Organic fertilizer particle surface microorganism coating process and coating device

Abstract

The invention relates to the field of organic fertilizer production, in particular to an organic fertilizer particle surface microorganism coating process and a coating device. Efficient preheating and stable conveying of particles are achieved through a Venturi type hot air feeding mechanism, stable hot air is formed through a centrifugal fan and an air heater, negative pressure material suction is combined with a Venturi tube, heat exchange and moisture removal of the particles are rapidly completed, gas-solid separation is achieved through a cyclone separator, and clean conveying of the particles is guaranteed. Three-stage layered spraying is adopted in the kettle coating stage, specifically, a biocompatible adhesive is firstly coated to build a base layer, then composite bacterial slurry containing a protective agent and a nutritional agent is sprayed to fix microorganisms, finally, an inert protective layer is coated to prevent adhesion and ultraviolet damage, in the process, due to the unique design of a main shoveling plate and an auxiliary shoveling plate, particles form complex movement, a film coating blind area is eliminated, and the film coating effect is improved. And precise multi-section spraying is matched, and it is ensured that each particle is evenly coated with a film. And in the discharging stage, the finished products are discharged in order by sliding the baffle.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of organic fertilizer production, in particular to a process and device for coating microorganisms on the surface of organic fertilizer particles. BACKGROUND

[0002] Organic fertilizer is an important production material for developing green agriculture, but its slow fertilizer efficiency and unbalanced nutrient ratio can be improved by combining specific functional microorganisms (such as nitrogen-fixing bacteria, phosphorus-dissolving bacteria, potassium-dissolving bacteria, and antagonistic bacteria) with organic fertilizer, which can significantly improve fertilizer utilization rate, promote crop growth, inhibit soil-borne diseases, and achieve "reducing the amount of chemical fertilizers and increasing their efficiency". Therefore, developing efficient and stable microbial organic fertilizer is a current research hotspot and industrial direction.

[0003] The current common microbial fertilizer preparation methods mainly include "internal mixing method" and "surface coating method". The "surface coating method" refers to first preparing organic fertilizer core particles, then spraying microbial liquid on the surface of the particles, and finally drying. Compared with the internal mixing method, the surface coating method avoids the direct damage of granulation and high temperature to microorganisms.

[0004] However, the existing equipment (such as a common roller spraying machine) has a spraying blind area, and the particles are prone to sticking together, resulting in uneven coating thickness, some particles not being stuck, and some being "stuck", which affects the product quality stability. SUMMARY

[0005] To overcome the deficiencies in the above background art, the present application provides a process and device for coating microorganisms on the surface of organic fertilizer particles.

[0006] The present application adopts the following technical solutions: A device for coating microorganisms on the surface of organic fertilizer particles, characterized in that the coating device comprises: A Venturi hot air feeding mechanism, which comprises a centrifugal fan, an air heater, a Venturi tube, a cyclone separator, and a hopper. The air outlet of the centrifugal fan is connected to the heating inlet of the air heater, the heating outlet of the air heater is connected to the converging section of the Venturi tube, the diverging section of the Venturi tube is connected to the separation inlet of the cyclone separator, and the throat section of the Venturi tube is connected to the discharge port of the hopper through a suction pipe. The coating kettle comprises a kettle body, main scraping plates, auxiliary scraping plates, an upper end cover, a lower end cover, a spraying pipe and a baffle, a plurality of main scraping plates are uniformly distributed along the inner wall of the kettle body in the circumferential direction, the elongated direction of the main scraping plates is parallel to the axial direction of the kettle body, the cross section of the main scraping plates is a curved spoon shape, the back surface of the main scraping plates with a large bending radius is provided with a plurality of inclined auxiliary scraping plates, the auxiliary scraping plates extend from the back surface, the upper end cover and the lower end cover at both ends of the kettle body are fixedly installed on a rack, the kettle body is obliquely arranged on the rack and can rotate relative to the upper end cover, the upper end cover at the high end of the oblique kettle body is provided with a feeding opening and is connected with a discharge opening of the cyclone separator for feeding, the lower end cover at the low end of the oblique kettle body is provided with a discharge opening for discharging, and the lower end cover is provided with a slidable baffle for controlling the opening and closing of the discharge opening, the spraying pipe penetrates through the upper end cover and the lower end cover and is provided with a plurality of atomizing nozzles for spraying coating materials.

[0007] As a further improvement, the air heater comprises a heating shell and a heating pipe, a heating cavity is arranged in the heating shell, heating inlets and outlets are arranged at both ends of the heating shell and are communicated with the heating cavity, a plurality of heating pipes are arranged in the heating cavity and are controlled by a heating controller mounted on the heating pipes, and the heating pipes are used for heating air flowing from the centrifugal fan.

