Spray granulation drying device and process for calcium chloride

Abstract

The invention relates to the technical field of spray granulation devices, and mainly discloses a spray granulation drying device and process for calcium chloride, the device adopts a vertical single air chamber structure and comprises a drying section, a granulation section with the taper of 44-45 degrees and a settling section with a constant cross section which are arranged from bottom to top, and an air distribution plate is provided with an opening ratio of 13-16% and a taper of 2-5 degrees. Two-fluid atomization is adopted by a spray gun, the atomization pressure is 4 + / -0.5 kg / cm higher than that of a solution pump, the spraying direction is vertically upward, and the technology comprises the steps that a seed crystal material layer of 0.4-0.6 mm is put in, hot air at the temperature of 400-450 DEG C is introduced to control the fluidization speed to be 2.6-3.1 m / s, and spraying coating is conducted in the state that the void ratio is kept to be 0.5-0.6. And the temperature of the tail gas is reduced to 150-170 DEG C, the dust content is reduced, and the technical problems that traditional equipment is serious in wall bonding, uneven in particle size and high in energy consumption are effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of spray granulation devices, and specifically to a spray granulation drying device and process for calcium chloride. Background Art

[0002] A spray granulation drying equipment is a device that forms liquid materials into droplets by spraying and then dries them with hot air to form granular products. The spray granulation drying equipment is divided into continuous type and batch type according to the operation mode. In the continuous spray granulation drying equipment, materials continuously enter and continuously discharge, which is suitable for large-scale and continuous production. In batch spray granulation drying, materials are added batch by batch, and the next batch is processed after each batch of materials is processed.

[0003] The spray granulation drying equipment is a key equipment for industrial production of granular materials. Existing continuous granulation drying equipment mostly adopts a rectangular horizontal multi-air chamber layout, and adjusts the hot air flow state through multiple independent air chambers to achieve continuous production. Although this technology is widely used, there are still the following significant defects in actual operation: 1. The adjustment of multiple air chambers is complex and the operation stability is poor. The existing device needs to accurately adjust the opening degree of the air chamber dampers of each air chamber to maintain the fluidization state, which highly depends on the experience of the operators. Improper adjustment is likely to cause local dead beds or uneven fluidization, and the dead bed shutdown rate is high during the startup stage, seriously restricting the continuous production efficiency and equipment reliability.

[0004] 2. There are design defects in the perforation rate of the air distribution plate, and it is difficult to control the discharge. To adapt to the long-span characteristics of the horizontal structure, the air distribution plate usually adopts a combined design of inclined holes and straight holes. However, since it is difficult for the perforation rate to dynamically match the change of the material layer, it is easy to cause the discharge speed to get out of control and the material layer to pile up too high, ultimately leading to the interruption of fluidization and dead beds.

[0005] 3. The particle size of the discharged materials is uneven, and the ineffective energy consumption is prominent. The unilateral layout of the discharge port results in a wide range of particle distribution. It is necessary to screen and crush the large particles and then return them for re-granulation. This process increases the ineffective energy consumption, and the surface of the particles after crushing is rough, and repeated drying leads to a decrease in the true density.

[0006] 4. Particles are repeatedly coated, and oversized particles are formed. When the spray guns are evenly arranged on both sides of the fluidized bed with a large span, the particles at the far end will be coated with atomized droplets again during the flow to the discharge end, resulting in the particle size exceeding the target range, further increasing the amount of returned materials and energy consumption.

[0007] 5. The structural defects of the air distribution plate lead to low energy efficiency. The inclined hole design interferes with the void ratio of the fluidized bed, making the dynamic pressure of the atomized droplets of the spray gun exceed the critical value. Some droplets penetrate the material layer and adhere to the side wall to form lumps. After the lumps fall off, the fluidization stability is damaged, and at the same time, the fine powder that has not participated in granulation escapes with the tail gas, resulting in effective heat energy loss.

