A fluidized bed granulator and granulation method

Abstract

This application discloses a fluidized bed granulator and granulation method, belonging to the field of fluidized bed granulation technology. The fluidized bed granulator includes a shell, within which a fluidization chamber is provided. Two rows of heat exchangers are arranged along the length of the fluidization chamber within the chamber, and a vertical channel is provided between the two rows of heat exchangers. This allows the fluidized granular material to circulate by rising along the vertical channel and descending along the space of the heat exchangers. Above each of the two rows of heat exchangers, a row of spray guns is arranged along the length of the fluidization chamber. The spray guns pass through the shell and are horizontally inserted into the fluidized material layer. The two rows of spray guns are staggered along the length of the fluidization chamber. The spray guns are airflow-type spray guns, and their fan-shaped atomizing surfaces are interconnected. This application utilizes the thrust of atomized compressed gas to flatten the material layer above the heat exchangers, reducing the height difference between the material layers. This allows the granular material to pass through the heat exchangers uniformly at a relatively consistent speed, achieving uniform drying and improving granulation efficiency and product quality.

Description

Technical Field

[0001] This application belongs to the field of fluidized bed granulation technology, specifically relating to a fluidized bed granulator and granulation method. Background Technology

[0002] Fluidized bed granulation technology involves spraying atomized liquid material onto the surface of fluidized particulate material in a fluidized bed, causing the liquid material to agglomerate on the particle surface through coating and agglomeration. Since its industrial application in 1965, this technology has been widely used in chemical, food, and pharmaceutical industries.

[0003] Fluidized bed granulation dryers are also known as fluidized bed granulators, fluidized bed spray granulators, fluidized bed spray granulation dryers, spray fluidized bed granulators, and spray fluidized bed granulation dryers. The fluidized particulate material within the fluidized bed is called the bed layer or material layer, and the space within the bed layer is called the fluidization chamber. Based on whether the production operation is continuous, they can be divided into continuous fluidized bed granulators and intermittent fluidized bed granulators. Currently, the most common continuous fluidized bed granulators in industrial production come in various forms depending on the spray gun position, such as bottom-side spray fluidized bed granulators (see CN201565289U), top-bottom spray fluidized bed granulators (see CN2629820Y), and bottom-top spray fluidized bed granulators (see CN2471821Y). Based on whether they have an internal heat exchanger, they can be divided into fluidized bed granulators with and without an internal heat exchanger.

[0004] Fluidized bed granulators with internal heat exchangers have high thermal efficiency because the internal heat exchanger is embedded in the fluidized layer of the fluidized bed, providing most of the required drying heat. Chinese patent document CN102744009A discloses a fluidized bed with an internal heat exchanger. Vertically arranged channel plates are installed in the fluidization chamber, forming channels between the channel plates or between the channel plates and the shell. Utilizing the low fluidization resistance in the channel area and the high fluidization resistance in the internal heat exchanger area, particles flow upwards in the channels and then turn downwards in the internal heat exchanger area at the top of the fluidized layer, thus forming a directional circulating flow of the particle material. The particle material contacts the atomized droplets when passing through the atomization zone. However, due to the low fluidization resistance in the channels, the particle material, under the action of the fluidizing gas, forms a high, gushing layer after reaching the top of the channels. That is, the height of the layer above the channels is significantly higher than the height of the layer above the heat exchanger, which in turn drives the particle material at the top of the channels to flow towards the heat exchanger side, resulting in uneven distribution of the layer above the heat exchanger. Specifically, the material layer is higher in areas closer to the channel above the heat exchanger and lower in areas farther from the channel. The material's own gravity provides the downward force, while the fluidizing gas provides upward buoyancy. When the upward buoyancy is equal across all cross-sections of the heat exchanger, the higher the material layer, the greater the weight of the material, and the greater the difference between gravity and buoyancy. This results in a stronger driving force for downward movement in these areas, propelling the particles downwards at a faster speed. Conversely, the lower the material layer, the smaller the difference between gravity and buoyancy, resulting in a weaker downward driving force and slower particle descent. This speed difference causes variations in heat and mass transfer rates and drying times across the same heat exchanger cross-section. Particles farther from the channel experience slower downward movement, longer drying times, and are prone to localized overheating, agglomeration, unstable overall bed fluidization, bed collapse, and poor product quality. Furthermore, the uneven downward movement speed of particles across different areas of the heat exchanger leads to a lower overall circulation speed, poorer heat and mass transfer, and lower drying efficiency. Summary of the Invention

[0005] The main objective of this application is to provide a fluidized bed granulator and granulation method to solve the problems of excessively long local drying time, unstable bed fluidization, and low product quality caused by uneven material distribution above the heat exchanger in the existing fluidized bed granulator with an internal heat exchanger, thereby further improving granulation efficiency.

