Straw curing process

Abstract

The invention discloses a straw curing process which comprises the steps of raw material preparation, moisture adjustment, layered feeding, puffing and curing, automatic water replenishing and the like. In the layered feeding process, the straw layers and the filler layers are alternately fed into a double-screw bulking machine in a layered mode so as to form vertical multi-layer alternate laying of the straw layers, the filler layers, the straw layers and the filler layers, and the filler layers comprise water absorption filler and / or nutrient filler. The straw layers and the filler layers containing the water-absorbing filler and / or the nutrient filler are alternately fed into the double-screw bulking machine in a layered manner, so that the straws can be subjected to the effects of screw rotation and cylinder heating in the curing process, and can be in full contact and interaction with the filler. The water absorption filler can absorb excessive moisture in the straw, the humidity of the material is further adjusted, and the curing effect is prevented from being affected by uneven moisture distribution; and the nutrient filler can provide necessary nutrient substances for microbial growth and chemical reaction in the curing process, and promote decomposition and conversion of the straws.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural waste resource utilization, and in particular to a straw maturation process. Background Art

[0002] Straw contains rich organic substances, such as nitrogen, phosphorus, potassium, calcium, magnesium and organic matter, and is a renewable biological resource with multiple uses. From the perspective of agricultural ecology, rationally maturing and returning straw to the field can realize the return of elements in the straw to the field, increase the content of soil organic matter, prevent soil compaction, enhance soil fertility, reduce the application of chemical fertilizers, and help form a virtuous cycle of agriculture. It is of great significance to improve the physical and chemical properties of soil and microbial flora, protect the ecological environment of land, improve fertilizer conversion efficiency, and promote sustainable agricultural development.

[0003] In the existing straw maturation process, natural composting has significant shortcomings compared to the puffing treatment using a double-screw puffing machine: natural composting generally takes 4-6 months and is greatly affected by seasonal climate changes. It is difficult to ensure complete decomposition of natural composting. Some straw may not be fully decomposed, resulting in continued decomposition in the soil after application, which will consume oxygen in the soil, affect the growth of crop roots, and may also breed pests and pathogens. During the composting process, especially when stacked for a long time, nutrient loss is serious. For example, nitrogen may volatilize into the atmosphere in the form of ammonia, resulting in a decrease in the nutrient content of the fertilizer and a weakening of the fertilizer effect. During the composting process, especially in the early stage of decomposition, an unpleasant odor will be produced, attracting mosquitoes to breed, polluting the surrounding environment, and affecting the lives of surrounding residents.

[0004] Therefore, it is necessary to provide a straw maturation process, which can greatly shorten the maturation time based on the use of a double-screw extruder, so that the straw can be evenly and fully decomposed, the nutrients can be well retained and converted, and the removal of harmful substances can be more effective, so that the obtained mature straw can form a loose and porous structure, and can also broaden the application in the feed field and the use of light industrial raw materials, as well as reduce pollution emissions and make resource recycling more efficient. Summary of the invention

[0005] The object of the present invention is to provide a straw maturation process to solve the problems in the prior art that the straw maturation process pollutes the environment, the utilization rate of the maturation product is low, and the stability of the maturation process is poor.

[0006] In order to solve the above technical problems, the present invention specifically provides the following technical solutions: The present invention provides a straw maturation process, comprising the following steps: (1) Raw material preparation: Select straw that is not moldy or rotten and remove impurities, then cut the straw into small pieces of 2-5 cm in length; (2) Moisture adjustment: Add purified water to the cut straw and mix evenly to keep the moisture content of the straw between 40% and 45%; (3) Layered feeding: feeding the straw layer and the filler layer into the double-screw extruder alternately for multiple times to form a straw layer-filler layer-straw layer-filler layer alternately laid up and down, wherein the filler layer contains a water-absorbing filler and / or a nutrient filler; (4) Puffing and maturation: The barrel of the twin-screw extruder is divided into multiple hot zones, and the heating temperature of each hot zone increases from the feed end to the discharge end. The heating temperature of the hot zone close to the feed end is 150-180°C, and the heating temperature of the hot zone at the discharge end is 400-450°C. The heating temperature difference between adjacent hot zones is 50-80°C, so as to achieve gradient heating of the straw. The residence time of the straw in the twin-screw extruder is 15-25s. Under the combined action of screw rotation, extrusion and barrel shell heating, the straw reaches a maturation state under high temperature and high pressure environment. (5) Automatic water replenishment: In steps (2) to (4), an online moisture monitor is used to monitor the moisture content of the straw in real time, and the amount of purified water added is adjusted according to the monitoring results to maintain the moisture content of the straw between 40% and 45%.