[0008] Due to the limitations of the structural design in the prior art, there are core problems such as complex operation, high energy consumption, uneven particle size, and poor equipment stability. There is an urgent need for a new granulation and drying device to achieve efficient, stable, and low-energy continuous production. Some continuous granulation and drying equipment in the prior art adopts a single air chamber vertical layout, which can appropriately solve the above technical problems. However, the existing vertical single air chamber spray granulation equipment still has the following technical problems when used for the spray granulation of calcium chloride: 1. Most of the spray guns in the existing equipment are arranged vertically downward or disorderly. The dynamic pressure of the atomized liquid droplets is too high. After penetrating the material layer, they adhere to the side wall of the equipment, resulting in particle agglomeration. The liquid droplets sprayed vertically downward are easily carried away by the hot air to form dust, causing ineffective drying. The spray distribution of the spray gun does not match the porosity of the fluidized material layer, and the liquid droplets cannot uniformly coat the surface of the particles, resulting in uneven particle size.

[0009] 2. The cross-sectional area of the granulation section of the existing single air chamber granulation equipment remains unchanged, and a reasonable wind speed gradient distribution is not formed. The formed particles repeatedly rise and fall in the granulation section due to the unreasonable wind speed gradient, resulting in uneven particle size and excessive surface drying and cracking. At the same time, the dust cannot be effectively settled, the dust content in the tail gas is high, and the heat energy is wasted seriously.

[0010] The existing single air chamber vertical equipment also has problems such as high agglomeration rate, poor dust control, energy consumption waste, and uneven particle size due to the unreasonable layout of the spray gun and the unreasonable configuration of the structural parameters of the granulation section, making it difficult to meet the continuous and efficient production requirements of materials such as calcium chloride. Summary of the Invention

[0011] The purpose of the present invention is to solve the technical problems existing in the prior art and provide a spray granulation and drying device and process for calcium chloride.

[0012] To achieve the above object, the present invention adopts the following technical solutions: A spray granulation drying device for calcium chloride, comprising an air chamber, a drying section, a granulation section, and a sedimentation section. The sedimentation section, granulation section, and drying section are arranged in sequence from top to bottom. The air chamber is arranged at the bottom of the drying section. An air inlet for introducing hot air is arranged on one side of the air chamber. A air distribution plate is arranged between the air chamber and the drying section. The air distribution plate is evenly provided with openings for uniformly introducing hot air into the drying section. A discharge pipe is arranged at the bottom of the drying section. The upper opening of the discharge pipe is communicated with the internal cavity of the drying section, and the bottom of the discharge pipe extends outside the air chamber. A plurality of uniformly distributed spray guns with a vertically upward spray direction are arranged in the drying section. An air outlet is arranged on one side of the top of the sedimentation section. The sedimentation section is located at the uppermost part of the fluidized bed. The cross-sectional area of the drying section is constant. The cross-sectional area of the granulation section gradually increases from bottom to top. The cross-sectional area of the sedimentation section is constant. The fluidization velocity of the granulation section is 2.6 m / s to 3.1 m / s, and the taper of the granulation section is 44 - 45°. The reasonable taper ensures that it is greater than the bulk density of calcium chloride so that calcium chloride does not accumulate material here. The thickness of the static material layer in the granulation section is 0.4 m to 0.6 m, the porosity of the material layer in the fluidized state is 0.5 to 0.6, the opening ratio of the air distribution plate is 13% to 16%, and the spray gun uses two-fluid atomization, and the atomization compressed air pressure is greater than the outlet pressure of the centrifugal pump by about 4 kg ± 0.5 / cm².

[0013] The spray gun includes a spray pipe and a nozzle. The spray pipe passes through the pipe wall of the drying section. A nozzle is arranged at the end of the spray pipe inside the drying section, and a compressed air inlet and a raw material liquid inlet are arranged at the end of the spray pipe outside the drying section.

[0014] When the output increases, the diameter of the air distribution plate becomes larger. To ensure the smooth discharge of dried particles around, two measures are taken: A further solution of the present invention lies in that: the air distribution plate is inclined downward along the circumference of the drying section towards the discharge port. Preferably, the inclination angle is 2 - 5°. The air distribution plate is designed with a certain taper to make it easier for the finished particles around to reach the discharge port and ensure smooth discharge.

[0015] As an alternative to the above solution: to adapt to a larger output, a plurality of discharge pipes are provided, and the plurality of discharge pipes are evenly distributed on the air distribution plate. The finished particles flow out in multiple segments and multiple paths.

