Automatic grading discharging device of crystallizer

Abstract

The invention discloses an automatic grading discharging device of a crystallizer. The upper stirring assembly and the lower stirring assembly are mounted in the cylinder; the guide cylinder is vertically mounted in the middle of the cylinder body, and the stirring end of the upper stirring assembly is arranged in the guide cylinder; the automatic layering plate divides the material stirring space into an upper circulating area and a lower discharging area which are arranged up and down, and one end of the automatic layering plate is fixedly installed on the bottom wall of the cylinder and located between the lower stirring assembly and the guide cylinder; the other end of the annular channel faces the bottom of the guide cylinder and forms a material circulating channel with the bottom of the guide cylinder; the discharge hole is formed in the bottom of the barrel; through the synergistic effect of the upper stirring assembly, the lower stirring assembly, the guide cylinder and the automatic layering plate, the same device can flexibly adapt to two different processes of brine mixing crystallization and decomposition crystallization, automatic grading and targeted discharging based on the particle size and density can be achieved, and the process adaptability and separation efficiency of equipment are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of chemical crystallization equipment technology, specifically to an automatic grading and discharging device for a crystallizer. Background Technology

[0002] In the production process of potassium chloride using carnallite as raw material, decomposition and crystallization is one of the key steps. In this step, carnallite undergoes controlled-rate decomposition in a crystallizer, precipitating potassium chloride crystals. As the core equipment, the uniform mixing of the solid and liquid phases inside the crystallizer, the growth of potassium chloride crystals, and the smooth discharge of the final product directly affect the crystallizer's production efficiency and product quality.

[0003] Traditional crystallizers often employ a top-mounted agitator, where the drive motor and agitator shaft are inserted from the top of the crystallizer. This structure has several inherent drawbacks: First, the long-shaft cantilever structure is prone to significant radial oscillation when agitating high-density, high-solids-content slurries, affecting the lifespan of the mechanical seal and agitation stability. Second, crystal particles naturally settle to the bottom of the crystallizer cone under gravity; the hydrodynamic force generated at the bottom by the top agitator is weak, easily leading to the accumulation and compaction of solid material at the bottom, especially near the discharge port, forming a "dead zone." Severe accumulation can easily block the discharge channel, forcing unplanned production line shutdowns for cleaning, seriously affecting the continuity and stability of production.

[0004] To address the issue of material accumulation at the bottom, the industry has experimented with or adopted bottom-stirring solutions, which involve placing the agitator at the bottom of the crystallizer. However, implementing bottom-stirring devices faces significant sealing challenges. Crystallizers are typically filled with corrosive mother liquor that may contain tiny crystal particles, creating a harsh working environment. The agitator shaft needs to penetrate the bottom of the container, requiring an extremely reliable dynamic seal. Leakage will lead to slurry spillage, causing not only material loss and environmental pollution but also potential corrosion of the equipment foundation and safety accidents. Conventional packing seals wear out quickly and are prone to leakage under these conditions, requiring frequent maintenance.

[0005] In addition, for commonly used equipment such as DTB crystallizers, the traditional top-mounted agitator has the disadvantages of poor material circulation and easy accumulation at the bottom, while independent bottom agitators face the problems of complex structure and unreliable dynamic seals.

[0006] Therefore, designing an internal structure for a crystallizer that can balance strong top circulation and strong bottom local disturbance, and utilize fluid dynamics principles to achieve automatic grading and stable discharge of crystallized particles, while fundamentally simplifying or avoiding the problem of high-pressure differential sealing at the bottom, has become the key to breaking through existing technological bottlenecks and meeting the requirements for long-term continuous operation of carnallite decomposition and crystallization. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an automatic grading and discharging device for crystallizers that is simple in structure, reliable in sealing, and can effectively avoid the accumulation of bottom material and blockage of the discharge port.