[0008] As a further improvement, the cyclone separator comprises an outer cylinder, an inner cylinder and a cone cylinder, the bottom of the outer cylinder is connected with the cone cylinder, the center of the outer cylinder is provided with the inner cylinder which is communicated with the separation outlet, and the side of the outer cylinder is provided with a separation inlet which is communicated with the separation outlet and a discharge opening at the bottom of the cone cylinder.

[0009] As a further improvement, a plurality of sliding blocks are fixedly installed on the baffle, and a lead screw is arranged on the lower end cover and is threadedly connected with the sliding blocks.

[0010] As a further improvement, an insulating layer is arranged on the outer ring surface of the kettle body, and the insulating layer is used for maintaining the temperature in the kettle body stable.

[0011] As a further improvement, the coating material comprises an adhesive, a composite bacteria slurry and a protective layer material.

[0012] As a further improvement, the spraying pipe is composed of three pipes, the atomizing nozzles are divided into first nozzles, second nozzles and third nozzles, and the three pipes are respectively connected with the first nozzles, the second nozzles and the third nozzles and are used for spraying the adhesive, the composite bacteria slurry and the protective layer material.

[0013] The application also provides a coating process of the organic fertilizer particle surface microorganism coating device, and the process comprises the following steps: Preheating and feeding stage: particle heating and stable conveying The centrifugal fan is started, and the air heater is started to heat the airflow and form stable hot air; The hot air flows through the Venturi tube converging section to accelerate, and forms negative pressure in the throat section to suck the particles in the hopper into the throat section; the particles and the high-speed hot air are mixed intensively in the diverging section and the conveying pipeline to quickly complete heat exchange, and the particles are heated up; The gas-solid mixture enters the cyclone separator, and the particles are separated out under the action of centrifugal force and temporarily stored in the cyclone separator; The preheated particles in the cyclone separator enter the kettle body from the upper feeding port of the coating kettle to complete the preheating and feeding process. Coating kettle coating stage: multi-stage precise spraying First stage: adhesive base layer spraying The kettle body rotates, and the inner wall main scraper "lifts up" the particles and takes them to the upper part of the kettle body, and the particles are concentrated and slide down to form a "material curtain"; the first spray head is opened, and the biocompatible adhesive is atomized and sprayed to the surface of the particles to form a wet bonding base layer. Second stage: composite slurry spraying After the adhesive spraying is completed, the second spray head is started, and the composite slurry is atomized and sprayed to the particle bonding base layer. Third stage: inert protective layer spraying After the slurry spraying is completed, the third spray head is opened, and the inert protective layer material is atomized and sprayed to the surface of the particles. During the process, the secondary scraper on the back of the main scraper breaks the single motion track of the particles, and the particles roll, jump and horizontally diffuse after being impacted, eliminating the coating blind area and ensuring that each surface of each particle is uniformly sprayed. Discharging stage: finished product discharge After the coating process is completed, the sliding baffle is opened, and the coated particles are discharged from the discharge port under the action of gravity.

[0014] From the above description of the structure of the present application, compared with the prior art, the present application has the following advantages: taking "preheating and feeding - layered coating - precise discharging" as the core, the particles are efficiently preheated and stably conveyed through the Venturi hot air feeding mechanism; stable hot air is formed by using a centrifugal fan and an air heater, combined with the Venturi negative pressure suction, the particle heat exchange and moisture removal are quickly completed, the cyclone separator realizes gas-solid separation to ensure clean particle conveying. The coating kettle stage adopts three-stage layered spraying: first, the biocompatible adhesive is sprayed to build a base layer, then the composite slurry containing protective agents and nutrients is sprayed to fix microorganisms, and finally the inert protective layer is sprayed to prevent adhesion and ultraviolet damage. The unique design of the main scraper and the secondary scraper during the process makes the particles form complex motion, eliminates the coating blind area, and cooperates with the precise multi-stage spraying to ensure that each particle is uniformly coated. In the discharging stage, the sliding baffle ensures that the finished product is discharged in an orderly manner. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The figure is a schematic diagram of the planar structure of the present application.

[0016] Figure 2 The sectional structure diagram of the air heater.

[0017] Figure 3 The sectional structure diagram of the Venturi tube.

[0018] Figure 4 The sectional structure diagram of the cyclone separator.

[0019] Figure 5 The three-dimensional structure diagram of the coating kettle.

[0020] Figure 6 The three-dimensional structure diagram of the kettle body.

[0021] Figure 7 The three-dimensional structure diagram of the upper end cover, the lower end cover, the spray pipe, the baffle and the support.

