Crystallization device for tetrachlorophthalic anhydride production

Abstract

The invention relates to the field of tetrachlorophthalic anhydride crystallization, in particular to a crystallization device for tetrachlorophthalic anhydride production, which comprises a machine body, the top end of the machine body is fixedly connected with a driving motor, the machine body is internally provided with a driving cleaning mechanism, and the driving cleaning mechanism is provided with a relative linkage mechanism. Through mechanical coupling of the unique driving cleaning mechanism and the multifunctional stirring mechanism, under driving of a single driving motor, powerful mixing of materials and continuous cleaning of a device wall are synchronously completed, a first scraper and a second scraper are attached to the inner wall in a self-adaptive mode under the action of centrifugal force, crystal deposition is effectively removed online, and the service life of the device is prolonged. The high-efficiency heat exchange state of a heat transfer surface is maintained, and cooling efficiency attenuation and process fluctuation caused by scaling are avoided, so that the necessary periodic shutdown kettle cleaning link in the traditional process is fundamentally reduced, the annual effective operation time of the device is greatly prolonged, the maintenance cost and the energy consumption are reduced, and stable, continuous and high-efficiency production is realized.

Description

Technical Field

[0001] This invention relates to the field of tetrachlorophthalic anhydride crystallization, specifically to a crystallization apparatus for the production of tetrachlorophthalic anhydride. Background Technology

[0002] In the industrial production of tetrachlorophthalic anhydride, crystallization is a key unit operation that determines the purity, crystal form, and particle size distribution of the final product. This process relies on precise control of the solution supersaturation, and uniform mixing and efficient heat transfer are fundamental to achieving this control. Currently, the industry commonly uses crystallizers equipped with stirring systems. Traditional stirrers, such as paddle and anchor stirrers, mainly generate unidirectional tangential or axial flow through rotation. Their mixing capacity is limited, and they easily form fluid "dead zones" within the vessel, leading to uneven local supersaturation. As a result, crystal nucleation and growth become uncontrollable, easily producing crystal clusters and agglomeration, or resulting in an excessively wide crystal particle size distribution, seriously affecting the subsequent filtration, washing process performance, and final quality of the product.

[0003] In addition, the crystallization process of tetrachlorophthalic anhydride easily forms a stubborn crystalline layer on the heat exchange wall, which significantly reduces heat transfer efficiency, makes temperature control difficult, and deteriorates process stability. On the other hand, regular manual or chemical cleaning operations not only increase labor intensity and production costs, but also lead to production interruptions and affect continuous operation. To solve the scaling problem, some improvement solutions have added scrapers to the stirring shaft. However, simple fixed or rigidly connected scrapers often cannot completely adhere to the slight unevenness of the wall surface caused by manufacturing or thermal deformation, resulting in incomplete cleaning and potential damage to the equipment due to excessive friction.

[0004] Therefore, the industry has long desired an integrated solution that not only achieves true three-dimensional, all-around, high-intensity mixing of materials within the crystallizer, eliminating temperature and concentration gradients, but also synchronously and adaptively cleans the vessel walls during operation, maintaining long-term, efficient heat transfer. In existing technologies, stirring and cleaning functions often rely on independent drives or simple mechanical connections, resulting in complex structures, high energy consumption, and difficulty in coordinating the two actions to achieve synergistic effects. Developing a compact crystallization device that can simultaneously achieve efficient mixing and self-cleaning through a single power source is of clear practical significance for improving the production quality and efficiency of tetrachlorophthalic anhydride and similar fine chemicals. Summary of the Invention

[0005] The purpose of this invention is to provide a crystallization apparatus for the production of tetrachlorophthalic anhydride, thereby solving the problems mentioned in the background art. To achieve the above objective, this invention provides the following technical solution: a crystallization apparatus for the production of tetrachlorophthalic anhydride, comprising a body, a drive motor fixedly connected to the top of the body, a drive cleaning mechanism installed inside the body, a relative linkage mechanism provided on the drive cleaning mechanism, a multi-functional stirring mechanism installed between the drive cleaning mechanism and the relative linkage mechanism, and a discharge port provided at the bottom of the body.

