A production apparatus and method for urea granules

Abstract

This invention relates to the field of urea production technology, specifically to a production apparatus for urea granules. The apparatus includes a molten ladle and a processing cylinder, which are connected and arranged vertically. A receiving hopper for holding medium-sized urea granules is installed inside the processing cylinder. The processing cylinder is equipped with a feed pipe that conveys the medium-sized urea granules and whose outlet is aligned with the receiving hopper. A shaking mechanism is installed on both sides of the receiving hopper. A discharge pipe with a valve is located below the receiving hopper on the processing cylinder. This invention uses the shaking mechanism to reciprocate the shaking of the receiving hopper, causing the medium-sized urea granules to flip and fully contact the urea droplets, resulting in large, uniform granules.

Description

Technical Field

[0001] This invention relates to the field of urea production technology, specifically to an apparatus and method for producing urea granules. Background Technology

[0002] Urea is a high-quality nitrogen fertilizer widely used in agriculture. Compared with other nitrogen fertilizers, urea has a high effective nutrient concentration (nitrogen content ≥46%), a certain degree of hygroscopicity, and no adverse effects on the soil with long-term use. With the improvement of agricultural mechanization, farmers' awareness of large-particle and medium-particle urea is gradually increasing, and the application rate and market demand are increasing year by year. How to efficiently produce high-quality granular urea products of specific sizes and uniform particle size has become an important direction for technological research and development.

[0003] Patent CN109437984B discloses a production device and operating process for converting large urea particles into medium-sized particles. It uses a combined granulation drum to generate particles of different sizes from urea solution under the action of fluidized air. A sieve is connected to the combined granulation drum via a conveying pipe. The sieve includes a mixing chamber, an isolation channel, and a filtration chamber. The mixing chamber includes a rotating shaft, a dispersing rod, a sleeve, a rotating rod, and a dispersing mesh. The filtration chamber has a first filter plate and a second filter plate arranged from top to bottom. The crusher includes a crushing roller, a hydraulic rod, a pressure relief component, a first fixed plate, a second fixed plate, and a lead screw. A cooler is connected to the mixing chamber, filtration chamber, and crusher via a conveying channel. A tail gas processor is used to collect the waste gas generated during the process. A monitor includes an A / D converter, a control unit, a data quantification and analysis unit, and a power supply unit for real-time monitoring of the process.

[0004] The aforementioned device uses a combined granulation drum to generate urea solution into particles of different sizes under the action of fluidized air. However, the device cannot agitate the medium-sized urea particles during processing, causing the fine droplets of the atomized urea solution to fall in one position for a long time. This results in the medium-sized urea particles being in contact with the fine droplets on one side for an extended period, reducing processing efficiency and quality. Furthermore, the size of the feed inlet cannot be adjusted during use, resulting in a fixed particle feed diameter and poor applicability.

[0005] In view of this, the present invention discloses a production apparatus for urea granules. Summary of the Invention

[0006] The purpose of this invention is to provide a production apparatus for urea granules. This apparatus is equipped with a melting tank, an atomizing pump, a shaking mechanism, and an adjusting mechanism. First, the melting tank, in conjunction with the atomizing pump, atomizes urea into fine droplets, which then crystallize and solidify onto medium-sized urea particles above the receiving hopper inside the processing cylinder. Simultaneously, the shaking mechanism reciprocates the receiving hopper, turning the medium-sized urea particles over so that they fully contact the urea droplets. After processing, the urea is discharged through a discharge port. The adjusting mechanism inside the discharge port allows for adjustment of the opening size, accommodating urea particles of different sizes and improving practicality and applicability.

[0007] The basic concept of the technical solution of this invention is as follows:

[0008] A production apparatus for urea granules includes a processing cylinder and a melting tank that are connected to each other, the processing cylinder being located below the melting tank; a receiving hopper for holding medium-sized urea is installed inside the processing cylinder, the processing cylinder is provided with a feed pipe for conveying the medium-sized urea, the outlet of the feed pipe being located above the receiving hopper, a shaking mechanism is installed on both sides of the receiving hopper, and a discharge pipe with a valve is provided below the receiving hopper in the processing cylinder.

[0009] As an example, the top of the processing cylinder is connected to a cylinder cover, and several support rods are provided between the bottom of the melting tank and the cylinder cover, and a discharge pipe connecting the melting tank and the processing cylinder is provided;

[0010] A sealing plate is installed below the cylinder cover, and the feed pipe passes through the cylinder cover and the sealing plate in sequence until it extends into the interior of the processing cylinder and is connected to an atomizing pump at the lower end.

