Spray granulation process and device thereof

Abstract

The invention relates to the technical field of ceramic product production and manufacturing equipment and a preparation process, in particular to a spray granulation process which comprises the following steps: preparing zirconium oxide slurry with the solid content of 90%, conveying the zirconium oxide slurry to a nozzle through a pipeline, and enabling the slurry to meet airflow at the nozzle and be atomized into tiny liquid drops; atomized liquid drops make contact with hot airflow for drying, the airflow temperature is controlled by a temperature control system to gradually rise from the inlet section to the outlet section of the main tower, and an airflow system adjusts the airflow speed and the airflow direction; the particles with the particle size larger than or equal to 40 micrometers fall to a discharging port in the bottom of the main tower under the action of strong airflow, and the particle size is lt; particles with the particle size of 40 microns flow to a brown air opening under the action of relatively weak air flow; the dried large particles are guided out from a discharge hole in the bottom of the main tower through a strong airflow regulator to be collected, and the dried small particles are collected through a connecting pipeline and a cyclone separator through an air inlet; the large particles are directly stored or subsequently processed, and the small particles are further processed or sub-packaged. Precise classified collection is achieved, and the granulation quality and the production efficiency are improved.

Description

Technical Field

[0001] This application relates to the technical field of ceramic product manufacturing equipment and preparation processes, and particularly to a spray granulation process and its device. Background Art

[0002] A spray granulation device is a device that uses spray technology to atomize liquid raw materials into fine particles and dries them into solid particles through hot air. This technology is widely used in industries such as chemical engineering, ceramics, pharmaceuticals, and food. Especially when producing materials with high requirements for fine particles and uniformity, it has significant advantages.

[0003] Chinese Patent CN116492916A discloses a spray granulation device for ceramic production processes, which includes a spray granulation tower, a raw material barrel, a transfer pump, a blower, a heater, a cyclone separator, a bag filter, an induced draft fan, and a spray device; the spray device includes a rotary atomization device, and the rotary atomization device includes a lower disk, an upper disk, a blade group, and a threaded connector; its characteristics are: the blade group includes a first blade group and a second blade group, the first blade group includes blades A, C, E, the second blade group includes blades B, D, the first blade group is connected to the upper surface of the lower disk 11 and has a gap with the upper disk, the second blade group is connected to the lower surface of the upper disk and has a gap with the lower disk 11, and blades A, C, E and blades B, D are arranged at intervals along the radial direction. The present invention can improve the atomization / particle size distribution uniformity of raw materials in the spray granulation tower, reduce the particle size of raw materials, and thus improve the spray granulation effect and efficiency.

[0004] Although the prior art has improved the atomization and particle size distribution uniformity in the spray granulation tower, during the drying stage, when the solvent in the droplets evaporates, the particles may adhere to each other due to surface tension, electrostatic interaction, or incomplete drying. In addition, uneven temperature gradients, airflow distribution, or particle collisions during the collection process in the drying process may also cause agglomeration. Summary of the Invention

[0005] In order to overcome the problems existing in the prior art, this application provides a spray granulation process and its device.

[0006] The spray granulation process and its device provided by this application adopt the following technical solutions:

[0007] A spray granulation process includes the following steps:

[0008] Step 1: Preparation and transportation of the slurry: Prepare a zirconia slurry with a solid content of 90%, and transport it to the nozzle through the pipeline of the pumping device. The slurry meets the airflow generated by the high-speed airflow generator at the nozzle and is atomized into tiny droplets;

[0009] Step 2: Drying and classification. The atomized droplets come into contact with hot air flow for drying. The temperature of the air flow is controlled by a temperature control system, and it gradually rises from the inlet section to the outlet section of the main tower. The temperature control system ensures the stability of the temperature inside the tower to avoid uneven particle distribution caused by temperature changes. The air flow system adjusts the air flow velocity and direction. Particles with a particle size ≥ 40 μm fall to the discharge port at the bottom of the main tower under the action of strong air flow, and particles with a particle size < 40 μm flow to the Xuanfeng port under the action of weaker air flow, realizing particle classification.

[0010] Step 3: Particle collection stage. The dried particles are collected through the air flow system. Among them, the large particles are exported from the discharge port at the bottom of the main tower through a strong air flow regulator for collection, and the small particles are collected through a connecting pipe to the cyclone separator via the Xuanfeng port.

[0011] Step 4: Product collection and post-treatment. The large particles directly enter storage or subsequent processing, and the small particles are further processed or packaged separately for different application requirements.

