CN100373001C - Pulping technique for fibers in grass class - Google Patents

Pulping technique for fibers in grass class Download PDF

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CN100373001C
CN100373001C CNB2005100908686A CN200510090868A CN100373001C CN 100373001 C CN100373001 C CN 100373001C CN B2005100908686 A CNB2005100908686 A CN B2005100908686A CN 200510090868 A CN200510090868 A CN 200510090868A CN 100373001 C CN100373001 C CN 100373001C
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weight percentage
raw material
black liquor
boiling
fibers
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CN1760445A (en
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陈松涛
李洪法
宋明信
杨吉慧
孙利军
路敦所
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Shandong Tralin Paper Co Ltd
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Shandong Tralin Paper Co Ltd
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Abstract

The present invention discloses a pulping technology of grass fibers. The pulp is made through the processes of preprocessing, once steaming and secondary steaming. The technology can overcome the insufficiency of low quality, high energy consumption and large environment pollution of the existing non-wood fiber pulp. The pollution to the environment is reduced, and the discharged black liquor for making pulp per ton is reduced by 50%. The silicon content in the black liquor is reduced by 50%, and water is saved by 50%. The formed pulp has the characteristics of light color, high whiteness, low hardness, high folding resistant strength, easy pulping and easy bleaching.

Description

Grass fiber pulping process
Technical field
The present invention relates to a kind of pulping process of fibers in grass class raw material, belong to the paper industry technical field.
Background technology
As everyone knows, can the fibers in grass class raw material become the paper making raw material of human kind sustainable development, is the problem that countries in the world are paid close attention to.It has compared many inferior positions with wood fiber raw material, as its harvesting, transportation, a large amount of labours of storage needs, raw material collection radius is little, and paper quality is inferior, and environmental problem is serious etc.
By analysis, the reason that causes has: the collection and the transportation radius of raw material are little, have limited the scale of straw pulp mill, cause its labor productivity lower, and the straw pulp mill scale in the world is basically all below 100,000 tons/year at present, and majority is ten thousand tons/year of 1-3.
Technology and production equipment fall behind: present straw pulp production technology does not also have to work out according to the slurrying characteristics of dogstail fully, and the maximization and the automatization level of production equipment are low.Therefore, specific energy consumption, water consumption, fibrous raw material and the industrial chemicals of straw pulp production consume high.
After the socio-economic development, the price of labour power improves, and the harvesting of straw resource, transportation, storage need a large amount of labours, and the mechanization problem of these links does not have corresponding solution.
Because the fibers in grass class form makes paper strength, surface strength, the opacity of straw pulp lower than timber.
Be exactly environmental problem in addition, the black liquor treatment of straw pulp is not solved at all so far, as builds a straw pulp alkali recycling engineering and recoup the investment than the wood pulp alkali of building equal scale many, and its amount of investment is equivalent to build the investment of an a complete set of paper production line; See technically, because heteroproteose cell and fiber fines are many in the dogstail raw material, the pentosan content height, so that the slurry drainability is poor, the black liquor difficulty is extracted in the washing back; Black liquor viscosity is big, and concentration is low, and evaporation load is big, and conductivity of heat is poor, and burning causes difficulty; Silicone content height in the black liquor solid, expanded performance is poor during burning, and calorific capacity is low, and white clay settleability and strainability are poor after the causticization, and the alkali loss rate is high.Get to the bottom of it is that existing digesting technoloy is also unreasonable on earth.
Grass class pulping technique is a system engineering, to study the overall process of slurrying according to the inhomogeneity of the biological structure of grass fiber raw material and the particularity of chemical composition, mainly be the characteristics of research fibers in grass class slurrying: 1. heavily get the raw materials ready, silica removal, remove heteroproteose cell, improve pulp quality, drainability; 2. the characteristic of grass fiber delignification.Owing in the grass fiber the easy molten lignin of more alkali is arranged, its slurrying difficulty is reduced, but it requires higher delignification rate that fiber is dissociated again simultaneously, so its pulping process should be very different with timber.3. owing to silicone content height in the raw material, the carbohydrate content height causes its black liquor viscosity height, and recovery difficult is big.4. contain a large amount of heteroproteose cells in the fibers in grass class (now being), papermaking is formed a series of harm.5. the bleachability of straw pulp is good than timber, easily adopts short flow process, and chlorine-free bleaching reaches high whiteness.
There are many technical staff to be devoted to the research of this respect, such as, application number is the processing method of a kind of black liquid of 98111534.9, belong to papermaking waste material processing method field, comprise following processing step: the black liquor after the boiling is entered the black liquor storage pool, during next boiling, after again this black liquor being put into rotary spherical digester, measure the alkalinity of black liquor, the needs according to boiling are added into caustic soda again, carry out boiling.The purpose of this invention is in order to reduce production costs, cut down the consumption of energy, boost productivity, reduce environmental pollution, but this method has just proposed a design, without any technological parameter.
Hubei Polytichnic College's journal 99 years 14 3 phases of volume have been delivered the article that is entitled as " strengthening imagination and Preliminary Practice that dogstail is got the raw materials ready and reforms boiling ", a kind of boiling thinking that this article discloses: low temperature high speed cooking, big liquor ratio boiling, secondary boiling.Comprise that particularly hot black liquor preimpregnation (can mend alkali) pre-row's black liquor one white liquid two that steams steams cold spurting.It adopts white liquid displacement carrying out two steamings, then successively with warm black liquor, washings displacement, and has adopted cold spurting.On technology, more complicated, and without any technological parameter.