[0016] A further solution of the present invention lies in that: waterproof asbestos gaskets are respectively arranged on the upper and lower sides of the air distribution plate.

[0017] A further solution of the present invention lies in that: a liquid package and a steam package are arranged at the drying section, similar to a pressure equalizing box, and the raw material liquid and compressed air are evenly distributed after passing through this device.

[0018] A further solution of the present invention is that: a plurality of observation ports are evenly distributed on the tube wall of the drying section. Preferably, there are 4 observation ports.

[0019] A further solution of the present invention is that: a sewage discharge port is provided at the bottom of the air chamber to discharge waste water after flushing the fluidized bed.

[0020] A further solution of the present invention is that: pressure measuring ports are provided on the drying section and the settling section for installing pressure sensors to measure the pressure at each part.

[0021] A further solution of the present invention is that: temperature measuring ports are provided at the air inlet, air outlet and drying section for installing temperature sensors to measure the temperature at each part.

[0022] A spray granulation drying process for calcium chloride includes the following steps: S1. Using the above spray granulation drying equipment, put seed particles of 1-2 mm into the drying section above the air distribution plate. After laying, the static bed height is 0.4-0.6 mm. S2. Pass hot air with a temperature of 400-450 °C into the air chamber. The hot air inlet wind speed is 15-20 m / s. The hot air blows the seed particles through the air distribution plate to be in a fluidized state. Control the fluidization speed to be 2.6-3.1 m / s to form a stable bed layer. The porosity of the stable bed layer in the fluidized state is 0.5-0.6. S3. Use a spray gun to spray the calcium chloride solution upward from bottom to top. The atomizing compressed air pressure is 4 kg ± 0.5 / cm² higher than the solution pump pressure. S4. As the particles continue to grow by coating, they settle to the lower drying section under the action of gravity. The finished product particles after drying are discharged from the feeding port. S5. Only a small amount of dust generated by the violent flow and friction of some particles in the settling section adheres here through collision. Some of them become larger and then settle to the granulation section for re-granulation. A small amount of dust is taken away by the tail gas and enters the subsequent dust removal process.

[0023] Compared with the prior art, the beneficial effects of the present invention are: (1) This device adopts a single air chamber design. An air distribution plate is arranged at the lower part. The hot air blows the seeds through the air distribution plate to be in a fluidized state, forming a stable material layer. The overall drying section of the device is conical, with a certain straight section set at the lower end as the drying section. The cross-section above the drying section continuously increases, and the wind speed decreases. As the particles are continuously coated and grow, they sink to the lower drying section under the action of gravity. The finished product particles after drying are discharged from the feeding port. The conical cylinder is used to make the wind speed of each section decrease uniformly from bottom to top. Therefore, the particle distribution in the fluidized state is from large to small from the drying section to the granulation section. The feeding port of this device is arranged at the bottom of the fluidized bed and connected to the air distribution plate. There is no air blowing at the feeding position. Therefore, the finished products in the fluidized state after drying around flow down from the feeding port under the action of gravity. This design makes the particle size of the finished product particles more uniform and reduces the content of small particles and powder.

[0024] (2) The spray gun adopts two-fluid atomization. The small droplets after compressed air atomization are distributed between particles, continuously coated and adhered, and slowly become larger and sink to the bottom. At the same time, the intense friction makes the particle surface smooth. Because the nozzle uses compressed air atomization, a good atomization effect can be achieved under low-pressure conditions. At the same time, the dynamic pressure of the ejected droplets decreases, and it is not easy to penetrate the material layer to generate fine powder. The dust in the tail gas is relatively low, and the wall sticking situation is reduced at the same time. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is the front view of the spray granulation drying device of the present invention; Figure 2 It is the side view of the spray granulation drying device of the present invention; Figure 3 It is the schematic diagram of the spray gun structure of the spray granulation drying device of the present invention; Figure 4 It is the schematic diagram of the air distribution plate structure of the spray granulation drying device of the present invention; Figure 5 It is the schematic diagram of the inclination angle of the air distribution plate of the spray granulation drying device of the present invention.

