Background technology
The method of producing paper pulp with string has: chemical method, Mechanical Method, chemical mechanical pulping.In chemical method, divide lime method, soda processes, anthraquinone-soda processes, sulfate process again.Soda processes in the prior art is to be raw material with the string.Its technical process is at first to get the raw materials ready, the raw material that will carry out pretreated production paper pulp is packed in rotary spherical digester or the upright pot equipment such as (digester, vertical digesters), adding chemicals such as NaOH again and carry out the gas phase boiling, is exactly directly logical Steam Heating, insulation and produce qualified paper pulp.
Preliminary treatment described in the prior art has dry method preliminary treatment, wet pretreatment, does wet pretreatment.The dry method preliminary treatment is removed impurity such as grass kind plant leaf, awns, earth exactly.Wet pretreatment washes raw material exactly with water, dried wet pretreatment be exactly carry out above-mentionedly doing, two processes of wet pretreatment.
Grass class pulping technique is a system engineering, comprising preliminary treatment, researcher of the present invention thinks that preliminary treatment concerns whole pulping process, because, according to the particularity of the inhomogeneity of the biological structure of grass fiber raw material and chemical composition and according to the characteristics of fibers in grass class slurrying, researcher of the present invention proposes to need to pay attention to the characteristics of the following aspects: heavily get the raw materials ready silica removal 1., remove heteroproteose cell, improve pulp quality, improve drainability, reduce the discharging of black liquor; 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, papermaking is formed a series of harm.
The processing method of a kind of black liquid of Chinese patent ZL98111534.9, 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, next time is during 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.
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 hot black liquor preimpregnation (can mend alkali)-pre-steaming-row's black liquor-Bai liquid two steaming-cold spurting particularly.It adopts white liquid displacement carrying out two steamings, then successively with warm black liquor, washings displacement, and has adopted cold spurting.
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.
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.
Researcher of the present invention finds, prior art is not to adopting black liquor, especially the black liquor that can recycle of the present invention is described, and of the present inventionly be used for pretreated black liquor not only in preliminary treatment, and to whole pulping process generation significant effects, in view of this, the present invention is proposed.
Summary of the invention
The object of the present invention is to provide a kind of black liquid that utilizes that fibers in grass class is flooded pretreated method, this method makes maceration extract contact fully with raw material, make the dipping of raw material evenly complete, can make full use of afterheat and alkali in the black liquor, with the molten material of the theobromine in the forage, from forage, separate, for follow-up boiling provides condition.
A kind of basic technology of soda pulping, comprising pretreating process, as described below:
1) the fibers in grass class raw material that will cross through dry process places steeper;
2) after the maceration extract that the needed alkali of adding heating and black liquor form in steeper, under normal pressure, steeper rotates the needed time and boiling container is incubated needed time sum;
3) under the static condition of boiling container or under the boiling container rotating conditions, be heated to needed temperature,, be incubated the needed time under the condition that boiling container is static under this temperature or under the boiling container rotating conditions;
4) said steeper is the dipping screw machine, and said boiling container is a rotary spherical digester.
Grass raw material of the present invention comprises: wheat straw, straw, reed, reed reed, sorghum rod, bagasse, awns bar are good with wheat straw, reed again.
Preliminary treatment described in the present invention comprises dry process, exactly the removal process of impurity such as leaf, awns, earth when making raw material with wheat straw, exactly impurity such as the leaf in the wheat straw, awns, wheat, marrow are removed, the bar height of straw is preferably in more than 1 meter, 4 millimeters of cane diameters, bar wall thickness 0.3-0.4 millimeter pulp cavity is again to be cut into wheat straw 2-3 centimetre for good.Lignin content by wheat straw is higher slightly than straw, so be difficult to boiling than straw.
Boiling container of the present invention can be rotary spherical digester or upright pot, also can be slurrying industry other boiling containers commonly used.
Needed alkali and No. 2 black liquor of in steeper, adding heating, under normal pressure, use dipping screw machine rotation 0.1-0.4 hour for well, maceration extract is contacted fully with raw material, make the dipping of raw material evenly complete, can make full use of heat and alkali in the black liquor, with the molten material of the theobromine in the forage, from forage, separate, for boiling provides condition.