99 years 3 phases of light industry and machinery have been delivered the article of " the energy saving and pollution alleviation transformation of batch cooking workshop section (author Wang Xiyuan) ", the document is thought on the basis of having summed up RDH (displacement heating fast) technology, boiling of wood pulp Extended Delignification and straw pulp low temperature high speed cooking should possess following condition: warm black liquor, hot black liquor preimpregnation (utilize residual alkali, have dense than low alkali when playing steaming); The bulk delignification initial stage adds white liquid (forming high-alkali, sulphur hydrogen radical ion concentration); Final stage of cooking adopts washing black liquid displacement (reducing stripping lignin intensity and ion concentration); Boiling begins and end has lower temperature; Overall process adopts big liquor ratio, the low even hot digestion of solid content; Cold spurting.The warm black liquor that proposes in pollutant that each section washed out that the document proposes and the pot merges, and reclaims heat and part chemicals then in the preheating preimpregnation, and the document is an imagination, and relevant parameters is not provided.
99 years 4 phases of Jiangsu papermaking disclose one piece and have been entitled as the article of " imagination of rotary spherical digester replacing and digesting technoloy flow process ", and the basic principle of the document is: big liquor ratio (1: 4.5-5); Secondary boiling (indirect temperature black liquor one steams, and hot black liquor displacement two is steamed), displacement washing in the ball, cold spurting, it is dense to replenish alkali with white liquid.The document adopts the outer preimpregnation of white liquid ball, does not disclose concrete technological parameter.
International Paper 20 discloses one piece and has been entitled as the article of " the lab scale research of Trial of Displacement Cooking of Wheat Straw " 1 phases of volume, and this article thinks that the condition of wheat straw alkaline cooking is: the dense uniform distribution in whole digestion process of alkali; Keep the lignin low in the cooking liquor or the concentration of other leachables; Boiling temperature is too not high.The document proposes: carry out white liquid temperature black liquor preimpregnation (being heated to 120 ℃) in the pot, adopt the white liquid and the hot black liquor displacement of different liquor ratios and finish boiling, replace black liquor with washings.
Wood fiber raw material at China is in great shortage, and as agricultural country, the present situation that the output of annual fibers in grass class is but very big wants the real demand that satisfies paper industry, must study the characteristic of fibers in grass class, and existing digesting technoloy is improved.
Therefore, China does not also have the pulping process of the practicable grass fiber of a cover at present, should be as early as possible from the fundamental realities of the country of China, work out a kind of quality that can not only improve straw pulp, and can reduce the careless class pulping process of the treating capacity and the liquid waste processing difficulty of waste liquid, be a great problem in the current paper technology.
Summary of the invention
The object of the present invention is to provide a kind of preprocess method of grass fiber pulping process.
Another object of the present invention is to provide a kind of once boiling method of grass fiber pulping process.
Another object of the present invention is to provide a kind of secondary boiled method of grass fiber pulping process.
Another object of the present invention is to provide the black liquor silicon removing method in a kind of grass fiber pulping process.
Another object of the present invention is to provide a kind of pulping process of non-wood fiber fibers in grass class, this technology can overcome the existing deficiency that the non-wood fiber pulp quality is low, energy consumption is high, environmental pollution is big.
In order to realize the object of the invention, the preprocess method of a kind of grass fiber pulping process of the present invention is: the fibers in grass class raw material is flooded through maceration extract, through holocellulose weight percentage in the fibers in grass class raw material of dipping is 60-70%, total lignin weight percentage is 12-20%, the poly-pentose weight percentage is 20-27%, all for the over dry raw material.
In addition, also contain ash content and benzene-pure extract in the fibers in grass class raw material through dipping.
The mode that said impregnation process adopts is: maceration extract is flooded the fibers in grass class raw material, make liquor ratio reach 1: 2.1-4.5, temperature is in 85-120 degree centigrade of insulation with mixed 10-100 minute under normal pressure, wherein in the condition insulation of 85-95 degree with mix 10-40 minute for well.
The content of alkali is the 25-35 grams per liter in the described maceration extract, and the over dry material quantity is 1 with the ratio of the total liquid weight of maceration extract: 2.1-4.5; When the used black liquid consistency of impregnation process is 11-14 ° of Be ' (20 ℃), SiO in the black liquor 2Content is less than 2.1%, when being preferably 12-14 ° of Be ' (20 ℃), and SiO in the black liquor 2Content is less than 1.86%, and solid concentration 14-20% is preferably 16-20%.
A kind of once boiling method of grass fiber pulping process, behind the fibers in grass class material cooking, the holocellulose weight percentage is 60-75% in the fiber, total lignin weight percentage is 8-10.0%, the poly-pentose weight percentage is 22-27%, is preferably, and the holocellulose weight percentage is 65-75%, total lignin weight percentage is 8-9%, and the poly-pentose weight percentage is 22-24%; All for the over dry raw material.
