CN112853796A - Preparation method for modifying papermaking pulp into pulp special for lyocell fibers - Google Patents
Preparation method for modifying papermaking pulp into pulp special for lyocell fibers Download PDFInfo
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- 229920000433 Lyocell Polymers 0.000 title claims abstract description 40
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 238000005406 washing Methods 0.000 claims abstract description 47
- 239000003513 alkali Substances 0.000 claims abstract description 31
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 27
- 238000006243 chemical reaction Methods 0.000 claims abstract description 26
- 230000007062 hydrolysis Effects 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 claims abstract description 20
- 230000020477 pH reduction Effects 0.000 claims abstract description 20
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 12
- 238000009874 alkali refining Methods 0.000 claims abstract description 11
- 238000007670 refining Methods 0.000 claims abstract description 8
- 238000010668 complexation reaction Methods 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims abstract description 7
- 239000012528 membrane Substances 0.000 claims abstract description 7
- 238000004537 pulping Methods 0.000 claims abstract description 5
- 239000002002 slurry Substances 0.000 claims description 29
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 230000018044 dehydration Effects 0.000 claims description 15
- 238000006297 dehydration reaction Methods 0.000 claims description 15
- 229920001131 Pulp (paper) Polymers 0.000 claims description 13
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 13
- 239000002738 chelating agent Substances 0.000 claims description 10
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical group Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 9
- 238000001035 drying Methods 0.000 claims description 9
- 229910001220 stainless steel Inorganic materials 0.000 claims description 9
- 239000010935 stainless steel Substances 0.000 claims description 9
- 239000012752 auxiliary agent Substances 0.000 claims description 7
- 230000004048 modification Effects 0.000 claims description 7
- 238000012986 modification Methods 0.000 claims description 7
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 6
- 239000000413 hydrolysate Substances 0.000 claims description 6
- 239000001301 oxygen Substances 0.000 claims description 6
- 229910052760 oxygen Inorganic materials 0.000 claims description 6
- 238000006722 reduction reaction Methods 0.000 claims description 6
- 241000276425 Xiphophorus maculatus Species 0.000 claims description 5
- 239000012295 chemical reaction liquid Substances 0.000 claims description 5
- 239000003814 drug Substances 0.000 claims description 5
- 238000000605 extraction Methods 0.000 claims description 5
- 238000001556 precipitation Methods 0.000 claims description 5
- 239000000047 product Substances 0.000 claims description 5
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 150000007522 mineralic acids Chemical class 0.000 claims description 4
- 238000005086 pumping Methods 0.000 claims description 4
- 239000008139 complexing agent Substances 0.000 claims description 3
- 230000003301 hydrolyzing effect Effects 0.000 claims description 3
- 238000004806 packaging method and process Methods 0.000 claims description 3
- 235000021395 porridge Nutrition 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 238000005728 strengthening Methods 0.000 claims description 3
- 238000010924 continuous production Methods 0.000 claims description 2
- 238000001125 extrusion Methods 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 238000010008 shearing Methods 0.000 claims description 2
- -1 steam Substances 0.000 claims description 2
- 238000003860 storage Methods 0.000 claims description 2
- 238000010411 cooking Methods 0.000 abstract description 8
- 239000002351 wastewater Substances 0.000 abstract description 4
- 229920002488 Hemicellulose Polymers 0.000 abstract description 3
- 239000000654 additive Substances 0.000 abstract description 2
- 229920005610 lignin Polymers 0.000 abstract description 2
- 239000002699 waste material Substances 0.000 abstract description 2
- 239000002023 wood Substances 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 7
- 239000000835 fiber Substances 0.000 description 7
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 description 6
- 238000012216 screening Methods 0.000 description 6
- 239000007844 bleaching agent Substances 0.000 description 5
- 239000002994 raw material Substances 0.000 description 5
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 4
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 4
- 239000004155 Chlorine dioxide Substances 0.000 description 3
- 229920000875 Dissolving pulp Polymers 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 3
- 229920000297 Rayon Polymers 0.000 description 3
- 238000004061 bleaching Methods 0.000 description 3
- 235000019398 chlorine dioxide Nutrition 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 238000010923 batch production Methods 0.000 description 2
