CN111592257B

CN111592257B - Straw raw material pretreatment method and device of straw water reducing agent

Info

Publication number: CN111592257B
Application number: CN201910166288.2A
Authority: CN
Inventors: 章德玉; 张惠琴; 张建斌; 刘流; 赵爱英; 王鹏; 刘岿; 司长代; 唐慧安; 左国防; 王小芳; 刘新文; 雷新有; 吕玲玲; 李志锋; 郭峰
Original assignee: Tianshui Normal University
Current assignee: Tianshui Normal University
Priority date: 2019-02-21
Filing date: 2019-02-21
Publication date: 2021-11-26
Anticipated expiration: 2039-02-21
Also published as: CN111592257A

Abstract

The invention discloses a straw raw material pretreatment method and a device thereof of a straw water reducing agent. The method comprises the steps of carrying out preliminary crushing, cleaning, drying, secondary crushing and micro-crushing pretreatment on straw raw materials; hydrolyzing straw powder prepared by micro-crushing pretreatment, wherein the hydrolysis method comprises the following steps: adding a lubricating additive, a hydrolysis main catalytic acid and a hydrolysis auxiliary catalytic acid into the straws, wherein the solid-to-liquid ratio of the straws, the lubricating additive, the hydrolysis main catalytic acid and the hydrolysis auxiliary catalytic acid is 1000 g: 6-10 ml: 15 ml: 100 ml. The method effectively separates the cellulose, the hemicellulose and the lignin, separates the hemicellulose and the lignin which are wrapped outside the cellulose, reduces the polymerization degree of plant cell walls, and improves the hydrolysis efficiency of the straw lignocellulose; the device has the advantages of simple structure, easy operation, high straw micro-crushing and hydrolysis efficiency, low cost and easy industrialization, creates favorable conditions for the synthesis of the straw water reducing agent, and has potential industrial value and application prospect.

Description

Straw raw material pretreatment method and device of straw water reducing agent

Technical Field

The invention relates to the field of pretreatment methods and equipment for straw raw materials of straw water reducing agent precursors, in particular to a pretreatment method and a pretreatment device for straw raw materials of a straw water reducing agent.

Background

At present, few research reports of directly using biomass straws as a water reducing agent exist, and most of the research reports are that cellulose and lignin are extracted and separated from the straws, or black liquor wastewater obtained by producing paper making and ethanol from the straws is used as a raw material for modification research of the water reducing agent or compounding research with a polycarboxylic acid water reducing agent.

A study on a lignin modified water reducer, CN 101337789A, a method for preparing a water reducer by condensation modification of wheat straw alkali lignin, comprises the steps of adding wheat straw alkali lignin into water with the weight of 4.4-5.5 times of that of wheat straw alkali lignin for dissolution, adding copper sulfate with the weight of 0.6-0.9% of that of the wheat straw alkali lignin, adjusting the pH value to 10-11 by using a caustic soda solution, adding anhydrous sodium sulfite with the weight of 45-55% of that of the wheat straw alkali lignin, heating to 88-92 ℃, reacting for 4-5 hours to prepare a sulfonated product, and carrying out condensation reaction on the sulfonated product and quantitative formaldehyde under the conditions of the pH value of 11.6-12.0 and the temperature of 65-75 ℃ to prepare the water reducer. The water reducing agent prepared by the method has low water reducing rate and can only be used as the most common water reducing agent. Chinese patent CN 101759856B "preparation method of sodium lignosulfonate water reducer", takes black liquor produced by soda boiling of corncobs, corncob acid hydrolysis residues, bagasse or corn stalks as raw materials, and prepares the sodium lignosulfonate water reducer with low water content by coarse filtration, ultrafiltration membrane concentration, sulfonation and spray drying. Chinese patent CN 106698993A, "a polycarboxylate water reducing agent", utilizes waste white mud to size, heat, mix with corn stalk again, add sodium dodecyl sulfate, dry and extrude the piece after stirring, the acid leaching obtains the hydrolyzate, utilize CaO to adjust the straw hydrolyzate to pH value 6.0-7.0, the hydrolyzate that obtains is dried, oxidized, sulfonated, add to polycarboxylate water reducing agent, use ultrasonic treatment 1-2 h after stirring evenly, obtain modified polycarboxylate water reducing agent. The method has the main advantages that the papermaking waste liquid is used for preparing the polycarboxylic acid water reducing agent, waste materials can be well changed into valuable materials, and the strong base in the papermaking waste liquid is utilized to pretreat the corn straws, so that the corn straws can be better soaked in acid for hydrolysis. The essence of the method is that lignin in the straws is sulfonated and compounded with a water reducing agent. Chinese patent CN 102936110A, "a lignosulfonate-polycarboxylic acid copolymerization composite high-performance water reducing agent and a preparation method thereof", is obtained by directly synthesizing lignosulfonate, methyl allyl polyoxyethylene ether and acrylic acid under the action of ammonium persulfate and neutralizing with sodium hydroxide. The essence of the water reducing agent is a lignosulfonate modified polycarboxylic acid water reducing agent.

At present, the research of directly using biomass straws as a water reducing agent mainly has two reports: chinese patent CN 106279574A 'A polycarboxylate superplasticizer modified by straws and a preparation method thereof', the first step is straw pretreatment: crushing straws, adding dilute acid, uniformly stirring and mixing, soaking for 18-36 h, filtering, and washing the straws to be neutral by using clear water; step two, preparing the straw modified polycarboxylate superplasticizer: adding methallyl polyoxyethylene-1000, methallyl polyoxyethylene-2400, maleic anhydride, acrylamide, sodium methallyl sulfonate and straws into a four-reflux device and a constant-pressure dropping funnel, adding ammonium persulfate into the constant-pressure dropping funnel, beginning to drop initiator ammonium persulfate at a dropping speed of 2-4 drops/s, and preserving heat for 4-5 hours after dropping; and cooling to 35-45 ℃, and adjusting the pH to 6.8-7.2 to obtain the straw modified polycarboxylic acid water reducing agent. Chinese patent CN 105713164B, "an aliphatic water-reducing agent prepared from straws and a preparation method thereof", is prepared by the steps of straw acid cleaning, straw modified aliphatic water-reducing agent and the like. The method specifically comprises the following steps: pretreating straws, namely crushing corn straws or wheat straws, adding dilute acid, uniformly stirring and mixing, soaking for 18-36 h, filtering, and washing the straws to be neutral by using clear water; adding water into a reaction kettle, then adding sodium sulfite, and dissolving; adding acetone into the dissolved sodium sulfite solution, and sulfonating for 8-12 min; then adding the pretreated straws, and stirring and reacting for 20-40 min; and adding formaldehyde into the solution, and reacting at 90-95 ℃ for 1-2 h to prepare the straw modified aliphatic water reducer. The technology effectively utilizes the straw waste resources, overcomes the defect of poor retarding effect of the existing aliphatic water reducing agent, improves the application range of the aliphatic water reducing agent, and reduces the production cost.

