CN117683947A - Process for preparing xylose from black liquor of paper mill - Google Patents
Process for preparing xylose from black liquor of paper mill Download PDFInfo
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- CN117683947A CN117683947A CN202311791122.2A CN202311791122A CN117683947A CN 117683947 A CN117683947 A CN 117683947A CN 202311791122 A CN202311791122 A CN 202311791122A CN 117683947 A CN117683947 A CN 117683947A
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- nanofiltration
- black liquor
- xylose
- paper mill
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- SRBFZHDQGSBBOR-IOVATXLUSA-N D-xylopyranose Chemical compound O[C@@H]1COC(O)[C@H](O)[C@H]1O SRBFZHDQGSBBOR-IOVATXLUSA-N 0.000 title claims abstract description 102
- PYMYPHUHKUWMLA-UHFFFAOYSA-N arabinose Natural products OCC(O)C(O)C(O)C=O PYMYPHUHKUWMLA-UHFFFAOYSA-N 0.000 title claims abstract description 51
- SRBFZHDQGSBBOR-UHFFFAOYSA-N beta-D-Pyranose-Lyxose Natural products OC1COC(O)C(O)C1O SRBFZHDQGSBBOR-UHFFFAOYSA-N 0.000 title claims abstract description 51
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 17
- 238000001728 nano-filtration Methods 0.000 claims abstract description 200
- 239000012528 membrane Substances 0.000 claims abstract description 112
- 239000003513 alkali Substances 0.000 claims abstract description 47
- 238000000034 method Methods 0.000 claims abstract description 43
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 39
- 230000008569 process Effects 0.000 claims abstract description 38
- 229920002488 Hemicellulose Polymers 0.000 claims abstract description 37
- 230000007062 hydrolysis Effects 0.000 claims abstract description 37
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 33
- 238000003860 storage Methods 0.000 claims abstract description 31
- 238000001914 filtration Methods 0.000 claims abstract description 28
- 238000000909 electrodialysis Methods 0.000 claims abstract description 23
- 238000001704 evaporation Methods 0.000 claims abstract description 20
- 230000008020 evaporation Effects 0.000 claims abstract description 20
- 238000007865 diluting Methods 0.000 claims abstract description 8
- 239000000413 hydrolysate Substances 0.000 claims abstract description 7
- 230000003301 hydrolyzing effect Effects 0.000 claims abstract description 7
- 239000002253 acid Substances 0.000 claims abstract description 5
- 239000000049 pigment Substances 0.000 claims abstract description 5
- 239000000084 colloidal system Substances 0.000 claims abstract description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 60
- 239000000243 solution Substances 0.000 claims description 38
- 238000010790 dilution Methods 0.000 claims description 26
- 239000012895 dilution Substances 0.000 claims description 26
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 239000003085 diluting agent Substances 0.000 claims description 10
- 229920005610 lignin Polymers 0.000 claims description 10
- 239000012141 concentrate Substances 0.000 claims description 7
- 238000002360 preparation method Methods 0.000 claims description 4
- 239000000706 filtrate Substances 0.000 claims description 3
- 230000001502 supplementing effect Effects 0.000 claims description 3
- 230000001276 controlling effect Effects 0.000 claims 3
- 230000001105 regulatory effect Effects 0.000 claims 1
- 238000010792 warming Methods 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 abstract description 6
- 238000004064 recycling Methods 0.000 abstract description 6
- 230000007613 environmental effect Effects 0.000 abstract description 5
- 230000009471 action Effects 0.000 abstract description 4
- 108010009736 Protein Hydrolysates Proteins 0.000 abstract description 3
- 238000011084 recovery Methods 0.000 abstract description 3
- 238000007670 refining Methods 0.000 abstract description 3
- 150000002500 ions Chemical class 0.000 description 17
- 239000000126 substance Substances 0.000 description 6
- 239000002028 Biomass Substances 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000000926 separation method Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 239000011550 stock solution Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 239000001913 cellulose Substances 0.000 description 2
- 230000014509 gene expression Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000010893 paper waste Substances 0.000 description 2
- 239000002957 persistent organic pollutant Substances 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 description 2
- 235000011152 sodium sulphate Nutrition 0.000 description 2
- 239000010902 straw Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 241000609240 Ambelania acida Species 0.000 description 1
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 235000014676 Phragmites communis Nutrition 0.000 description 1
- 244000082204 Phyllostachys viridis Species 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- 241000209140 Triticum Species 0.000 description 1
- 235000021307 Triticum Nutrition 0.000 description 1
- 240000008042 Zea mays Species 0.000 description 1
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 description 1
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000002154 agricultural waste Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000010905 bagasse Substances 0.000 description 1
- 239000011425 bamboo Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000012459 cleaning agent Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 235000005822 corn Nutrition 0.000 description 1
- HEBKCHPVOIAQTA-NGQZWQHPSA-N d-xylitol Chemical compound OC[C@H](O)C(O)[C@H](O)CO HEBKCHPVOIAQTA-NGQZWQHPSA-N 0.000 description 1
- 238000004042 decolorization Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000002440 industrial waste Substances 0.000 description 1
