Continuous evaporative crystallization kettle

Abstract

The utility model provides a continuous evaporative crystallization kettle, which relates to the technical field of evaporative crystallization, and comprises a shell, a feeding hole is formed in the lower end of the shell, a gas-phase discharging hole is formed in the upper end of the shell, and a mother liquor overflow hole is formed in the side wall of the shell; the elutriation leg is connected to the lower portion of the shell, the inner space of the elutriation leg is communicated with the inner space of the shell, the lower end of the elutriation leg is provided with a bottom plate, the middle of the bottom plate protrudes upwards, the periphery of the bottom plate is sunken downwards, and a crystal mush discharging port is formed in the downwards-sunken position of the bottom plate; the stirring device comprises a push type stirring mechanism arranged in the shell, and the crystal mush discharging opening is located in the action range of the push type stirring mechanism; the problems that in the prior art, an evaporative crystallization kettle is prone to scaling and difficult to clean, and a crystal mush discharging opening is prone to being blocked are solved.

Description

Technical Field

[0001] This utility model belongs to the field of evaporation crystallization technology, and more specifically, relates to a continuous evaporation crystallization kettle. Background Technology

[0002] Evaporation crystallization, as the final step in zero-discharge wastewater treatment, is receiving increasing attention. Currently, industrial evaporation crystallization generally employs two methods: multi-effect evaporation (MED) or mechanical vapor recompression (MVR). The biggest problem with both methods is that inorganic salts such as sodium sulfate and sodium chloride precipitated during the evaporation crystallization process form scale on the surface of the reboiler heat exchange tubes, leading to reduced heat exchange efficiency, difficulty in long-term operation, frequent shutdowns for cleaning, and poor continuity. In addition, the crystal slurry discharge port at the bottom of the crystallizer is easily blocked by precipitated crystals, causing difficulties in discharging the slurry.

[0003] Patent publication number CN211611691U proposes installing a brush on the surface of the stirring shaft of an evaporator to clean the inner wall of the evaporator. However, the brush has a limited cleaning range, only able to clean the upper part of the stirring paddle, and the brush needs to rotate at the same speed as the stirring paddle. Excessive speed can shorten the brush's lifespan and cause it to easily break. Patent publication number CN218501275U proposes using dual motors and a telescopic scraper to clean the evaporator wall, achieving thorough cleaning of the inner wall. However, the problem of clogging at the discharge port remains unresolved. The bottom discharge port is located in the vacuum zone of the stirring shaft, easily accumulating large amounts of crystals, leading to blockages in the crystal slurry discharge port and pipelines. Furthermore, this solution does not thicken the crystal slurry, resulting in an excessively high mother liquor content in the discharged slurry, causing increased pressure in subsequent solid-liquid separation equipment. Utility Model Content

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a continuous evaporation crystallization kettle, which solves the problems of easy scaling, difficulty in cleaning, and easy clogging of the crystal slurry outlet in existing evaporation crystallization kettles.

[0005] To achieve the above objectives, this utility model provides a continuous evaporation crystallization kettle, comprising:

[0006] The shell has a feed inlet at its lower end, a gas outlet at its upper end, and a mother liquor overflow outlet on its side wall.

[0007] The washing leg is connected to the lower part of the shell, and the internal space of the washing leg is connected to the internal space of the shell. The lower end of the washing leg is provided with a bottom plate that is raised in the middle and recessed around the perimeter. The bottom plate is provided with a crystal slurry outlet at the recessed position.

[0008] A stirring device, comprising a propulsion stirring mechanism disposed within the housing, wherein the crystal slurry outlet is within the effective range of the propulsion stirring mechanism.

[0009] Optionally, a jacket is provided on the outer side of the housing, and a steam inlet and a condensate outlet are respectively provided on the upper and lower parts of the jacket.

[0010] Optionally, the propulsion stirring mechanism includes:

[0011] The first drive motor is located above the housing;

[0012] A stirring shaft extends through the top of the housing and is connected to the output end of the first drive motor;

[0013] A propulsion-type stirring paddle is connected to the stirring shaft.

[0014] Optionally, the stirring device further includes a frame-type stirring mechanism, wherein the outer periphery of the frame-type stirring mechanism is provided with scrapers that cooperate with the inner wall of the housing.

[0015] Optionally, the frame-type stirring mechanism includes:

[0016] A second drive motor is disposed above the housing, and a first bevel gear is provided at the output end of the second drive motor;

[0017] A stirring cylinder extends through the top of the housing and is rotatably sleeved on the outside of the stirring shaft. A second bevel gear that meshes with the first bevel gear is provided at the upper end of the stirring cylinder.