[0006] To address the aforementioned technical problems, this application provides a fluidized bed granulator. The shell contains, from bottom to top, an air inlet chamber, a fluidizing chamber, and a settling chamber. An air distribution plate is provided between the air inlet chamber and the fluidizing chamber. Two rows of heat exchangers are arranged along the length of the fluidizing chamber within the fluidizing chamber. A vertical channel is provided between the two rows of heat exchangers. The fluidized granular material within the fluidizing chamber circulates by rising along the vertical channel and descending along the space of the heat exchangers. Above each of the two rows of heat exchangers, a row of spray guns is arranged along the length of the fluidizing chamber. The spray guns pass through the shell and are horizontally inserted into the fluidized material layer. The two rows of spray guns are staggered along the length of the fluidizing chamber. The spray guns are airflow-type spray guns, forming a fan-shaped atomizing surface within the cross-section of the fluidized material layer. The fan-shaped atomizing surfaces of the spray guns are interconnected. In this application, "interconnected" means that the edges of the fan-shaped atomizing surfaces formed by the spray guns are connected or partially overlapped, making the atomization zone continuous overall.

[0007] By employing the above-described technical solution, the technical solution provided in this application has at least the following advantages: (i) Eliminate the height difference of the material layer above the heat exchanger to achieve uniform passage of particulate material through the heat exchanger. In existing technologies, because the atomization zone only covers a localized area, there is a significant height difference in the material layer above the heat exchanger (higher near the vertical channel and lower further away), resulting in inconsistent velocity of the particulate material as it descends through the heat exchanger, poor local fluidity, and consequently, problems such as agglomeration, accumulation, and blockage. In severe cases, it can even cause instability in the fluidized bed and pose a risk of bed collapse. This application addresses this by setting two rows of heat exchangers and a vertical channel between them within the fluidization chamber, enabling the particulate material to form a directional circulating motion of "rising along the channel and falling along the heat exchanger side." Furthermore, horizontally inserted and staggered airflow spray guns are installed above the two rows of heat exchangers, allowing the fan-shaped atomization surfaces formed by compressed air to connect and create a continuous, non-overlapping atomization zone. The thrust of the atomized compressed gas flattens the particulate material layer above the heat exchanger, reducing the height difference of the material layer above the heat exchanger. As a result, particulate materials can pass through the heat exchanger at a relatively uniform speed, resulting in a more uniform distribution of the drying residence time of particulate materials in the heat exchanger area. This effectively eliminates problems such as excessively long drying time, localized material retention, and overheating caused by the slow downward movement speed in the heat exchanger area away from the vertical channel. It also reduces the risk of localized material agglomeration, dead bed, and bed collapse, making the material temperature distribution in all sections of the bed in the heat exchanger area more uniform, resulting in better product quality and more stable bed fluidization.

[0008] (ii) Enhance the circulation and heat and mass transfer of particulate materials to improve drying efficiency. Because the material layer above the heat exchanger tends to be flat, the downward movement speed of the granular material becomes more uniform, resulting in faster circulation and a shorter circulation cycle. Simultaneously, by connecting the atomizing surfaces, the dry granular material can come into contact with the atomized liquid as much as possible, leading to a more uniform wet-dry distribution of the granular material. On one hand, the lower bed temperature is beneficial for increasing drying intensity, thus allowing for a higher liquid spray volume from the spray gun and improving granulation efficiency. On the other hand, the elimination of localized overheating ensures a uniform temperature difference between the material, the heat exchanger, and the hot air, preventing reduced evaporation intensity due to localized overheating and further improving drying efficiency.

[0009] (III) Optimize product particle size distribution and improve product quality Because the granular material is circulated evenly and dried consistently, the contact and heating conditions between the granules and the atomized liquid during the growth process tend to be consistent, which helps to improve the uniformity of the particle size of the granular material in the bed, resulting in a narrower particle size distribution range in the final product and a significant improvement in product quality.