If adopt the rotary spherical digester boiling, its condition is at the static dipping of rotary spherical digester under the condition of normal pressure after 0.1-0.4 hour, under the rotary spherical digester rotating conditions, raw material in the rotary spherical digester of packing into is mixed, under normal pressure in insulation more than 85 degrees centigrade with mix more than 10 minutes, wherein in the insulation of the condition of 85-95 degree with mix 10-40 minute for well.The rotary speed of rotary spherical digester generally is controlled at 3-6 rev/min.
The black liquor that is added is hereinafter described No. 2 black liquor for well.In the alkali and the formed maceration extract of black liquor that adds in dipping screw machine and rotary spherical digester, used alkali can be aqueous slkali, is NaOH or anthraquinone-NaOH, and concentration is 13-15% over dry grass percetage by weight.
The content of alkali is the 25-35 grams per liter in immersion liquid, and over dry material quantity (T) is 1 with the weight ratio of the total liquid measure of maceration extract: 2.1-4.5.
Owing to before the boiling first time, raw material has been carried out the dipping preliminary treatment, utilized black liquor as waste material, make black liquor obtain cycling and reutilization, reduce environment () pressure that black liquor is handled, owing to, make at boiling first time heteroproteose cell that time deviates from, hemicellulose, lignin to be that main concentrated black liquid (black liquor) separates discharge to the preliminary treatment of raw material dipping.The concentrated black liquid of taking out, discharging during boiling for the first time is a black liquor.
Corresponding preliminary treatment of the present invention, the digesting technoloy that can adopt comprises rotary spherical digester boiling or vertically digesting, when adopting the rotary spherical digester boiling, can adopt washing fractional digestion technology in the ball, promptly, after process is carried out impregnation process to grass in rotary spherical digester, in rotary spherical digester, add alkali and black liquor and form cooking liquor for the first time, under the rotary spherical digester rotation, in rotary spherical digester, feed steam to needed vapour pressure, carry out little pressure of exitting to rotary spherical digester and approach zero, in rotary spherical digester, add again steam make reach needed pressure after, the needed time of insulation is carried out the cooking reaction first time under the rotary spherical digester rotating conditions, is incubated a period of time afterwards, and the heteroproteose cell that has reached this moment in the interior most of fiber of ball is degraded, the part hemicellulose, lignin also is degraded, take out from the mouth that spurts of rotary spherical digester this moment, discharge opeing, this process are equivalent to carry out a wet scrubbing and remove leaf, awns in ball, impurity such as stem marrow are discharged with black liquor, and at this moment the concentrated black liquid of Pai Chuing is No. No. 1 black liquor.
Discharge the mixture that in rotary spherical digester, replenishes alkali and black liquor (No. 2 black liquor) behind concentrated black liquid, form cooking liquor for the second time, in rotary spherical digester, feed steam, make and reach needed vapour pressure in the rotary spherical digester, after little venting makes the vapour pressure in the rotary spherical digester reduce to needed pressure, in rotary spherical digester, add steam again and reach required pressure once more, under the pressure that is arrived once more, be incubated, after keeping the needed time, carry out heat and spurt discharging, with traditional wash engine slurry is carried out countercurrent washing, formed cleaning solution is called black liquor No. 2.
More than alkalinity 26 grams per liters, be good with the 28-32 grams per liter again the first time of adding in rotary spherical digester that the mixture of alkali and black liquor (No. 2 black liquor) forms in the cooking liquor.Over dry material quantity (T) is 1 with the weight ratio of the total liquid measure of the cooking liquor first time: 3.5-5.0.In rotary spherical digester, feed water vapour, make the pressure of steam be 0.3-0.4Mpa after, the pressure to ball of exitting is zero or near zero, again with put to the ball internal pressure be 0-0.02Mpa for well.Under the rotation of rotary spherical digester, make the pressure in the rotary spherical digester reach 0.3-0.4Mpa once more, (be equivalent to about temperature 140 degree) carry out the boiling first time under the pressure condition of 0.3-0.4Mpa, digestion time is 40-80 minute, insulation is 10-40 minute under the pressure of 0.3-0.4Mpa, spurt from rotary spherical digester mouthful take out, discharge opeing, adding alkali and No. 2 black liquor contain in the cooking liquor more than alkali 16 grams per liters formed second time after discharge opeing, be good with the 16-25 grams per liter again, over dry material quantity (T) is 1 with total liquid measure ratio of the cooking liquor second time: 3.5-5.0.After adding alkali and No. 2 black liquor formed second time of cooking liquors, add steam pressure in the rotary spherical digester and rise to 0.5-0.6MPa.
