Clean production system of compound fertilizer

Abstract

The invention discloses a clean production system of a compound fertilizer, which comprises a primary granulation device, a storage device, a metering device, a mixing device, a screening device and a packaging device, the primary granulation device is used for preparing raw materials of the compound fertilizer into granular raw materials, and the storage device is used for storing the granular raw materials after primary granulation; the metering device is used for weighing and metering granular raw materials, the mixing device is used for mixing and stirring the weighed and metered granular raw materials, the screening device is used for screening the mixed granular raw materials, the packaging device is used for packaging the screened granular raw materials, and the raw materials are directly granulated and put in storage. The obvious defects of moisture absorption, hardening and deterioration easily caused by raw material storage in a compound fertilizer plant are overcome, the worry of long-term storage of the raw materials is fundamentally solved, the usable area and conditions of a production plant are optimized, and the production environment is effectively improved.

Description

Technical Field

[0001] The invention relates to the field of compound fertilizer production, in particular to a clean production system of compound fertilizer. Background Art

[0002] Compound fertilizer refers to a fertilizer containing two or more nutrients. These nutrients are mainly nitrogen (N), phosphorus (P), and potassium (K), so compound fertilizers are usually expressed in terms of their nutrient composition using their corresponding contents.

[0003] At present, the existing production methods of compound fertilizer mainly include high tower granulation and agglomeration granulation. High tower granulation can realize the production of part of fertilizers, and its raw materials need to be liquefiable, and the liquefaction temperature is relatively sensitive. Commonly used, such as urea, has corresponding requirements for raw materials, and thus there are production limitations; in the production process of agglomeration granulation, most of the raw materials are inorganic salts, which are easy to absorb moisture, harden, liquefy and other properties, and the appearance is small particles, powder and other forms. The current manufacturers simply store the purchased packaging bags in an open raw material warehouse. Moisture absorption, hardening, and liquidization to produce a muddy environment often occur and cannot be solved. In addition, the dust phenomenon is serious during the production process, resulting in a poor overall production environment and causing a certain degree of environmental pollution, which needs further improvement. Summary of the invention

[0004] In order to further improve the production environment, the present application provides a clean production system for compound fertilizer.

[0005] The present application provides a clean production system for compound fertilizer, which adopts the following technical solution: A clean production system for compound fertilizer comprises a primary granulation device, a storage device, a metering device, a mixing device, a screening device and a packaging device. The primary granulation device prepares various raw materials of the compound fertilizer into granular raw materials, the storage device is used to store the granular raw materials after primary granulation, the metering device is used to weigh and meter the granular raw materials, the mixing device is used to mix and stir the weighed and metered granular raw materials, the screening device is used to screen the mixed granular raw materials, and the packaging device is used to package the screened granular raw materials.

[0006] Optionally, the diameter of the granular raw material after the first granulation is 4-5 mm or 5-30 mm.

[0007] Optionally, the mixing device includes a blender and a mixer, the blender is used to mix granular raw materials with a diameter of 4-5 mm, and the mixer is used to mix granular raw materials with a diameter of 5-30 mm.

[0008] Optionally, it also includes a crushing device and a secondary granulation device, wherein the crushing device is used to crush the granular raw materials mixed by the mixer, and the secondary granulation device is used to perform secondary granulation on the crushed granular raw materials. The granular raw materials after secondary granulation are transported to the screening device for screening, and the screened granular raw materials are supplied to the packaging device.

[0009] Optionally, the residual material produced during screening by the screening device is transported to the granulation site as return material.

[0010] Optionally, both the primary granulation device and the secondary granulation device adopt a double-roll granulator, and the diameter of the granular raw material after granulation by the secondary granulation device is 4-5 mm.

[0011] Optionally, the storage device includes a silo, a feed port is provided on one side of the top of the silo, a discharge port is provided on the bottom of the silo, a spiral downward material drop chute is provided in the silo, and a stop valve and a vibration motor are provided at the discharge port of the silo.

[0012] Optionally, a wind ball for ventilation is provided on the top of the silo, and a dehumidifier is provided on the silo, and the dehumidifier is used to dehumidify the inside of the silo.

