Steam explosion rice straw feed preparation method based on secondary pressure boosting and feed

Abstract

The invention relates to the technical field of crop straw feed treatment, and discloses a steam explosion rice straw feed preparation method based on secondary boosting, which comprises the following steps: S1, raw material pretreatment: crushing rice straws into strip-shaped structures of 3-5cm, and removing iron; s2, chemical pretreatment: adding urea or ammonia water in a certain proportion of the dry weight of the straws into the crushed straws, adjusting the water content, and carrying out a sealed reaction; s3, primary pressure increasing: the pretreated straw is loaded into a steam explosion device, saturated steam is introduced, the pressure is maintained at 0.8-1.4 MPa, and the pressure is maintained for 30-400 seconds; s4, secondary pressure boosting explosion: introducing saturated steam after the pressure maintaining time is reached, rapidly increasing the pressure to 1.5-1.8 MPa, and instantly releasing the pressure; and S5, collecting a product. The neutral detergent fiber content (NDF) and the acid detergent fiber content (ADF) of the rice straw feed are remarkably reduced, and meanwhile the straw tearing effect, the crude protein content, the fiber degradation rate and the feeding value are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of crop straw feed treatment, and particularly relates to a method for preparing steam-exploded rice straw feed based on secondary pressure boosting and a feed. Background Art

[0002] Crop straw resources in China are very rich. About 700 million tons of crop straw are produced every year, among which 230 million tons are rice straw, accounting for 29.93% of the total straw. The feed utilization rate only accounts for 17.99% of the comprehensive utilization rate. Most of them are directly burned or directly returned to the field as fertilizer, which not only causes huge resource waste, but also causes many environmental pollution problems. The feed utilization of straw can not only expand the feed source, solve the problem of shortage of roughage brought about by the rapid development of animal husbandry in China, reduce the breeding cost, but also reduce the environmental pollution caused by straw burning. However, untreated straw has poor palatability and low digestibility, which limits the application of straw in animal husbandry production. Pretreatment of straw can break the cell wall structure of straw, improve the nutritional value and digestibility of straw, and improve palatability. At present, the pretreatment methods of straw include physical, chemical, biological and combined treatment methods, etc. Among them, steam explosion can significantly increase the degradation of cellulose, hemicellulose and lignin, improve the nutritional value and digestibility of straw, and has the advantages of short treatment time, high efficiency and no environmental pollution.

[0003] Most existing steam explosion technologies use single-pressure treatment. Although it can partially destroy the fiber structure, the tearing effect on straw fibers is limited, and the increase in crude protein is insufficient. In addition, the synergistic effect of chemical pretreatment and steam explosion has not been fully explored.

[0004] The existing patent CN 109170227 A discloses a method of single-pressure steam explosion combined with ammoniation treatment, but does not involve staged pressure boosting; CN 119184216 A optimizes the steam explosion parameters of rice straw, but does not solve the problems of high lignin residue and limited straw tearing effect. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for preparing steam-exploded rice straw feed based on secondary pressure boosting, which can significantly reduce the neutral detergent fiber content (NDF) and acid detergent fiber content (ADF) of rice straw feed, and at the same time improve the straw tearing effect, crude protein content, fiber degradation rate and feeding value.

[0006] The above technical purpose of the present invention is achieved through the following technical solutions: A method for preparing steam-exploded rice straw feed based on secondary pressure boosting, comprising the following steps: S1 Raw material pretreatment: Crush the rice straw into strips of 3-5cm and remove iron. Select the freshest straw to reduce the degree of lignification. The crushing process can increase the specific surface area of ​​the straw, so that the subsequent chemical pretreatment and steam explosion process can act more fully on the straw and improve the treatment effect. The crushed raw materials are firstly subjected to a first stage of iron removal to remove the iron-containing impurities close to the surface of the belt, and then to a second stage of iron removal to remove the iron-containing impurities inside the raw materials. Through the combination of "surface adsorption + deep detection", the iron removal efficiency is significantly improved. Compared with the existing technology, it can effectively reduce the equipment failure rate and reduce the risk of metal contamination in feed.