However, the two research results are only small-scale shaking tests in laboratories, firstly, the degree and method of fine crushing are not provided for crushing the straws, but the straw crushing is only provided, secondly, excessive chloride ions and sulfate ions are brought in by the hydrolysis of the straws by using conventional dilute hydrochloric acid or dilute sulfuric acid to influence the performance of the water reducing agent, thirdly, the conception and concept of industrial tests are not provided, and a great distance is left between the research results and industrial production devices and production systems.

The water reducer prepared by directly modifying the crop straws has high pretreatment requirements on the straw raw materials, and the fine granularity and the hydrolysis effect directly influence the performance of the prepared water reducer, which is also a key problem that needs to be considered in the industrial production of the straw-based water reducer, otherwise, the water reducer cannot play a role in developing and utilizing novel water reducers. However, the reports of the method and the device for the micro-crushing and hydrolysis pretreatment of the straw raw material for directly preparing the water reducing agent by using the crop straws are not seen yet.

Disclosure of Invention

The invention aims to provide a method for pretreating straw raw materials of a straw water reducing agent, which effectively separates cellulose, hemicellulose and lignin, separates the hemicellulose and the lignin which are wrapped outside the cellulose, reduces the degree of polymerization of plant cell walls, and improves the hydrolysis efficiency of straw lignocellulose; the invention also aims to provide a device for preparing the straw water reducing agent by pretreating straw raw materials.

In order to achieve the purpose, the straw raw material pretreatment method of the straw water reducing agent comprises the following specific steps:

s1, carrying out micro-crushing pretreatment on straw raw materials:

the method comprises the following steps of (1) naturally drying a raw material straw bundle, and then carrying out primary crushing, cleaning, drying, secondary crushing and micro-crushing pretreatment; the primary crushing is to crush the raw material straws into straw sections of 1-3 cm; the cleaning is to remove silt and impurities in the raw material straws subjected to the primary crushing step by washing; drying the cleaned raw material straws until the water content is below 10 percent, wherein the water content is calculated by mass percent; the secondary crushing is to crush the dried raw material straws into straw sections with the diameter of less than 10 mm; the micro-crushing pretreatment is to crush the raw material straws subjected to the secondary crushing step to be less than 400 mu m;

s2, straw powder hydrolysis pretreatment:

hydrolyzing the straw powder prepared by the S1 micro-crushing pretreatment, wherein the hydrolysis method comprises the following steps: adding a lubricating additive, a hydrolysis main catalytic acid and a hydrolysis auxiliary catalytic acid into the straws, wherein the solid-to-liquid ratio of the straws, the lubricating additive, the hydrolysis main catalytic acid and the hydrolysis auxiliary catalytic acid is 1000 g: 6-10 ml: 15 ml: 100 ml.

The invention relates to a device for pretreating straw raw materials of a straw water reducing agent, which comprises an equipment support, and a crushing member, a cleaning member, a drying member and a storage tank which are arranged on the equipment support, wherein the crushing member comprises a straw primary crushing module, a secondary crushing module and horizontal ball mill micro crushing, and the straw primary crushing module arranged on the equipment support is sequentially connected with a 1# straw coarse material conveying air duct, a cleaning module, a pre-drying module, a coarse material conveying belt, a spiral dryer, a cyclone separator, a material collecting bin, a 2# straw dry coarse material conveying air duct, a secondary crushing module, a horizontal ball mill micro crushing module, a 1# straw conveying belt, a buffer storage tank, a 1# material collecting bin weighing module, a 2# powder conveying belt, a spiral extrusion hydrolysis unit, a 2# material collecting bin weighing module and a storage tank with a cart; a heater is arranged outside the screw extrusion hydrolysis unit, and a batching storage tank group is arranged above the screw extrusion hydrolysis unit; an opening is arranged above the cyclone separator, and the opening of the cyclone separator is connected with the pre-drying module through a pipeline.

According to the device for pretreating straw raw materials of the straw water reducing agent, a feed inlet is arranged above the straw primary crushing module, a powder collecting port is arranged below the straw primary crushing module, a primary crushing raw material straw discharge port is arranged below the side wall of the straw primary crushing module, the powder collecting port is connected with a powder collecting box, the primary crushing raw material straw discharge port is connected with the feed inlet formed above the cleaning module through a 1# straw coarse material conveying air duct, and a discharge port is formed in the side wall of the cleaning module and connected with a discharge port formed in the side wall of the pre-drying module; the bottom of the pre-drying module is provided with a pre-drying raw material straw discharge port and a hot air inlet, the pre-drying raw material straw discharge port is connected with a feed port arranged in the middle of the side wall of the spiral dryer through a coarse material conveying belt, the top of the spiral dryer is provided with a hot air outlet, the lower end of the spiral dryer is provided with a hot air inlet, the hot air inlet is connected with a fan, the hot air outlet of the spiral dryer is connected with a feed port arranged in the middle of the side wall of the cyclone separator, an opening is arranged above the cyclone separator, the lower part of the cyclone separator is provided with a separation discharge port, the opening of the cyclone separator is connected with the hot air inlet below the pre-drying module through a pipeline, the separation discharge port is connected with a feed port arranged at the top of the collecting bin through a pipeline, the bottom of the separation discharge port is provided with a collecting bin discharge port, and the collecting bin discharge port is connected with a crushing cavity feed port at the top of the secondary crushing module through a No. 2 straw dry coarse material conveying duct, the bottom end of the secondary crushing module is provided with a crushed raw material discharge port, the crushed raw material discharge port is connected with a feed port of the horizontal ball mill micro crushing module, the discharge port of the horizontal ball mill micro crushing module is connected with a feed port arranged at the top of a buffer storage tank through a No. 1 powder conveying belt, the discharge port arranged at the bottom of the buffer storage tank is connected with a feed port arranged at the top of a No. 1 aggregate bin weighing module, the discharge port arranged at the bottom of the No. 1 aggregate bin weighing module is connected with the feed end of a spiral extrusion hydrolysis unit through a No. 2 powder conveying belt, the discharge end of the spiral extrusion hydrolysis unit is connected with the feed port of the No. 2 aggregate bin weighing module, and the discharge port of the No. 2 aggregate bin weighing module is connected with a storage tank of a cart; the screw extrusion hydrolysis unit comprises four 1# screw extruders, 2# screw extruders, 3# screw extruders and 4# screw extruders which are connected in series, heating pipes connected with heaters are respectively arranged on the 1# screw extruders, the 2# screw extruders, the 3# screw extruders and the 4# screw extruders, a batching storage tank group is arranged above the screw extrusion hydrolysis unit and consists of a 1# batching storage tank, a 2# batching storage tank and a 3# batching storage tank, and the batching liquid in the 1# batching storage tank, the 2# batching storage tank and the 3# batching storage tank is respectively a lubricating additive, a hydrolysis main catalytic acid and a hydrolysis auxiliary catalytic acid; an opening is arranged above the cyclone separator, and the opening of the cyclone separator is connected with the opening below the pre-drying module through a pipeline.

