CN105113307A - Pulping method via pre-extraction of bagasse easily soluble hemicelluloses, and product obtained via pulping method - Google Patents
Pulping method via pre-extraction of bagasse easily soluble hemicelluloses, and product obtained via pulping method Download PDFInfo
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Abstract
The invention discloses a pulping method via pre-extraction of bagasse easily soluble hemicelluloses, and a product obtained via the pulping method. The pulping method comprises following steps: bagasse raw material is subjected to alkaline extraction at normal temperature so as to obtain a coarse extraction liquid containing bagasse; the coarse extraction liquid is filtered so as to obtain extracted bagasse and a filtrate; the extracted bagasse is squeezed until dryness degree is 30% or higher so as to obtain extracted bagasse and a squeezed fluid; the squeezed fluid is mixed with the filtrate so as to obtain an extraction liquid; the extracted bagasse is delivered into a boiling vessel for alkaline cooking so as to obtain paper pulp; and the extraction liquid is separated so as to obtain finished product hemicelluloses. According to the pulping method, conventional paper pulp is produced, and bagasse hemicelluloses is produced simultaneously, a novel industrial chain is increased, and economic benefits are increased; the pulping method is capable of reducing alkali amount in subsequent bagasse cooking, reducing cooking holding temperature and temperature holding time, increasing cooking delignification efficiency, reducing subsequent consumption of bleaching chemicals, and saving energy and reducing consumption.
Description
Technical field
The invention belongs to biorefinery and pulping and paper-making scientific domain, be specifically related to pulping process of the easy molten hemicellulose of a kind of pre-extracting bagasse and products thereof.
Background technology
Bagasse is the byproduct in sugar refinery, and bagasse is all directly burnt as fuel by former most of sugar refinery, it is found that bagasse contains abundant fiber afterwards, is the paper making raw material of high-quality, so people utilize Bagassepulping papermaking one after another.According to statistics, 1 ton of sucrose is often produced by generation 0.6 ton of over dry except marrow bagasse.Within 2011/2012 year, squeeze season, the output of China's sucrose is 1,050 ten thousand tons, and 6,300,000 tons of over dry can be provided except marrow bagasse, but only have the bagasse of 50% for papermaking, other most of bagasse is still burnt by as fuel.
Mainly utilize pulping wood papermaking abroad; China is the country that a forest lacks; paper industry is every year from a large amount of wood chip of external import and wood pulp; more and more serious along with global greenhouse effect; global natural calamity also gets more and more; therefore the cry conserved forests in world wide is also more and more higher, utilizes non-wood material pulping and paper-making for preserving our planet, and reduces greenhouse effects and has very positive meaning.
The primary chemical composition of bagasse is cellulose, hemicellulose and lignin, also containing a small amount of organic extract and inorganic matter.Cellulose is the linear polymer connected by 1-4 β glycosidic bond by glucose unit, sugarcane fiber cellulose content is about 45%, its degree of polymerization is different because of outer hide fiber and internal fiber, and crust fibrous polymer degree exceedes general leaf wood (as Eucalyptus), but lower than needlebush; The bast fibres degree of polymerization is close with wheat straw.Hemicellulose is the heterogeneity glycan with side chain; bagasse hemicellulose main chain mainly xylose units is connected by 1-4 β glycosidic bond; side chain contains acetyl group, 4-O-methyl glucose uronic acid base and aralino; hemicellulose is not containing crystal region; its degree of polymerization is between 50 ~ 300; the hemicellulose that the degree of polymerization is lower can be dissolved in the high aqueous slkali of concentration, and side chain is easy to rupture and consumes boiling alkali.Hemicellulose is mainly distributed on fiber finer cell wall, is generally connected by chemical bond with lignin.The hemicellulose level of bagasse is 25 ~ 30%.Lignin is a kind of material of tridimensional network, its main component units is phenylpropyl alcohol alkyl structure unit, and lignin is mainly distributed between fibrocyte, is sticked together tightly by fiber, particularly primary wall is also containing lignin for fiber finer cell wall, and bagasse content of lignin is about 20%.
