CN115109271B

CN115109271B - Method for biologically refining plant fiber raw material and device used by same

Info

Publication number: CN115109271B
Application number: CN202210956162.7A
Authority: CN
Inventors: 刘运思; 张睿哲; 邓日灵
Original assignee: Guangzhou Yuding Biotechnology Co ltd
Current assignee: Guangzhou Yuding Biotechnology Co ltd
Priority date: 2022-08-10
Filing date: 2022-08-10
Publication date: 2023-07-25
Anticipated expiration: 2042-08-10
Also published as: CN115109271A

Abstract

The invention provides a plant fiber raw material biorefinery method and a device used by the same, wherein the method comprises the following steps: extracting plant fiber raw materials by using organic acid to obtain coarse pulp and extract; the crude slurry is washed and then sequentially subjected to desolventizing and dispersing treatment to obtain cellulose; mixing the washing liquid after washing the slurry with the extract, and sequentially carrying out evaporation concentration, hot water stirring and solid-liquid separation to obtain sugar liquid containing organic acid and lignin; reversely extracting the sugar solution containing the organic acid to obtain sugar solution with the organic acid content of less than 1.5wt% and extract phase solution; rectifying the extract phase solution to obtain organic acid and azeotropic liquid; the method adopts an organic acid treatment method to effectively separate the fiber, lignin and hemicellulose in the plant fiber raw material, and simultaneously recycles the used solvents, thereby having high economic benefit, being environment-friendly and being beneficial to industrial production.

Description

Method for biologically refining plant fiber raw material and device used by same

Technical Field

The invention belongs to the technical field of biochemical engineering, and particularly relates to a method for biologically refining a plant fiber raw material and a device used by the method.

Background

Plant fiber raw materials are very abundant renewable resources in nature, and if the plant fiber raw materials can be well utilized, the cost of chemical raw materials and automobile fuels can be greatly reduced. However, the utilization of plant fiber raw materials has been insufficient so far. This is because cellulose, hemicellulose and lignin, which are main components in the plant fiber raw material, are closely combined together and their processability is also poor. The cellulose has a melting temperature higher than the decomposition temperature, and therefore does not have solubility or fluidity even when heated to decompose. A certain pretreatment process is needed for utilizing the plant fiber raw material, hemicellulose and part or all lignin in the plant fiber raw material are separated from cellulose, and hemicellulose is hydrolyzed into sugar liquid mainly containing oligosaccharide, so that the rest cellulose becomes a material which has loose structure and is easy to be rapidly hydrolyzed by acid or enzyme, and the full utilization of biomass is realized.

CN104389216a discloses a process for separating lignin and holocellulose from lignocellulosic feedstock, comprising the steps of: a. mixing wood fiber raw materials with alkali liquor, and soaking and swelling; b. homogenizing the soaked and swelled wood fiber raw material, and filtering and separating to obtain solid filter residues and filtrate I; c. adding the solid filter residue after water washing into a benzenesulfonate water solution, steaming, filtering and separating to obtain filter residue containing holocellulose and filtrate containing lignin; d. washing filter residues containing the holocellulose with water to obtain the holocellulose; e. adding water into the lignin-containing filtrate obtained in the step c to separate out lignin, filtering to obtain lignin filter residue and filtrate II, and washing and drying the lignin filter residue to obtain lignin. The method adopts dilute alkali treatment, does not separate cellulose from hemicellulose, and the generated monosaccharide can be isomerized into organic acid under alkaline condition, so that the oligosaccharide yield is reduced.

CN108660837a discloses a method for separating cellulose, hemicellulose and lignin from plant fiber raw materials, the separating method comprises the steps of pressurizing or heating and steaming the plant fiber raw materials at normal pressure through lactic acid/choline chloride eutectic solvent, selectively dissolving out lignin and hemicellulose, and washing residual insoluble matters to obtain cellulose; adding water into the eutectic solvent dissolution solution containing lignin and hemicellulose to separate out lignin, and washing and separating to obtain lignin; the rest of the eutectic solvent aqueous solution containing hemicellulose is subjected to nanofiltration separation to obtain hemicellulose; the eutectic solvent aqueous solution can be recycled after concentration and dehydration. The method adopts the filter membrane to filter and obtain the hemicellulose, has higher cost, and the obtained hemicellulose is not easy to be utilized in the form of filtrate due to the existence of choline chloride, and the utilization means has certain limitation.

In summary, how to provide a biorefinery method for effectively separating cellulose, hemicellulose and lignin from plant fiber raw materials with simple process flow and high economic benefit and realizing resource utilization is a current urgent problem to be solved.

Disclosure of Invention

Aiming at the problems existing in the prior art, the invention aims to provide a plant fiber raw material biorefinery method and a device used by the plant fiber raw material biorefinery method, wherein the method adopts an organic acid treatment method to effectively separate fibers, lignin and hemicellulose in plant fiber raw materials, and simultaneously solvents used in production are recycled, so that the resource utilization is realized, the economic benefit is high, the environment is friendly, and the industrial production is facilitated.