The once boiling method adopts steam-heated mode, feeds water vapour in boiling vessel, make the pressure of steam be 0.3-0.5Mpa after, middle little venting once, be 30-80 minute heat time heating time, temperature is 140 ℃-150 ℃, be incubated 10-40 minute, take out then, discharge opeing.
Wherein, boiling mode of the present invention can be divided into continuously stewing and batch (-type) boiling, and concrete technology can be adjusted according to employed boiling mode.
Such as adopting the batch (-type) digesting technoloy can be: in boiling vessel, feed water vapour, make the pressure of steam be 0.3-0.4Mpa after, the pressure to boiling vessel of exitting is zero or near zero, again with put to the boiling vessel internal pressure be 0-0.02Mpa for well.Make the pressure in the rotary spherical digester reach 0.3-0.4Mpa once more, under the pressure condition of 0.3-0.4Mpa, be equivalent to 140 ℃-150 ℃ of temperature, heat, be 40-80 minute heat time heating time, and insulation is 10-40 minute under the pressure of 0.3-0.4Mpa, takes out then, discharge opeing.
The continuously stewing mode is: feed water vapour in first boiling pipe, after making the pressure of steam be 0.4-0.45Mpa, heat with this understanding, be equivalent to 140 ℃-150 ℃ of temperature, be 30 minutes heat time heating time, and insulation is 20 minutes under the pressure of 0.4-0.45Mpa, and boiling vessel heats at leading portion, back segment insulation is taken out, discharge opeing then.
Before once boiling, can carry out preliminary treatment earlier, be 60-70% through holocellulose weight percentage in the fibers in grass class raw material of dipping, total lignin weight percentage is 12-20%, the poly-pentose weight percentage is 20-27%, all for the over dry raw material.
A kind of secondary boiled method of grass fiber pulping process, the composition of secondary boiled back gained slurry is: the holocellulose weight percentage is 70-80%, total lignin weight percentage is 0.5-2.0%, and the poly-pentose weight percentage is 21-26%, all for the over dry raw material.
Before secondary boiled, can carry out once boiling earlier, after the boiling in the fiber holocellulose weight percentage be 60-75%, total lignin weight percentage is 8-10%, the poly-pentose weight percentage is 22-27%, all for the over dry raw material.
Preferably also comprising preliminary treatment, is 60-70% through holocellulose weight percentage in the fibers in grass class raw material of dipping, and total lignin weight percentage is 12-20%, and the poly-pentose weight percentage is 22-27%, all for the over dry raw material.
A kind of secondary boiled method of pulping process of fibers in grass class, be that fibers in grass class is mixed with cooking liquor, adopt steam-heated mode, steam pressure is upgraded to 0.5-0.75MPa, temperature is at 155-165 ℃, digestion time 40-80 minute, be incubated 20-60 minute, can discharging pulp liquid from boiling vessel.
Wherein: adopt the batch (-type) digesting technoloy can be: fiber is mixed with cooking liquor, adopt steam-heated mode, steam pressure is upgraded to 0.5-0.6MPa, after once more little pressure of exitting to boiling vessel is reduced to 0.3-0.4MPa, makes the pressure of boiling vessel rise to 0.6-0.7MPa again, be equivalent to temperature at 155-165 ℃, temperature in the boiling vessel is risen, under the pressure of 06-0.7MPa, digestion time 40-80 minute, be incubated 20-60 minute, can discharging pulp liquid from boiling vessel.
The continuously stewing mode is: in first boiling vessel and second boiling vessel junction, fiber is mixed with cooking liquor, adopt steam-heated mode, steam pressure is upgraded to 0.7-0.75MPa, be equivalent to temperature at 155-165 ℃, cooking and heat-preservation 50-60 minute, from second boiling vessel grout outlet with the cold form discharging pulp liquid that spurts.
A kind of pulping process of fibers in grass class, be that fibers in grass class is carried out preliminary treatment earlier, again through once boiling, secondary boiled forming, through holocellulose weight percentage in the fibers in grass class raw material of dipping is 60-70%, total lignin weight percentage is 12-20%, the poly-pentose weight percentage is 20-27%, all for the over dry raw material
Behind the once boiling, the holocellulose weight percentage is 60-75% in the fiber, and total lignin weight percentage is 8-10.0%, and the poly-pentose weight percentage is 22-27%, all for the over dry raw material;
The composition of secondary boiled back gained slurry is: the holocellulose weight percentage is 70-80%, and total lignin weight percentage is 0.5-2.0%, and the poly-pentose weight percentage is 21-26%, all for the over dry raw material.
Researcher of the present invention analyzes the fibers in grass class raw material, discovery, must be handled it before boiling at the biological structure of grass fiber and the characteristic of chemical composition, some are handled in advance to the disadvantageous composition of pulping, such as impurity heteroproteose cells such as leaf, fringe, sheath, silicon.
Fibers in grass class raw material of the present invention can adopt existing fibers in grass class raw material commonly used, such as paddy and wheat grass, reed, giantreed, reed reed, awns bar etc.
Chemical composition to fibers in grass class raw material commonly used is analyzed, find that the holocellulose weight percentage is 65-72%, total lignin weight percentage is 18-20%, the poly-pentose weight percentage is 22-28%, benzene-pure extract weight percentage is 2-3%, the ash weight percentage is 7-11%, all for the over dry raw material.