The traditional soda pulping process of bagasse adopts NaOH or NaOH and vulcanized sodium to react at high temperature under high pressure with bagasse under the condition of adding or do not add anthraquinone, lignin in bagasse in the basic conditions, the Small molecular lignin that size degradation becomes can be dissolved in aqueous slkali, destroy fibrocellular intercellular layer, thus making the fiber separation be closely connected become single fiber to become paper pulp, lignin is then dissolved in black digestion liquid.Bagasse after boiling obtains paper pulp by being separated black liquor, and black liquor send alkali recovery furnace to burn through evaporation and concentration again, and organic matter changes into heat energy power-generating, and inorganic matter generates sodium carbonate, and sodium carbonate generates NaOH through causticization again, comes back to the boiling stage.
At early stage of cooking, the hemicellulose of a great deal of can be dissolved in alkaline cooking liquor, and before reaching maximum temperature of cooking, in black liquor, the concentration of hemicellulose reaches maximum, and subsequently, hemicellulose is at high temperature degraded, and generates mutation saccharic acid, consumes boiling alkali.Under high-temperature alkaline condition, peeling reaction can be there is, stripped down one by one by cellulose terminal aldehyde groups in a small amount of cellulose, cause cellulosic degraded, simultaneously under high-temperature alkaline condition, also can there is basic hydrolysis in cellulose, the cellulosic degree of polymerization also can be caused to reduce, when cellulosic degree of polymerization is very low, cellulose also can be dissolved in black liquor, and the same with the hemicellulose dissolved, the cellulose of dissolving at high temperature, mutation saccharic acid can be degraded into further, consume boiling alkali.
As mentioned above, hemicellulose is dissolved in the consumption that can increase alkali in black liquor, and the hemicellulose in addition in black liquor can increase the viscosity of black liquor, increase load and the water consumption of pulp washing, black liquor viscosity increase is unfavorable for the evaporation of black liquor, easily causes fouling of evaporator, affects evaporation efficiency.Because hemicellulose belongs to carbohydrate, its combustion heat value only has the half of lignin, and in black liquor, hemicellulose level is high, can reduce the thermal efficiency and the production capacity of alkali recovery furnace.Bagasse contains abundant hemicellulose, and its hemicellulose forms mainly xylan.Xylan can be hydrolyzed into wood sugar, wood sugar by fermentation or other chemical treatment can prepare ethanol, butanols, 1,2, bio-fuel and the chemicals such as 4-butantriol, lactic acid, furfural, xylitol, wherein ethanol, butanols can Substitute For Partial vehicle fuel, 1,2,4-butantriol can be used as the solid propellant of rocket, lactic acid and furfural are important basic chemical industry raw materials, PLA (PLA) after lactic acid polymerizes can replace plastics, has wide practical use, and xylitol can as the alternative sugar of diabetes patient.Hemicellulose can also directly be used as pulp additive with polymer morphology, prepare the purposes such as aquogel or thermoplastic xylan derivative.Based on above reason, lot of domestic and international researcher just proposes the idea of pre-extracting hemicelluloses before slurrying.
U.S. Patent application US20110214826A1 proposes the method for pre-extracting hemicelluloses and then slurrying from lignocellulose raw material, the method divides 3 steps, first be the hemicellulose in pre-extracting lignocellulose raw material, require that the aqueous solution of pre-extracting must containing can partly neutralize the acidic materials discharged from lignocellulose raw material, so as at the end of pre-extracting extract pH 4.5 ~ 11 scope; Second step be raw material after extracting again through slurrying, make lignocellulose raw material be separated into paper pulp; Final step is again adsorbed onto in the paper pulp of second step by the hemicellulose of extracting.Because the method adopts wood chip to be raw material, need higher temperature, hemicellulose is while extracting, also along with the stripping of a large amount of lignin, half-and-half cellulosic separation and application all produce harmful effect, hemicellulose adsorption process efficiency last is in addition lower, and a large amount of hemicellulose still enters into black liquor system, does not obtain higher value application.