[0006] Preferably, the drive cleaning mechanism includes a fixed limiting ring, which is fixedly connected to the inside of the machine body. A drive rod is fixedly connected to the lower end of the drive motor drive shaft. An L-shaped stirring rod is fixedly connected to the bottom of the drive rod. Three L-shaped stirring rods are arranged around the lower circumference of the drive rod. A scraper is hinged to the side of the L-shaped stirring rod. The scraper is positioned at the top, middle, and bottom of the three L-shaped stirring rods to ensure that it covers the entire inner wall of the machine body. A scraper is hinged to the lower end of the L-shaped stirring rod. Similarly, the scraper is positioned at the left, middle, and right of the bottom of the L-shaped stirring rod to ensure that it covers the entire bottom. A groove is formed on the surface of the L-shaped stirring rod.

[0007] Preferably, the relative linkage mechanism includes a support rod, which is fixedly connected to the surface of the fixed limiting ring. A hollow roller is fixedly connected to the lower end of the support rod. A drive rod passes through the hollow roller and is rotatably connected inside the hollow roller. A reciprocating groove is formed on the surface of the hollow roller, and a rotating ring is slidably connected inside the reciprocating groove. The rotating ring is rotatably connected to the surface of the hollow roller.

[0008] Preferably, the multifunctional stirring mechanism includes a connecting rod hinged to the surface of a rotating ring. Three sets of connecting rods are arranged circumferentially on the surface of the rotating ring. A sliding rod is rotatably connected to the side of each connecting rod. A spring tube is sleeved on the surface of the sliding rod, allowing the sliding rod to rotate inside the spring tube. A slider is fixedly connected to one end of the spring tube, and the slider slides within a groove. A connecting V-groove is formed inside the sliding rod. An elastic stirring rod is slidably connected to the surface of the spring tube. A pull wheel is fixedly connected to the end of the sliding rod near the connecting rod. U-shaped pull bars are slidably connected to the upper and lower ends of the hollow roller. The U-shaped pull bars penetrate the hollow end of the connecting rod and engage with the pull wheel. The U-shaped pull bars are fixedly connected to a fixed limiting ring via a bracket to ensure their stationary state.

[0009] Preferably, when the drive rod rotates, it drives the L-shaped stirring rod to rotate. The L-shaped stirring rod drives the slider and the spring tube to rotate through the slide groove. The spring tube drives the connecting rod and the rotating ring to move up and down in the reciprocating groove on the surface of the hollow roller through the slide rod. At the same time, it drives the slide rod to rotate through the pull wheel rolling on the U-shaped pull bar.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: In this invention, through the mechanical coupling of a unique drive cleaning mechanism and a multi-functional stirring mechanism, powerful mixing of materials and continuous cleaning of the vessel wall are simultaneously achieved under the drive of a single motor. Scraper 1 and Scraper 2 adaptively adhere to the inner wall under centrifugal force, effectively removing crystalline deposits online and maintaining the high-efficiency heat exchange state of the heat transfer surface. This avoids cooling efficiency degradation and process fluctuations caused by scaling. This fundamentally reduces the periodic shutdown and vessel cleaning required in traditional processes, significantly increases the annual effective operating time of the equipment, reduces maintenance costs and energy consumption, and achieves stable, continuous, and efficient production.

[0011] In this invention, rotational motion is converted into reciprocating motion through a relative linkage mechanism and transmitted to a multifunctional stirring mechanism. This causes the elastic stirring rod to simultaneously undergo a composite motion of revolution, lifting and lowering, and oscillation. This motion mode generates strong three-dimensional unsteady turbulence in the crystallization vessel, completely eliminating dead zones in mixing and mass transfer, and ensuring extreme uniformity of the temperature and concentration fields. As a result, the generation of crystal nuclei and the growth of crystals are more uniform and controllable in space and time, effectively suppressing the formation of crystal clusters and agglomerates. Ultimately, a tetrachlorophthalic anhydride product with concentrated particle size distribution, regular crystal shape, and higher purity is obtained, improving the product's filterability and subsequent processing performance.

[0012] In this invention, multiple functions, including basic mixing, wall cleaning, three-dimensional mixing, and localized shearing, are integrated into a compact mechanical linkage system driven by a single motor. Precise power transmission and motion conversion between mechanisms are achieved through structures such as chutes, reciprocating channels, and U-shaped tie rods, resulting in coordinated movements without additional independent drive units. This integrated design not only simplifies the equipment structure and reduces manufacturing costs and potential failure points, but also avoids interference and energy consumption accumulation issues that may arise from multiple power sources. This makes the system more reliable, energy utilization more concentrated and efficient, and the overall energy efficiency ratio significantly improved. Attached Figure Description

