Soil improvement method and system based on straw indirect carbonization

Abstract

The invention discloses a soil improvement method and system based on straw indirect carbonization, and the method comprises the following steps: (A) collecting straw, and cutting the straw into straw particles; (B) extruding and breaking the epidermis of the straw particles; (C) heating the extruded straw particles by using microwaves to obtain puffed straw particles; and (D) carbonizing the surfaces of the puffed straw particles to obtain carbonized particles for being discharged into soil. The indirect carbonization mode of first wall breaking and puffing and then surface carbonization can significantly reduce energy consumed during carbonization, shorten the treatment time of the straw, and facilitate straw carbonization and field returning treatment of large-area soil, meanwhile, carbonized particles with the carbonized surface can provide enough biomass charcoal for the soil, and the soil quality is improved. Part of carbonized particles in the field do not need to be transported out due to the fact that the biomass charcoal exceeds the soil bearing capacity, and nutrient substances in the straw are well reserved by the carbonized particles.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural equipment, and in particular to a soil improvement method and system based on indirect carbonization of straw. Background Art

[0002] Straw is an important source of soil organic matter. The carbon content of straw charcoal is more than 65%, which has a good carbon fixation and emission reduction effect. Returning straw to the field can effectively improve soil properties, optimize soil functions, and improve the quality of cultivated land. Scientifically carrying out the recycling of crop straw is of great significance for stabilizing the agricultural ecological balance, improving the ecological environment, and alleviating resource constraints.

[0003] At present, there are two main ways to return straw to the fields. One is to collect the straw and move it out of the field for processing, and then add the processed material to the soil. For example, the straw is moved out of the field and returned to the field after fermentation. Another example is to carbonize the straw into biochar and then add it to the soil. However, this method of removing the straw from the field is bound to consume more manpower and material resources, has high costs, and is not suitable for large-scale straw processing. The other is to collect straw in the field and process the straw at the same time, so as to realize the in-situ return of the straw to the field. In recent years, carbonizing the straw into biochar and then directly returning it to the field has become a focus of attention. For example, patent CN102640617B discloses an integrated device for rice and wheat harvesting and straw carbonization and returning to the field, which can simultaneously complete rice and wheat harvesting and straw carbonization and returning to the field, saving transportation costs; patent CN112063401B discloses a mobile straw baking and carbonization treatment in-situ return method that integrates the collection, crushing, baking, carbonization and return of straw to the field, realizing the in-situ baking and carbonization of straw and returning it to the field.

[0004] However, due to the high moisture content in the straw, direct carbonization usually consumes a lot of energy. Therefore, although the transportation cost is saved, the time and energy consumption of carbonizing the straw are not significantly reduced. When applied to large-scale soil carbonization and returning to the field, it still faces the problems of high energy consumption and low efficiency. At the same time, direct carbonization will also consume the nutrients in the straw, resulting in low utilization rate of the nutrients in the straw, which is not conducive to soil improvement. Not only that, if all the collected straw is carbonized into biochar and returned to the field, when the biochar exceeds the bearing capacity of the soil, it will cause adverse effects. Therefore, the existing in-situ carbonization and returning to the field usually requires the removal of part of the biochar. Summary of the invention

[0005] One object of the present invention is to provide a soil improvement method based on indirect carbonization of straw, which comprises collecting straw and subjecting the collected straw to extrusion and microwave wall breaking to obtain puffed straw particles, and then carbonizing the surface of the puffed straw particles, so that the interior of the finally obtained carbonized particles can retain the main nutrients of the straw, and at the same time, the surface of the carbonized particles has certain carbonaceous properties and mechanical strength. On the basis of meeting the soil's demand for biomass charcoal, it can better provide nutrients for the soil, thereby effectively improving the soil improvement effect.

[0006] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0007] A soil improvement method based on indirect carbonization of straw comprises the following steps:

[0008] (A) collecting straw and cutting the straw into straw particles;

[0009] (B) squeezing and destroying the epidermis of the straw particles;

[0010] (C) heating the extruded straw particles using microwaves to obtain puffed straw particles;

[0011] (D) carbonizing the surface of the puffed straw particles to obtain carbonized particles for discharge into the soil.

[0012] In this technical solution, the straw collected in the field is directly processed into carbonized particles with carbonized surfaces and retained nutrients inside, and then the carbonized particles are discharged into the soil to achieve the purpose of improving the soil.

[0013] Specifically, in step (A), after picking up and collecting straw in the field, the straw is crushed and cut to obtain a plurality of straw particles. In one or more embodiments, the collection and cutting of the straw can be completed using an existing integrated carbonization and field return device.

[0014] In step (B), the surface of the straw particles is squeezed, for example, by using a screw extruder, so that the straw particles are continuously squeezed with each other and with the screw or the inner wall of the extruder, thereby destroying the integrity of the surface structure of the straw particles.