[0007] Preferably, in step (1), impurities are removed by a multi-layer vibrating screen, and the multi-layer vibrating screen comprises at least three layers of screens; wherein the aperture of the first layer of screens is between 5-10 cm, the aperture of the second layer of screens is between 2-5 cm, and the aperture of the third layer of screens is between 2-5 mm; before cutting, the straw raw material passes through the first layer of screens, the second layer of screens, and the third layer of screens in sequence to remove impurities; after cutting, the straw raw material passes through the second layer of screens again to screen out straw with a length greater than 5 cm.

[0008] Preferably, in step (2), purified water is atomized by a nozzle and then sprayed on the straw, and a stirring device is turned on at the same time, so that the straw absorbs water evenly during the stirring process; wherein the stirring speed of the stirring device is 30 to 60 r / min, and the stirring time is 15 to 30 min, until the surface of the straw is evenly moistened without obvious dry parts.

[0009] Preferably, in step (3), the thickness of the filler layer is 2-3 cm, and the thickness of the straw layer is 5-10 cm; wherein the water-absorbing filler comprises montmorillonite, and the nutritional filler comprises soybean meal.

[0010] Preferably, in step (3), montmorillonite and soybean meal are mixed in a ratio of 1:2, and starch paste is added as a binder; wherein the amount of the starch paste is 5% to 10% of the total mass of the filler layer, and the starch paste is formed into particles with a diameter of 2 to 5 mm by a granulator.

[0011] Preferably, in step (3), pure water is added to the filler layer and mixed to prepare a wet filler with a moisture content of 60%-70%; wherein, sucrose fatty acid ester is added as an emulsifier during the mixing process of the wet filler, and the amount of sucrose fatty acid ester is 0.5%-1% of the total mass of the filler layer, and then the wet filler is allowed to stand for 30-60 minutes to allow the water to fully penetrate into the filler.

[0012] Preferably, in step (3), in the twin-screw extruder, a wet filler layer with a thickness of 4 to 6 cm is first laid, and then a straw layer with a thickness of 6 to 8 cm is laid; wherein, when laying the straw layer, a spray device is used to spray purified water on the surface of the straw, and the spraying amount is 5% to 10% of the mass of the straw to make the surface moist.

[0013] Preferably, in step (3), after each straw layer is laid, a film is covered on its surface, and the film thickness is 0.05-0.1 mm; wherein the film is a modified cellulose edible packaging film, and the modified cellulose edible packaging film is provided with a plurality of air holes, the aperture of the air holes is 1-2 mm, and the hole spacing of the air holes is 5-10 mm.

[0014] Preferably, in step (3), the filler layer comprises an upper filler layer and a lower filler layer, wherein the upper filler layer is composed of soybean meal and a water retaining agent, and is used to slowly release moisture during the puffing process and provide nutrition for the straw layer; the lower filler layer is composed of montmorillonite and soybean meal in a ratio of 3:1, and is used to absorb and retain moisture; wherein the water retaining agent is sodium polyacrylate, and the amount of sodium polyacrylate is 3% to 5% of the total mass of the upper filler layer; the moisture content of the upper filler layer is controlled at 40% to 50%, and the moisture content of the lower filler layer is controlled at 50% to 60%.

[0015] Preferably, in step (3), in the extruder, a layer of wet filler with a thickness of 5 to 7 cm is first laid as the lower layer, and then a layer of straw with a thickness of 7 to 9 cm is laid as the middle layer, and then a layer of wet filler with a thickness of 3 to 5 cm is laid as the upper layer, and then another layer of straw is laid as the middle layer, and so on alternately; during the laying process, the filler layer and the straw layer are gradually mixed during the feeding process by the low speed rotation of the twin-screw extruder, so as to form a gradient distribution structure.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention controls the moisture content of the straw between 40% and 45%, which is conducive to forming good material fluidity and plasticity in the extruder, making it easier for the straw to undergo physical and chemical changes under the rotation and extrusion of the screw, promoting the degradation and transformation of macromolecular substances such as cellulose and hemicellulose, and improving the ripening effect. It avoids the need to consume too much energy to evaporate water during the puffing and ripening process due to excessive moisture, thereby reducing energy consumption. At the same time, it can also prevent the excessive friction heat generated by the straw in the extruder due to too little moisture, resulting in local overheating and affecting the quality uniformity of the ripened product.