Chinese patent CN102617284B describes a kind of method that Eucalyptus sheet hydrolyzate produces xylitol, its cardinal principle is that when utilizing Eucalyptus prehydrolysis, xylan is degraded into compound sugar and is dissolved in hot water hydrolyzate, again acid hydrolysis is carried out to hydrolyzate, compound sugar is made to be hydrolyzed into monose further, then wood sugar is obtained to hydrolyzate decolorizing, ion-exchange purification, concentrated, crystallization treatment, wood sugar obtains xylitol through hydrotreatment again, and the Eucalyptus sheet after hydrolysis obtains dissolving pulp through boiling, bleaching.The method is only suitable for dissolving pulp and produces, and due to temperature during prehydrolysis higher (more than 120 ~ 180 DEG C), in hydrolyzate, the concentration of wood sugar is low, and accessory substance (lignin, furfural, acetic acid) is many, causes the production cost of wood sugar high.
Chinese patent CN101565907A describes one " bagasse alkaline pulping method of preextraction hemicellulose and products thereof ", this patent is also before slurrying, extract bagasse hemicellulose then slurrying, but the method extracts hemicellulose when heating with NaOH, the same with U.S. Patent application US20110214826A1 presented hereinbefore, intensification can cause a large amount of stripping of lignin in Bagasse Material, intensification also can be led lysogenic hemicellulose and degrade, be unfavorable for the separation of bagasse hemicellulose, also can affect the hemicellulose quality of extraction, the consumption of the process energy can be increased simultaneously, the operation of process is also more difficult.This patent adopts known and disclosed technology to prepare the products such as wood sugar, xylo-oligosaccharide, xylitol to the extract containing hemicellulose in addition, this process is the difficult point of this invention, in fact at present still there is no good method to be separated, this process of this patent.
In sum, south China has abundant Bagasse Material, and bagasse contains higher hemicellulose, and add that Bagasse Material institutional framework is loosened, in digestion process, hemicellulose is very easily dissolved in cooking liquor, causes the reduction of black liquor viscosity increase and alkali recovery efficiency.Current bagasse digesting technoloy and equipment always relatively backward, product is single, and production efficiency is low, seriously polluted.Pre-extracting bagasse hemicellulose can improve existing bagasse digesting technoloy, and increases new industrial chain, improves the economic benefit of enterprise.
Summary of the invention
For solving the shortcoming and defect part of prior art, primary and foremost purpose of the present invention is the pulping process providing the easy molten hemicellulose of a kind of pre-extracting bagasse.The method is before bagasse boiling, and first Extraction parts hemicellulose, then prepares paper grade pulp with alkaline cooking, and this extracting method is little on the impact of follow-up Bagassepulping, also can improve output and the efficiency of slurrying.
Another object of the present invention is to provide the product that the pulping process of the easy molten hemicellulose of above-mentioned pre-extracting bagasse obtains.Hemicellulose diffluent in bagasse can extract by the inventive method effectively, and carries out being separated and obtain a kind of new industrial products---hemicellulose.
For achieving the above object, the present invention adopts following technical scheme:
A pulping process for the easy molten hemicellulose of pre-extracting bagasse, comprises the following steps:
(1) alkali density of bagasse: Bagasse Material is used alkali density under the condition of normal temperature, obtains the crude extract containing bagasse;
(2) extraction of extract: the crude extract that step (1) obtains first is filtered, obtains the bagasse after extracting and filtrate; Then the bagasse after extracting is expressed to the mass dryness fraction of more than 30%, obtains extracting bagasse and squeezed fluid; Squeezed fluid is extract with filtrate mixing;
(3) alkaline cooking of extracting bagasse: the extracting bagasse that step (2) obtains is delivered to boiling vessel and carry out alkaline cooking and obtain paper pulp.
In above-mentioned steps (1); acetyl group on bagasse hemicellulose molecule and alditol acidic group can be neutralized by alkali and remove; the hemicellulose that relative molecular mass is less is then dissolved in aqueous slkali; micromolecular phenolic lignin also can be dissolved in alkali lye, and a small amount of silica in Bagasse Material is also dissolved in alkali lye.
Normal temperature described in step (1) is 20 ~ 40 DEG C, and the process conditions of described alkali density are: extraction times 30 ~ 60 minutes, alkali concn 30 ~ 180g/L, liquid-solid ratio 5:1 ~ 8:1 (L/kg).