[0015] In step (C), microwaves are used to heat the straw particles with damaged skin, so that the moisture on the surface and inside of the straw particles is continuously converted into water vapor. Since the moisture on the surface evaporates faster, the moisture inside is continuously accumulated. When the pressure difference between the inside and outside of the skin reaches a certain level, the steam will break the skin of the straw particles and expand them, thereby obtaining expanded straw particles with damaged skin and porous mesh structure inside. At the same time, during the expansion process, nutrients such as sugar, protein, and minerals inside the straw particles are gradually released, the solubility of soluble protein and dietary fiber increases, and the activity of harmful microorganisms decreases.

[0016] In step (D), the surface of the puffed straw particles is carbonized, and the surface of the obtained carbonized particles forms a carbon structure containing a high ash content under the carbonization effect, and obtains certain carbon properties on the basis of retaining the original characteristics of the straw; at the same time, the interior of the carbonized particles is not carbonized, and still maintains a fluffy porous network structure, and the nutrients are not affected by carbonization.

[0017] Compared with the direct carbonization method of crushing the straw and then carbonizing it completely in the prior art, the indirect carbonization method of first breaking the wall and expanding it and then carbonizing the surface in this technical solution can significantly reduce the energy consumed during carbonization and shorten the processing time of the straw, which is conducive to the carbonization and field treatment of straw in large areas of soil. In addition, the carbonized particles with surface carbonization can provide sufficient biochar for the soil on the one hand, and there is no need to transport some carbonized particles out of the field because the biochar exceeds the soil carrying capacity. On the other hand, the carbonized particles also retain the nutrients in the straw well, and the internal porous structure formed by expansion is also conducive to decomposition by microorganisms, creating conditions for improving the utilization rate of the straw and accelerating the decomposition of the straw in the field.

[0018] Furthermore, in the step (B), the cut straw particles are first humidified at a temperature of 40 to 80°C, and then extruded to break the skin of the straw particles. In the present technical solution, the straw particles are first heated and humidified before being extruded and broken. By heating the straw particles, the straw particles can be more easily broken in the extrusion and wall breaking process, and since a certain initial temperature is already present in the microwave wall breaking process, the processing efficiency of microwave wall breaking can be effectively improved, and the energy consumption of microwave wall breaking can be reduced. By humidifying the straw particles, the water content on the surface and inside of the straw particles is further increased, for example, reaching more than 40%. The skin of the straw particles with a higher moisture content is more easily broken in the subsequent extrusion and wall breaking process, which is beneficial to the puffing of the straw particles in the microwave wall breaking process. At the same time, the increase in moisture inside the straw particles will effectively enhance the pumping effect inside and outside the straw particles in the microwave wall breaking process, making the straw particles easier to puff, and further improving the processing efficiency of the puffed straw particles.

[0019] Furthermore, in the step (C), the temperature of microwave heating of the straw particles is 90 to 160°C, and the heating time is 3 to 10 minutes. In the present technical solution, the temperature of microwave heating should not be too low, otherwise it will not only fail to effectively affect the activity of harmful microorganisms in the straw, but also the moisture of the straw itself or the moisture humidified in the pretreatment step will be detrimental to the carbonization of the subsequent puffed straw particles; at the same time, the temperature of microwave heating should not be too high, otherwise the nutrients in the straw will easily be lost with the water vapor or react and lose nutrition at high temperature. Therefore, in the present technical solution, preferably, the temperature of microwave heating of the straw particles is controlled at 90 to 160°C, so that while achieving better puffing of the straw particles, the discharged gas also has a certain temperature, and the discharged gas can be reused in the pretreatment device to heat the collected straw particles, thereby reducing the overall energy consumption of the treatment process.

[0020] Furthermore, in step (D), the puffed straw particles roll through the flame, and the flame burns the surface of the puffed straw particles, so that the surface of the puffed straw particles is evenly carbonized. In this technical solution, the puffed straw particles roll through the flame so that the flame can quickly burn all parts of the surface of the puffed straw particles, while avoiding burning the inside of the puffed straw particles, so that the surface of the puffed straw particles is quickly and evenly carbonized. In some preferred embodiments, the burning time of the flame on the surface of the puffed straw particles is no more than 5 seconds. In one or more embodiments, a ceramic microporous plate is used as a platform for the rolling of the puffed straw particles, and a flame is arranged under the ceramic microporous plate. The flame passes through each micropore on the ceramic microporous plate to evenly burn the rolling puffed straw particles, so that the surface is carbonized.