[0008] The technical problem to be solved by the present invention is achieved through the following technical solution: an automatic grading and discharging device for a crystallizer, comprising; The cylinder has an internal space for material mixing. The upper mixing assembly is installed at the top of the cylinder and is configured to mix the upper material inside the cylinder. The bottom mixing assembly is installed at the bottom of the cylinder and is configured to mix the material at the bottom of the cylinder. The guide tube is vertically installed in the middle of the cylinder body, and the stirring end of the upper stirring assembly is placed inside the guide tube, which is configured to establish a material circulation channel between the inside and outside of the guide tube. An automatic stratification plate divides the material mixing space into an upper circulation zone and a lower discharge zone arranged one above the other. One end of the automatic stratification plate is fixedly installed on the bottom wall of the cylinder and located between the lower mixing assembly and the guide cylinder, while the other end faces the bottom of the guide cylinder and forms an annular channel for material circulation with the bottom of the guide cylinder. The discharge port is located at the bottom of the cylinder and below the automatic stratification plate. The material in the lower discharge zone is provided with centrifugal force by the lower mixing assembly and is discharged through the discharge port while being blocked from rising by the bottom surface of the automatic stratification plate.

[0009] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the above-mentioned automatic grading and discharge device for crystallizer, wherein an overflow weir is embedded in the top side wall of the cylinder, and an overflow port is provided on the outer side wall of the overflow weir.

[0010] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the above-mentioned automatic grading and discharge device for crystallizer has several guide plates fixedly arranged at intervals on the inner wall of the middle part of the cylinder. The guide plates are arranged vertically to guide the material circulation outside the guide cylinder.

[0011] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the above-mentioned automatic classification and discharge device for crystallizer, wherein the upper stirring assembly includes a transmission device I fixedly installed on the top of the cylinder, the power output end of the transmission device I is connected to the stirring shaft I through a coupling, the bottom of the stirring shaft I extends vertically into the cylinder and is located in the middle of the guide tube, and an upper stirring impeller is fixedly provided on the bottom outer circumferential surface of the stirring shaft I.

[0012] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the automatic classification and discharge device for crystallizer described above, wherein the lower stirring assembly includes a transmission device II fixedly installed at the bottom of the cylinder, the power output end of the transmission device II is connected to the stirring shaft II via a coupling, the top of the stirring shaft II extends vertically into the bottom of the cylinder and is located in the lower discharge area, and a lower stirring impeller is fixedly provided on the outer circumferential surface of the top of the stirring shaft II.

[0013] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the automatic grading and discharge device for crystallizer described above, wherein the outer circumferential surface of the middle part of the stirring shaft II is installed inside the bottom of the cylinder by a mechanical seal.

[0014] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the automatic grading and discharge device for crystallizer described above, wherein the lower stirring impeller is composed of an impeller hub and impeller blades; The impeller hub is fixedly connected to the bottom end of the stirring shaft II; The impeller blades are symmetrically fixed at both ends along the length of the impeller hub.

[0015] The technical problem to be solved by the present invention can also be achieved through the following technical solution: the automatic grading and discharge device for crystallizer described above, wherein the automatic grading plate is perpendicular to the impeller blades and the bottom inner wall of the cylinder.

[0016] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the automatic grading and discharge device for crystallizer described above, wherein the automatic grading plate is formed into a hollow frustum shape.

[0017] The technical problem to be solved by the present invention can also be achieved by the following technical solution: the automatic classification and discharge device for crystallizer described above, wherein the rotation speed of the stirring shaft I is 100~200 rpm and the rotation speed of the stirring shaft II is 300~400 rpm.