- 230000000536 complexating effect Effects 0.000 description 2
- 238000007380 fibre production Methods 0.000 description 2
- 150000004676 glycans Chemical class 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910021645 metal ion Inorganic materials 0.000 description 2
- 229920001282 polysaccharide Polymers 0.000 description 2
- 239000005017 polysaccharide Substances 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229920002994 synthetic fiber Polymers 0.000 description 2
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 244000166124 Eucalyptus globulus Species 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229920000609 methyl cellulose Polymers 0.000 description 1
- 239000001923 methylcellulose Substances 0.000 description 1
- 235000010981 methylcellulose Nutrition 0.000 description 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 1
- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000004627 regenerated cellulose Substances 0.000 description 1
- 239000011122 softwood Substances 0.000 description 1
- 239000012209 synthetic fiber Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/001—Modification of pulp properties
- D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
- D21C9/004—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives inorganic compounds
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
- D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
- D21B1/30—Defibrating by other means
- D21B1/34—Kneading or mixing; Pulpers
- D21B1/345—Pulpers
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/001—Modification of pulp properties
- D21C9/007—Modification of pulp properties by mechanical or physical means
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/18—De-watering; Elimination of cooking or pulp-treating liquors from the pulp
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
- D21F11/02—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines of the Fourdrinier type
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
- D21H13/02—Synthetic cellulose fibres
Abstract
A preparation method for modifying papermaking pulp into pulp special for lyocell fibers belongs to the technical field of pulp pulping. Comprises the following steps: the method comprises the steps of hydraulic pulping and material preparation, squeezing, dewatering and concentrating, reaction tower hydrolysis, a first multi-section washing step, alkali tower refining, squeezing and dealkalization, a second multi-section washing step, reaction tower polymerization reduction, a third multi-section washing step, acidification and complexation treatment, a fourth multi-section washing step and paper making and forming. The invention has the advantages that: the alkaline cooking process is not needed, the cooking black liquor or red liquor with high COD content is not generated, the COD of the wastewater in the production process is less than or equal to 500, and the treatment is easy. The alkali liquor after alkali refining can be subjected to membrane treatment, the alkali liquor can be recycled, and the waste can be used for extracting additives such as hemicellulose, lignin and the like.
Description
Technical Field
The invention belongs to the technical field of pulp making, and relates to a preparation method for modifying papermaking pulp into pulp special for lyocell fibers.
Background
Lyocell fiber (Lyocell) is commonly called as "velveteen", is made from natural plant fiber as a raw material, is known in the middle of the 90 s of the 20 th century, and is known as the most valuable product in artificial fiber history in the last half century. The Lyocell fiber has various excellent performances of natural fiber and synthetic fiber, Lyocell is green fiber, raw materials of Lyocell are inexhaustible cellulose in nature, a production process has no chemical reaction, a used solvent is nontoxic, the recovery rate of the solvent can reach more than 99%, and the production process is green and environment-friendly, so the Lyocell fiber is called as '21 st century green fiber'.
The lyocell fiber industry has monopoly status, the production technology is basically monopolized in foreign companies, the productivity is small, in recent years, along with further digestion and absorption of the lyocell fiber production technology by domestic enterprises, the lyocell fiber production technology slowly becomes a relatively mature solvent method regenerated cellulose fiber industrialized production technology, the single-line production capacity of a new project in China is further improved, the lyocell industry in China is steadily developed, and the capacity of 100 million tons of productivity is expected to be reached in the coming years.
The raw material for producing the special pulp for the lyocell fiber is wood, and because the market demand is low, the production factory is mainly in the states of America, south Africa and the like at present, the productivity is low, and the total yield is low; no manufacturers for producing the pulp special for the lyocell fiber exist in China. The domestic wood pulp is mainly dissolving pulp for making paper pulp and common viscose fiber.