The use method of the straw raw material pretreatment device of the straw water reducing agent comprises the following implementation steps:

a. weighing the straw powder prepared by micro-crushing pretreatment through a 1# aggregate bin weighing device, and feeding the straw powder into a 1# screw extruder, a 2# screw extruder, a 3# screw extruder and a 4# screw extruder for hydrolysis;

b. in the hydrolysis process, firstly, water with the temperature of 50-60 ℃ in a heater is started to heat the machine body through a coil heat exchanger, and then the prepared liquid in the material preparation storage tank group is added simultaneously;

c. when the materials enter a No. 1 screw extruder, starting a peristaltic pump or a liquid level valve to control and slowly add the prepared liquid of a No. 1 material preparing storage tank, a No. 2 material preparing storage tank and a No. 3 material storing tank in the material preparing storage tank group into a screw extrusion hydrolysis unit;

d, discharging the material from the No. 1 screw extruder into the No. 2 screw extruder for hydrolysis;

e. opening a new round of straw materials to enter a No. 1 screw extruder, adding the prepared liquid in a No. 1 preparing storage tank, a No. 2 preparing storage tank and a No. 3 preparing storage tank in a preparing storage tank group, and performing heat preservation, mixing materials and preliminary hydrolysis; each ingredient storage tank of the ingredient storage tank group is provided with a communicated liquid level meter and a liquid level graduated scale;

f, discharging the further hydrolyzed materials from the No. 2 screw extruder into the No. 3 screw extruder for reinforced hydrolysis, and discharging the materials from the No. 1 screw extruder into the No. 2 screw extruder for further hydrolysis;

g, performing 'intermittent continuous propulsion' on a hydrolyzed material of a 3# spiral extruder, entering a 4# spiral extruder for deep hydrolysis, a material of a 2# spiral extruder, a material of a 3# spiral extruder, a material of a 1# spiral extruder, a material of a 2# spiral extruder and a new material of a 1# spiral extruder;

h.4# screw extruder material blowing after degree of depth hydrolysis gets into the storage tank of taking the shallow after reaching specified weight after weighing through 2# aggregate storehouse weighing device and transports, and the storage tank of next area shallow gets into work.

The straw is one or combination of wheat straw and corn straw.

The hot air used by the pre-drying module is waste heat air exhausted by the spiral dryer, and the temperature of the pre-dried air is 50-150 ℃.

The ball mill of the horizontal ball mill micro-crushing module is a horizontal ball mill, and the ball milling parameters are as follows: the particle size of the straw raw material is less than 10mm, the rotating speed is 10-50 r/min, the loading amount of the straw raw material is 10-15 Kg, the diameter of copper balls is 10-15 mm, the ball milling time is 10-15 min, and the particle size of discharged materials is 75-400 mu m.

The lubricating additive is one or a combination of stearic acid and oleic acid, and the solid-to-solid ratio of the straw to the lubricating additive is 1000g to (6-10) ml; the solid acid ratio of the straw to the hydrolysis main catalytic acid is 1000g to (10-30) ml; the hydrolysis promoting acid preparation solution is dilute sulfuric acid or dilute hydrochloric acid with the mass concentration of 30g/L, and the solid-acid ratio of straw to hydrolysis promoting dilute acid is 1000g to 100 ml;

the main hydrolysis catalytic acid solution is one or a combination of more of monobasic (carboxylic) acid, dibasic (carboxylic) acid or polybasic (carboxylic) acid;

the monobasic (carboxylic) acid is one or a combination of hypophosphorous acid, formic acid, acetic acid, benzoic acid, acrylic acid, methacrylic acid, stearic acid and oleic acid;

the dibasic (carboxylic) acid is one or more of phosphorous acid, oxalic acid (oxalic acid), terephthalic acid, itaconic acid, maleic acid and maleic anhydride;

the polybasic (carboxylic) acid is one or two of phosphoric acid and citric acid.

The principle requires that the addition amount of acid is reduced along with the characteristic that H + is released by monobasic acid, dibasic acid and polybasic acid, and when the monobasic (carboxylic) acid is added, the solid acid ratio of the straw to the main catalytic acid is 1000g to 30 ml; when adding binary (carboxylic) acid, the solid acid ratio of straw to main catalytic acid is 1000g to 20 ml; when ternary (carboxylic) acid is added, the solid-to-solid ratio of the straw to the lubricating additive is 1000g to (6-10) ml; the solid acid ratio of the straw to the main catalytic acid is 1000g to 15 ml; the solid acid ratio of the straw to the hydrolysis promoting diluted acid is 1000g to 100 ml.

The screw extruder of the screw extrusion hydrolysis unit is a single/double screw extruder, the rotating speed of a motor is controlled to be 50-80 r/min, the certain hydrolysis time of each batch of materials in a single screw extruder is 5min, and the total hydrolysis time of the hydrolysis unit consisting of 4 screw extruders is 20min correspondingly.

1# aggregate storehouse weighing device and 2# aggregate storehouse weighing device are the suspension type structure, can weigh the accuracy of straw powder, and the quality of hydrolysising is ensured to the accurate input of the powder of being convenient for.

The heater heats materials in the shell through a coil heat exchanger wound outside the shell of the screw extrusion hydrolysis unit, and the flow direction of a heat medium is opposite to the direction of the materials in the screw extrusion hydrolysis unit, so that countercurrent heat exchange is realized.

