A method for designing a variable-curvature hot-air distributor structure of a spray drying apparatus

Abstract

The application discloses a variable-curvature hot air distributor structure design method for a spray drying device, wherein the shell of the hot air distributor comprises an upper volute plate, a lower volute plate, a volute shell side plate, a volute shell air outlet baffle, an air inlet outer side plate, an air inlet inner side plate, a cover plate, a conical air outlet outer plate, a conical air outlet inner plate, an atomizer attachment plate and a flow guide vane, and the air inlet of the hot air distributor, the volute shell distribution area, the volute shell air outlet, the conical air outlet channel and the distributor air outlet are formed by the above components. The application has a significant effect on solving the problems of the internal flow field deviation of the tower body and the material wall sticking caused by the uneven air inlet of the flow field in the spray drying. The uniformity, speed and direction of the fluid entering the drying tower can be designed and controlled according to the material properties, high-efficiency drying is realized, and the design is coupled with the size of the drying tower, so that the same-ratio industrial scale-up design can be realized.

Description

Technical Field

[0001] This invention relates to the field of spray drying technology, and in particular to a structural design method for a variable curvature hot air distributor in a spray drying device. Background Technology

[0002] In spray drying, the flow field distribution within the drying tower has a significant impact on product quality and efficiency, and the flow field environment within the tower is almost entirely controlled by the structure of the hot air distributor. Improving the uniformity of the inlet flow field of the hot air distributor can effectively control the flow field inside the drying tower, thus promoting the quality and efficiency of spray-dried products.

[0003] The uniformity of the airflow field in spray drying directly determines important performance indicators such as material adhesion to the wall, drying time, and product moisture content during the spray drying process. Currently, most hot air distributors on the market have an inlet volute structure design that cannot ensure consistent air velocity and air volume at all parts of the outlet while simultaneously discharging air along the annular outlet.