In the inventive method, extraction temperature is normal temperature 20 ~ 40 DEG C, and without the need to increasing new heat energy, extract is easily molten hemicellulose and a small amount of lignin, and extractive process has no adverse effects to follow-up boiling.
Alkali in alkali density described in step (1) is NaOH.
Step (2) also comprises the bagasse after to extruding and washs, and to reduce the concentration of NaOH in bagasse, and help the hemicellulose washing out dissolving, cleaning solution mixes with squeezed fluid and filtrate.
Can extrude with two roll press or screw extruder in step (2).
The process conditions of the alkaline cooking described in step (3) are: cooking and heat-preservation temperature 140 ~ 160 DEG C, boiling alkali charge is 14 ~ 16% of Bagasse Material quality, 30 ~ 60 minutes cooking and heat-preservation time, boiling liquid-solid ratio 3.0 ~ 5.5:1.0, anthraquinone consumption is 0.1% of Bagasse Material quality.
Alkali described in step (3) is NaOH.
The product of the pulping process acquisition of the easy molten hemicellulose of above-mentioned pre-extracting bagasse, the extract obtained for step (2) is separating obtained, and concrete steps are:
The ultrafiltration of (a) extract: extract step (2) obtained first filters with 200 eye mesh screens, is separated tiny bagasse, then filters extract with milipore filter;
The alcohol settling of (b) trapped fluid and separation: when in the trapped fluid that step (a) obtains, organic concentration reaches more than 40g/L, precipitate trapped fluid with the absolute ethyl alcohol of 1 ~ 5 times of trapped fluid volume, the centrifugation of precipitation mixed liquor is precipitated thing hemicellulose product and supernatant.
In the ultra-filtration process of above-mentioned steps (a), alkali and the lower xylan of relative molecular mass will pass through milipore filter, and the xylan that relative molecular mass is larger is then trapped; Permeate gets back to the alkaline cooking stage that step (1) circulates or enters step (3) after supplementing alkali.
Milipore filter described in step (a) retain relative molecular mass 1000 ~ 1500.
Centrifugation described in step (b) refers to that the supercentrifuge with 1000 ~ 5000 revs/min is separated.
The supernatant that step (b) obtains reclaims ethanol through decompression distillation, and the ethanol of recovery can be got back to settling system and recycle, and continues to get back to settling system after the residue cooling after decompression distillation.
Principle of the present invention is: bagasse contains abundant hemicellulose, it is xylan that its hemicellulose mainly forms, under room temperature, the degree of polymerization is to be dissolved in certain density aqueous slkali lower than the hemicellulose of 150, cellulose and lignin are then relatively stable, thus the separation of easy molten hemicellulose can be realized, after being separated, hemicellulose has very big difference due to relative molecular mass and extracting alkali lye, extracting alkali lye can be separated with hemicellulose by the mode of ultrafiltration, the hemicellulose of extracting can be deposited in ethanolic solution, the separation of hemicellulose can be realized by high speed centrifugation, ethanol can reclaim ethanol by decompression distillation, bagasse after extracting adopts conventional method slurrying, little to the quality influence of paper pulp, can improve the effect of slurrying delignification and the efficiency of alkali collection.
Compared with prior art, the present invention has the following advantages and beneficial effect:
(1) the present invention is while traditional slurrying, adds a new product, can improve competitiveness and the economic benefit of enterprise;
(2) the present invention is by pre-extracting bagasse hemicellulose, can improve the production capacity of unit equipment, reduces boiling chemicals and consumes and energy consumption, improve the efficiency of slurrying delignification;
(3) viscosity of Bagassepulping black liquor of the present invention is starkly lower than conventional boil black liquor, can improve brown stock detersive efficiency and reduce slurry amount.
(5) the inventive method can also reduce the alkali charge of follow-up bagasse boiling, reduces the temperature and time of cooking and heat-preservation, reduces the consumption of following bleaching chemicals, and reaches energy-saving and cost-reducing object.
(6) in the inventive method, after the boiling of extracting bagasse, the viscosity of black liquor can decline greatly, improves the efficiency of chemical recovery system evaporation, reduces fouling of evaporator, improves the thermal efficiency of alkali collection combustion furnace.
