Method for treating lignocellulose

Abstract

The invention relates to the technical field of lignocellulose treatment, in particular to a lignocellulose treatment method which comprises the following steps: step 1, pre-cleaning, cutting, desilting, dedusting and traditional purification treatment; 2, thread rolling is conducted, specifically, a purchased thread rolling machine is used for rolling into threads; 3, enzymolysis: spirally conveying the filamentous material into an enzymolysis tank for enzymolysis; step 4, heating: heating the materials after enzymolysis, and step 5, performing gas explosion: performing gas explosion on the materials by using a gas explosion device so as to complete the treatment of the lignin fibers. According to the invention, when hemicellulose is degraded, degradation of cellulose and polycondensation of lignin are not caused; non-condensable gas does not need to be discharged; and meanwhile, the materials are subjected to gas explosion through the specially-made gas explosion device, the materials exploded through the method are very soft and loose, and different mechanical and chemical treatment processes adopted according to subsequent different requirements are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of lignocellulose treatment, and specifically provides a method for treating lignocellulose. Background Art

[0002] During the treatment of lignin fibers, operations such as enzymatic hydrolysis, heating, and steam explosion are required. However, in enzymatic hydrolysis, the mechanical methods of traditional processes cannot achieve selective degradation. That is, during the degradation of hemicellulose, it will also cause the degradation of cellulose and the condensation of lignin (affected by temperature and pressure). In the chemical methods of traditional processes, a large amount of caustic soda (17%, mass percentage) is used to selectively dissolve hemicellulose and lignin, while swelling a small amount of cellulose. However, it will produce a large amount of difficult-to-treat black liquor, causing environmental pollution.

[0003] During heating, traditional processes generally use low-pressure steam, a condensable gas, to heat lignin fiber raw materials, aiming to displace the non-condensable gas in the raw material capillary tubes. The non-condensable gas needs to be discharged after multiple small air releases. At the same time, during steam explosion, traditional steam explosion treatment is a treatment method developed in recent years. The raw materials are heated with steam to 180 - 235 °C and maintained at a certain pressure for a certain time. When suddenly depressurized and sprayed, secondary steam is generated, and the volume increases sharply. Under the action of mechanical force, the structure of the solid material is damaged. However, due to the high temperature and pressure, the requirements for equipment are high. When spraying, it generates a very high-decibel noise, with high danger and poor environmental protection. Moreover, it is an intermittent operation and cannot be industrialized on a large scale. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for treating lignocellulose to solve the problems mentioned in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A method for treating lignocellulose, comprising the following steps:

[0006] Step 1: Pre-cleaning. Cut crop straws, bamboo, wood, or reeds into a certain specification as required, and then perform mud removal, dust removal, and traditional purification treatment on the cut crop straws, bamboo, wood, or reed materials.

[0007] Step 2: Wire drawing. Immerse the cut and mud-removed, dust-removed, and purified materials in water, and then use an externally purchased wire drawing machine to draw them into filaments.

[0008] Step 3: Enzymatic hydrolysis. Spiral convey the filamentous materials drawn by the wire drawing machine to the inside of an enzymatic hydrolysis tank through a spiral conveyor for enzymatic hydrolysis. The enzyme used during enzymatic hydrolysis is a biological composite enzyme, and the duration of enzymatic hydrolysis is 30 minutes.

[0009] Step 4: Heating. Heat the enzymatically hydrolyzed material. When heating, use a small amount of steam to improve the heating efficiency. At the same time, use microwave heating technology to heat the water in the cavities of the raw material cells, causing the water in the cell cavities to burst by microwave.

[0010] Step 5: Air explosion. Use an air explosion device to perform air explosion on the material. During air explosion, the material is centrifuged at high speed and thrown into the blasting chamber of the air explosion device for high-speed continuous blasting. The moisture of the blasted material will be lost, and the moisture forms steam, thus completing the treatment of lignin fibers.

[0011] Preferably, the crop straws in Step 1 include the straws of gramineous plants such as rice, wheat, sorghum, corn, and cotton. The fine fibers and mud obtained during cutting can be used as fertilizers, biomass, and packaging paper fillers after being pulverized.

[0012] Preferably, the material obtained by cutting, de-mudding, dust-removing, and purification treatment in Step 2 is impregnated with water at a mass ratio of 1:8 - 10 for 1 hour.

