Rake dryer for producing 2-chloro-4-fluorobenzoic acid

Abstract

The invention discloses a rake dryer for 2-chloro-4-fluorobenzoic acid production, and relates to the technical field of material drying, the rake dryer comprises a main body support, a drying cylinder is mounted above the main body support, a material conveying assembly is arranged in the main body support, and the material conveying assembly comprises rotating shafts symmetrically distributed in the drying cylinder; the outer walls of the rotating shafts are fixedly connected with paddle rails, the paddle rails are integrally in a continuous thread shape, and the ratio of the thread spacing at the center position of the outer wall of each rotating shaft to the thread spacing at the left and right positions of the outer wall of each rotating shaft is one to two; when materials enter the barrel, the materials are in contact with the blade tracks at close intervals in the center of the rotating shaft, dense propelling force is formed by small screw pitches, adhesive accumulation formed among the materials is forcibly broken, the materials are decomposed into dispersed material flows at the initial stage of entering the barrel, and expansion space is provided for the materials by loose track intervals. And secondary agglomeration caused by extrusion in the conveying process is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of material drying, in particular to a rake dryer for 2-chloro-4-fluorobenzoic acid production. BACKGROUND

[0002] The rake dryer for 2-chloro-4-fluorobenzoic acid production is a vacuum drying device specially used for 2-chloro-4-fluorobenzoic acid production, adopts a horizontal cylinder structure, and cooperates steam heating through a jacket and a vacuum system to uniformly heat 2-chloro-4-fluorobenzoic acid wet material in a closed environment during work. The main body of the device is made of stainless steel to resist acid corrosion, is equipped with a blast-proof motor and a nitrogen protection system, and meets the explosion-proof drying requirements of organic fluorine compounds.

[0003] However, the prior art still has the following defects in specific use: 1. The raw material input end of the existing rake dryer is arranged at the center position of the top of the cylinder. From the structural point of view, the input end is arranged at the center of the top of the cylinder, so that the material falls vertically under the action of gravity, and forms a pile shape with the falling point as the center. Although the stirring shaft is continuously running, it is limited by the structure and movement track of the stirring paddle, and cannot timely generate sufficient radial pushing force on the material in the central area in the initial stage of material falling. At the same time, the material itself has internal friction and adhesion, and after falling and piling up, a relatively stable piling structure is formed, which further hinders the stirring shaft from uniformly dispersing the material. The centralized feeding mode causes the accumulation of raw materials, so that the stirring shaft needs to spend more time and energy to break the material accumulation in the central area, prolonging the overall stirring and mixing cycle and reducing the amount of material processed per unit time. In terms of product quality, uneven distribution of raw materials in the cylinder directly causes differences in contact area and contact time between different parts of the material and the drying medium. Some materials may be over-dried, while other materials may be under-dried, resulting in uneven product quality and difficulty in meeting the process standards. From the equipment maintenance point of view, the accumulation of raw materials causes uneven stress on the stirring shaft, which is prone to deformation and bearing wear during long-term operation.

[0004] 2. Compared with existing rake dryers, the mechanical stirring method of a single stirring shaft is difficult to break the static accumulation pattern of materials in the drum. When the stirring shaft rotates, the materials can only perform limited circular motion and up-and-down tumbling under the drive of the blades. This motion not only lacks the dispersion force of the materials, but also makes it difficult for materials in different areas of the drum to be fully mixed. A large amount of materials accumulate near the stirring shaft or in the corners of the drum wall. At the same time, hot air can only rely on natural convection to contact the material surface. However, the driving force of natural convection is weak, which causes the hot air to flow slowly in the drum and is difficult to penetrate into the material accumulation layer. Furthermore, 2-chloro-4-fluorobenzoic acid is prone to agglomeration and adhesion due to the strong hydrogen bonds and polar effects of halogen atoms between molecules, which further hinders the penetration of hot air and aggravates the mass transfer resistance. On the one hand, due to insufficient contact and low renewal frequency between hot air and material particles, the heat transferred by the jacket cannot penetrate the thermal resistance layer on the material surface and cannot be effectively conducted to the interior of the material. This makes it difficult for moisture inside the material to evaporate, significantly reducing the overall drying rate, forcing a longer production cycle, and severely affecting production efficiency. On the other hand, the moisture evaporated from the material surface cannot be carried away by the hot air in time, forming a high humidity gradient on the particle surface, which in turn forms a mass transfer resistance layer. This resistance layer not only further slows down the moisture evaporation rate but also causes heat to accumulate on the material surface, resulting in excessively high local temperatures.