[0010] As an alternative approach in this application, interconnected fan-shaped atomizing surfaces collectively cover the cross-section of the fluidized material layer. Through this arrangement, a continuous atomizing zone without significant overlap is formed within the cross-section of the fluidized material layer. When the interconnected fan-shaped atomizing surfaces further collectively cover the cross-section of the fluidized material layer, the leveling effect of the material layer is more significant, and the drying uniformity is further improved.

[0011] Furthermore, within the cross-section of the fluidization chamber, the included angle is α, with the center point of the nozzle of one spray gun in a row as the vertex and the center points of the nozzles of two spray guns adjacent to that spray gun in another row as the other two points; the atomization angle of the fan-shaped atomization surface of the spray gun is β; and α≤β.

[0012] Furthermore, the atomization angle β and the included angle α also satisfy β ≤ 1.1α. Within this range, there is only a small overlap between adjacent fan-shaped atomization surfaces. If the overlap is too large, on the one hand, it will lead to excessively high local atomized droplet concentration, significantly increasing the moisture content in that area, requiring more heat to complete drying, and increasing energy consumption; on the other hand, overlapping droplets are prone to collision and merging to form larger droplets. When these large droplets come into contact with the granular material, it becomes more difficult for moisture to migrate into the particle interior, and the droplet's own gravity will also increase, possibly exceeding the carrying capacity of the normal fluidizing airflow, causing the particles to be unable to maintain a stable fluidized state. The combined effect of the above factors can easily cause material agglomeration and local bed collapse within the bed, and in severe cases, even prevent the granulation process from operating continuously and stably. Therefore, controlling β within 1.1α can effectively avoid the risks of uneven drying load, decreased particle quality, and fluidization instability caused by excessive overlap of atomization surfaces, ensuring the leveling effect of the material layer and the uniformity of drying.

[0013] As an optional embodiment of this application, the spray gun is a swirl-type spray gun, and its atomization angle β is adjustable within a range of 20° to 30°. Using this technical solution, the operator can freely adjust the β angle according to process requirements, ensuring that the included angle α with the fixed angle α after equipment assembly satisfies α≤β, thereby achieving optimal matching of the fan-shaped atomization surface.

[0014] As an alternative embodiment of this application, when the projections of two adjacent spray guns in one row onto another row include one spray gun from that other row, the spray gun is located exactly in the middle of the projections of the two adjacent spray guns.

[0015] Furthermore, along the length of the fluidizing chamber, there is a safe distance between the fan-shaped atomizing surfaces of the spray guns located at both ends of the fluidizing chamber and the sidewalls or endwalls of the fluidizing chamber. Using this technical solution, the atomized droplets sprayed from the spray guns at both ends of the fluidizing chamber will not be sprayed onto the sidewalls or endwalls of the fluidizing chamber, thus avoiding wall adhesion or even scaling.

[0016] As an optional embodiment of this application, the air distribution plate in the area directly below the heat exchanger is horizontally arranged, and the opening ratio of the air distribution plate in this area is uniform. Using this technical solution, the particulate material in this area can obtain uniform fluidizing buoyancy, which, in conjunction with the effect of atomized compressed gas to make the particulate material layer above the heat exchanger tend to be flat, ensures that the particulate material moves downward through the heat exchanger at a relatively uniform speed, further improving drying uniformity.

[0017] As an optional embodiment of this application, the opening ratio of the area directly below the vertical channel on the air distribution plate is equal to or greater than the opening ratio of the area directly below the heat exchanger on the air distribution plate. This technical solution helps to increase the circulation speed of particulate materials and enhance the drying effect.

[0018] As an optional embodiment of this application, the ratio of the width of the vertical channel to the width of the fluidizing chamber is 0.1 to 0.35. By controlling the ratio of the vertical channel width to the fluidizing chamber width within the range of 0.1 to 0.35, this application ensures that the vertical channel occupies a relatively small proportion (10% to 35%) of the fluidizing chamber cross-section, while the proportion occupied by the two rows of heat exchangers and their outer areas is correspondingly larger (65% to 90%). On the one hand, a sufficiently wide heat exchanger area provides ample heat exchange area and residence time for the particulate material, facilitating full contact between the material and the heat exchanger, thus improving drying efficiency and heat utilization. On the other hand, maintaining a moderate width for the vertical channel ensures sufficient upward airflow space and material circulation throughput without being excessively wide, which would lead to over-compression of the heat exchanger area. This ratio range achieves a balance between "a sufficiently narrow vertical channel to maintain rapid directional circulation, and a sufficiently wide heat exchanger area to ensure efficient heat exchange," further optimizing the overall performance of the fluidized bed granulator.