The hydrolysis promoting acid preparation solution is dilute sulfuric acid or dilute hydrochloric acid with the mass concentration of 30g/L, and the solid-acid ratio of the straw to the hydrolysis promoting dilute acid is 1000g to 100 ml.

The screw extruder is a single/double screw extruder, and the rotating speed of a motor is controlled to be 50-80 r/min.

The certain hydrolysis time is 5min for each batch of materials in a single screw extruder due to continuous operation, and the total hydrolysis time of a hydrolysis unit consisting of 4 screw extruders is 20min correspondingly.

Each ingredient storage tank of the ingredient storage tank group is provided with a simple communicated liquid level meter and a liquid level graduated scale, so that the control of respective liquid preparation and the step-by-step feeding are facilitated.

The heater heats materials in the shell through a coil heat exchanger wound outside the shell of the screw extruder, and the flow direction of a heat medium is opposite to the direction of the materials in the screw extruder and is in countercurrent heat exchange.

The material collecting bin weighing module is of a suspension type structure, can accurately weigh straw powder, is convenient for accurate feeding of the powder, and ensures hydrolysis quality.

The straw raw material pretreatment method and the device of the straw water reducing agent have the beneficial effects that:

(1) the use method of the device can clean the raw materials conveniently, and prevent the straw from being crushed too thin to cause great loss of organic components in straw powder and difficulty in subsequent liquid-solid separation in the cleaning process;

(2) the cleaned straw sections are subjected to a drying process of a pre-drying module and a spiral dryer, hot air used by the pre-drying module comes from waste hot air exhausted by the spiral dryer, so that the full utilization of energy is realized, the drying efficiency is high, and the level that the moisture content of the straw is below 10% (calculated by mass percent) is easily reached;

(3) by utilizing the characteristics of the ball mill, straw segments of about 1-3 cm are easily finely ground into straw powder of 75-400 mu m, so that the subsequent hydrolysis and the preparation of a water reducing agent are facilitated; after ball milling treatment, lignin components in the straws are basically damaged, the cellulose is easier to hydrolyze due to the degradation of lignin, the crystallinity of the straws is reduced after long-time ball milling, and the ratio of amorphous cellulose and the reaction active area are increased, so that the cellulose of the straws is easier to permeate by weak acid and is easier to hydrolyze;

(4) the straw raw material is degraded by a combined organic/inorganic acid mixed acid pretreatment method by spirally extruding by a semi-dry method (the water content in the straw reaches about 10 percent, and liquid-phase hydrolysis catalytic acid is added), and the straw raw material has the advantages of small corrosion to equipment, high degradation rate, simple reaction process, mild reaction conditions, low cost and easy industrial application;

(5) the organic acid main catalyst used by the straw raw material pretreated by combining the semidry method screw extrusion with the organic/inorganic acid mixed acid can be used as an unsaturated micromolecule monomer required by the subsequent preparation of the water reducing agent, particularly the unsaturated carboxylic acid micromolecule monomer can actively participate in the subsequent synthesis of the polycarboxylic acid water reducing agent, and the product performance is not influenced by slight excess;

(6) during the pretreatment of the straw lignocellulose raw material by combining the semidry method screw extrusion with the organic/inorganic acid mixed acid, not only are the straw lignin, hemicellulose and cellulose further separated, but also the main products of straw hydrolysis are mannose, glucose, galactose, xylose and arabinose. Meanwhile, various complex reactions are generated, and some small molecular compounds are generated, for example, hydrolysis sugar, organic acid, furfural, 5-hydroxymethyl furfural, phenolic compounds and the like are usually generated in a pretreated material liquid phase; hemicellulose can concomitantly produce compounds such as acetic acid, arabinose, xylose, mannose, galactose and glucose; cellulose can produce glucose; lignin can produce phenolic compounds; extractives and ashes, etc. can produce wood resins, etc. Meanwhile, part of arabinose and xylose are further hydrolyzed and converted into furfural, mannose and galactose, glucose is further hydrolyzed and converted into hydroxymethyl furfural, furfural is further hydrolyzed and converted into formic acid, and hydroxymethyl furfural is further hydrolyzed and converted into formic acid and levulinic acid. The generated small molecular compounds can be used as small molecular monomers required for synthesizing the water reducing agent, have respective characteristics, such as the retarding and water reducing effects of monosaccharide, polysaccharide and carboxylic acid, the slump retaining effect of furfural and phenolic compounds and the like, and the generated organic weak acids such as formic acid, acetic acid, levulinic acid and the like provide H < + > which has the promotion effect on hydrolysis, accelerate the hydrolysis process, remarkably promote the degradation of cellulose and lignin in the straws, have higher saccharification rate and mild reaction conditions, are simple in reaction process, basically free of pollution and easy for industrial production.

(7) The screw extruder has the characteristics of functions of horizontal plug flow, high-speed extrusion and strong shearing, and the long-time functions of high-speed extrusion and strong shearing further reduce the crystallinity of the straws, and further increase the ratio of amorphous cellulose and the reaction active area, so that the cellulose of the straws is easier to permeate by weak acid and is easier to hydrolyze, the hydrolysis of the straws is more efficient and easy to control, and meanwhile, because the shell of the screw extruder body is provided with the coil heat exchanger, the temperature is convenient to rise, the reaction is accelerated, and the operation is easy;

(8) the screw extruder set is connected in series, so that the hydrolysis time in the screw extruder is prolonged, the hydrolysis efficiency is improved, and the intermittent continuous operation process is easy to realize.

(9) The batching storage tank group is provided with a simple communicated liquid level meter and a liquid level graduated scale, so that the feeding amount of liquid materials can be conveniently controlled; the suspension type weighing material collecting bin module can accurately weigh straw powder, is convenient for accurate feeding of the powder, and ensures hydrolysis quality.

(10) The production system has the advantages of continuous and compact process, simple equipment, easy operation, high straw micro-crushing and hydrolysis efficiency, low cost and easy industrialization, creates favorable conditions for the synthesis of the straw-based water reducing agent, and has potential industrial value and application prospect.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present invention;

in the figure: 1-equipment support; 2-a straw primary crushing module; 3-bundling the raw material straws; 4-1# straw coarse material conveying air duct; 5-a cleaning module; 6-a pre-drying module; 7-coarse material conveyer belt; 8-a spiral dryer; 9-a cyclone separator; 10-a material collecting bin; a No. 11-2 straw dry coarse material conveying air duct; 12-a secondary crushing module; 13-horizontal ball mill micro-crushing module; 14-1# powder conveyer belt; a 15-1# aggregate bin weighing module; 16-a buffer tank; 17-2# powder conveyer belt; 18-ingredient storage tank group; 19-a screw extrusion hydrolysis unit; 20-a heater; a 21-2# aggregate bin weighing module; 22-storage tank with cart.