[0005] Therefore, in view of this, the present invention proposes a rake dryer for the production of 2-chloro-4-fluorobenzoic acid to make up for and improve the deficiencies of the prior art. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a rake dryer for the production of 2-chloro-4-fluorobenzoic acid, thereby resolving the technical issues raised in the background section.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a rake dryer for the production of 2-chloro-4-fluorobenzoic acid, comprising a main support frame, a drying cylinder mounted on the top of the main support frame, a material conveying assembly disposed inside the main support frame, the material conveying assembly comprising rotating shafts symmetrically distributed inside the drying cylinder, and paddle tracks fixedly connected to the outer walls of the rotating shafts, the paddle tracks being in a continuous thread shape, and the ratio of the thread pitch at the center position of the outer wall of the rotating shaft to the thread pitch at the left and right positions of the outer wall of the rotating shaft being 1:2.

[0008] Furthermore, an input pipe is provided at the top of the drying cylinder, and an output pipe is provided at the bottom of the drying cylinder. Both the input pipe and the output pipe are located at the center of the drying cylinder. A drive module is installed on the side of the drying cylinder. The drive module includes a drive motor. A stirring shaft is assembled at the output shaft end of the drive motor, and the stirring shaft is located at the axial center inside the drying cylinder.

[0009] Further, the outer wall of the drying cylinder is rotationally connected with a driving runner, the outer wall of the driving runner is drivingly connected with a transmission belt, the end of the transmission belt away from the driving runner is drivingly connected with a driven runner, and the driven runner is fixedly connected to the end of the different rotation shafts in a staggered form.

[0010] Further, the radius ratio of the driving runner to the driven runner is three to one, the rotation shafts are rotationally connected to the inner side wall of the drying cylinder, the rotation shafts are located above the side of the inside of the drying cylinder, and the paddle track at the center position of the outer wall of the rotation shaft corresponds to the input pipeline above the drying cylinder.

[0011] Further, the side wall of the drying cylinder is fixedly connected with a protective shell in a symmetrical manner, and the protective shell has a shape that is wider at the bottom and narrower at the top, and corresponds to the outside of the driving runner and the driven runner.

[0012] Further, the left and right sides of the outer wall of the paddle track are fixedly connected with elastic tabs, the elastic tabs are distributed in a staggered manner, and the elastic tabs as a whole have a wave shape.

[0013] Further, the stirring shaft body is composed of a central shaft and not less than four rakes, the central shaft is designed as a hollow, and the central shaft is rotationally connected with the rakes, the inside of the stirring shaft body is provided with a crushing assembly, the crushing assembly includes a solid shaft rotationally connected to the inner wall of the stirring shaft body, the outer wall of the solid shaft is fixedly connected with a weight block, the solid shaft and the weight block correspond to the center position inside the stirring shaft body, the left and right sides of the solid shaft are fixedly connected with branch shafts, the solid shaft and the branch shafts are controlled and driven by the driving motor in the driving module, and the solid shaft, the threaded shaft sleeve are fixedly connected with the rakes in the stirring shaft body.

[0014] Further, the outer wall of the branch shaft is fixedly connected with a threaded shaft sleeve, the outer wall of the threaded shaft sleeve is threadedly connected with a nut sleeve ring, the outer wall of the nut sleeve ring is fixedly connected with a counterweight piece, the threaded shaft sleeve and the nut sleeve ring form a ball screw structure, and the nut sleeve ring is located on the side close to the solid shaft in the initial state.

[0015] Further, the branch shaft and the counterweight piece are symmetrically installed with an auxiliary shaft sliding plate, and the auxiliary shaft sliding plate is slidingly connected with the branch shaft and the counterweight piece.