[0017] 2. The present invention alternately feeds the straw layer and the filler layer containing the water-absorbing filler and / or the nutrient filler into the double-screw extruder in layers, so that the straw can not only be affected by the screw rotation and the barrel heating during the maturation process, but also fully contact and interact with the filler. The water-absorbing filler can absorb the excess water in the straw, further adjust the humidity of the material, and prevent the maturation effect from being affected by uneven water distribution; the nutrient filler can provide the necessary nutrients for the growth of microorganisms and chemical reactions in the maturation process, promote the decomposition and transformation of the straw, improve the nutritional value of the maturation product, and improve the maturation effect.

[0018] 3. The present invention uses layered fillers and reasonably controls the thickness of each layer, so that the material is heated and pressed more evenly in the twin-screw extruder, which is beneficial to improving the extrusion effect, so that the fiber structure of the straw is more fully destroyed and modified, thereby improving the digestibility and water absorption of the straw and better meeting the requirements of different application fields. Since the mixing of montmorillonite, soybean meal and straw is more uniform, the distribution of nutrients is reasonable, and the moisture regulation and heat transfer effects are good, the ripening reaction can be carried out more quickly and fully, thereby shortening the straw ripening time to a certain extent and improving production efficiency.

[0019] 4. The present invention makes the filler layer into a wet filler with a moisture content of 60%-70%, which can provide sufficient moisture for the straw maturation process, promote chemical reactions inside the straw, help dissolve and transfer nutrients, etc., which is conducive to improving the maturation effect and making the straw easier to be processed or used later. By adding 0.5% to 1% of the total mass of the filler layer of sucrose fatty acid ester as an emulsifier, it is helpful to improve the mixing uniformity of the various components in the filler. Ensuring the stability and repeatability of the maturation process is conducive to producing a mature straw product with stable and reliable quality. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Embodiment 1: This embodiment provides a straw maturation process, comprising the following steps: (1) Raw material preparation: Select straw that is not moldy or rotten and remove impurities, then cut the straw into small pieces of 2-5 cm in length; (2) Moisture adjustment: Add purified water to the cut straw and mix evenly to keep the moisture content of the straw between 40% and 45%; (3) Layered feeding: feeding the straw layer and the filler layer into the double-screw extruder alternately for multiple times to form a straw layer-filler layer-straw layer-filler layer alternately laid up and down, wherein the filler layer contains a water-absorbing filler and / or a nutrient filler; (4) Puffing and maturation: The barrel of the twin-screw extruder is divided into multiple hot zones, and the heating temperature of each hot zone increases from the feed end to the discharge end. The heating temperature of the hot zone close to the feed end is 150-180°C, and the heating temperature of the hot zone at the discharge end is 400-450°C. The heating temperature difference between adjacent hot zones is 50-80°C, so as to achieve gradient heating of the straw. The residence time of the straw in the twin-screw extruder is 15-25s. Under the combined action of screw rotation, extrusion and barrel shell heating, the straw reaches a maturation state under high temperature and high pressure environment. (5) Automatic water replenishment: In steps (2) to (4), an online moisture monitor is used to monitor the moisture content of the straw in real time, and the amount of purified water added is adjusted according to the monitoring results to maintain the moisture content of the straw between 40% and 45%.

[0022] The straw maturation process provided by the present invention can avoid the influence of the quality of the raw materials themselves on the maturation effect of the straw and the quality of the final product of the straw maturation by selecting and removing the straw without mildew and rot in step (1). For example, harmful substances such as toxins produced by mildew can be prevented from entering the maturation product, thereby ensuring the safety of subsequent products during use and improving their quality as feed, fertilizer, etc. Before the straw is subjected to the maturation process, the straw is cut into small sections of 2-5 cm, which helps to increase the contact area between the straw and water, filler, and the screw and barrel of the extruder, making it easier for water to penetrate into the interior of the straw, and facilitating the transfer of heat and the exchange of substances during the extrusion and maturation process, thereby improving the efficiency and uniformity of the maturation reaction and enabling the straw to be more fully maturated. In the moisture adjustment process of step (2), the moisture content of the straw is controlled between 40% and 45%, which can create a suitable humidity environment for straw maturation. Appropriate moisture content is conducive to forming good material fluidity and plasticity in the extruder, making it easier for the straw to undergo physical and chemical changes under the rotation and extrusion of the screw, promoting the degradation and transformation of macromolecular substances such as cellulose and hemicellulose, and improving the ripening effect. Maintaining an appropriate moisture content can avoid the need to consume too much energy to evaporate water during the puffing and ripening process due to excessive moisture, thereby reducing energy consumption and improving the economic efficiency of production. At the same time, it can also prevent the excessive friction and heat generation of the straw in the extruder due to too little moisture, resulting in local overheating and affecting the quality uniformity of the ripened product.