To achieve the purpose, the invention adopts the following technical scheme:

in one aspect, the present invention provides a method for biorefinery of a plant fiber raw material, the method comprising the steps of:

(1) Extracting plant fiber raw materials by using organic acid to obtain coarse pulp and extract;

(2) Countercurrent washing is carried out on the coarse pulp obtained in the step (1) by adopting organic acid, so as to obtain washing liquid and washing pulp; then desolventizing the obtained washing slurry to obtain organic acid and desolventized slurry; performing dispersion treatment on the desolventizing slurry to obtain cellulose;

(3) Combining the extract liquid obtained in the step (1) with the washing liquid obtained in the step (2), and evaporating and concentrating to obtain organic acid and concentrated extract liquid; stirring and solid-liquid separation are sequentially carried out on the concentrated extract liquid to obtain a sugar liquid with lignin and organic acid content of 10-30wt%;

(4) Reversely extracting the sugar solution with the organic acid content of 10-30wt% in the step (3) by adopting a good solvent to obtain sugar solution with the organic acid content of less than 1.5wt% and an extract phase solution; and rectifying the extract phase solution to obtain the organic acid and azeotropic liquid.

In the method, the vegetable fiber raw material is extracted by adopting organic acid, and the obtained coarse pulp has good drainage property (the beating degree is less than or equal to 15 DEG SR), so that the subsequent washing efficiency is improved, and further, the extraction rate of lignin is increased; filtering the obtained extract liquid before evaporating and concentrating to remove fine particles, thereby being beneficial to improving the quality of lignin and hemicellulose; the method has the advantages of simple process flow, high economic benefit and better industrial application prospect.

In the invention, the extraction by using organic acid mainly removes lignin in plant fiber raw materials, and the lignin is dissolved out physically and chemically. Physical leaching refers to low molecular weight lignin in which organic acid is more soluble in raw materials, and chemical reaction leaching refers to that under the action of an organic acid extract, the high molecular weight lignin is mainly broken by alpha-O-aryl ether bonds and beta-O-aryl ether bonds to generate low molecular weight lignin, so that the low molecular weight lignin is further dissolved in the organic acid extract.

In the invention, a large amount of hemicellulose is degraded into oligosaccharide and monosaccharide in the process of extracting by utilizing organic acid, because the hemicellulose molecular chain contains free hydroxyl groups and has more branched chains, the types and the connection modes of glycosyl groups are various, and glycosidic bonds among glycosyl groups in an acidic medium are broken, so that the hemicellulose is degraded and dissolved in an organic acid extract.

The following technical scheme is a preferred technical scheme of the invention, but is not a limitation of the technical scheme provided by the invention, and the technical purpose and beneficial effects of the invention can be better achieved and realized through the following technical scheme.

As a preferred embodiment of the present invention, the solid-to-liquid ratio of the plant fiber raw material to the organic acid in the step (1) is 1 (4-20) kg/L, for example, 1:4kg/L, 1:5kg/L, 1:6kg/L, 1:8kg/L, 1:10kg/L, 1:12kg/L, 1:14kg/L, 1:16kg/L, 1:18kg/L, or 1:20kg/L, etc., but not limited to the above values, and other non-listed values within the above values are equally applicable, preferably 1 (8-16) kg/L.

In the present invention, the plant fiber raw materials include bagasse, bamboo, straw, wheat straw, corn stalk, reed, pine wood, eucalyptus, etc., but are not limited thereto.

In the invention, the extraction effect is better as the addition amount of the organic acid is larger, but the consumption amount of the organic acid is overlarge, the cost is larger, and the economical efficiency is poorer.

Preferably, the organic acid in step (1) includes any one of formic acid, acetic acid or propionic acid.

Preferably, the concentration of the organic acid in step (1) is 40-99wt%, such as 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt% or 99wt%, etc., but is not limited to the recited values, and other non-recited values within this range are equally applicable, preferably 60-90wt%.

Preferably, the temperature of the extraction in step (1) is 100-180 ℃, for example 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 165 ℃, 170 ℃, 175 ℃ or 180 ℃, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable, preferably 130-150 ℃.

In the invention, the extraction temperature has important influence on the extraction of the following three components. Too low a temperature can result in incomplete lignin removal, and difficult pulping of fiber raw materials; if the temperature is too high, lignin removal is promoted, and a large amount of cellulose and hemicellulose are degraded, so that the pulp yield is reduced.

Preferably, the time of the extraction in the step (1) is 60-300min, for example 60min, 90min, 120min, 150min, 180min, 210min, 240min, 270min or 300min, etc., but not limited to the recited values, and other non-recited values within the range are equally applicable, preferably 120-180min.

In the present invention, the yield of the brown stock after extraction is 40 to 70%, for example 40%, 45%, 50%, 55%, 60%, 65% or 70%, etc., but is not limited to the values listed, and other values not listed in the range are equally applicable.

In the present invention, the lignin content in the raw pulp obtained after extraction is 3 to 15wt%, for example, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%, etc.; the hemicellulose content is 30-60wt%, for example 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt% or 60wt%, etc., and the above values are not limited to the values recited, but other values not recited in the respective ranges are equally applicable.

In the invention, the lignin content in the extracted liquid obtained after extraction accounts for 50-90wt% of lignin in the raw material, such as 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt% or the like; the hemicellulose content is 30-60wt%, such as 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, etc. of the hemicellulose in the material, and the selection of the above values is not limited to the listed values, and other values not listed in the respective value ranges are equally applicable.

In a preferred embodiment of the present invention, the number of the countercurrent washing stages is at least 2, for example, 2, 3, 4, 5, 6 or 7 stages, but the present invention is not limited to the recited values, and other non-recited values within the range are equally applicable.

In the present invention, the number of the countercurrent washing stages is equal to the number of the washing apparatuses required.