Detailed description of the invention
Below in conjunction with embodiment, the present invention is described in further detail, but embodiments of the present invention are not limited thereto.
Embodiment 1
A pulping process for the easy molten hemicellulose of pre-extracting bagasse, comprises the following steps:
(1) alkali density of bagasse: with sodium hydroxide solution (25 DEG C) extracting bagasse at normal temperatures of 40g/L, per kilogram over dry bagasse 8L concentration is the sodium hydroxide solution of 40g/L, extraction times 1 hour, bagasse extract content 10.32%;
(2) extraction of extract: extract and bagasse are first filtered, cutting out partial extract, is then expressed to the mass dryness fraction of more than 30% with two roll press or screw extruder by the bagasse after extracting;
(3) alkaline cooking of extracting bagasse: the bagasse soda-aq cooking of step (2) gained is carried out boiling, process conditions are as follows: sodium hydroxide concentration is 16% of Bagasse Material quality, anthraquinone consumption is 0.1% of Bagasse Material quality, all relative to over dry bagasse weight, cooking liquor, than 5.5:1, is warmed up to 60 minutes holding temperature time, cooking and heat-preservation temperature 160 DEG C, temperature retention time 30 minutes, the H factor 213.Boiling result: paper pulp kappa number 5.98, screened yield 52.34%, black liquor solid concentration 90.6g/L, black liquor 25 DEG C, 30% solid content time viscosity be 2.14CP, pulp viscosity 24.46CP, pulp brightness 50.60%.
The extract that above-mentioned steps (2) obtains is isolated to hemicellulose, and concrete steps are:
The ultrafiltration of (a) extract: extract step (2) obtained first filters with 200 eye mesh screens, be separated tiny bagasse, then with retain relative molecular mass be 1000 milipore filter filter, get back to the alkaline cooking stage that step (1) circulates or enters step (3) after permeate supplemental hydrogen sodium oxide molybdena, be transferred to next step when organic concentration in trapped fluid reaches more than 40g/L;
The alcohol settling of (b) trapped fluid: the trapped fluid that step (a) the is obtained alcohol settling of 2 times of volume ratios, the precipitation mixture centrifuge of 3000 revs/min is separated 30 minutes, obtain hemicellulose, clear liquid send decompression distillation to reclaim ethanol.Over dry bagasse per ton is separable obtains hemicellulose 80 kilograms.
Embodiment 2
A pulping process for the easy molten hemicellulose of pre-extracting bagasse, comprises the following steps:
(1) alkali density of bagasse: with sodium hydroxide solution (25 DEG C) extracting bagasse at normal temperatures of 100g/L, per kilogram over dry bagasse 8L concentration is the sodium hydroxide solution of 100g/L, extraction times 1 hour, bagasse extract content 16.22%;
(2) extraction of extract: first extract extract according to embodiment 1 step (2), then with 3 times of washings of the clear water to initial over dry bagasse weight, finally with two roll press or screw extruder, the bagasse after washing is expressed to the mass dryness fraction of more than 30%, extrudes liquid and be mixed into together in extract;
(3) alkaline cooking of extracting bagasse: the bagasse soda-aq cooking of step (2) gained is carried out boiling, process conditions are as follows: sodium hydroxide concentration is 15% of Bagasse Material quality, anthraquinone consumption is 0.1% of Bagasse Material quality, all relative to over dry bagasse weight, cooking liquor, than 5.5:1, is warmed up to 60 minutes holding temperature time, cooking and heat-preservation temperature 160 DEG C, temperature retention time 30 minutes, the H factor 213.Boiling result, paper pulp kappa number 4.50, screened yield 44.43%, black liquor solid concentration 86.4g/L, black liquor 25 DEG C, 30% solid content time viscosity be 1.88CP, pulp viscosity 20.12CP, pulp brightness 52.80%.
The extract that above-mentioned steps (2) obtains is isolated to hemicellulose, and concrete steps are with the step (a) of embodiment 1 and step (b).Over dry bagasse per ton is separable obtains hemicellulose 130 kilograms.