[0023] More specifically, in the layered feeding process of step (3), on the one hand, by alternately feeding the straw layer and the filler layer containing the water-absorbing filler and / or the nutrient filler into the twin-screw extruder, the straw can be not only subjected to the effects of screw rotation and barrel heating during the maturation process, but also fully contact and interact with the filler. The water-absorbing filler can absorb excess water in the straw, further adjust the humidity of the material, and prevent the maturation effect from being affected by uneven water distribution; the nutrient filler can provide necessary nutrients for the growth of microorganisms and chemical reactions during the maturation process, promote the decomposition and transformation of the straw, and improve the nutritional value of the maturation product, which can improve the maturation effect.

[0024] Furthermore, on the other hand, this layered structure helps to form a more stable material structure during the puffing and maturation process, making the straw less likely to deform and break under high temperature and high pressure environments, thereby ensuring the uniformity of shape and particle size of the maturation product, which is beneficial to subsequent processing and application. For example, when used as feed, it can improve its palatability and digestibility; when used as fertilizer, it can improve its dispersibility and sustained release properties in the soil, thereby enhancing product stability.

[0025] Furthermore, on another aspect, the twin-screw extruder barrel adopts a design of multiple heat zones and the heating temperature increases from the feed end to the discharge end, which can realize gradient heating of the straw. In the lower temperature zone of the feed end, the straw is first preheated to evaporate the water therein slowly, avoiding the explosion phenomenon caused by the rapid vaporization of water due to sudden high temperature; as the material moves to the discharge end, the temperature gradually increases, and the straw undergoes different degrees of physical and chemical changes in different temperature zones, such as cellulose softening, hemicellulose degradation, lignin modification, etc. This gradient heating method is conducive to giving full play to the role of each temperature section in promoting the maturation of the straw, making the maturation of the straw more uniform and thorough, improving the quality and performance of the maturation product, and realizing gradient heating.

[0026] Furthermore, on another aspect, the residence time of the straw in the twin-screw extruder is only 15-25 seconds. The relatively short residence time combined with the combined effects of screw rotation, extrusion and barrel shell heating can make the straw reach a mature state in a short time, greatly improving production efficiency and meeting the needs of large-scale industrial production. At the same time, precise control of parameters such as residence time and heating temperature can also ensure the quality stability and consistency of the matured product, which is conducive to standardized production and market promotion of the product.

[0027] Furthermore, on another aspect, an online moisture monitor is used to monitor the moisture content of the straw in real time during the entire ripening process, and the amount of purified water added is automatically adjusted according to the monitoring results, so that the moisture content of the straw can be accurately controlled. This can ensure that the straw can be kept within the optimal moisture content range in each process link, so that it is always under good ripening conditions, further improve the quality stability and uniformity of the ripened product, and reduce the product quality differences caused by moisture fluctuations. The application of the automatic water replenishment system reduces the workload of manual sampling and testing and manual adjustment of moisture, reduces the errors and uncertainties caused by manual operations, and improves the automation level and control accuracy of the production process. At the same time, it also helps to reduce labor intensity and production costs, improve production efficiency and the economic benefits of the enterprise.

[0028] More specifically, in step (1), impurities are removed by a multi-layer vibrating screen, and the multi-layer vibrating screen comprises at least three layers of screens; wherein the aperture of the first layer of screens is between 5-10 cm, the aperture of the second layer of screens is between 2-5 cm, and the aperture of the third layer of screens is between 2-5 mm; before cutting, the straw raw material passes through the first layer of screens, the second layer of screens, and the third layer of screens in sequence to remove impurities; after cutting, the straw raw material passes through the second layer of screens again to screen out straw with a length greater than 5 cm.

[0029] In this embodiment, the aperture of the first layer of screen is between 5-10cm, which can effectively screen out larger impurities in the straw raw material, such as large stones, wood blocks, etc., to prevent these impurities from entering the subsequent processing links and causing damage to the processing equipment, such as damaging the cutting tool, blocking the conveying pipeline, etc., extending the service life of the equipment and reducing the equipment maintenance cost. After passing through the first layer of screen, the aperture of the second layer of screen is between 2-5cm, further removing medium-sized impurities, and at the same time preliminarily classifying the straw, so that the relatively small and relatively pure straw enters the third layer of screen, improving the precision and efficiency of impurity removal, and providing higher quality raw materials for subsequent processing. The aperture of the third layer of screen is between 2-5mm, which can screen out fine impurities in the straw raw material, such as dust, sand, etc., making the straw purer, which is conducive to improving the quality of straw maturation products. For example, when the matured straw is used for feed production, removing fine impurities can improve the palatability and safety of the feed; when the matured straw is used for papermaking, the impact of impurities on the quality of paper can be reduced.