[0022] Figure 8 The internal plan structure diagram of the coating kettle.

[0023] Figure 9 The Figure 8 The enlarged diagram of A.

[0024] Figure 10 The three-dimensional structure diagram of the coating kettle from another perspective. DETAILED DESCRIPTION

[0025] The specific embodiments of the present application will be described below with reference to the accompanying drawings.

[0026] As shown in the accompanying drawings, an organic fertilizer particle surface microorganism coating device, the core of which is to realize the integrated process of particle preheating, accurate coating and high-efficiency discharging through the coordinated operation of the Venturi hot air feeding mechanism and the coating kettle 5. Figure 1 As shown in the accompanying drawings, the Venturi hot air feeding mechanism, as the "feed pretreatment unit" of the device, is composed of a centrifugal fan 1, an air heater 2, a Venturi tube 3, a cyclone separator 4, a hopper 8 and a key auxiliary component star-type discharger 9. Each component is closely matched, which not only guarantees the continuity of material conveying, but also completes the particle preheating process, laying a foundation for the subsequent coating quality.

[0027] Figure 1 As shown in the accompanying drawings, the Venturi hot air feeding mechanism, as the "feed pretreatment unit" of the device, is composed of a centrifugal fan 1, an air heater 2, a Venturi tube 3, a cyclone separator 4, a hopper 8 and a key auxiliary component star-type discharger 9. Each component is closely matched, which not only guarantees the continuity of material conveying, but also completes the particle preheating process, laying a foundation for the subsequent coating quality.

[0028] As shown in the accompanying drawings, the Venturi hot air feeding mechanism, as the "feed pretreatment unit" of the device, is composed of a centrifugal fan 1, an air heater 2, a Venturi tube 3, a cyclone separator 4, a hopper 8 and a key auxiliary component star-type discharger 9. Each component is closely matched, which not only guarantees the continuity of material conveying, but also completes the particle preheating process, laying a foundation for the subsequent coating quality. Figure 1 ​As shown, centrifugal fan 1 as air flow power source, with high wind pressure and low noise design, its outlet precisely docking air heater 2 heating inlet 23, can stable output continuous airflow. When working, fan through adjusting the wind speed gear (can be set according to the particle size 3-5 grade wind speed), ensure that the air flow velocity and the subsequent venturi 3 negative pressure formation needs matching, avoid because of airflow too strong lead to particle breakage, or airflow too weak affect the conveying efficiency.

[0029] As shown in the accompanying Figure 1 and Figure 2 air heater 2 undertakes the function of airflow heating, the whole by heating shell 21, heating tube 25 and heating controller 26 constitute. Heating shell 21 adopts high temperature resistant stainless steel material, the inner wall is anticorrosive treatment, effectively prolong the service life of the equipment; the heating cavity 22 in the shell is a closed cavity, two ends are set up heating inlet 23 and heating outlet 24 respectively, ensure that the airflow in the heating cavity 22 is fully heat exchange. Heating cavity 22 is evenly distributed with multiple spiral heating tube 25 (material selection of nickel chromium alloy, high thermal conductivity and oxidation resistance), each heating tube 25 is independently connected with heating controller 26, which can realize the partition temperature control. Heating controller 26 supports precise temperature regulation (range can be set to 40-80 DEG C, error ±2 DEG C), can set the appropriate heating temperature according to the heat resistance of different particle materials (such as straw, livestock and poultry manure organic fertilizer particles), to avoid high temperature damage the nutrient composition inside the particle.

[0030] As shown in the accompanying Figure 1 and 3 venturi 3 is designed according to venturi effect, is the key component to realize "air flow injection particles", the whole is divided into three parts of tapered section 3a, throat section 3b and expanding section 3c. The inner diameter of tapered section 3a gradually decreases from the inlet to throat section 3b, so that the hot air flowing from air heater 2 is accelerated here, and a stable negative pressure area is formed at throat section 3b; the throat section 3b is connected with the discharge port of hopper 8 through suction pipe 31, and a star type unloader 9 is installed between suction pipe 31 and hopper 8. The star type unloader 9 adopts stainless steel impeller and is driven by frequency conversion motor, which can accurately control the unloading amount (adjustment range is 50-200 kg / h). It can avoid the blockage of suction pipe 31 caused by the one-time influx of particles, and can also cooperate with the stable suction of particles under negative pressure. After the particles are sucked into the throat section 3b, they are mixed with high-speed hot air in the expanding section 3c and the subsequent conveying pipeline. The inner diameter of expanding section 3c gradually increases, and the air flow velocity slows down, providing space for air-solid two-phase heat exchange, so that the cold particles are rapidly heated to the set temperature (consistent with the temperature of hot air) within 10-15 seconds, and the trace of moisture attached to the surface of the particles is removed, improving the adhesion of the subsequent coating material.