Detailed Description

The straw raw materials used in the following examples are wheat straw and corn straw harvested in the Tianshui area of Gansu province in 2017, cotton straw harvested in Xinjiang, the harvested straws are air-dried, the dried straws (including roots, stems and leaves) are crushed and ground to obtain fine powder, and the fine powder is subjected to composition content analysis and detection of lignin, hemicellulose, cellulose and the like, and the analysis results are shown in the following table 1 (in terms of dry substances, mass fraction%);

TABLE 1 analysis and detection data of straw composition content

(dry basis mass%)

Raw material components%	Cellulose, process for producing the same, and process for producing the same	Hemicellulose	Lignin	Water content ratio	Ash content
						Wheat straw	36.7	27	15.4	5.46	13.1
Corn stalk	38.1	21.1	18.0	6.77	11.5

Example 1

The invention relates to a straw raw material pretreatment method of a straw water reducing agent, which comprises the following specific steps as shown in figure 1:

s1, carrying out micro-crushing pretreatment on straw raw materials:

the method comprises the steps of naturally air-drying a raw material straw bundle 3, crushing the raw material straw bundle into straw sections of 1-3 cm through a straw primary crushing module 2, feeding the discharged materials into a cleaning module 5 through a 1# straw coarse material conveying air duct 4, cleaning impurities such as silt and sand in the primary crushed straw sections, feeding the cleaned straw sections into a pre-drying module 6 through a discharge port of the cleaning module 5 for primary drying, feeding the straw sections into a spiral dryer 8 through a coarse material conveying belt 7 for further drying, blowing the dried straw sections out of the upper part of the spiral dryer 8, feeding the dried straw sections into a cyclone separator 9 connected with a discharge port of the spiral dryer 8 for gas-solid separation, feeding the obtained straw section solid materials into a material collecting bin 10, feeding the straw sections into a secondary crushing module 12 through a 2# straw coarse material conveying air duct 11, crushing the straw sections into straw sections below 10mm, feeding the discharged materials into a horizontal ball mill micro-crushing module 13 for ball milling, discharging the crushed raw materials with the particle size of below 400 mu m, stopping ball milling, and discharging;

the ball mill in the horizontal ball mill micro-crushing module 13 is a planetary horizontal ball mill, the grain diameter of the straw raw material is less than 10mm, the rotating speed is 10-50 r/min, the raw material loading amount is 15Kg, the ball loading amount is 1500, 1000 copper balls with the diameter of 10mm and 500 copper balls with the diameter of 15mm are filled, the ball milling time is 15min, and the grain diameter of the obtained micro-crushed raw material is 75-400 mu m;

s2, straw powder hydrolysis pretreatment:

s1, feeding the raw material in the horizontal ball mill micro-crushing module 13 into a buffer storage tank 16 through a 1# powder conveyer belt 14, feeding the raw material in the buffer storage tank 16 into a 1# aggregate bin weighing device 15, weighing 15000g of the raw material in the 1# aggregate bin weighing device 15, and feeding the raw material into a zigzag spiral extrusion hydrolysis unit 19 formed by connecting 1#, 2#, 3# and 4# spiral extruders in series for hydrolysis; in the hydrolysis process, firstly, a heater 20 is started, water with the temperature of 50-60 ℃ is heated by a coil heat exchanger, then the prepared liquid in a prepared material storage tank group 18 is added simultaneously, the materials enter a 1# screw extruder, a peristaltic pump or a liquid level valve is started to control the prepared liquid in a 1# prepared material storage tank, a 2# prepared material storage tank and a 3# material storage tank in the prepared material storage tank group 18 to be slowly added into a screw extrusion hydrolysis unit 19 simultaneously, the prepared liquid in the 1# prepared material storage tank, the 2# prepared material storage tank and the 3# prepared liquid storage tank are respectively a lubricating additive, a hydrolysis main catalytic acid and a hydrolysis auxiliary catalytic acid with certain concentration dosage, the materials are discharged into the 2# screw extruder for further hydrolysis after heat preservation and primary hydrolysis for a certain time, a new round of straw materials are started to enter the 1# screw extruder, the prepared liquid in the 1# prepared material storage tanks, the 2# prepared liquid in the 3# prepared material storage tank group 18 is added, the materials are heat preserved and primarily hydrolyzed, in the process, the 2# screw extruder discharges materials which are further hydrolyzed and enters the 3# screw extruder for reinforced hydrolysis, and the 1# screw extruder discharges materials which enter the 2# screw extruder for further hydrolysis; the subsequent process is that the 3# screw extruder hydrolyzes the material and enters the 4# screw extruder for deep hydrolysis, the 2# screw extruder enters the 3# screw extruder, the 1# screw extruder enters the 2# screw extruder, the new material enters the 1# screw extruder, the process is intermittent continuous, the material after the 4# screw extruder deeply hydrolyzes is discharged, the material after weighing by the 2# aggregate bin weighing device 21 enters the material storage tank 22 with the cart to reach the specified weight and then is transported away, and the next material storage tank 22 with the cart enters the work;

the lubricating additive is oleic acid, and the solid-to-solid ratio of the straw to the oleic acid is 1000g to 10 ml;

the main hydrolysis catalytic acid is acrylic acid represented by monobasic (carboxylic) acid, and the solid-acid ratio of straw to acrylic acid is 1000 g: 30 ml;

the hydrolysis catalysis-assisting acid is dilute sulfuric acid with the mass concentration of 30g/L, and the solid acid ratio of the straw to the dilute sulfuric acid is 1000 g: 100 ml;

the screw extruder is a single screw extruder, and the rotating speed of the single screw extruder is controlled to be 50 r/min;

the hydrolysis time of the single screw extruder is 2.5min, and the total hydrolysis time of a hydrolysis unit consisting of 4 corresponding screw extruders is 10min respectively.

