A continuous evaporation crystallization device for sodium salt

Abstract

The utility model relates to crystallizer technical field discloses a kind of sodium salt continuous evaporation crystallization equipment, including crystallizing tank and receiving liquid tank, vacuumizing equipment, condenser, heater, crystallizing tank outside is fixedly connected with jacketed cylinder, crystallizing tank outside is also fixedly connected with feed end via jacketed cylinder, the lower end of crystallizing tank is fixedly connected with multiple discharge end via jacketed cylinder, feed end and discharge end are respectively communicated with the inner cavity of crystallizing tank, jacketed cylinder outside is fixedly connected with jacketed water outlet end, the lower end of jacketed cylinder is fixedly connected with jacketed water inlet end. Scraper is fixed on swingable connecting arm, and connecting arm and auxiliary arm are connected by eccentric arrangement fixed shaft, when stirring shaft reverses, scraper rotates by connecting arm with fixed shaft as axis under the action of centrifugal force and crystal pulp resistance, can be actively pasted to the inner wall surface of crystallizing tank.

Description

Technical Field

[0001] This utility model relates to the field of crystallizer technology, and in particular to a continuous evaporation crystallization device for sodium salt. Background Technology

[0002] Sodium salt crystallization, simply put, is the process of precipitating sodium salts in a solution as particles. For example, in concentrated seawater or brine, as water evaporates, the concentration of sodium ions and chloride ions (or other acid radicals) increases. Once the saturation level is exceeded, they will arrange themselves into crystals in an orderly manner, changing from a liquid to a solid. Sodium salt evaporation crystallization commonly uses crystallization equipment such as multi-effect evaporators, mechanical vapor recompression evaporators, forced circulation crystallizers, and crystallization kettles.

[0003] In the evaporation and crystallization process of inorganic salts such as sodium salts, existing crystallization kettles typically maintain a certain gap between the scraper and the kettle wall, for example, 2-5 mm. This is to prevent the scraper from directly and continuously abrading the kettle wall and to prevent metal powder from contaminating the crystal slurry. However, in actual operation, during the stirring and heating process of the salt-containing crystal slurry, due to the high supersaturation near the kettle wall, salts easily and gradually deposit on the inner wall of the kettle, forming a dense adhesion layer. Because there is a gap between the scraper and the kettle wall, this adhesion layer is located within this gap, making it inaccessible to the scraper and thus preventing its effective removal. As the crystallization time increases, the deposited layer thickens, leading to a significant decrease in the heat transfer efficiency of the heat exchange jacket. This slows down the cooling or heating rate of the crystallization vessel, forcing a longer production cycle. At the same time, the locally thickened deposited layer may occasionally peel off and mix into the crystal slurry, becoming coarse or irregular grains that affect the particle size distribution and purity of the final product. To remove this scale, operators have to frequently stop the machine and use high-pressure water or chemical cleaning methods to treat the inner wall, which increases labor intensity and generates additional cleaning waste liquid, hindering continuous and clean production. Utility Model Content

[0004] The purpose of this invention is to provide a continuous evaporation and crystallization device for sodium salts. It adopts a swingable connecting arm with a scraper. By using the scraper, which is eccentrically installed relative to the axis of the stirring shaft, centrifugal force can be used to make the scraper actively stick to the tank wall when the stirring shaft is rotated, which can effectively solve the problems in the background art.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0006] A continuous evaporation crystallization device for sodium salt includes a crystallization tank and a receiving tank, a vacuum pump, a condenser, and a heater. A jacketed cylinder is fixedly connected to the outside of the crystallization tank, and a feed inlet is also fixedly connected to the outside of the crystallization tank via the jacketed cylinder. Multiple discharge inlets are fixedly connected to the lower end of the crystallization tank via the jacketed cylinder. The feed inlets and discharge inlets are respectively connected to the inner cavity of the crystallization tank. A jacketed water outlet is fixedly connected to the outside of the jacketed cylinder, and a jacketed water inlet is fixedly connected to the lower end of the jacketed cylinder, communicating with the jacketed heat exchange cavity formed between the jacketed cylinder and the outer wall of the crystallization tank. The receiving tank is connected to the input end of the vacuum pump and the condenser via pipes. The gas output end is connected, the top of the crystallizer is connected to the gas input end of the condenser through a pipe, the liquid input end of the heater is connected to the water outlet end of the jacket through a pipe, the liquid output end of the heater is connected to the water inlet end of the jacket through a circulation pump, and multiple discharge ends are connected to the feed end of the discharge pump through pipes. A frame is fixedly connected to the crystallizer, and a motor is fixedly connected to the frame. One end of the output shaft of the motor extends into the crystallizer and is fixedly connected to a stirring shaft. Multiple stirring blades and auxiliary arms are fixedly connected to the outside of the stirring shaft. A connecting arm is movably connected to one end of the auxiliary arm, and a scraper is fixedly connected to one end of the connecting arm.