[0004] The uniformity of the flow field in the inlet volute cavity of the hot air distributor directly determines the uniformity of the flow field inside the tower. Therefore, this is a major technical barrier in spray drying design. Solving this problem can effectively prevent airflow deviation and collision with the wall caused by the difference in flow rate and velocity between the flow fields inside the wall drying tower. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for designing a variable curvature hot air distributor for a spray drying equipment, wherein the shell of the hot air distributor includes an upper volute plate, a lower volute plate, a volute side plate, a volute outlet baffle, an outer inlet plate, an inner inlet plate, a cover plate, a conical outlet outer plate, a conical outlet inner plate, an atomizer bonding plate, and a guide vane, and the above components constitute the air inlet, volute distribution area, volute outlet, conical outlet channel, and distributor outlet of the hot air distributor; The hot air distributor is constructed entirely of 304 stainless steel, providing sufficient impact resistance, corrosion resistance, high-temperature resistance, and hygiene to meet the drying requirements of materials. The upper volute plate is formed by an Archimedean spiral and two parallel tangent lines on its outer perimeter, with the inner circle being a concentric circle aligned with the center of the outer Archimedean spiral. The size of the concentric circle matches the diameter of the volute's outlet baffle, and the distance between the two parallel lines matches the width of the inlet. The lower volute plate is designed identically to the upper volute plate. The volute side plate is connected to the upper and lower volute plates, its shape matching the outer structure of the upper volute plate, and its height matching the inlet height. The diameter of the volute outlet baffle is designed to be 0.2 times the diameter of the external drying tower barrel. The height is determined by the cross-sectional area of ​​the volute outlet; the outer side plate of the air inlet is the side boundary structure of the air inlet channel, the height of which is determined by the height of the air inlet, and the length is coupled with the diameter of the drying tower barrel, so that the air inlet is located at the outer surface boundary of the drying tower barrel; the structure and size of the inner side plate of the air inlet are consistent with those of the outer side plate of the air inlet; the cover plate realizes the upper space closure of the hot air distributor flow area, and forms a ring with circles of different inner and outer sizes, wherein the inner ring size is coupled with the diameter of the corresponding position of the external atomizer, and the outer ring is consistent with the inner side plate of the air inlet and forms a closed space with it; the upper volute plate, lower volute plate, volute side plate, volute outlet baffle, outer side plate of the air inlet, inner side plate of the air inlet, and cover plate are welded to form the air inlet volute structure in the hot air distributor. The conical air outlet outer plate is a conical barrel with a larger diameter at the top and a smaller diameter at the bottom. Its upper circular dimension is the same as the inner diameter of the lower volute plate and is welded to it. The bottom circular dimension is determined by the cross-sectional area of ​​the conical air outlet inner plate and the distributor's air outlet. This structure is determined after selecting a certain cone angle. The conical air outlet inner plate is a conical barrel with a smaller diameter than the conical air outlet outer plate and parallel to it. Its bottom small circular diameter is determined by the maximum size of the atomizer. The atomizer bonding plate is a conical barrel with different diameters. Its upper end is consistent with the inner ring diameter of the cover plate and is welded to it, while its lower end is welded to the lower ring of the conical air outlet inner plate. The number of guide vanes is several, evenly installed inside the conical air outlet channel, forming a certain angle with the vertical direction. The conical air outlet outer plate, conical air outlet inner plate, atomizer bonding plate, and guide vanes constitute the air outlet guiding structure in the hot air distributor. The inlet cross-sectional area is calculated based on the hot air flow rate and given inlet velocity according to the spray drying specifications. The structural dimensions are then further confirmed according to a length-to-width ratio of 1:2. The volute distribution area is controlled by the inlet volute structure, with its size determined by the volute terminal flow rate accounting for 20% of the inlet flow rate. An average flow velocity is then given inside the volute to determine the terminal flow cross-section, further determining the terminal cross-section length. The terminal cross-section width is consistent with the inlet. The volute outlet, with a diameter determined to be 0.2 times the diameter of the drying tower, is determined by combining the inlet flow rate and... Given an outlet air velocity, the cross-sectional area of ​​the structure is further calculated to determine the interface height. The conical outlet channel is formed by a lower volute plate, a conical outlet outer plate, a conical outlet inner plate, and guide vanes, providing velocity and direction for hot air entering the drying tower. The cross-sectional area of ​​the distributor outlet is calculated based on the inlet air flow rate and the given hot air inlet velocity, and the structural dimensions are determined by the size of the lower ring of the conical outlet inner plate. The inlet, volute distribution area, volute outlet, conical outlet channel, and distributor outlet constitute the internal flow area of ​​the hot air distributor.

[0006] Preferably, the diameter D of the volute air outlet is the overall design origin of the entire hot air distributor, and its design dimension is taken as the inner diameter D of the spray drying tower. 塔 of This ratio parameter is... The value should be controlled within the range of 0.2-0.4, and the specific formula is as follows: .

[0007] Preferably, based on the air inlet of the hot air distributor, the cross-sectional area S1 of the air inlet is calculated under the premise of a fixed air inlet velocity V1 and air inlet flow rate Q, while the aspect ratio of the square air inlet is... The length 'a' and width 'b' of the air inlet are determined below, and this proportional parameter... The value should be controlled within the range of 1-2. The specific formula is as follows: .

[0008] Preferably, the radial width of the terminal section d is the area through which the air flows through a plane coinciding with the inlet of the volute after completing a full circle of airflow. The principle for setting this dimension is that a portion of the inlet airflow flows through the terminal section at a velocity V2 after the fluid enters the volute, thereby determining the area of ​​the terminal section and further determining the width d. Here, a portion of the flow rate is set as a fraction of the inlet airflow. The ratio parameter is controlled within the range of 0.1-0.3. The specific formula is as follows: .

[0009] Preferably, the height h of the volute outlet is designed based on the calculated cross-sectional area S2 of the volute outlet under the premise of a fixed flow velocity V3 and an inlet flow rate Q, and is also calculated based on the diameter D of the volute outlet. The specific formula is as follows: .