Example 2

The invention relates to a straw raw material micro-crushing-hydrolysis pretreatment method of a straw-based water reducing agent, which comprises the following specific steps of:

s1: the straw raw material is pretreated by micro-crushing, and the specific process is completely the same as the S1 process in the embodiment 1;

s2: the hydrolysis pretreatment of the straw powder is completely the same as the S2 process of the embodiment 1, and the difference is that the added hydrolysis catalytic acid is different, which is specifically shown in the following steps:

the lubricating additive is stearic acid, and the solid-to-solid ratio of the straw to the stearic acid is 1000g to 10 ml;

the main hydrolysis catalytic acid is binary (carboxylic) acid represented by itaconic acid, and the solid acid ratio of straw to the itaconic acid is 1000 g: 20 ml;

the hydrolysis catalysis-assisting acid is dilute hydrochloric acid with the mass concentration of 30g/L, and the solid acid ratio of the straw to the dilute hydrochloric acid is 1000 g: 100 ml.

Example 3

the lubricating additive is a mixture of 1/2 stearic acid and oleic acid, and the solid-to-solid ratio of the straw to the lubricating additive is 1000g to 10 ml.

The main hydrolysis catalytic acid is polybasic (carboxylic) acid represented by citric acid, and the solid acid ratio of straw to citric acid is 1000 g: 15 ml;

the hydrolysis catalysis-assisting acid is a mixed acid of 1/2 diluted sulfuric acid and diluted hydrochloric acid with the mass concentration of 30g/L, and the solid acid ratio of straw to the catalysis-assisting acid is 1000 g: 100 ml.

Comparative example 1

A conventional straw raw material crushing-conventional inorganic acid hydrolysis pretreatment method comprises the following specific steps:

s1: the straw raw material crushing pretreatment comprises the following specific steps:

crushing, cleaning and drying the straw raw material; after a certain amount of raw material straw bundles are naturally air-dried, crushing the raw material straw bundles into straw sections of 1-3 cm by a conventional agricultural straw crusher; then impurities such as mud and sand in the waste water are cleaned through a cleaning module 5; and then the straw is dried for the second time through a pre-drying module 6 and a spiral dryer 8) respectively to ensure that the water content of the straw is below 10 percent (calculated by mass percentage).

S2: the straw powder hydrolysis pretreatment comprises the following specific steps:

15000g of straw powder prepared by S1 pretreatment is weighed and sent into a conventional degradation device-heating reaction kettle for hydrolysis. In the hydrolysis process, dilute sulfuric acid or dilute hydrochloric acid is used as catalytic acid for hydrolysis, and a dilute acid soaking stirrer is used for stirring. Firstly, 60L of dilute sulfuric acid with the mass concentration of 10g/L is added, the quantity of H + provided by catalytic acid is basically the same as that provided by the

embodiments

1, 2 and 3 in theory, and hydrolysis is carried out at the hydrolysis temperature of 50 ℃ for 20min, 60min, 120min and 180min respectively.

Comparative example 2

The invention relates to a conventional straw raw material crushing-organic acid/inorganic acid mixed hydrolysis pretreatment method and a device thereof, which comprises the following steps:

s1: the straw raw material is subjected to crushing pretreatment, the specific process is the same as the S1 process of comparative example 1, and the prepared straw powder has the particle size of 1-3 cm.

S2: the hydrolysis pretreatment of straw powder, the specific process is the same as the S2 process of example 1, and the hydrolysis is carried out by taking organic acid/inorganic acid mixed acid as catalytic acid in a screw extruder hydrolysis unit.

Comparative example 3

The invention relates to a pretreatment method and a device for ball milling and micro crushing of straw raw materials and conventional inorganic acid hydrolysis, which comprises the following steps:

s1: the straw raw material is subjected to crushing pretreatment, the specific process is the same as the S1 process in the embodiment 1, and finally, the particle size of the straw powder prepared by ball milling is 75-400 mu m.

S2: the straw powder hydrolysis pretreatment is carried out, the specific process is the same as the S2 process of comparative example 1, and inorganic acid sulfuric acid is used as catalytic acid for hydrolysis in a heating reaction kettle.

Determination of sugar content in hydrolysate

The hydrolysis effect is based on the total sugar content (including mannose, glucose, galactose, xylose and arabinose) of the hydrolysate. The examples and comparative examples comprehensively consider the influence of the straw material granularity, the type and amount of catalytic acid, the hydrolysis equipment characteristics and the like on the straw hydrolysis effect in the straw pretreatment process, and make evaluations on the hydrolysis method and equipment of the process.

Taking 1g of the hydrolyzed straw, adding 60ml of purified water for dissolving, stirring for 5min, taking out the slurry, separating on a centrifugal machine, centrifuging at the rotating speed of 500r/min for 5min, and separating the supernatant for determining the content of reducing sugar and monosaccharide components. The hydrolysis effect of the straw lignocellulose is evaluated by measuring the content of soluble sugar by a 3, 5-dinitrosalicylic acid method. The remaining precipitate is unhydrolyzed straw lignocellulose and insoluble materials thereof, and is continuously used for the subsequent oxidative sulfonation modification of the straw lignocellulose and the application in the water reducing agent.

The hydrolysis effects of examples 1 to 3 and comparative examples 1 to 3 are shown in Table 2.

Table 2 influence of straw powder particle size, hydrolysis catalytic acid, hydrolysis time, hydrolysis method on hydrolysis effect (sugar content):

as can be seen from table 2: the grain size of the straw, the type of hydrolysis catalytic acid, the hydrolysis time and the treatment method all have influence on the total sugar content of the hydrolysate. The hydrolysis effects of examples 1 to 3 were superior to those of comparative examples 1 to 3.

The smaller the granularity of the straw is, the more beneficial the straw hydrolysis is, the higher the total sugar content is, the shorter the hydrolysis time is, and the better the hydrolysis effect is. This is due to: the straw is treated by ball milling, so that the size of the cellulose material can be obviously reduced, the ordered structure of cellulose crystals is further destroyed, the crystallinity of cellulose is reduced, the reaction surface is enlarged, the accessibility of the cellulose to chemical reagents is improved, the cellulose is more easily degraded by catalytic acid, and the conversion of carbohydrate polymers to sugar is promoted, therefore, the smaller the particle size of the straw is, the more beneficial the hydrolysis of the straw is.