[0031] As shown in the accompanying drawings Figure 1 and Figure 4 The cyclone separator 4 is responsible for gas-solid separation and particle temporary storage, which is composed of an outer cylinder 41, an inner cylinder 42 and a conical cylinder 45. The outer cylinder 41 is a cylindrical structure, which is seamlessly welded with the conical conical cylinder 45 at the bottom, and the bottom of the conical cylinder 45 is provided with a discharge port 46 for particle discharge; the inner cylinder 42 is vertically arranged in the center of the outer cylinder 41, and the upper end of the inner cylinder 42 extends to the outside of the outer cylinder 41 to form a separation outlet 44 for exhaust gas discharge; the separation inlet 43 is provided on the side of the outer cylinder 41 in the tangential direction, and is connected with the converging section 3c of the Venturi tube 3 through a pipeline. When the gas-solid mixture enters the outer cylinder 41 from the separation inlet 43, it moves at high speed along the inner wall of the outer cylinder 41, and under the action of centrifugal force, the particles are thrown to the inner wall of the outer cylinder 41 and slide along the inner wall to the conical cylinder 45, and finally discharged from the discharge port 46; while the exhaust gas carrying a small amount of dust is gathered to the center and discharged from the separation outlet 44 through the inner cylinder 42. In order to further improve the environmental protection, the separation outlet 44 can be connected to a small bag filter, which can filter the dust in the exhaust gas (the filtering efficiency can reach more than 99.5%), and the filtered clean air is released to avoid dust pollution.

[0032] As shown in the accompanying drawings Figure 1 The hopper 8 and the star-shaped discharger 9 are designed with a conical bottom, and the volume can be set according to the production requirements (usually 0.5-2m³), which can temporarily store the organic fertilizer particles to be treated, and the conical bottom structure can prevent the particles from accumulating and blocking the discharge port. The star-shaped discharger 9 is installed between the hopper 8 and the suction pipe 31, and between the discharge port 46 of the cyclone separator 4 and the coating kettle 5. In addition to controlling the discharge amount, the star-shaped discharger 9 also has a "sealing" function: the gap between the impeller and the shell is only 0.1-0.3mm, which can effectively block the communication between the upper and lower air flows, ensuring the stability of the negative pressure of the throat section 3b of the Venturi tube 3 (avoiding the failure of material suction due to insufficient negative pressure caused by air leakage), and maintaining the airtightness of the coating kettle 5 (preventing external air from entering to affect the temperature and humidity in the kettle, thereby destroying the microbial activity), realizing the "uniform, controllable and sealed" conveying of materials.

[0033] In use, start the centrifugal fan 1, airflow is established, start the air heater 2, and the airflow is heated to the set temperature. The hot air passes through the Venturi tube 3, and a stable negative pressure is generated at the throat section 3b. Then start the star-shaped discharger 9 at the suction pipe 31 to quantitatively suck the cold particles into the throat section 3b. The cold particles are mixed and heat-exchanged with the high-speed hot air in the gradually expanding section 3c of the Venturi tube 3 and the conveying pipe, and are rapidly heated. The gas-solid mixture enters the cyclone separator 4, and the preheated particles are separated and uniformly fed into the rotary coating kettle 5 through the star-shaped discharger 9. The exhaust gas is discharged from the separation outlet 44 at the top of the cyclone separator 4, and can be connected to a small bag-type dust collector for venting.

[0034] As shown in the accompanying drawings, Figure 1 The coating kettle 5 is the "core film-coating unit" of the device, and through the unique structural design and multi-stage spraying process, the precise spraying of the binder, the composite slurry, and the protective layer material is realized, and the uniformity of particle film-coating and the prevention of microbial cross-contamination are ensured.

[0035] As shown in the accompanying drawings, Figures 5 to 7 The coating kettle 5 is composed of a kettle body 51, a main scraper 52, a vice scraper 53, an upper end cover 54, a lower end cover 55, a spraying pipe 56, a baffle 57, and a bracket 58, and is installed on the rack 6 in a whole inclined manner. The inclination angle can be adjusted according to production needs (commonly 5-10°), and the gravity is used to assist the movement of particles from the high end to the low end to realize continuous film-coating.