[0016] Further, the side wall of the counterweight piece is symmetrically fixedly connected with an inclined support plate, the outer wall of the stirring shaft body is symmetrically fixedly connected with a support seat, the inside of the support seat is slidably connected with an extension convex tooth, the outer wall of the extension convex tooth is sleeved with a return spring, the two ends of the return spring are fixedly connected with the extension convex tooth and the support seat respectively, and the extension convex tooth is located on the movement path of the inclined support plate.

[0017] Compared with the prior art, the present application has the following advantages: (1) The device is improved by setting the symmetric rotating shaft and the variable-pitch paddle track inside the drying cylinder, which solves the problem of vertical feeding accumulation in the prior art. When the material falls into the cylinder through the input pipeline, it first contacts the paddle track with close spacing at the center of the rotating shaft. The small pitch forms a dense propulsion force, which divides the concentrated material into two sides. This axial thrust using the thread forcibly breaks the adhesive accumulation between the materials, and the material is dispersed into a flow at the initial stage of entering the cylinder. As the material moves to both sides of the cylinder, the loose track spacing provides expansion space for it, avoiding secondary agglomeration caused by extrusion in the conveying process. With the continuous rotation of the rotating shaft, the material falls in the cylinder in a relatively uniform manner, laying the foundation for the subsequent drying process.

[0018] Compared with the prior art, the device changes the movement path of the material in the cylinder from simple vertical accumulation to a combined movement mode of spiral dispersion and radial diffusion. With the heat conduction effect of the cylinder jacket, the contact area between the material and the heat medium can be greatly increased, the heat transfer efficiency can be accelerated, and the drying time can be effectively shortened. In addition, the variable-pitch track can dynamically control the material flow, diffuse the material from the center dense area to the two loose areas, make the thickness distribution of the material layer in the cylinder more uniform, and better avoid the situation of insufficient or excessive drying caused by local material being too thick.

[0019] Among them, by designing the driving pulley and the driven pulley with a radius ratio of three to one, the rotating shaft can obtain three times the speed of the stirring shaft. This high-speed rotation can quickly disperse the material with stronger centrifugal force and mechanical thrust, thereby avoiding its accumulation in the rotating shaft area. In combination with the high-speed rotating paddle track, the material falling on the center of the rotating shaft is quickly thrown to both sides of the cylinder along the tangent direction, which also avoids the accumulation of material at the input point area, thereby ensuring that the material is dispersed to all parts of the cylinder at a faster speed.

[0020] (2) Especially important is that the device is introduced in the outer wall of the paddle track with elastic tab, the wave shape structure of the elastic tab produces periodic elastic deformation in rotation, through the mechanical action of elastic - rebound, broken lump material, this kind of flexible crushing method can effectively scatter the agglomerated particles, make the product granularity more uniform, purity more stable, and, staggered arrangement of the paddle when rotating, with the help of the wave surface of the flow guide, the material is thrown to the parabolic trajectory to the cylinder two sides, form the asymmetric dispersion path, this way greatly extends the material in space trajectory, makes it form a thinner dispersion layer when falling, increases the contact opportunity with the hot wall.

[0021] Wherein, when the material is completed with the continuous rotation of the rotating shaft, the paddle track will produce a certain airflow in the rotating process, the downward airflow forms a forced convection field in the cylinder, accelerates the contact update frequency of hot air and material particles, so that the heat transferred by the jacket is more efficiently conducted to the surface of the material, at the same time, the blowing effect of the airflow on the material surface can take away the evaporated moisture in time, reduce the humidity gradient of the particle surface, break the mass transfer resistance bottleneck in the drying process, in addition, the directional airflow forms a positive pressure zone at the bottom of the cylinder, which effectively suppresses the flying of fine powder material, and the scouring effect of the airflow on the cylinder wall can prevent the material from coking on the wall, especially suitable for 2-chloro-4-fluorobenzoic acid and other low melting point heat-sensitive materials.