As can be seen from Table 2, the effect of the combination of the organic acid and the inorganic acid providing the same H + and the use of the inorganic acid alone on the degradation of the straws are not greatly influenced, the inorganic acid degradation is dominant at the beginning, and the degradation of the organic acid and the inorganic acid is gradually dominant along with the extension of the degradation time. This may be due to: the organic acid and the inorganic acid are combined to be used as straw hydrolysis catalytic acid, the speed of releasing H + by the organic acid hydrolysis is lower than the speed of releasing H + by the inorganic acid hydrolysis, the inorganic acid is dominant in the early stage of hydrolysis, the concentration of the inorganic acid is lower and lower along with the progress of hydrolysis, the speed of releasing H + is reduced, the organic acid has advantages on the hydrolysis, and under the condition of theoretically releasing the same H +, the result that the straw degradation effect is not influenced greatly by the organic acid and the inorganic acid only finally appears.

As can be seen from Table 2, the effect of hydrolysis in the screw extruder is far superior to that in the conventional reaction vessel. Under almost the same optimal hydrolysis effect condition, the hydrolysis time of hydrolysis in the screw extruder is only 1/8-1/9 of that of hydrolysis in a conventional reaction kettle. This is due to the strong mixing capability of screw extruders, which are typical "three pass one reverse" process intensification devices. After high-speed extrusion and strong shearing of the screw extruder, the particle size of the straw is further reduced, and in the extrusion process, great friction force is generated between the material and screw blades and between the material and the material, so that the material is crushed, cell walls are completely broken, lignin and cellulose are further separated, micropores of the lignocellulose are increased, the specific surface area is increased, and the accessibility of chemical reagents is further improved. The mechanical heat energy generated in the process of screw extrusion can raise the temperature of the material and accelerate the hydrolysis reaction. As the screw extrusion hydrolysis proceeds, the degraded lignocellulose generates a plurality of active sites which can be penetrated and decomposed by the solution continuously, the accessibility of the chemical agent is increased, and the degradation rate is increased. The synergistic effect of the screw extrusion and the organic acid combined inorganic acid hydrolysis improves the hydrolysis efficiency of the straw and greatly shortens the hydrolysis time.

As can be seen from table 2: for straw micro powder with the particle size of 75-400 mu m, the total sugar content of the hydrolysate tends to increase and decrease along with the extension of the hydrolysis time, and the hydrolysis time is 20min, which is a maximum point. Certainly, the hydrolysis process of 1-3 cm and 2-10 mm straws can also have the phenomenon along with the prolonging of time, and only the time points are different. This is mainly due to: the extension of the screw extrusion hydrolysis time is detrimental to the degradation of lignocellulose, since over time some of the sugars are further converted to other products, resulting in a decrease in sugar content.

The organic acid main catalyst selected for straw hydrolysis can be used as a small molecular monomer required for the subsequent preparation of the water reducing agent, particularly, the unsaturated carboxylic acid monomer can actively participate in the subsequent synthesis of the polycarboxylic acid water reducing agent, and the product performance is not influenced even if the unsaturated carboxylic acid monomer is slightly excessive. And the method reduces and avoids the adverse effects that the inorganic acid hydrochloric acid or sulfuric acid is taken as hydrolysis acid to bring excessive chloride ions and sulfate ions, and the straw-based water reducing agent synthesized subsequently has corrosivity and the like in the application of reinforced concrete.

The corn straw, the cotton straw and the oil straw are used as raw materials, and the similar effects are achieved.

Claims

1. A straw raw material pretreatment method of a straw water reducing agent is characterized by comprising the following steps: the specific process is as follows:

s1, carrying out micro-crushing pretreatment on straw raw materials:

s2, straw powder hydrolysis pretreatment:

hydrolyzing the straw powder prepared by the S1 micro-crushing pretreatment, wherein the hydrolysis method comprises the following steps: adding a lubricating additive, a main hydrolysis catalytic acid and a hydrolysis co-catalytic acid into the straws, wherein the solid-to-liquid ratio of the straws, the lubricating additive, the main hydrolysis catalytic acid and the hydrolysis co-catalytic acid is 1000 g: 6-10 ml: 15 ml: 100 ml;

the lubricating additive is one or a combination of stearic acid and oleic acid;

the main hydrolysis catalytic acid is one or a combination of more of monocarboxylic acid, dicarboxylic acid or polycarboxylic acid;

the hydrolysis catalysis-assisting acid is dilute sulfuric acid or dilute hydrochloric acid with the mass concentration of 30 g/L.

2. The device of claim 1, which comprises an equipment support (1), and a crushing member, a cleaning member, a drying member and a storage tank which are arranged on the equipment support (1), and is characterized in that: the grinding component comprises a straw primary crushing module (2), a secondary crushing module (12) and a horizontal ball mill micro crushing module (13), wherein the straw primary crushing module (2) arranged on the equipment support (1) is sequentially connected with a 1# straw coarse material conveying air duct (4), a cleaning module (5), a pre-drying module (6), a coarse material conveying belt (7), a spiral dryer (8), a cyclone separator (9), a material collecting bin (10), a 2# straw dry coarse material conveying air duct (11), the secondary crushing module (12), the horizontal ball mill micro crushing module (13), a 1# powder conveying belt (14), a buffer storage tank (16), a 1# material collecting bin weighing module (15), a 2# powder conveying belt (17), a spiral extrusion hydrolysis unit (19), a 2# material collecting bin weighing module (21) and a storage tank (22) with a cart; a heater (20) is arranged outside the screw extrusion hydrolysis unit (19), and a batching storage tank group (18) is arranged above the screw extrusion hydrolysis unit (19); an opening is arranged above the cyclone separator (9), and the opening of the cyclone separator (9) is connected with the pre-drying module (6) through a pipeline.