[0021] Furthermore, in the step (D), the puffed straw particles are purged with airflow before the surface of the puffed straw particles is carbonized. In the present technical solution, the puffed straw particles are purged with airflow after being broken by microwaves to remove the residue on the puffed straw particles, and more importantly, the airflow can further reduce the moisture of the puffed straw particles, especially the moisture on the surface of the puffed straw particles, so that in the subsequent flame carbonization process, the surface of the puffed straw particles can be more easily carbonized, and the energy consumption of carbonization is lower; not only that, the airflow can recycle part of the moisture to the pretreatment device, so as to use this part of the moisture to humidify the collected straw particles, thereby reducing the overall energy consumption of the treatment process.

[0022] Furthermore, in the step (D), the obtained carbonized particles are cooled, and the bacterial agent is sprayed on the cooled carbonized particles. The surface temperature of the carbonized particles is relatively high after burning. Therefore, in order to spray the bacterial agent on them, the carbonized particles need to be cooled first. There are many ways to cool the carbonized particles, such as using air flow or water flow to reduce their temperature. In some preferred embodiments, water flow is sprayed on the carbonized particles to reduce their temperature and increase their humidity to facilitate the survival of the bacterial agent. Afterwards, the bacterial agent is sprayed on the cooled carbonized particles. The carbonized porous structure on the surface of the carbonized particles and the expanded porous mesh structure inside can provide a shelter for the growth and reproduction of the bacterial community, which is beneficial to the immobilization of the bacterial community, and then the advantages of the bacterial community can be brought into play after the carbonized particles are discharged into the soil, thereby improving the soil improvement effect.

[0023] Another object of the present invention is to provide a soil improvement system, which utilizes an extrusion wall breaking device, a microwave wall breaking device and an indirect carbonization device to in-situ process the collected straw, and thereby obtains indirect carbonized particles with a carbonized surface and a porous mesh structure inside, which can not only meet the soil's demand for biochar, but also provide the soil with more nutrients from the straw, thereby improving the soil structure.

[0024] The above-mentioned object of the present invention is achieved by the following technical solutions:

[0025] A soil improvement system based on indirect carbonization of straw, comprising a frame, a walking device is arranged on the frame, and the frame is also provided with:

[0026] A collecting and cutting device, used for collecting straw and cutting the straw into straw particles;

[0027] A pre-processing device, connected to the collecting and cutting device via a first conveying device, the pre-processing device being used to heat and humidify the straw particles;

[0028] An extrusion wall-breaking device, connected to the pretreatment device, and used for extruding the straw particles and destroying the surface of the straw particles;

[0029] One or more microwave wall-breaking devices are connected to the extrusion wall-breaking device, and the microwave wall-breaking device is used for microwave heating of the extruded straw particles to obtain puffed straw particles;

[0030] An indirect carbonization device is connected to the microwave wall-breaking device via a second transmission device, and the indirect carbonization device is used to carbonize the surface of the puffed straw particles to obtain carbonized particles for discharge into the soil.

[0031] Similar to the existing straw carbonization device, the soil improvement system provided in the present technical solution also includes a frame and a walking device to achieve movement in the field, collection and in-situ carbonization of straw.

[0032] Different from the existing straw carbonization devices, the soil improvement system in this technical solution adopts a collecting and cutting device, a pretreatment device, an extrusion breaking device, a microwave breaking device and an indirect carbonization device to process the collected straw into carbonized particles with carbonized surface and porous mesh structure inside.

[0033] Specifically, in the technical solution, after collecting the straw, the collecting and cutting device crushes and cuts the straw to obtain straw particles in sections. The output end of the collecting and cutting device is connected to the input end of the first conveying device, and the output end of the first conveying device is connected to the pre-processing device. Therefore, the cut straw particles are transferred to the pre-processing device through the first conveying device for pre-processing.

[0034] In the technical scheme, the pretreatment device is used to heat and humidify the straw particles. The temperature and humidity of the treated straw particles are increased, which is conducive to the subsequent extrusion wall breaking device and microwave wall breaking device to process the straw particles, strengthen the degree of skin damage of the straw particles, and enhance the puffing effect of microwave heating. In some preferred embodiments, the pretreatment device is provided with a stirring mechanism, a heating mechanism and a humidifying mechanism. After the straw particles enter the pretreatment device, moisture is introduced into the straw particles through the humidifying mechanism, the heating mechanism increases the temperature of the straw particles, and then the stirring mechanism is used to make the straw particles fully heated and humidified, and finally discharged through the discharge port and enter the extrusion wall breaking device.

[0035] In the present technical solution, the extrusion wall-breaking device preferably adopts the structure of a screw extruder, and utilizes the rotation of the screw to drive the straw particles to move from the feed port to the discharge port. During the movement, the straw particles, the straw particles and the screw, and the straw particles and the inner wall of the extruder are continuously squeezed to destroy the integrity of the surface of the straw particles. In one or more preferred embodiments, the extrusion wall-breaking device adopts a screw extruder with a gradual screw pitch, and the screw pitch gradually decreases from the feed port to the discharge port to reduce the space between adjacent spiral blades, strengthen the extrusion of the straw particles, and increase the degree of damage to the surface of the straw particles.