[0036] As shown in the accompanying drawings, Figure 8 and Figure 9 The kettle body 51 is used as a film-coating cavity and is made of 304 stainless steel. The inner wall is polished (roughness Ra≤0.8μm) to avoid particle adhesion. The length and diameter of the kettle body 51 are set according to the production capacity (commonly 3-6m in length and 1-1.5m in diameter). The outer ring surface of the kettle body 51 is tightly wrapped with a heat preservation layer 512 made of aluminum silicate cotton material and covered with a stainless steel protective layer. This design can effectively reduce the heat loss in the kettle body 51 and maintain the temperature stability in the kettle body 51 (fluctuation range ±3℃). This design is crucial as it can prevent the condensation of bacteria liquid due to the overcooling of the inner wall of the kettle body 51 (which affects the flowability and uniformity of the spraying of the bacteria liquid), and can provide a suitable temperature environment for microorganisms (to avoid the decrease of microbial activity caused by low temperature).

[0037] As shown in the accompanying drawings, Figure 1 and Figure 7As shown, the kettle body 51 is respectively installed with an upper end cover 54 (inclined high end) and a lower end cover 55 (inclined low end) at both ends, both of which are fixed on the rack 6 through a support 58, which is welded by high-strength carbon steel. The upper end cover 54 and the kettle body 51 adopt mechanical sealing (the sealing element is made of wear-resistant rubber material), which ensures the sealing of the kettle body 51, and leaves a feeding port 541 and a spray pipe 56 through hole; the lower end cover 55 and the kettle body 51 also adopt sealing design, and leave a discharging port 551 and a spray pipe 56 through hole.

[0038] The rotation of the kettle body 51 is driven by a variable frequency motor, and the motor is connected with a gear (or a friction wheel) through a reducer, the gear is engaged with the gear ring on the outer surface of the kettle body 51 (or the friction wheel is in contact with the outer surface of the kettle body), and the stable rotation of the kettle body 51 is realized.

[0039] As shown in the accompanying drawings Figure 6 and Figure 8 As shown, the inner wall of the kettle body 51 is uniformly distributed with a plurality of main scoops 52, which cooperate with the auxiliary scoops 53 on the back of the main scoops 52 to form a unique "particle stirring system", which fundamentally solves the problems of uneven particle coating and blind area in traditional coating equipment.

[0040] The main scoops 52 adopt a curved spoon-shaped structure design, the cross section is "U" type and the curvature is optimized (the curvature radius is set according to the diameter of the kettle body), this shape can "lift" more particles when the kettle body 51 rotates, and the lifting amount of particles is improved; the extension direction of the main scoops 52 is parallel to the axial direction of the kettle body 51, and the installation surface has an angle (for example, 15°) with the radial direction of the kettle body 51, and the opening is directed to the rotation direction of the kettle body 51 — to maximize the "material lifting efficiency", avoid the particles from sliding off from both sides of the scoop, and ensure that each scoop can stably carry particles to the upper part of the kettle body. When the particles rotate with the main scoops 52 to the top of the kettle body 51 (reach the maximum inclination), they will slide down from the inside of the main scoops 52 due to gravity, forming a dense "material curtain", which provides an ideal condition for the subsequent precise spraying of the spray pipe 56 — the atomized coating material can directly act on the "material curtain" and fully contact with the particles, avoiding spraying omission.

[0041] On the back of each main scraper 52, which has a large bending radius (i.e. the side away from the direction of rotation of the kettle body), a plurality of inclined secondary scrapers 53 are evenly arranged. The secondary scrapers 53 are made of thin stainless steel plates and form an angle of 30-45° with the back of the main scraper 52. The inclination directions of different secondary scrapers 53 are slightly different. The main scraper 52 mainly drives the particles to make a compound motion in the axial and circumferential directions, while the secondary scraper 53 breaks the single motion track of the particles. When the particles slide down from the main scraper 52, they will hit the secondary scrapers 53 with different angles. Under the impact force, the particles will produce complex motions such as tumbling, jumping, and lateral diffusion, which can ensure that every surface (including the side and bottom surfaces) of the particles is fully exposed to the spraying area, completely eliminating the "film blind area" (such as the local non-film problem caused by the mutual shielding of particles in traditional equipment). At the same time, the violent turbulent motion can also avoid the "agglomeration and adhesion" of particles due to the viscosity of the coating material. The continuous collision and separation between particles make the particles that have just been sprayed with viscous material unable to contact for a long time, effectively reducing the caking phenomenon and ensuring the dispersibility of the finished particles.

[0042] As shown in the accompanying drawings Figure 7 and Figure 8 The spray pipe 56 and the atomizing nozzle 561 form a "precision spraying system". Through the design of three independent pipes and three types of nozzles, the coating materials (adhesive, composite slurry, and protective layer material) are sprayed in stages, ensuring the spraying effect of each material and eliminating cross-contamination to protect the activity of microorganisms.