[0013] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 This is a schematic diagram of the side cross-sectional structure of the present invention; Figure 3 This is a schematic diagram of the internal structure of the body of the present invention; Figure 4 This is a schematic diagram showing the connection relationship between the scraper and the stirring rod in the driving cleaning mechanism of the present invention; Figure 5 This is a schematic diagram of the relative linkage mechanism structure of the present invention; Figure 6 This is a schematic diagram of the multifunctional stirring mechanism of the present invention; Figure 7 This is a side cross-sectional view of the multifunctional stirring mechanism of the present invention; Figure 8 This is a schematic diagram of the side cross-sectional structure of the slide bar of the present invention; Figure 9 This is a partially enlarged structural diagram of the multifunctional stirring mechanism of the present invention.

[0014] In the diagram: 1. Machine body; 2. Drive motor; 3. Drive cleaning mechanism; 4. Relative linkage mechanism; 5. Multifunctional stirring mechanism; 31. Fixed limit ring; 32. Drive rod; 33. Biased L-shaped stirring rod; 34. Scraper 1; 35. Scraper 2; 36. Slide groove; 41. Support rod; 42. Hollow roller; 43. Reciprocating groove; 44. Rotating ring; 51. Connecting rod; 52. Slide rod; 53. Bourdon tube; 54. Slider; 55. Connecting V-groove; 56. Elastic stirring rod; 57. Pulling wheel; 58. U-shaped pull bar. Detailed Implementation

[0015] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0016] Please see Figures 1 to 9 The present invention provides a technical solution: a crystallization device for the production of tetrachlorophthalic anhydride, comprising a body 1, a drive motor 2 fixedly connected to the top of the body 1, a drive cleaning mechanism 3 installed inside the body 1, a relative linkage mechanism 4 provided on the drive cleaning mechanism 3, a multi-functional stirring mechanism 5 installed between the drive cleaning mechanism 3 and the relative linkage mechanism 4, and a discharge port provided at the bottom of the body 1.

[0017] Specifically, at the start of the crystallization process, a solution containing tetrachlorophthalic anhydride is injected into the machine body 1. The drive motor 2 is activated, and its drive shaft rotates the entire drive cleaning mechanism 3, which is the core power source of the device. The drive cleaning mechanism 3 not only handles basic stirring but also, through its unique structural design, transmits power to the relative linkage mechanism 4 and the multi-functional stirring mechanism 5, thereby triggering a series of complex relative movements and linkage effects. This achieves comprehensive, multi-mode mixing and cleaning functions driven by a single power source. Through precise coupling between the various mechanisms, this device effectively solves problems such as mixing dead zones, uneven crystallization particles, and severe scaling on the walls and bottom of traditional crystallizers, significantly improving the purity, particle size uniformity, and production efficiency of the crystallized product.

[0018] The drive cleaning mechanism 3 includes a fixed limiting ring 31, which is fixedly connected to the inner wall of the machine body 1 to provide stable internal support and positioning reference. The lower end of the drive shaft of the drive motor 2 passes through the top of the machine body 1 and is connected to it through a sealed bearing. A drive rod 32 is fixedly connected to its end. An L-shaped stirring rod 33 is fixedly connected to the bottom of the drive rod 32. Three L-shaped stirring rods 33 are evenly arranged along the circumference at the lower end of the drive rod 32, forming a basic stirring frame. Each L-shaped stirring rod 33 has a scraper 34 hinged to its upper, middle, and lower sides, so that the three sets of scrapers 34 can cover the entire cylindrical inner wall of the machine body 1 in the vertical direction. Meanwhile, at the lower end of each of the biased L-shaped stirring rods 33, scraper blades 35 are respectively hinged at three positions on the left, middle and right along the horizontal direction to ensure that the arc-shaped bottom of the machine body 1 can be fully covered. Under the combined action of centrifugal force, fluid resistance and their hinged structure, scraper blades 34 and 35 can adaptively slide close to the inner wall and bottom curved surface of the machine body 1, thereby continuously scraping off the attached or deposited crystalline materials during the stirring process, preventing the formation of hard scale layer, ensuring efficient heat transfer and a clean production environment. The surface of the biased L-shaped stirring rod 33 is provided with a sliding groove 36 along its length direction for sliding cooperation with the multi-functional stirring mechanism 5.