[0013] Preferably, the biological composite enzyme in Step 3 is a compound enzyme of xylanase, pectinase, and protease, and the enzymatic hydrolysis temperature of the biological composite enzyme is 55 - 60°C.

[0014] Preferably, the steam in Step 4 is a 3 - 4 bar low-temperature and low-pressure saturated steam.

[0015] Preferably, during the verification experiment in Step 4, the heating method verified by the prototype machine is electromagnetic heating and microwave heating. When electromagnetic heating, it means heating the cooling water of the electromagnetic heating, and heating is carried out through the heated cooling water.

[0016] Preferably, the principle of the air explosion device in Step 5 is to use 8 bar of compressed air to heat the material with a moisture content of 30 - 40% to about 165°C and then enter the blasting intermediate cavity. The material is pressure-locked to ensure that the moisture inside the material will not vaporize and the pressure cannot be released. Then, a self-developed special pump is used to suck the material out of the intermediate cavity. The material is centrifuged at high speed and thrown into the blasting chamber for high-speed continuous blasting. The moisture of the blasted material is lost, and the moisture forms steam.

[0017] Preferably, the steam after blasting in Step 5 is recycled and used to heat the material during enzymatic hydrolysis in Step 3.

[0018] Preferably, the material to be processed has non-condensable gas in its cell cavity. During air explosion, the non-condensable gas in the cell cavity of the material suddenly decompresses in the blasting cavity, which will tear the cell wall from the inside. At the same time, the water in the cell cavity will be carried out during the gas expansion process, exacerbating the rupture of the cell wall. The thermally compressed non-condensable gas is a kind of flue gas, which can reheat the material in the intermediate chamber of air explosion, reduce the consumption of steam, and at the same time solve the problems of desulfurization and denitrification of flue gas.

[0019] Preferably, the material to be processed has non-condensable gas in its cell cavity. During air explosion, the non-condensable gas in the cell cavity of the material suddenly decompresses in the blasting cavity, which will tear the cell wall from the inside. At the same time, the water in the cell cavity will be carried out during the gas expansion process, exacerbating the rupture of the cell wall. The thermally compressed non-condensable gas is a kind of flue gas, which can reheat the material in the intermediate chamber of air explosion, reduce the consumption of steam, and at the same time solve the problems of desulfurization and denitrification of flue gas.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: The method for treating lignocellulose uses a biological composite enzyme, namely a compound enzyme of xylanase, pectinase and protease, during enzymatic hydrolysis, so that while degrading hemicellulose, it will not cause the degradation of cellulose and the condensation of lignin; by using a small amount of steam to improve the heating efficiency, and at the same time using microwave heating technology to heat the water in the cell cavity of the raw material. These two heating methods do not require the discharge of non-condensable gas; at the same time, the material is subjected to air explosion by a special air explosion device. The material after blasting is very soft and loose, which is convenient for subsequent different mechanical and chemical treatment processes according to different requirements. Moreover, the compressed air used for air explosion needs to be flue gas, which can reheat the material in the intermediate chamber of air explosion, reduce the consumption of steam, and at the same time solve the problems of desulfurization and denitrification of flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flowchart of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0023] The structure of a method for treating lignocellulose provided by the present invention is as Figure 1 shown, and includes the following steps:

[0024] Step 1: Pre - cleaning. Cut crop straws, bamboo, wood or reeds into certain specifications as required, and then perform mud removal, dust removal and traditional purification treatment on the cut crop straws, bamboo, wood or reed materials. Among them, the crop straws include herbaceous plant straws of rice, wheat, sorghum, corn and cotton. The fine fibers and mud obtained during cutting can be used as fertilizers, biomass, and packaging paper fillers after being pulverized.

[0025] Step 2: Silk rubbing. Immerse the cut and mud - removed, dust - removed and purified materials in water, and then use an externally purchased silk - rubbing machine to rub them into filaments. Among them, the cut and mud - removed, dust - removed and purified materials are immersed in water for 1 hour at a mass ratio of 1:8 - 10 to increase the contact area between the bio - enzyme and the materials to improve the enzymatic hydrolysis efficiency.