[0036] In the present technical solution, the discharge port of the extrusion wall breaking device is connected to the feed port of one or more microwave wall breaking devices. In some embodiments, the microwave wall breaking device may also adopt the structure of a screw extruder. At the same time, a plurality of magnetrons are arranged on the outer wall of the shell of the screw extruder. The microwaves generated by the magnetrons enter the interior of the microwave wall breaking device through the through holes arranged on the outer wall and the mica sheets located in the through holes, and heat the straw particles with the destroyed surface to obtain puffed straw particles with a porous mesh structure formed inside.

[0037] In the technical solution, the discharge port of one or more microwave wall-breaking devices is connected to the input end of the second conveying device, and the output end of the second conveying device is connected to the indirect carbonization device. The indirect carbonization device carbonizes the surface of the puffed straw particles, and the surface of the obtained carbonized particles forms a carbonaceous structure with a high ash content under the carbonization effect, and obtains certain carbonaceous properties on the basis of retaining the original characteristics of the straw. In addition, the interior of the carbonized particles is not carbonized, and still maintains a fluffy porous network structure, and the nutrients are not affected by carbonization.

[0038] Furthermore, the indirect carbonization device is provided with a carbonization mechanism, a cooling mechanism and a microbial agent adding mechanism from top to bottom in sequence, wherein the carbonization mechanism is used to burn the surface of the puffed straw particles, the cooling mechanism is used to spray a cooling liquid onto the carbonized particles, and the microbial agent adding mechanism is used to spray a microbial agent onto the carbonized particles after the temperature has been reduced. In this technical solution, the indirect carbonization device is provided with a carbonization mechanism, a cooling mechanism and a microbial agent adding mechanism from top to bottom in an inclined manner. In some preferred embodiments, the carbonization mechanism includes a carbonization plate, such as a ceramic microporous plate, and the top of the carbonization plate is used for rolling the puffed straw particles, and a flame head is provided below the carbonization plate to spray flames to burn the surface of the rolling puffed straw particles; the cooling mechanism includes a first guide plate, which is also provided with a plurality of through holes, so that when the carbonized particles roll on the first guide plate, the spray head below the first guide plate can spray cooling liquid to reduce the temperature of the carbonized particles; the bacterial agent adding mechanism includes a second guide plate, and the second guide plate has a similar structure to the first guide plate. When the cooled carbonized particles roll on the second guide plate, the bacterial agent spray head below the second guide plate sprays the bacterial agent onto the cooled carbonized particles, and finally obtains carbonized particles loaded with bacterial agent.

[0039] Furthermore, a reflux pipe is connected between the indirect carbonization device and the pretreatment device. After the straw particles are processed by the extrusion wall breaking device and the microwave wall breaking device, the high-temperature gas generated during the processing carries a certain amount of moisture and finally enters the carbonization device. In this technical solution, a reflux pipe is set between the indirect carbonization device and the pretreatment device, and a part of the high-temperature gas in the indirect carbonization device can be reintroduced into the pretreatment device through the reflux pipe by a blower, so as to heat and humidify the straw particles in the pretreatment device, thereby improving the utilization efficiency of heat and moisture and effectively reducing the energy consumption of the system.

[0040] Furthermore, it also includes a blower, which is used to deliver airflow into the second conveying device. In this technical solution, the blower delivers airflow into the second device through a pipeline connected to the inside of the second conveying device, and uses the airflow to sweep the puffed straw particles moving in the second conveying device to reduce the moisture and residue on the surface of the puffed straw particles, avoid excess moisture increasing carbonization energy consumption and prolonging carbonization time, which is conducive to improving the subsequent carbonization effect of the puffed straw particles. At the same time, this part of moisture can also be transported to the pretreatment device again through the reflux pipeline to further reduce the energy consumption of the system.

[0041] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0042] 1. The indirect carbonization method of first breaking the wall and expanding and then carbonizing the surface can significantly reduce the energy consumed during carbonization and shorten the processing time of straw, which is conducive to the carbonization and field treatment of straw in large areas of soil;

[0043] 2. The carbonized particles obtained by indirect carbonization of the present invention are only carbonized on the surface, so they can provide sufficient biochar for the soil, but there is no need to transport some carbonized particles out of the field because the biochar exceeds the soil carrying capacity. At the same time, the carbonized particles also retain the nutrients in the straw well, and the internal porous structure formed by puffing is also conducive to being decomposed by microorganisms, creating conditions for improving the utilization rate of the straw and accelerating the decomposition of the straw in the field;

[0044] 3. The present invention heats the straw particles, which makes them easier to break in the extrusion breaking process and reduces the energy consumption of microwave breaking. Humidifying the straw particles is conducive to breaking the surface of the straw particles in the subsequent extrusion breaking process, promoting the puffing of the straw particles in the microwave breaking process. At the same time, the increase in moisture inside the straw particles will effectively enhance the pumping effect inside and outside the straw particles in the microwave breaking process, making the straw particles easier to puff, and further improving the processing efficiency of puffed straw particles.