1. Present production technology for making paper pulp by wood
Peeling raw wood, slicing by a slicer, putting the wood chips into a boiler, reacting with caustic soda or sulfate cooking liquor at a certain temperature and under a certain pressure to prepare coarse pulp, washing and screening the coarse pulp for multiple times, then putting the coarse pulp into a bleaching section, reacting with alkaline and neutral bleaching agents (the bleaching agents comprise alkaline hydrogen peroxide, hypochlorite, chlorine dioxide, oxygen, ozone and the like) for multiple times to prepare bleached pulp, washing and screening for multiple times, removing impurities, papermaking, forming, drying, slitting to prepare platy wood pulp, and packaging with a certain specification and weight, wherein the commercial pulp is called paper pulp.
2. Production technology of dissolving pulp for viscose fiber at present
Peeling raw wood, slicing by a slicer, allowing the wood chips to enter a No. 1 digester, performing high-temperature prehydrolysis, extracting polysaccharide, allowing the raw wood to enter a No. 2 digester again, reacting with caustic soda and sulfate cooking liquor at a certain temperature and under a certain pressure to obtain coarse pulp, washing and screening the coarse pulp for multiple times, allowing the coarse pulp to enter a bleaching section, allowing the coarse pulp to react with alkaline and neutral bleaching agents (such as alkaline hydrogen peroxide, hypochlorite, chlorine dioxide, oxygen, ozone and the like) for multiple times to obtain bleached pulp, washing and screening for multiple times, removing impurities, papermaking, forming, drying, and cutting to obtain the platy dissolved pulp.
3. Production technology of current foreign lyocell fiber special pulp
Peeling raw wood, slicing by a slicer, putting the wood chips into a digester, reacting with sulfite cooking liquor at a certain temperature and under a certain pressure to prepare coarse pulp, washing and screening the coarse pulp for multiple times, then putting the coarse pulp into a bleaching section, reacting with alkaline and neutral bleaching agents (the bleaching agents comprise alkaline hydrogen peroxide, chlorine dioxide, oxygen, ozone and the like) for multiple times, performing acid treatment or complexing treatment to prepare bleached pulp, washing and screening for multiple times, removing impurities, papermaking, forming, drying and slitting to prepare platy wood pulp which is special pulp for lyocell fibers.
The pulping method produces a large amount of malodorous gas and polluted wastewater in the production process, particularly in the high-temperature cooking stage, and has high chroma and heavy pollution.
The papermaking wood pulp can not be used for the production of lyocell fibers due to the low content of methyl cellulose, higher viscosity, high polymerization degree, and high content of hemicellulose, various ash contents and metal ions. The dissolving pulp for viscose fiber cannot be directly used for the production of lyocell fiber because of high metal ions and high polysaccharide content.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a preparation method for modifying papermaking pulp into special pulp for lyocell fibers.
A preparation method for modifying papermaking pulp into pulp special for lyocell fibers comprises the following steps: the method comprises the steps of hydraulic pulping and material preparation, squeezing, dewatering and concentrating, reaction tower hydrolysis, a first multi-section washing step, alkali tower refining, squeezing and dealkalization, a second multi-section washing step, reaction tower polymerization reduction, a third multi-section washing step, acidification and complexation treatment, a fourth multi-section washing step and paper making and forming.
The invention has the advantages that:
(1) provides a new method for producing the pulp special for the lyocell fiber;
(2) in the production process, an alkaline cooking process is not adopted, the cooking black liquor or red liquor with high COD content is not generated, the COD of the wastewater in the production process is less than or equal to 500, and the wastewater is easy to treat.
(3) The alkali liquor after alkali refining can be subjected to membrane treatment, the alkali liquor can be recycled, and the waste can be used for extracting additives such as hemicellulose, lignin and the like.
(4) The quality indexes of the pulp special for the lyocell fiber are as follows:
polymerization degree: 450-600, alpha cellulose is more than or equal to 90%, R10 is more than or equal to 90%, R18 is more than or equal to 93%, ash content is less than or equal to 0.1%, Fe is less than or equal to 2.0ppm, Ca is less than or equal to 50ppm, Mg is less than or equal to 50ppm, and whiteness is more than or equal to 92%.