[0010] Preferably, based on the above definitions and ranges of structural design parameters, the Archimedean spiral volute of the hot air distributor is further determined, and two volute structural parameters can be derived as follows: To determine the starting position and minimum radius of rotation of an Archimedean spiral, an important parameter is its base circle radius, D, which is the base circle radius of the spiral's volute. 基 The formula is determined as follows:

[0011] To represent the distance the Archimedean spiral travels along its axis in one complete rotation and to control the tightness of the spiral, another important parameter of the Archimedean spiral is determined: the pitch. The formula for determining the pitch p of the Archimedean spiral volute is as follows: .

[0012] Preferably, the outer circumferential contours of the upper and lower volute plates are segments of an Archimedean spiral profile, the linear characteristics of which are based on the standard Archimedean spiral profile. The equation of the standard Archimedean spiral profile is as follows:

[0013] Applying this standard profile equation to the design of the inlet volute of a hot air distributor for spray drying transforms it into: .

[0014] Preferably, the outlet cone angle α1 of the hot air distributor is controlled within the range of 50-70 degrees, and the outlet cone height h1 of the hot air distributor is based on the outlet inner diameter D1 of the hot air distributor and the atomizer diameter D. 雾 The control is based on the diameter D of the volute outlet and the cone angle α1 of the hot air distributor outlet, which determines the outer diameter D2 of the hot air distributor outlet. The specific formula is as follows: .

[0015] Preferably, the outlet inner diameter D1 of the hot air distributor is further determined by calculating the inlet cross-sectional area S3 under the premise of selecting a fixed inlet air velocity V4 and inlet air flow rate Q. The specific formula is as follows: .

[0016] Preferably, the height h1 of the hot air distributor outlet cone is determined by the hot air distributor outlet inner diameter D1 and the atomizer diameter D. 雾 The control requires that the inner diameter D1 of the distributor outlet be within the atomizer diameter D. 雾 This ratio parameter is more than twice as high. Therefore, it should be controlled within the range of 1.1-2. The specific formula for calculating and back-calculating the outlet cone height of the h1 hot air distributor is as follows:

[0017] verify Whether it falls within the range of 1.1-2, and whether it meets the design standards and has a large adjustment range so that the height h1 of the hot air distributor outlet cone can be adjusted according to the tower specifications.

[0018] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention has a significant effect on solving the problems of internal flow field displacement and material adhesion to the walls caused by uneven airflow in spray drying. The uniformity, velocity, and direction of the fluid entering the drying tower can be designed and controlled according to the material properties to achieve efficient drying; at the same time, this design, coupled with the size of the drying tower, can achieve industrial-scale design. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the hot air distributor according to an embodiment of the present invention; Figure 2 This is a three-dimensional structural diagram of the hot air distributor according to an embodiment of the present invention; Figure 3 for Figure 2 Front view structural diagram; Figure 4 for Figure 3 Schematic diagram of the cross-sectional structure of AA; Figure 5 This is a schematic diagram of the dimensions of the hot air distributor according to an embodiment of the present invention.

[0020] In the diagram: 1. Upper volute plate, 2. Lower volute plate, 3. Volute side plate, 4. Volute air outlet baffle, 5. Outer side plate of air inlet, 6. Inner side plate of air inlet, 7. Cover plate, 8. Conical outer air outlet plate, 9. Conical inner air outlet plate, 10. Atomizer bonding plate, 11. Guide vane, 12. Air inlet, 13. Volute distribution area, 14. Volute air outlet, 15. Conical air outlet channel, 16. Distributor air outlet. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0022] refer to Figure 1 The hot air distributor structure shown, with a 5kg / h evaporation capacity, has the following characteristics: The hot air distributor structure is welded from 304 stainless steel, providing sufficient impact resistance, corrosion resistance, high temperature resistance, and hygiene, meeting the drying requirements of almost all materials. The outer perimeter of the upper volute plate 1 is formed by an Archimedean spiral and two parallel tangent straight lines. The inner circle is a concentric circle aligned with the center of the outer Archimedean spiral. The size of the concentric circle is consistent with the diameter of the outlet baffle 4 of the volute shell (189mm). The distance between the two parallel straight lines is consistent with the width of the inlet 12 (83mm). The lower volute plate 2 is designed identically to the upper volute plate 1. The volute shell side plate 3 is connected to the upper volute plate 1 and the lower volute plate 2, with an outer shape consistent with the outer structure of the upper volute plate 1 and a height consistent with the height of the inlet 2 (42mm). The diameter of the outlet baffle 4 of the volute shell is designed to be 0.2 times the diameter of the drying tower (944mm), and its height is determined by the cross-sectional area of ​​the outlet 14 of the volute shell. The outer side plate 5 of the air inlet is the side boundary structure of the air inlet channel. Its height is determined by the height of the air inlet 12, and its length is coupled with the diameter of the drying tower barrel, so that the air inlet 12 is located at the outer surface boundary of the drying tower barrel. The structure and dimensions of the inner side plate 6 of the air inlet are the same as those of the outer side plate 5 of the air inlet. The cover plate 7 realizes the upper space closure of the hot air volute distributor flow area 13. It is formed by generating a ring with inner and outer circles of different sizes. The inner ring size is coupled with the diameter of the circle corresponding to the atomizer position, and the outer ring is consistent with the inner side plate 6 of the air inlet and forms a closed space with it. The upper volute plate 1, the lower volute plate 2, the volute side plate 3, the volute outlet baffle 4, the outer side plate 5 of the air inlet, the inner side plate 6 of the air inlet, and the cover plate 7 are welded to form the air inlet volute structure in the hot air distributor.