[0013] Optionally, a conveying device is also included, which is used to convey granular raw materials. The conveying device includes an inclined tube that is arranged obliquely, an inlet is arranged at one high end of the inclined tube, and an outlet is arranged at the other end. An isolation layer is arranged inside the inclined tube, a material flow layer is formed above the isolation layer, and a compressed air flow layer is formed below the isolation layer. The isolation layer is provided with dense through holes.

[0014] Optionally, the conveying device also includes an air storage tank, an air intake pipe connecting the air storage tank and the inclined tube is arranged between the two, the inclined tube is connected to a return air pipe, the end of the return air pipe away from the inclined tube is connected to the air intake pipe, and both the air intake pipe and the return air pipe are provided with a one-way valve, and the inclined tube adopts a high-pressure vinyl chloride tube or a high-pressure polypropylene tube.

[0015] In summary, the present application includes at least one of the following beneficial technical effects: 1. The raw materials are directly granulated and stored, which solves the obvious drawbacks of moisture absorption, compaction and deterioration of raw materials in compound fertilizer plants, fundamentally solves the worries of long-term storage of raw materials, and optimizes the use area and conditions of production plants; 2. The new storage form can store granulated raw materials in large quantities. The contact area between particles is reduced, the volume compression density is increased, and it is not easy for humid gas to enter. In addition, the exhaust and dehumidification on the top not only greatly overcome the problem of raw materials absorbing moisture and hardening due to bagging, but also enhance the fluidity of raw materials, creating a foundation for the automatic system of computer batching and electronic metering feeding; 3. Large-scale raw material storage mode saves the land area for raw material storage. Single-substance granular materials can realize computer-controlled automatic batching, feeding and electronic metering and discharging; 4. The 4-5mm particles of the primary granulation formed by roller extrusion have the same appearance. The air in the raw materials is removed by extrusion, the gap is compressed, and the density and specific gravity of the formed particles tend to be uniform. The blending of such raw materials will not cause blending stratification due to particle size, density difference and different adsorption capacity. The blended compound fertilizer meets the internationally accepted blending fertilizer ratio principle and can meet the quality requirements of homogenized and fully blended fertilizer, which not only saves processing costs and improves production efficiency, but also enables the subsequent simple compound fertilizer to be realized, which may form a new fertilizer production model; 5. The new process has made a thorough improvement on the stubborn environmental pollution problem in the current production and transportation links. That is, a closed high-pressure vinyl chloride pipe or high-pressure polypropylene pipe is used as the main conveying body, and an isolation layer is lined inside. Compressed air is introduced to produce directional flow, driving the granular materials to flow smoothly along the set inclination angle. This new type of inclined trough angle inclined tube type conveying overcomes the material clogging and solves the corrosion and environmental pollution problems commonly existing in inorganic salts in the raw materials of compound fertilizer production; 6. Overcome the main difficulties faced by compound fertilizer manufacturers in achieving green factory (clean production) standards, and overcome a series of practical problems in the current three major production methods (high tower granulation, agglomeration granulation, roller extrusion granulation), such as material overflow, dust splashing, and corrosion caused by material moisture absorption and adhesion to production equipment; 7. The realization of new green factory (clean production) is due to the simple and efficient process, less granulation equipment and auxiliary facilities, and the energy consumption is significantly lower than other types of production energy consumption, which directly reduces the production cost; 8. The new one-time granulation mode overcomes the product defects caused by various drawbacks of previous blended fertilizers and can fully realize the automated production of blended fertilizers. Judging from foreign examples, blended fertilizers are the most economical compound fertilizer production mode. This method may bring about beneficial changes in compound fertilizer production and will promote the realization of intensive, simplified, low-energy and diversified compound fertilizer production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is an overall schematic diagram of Example 1.

[0017] Figure 2 It is a three-dimensional diagram of the silo in Example 1.

[0018] Figure 3 It is a structural diagram of the blanking chute in Example 1.

[0019] Figure 4 It is a schematic diagram of the structure of the conveying device in Example 1.