[0045] 4. The present invention uses airflow to purge the puffed straw particles before carbonizing the surface of the puffed straw particles, which can further reduce the moisture and residue of the puffed straw particles, especially the moisture on the surface of the puffed straw particles, so that in the subsequent flame carbonization process, the surface of the puffed straw particles can be more easily carbonized, and the energy consumption of carbonization is lower;

[0046] 5. The present invention provides a soil improvement system, which utilizes an extrusion wall breaking device, a microwave wall breaking device and an indirect carbonization device to process the collected straw in situ, and the obtained indirect carbonized particles with carbonized surface and porous network structure inside can not only meet the soil's demand for biochar, but also provide the soil with more nutrients from the straw and improve the soil structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0048] Figure 1 It is a flowchart of a soil improvement method in a specific embodiment of the present invention;

[0049] Figure 2 It is a structural schematic diagram of a soil improvement system in a specific embodiment of the present invention;

[0050] Figure 3 It is a schematic structural diagram of a microwave wall breaking device in a specific embodiment of the present invention;

[0051] Figure 4 It is a schematic structural diagram of an extrusion wall-breaking device in a specific embodiment of the present invention;

[0052] Figure 5 It is a structural schematic diagram of a pre-processing device in a specific embodiment of the present invention;

[0053] Figure 6 It is a structural schematic diagram of an indirect carbonization device in a specific embodiment of the present invention;

[0054] Figure 7 It is a schematic diagram of the adjustable mechanism of the carbonization plate of the indirect carbonization device in a specific embodiment of the present invention.

[0055] Marks and corresponding parts names in the attached drawings:

[0056] 1-collecting and cutting device, 2-extrusion wall breaking device, 21-second shell, 22-second screw, 23-second motor, 24-second feed port, 25-second discharge port, 3-microwave wall breaking device, 31-first shell, 32-first screw, 33-magnetron, 34-through hole, 35-first motor, 36-first feed port, 37-first discharge port, 4-indirect carbonization device, 41-fourth shell, 42-fourth feed port, 43-exhaust port, 44-fourth discharge port, 45-carbonization plate, 46-flame head, 47-airflow regulating valve, 48-first guide plate, 49-first Second water tank, 410-second liquid spray head, 411-bacteria agent box, 412-second guide plate, 413-bacteria agent spray head, 414-hydraulic cylinder, 415-bearing, 416-slider, 417-chute, 5-pretreatment device, 51-third shell, 52-third motor, 53-stirring paddle, 54-blocking plate, 55-third feed port, 56-third discharge port, 57-first water tank, 58-first liquid spray head, 6-first conveying device, 7-second conveying device, 71-jet pipe, 8-blower, 9-reflux pipe, 10-traveling device, 11-loosening plow device, 12-frame. DETAILED DESCRIPTION

[0057] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0058] In the description of the present invention, it should be understood that the terms "front", "rear", "left", "right", "up", "down", "vertical", "horizontal", "high", "low", "inside", "outside", etc., indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the scope of protection of the present invention.

[0059] Embodiment 1:

[0060] like Figure 1 A soil improvement method based on indirect carbonization of straw is shown, comprising the following steps:

[0061] (A) collecting straw and cutting the straw into straw particles;

[0062] (B) squeezing and destroying the epidermis of the straw particles;

[0063] (C) heating the extruded straw particles using microwaves to obtain puffed straw particles;

[0064] (D) carbonizing the surface of the puffed straw particles to obtain carbonized particles for discharge into the soil.

[0065] Compared with the direct carbonization method in the prior art of crushing the straw and then carbonizing it completely, the indirect carbonization method of first breaking the wall and expanding it and then carbonizing the surface in this embodiment can significantly reduce the energy consumed during carbonization and shorten the straw processing time, which is beneficial to the carbonization and return of straw to the field in large areas of soil.

[0066] In some preferred embodiments, in the step (B), the cut straw particles are first humidified at a temperature of 40 to 80°C, and then squeezed to break the skin of the straw particles. In one or more embodiments, a pretreatment device can be provided before the extrusion wall breaking process, and the collected straw particles are stirred, heated, and humidified by the pretreatment device, and the extrusion wall breaking process is performed after the straw particles reach the required humidity and temperature. In one or more embodiments, the pressure of the extrusion wall breaking process can be adjusted to gradually increase from the feed port to the discharge port to further improve the effect of damaging the skin of the straw particles.