[0011] As an example, the vibration mechanism includes a vibration groove, a first motor, and a transmission disc. The vibration groove is formed on both sides inside the processing cylinder. The first motor is installed below one side inside the vibration groove. The power output shaft of the first motor is connected to the transmission disc. The disc surface of the transmission disc is connected to one end of a first connecting rod. The other end of the first connecting rod is connected to one end of a second connecting rod. The other end of the second connecting rod is connected to one end of a connecting rod, and the other end of the connecting rod is connected to both sides of the receiving hopper.

[0012] Preferably, one end of the limiting rod is installed on the outside of the second connecting rod, a limiting groove is formed on the right side inside the shaking groove, and the other end of the limiting rod is connected inside the limiting groove.

[0013] As an example, an adjustment mechanism is installed inside the receiving hopper. The adjustment mechanism includes a discharge port, a second motor, and a mounting slot. The discharge port extends through the interior of the receiving hopper, and the mounting slot is located inside the discharge port. The second motor is mounted on the right side of the shaft inside the mounting slot. The power output shaft of the second motor is connected to a screw. A threaded sleeve is threaded onto the outer side of the screw. One end of an adjusting rod is connected to the left side of the outer side of the threaded sleeve, and the adjusting rod is entirely fitted onto the outer side of the screw. The other end of the adjusting rod is connected to a sealing plug. One end of an adjusting plate is connected to the outer side of the sealing plug. A sealing groove is provided inside the discharge port at a mirror position of the mounting slot, and the other end of the adjusting plate is inserted into the sealing groove.

[0014] As an example, the mounting groove has sliding grooves on both sides inside, one end of a slider is slidably connected inside the sliding groove, and the other end of the slider is connected to both sides of the threaded sleeve.

[0015] As an example, the outside of the feed tube is wrapped with a heating wire, and the outside of the heating wire is wrapped with a heat insulation layer.

[0016] As an example, it also includes a formaldehyde gas cylinder disposed outside the processing cylinder, the formaldehyde gas cylinder being connected to a gas pump, one end of which is connected to a delivery pipe above the gas pump, and the other end of the delivery pipe extending to the bottom of a receiving hopper inside the processing cylinder and provided with a gas distribution structure.

[0017] The present invention provides a method for producing urea granules, characterized in that the production method is carried out in a production apparatus according to any one of the above descriptions.

[0018] As an example, the method includes the following steps:

[0019] A urea solution with a mass concentration of 85-95% and a temperature of 75-100℃ is fed through the feed pipe and sprayed onto medium-particle urea on the receiving hopper by an atomizing pump.

[0020] At the same time, the shaking mechanism is activated to shake and flip the medium-particle urea on the receiving hopper;

[0021] After the urea solution is fed in, turn off the shaking mechanism, let it stand, and then discharge the material.

[0022] As an example, formaldehyde gas is introduced into the gas distribution structure below the receiving hopper while the shaking mechanism is activated, to agitate and stir the medium-sized urea particles on the receiving hopper.

[0023] Preferably, the urea solution contains 0.2% to 0.6% thiourea and 0.1% to 0.3% cyclodextrin.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] This invention, equipped with a melting tank, an atomizing pump, a shaking mechanism, and an adjusting mechanism, first uses the melting tank in conjunction with the atomizing pump to atomize urea into fine droplets, which then crystallize and solidify on medium-sized urea particles above the receiving hopper inside the processing cylinder. Simultaneously, the shaking mechanism reciprocates the receiving hopper, turning the medium-sized urea particles over so that they fully contact the urea droplets. After processing, the urea is discharged through the discharge port. The adjusting mechanism inside the discharge port allows for adjustment of the opening size, accommodating the discharge of urea particles of different sizes, thus achieving control and improving practicality and applicability.

[0026] The large urea particles produced by the device of this invention have a smooth and round appearance, which improves the appearance quality of large urea particles. Moreover, when used to prepare slow-release modified urea particles, it helps to improve the efficiency of later processes such as coating and enhances market competitiveness. Attached Figure Description

[0027] Figure 1 This is an overall schematic diagram of a production apparatus for urea granules according to the present invention.