[0020] Figure 5 It is a structural diagram of the chute gas feeding mechanism in Example 1.

[0021] Figure 6 It is a structural diagram of the chute gas feeding mechanism in Example 2.

[0022] Figure 7 It is a structural diagram of the interior of the inclined tube in Example 3.

[0023] Figure 8 It is a cross-sectional view of the blockage clearing member in Example 3.

[0024] Fig. 9 It is a structural diagram of the wind ball in Example 3.

[0025] Description of reference numerals: 1. Silo; 2. Feeding port; 3. Discharging port; 4. Stop valve; 5. Dropping chute; 6. Bracket; 7. Reinforcement rod; 8. Vibration motor; 9. Wind ball; 10. Conveying device; 11. Shell; 12. Hoist; 13. Chute gas conveying mechanism; 14. Inclined pipe; 15. Feeding pipe; 16. Inlet; 17. Discharging end; 18. Outlet; 19. Isolation layer; 20. Material flow layer; 21. Compressed air flow layer; 22. Through hole; 23. Inlet pipe; 24. Storage Gas tank; 25. Return air pipe; 26. One-way valve; 27. Pressure relief valve; 28. Integrated box; 29. ​​Channel; 30. Filter bag; 31. Clearing plate; 32. Telescopic member; 33. Clearing member; 34. Connecting spring; 35. Wind wheel; 36. Cam; 37. Conical tip; 38. Scraper; 39. Trough; 40. Reset spring; 41. Fan blade; 42. Inclined part; 43. Cylinder; 44. Mounting part; 45. Fan; 46. Cloth bag; 47. Rod; 48. Side guard. DETAILED DESCRIPTION

[0026] The following is combined with Figure 1-9 This application is described in further detail.

[0027] Example 1 A clean production system for compound fertilizer, such as Figure 1As shown, it includes a primary granulation device, a storage device, a metering device, a mixing device, a screening device and a packaging device, wherein the primary granulation device adopts a double-roll granulator, and the primary granulation device is used to perform primary granulation on the compound fertilizer raw material to obtain a granular raw material, and the granular raw material is divided into large particles and small particles, wherein the diameter of the small particles is 4-5mm, and the diameter of the large particles is 5-30mm, and the obtained granular raw material is transported to the storage device for storage; in this embodiment, the storage device adopts a silo 1, and the storage device classifies various granular raw materials and stores them independently; the metering device adopts a metering hopper, and obtains the corresponding granular raw materials from the storage device according to actual needs, and the granular raw materials are accurately weighed by the metering hopper; the mixing device is mainly used to mix and stir the granular raw materials after passing through the metering hopper; the screening device adopts a screening machine, and the screening device screens the granular raw materials after mixing and stirring, and the granular raw materials that meet the requirements are transported to the packaging device for packaging; the packaging device adopts a packaging machine, which mainly packages the sieved granular raw materials.

[0028] like Figure 1 As shown, the mixing device includes a blender and a mixer, wherein the blender is mainly used to mix and stir granular raw materials with a diameter of 4-5mm, and the mixer is mainly used to mix large particles after primary granulation, that is, to stir and mix granular raw materials with a diameter of 5-30mm, the mixing and stirring speed is 8-30 rpm, and the stirring time is 10 minutes. In this way, the small granular raw materials after primary granulation are transported to the blender after passing through the metering hopper for blending, and then sieved by the screening machine after blending. The sieved granular raw materials can be packaged by the packaging machine to realize the direct production of blended fertilizers, and such blended fertilizers will not have blending stratification caused by different particle sizes, density differences and adsorption capacities. The blended compound fertilizer meets the internationally accepted blended fertilizer ratio principle and can meet the quality requirements of fully homogenized blended fertilizers, which saves processing costs and improves production efficiency.

[0029] like Figure 1 As shown, it also includes a crushing device and a secondary granulation device, wherein the crushing device adopts a crusher, and the crushing device is used to crush the large particle raw materials mixed by the mixer, and the crushed particle raw materials are then transported to the secondary granulation device for secondary granulation. In this embodiment, the secondary granulation device also adopts a double-roll granulator, and the diameter of the particle raw materials after the secondary granulation is 4-5mm. The particle raw materials after the secondary granulation are transported to the screening machine for screening, and the particle raw materials that meet the requirements are finally transported to the packaging device for packaging.