Detailed Description
It will be apparent that those skilled in the art can make many modifications and variations based on the spirit of the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element, component or section is referred to as being "connected" to another element, component or section, it can be directly connected to the other element or section or intervening elements or sections may also be present. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art.
The following examples are further illustrative in order to facilitate the understanding of the embodiments, and the present invention is not limited to the examples.
Example 1:
a preparation method for modifying papermaking pulp into pulp special for lyocell fibers widens the production method of the pulp special for the lyocell fibers, reduces the investment scale of equipment and reduces the pollution load in the production of wood pulp.
A preparation method for modifying papermaking pulp into pulp special for lyocell fibers comprises the following steps:
hydraulic pulp crushing and material preparation: a platy paper-making-grade wood pulp bag (800x600x850, 220Kg) is placed on a chain plate conveyor by a bag clamping vehicle, package iron wires (steel belts) are removed by manual shearing and extraction, then the chain plate conveyor is conveyed into a hydraulic pulper (a certain amount of water is added in advance), and a pulp plate collides with a blade and is thrown to the edge of a groove body to form a horizontal vortex by the centrifugal force generated by the strong rotation of a rotor of the hydraulic pulper. And the pulp rises along the edge and falls back to the turntable, then a negative pressure area is formed in the center of the groove body, and the circulation forms a vertical vortex, so that the pulp and the like are contacted with the blade back and forth and are continuously disintegrated, and the pulp is broken into pulp porridge with the concentration of about 5 percent so as to be convenient for pumping.
Squeezing, dewatering and concentrating: the slurry gruel with the concentration of about 5 percent is pumped to a mesh belt type dehydrator or a roller type pulp extruder by a low-concentration slurry pump, is strongly dehydrated to the dryness of about 30 percent by mechanical squeezing, and is sent to a hydrolysis reaction tower.
A hydrolysis step of a reaction tower: the reaction tower is a vertical stainless steel tower, a spiral stirrer is arranged at the lower part of the reaction tower, slurry is fed in and discharged out from the upper part, the hydrolysis tower is used for batch production, namely, the feeding is stopped after the slurry is fully fed in, the hydrolysis is carried out, and the discharged material is discharged and emptied into the next cycle after the hydrolysis is finished. During hydrolysis reaction, hydrolysate is pumped from the middle part and the bottom part of the hydrolysis tower and pumped from the upper part of the hydrolysis tower to realize strong circulation; the hydrolysate can be desalted water, or hydrochloric acid and inorganic sulfuric acid. Hydrolyzing with desalted water at 150-175 ℃ for 30-180 min;
a multi-stage washing step: the hydrolyzed pulp is pumped into a mesh belt type high-speed pulp washer or a roller type pulp extruder to realize mechanical dehydration, water addition replacement and multiple cycles, so that a pulp washing mode of combining powerful dehydration and replacement is realized, the extraction rate is high, and the washing factor is high;
alkali tower refining: the alkali tower is a vertical stainless steel tower, a spiral stirrer is arranged at the lower part of the alkali tower, slurry enters from the top and exits from the bottom, and the alkali tower is produced continuously, keeps a certain liquid level and enters while exiting. Caustic soda solution for alkali refining, wherein the alkali content is 60-120 mg/L; temperature: 30 to 70 ℃. Alkali refining time: 30-120 min; concentrating the pulp: 8 to 12 percent; oxygen can be added for strengthening in the alkali refining process.
And (3) squeezing and dealkalizing: the hydrolyzed slurry is pumped into a double-mesh belt type or double-roll type squeezer, alkali liquor is extracted through mechanical extrusion, and the extracted alkali liquor can be recycled after being treated by a membrane removal treatment system.