[0022] (3) The device drives the reciprocating movement of the inclined surface support plate with the help of the solid shaft, so that the telescopic convex teeth form regular extrusion on the material, and then the stirring shaft body forms a complex effect of "stirring - extrusion", which brings multiple technical advantages: Firstly, the intermittent extrusion of telescopic convex teeth is like a miniature punch, which breaks the adhesion force inside the material with local high pressure, and further breaks the lumps, which is complementary to the traditional shear crushing, and can well solve the problem of hardening of the material in the later drying stage.

[0023] Secondly, when the telescopic convex teeth extrude the material, the material in the cylinder will be forced to change its stacking state, so that the material layer changes periodically between fluffy and compact, breaks the thermal resistance layer inside the material, and makes the heat of the jacket more smoothly conduct to the center area. With the rotation of the stirring shaft, the heat exchange effect can be significantly enhanced.

[0024] Thirdly: the extrusion of the material in the cylinder produces periodic density fluctuations, and through regular extrusion and release, the material layer constantly experiences alternating changes between fluffy and compact. This dynamic process breaks the static stacking structure of the material, so that the internal moisture can more smoothly migrate to the surface and evaporate, greatly improving the uniformity of moisture evaporation. Compared with the traditional stirring method, this design effectively avoids the dry blind area or over-drying area formed by local accumulation of the material. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a front view schematic diagram of the present application; Figure 2 It is a schematic diagram of the internal structure of the drying cylinder of the present application; Figure 3 It is a schematic diagram of the internal structure of the protective shell of the present application; Figure 4 It is a schematic diagram of the paddle track of the present application; Figure 5 It is a schematic diagram of the side view plane of the stirring shaft body and the paddle track of the present application; Figure 6 It is a schematic diagram of the crushing assembly of the present application; Figure 7 It is a schematic diagram of the internal structure of the stirring shaft body of the present application; Figure 8 It is a schematic diagram of the side view plane of the internal structure of the stirring shaft body of the present application; Figure 9 It is a schematic diagram of the telescopic protrusion of the present application; Figure 10 It is a schematic diagram of the internal structure of the support seat of the present application.

[0026] The figure reference is: 1, main support; 11, drying cylinder; 12, driving module; 13, stirring shaft body; 2, material conveying assembly; 21, driving pulley; 22, transmission belt; 23, driven pulley; 24, protective shell; 25, rotating shaft; 26, paddle track; 27, elastic tab; 3, crushing assembly; 31, solid shaft; 32, weight block; 33, branch shaft; 34, threaded shaft sleeve; 35, nut sleeve ring; 36, counterweight piece; 37, auxiliary shaft sliding plate; 38, inclined support plate; 39, telescopic protrusion; 310, support seat; 311, return spring. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application; It should be noted that the structure and working principle of the above-mentioned main support 1, drying cylinder 11, driving module 12, stirring shaft body 13 and other devices belong to the prior art, and will not be described here.

[0028] Embodiment 1 Please refer to Figures 1-10The illustrated, a 2-chloro-4-fluorobenzoic acid production with rake dryer, including main support 1, the upper portion of main support 1 is provided with drying cylinder 11, the inside of main support 1 is provided with feeding assembly 2, feeding assembly 2 includes rotating shaft 25 which is symmetrically distributed in the inside of drying cylinder 11, the outer wall of rotating shaft 25 is fixedly connected with paddle track 26, paddle track 26 is in the form of continuous thread shape as a whole, and the thread spacing at the center position of the outer wall of rotating shaft 25 is in the ratio of one to two to the thread spacing at the left and right positions of the outer wall of rotating shaft 25.