Preferably, the countercurrent washing is performed in the following manner: the detergent enters from the last section, between two adjacent sections of washing, the washing liquid obtained after the washing of the last section is used as the detergent of the previous section; finally, the washing liquid in the first stage and the extracting liquid are collected in the same tank, and the obtained washing slurry is discharged from the last stage.

In the invention, the washing equipment of the first section is connected with an extractor, and the washing equipment of the last section is connected with a desolventizing machine; criteria for washing completion included: the washing liquid in the first stage, i.e. the last washing liquid, is yellow or transparent and colorless.

In the method, a multi-stage countercurrent washing mode is adopted, namely, the washing liquid obtained after the washing of the next stage is used as the washing agent of the previous stage between the two stages of washing, and the washing mode can effectively reduce the consumption of the washing solvent, and simultaneously improve the concentration of the washing liquid, thereby being beneficial to the subsequent extraction of lignin and hemicellulose.

Preferably, the content of organic acid in the desolventizing slurry of step (2) is 0.05-3wt%, e.g. 0.05wt%, 0.1wt%, 0.2wt%, 0.5wt%, 0.7wt%, 1.0wt%, 1.2wt%, 1.5wt%, 1.7wt%, 1.9wt%, 2wt%, 2.5wt%, or 2wt%, etc., but is not limited to the recited values, and other non-recited values within this range of values are equally applicable.

Preferably, the organic acid obtained after the desolventizing treatment in the step (2) includes 3 recovery routes, and the first route is returned to the step (1) for recycling; the second way is to carry out rectification together with the extract phase solution in the step (4); route three is recycled for return to the last wash, preferably a combination of routes one and two.

In the present invention, the recovery route of the organic acid may be performed 3 kinds simultaneously, and any one or a combination of two kinds may be selected.

Preferably, the dispersing treatment in the step (2) includes any one of hydraulic pulping, pulp fluffing and pulp wire-separating fibrillation.

As a preferred technical scheme of the invention, the washing liquid and the extracting liquid in the step (3) are filtered before being subjected to the evaporation concentration.

Preferably, the filter pore size of the filter is greater than 300 mesh, such as 320 mesh, 340 mesh, 360 mesh, 380 mesh, 400 mesh, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

In the invention, the pore size of the filter material has a certain influence on the quality of the final lignin. If the mesh number is too small, large-particle impurities in the concentrated extract are more, and the lignin quality and the preparation of downstream products are affected.

Preferably, the organic acid obtained after evaporation and concentration in the step (3) comprises 3 recovery paths, and the first path is returned to the step (1) for recycling; the second way is to carry out rectification together with the extract phase solution in the step (4); route three is recycled for return to the last wash, preferably a combination of routes one and two.

Preferably, the temperature of the evaporation concentration in the step (3) is 120-150 ℃, for example 120 ℃, 130 ℃, 140 ℃, 150 ℃, etc., but is not limited to the recited values, and other non-recited values within the range of the recited values are equally applicable.

In the present invention, the solid content of the concentrated extract is 40 to 60wt%, for example 40wt%, 45wt%, 50wt%, 55wt% or 60wt%, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the stirring in step (3) is performed in water at 40-90 ℃, for example 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ or 90 ℃, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the stirring speed in step (3) is 100-1000rpm, such as 100rpm, 200rpm, 300rpm, 400rpm, 500rpm, 600rpm, 700rpm, 800rpm, 900rpm or 1000rpm, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable, preferably 500-1000rpm.

In the present invention, the lignin in step (3) has a solid content of 15 to 65wt%, for example, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt% or 65wt%, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

In the present invention, the concentration of sugar in the sugar solution having the organic acid content of 10 to 30wt% in the step (3) is 0.5 to 20wt%, for example, 0.5wt%, 1wt%, 5wt%, 7wt%, 10wt%, 12wt%, 15wt%, 18wt% or 20wt%, etc., but not limited to the recited values, and other non-recited values within the range of the values are equally applicable.

In the invention, the removal rate of lignin in the plant fiber raw material after the step (3) can reach 50-90%, and lignin contains a large number of functional groups such as hydroxyl, methoxy, ester bonds and the like, wherein the phenolic hydroxyl content is increased by 50-120%, the carboxyl content is increased by 40-130%, the acetyl content is increased by 30-80%, and the aliphatic hydroxyl content is reduced by 10-20%, so that various special materials can be prepared by modification.

In the invention, 30-60% of hemicellulose in the plant fiber raw material is dissolved after the step (3), and the hemicellulose is further degraded into xylose, glucose, arabinose, galactose or mannose, and the like, so that the sugar solution with the organic acid content of 10-30wt% is obtained.

As a preferred embodiment of the present invention, the back extraction in the step (4) is performed using a good solvent.

Preferably, the good solvent comprises any one of sec-butyl acetate, dichloroethane, toluene or n-hexane.

Preferably, the volume ratio of the good solvent to the sugar solution having an organic acid content of 10-30wt% is (1-6): 1, for example, 1:1, 2:1, 3:1, 4:1, 5:1 or 6:1, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

In the invention, the addition of the good solvent not only can effectively reversely extract the organic acid, but also can effectively reduce the energy consumption of rectification when forming an azeotrope with water during the subsequent separation; and the addition amount of the good solvent needs to be controlled. If the good solvent is too little, the organic acid residue in the sugar solution is more, which is unfavorable for recycling the organic acid; if the good solvent is too much, the organic acid in the sugar solution can be extracted in a better reverse direction, but the waste of the good solvent is caused, and the load of the subsequent rectifying tower is increased.