3. The device for pretreating straw raw materials of a straw water reducing agent according to claim 2, wherein: a feeding hole is formed above the straw primary crushing module (2), a powder collecting hole is formed below the straw primary crushing module, a primary crushing raw material straw discharging hole is formed below the side wall of the straw primary crushing module, the powder collecting hole is connected with a powder collecting box, the primary crushing raw material straw discharging hole is connected with the feeding hole formed above the cleaning module (5) through a 1# straw coarse material conveying air duct (4), and the discharging hole formed in the side wall of the cleaning module (5) is connected with the discharging hole formed in the side wall of the pre-drying module (6); predrying raw material straw discharge gate and hot air inlet have been seted up to the bottom of predrying module (6), predrying raw material straw discharge gate passes through coarse fodder conveyer belt (7) and connects the feed inlet that spiral dryer (8) lateral wall middle part was seted up, hot air outlet has been seted up at the top of spiral dryer (8), and hot air inlet has been seted up to its lower extreme, hot air inlet connection fan, the hot air outlet of spiral dryer (8) connects the feed inlet that cyclone (9) lateral wall middle part was seted up, and the top of cyclone (9) is provided with the opening, and the separation discharge gate has been seted up to its lower part, the opening of cyclone (9) passes through the hot air inlet connection of pipeline with predrying module (6) below, and the separation discharge gate passes through the feed inlet that pipe connection storehouse (10) top was seted up, and the storehouse discharge gate has been seted up to its bottom, and the storehouse discharge gate passes through 2# straw dry coarse fodder conveyer duct (11) and connects secondary crushing module (12) A crushing cavity feeding hole at the top end, a crushed raw material discharging hole is formed in the bottom end of the secondary crushing module (12), the crushed raw material discharging hole is connected with a feeding hole of the horizontal ball mill micro crushing module (13), the discharging hole of the horizontal ball mill micro crushing module (13) is connected with a feeding hole formed in the top of a buffer storage tank (16) through a 1# powder conveying belt (14), the discharging hole formed in the bottom of the buffer storage tank (16) is connected with a feeding hole formed in the top of a 1# aggregate bin weighing module (15), the discharging hole formed in the bottom of the 1# aggregate bin weighing module (15) is connected with the feeding end of a spiral extrusion hydrolysis unit (19) through a 2# powder conveying belt (17), the discharging end of the spiral extrusion hydrolysis unit (19) is connected with the feeding hole of the 2# aggregate bin weighing module (21), and the discharging hole of the 2# aggregate bin weighing module (21) is connected with a storage tank (22) of a cart; screw extrusion hydrolysis unit (19) comprises four 1# screw extruder, 2# screw extruder, 3# screw extruder, 4# screw extruder of establishing ties, be provided with the heating pipe of being connected with heater (20) on 1# screw extruder, 2# screw extruder, 3# screw extruder, the 4# screw extruder respectively, screw extrusion hydrolysis unit (19) top is provided with batching storage tank group (18), batching storage tank group (18) comprises 1# batching storage tank, 2# batching storage tank and 3# material storage tank, and the joining in marriage liquid in 1# batching storage tank, 2# batching storage tank, the 3# batching storage tank is lubricating additive, hydrolysis main catalytic acid and hydrolysis cocatalyst acid respectively.

4. The use method of the straw raw material pretreatment device for the straw water reducing agent according to claim 3, is characterized in that:

a. weighing the straw powder prepared by micro-crushing pretreatment through a 1# aggregate bin weighing module (15), and feeding the straw powder into a 1# screw extruder, a 2# screw extruder, a 3# screw extruder and a 4# screw extruder for hydrolysis;

b. in the hydrolysis process, firstly, water with the temperature of 50-60 ℃ in a heater (20) is started to heat the machine body through a coil heat exchanger, and then the prepared liquid in the material preparation storage tank group (18) is added simultaneously;

c. when the materials enter a No. 1 screw extruder, a peristaltic pump or a liquid level valve is started to control the preparation liquid of a No. 1 preparation storage tank, a No. 2 preparation storage tank and a No. 3 preparation storage tank in a preparation storage tank group (18) to be slowly added into a screw extrusion hydrolysis unit (19) at the same time;

e. opening a new round of straw materials to enter a No. 1 screw extruder, adding the mixture liquid in a No. 1 mixing storage tank, a No. 2 mixing storage tank and a No. 3 mixing storage tank in a mixing storage tank group (18), and performing heat preservation, mixing materials and preliminary hydrolysis; each ingredient storage tank of the ingredient storage tank group (18) is provided with a communicated liquid level meter and a liquid level graduated scale;

h.4# screw extruder is the material blowing after the degree of depth hydrolysis, gets into storage tank (22) of taking the shallow after weighing through 2# collection feed bin weighing module (21) and reaches the specified weight and transports away, and storage tank (22) of next taking the shallow gets into work.

5. The use method of the straw raw material pretreatment device for the straw water reducing agent according to claim 4, is characterized in that: the straw is one or combination of wheat straw and corn straw.

6. The use method of the straw raw material pretreatment device for the straw water reducing agent according to claim 5, is characterized in that: the hot air used by the pre-drying module (6) is waste heat air exhausted from the spiral dryer (8), and the temperature of the pre-dried air is 50-150 ℃.

7. The use method of the straw raw material pretreatment device for the straw water reducing agent according to claim 4, is characterized in that: the ball mill of the horizontal ball mill micro-crushing module (13) is a horizontal ball mill, and the ball milling parameters are as follows: the particle size of the straw raw material is less than 10mm, the rotating speed is 10-50 r/min, the loading amount of the straw raw material is 10-15 Kg, the diameter of copper balls is 10-15 mm, the ball milling time is 10-15 min, and the particle size of discharged materials is 75-400 mu m.

8. The use method of the straw raw material pretreatment device for the straw water reducing agent according to claim 4, is characterized in that: the solid-to-solid ratio of the straw to the lubricating additive is =1000g to (6-10) ml; the solid acid ratio of the straw to the hydrolysis main catalytic acid is =1000g to (10-30) ml; the solid acid ratio of the straw to the hydrolysis cocatalyst diluted acid is =1000 g: 100 ml;

the monoacid is one or a combination of hypophosphorous acid, formic acid, acetic acid, benzoic acid, acrylic acid, methacrylic acid, stearic acid and oleic acid;

the dibasic acid is one or more of phosphorous acid, oxalic acid, terephthalic acid, itaconic acid, maleic acid and maleic anhydride;

the polybasic acid is one or two of phosphoric acid and citric acid.

9. The use method of the straw raw material pretreatment device for the straw water reducing agent according to claim 4, is characterized in that: the screw extruder of the screw extrusion hydrolysis unit (19) is a single/double screw extruder, the rotating speed of a motor is controlled to be 50-80 r/min, the certain hydrolysis time of each batch of materials in a single screw extruder is 5min, and the total hydrolysis time of the hydrolysis unit consisting of 4 screw extruders is 20min correspondingly.

10. The use method of the straw raw material pretreatment device for the straw water reducing agent according to claim 8, is characterized in that: the heater (20) heats materials in the shell through a coil heat exchanger wound outside the shell of the screw extrusion hydrolysis unit (19), and the flow direction of a heat medium is opposite to the direction of the materials in the screw extrusion hydrolysis unit (19) and is in countercurrent heat exchange.