[0030] like Figure 1 As shown, the remaining material after screening by the screening machine is transported to the granulation site as return material for recycling, thereby making full use of the remaining material, avoiding waste of the remaining material, and effectively reducing production costs.

[0031] like Figure 2 As shown, the storage device adopts a silo 1, which is in a vertical cylindrical shape. A feed port 2 is opened on one side of the top of the silo 1. The top and bottom of the silo 1 are both conical, and a discharge port 3 is arranged at the bottom of the silo 1. A stop valve 4 is arranged at the silo 1 corresponding to the discharge port 3, and the discharge of the material from the discharge port 3 can be achieved by opening the stop valve 4.

[0032] like Figure 2 and Figure 3 As shown, a spiral downward material drop chute 5 is provided inside the silo 1, the top of the material drop chute 5 is close to the feed port 2, the bottom of the material drop chute 5 is close to the discharge port 3, one side of the material drop chute 5 is fixed to the inner wall of the silo 1, and the other side is provided with a retaining edge 48, the retaining edge 48 is used to prevent the side of the material from falling, so that after the granular raw material enters from the feed port 2, it can slowly slide along the material drop chute 5 to the bottom of the silo 1 for storage, thereby avoiding the phenomenon that the granular raw material falls directly and causes breakage.

[0033] like Figure 2 As shown, a bracket 6 for supporting the silo 1 is provided at the bottom thereof, a reinforcing rod 7 connecting the bracket 6 and the silo 1 is provided between the bracket 6 and the silo 1, and a vibration motor 8 is provided on the reinforcement rod 7. With the aid of the vibration motor 8, vibration can be generated during discharging to ensure that the material in the silo can be discharged from the discharge port 3 in an orderly manner to reduce the occurrence of blockage; in addition, the inner wall of the silo 1 and the surface of the blanking chute 5 are coated with resin coatings and other barrier coatings to prevent moisture absorption and reduce friction to facilitate flow.

[0034] like Figure 2 As shown, a wind ball 9 for ventilation is arranged on the top of the silo 1, and good ventilation between the inside of the silo 1 and the outside is achieved through the wind ball 9. In addition, a dehumidifier is also connected to the silo 1, and the inside of the silo 1 can be effectively dehumidified by the dehumidifier. A cloth bag 46 is arranged at the end of the wind ball 9 extending into the silo body, and the cloth bag 46 can block the discharge of internal dust, thereby effectively preventing dust.

[0035] This storage method for granular raw materials solves a series of drawbacks caused by the traditional fertilizer production enterprises storing bagged raw materials on high racks, which are very easy to absorb moisture, and the environment has been greatly improved.

[0036] like Figure 3As shown, the present embodiment also includes a conveying device 10, which is used for conveying granular raw materials between various links in the above-mentioned system. The conveying device 10 includes a shell 11, an elevator 12 and a chute gas conveying mechanism 13. The elevator 12 and the chute gas conveying mechanism 13 are both located in the shell 11, and the elevator 12 and the chute gas conveying mechanism 13 are alternately and continuously distributed, so that the material is in a closed environment in the shell 11 during the conveying process, which effectively reduces the dust phenomenon, and thus can well improve the external workshop environment. In actual use, the elevator 12 can be used with the chute gas conveying mechanism 13 as a conveying group, and multiple conveying groups can be set according to the distance between the processes to finally achieve the purpose of material conveying. The elevator 12 is used to lift the material from a low place to a high place, and the material lifted to the high place is then dropped and fed through the chute gas conveying mechanism 13, and such a cycle can achieve the purpose of good feeding.