[0043] The spray pipe 56 is composed of three independent stainless steel pipes. The three pipes pass through the upper end cover 54 and the lower end cover 55 in parallel. The inlet end of each pipe is connected to an external storage tank and a high-pressure pump (the pump pressure is set to 0.3-0.5 MPa). The spraying amount is controlled by adjusting the pump speed to realize "on-demand feeding".

[0044] The atomizing nozzle 561 is divided into a first nozzle 56a, a second nozzle 56b, and a third nozzle 56c, which are connected to the three independent pipes respectively to spray adhesive, composite slurry, and protective layer material. The installation angle of the atomizing nozzle 561 is optimized. All atomizing nozzles 561 are directed towards the falling path of the "material curtain" to ensure that the atomized material can maximize the contact area with the particles.

[0045] First nozzle 56a: Sprays a biocompatible adhesive. The selected adhesive is a natural polymer material (such as a 2-5% concentration of sodium alginate solution, a 1-3% concentration of xanthan gum solution, or a modified starch solution). This type of adhesive has three major advantages: First, it has good biocompatibility, does not react toxicly with microorganisms, and can be degraded by microorganisms (avoiding residual pollution of the soil); second, it has moderate viscosity, which can form a thin, moist base layer on the particle surface, providing a "bonding foundation" for the subsequent adhesion of the composite bacterial slurry; third, it is rich in carbohydrates, which can serve as an "initial food source" for microorganisms, providing energy for microorganisms in the early stages of coating.

[0046] Second nozzle 56b: Sprays a composite bacterial slurry, which is composed of microbial agents (such as Bacillus subtilis, phosphorus-solubilizing and potassium-solubilizing bacteria, etc., with an effective viable count ≥2×10⁻⁶). 9 The microbial agent (CFU / g), protectant, and nutrient are pre-mixed in a specific ratio (typically, microbial agent: protectant: nutrient = 10:3:2). The protectant, consisting of skim milk powder (5-10% concentration), glycerol (3-5% concentration), or trehalose (2-4% concentration), forms a protective film on the surface of microbial cells, resisting subsequent stresses such as dryness and temperature fluctuations. The nutrient consists of a small amount of carbon source (such as glucose) and nitrogen source (such as amino acids), controlled at 1-2%, providing energy for the microorganisms during their "dormant period" after coating and before application to the soil, thus maintaining their activity.

[0047] The third nozzle, 56c, sprays an inert protective layer material, using modified inorganic minerals (such as modified diatomaceous earth or attapulgite, with a particle size of 100-200 mesh) or plant-derived hydrophobic materials (such as palm oil derivatives). The spraying amount is controlled at 1-3% of the particle mass. This protective layer has three main functions: first, physical isolation, reducing adhesion between particles (preventing clumping of the finished product); second, moisture and moisture absorption, forming a hydrophobic layer on the particle surface to prevent the absorption of moisture from the air during storage (preventing premature activation of microorganisms due to moisture); and third, UV resistance, as the inorganic mineral particles can shield against ultraviolet rays, preventing sunlight from causing microbial inactivation.

[0048] In addition, as attached Figure 10 As shown, a sliding baffle 57 is provided at the discharge port 551 of the lower end cover 55 to control the opening and closing of the discharge port and the discharge speed. The baffle 57 is made of stainless steel plate, and multiple sliders 571 are fixedly installed on its surface. A lead screw 572 is installed on the lower end cover 55, and the lead screw and the sliders 571 are connected by threads. One end of the lead screw is connected to a lead screw motor (variable frequency motor). During operation, the lead screw is driven to rotate by the lead screw motor, which drives the sliders 571 to slide against the baffle 57, thereby adjusting the opening size of the discharge port 551 and controlling the discharge speed.