Preferably, the sugar solution with the organic acid content of less than 1.5wt% in the step (4) is returned to the step (3) to be mixed with the concentrated extract solution and stirred.

According to the invention, the sugar solution is returned to the stirring step of the step (3) for circulation, and the concentration of sugar in the sugar solution can be improved without concentrating the sugar solution by an evaporation concentration mode, so that the energy consumption is greatly saved.

Preferably, the temperature of the rectification in step (4) is 60-90 ℃, such as 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃, 85 ℃, or 90 ℃, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the organic acid obtained after the rectification in the step (4) is returned to the last washing stage and recycled in the step (1).

Preferably, the azeotropic liquid of step (4) comprises water and a good solvent.

Preferably, the azeotropic liquid in the step (4) is split to obtain a good solvent and water, and the obtained good solvent is returned to the step (4) for reverse extraction.

As a preferred technical solution of the present invention, the method comprises the steps of:

(1) Mixing plant fiber raw material and organic acid according to solid-liquid ratio of 1 (8-16) kg/L, extracting at 130-150deg.C for 120-180min to obtain coarse pulp and extract;

(2) Carrying out countercurrent washing on the crude slurry obtained in the step (1) by adopting organic acid for at least 2 sections to obtain washing liquid and washing slurry; then desolventizing the obtained washing slurry to obtain organic acid and desolventized slurry with the organic acid content of 0.05-3wt%, wherein the obtained organic acid comprises 3 recovery paths, and the first path is returned to the step (1) for recycling; the second way is to carry out rectification together with the extract phase solution in the step (4); the third way is to return to the last washing section for recycling; carrying out hydraulic pulping on the desolventizing slurry to obtain cellulose;

(3) Filtering the extract liquid obtained in the step (1) and the washing liquid obtained in the step (2) by adopting a filter material with the aperture larger than 300 meshes, and then evaporating and concentrating at 120-150 ℃ to obtain organic acid and concentrated extract liquid; the obtained organic acid comprises 3 recovery paths, wherein the first path is to return to the step (1) for recycling; the second way is to carry out rectification together with the extract phase solution in the step (4); the third way is to return to the last washing section for recycling; stirring the concentrated extract in water at 40-90 ℃ at a speed of 500-1000rpm, and then carrying out solid-liquid separation to obtain a sugar solution with lignin and organic acid content of 10-30 wt%;

(4) Reversely extracting the sugar solution with the organic acid content of 10-30wt% in the step (3) by adopting a good solvent according to the volume ratio (3-4): 1 to obtain sugar solution with the organic acid content of less than 1.5wt% and an extract phase solution, returning the sugar solution with the organic acid content of less than 1.5wt% to the step (3), mixing with the concentrated extract solution, and stirring; rectifying the extract phase solution at 60-90 ℃ to obtain organic acid and azeotropic liquid, and returning the obtained organic acid to the last washing stage and recycling in the step (1); and (3) carrying out phase separation on the azeotropic liquid to obtain a good solvent and water, and returning the obtained good solvent to the step (4) for recycling.

In the invention, the method effectively realizes the separation and utilization of 3 major components, and simultaneously, the reagents involved in the process are recycled, so that the production cost is reduced, the method is environment-friendly, and the method has better economic benefit.

In another aspect, the present invention provides an apparatus for use in the above method, the apparatus comprising an extraction unit, a washing unit, a reverse extraction unit, and a rectification unit connected in sequence;

the extraction unit comprises an extractor;

the washing unit comprises washing equipment, a desolventizing machine and fiber dispersing equipment which are connected in sequence;

The reverse extraction unit comprises a primary filter, an evaporator, a stirrer, a secondary filter and an extraction tower which are connected in sequence;

the rectification unit comprises a rectification tower.

As a preferable technical scheme of the invention, the extractor comprises any one of a horizontal tube type continuous extractor, an extraction ball or an extraction pot.

Preferably, the washing apparatus comprises at least 2, and is arranged in series, for example 2, 3, 4, 5 or 6, etc., but is not limited to the recited values, and other non-recited values within the range of values are equally applicable.

Preferably, the washing apparatus comprises any one or a combination of at least two of a screw press, twin roll press, vacuum washer or spiral belt washer, typical but non-limiting examples of which are: a combination of a screw press and a twin-roll press, a combination of a vacuum washer and a screw belt washer, a combination of a screw press, a twin-roll press and a vacuum washer, etc.

Preferably, the desolventizing machine comprises any one of a DTDC desolventizing machine, a DT desolventizing machine, a high-bed desolventizing machine, a DTC desolventizing machine or a hybrid desolventizing machine.

Preferably, the fiber dispersing apparatus comprises any one of a hydropulper, a beater, a cylindrical refiner, a conical refiner or a disc refiner.

As a preferred embodiment of the present invention, the back extraction unit further comprises a phase separator connected to the evaporator. Preferably, the primary filter and the secondary filter independently comprise any one of a candle filter, a rotary membrane filter, a single bag filter, a multi-bag filter, a plate and frame filter press, a positive pressure filter, or a negative pressure filter.

Preferably, the stirrer comprises a high speed stirrer.

As a preferable technical scheme of the invention, the rectifying tower comprises any one of a mesh screen type rectifying tower, a packed rectifying tower, a bubble cap rectifying tower, a sieve plate rectifying tower, a float valve rectifying tower, a Raschig ring packed tower, a pall ring packed tower and the like plate type rectifying tower or a packed rectifying tower.