- 229910017053 inorganic salt Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000036284 oxygen consumption Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 231100000614 poison Toxicity 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000004458 spent grain Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000006277 sulfonation reaction Methods 0.000 description 1
- 239000003440 toxic substance Substances 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Abstract
The invention discloses a process for preparing xylose by using black liquor from a paper mill, and belongs to the technical field of xylose production. Diluting the black liquor of the paper mill with process water, and then introducing the diluted black liquor into a nanofiltration membrane device; under the action of nanofiltration membrane, performing nanofiltration dealkalization to obtain nanofiltration alkali liquor and nanofiltration concentrated solution, wherein the nanofiltration alkali liquor can be recycled or concentrated for takeaway after being stored in a temporary storage tank; hydrolyzing the nanofiltration concentrated solution under a certain condition, and filtering after the hydrolysis is completed to obtain filter residues and hydrolysate; filtering the hydrolysate, removing acid by electrodialysis device, removing pigment and colloid by membrane separator, removing ion by ion exchanger, concentrating by evaporation concentration device, and refining to obtain xylose. The invention ensures that most of alkali is recovered in the whole process, and the conversion from hemicellulose to xylose is carried out, thereby realizing the effective recovery of alkali and hemicellulose in black liquor, recycling, green production and contributing to environmental protection.
Description
Technical Field
The invention relates to a process for preparing xylose by using black liquor of a paper mill, in particular to a process for preparing xylose by using black liquor of a paper mill as a raw material, adopting nanofiltration to dealkalize and then hydrolyzing hemicellulose.
Background
In the paper industry, the wastewater produced by the alkaline pulping process contains a large amount of lignin and is black brown, and is called "black liquor". The black liquor contains a large amount of suspended solids, organic pollutants and toxic substances, and if the black liquor is directly discharged into a water body, serious pollution can be caused. The main hazards include:
1. papermaking wastewater containing a large amount of hemicellulose, pigment and inorganic salt can darken water and has special foul smell;
2. the biochemical oxygen consumption of the papermaking black liquor containing high-concentration organic pollutants is up to 5000-40000g/L, so that the dissolved oxygen in the water body can be greatly consumed, and the water quality is affected;
3. the existence of a large amount of alkaline substances in the black liquor can lead the pH value of the water body to be increased sharply, and the balance of the water body environment is destroyed.
The black liquor from the paper mill contains about 25% lignin and about 20% hemicellulose, as well as xylose, potassium, nitrogen, phosphorus, etc. At present, black liquor of paper mill is treated mainly by means of boiler combustion, but the treatment cost is high, and secondary pollution is generated; meanwhile, lignin, hemicellulose and the like in the biomass are not effectively recycled, namely the economic value of the biomass is not fully utilized.
Although, in the prior art CN105625075a, a method of separating lignocellulose biomass by combining hydrothermal and sulfonation pretreatment is disclosed, wherein the lignocellulose biomass is derived from agricultural waste (such as corn stalk, wheat straw, rice straw, reed, bagasse, etc.), forestry waste (such as wood chips, saw dust, bark, etc.), bamboo, energy plants, industrial waste (such as fiber residue of pulp and paper mill, spent grain after wine brewing, etc.), municipal waste (such as waste paper, waste paper box, etc.), or a combination thereof. Wherein, the substrate cellulose is mainly used for preparing xylo-oligosaccharide, and the related sulfonated black liquor is concentrated and modified to prepare the lignin-based organic compound fertilizer for returning to the field. However, the method directly uses biomass raw materials, has relatively simple components, and has higher temperature required for preparing xylose and longer reaction time, thus leading to more carbide. In addition, in the prior art CN1272259C, a pollution-free emission treatment process of papermaking black liquor is disclosed, but the precipitation separation of cellulose, hemicellulose and xylose is realized mainly by using chemical reagents, the introduction of new substances is involved, and meanwhile, the effective conversion rate of hemicellulose is lower.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a process for preparing xylose by using black liquor of a paper mill. In the technical scheme, paper mill black liquor is used as a raw material, and hemicellulose and alkali liquor are effectively separated and recycled through a physical method (nanofiltration membrane); then, sulfuric acid is used as a catalyst, and is rapidly hydrolyzed (time is less than 3 hours) under the conditions of low acid (less than 2 percent) and low temperature (less than 110 ℃), so that high conversion rate of hemicellulose (more than 99 percent of hemicellulose can be hydrolyzed into sugar substances, mainly xylose) and low loss of xylose are ensured;
the invention ensures that most of alkali is recovered in the whole process, and the conversion from hemicellulose to xylose is carried out, thereby realizing the effective recovery of alkali and hemicellulose in black liquor, recycling, green production and contributing to environmental protection.