[0030] Furthermore, in step (1), the cut straw is again screened through the second screen to screen out straw with a length greater than 5 cm, which can ensure that the length of the cut straw meets the processing requirements and makes the size of the straw more uniform, which is conducive to subsequent processing and use in the double-screw extruder. By screening and removing the straw with excessive length, the straw can be better mixed with fillers, purified water and other raw materials or react chemically in subsequent processing to ensure that it can be evenly heated and fully expanded in the extruder, avoiding problems such as local overheating and burning caused by uneven particle size, and improving the performance and quality stability of the matured straw.

[0031] More specifically, in step (2), purified water is atomized by a nozzle and then sprayed on the straw, and a stirring device is turned on at the same time, so that the straw absorbs water evenly during the stirring process; wherein the stirring speed of the stirring device is 30 to 60 r / min, and the stirring time is 15 to 30 min, until the surface of the straw is evenly moistened without obvious dry parts.

[0032] More specifically, in step (3), the thickness of the filler layer is 2-3 cm, and the thickness of the straw layer is 5-10 cm; wherein the water-absorbing filler comprises montmorillonite, and the nutritional filler comprises soybean meal. Montmorillonite and soybean meal are mixed in a ratio of 1:2, and starch paste is added as a binder; wherein the amount of the starch paste is 5%-10% of the total mass of the filler layer, and the granulator is used to form granules with a diameter of 2-5 mm.

[0033] In this embodiment, firstly, montmorillonite has a strong water absorption capacity, can absorb and retain a large amount of water, and slowly releases it during the straw maturation process, providing a continuous and stable moisture environment for microbial fermentation and chemical reactions in the straw and soybean meal, which is conducive to improving the maturation effect. The right amount of water plus the water absorption and expansion characteristics of montmorillonite can keep the material in an appropriate humidity and loose state, prevent the straw and filler from agglomerating due to uneven moisture during the maturation process, ensure the good fluidity of the material in the twin-screw extruder, and ensure the smooth progress of the maturation process.

[0034] In the present embodiment, secondly, soybean meal is rich in nutrients such as protein and amino acids, and is a high-quality protein source for animal feed. Adding it as a nutritional filler to the straw maturation process can significantly improve the nutritional value of straw and broaden the application range of straw, such as being used to produce higher-quality animal feed. Thirdly, montmorillonite and soybean meal are mixed in a ratio of 1:2 to make the nutrients more comprehensive and balanced. The mineral elements in montmorillonite can also provide certain nutritional supplements for the products after straw maturation, meeting the diversified needs of different biological or industrial production for nutrients. Adding 5% to 10% starch paste as a binder and making particles with a diameter of 2 to 5 mm helps to better bond montmorillonite, soybean meal and straw together to form particles with stable structure. Thirdly, during the straw maturation process, the particles can remain intact, reduce crushing and pulverization, improve the quality and stability of the product, and facilitate subsequent storage, transportation and use. The granular filler has good fluidity and can be more evenly distributed between the straw layers in the double-screw extruder and fully mixed with the straw, further improving the uniformity of material mixing, which is beneficial to the consistency of heat transfer and extrusion and maturation, making the quality of the matured straw product more uniform and stable.

[0035] In this embodiment, the filler is layered and the thickness of each layer is reasonably controlled, so that the material is heated and pressed more evenly in the twin-screw extruder, which is conducive to improving the expansion effect, so that the fiber structure of the straw is more fully destroyed and modified, thereby improving the digestibility, water absorption and other properties of the straw, and better meeting the requirements of different application fields. Since the mixing of montmorillonite, soybean meal and straw is more uniform, the distribution of nutrients is reasonable, and the moisture regulation and heat transfer effects are good, the ripening reaction can be carried out more quickly and fully, thereby shortening the straw ripening time to a certain extent and improving production efficiency. This process makes full use of resources such as montmorillonite and soybean meal, combines them with straw, realizes the effective integration and recycling of resources, reduces the generation of waste, and conforms to the concept of environmental protection and sustainable development. Compared with some traditional chemical additives, natural materials such as montmorillonite and soybean meal are more environmentally friendly, will not pollute the environment, reduce the environmental risks in the straw ripening process, and are conducive to ecological environmental protection.

[0036] Example 2: This example provides a straw maturation process, which differs from Example 1 in that: In the step (3), pure water is added to the filler layer and mixed to prepare a wet filler with a moisture content of 60% to 70%. During the mixing process of the wet filler, sucrose fatty acid ester is added as an emulsifier, and the amount of sucrose fatty acid ester is 0.5% to 1% of the total mass of the filler layer. The wet filler is then allowed to stand for 30 to 60 minutes to allow the water to fully penetrate into the filler.