Before raw material is flooded, can adopt prior art that raw material is carried out preliminary treatment, promptly adopt conventional dried, wet feed preparation, to remove impurity such as leaf, fringe, grain, marrow, can alleviate the pressure of subsequent technique like this, and improve the quality of straw pulp.Dried, wet feed preparation can adopt existing conventional equipment, such as chaffcutter, screening machine, dust removal machine, wet cleaner, wet scrubbing Straw-crumbling machine, inclined screw Water Extraction Machinery etc.Fibers in grass class raw material through the removal moisture content after getting the raw materials ready also can be described as fine fodder, and the moisture of deduction dogstail is the over dry grass, and the length of general blade is at 15-30mm, and the technology of getting the raw materials ready of raw material is technology as well known to those skilled in the art.
The mode that the said impregnation process of the present invention adopts is: maceration extract is flooded the fibers in grass class raw material, make liquor ratio reach 1: 2.1-4.5, temperature is in insulation more than 85 degrees centigrade with mix more than 10 minutes under normal pressure, wherein in the insulation of the condition of 85-95 degree with mix 10-40 minute for well.Maceration extract is contacted fully with raw material, make raw material dipping evenly fully.
The content of alkali is the 25-35 grams per liter in maceration extract, and over dry material quantity (T) is 1 with the ratio of the total liquid weight of maceration extract: 2.1-4.5.
Said maceration extract is to contain the dense black liquor of certain alkali, it is the mixed liquor of alkali and black liquor, the Controllable Temperature of black liquor is between 80-95 ℃, the alkali that adds in the black liquor can be caustic soda (NaOH), addition is controlled at the 25-36 grams per liter, be preferably the 28-32 grams per liter, black liquor can directly adopt the waste liquid that produces in the digestion process of preparation straw pulp, (liquor ratio reaches 1: 2.1-4.5) repetitive cycling is used the black liquor that produces in the preparation straw pulp under the condition of big liquor ratio like this, improve the extraction concentration of black liquor, reduce the discharge capacity of black liquor, administer thereby reach to concentrate, alleviate the purpose of environmental pollution and water saving, also guaranteed simultaneously liquid phase cooking, circulation in the pot, the realization of displacement and heat washing.
When the used black liquid consistency of this stage impregnation process is 11-14 ° of Be ' (20 ℃), SiO in the black liquor 2Content is less than 2.1%, when being preferably 12-14 ° of Be ' (20 ℃), and SiO in the black liquor 2Content is less than 1.86%, and solid concentration 14-20% is preferably 16-20%.
Wherein, pH value is 11-14, preferred 11.8-13.3, and residual alkali number is the 8-12 grams per liter, is preferably the 8-10 grams per liter, COD is 150000-180000mg/l, is preferably 160000-180000mg/l.
Through holocellulose weight percentage in the fibers in grass class raw material of dipping is 60-70%, and total lignin weight percentage is 12-20%, and the poly-pentose weight percentage is 20-27%, all for the over dry raw material.
Raw material has been carried out the dipping preliminary treatment, utilized black liquor, made black liquor obtain cycling and reutilization, reduced the pressure that environment is handled black liquor as waste material, because to the preliminary treatment of raw material dipping, make that deviating from heteroproteose cell, hemicellulose, lignin when heat treated is main black liquid separation discharge.
Fiber behind the dipping adopts steam-heated mode through once boiling, feeds water vapour in boiling vessel, after making the pressure of steam be 0.3-0.5Mpa, be 30-80 minute heat time heating time, and temperature is 140 ℃-150 ℃, be incubated 10-40 minute, take out then, discharge opeing.One ton of paper pulp is only discharged the black liquor about 3 cubic metres.
At this moment, be 60-75% through holocellulose weight percentage in the fiber behind the once boiling, total lignin weight percentage is 8-10%, the poly-pentose weight percentage is 22-27%, all for the over dry raw material.
Treated fiber can be produced the paper pulp of better quality according to the digesting technoloy of this area routine, and the hemicellulose in the paper pulp of gained, poly-pentose content are low, and useful cellulose is higher.
Preferred digesting technoloy is: will mix with cooking liquor through pretreated fiber, adopt steam-heated mode, steam pressure is upgraded to 0.5-0.6Mpa, after once more little pressure of exitting to boiling vessel is reduced to 0.3-0.4MPa, make the pressure of boiling vessel rise to 0.6-0.7Mpa (being equivalent to temperature about 155 degree) again, the temperature in the boiling vessel is risen, under the pressure of 06~0.7Mpa, digestion time 40-80 minute, be incubated 20-60 minute, can discharging pulp liquid from boiling vessel.The volume of the black liquor of one ton of slurry production is about 7 cubic metres.
The gained pulp liquor can carry out countercurrent washing with the traditional wash engine known to the those skilled in the art, discharges black liquor.When the black liquid consistency of this moment is 12-14 ° of Be ' (20 ℃), SiO in the black liquor 2Content is less than 1.86%.This black liquor can be used as maceration extract and cooking liquor.If black liquor silicone content height, easily cause black liquor viscosity big, recovery difficult strengthens, influence pulp quality, silicone content can reduce 50% in the black liquor of pulping process gained of the present invention and adopt, and has reached the purpose of silica removal, but also can repetitive cycling use, reduced the pollution to environment, the black liquor that slurry per ton is discharged can reduce 50%, can save water 50%.