[0028] Figure 2 This is a schematic diagram of the adjustment mechanism of a urea granule production device according to the present invention;

[0029] Figure 3 This is a schematic diagram of the shaking mechanism of a urea granule production device according to the present invention.

[0030] Marked in the image:

[0031] 1. Processing cylinder; 2. Vibration mechanism; 201. Vibration groove; 202. Transmission disc; 203. First motor; 204. Limiting groove; 205. Connecting rod; 206. Second connecting rod; 207. First connecting rod; 208. Limiting rod; 3. Adjustment mechanism; 301. Discharge port; 302. Sealing groove; 303. Adjusting plate; 304. Mounting groove; 305. Second motor; 306. Screw; 307. Slider; 308. Screw sleeve; 309. 310. Slide chute; 311. Adjusting sleeve rod; 312. Sealing plug; 4. Feed pipe; 5. Cylinder cover; 6. Heating wire; 7. Discharge pipe; 8. Support rod; 9. Atomizing pump; 10. Sealing plate; 11. Melting tank; 12. Sealing ring; 13. Tank cover; 14. Connecting column; 15. Base; 16. Discharge pipe; 17. Receiving hopper; 18. Insulation layer; 19. Control valve; 20. Formaldehyde gas tank; 21. Gas pump; 22. Conveying pipe; 23. Gas distribution structure. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The particle size of the medium-sized urea in this invention is 1.18 mm to 3.35 mm, and the urea granule product is large-particle urea with a particle size of 2.00 mm to 4.75 mm or 5 mm to 8 mm.

[0034] Example 1

[0035] like Figures 1-3 As shown, a production apparatus for urea granules includes a processing cylinder 1 and a melting tank 11, with the processing cylinder 1 located below the melting tank 11.

[0036] Specifically, as an example, a lid 13 is installed on the top of the melting tank 11. The lid 13 is fixed by a connecting post installed on the top left side of the melting tank 11, and a sealing ring 12 is installed below the lid 13.

[0037] A base 15 is installed below the processing cylinder 1. A feed pipe 4 for supplying medium-particle urea is connected to the upper left side of the processing cylinder 1, and a discharge pipe 16 is connected to the lower right side of the processing cylinder 1. A control valve 19 is installed on the discharge pipe 16. The control valve 19 not only controls the discharge but also ensures that there is no leakage when gas is injected into the lower part of the processing cylinder 1 later.

[0038] The processing cylinder 1 is equipped with a receiving hopper 17 for placing medium-sized urea. The outlet of the feed pipe 4 is located above the receiving hopper 17. A shaking mechanism 2 for shaking the receiving hopper 17 is installed on both sides of the receiving hopper 17.

[0039] A manual or electric valve can be installed on the feed pipe 4. A conventional setting can be used. No view is provided in this invention.

[0040] like Figure 3As shown, as an example, the vibration mechanism 2 includes a vibration groove 201, a first motor 203, and a transmission disc 202. The vibration groove 201 is formed on both sides inside the processing cylinder 1. The first motor 203 is installed below one side inside the vibration groove 201. The power output shaft of the first motor 203 is connected to the transmission disc 202. The disc surface of the transmission disc 202 is connected to one end of the first connecting rod 207. The other end of the first connecting rod 207 is connected to one end of the second connecting rod 206. The other end of the second connecting rod 206 is connected to one end of the connecting rod 205. The other end of the connecting rod 205... The first motor 203 can drive the transmission disc 202 to rotate, causing the first connecting rod 207 to rotate as well. When the first connecting rod 207 rotates, it causes the second connecting rod 206 to move as well. At the same time, the limiting rod 208 on the outside of the second connecting rod 206 slides inside the limiting groove 204, thereby limiting the rotation of the second connecting rod 206. This allows the second connecting rod 206 to move up and down reciprocally inside the shaking groove 201, causing the connecting rod 205 and the receiving hopper 17 to shake and flip the urea particles in the middle.

[0041] One end of the limiting rod 208 is connected to the outer side of the second connecting rod 205. A limiting groove 204 is opened on the right side of the inside of the shaking groove 201. The other end of the limiting rod 208 is connected to the inside of the limiting groove 204. The limiting rod 208 slides inside the limiting groove 204 to limit the rotation of the second connecting rod 206.