[0023] The conical air outlet outer plate 8 is a conical barrel with varying diameters. The upper circular dimension is the inner diameter of the lower volute plate 2, which is welded to it. The bottom circular dimension is determined by the cross-sectional area of ​​the conical air outlet inner plate 9 and the distributor outlet 16. This structure is determined after selecting a certain cone angle of 60 degrees. The conical air outlet inner plate 9 is a conical barrel with a smaller diameter than the conical air outlet outer plate 8 and parallel to it. The smaller diameter at the bottom of this structure is determined by the maximum size of the atomizer, 70mm. The atomizer bonding plate 10 is a conical barrel with varying diameters. Its upper end is consistent with the inner ring diameter of the cover plate 7 and is welded to it. Its lower end is welded to the lower ring of the conical air outlet inner plate 9. The guide vane 11 is installed inside the conical air outlet channel 15, forming a certain angle of 30 degrees with the vertical direction. The conical outer air outlet plate 8, the conical inner air outlet plate 9, the atomizer bonding plate 10, and the guide vane 11 constitute the air outlet guiding structure in the hot air distributor.

[0024] The hot air flow rate of air inlet 12, calculated according to the spray drying specifications, is 250 m³ / h. 3 The inlet cross-sectional area is calculated based on the given inlet air velocity of 20 m / s and the length-to-width ratio of 1:2. The volute distribution area 13 is controlled by the dimensions of the inlet volute structure, with its size determined by the volute terminal flow rate accounting for 20% of the inlet air flow rate. An average flow velocity of 15 m / s is given inside the volute to determine the terminal flow cross-section, further determining the terminal cross-section length to be 22 mm, where the terminal cross-section width is consistent with the inlet 12. The volute outlet 14, with a diameter determined to be 0.2 times the diameter of the drying tower barrel, has its flow cross-sectional area calculated based on the inlet air flow rate and a given outlet air velocity of 15 m / s, thus determining the interface height. The conical outlet channel 15 is formed by the lower volute plate 2, the conical outlet outer plate 8, the conical outlet inner plate 9, and the guide vanes 11, providing velocity and direction for hot air entering the drying tower. The cross-sectional area of ​​the distributor outlet 16 is calculated based on the inlet air flow rate and the given hot air inlet velocity of 10 m / s. The structural dimensions are then determined by the size of the lower ring of the conical outlet inner plate 9. The inlet 12, the volute distribution flow area 13, the volute outlet 14, the conical outlet channel 15, and the distributor outlet 16 together constitute the internal flow area of ​​the hot air distributor.