[0026] During specific implementation, cut crop straws, bamboo, wood or reeds into certain specifications as required, and then perform mud removal, dust removal and traditional purification treatment on the cut crop straws, bamboo, wood or reed materials. Among them, the crop straws include herbaceous plant straws of rice, wheat, sorghum, corn and cotton. The fine fibers and mud obtained during cutting can be used as fertilizers, biomass, and packaging paper fillers after being pulverized. Then, immerse the cut and mud - removed, dust - removed and purified materials in water for 1 hour at a mass ratio of 1:8 - 10 to increase the contact area between the bio - enzyme and the materials to improve the enzymatic hydrolysis efficiency, and then use an externally purchased silk - rubbing machine to rub them into filaments.

[0027] Step 3: Enzymatic hydrolysis. Spiral - convey the filamentous materials rubbed by the silk - rubbing machine to the inside of the enzymatic hydrolysis tank through a screw conveyor for enzymatic hydrolysis. The enzyme used during enzymatic hydrolysis is a bio - composite enzyme, and the duration of enzymatic hydrolysis is 30 minutes. Among them, the bio - composite enzyme is a compound enzyme of xylanase, pectinase and protease. The enzymatic hydrolysis temperature of the bio - composite enzyme is 55 - 60°C. Generally speaking, the hemicellulose in gramineae is mainly xylan and a small amount of xyloglucan. Considering that lignin is made into a slow - release organic fertilizer, xylanase + xyloglucanase (GH74) (Paenibacillus sp.) + laccase (Trametes sp.1j - 1 is the best, Phanerochaete chrysosporium) (biological bleaching effect) endo - xylanase generates oligosaccharides; exo - xylanase generates monosaccharides. The endo - xylanase produced by Streptomyces Str7B is very high, and the presence of Mn and Cu ions leads to a decrease in xylanase activity.

[0028] Specifically, from the perspective of the microstructure of lignocellulose, lignin in cell corners and the middle lamella is connected to cellulose microcrystals and structural proteins through hemicellulose. Due to the complexity of the structure of lignin itself, it is the most difficult to remove among the three major categories of plant fibers, hemicellulose, and lignin. Hemicellulose is polymerized from pentose sugars such as xylose. Compared with cellulose microcrystals polymerized from hexose sugars, hemicellulose is more easily degraded regardless of whether mechanical, chemical, or biological methods are used. After hemicellulose is degraded, lignin naturally falls off. Moreover, the degradation of hemicellulose reduces the cross-linking of fiber microcrystals, facilitating the separation of fiber microcrystals. At the same time, the cavities formed after hemicellulose degradation are conducive to the subsequent infiltration of water, gas, steam, and chemical reagents, improving the efficiency of subsequent treatment processes.

[0029] However, in the prior art, mechanical methods cannot achieve selective action. While degrading hemicellulose, they also cause the degradation of cellulose and the condensation of lignin (affected by temperature and pressure). In the chemical method of traditional processes, a large amount of caustic soda (17%, mass percentage) is used to selectively dissolve hemicellulose and lignin, while swelling a small amount of cellulose. However, it will produce a large amount of difficult-to-treat black liquor, causing environmental pollution. The biological method for treating the three major components has strong selectivity, mild reaction conditions, and each enzyme has specificity.

[0030] With the rapid development of biotechnology in the past two decades, ligninase, cellulase, hemicellulase (xylanase), and pectinase are all commercially available. The best ligninase is laccase, but it still takes about 7 days for the best laccase to degrade lignin, which cannot be applied on a large scale industrially. Cellulase mainly cuts, but cellulose is the required product and should be retained as much as possible, so cellulase is not used.

[0031] Step 4: Heating. Heat the enzymatically hydrolyzed material. Use a small amount of steam during heating to improve the heating efficiency. At the same time, use microwave heating technology to heat the water in the cell cavity of the raw material, causing the water in the cell cavity to undergo microwave explosion. The steam is a low-temperature and low-pressure saturated steam of 3 - 4 bar. At the same time, during the verification of the principle machine, the heating method used is electromagnetic heating and microwave heating. Electromagnetic heating means heating the cooling water by electromagnetic induction, and then heating through the heated cooling water.

[0032] In the traditional process of this step, a condensable gas, low-pressure steam, is used to heat the lignocellulose raw material, aiming to displace the non-condensable gas in the capillary of the raw material. The non-condensable gas needs to be discharged after multiple small air releases. However, in the present invention, a small amount of steam is used to improve the heating efficiency, and at the same time, microwave heating technology is used to heat the water in the cell cavity of the raw material. Regardless of the heating method, there is no need to discharge non-condensable gas.