[0037] In this embodiment, first, the filler layer is made into a wet filler with a moisture content of 60%-70%, which can provide sufficient moisture for the straw maturation process. Moisture plays an important role in the maturation process, such as promoting chemical reactions inside the straw, helping the dissolution and transmission of nutrients, etc., which is conducive to improving the maturation effect and making the straw easier to be processed or used later. Secondly, the wet filler is allowed to stand for 30-60 minutes, so that the moisture has enough time to fully penetrate into the filler. This ensures that the humidity of each part of the filler is uniform, avoids local drying or excessive moisture, lays the foundation for subsequent uniform mixing with the straw and uniform transfer of heat and materials during the maturation process, and helps to improve the quality stability of the maturation product. Again, adding sucrose fatty acid esters in an amount of 0.5%-1% of the total mass of the filler layer as an emulsifier helps to improve the mixing uniformity of the various components in the filler. Sucrose fatty acid esters can reduce the surface tension between water and other components, making them easier to merge and disperse with each other, thereby ensuring that the filler can be more evenly distributed in the straw layer when mixed with the straw, and improving the uniformity of the entire material system. During the storage and use of wet fillers, emulsifiers can prevent the separation of different components in the fillers due to differences in density, solubility, etc. This allows the fillers to always maintain consistency and stability of the ingredients after being mixed with the straw and entering the double-screw extruder, ensuring the stability and repeatability of the maturation process, which is conducive to the production of mature straw products with stable and reliable quality. Sucrose fatty acid esters themselves have certain stability and antioxidant properties. Adding them to wet fillers can play a certain protective role on the nutrients therein. For example, it prevents some easily oxidizable nutrients from being oxidized and destroyed during contact with water or during the maturation process, thereby better retaining the nutrients in the fillers and improving the nutritional value of the matured straw products.

[0038] In this embodiment, the use of emulsifier can make the wet filler have better texture and taste. When the ripened straw product is used for feed and other applications, the good taste can increase the animal's feeding rate, thereby improving the utilization rate of straw, which is beneficial to the development of related industries such as animal husbandry. After entering the double-screw extruder, the wet filler with uniform mixing and good water penetration can better adapt to the process conditions such as high temperature, high pressure and screw pushing in the extruder. Its good fluidity and dispersibility can reduce the risk of blockage in the extruder, reduce equipment failure and downtime, improve production efficiency, and reduce production costs. Since the various properties of the wet filler are optimized, it can more effectively transfer heat and promote the progress of chemical reactions during the process of co-ripening with the straw. This helps to accelerate the ripening reaction speed of the straw, shorten the ripening time, and while improving production efficiency, it can also reduce energy consumption and achieve the purpose of energy conservation and emission reduction.

[0039] More specifically, in step (3), a layer of wet filler with a thickness of 4 to 6 cm is first laid in the twin-screw extruder, and then a layer of straw with a thickness of 6 to 8 cm is laid; wherein, when laying the straw layer, a spray device is used to spray purified water on the surface of the straw, and the spraying amount is 5% to 10% of the mass of the straw to make the surface wet. After each layer of straw is laid, a film is covered on the surface, and the film thickness is 0.05 to 0.1 mm; wherein, the film is a modified cellulose edible packaging film, and the modified cellulose edible packaging film is provided with a plurality of air holes, the aperture of the air holes is 1 to 2 mm, and the hole spacing of the air holes is 5 to 10 mm.

[0040] In this embodiment, firstly, the modified cellulose edible packaging film with a thickness of 0.05-0.1 mm has a certain barrier property, which can effectively reduce the loss of water in the straw layer and the wet filler layer, so that the material always maintains a suitable humidity environment in the twin-screw extruder. This helps the cellulose and other components in the straw to fully absorb water, so as to better carry out the ripening reaction and improve the ripening effect. The covering of the film can make the water more evenly penetrate and distribute in the straw layer. Due to the presence of the film, the water will not be lost quickly or unevenly distributed due to external factors (such as the airflow in the extruder, etc.), ensuring that all parts of the straw layer can obtain sufficient water, which is conducive to improving the uniformity of ripening and making the quality of the ripened straw more stable and consistent. Secondly, the film can slow down the loss of heat to a certain extent and help maintain a relatively stable temperature environment in the twin-screw extruder. During the ripening process, stable temperature is crucial for the chemical reaction and physical change of the straw. It can ensure that the ripening reaction is carried out at a predetermined rate and degree, and avoid problems such as incomplete ripening or over-ripening caused by temperature fluctuations, thereby improving the quality and efficiency of straw ripening. Secondly, the presence of air holes allows heat to be transferred more evenly between the straw layer and the wet filler layer. Hot air can flow between the layers through the air holes, making the material heated more evenly, further promoting the straw maturation reaction, improving the uniformity of the puffing effect, and making the structure and performance of the matured straw more consistent.