A multi-stage washing step: similar to the multi-section washing after hydrolysis, the dealkalized pulp is diluted by adding water to be pulp congee with the concentration of about 5 percent, and is sent into a mesh belt type high-speed pulp washer or a roller type pulp extruder by a pump to realize mechanical dehydration, water addition replacement and multiple cycles, thereby realizing the pulp washing mode of combining strong dehydration and replacement, and having high extraction rate and high washing factor;
a step of descending polymerization of a reaction tower: the reaction tower is a vertical stainless steel tower, a spiral stirrer is arranged at the lower part of the reaction tower, slurry enters from the lower part and flows out from the upper part, continuous production is carried out, and the reaction liquid medicine is hypochlorite or hydrogen peroxide. Before the pump is sent into the reaction tower, a mixer is arranged in front of the pump, and reaction liquid medicine, steam, alkali liquor and the like are added. During the polymerization reduction reaction, the slurry is concentrated: 8% -12%, PH: 9-14, wherein the dosage of the hydrogen peroxide is 0.5% -5%; the temperature is 40-100 ℃, and the time is 30-180 min; a small amount of chelating agent aid may be added during the precipitation stage.
A multi-stage washing step: adding water into the slurry after the precipitation to dilute the slurry to about 5 percent of concentration, pumping the slurry into a mesh belt type high-speed pulp washer or a roller type pulp extruder by a pump to realize mechanical dehydration, water addition replacement and multiple circulation, and realizing a pulp washing mode of combining strong dehydration and replacement.
Acidifying and complexing treatment: the slurry acidification is carried out in an acidification tank or tower, and inorganic acid sulfuric acid or hydrochloric acid is used for acidification. Upon acidification, PH: 1-2, the temperature is 30-50 ℃, the time is 30-60 min, and a chelating agent or a complexing agent auxiliary agent is added after acidification.
A multi-stage washing step: the acidified pulp is pumped into a mesh belt type high-speed pulp washer or a roller type pulp extruder to realize mechanical dehydration, water addition replacement and multiple cycles, and a pulp washing mode of combining powerful dehydration and replacement is realized.
A papermaking forming step: the washed semi-finished pulp passes through a long net or a wet part of a clamping net, is distributed and formed in a low-concentration state, is dehydrated through a net part in a vacuum area, is mechanically pressed and dehydrated in a large roller area to form a pulp board with 50% dryness, is dried into a formed pulp board with 90% dryness through a plurality of drying cylinders or an air cushion type dryer, is cut into plate-shaped pulp with 800x600 specification through a paper cutter, and is packed and bundled into a finished product to be packaged and put in storage.
And (5) drying the finished product.
Example 2:
a preparation method for modifying papermaking pulp into pulp special for lyocell fibers comprises the following steps:
step 1), preparing materials: removing packaging iron wires (steel belts) of the paper-making wood pulp bag, and crushing the paper-making wood pulp bag into paste with the concentration of about 5% by a hydraulic pulper;
step 2), squeezing, dewatering and conveying: the pulp gruel with the concentration of about 5 percent is pressed mechanically and dehydrated to the dryness of about 30 percent, and then is sent into a hydrolysis reaction tower.
Step 3), hydrolysis of a reaction tower: the reaction tower is a vertical stainless steel tower, the upper part is fed in and the lower part is discharged out, the batch production is carried out, and the hydrolysate can be circulated strongly; the hydrolysate can be desalted water, or hydrochloric acid and inorganic sulfuric acid. Hydrolyzing with desalted water at 150-175 ℃ for 30-180 min;
step 4), washing with multi-section washing equipment, strongly dewatering and replacing are combined with each other, the extraction rate is high, and the washing factor is high;
step 5), refining in an alkali tower: the alkali tower is a vertical stainless steel tower, caustic soda is used for alkali refining, and the alkali content is 60-120 mg/L; temperature: 30 to 70 ℃. Alkali refining time: 30-120 min; concentrating the pulp: 8 to 12 percent; oxygen can be added for strengthening in the alkali refining process.
Step 6), squeezing and dealkalizing: the squeezed alkali liquor can be recycled after being treated by a membrane removing treatment system.