Preferably, the rectification unit further comprises a phase separator connected to the rectification column.

Preferably, the evaporator of the reverse extraction unit, the desolventizing machine of the washing unit and the rectifying tower of the rectifying unit are all connected with a storage tank.

In the invention, organic acid generated in the production process enters a storage tank for mixing, and is recycled through various ways after the concentration is stable.

Compared with the prior art, the invention has the following beneficial effects:

(1) According to the method, the plant fiber raw material is extracted by adopting the organic acid, so that the drainage property of the obtained coarse pulp is improved, and the extraction rate and quality of cellulose, lignin and hemicellulose are effectively improved through the optimization of the subsequent process, so that the yield of cellulose is 48-57%; the extraction rate of lignin reaches more than 79 percent, and the purity reaches more than 89 percent; the extraction rate of hemicellulose reaches more than 74 percent, and the purity reaches more than 88 percent; meanwhile, the recycling of the reagent is realized, and the aim of clean production without waste liquid discharge is fulfilled;

(2) According to the method, the reversely extracted sugar solution is recycled for lignin precipitation, so that the concentration of sugar in the sugar solution can be improved without concentrating the sugar solution in an evaporation concentration mode, and the energy consumption is greatly saved;

(3) The method disclosed by the invention is simple in process flow, low in production energy consumption, good in economic benefit and beneficial to industrial application.

Drawings

FIG. 1 is a process flow diagram of a plant fiber raw material biorefinery process used in example 1 of the invention;

wherein, the device comprises a 1-extraction pot, a 2-spiral pulp extruder, a 3-DTDC desolventizer, a 4-hydraulic pulper, a 5-candle filter, a 6-evaporator, a 7-high-speed stirrer, an 8-plate-and-frame filter press, a 9-reverse extraction tower, a 10-packed rectifying tower, an 11-phase separator and a 12-storage tank.

Detailed Description

For better illustrating the present invention, the technical scheme of the present invention is convenient to understand, and the present invention is further described in detail below. The following examples are merely illustrative of the present invention and are not intended to represent or limit the scope of the invention as defined in the claims.

The following are exemplary but non-limiting examples of the invention:

example 1:

the embodiment provides a plant fiber raw material biorefinery method and a plant fiber raw material biorefinery device, and a process flow chart of the method is shown in fig. 1.

The method comprises the following steps:

(1) Adding reed straw subjected to cutting, screening and purifying treatment into the extraction pot 1, and then adding acetic acid with concentration of 80wt% according to the solid-to-liquid ratio of 1:15kg/L, so that the temperature in the extraction pot 1 is raised to 150 ℃, and preserving heat for 120min; crude pulp and extract liquid obtained after extraction is completed;

the yield of the obtained coarse pulp is 55%, the lignin content in the coarse pulp is 5wt% and the hemicellulose content is 10wt%;

the lignin content in the obtained extract liquid is 83% of the lignin in the raw material, and the hemicellulose content is 75% of the hemicellulose in the raw material;

(2) Pumping the crude slurry and the extract liquid obtained in the step (1) into a pulp extrusion screw machine 2, and carrying out 3-section countercurrent washing by adopting the recovered acetic acid to obtain washing liquid and washing slurry; desolventizing the obtained washing slurry to obtain acetic acid and desolventized slurry; carrying out hydraulic pulping on the desolventizing slurry to obtain cellulose;

(3) Filtering the extract liquid obtained in the step (1) and the washing liquid obtained in the step (2) by adopting a filter material with the aperture of 350 meshes, and then evaporating and concentrating at the temperature of 125 ℃ to obtain acetic acid and a concentrated extract liquid; stirring the concentrated extract in water at 60 ℃ at a speed of 700rpm, and then filtering to obtain a sugar solution with lignin and acetic acid content of 15 wt%;

(4) Reversely extracting the sugar solution with acetic acid content of 15wt% in the step (3) by adopting dichloroethane according to the volume ratio of 3:1 to obtain sugar solution with acetic acid content of 0.8wt% and an extract phase solution; returning the sugar solution with the acetic acid content of 0.8 weight percent to the step (3), mixing with the concentrated extract solution and stirring; rectifying the extract phase solution at 76 ℃ to obtain acetic acid and azeotropic liquid; and (3) carrying out phase separation on the azeotropic liquid to obtain dichloroethane and water, and returning the obtained dichloroethane to the step (4) for recycling.

The acetic acid generated in the production process of the step (2) and the step (3) comprises 3 recovery ways, wherein the first way is to return to the step (1) for recycling, and the second way is to carry out rectification together with the extraction phase solution of the step (4); the third way is to return to the last washing section for recycling;

And (3) returning the acetic acid generated in the production process in the step (4) to the final washing stage and recycling in the step (1).

The method is carried out by adopting a device which comprises an extraction unit, a washing unit, a reverse extraction unit and a rectification unit which are connected in sequence;

the extraction unit comprises an extraction pot 1;

the washing unit comprises 3 spiral pulp extruders 2, a DTDC desolventizing machine 3 and a hydropulper 4 which are connected in sequence;

the reverse extraction unit comprises a candle filter 5, an evaporator 6, a high-speed stirrer 7, a plate-and-frame filter press 8 and a reverse extraction tower 9 which are connected in sequence;

the rectification unit comprises a packed rectification tower 10 and a phase separator 11 which are connected in sequence;

the evaporator 6 of the reverse extraction unit, the DTDC desolventizing machine 3 of the washing unit and the packed rectifying tower 10 of the rectifying unit are all connected with a storage tank 12.