[0067] In some preferred embodiments, in the step (C), the temperature of microwave heating the straw particles is 90-160° C., and the heating time is 3-10 minutes.

[0068] In some preferred embodiments, in step (D), the puffed straw particles roll through a flame, and the flame burns the surface of the puffed straw particles, so that the surface of the puffed straw particles is evenly carbonized. In some embodiments, the flame burns the surface of the puffed straw particles for no more than 5 seconds.

[0069] In some preferred embodiments, in the step (D), the puffed straw particles are purged with airflow before the surface of the puffed straw particles is carbonized. In one or more embodiments, the temperature of the purge airflow is preferably 20-30° C. to reduce the loss of volatile nutrients in the puffed straw particles, and at the same time, the entire puffed straw particles, especially the interior, are cooled, which is conducive to the subsequent spraying of active bacterial agents on the carbonized particles.

[0070] In some preferred embodiments, in the step (D), the obtained carbonized particles are cooled, and the bacterial agent is sprayed on the cooled carbonized particles. The carbonized porous structure on the surface of the carbonized particles and the expanded porous mesh structure inside can provide a shelter for the growth and reproduction of the bacterial community, which is conducive to the immobilization of the bacterial community, and then the advantages of the bacterial community can be brought into play after the carbonized particles are discharged into the soil, thereby improving the soil improvement effect.

[0071] Embodiment 2:

[0072] like Figure 2 The soil improvement system based on indirect carbonization of straw shown in the figure comprises a frame 12, on which a walking device 10 is arranged, and on which:

[0073] The collecting and cutting device 1 is used to collect straw and cut the straw into straw particles;

[0074] A pre-processing device 5, connected to the collecting and cutting device 1 via a first conveying device 6, the pre-processing device 5 is used to heat and humidify the straw particles;

[0075] An extrusion wall-breaking device 2, connected to the pretreatment device 5, and used for extruding the straw particles and destroying the surface of the straw particles;

[0076] One or more microwave wall-breaking devices 3 are connected to the extrusion wall-breaking device 2, and the microwave wall-breaking device 3 is used for microwave heating of the extruded straw particles to obtain puffed straw particles;

[0077] The indirect carbonization device 4 is connected to the microwave wall-breaking device 3 via a second transmission device 7. The indirect carbonization device 4 is used to carbonize the surface of the puffed straw particles to obtain carbonized particles for discharge into the soil.

[0078] During operation, after collecting the straw, the collecting and cutting device crushes and cuts the straw to obtain straw particles in sections. The collected straw particles are output to the pretreatment device through the first conveying device. The pretreatment device is used to heat and humidify the straw particles. The temperature and humidity of the treated straw particles increase, which is conducive to the subsequent extrusion wall breaking device and microwave wall breaking device to process the straw particles, strengthen the degree of epidermal damage of the straw particles, and enhance the puffing effect of microwave heating. Afterwards, the epidermal integrity of the straw particles is destroyed during the process of conveying the straw particles by the extrusion wall breaking device. Subsequently, the microwave wall breaking device generates microwaves to radiate the straw particles inside, heats the straw particles with the damaged epidermis, and obtains puffed straw particles with a porous mesh structure formed inside. Next, the puffed straw particles enter the indirect carbonization device, which carbonizes the surface of the puffed straw particles without affecting the porous mesh structure inside. On the one hand, the carbonized particles with carbonized surface can provide sufficient biochar for the soil, eliminating the need to transport some carbonized particles out of the field because the biochar exceeds the soil carrying capacity. On the other hand, the carbonized particles also retain the nutrients in the straw well, and the internal porous structure formed by puffing is conducive to decomposition by microorganisms, creating conditions for improving the utilization rate of the straw and accelerating the decomposition of the straw in the field.

[0079] In one or more embodiments, the first and second conveying devices are screw conveyors.

[0080] In some embodiments, Figure 2 As shown, a reflux pipe 9 is connected between the indirect carbonization device 4 and the pretreatment device 5. A part of the high-temperature gas in the indirect carbonization device can be reintroduced into the pretreatment device through the reflux pipe by a blower to heat and humidify the straw particles in the pretreatment device, thereby improving the utilization efficiency of heat and water and effectively reducing the energy consumption of the system.

[0081] In some embodiments, a blower 8 is further included, and the blower 8 is used to deliver airflow into the second conveying device 7. In one or more embodiments, the temperature of the airflow is preferably 20-30°C.

[0082] Embodiment 3:

[0083] On the basis of the above-mentioned embodiment, the interior of the indirect carbonization device 4 is provided with a carbonization mechanism, a cooling mechanism and a bacterial agent adding mechanism from top to bottom, wherein the carbonization mechanism is used to burn the surface of the puffed straw particles, the cooling mechanism is used to spray cooling liquid onto the carbonized particles, and the bacterial agent adding mechanism is used to spray bacterial agent onto the carbonized particles after cooling.