Step 7), reducing polymerization and adjusting viscosity: the reaction tower is a vertical stainless steel tower, and the reaction liquid medicine is hypochlorite or hydrogen peroxide.
Concentrating the pulp: 8% -12%, PH: 9-14, wherein the dosage of the hydrogen peroxide is 0.5% -5%; the temperature is 40-100 ℃, and the time is 30-180 min; a small amount of chelating agent aid may be added during the precipitation stage.
Step 8), acidification and complexation treatment: inorganic acid sulfuric acid or hydrochloric acid is used for acidification. Upon acidification, PH: 1-2, the temperature is 30-50 ℃, the time is 30-60 min, and a chelating agent or a complexing agent auxiliary agent is added after acidification.
And step 9), after the pulp is washed by multiple sections again, manufacturing and slitting forming are carried out by a long-mesh multi-cylinder paper machine or a mesh-sandwiched air cushion pulp machine. The finished pulp is 800x600 specification or roll pulp.
Example 3:
the preparation method for modifying papermaking pulp into the pulp special for the lyocell fibers as described in the embodiment 1 and the embodiment 2 comprises the following parameters and process conditions:
1. raw materials: sulfate bleached softwood pulp, wherein DP: 950, alpha cellulose: 86 percent, 89 percent of whiteness, 0.3 percent of ash and 25ppm of Fe.
2. The hydraulic pulper is pulped by desalted water, and the concentration is 4.5 percent.
3. And (4) squeezing and dewatering by a single-screw squeezer, wherein the dryness is 32%.
4. Hydrolysis in a hydrolysis tower: introducing saturated steam, and heating to 160 deg.C for 90 min.
5. Extruding, dehydrating and washing by a double-screw pulp extruder, feeding into a refining tower, concentrating pulp: 10%, temperature 35 ℃, alkali content 80mg/L, time 60 min.
6. Dealkalizing the extruder of the double-net pulp press, pressing the extruder to 25 percent of dryness, removing a membrane by using an alkali liquor system, adjusting the concentration of the slurry and feeding the slurry into a reaction tower.
7. Polymerization reduction reaction tower: the pulp concentration is 10%, the hydrogen peroxide dosage is 1%, the temperature is 55 ℃, the time is 60min, and the chelating agent auxiliary agent EDTA dosage is 0.1%.
8. And extruding, dehydrating and washing by a double-screw extruder.
9. Acidification and complexation treatment: concentrating the pulp: 4.5%, hydrochloric acid for acidification, PH: 1-2 ℃, the temperature is 40 ℃, the dosage of the chelating agent auxiliary agent EDTA is 0.1%, and the time is 60 min.
10. And extruding, dehydrating and washing by a double-screw extruder.
11. Low concentration flow, concentration 2%, mesh forming, air cushion drying, and rolling into pulp.
Example 4: the preparation method for modifying papermaking pulp into the pulp special for the lyocell fibers as described in the embodiment 1 and the embodiment 2 comprises the following parameters and process conditions:
1. raw materials: sulfate bleached eucalyptus pulp, wherein DP: 850, alpha cellulose: 91.5 percent, whiteness of 91 percent, ash content of 0.3 percent and Fe content of 25 ppm.
2. The hydraulic pulper is pulped by desalted water, and the concentration is 4.5 percent.
3. And (4) squeezing and dewatering by a single-screw squeezer, wherein the dryness is 32%.
4. Hydrolysis in a hydrolysis tower: introducing saturated steam, and heating to 160 deg.C for 90 min.
5. Extruding, dehydrating and washing by a double-screw pulp extruder, feeding into a refining tower, concentrating pulp: 10 percent, the temperature is 35 ℃, the alkali content is 85mg/L, and the time is 60 min.
6. Dealkalizing the extruder of the double-net pulp press, pressing the extruder to 25 percent of dryness, removing a membrane by using an alkali liquor system, adjusting the concentration of the slurry and feeding the slurry into a reaction tower.