[0012] By adopting the above technical solution, during the zirconia spray granulation process, this process effectively solves the agglomeration problem through the synergistic effect of multiple stages. When the slurry is atomized, for the zirconia slurry with a high solid content acting on the air flow generated by the high-speed air flow generator, the particles are evenly distributed in the tiny droplets, reducing the chance of agglomeration. In the drying and classification stage, the temperature control system precisely controls the temperature to gradually rise from the inlet section to the outlet section of the main tower, ensuring uniform drying of the droplets and avoiding rapid drying that may cause rapid surface crusting, where the internal solvent cannot escape, forming hollow particles or causing agglomeration after rupture. At the same time, the air flow system adjusts the air flow velocity and direction, making it difficult for particles to aggregate in the dynamic air flow. In the particle collection stage, strong and weak air flows respectively guide particles of different particle sizes, avoiding static accumulation of particles and collision and adhesion between large and small particles. In the product collection and post-treatment stage, they are processed separately according to the use of the particles. Especially for the surface modification of small particles, the surface properties are optimized to reduce the agglomeration tendency.

[0013] A spray granulation device comprises the following components:

[0014] A slurry atomization unit, which includes a storage tank, a pumping device, and a nozzle. The storage tank is used to hold the zirconia slurry with a solid content of 90%. The pumping device is connected to the storage tank through a pipeline and transports the slurry to the nozzle at a pressure of 10 - 20 MPa. The gas inlet of the nozzle is connected to a high-speed air flow generator with a flow velocity of 50 - 80 m / s, which is used to atomize the slurry into droplets with a particle size of 10 - 100 μm.

[0015] Gradient temperature-controlled drying and classification unit, including a main tower, a temperature control system and an air flow system. The top of the main tower is provided with a nozzle, and the main tower is divided into an inlet section and an outlet section; the temperature control system includes a low-temperature heater arranged in the inlet section and a high-temperature heater arranged in the outlet section, controlling the temperature of the inlet section to be 200-400 °C and the temperature of the outlet section to be 600-800 °C respectively; the air flow system includes a strong air flow fan at the bottom of the main tower and a weak air flow regulator in the middle of the main tower. The strong air flow fan generates a downward air flow with a flow rate of 5-8 m / s, and the weak air flow regulator generates a lateral air flow with a flow rate of 1-3 m / s;

[0016] Particle classification and collection unit: including the discharge port at the bottom of the main tower, the Xuanfeng port and the cyclone separator. The discharge port at the bottom of the main tower is used to collect particles with a particle size of ≥40 μm. The Xuanfeng port is connected to the weak air flow regulator and transports particles with a particle size of <40 μm to the cyclone separator for collection.

[0017] By adopting the above technical solution, zirconia slurry with a solid content of 90% in the storage tank is transported through a pipeline to a nozzle connected to a high-speed air flow generator with a flow rate of 50-80 m / s by a pumping device under a pressure of 10-20 MPa, and is atomized into tiny droplets with a size of 10-100 μm under the impact and shear of the high-speed air flow, laying a foundation for subsequent drying and granulation; the atomized droplets enter from the nozzle at the top of the main tower. The main tower is divided into an inlet section and an outlet section. The low-temperature heater in the inlet section controls the temperature at 200-400 °C to make the droplets initially evaporate water and partially solidify. The high-temperature heater in the outlet section raises the temperature to 600-800 °C to promote its further drying and solidification into particles. The strong air flow fan at the bottom of the main tower generates a downward air flow of 5-8 m / s to accelerate the falling and drying of the particles. The weak air flow regulator in the middle generates a lateral air flow of 1-3 m / s to make the particles evenly distributed and generate different acting forces according to the particle size, realizing preliminary classification; after gradient temperature-controlled drying and preliminary classification, larger particles with a particle size of ≥40 μm are collected from the discharge port at the bottom of the main tower under the action of gravity and downward strong air flow. Smaller particles with a particle size of <40 μm are transported to the cyclone separator through the Xuanfeng port under the influence of the lateral weak air flow, and the collection of small particles is completed by using centrifugal force, realizing accurate classification and collection according to particle size based on the differences in the movement characteristics of particles with different particle sizes in the air flow.

[0018] Preferably, a number of groups of tangential inlet pipes evenly distributed circumferentially along the side wall of the main tower are adopted on the side wall in the middle of the main tower. The angle between the axis of the tangential inlet pipe and the tangent direction of the inner wall of the spray tower is 15°-30°, and each tangential inlet pipe is connected to an external compressed air source through an independent air flow pipeline; the gas output by the compressed air source is preheated to 80-120 °C by a heater and then sprayed into the main tower from the tangential inlet pipe at a flow rate of 8-12 m / s under the action of an air inlet pump, forming a swirling flow field surrounding the atomized droplets.