[0018] Compared with the prior art, the beneficial technical effects of the present invention are: (1) The automatic grading and discharge device of this crystallizer establishes material circulation fields with opposite directions inside and outside the guide tube through the linkage of the upper stirring assembly, the lower stirring assembly and the guide tube. This adapts to two different processes, brine crystallization and decomposition crystallization. This solves the technical problem of traditional crystallizers having a single function and difficulty in flexibly switching processes, and greatly improves the utilization rate of equipment and the flexibility of the production line. In both process modes, the device can automatically separate the coarse crystals that meet the requirements, such as carnallite or potassium chloride, from the fine crystals and mother liquor by utilizing the synergistic effect of the circulation flow field and gravity settling. The key design of the automatic grading plate effectively prevents the target crystals enriched in the lower discharge zone from returning to the upper circulation zone, keeping them locked at the bottom. Finally, the target crystals are stably discharged from the discharge port in the form of concentrated crystal slurry under the stable centrifugal force provided by the lower stirring assembly, thereby directly obtaining products with higher purity and larger particle size, improving the crystallization yield and efficiency.

[0019] (2) The independently driven lower stirring assembly generates strong shear and disturbance directly at the bottom of the crystallizer. Combined with the guiding effect of the automatic stratification plate, it fundamentally avoids the accumulation and caking of solid materials at the bottom of the cone and near the discharge port, eliminating the risk of blockage that could lead to unplanned shutdowns. This is in stark contrast to the defect of traditional top stirring which easily forms a "dead zone" at the bottom.

[0020] (3) The design of independent upper and lower stirring shortens the length of the stirring shaft, reduces the vibration and wear caused by the long shaft cantilever, and improves the life and operation stability of the mechanical seal; the bottom stirring structure directly acts on the discharge area, which is highly efficient. At the same time, the overall layout is clear and the installation and maintenance are more convenient, effectively solving the inherent contradictions of complex structure and unreliable sealing of traditional bottom stirring devices.

[0021] (4) The combination of the guide tube and the guide plate enhances the orderliness and efficiency of the internal circulation, promotes the uniform transfer of heat and mass, and is conducive to crystal growth. The automatic layering plate realizes the hydrodynamic separation between the "circulation zone" and the "settling and discharge zone", so that the stirring energy can be more focused on the core functions of each zone, namely strong mixing in the upper part, anti-accumulation and discharge in the lower part, avoiding ineffective energy dissipation and optimizing the system energy consumption. Attached Figure Description

[0022] Figure 1 This is a partial front view of the graded discharge device of the present invention before use; Figure 2 This is a front view schematic diagram of the graded discharge device of the present invention in use; Figure 3 This is a top view of the automatic layering plate of the present invention.

[0023] Reference numerals in the attached drawings: 1. Cylinder; 2. Guide cylinder; 3. Automatic stratification plate; 4. Discharge port; 5. Overflow weir; 6. Overflow outlet; 7. Guide plate; 8. Transmission device I; 9. Stirring shaft I; 10. Upper stirring impeller; 11. Transmission device II; 12. Stirring shaft II; 13. Lower discharge zone; 14. Impeller blades; 15. Impeller hub; 16. Annular channel. Detailed Implementation

[0024] The specific technical solutions of the present invention will be further described below with reference to the accompanying drawings, so as to enable those skilled in the art to further understand the present invention, without constituting a limitation on its rights.

[0025] Example 1, referring to Figure 1-3 An automatic grading and discharging device for a crystallizer includes: Cylinder 1, which can be a cylindrical structure with a bottom that is larger at the top and smaller at the bottom, and its specific shape and size can be selected according to the usage requirements. It has a material mixing space inside. The upper stirring assembly is installed on the top of the cylinder 1 and is configured to stir the upper material inside the cylinder 1. Its rotation speed can be selected according to the usage requirements. The lower stirring assembly is installed at the bottom of the cylinder 1 and is configured to stir the bottom material inside the cylinder 1. Its speed can be selected according to the usage requirements. The guide tube 2 is formed into a roughly cylindrical structure and is vertically installed in the middle of the cylinder 1. The stirring end of the upper stirring assembly is placed inside the guide tube 2, and it is configured to establish a material circulation channel between the inside and outside of the guide tube 2. The automatic layering plate 3 is formed into a hollow frustum shape. Its size and specifications can be selected according to the usage requirements. Its cross-section is in the shape of a ring. It divides the material mixing space into an upper circulation area and a lower discharge area arranged one above the other. One end of the automatic layering plate 3 is fixedly installed on the bottom wall of the cylinder 1 and located between the lower mixing assembly and the guide cylinder 2. The other end faces the bottom of the guide cylinder 2 and forms an annular channel 16 with the bottom of the guide cylinder 2 to form a material circulation channel. The discharge port 4 is located at the bottom of the cylinder 1 and below the automatic stratification plate 3. The material in the lower discharge zone is provided with centrifugal force by the lower mixing assembly and is discharged through the discharge port 4 while being blocked from rising by the bottom surface of the automatic stratification plate 3.