In order to achieve the technical purpose, the following technical scheme is provided:
the first object of the present technical solution is to provide: a process for preparing xylose from black liquor in a paper mill, comprising the steps of:
1) Dilution: the mass ratio of the black liquor to the process water in the paper mill is 1:1-3, diluting the black liquor to obtain black liquor diluent;
wherein the black liquor of the paper mill comprises 30-35g/L hemicellulose, 20-24g/L sodium hydroxide and 50-60g/L lignin;
2) Nanofiltration dealkalization: introducing the black liquor diluent into a nanofiltration membrane device, and controlling to obtain nanofiltration alkaline liquor with refraction of 0.5-0.6 and nanofiltration concentrated liquor with refraction of 20-24 (comprising hemicellulose concentration > 30g/L and sodium hydroxide concentration < 3 g/L) under the action of the nanofiltration membrane device; wherein, after the nanofiltration alkali liquor is stored in the temporary storage tank, the nanofiltration alkali liquor can be recycled or concentrated for takeaway;
3) Hydrolysis: adding acid into the nanofiltration concentrated solution, hydrolyzing, filtering to remove unhydrolyzed lignin, and controlling to obtain filter residue and hydrolysate (comprising xylose concentration > 25g/L, sodium sulfate concentration 4-5g/L and sulfuric acid concentration 20-21 g/L) with refraction of 6.8-7.4 and electric conductance of 32-36 ms/cm;
4) Post-treatment: and (3) carrying out electrodialysis device deacidification, membrane separator pigment and colloid removal, ion exchanger ion removal and evaporation concentration device concentration on the hydrolysate, and further refining to obtain xylose.
Preferably, the nanofiltration dealkalization comprises at least two stages of nanofiltration dealkalization.
Preferably, the nanofiltration dealkalization comprises primary nanofiltration dealkalization and secondary nanofiltration dealkalization, and the black liquor diluent is subjected to primary nanofiltration dealkalization to obtain primary nanofiltration alkali liquor and primary nanofiltration concentrated liquor; performing secondary nanofiltration dealkalization on the primary nanofiltration concentrated solution to obtain secondary nanofiltration alkali liquor and secondary nanofiltration concentrated solution;
wherein in the nanofiltration membrane device I, the feeding flow of the black liquor diluent is 35-40m 3 And/h, the discharge flow of the primary nanofiltration alkali liquor is 25-30m 3 And/h, the discharge flow of the first-level nanofiltration concentrated solution is 10-15m 3 /h; the pressure is 30-35bar, and the operating temperature is 35-40 ℃.
In the nanofiltration membrane device II, the feed flow rate of the first-stage nanofiltration concentrated solution is 25-30m 3 And/h, the water supplementing flow of the process water is 15-20m 3 /h; the discharge flow of the secondary nanofiltration alkali liquor is 15-20m 3 /h, second orderThe discharge flow of the nanofiltration concentrated solution is 10-15m 3 /h; the pressure is 30-35bar, and the operating temperature is 35-40 ℃.
And the first-level nanofiltration concentrated solution comprises hemicellulose with the concentration of 30-35g/L and sodium hydroxide with the concentration of 6.0-8.0 g/L; the primary nanofiltration alkaline liquor comprises hemicellulose with the concentration of 0.5-1.0g/L and sodium hydroxide with the concentration of 6.0-8.0 g/L.
The secondary nanofiltration concentrated solution comprises hemicellulose with the concentration of 30-35g/L and sodium hydroxide with the concentration of 2-3 g/L; the secondary nanofiltration alkaline liquor comprises hemicellulose with the concentration of 0.5-1g/L and sodium hydroxide with the concentration of 2-3 g/L.