Because the concentrated black liquid that boiling for the first time produces is discharged, fiber in the rotary spherical digester has been carried out the washing of a wet separation matter with regard to being equivalent to cooking liquor for the first time, after carrying out the boiling first time, carry out the boiling second time again again, proceed delignification reaction, so this technology is called washing fractional digestion technology in the ball.After once more little pressure of exitting to rotary spherical digester is reduced to 0.3-0.4MPa, make the pressure of rotary spherical digester rise to 0.6-0.7Mpa (being equivalent to temperature about 155 degree) again, temperature in the ball is risen, under the pressure of 06~0.7Mpa, carry out the boiling second time, digestion time 40-80 minute under the rotary spherical digester rotation, be incubated 20~60 minutes, spurt from rotary spherical digester and mouthful to carry out heat and spurt discharge, carry out countercurrent washing, form No. 2 black liquor with the traditional wash engine known to the those skilled in the art.When rotary spherical digester rotated, its rotary speed was 3-6 rev/min, with alkali preparation for the first time cooking liquor, used black liquor is black liquor No. 2 during cooking liquor for the second time.
In order to reduce alkaline consumption and to improve the paper pulp rate, in the boiling first time or for the first time, during boiling for the second time, 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.
Because after carrying out the boiling first time, the poly-pentose class that is generated in the digestion process, part lignin are discharged for the first time.The pressure ratio of water vapour is lower during boiling for the first time, the temperature in the ball low (about 130 degree).The not condensation of lignin that is generated when making boiling for the first time sticks on the fiber surface, makes the slurry water filtering performance good and wood pulp is approaching, residual alkali 0.09-0.2 grams per liter in starching after the black liquid extraction.
No. 1 black liquor of being produced after the boiling first time, one ton of paper pulp are only discharged No. 1 black liquor about 3 cubic metres, and No. 1 black liquor that one ton of slurry is produced and the volume of No. 2 black liquor are about 7 cubic metres.The pulp quality that this explained hereafter goes out is good, can partly replace hardwood pulp.
Adopt preliminary treatment of the present invention and in conjunction with described digesting technoloy, formed paste color is shallow, the whiteness height, hardness is low, intensity folding height, easily making beating, easily bleaching, 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 K 15.0-18.0, unscreened yield 47.5-50%, screened stock hardness K 10-13, 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 thick starch degree K 9-14 of the present invention, unscreened yield 49.5-52.5%, screened stock hardness K 7-12, screened stock whiteness (1SO) 39-48.7%, beating degree SR 18~28, 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 k 13.2 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%.
Unless otherwise indicated, black liquor of the present invention or concentrated black liquid according to as give a definition:
Contain residual alkali 6.5-8.5 grams per liter in the concentrated black liquid (No. 1 black liquor), solid concentration 220-260 grams per liter, inorganic matter is that sulfate ash (in NaOH) is the 85-95 grams per liter, organic matter 145-165 grams per liter, organic matter/inorganic matter 1.55~1.85, silica 6-8.5 grams per liter, total alkali (in sodium oxide molybdena) 50-70 grams per liter, indifferent oxide 0.1~0.3%, said percentage composition are black liquor total solid meter.The PH 11.6-13.0 of said concentrated black liquid (No. 1 black liquor), COD 24-26 ten thousand mg/litre, Baume degrees is 15~18 ° of Be ' (20 ℃).