Embodiment 3
A pulping process for the easy molten hemicellulose of pre-extracting bagasse, comprises the following steps:
(1) alkali density of bagasse: with sodium hydroxide solution (25 DEG C) extracting bagasse at normal temperatures of 180g/L, per kilogram over dry bagasse 8L concentration is the sodium hydroxide solution of 180g/L, extraction times 1 hour, bagasse extract content 12.62%;
(2) extraction of extract: with embodiment 2 step (2);
(3) alkaline cooking of extracting bagasse: the bagasse soda-aq cooking of step (2) gained is carried out boiling, process conditions are as follows: sodium hydroxide concentration is 14.5% of Bagasse Material quality, anthraquinone consumption is 0.1% of Bagasse Material quality, all relative to over dry bagasse weight, cooking liquor, than 5.5:1, is warmed up to 60 minutes holding temperature time, cooking and heat-preservation temperature 155 DEG C, temperature retention time 30 minutes, CFH 39.Boiling result, paper pulp kappa number 5.21, screened yield 50.58%, black liquor solid concentration 88.8g/L, black liquor 25 DEG C, 30% solid content time viscosity be 1.92CP, pulp viscosity 21.86CP, pulp brightness 52.20%.
The extract that above-mentioned steps (2) obtains is isolated to hemicellulose, and concrete steps are with the step (a) of embodiment 1 and step (b).Over dry bagasse per ton is separable obtains hemicellulose 90 kilograms.
Comparative example 1
Directly bagasse and chemicals are joined boiling vessel carries out boiling, process conditions are as follows: sodium hydroxide concentration is 18% of Bagasse Material quality, anthraquinone consumption is 0.1% of Bagasse Material quality, all relative to over dry raw material weight, cooking liquor compares 5.5:1, little steam bleeding temperature 150 DEG C, is warmed up to 40 minutes little steam bleeding time, little steam bleeding temperature retention time 10 minutes; Cooking and heat-preservation temperature 165 DEG C, little steam bleeding to temperature retention time 20 minutes, temperature retention time 50 minutes, the H factor 643.Boiling slurry Kappa number 8.2, screened yield 55.87%, black liquor solid concentration 95.5g/L, black liquor 25 DEG C, 30% solid content time viscosity be 8.26CP, pulp viscosity 18.22CP, pulp brightness 46.01%, this method cannot reclaim bagasse hemicellulose.
Comparative example 2
(1) the pre-extracting of the alkali of bagasse: the pre-extracting of Bagasse Material under ramp case, alkali charge is 8% of Bagasse Material quality, pre-extracting liquid-solid ratio 5.5:1, extraction temperature 140 DEG C, 20 minutes heating-up times, temperature retention time 50 minutes, reaction end pH value 6.8, bagasse extract content 31.13%, the non-pulping of bagasse after extracting.
(2) separation of bagasse extract: because pre-extracting carries out in pressure vessel, the separation that pre-extracting is difficult to carry out extract is carried out in existing digesting apparatus is as rotary spherical digester, steam pipe, the pre-extraction device of pressure of separable extract must be increased, the present invention is in order to contrast the effect of pre-extracting hemicelluloses under ramp case, less than 100 DEG C are cooled to pre-extracting bagasse, then blowing from boiling vessel, adopt two roll press the bagasse of pre-extracting to be expressed to the mass dryness fraction of more than 30%, collect the extract be separated.
(3) alkaline cooking of pre-extracting bagasse: the bagasse soda-aq cooking of step (2) gained is carried out boiling, process conditions are as follows: sodium hydroxide concentration is 10% of Bagasse Material quality, anthraquinone consumption is 0.1% of Bagasse Material quality, all relative to over dry raw material weight, cooking liquor, than 5.0:1, is warmed up to 60 minutes holding temperature time, cooking and heat-preservation temperature 160 DEG C, temperature retention time 30 minutes, the H factor 213.Boiling result: paper pulp kappa number 6.54, screened yield 53.85%, black liquor solid concentration 85.4g/L, black liquor 25 DEG C, 30% solid content time viscosity be 6.25CP, pulp viscosity 24.28CP, pulp brightness 48.64%.