The second object of the present technical solution is to provide: a system for preparing xylose from black liquor in paper mill comprises a black liquor dilution tank, a nanofiltration membrane device, a hydrolysis device, a filtering device, an electrodialysis device, a membrane separator and an ion exchanger;
a paper mill black liquor storage tank is arranged at the front side of the station of the black liquor dilution tank, a discharge hole of the paper mill black liquor storage tank is connected with a black liquor dilution tank feed inlet, and the black liquor dilution tank is connected with a process water feed pipe;
the nanofiltration membrane device is arranged at the rear side of a station of the black liquor dilution tank, and a discharge hole of the black liquor dilution tank is connected with a feed hole of the nanofiltration membrane device;
the hydrolysis device is arranged at the rear side of a station of the nanofiltration membrane device, and a nanofiltration concentrated solution outlet on the nanofiltration membrane device is connected with a feed inlet of the hydrolysis device;
the filtering device is arranged at the rear side of the station of the hydrolysis device, and the discharge hole of the hydrolysis device is connected with the filtering device;
the electrodialysis device is arranged at the rear side of a station of the filtering device, and a filtrate outlet on the filtering device is connected with the electrodialysis device;
the membrane separator is arranged at the rear side of a station of the electrodialysis device, and the electrodialysis device is connected with the membrane separator;
the ion exchanger is arranged at the rear side of the station of the membrane separator, and the membrane separator is connected with the ion exchanger;
the evaporation concentration device is arranged at the rear side of a station of the membrane ion exchanger, the ion exchanger is connected with the evaporation concentration device, and the evaporation concentration device is connected with the xylose storage tank;
a continuous path for preparing xylose from the black liquor of the paper mill is formed among the black liquor storage tank, the black liquor dilution tank, the nanofiltration membrane device, the hydrolysis device, the filtering device, the electrodialysis device, the membrane separator, the ion exchanger, the evaporation concentration device and the xylose storage tank.
Further, the process water inlet pipe is connected with a process water storage tank.
Further, a nanofiltration alkali liquor outlet on the nanofiltration membrane device is connected with a nanofiltration alkali liquor temporary storage tank.
Furthermore, the nanofiltration membrane in the nanofiltration membrane device is a roll membrane.
Further, the nanofiltration membrane device comprises a nanofiltration membrane device I and a nanofiltration membrane device II, a black liquor dilution tank discharge port is connected with a nanofiltration membrane device I feed inlet, a nanofiltration concentrate outlet on the nanofiltration membrane device I is connected with a nanofiltration membrane device II feed inlet, and a process water inlet pipe is connected with the nanofiltration membrane device II, and a nanofiltration concentrate outlet on the nanofiltration membrane device II is connected with a hydrolysis device.
Furthermore, the nanofiltration alkali liquor outlet on the nanofiltration membrane device I and the nanofiltration alkali liquor outlet on the nanofiltration membrane device II are connected with a nanofiltration alkali liquor temporary storage tank.
Further, the hydrolysis device is connected with a sulfuric acid conveying pipe for adjusting acidity and a steam pipe for heating.
In addition, the devices are also matched with a cleaning system, and the cleaning system comprises a cleaning tank, various cleaning agent adding devices, matched pipelines and the like. And according to actual demands, each conveying pipeline is provided with a flowmeter, a control valve, an automatic control device and the like.
In this technical scheme, relate to theory of operation and include:
in the nanofiltration membrane system, the pressure difference at two sides of the nanofiltration membrane is used as a driving force, the nanofiltration membrane is used as a filtering medium, and under a certain pressure, when the stock solution flows through the surface of the nanofiltration membrane, a plurality of tiny micropores densely distributed on the surface of the nanofiltration membrane only allow water and small molecular substances to pass through to become permeate, and substances with the volume larger than the micro-pore diameter of the surface of the nanofiltration membrane in the stock solution are trapped at the liquid inlet side of the nanofiltration membrane to become concentrated solution, so that the purposes of purifying, separating and concentrating the stock solution are realized.
In a hydrolysis system, sulfuric acid acts as a catalyst with hemicellulose under a certain temperature condition, so that a reaction path is changed, the activation energy of the reaction is reduced, and the hemicellulose is promoted to react with water to decompose into xylose and various substances.
The technical scheme relates to the relations of the back side of the station, the relation between the stations, the relation between the inner side and the upper side, etc., which are defined according to the condition of the actual use state, are conventional expressions in the technical field and are also conventional expressions in the actual use process of the operators in the field.