[0025] Based on the size of this hot air distributor Figure 5 The structural dimensions of the hot air distributor shown are designed based on the combined dimensions of the internal flow velocity and the coupling tower. The diameter D of the volute outlet is the overall design origin of the hot air distributor, and its design dimension is taken from the inner diameter D of the spray drying tower. 塔 of The ratio parameter is controlled within the range of 0.2-0.4. In this example, D... 塔 =1000mm =0.2 The specific formula for calculation is as follows:

[0026] Based on the air inlet of the hot air distributor, the cross-sectional area S1 of the air inlet is calculated under the premise of a fixed air inlet velocity V1 and air inlet flow rate Q. Meanwhile, the aspect ratio of the square air inlet is... (This ratio parameter is controlled within the range of 1-2) Figure 5 The air inlet has a length of 'a' and a width of 'b'. In this example, Q = 250 m. 3 / h, V1=20 m / s, The specific formula for calculating =2 is as follows:

[0027] The termination section width d represents the radial width of the airflow after it has completed a full circle of flow through the plane coinciding with the inlet of the volute. Its dimension is determined by the principle that a portion of the inlet airflow flows through the termination section at a velocity V2 after the fluid enters the volute. This is used to determine the termination section area and further determine the termination section width d; where the portion of the flow is assumed to be a fraction of the inlet airflow. The ratio parameter is controlled within the range of 0.1-0.3. In this example, V2 = 15 m / s. =0.2 The specific formula for calculation is as follows:

[0028] The design of the outlet height h of the volute is based on the calculated outlet cross-sectional area S2, assuming a fixed flow velocity V3 and inlet airflow Q, and also on the outlet diameter D of the volute. In this example, V3 = 10 m / s, and the specific formula is as follows:

[0029] Based on the above definitions and ranges of structural design parameters, the Archimedes spiral volute of the hot air distributor is further determined, and two volute structural parameters can be derived as follows: To determine the starting position and minimum radius of rotation of the Archimedean spiral, an important parameter is the base circle radius. This design invention specifies the base circle radius D of the Archimedean spiral volute. 基 The formula is determined as follows:

[0030] To represent the distance traveled along the axis of the Archimedean spiral in one complete rotation (360° or 2π radians), and to control the tightness of the Archimedean spiral, another important parameter of the Archimedean spiral is determined: the pitch. The formula for determining the pitch p of the Archimedean spiral volute is as follows:

[0031] The hot air distributor in the spray drying invention described above exhibits a regular geometric linear geometric contour feature, but as... Figure 1 The outer circumferential contours of the upper volute plate 1 and the lower volute plate 2 shown are segments of an Archimedean spiral profile, whose linear characteristics are based on the standard Archimedean spiral features. The equation for the standard Archimedean spiral profile is as follows:

[0032] Applying this standard profile equation to the design of the inlet volute of a hot air distributor for spray drying transforms it into:

[0033] Curvature is a physical quantity that describes the degree of curvature of a curve at a point, and is numerically equal to the reciprocal of the radius of curvature of the curve at that point. (where R is the radius of curvature) Its radius of curvature formula is:

[0034] For the Archimedean spiral volute of this design invention ,in , The corresponding curvature formula is:

[0035] It can be seen that the curvature of the Archimedes spiral varies with The size increases and decreases, and the degree of curvature gradually becomes gentler, which can well match the application requirements of spray drying for the volute.

[0036] Figure 5 The α1 hot air distributor outlet cone angle and h1 hot air distributor outlet cone height are given in the figure (the angle parameter is controlled within the range of 50-70 degrees, and the height parameter is based on the hot air distributor outlet inner diameter D1 and atomizer diameter D). 雾 (Regulation) The outer diameter of the hot air distributor outlet (D2) is determined based on the diameter D of the volute outlet and the cone angle α1 of the hot air distributor outlet. In this example, α1 = 60 degrees and h1 = 50 mm. The specific formula calculation is as follows:

[0037] Figure 5 The outlet inner diameter D1 of the hot air distributor shown is further determined by calculating the inlet cross-sectional area S3 under the premise of a fixed outlet air velocity V4 and inlet air flow rate Q. The specific formula is as follows:

[0038] The height h1 of the outlet cone of the hot air distributor is determined by the inner diameter D1 of the hot air distributor outlet and the diameter D of the atomizer. 雾 The control requires that the inner diameter D1 of the distributor outlet be within the atomizer diameter D. 雾 More than twice (this ratio parameter is controlled within the range of 1.1-2). In this example, D 雾 =70 mm Therefore The specific formula for calculating and back-calculating the outlet cone height of the h1 hot air distributor is as follows:

[0039] Verified Within the range of 1.1-2, the design standard is met and there is a large adjustment space. The height h1 of the outlet cone of the hot air distributor can be adjusted according to the tower specifications.