Example 2:

the embodiment provides a plant fiber raw material biorefinery method and a device used by the same, wherein the method comprises the following steps:

(1) Adding chopped, screened and purified corn stalks into the extraction pot 1, and then adding propionic acid with the concentration of 85wt% according to the solid-to-liquid ratio of 1:20kg/L, so that the temperature in the extraction pot 1 is raised to 165 ℃, and preserving heat for 180min; crude pulp and extract liquid obtained after extraction is completed;

The yield of the obtained coarse pulp is 48%, the lignin content in the coarse pulp is 4wt% and the hemicellulose content is 7%;

the lignin content in the obtained extract liquid accounts for 89% of the lignin in the raw material, and the hemicellulose content accounts for 85% of hemicellulose in the raw material;

(2) Pumping the crude slurry and the extract liquid obtained in the step (1) into a double-roller pulp extruder, and carrying out 4-section countercurrent washing by adopting the recovered propionic acid to obtain washing liquid and washing slurry; desolventizing the obtained washing slurry to obtain propionic acid and desolventized slurry; carrying out hydraulic pulping on the desolventizing slurry to obtain cellulose;

(3) Filtering the extract liquid obtained in the step (1) and the washing liquid obtained in the step (2) by using a filter material with the aperture of 400 meshes, and then evaporating and concentrating at 145 ℃ to obtain propionic acid and a concentrated extract liquid; stirring the concentrated extract in water at 90 ℃ at a speed of 1000rpm, and then filtering to obtain a sugar solution with lignin and propionic acid content of 18 wt%;

(4) Reversely extracting the sugar solution with 18 weight percent of propionic acid content in the step (3) by toluene according to the volume ratio of 4:1 to obtain the sugar solution with 0.9 weight percent of propionic acid content and an extract phase solution; returning the sugar solution with the propionic acid content of 0.7 weight percent to the step (3), mixing with the concentrated extract solution and stirring; rectifying the extract phase solution at 90 ℃ to obtain propionic acid and azeotropic liquid; and (3) carrying out phase separation on the azeotropic liquid to obtain toluene and water, and returning the obtained toluene to the step (4) for recycling.

The propionic acid generated in the production process of the step (2) and the step (3) comprises 3 recovery paths, wherein the first path is returned to the step (1) for recycling, and the second path is rectified together with the extraction phase solution of the step (4); the third way is to return to the last washing section for recycling;

and (3) returning the propionic acid generated in the production process in the step (4) to the final washing stage and recycling in the step (1).

the extraction unit comprises an extraction pot 1;

the washing unit comprises 4 double-roller pulp extruders, a high-material-layer desolventizing machine and a hydropulper 4 which are connected in sequence;

the reverse extraction unit comprises a rotary membrane filter, an evaporator 6, a high-speed stirrer 7, a plate-and-frame filter press 8 and a reverse extraction tower 9 which are connected in sequence;

the evaporator 6 of the reverse extraction unit, the high-material-layer desolventizing machine of the washing unit and the packing type rectifying tower 10 of the rectifying unit are connected with a storage tank 12.

Example 3:

(1) Adding reed straw subjected to cutting, screening and purifying treatment into an extraction pot 1; then adding acetic acid with concentration of 80wt% according to the solid-liquid ratio of 1:15 kg/L; raising the temperature in the extraction pot 1 to 140 ℃, and preserving the heat for 150min; crude pulp and extract liquid obtained after extraction is completed;

the yield of the obtained coarse pulp is 57%, the lignin content in the coarse pulp is 6wt% and the hemicellulose content is 10wt%;

the lignin content in the obtained extract liquid accounts for 79% of the lignin in the raw material, and the hemicellulose content accounts for 74% of hemicellulose in the raw material;

(3) Filtering the extract liquid obtained in the step (1) and the washing liquid obtained in the step (2) by adopting a filter material with the aperture of 320 meshes, and then evaporating and concentrating at the temperature of 125 ℃ to obtain acetic acid and a concentrated extract liquid; stirring the concentrated extract in water at 50 ℃ at a speed of 500rpm, and then filtering to obtain a sugar solution with lignin and acetic acid content of 20 wt%;

(4) Adopting sec-butyl acetate to reversely extract the sugar solution with the acetic acid content of 20wt% in the step (3) according to the volume ratio of 3:1 to obtain sugar solution with the acetic acid content of 0.7wt% and an extract phase solution; returning the sugar solution with the acetic acid content of 0.7 weight percent to the step (3), mixing with the concentrated extract solution and stirring; rectifying the extract phase solution at 90 ℃ to obtain acetic acid and azeotropic liquid; and (3) carrying out phase separation on the azeotropic liquid to obtain sec-butyl acetate and water, and returning the obtained sec-butyl acetate to the step (4) for recycling.

the extraction unit comprises an extraction pot 1;

The washing unit comprises 3 pulp extrusion screw machines 2, a DTDC desolventizing machine 3 and a hydropulper 4 which are connected in sequence;

the reverse extraction unit comprises a candle filter 5, an evaporator 6, a high-speed stirrer 7, a plate-and-frame filter press 8 and a reverse extraction tower 9 which are connected in sequence; the reverse extraction unit further comprises a phase separator 11 connected to the evaporator 6;

Example 4:

this example provides a process for biorefinery of a plant fibre raw material, which process differs from that of example 1 only in that: the concentration of acetic acid in the step (1) is 50wt%.