Containing in the described cooking liquor more than alkali 16 grams per liters, is good with the 16-25 grams per liter again, and over dry material quantity (T) is 1 with total liquid measure ratio of cooking liquor: 3.5-5.0.
By analysis, through after the boiling, the composition of gained paper pulp is: the holocellulose weight percentage is 70-80%, and total lignin weight percentage is 0.5-2.0%, and the poly-pentose weight percentage is 21-26%, all for the over dry raw material.
In order to reduce alkaline consumption and to improve the paper pulp rate, when preliminary treatment and boiling, all add a kind of in anthraquinone and the derivative thereof, the addition of anthraquinone and derivative thereof is the 0.6-0.8% of over dry material quantity.Digesting assistant anthraquinone and derivative thereof have the effect that improves delignification and protection carbohydrate.The result of use of anthraquinone is because of the different difference to some extent with pulping process of raw material.
Pulping process of the present invention can adopt existing digesting apparatus to finish, the digesting apparatus of using always such as those skilled in the art such as batch (-type) boiling vessel, continuous steamers.The batch (-type) boiling vessel comprises rotary spherical digester, digester; (continuous steamer vertical) transverse tube type and inclined tube-type.Concrete technology those skilled in the art can adjust in scope disclosed by the invention according to employed boiling mode.
In pulping process of the present invention, because silicone content can reduce 50% in the black liquor, can adopt black liquor as maceration extract and cooking liquor, black liquor can repetitive cycling use, and has reduced the pollution to environment, and the black liquor that slurry per ton is discharged can reduce 50%, can save water 50%.And formed paste color is shallow, and whiteness height, hardness are low, intensity folding height, easily making beating, easily bleaching, and the physical property performance of comparing its paper pulp with prior art tradition caustic soda AQ technology is respectively: caustic soda AQ technology, thick starch degree K15.0-18.0, unscreened yield 47.5-50%, screened stock hardness K10-13, screened stock whiteness (1SO) 36-39%, beating degree 28-32 ° of SR, weight in wet base 2-2.6 gram, fracture length 2-2.8Km, folding strength, 8-15 time
And the thick starch degree of this technology K9-14, unscreened yield 49.5-52.5%, screened stock hardness K7-12, screened stock whiteness (1SO) 39-48.7%, beating degree 18-28 ° of SR, weight in wet base 4.2-10.2 gram, fracture length 2.7-4.0Km, folding strength 50-150 time (more than be the statistics of 14 rotary spherical digesters).
Its association with pulp bleaching performance is respectively conventional slurry bleaching, hardness k13.2 before floating, concentration 5.2% before floating, bleaching time 4 hours, bleaching concentration 28g/l, bleachability 7.5%, terminal point whiteness (1SO) 74.5%, the residual chlorine 0.35% of terminal point, 28 ° of SR of beating degree, weight in wet base 1.8g, fracture length 2.875km, folding strength 10 times, hardness k10.8 before then this technology is floated, concentration 4.3% before floating, bleaching time 4 hours, bleaching concentration 24.7g/l, bleachability 6.7%, terminal point whiteness (1SO) 76.8%, the residual chlorine 0.369/l of terminal point, 30 ° of SR of beating degree, weight in wet base 2.1 grams, fracture length 3.675km, folding strength 79 times.
35 ° of SR of making beating back paper pulp physical property this technology beating degree, weight in wet base 1.69g, fracture length 3.65km, folding strength 68 times, tearability 480Nm, whiteness (1SO) 76.8%; And 31 ° of SR of conventional boiling beating degree, weight in wet base 1.7g, fracture length 3.254Km, folding strength 26 times, tearability 440Nm, whiteness (1SO) 74.5%.
Though more existing researchers propose with white liquid, black liquor grass fiber to be carried out boiling, but some imaginations have been proposed just, and do not propose with full black liquor impregnation and boiling, and researcher of the present invention thinks, as long as grass fiber is rationally handled, remove heteroproteose cell wherein, just can obtain the high-quality slurry that can match in excellence or beauty with wood pulp.Researcher of the present invention at first carries out pre-preg to grass fiber and handles, and then through twice boiling, when first time boiling, promptly drives away on marrow, the awn of wheat, the mud and silicon, and removes part pentosan and part lignin; When second time boiling, further delignification, the pentosan of oxidation stripping and lignin, good, the easy making beating of the slurry drainability of gained like this, easily bleaching, and also black liquor viscosity is low, the concentration height, and it is easy to extract, recyclable utilization.
Adopt process route of the present invention, the straw pulp of preparation can partly replace hardwood pulp, and paste color is shallow, whiteness is high; Hardness is low, intensity, folding height; Good, the easy making beating of drainability, easily bleaching, the fibers in grass class raw material carries out delignification under equal condition uniformly, and cooking liquor is in the dense constantly circulation heating down of certain alkali, the lignin of being deviate from is along with the continuous circulation of cooking liquor adds heat flow, be not easy condensation on fiber, therefore former pulp brightness can improve 5-8%.