[0018] A frame-type stirring paddle is connected to the stirring cylinder.

[0019] Optionally, the inner wall of the shell is provided with an annular baffle, which is positioned above the frame-type stirring paddle.

[0020] Optionally, the scraper is disposed on the outer side of the frame-type agitator in the radial direction.

[0021] Optionally, the inner diameter of the washing leg is 20-50% of the inner diameter of the shell, the height-to-diameter ratio of the shell is 1:1 to 2:1, and the height-to-diameter ratio of the washing leg is 0.5:1 to 3:1.

[0022] Optionally, the area of ​​the baffle is 40% to 80% of the cross-sectional area of ​​the housing.

[0023] Optionally, the mother liquor overflow port is located above the baffle.

[0024] This invention provides a continuous evaporation crystallization kettle, which has the following advantages: The kettle has a washing leg at the bottom of the shell. The lower end of the washing leg has a bottom plate that bulges upwards in the center and is concave downwards around the edges, forming a W-shaped vertical cross-section. The crystal slurry outlet is located in the concave part of the bottom plate. The washing leg design avoids a vacuum zone directly below the stirring shaft, preventing crystal accumulation in the vacuum zone. It also features a propulsion stirring mechanism, placing the crystal slurry outlet within its range of motion, ensuring continuous agitation of the crystals at the outlet and preventing blockage. Furthermore, the washing leg design allows for a thicker crystal structure within the washing leg, increasing the crystal ratio and facilitating subsequent solid-liquid separation.

[0025] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0026] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings, in which like reference numerals generally represent like parts.

[0027] Figure 1 A schematic diagram of a continuous evaporation crystallization vessel according to an embodiment of the present invention is shown.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. Shell; 11. Inlet; 12. Gas phase outlet; 13. Mother liquor overflow outlet; 14. Crystal slurry outlet;

[0030] 2. Agitator; 21. First geared motor; 22. Second geared motor; 23. Agitator shaft; 24. Frame-type agitator; 25. Scraper; 26. Propeller agitator; 27. First bevel gear; 28. Second bevel gear;

[0031] 3. Jacket; 31. Steam inlet; 32. Condensate outlet;

[0032] 4. Baffle;

[0033] 5. Wash your legs. Detailed Implementation

[0034] Preferred embodiments of the present invention will now be described in more detail. While preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0035] like Figure 1 As shown, this utility model provides a continuous evaporation crystallization kettle, comprising:

[0036] The shell 1 has a feed inlet 11 at its lower end, a gas outlet 12 at its upper end, and a mother liquor overflow outlet 13 on its side wall.

[0037] Washing leg 5 is connected to the bottom of the shell 1. The internal space of washing leg 5 is connected to the internal space of shell 1. The lower end of washing leg 5 is provided with a bottom plate that is raised in the middle and recessed around the perimeter. The bottom plate is provided with a crystal slurry outlet 14 at the recessed position.

[0038] The stirring device 2 includes a propulsion stirring mechanism disposed within the housing 1, and the crystal slurry outlet 14 is within the effective range of the propulsion stirring mechanism.

[0039] Specifically, to address the problems of scale buildup, difficulty in cleaning, and easy clogging of the crystal slurry outlet 14 in existing evaporation crystallization kettles, the continuous evaporation crystallization kettle provided by this invention has a washing leg 5 below the shell 1. The lower end of the washing leg 5 has a bottom plate with a central upward protrusion and a surrounding downward depression, forming a W-shaped vertical cross-section at the lower end of the washing leg 5. The crystal slurry outlet 14 is located in the downward-depressed part of the bottom plate. The washing leg 5 avoids the stirring vacuum zone directly below the stirring shaft 23, preventing crystal accumulation in the vacuum zone. It also has a propulsion stirring mechanism, and the crystal slurry outlet 14 is within the range of action of the propulsion stirring mechanism, so that the crystals at the crystal slurry outlet 14 are constantly disturbed, preventing clogging of the crystal slurry outlet 14. Furthermore, the washing leg 5 makes the crystals thicker within the washing leg 5, increasing the crystal ratio and facilitating subsequent solid-liquid separation.

[0040] Optionally, a jacket 3 is provided on the outer side of the shell 1, and a steam inlet 31 and a condensate outlet 32 ​​are respectively provided on the upper and lower parts of the jacket 3.

[0041] Specifically, the jacket 3 is connected to the outer wall of the shell 1, and saturated steam can be introduced into the jacket 3 for heating.