[0019] Preferably, an adjustable guide pipe is further provided at the outlet of the tangential inlet pipe. The adjustable guide pipe is rotatably connected to the main tower wall and is driven by a micro motion air cylinder to adjust within a range of 30°-60°.

[0020] Preferably, the micro motion air cylinders are located on both sides of the adjustable guide plate and are respectively located on both sides of the rotating shaft of the adjustable guide plate and the main tower wall. An elastic heat insulation layer is used for sealing connection between the adjustable guide plate and the main tower wall, and the outer end of the adjustable guide plate is communicated with the tangential inlet pipe through an elastic threaded air pipe.

[0021] By adopting the above technical solutions, in the spray granulation equipment, a plurality of groups of tangential inlet pipes evenly distributed along the circumferential direction are arranged on the side wall in the middle of the main tower. The included angle between the axis of the tangential inlet pipe and the tangent direction of the inner wall of the spray tower is 5°-30°. Each tangential inlet pipe is connected to an external compressed air source through an independent air flow pipeline. The gas output by the compressed air source is first preheated to 80-120 °C by a heater and then sprayed into the main tower from the tangential inlet pipe at a flow rate of 8-12 m / s under the action of an air inlet pump, so as to form a swirling flow field surrounding the atomized droplets. An adjustable guide pipe is provided at the outlet of the tangential inlet pipe. The adjustable guide plate is rotatably connected to the main tower wall and is driven by the micro motion air cylinders located on both sides of it and respectively on both sides of the rotating shaft of the main tower wall, and can be adjusted within a range of 30°-60°. An elastic heat insulation layer is used for sealing connection between the adjustable guide plate and the main tower wall, and the outer end is communicated with the tangential inlet pipe through an elastic threaded air pipe, so as to flexibly adjust the direction and angle of the air flow ejected from the tangential inlet pipe and further optimize the action effect of the swirling flow field on the atomized droplets and particles.

[0022] Preferably, an annular bracket is fixedly installed at the inner top of the main tower. A plurality of groups of ultrasonic vibration plates are symmetrically arranged on the annular bracket. Each group of ultrasonic vibration plates includes a plurality of piezoelectric ceramic sheets arranged in the vertical direction and is connected to the start-stop signal of the atomizing nozzle through a controller.

[0023] By adopting the above technical solutions, when the atomizing nozzle starts to perform the slurry atomization operation, the controller receives the start signal and immediately triggers the ultrasonic vibration plate to work. The piezoelectric ceramic sheets generate vibrations after receiving the electrical signal and then emit ultrasonic waves. The ultrasonic waves propagate in the space at the inner top of the main tower and act on the slurry droplets just ejected from the atomizing nozzle. The energy of the ultrasonic waves can further refine the droplets, prevent the droplets from agglomerating in the initial stage, help to form smaller droplets with more uniform particle sizes, thereby optimizing the formation quality of the droplets in the early stage of the entire spray granulation process and laying a better foundation for subsequent drying, classification, collection and post-treatment and other links; when the atomizing nozzle stops working, the controller receives the stop signal and the ultrasonic vibration plate also stops working.

[0024] Preferably, an ion wind rod and a nitrogen injection system are sequentially arranged in the connecting pipeline between the air outlet and the cyclone separator.

[0025] Preferably, the ion air bars are used to neutralize the static charges on the surface of the particles and are arranged at equal intervals along the axial direction of the pipeline. Each group contains discharge needles with alternating positive and negative electrodes.

[0026] Preferably, the nitrogen injection system includes a nitrogen storage tank, a gas distribution ring, and a flow controller. The nitrogen storage tank is connected to the gas distribution ring through a main pipeline. The gas distribution ring is embedded in the inner wall of the pipeline, and a number of micropores are evenly opened around the circumference. Nitrogen is sprayed into the pipeline radially through the micropores. The flow controller adjusts the nitrogen flow rate according to the real-time detection data of the oxygen sensor in the pipeline to make the oxygen content ≤ 0.5%.

[0027] Preferably, the end of the connecting pipeline is provided with a conical flaring section. The flaring angle of the flaring section is 30° - 45°, and spiral guide vanes for reducing the particle flow rate and dispersing the movement trajectory are welded on the inner wall.