Extract comparative example 2 step (2) obtained is separated hemicellulose, concrete steps are with the step (a) of embodiment 1 and step (b), found that the hemicellulose amount obtained with alcohol settling is little, over dry bagasse per ton is separable obtains hemicellulose 8 kilograms.
Comparative example 1 illustrates traditional bagasse caustic soda anthraquinone boiling result, and boiling alkali charge is high, and digestion time is long, holding temperature is high, the H factor is large, and energy consumption is high, and the viscosity of black liquor is large, paper pulp kappa number is high, the viscosity of paper pulp is low, and the whiteness of paper pulp is low, means that delignification efficiency is low, fiber degradation is serious, and the consumption of following bleaching chemicals is large.
Comparative example 2 illustrates carries out the pre-extracting of alkali when being warmed up to 140 DEG C, can find that the extracting amount of bagasse is up to 31.13%, the hemicellulose of bagasse is usually at 25-30%, and whole bagasse hemicellulose can not be removed in soda pulping process process, the hemicellulose of 30% ~ 40% is also had to remain, so carry out the pre-extracting of alkali at elevated temperatures, containing a large amount of lignins in extract, half-and-half cellulosic separation is very unfavorable in the existence of these lignins, pre-extract pH value is at neutral range, the hemicellulose that neutral range dissolves is limited, only have the very little hemicellulose of the degree of polymerization just can be dissolved in pre-extract, typically in the pre-extracting incipient stage, easy molten hemicellulose is in alkaline range stripping, owing to being at high temperature carry out pre-extracting, the hemicellulose dissolved is degraded, generate mutation saccharic acid, pre-extract pH is declined, partly soluble hemicellulose is due to system pH decline, again can be redeposited on fiber, the very low hemicellulose of the degree of polymerization is only had finally to be dissolved in extract, but along with the carrying out of reaction, this part hemicellulose also can continue degraded, finally cause the hemicellulose with obtaining during alcohol settling little.
Embodiment 1 illustrates the result obtained according to method of the present invention, compare conventional method, the present invention can reduce boiling alkali charge, reduces holding temperature, reduce digestion time, thus reach energy-saving and cost-reducing effect, improve the efficiency of boiling delignification, improve the viscosity of paper pulp, improve the whiteness of paper pulp, reduce the viscosity of black liquor, increase new product simultaneously, increase economic efficiency.
Embodiment 2 illustrates according to method of the present invention, change the result that extracting paper mill wastewater obtains, display extracting paper mill wastewater has a great impact follow-up boiling, extracting alkali concn is higher, boiling delignification efficiency is higher, the extraction efficiency of hemicellulose is also higher, but digester yield declines also larger.
Embodiment 3 illustrates according to method of the present invention, continue the result that change extracting paper mill wastewater obtains, the result of display extracting paper mill wastewater to follow-up boiling is not the linear relation increased, after pre-extracting hemicelluloses, the alkali charge of follow-up alkaline cooking and holding temperature have larger impact to digester yield.
Above-described embodiment is the present invention's preferably embodiment; but embodiments of the present invention are not restricted to the described embodiments; change, the modification done under other any does not deviate from Spirit Essence of the present invention and principle, substitute, combine, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.
Claims (10)
1. a pulping process for the easy molten hemicellulose of pre-extracting bagasse, is characterized in that, comprise the following steps:
(1) alkali density of bagasse: Bagasse Material is used alkali density under the condition of normal temperature, obtains the crude extract containing bagasse;
(2) extraction of extract: the crude extract that step (1) obtains first is filtered, obtains the bagasse after extracting and filtrate; Then the bagasse after extracting is expressed to the mass dryness fraction of more than 30%, obtains extracting bagasse and squeezed fluid; Squeezed fluid is extract with filtrate mixing;
(3) alkaline cooking of extracting bagasse: the extracting bagasse that step (2) obtains is delivered to boiling vessel and carry out alkaline cooking and obtain paper pulp.
2. the pulping process of the easy molten hemicellulose of a kind of pre-extracting bagasse according to claim 1, it is characterized in that, normal temperature described in step (1) is 20 ~ 40 DEG C, the process conditions of described alkali density are: extraction times 30 ~ 60 minutes, alkali concn 30 ~ 180g/L, liquid-solid ratio 5:1 ~ 8:1.