By adopting the technical scheme, the beneficial technical effects brought are as follows:
1. in the invention, the black liquor of paper mill is dealkalized by nanofiltration, most of alkali liquor is effectively separated, and nanofiltration concentrated solution and nanofiltration alkali liquor are obtained; the concentrated solution has low alkali content, can effectively reduce hydrolysis acidity, and creates conditions for hydrolysis reaction and subsequent refinement; the alkali liquor contains higher sodium hydroxide and a small amount of organic matters such as hemicellulose, and the separation and recovery of alkali in the black liquor are effectively realized. The hemicellulose is converted into xylose by hydrolysis reaction, and other organic matters are reacted and separated from the hydrolysis liquid and discharged along with hydrolysis filter residues, so that the treatment of the organic matters in the black liquor is effectively realized, and the method has very important significance for protecting the environment;
in the process of nano-filtering, dealkalizing and hydrolyzing black liquor to prepare xylose in a paper mill, the specific control conditions of nano-filtering and hydrolyzing are limited, so that on one hand, the alkali removal rate in the black liquor is increased, and the recycling of alkali is realized; on the other hand, the hemicellulose is effectively converted into xylose by hydrolysis, thereby creating economic benefits. The recycling of resources is realized, the COD content in the sewage is greatly reduced, and the environmental protection pressure is effectively reduced;
2. the invention is applied to the comprehensive utilization process of the black liquor in the paper mill, thereby achieving the purposes of purifying alkali and hemicellulose in the black liquor in the paper mill and classifying and recycling. On the premise of effectively reducing black liquor pollution of paper mill, the production of xylose products is realized, and the economic benefit is improved. Meanwhile, the recycling of the hemicellulose and the alkali is realized, the environmental protection benefit is greatly improved, and the environmental protection pressure is reduced;
3. according to the invention, the nanofiltration and hydrolysis combined method is adopted to recover alkali and prepare xylose, so that the operation efficiency and the separation effectiveness are improved, the controllability is higher, the introduction of new impurities is effectively avoided, the cost is reduced, and the profit is effectively increased;
4. in the invention, the service life of various membrane devices is greatly prolonged (the service life of the membrane is prolonged by more than 30 percent), the stability of the comprehensive utilization process of black liquor in paper mill is improved, and the cost of equipment consumption is reduced.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a functional block diagram (I) of the manufacturing system of the present invention;
FIG. 3 is a functional block diagram (II) of the preparation system of the present invention;
FIG. 4 is a schematic diagram of the operation principle of the nanofiltration membrane in the invention;
FIG. 5 is a schematic diagram of a hydrolysis workflow in the present invention;
wherein, in the figure: 1. black liquor diluting tank, 2, nanofiltration membrane device, 21, nanofiltration membrane device I, 22, nanofiltration membrane device II, 3, hydrolysis device, 4, electrodialysis device, 5, membrane separator, 6, evaporation concentration device, 7, paper mill black liquor storage tank, 8, process water inlet pipe, 9, xylose storage tank, 10, process water storage tank, 11, nanofiltration alkali liquor temporary storage tank, 12, sulfuric acid conveying pipe, 13, steam pipe, 14, filtration device, 15, ion exchanger.
Detailed Description
In the following, it is obvious that the embodiments described are only some embodiments of the present invention, but not all embodiments, by clearly and completely describing the technical solutions in the embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
The present embodiment provides: a process for preparing xylose from black liquor of paper mill, as shown in fig. 1, comprising the steps of:
1) Dilution: the mass ratio of the black liquor to the process water in the paper mill is 1:1-3, diluting the black liquor to obtain black liquor diluent;
wherein the black liquor of the paper mill comprises 30-35g/L hemicellulose, 20-24g/L sodium hydroxide and 50-60g/L lignin;
2) Nanofiltration dealkalization: introducing the black liquor diluent into a nanofiltration membrane device 2, and controlling to obtain nanofiltration alkaline liquor with refraction of 0.5-0.6 and nanofiltration concentrated liquor with refraction of 20-24 (comprising hemicellulose concentration > 30g/L and sodium hydroxide concentration < 3 g/L) under the action of the nanofiltration membrane device 2 (shown in figure 4); wherein, after the nanofiltration alkali liquor is stored in the temporary storage tank, the nanofiltration alkali liquor can be recycled or concentrated for takeaway;
3) Hydrolysis: adding acid into the nanofiltration concentrated solution, hydrolyzing (shown in figure 5), filtering to remove unhydrolyzed lignin, and controlling to obtain filter residue and hydrolysate (comprising xylose concentration > 25g/L, sodium sulfate concentration 4-5g/L and sulfuric acid concentration 20-21 g/L) with refraction of 6.8-7.4 and electric conductance of 32-36 ms/cm;
4) Post-treatment: and (3) carrying out electrodialysis device deacidification, membrane separator pigment and colloid removal, ion exchanger ion removal and evaporation concentration device concentration on the hydrolysate, and further refining to obtain xylose.