[0019] Based on the same inventive concept, this application also provides a fluidized bed granulation method using the above-mentioned fluidized bed granulator: fluidizing gas is introduced into the air inlet chamber to fluidize the granular material above the air distribution plate, causing it to circulate by rising along the vertical channel and descending along the space of the heat exchanger area within the fluidized chamber; atomized droplets are sprayed into the bed layer of the fluidized chamber through a spray gun to form a fan-shaped atomization surface in the cross-section of the fluidized material layer, and the fan-shaped atomization surfaces of the spray gun are interconnected; the granular material is heated and dried using a heat exchanger. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure and material flow field of a fluidized bed granulator according to an embodiment of this application.

[0021] Figure 2 for Figure 1 A top view of a fluidized bed granulator.

[0022] Figure 3 This is a schematic diagram of α and β for another embodiment of this application.

[0023] In the figure, 1-shell, 2-air inlet chamber, 3-fluidization chamber, 4-sedimentation chamber, 5-air distribution plate, 6-fan-shaped atomizing surface, 7-heat exchanger, 8-vertical channel, 9-spray gun, 9.1-first spray gun, 9.2-second spray gun, 9.3-third spray gun. Detailed Implementation

[0024] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0025] Example 1 This embodiment provides a fluidized bed granulator, the structure of which is as follows: Figure 1 As shown, the top view is as follows Figure 2 As shown. The fluidized bed granulator includes a shell 1, and inside the shell 1, from bottom to top, there are an air inlet chamber 2, a fluidization chamber 3 and a settling chamber 4. An air distribution plate 5 is provided between the air inlet chamber 2 and the fluidization chamber 3.

[0026] like Figure 1 As shown, fluidization chamber 3 is rectangular in shape and has a length direction (i.e., Figure 2 (the direction extending vertically) and the width direction (i.e.) Figure 2 (Extending left and right in the direction). Two rows of heat exchangers 7 are arranged along the length of the fluidization chamber 3, and a vertical channel 8 is provided between the two rows of heat exchangers 7. During operation, the particulate material in the fluidized state in the fluidization chamber 3 rises along the vertical channel 8 and descends along the space of the area where the heat exchangers 7 are located, forming a directional circulation motion.

[0027] Above each of the two rows of heat exchangers 7, along the length of the fluidization chamber 3, is a row of spray guns 9. For example... Figure 2 As shown, the spray gun 9 passes through the housing 1 and is horizontally inserted into the fluidized bed. The spray guns 9 are staggered along the length of the fluidization chamber 3. The spray guns 9 are airflow spray guns, using compressed air as the atomizing gas. The spray guns 9 form fan-shaped atomizing surfaces 6 within the cross-section of the fluidized bed. The fan-shaped atomizing surfaces 6 of the spray guns 9 are interconnected.

[0028] It should be noted that the so-called "interconnection" means that the edges of the fan-shaped atomizing surface 6 formed by the spray gun 9 are connected or partially overlapped, so as to form a continuous atomizing zone within the cross-section of the fluidized material layer.

[0029] Example 2 This embodiment provides a fluidized bed granulation method using the fluidized bed granulator as described in Embodiment 1: Fluidizing gas (e.g., hot air) is introduced into the air inlet chamber 2. The fluidizing gas enters the fluidization chamber 3 through the air distribution plate 5, causing the particulate material above the air distribution plate 5 to be in a fluidized state. Figure 1 As shown, the solid arrows indicate the movement trend of the particulate material. Under the action of the two rows of heat exchangers 7 and the vertical channel 8 between them, the particulate material forms a directional circulating movement that rises along the vertical channel 8 and descends along the space of the area where the heat exchangers 7 are located.

[0030] Simultaneously, atomized droplets are sprayed into the fluidization chamber 3 through the spray gun 9, forming a fan-shaped atomization surface 6 within the cross-section of the fluidized material layer. The atomized compressed gas has sufficient pressure to allow the fan-shaped atomization surfaces 6 to connect with each other and generate sufficient thrust.

[0031] A heat medium (such as steam, thermal oil, or hot water) is introduced into the heat exchanger 7 to heat and dry the material in the fluidization chamber 3.