[0033] In specific implementation, the filamentous material formed by the thread rolling machine is spirally conveyed into the enzymolysis tank through a screw conveyor for enzymolysis. The enzyme used in enzymolysis is a biological compound enzyme of a xylanase, a pectinase and a protease. The enzymolysis temperature is 55-60 °C, and the enzymolysis duration is 30 minutes. Then, the enzymolyzed material is heated. When heating, a small amount of 3-4 bar low-temperature and low-pressure saturated steam is used to improve the heating efficiency. At the same time, the microwave heating technology is used to heat the water in the raw material cell cavity, so that the water in the cell cavity is microwave-exploded.

[0034] Step Five: Air explosion. Use a special air explosion device to conduct air explosion on the material. When conducting air explosion, the material is centrifuged at high speed and thrown into the explosion chamber of the air explosion device for high-speed continuous explosion. The water content of the material after explosion will be lost, and the water forms steam, thus completing the treatment of lignin fiber. The principle of the air explosion device is that when 8 bar of compressed air heats the material with a water content of 30-40% to about 165 °C and enters the explosion intermediate cavity, the material is pressure-locked to prevent the water inside the material from vaporizing, that is, the pressure cannot be released. Then, a self-developed special pump is used to suck the material out of the intermediate cavity. The material is centrifuged at high speed and thrown into the explosion chamber for high-speed continuous explosion. The water content of the material after explosion is lost, and the water forms steam. The non-condensable gas in the material cell cavity suddenly decompresses in the explosion chamber, and it will also tear the cell wall from the inside. At the same time, the water in the cell cavity will be carried out during the gas expansion process, aggravating the rupture of the cell wall. The material after explosion by this method is very soft and loose, and is convenient for different mechanical and chemical treatment processes adopted according to different subsequent requirements.

[0035] Specifically, the 6-8 bar compressed air needs to be a compressible non-condensable gas to prevent pressure drop and fail to play the role of pressure locking. It is preferably hot compressed non-condensable gas, such as flue gas, etc., which can heat the material in the air explosion intermediate chamber for the second time, reduce the steam consumption, and at the same time solve the problem of desulfurization and denitrification of flue gas. The steam in the explosion chamber can be recycled and used to heat the material during enzymolysis.

[0036] This traditional steam explosion treatment in this step is a treatment method developed in recent years. The raw material is heated with steam to 180-235 °C, and the pressure is maintained for a certain time. When suddenly decompressing and spraying, secondary steam is generated, and the volume increases sharply. Under the action of mechanical force, the solid material structure is damaged. However, due to the high temperature and high pressure, the requirements for equipment are high. When spraying, very high-decibel noise is generated, with high danger and poor environmental protection, and it is an intermittent operation, so it cannot be industrialized on a large scale. While in the present invention, the material is subjected to air explosion through an air explosion device. The material after explosion is very soft and loose, and is convenient for different mechanical and chemical treatment processes adopted according to different subsequent requirements.

[0037] Finally, use an air explosion device to perform air explosion on the material. During air explosion, the material is centrifugally thrown into the blasting chamber of the air explosion device at high speed for high-speed continuous blasting. The moisture of the material after blasting will be lost, and the moisture forms steam, thus completing the treatment of lignin fiber.

[0038] Method steps: First, cut crop straw, bamboo, wood or reed into certain specifications as required, and then perform mud removal, dust removal and traditional purification treatment on the cut crop straw, bamboo, wood or reed materials. The crop straw includes cereal straws such as rice, wheat, sorghum, corn and cotton. The fine fibers and mud obtained during cutting can be used as fertilizers, biomass and packaging paper fillers after being pulverized; Next, impregnate the cut and mud-removed, dust-removed and purified materials with water at a mass ratio of 1:8 - 10 for 1 hour to increase the contact area between the biological enzyme and the material to improve the enzymatic hydrolysis efficiency, and then use an externally purchased wire drawing machine to draw it into filaments.

[0039] Subsequently, use a screw conveyor to convey the filamentous material drawn by the wire drawing machine spirally into the enzymatic hydrolysis tank for enzymatic hydrolysis. The enzyme used during enzymatic hydrolysis is a biological compound enzyme of a xylanase, pectinase and protease. The enzymatic hydrolysis temperature is 55 - 60 °C, and the duration of enzymatic hydrolysis is 30 minutes; After that, heat the material after enzymatic hydrolysis. When heating, use a small amount of 3 - 4 bar low-temperature and low-pressure saturated steam to improve the heating efficiency. At the same time, use microwave heating technology to heat the moisture in the raw material cell cavity, so that the moisture in the cell cavity undergoes microwave explosion.