Example 2
Based on the embodiment 1, the embodiment adopts two-stage nanofiltration dealkalization, and the specific steps are as follows:
the nanofiltration dealkalization comprises a first nanofiltration dealkalization and a second nanofiltration dealkalization, and the black liquor diluent is subjected to a first nanofiltration dealkalization to obtain a first nanofiltration alkali liquor and a first nanofiltration concentrated liquor; performing secondary nanofiltration dealkalization on the primary nanofiltration concentrated solution to obtain secondary nanofiltration alkali liquor and secondary nanofiltration concentrated solution;
wherein, in the nanofiltration membrane device I21, the feeding flow of the black liquor diluent is 35-40m 3 And/h, the discharge flow of the primary nanofiltration alkali liquor is 25-30m 3 And/h, the discharge flow of the first-level nanofiltration concentrated solution is 10-15m 3 /h; the pressure is 30-35bar, and the operating temperature is 35-40 ℃.
In the nanofiltration membrane device II 22, the feed flow rate of the primary nanofiltration concentrated solution is 25-30m 3 And/h, the water supplementing flow of the process water is 15-20m 3 /h; the discharge flow of the secondary nanofiltration alkali liquor is 15-20m 3 And/h, the discharge flow of the secondary nanofiltration concentrated solution is 10-15m 3 /h; the pressure is 30-35bar, and the operating temperature is 35-40 ℃.
And the first-level nanofiltration concentrated solution comprises hemicellulose with the concentration of 30-35g/L and sodium hydroxide with the concentration of 6.0-8.0 g/L; the primary nanofiltration alkaline liquor comprises hemicellulose with the concentration of 0.5-1.0g/L and sodium hydroxide with the concentration of 6.0-8.0 g/L.
The secondary nanofiltration concentrated solution comprises hemicellulose with the concentration of 30-35g/L and sodium hydroxide with the concentration of 2-3 g/L; the secondary nanofiltration alkaline liquor comprises hemicellulose with the concentration of 0.5-1g/L and sodium hydroxide with the concentration of 2-3 g/L.
Example 3
The present embodiment provides: a system for preparing xylose by using black liquor from paper mill, as shown in figure 2, comprises a black liquor dilution tank 1, a nanofiltration membrane device 2, a hydrolysis device 3, a filtering device 14, an electrodialysis device 4, a membrane separator 5, an ion exchanger 15 and an evaporation concentration device 6;
the front side of the station of the black liquor diluting tank 1 is provided with a paper mill black liquor storage tank 7, a discharge hole of the paper mill black liquor storage tank 7 is connected with a feed hole of the black liquor diluting tank 1, the black liquor diluting tank 1 is connected with a process water inlet pipe 8, and the process water inlet pipe 8 is connected with a process water storage tank 10; the nanofiltration membrane device 2 is arranged at the rear side of a station of the black liquor dilution tank 1, and a discharge port of the black liquor dilution tank 1 is connected with a feed port of the nanofiltration membrane device 2; the hydrolysis device 3 is arranged at the rear side of a station of the nanofiltration membrane device 2, a nanofiltration concentrated solution outlet on the nanofiltration membrane device 2 is connected with a feed inlet of the hydrolysis device 3, and a nanofiltration alkali solution outlet on the nanofiltration membrane device 2 is connected with a nanofiltration alkali solution temporary storage tank 11; the filtering device 14 is arranged at the rear side of the station of the hydrolysis device 3, and a discharge hole of the hydrolysis device 3 is connected with the filtering device 14; the electrodialysis device 4 is arranged at the rear side of a station of the filtering device 14, and a filtrate outlet on the filtering device 14 is connected with the electrodialysis device 4; the membrane separator 5 is arranged at the rear side of the station of the electrodialysis device 4, and the electrodialysis device 4 is connected with the membrane separator 5; the ion exchanger 15 is arranged at the rear side of the station of the membrane separator 5, and the membrane separator 5 is connected with the ion exchanger 15; the evaporation concentration device 6 is arranged at the rear side of a station of the membrane ion exchanger 15, the ion exchanger 15 is connected with the evaporation concentration device 6, and the evaporation concentration device 6 is connected with the xylose storage tank 9;
a continuous path for preparing xylose from the black liquor of the paper mill is formed among the black liquor storage tank 7, the black liquor dilution tank 1, the nanofiltration membrane device 2, the hydrolysis device 3, the filtering device 14, the electrodialysis device 4, the membrane separator 5, the ion exchanger 15, the evaporation concentration device 6 and the xylose storage tank 9.
Example 4
On the basis of the embodiment 3, the nanofiltration membrane device is further limited in the embodiment so as to further explain the technical scheme.
Wherein, the nanofiltration membrane in the nanofiltration membrane device 2 is a coiled membrane, such as: a polyamide alkali-resistant film.
