a) and then means (b) for separating the pulp from the black liquor and subsequently removing the pulp from the black liquor; (c), and then diluting the black liquor with an acid aqueous solution to obtain a rig from the diluted black liquor obtained. (d) means for precipitating the lignin and leaving a lignin-deficient supernatant; and (e) means for subsequently separating the black liquor from the lignin-depleted supernatant. 48. Pulp fibrous plant materials and recover the pulp and by-products of the pulping process. A device that Fibrous plant materials are pulped with water-miscible organic solvents to produce pulp and black liquor; An extractor that separates and removes the solvent from the black liquor and a residual black liquor that separates and removes the solvent from the black liquor. Leave a flush tank and, Condenser to concentrate and recycle flushed solvent and residual black liquor, water, and acid to precipitate the lignin from the residual black liquor by rapidly and carefully mixing the mixture consisting of A mixer is used to separate the lignin from the mixture of residual black liquor, water, and acid. , water, and lignin with acid and a settling tank to form a clarified residual black liquor supernatant and, The lignin is further separated from residual black liquor, water, and acid to produce powdered lignin and a centrifuge for forming a clarified residual black liquor supernatant; The solvent content in the supernatant introduced into the column from the settling tank and centrifuge is It is collected and recycled for further pulping of fibrous plant materials. a solvent recovery column forming an effluent; Concentrate the can effluent to recover hemicellulose, sugars, extracts, and low molecular weight lignin. A device consisting of an evaporator that collects water or burns it as fuel. 49. The fibrous plant material is pulped in a water-miscible organic solvent, and the water-miscible Equipment for recovering organic solvents, lignin, and other by-products from the pulping process. hand, pulping the fibrous plant material in the water-miscible organic solvent to produce a cooking mixture; means (a), wherein the cooking mixture comprises cellulose pulp and black liquor; black liquor includes the lignin and the byproduct; The cellulose pulp and the black liquor produced by the pulping means (a) are Separating means (b) and the cellulose pulp separated by the means (b) means (c) for separating brown stock pulp from said means (c); (d) means for recovering the separated brown stock pulp; means (e) for separating the lignin from the black liquor separated by the means (b); )and, means (f) for recovering the lignin from the black liquor separated by the means (b); )and, the water-miscible organic solvent and the black liquor separated by the means (b); means (g) for separating by-products; and said water-miscible organic solvent, and said means (g). ) a means (h) for recovering the by-product separated by the method. 50. The water-miscible organic solvent recovered by the means (h) is placed in the apparatus. 50. The apparatus of claim 49, further comprising means (i) for recycling for further use. . 51. Separating crude furfural from the black liquor separated by the means (b) 51. The apparatus of claim 50, further comprising means (j) for: 52. Furfural production from crude furfural separated by the above means (j) 52. The apparatus of claim 51, further comprising means (k) for separating objects. 53. means for recovering said furfural product separated by said means (k); 53. The apparatus of claim 52, further comprising (l). 54. separating a tarry organic phase from the black liquor separated by the means (b); 54. The apparatus of claim 53, further comprising means (m). 55. Low molecular weight lignin is extracted from the tarry organic phase separated by the means (m). 55. The apparatus of claim 54, further comprising means (n) for separating the particles. 56. means (o) for recovering the low molecular weight lignin separated by the means (n); 56. The apparatus of claim 55, further comprising: 57. The furfural product recovered by the means (l) is placed in the device. 57. The apparatus of claim 56, further comprising means (p) for recycling for further use. . 58. Said means (d) for collecting said brown stock comprises collecting said brown stock. 58. The apparatus of claim 57, further comprising means (q) for bleaching the liquid. 59. The means (q) for bleaching the brown stock comprises bleaching the brown stock. 59. The apparatus of claim 58, further comprising means (r) for separating the bleach filtrate from the stock. 60. The means (s) for recovering the bleach filtrate separated by the means (r) 60. The apparatus of claim 59, comprising: 61. The bleach filtrate recovered by the means (s) is further processed in the apparatus. 61. The apparatus of claim 60, further comprising means (t) for recycling for use in. 62. The fibrous plant material is pulped in a water-miscible organic solvent, and the water-miscible Organic solvents, lignin, and other by-products obtained from the pulping of the fibrous plant material. An apparatus for recovering a material, the apparatus comprising: pulping the fibrous plant material with the water-miscible organic solvent; an extractor for producing a cooking mixture, the cooking mixture comprising a cellulose pulp; a pulp and a black liquor, the black liquor and the cellulose pulp being separated from the cooking mixture; an extractor for separating alcohol from said black liquor and a separator for separating alcohol from said black liquor to form a residual black liquor; and, a condenser for recovering the water-miscible organic solvent and mixing the residual black liquor with water and an acid; a mixer for separating lignin from the residual black liquor; and a separator that separates the lignin from the residual black liquor to produce a residual black liquor filtrate; The residual black liquor filtrate contains furfural, low molecular weight lignin, and the by-products. A device consisting of 63. Alcohol is recovered from the residual black liquor filtrate, and the recovered alcohol is Recycle the residual black liquor along with water-miscible organic solvents to prevent residual black liquor a solvent recovery column forming a side draw containing lufural; The residual black liquor can effluent is concentrated to remove low molecular weight lignin and the by-products from the black liquor can. 63. The apparatus of claim 62, further comprising an evaporator for recovering liquid can effluent. 64. The cellulose pulp is washed with the recovered alcohol to remove the cellulose pulp. The alcohol/water a washer for recovering filtrate from said washing; a washer for washing the brown stock pulp with water; and a washer for washing the brown stock pulp with water; The pulp is bleached, a bleach filtrate is produced, recycled, and the alcohol/water 64. The apparatus of claim 63, further comprising a bleach system in combination with the filtrate. 65. The furfural side draw is cooled and the crude furfural layer and alco a heat exchanger that generates a layer rich in alcohol; and a heat exchanger that generates a layer rich in alcohol; a decanter that separates the oil-rich layer; The crude furfural layer was extracted into furfural raffinate and alcohol extraction. an extractor for producing the furfural raffinate and purifying the furfural raffinate to produce the furfural raffinate; 65. The apparatus of claim 64, further comprising a purification system that produces a Ral product. 66. further comprising a condenser for condensing the alcohol from the alcohol-rich layer. 66. The apparatus of claim 65, comprising: 67. concentrating a first portion of the residual black liquor can effluent containing the low molecular weight lignin; an evaporator for forming a tarry organic phase and an aqueous phase; a decanter for separating the low molecular weight lignin in the aqueous phase from the aqueous phase; an extraction column that produces an aqueous extract and a raffinate; and an extraction column that produces an aqueous extract and a raffinate; a solvent recovery device for separating the organic solvent and recovering the organic solvent; distilling the raffinate to produce a can effluent containing the low molecular weight lignin; 67. The apparatus of claim 66, further comprising a distillation column.