[0037] like Figure 4-Figure 5 As shown, the chute gas conveying mechanism 13 includes an inclined tube 14 arranged obliquely, a feed pipe 15 is arranged at one end of the inclined tube 14 at a high position, the feed pipe 15 forms an inlet 16 at the inclined tube 14, the inlet 16 is for the granular raw material to enter, the lower end of the inclined tube 14 is a discharge end 17, an outlet 18 for the granular raw material to be discharged is formed at the discharge end 17, and an isolation layer 19 is horizontally arranged in the middle of the inclined tube 14, the upper part of the isolation layer 19 is a material flow layer 20, the lower part of the isolation layer 19 is a compressed air flow layer 21, the isolation layer 19 is provided with vertically penetrating through holes 22, and the through holes 22 are evenly and densely distributed on the isolation layer 19; in addition, an air inlet pipe 23 connected to the compressed air flow layer 21 is arranged on the inclined tube 14, and the air inlet pipe 23 is connected to the compressed air flow layer 21 at one end of the inclined tube 14 at a high position. The inclined trough gas conveying mechanism 13 also includes an air tank 24, in which compressed gas is stored. The end of the air inlet pipe 23 away from the inclined tube 14 is connected to the air tank 24, and the compressed air is continuously provided to the compressed air flow layer 21 through the air tank 24. The flow of compressed air is used to promote the flow of particulate materials in the material flow layer 20. The inclined tube 14 adopts a high-pressure vinyl chloride tube or a high-pressure polypropylene tube. This new type of inclined trough angle inclined tube 14 type conveying overcomes the material blockage and solves the corrosion and environmental pollution problems commonly existing in inorganic salts in the raw materials of compound fertilizer production. On the one hand, the material can fall under the action of its own gravity, and on the other hand, the compressed air plays a further role in assisting the conveying of the material, ensuring that the particulate material can fall well and be conveyed forward.

[0038] like Figure 5As shown, a return air pipe 25 connected to the lower end of the inclined tube 14 is connected, one end of the return air pipe 2525 is in circulation with the compressed air flow layer 21 at the lower end of the inclined tube 14, and the other end is connected with the intake pipe 23, so that part of the compressed air can be recycled and utilized, waste can be reduced, and the purpose of energy saving can be further achieved; in this embodiment, a one-way valve 26 is provided on the intake pipe 23 and the return air pipe 25, so that the compressed air can only flow in one direction to avoid backflow.

[0039] like Figure 4 As shown, a pressure relief valve 27 is provided on the outer shell 11. Since the compressed air in the air storage tank 24 is continuously provided to the inclined tube 14, the pressure in the outer shell 11 will continue to increase. After reaching a certain pressure, the pressure relief valve 27 can be used to release the pressure, thereby avoiding the situation where the internal pressure of the outer shell 11 is too high. At the same time, a filter cloth for filtering dust is provided at the pressure relief valve 27. The filter cloth blocks the discharge of internal dust, thereby achieving the discharge of internal pressure while effectively preventing dust.

[0040] Example 2 A clean production system for compound fertilizer, such as Figure 6 As shown, the difference between it and Example 1 lies in the difference of the chute gas conveying mechanism 13. In this embodiment, a dust box is arranged on the return air pipe 25 of the chute gas conveying mechanism 13, and a channel 29 for communicating with the return air pipe 25 is arranged in the dust box, and a filter bag 30 is arranged in the channel 29. Since some powder will inevitably be generated during the conveying process of the particulate material, the powder will flow into the return air pipe 25. The design of the filter bag 30 can filter the powder to avoid the situation where the powder continues to flow in the pipeline and accumulates more and more. In this embodiment, two dust boxes are arranged horizontally in parallel, and the dust boxes are horizontally slidably connected to the return air pipe 25. When a large amount of powder accumulates in one dust box, the other dust box is switched to be connected to the return air pipe 25 by sliding. At this time, the powder in the dust box can be cleaned, and the return air pipe 25 can be kept in a working state continuously, and the production efficiency will not be affected by the cleaning of the powder.