As shown in FIG. 3, the nanofiltration membrane device 2 comprises a nanofiltration membrane device I21 and a nanofiltration membrane device II 22, a discharge port of the black liquor dilution tank 1 is connected with a feed port of the nanofiltration membrane device I21, a nanofiltration concentrate outlet on the nanofiltration membrane device I21 is connected with a feed port of the nanofiltration membrane device II 22, the nanofiltration membrane device II 22 is connected with a process water inlet pipe 8, and a nanofiltration concentrate outlet on the nanofiltration membrane device II 22 is connected with the hydrolysis device 3.
The nanofiltration alkali liquor outlet on the nanofiltration membrane device I21 and the nanofiltration alkali liquor outlet on the nanofiltration membrane device II 22 are connected with the nanofiltration alkali liquor temporary storage tank 11. The hydrolysis apparatus 3 is connected with a sulfuric acid delivery pipe 12 for adjusting acidity and a steam pipe 13 for raising temperature.
Example 5
On the basis of examples 1-4, the black liquor of the paper mill is diluted by twice of process water and then is introduced into the nanofiltration membrane device 2; under the action of nanofiltration membrane (the conditions are shown in the following tables 1-2), performing primary nanofiltration dealkalization and secondary nanofiltration dealkalization to obtain nanofiltration alkali liquor and nanofiltration concentrated solution (shown in the following table 4), wherein the nanofiltration alkali liquor can be recycled or concentrated for takeaway after being stored in a temporary storage tank;
then, the nanofiltration concentrated solution is hydrolyzed under certain conditions (the conditions are shown in the following table 3), and after the hydrolysis is completed, filter residues and hydrolysate are obtained by filtration (the following table 5); the hydrolysate is further refined through decolorization, membrane separation, evaporation and the like to obtain xylose.
Claims (10)
1. A process for preparing xylose from black liquor in a paper mill, comprising the steps of:
1) Dilution: the mass ratio of the black liquor to the process water in the paper mill is 1:1-3, diluting the black liquor to obtain black liquor diluent; wherein the black liquor of the paper mill comprises 30-35g/L hemicellulose, 20-24g/L sodium hydroxide and 50-60g/L lignin;
2) Nanofiltration dealkalization: introducing the black liquor diluent into a nanofiltration membrane device (2), performing nanofiltration dealkalization, and controlling to obtain nanofiltration concentrated solution with refraction of 20-24;
3) Hydrolysis: adding acid into the nanofiltration concentrated solution, hydrolyzing, filtering to remove unhydrolyzed lignin, and controlling to obtain hydrolysate with refraction of 6.8-7.4 and electric conductance of 32-36 ms/cm;
4) Post-treatment: and (3) carrying out electrodialysis device deacidification, membrane separator pigment removal, colloid removal, ion exchanger ion removal and evaporation concentration device concentration on the hydrolysate to obtain xylose.
2. The process for producing xylose from black liquor in paper mill according to claim 1, characterized in that in the nanofiltration dealkalization, the control pressure is 30-35bar and the operating temperature is 35-40 ℃.
3. The process for producing xylose from black liquor of paper mill according to claim 2, characterized in that said nanofiltration dealkalization comprises at least two stages of nanofiltration dealkalization.
4. A process for the preparation of xylose from black liquor in a paper mill according to claim 3, characterised in that the nanofiltration dealkalization comprises a first nanofiltration dealkalization and a second nanofiltration dealkalization, the black liquor dilution is subjected to a first nanofiltration dealkalization in a nanofiltration membrane device i (21), the pressure is controlled to be 30-35bar and the operating temperature is controlled to be 35-40 ℃, and a first nanofiltration lye and a first nanofiltration concentrate are obtained; wherein the first-level nanofiltration concentrated solution comprises hemicellulose with the concentration of 30-35g/L and sodium hydroxide with the concentration of 6.0-8.0 g/L; the primary nanofiltration alkali liquor comprises hemicellulose with the concentration of 0.5-1.0g/L and sodium hydroxide with the concentration of 6.0-8.0 g/L;
performing secondary nanofiltration dealkalization on the primary nanofiltration concentrated solution in a nanofiltration membrane device II (22), controlling the pressure to be 30-35bar and the operating temperature to be 35-40 ℃ to obtain secondary nanofiltration alkali liquor and secondary nanofiltration concentrated solution; wherein, the level nanofiltration concentrated solution comprises hemicellulose with the concentration of 30-35g/L and sodium hydroxide with the concentration of 2-3 g/L; the secondary nanofiltration alkaline liquor comprises hemicellulose with the concentration of 0.5-1g/L and sodium hydroxide with the concentration of 2-3 g/L.