[0026] In Example 1, the automatic grading and discharge device for crystallizer is suitable for both brine crystallization and decomposition crystallization operations. By cooperating with the upper stirring assembly and the guide tube 2 to establish a powerful main circulation, and by utilizing the synergistic effect of the lower stirring assembly and the automatic grading plate 3, it achieves effective blocking, enrichment and stable discharge of precipitated crystals. The automatic grading and discharge effect is good, which solves the technical problems of easy accumulation of bottom material, easy blockage of discharge port 4 and poor process adaptability under the previous single stirring method.

[0027] Example 2, an automatic grading and discharge device for a crystallizer as described in Example 1, wherein an overflow weir 5 is embedded in the top side wall of the cylinder 1, and an overflow port 6 is provided on the outer side wall of the overflow weir 5.

[0028] In Example 2, the added overflow weir 5 and overflow port 6 can discharge excess fluid by themselves, meeting basic operational requirements.

[0029] Example 3: The automatic grading and discharge device for crystallizer described in Example 1 has several guide plates 7 fixedly arranged at intervals on the inner wall of the middle part of the cylinder 1. The guide plates 7 are vertically arranged and are formed into a roughly square plate structure. The number and installation spacing can be selected according to the usage requirements, thereby providing guidance for the material circulation outside the guide cylinder 2.

[0030] In Example 3, the purpose of adding the guide plate 7 is to guide and regulate the circulating flow of materials from bottom to top or from top to bottom outside the guide tube 2, reduce eddies and short-circuit flow, thereby improving the overall circulation efficiency and flow field stability, ensuring uniform crystal suspension and growth environment, and enhancing the classification effect.

[0031] Example 4, an automatic grading and discharging device for a crystallizer as described in Example 1, wherein the upper stirring assembly includes a transmission device I8 fixedly installed on the top of the cylinder 1. The transmission device I8 can be a servo motor, etc., and its specifications and models can be selected according to the usage requirements. The power output end of the transmission device I8 is connected to the stirring shaft I9 through a coupling. The rotation speed of the stirring shaft I9 can be 100~200 rpm. The bottom of the stirring shaft I9 extends vertically into the cylinder 1 and is located in the middle of the guide cylinder 2. An upper stirring impeller 10 is fixedly provided on the outer circumferential surface of the bottom of the stirring shaft I9. The upper stirring impeller 10 can be an axial flow stirring impeller 10.

[0032] Example 5, an automatic grading and discharging device for a crystallizer as described in Example 1, wherein the lower stirring assembly includes a transmission device II11 fixedly installed at the bottom of the cylinder 1. The transmission device II11 can be a servo motor, etc., and its specifications and models can be selected according to the usage requirements. The power output end of the transmission device II11 is connected to the stirring shaft II12 through a coupling. The rotation speed of the stirring shaft II12 can be 300~400 rpm. The top of the stirring shaft II12 extends vertically into the bottom of the cylinder 1 and is located in the lower discharge area 13. A lower stirring impeller is fixedly provided on the outer circumferential surface of the top of the stirring shaft II12. The outer circumferential surface of the middle part of the stirring shaft II12 is installed inside the bottom of the cylinder 1 through a mechanical seal. The mechanical seal can be a rotary mechanical seal structure in the prior art. The specifications and models can be selected according to the usage requirements, so its specific structural principle will not be described in detail here. The bottom of the cylinder 1 is an inverted frustum-shaped structure with a hollow top. The lower stirring impeller is composed of an impeller hub 15 and impeller blades 14. The impeller hub 15 is fixedly connected to the bottom end of the stirring shaft II 12; The impeller blades 14 are symmetrically fixed at both ends along the length of the impeller hub 15, and the automatic layering plate 3 is perpendicular to the bottom inner wall of the impeller blades 14 and the cylinder 1, respectively.