[0084] In some preferred embodiments, Figure 6 As shown, the indirect carbonization device 4 includes a fourth shell 41, which is provided with a fourth feed port 42 for connecting to the output end of the second conveying device, a fourth discharge port 44 for discharging carbonized particles with bacterial agent, and an exhaust port 43 connected to the return pipe.

[0085] The indirect carbonization device 4 is provided with a carbonization mechanism, a cooling mechanism and a bacterial agent adding mechanism from top to bottom. The carbonization mechanism includes a carbonization plate 45 inclined toward the center of the fourth shell, such as a ceramic microporous plate, and a flame head 46 is provided below the carbonization plate 45. The flame head 46 is used to spray flames toward the carbonization plate 45, and the flames burn the puffed straw particles rolling on the carbonization plate 45 through the micropores on the carbonization plate 45. In one or more embodiments, an air flow regulating valve is provided between the flame head 46 and the air source to adjust the size of the flame sprayed by the flame head, thereby adjusting the carbonization effect. The cooling mechanism includes a first guide plate 48 inclined toward the center of the fourth shell, a first through hole is provided on the first guide plate 48, and a second liquid spray head 410 is provided below the first guide plate 48. The second liquid spray head 410 is connected to the second water tank 49 to realize that the cooling water in the second water tank 49 is pressed to the second liquid spray head 410, and sprayed on the carbonized particles to reduce the temperature of the carbonized particles. The microbial agent adding mechanism includes a second guide plate 412 inclined toward the center of the fourth shell, a second through hole is provided on the second guide plate 412, a microbial agent nozzle 413 is provided below the second guide plate 412, and the microbial agent nozzle 413 is connected to the microbial agent box 411 to press the microbial agent in the microbial agent box to the microbial agent nozzle 413 and spray it to the carbonized particles after cooling, and finally the carbonized particles carrying the microbial agent are discharged to the soil through the fourth discharge port 44.

[0086] In one or more embodiments, the length and quantity of the carbonization mechanism, cooling mechanism, and microbial agent adding mechanism can be set according to actual needs to ensure that the surface of the puffed straw particles is fully carbonized, the carbonized particles are fully cooled and carry the expected content of microbial agent.

[0087] In some embodiments, the inclination angle of the carbonized plate is adjustable. Figure 7As shown, a hydraulic cylinder 414 is provided on the fourth housing 41, and a bearing 415 hinged to the first end of the carbonized plate 45 is provided on the output end of the hydraulic cylinder. The hydraulic cylinder can push the first end of the carbonized plate 415 to move toward or away from the center of the first housing 41; a slider 416 is connected to the second end of the carbonized plate 45, and the slider 416 can move vertically up and down along a slide groove 417 provided on the inner wall of the fourth housing 41. The reciprocating movement of the hydraulic cylinder 414 can drive the first end of the carbonized plate 415 to move, thereby making the inclination angle of the carbonized plate adjustable, thereby changing the carbonization time.

[0088] Embodiment 4:

[0089] On the basis of the above embodiment, the pretreatment device 5 includes a third housing 51, and a material baffle plate 54 that can be opened or closed is arranged in the third housing 51. A third motor 52 is arranged outside the third housing 51, and the output end of the third motor 52 is connected to a stirring paddle 53 located in the third housing 51, and the stirring paddle 53 is located above the material baffle plate 54. The third housing 51 is also connected to the indirect carbonization device 4 through the reflux pipe 9.

[0090] During operation, the baffle plate is closed to collect a sufficient amount of straw particles, and the high-temperature and water-containing gas enters the baffle plate 54 through the reflux pipe 9 and contacts the straw particles. The stirring paddle drives the straw particles to rotate so that they are fully heated and humidified. Then the baffle plate is opened, and the straw particles are discharged to the extrusion wall breaking device 2 through the third discharge port 56.

[0091] In one or more embodiments, a first water tank 57 is also provided on the third shell 51, and the first water tank 57 is connected to a first liquid spray head 58 located in the third shell 51, so that when the moisture carried in the high-temperature gas is insufficient, the stored liquid is sprayed onto the straw particles through the first liquid spray head, thereby assisting in increasing the moisture content of the straw particles.

[0092] Embodiment 5:

[0093] Based on the above embodiments, Figure 3 As shown, the microwave wall breaking device 3 includes a first shell 31, on which a first feed port 36 and a first discharge port 37 are provided. A first screw 32 is provided inside the first shell 31, and the first screw 32 rotates when driven by a first motor 35, driving the internal straw particles to move from the feed port toward the discharge port.