[0042] Optionally, the propulsion mixing mechanism includes:

[0043] The first drive motor is located above the housing 1;

[0044] The stirring shaft 23 passes through the top of the housing 1 and is connected to the output end of the first drive motor;

[0045] The propulsion impeller 26 is connected to the stirring shaft 23.

[0046] Specifically, the first drive motor drives the stirring shaft 23 to rotate the propulsion stirring paddle 26. The propulsion stirring paddle 26 is an axial paddle that stirs inside the shell 1 to ensure the suspension and mixing effect of the material.

[0047] In this embodiment, the first drive motor is a first geared motor 21.

[0048] In this embodiment, the diameter of the propulsion impeller 26 is 30%-60% of the inner diameter of the shell 1, and there are multiple impellers arranged at intervals.

[0049] Optionally, the stirring device 2 also includes a frame-type stirring mechanism, the outer periphery of which is provided with scrapers 25 that cooperate with the inner wall of the housing 1.

[0050] Specifically, the frame-type mixing mechanism works in conjunction with the propeller-type mixing mechanism to achieve the mixing function and improve the mixing effect.

[0051] In this embodiment, the sum of the diameter of the frame-type stirring paddle 24 and the width of the two side scrapers 25 is the same as the inner diameter of the shell 1. The scrapers 25 are made of materials that are both tough and heat-resistant, such as polytetrafluoroethylene, polyvinylidene fluoride, and fluororubber.

[0052] Optionally, the frame-type stirring mechanism includes:

[0053] The second drive motor is located above the housing 1, and the output end of the second drive motor is provided with a first bevel gear 27;

[0054] A stirring drum extends through the top of the housing 1 and is rotatably sleeved on the outside of the stirring shaft 23. A second bevel gear 28 that engages with the first bevel gear 27 is provided at the upper end of the stirring drum.

[0055] The frame-type stirring paddle 24 is connected to the stirring drum.

[0056] Specifically, the second drive motor can drive the stirring drum to rotate the frame-type stirring paddle 24, and at the same time drive the scraper 25 to move relative to the inner wall of the shell 1, so as to exert the effect of the scraper 25. The frame-type stirring paddle 24 and the propeller-type stirring paddle 26 are driven by different drive motors, and the two can use different speeds to meet the stirring requirements and the life requirements of the scraper 25. By having the radial paddle frame-type stirring paddle 24 carrying the scraper 25 and the axial paddle propeller-type stirring paddle 26 that ensures the suspension of materials work at different speeds, the two work together to avoid scaling on the inner wall of the shell 1, ensuring the heat exchange effect, and ensuring the suspension of solid crystals, thus realizing the long-term and continuous operation of the continuous evaporation crystallization kettle.

[0057] Furthermore, the frame-type stirring paddle 24 can be coupled with the stirring rod via bearings.

[0058] In this embodiment, the second drive motor is a second geared motor 22.

[0059] In this embodiment, the diameter of the frame-type agitator 24 is 80%-95% of the inner diameter of the housing 1, and the propulsion agitator 26 is disposed inside the frame-type agitator 24.

[0060] Optionally, an annular baffle 4 is provided on the inner wall of the shell 1, and the baffle 4 is positioned above the frame-type stirring paddle 24.

[0061] Specifically, the outer periphery of the baffle 4 is connected to the inner wall of the housing 1.

[0062] Optionally, the scraper 25 is disposed on the outer side of the frame-type agitator 24 in the radial direction.

[0063] Specifically, the frame-type stirring paddle 24 drives the scraper 25 to clean the crystals adhering to the inner wall of the shell 1 in a timely manner, ensuring the heat exchange efficiency of the wall surface.

[0064] Furthermore, the propulsion agitator 26 can control the solid suspension in the crystallization vessel. Combined with the washing leg 5 and the W-shaped bottom structure design, it can prevent crystals from depositing and scaling at the bottom, clogging the crystal slurry outlet 14, and can also make the washing leg 5 thick, increasing the solid content of the crystals, which is convenient for subsequent solid-liquid separation operations, and realizing the long-term, continuous and stable operation of the continuous evaporation crystallization vessel.

[0065] Optionally, the inner diameter of the washing leg 5 is 20-50% of the inner diameter of the shell 1, the height-to-diameter ratio of the shell 1 is 1:1 to 2:1, and the height-to-diameter ratio of the washing leg 5 is 0.5:1 to 3:1.

[0066] Optionally, the area of ​​the baffle 4 is 40% to 80% of the cross-sectional area of ​​the housing 1.

[0067] Optionally, the mother liquor overflow port 13 is located above the baffle 4.