[0007] S2 Chemical pretreatment: Add urea or ammonia water in a certain proportion of the dry weight of the straw to the crushed straw, adjust the moisture content to 30% - 60%, and seal the reaction for 24 - 48 hours; The role of urea and ammonia water: They are both alkaline substances that can react with lignin in the straw to partially dissolve and decompose the lignin, thereby destroying the cell wall structure of the straw and reducing the crystallinity of the fiber. At the same time, urea will decompose and produce ammonia under the action of microorganisms. Ammonia can combine with some components in the straw to increase the crude protein content of the straw; Adjust the moisture content: The appropriate moisture content can ensure the uniformity and effectiveness of chemical pretreatment. As a reaction medium, water helps urea or ammonia water to better penetrate into the interior of the straw and promote the chemical reaction.

[0008] S3 Initial pressure increase: The pretreated straw is loaded into the steam explosion device and saturated steam is introduced. The pressure is maintained at 0.8-1.4MPa for 30-400 seconds. The steam molecules penetrate into the pores of the straw cell wall and the gaps between the microfibrils under the action of pressure, destroying the hydrogen bonds and van der Waals forces between lignin and cellulose, causing the lignin to be initially softened. The chemical pretreatment agent (such as ammonia) penetrates into the interior of the lignin with the steam, breaks the phenylpropane structure of the lignin through alkaline hydrolysis, and reduces the molecular weight of the lignin.

[0009] S4 Secondary pressure boosting and blasting: After reaching the pressure holding time, saturated steam is introduced, and the pressure is rapidly increased to 1.5 - 1.8 MPa and then instantaneously relieved, causing the rice straw to burst out from the feeding port of the discharging device; the pressure is rapidly increased to 1.5 - 1.8 MPa in the secondary pressure boosting to form a large instantaneous pressure difference. This pressure difference is converted into huge expansion energy during instantaneous pressure relief, causing the volume of steam molecules inside the straw to expand sharply, generating an impact force similar to "implosion"; the fiber bundles are forcibly torn along the lignin - cellulose interface to form fine fiber filaments with a diameter of 5 - 20 μm, and the specific surface area is increased by 50% - 80% compared with that after the primary pressure boosting, significantly improving the enzymatic hydrolysis and microbial digestion efficiency, converting the straw from a "difficult - to - digest lignocellulose complex" into a "highly - feedable filamentous fiber matrix", and finally achieving multiple technical effects of increasing crude protein, optimizing fiber degradation rate and reducing energy consumption.

[0010] S5 Product collection: The blasted filamentous straw is collected into a storage tank through a pipeline and made into high - nutritional - value feed after drying.

[0011] Preferably, the urea added in the chemical pretreatment step is 0.5% - 6% of the dry weight of the straw.

[0012] Preferably, the addition amount of the urea is 2% - 6% of the dry weight of the straw.

[0013] Preferably, the ammonia water added in the chemical pretreatment step is 1% - 8% of the dry weight of the straw.

[0014] Preferably, the addition amount of the ammonia water is 3% - 8% of the dry weight of the straw.

[0015] Preferably, the steam pressure in the primary pressure boosting step is 0.9 - 1.1 MPa, and the pressure holding time is 180 - 300 seconds.

[0016] Preferably, the steam pressure in the secondary pressure boosting and blasting step is 1.7 - 1.8 MPa.

[0017] Preferably, the steam pressure in the primary pressure boosting step is 1.0 MPa, the pressure holding time is 250 seconds; the addition amount of urea in the chemical pretreatment step is 6% of the dry weight of the straw, and the steam pressure in the secondary pressure boosting and blasting step is 1.8 MPa and then instantaneously relieved.

[0018] A feed is prepared by the above - mentioned preparation method.

[0019] The outstanding effects of the present invention are: Compared with the prior art, the relative quality and relative feeding value of the rough rice straw feed are improved, and the crude protein content is increased.