[0028] By adopting the above technical solutions, an ion air bar and a nitrogen injection system are sequentially arranged in the connecting pipeline between the tuyere and the cyclone separator. The ion air bar can generate ion wind to neutralize the surface charges of small particles during transportation, reducing the agglomeration caused by electrostatic interaction between particles. The nitrogen injection system consists of a nitrogen storage tank, a gas distribution ring, and a flow controller. The nitrogen storage tank is connected to the gas distribution ring embedded in the inner wall of the pipeline through a main pipeline. The micropores evenly opened around the circumference of the gas distribution ring can make nitrogen spray into the pipeline radially. The flow controller dynamically adjusts the nitrogen flow rate according to the real-time detection data of the oxygen sensor in the pipeline to ensure that the oxygen content in the pipeline ≤ 0.5%, creating a low-oxygen environment to prevent adverse reactions such as oxidation of small particles during transportation. In addition, the end of the connecting pipeline is provided with a conical flaring section with a flaring angle of 30° - 45°, and the spiral guide vanes welded on its inner wall can reduce the particle flow rate and disperse its movement trajectory, making the state of small particles more stable before entering the cyclone separator, which helps to improve the collection efficiency and effect of the cyclone separator on small particles.

[0029] In summary, the present application includes at least one of the following beneficial technical effects:

[0030] 1. The present application uses a pumping device to conduct high-pressure transportation of zirconia slurry with high solid content, and cooperates with high-speed air flow impact and shear to quickly atomize the slurry into small droplets. The high solid content reduces the subsequent drying energy consumption, and the momentum exchange between the high-speed air flow and the high-pressure slurry realizes efficient atomization, providing a basis for high-quality granulation and improving production efficiency;

[0031] 2. The present application divides the main tower into an inlet section and an outlet section, and realizes gradient drying and solidification of droplets by a low-temperature heater and a high-temperature heater respectively. At the same time, the strong air flow fan at the bottom and the weak air flow regulator in the middle cooperate to achieve preliminary classification according to the difference in the movement characteristics of particles with different particle sizes in the air flow, ensuring the uniformity of product quality and improving the collection purity of particles;

[0032] 3. Based on the movement characteristics of particles with different particle sizes in the air flow, this application collects large particles from the bottom discharge port of the main tower through the action of gravity, downward air flow and lateral air flow, and transports small particles to the cyclone separator through the Xuanfeng port for collection using centrifugal force, realizing precise classification collection and improving the collection efficiency. Description of the Drawings

[0033] Figure 1 is a flowchart of a spray granulation process;

[0034] Figure 2 is a schematic diagram of the overall structure of a spray granulation device;

[0035] Figure 3 is Figure 2 the enlarged view at A in

[0036] Figure 4 is a schematic diagram of the connection structure of the tangential inlet pipe between the main towers;

[0037] Figure 5 is a sectional view of the connection between the gas distribution ring and the main pipe.

[0038] Description of the reference numerals: 1. Storage tank; 2. Pumping device; 21. Pipe; 3. Nozzle; 4. High-speed air flow generator; 5. Main tower; 51. Inlet section; 52. Outlet section; 56. Tangential inlet pipe; 561. Air flow pipe; 562. Heater; 563. Air inlet pump; 564. Adjustable guide pipe; 565. Micro motion cylinder; 566. Elastic heat insulation layer; 567. Elastic threaded air guide pipe; 57. Ring support; 571. Ultrasonic vibration plate; 572. Piezoelectric ceramic sheet; 6. Temperature control system; 61. Low-temperature heater; 62. High-temperature heater; 7. Air flow system; 71. Strong air flow fan; 72. Weak air flow regulator; 8. Discharge port; 9. Xuanfeng port; 91. Connection pipe; 92. Conical flared section; 921. Spiral guide vane; 10. Cyclone separator; 11. Ion wind rod; 111. Discharge needle; 12. Nitrogen injection system; 121. Nitrogen storage tank; 122. Gas distribution ring; 1221. Micro hole; 123. Flow controller; 124. Main pipe; 13. Controller. Detailed Description of the Embodiment

[0039] The following will Figures 1-5 further elaborate on this application in detail.

[0040] The embodiment of this application discloses a spray granulation process and its device.

[0041] Referring to Figure 1 , a spray granulation process includes the following steps:

[0042] Step 1: Preparation and transportation of the slurry: Prepare a zirconia slurry with a solid content of 90%, and transport it to the nozzle 3 through the pipeline 21 of the pumping device 2. The slurry meets the airflow generated by the high-speed airflow generator 4 at the nozzle 3 and is atomized into tiny droplets;

[0043] Step 2: Drying and classification. The atomized droplets are in contact with the hot airflow for drying. The temperature of the airflow is controlled by the temperature control system 6, and the temperature gradually rises from the inlet section 51 to the outlet section 52 of the main tower 5. The temperature control system 6 ensures the stability of the temperature inside the tower to avoid uneven particle distribution caused by temperature changes. The airflow system 7 adjusts the airflow velocity and direction; Particles with a particle size ≥ 40μm fall to the discharge port 8 at the bottom of the main tower 5 under the action of strong airflow, and particles with a particle size < 40μm flow to the swirl air outlet 9 under the action of weaker airflow, realizing particle classification;

[0044] Step 3: Particle collection stage. The dried particles are collected through the airflow system 7. Among them, the large particles are exported from the discharge port 8 at the bottom of the main tower 5 through the strong airflow regulator for collection, and the small particles are collected through the connecting pipeline 91 to the cyclone separator 10 via the swirl air outlet 9;

[0045] Step 4: Product collection and post-treatment. The large particles directly enter storage or subsequent processing, and the small particles are further processed or packaged separately for different application requirements.