[0019] The relative linkage mechanism 4 includes a support rod 41, which is fixedly connected to the lower surface of the fixed limiting ring 31. A hollow roller 42 is fixedly connected to the lower end of the support rod 41. A drive rod 32 coaxially passes through the hollow roller 42 and is rotatably connected to the inner wall of the hollow roller 42 through a bearing, so that the drive rod 32 can rotate independently of the hollow roller 42. A spiral reciprocating groove 43 is formed on the surface of the hollow roller 42. A rotating ring 44 is slidably connected inside the reciprocating groove 43. The rotating ring 44 is also sleeved on the outer surface of the hollow roller 42 and is rotatably connected to it through another set of bearings. The core function of this mechanism is to transform the single rotational motion of the drive rod 32 into a regular reciprocating motion of the rotating ring 44 relative to the hollow roller 42 along its axis. Specifically, when the drive rod 32 rotates, it drives the rotating ring 44 to rotate through the connecting component (described later) in the multi-functional stirring mechanism 5. Since the rotating ring 44 is restricted to sliding within the spiral reciprocating groove 43, its own rotational motion is forced to be converted into up-and-down reciprocating movement along the surface of the hollow roller 42. This ingenious motion conversion is the key to achieving three-dimensional stirring in this device.

[0020] The multifunctional stirring mechanism 5 includes three sets of connecting rods 51, which are uniformly hinged to the outer surface of the rotating ring 44 along the circumferential direction. A slide rod 52 is rotatably connected to the end of each connecting rod 51 away from the rotating ring 44. A spring tube 53 is slidably sleeved on the surface of the slide rod 52, and the end of the slide rod 52 can rotate within a limited range inside the spring tube 53. A slider 54 is fixedly connected to one end of the spring tube 53, and the slider 54 is adaptedly embedded in the groove 36 on the surface of the L-shaped stirring rod 33 and can slide along it. The slide rod 52 has a communicating V-shaped groove 55 axially formed inside. Multiple elastic stirring rods 56 are slidably sleeved on the surface of the spring tube 53 along its length. The root of the elastic stirring rod 56 extends into the interior of the spring tube 53 and slidably engages with the communicating V-shaped groove 55 on the slide rod 52. A pull wheel 57 is fixedly connected to one end of the slide rod 52 near the connecting rod 51. U-shaped pull bars 58 are symmetrically slidably connected to the upper and lower ends of the hollow roller 42. The U-shaped pull bars 58 penetrate the hollow end of the connecting rod 51 and mesh with the pull wheel 57.

[0021] The working process and beneficial effects of this mechanism are as follows: When the drive rod 32 rotates, it first drives the L-shaped stirring rod 33 to revolve, achieving basic horizontal circular stirring. Simultaneously, the L-shaped stirring rod 33, through its groove 36, drives the slider 54 and the fixed spring tube 53 to revolve together. The spring tube 53, in turn, drives the connecting rod 51 through the slide rod 52, thereby driving the rotating ring 44 to rotate. Due to the action of the relative linkage mechanism 4, the rotation of the rotating ring 44 is converted into a reciprocating motion. This reciprocating motion is transmitted in the opposite direction to the slide rod 52 and the spring tube 53 through the connecting rod 51, causing the latter to simultaneously revolve and slide up and down within the groove 36 while revolving. This complex motion makes the movement trajectory of the elastic stirring rod 56 fixed on the spring tube 53 within the body 1 extremely complex. It has both horizontal circular motion and vertical lifting motion, and can also generate slight radial oscillation through the elastic deformation of the spring tube 53, thereby forming strong three-dimensional turbulence in the crystallization solution, completely breaking the gradient of the temperature field and concentration field, and promoting the uniform generation of crystal nuclei and the uniform growth of crystals.

[0022] Secondly, during the reciprocating motion of the slide rod 52 with the connecting rod 51, the pull wheel 57 fixed on it rolls along the stationary U-shaped pull bar 58. Due to the meshing action, the rolling of the pull wheel 57 is converted into the periodic forward and reverse rotation of the slide rod 52 in the spring tube 53. The rotation of the slide rod 52 is transmitted to the root of each elastic stirring rod 56 through the internal connecting V-shaped groove 55, driving all elastic stirring rods 56 to swing synchronously around the axis of the spring tube 53. This oscillating stirring further enhances the shear force and renewal rate of the local fluid, which is particularly helpful in preventing crystals from agglomerating and growing on the surface of the stirring element, and can keep the fine crystals in a suspended state, avoiding premature deposition at the bottom.