[0033] In Example 5, the lower stirring impeller consists of an impeller hub 15 and impeller blades 14. Its structure is precisely matched with the bottom of the inverted frustum-shaped cylinder 1 and the automatic stratification plate 3. The impeller blades 14 are parallel to the bottom side wall of the cylinder, which can generate a strong shear flow and impart centrifugal force to the material in the lower discharge zone 13. At the same time, it and the vertical automatic stratification plate 3 together form an efficient flow guiding and blocking structure to ensure that the enriched crystal slurry is stably guided to the discharge port 4. The application of mechanical seals fundamentally solves the leakage risk of the bottom rotating shaft and ensures the long-term sealing reliability of the device.

[0034] It should be noted that the upper impeller is axial flow type, and its main function is to generate axial circulation force to drive the crystal slurry to form a stable upper and lower convection circulation in the guide tube, ensuring uniform supersaturation distribution; while the lower impeller is radial / mixed flow type, which mainly provides low shear force and centrifugal force.

[0035] The automatic grading and discharging device for the crystallizer in Examples 1-5 is suitable for both brine-mixing crystallization and decomposition crystallization operations. (1) Brine crystallization mode, carnallite sedimentation discharge: Target flow field: downward inside guide tube 2, upward outside guide tube 2.

[0036] Implementation method: The upper stirring assembly is turned on, pumping the fluid from top to bottom, forming a downward jet in the guide tube 2. This jet changes direction after impacting the bottom. At this time, the overall flow field is dominated by the upper stirring, forming a large circulation of "downward inside the tube and upward outside the tube". In this circulation, the generated carnallite crystals settle downward outside the guide tube 2. The key role of the automatic stratification plate 3 is that its inclined plate surface and the annular channel 16 together form a fluid dynamic "interception screen": it allows the circulating mother liquor to pass through, while the carnallite coarse crystals with greater gravity are positioned relatively lower due to gravity. Therefore, they are effectively blocked by the bottom plate surface of the automatic stratification plate 3, preventing the carnallite coarse crystals that have settled downward from returning to the upper circulation area. Instead, they are forced to accumulate in the lower discharge area 13 below the automatic stratification plate 3. When discharging, the accumulated carnallite crystal slurry is transported to the bottom inner wall of the cylinder 1 by the centrifugal force provided by the lower stirring assembly, and finally discharged from the discharge port 4.

[0037] (2) Decomposition crystallization mode, crude potassium output: Target flow field: upward inside guide tube 2, downward outside guide tube 2.

[0038] Implementation: The upper impeller 10 of the upper stirring assembly can be an axial flow impeller capable of generating an upward pumping flow, and the transmission device I8 reverses. At this time, the upper stirring assembly forms an upward jet within the guide tube 2. That is to say, due to the "suction" effect of the upper stirring assembly, the fluid in the guide tube 2 tends to enter from the bottom of the guide tube 2 and flow upward, thus completing the "upward inside the tube, downward outside the tube" cycle. In this reverse cycle, potassium chloride (crude potassium) crystals that have grown to a sufficient particle size settle to the lower discharge zone 13 by their own weight, while fine crystals and mother liquor continue to participate in the circulation and growth in the upper circulation zone, achieving continuous hydraulic classification of crystals to a certain extent. In this mode, the crude potassium crystals intercepted by the automatic stratification plate 3 are enriched in the lower discharge zone 13 and transported to the bottom inner wall of the cylinder 1 by the centrifugal force provided by the lower stirring assembly, and finally discharged from the discharge port 4.