Black liquor (No. 2 black liquor) contains residual alkali 9-11 grams per liter, solid concentration 165-185 grams per liter, inorganic matter sulfate ash (in NaOH) is the 65-75 grams per liter, organic matter 101-131 grams per liter, organic matter/inorganic matter 1.35-1.65, silica 3.5-6.5 grams per liter, total alkali (in sodium oxide molybdena) 40-58 grams per liter, indifferent oxide 0.1-0.3%, said percentage composition are all to black liquor total solid meter.Said black liquor (No. 2 black liquor) PH 12.6-13.9; COD 15-18.5 ten thousand millis/liter; Baume degrees is 11~14 ° of Be ' (20 ℃).
The present invention adopts washing fractional digestion technology in the ball, maceration extract is contacted fully with raw material, make the dipping of raw material evenly complete, can make full use of heat and alkali in the black liquor,, from forage, separate the molten material of the theobromine in the forage, and then through twice boiling, when first time boiling, promptly drive away marrow, the awn of wheat, earth and silicon, and remove big portion 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.
The present invention carries out reuse with the discharges heat and the chemical agent of batch cooking effectively, reduces the consumption of the energy greatly, also has the reduction pulp hardness, improves pulp quality, reduces alkaline consumption, reduces a series of advantages such as pollution to environment.And the process route that adopts researcher of the present invention to develop, 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 specific embodiment
Below the present invention is further illustrated with specific embodiment, will help the present invention and its advantage of tool are better understood, and following embodiment is to the unqualified effect of protection scope of the present invention, and protection scope of the present invention is determined by claim.
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, will be through the long 2-3 of the wheat straw of preliminary treatment centimetre, 4.8 tons of over dry wheat straws place the dipping screw machine to add the maceration extract of heating, and maceration extract is made up of liquid caustic soda and No. 2 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: 3.5 with the weight ratio of the total liquid measure of maceration extract, after in the dipping screw machine, 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.Dipping is after 1 hour, at 90 degrees centigrade of following rotary heat-insulatings and mixing 15 minutes in rotary spherical digester.No. 2 used black liquor of preparation maceration extract, residual alkali 10.2 grams per liters, 12.22 ° of Be ' of Baume degrees (20 ℃), solid concentration 177.9 grams per liters, COD152567mg/ 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%.
Embodiment 2
Device therefor and process conditions are basic same with embodiment 1 in the present embodiment, the concentration that only different is adds alkali is 13% over dry grass percetage by weight, NaOH content 35 grams per liters in the maceration extract, over dry wheat straw amount (T) is 1: 3.9 with the weight ratio of the total liquid measure of maceration extract, rotary dipping is 0.4 hour under the normal pressure, maceration extract is heated to 95 degree and wheat straw mixes rotary heat-insulating 30 minutes.
Embodiment 3
Used equipment and process conditions are basic same with embodiment 1 in the present embodiment, the concentration that only different is adds alkali is 15% over dry grass percetage by weight, the content of NaOH is 32 grams per liters in the maceration extract, over dry wheat straw amount (T) is 1: 4.2 with the weight ratio of the total liquid measure of maceration extract, rotary dipping is 0.3 hour under normal pressure, maceration extract is heated to 85 degree and wheat straw mixes rotary heat-insulating 40 minutes.
Embodiment 4
Present embodiment device therefor and process conditions basic with embodiment 1 with, the weight ratio of only different is over dry wheat straw amount (Kg) and the total liquid measure of maceration extract is 1: 4.5.
Embodiment 5
Washing fractional digestion technology in the ball of present embodiment, after process is flooded preliminary treatment to wheat straw in the foregoing description 1, in rotary spherical digester, add alkali and No. 2 black liquor formation 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, under the rotary spherical digester rotation, make the steam pressure in the rotary spherical digester rise to 0.35MPa again, under the pressure of 0.35MPa, carry out the boiling first time, after digestion time is 60 minutes, after 25 minutes, spurts mouth from rotary spherical digester and take out in insulation under the pressure of 0.35MPa, discharge opeing, what discharge is No. 1 black liquor, add alkali and No. 2 black liquor formed second time of cooking liquors after discharging No. 1 black liquor, contain NaOH 26 grams per liters in the cooking liquor for the second time, over dry wheat straw amount (T) is 1: 4.6 with the weight ratio of the total amount of boiling for the second time.In the discharge opeing process, discharge behind No. 1 black liquor when adding steam and mend into alkali and the black liquor formed second time of cooking liquor, in rotary spherical digester, feed steam and make the pressure in the ball rise to 0.55Mpa, the temperature in the rotary spherical digester raises continuously.