[0023] In summary, this invention, through a single power input from the drive motor 2, and the synergistic action of the drive cleaning mechanism 3, the relative linkage mechanism 4, and the multi-functional stirring mechanism 5, ultimately transforms into: 1) an adaptive wall-scraping cleaning action covering the entire inner wall and bottom (executed by scraper 1 34 and scraper 2 35); 2) basic horizontal swirling stirring (executed by the biased L-shaped stirring rod 33); 3) three-dimensional reciprocating-rotational composite stirring (executed by the revolution and lifting of the spring tube 53 and the elastic stirring rod 56); and 4) enhanced local shearing oscillating stirring (executed by the oscillation of the elastic stirring rod 56). These four action modes are performed simultaneously, in the same machine, and in coordination, achieving thorough mixing and continuous cleaning of the material in the crystallization vessel without dead angles. This ensures the high efficiency, uniformity, and stability of the crystallization process, ultimately obtaining a tetrachlorophthalic anhydride crystal product with concentrated particle size distribution and high purity, while greatly reducing the cost of vessel cleaning and maintenance and energy consumption.

[0024] The method of use and advantages of the present invention: The working process of this crystallization apparatus for the production of tetrachlorophthalic anhydride is as follows: like Figures 1 to 9 As shown.

[0025] In use, the operation of this tetrachlorophthalic anhydride crystallization device begins with the start of the drive motor 2. When the motor is running, its power core—the drive rod 32—starts to rotate, directly driving the three biased L-shaped stirring rods 33 fixed at its lower end to perform basic circular motion, which is the first basic layer of mixing.

[0026] The key point is that this system is far more than just simple stirring. While the L-shaped stirring rod 33 rotates, the scraper blades 34 (hinged at the top, middle, and bottom) and the scraper blade 35 (at the bottom) adaptively adhere to the inner wall and bottom curved surface of the machine body 1, aided by centrifugal force and material resistance. This allows the device to simultaneously and continuously scrape and clean the surface of the machine body 1 from the very beginning of stirring, effectively preventing tetrachlorophthalic anhydride crystals from forming scale on the heat transfer surface and ensuring stable heat exchange efficiency during crystallization. This is its first significant advantage: "stirring is cleaning," solving the pain point of traditional crystallizers requiring frequent shutdowns for cleaning.

[0027] A more ingenious linkage occurs inside the device. The rotation of the drive rod 32, through the sliding of the slider 54 in the groove 36, transmits power to the spring tube 53 and the slide rod 52, which in turn pushes the connecting rod 51 to drive the rotating ring 44 to rotate. Since the rotating ring 44 is confined to the spiral reciprocating groove 43 on the surface of the hollow roller 42, its rotation is cleverly transformed into a regular up-and-down reciprocating motion.

[0028] This reciprocating motion is transmitted in the opposite direction through the connecting rod 51, causing the entire multi-functional stirring mechanism 5—especially the spring tube 53 and the multiple elastic stirring rods 56 slidably sleeved on it—to undergo vertical lifting motion while revolving. The elastic stirring rods 56 thus follow a complex three-dimensional spatial trajectory, creating strong three-dimensional turbulence in the crystallizing liquid. This multi-directional, dead-angle-free mixing completely breaks down temperature and concentration gradients, greatly promoting the uniform generation of crystal nuclei and the regular growth of crystals, thereby improving the uniformity and purity of the product crystallization.

[0029] Meanwhile, as the slide bar 52 moves up and down, the pull wheel 57 at its end rolls along the fixed U-shaped pull bar 58 and rotates. This rotation drives all the elastic stirring rods 56 to swing synchronously through the connecting V-shaped groove 55 inside the slide bar 52. This swinging is like countless flexible "little fingers", which produces additional gentle shearing and disturbance to the material. Its advantage is that it can effectively disperse any possible crystal clusters and prevent crystals from adhering and growing on the stirring parts, while also avoiding excessive mechanical damage to the already formed complete crystals. It is particularly suitable for precision crystallization processes that require control of crystal particle size.

[0030] In summary, this device, through a sophisticated mechanical linkage design, uses only one drive motor 2 to simultaneously drive four major functional actions: basic swirling stirring, adaptive wall scraping, three-dimensional lifting disturbance, and localized flexible shearing. All these actions work in tandem to create a crystallization environment characterized by extremely thorough mixing, uniform temperature and concentration, and no risk of scaling. The resulting comprehensive benefits are obvious: it not only significantly improves the crystallization efficiency of tetrachlorophthalic anhydride and the product quality, resulting in more uniform particle size and higher purity, but also greatly reduces energy consumption and production interruptions caused by cleaning and maintenance, achieving efficient, stable, and low-maintenance continuous production.