[0042] like Figure 2 As shown, an adjusting mechanism 3 is installed inside the receiving hopper 17. The adjusting mechanism 3 includes a discharge port 301, a second motor 305, and a mounting groove 304. The discharge port 301 is opened through the inside of the receiving hopper 17, and the mounting groove 304 is opened inside the discharge port 301. The second motor 305 is installed at the right side of the shaft inside the mounting groove 304. The power output shaft of the second motor 305 is connected to a screw 306. A screw sleeve 308 is threadedly connected to the outside of the screw 306. One end of an adjusting sleeve rod 310 is connected to the outer left side of the screw sleeve 308, and the adjusting sleeve rod 310 is entirely sleeved on the outside of the screw 306. A sealing plug 311 is connected to the other end of the adjusting sleeve rod 310. One end of the side-connected adjusting plate 303 has a sealing groove 302 on the inner side of the discharge port 301, which is located in the mirror position of the mounting groove 304. The other end of the adjusting plate 303 is inserted into the sealing groove 302. The second motor 305 can drive the screw 306 to rotate, so that the screw 306 drives the outer screw sleeve 308 to rotate. At the same time, the sliders 307 on both sides of the screw sleeve 308 slide inside the sliding groove 309 to restrict the rotation of the screw sleeve 308. The screw sleeve 308 moves outside the screw 306, which drives the adjusting sleeve rod 310 to move accordingly. When the adjusting sleeve rod 310 moves, it drives the sealing plug 311 and the adjusting plate 303 to move. The adjusting plate 303 adjusts the size of the discharge port 301.

[0043] The mounting groove 304 has sliding grooves 309 on both sides inside. One end of the slider 307 is slidably connected inside the sliding groove 309, and the other end of the slider 307 is connected to both sides of the threaded sleeve 308. The slider 307 slides inside the sliding groove 309 to restrict the rotation of the threaded sleeve 308.

[0044] As an example, the top of the processing cylinder 1 is provided with a cylinder cover 5, and two or more support rods 8 are provided between the bottom of the melting tank 11 and the cylinder cover 5, and a discharge pipe 7 connecting the melting tank 11 and the processing cylinder 1 is provided.

[0045] As an example, specifically, a sealing plate 10 is installed below the cylinder cover 5, and one end of the feed pipe 7 is connected to the lower axis of the melting tank 11. The other end of the feed pipe 7 extends through the cylinder cover 5 and the sealing plate 10 until it enters the interior of the processing cylinder 1, and is connected to an atomizing pump 9 at the lower end.

[0046] The melting tank 11 is used in conjunction with the atomizing pump 9 to atomize urea into fine droplets that fall downwards and then into the receiving hopper 17, where they crystallize and solidify on the medium-sized urea placed above the receiving hopper 17. At the same time, the shaking mechanism 2 reciprocates the shaking of the receiving hopper 17, turning the medium-sized urea over so that it can fully contact the urea droplets to form uniform large-particle urea.

[0047] After processing, the urea is discharged through the discharge port 301. The adjustment mechanism 3 inside the discharge port 301 can adjust the opening size of the discharge port 301 to meet the discharge of urea particles of different sizes, thus improving practicality and applicability.

[0048] As an optimization, a formaldehyde gas tank 20 is further provided, which is connected to a gas pump 21. A delivery pipe 22 is provided above the gas pump 21. One end of the delivery pipe 22 is connected to the gas pump 21, and the other end extends to the bottom of the receiving hopper 17 inside the processing cylinder 1. A gas distribution structure 23 is also provided.

[0049] Preferably, while the shaking mechanism 2 is activated, formaldehyde gas is introduced into the gas distribution structure 23 located below the receiving hopper 17 to agitate and stir the medium-sized urea particles on the receiving hopper 17, promoting the formation of large-sized urea particles and resulting in a more aesthetically pleasing appearance. The particles are more regular and smooth, improving processing efficiency and quality.

[0050] Furthermore, as an example of optimization, the outer side of the feed pipe 7 is wrapped with a heating wire 6, and the outer side of the heating wire 6 is wrapped with a heat insulation layer 18, ensuring that the molten liquid in the melting tank 11 does not solidify as it flows down, thus improving processing quality. The heat insulation layer 18 is provided outside the heating wire 6 to reduce heat loss.

[0051] Example 2

[0052] Based on the apparatus described in Example 1.