[0041] In this embodiment, during the operation of the twin-screw extruder, the material will be pushed and stirred by the screw to produce a certain movement. The covering film can prevent the straw and wet filler from splashing out of the extruder during the movement, avoiding the waste of materials and pollution to the surrounding environment, while also reducing the workload of operators to clean equipment and work areas, and improving the cleanliness and safety of the production process. As an isolation barrier, the film can effectively prevent external impurities, dust, etc. from entering the material layer, avoiding adverse effects on the straw maturation process and the quality of the final product, and ensuring the purity and quality of the matured straw. The modified cellulose edible packaging film can provide a certain protection for the nutrients in the straw. During the maturation process, some nutrients may undergo oxidation, decomposition, etc. due to contact with air, moisture, etc., resulting in the loss or destruction of nutrients. The covering of the film can reduce the contact between nutrients and the external environment, thereby better retaining the nutrients in the straw and improving the nutritional value of the straw product after maturation. The setting of the air vents provides suitable conditions for the growth and fermentation of microorganisms. During the straw maturation process, some microbial agents may be added to promote the fermentation reaction. The air holes can ensure that the microorganisms carry out normal metabolic activities in an aerobic environment, which is beneficial to improving the fermentation efficiency and further improving the quality and performance of the straw, making it more suitable for use in feed, biofertilizer and other fields.

[0042] In this embodiment, by covering the film and combining the design of the air holes, the straw can form a more uniform and loose structure during the expansion process. Under high temperature and high pressure environment, the gas generated by the evaporation of water inside the straw can be discharged in an orderly manner through the air holes, thereby forming more pores and channels inside the straw, improving the expansion rate and volume expansion multiple of the straw, and making the ripened straw have better palatability, digestibility and adsorption performance. The presence of the film helps to improve the stability and storage performance of the ripened straw product. It can prevent the quality of the straw from being affected by moisture absorption, deterioration and other reasons during storage and transportation, extend the shelf life of the product, and facilitate the long-term storage and use of the product. This can prevent excessive evaporation of water, and ensure a certain degree of air permeability, avoiding the generation of undesirable gas accumulation during the expansion process.

[0043] More specifically, in step (3), the filler layer comprises an upper filler layer and a lower filler layer, wherein the upper filler layer is composed of soybean meal and a water retaining agent, and is used to slowly release water during the puffing process and provide nutrition to the straw layer; the lower filler layer is composed of montmorillonite and soybean meal in a ratio of 3:1, and is used to absorb and retain water; wherein the water retaining agent is sodium polyacrylate, and the amount of sodium polyacrylate is 3% to 5% of the total mass of the upper filler layer; the moisture content of the upper filler layer is controlled at 40% to 50%, and the moisture content of the lower filler layer is controlled at 50% to 60%.

[0044] More specifically, in step (3), in the extruder, a layer of wet filler with a thickness of 5 to 7 cm is first laid as the lower layer, and then a layer of straw with a thickness of 7 to 9 cm is laid as the middle layer, and then a layer of wet filler with a thickness of 3 to 5 cm is laid as the upper layer, and then another layer of straw is laid as the middle layer, and so on alternately; during the laying process, the filler layer and the straw layer are gradually mixed during the feeding process through the low speed rotation of the twin-screw extruder, forming a gradient distribution structure.

[0045] In this embodiment, the low speed of the twin-screw extruder is 30~50r / min, and the layered structure of the wet filler and straw layers with inconsistent thickness can gradually transfer moisture from bottom to top, which is more conducive to the straw to absorb moisture evenly and can continuously maintain a certain moisture content during the extrusion process.

[0046] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A straw maturation process, characterized in that: The following steps are involved: (1) Raw material preparation: Select straw that is not moldy or rotten and remove impurities, then cut the straw into small pieces of 2-5 cm in length; (2) Moisture adjustment: Add purified water to the cut straw and mix evenly to keep the moisture content of the straw between 40% and 45%; (3) Layered feeding: feeding the straw layer and the filler layer into the double-screw extruder alternately for multiple times to form a straw layer-filler layer-straw layer-filler layer alternately laid up and down, wherein the filler layer contains a water-absorbing filler and / or a nutrient filler; (4) Puffing and maturation: The barrel of the twin-screw extruder is divided into multiple hot zones, and the heating temperature of each hot zone increases from the feed end to the discharge end. The heating temperature of the hot zone close to the feed end is 150-180°C, and the heating temperature of the hot zone at the discharge end is 400-450°C. The heating temperature difference between adjacent hot zones is 50-80°C, so as to achieve gradient heating of the straw. The residence time of the straw in the twin-screw extruder is 15-25s. Under the combined action of screw rotation, extrusion and barrel shell heating, the straw reaches a maturation state under high temperature and high pressure environment. (5) Automatic water replenishment: In steps (2) to (4), an online moisture monitor is used to monitor the moisture content of the straw in real time, and the amount of purified water added is adjusted according to the monitoring results to maintain the moisture content of the straw between 40% and 45%.