[0046] During the zirconia spray granulation process, this process effectively solves the agglomeration problem through the synergistic effect of multiple stages. When the slurry is atomized, for the zirconia slurry with a high solid content acting on the airflow generated by the high-speed airflow generator 4, the particles are evenly distributed in the tiny droplets, reducing the chance of agglomeration; In the drying and classification stage, the temperature control system 6 precisely controls the temperature to gradually rise from the inlet section 51 to the outlet section 52 of the main tower 5, ensuring uniform drying of the droplets and avoiding rapid drying that may cause rapid surface crusting, where the internal solvent cannot escape, forming hollow particles or causing agglomeration after rupture. At the same time, the airflow system 7 adjusts the airflow velocity and direction, making it difficult for particles to aggregate in the dynamic airflow; In the particle collection stage, strong and weak airflows respectively guide particles of different particle sizes, avoiding static accumulation of particles and collision and adhesion between large and small particles; In the product collection and post-treatment stage, the particles are processed separately according to their uses, especially surface modification of small particles to optimize the surface properties and reduce the agglomeration tendency.

[0047] Refer to Figures 2 to 5, A spray granulation device, comprising the following components: a slurry atomization unit, which includes a storage tank 1, a pumping device 2, and a nozzle 3; the storage tank 1 is used to hold zirconia slurry with a solid content of 90%; the pumping device 2 is connected to the storage tank 1 through a pipeline 21 and conveys the slurry to the nozzle 3 at a pressure of 20 MPa; a high-speed gas flow generator 4 with a gas flow rate of 80 m / s is connected to the gas inlet of the nozzle 3, which is used to atomize the slurry into liquid droplets with a particle size of 10 - 100 μm; a gradient temperature-controlled drying and classification unit, including a main tower 5, a temperature control system 6, and an air flow system 7. The top of the main tower 5 is provided with the nozzle 3, and the main tower 5 is divided into an inlet section 51 and an outlet section 52; the temperature control system 6 includes a low-temperature heater 61 arranged in the inlet section 51 and a high-temperature heater 62 arranged in the outlet section 52, which respectively control the temperature of the inlet section 51 to be 400 °C and the temperature of the outlet section 52 to be 800 °C; the air flow system 7 includes a strong air flow fan 71 at the bottom of the main tower 5 and a weak air flow regulator 72 in the middle of the main tower 5. The strong air flow fan 71 generates a downward air flow with a flow rate of 8 m / s, and the weak air flow regulator 72 generates a lateral air flow with a flow rate of 3 m / s; a particle classification and collection unit: including a discharge port 8 at the bottom of the main tower 5, a swirler port 9, and a cyclone separator 10. The discharge port 8 at the bottom of the main tower 5 is used to collect particles with a particle size ≥ 40 μm. The swirler port 9 is connected to the weak air flow regulator 72 and conveys particles with a particle size < 40 μm to the cyclone separator 10 for collection. The zirconia slurry with a solid content of 90% in the storage tank 1 is conveyed through the pipeline 21 to the nozzle 3 connected to the high-speed gas flow generator 4 with a gas flow rate of 80 m / s at a pressure of 20 MPa by the pumping device 2, and is atomized into tiny liquid droplets of 10 - 100 μm under the impact and shear of the high-speed gas flow, laying a foundation for subsequent drying and granulation; the atomized liquid droplets enter from the nozzle 3 at the top of the main tower 5. The main tower 5 is divided into an inlet section 51 and an outlet section 52. The low-temperature heater 61 in the inlet section 51 controls the temperature to 400 °C to enable the liquid droplets to initially evaporate moisture and partially solidify. The high-temperature heater 62 in the outlet section 52 raises the temperature to 800 °C to promote its further drying and solidification into particles. The strong air flow fan 71 at the bottom of the main tower 5 generates a downward air flow of 8 m / s to accelerate the falling and drying of the particles. The weak air flow regulator 72 in the middle generates a lateral air flow of 3 m / s to make the particles evenly distributed and generate different acting forces according to the particle size, realizing preliminary classification; after gradient temperature-controlled drying and preliminary classification, larger particles with a particle size ≥ 40 μm are collected from the discharge port 8 at the bottom of the main tower 5 under the action of gravity and downward strong air flow. Smaller particles with a particle size < 40 μm are affected by the lateral weak air flow and are conveyed to the cyclone separator 10 through the swirler port 9, and the collection of small particles is completed by using centrifugal force, realizing accurate classification and collection according to particle size based on the difference in the movement characteristics of particles with different particle sizes in the air flow.