[0031] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A crystallization device for producing tetrachlorophthalic anhydride, comprising a machine body (1) and a driving motor (2) arranged at the top of the machine body, characterized in that: The machine body (1) is internally provided with: A driving cleaning mechanism (3) directly driven by the driving motor (2) for performing basic stirring and wall cleaning; A relative linkage mechanism (4) provided on one side of the driving cleaning mechanism (3); and A multifunctional stirring mechanism (5) connected between the driving cleaning mechanism (3) and the relative linkage mechanism (4); Wherein, the output of the driving motor (2) is transmitted through the driving cleaning mechanism (3) and acts on the relative linkage mechanism (4) through the multifunctional stirring mechanism (5), so that the multifunctional stirring mechanism (5) generates a compound motion relative to the driving cleaning mechanism (3), thereby realizing multidirectional mixing and synchronous cleaning of crystalline materials.

2. The crystallization apparatus for producing tetrachlorophthalic anhydride according to claim 1, characterized by: The driving cleaning mechanism (3) includes a fixed limiting ring (31) fixed to the inner wall of the machine body (1), a driving rod (32) connected with the output shaft of the driving motor (2), and three deflection L-shaped stirring rods (33) circumferentially distributed at the lower end of the driving rod (32); The side surface and the lower end of the deflection L-shaped stirring rod (33) are respectively provided with a plurality of scraping plates (34) and (35) which can be self-adapted to the inner wall and the bottom surface of the machine body (1) through a hinged manner.

3. The crystallization apparatus for producing tetrachlorophthalic anhydride according to claim 2, characterized by: The relative linkage mechanism (4) includes a support rod (41) connected with the fixed limiting ring (31) and a hollow roller (42) fixedly connected with the support rod (41). The driving rod (32) penetrates through the hollow roller (42) and is rotationally connected therewith; the hollow roller (42) is provided with a spiral reciprocating groove (43) on the surface, a rotating ring (44) is slidingly and rotationally sleeved on the outer surface of the hollow roller (42) and is slidingly matched with the reciprocating groove (43), so as to convert the rotary input of the rotating ring (44) into reciprocating motion output along the axis of the hollow roller (42).

4. The crystallization apparatus for producing tetrachlorophthalic anhydride according to claim 3, characterized by: The multifunctional stirring mechanism (5) includes three groups of connecting rods (51), one end of the connecting rod (51) is hinged to the rotating ring (44), and the other end is connected with a sliding block (54) through a sliding rod (52) and a spring pipe (53); The sliding block (54) is slidingly arranged in the sliding groove (36) formed on the surface of the deflection L-shaped stirring rod (33); a plurality of elastic stirring rods (56) are slidingly sleeved on the surface of the spring pipe (53).

5. The crystallization apparatus for producing tetrachlorophthalic anhydride according to claim 4, characterized by: The sliding rod (52) is internally provided with a communication V-shaped groove (55), the roots of the elastic stirring rods (56) extend into the spring pipe (53) and are slidingly matched with the communication V-shaped groove (55), so that the rotation of the sliding rod (52) can drive all the elastic stirring rods (56) to swing synchronously.

6. The crystallization apparatus for producing tetrachlorophthalic anhydride according to claim 5, characterized by: The end of the sliding rod (52) close to the connecting rod (51) is fixedly connected with a pull strip wheel (57), the end of the hollow roller (42) is provided with a fixed U-shaped pull strip (58), the U-shaped pull strip (58) is engaged with the pull strip wheel (57), so as to convert the reciprocating linear motion of the sliding rod (52) into periodic forward and reverse rotation.

7. The crystallization apparatus for producing tetrachlorophthalic anhydride according to claim 6, characterized by: Three said scrapers one (34) are respectively arranged at upper, middle and lower positions of the side of the three deflection L-shaped stirring rods (33), and the scraper two (35) is arranged at the bottom left, middle and right positions of the deflection L-shaped stirring rod (33) to cover the vertical inner wall and the bottom surface of the machine body (1) respectively.

8. The crystallization apparatus for producing tetrachlorophthalic anhydride according to claim 7, characterized by: The linkage assembly composed of the connecting rod (51), the slide rod (52), the spring tube (53) and the sliding block (54) is uniformly arranged in three groups in the circumferential direction and is correspondingly matched with the sliding groove (36) on the three deflection L-shaped stirring rods (33).

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