[0027] In the figure: 1. Air chamber; 2. Drying section; 3. Granulation section; 4. Settling section; 5. Air inlet; 6. Feeding pipe; 7. Air distribution plate; 8. Spray gun; 9. Air outlet; 10. Waterproof asbestos gasket; 11. Liquid package; 12. Steam drum; 13. Observation port; 14. Drain port; 15. Temperature measuring port; 16. Pressure measuring port; 17. Compressed air inlet; 18. Raw liquid inlet. Detailed implementation mode

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0029] As Figures 1-5 shown, a spray granulation drying device for calcium chloride includes an air chamber 1, a drying section 2, a granulation section 3, and a sedimentation section 4. The sedimentation section 4, granulation section 3, and drying section 2 are arranged in sequence from top to bottom.

[0030] The air chamber 1 is arranged at the bottom of the drying section 2. An air inlet 5 for introducing hot air is arranged on one side of the air chamber 1. A air distribution plate 7 is arranged between the air chamber 1 and the drying section 2. The air distribution plate 7 is evenly provided with openings for uniformly introducing hot air into the drying section 2. A feeding pipe 6 is arranged at the bottom of the drying section 2. The upper opening of the feeding pipe 6 is communicated with the internal cavity of the drying section 2, and the bottom of the feeding pipe 6 extends outside the air chamber 1. In this device, the feeding pipe 6 is arranged at the bottom of the fluidized bed and connected to the air distribution plate 7, and there is no air blowing at the feeding position. Therefore, the finished products in a fluidized state after drying all around flow down from the feeding pipe 6 under the action of gravity. The fluidization speed of the drying section 2 is relatively high, and the hot air blows the small particles and dust to the upper granulation section 3, reducing the particle size distribution range during the drying process and making the discharge particle size more uniform; the return material amount is lower, reducing the ineffective energy consumption.

[0031] An air outlet 9 is arranged on one side of the top of the sedimentation section 4, and the sedimentation section 4 is located at the top of the fluidized bed.

[0032] The sedimentation section 4 is located at the top of the fluidized bed, where the interface is the largest, the wind speed is the slowest, and the water content of the tail gas is the highest. Since the spray gun 8 cannot penetrate the fluidized material layer, only a small amount of dust generated by the intense flow and friction of some particles collides and adheres here. Part of it becomes larger and settles to the granulation section 3 for re-granulation, and a small part of the dust is taken away by the tail gas and enters the subsequent dust removal process.

[0033] The present invention adopts a single air chamber design. The hot air enters the air chamber for buffering and then enters the drying section 2 of the drying tower through the air distribution plate 7 at the bottom of the bed. The design of the single air chamber 1 enables the entire device not to need to adjust the air pressure at each position of the air distribution plate 7, making it easier to lay the material layer during the start-up stage of the device; at the same time, during the operation process, the adjustment of the air damper is reduced, which is simpler and more efficient. The inlet air speed is 15 - 20 m / s to control the pipeline resistance.

[0034] A plurality of spray guns 8 which are evenly distributed and have a vertical upward spray direction are arranged in the drying section 2. The spray gun 8 includes a spray pipe and a nozzle. The spray pipe passes through the pipe wall of the drying section 2. A nozzle is arranged at the end of the spray pipe inside the drying section 2, and a compressed air inlet 17 and a raw material liquid inlet 18 are arranged at the end of the spray pipe outside the drying section 2.

[0035] The spray gun 8 uses two-fluid atomization, and the atomization compressed air pressure is about 4 kg ± 0.5 / cm² greater than the outlet pressure of the centrifugal pump. The design and arrangement of the spray gun 8 use two-fluid atomization. The liquid material uses a common centrifugal pump with a head of 30 m, and the atomization compressed air pressure is about 4 kg / cm 2 , under the condition of ensuring the atomization effect, the kinetic energy of the atomized liquid material is relatively low and always remains inside the material layer with a void fraction of 0.5 - 0.6. It continuously undergoes coating drying among the flowing particles and cannot penetrate the material layer, reducing the situation of wall sticking and dusting.

[0036] The finer atomization particle size makes the granulation mechanism tend to coating. Compared with the agglomeration granulation of traditional pressure atomization, the particle surface is smoother, and the true density and bulk density of the particles are higher. The spray guns 8 are evenly arranged around the device and spray upward. During the process of the particles descending, they are continuously coated and dried, and there will be no repeated drying process in a square fluidized bed, resulting in higher drying efficiency.