[0040] As above Figure 1 The overall structure shown, under these hardware conditions, performs the following actions to control the uniformity of the flow field inside the drying tower.

[0041] (1) Air intake The hot air distributor's air intake operation is entirely completed within the air intake duct, which is formed by the upper volute plate 1, the lower volute plate 2, the outer side plate 5 of the air inlet, the inner side plate 6 of the air inlet, and the air inlet 12. During spray drying, the fluid, driven by a blower, heated by a heater, and after dust removal, enters the air intake duct through the air inlet 12 at a flow rate of 20 m / s. The hot air exhibits a uniform and stable flow field within the duct.

[0042] (2) Adjustment of flow field uniformity inside the volute Hot air enters the volute after passing through the inlet duct. Upon entering the volute, due to the abrupt expansion of the flow cross-section, some fluid is forced to fill the outlet 14 due to pressure relief and is discharged. Simultaneously, due to its high initial velocity, most of the flow flows along the side plate 3 of the volute. Because the volute employs an Archimedean spiral design, the radius at each point on the volute decreases uniformly along the wall. Therefore, as the fluid flows along the wall, it continuously exits from the outlet 14 as the flow cross-section decreases, until the fluid has completed a full circle along the wall. However, simply reducing the flow cross-section is insufficient to ensure uniform airflow at all points of the outlet 14. The significant pressure relief caused by the large difference in flow cross-sections upon entering the volute forces a large volume of airflow towards the outlet 14. This results in insufficient airflow at the tail end of the volute, leading to a smaller discharge rate. This uneven flow at the outlet 14 further affects the uniformity of the flow field inside the spray drying tower.

[0043] To effectively solve the above problems and achieve uniform flow at the volute outlet 14, this invention designs a compression-type volute structure. By designing a shorter volute outlet 14 height, pressure is maintained within the volute's internal flow field, reducing the amount of fluid discharged at the volute inlet. This design selects 0.2 times the drying tower diameter as the outlet diameter and a lower flow velocity, combined with the inlet air flow rate, to calculate a smaller flow cross-section. When fluid passes through this mechanism, it undergoes compression. Because the volute outlet 14 reduces fluid discharge, some fluid still remains after passing through the volute's end section. This portion of fluid re-enters the volute inlet section, counteracting the initial fluid entry and preventing premature discharge, thus forming a complete and uniform airflow circulation.

[0044] To effectively verify the uniformity of the internal flow field control by this structure, the velocities at more than 14 points at the volute outlet were experimentally measured to obtain relevant results. The velocity uniformity index was used to evaluate the airflow velocity distribution results under different simulation models, and its expression is shown in formula (1). The closer the value is to 1, the better the speed uniformity.

[0045] (1) in This represents the velocity at each point on the measured cross-section. This represents the average velocity on the measured cross section.

[0046] By monitoring speed results and Substituting the value of 15 m / s into formula (1), we get the value at the volute outlet 14. The value is 0.976, which is close to 1, indicating that the design structure effectively controls the uniformity of the flow field.

[0047] (3) Airflow regulation Hot air enters the conical outlet channel 15 after passing through the volute outlet 14. After being distributed and regulated by the volute, the flow field is evenly distributed throughout the channel. As the flow cross-section of the channel continuously narrows, the fluid accelerates within the channel, and the velocity direction of the fluid before entering the drying tower is changed by the baffles. As the velocity continuously increases, it is finally accelerated to a suitable speed at the distributor outlet 16 to dry the material droplets. Ultimately, the fluid forms a uniform and stable thermal flow field within the drying tower with appropriate velocity and direction.