[0049] The application also provides a coating process of the organic fertilizer particle surface microorganism coating device, which comprises the following steps. Preheating and feeding stage: particle heating and stable conveying Start the centrifugal fan 1, and after the air flow is stably circulated in the pipeline, start the air heater 2 to heat the pipe 25 to a set temperature, so that the air flow flowing through the heating cavity 22 is heated to a target value to form stable hot air. Start the star-shaped unloader 9 between the hopper 8 and the suction pipe 31, and the cold particles in the hopper 8 are quantitatively fed into the suction pipe 31; the hot air flows through the converging section 3a of the Venturi tube 3 to accelerate, and a negative pressure is formed in the throat section 3b to suck the particles into the throat section 3b; the particles and the high-speed hot air are mixed violently in the diverging section 3c and the conveying pipeline, and the heat exchange is completed within 10-15 seconds, the particle temperature rises to a set value, and the surface trace moisture is evaporated at the same time, improving the adhesion of the subsequent coating material; The gas-solid mixture enters from the tangent of the cyclone separator 4 separation inlet 43, moves at a high speed along the outer cylinder 41 wall, and is thrown to the inner wall of the outer cylinder 41 under the action of centrifugal force and slides down to the cone cylinder 45 for temporary storage; the waste gas carrying dust gathers towards the center, is discharged from the separation outlet 44 of the inner cylinder 42, and is filtered by a bag-type dust collector (efficiency ≥ 99.5%) before being cleaned and vented; Start the star-shaped unloader 9 between the discharge port 46 of the cyclone separator 4 and the heat preservation pipeline 7, and the preheated particles enter the kettle body 51 from the upper end cover 54 of the coating kettle 5, completing the preheating and feeding process. Coating kettle 5 coating stage: multi-stage precise spraying First stage: adhesive base layer spraying The kettle body 51 rotates at a set speed, the inner wall main scraper 52 “lifts” the particles and brings them to the upper part of the kettle body 51, and the particles are concentrated and slide down to form a “material curtain”; the first nozzle 56a (connected with the adhesive pipeline) is opened, the biocompatible adhesive is atomized and sprayed onto the particle surface to form a wet adhesive base layer, providing a basis for microbial adhesion, and the carbohydrates in the adhesive provide initial energy for the microorganisms.

[0050] Second stage: composite slurry spraying After the adhesive spraying is completed, the second nozzle 56b (connected with the slurry pipeline) is started, and the composite slurry is atomized and sprayed onto the particle adhesive base layer; the microorganisms in the slurry are embedded and fixed in the adhesive matrix, the protective agent forms a protective film on the surface of the microorganisms, the nutrient agent reserves energy for the microorganisms in the “dormant period”, and the amount of bacteria is ensured to reach the design value; Third stage: inert protective layer spraying After the bacterial slurry spraying is finished, the third nozzle 56c (with a protective layer pipeline) is opened to atomize and spray the inert protective layer material to the surface of the particles to form an extremely thin physical barrier; this layer can reduce particle adhesion, prevent moisture absorption during storage, and shield ultraviolet rays to extend the shelf life of microorganisms; During the process, the secondary copying plate 53 on the back of the primary copying plate 52 breaks the single motion trajectory of the particles, and the particles roll, jump and spread horizontally after being impacted, eliminating the blind area of the coating and ensuring that each surface of each particle is evenly sprayed; Discharging stage: finished product discharge After the coating process is completed, the lead screw motor of the lower end cover 55 is started to drive the lead screw 572 to rotate, driving the sliding block 571 and the baffle 57 to slide, opening the discharge port 551, and the coated particles are discharged from the discharge port 551 under the action of gravity.

[0051] From the above working process, the present application takes "preheating and feeding - layered coating - precise discharging" as the core, and realizes efficient preheating and stable conveying of particles through the Venturi hot air feeding mechanism: stable hot air is formed by using the centrifugal fan 1 and the air heater 2, combined with the negative pressure suction of the Venturi tube 3, the particle heat exchange and moisture removal are completed within 10-15 seconds, and the cyclone separator 4 realizes gas-solid separation to ensure clean particle conveying. The coating kettle 5 stage adopts three-stage layered spraying: first, build a base layer with biocompatible adhesive, then spray a composite bacterial slurry containing protective agents and nutrients to fix microorganisms, and finally cover an inert protective layer to prevent adhesion and ultraviolet damage. During the process, the unique design of the primary copying plate 52 and the secondary copying plate 53 makes the particles form complex motion, eliminating the coating blind area, and cooperating with precise multi-stage spraying, ensuring that each particle is evenly coated. The sliding baffle 57 ensures that the finished product is discharged in order.

[0052] The above is only a specific embodiment of the present application, but the design concept of the present application is not limited to this, and any non-essential modification of the present application using this concept shall be deemed to be an infringement of the protection scope of the present application.