During preparation preliminary treatment maceration extract, No. 2 used black liquor PH 13.33, residual alkali 10.2 grams per liters, 12.22 ° of Be ' of Baume degrees (20 ℃), solid concentration 177.9 grams per liters, COD 152567mg/ liter, inorganic matter (sulfated ash, in NaOH) the 71.73g/ liter, organic matter 106.17g/ liter, organic matter/inorganic matter 1.48, silica 4.86g/ liter, total alkali (in sodium oxide molybdena) 48.26g/ liter, indifferent oxide 0.2%.
No. 1 black liquor PH12.6 that is discharged in the present embodiment, residual alkali 7.8 grams per liters, 16.12 ° of Be ' of Baume degrees (20 ℃), solid concentration 250.9 grams per liters, 247128 milligrams of COD, inorganic matter (sulfated ash is 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%.
After carrying out the boiling first time, replenish alkali and No. 2 black liquor by adding steam port after discharging No. 1 black 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, be incubated 60 minutes, mouthful carry out heat from spurting of rotary spherical digester and spurt, carry out No. 2 black liquor of countercurrent washing generation with the par belt pulp washing machine.No. 2 black liquor PH 13.6 that generated, residual alkali 10.6 grams per liters, 12.5 ° of Be ' of Baume degrees (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 is (with sodium oxide molybdena Na
2O) 50.15 grams per liters, indifferent oxide 0.21%.
Embodiment 6
Washing fractional digestion technology and equipment thereof are substantially with embodiment 6 in the ball of present embodiment, only different is to contain NaOH 28 grams per liters in the cooking liquor for the first time, over dry wheat straw material amount (T) is 1: 4.4 with the weight ratio of the total liquid measure of the cooking liquor first time, executing under the commentaries on classics in rotary spherical digester water flowing steam at rotary spherical digester, to make its pressure be 0.3MPa, exit to the ball internal pressure be 0.02, making rotary spherical digester pressure again is 0.3MPa, under the pressure of 0.3MPa, carry out the boiling first time, behind the digestion time 80 minutes, insulation is 10 minutes under the pressure of 0.3MPa.Contain NaOH 16 grams per liters in the cooking liquor for the second time, over dry wheat straw amount (T) is 1: 4.4 with the weight ratio of the total liquid measure of the cooking liquor second time, and the ball internal pressure rises to 0.5MPa.The little venting reduced to 0.3MPa to the ball internal pressure, makes the rotary spherical digester internal pressure be raised to 0.6MPa again, and boiling is 60 minutes under the pressure of 0.6MPa, static insulation 30 minutes.
Add anthraquinone when first and second time boiling respectively, its addition is 0.8 ‰ of an over dry wheat straw amount (T).
Embodiment 7
Washing fractional digestion technology and equipment thereof are substantially with embodiment 6 in the ball of present embodiment, only different is, contain NaOH 32 grams per liters in the cooking liquor for the first time, absolute wheat straw material amount (T) is 1: 4.9 with the weight ratio of the total liquid measure of boiling for the second time, under the rotary spherical digester rotation, in rotary spherical digester, feed water vapour, making its pressure is 0.4MPa, under the pressure of 0.4MPa, carry out the boiling first time after 80 minutes, insulation is 40 minutes under the pressure of 0.4MPa, contains NaOH 25 grams per liters in the cooking liquor for the second time, over dry wheat straw amount is 1: 4.8 with the total liquid measure ratio of the cooking liquor second time, and the ball internal pressure rises to 0.6MPa.After carrying out the boiling first time, feed steam in rotary spherical digester, making the pressure in the rotary spherical digester is 0.6MPa, exits to 0.4MPa, and making rotary spherical digester pressure again is 0.6MPa, and boiling is 70 minutes under the pressure of 0.7MPa, is incubated 20 minutes.
Add anthraquinone when second time boiling, the amount of its adding is 0.6 ‰ of an over dry wheat straw material amount.