7. Polymerization reduction reaction tower: the pulp concentration is 10%, the hydrogen peroxide dosage is 1%, the temperature is 55 ℃, the time is 50min, and the chelating agent auxiliary agent EDTA dosage is 0.1%.
8. And extruding, dehydrating and washing by a double-screw extruder.
9. Acidification and complexation treatment: concentrating the pulp: 4.5%, hydrochloric acid for acidification, PH: 1-2 ℃, the temperature is 40 ℃, the dosage of the chelating agent auxiliary agent EDTA is 0.1%, and the time is 60 min.
10. And extruding, dehydrating and washing by a double-screw extruder.
11. Low concentration flow, concentration 2%, mesh forming, air cushion drying, and rolling into pulp.
As described above, although the embodiments of the present invention have been described in detail, it will be apparent to those skilled in the art that many modifications are possible without substantially departing from the spirit and scope of the present invention. Therefore, such modifications are also all included in the scope of protection of the present invention.
Claims (10)
1. A preparation method for modifying papermaking pulp into pulp special for lyocell fibers is characterized by comprising the following steps: the method comprises the steps of hydraulic pulping and material preparation, squeezing, dewatering and concentrating, reaction tower hydrolysis, a first multi-section washing step, alkali tower refining, squeezing and dealkalization, a second multi-section washing step, reaction tower polymerization reduction, a third multi-section washing step, acidification and complexation treatment, a fourth multi-section washing step and paper making and forming.
2. The method for preparing the pulp special for the modification of the papermaking pulp into the lyocell fiber according to claim 1, wherein the hydraulic pulp crushing preparation step comprises: putting a platy paper-making wood pulp bag on a chain plate conveyor by using a bag clamping vehicle, manually shearing, extracting and removing packaging iron wires, conveying the wood pulp bag into a hydraulic pulper by using the chain plate conveyor, adding a certain amount of water in advance, and enabling the pulp plate to collide with a blade by using a centrifugal force generated by strong rotation of a rotor of the hydraulic pulper and be thrown to the edge of a groove body to form a horizontal vortex; and the pulp rises along the edge and falls back to the turntable, then a negative pressure area is formed in the center of the groove body, and the circulation forms a vertical vortex, so that the pulp and the like are contacted with the blade back and forth and are continuously disintegrated, and the pulp is broken into pulp porridge with the concentration of about 5 percent so as to be convenient for pumping.
3. The method for preparing the pulp special for the modification of the papermaking pulp into the lyocell fiber according to claim 1, wherein the step of press dewatering and concentration comprises the following steps: the slurry porridge with the concentration of about 5 percent is pumped to a mesh belt type dehydrator or a roller type pulp extruder by a low-concentration slurry pump, is strongly dehydrated to the dryness of about 30 percent by mechanical squeezing and is sent to a hydrolysis reaction tower;
a hydrolysis step of a reaction tower: the reaction tower is a vertical stainless steel tower, a spiral stirrer is arranged at the lower part of the reaction tower, slurry is fed in and discharged out from the upper part, the hydrolysis tower is used for intermittent production, namely, the feeding is stopped after the slurry is fully fed in, the hydrolysis is carried out, and the discharged material is discharged and emptied to enter the next cycle after the hydrolysis is finished; during hydrolysis reaction, hydrolysate is pumped from the middle part and the bottom part of the hydrolysis tower and pumped from the upper part of the hydrolysis tower to realize strong circulation; the hydrolysate can be desalted water, or hydrochloric acid and inorganic acid of sulfuric acid; and hydrolyzing with desalted water at 150-175 ℃ for 30-180 min.
4. The method for preparing the pulp special for the modified lyocell fiber of the papermaking pulp according to claim 1, wherein the first multi-stage washing step comprises: the hydrolyzed pulp is pumped into a mesh belt type high-speed pulp washer or a roller type pulp extruder to realize mechanical dehydration, water addition replacement and multiple cycles.