[0040] Finally, use an air explosion device to perform air explosion on the material. During air explosion, the material is centrifugally thrown into the blasting chamber of the air explosion device at high speed for high-speed continuous blasting. The moisture of the material after blasting will be lost, and the moisture forms steam, thus completing the treatment of lignin fiber.

[0041] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A method for treating lignocellulose, characterized in that, It includes the following steps: Step 1: Pre-cleaning. Cut crop straws, bamboo, wood or reeds into certain specifications as required, and then perform mud removal, dust removal and traditional purification treatment on the cut crop straws, bamboo, wood or reed materials; Step 2: Silk rubbing. Immerse the cut and mud-removed, dust-removed and purified materials in water, and then use an externally purchased silk rubbing machine to rub them into filaments; Step 3: Enzymatic hydrolysis. Spiral convey the filamentous materials rubbed by the silk rubbing machine into the enzymatic hydrolysis tank through a spiral conveyor for enzymatic hydrolysis. The enzyme used during enzymatic hydrolysis is a biological composite enzyme, and the duration of enzymatic hydrolysis is 30 minutes; Step 4: Heating. Heat the materials after enzymatic hydrolysis. Use a small amount of steam during heating to improve the heating efficiency. At the same time, use microwave heating technology to heat the water in the raw material cell cavity, so that the water in the cell cavity undergoes microwave explosion; Step 5: Air explosion. Use an air explosion device to perform air explosion on the materials. During air explosion, the materials are centrifuged at high speed and thrown into the explosion chamber of the air explosion device for high-speed continuous explosion. The water content of the materials after explosion will be lost, and the water forms steam, thus completing the treatment of lignin fibers.

2. The method for treating lignocellulose according to claim 1, characterized in that: The crop straws in Step 1 include the straws of gramineous plants such as rice, wheat, sorghum, corn and cotton. The fine fibers and mud obtained during cutting can be used as fertilizers, biomass and packaging paper fillers after being pulverized.

3. A method for treating lignocellulose according to claim 1, characterized in that: The materials cut and subjected to mud removal, dust removal and purification treatment in Step 2 are immersed in water at a mass ratio of 1:8 - 10 for 1 hour.

4. A method for treating lignocellulose according to claim 1, characterized in that: The biological composite enzyme in Step 3 is a compound enzyme of xylanase, pectinase and protease, and the enzymatic hydrolysis temperature of the biological composite enzyme is 55 - 60°C.

5. A method for treating lignocellulose according to claim 1, characterized in that: The steam in Step 4 is a 3 - 4 bar low-temperature and low-pressure saturated steam.

6. A method for treating lignocellulose according to claim 5, characterized in that: During the verification experiment in Step 4, the heating method verified by the prototype machine is electromagnetic heating and microwave heating. When electromagnetic heating is used, it means heating the cooling water by electromagnetic heating, and heating is carried out through the heated cooling water.

7. A method for treating lignocellulose according to claim 6, characterized in that: The principle of the air explosion device in Step 5 is that after the compressed air at 8 bar heats the materials with a water content of 30 - 40% to about 165°C and enters the explosion intermediate cavity, the materials are pressure-locked to ensure that the water inside the materials will not vaporize and the pressure cannot be released. Then, a self-developed special pump is used to suck the materials out of the intermediate cavity. The materials are centrifuged at high speed and thrown into the explosion chamber for high-speed continuous explosion. The water content of the materials after explosion is lost, and the water forms steam.

8. A method for treating lignocellulose according to claim 7, characterized in that: The steam after explosion in Step 5 is recycled and used to heat the materials during enzymatic hydrolysis in Step 3.

9. A method for treating lignocellulose according to claim 7, characterized in that: There are non-condensable gases in the cell cavity of the treated materials. During air explosion, the non-condensable gases in the cell cavity of the materials suddenly decompress in the explosion cavity, which will tear the cell wall from the inside. At the same time, the water in the cell cavity will be carried out during the gas expansion process, exacerbating the rupture of the cell wall. This thermally compressed non-condensable gas is a kind of flue gas, and the flue gas can be used to heat the materials in the air explosion intermediate chamber for the second time, reducing the consumption of steam and at the same time solving the problem of desulfurization and denitrification of flue gas.

Images