[0037] The cross-sectional area of the drying section 2 is constant, the cross-sectional area of the granulation section 3 gradually increases from bottom to top, and the cross-sectional area of the sedimentation section 4 is constant. The cross-sectional area of the granulation section 3 above the air distribution plate 7 increases successively, and the interfacial wind speed decreases successively. As the fluidization progresses, the large particles sprayed in the granulation section 3 settle naturally to the bottom drying section 2 of the device and are discharged through the blanking pipe 6 after drying in the drying section 2. This design makes the particle size of the finished product more uniform and reduces the content of small particles and powder.

[0038] The fluidization velocity of the granulation section 3 is 2.6 m / s - 3.1 m / s, the cross-sectional area increment rate of the granulation section 3 is 10% - 15%; the thickness of the static material layer of the granulation section 3 is 0.4 mm - 0.6 mm, the void fraction of the material layer in the fluidized state is 0.5 - 0.6, and the opening ratio of the air distribution plate 7 is 13% - 16%.

[0039] The key difference between the present invention and the existing single air chamber 1 granulation device lies in the cancellation of the built-in heater. Through the coordinated control of the fluidization velocity gradient of the single air chamber 1 and the dynamic pressure of the spray gun 8, low-temperature and high-efficiency drying is achieved (the tail gas temperature is 150 - 170 °C), which is especially suitable for granulating heat-sensitive materials such as calcium chloride. Since the main structure of this device is circular and the fluidizing air has only one direction from top to bottom, the size of the opening ratio only affects the thickness of the material layer and does not affect the discharging direction, so a relatively low opening ratio can be adopted. During operation, the output is controlled by controlling the thickness of the material layer, and the operation is convenient.

[0040] When the output increases, the diameter of the air distribution plate 7 becomes larger. To ensure the smooth discharging of the dried particles around, two measures are taken: A further solution of the present invention is that: as Figure 5 shown, the air distribution plate 7 is inclined downward towards the discharging port along the circumference of the drying section 2. Preferably, the inclination angle is 2 - 5°. The air distribution plate 7 is designed with a certain taper to make it easier for the finished particles around to reach the discharging port and ensure smooth discharging.

[0041] As an alternative to the above solution: to adapt to a larger output, a plurality of discharging pipes 6 are provided, and the plurality of discharging pipes 6 are evenly distributed on the air distribution plate 7. So that the finished particles flow out in multiple segments and multiple paths.

[0042] A further solution of the present invention is that: as Figure 4 shown, waterproof asbestos gaskets 10 are respectively arranged on the upper and lower sides of the air distribution plate 7.

[0043] As Figure 2 shown, a liquid package 11 and a steam package 12 are arranged at the drying section 2, similar to a pressure equalizing box. The raw material liquid and compressed air are evenly distributed after passing through this device.

[0044] As Figure 1 shown, a plurality of observation ports 13 are evenly distributed on the tube wall of the drying section 2. Preferably, 4 observation ports 13 are provided.

[0045] A sewage discharge port 14 is arranged at the bottom of the air chamber 1 to discharge the waste water after flushing the fluidized bed.

[0046] Pressure measuring ports 16 are arranged on the drying section 2 and the settling section 4 for installing pressure sensors to measure the pressures of each part.

[0047] Temperature measuring ports 15 are arranged at the air inlet 5, the air outlet 9 and the drying section 2 for installing temperature sensors to measure the temperatures of each part.

[0048] Other advantages of the present invention are as follows: The device adopts a countercurrent design method, with the drying section 2 located at the bottom. Compared with traditional fluidized beds, the drying and granulation processes are clearly demarcated, ensuring the drying effect and particle distribution. In actual operation, the temperature of the tail gas of traditional fluidized beds needs to be controlled at about 180 - 200 °C to produce qualified products, while the device can operate stably with the tail gas controlled at 150 - 170 °C. The layout of the circular single air chamber 1 has a smaller volume. Taking 2 T / H as an example, the diameter of the fluidization section of the circular fluidized bed is 2.2 meters, while the square fluidized bed requires 0.75 * 6 m, corresponding to a smaller floor area of the device.