5. The process for producing xylose from black liquor in paper mill according to claim 6, wherein in the primary nanofiltration dealkalization step, the flow rate of the black liquor dilution is 35-40m 3 And/h, the discharge flow of the primary nanofiltration alkali liquor is 25-30m 3 And/h, the discharge flow of the first-level nanofiltration concentrated solution is 10-15m 3 /h；
In the secondary nanofiltration dealkalization procedure, the feed flow rate of the primary nanofiltration concentrated solution is 25-30m 3 And/h, the water supplementing flow of the process water is 15-20m 3 /h; the discharge flow of the secondary nanofiltration alkali liquor is 15-20m 3 And/h, the discharge flow of the secondary nanofiltration concentrated solution is 10-15m 3 /h。
6. The process for producing xylose from black liquor of paper mill according to any one of claims 1 to 5, characterized in that the production system employed comprises: a black liquor dilution tank (1), a nanofiltration membrane device (2), a hydrolysis device (3), a filtering device (14), an electrodialysis device (4), a membrane separator (5), an ion exchanger (15) and an evaporation concentration device (6);
the front side of a station of the black liquor dilution tank (1) is provided with a paper mill black liquor storage tank (7), a discharge hole of the paper mill black liquor storage tank (7) is connected with a feed hole of the black liquor dilution tank (1), and the black liquor dilution tank (1) is connected with a process water feed pipe (8); the nanofiltration membrane device (2) is arranged at the rear side of a station of the black liquor dilution tank (1), and a discharge hole of the black liquor dilution tank (1) is connected with a feed hole of the nanofiltration membrane device (2); the hydrolysis device (3) is arranged at the rear side of a station of the nanofiltration membrane device (2), and a nanofiltration concentrated solution outlet on the nanofiltration membrane device (2) is connected with a feed inlet of the hydrolysis device (3); the filtering device (14) is arranged at the rear side of the station of the hydrolysis device (3), and the discharge port of the hydrolysis device (3) is connected with the filtering device (14); the electrodialysis device (4) is arranged at the rear side of a station of the filtering device (14), and a filtrate outlet on the filtering device (14) is connected with the electrodialysis device (4); the membrane separator (5) is arranged at the rear side of a station of the electrodialysis device (4), and the electrodialysis device (4) is connected with the membrane separator (5); the ion exchanger (15) is arranged at the rear side of the station of the membrane separator (5), and the membrane separator (5) is connected with the ion exchanger (15); the evaporation concentration device (6) is arranged at the rear side of a station of the membrane ion exchanger (15), the ion exchanger (15) is connected with the evaporation concentration device (6), and the evaporation concentration device (6) is connected with the xylose storage tank (9);
a continuous path for preparing xylose from the black liquor of the paper mill is formed among a black liquor storage tank (7), a black liquor dilution tank (1), a nanofiltration membrane device (2), a hydrolysis device (3), a filtering device (14), an electrodialysis device (4), a membrane separator (5), an ion exchanger (15), an evaporation concentration device (6) and a xylose storage tank (9).
7. Process for the preparation of xylose from paper mill black liquor according to claim 6, characterized in that the process water inlet pipe (8) is connected with a process water storage tank (10).
8. The process for preparing xylose from black liquor in paper mill according to claim 6, characterized in that the nanofiltration lye outlet on the nanofiltration membrane device (2) is connected with a nanofiltration lye temporary storage tank (11).
9. The process for preparing xylose by using black liquor from paper mill according to claim 6, wherein the nanofiltration membrane device (2) comprises a nanofiltration membrane device I (21) and a nanofiltration membrane device II (22), a discharge port of the black liquor dilution tank (1) is connected with a feed port of the nanofiltration membrane device I (21), a nanofiltration concentrate outlet on the nanofiltration membrane device I (21) is connected with a feed port of the nanofiltration membrane device II (22), a process water inlet pipe (8) is connected with the nanofiltration membrane device II (22), and a nanofiltration concentrate outlet on the nanofiltration membrane device II (22) is connected with the hydrolysis device (3).
10. Process for the preparation of xylose from black liquor in paper mill according to claim 6, characterized in that the hydrolysis device (3) is connected with a sulfuric acid delivery pipe (12) for regulating acidity and a steam pipe (13) for warming up.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311791122.2A CN117683947A (en) | 2023-12-25 | 2023-12-25 | Process for preparing xylose from black liquor of paper mill |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311791122.2A CN117683947A (en) | 2023-12-25 | 2023-12-25 | Process for preparing xylose from black liquor of paper mill |
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| CN117683947A true CN117683947A (en) | 2024-03-12 |
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