[0048] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A structural design method for a variable curvature hot air distributor in a spray drying equipment, characterized in that: The housing of the hot air distributor includes an upper volute plate, a lower volute plate, a volute side plate, a volute outlet baffle, an outer air inlet plate, an inner air inlet plate, a cover plate, a conical outlet outer plate, a conical outlet inner plate, an atomizer bonding plate, and a guide vane. The above components together form the air inlet, volute distribution area, volute outlet, conical outlet channel, and distributor outlet of the hot air distributor. The hot air distributor is constructed entirely of 304 stainless steel, providing sufficient impact resistance, corrosion resistance, high-temperature resistance, and hygiene to meet the drying requirements of materials. The upper volute plate is formed by an Archimedean spiral and two parallel tangent lines on its outer perimeter, with the inner circle being a concentric circle aligned with the center of the outer Archimedean spiral. The size of the concentric circle matches the diameter of the volute's outlet baffle, and the distance between the two parallel lines matches the width of the inlet. The lower volute plate is designed identically to the upper volute plate. The volute side plate is connected to the upper and lower volute plates, its shape matching the outer structure of the upper volute plate, and its height matching the inlet height. The diameter of the volute outlet baffle is designed to be 0.2 times the diameter of the external drying tower barrel. The height is determined by the cross-sectional area of ​​the volute outlet; the outer side plate of the air inlet is the side boundary structure of the air inlet channel, the height of which is determined by the height of the air inlet, and the length is coupled with the diameter of the drying tower barrel, so that the air inlet is located at the outer surface boundary of the drying tower barrel; the structure and size of the inner side plate of the air inlet are consistent with those of the outer side plate of the air inlet; the cover plate realizes the upper space closure of the hot air distributor flow area, and forms a ring with circles of different inner and outer sizes, wherein the inner ring size is coupled with the diameter of the corresponding position of the external atomizer, and the outer ring is consistent with the inner side plate of the air inlet and forms a closed space with it; the upper volute plate, lower volute plate, volute side plate, volute outlet baffle, outer side plate of the air inlet, inner side plate of the air inlet, and cover plate are welded to form the air inlet volute structure in the hot air distributor. The conical air outlet outer plate is a conical barrel with a larger diameter at the top and a smaller diameter at the bottom. Its upper circular dimension is the same as the inner diameter of the lower volute plate and is welded to it. The bottom circular dimension is determined by the cross-sectional area of ​​the conical air outlet inner plate and the distributor's air outlet. This structure is determined after selecting a certain cone angle. The conical air outlet inner plate is a conical barrel with a smaller diameter than the conical air outlet outer plate and parallel to it. Its bottom small circular diameter is determined by the maximum size of the atomizer. The atomizer bonding plate is a conical barrel with different diameters. Its upper end is consistent with the inner ring diameter of the cover plate and is welded to it, while its lower end is welded to the lower ring of the conical air outlet inner plate. The number of guide vanes is several, evenly installed inside the conical air outlet channel, forming a certain angle with the vertical direction. The conical air outlet outer plate, conical air outlet inner plate, atomizer bonding plate, and guide vanes constitute the air outlet guiding structure in the hot air distributor. The inlet cross-sectional area is calculated based on the hot air flow rate and given inlet velocity according to the spray drying specifications. The structural dimensions are then further confirmed according to a length-to-width ratio of 1:

2. The volute distribution area is controlled by the inlet volute structure, with its size determined by the volute terminal flow rate accounting for 20% of the inlet flow rate. An average flow velocity is then given inside the volute to determine the terminal flow cross-section, further determining the terminal cross-section length. The terminal cross-section width is consistent with the inlet. The volute outlet, with a diameter determined to be 0.2 times the diameter of the drying tower, is determined by combining the inlet flow rate and... Given an outlet air velocity, the cross-sectional area of ​​the structure is further calculated to determine the interface height. The conical outlet channel is formed by a lower volute plate, a conical outlet outer plate, a conical outlet inner plate, and guide vanes, providing velocity and direction for hot air entering the drying tower. The cross-sectional area of ​​the distributor outlet is calculated based on the inlet air flow rate and the given hot air inlet velocity, and the structural dimensions are determined by the size of the lower ring of the conical outlet inner plate. The inlet, volute distribution area, volute outlet, conical outlet channel, and distributor outlet constitute the internal flow area of ​​the hot air distributor.

2. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 1, characterized in that: The diameter D of the volute air outlet is the overall design origin of the entire hot air distributor, and its design dimension is taken as the inner diameter D of the spray drying tower. 塔 of This ratio parameter is... The value should be controlled within the range of 0.2-0.4, and the specific formula is as follows: 。 3. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 2, characterized in that: Based on the air inlet of the hot air distributor, the cross-sectional area S1 of the air inlet is calculated under the premise of a fixed air inlet velocity V1 and air inlet flow rate Q. Meanwhile, the aspect ratio of the square air inlet is... The length 'a' and width 'b' of the air inlet are determined below, and this proportional parameter... The value should be controlled within the range of 1-2. The specific formula is as follows: 。 4. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 3, characterized in that: The radial width of the terminal section d, which is the area of ​​the airflow after it enters the volute and flows through a complete circle along the plane coinciding with the volute inlet, is determined by the principle of setting its size: a portion of the inlet airflow flows through the terminal section at a velocity V2 after the fluid enters the volute. This determines the area of ​​the terminal section and further determines the width d of the terminal section. Here, a portion of the flow is assumed to be a fraction of the inlet airflow. The ratio parameter is controlled within the range of 0.1-0.

3. The specific formula is as follows: 。 5. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 4, characterized in that: The height h of the volute outlet is designed based on the calculated cross-sectional area S2 of the volute outlet, assuming a fixed flow velocity V3 and an inlet airflow Q. The design is also based on the volute outlet diameter D. The specific formula is as follows: 。 6. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 5, characterized in that: Based on the above definitions and ranges of structural design parameters, the Archimedes spiral volute of the hot air distributor is further determined, and two volute structural parameters can be derived as follows: To determine the starting position and minimum radius of rotation of an Archimedean spiral, an important parameter is its base circle radius, D, which is the base circle radius of the spiral's volute. 基 The formula is determined as follows: ， To represent the distance the Archimedean spiral travels along its axis in one complete rotation and to control the tightness of the spiral, another important parameter of the Archimedean spiral is determined: the pitch. The formula for determining the pitch p of the Archimedean spiral volute is as follows: 。 7. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 6, characterized in that: The outer circumferential contours of the upper and lower volute plates are segments of an Archimedean spiral profile. Their linear characteristics are based on the standard Archimedean spiral profile, and the equation for the standard Archimedean spiral profile is as follows: ，， Applying this standard profile equation to the design of the inlet volute of a hot air distributor for spray drying transforms it into: 。 8. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 7, characterized in that: The outlet cone angle α1 of the hot air distributor is controlled within the range of 50-70 degrees. The outlet cone height h1 of the hot air distributor is based on the outlet inner diameter D1 of the hot air distributor and the atomizer diameter D. 雾 The control is based on the diameter D of the volute outlet and the cone angle α1 of the hot air distributor outlet, which determines the outer diameter D2 of the hot air distributor outlet. The specific formula is as follows: 。 9. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 8, characterized in that: The design of the outlet inner diameter D1 of the hot air distributor is further determined by calculating the inlet cross-sectional area S3 under the premise of selecting a fixed inlet air velocity V4 and inlet air flow rate Q. The specific formula is as follows: 。 10. The structural design method for a variable curvature hot air distributor in a spray drying equipment according to claim 9, characterized in that: The height h1 of the hot air distributor outlet cone is determined by the hot air distributor outlet inner diameter D1 and the atomizer diameter D. 雾 The control requires that the inner diameter D1 of the distributor outlet be within the atomizer diameter D. 雾 This ratio parameter is more than twice as high. Therefore, it should be controlled within the range of 1.1-2. The specific formula for calculating and back-calculating the outlet cone height of the h1 hot air distributor is as follows: ， verify Whether it falls within the range of 1.1-2, and whether it meets the design standards and has a large adjustment range so that the height h1 of the hot air distributor outlet cone can be adjusted according to the tower specifications.

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