[0032] Under the thrust of the atomized compressed gas ejected from the spray gun 9, the material layer above the heat exchanger 7 tends to flatten, and the height difference between the material layers is significantly reduced. The granular material descends uniformly through the heat exchanger 7 at a relatively consistent speed, resulting in uniform heat and mass transfer, a uniform bed temperature distribution, and no localized overheating or agglomeration. Due to the reduced height difference between the material layers, the circulation speed is increased, and the drying efficiency is improved. Compared to schemes without the spray gun arrangement of this application, the spray volume of this embodiment is significantly increased, resulting in a corresponding increase in granulation output, uniform product particle size distribution, stable bed fluidization, and no risk of bed collapse.

[0033] Example 3 This embodiment provides a fluidized bed granulator, the structure of which is as follows: Figure 1 , Figure 2 As shown. The fluidized bed granulator includes a shell 1, and inside the shell 1, from bottom to top, there are an air inlet chamber 2, a fluidization chamber 3 and a settling chamber 4. An air distribution plate 5 is provided between the air inlet chamber 2 and the fluidization chamber 3.

[0034] like Figure 1 As shown, fluidization chamber 3 is rectangular in shape and has a length direction (i.e., Figure 2 (the direction extending vertically) and the width direction (i.e.) Figure 2 (Extending in the left and right directions). Two rows of heat exchangers 7 are arranged along the length of the fluidization chamber 3, with a vertical channel 8 between the two rows of heat exchangers 7. The heat exchangers 7 are either tubular or plate heat exchangers. As an option, in this embodiment, the heat exchangers 7 are tubular heat exchangers, through which a heat medium (steam is used in this embodiment) is circulated to heat and dry the material within the fluidization chamber 3. Each row of heat exchangers 7 includes multiple heat exchanger units arranged along the length of the fluidization chamber 3. The heat exchanger units on both sides of the vertical channel 8 are symmetrically arranged to ensure the symmetry and stability of the particulate material circulation within the fluidization chamber 3.

[0035] The ratio of the width of the vertical channel 8 to the width of the fluidizing chamber 3 is 0.1 to 0.35. As an optional approach, in this embodiment, the ratio of the width of the vertical channel 8 to the width of the fluidizing chamber 3 is 0.24. Those skilled in the art will understand that the ratio of the width of the vertical channel 8 to the width of the fluidizing chamber 3 can be selected within the range of 0.1 to 0.35, for example, 0.1, 0.2, 0.3 or 0.35.

[0036] The air distribution plate 5 is horizontally positioned in the area directly below the heat exchanger 7, and this area has a uniform opening ratio. This allows the particulate material in this area to receive uniform fluidizing buoyancy. Combined with the effect of the atomized compressed gas flattening the particulate material layer above the heat exchanger, this ensures that the particulate material moves downwards through the heat exchanger 7 at a relatively uniform speed, further improving drying uniformity. The opening ratio of the area on the air distribution plate 5 directly below the vertical channel 8 is equal to the opening ratio of the area directly below the heat exchanger 7.

[0037] Above each of the two rows of heat exchangers 7, along the length of the fluidization chamber 3, is a row of spray guns 9. The spray guns 9 pass through the shell 1 and are horizontally inserted into the fluidized material layer. The spray guns 9 are airflow spray guns, using compressed air as the atomizing compressed gas. As an optional method, this embodiment uses flat fan-shaped atomizing spray guns to form a fan-shaped atomizing surface 6 within the cross-section of the fluidized material layer. This atomization pattern can generate a greater thrust within the cross-section of the fluidized material layer, which is beneficial for making the particulate material layer above the heat exchangers 7 tend to be flat. The outlet of the spray guns 9 is located at a certain distance above the heat exchangers 7. This distance should ensure that the atomizing compressed gas can effectively act on the material layer above the heat exchangers 7, while avoiding spraying liquid material onto the heat exchangers 7 and causing scaling.