Example 5:

this example provides a process for biorefinery of a plant fibre raw material, which process differs from that of example 1 only in that: the temperature of the extraction in step (1) was 100 ℃.

Example 6:

this example provides a process for biorefinery of a plant fibre raw material, which process differs from that of example 2 only in that: the temperature of the extraction in step (1) was 185 ℃.

Example 7:

this example provides a process for biorefinery of a plant fibre raw material, which process differs from that of example 1 only in that: the extract and the washing liquid in the step (3) are not filtered.

Example 8:

this example provides a process for biorefinery of a plant fibre raw material, which process differs from that of example 1 only in that: the volume ratio of dichloroethane to the sugar solution with acetic acid content of 15wt% in the step (4) is 1:1.

Example 9:

this example provides a process for biorefinery of a plant fibre raw material, which process differs from that of example 1 only in that: in the step (3), the stirring speed was 100rpm.

The cellulose, lignin and acid-containing sugar solutions having an acid content of less than 1.5wt% obtained in examples 1 to 9 were measured for the extraction yield and purity of sugar (i.e., hemicellulose), and the results are shown in Table 1.

TABLE 1

By adopting the method disclosed by the invention in the embodiments 1-3, three components in the plant fiber raw material are effectively separated through an optimized process, and the product quality is improved, so that the yield of cellulose is 48-57%, the extraction rate of lignin with the purity of more than 82% is more than 79%, and the purity of lignin is more than 89%; the extraction rate of hemicellulose reaches more than 74 percent, and the purity reaches more than 88 percent; in the embodiment 4, the concentration of acetic acid in the extraction process is reduced, so that the extraction effect is poor, and the extraction rate of lignin and hemicellulose is obviously reduced; in the embodiment 5, the extraction temperature is too low, so that the extraction effect is poor, lignin and hemicellulose are less removed, and the fibers are heavy; in the embodiment 6, the extraction temperature is too high, the extraction rate of lignin and hemicellulose is obviously increased, and the yield of cellulose is low; in the embodiment 7, the pore diameter of the filter material is too large to effectively remove impurities, so that the quality of lignin products is affected; in example 8, the amount of the good solvent in the back extraction was too small, resulting in a large amount of residual organic acid in the sugar solution; the stirring speed in example 9 was low, resulting in flocculation and inclusion of sugar liquor when lignin was precipitated in hot water, thus resulting in a high sugar content in lignin solids.

According to the embodiment, the method adopts the organic acid to extract the plant fiber raw material, so that the drainage property of the obtained coarse pulp is improved, and the extraction rate and quality of cellulose, lignin and hemicellulose are effectively improved through the optimization of the subsequent process, and the purity is more than 82%; the extraction rate of lignin reaches more than 79 percent, and the purity reaches more than 89 percent; the extraction rate of hemicellulose reaches more than 74 percent, and the purity reaches more than 88 percent; meanwhile, the recycling of the reagent is realized, and the aim of clean production without waste liquid discharge is fulfilled; on the other hand, the filtered sugar solution is returned to the stirring step for circulation, and the concentration of sugar in the sugar solution can be improved without concentrating the sugar solution through evaporation concentration, so that the energy consumption is greatly saved; the method has the advantages of simple process flow, low production energy consumption, better economic benefit and contribution to industrial application.

The applicant states that the detailed method and apparatus of the present invention are described by way of the above examples, but the present invention is not limited to, i.e., does not mean that the present invention must be practiced in dependence upon, the above detailed method and apparatus. It should be apparent to those skilled in the art that any modifications, equivalent substitutions for operation of the present invention, addition of auxiliary operations, selection of specific modes, etc., are intended to fall within the scope of the present invention and the scope of the disclosure.

Claims

1. A method for biorefinery of a plant fiber raw material, said method comprising the steps of:

the number of the countercurrent washing sections is at least 2;

the countercurrent washing mode is as follows: the detergent enters from the last section, between two adjacent sections of washing, the washing liquid obtained after the washing of the last section is used as the detergent of the previous section; finally, collecting the washing liquid in the first section and the extracting liquid in the same tank, and discharging the obtained washing slurry from the last section;

the stirring speed in the step (3) is 500-1000rpm;

(4) Reversely extracting the sugar solution with the organic acid content of 10-30wt% in the step (3) by adopting a good solvent to obtain sugar solution with the organic acid content of less than 1.5wt% and an extract phase solution; rectifying the extract phase solution to obtain organic acid and azeotropic liquid;

the good solvent is any one of dichloroethane, toluene or n-hexane;

the volume ratio of the good solvent to the sugar solution with the organic acid content of 10-30wt% is (3-4): 1.

2. The method of claim 1, wherein the solid to liquid ratio of the plant fiber feedstock to the organic acid of step (1) is 1 (4-20) kg/L.

3. The method of claim 2, wherein the solid to liquid ratio of the plant fiber raw material to the organic acid in step (1) is 1 (8-16) kg/L.

4. The method of claim 1, wherein the organic acid of step (1) comprises any one of formic acid, acetic acid, or propionic acid.