[0094] A magnetron 33 is disposed on the outer wall of the first shell 31, and a microwave emitting end of the magnetron 33 is connected to the first shell 31 through a through hole 34 disposed on the first shell 31, and a mica sheet is disposed in the through hole 34. During the movement of the straw particles, the microwaves generated by the magnetron 33 enter the first shell 31 through the through hole to radiate and heat the straw particles.

[0095] Embodiment 6:

[0096] Based on the above embodiments, Figure 4 As shown, the extrusion wall breaking device 2 includes a second shell 21, on which a second feed port 24 and a second feed port 25 are provided, and a second screw 22 is provided inside the second shell 21. The second screw 22 rotates when driven by a second motor 23, driving the internal straw particles to move from the feed port toward the discharge port. During the movement, the straw is continuously squeezed with the straw, the straw and the screw, and the straw and the inner wall of the shell to destroy the surface of the straw particles.

[0097] In some preferred embodiments, the pitch of the second screw gradually decreases from the second feed port 24 to the second discharge port 25, so that the extrusion force on the straw particles during the movement is continuously increased.

[0098] The terms "first", "second", "third", "fourth", etc. (e.g., first discharge port, second discharge port, third discharge port, fourth discharge port, first water tank, second water tank, etc.) used in the present invention are only used to distinguish the corresponding components for the sake of clarity of description, and are not intended to limit any order or emphasize importance, etc. In addition, the term "connected" used in the present invention may be directly connected or indirectly connected via other components unless otherwise specified.

[0099] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A soil improvement method based on indirect carbonization of straw, characterized in that: The following steps are involved: (A) collecting straw and cutting the straw into straw particles; (B) squeezing and destroying the epidermis of the straw particles; (C) heating the extruded straw particles using microwaves to obtain puffed straw particles; (D) carbonizing the surface of the puffed straw particles to obtain carbonized particles for discharge into the soil.

2. A soil improvement method based on indirect carbonization of straw according to claim 1, characterized in that: In the step (B), the cut straw particles are first humidified at a temperature of 40 to 80° C., and then squeezed to destroy the surface of the straw particles.

3. The soil improvement method based on indirect carbonization of straw according to claim 1, characterized in that: In the step (C), the temperature of microwave heating the straw particles is 90 to 160° C., and the heating time is 3 to 10 minutes.

4. The soil improvement method based on indirect carbonization of straw according to claim 1, characterized in that: In the step (D), the puffed straw particles roll through a flame, and the flame burns the surface of the puffed straw particles, so that the surface of the puffed straw particles is evenly carbonized.

5. The soil improvement method based on indirect carbonization of straw according to claim 4, characterized in that: In the step (D), before carbonizing the surface of the puffed straw particles, the puffed straw particles are purged with airflow.

6. The soil improvement method based on indirect carbonization of straw according to claim 4, characterized in that: In the step (D), the obtained carbonized particles are cooled, and a bacterial agent is sprayed on the cooled carbonized particles.

7. A soil improvement system based on indirect carbonization of straw, comprising a frame (12), on which a walking device (10) is arranged, characterized in that: The frame (12) is also provided with: A collecting and cutting device (1) is used to collect straw and cut the straw into straw particles; A pre-processing device (5) connected to the collecting and cutting device (1) via a first conveying device (6), the pre-processing device (5) being used for heating and humidifying the straw particles; An extrusion wall-breaking device (2) is connected to the pretreatment device (5), and the extrusion wall-breaking device (2) is used to extrude the straw particles and destroy the surface of the straw particles; One or more microwave wall-breaking devices (3) are connected to the extrusion wall-breaking device (2), and the microwave wall-breaking device (3) is used for microwave heating the extruded straw particles to obtain puffed straw particles; The indirect carbonization device (4) is connected to the microwave wall-breaking device (3) via a second transmission device (7), and the indirect carbonization device (4) is used to carbonize the surface of the puffed straw particles to obtain carbonized particles for discharge into the soil.

8. The soil improvement system based on indirect carbonization of straw according to claim 7, characterized in that: The indirect carbonization device (4) is provided with a carbonization mechanism, a cooling mechanism and a bacterial agent adding mechanism in sequence from top to bottom, wherein the carbonization mechanism is used to burn the surface of the puffed straw particles, the cooling mechanism is used to spray cooling liquid onto the carbonized particles, and the bacterial agent adding mechanism is used to spray bacterial agent onto the carbonized particles after cooling.

9. The soil improvement system based on indirect carbonization of straw according to claim 7, characterized in that: A reflux pipeline (9) is connected between the indirect carbonization device (4) and the pretreatment device (5).

10. The soil improvement system based on indirect carbonization of straw according to claim 7, characterized in that: It also comprises a blower (8), wherein the blower (8) is used to deliver airflow into the second conveying device (7).

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