[0029] It should be noted that the upper portion of drying cylinder 11 is provided with an input pipe, the lower portion of drying cylinder 11 is provided with an output pipe, and the input pipe and the output pipe are located at the center position of drying cylinder 11, the side portion of drying cylinder 11 is provided with driving module 12, driving module 12 includes driving motor, the output shaft end of driving motor is assembled with stirring shaft body 13, and stirring shaft body 13 is located at the axial position in the inside of drying cylinder 11, the outer wall of drying cylinder 11 is rotatably connected with driving pulley 21, the outer wall of driving pulley 21 is drivingly connected with transmission belt 22, one end of transmission belt 22 away from driving pulley 21 is drivingly connected with driven pulley 23, driven pulley 23 is fixedly connected to the end position of different rotating shaft 25 in the form of staggered, the radius ratio of driving pulley 21 to driven pulley 23 is three to one, rotating shaft 25 is rotatably connected to the inner side wall of drying cylinder 11, rotating shaft 25 is located at the upper side in the inside of drying cylinder 11, and the paddle track 26 at the center position of the outer wall of rotating shaft 25 corresponds to the input pipe above drying cylinder 11, the side wall of drying cylinder 11 is symmetrically fixedly connected with protective shell 24, protective shell 24 is in the shape of wide below and narrow above, which is adapted to correspond to the outside of driving pulley 21 and driven pulley 23, the left and right sides of the outer wall of paddle track 26 are fixedly connected with elastic tab 27, elastic tab 27 is staggered, and elastic tab 27 is in the shape of wave as a whole.

[0030] Specifically, after the driving motor is started, the output shaft cooperates with other components to drive stirring shaft body 13 to rotate at the axial position of drying cylinder 11, driving pulley 21 located at the outer wall of drying cylinder 11 is connected with the power output shaft end of driving motor and the branch shaft 33 in the inside of stirring shaft body 13 respectively, so when the driving motor starts to run, driving pulley 21 rotates synchronously with the output shaft end.

[0031] Driving pulley 21 drives driven pulley 23 to rotate through transmission belt 22, the radius ratio of driving pulley 21 to driven pulley 23 is three to one, so a speed reduction transmission is formed between them, so that driven pulley 23 rotates with higher torque, since driven pulley 23 is fixed at the end of different rotating shaft 25 in the form of staggered, the symmetrically distributed rotating shaft 25 will rotate synchronously under the drive of driven pulley 23.

[0032] The material enters the cylinder through the input pipe at the center position above the drying cylinder 11. At this time, the rotating shaft 25 has started to rotate, and the threaded structure at the center position of the paddle track 26 first contacts the material below the input pipe. The material is dispersed to both sides through intensive stirring. Since the paddle track 26 on the outer wall of the rotating shaft 25 is a continuous threaded structure, and the thread spacing at the center position is twice that at the left and right positions, when the rotating shaft 25 rotates under the drive of the driven pulley 23, the threaded paddle track 26 will form a spiral propulsion force. Due to the inconsistent density ratio of the paddle track 26, there is a difference in conveying between the center position and the two side positions of the paddle track 26. The center thread spacing is smaller, the pushing speed of the material is slower during rotation, but the stirring is more intensive. The thread spacing on the left and right sides is larger, and the pushing speed is faster, forming a differentiated effect of "slow stirring at the center and fast conveying on both sides".

[0033] During the conveying of the material, since the wave-shaped elastic prongs 27 are fixed on the left and right sides of the outer wall of the paddle track 26 in an interlaced manner, when the rotating shaft 25 rotates, the elastic prongs 27 move synchronously with the paddle track 26. When the elastic prongs 27 pass through the material, the deformation and reset of the wave-shaped edge produce a tearing and overturning effect on the material, breaking the material clumps and enhancing the uniformity of drying.