[0020] Enhance the tearing effect of straw fibers, increase the specific surface area of the fibers, facilitate the degradation by cellulase and the attachment and colonization of rumen microorganisms, improve the degradation rate of straw cellulose, and enable cattle and sheep to more efficiently digest and utilize feed.

[0021] The energy consumption is reduced by 10%, which is suitable for large-scale production. Specific implementation manners

[0022] The following combines examples to further describe in detail the specific implementation manners of the present invention. The following examples are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0023] Example 1 First, crush rice straw into fragments with a length of 3 - 5 cm. It is preferably to use straw with better freshness. After crushing the raw materials, first perform primary iron removal to remove iron-containing impurities close to the surface of the belt in the raw materials, and then perform secondary iron removal to remove iron-containing impurities inside the raw materials.

[0024] Secondly, after completing iron removal, spray ammonia water accounting for 1% of the weight of the rice straw on the crushed rice straw, adjust the moisture content of the straw to 45%, and place it in a closed container for conventional ammoniation chemical treatment at room temperature. The sealing reaction time is 28 hours.

[0025] Thirdly, load the chemically pretreated rice straw into a steam explosion device, introduce saturated steam, maintain the pressure at 1.1 MPa, and keep the pressure for 180 seconds.

[0026] Fourthly, after reaching the pressure-holding time, introduce saturated steam, quickly increase the pressure to 1.6 MPa and then instantaneously relieve the pressure.

[0027] Fifthly, collect the exploded filamentous straw through a pipeline into a storage tank, and obtain high-nutrition feed after drying.

[0028] Example 2 First, crush rice straw into fragments with a length of 3 - 5 cm. It is preferably to use straw with better freshness. After crushing the raw materials, first perform primary iron removal to remove iron-containing impurities close to the surface of the belt in the raw materials, and then perform secondary iron removal to remove iron-containing impurities inside the raw materials.

[0029] Secondly, after completing iron removal, spray urea accounting for 2% of the weight of the rice straw on the crushed rice straw, adjust the moisture content of the straw to 35%, and place it in a closed container for conventional ammoniation chemical treatment at room temperature. The sealing reaction time is 32 hours.

[0030] Thirdly, load the chemically pretreated rice straw into a steam explosion device, introduce saturated steam, maintain the pressure at 0.9 MPa, and keep the pressure for 300 seconds.

[0031] Fourth, after reaching the holding pressure time, saturated steam is introduced, and the pressure is rapidly increased to 1.7 MPa and then instantaneously relieved.

[0032] Fifth, the shredded straw after blasting is collected into a storage tank through a pipeline, and high-nutrition feed is prepared after drying.

[0033] Example 3 First, the rice straw is crushed into fragments with a length of 3 - 5 cm. It is best to use straw with better freshness. The crushed raw material is first subjected to primary iron removal to remove the iron-containing impurities close to the surface of the belt in the raw material, and then secondary iron removal to remove the iron-containing impurities inside the raw material.

[0034] Second, after iron removal is completed, 3% ammonia water by weight of the rice straw is sprayed onto the crushed rice straw, the moisture content of the straw is adjusted to 55%, and it is placed in a sealed container for conventional ammoniation chemical treatment at normal temperature. The sealing reaction time is 36 hours.

[0035] Third, the rice straw after chemical pretreatment is loaded into a steam explosion device, saturated steam is introduced, and the pressure is maintained at 1.3 MPa for 80 seconds.

[0036] Fourth, after reaching the holding pressure time, saturated steam is introduced, and the pressure is rapidly increased to 1.5 MPa and then instantaneously relieved.

[0037] Fifth, the shredded straw after blasting is collected into a storage tank through a pipeline, and high-nutrition feed is prepared after drying.

[0038] Example 4 First, the rice straw is crushed into fragments with a length of 3 - 5 cm. It is best to use straw with better freshness. The crushed raw material is first subjected to primary iron removal to remove the iron-containing impurities close to the surface of the belt in the raw material, and then secondary iron removal to remove the iron-containing impurities inside the raw material.