[0068] Specifically, the mother liquor overflow port 13 is located in the upper middle part of the shell 1, for example, at 2 / 3 of the total height of the shell 1.

[0069] In summary, when using the continuous evaporation crystallizer provided by this utility model, taking a single evaporation crystallization operation as an example: the shell 1 has a diameter of 1m and a height of 1.3m; a washing leg 5 is set at the bottom, with a diameter of 0.4m and a height of 0.3m; the frame-type stirring paddle 24 has a diameter of 0.9m, and scrapers 25 are connected to both sides of the frame-type stirring paddle 24, with a single-sided width of 0.05m, and the scrapers 25 are made of polytetrafluoroethylene (PTFE); the propeller-type stirring paddle 26 has a diameter of 0.4m and three layers of impellers; the baffle 4 occupies about 50% of the inner circumferential cross-sectional area of ​​the shell 1, and the mother liquor overflow port 13 is located at 2 / 3 of the height of the shell 1. Material enters the shell 1 through inlet 11. The frame-type agitator 24 is activated at a speed of approximately 10-30 r / min, and the propeller-type agitator 26 is activated at a speed of approximately 50-200 r / min. Saturated steam is introduced through steam inlet 31 at the top of the jacket 3 for heating. Water vapor is obtained through gas outlet 12. This water vapor can be connected to a steam compressor for compression and used as a heat source, or a negative pressure evaporation crystallizer can be installed at the rear end as a heat source for the subsequent evaporation effect, achieving heat coupling. During the evaporation process, the liquid level in the continuous evaporation crystallizer remains constant. When the condensate extraction rate reaches the design value, concentrated crystal slurry begins to be continuously discharged from the washing leg 5 into the solid-liquid separation process. The mother liquor overflow outlet 13 overflows to obtain clear mother liquor without crystals, thus achieving continuous and stable operation of the continuous evaporation crystallizer.

[0070] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A continuous evaporation crystallization vessel, characterized in that, include: The shell has a feed inlet at its lower end, a gas outlet at its upper end, and a mother liquor overflow outlet on its side wall. The washing leg is connected to the lower part of the shell, and the internal space of the washing leg is connected to the internal space of the shell. The lower end of the washing leg is provided with a bottom plate that is raised in the middle and recessed around the perimeter. The bottom plate is provided with a crystal slurry outlet at the recessed position. A stirring device, comprising a propulsion stirring mechanism disposed within the housing, wherein the crystal slurry outlet is within the effective range of the propulsion stirring mechanism.

2. The continuous evaporation crystallization reactor according to claim 1, characterized in that, The outer side of the shell is provided with a jacket, and the upper and lower parts of the jacket are respectively provided with a steam inlet and a condensate outlet.

3. The continuous evaporation crystallization reactor according to claim 1, characterized in that, The propulsion mixing mechanism includes: The first drive motor is located above the housing; A stirring shaft extends through the top of the housing and is connected to the output end of the first drive motor; A propulsion-type stirring paddle is connected to the stirring shaft.

4. The continuous evaporation crystallization reactor according to claim 3, characterized in that, The stirring device also includes a frame-type stirring mechanism, and the outer periphery of the frame-type stirring mechanism is provided with scrapers that cooperate with the inner wall of the shell.

5. The continuous evaporation crystallization reactor according to claim 4, characterized in that, The frame-type stirring mechanism includes: A second drive motor is disposed above the housing, and a first bevel gear is provided at the output end of the second drive motor; A stirring cylinder extends through the top of the housing and is rotatably sleeved on the outside of the stirring shaft. A second bevel gear that meshes with the first bevel gear is provided at the upper end of the stirring cylinder. A frame-type stirring paddle is connected to the stirring cylinder.

6. The continuous evaporation crystallization reactor according to claim 5, characterized in that, The inner wall of the shell is provided with an annular baffle, which is positioned above the frame-type stirring paddle.

7. The continuous evaporation crystallization reactor according to claim 5, characterized in that, The scraper is located on the outer side of the frame-type agitator in the radial direction.

8. The continuous evaporation crystallization reactor according to claim 1, characterized in that, The inner diameter of the washing leg is 20-50% of the inner diameter of the shell, the height-to-diameter ratio of the shell is 1:1 to 2:1, and the height-to-diameter ratio of the washing leg is 0.5:1 to 3:

1.

9. The continuous evaporation crystallization reactor according to claim 6, characterized in that, The area of ​​the baffle is 40% to 80% of the cross-sectional area of ​​the shell.

10. The continuous evaporation crystallization reactor according to claim 6, characterized in that, The mother liquor overflow port is located above the baffle.

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