5. The process of claim 1, wherein the concentration of the organic acid in step (1) is 40-99wt%.

6. The method of claim 5, wherein the concentration of the organic acid in step (1) is 60-90wt%.

7. The process according to claim 1, wherein the extraction temperature of step (1) is 100-180 ℃.

8. The process of claim 7, wherein the extraction in step (1) is at a temperature of 130-150 ℃.

9. The method according to claim 1, wherein the extraction time of step (1) is 60-300min.

10. The method of claim 9, wherein the extraction time of step (1) is 120-180min.

11. The method according to claim 1, wherein the content of organic acid in the desolventizing slurry of step (2) is 0.05-3wt%.

12. The method according to claim 1, wherein the organic acid obtained after the desolventizing treatment in step (2) includes 3 recovery routes, one route is returned to step (1) for recycling; the second way is to carry out rectification together with the extract phase solution in the step (4); and the third way is to return to the last washing stage for recycling.

13. The method of claim 12, wherein the organic acid obtained after the desolventizing treatment of step (2) is a combination of pathway one and pathway two.

14. The method of claim 1, wherein the dispersing in step (2) comprises any of hydraulic pulping, slurry fluffing, or slurry fibrillation.

15. The method of claim 1, wherein the washing solution and the extraction solution of step (3) are filtered prior to the evaporation concentration.

16. The method of claim 15, wherein the filtered filter pore size is greater than 300 mesh.

17. The method of claim 1, wherein the organic acid obtained after the evaporation and concentration in the step (3) comprises 3 recovery routes, wherein the first route is returned to the step (1) for recycling; the second way is to carry out rectification together with the extract phase solution in the step (4); and the third way is to return to the last washing stage for recycling.

18. The method of claim 17, wherein the organic acid obtained after concentration by evaporation in step (3) is a combination of pathway one and pathway two.

19. The method of claim 1, wherein the temperature of the evaporative concentration in step (3) is 120-150 ℃.

20. The method of claim 1, wherein the stirring of step (3) is performed in water at 40-90 ℃.

21. The method of claim 1, wherein the sugar solution of step (4) having an organic acid content of less than 1.5wt% is returned to step (3) to be mixed with the concentrated extract solution and stirred.

22. The method of claim 1, wherein the temperature of the rectification of step (4) is 60-90 ℃.

23. The method according to claim 1, wherein the organic acid obtained after the rectification in step (4) is returned to the last washing stage and recycled in step (1).

24. The process of claim 1 wherein the azeotropic liquid in step (4) comprises water and a good solvent.

25. The method of claim 1, wherein the azeotropic liquid is separated in step (4) to obtain a good solvent and water, and the good solvent is returned to step (4) for back extraction.

26. The method according to claim 1, characterized in that it comprises the steps of:

(4) Reversely extracting the sugar solution with the organic acid content of 10-30wt% in the step (3) by adopting a good solvent according to the volume ratio (3-4): 1 to obtain sugar solution with the organic acid content of less than 1.5wt% and an extract phase solution, returning the sugar solution with the organic acid content of less than 1.5wt% to the step (3), mixing with the concentrated extract solution, and stirring; rectifying the extract phase solution at 60-90 ℃ to obtain organic acid and azeotropic liquid, and returning the obtained organic acid to the last washing stage and recycling in the step (1); the azeotropic liquid is subjected to phase separation to obtain a good solvent and water, and the obtained good solvent is returned to the step (4) for recycling;

The good solvent is any one of dichloroethane, toluene or n-hexane.

27. An apparatus for use in a method according to any one of claims 1 to 26, comprising an extraction unit, a washing unit, a countercurrent extraction unit and a rectification unit connected in sequence;

the extraction unit comprises an extractor;

the reverse extraction unit comprises a primary filter, an evaporator, a stirrer, a secondary filter and a reverse extraction tower which are connected in sequence;

the rectification unit comprises a rectification tower.

28. The apparatus of claim 27, wherein the extractor comprises any one of a cross-tube continuous extractor, an extraction bulb, or an extraction pan.

29. The apparatus of claim 27, wherein the washing device comprises at least 2 washing units and is arranged in series.

30. The apparatus of claim 29, wherein the washing device comprises any one or a combination of at least two of a screw press, a twin roll press, a vacuum washer, or a screw belt washer.

31. The apparatus of claim 27, wherein the desolventizer comprises any one of a DTDC desolventizer, a DT desolventizer, a high-bed desolventizer, a DTC desolventizer, or a hybrid desolventizer.

32. The apparatus of claim 27, wherein the fiber dispersing device comprises any one of a hydropulper, a beater, a cylindrical refiner, a conical refiner, or a disc refiner.

33. The apparatus of claim 27, wherein the reverse extraction unit further comprises a phase separator coupled to the evaporator.

34. The apparatus of claim 27, wherein the primary filter and the secondary filter independently comprise any one of a candle filter, a rotary membrane filter, a single bag filter, a multi-bag filter, a plate and frame filter press, a positive pressure filter, or a negative pressure filter.

35. The apparatus of claim 27, wherein the agitator comprises a high speed agitator.

36. The apparatus of claim 27, wherein the rectifying column comprises any one of a mesh screen rectifying column, a packed rectifying column, a bubble cap rectifying column, a sieve plate rectifying column, a float valve rectifying column, a raschig ring packed column, or a pall ring packed column.

37. The apparatus of claim 27, wherein the rectification unit further comprises a phase separator coupled to the rectification column.

38. The apparatus of claim 27, wherein the evaporator of the reverse extraction unit, the desolventizer of the scrubbing unit, and the rectifying column of the rectifying unit are all connected to a storage tank.