[0039] Second, after iron removal is completed, 6% urea by weight of the rice straw is sprayed onto the crushed rice straw, the moisture content of the straw is adjusted to 40%, and it is placed in a sealed container for conventional ammoniation chemical treatment at normal temperature. The sealing reaction time is 40 hours.

[0040] Third, the rice straw after chemical pretreatment is loaded into a steam explosion device, saturated steam is introduced, and the pressure is maintained at 1.0 MPa for 250 seconds.

[0041] Fourth, after reaching the holding pressure time, saturated steam is introduced, and the pressure is rapidly increased to 1.8 MPa and then instantaneously relieved.

[0042] Fifth, the shredded straw after blasting is collected into a storage tank through a pipeline, and high-nutrition feed is prepared after drying.

[0043] Example 5 First, crush the rice straw into pieces with a length of 3 - 5 cm. It is best to use straw with better freshness. After crushing the raw material, first perform primary iron removal to remove iron impurities close to the surface of the belt in the raw material, and then perform secondary iron removal to remove iron impurities inside the raw material.

[0044] Secondly, after iron removal, spray 2% of urea by weight of the rice straw on the crushed rice straw, adjust the moisture content of the straw to 35%, and place it in a closed container for conventional ammoniation chemical treatment at room temperature. The sealing reaction time is 32 hours.

[0045] Thirdly, load the chemically pretreated rice straw into a steam explosion device, introduce saturated steam, maintain the pressure at 0.9 MPa, and keep the pressure for 300 seconds.

[0046] Fourthly, after reaching the pressure holding time, introduce saturated steam, quickly increase the pressure to 1.7 MPa and then instantaneously release the pressure.

[0047] Fifthly, collect the exploded filamentous straw into a storage tank through a pipeline, and obtain high - nutritional - value feed after drying.

[0048] Example 6 First, crush the rice straw into pieces with a length of 3 - 5 cm. It is best to use straw with better freshness. After crushing the raw material, first perform primary iron removal to remove iron impurities close to the surface of the belt in the raw material, and then perform secondary iron removal to remove iron impurities inside the raw material.

[0049] Secondly, after iron removal, spray 8% of ammonia water by weight of the rice straw on the crushed rice straw, adjust the moisture content of the straw to 30%, and place it in a closed container for conventional ammoniation chemical treatment at room temperature. The sealing reaction time is 48 hours.

[0050] Thirdly, load the chemically pretreated rice straw into a steam explosion device, introduce saturated steam, maintain the pressure at 0.8 MPa, and keep the pressure for 400 seconds.

[0051] Fourthly, after reaching the pressure holding time, introduce saturated steam, quickly increase the pressure to 1.6 MPa and then instantaneously release the pressure.

[0052] Fifthly, collect the exploded filamentous straw into a storage tank through a pipeline, and obtain high - nutritional - value feed after drying.

[0053] Example 7 First, crush the rice straw into pieces with a length of 3 - 5 cm. It is best to use straw with better freshness. After crushing the raw material, first perform primary iron removal to remove iron impurities close to the surface of the belt in the raw material, and then perform secondary iron removal to remove iron impurities inside the raw material.

[0054] Secondly, after iron removal, spray 0.5% of urea by weight of the rice straw on the crushed rice straw, adjust the moisture content of the straw to 60%, and place it in a closed container for conventional ammoniation chemical treatment at room temperature. The sealing reaction time is 24 hours.

[0055] Thirdly, load the chemically pretreated rice straw into a steam explosion device, introduce saturated steam, maintain the pressure at 1.4 MPa, and keep the pressure for 30 seconds.

[0056] Fourthly, after reaching the pressure holding time, introduce saturated steam, quickly increase the pressure to 1.7 MPa and then instantaneously release the pressure.

[0057] Fifthly, collect the shredded straw after explosion through a pipeline into a storage tank, and obtain high - nutritional - value feed after drying.