Under the condition of big liquor ratio, reuse black liquor, reduce the discharge capacity (7 cubic metres of black liquor of slurry row per ton) of black liquor, administer, alleviate the purpose of environmental pollution and water saving thereby reach to concentrate.The character of digesting technoloy gained black liquor of the present invention is different with traditional handicraft, and silicone content can reduce 50% in the black liquor, and when the concentration raising of black liquid extraction, and viscosity reduces.
Silicone content is 3-5% in the black liquor that is produced in the general fibers in grass class raw pulp process, and silica and alkali effect generate sodium metasilicate, and easily fouling has influenced carrying out smoothly of alkali recovery process in combustion process.And the silicone content in the gained black liquor of the present invention only is 1-2%, has reduced the content (promptly having reached the purpose of silica removal) of silicon, and this also is one of obvious reason that reduces of viscosity, and swelling bulk coefficient (VIE) is enlarged markedly.
The pulping process of fibers in grass class of the present invention, pulp quality height, the deficiency that energy consumption is low, environmental pollution is big have reduced the pollution to environment, and the black liquor that slurry per ton is discharged can reduce 50%, can save water 50%.And formed paste color is shallow, and whiteness height, hardness are low, intensity folding height, easily making beating, easily bleaching.This technology can be applicable to the transformation of domestic ryegrass pulping factory, can improve pulp strength, improves the quality of waste liquid, is beneficial to recycling, reduces discharging of waste liquid and BOD, COD amount.
The specific embodiment
Following embodiment further describes the present invention, but described embodiment only is used to illustrate the present invention rather than restriction the present invention.
Test item reference standard: the mensuration GB/T 2677﹠amp of moisture; #8226; 2-1993; The mensuration GB/T2677﹠amp of content of ashes; #8226; 3-1993; Water extract Determination on content GB/T 2677﹠amp; #8226; 4-1993; 1%NaOH extract Determination on content GB/T 2677﹠amp; #8226; 5-1993; Benzene-pure extract Determination on content GB/T 2677﹠amp; #8226; 6-1994; The mensuration GB/T 2677﹠amp of holocellulose content; #8226; 10-1995; Acid-insoluble lignin Determination on content GB/T2677﹠amp; #8226; 8-1994; Acid soluble lignin Determination on content GB/T 10337-1989 (ultraviolet spectroscopy); Poly-pentose Determination on content GB/T 2677﹠amp; #8226; 9-1994 (dibrominated method).
The preparation of former material samples: air-dry wheat straw raw material sample is pulverized with pulverizer (Willey mill), and the gained powder screens through sample sifter, gets the part between 40~60 orders, uses for analyzing behind the equilibrium water conten.
The preparation of paper pulp sample: after the wet pulp sample disperseed, on sheeting mould, copy into the grout sheet, be torn into 5mm * 5mm fritter after air-dry with the copper mesh that is coated with clean calico, standby behind the equilibrium water conten.
Embodiment 1
In the present embodiment to the used impregnation process technology of soda pulping process, with 25 cubic metres rotary spherical digesters as boiling container, by analysis, the holocellulose weight percentage is 69.96% in the over dry wheat straw, and the poly-pentose weight percentage is 25.41%, ash content 7.35%, benzene one pure extract 2.35%, total lignin 19.85% will be through the long 2-3 of the wheat straw of preliminary treatment centimetre, 4.8 ton over dry wheat straw places boiling container to add the maceration extract of heating, maceration extract is made up of liquid caustic soda and black liquor.The concentration that adds alkali is NaOH (NaOH) solution of the percentage of 14% over dry grass weight, the content of NaOH is 28 grams per liters in the maceration extract, over dry wheat straw amount (T) is 1: 2.8 with the weight ratio of the total liquid measure of maceration extract, after in boiling container, adding the maceration extract wheat straw, rotary dipping is 0.25 hour under normal pressure, maceration extract is contacted fully with raw material, make the raw material dipping evenly.At dipping under the rotary spherical digester quiescent conditions after 1 hour, at 90 degrees centigrade of following rotary heat-insulatings and mixing 15 minutes.The used black liquor of preparation maceration extract, residual alkali 10.2 grams per liters, 12.22oBe ' (20 ℃), solid concentration 177.9 grams per liters, COD 152567mg/ liter, organic matter 106.17 grams per liters, organic matter/inorganic matter 1.48, silica 4.86 grams per liters, total alkali (in sodium oxide molybdena) 48.26 grams per liters, indifferent oxide 0.2%.Through holocellulose weight percentage in the wheat straw fiber raw material of dipping is 66.65%, and total lignin weight percentage is 13.21%, and the poly-pentose weight percentage is 23.5%, all for the over dry raw material.
After the dipping preliminary treatment, in rotary spherical digester, add alkali and black liquor and form cooking liquor for the first time, contain NaOH 30 grams per liters in the cooking liquor in the first time, over dry wheat straw material amount (T) is 1: 4.8 with the weight ratio of total liquid measure of cooking liquor for the first time, rotary spherical digester with 4.5 rev/mins rotation under, in rotary spherical digester, it is 0.35MPa that feeding steam makes its pressure, little pressure of exitting to rotary spherical digester approaches 0, makes the steam pressure in the rotary spherical digester rise to 0.35MPa again under the rotary spherical digester rotation, carries out the boiling first time under the pressure of 0.35MPa, after digestion time is 60 minutes,, spurt mouth from rotary spherical digester and carry out pump drainage liquid after 25 minutes in insulation under the pressure of 0.35MPa, take out, discharge black liquor.The holocellulose weight percentage is 67.61% in the fiber behind the once boiling, and total lignin weight percentage is 9.1%, and the poly-pentose weight percentage is 23.91%, all for the over dry raw material.At this moment, black liquor PH12.6, residual alkali 7.8 grams per liters, 16.12 ° Be ' (20 ℃), solid concentration 250.9 grams per liters, 247128 milligrams of COD, inorganic matter (sulfated ash, in NaOH) 92.96 grams per liters, organic matter 157.89 grams per liters, organic matter/inorganic matter 1.7, silica 7.21 grams per liters, total alkali (in sodium oxide molybdena) 60.28 grams per liters, indifferent oxide 6.2%.