[0049] A spray granulation drying process for calcium chloride includes the following steps: S1. Using the above spray granulation drying equipment, seed particles with a size of 1 - 2 mm are put into the drying section 2 above the air distribution plate 7. After laying, the static bed height is 0.4 - 0.6 mm. S2. Hot air with a temperature of 400 - 450 °C is introduced into the air chamber 1, and the inlet air velocity of the hot air is 15 - 20 m / s. The hot air blows the seed particles through the air distribution plate 7 into a fluidized state, and the fluidization velocity is controlled at 2.6 - 3.1 m / s to form a stable bed layer. The porosity of the stable bed layer in the fluidized state is 0.5 - 0.6. S3. Using a spray gun 8 to spray the calcium chloride solution upward from bottom to top, and the pressure of the atomized compressed air is 4 kg ± 0.5 / cm² higher than the pressure of the solution pump. S4. As the particles continuously grow by coating, they settle to the lower drying section 2 under the action of gravity, and the dried finished particles are discharged from the discharge port. S5. In the settling section 4, only a small amount of dust generated by the intense flow and friction of some particles collides and adheres here. Part of it becomes larger and then settles to the granulation section 3 for re - granulation, and a small amount of dust is taken away by the tail gas and enters the subsequent dust removal process.

[0050] In S1, the fluidization velocity and the opening ratio of the drying section are determined in the following way: 1. Calculate the fixed - bed porosity according to the particulate physical properties parameters. Particle density: = 1400 kg / m³; Bulk density: = 800 kg / m³; Fixed - bed porosity: = (1400 - 800) / 1400 = 0.43; 2. Calculate the Archimedes number according to the fluidization air parameters. , Fluidization air temperature: t = 170 °C; Fluidization air kinematic viscosity: = 29.4×10⁻ 6 m² / s; Fluidizing air density: = 0.85 kg / m³;

[0051] When the calcium chloride particles = 6mm ; 3. Calculate the critical fluidization velocity according to the critical fluidization void fraction of the fixed - bed material , According to the existing public books, according to value look up the table to get = 20;

[0052] Using the above method, calculate successively = 6mm, = 2.1m / s; = 4mm, = 1.6m / s; = 1mm, = 0.4m / s; 4. Determine the actual fluidization velocity,

[0053] In the design of the calcium chloride fluidized bed, the fluidization velocity in the general area is the critical fluidization velocity plus 1m / s, = 6mm, then the fluidization velocity in the drying section = 3.1m / s, = 4mm, the fluidization velocity = 2.6m / s, = 1mm the fluidization velocity = 1.4m / s, According to the above velocities, determine the diameters of each section in the granulation section successively to ensure the best flow state during operation.

[0054] 5. Calculation of the perforation rate of the air distribution plate (1). Calculate the pressure drop of the bed layer according to the thickness of the material layer Calculate the bed - layer pressure drop

[0055] = 4mm, = 320kg / m 2 , = 5mm, = 400 kg / m 2 , (2). Pressure drop of air distribution plate Set

[0056] = 4 mm, = 32 kg / m 2 , = 5 mm, = 40 kg / m 2 , (3). Reynolds number Re Calculate

[0057] With the optimal finished product particle size = 6 mm, then the fluidization velocity in the drying section = 3.1 m / s, = 632; Look up the hole velocity coefficient in the existing public books = 0.7; (4). Small hole gas velocity Calculate

[0058] = 4 mm, , = 5 mm, , = 6 mm, ; (5). Calculation of orifice opening rate φ

[0059] = 4 mm, , = 5 mm, , = 6 mm, .

[0060] Since the main structure of this device is circular and the fluidizing air has only one direction from top to bottom, the size of the orifice opening rate only affects the thickness of the material layer and will not affect the discharging direction. A relatively low orifice opening rate can be taken, and the output is controlled by controlling the thickness of the material layer during operation. It is convenient to operate.

[0061] The spray gun uses two-fluid atomization. The liquid material uses an ordinary centrifugal pump with a head of 30 m. The atomizing compressed air pressure is greater than the outlet pressure of the centrifugal pump by about 4 kg / cm². With this design, while ensuring the atomization effect, the kinetic energy of the atomized liquid material is relatively low and it always remains inside the material layer with a void fraction of 0.5 - 0.6. It continuously undergoes coating and drying among the flowing particles without being able to penetrate the material layer, reducing the situation of wall sticking and dusting.