[0038] like Figure 2As shown, two rows of spray guns 9 are staggered along the length of the fluidization chamber 3. In this embodiment, when the projections of two adjacent spray guns 9 in one row onto the other row include one spray gun 9 from that other row, that spray gun 9 is located precisely in the middle of the projections of the two adjacent spray guns 9. Specifically, as... Figure 2 As shown, taking the first spray gun 9.1, the second spray gun 9.2, and the third spray gun 9.3 as examples, the first spray gun 9.1 and the second spray gun 9.2 are two adjacent spray guns in the right row. Projecting the first spray gun 9.1 and the second spray gun 9.2 vertically along the width of the fluidization chamber 3 onto the straight line of the left row yields two projection points (not shown in the figure). The third spray gun 9.3 in the left row is located exactly between these two projection points, and the distance from the center point of the third spray gun 9.3 to the two projection points is equal; that is, the third spray gun 9.3 is located in the exact middle of the projections of the first spray gun 9.1 and the second spray gun 9.2. Similarly, the projections of adjacent spray guns in the left row onto the right row also include the corresponding spray guns in the right row, and these spray guns are located in the exact middle position. Through this arrangement, the two rows of spray guns form a uniform alternating stagger in the length direction, ensuring the uniform connection of the fan-shaped atomization surface within the cross-section of the fluidization chamber.

[0039] The lateral distance between the two rows of spray guns 9 and the spacing between adjacent spray guns 9 in the same row are set according to the atomization angle of the spray guns 9 and the width and length of the fluidization chamber 3, so that the fan-shaped atomization surfaces 6 of adjacent spray guns 9 are connected at their edges or partially overlap (in this embodiment, they are connected at their edges) within the cross-section of the fluidized material layer, thereby forming a continuous atomization zone. As an optional approach, in this embodiment, each row of spray guns 9 is arranged at equal intervals, and the arrangement spacing between the two rows of spray guns is the same.

[0040] Within the cross-section of the fluidization chamber 3, the included angle α is formed by taking the center point of the nozzle of one spray gun 9 in one row as the vertex, and the center points of the nozzles of the two spray guns 9 adjacent to that spray gun in another row as the other two points. Specifically, as shown... Figure 2 As shown, taking the first spray gun 9.1, the second spray gun 9.2, and the third spray gun 9.3 as examples, with the center point of the nozzle of the third spray gun 9.3 in the left row as the vertex, and the center points of the nozzles of the first spray gun 9.1 and the second spray gun 9.2 in the right row adjacent to the third spray gun 9.3 as the other two points, the included angle formed by the line connecting the three points is α. The atomization angle of the fan-shaped atomizing surface 6 of the spray gun 9 is β. In this application, α≤β. As an optional method, in this embodiment, β=α=23°, so that the edges of the fan-shaped atomizing surface 6 of the spray gun 9 are connected and jointly cover the cross-section of the fluidized material layer. Through the above arrangement, this embodiment forms a continuous and non-overlapping atomization zone within the cross-section of the fluidized material layer.

[0041] In this embodiment, the spray gun 9 is a swirling spray gun. It has an internal gas guide channel and a liquid guide cone. Compressed air, after passing through the guide channel, rotates at high speed, creating a quadruple superposition of axial shearing, radial centrifugal force, swirling turbulence, and circumferential shearing with the liquid material inside and at the outlet of the spray gun. This results in finer atomized droplets, more uniform distribution, and a wider atomization coverage. Simultaneously, the atomization angle β of this spray gun can be freely adjusted within the range of 20° to 30°. The size of the atomization angle β is mainly determined by the guide angle of the gas guide channel: the larger the gas guide angle, the stronger the rotating airflow, and the larger the atomization angle β. The guide angle of the liquid guide cone mainly affects the uniformity of droplet distribution on the cross-sectional end face of the atomization zone; the larger the guide angle, the higher the droplet distribution probability in the outer circular area. By synergistically adjusting the gas and liquid guide angles, an ideal atomization angle β can be obtained within the range of 20° to 30°.

[0042] Along the length of the fluidization chamber 3, the fan-shaped atomizing surface 6 of the spray gun 9 located at both ends of the fluidization chamber 3 has a safe distance of 30~100mm between it and the end wall of the fluidization chamber 3, so as to avoid the atomized droplets being sprayed directly onto the end wall and causing wall adhesion or even scaling.

[0043] During operation, fluidizing gas (hot air is used in this embodiment, and the temperature is set according to process requirements) is introduced into the air inlet chamber 2. The fluidizing gas enters the fluidization chamber 3 through the air distribution plate 5, causing the particulate material above the air distribution plate 5 to fluidize. Under the action of the two rows of heat exchangers 7 and the vertical channel 8 between them, the particulate material forms a directional circulation motion that rises along the vertical channel 8 and falls along the space where the heat exchangers 7 are located.