[0041] Example 3 A clean production system for compound fertilizer, such as Figure 7-Figure 8As shown, the difference between this embodiment and embodiment 1 mainly lies in the difference in the internal structure of the inclined tube 14. In this embodiment, a clearing plate 31 is provided in the compressed air flow layer 21 in the inclined tube 14. The clearing plate 31 is vertically movably connected to the bottom wall of the inclined tube 14 through telescopic members 32 at both ends. A clearing piece 33 corresponding to and cooperating with each through hole 22 on the isolation layer 19 is provided on the top of the clearing plate 31. A connecting spring 34 connecting the clearing plate 31 and the bottom wall of the inclined tube 14 is provided. The connecting spring 34 is used to drive the clearing plate 31 to move downward and reset, that is, the connecting spring 34 is used to drive the clearing plate 31 to reset to a state where the clearing piece 33 is separated from the through hole 22. In addition, a spring 34 is provided in the inclined tube 14 to drive the clearing plate 31 toward the isolation layer 19. The driving member moves in the direction of the isolation layer 19. In this embodiment, the driving member adopts a wind wheel 35, which is arranged at the compressed air flow layer 21. The wind wheel 35 is driven to rotate as the compressed air circulates. A cam 36 is arranged at the central axis of the wind wheel 35, so that the cam 36 can be driven to rotate continuously as the wind wheel 35 rotates. The cam 36 abuts against the clearing plate 31 to drive it to move toward the isolation layer 19. The clearing member 33 is inserted into the through hole 22 to achieve effective clearing of the through hole 22. The clearing plate 31 moves back and forth continuously in this way, and the clearing operation of the isolation layer 19 is well achieved. The structure is simple and no manual operation is required for clearing. It is simple and convenient, and the conveying effect of the particulate material is avoided to be affected by the blockage of the through hole 22.

[0042] like Figure 8 As shown, the clearing member 33 includes a conical tip 37 at the top, and the conical tip 37 makes it easier for the clearing member 33 to be inserted into the through hole 22 to clear the blockage. In addition, scraping strips 38 are symmetrically arranged on both sides of the clearing member 33, and the scraping strips 38 are horizontally slidably connected to the clearing member 33. A groove 39 for the scraping strip 38 to move inward is provided on the clearing member 33, and a return spring 40 for driving the scraping strip 38 to move outward is arranged in the groove 39. In this embodiment, the clearing member 33 is rotatably connected to the clearing plate 31, and the bottom end of the clearing member 33 passes through the rear end of the clearing plate 31 to be provided with a fan blade 41, and the fan blade 41 is also located in the compressed air flow layer 21. When compressed air circulates, the fan blades 41 are driven to rotate, thereby synchronously driving the blockage clearing member 33 to rotate. In this way, the blockage clearing member 33 can not only penetrate into the through hole 22 in the vertical direction to clear the blockage, but also can scrape the inner wall of the through hole 22 with the help of the scraping strips 38 on both sides during the rotation process, thereby achieving better clearing efficiency for the through hole 22 and a more comprehensive clearing effect. The movable scraping strip 38 is designed to meet the use of through holes 22 with different apertures and has better applicability. The top end of the scraping strip 38 has an inclined portion 42, and the inclination angle of the inclined portion 42 is consistent with the conical top 37, which facilitates the clearing member 33 to be better inserted into the through hole 22.

[0043] like Figure 7As shown, the wind wheel 35 is vertically lifted and connected to the inclined tube 14, and a cylinder 43 is provided on the inclined tube 14 for driving the wind wheel 35 to vertically lift and lower, so that the position of the wind wheel 35 can be adjusted. When there is no need to clear the blockage, the wind wheel 35 can be driven downward by the cylinder 43 so that the cam 36 does not contact the isolation layer 19, thereby maintaining a good ventilation effect of the isolation layer 19 and reducing the situation where the cam 36 contacts the clearing plate 31 and continuously generates impact noise.

[0044] like Fig. 9 As shown, in this embodiment, the bottom end of the wind ball 9 has a mounting portion 44 for extending into the silo 1, and a fan 45 is arranged in the mounting portion 44. The air outlet direction of the fan 45 is toward the wind ball 9. With the help of further design of the fan 45, the air flow efficiency can be improved, and the ventilation effect of the wind ball 9 can be improved. The bottom end of the mounting portion 44 is a ventilation port, and a cloth bag 46 is arranged at the ventilation port. The cloth bag 46 is used to block and suppress the discharge of dust in the silo body, and dust is effectively prevented; in addition, a vertical rod 47 is arranged on the fan 45, and the bottom end of the rod 47 abuts against the cloth bag 46. The vibration generated when the fan 45 is working can be transmitted to the cloth bag 46 through the rod 47, causing the cloth bag 46 to shake, so that the dust adhering to the cloth bag 46 can be shaken off, avoiding the clogging of the cloth bag 46 to affect the ventilation effect, and realizing automatic clearing of the cloth bag 46.