[0034] Based on the embodiments, please refer to Figures 1-10As shown, the stirring shaft body 13 is composed of a central shaft and no less than four rakes, the central shaft is hollow, and the central shaft is rotatably connected with the rakes. The stirring shaft body 13 is internally provided with a crushing assembly 3. The crushing assembly 3 includes a solid shaft 31 rotatably connected to the inner wall of the stirring shaft body 13. The outer wall of the solid shaft 31 is fixedly connected with a weight block 32. The solid shaft 31 and the weight block 32 are both located at the central position of the stirring shaft body 13. Two branch shafts 33 are symmetrically fixedly connected to the two sides of the solid shaft 31. The solid shaft 31 and the branch shafts 33 are both controlled and driven by the driving motor in the driving module 12. The solid shaft 31 and the threaded shaft sleeves 34 are both fixedly connected with the rakes in the stirring shaft body 13. The outer wall of each branch shaft 33 is fixedly connected with a threaded shaft sleeve 34. The outer wall of each threaded shaft sleeve 34 is threadedly connected with a nut sleeve ring 35. The outer wall of each nut sleeve ring 35 is fixedly connected with a counterweight plate 36. A ball screw structure is formed between the threaded shaft sleeve 34 and the nut sleeve ring 35, and the nut sleeve ring 35 is located on the side close to the solid shaft 31 in the initial state. An auxiliary shaft sliding plate 37 is symmetrically installed between the branch shaft 33 and the counterweight plate 36. The auxiliary shaft sliding plate 37 is slidably connected with the branch shaft 33 and the counterweight plate 36. The side wall of the counterweight plate 36 is symmetrically fixedly connected with an inclined surface support plate 38. The outer wall of the stirring shaft body 13 is symmetrically fixedly connected with a support seat 310. The inside of the support seat 310 is slidably connected with an extension convex tooth 39. The outer wall of the extension convex tooth 39 is sleeved with a return spring 311. The two ends of the return spring 311 are fixedly connected with the extension convex tooth 39 and the support seat 310, respectively. The extension convex tooth 39 is located on the movement path of the inclined surface support plate 38.

[0035] Specifically, the driving motor controls the rotation of the solid shaft 31 and the branch shaft 33. The solid shaft 31 is located at the center of the stirring shaft body 13, and the branch shafts 33 are symmetrically distributed on both sides. In the initial state, the nut sleeve ring 35 is located on the side of the threaded shaft sleeve 34 close to the solid shaft 31. The counterweight plate 36 is slidably connected with the branch shaft 33 through the auxiliary shaft sliding plate 37. At this time, the counterweight plate 36 is close to the center, and the centrifugal force is small. The extension convex tooth 39 is retracted in the support seat 310 under the action of the return spring 311, and is located on the movement path of the inclined surface support plate 38 and is not extruded by external force.

[0036] After the drive motor starts, the solid shaft 31 drives the counterweight 32 to rotate, generating an initial centrifugal force, which enhances the stability and stirring force of the stirring shaft 13. The branch shaft 33 rotates synchronously, driving the threaded bushing 34 to rotate. Since the threaded bushing 34 and the nut collar 35 form a ball screw structure, the nut collar 35 will move axially along the threaded bushing 34 when rotating. When the threaded bushing 34 rotates, the nut collar 35 moves from the side closest to the solid shaft 31 to the end of the branch shaft 33 under the action of the ball screw, while the counterweight 36 moves outward synchronously with the nut collar 35. The attached shaft slide plate 37 slides between the branch shaft 33 and the counterweight 36 to ensure smooth movement of the counterweight 36. After the counterweight 36 moves outward, the center of gravity inside the stirring shaft 13 changes, which allows the stirring shaft 13 to generate radial stirring forces of different intensities at different positions as the counterweight 36 moves, thus enhancing the shearing and crushing effect on the material.

[0037] During the outward movement of the counterweight plate 36, the inclined support plate 38 on the side wall gradually contacts and squeezes the inclined surface of the telescopic tooth 39. After being squeezed, the telescopic tooth 39 overcomes the resistance of the return spring 311 and slides outward to the support seat 310 until the inclined support plate 38 completely passes the tooth. As the branch shaft 33 continues to rotate, the nut collar 35 moves back along the outer wall of the threaded bushing 34. During the process of the inclined support plate 38 disengaging from the telescopic tooth 39, the telescopic tooth 39 is reset under the action of the return spring 311 and retracts into the support seat 310 again, forming a periodic "squeeze-reset" action. Through the intermittent squeezing of the telescopic tooth 39, the adhesion force inside the material is broken through with local high pressure, and the agglomerates are decomposed into finer pieces, thereby solving the problem of material agglomeration and hardening in the later stage of drying.

[0038] 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 rake dryer for the production of 2-chloro-4-fluorobenzoic acid, comprising a main support (1), wherein a drying cylinder (11) is mounted above the main support (1), characterized in that: The main support (1) is provided with a material conveying assembly (2). The material conveying assembly (2) includes rotating shafts (25) symmetrically distributed inside the drying cylinder (11). The outer walls of the rotating shafts (25) are fixedly connected with blade tracks (26). The blade tracks (26) are in a continuous thread shape. The ratio of the thread pitch at the center of the outer wall of the rotating shaft (25) to the thread pitch at the left and right positions of the outer wall of the rotating shaft (25) is 1:

2.