[0039] In other words, both of the above operating modes can achieve efficient hydrodynamic retention and spatial enrichment of the target crystals through the automatic layering plate 3, automatically separating the "growth / circulation space" and the "product discharge space", thereby improving the crystallization yield and efficiency.

Claims

1. An automatic grading and discharging device for a crystallizer, characterized in that: include; The cylinder has an internal space for material mixing. The upper mixing assembly is installed at the top of the cylinder and is configured to mix the upper material inside the cylinder. The bottom mixing assembly is installed at the bottom of the cylinder and is configured to mix the material at the bottom of the cylinder. The guide tube is vertically installed in the middle of the cylinder body, and the stirring end of the upper stirring assembly is placed inside the guide tube, which is configured to establish a material circulation channel between the inside and outside of the guide tube. An automatic stratification plate divides the material mixing space into an upper circulation zone and a lower discharge zone arranged one above the other. One end of the automatic stratification plate is fixedly installed on the bottom wall of the cylinder and located between the lower mixing assembly and the guide cylinder, while the other end faces the bottom of the guide cylinder and forms an annular channel for material circulation with the bottom of the guide cylinder. The discharge port is located at the bottom of the cylinder and below the automatic stratification plate. The material in the lower discharge zone is provided with centrifugal force by the lower mixing assembly and is discharged through the discharge port while being blocked from rising by the bottom surface of the automatic stratification plate.

2. The automatic grading and discharging device for a crystallizer according to claim 1, characterized in that: An overflow weir is embedded in the top side wall of the cylinder, and an overflow port is provided on the outer side wall of the overflow weir.

3. The automatic grading and discharging device for a crystallizer according to claim 1, characterized in that: Several guide plates are fixedly installed at intervals on the inner wall of the middle part of the cylinder. The guide plates are set vertically to guide the material circulation outside the guide cylinder.

4. The automatic grading and discharging device for a crystallizer according to claim 1, characterized in that: The upper stirring assembly includes a transmission device I fixedly installed on the top of the cylinder. The power output end of the transmission device I is connected to the stirring shaft I via a coupling. The bottom of the stirring shaft I extends vertically into the cylinder and is located in the middle of the guide tube. An upper stirring impeller is fixedly provided on the outer circumferential surface of the bottom of the stirring shaft I.

5. The automatic grading and discharging device for a crystallizer according to claim 1, characterized in that: The lower stirring assembly includes a transmission device II fixedly installed at the bottom of the cylinder. The power output end of the transmission device II is connected to the stirring shaft II via a coupling. The top of the stirring shaft II extends vertically into the bottom of the cylinder and is located in the lower discharge area. A lower stirring impeller is fixedly provided on the outer circumferential surface of the top of the stirring shaft II.

6. The automatic grading and discharging device for a crystallizer according to claim 5, characterized in that: The outer circumferential surface of the middle part of the stirring shaft II is installed inside the bottom of the cylinder through a mechanical seal.

7. The automatic grading and discharging device for a crystallizer according to claim 5, characterized in that: The lower stirring impeller is composed of an impeller hub and impeller blades; The impeller hub is fixedly connected to the bottom end of the stirring shaft II; The impeller blades are symmetrically fixed at both ends along the length of the impeller hub.

8. The automatic grading and discharging device for a crystallizer according to claim 7, characterized in that: The automatic layering plate is perpendicular to both the impeller blades and the bottom inner wall of the cylinder.

9. The automatic grading and discharging device for a crystallizer according to claim 1, characterized in that: The automatic layering plate is formed into a hollow frustum shape.

10. An automatic grading and discharging device for a crystallizer according to claim 1, characterized in that: The stirring shaft I rotates at a speed of 100~200 rpm, and the stirring shaft II rotates at a speed of 300~400 rpm.

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