[0058] Comparative Example First, crush the rice straw into pieces with a length of 3 - 5 cm. It is best to use straw with better freshness. After crushing the raw material, first perform primary iron removal to remove iron impurities close to the surface of the belt in the raw material, and then perform secondary iron removal to remove iron impurities inside the raw material.

[0059] Secondly, after iron removal, spray 6% of urea by weight of the rice straw on the crushed rice straw, adjust the moisture content of the straw to 40%, and place it in a closed container for conventional ammoniation chemical treatment at room temperature. The sealing reaction time is 40 hours.

[0060] Thirdly, load the chemically pretreated rice straw into a steam explosion device, introduce saturated steam, maintain the pressure at 1.0 MPa, and release the pressure instantaneously after keeping the pressure for 250 seconds.

[0061] Fifthly, collect the shredded straw after explosion through a pipeline into a storage tank, and obtain feed after drying.

[0062] Test the feed prepared in the above Examples 1 - 6 and the comparative example in terms of tearing effect, crude protein content, neutral detergent fiber content, acid detergent fiber content, dry matter intake, dry matter digestibility, relative feeding value, etc. The data of each test item are shown in the following table:

[0063] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications made under the above assumptions should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing steam-exploded rice straw feed based on secondary pressure increase, characterized in that: The following steps are involved: S1 Raw material pretreatment: crush rice straw into strips of 3-5 cm and remove iron; S2 Chemical pretreatment: Add urea or ammonia water in a certain proportion of the dry weight of the straw to the crushed straw, adjust the moisture content to 30% - 60%, and seal the reaction for 24 - 48 hours; S3 Initial pressure increase: The pretreated straw is loaded into the steam explosion device, saturated steam is introduced, and the pressure is maintained at 0.8-1.4MPa for 30-400 seconds; S4 Secondary pressure-boosting blasting: After the pressure-holding time is reached, saturated steam is introduced to quickly increase the pressure to 1.5 - 1.8 MPa and then release the pressure instantly, causing the rice straw to explode out of the discharge device spray port; S5 Product collection: The shredded straw is collected into a storage tank through a pipeline and dried to produce high-nutritional-value feed.

2. The method for preparing rice straw feed by steam explosion based on secondary pressure boosting according to claim 1, characterized in that: In the chemical pretreatment step, 0.5% - 6% urea of ​​the dry weight of the straw is added.

3. The method for preparing rice straw feed by steam explosion based on secondary pressure boosting according to claim 2, characterized in that: The amount of urea added is 2% - 6% of the dry weight of the straw.

4. The method for preparing steam-exploded rice straw as feed based on secondary pressure boosting according to claim 1, characterized in that: In the chemical pretreatment step, 1% to 8% ammonia water is added based on the dry weight of the straw.

5. The method for preparing steam-exploded rice straw as feed based on secondary pressure boosting according to claim 4, characterized in that: The amount of ammonia water added is 3% - 8% of the dry weight of the straw.

6. The method for preparing steam-exploded rice straw as feed based on secondary pressure boosting according to claim 1, characterized in that: The steam pressure of the initial pressure-increasing step is 0.9-1.1 MPa, and the pressure-holding time is 180-300 seconds.

7. The method for preparing steam-exploded rice straw as feed based on secondary pressure boosting according to claim 1, characterized in that: The steam pressure in the secondary pressure-boosting explosion step is 1.7-1.8 MPa.

8. The method for preparing steam-exploded rice straw as feed based on secondary pressure boosting according to claim 1, characterized in that: The steam pressure in the initial pressure-raising step is 1.0 MPa, and the pressure-holding time is 250 seconds; the amount of urea added in the chemical pretreatment step is 6% of the dry weight of the straw, and the steam pressure in the secondary pressure-raising and blasting step is 1.8 MPa and then released instantly.

9. A feed, characterized in that: The rice straw is prepared by the method for preparing steam-exploded rice straw as feed based on secondary pressure increase as described in any one of claims 1 to 8.

Images