[0048] Refer to Figures 2 to 5, several groups of tangential air inlet pipes 56 evenly distributed circumferentially along the side wall of the main tower 5 are adopted on the middle side wall of the main tower 5. The angle between the axis of the tangential air inlet pipe 56 and the tangent direction of the inner wall of the spray tower is 30°. And each tangential air inlet pipe 56 is connected to an external compressed air source through an independent air flow pipeline 561; the gas output by the compressed air source is preheated to 120 °C by a heater 562 and then sprayed into the main tower 5 from the tangential air inlet pipe 56 at a flow rate of 12 m / s under the action of an air inlet pump 563 to form a swirling flow field surrounding the atomized droplets. An adjustable guide pipe 564 is also provided at the outlet of the tangential air inlet pipe 56. The adjustable guide pipe 564 is rotatably connected to the wall of the main tower 5 and is driven by a micro motion cylinder 565 to adjust within a range of 30° - 60°. The micro motion cylinder 565 is located on both sides of the adjustable guide plate and is respectively located on both sides of the adjustable guide plate and the rotating shaft of the wall of the main tower 5. Among them, the adjustable guide plate is hermetically connected to the wall of the main tower 5 through an elastic heat insulation layer 566, and the outer end of the adjustable guide plate is communicated with the tangential air inlet pipe 56 through an elastic threaded air duct 567. In the spray granulation equipment, several groups of tangential air inlet pipes 56 evenly distributed circumferentially are arranged on the middle side wall of the main tower 5. The angle between the axis of the tangential air inlet pipe 56 and the tangent direction of the inner wall of the spray tower is 30°. Each tangential air inlet pipe 56 is connected to an external compressed air source through an independent air flow pipeline 561. The gas output by the compressed air source is first preheated to 120 °C by a heater 562 and then sprayed into the main tower 5 from the tangential air inlet pipe 56 at a flow rate of 12 m / s under the action of an air inlet pump 563, thereby forming a swirling flow field surrounding the atomized droplets. An adjustable guide pipe 564 is provided at the outlet of the tangential air inlet pipe 56. The adjustable guide plate is rotatably connected to the wall of the main tower 5 and is driven by the micro motion cylinder 565 located on both sides of it and respectively on both sides of the rotating shaft of the wall of the main tower 5 to adjust within a range of 30° - 60°. And the adjustable guide plate is hermetically connected to the wall of the main tower 5 through an elastic heat insulation layer 566, and the outer end is communicated with the tangential air inlet pipe 56 through an elastic threaded air duct 567, so as to flexibly adjust the direction and angle of the air flow sprayed out by the tangential air inlet pipe 56 and further optimize the action effect of the swirling flow field on the atomized droplets and particles.

[0049] Refer to Figures 2 to 5, an annular bracket 57 is fixedly installed at the inner top of the main tower 5. A number of groups of ultrasonic vibration plates 571 are symmetrically arranged on the annular bracket 57. Each group of ultrasonic vibration plates 571 includes a number of piezoelectric ceramic sheets 572 arranged in the vertical direction, and is connected to the start-stop signal of the atomizing nozzle 3 through the controller 13. When the atomizing nozzle 3 starts the slurry atomization operation, the controller 13 receives the start signal, and then triggers the ultrasonic vibration plate 571 to work. After receiving the electrical signal, the piezoelectric ceramic sheet 572 generates vibration and then emits ultrasonic waves. The ultrasonic waves propagate in the space at the inner top of the main tower 5 and act on the slurry droplets just ejected from the atomizing nozzle 3. The energy of the ultrasonic waves can further refine the droplets, prevent the droplets from agglomerating at the initial stage, help to form smaller droplets with more uniform particle sizes, thereby optimizing the formation quality of the droplets in the early stage of the entire spray granulation process and laying a better foundation for subsequent drying, classification, collection and post-treatment processes; when the atomizing nozzle 3 stops working, the controller 13 receives the stop signal, and the ultrasonic vibration plate 571 also stops working.