5. The method for preparing the pulp special for the modification of the papermaking pulp into the lyocell fiber according to claim 1, wherein the alkali tower refining step comprises: the alkali tower is a vertical stainless steel tower, a spiral stirrer is arranged at the lower part of the alkali tower, slurry enters from the top and exits from the bottom, the alkali tower is produced continuously, a certain liquid level is reserved, and the slurry enters and exits simultaneously; caustic soda solution for alkali refining, wherein the alkali content is 60-120 mg/L; temperature: 30-70 ℃; alkali refining time: 30-120 min; concentrating the pulp: 8 to 12 percent; oxygen can be added for strengthening in the alkali refining process.
6. The method for preparing the pulp special for the modification of the papermaking pulp into the lyocell fiber according to claim 1, wherein the pressing and dealkalizing steps are as follows: the hydrolyzed slurry is pumped into a double-mesh belt type or double-roll type squeezer, alkali liquor is extracted through mechanical extrusion, and the extracted alkali liquor can be recycled after being treated by a membrane removal treatment system.
7. The method for preparing the pulp special for the modified lyocell fiber of the papermaking pulp according to claim 1, wherein the second multi-stage washing step comprises: similar to the multi-stage washing after hydrolysis, the dealkalized pulp is diluted by adding water to be pulp congee with the concentration of about 5 percent and is sent into a mesh belt type high-speed pulp washer or a roller type pulp extruder by a pump to realize mechanical dehydration, water addition replacement and multiple cycles, thereby realizing the pulp washing mode of combining strong dehydration and replacement, and having high extraction rate and high washing factor.
8. The method for preparing the pulp special for the modified lyocell fiber of the papermaking pulp according to claim 1, wherein the step of reducing polymerization in the reaction tower comprises: the reaction tower is a vertical stainless steel tower, a spiral stirrer is arranged at the lower part of the reaction tower, slurry enters from the lower part and flows out from the upper part, continuous production is carried out, and the reaction liquid medicine is hypochlorite or hydrogen peroxide; before the pump is sent into the reaction tower, a mixer is arranged in front of the pump, and reaction liquid medicine, steam, alkali liquor and the like are added; during the polymerization reduction reaction, the slurry is concentrated: 8% -12%, PH: 9-14, wherein the dosage of the hydrogen peroxide is 0.5% -5%; the temperature is 40-100 ℃, and the time is 30-180 min; a small amount of chelating agent aid may be added during the precipitation stage.
9. The method for preparing the pulp special for the modified lyocell fiber of the papermaking pulp according to claim 1, wherein the third multi-stage washing step comprises: adding water into the slurry after the precipitation to dilute the slurry to about 5 percent of concentration, pumping the slurry into a mesh belt type high-speed pulp washer or a roller type pulp extruder by a pump to realize mechanical dehydration, water addition replacement and multiple circulation, and realizing a pulp washing mode of combining strong dehydration and replacement.
10. The method for preparing the pulp special for the modified lyocell fiber of the papermaking pulp according to claim 1, wherein the acidification and complexation treatment steps are as follows: acidifying the slurry in an acidification tank or tower with inorganic acid sulfuric acid or hydrochloric acid; upon acidification, PH: 1-2, the temperature is 30-50 ℃, the time is 30-60 min, and a chelating agent or a complexing agent auxiliary agent is added after acidification;
a fourth multi-stage washing step: sending the acidified pulp into a mesh belt type high-speed pulp washer or a roller type pulp extruder through a pump to realize mechanical dehydration, water addition replacement and multiple cycles, and realizing a pulp washing mode of combining strong dehydration and replacement;
a papermaking forming step: the washed semi-finished pulp passes through a long net or a wet part of a clamping net, is distributed and formed in a low-concentration state, is dehydrated through a net part in a vacuum area, is mechanically pressed and dehydrated in a large roller area to form a pulp board with 50% dryness, is dried into a formed pulp board with 90% dryness through a plurality of drying cylinders or an air cushion type dryer, is cut into plate-shaped pulp with 800x600 specification through a paper cutter, and is packed and bundled into a finished product to be packaged and put in storage; and (5) drying the finished product.
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Cited By (2)
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