Continue to replenish alkali and black liquor through the straw pulp fiber after the once boiling processing, wherein contain NaOH 26 grams per liters, over dry wheat straw amount (T) is 1: 4.6 with the weight ratio of the total amount of cooking liquor, in rotary spherical digester, feed steam, make the rotary spherical digester internal pressure reach 0.55MPa, little pressure of exitting to rotary spherical digester is reduced to 0.35MPa, make the rotary spherical digester internal pressure be raised to 0.65MPa again, carry out the boiling second time at the pressure rotary spherical digester of 0.65MPa under with 4.5 rev/mins rotation, digestion time 40 minutes, static insulation 60 minutes mouthful is carried out heat from spurting of rotary spherical digester and is spurted, and carries out countercurrent washing generation black liquor with the par belt pulp washing machine.By analysis, through after the boiling, the composition of gained paper pulp is: the holocellulose weight percentage is 72.58%, and total lignin weight percentage is 1.23%, and poly-pentose weight percentage 21.73% is all for the over dry raw material.The black liquor PH13.6 that is generated, residual alkali 10.6 grams per liters, 12.5 ° Be ' (20 ℃), solid concentration 179.92 grams per liters, COD 153790 mg/litre, organic matter 112 grams per liters, organic matter/inorganic matter 1.51, silica 4.90 grams per liters, total alkali (with sodium oxide molybdena Na2O) 50.15 grams per liters, indifferent oxide 0.21%.
Embodiment 2
With embodiment 1, different is that the composition of rice-straw fibre raw material is: the holocellulose weight percentage is 67.6%, and the poly-pentose weight percentage is 26.8%, ash content 10.21%, benzene-pure extract 2.32%, total lignin 18.96%.
The holocellulose weight percentage is 66% in the wheat straw fiber raw material of dipping, and total lignin weight percentage is 16.03%, and the poly-pentose weight percentage is 20%, all for the over dry raw material.
The holocellulose weight percentage is 69.52% in the fiber behind the once boiling, and total lignin weight percentage is 9.74%, and the poly-pentose weight percentage is 19.75%, all for the over dry raw material.
The composition of secondary boiled gained paper pulp is: the holocellulose weight percentage is 75.73%, and total lignin weight percentage is 1.46%, and the poly-pentose weight percentage is 22.45%, all for the over dry raw material.
Embodiment 3
With embodiment 1, different is that the composition of rice-straw fibre raw material is: the holocellulose weight percentage is 67.6%, and the poly-pentose weight percentage is 27.6%, ash content 9.58%, benzene one pure extract 3.87%, total lignin 23.1%.
The holocellulose weight percentage is 63% in the wheat straw fiber raw material of dipping, and total lignin weight percentage is 14%, and the poly-pentose weight percentage is 20%, all for the over dry raw material.
The holocellulose weight percentage is 70.02% in the fiber behind the once boiling, and total lignin weight percentage is 8.8%, and the poly-pentose weight percentage is 25%, all for the over dry raw material.
The composition of secondary boiled gained paper pulp is: the holocellulose weight percentage is 76.58%, and total lignin weight percentage is 1.5%, and the poly-pentose weight percentage is 22%, all for the over dry raw material.
Embodiment 4
Present embodiment adopts the transverse tube type continuous steamer to carry out continuous steaming-boiling technology, by analysis, the holocellulose weight percentage is 68.9% in the over dry wheat straw, the poly-pentose weight percentage is 23.5%, ash content 7.35%, benzene one pure extract 3.12%, total lignin 19.85%, to be about 3 centimetres through the wheat straw of preliminary treatment, 4.8 tons of over dry wheat straws place the maceration extract that adds heating in first boiling pipe, and maceration extract is made up of liquid caustic soda and black liquor.The concentration that adds alkali is NaOH (NaOH) solution of the percentage of 16% over dry grass weight, the content of NaOH is 32 grams per liters in the maceration extract, over dry wheat straw amount (T) is 1: 4.5 with the weight ratio of the total liquid measure of maceration extract, temperature was mixed 20 minutes in 105 degrees centigrade under 0.1MPa pressure, maceration extract is contacted fully with raw material, make the raw material dipping evenly.The used black liquor of preparation maceration extract, residual alkali 9.8 grams per liters, 13.1 ° of Be ' (20 ℃), solid concentration 177.9 grams per liters, COD 16253mg/ liter.Through holocellulose weight percentage in the wheat straw fiber raw material of dipping is 67.86%, and total lignin weight percentage is 12.11%, and the poly-pentose weight percentage is 25.8%, all for the over dry raw material.