2. A straw maturation process according to claim 1, characterized in that: In the step (1), impurities are removed by a multi-layer vibrating screen, wherein the multi-layer vibrating screen comprises at least three layers of screens; Among them, the aperture of the first layer of screen is between 5-10cm, the aperture of the second layer of screen is between 2-5cm, and the aperture of the third layer of screen is between 2-5mm; Before cutting, the straw raw material passes through the first layer of screen, the second layer of screen, and the third layer of screen in sequence to remove impurities; After the straw raw material is cut, it is passed through the second layer of screen to screen out the straw with a length greater than 5 cm.

3. A straw maturation process according to claim 2, characterized in that: In step (2), the purified water is atomized by a nozzle and then sprayed on the straw, and the stirring device is turned on at the same time, so that the straw absorbs water evenly during the stirring process; The stirring speed of the stirring equipment is between 30 and 60 r / min, and the stirring time is between 15 and 30 min, until the surface of the straw is evenly moistened without obvious dry parts.

4. A straw maturation process according to claim 3, characterized in that: In step (3), the thickness of the filler layer is 2-3 cm, and the thickness of the straw layer is 5-10 cm; Wherein, the water-absorbing filler comprises montmorillonite, and the nutritional filler comprises soybean meal.

5. A straw maturation process according to claim 4, characterized in that: In the step (3), montmorillonite and soybean meal are mixed in a ratio of 1:2, and starch paste is added as a binder; The starch paste is used in an amount of 5% to 10% of the total mass of the filler layer, and is formed into particles with a diameter of 2 to 5 mm by a granulator.

6. A straw maturation process according to claim 4, characterized in that: In the step (3), pure water is added to the packing layer and mixed to prepare a wet packing with a moisture content of 60% - 70%; Among them, sucrose fatty acid ester is added as an emulsifier during the mixing process of the wet filler, and the amount of sucrose fatty acid ester is 0.5%~1% of the total mass of the filler layer. The wet filler is then allowed to stand for 30~60 minutes to allow the water to fully penetrate into the filler.

7. A straw maturation process according to claim 6, characterized in that: In the step (3), a layer of wet filler with a thickness of 4 to 6 cm is first laid in the twin-screw extruder, and then a layer of straw with a thickness of 6 to 8 cm is laid; When laying the straw layer, use a spray device to spray purified water on the surface of the straw, with the spraying amount being 5% to 10% of the straw mass, to make its surface moist.

8. A straw maturation process according to claim 7, characterized in that: In the step (3), after each straw layer is laid, a film is covered on the surface thereof, and the thickness of the film is 0.05-0.1 mm; Wherein, the film is a modified cellulose edible packaging film, and the modified cellulose edible packaging film is provided with a plurality of air holes, the aperture of the air holes is 1-2 mm, and the hole spacing of the air holes is 5-10 mm.

9. A straw maturation process according to claim 8, characterized in that: In step (3), the filler layer comprises an upper filler layer and a lower filler layer, wherein the upper filler layer is composed of soybean meal and a water retaining agent, and is used to slowly release water during the puffing process and provide nutrition to the straw layer; the lower filler layer is composed of montmorillonite and soybean meal in a ratio of 3:1, and is used to absorb and retain water; Wherein, the water retaining agent is sodium polyacrylate, and the amount of the sodium polyacrylate is 3% to 5% of the total mass of the upper filler; The moisture content of the upper filler is controlled at 40% to 50%, and the moisture content of the lower filler is controlled at 50% to 60%.

10. The straw maturation process according to claim 9, characterized in that: In the step (3), in the extruder, a layer of wet filler with a thickness of 5 to 7 cm is first laid as the lower layer, and then a layer of straw with a thickness of 7 to 9 cm is laid as the middle layer, and then a layer of wet filler with a thickness of 3 to 5 cm is laid as the upper layer, and then another layer of straw is laid as the middle layer, and so on alternately; during the laying process, the filler layer and the straw layer are gradually mixed during the feeding process by the low speed rotation of the twin-screw extruder, so as to form a gradient distribution structure.