Claims

1. A device for coating organic fertilizer granules with microorganisms, characterized in that, The encapsulation device includes: A Venturi-type hot air feeding mechanism includes a centrifugal fan, an air heater, a Venturi tube, a cyclone separator, and a hopper. The air outlet of the centrifugal fan is connected to the heating inlet of the air heater, the heating outlet of the air heater is connected to the converging section of the Venturi tube, the expanding section of the Venturi tube is connected to the separation inlet of the cyclone separator, and the throat of the Venturi tube is connected to the discharge outlet of the hopper through a suction pipe. A coating vessel includes a vessel body, main lifting plates, auxiliary lifting plates, an upper end cover, a lower end cover, a spray pipe, and a baffle. Multiple main lifting plates are evenly distributed circumferentially along the inner wall of the vessel body. The extension direction of the main lifting plates is parallel to the axial direction of the vessel body. The cross-section of each main lifting plate is a curved spoon shape. Multiple inclined auxiliary lifting plates are located on the back side of the main lifting plates with a large curvature, extending from the back side. The upper and lower end covers at both ends of the vessel body are fixedly mounted on a frame. The vessel body is inclined on the frame and can rotate relative to the upper end cover. The upper end cover at the higher inclined end of the vessel body has a feeding port connected to the discharge port of the cyclone separator for feeding. The lower end cover at the lower inclined end of the vessel body has a discharging port for discharging, and the lower end cover has a sliding baffle to control the opening and closing of the discharging port. The spray pipe penetrates the upper and lower end covers and has multiple atomizing nozzles for spraying the coating material.

2. The microbial coating device for the surface of organic fertilizer granules as described in claim 1, characterized in that: The air heater includes a heating shell and heating tubes. The heating shell has a heating cavity inside, with a heating inlet and a heating outlet at both ends that are connected to the heating cavity. The heating cavity has multiple heating tubes, which are controlled by a heating controller installed on the heating tubes. The heating tubes are used to heat the air flowing in from the centrifugal fan.

3. The microbial coating device for the surface of organic fertilizer granules as described in claim 1, characterized in that: The cyclone separator includes an outer cylinder, an inner cylinder, and a cone. The bottom of the outer cylinder is connected to the cone. The center of the outer cylinder has an inner cylinder that communicates with the separation outlet. The side of the outer cylinder has a separation inlet that communicates with the separation outlet and the discharge port at the bottom of the cone.

4. The microbial coating device for the surface of organic fertilizer granules as described in claim 1, characterized in that: The baffle is fixedly installed with multiple sliders, and the lower end is covered with a lead screw that is threadedly connected to the sliders.

5. The microbial coating device for the surface of organic fertilizer granules as described in claim 1, characterized in that: The outer circumference of the vessel is covered with a heat insulation layer, which is used to maintain a stable temperature inside the vessel.

6. The microbial coating device for the surface of organic fertilizer granules as described in claim 1, characterized in that: The coating material includes an adhesive, a composite bacterial slurry, and a protective layer material.

7. The microbial coating device for the surface of organic fertilizer granules as described in claim 6, characterized in that: The spray pipe consists of three pipes, and the atomizing nozzle is divided into a first nozzle, a second nozzle, and a third nozzle, which are connected to the three pipes respectively, and spray the adhesive, composite bacterial slurry, and protective layer material accordingly.

8. The coating process of the microbial coating device for the surface of organic fertilizer granules as described in claim 1, the process comprising the following steps: Preheating and feeding stage: Particle heating and stable conveying Turn on the centrifugal fan and start the air heater to heat the airflow and form a stable hot air; Hot air accelerates as it flows through the converging section of the venturi tube, creating a negative pressure in the throat section, which draws the particles from the hopper into the throat section. The particles and high-speed hot air mix violently in the expanding section and the conveying pipe, quickly completing heat exchange and raising the temperature of the particles. The gas-solid mixture enters the cyclone separator, where the particles are separated by centrifugal force and temporarily stored in the cyclone separator. The preheated particles inside the cyclone separator enter the vessel body through the feed port of the coating vessel to complete the preheating and feeding process; Coating stage: Multi-stage precision spraying Phase 1: Adhesive Base Coating The vessel rotates, and the main lifting plate on the inner wall "scoops up" the particles and brings them to the upper part of the vessel. The particles then fall in a concentrated manner to form a "material curtain". The first nozzle is turned on to atomize and spray the biocompatible adhesive onto the surface of the particles, forming a moist and adhesive base layer. Phase Two: Composite Microbial Slurry Spraying After the adhesive is sprayed, the second nozzle is activated to atomize and spray the composite bacterial slurry onto the granular bonding substrate. Phase 3: Inert protective layer spraying After the bacterial slurry spraying is completed, the third nozzle is turned on to atomize and spray the inert protective layer material onto the particle surface. During the process, the auxiliary plate on the back of the main plate breaks the single movement trajectory of the particles. After impact, the particles roll, jump, and spread laterally, eliminating the coating blind zone and ensuring that each particle is evenly coated on all surfaces. Material feeding stage: Finished product discharge After the entire coating process is completed, slide the baffle to open the discharge port, and the coated particles will be discharged from the discharge port under the action of gravity.

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