[0053] A method for producing urea granules according to the present invention:

[0054] In use, a urea solution with a mass concentration of 85-95% and a temperature of 75-100℃ is first fed through the feed pipe 7. Then, the urea solution is sprayed by the atomizing pump 9 onto the upper part of the processing cylinder 1, where it falls onto the outside of the medium-sized urea particles and crystallizes and solidifies. At the same time, the first motor 203 is powered by an external power source, which drives the transmission disk 202 to rotate, causing the first connecting rod 207 to rotate as well. When the first connecting rod 207 rotates, it drives the second connecting rod 206 to move as well. Meanwhile, the limiting rod 208 on the outside of the second connecting rod 206 slides inside the limiting groove 204, thereby limiting the rotation of the second connecting rod 206. This allows the second connecting rod 206 to move up and down reciprocally inside the shaking groove 201, causing the connecting rod 205 and the receiving bucket 17 to reciprocate and shake, thus shaking and turning the medium-sized urea particles.

[0055] Preferably, while activating the shaking mechanism 2, formaldehyde gas is introduced into the gas distribution structure 23 located below the receiving hopper 17 to agitate the medium-sized urea particles on the receiving hopper 17. This process uses formaldehyde gas to subtly shape and reshape the surface of the particles, resulting in a smoother and more uniform appearance. When used as a raw material for the preparation of slow-release modified urea, it can reduce the time spent on processes such as coating, thereby shortening the overall process time and improving efficiency.

[0056] During feeding, the second motor 305 is powered by an external power source, which drives the screw 306 to rotate. This causes the screw 306 to rotate the outer screw sleeve 308. At the same time, the sliders 307 on both sides of the screw sleeve 308 slide inside the groove 309, which restricts the rotation of the screw sleeve 308. The screw sleeve 308 then moves outside the screw 306, causing the adjusting sleeve rod 310 to move accordingly. When the adjusting sleeve rod 310 moves, it causes the sealing plug 311 and the adjusting plate 303 to move. The adjusting plate 303 adjusts the size of the feeding port 301 to limit the particle size. Finally, the particles are discharged through the discharge pipe 16.

[0057] The obtained large-particle urea has a smooth and regular surface with good uniformity, and the particle size of the large-particle urea is ≥92% for 2.00mm~4.75mm or ≥92% for 5mm~8mm.

[0058] Example 3

[0059] The only difference from Example 2 is that a urea solution with a mass concentration of 80% and a temperature of 110°C is used; everything else remains the same.

[0060] The surface smoothness, regularity, and uniformity of the obtained large-particle urea were slightly inferior to those in Example 2, wherein the particle size of the large-particle urea was 2.00 mm to 4.75 mm ≥ 90% or 5 mm to 8 mm ≥ 90%.

[0061] Example 4

[0062] The only difference from Example 2 is that a urea solution with a mass concentration of 97% and a temperature of 70°C is used; everything else remains the same.

[0063] The surface smoothness, regularity, and uniformity of the obtained large-particle urea were slightly inferior to those in Example 2, wherein the particle size of the large-particle urea was 2.00 mm to 4.75 mm ≥ 85% or 5 mm to 8 mm ≥ 85%.

[0064] Example 5

[0065] The only difference from Example 2 is the addition of 0.3% thiourea and 0.2% cyclodextrin by weight of the urea solution; all other aspects remain unchanged.

[0066] The obtained large-particle urea has a slightly better surface smoothness, regularity, and uniformity than that of Example 2, wherein the particle size of the large-particle urea is 2.00 mm to 4.75 mm ≥ 95% or 5 mm to 8 mm ≥ 95%. Moreover, its fertilizer efficiency is 20% higher than that of the large-particle urea in Example 2.

[0067] Example 6

[0068] The only difference from Example 2 is the addition of 0.6% thiourea and 0.1% cyclodextrin by weight of the urea solution, while all other aspects remain unchanged.

[0069] The obtained large-particle urea has a slightly better surface smoothness, regularity, and uniformity than that of Example 2, wherein the particle size of the large-particle urea is 2.00 mm to 4.75 mm ≥ 93% or 5 mm to 8 mm ≥ 93%. Moreover, the fertilizer efficiency is 35% higher than that of the large-particle urea in Example 2.

[0070] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection defined by the claims submitted herein.