[0050] Refer to Figures 2 to 5, an ion wind rod 11 and a nitrogen injection system 12 are successively arranged in the connecting pipe 91 between the tuyere 9 of the cyclone and the cyclone separator 10. The nitrogen injection system 12 includes a nitrogen storage tank 121, a gas distribution ring 122 and a flow controller 123. The nitrogen storage tank 121 is connected to the gas distribution ring 122 through a main pipe 124. The gas distribution ring 122 is embedded in the inner wall of the pipe 21, and a number of micropores 1221 are evenly arranged in the circumferential direction. Nitrogen is sprayed into the pipe 21 radially through the micropores 1221. The flow controller 123 adjusts the nitrogen flow rate according to the real-time detection data of the oxygen sensor in the pipe 21 to make the oxygen content ≤ 0.5%. The ion wind rod 11 is used to neutralize the static charge on the surface of the particles and is arranged at equal intervals along the axial direction of the pipe 21, and each group thereof includes discharge needles 111 arranged with positive and negative electrodes alternating. The end of the connecting pipe 91 is provided with a tapered flaring section 92, the flaring angle of the flaring section is 30°, and a spiral deflector 921 for reducing the particle flow rate and dispersing the movement track is welded on the inner wall. In the connecting pipe 91 between the tuyere 9 of the cyclone and the cyclone separator 10, the ion wind rod 11 and the nitrogen injection system 12 are successively arranged. The ion wind rod 11 can generate ion wind to neutralize the surface charge of small particles during transportation and reduce the agglomeration caused by electrostatic interaction between particles. The nitrogen injection system 12 is composed of a nitrogen storage tank 121, a gas distribution ring 122 and a flow controller 123. The nitrogen storage tank 121 is connected to the gas distribution ring 122 embedded in the inner wall of the pipe 21 through a main pipe 124. The micropores 1221 evenly arranged in the circumferential direction of the gas distribution ring 122 can make nitrogen spray into the pipe 21 radially. The flow controller 123 dynamically adjusts the nitrogen flow rate according to the real-time detection data of the oxygen sensor in the pipe 21 to ensure that the oxygen content in the pipe 21 ≤ 0.5%, creating a low-oxygen environment to prevent adverse reactions such as oxidation of small particles during transportation. In addition, the end of the connecting pipe 91 is provided with a tapered flaring section 92 with a flaring angle of 45°, and the spiral deflector 921 welded on its inner wall can reduce the particle flow rate and disperse its movement track, making the state of small particles more stable before entering the cyclone separator 10, which helps to improve the collection efficiency and effect of the cyclone separator 10 on small particles.

[0051] The above are all the preferred embodiments of this application, and the protection scope of this application is not limited thereby. Therefore, all equivalent changes made according to the structure, shape and principle of this application should be covered within the protection scope of this application.

Claims

1. A spray granulation process, characterized in that: It includes the following steps: Step 1: Preparation and transportation of slurry: Prepare a zirconia slurry with a solid content of 90%, and transport it to the nozzle (3) through the pipeline (21) of the pumping device (2). The slurry meets the airflow generated by the high-speed airflow generator (4) at the nozzle (3) and is atomized into tiny droplets. Step 2: Drying and classification: The atomized droplets are in contact with the hot airflow for drying. The temperature of the airflow is controlled by the temperature control system (6), and the temperature gradually rises from the inlet section (51) to the outlet section (52) of the main tower (5). The temperature control system (6) ensures the stability of the temperature inside the tower to avoid uneven particle distribution caused by temperature changes. The airflow system (7) adjusts the airflow velocity and direction. Particles with a particle size ≥ 40μm fall to the bottom discharge port (8) of the main tower (5) under the action of strong airflow, and particles with a particle size < 40μm flow towards the vortex air port (9) under the action of weaker airflow to achieve particle classification. Step 3: Particle collection stage: The dried particles are collected through the airflow system (7). Among them, the large particles are exported from the discharge port (8) at the bottom of the main tower (5) through the strong airflow regulator for collection, and the small particles are collected through the connecting pipeline (91) to the cyclone separator (10) via the vortex air port (9). Step 4: Product collection and post-treatment: The large particles directly enter storage or subsequent processing, and the small particles are further processed or packaged separately for different application requirements.