[0045] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A clean production system for compound fertilizer, characterized in that: The invention comprises a primary granulation device, a storage device, a metering device, a mixing device, a screening device and a packaging device. The primary granulation device prepares various raw materials of the compound fertilizer into granular raw materials. The storage device is used to store the granular raw materials after primary granulation. The metering device is used to weigh and meter the granular raw materials. The mixing device is used to mix and stir the weighed and metered granular raw materials. The screening device is used to screen the mixed granular raw materials. The packaging device is used to package the screened granular raw materials.

2. A clean production system for compound fertilizer according to claim 1, characterized in that: The diameter of the granular raw material after the primary granulation is 4-5mm or 5-30mm.

3. A clean production system for compound fertilizer according to claim 2, characterized in that: The mixing device comprises a blender and a mixer. The blender is used to mix granular raw materials with a diameter of 4-5 mm, and the mixer is used to mix granular raw materials with a diameter of 5-30 mm.

4. A clean production system for compound fertilizer according to claim 3, characterized in that: It also includes a crushing device and a secondary granulating device, wherein the crushing device is used to crush the granular raw materials mixed by the mixer, and the secondary granulating device is used to perform secondary granulation on the crushed granular raw materials. The granular raw materials after the secondary granulation are transported to the screening device for screening, and the screened granular raw materials are supplied to the packaging device.

5. A clean production system for compound fertilizer according to claim 4, characterized in that: The residual material produced during the screening by the screening device is transported to the granulation site as return material.

6. A clean production system for compound fertilizer according to claim 4, characterized in that: The primary granulation device and the secondary granulation device both adopt double-roller granulators, and the diameter of the granular raw materials granulated by the secondary granulation device is 4-5 mm.

7. The clean production system of compound fertilizer according to claim 1, characterized in that: The storage device comprises a silo (1), a feeding port (2) is arranged on one side of the top of the silo (1), a discharging port (3) is arranged at the bottom of the silo (1), a spiral downward material dropping chute (5) is arranged in the silo (1), and a stop valve (4) and a vibration motor (8) are arranged at the discharging port (3) of the silo (1).

8. A clean production system for compound fertilizer according to claim 7, characterized in that: A wind ball (9) for ventilation is arranged on the top of the silo (1), and a dehumidifier is arranged on the silo (1), and the dehumidifier is used to dehumidify the interior of the silo (1).

9. The clean production system of compound fertilizer according to claim 1, characterized in that: The invention also comprises a conveying device (10), wherein the conveying device (10) is used for conveying granular raw materials, and the conveying device (10) comprises an inclined tube (14) arranged obliquely, wherein an inlet (16) is arranged at one end at a high position of the inclined tube (14), and an outlet (18) is arranged at the other end thereof, and an isolation layer (19) is arranged inside the inclined tube (14), a material flow layer (20) is formed above the isolation layer (19), and a compressed air flow layer (21) is formed below the isolation layer (19), and the isolation layer (19) is provided with densely distributed through holes (22).

10. A clean production system for compound fertilizer according to claim 9, characterized in that: The conveying device (10) further comprises an air storage tank (24); an air intake pipe (23) connecting the air storage tank (24) and the inclined tube (14) is arranged between the air storage tank (24) and the inclined tube (14); a return air pipe (25) is connected to the inclined tube (14); an end of the return air pipe (25) away from the inclined tube (14) is connected to the air intake pipe (23); both the air intake pipe (23) and the return air pipe (25) are provided with a one-way valve (26); and the inclined tube (14) is made of a high-pressure vinyl chloride tube or a high-pressure polypropylene tube.

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