Claims

1. A production apparatus for urea granules, characterized in that: The device includes a connected processing cylinder (1) and a melting tank (11), with the processing cylinder (1) located below the melting tank (11); a receiving hopper (17) for holding medium-sized urea is installed inside the processing cylinder (1); the processing cylinder (1) is provided with a feed pipe (4) for conveying medium-sized urea; the outlet of the feed pipe (4) is located above the receiving hopper (17); a shaking mechanism (2) is installed on both sides of the receiving hopper (17); and a discharge pipe (16) with a valve is provided below the receiving hopper (17) in the processing cylinder (1). The top of the processing cylinder (1) is connected to a cylinder cover (5), and several support rods (8) are provided between the bottom of the melting tank (11) and the cylinder cover (5), and a feed pipe (7) is provided to connect the melting tank (11) and the processing cylinder (1). A sealing plate (10) is installed below the cylinder cover (5). The feed pipe (7) passes through the cylinder cover (5) and the sealing plate (10) in sequence until it extends into the interior of the processing cylinder (1) and is connected to an atomizing pump (9) at the lower end. The vibration mechanism (2) includes a vibration groove (201), a first motor (203), and a transmission disc (202). The vibration groove (201) is formed on both sides inside the processing cylinder (1). The first motor (203) is installed below one side inside the vibration groove (201). The power output shaft of the first motor (203) is connected to the transmission disc (202). The disc surface of the transmission disc (202) is connected to one end of the first connecting rod (207), and the other end of the first connecting rod (207) is connected to the transmission disc (202). One end of the second connecting rod (206) is connected to the other end of the connecting rod (205), and the other end of the connecting rod (205) is connected to both sides of the receiving bucket (17); one end of the limiting rod (208) is installed on the outside of the second connecting rod (205) of the second connecting rod (206), and a limiting groove (204) is opened on the right side inside the shaking groove (201), and the other end of the limiting rod (208) is connected to the inside of the limiting groove (204); It also includes a formaldehyde gas tank (20) located outside the processing cylinder (1), the formaldehyde gas tank (20) is connected to a gas pump (21), one end of a delivery pipe (22) is connected above the gas pump (21), and the other end of the delivery pipe (22) extends to the bottom of the receiving hopper (17) inside the processing cylinder (1) and is provided with a gas distribution structure (23).

2. The production apparatus for urea granules according to claim 1, characterized in that: An adjustment mechanism (3) is installed inside the receiving hopper (17). The adjustment mechanism (3) includes a discharge port (301), a second motor (305), and a mounting groove (304). The discharge port (301) extends through the interior of the receiving hopper (17). The mounting groove (304) is located inside the discharge port (301). The second motor (305) is mounted on the right side of the mounting groove (304). The power output shaft of the second motor (305) is connected to a screw (306). The outer side of the screw (306) is threaded. There is a threaded sleeve (308), and one end of an adjusting sleeve rod (310) is connected to the left side of the outer side of the threaded sleeve (308). The adjusting sleeve rod (310) is sleeved on the outside of the screw rod (306). The other end of the adjusting sleeve rod (310) is connected to a sealing plug (311). One end of an adjusting plate (303) is connected to the outside of the sealing plug (311). A sealing groove (302) is opened on the inner side of the discharge port (301) at the mirror position of the mounting groove (304). The other end of the adjusting plate (303) is inserted into the inside of the sealing groove (302).

3. The production apparatus for urea granules according to claim 2, characterized in that: The mounting groove (304) has sliding grooves (309) on both sides inside. One end of a slider (307) is slidably connected inside the sliding groove (309), and the other end of the slider (307) is connected to both sides of the screw sleeve (308).

4. The production apparatus for urea granules according to claim 1, characterized in that: The outside of the feed pipe (7) is wrapped with a heating wire (6), and the outside of the heating wire (6) is wrapped with a heat insulation layer (18).

5. A method for producing urea granules, characterized in that, The production method is carried out in the production apparatus according to any one of claims 1-4, and includes the following steps: 1) A urea solution with a mass concentration of 85~95% and a temperature of 75~100℃ is fed through the feed pipe (7) and sprayed by the atomizing pump (9) onto the medium-particle urea in the receiving hopper (17); 2) Start the shaking mechanism (2) to make the receiving bucket (17) shake back and forth, and at the same time introduce formaldehyde gas into the gas distribution structure (23) to agitate and stir the medium-sized urea on the receiving bucket (17). 3) Turn off the shaking mechanism (2), let it stand to crystallize, and discharge the large-particle urea product through the discharge pipe (16); The urea solution contains 0.2% to 0.6% thiourea and 0.1% to 0.3% cyclodextrin by mass of the urea solution.

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