3. the pulping process of the easy molten hemicellulose of a kind of pre-extracting bagasse according to claim 1, it is characterized in that, the alkali in the alkali density described in step (1) is NaOH.
4. the pulping process of the easy molten hemicellulose of a kind of pre-extracting bagasse according to claim 1, is characterized in that, step (2) also comprises the bagasse after to extruding and washs.
5. the pulping process of the easy molten hemicellulose of a kind of pre-extracting bagasse according to claim 1, is characterized in that, with the bagasse after two roll press or plodder extracting in step (2).
6. the pulping process of the easy molten hemicellulose of a kind of pre-extracting bagasse according to claim 1, it is characterized in that, the process conditions of the alkaline cooking described in step (3) are: cooking and heat-preservation temperature 140 ~ 160 DEG C, boiling alkali charge is 14 ~ 16% of Bagasse Material quality, 30 ~ 60 minutes cooking and heat-preservation time, boiling liquid-solid ratio 3 ~ 5.5:1, anthraquinone consumption is 0.1% of Bagasse Material quality.
7. the pulping process of the easy molten hemicellulose of a kind of pre-extracting bagasse according to claim 1, it is characterized in that, the alkali described in step (3) is NaOH.
8. the product of the pulping process acquisition of the easy molten hemicellulose of a kind of pre-extracting bagasse according to any one of claim 1 to 7, it is characterized in that, described product is that the extract that step (2) obtains is separating obtained, concrete steps are: extract first filters with 200 eye mesh screens by (a), be separated tiny bagasse, then with milipore filter, extract filtered; B () is when in the trapped fluid that step (a) obtains, organic concentration reaches more than 40g/L, precipitate trapped fluid with the absolute ethyl alcohol of 1 ~ 5 times of trapped fluid volume, the centrifugation of precipitation mixed liquor is precipitated thing hemicellulose product and supernatant.
9. product according to claim 8, is characterized in that, the milipore filter described in step (a) retain relative molecular mass 1000 ~ 1500.
10. product according to claim 8, is characterized in that, the centrifugation described in step (b) refers to that the supercentrifuge with 1000 ~ 5000 revs/min is separated.
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| CN201510439465.1A Pending CN105113307A (en) | 2015-07-23 | 2015-07-23 | Pulping method via pre-extraction of bagasse easily soluble hemicelluloses, and product obtained via pulping method |
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| CN114150522A (en) * | 2021-08-10 | 2022-03-08 | 天津科技大学 | Low-energy-consumption pulping method for quickly dissolving out hemicellulose |
| CN114687234A (en) * | 2022-03-31 | 2022-07-01 | 华南理工大学 | Method for preparing fluff pulp by using bamboos and fluff pulp prepared by method |
| CN117107539A (en) * | 2023-09-22 | 2023-11-24 | 云南云景林纸股份有限公司 | Eucalyptus pulp with low polymerization degree and production process and application thereof |
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| CN106188600A (en) * | 2016-08-16 | 2016-12-07 | 东华大学 | Method and the purposes of heterogeneous composite membrane is prepared with coir fibre nanometer fibril enhancing |
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| CN114150522B (en) * | 2021-08-10 | 2024-01-05 | 天津科技大学 | Low-energy-consumption pulping method for rapidly dissolving hemicellulose |
| CN114687234A (en) * | 2022-03-31 | 2022-07-01 | 华南理工大学 | Method for preparing fluff pulp by using bamboos and fluff pulp prepared by method |
| WO2023184969A1 (en) * | 2022-03-31 | 2023-10-05 | 华南理工大学 | Method for preparing fluff pulp from bamboos, and fluff pulp prepared thereby |
| CN117107539A (en) * | 2023-09-22 | 2023-11-24 | 云南云景林纸股份有限公司 | Eucalyptus pulp with low polymerization degree and production process and application thereof |
| CN117107539B (en) * | 2023-09-22 | 2024-05-03 | 云南云景林纸股份有限公司 | Eucalyptus pulp with low polymerization degree and production process and application thereof |
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