[0044] A heat medium (steam is used in this embodiment, and the pressure and temperature are set according to process requirements) is introduced into the heat exchanger 7 to heat and dry the material in the fluidization chamber 3. At the same time, liquid material is sprayed into the fluidization chamber 3 through the spray gun 9. The atomized compressed gas has sufficient pressure to allow the fan-shaped atomizing surfaces 6 to connect with each other and generate sufficient thrust.

[0045] Under the thrust of the atomized compressed gas ejected from the spray gun 9, the material layer above the heat exchanger 7 tends to flatten. The particulate material falls uniformly through the heat exchanger 7 at a relatively uniform speed, resulting in uniform heat and mass transfer, uniform bed temperature distribution, and no local overheating or agglomeration.

[0046] Due to the reduced material layer height difference, the circulation speed is increased, and the drying efficiency is improved. In this embodiment, the liquid spraying volume of the spray gun is significantly increased compared with the prior art (which does not use the spray gun arrangement of this application), resulting in a corresponding increase in granulation output, uniform product particle size distribution, stable bed fluidization, and no risk of bed collapse.

[0047] Example 4 Figure 3Example 4 is shown. The difference between this example and Example 3 lies in the relationship between the atomization angle and the included angle of the spray gun 9, as well as the connection method between the fan-shaped atomization surfaces, as detailed below: In this embodiment, within the cross-section of the fluidization chamber 3, the included angle is α, with the center point of the nozzle of one spray gun 9 in one row as the vertex and the center points of the nozzles of two spray guns 9 adjacent to that spray gun in another row as the other two points; the atomization angle of the fan-shaped atomizing surface 6 of the spray gun 9 is β. This differs from the arrangement in Embodiment 3 where β=α and the edges of the fan-shaped atomizing surface are connected, as shown below. Figure 3 As shown, in this embodiment, β is slightly greater than α. Specifically, in this embodiment, β = 23°. Figure 3 (As shown by the dashed line), α = 21° ( Figure 3 (As shown by the dashed line in the middle), so that the fan-shaped atomizing surfaces 6 of adjacent spray guns 9 partially overlap within the cross-section of the fluidized material layer.

[0048] It should be noted that the core of this application lies in ensuring that the atomization angle β of the spray gun and its corresponding included angle α satisfy the proportional relationship of α≤β≤1.1α. The β=23° and α=21° given in this embodiment are merely specific examples, intended to demonstrate that when β is slightly larger than α (but still satisfies β≤1.1α), a small overlap of the fan-shaped atomization surface can be achieved. In other embodiments, the absolute values ​​of α and β can be flexibly adjusted according to factors such as the actual size of the fluidization chamber and the installation spacing of the spray guns, provided that α≤β≤1.1α is satisfied. For example, β=25° and α=23°, or β=22° and α=21.3°, or β=22° and α=20.5°, etc., all of which can achieve the inventive objective of moderate overlap and avoidance of excessive overlap.

[0049] Based on the aforementioned angular relationship, the lateral distance between the two rows of spray guns 9 and the spacing between adjacent spray guns 9 in the same row are set accordingly, so that the fan-shaped atomizing surfaces 6 of adjacent spray guns 9 form a moderate overlap within the cross-section of the fluidized material layer. The size of the overlapping area should be controlled to be less than 10% of the area of ​​a single fan-shaped atomizing surface to avoid excessive concentration of local droplets or excessive thrust superposition. Through this arrangement, the fan-shaped atomizing surfaces 6 of the spray guns 9 are connected to each other, jointly covering the cross-section of the fluidized material layer, forming a continuous atomization zone without significant overlap.

[0050] Since β is slightly larger than α and there is moderate overlap between the atomizing surfaces, the atomizing zone in this embodiment has appropriate coverage redundancy within the cross-section of the fluidized material layer. This ensures the continuity of the atomizing zone and avoids problems such as local over-wetting or uneven thrust caused by excessive overlap. The thrust of the atomized compressed gas on the particulate material layer above the heat exchanger 7 is more uniform and stable, which can effectively make the material layer tend to be flat.

[0051] The other structures and working processes in this embodiment are the same as in Embodiment 3, and will not be repeated here.

[0052] Example 5 The difference between this embodiment and embodiment 3 is that the opening ratio of the area directly below the vertical channel 8 on the air distribution plate 5 is greater than that of the area directly below the heat exchanger 7. This reduces the fluidization resistance in the vertical channel 8 area, which is beneficial for the particulate material to move upward along the vertical channel 8 and form a stable directional circulation. Specifically, the opening ratio of the area directly below the vertical channel 8 is 20% higher than that of the area directly below the heat exchanger 7.