[0062] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be embraced within the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

Claims

1. A spray granulation drying device for calcium chloride, characterized in that: The invention comprises an air chamber (1), a drying section (2), a granulation section (3) and a sedimentation section (4), wherein the sedimentation section (4), the granulation section (3) and the drying section (2) are arranged in sequence from top to bottom, the air chamber (1) is arranged at the bottom of the drying section (2), an air inlet (5) for introducing hot air is arranged on one side of the air chamber (1), an air distribution plate (7) is arranged between the air chamber (1) and the drying section (2), openings are evenly arranged on the air distribution plate (7), a feed pipe (6) is arranged at the bottom of the drying section (2), a plurality of evenly distributed spray guns (8) with a spray direction vertically upward are arranged in the drying section (2), and the sedimentation section (4) is provided with a plurality of evenly distributed spray guns (8) with a spray direction vertically upward. ) is provided with an air outlet (9) on one side of the top, the cross-sectional area of ​​the granulation section (3) gradually increases from bottom to top, and the cross-sectional area of ​​the sedimentation section (4) is constant; the fluidization velocity of the granulation section (3) is 2.6m / s~3.1m / s, and the taper of the granulation section (3) is 44°-45°; the static material layer thickness of the granulation section (3) is 0.4m~0.6m, the porosity of the material layer in the fluidized state is 0.5~0.6, the opening rate of the air distribution plate (7) is 13%~16%, and the spray gun (8) uses two-fluid atomization, and the atomization compressed air pressure is greater than the centrifugal pump outlet pressure by 4±0.5kg / cm².

2. A spray granulation drying device for calcium chloride according to claim 1, characterized in that: The air distribution plate (7) is arranged obliquely along the circumference of the drying section (2) toward the lower material outlet.

3. A spray granulation drying device for calcium chloride according to claim 2, characterized in that: The inclination angle of the air distribution plate (7) is 2-5°.

4. A spray granulation drying device for calcium chloride according to claim 2, characterized in that: A plurality of the feed pipes (6) are provided, and the plurality of feed pipes (6) are evenly distributed on the air distribution plate (7).

5. A spray granulation drying device for calcium chloride according to claim 2, characterized in that: Waterproof asbestos pads (10) are respectively provided on the upper and lower sides of the air distribution plate (7).

6. A spray granulation drying device for calcium chloride according to claim 2, characterized in that: The drying section (2) is provided with a liquid drum (11) and a steam drum (12).

7. A spray granulation drying device for calcium chloride according to claim 2, characterized in that: A plurality of observation ports (13) are evenly distributed on the tube wall of the drying section (2).

8. A spray granulation drying device for calcium chloride according to claim 2, characterized in that: A sewage outlet (14) is provided at the bottom of the wind chamber (1).

9. A spray granulation drying device for calcium chloride according to claim 2, characterized in that: The drying section (2) and the settling section (4) are provided with pressure measuring ports (16), and the air inlet (5), the air outlet (9) and the drying section (2) are provided with temperature measuring ports (15).

10. A spray granulation drying process for calcium chloride as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Using the above-mentioned spray granulation drying equipment, 1-2 mm seed particles are placed into the drying section (2) above the air distribution plate (7). After laying, the static material layer height is 0.4-0.6m. S2. hot air at a temperature of 400-450° C. is introduced into the air chamber (1) at a hot air inlet velocity of 15-20 m / s. The hot air blows the seed particles into a fluidized state through the air distribution plate (7). The fluidization velocity is controlled to be 2.6-3.1 m / s to form a stable material layer. The porosity of the stable material layer in the fluidized state is 0.5-0.6; S3. The calcium chloride solution is sprayed upward from bottom to top using a spray gun (8), and the atomizing compressed air pressure is 4kg±0.5 / cm² higher than the solution pump pressure; S4. As the particles continue to grow, they settle to the lower drying section (2) under the action of gravity, and the finished particles are discharged from the feed port; S5. Small dust particles generated by the intense flow and friction of particles in the sedimentation section (4) collide and adhere here, while another part becomes larger and settles to the granulation section (3) for re-granulation. A small part of the dust enters the subsequent dust removal process through the air outlet (9).

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