After the dipping preliminary treatment, adopt steam-heated mode, in first boiling pipe, feed water vapour, make the pressure of steam be 0.4Mpa after, temperature 145 degree heat, and be 30 minutes heat time heating time, is incubated 20 minutes, boiling vessel heats at leading portion, and back segment insulation is taken out, discharge opeing then.The holocellulose weight percentage is 72.52% in the fiber behind the once boiling, and total lignin weight percentage is 8.8%, and the poly-pentose weight percentage is 26%, all for the over dry raw material.
Carry out secondary boiled through the straw pulp fiber after the once boiling processing, in first boiling pipe and second boiling pipe junction, fiber is mixed with cooking liquor, adopt steam-heated mode, steam pressure is upgraded to 0.75Mpa, temperature 165 the degree, cooking and heat-preservation 60 minutes, from second boiling pipe grout outlet with the cold form discharging pulp liquid that spurts.
The composition of secondary boiled gained paper pulp is: the holocellulose weight percentage is 78.58%, and total lignin weight percentage is 1.2%, and the poly-pentose weight percentage is 26%, all for the over dry raw material.

Claims (9)

1. the pulping process of a grass fiber is characterized in that,
A) fibers in grass class is carried out preliminary treatment earlier, again through once boiling, secondary boiled forming, described preliminary treatment is an impregnation process, maceration extract is flooded the fibers in grass class raw material, make liquor ratio reach 1: 2.1-4.5, temperature is in the insulation of 85-120 degree centigrade condition with mix 10-100 minute for well under normal pressure; Further, the content of alkali is the 25-35 grams per liter in the described maceration extract;
B) in described once boiling, adopt steam-heated mode, in boiling vessel, feed water vapour, make the pressure of steam be 0.3-0.5Mpa after, middle little venting once, be 30-80 minute heat time heating time, temperature is 140-150 ℃, be incubated 10-40 minute, take out then, discharge opeing;
C) described secondary boiled method is that fibers in grass class is mixed with cooking liquor, adopts steam-heated mode, and steam pressure is upgraded to 0.5-0.75Mpa, temperature is at 155-165 ℃, digestion time 40-80 minute, be incubated 20-60 minute, can discharging pulp liquid from boiling vessel.
2. pulping process according to claim 1, it is characterized in that the mode that described dipping adopts is: temperature is incubated under the 85-95 degrees celsius and mixed 10-40 minute under normal pressure.
3. pulping process according to claim 1, it is characterized in that through described preliminary treatment, holocellulose weight percentage in the fibers in grass class raw material is 60-70%, total lignin weight percentage is 12-20%, the poly-pentose weight percentage is 20-27%, and each content is all for the over dry raw material.
4. technology according to claim 1 is characterized in that, during 20 ℃ of used black liquor of described impregnation process, concentration is 11-14 ° of Be ', SiO in the black liquor 2Content is less than 2.1%, solid concentration 14-20%.
5. technology according to claim 3 is characterized in that, during 20 ℃ of used black liquor of described impregnation process, concentration is 12-14 ° of Be ', SiO in the black liquor 2Content is less than 1.86%, and solid concentration is 16-20%.
6. pulping process according to claim 1, it is characterized in that behind once boiling the holocellulose weight percentage in the fiber is 60-75%, total lignin weight percentage is 7-11%, the poly-pentose weight percentage is 22-27%, all for the over dry raw material.
7. pulping process according to claim 6, it is characterized in that behind once boiling the holocellulose weight percentage in the cellulose is 65-75%, total lignin weight percentage is 8-10%, the poly-pentose weight percentage is 22-24%, all for the over dry raw material.
8. technology according to claim 1, it is characterized in that at the composition of described secondary boiled back gained slurry being: brown cellulose percentage composition is 70-80%, total lignin weight percentage is 0.5-2.0%, and the poly-pentose weight percentage is 21-26%, all for the over dry raw material.
9. technology according to claim 1 is characterized in that, the fibers in grass class raw material is carried out preliminary treatment, passes through once boiling, secondary boiled again, and when secondary boiled back gained black liquor was 20 ℃, concentration was 12-14 ° of Be ', SiO in the black liquor 2Content is less than 1.86%.
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CN1048736A (en) * 1989-07-31 1991-01-23 哈尔滨工业大学 A kind of paper made from mixed pulp of grass and synthetic fibre
US5885414A (en) * 1997-08-18 1999-03-23 Kvaerner Pulping Ab Method of producing pulp with high alkali cooking in the last cooking stage
CN1333403A (en) * 2001-08-30 2002-01-30 山东泉林纸业有限责任公司 Dogstail pulp large liquor ratio circular heating replacing digestion technology and digestion equipment thereof

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CN1048736A (en) * 1989-07-31 1991-01-23 哈尔滨工业大学 A kind of paper made from mixed pulp of grass and synthetic fibre
US5885414A (en) * 1997-08-18 1999-03-23 Kvaerner Pulping Ab Method of producing pulp with high alkali cooking in the last cooking stage
CN1333403A (en) * 2001-08-30 2002-01-30 山东泉林纸业有限责任公司 Dogstail pulp large liquor ratio circular heating replacing digestion technology and digestion equipment thereof

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