[0053] The other structures and working processes in this embodiment are the same as in Embodiment 3, and will not be repeated here.

Claims

1. A fluidized bed granulator, characterized in that: Includes the housing (1); The shell (1) is provided with an air inlet chamber (2), a fluidization chamber (3) and a settling chamber (4) in sequence from bottom to top, and an air distribution plate (5) is provided between the air inlet chamber (2) and the fluidization chamber (3). The fluidization chamber (3) is provided with two rows of heat exchangers (7) arranged along the length of the fluidization chamber (3); A vertical channel (8) is provided between the two rows of heat exchangers (7). The particulate material in the fluidized state in the fluidization chamber (3) rises along the vertical channel (8) and descends along the space of the area where the heat exchanger (7) is located, and circulates. Above each of the two rows of heat exchangers (7), a row of spray guns (9) is provided along the length of the fluidization chamber (3). The spray guns (9) pass through the shell (1) and are horizontally inserted into the fluidized material layer. The two rows of spray guns (9) are arranged alternately along the length of the fluidization chamber (3). The spray gun (9) is an airflow spray gun. The spray gun (9) forms a fan-shaped atomizing surface (6) in the cross-section of the fluidized material layer. The fan-shaped atomizing surfaces (6) of the spray gun (9) are connected to each other. The thrust of the atomized compressed gas makes the granular material layer above the heat exchanger (7) tend to be flat, reducing the height difference of the material layer above the heat exchanger (7). Interconnected fan-shaped atomizing surfaces (6) jointly cover the cross-section of the fluidized material layer; within the cross-section of the fluidizing chamber (3), the included angle is α, with the center point of the nozzle of one spray gun (9) in a row as the vertex and the center points of the nozzles of two spray guns (9) adjacent to the spray gun in another row as the other two points; the atomization angle of the fan-shaped atomizing surface (6) of the spray gun (9) is β; and α≤β; the adjustment range of the atomization angle β is 20°~30°.

2. The fluidized bed granulator according to claim 1, characterized in that: The atomization angle β and the included angle α also satisfy β≤1.1α.

3. The fluidized bed granulator according to claim 1, characterized in that: The spray gun (9) is a swirl spray gun.

4. The fluidized bed granulator according to claim 1, characterized in that: When the projection of two adjacent spray guns (9) in one row onto another row contains one spray gun (9) of that other row, the spray gun (9) is located exactly in the middle of the projection of the two adjacent spray guns (9).

5. The fluidized bed granulator according to any one of claims 1 to 4, characterized in that: Along the length of the fluidization chamber (3), there is a safe distance between the fan-shaped atomizing surface (6) of the spray gun (9) located at both ends of the fluidization chamber (3) and the side wall and end wall of the fluidization chamber (3).

6. The fluidized bed granulator according to any one of claims 1 to 4, characterized in that: The air distribution plate (5) in the area directly below the heat exchanger (7) is horizontally arranged, and the opening ratio of the air distribution plate in this area is uniform.

7. The fluidized bed granulator according to any one of claims 1 to 4, characterized in that: The opening ratio of the area directly below the vertical channel (8) on the air distribution plate (5) is equal to or greater than the opening ratio of the area directly below the heat exchanger (7) on the air distribution plate (5).

8. The fluidized bed granulator according to any one of claims 1 to 4, characterized in that: The width of the vertical channel (8) is 0.1 to 0.35 of the width of the fluidization chamber (3).

9. A fluidized bed granulation method using a fluidized bed granulator as described in any one of claims 1 to 8, characterized in that: Fluidizing gas is introduced into the air inlet chamber (2) so that the granular material above the air distribution plate (5) is in a fluidized state and circulates by rising along the vertical channel (8) and descending along the space of the heat exchanger (7) in the fluidization chamber (3). Atomized droplets are sprayed into the bed of the fluidization chamber (3) through the spray gun (9), forming a fan-shaped atomization surface (6) in the cross-section of the fluidized material layer. The fan-shaped atomization surfaces (6) of the spray gun (9) are connected to each other. The thrust of the atomized compressed gas makes the granular material layer above the heat exchanger (7) tend to be flat, reducing the height difference of the material layer above the heat exchanger (7). The particulate material is heated and dried using a heat exchanger (7).

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