2. The rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 1, characterized in that: An input pipe is provided above the drying cylinder (11), and an output pipe is provided below the drying cylinder (11). Both the input pipe and the output pipe are located at the center of the drying cylinder (11). A drive module (12) is installed on the side of the drying cylinder (11). The drive module (12) includes a drive motor. A stirring shaft (13) is assembled at the output shaft end of the drive motor. The stirring shaft (13) is located at the axial center inside the drying cylinder (11).

3. The rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 1, characterized in that: The outer wall of the drying cylinder (11) is rotatably connected to a drive wheel (21), and the outer wall of the drive wheel (21) is driven by a drive belt (22). The end of the drive belt (22) away from the drive wheel (21) is driven by a driven wheel (23). The driven wheels (23) are fixedly connected to the ends of different rotating shafts (25) in an alternating manner.

4. A rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 3, characterized in that: The radius ratio of the active rotor (21) to the driven rotor (23) is three to one. The rotating shafts (25) are all rotatably connected to the inner wall of the drying cylinder (11). The rotating shafts (25) are located on the upper side inside the drying cylinder (11), and the paddle track (26) at the center of the outer wall of the rotating shaft (25) corresponds to the input pipe above the drying cylinder (11).

5. A rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 1, characterized in that: The side wall of the drying cylinder (11) is symmetrically fixedly connected with a protective shell (24), and the protective shell (24) is wider at the bottom and narrower at the top, which is adapted to be located outside the driving wheel (21) and the driven wheel (23).

6. A rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 1, characterized in that: Elastic paddles (27) are fixedly connected to both sides of the outer wall of the blade track (26). The elastic paddles (27) are staggered and the elastic paddles (27) are wavy in shape.

7. A rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 2, characterized in that: The stirring shaft (13) is composed of a central shaft and at least four rake teeth. The central shaft is hollow and is rotatably connected to the rake teeth. The stirring shaft (13) is equipped with a crushing component (3). The crushing component (3) includes a solid shaft (31) rotatably connected to the inner wall of the stirring shaft (13). A weight block (32) is fixedly connected to the outer wall of the solid shaft (31). The solid shaft (31) and the weight block (32) are both located at the center of the stirring shaft (13). Branch shafts (33) are symmetrically fixedly connected to both sides of the solid shaft (31). The solid shaft (31) and the branch shafts (33) are both driven by the drive motor in the drive module (12). The solid shaft (31) and the threaded bushing (34) are fixedly connected to the rake teeth in the stirring shaft (13).

8. A rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 7, characterized in that: The outer wall of each branch shaft (33) is fixedly connected with a threaded bushing (34), the outer wall of each threaded bushing (34) is threadedly connected with a nut collar (35), the outer wall of each nut collar (35) is fixedly connected with a counterweight plate (36), the threaded bushing (34) and the nut collar (35) form a ball screw structure, and the nut collar (35) is initially located on the side close to the solid shaft (31).

9. A rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 7, characterized in that: A secondary shaft sliding plate (37) is symmetrically installed between the branch shaft (33) and the counterweight plate (36), and the secondary shaft sliding plate (37) is slidably connected to the branch shaft (33) and the counterweight plate (36).

10. A rake dryer for the production of 2-chloro-4-fluorobenzoic acid according to claim 8, characterized in that: The counterweight plate (36) is symmetrically fixedly connected to the side wall of the inclined plate (38), and the outer wall of the stirring shaft (13) is symmetrically fixedly connected to the support seat (310). The support seat (310) is slidably connected to the inside of each telescopic tooth (39). The outer wall of each telescopic tooth (39) is sleeved with a return spring (311). The two ends of the return spring (311) are fixedly connected to the telescopic tooth (39) and the support seat (310) respectively, and the telescopic tooth (39) is located on the movement path of the inclined plate (38).

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