2. A spray granulation device for implementing the spray granulation process according to claim 1, characterized in that: It includes the following components: Slurry atomization unit: The slurry atomization unit includes a storage tank (1), a pumping device (2) and a nozzle (3). The storage tank (1) is used to hold a zirconia slurry with a solid content of 90%. The pumping device (2) is connected to the storage tank (1) through a pipeline (21) and transports the slurry to the nozzle (3) at a pressure of 10 - 20 MPa. The gas inlet of the nozzle (3) is connected to a high-speed airflow generator (4) with a flow rate of 50 - 80 m / s, which is used to atomize the slurry into droplets with a particle size of 10 - 100μm. Gradient temperature-controlled drying and classification unit, including a main tower (5), a temperature control system (6) and an air flow system (7). The top of the main tower (5) is provided with a nozzle (3). The main tower (5) is divided into an inlet section (51) and an outlet section (52). The temperature control system (6) includes a low-temperature heater (61) arranged in the inlet section (51) and a high-temperature heater (62) arranged in the outlet section (52), controlling the temperature of the inlet section (51) to be 200 - 400 °C and the temperature of the outlet section (52) to be 600 - 800 °C respectively. The air flow system (7) includes a strong air flow fan (71) at the bottom of the main tower (5) and a weak air flow regulator (72) in the middle of the main tower (5). The strong air flow fan (71) generates a downward air flow with a flow rate of 5 - 8 m / s, and the weak air flow regulator (72) generates a lateral air flow with a flow rate of 1 - 3 m / s. Particle classification and collection unit: including a discharge port (8) at the bottom of the main tower (5), a swirler port (9) and a cyclone separator (10). The discharge port (8) at the bottom of the main tower (5) is used to collect particles with a particle size ≥ 40 μm. The swirler port (9) is connected to the weak air flow regulator (72) and transports particles with a particle size < 40 μm to the cyclone separator (10) for collection.

3. The spray granulation device according to claim 2, wherein: On the middle side wall of the main tower (5), several groups of tangential inlet pipes (56) are evenly distributed circumferentially along the side wall of the main tower (5). The angle between the axis of the tangential inlet pipe (56) and the tangent direction of the inner wall of the spray tower is 15° - 30°. And each tangential inlet pipe (56) is connected to an external compressed air source through an independent air flow pipeline (561). The gas output by the compressed air source is preheated to 80 - 120 °C by a heater (562) and then sprayed into the main tower (5) from the tangential inlet pipe (56) at a flow rate of 8 - 12 m / s under the action of an air inlet pump (563) to form a swirling flow field around the atomized droplets.

4. The spray granulation device according to claim 3, characterized in that: An adjustable guide pipe (564) is also provided at the outlet of the tangential inlet pipe (56). The adjustable guide pipe (564) is rotatably connected to the main tower (5) wall and is driven by a micro-motion air cylinder (565) to adjust within a range of 30° - 60°.

5. The spray granulation device according to claim 4, wherein: The micro-motion air cylinder (565) is located on both sides of the adjustable guide plate, and is respectively located on both sides of the adjustable guide plate and the rotating shaft of the main tower (5) wall. Among them, the adjustable guide plate is hermetically connected to the main tower (5) wall through an elastic heat insulation layer (566), and the outer end of the adjustable guide plate is connected to the tangential inlet pipe (56) through an elastic threaded air duct (567).

6. The spray granulation device according to claim 2, characterized in that: An annular bracket (57) is fixedly installed at the inner top of the main tower (5). Several groups of ultrasonic vibrating plates (571) are symmetrically arranged on the annular bracket (57). Each group of ultrasonic vibrating plates (571) includes several piezoelectric ceramic sheets (572) arranged in the vertical direction and is connected to the start-stop signal of the atomizing nozzle (3) through a controller (13).

7. The spray granulation device according to claim 2, wherein: An ion wind rod (11) and a nitrogen injection system (12) are sequentially arranged in the connecting pipeline (91) between the swirler port (9) and the cyclone separator (10).

8. The spray granulation device according to claim 7, wherein: The ion wind rod (11) is used to neutralize the static charge on the surface of particles and is arranged at equal intervals along the axial direction of the pipeline (21), and each group includes discharge needles (111) with positive and negative electrodes arranged alternately.

9. The spray granulation device according to claim 8, characterized in that: The nitrogen injection system (12) includes a nitrogen storage tank (121), a gas distribution ring (122) and a flow controller (123). The nitrogen storage tank (121) is connected to the gas distribution ring (122) through a main pipeline (124). The gas distribution ring (122) is embedded in the inner wall of the pipeline (21), and a number of micropores (1221) are evenly arranged around the circumference. Nitrogen is sprayed into the pipeline (21) radially through the micropores (1221). The flow controller (123) adjusts the nitrogen flow rate according to the real-time detection data of the oxygen sensor in the pipeline (21) so that the oxygen content ≤ 0.5%.

10. A spray granulation device according to claim 9, characterized in that: The end of the connecting pipeline (91) is provided with a conical flaring section (92). The expansion angle of the flaring section is 30° - 45°, and a spiral guide vane (921) for reducing the particle flow rate and dispersing the movement track is welded on the inner wall.

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