[0007] As a further preferred embodiment of this utility model, a positioning groove is provided at the end of the auxiliary arm away from the stirring shaft to provide installation space for the connecting arm and to limit the bidirectional swing of the connecting arm. A fixed shaft is fixedly connected to the inner side of the positioning groove to provide a foundation for the connection between the auxiliary arm and the connecting arm.

[0008] As a further preferred embodiment of this utility model, one end of the connecting arm is provided with a connecting groove and is rotatably connected to the fixed shaft, and the other end of the connecting arm is provided with an installation groove and is fixedly connected to the scraper.

[0009] As a further preferred embodiment of this utility model, the connecting arm is inclined to one side relative to the auxiliary arm, with an included angle of thirty degrees. Based on the eccentric arrangement of the fixed shaft, the rotatable end of the connecting arm is eccentrically set relative to the rotation center of the stirring blade. The swing of the connecting arm is controlled by the forward and reverse rotation of the stirring shaft and the action of centrifugal force, thereby controlling the adhesion and separation of the scraper from the inner wall of the crystallizing tank.

[0010] As a further preferred embodiment of this utility model, the scraper is made of polytetrafluoroethylene material.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] In this invention, the scraper is fixed on a swingable connecting arm, and the connecting arm and the auxiliary arm are connected by an eccentrically arranged fixed shaft. When the stirring shaft rotates forward, the centrifugal force and the resistance of the crystal slurry are used to keep the scraper at a fixed distance from the tank wall. When the stirring shaft rotates in reverse, the scraper rotates around the fixed shaft through the connecting arm under the action of centrifugal force and the resistance of the crystal slurry, and can actively stick to the inner wall of the crystallization tank. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the main structural layout of this utility model;

[0014] Figure 2 This is a cross-sectional view of the crystallization tank of this utility model;

[0015] Figure 3 This is a schematic diagram showing the positional status of the crystallizer, stirring shaft, auxiliary arm, connecting arm, and scraper of this utility model.

[0016] Figure 4 This is a schematic diagram of the stirring shaft, auxiliary arm, connecting arm, and scraper structure of this utility model;

[0017] Figure 5 This is a schematic diagram of the auxiliary arm structure of this utility model;

[0018] Figure 6 This is a schematic diagram of the connecting arm structure of this utility model.

[0019] In the diagram: 1. Crystallization tank; 2. Receiving tank; 3. Vacuum pump; 4. Condenser; 5. Heater; 6. Circulating pump; 7. Discharge pump; 8. Jacketed cylinder; 9. Frame; 10. Motor; 11. Stirring shaft; 12. Stirring blade; 13. Auxiliary arm; 14. Connecting arm; 15. Scraper; 16. Feed end; 17. Discharge end; 18. Jacket water inlet end; 19. Jacket water outlet end; 20. Positioning groove; 21. Fixed shaft; 22. Connecting groove; 23. Mounting groove. Detailed Implementation

[0020] To make the technical means, creative features, objectives and effects of this utility model easier to understand, the present utility model will be further described below in conjunction with specific embodiments.

[0021] like Figures 1-6As shown, this utility model provides a continuous evaporation crystallization device for sodium salt, including a crystallization tank 1 and a receiving tank 2, a vacuum pump 3, a condenser 4, and a heater 5. A jacketed cylinder 8 is fixedly connected to the outside of the crystallization tank 1, and a feed end 16 is also fixedly connected to the outside of the crystallization tank 1 via the jacketed cylinder 8. Multiple discharge ends 17 are fixedly connected to the lower end of the crystallization tank 1 via the jacketed cylinder 8. The feed end 16 and the discharge ends 17 are respectively connected to the inner cavity of the crystallization tank 1. A jacketed water outlet 19 is fixedly connected to the outside of the jacketed cylinder 8, and a jacketed water inlet 18 is fixedly connected to the lower end of the jacketed cylinder 8, which is connected to the jacketed heat exchange cavity formed between the jacketed cylinder 8 and the outer wall of the crystallization tank 1. The receiving tank 2 is connected to the input end of the vacuum pump 3 through pipes. The gas output end of the condenser 4 is connected to the top of the crystallizer 1 via a pipe. The liquid input end of the heater 5 is connected to the jacket water outlet 19 via a pipe. The liquid output end of the heater 5 is connected to the jacket water inlet 18 via the circulation pump 6. Multiple discharge ends 17 are connected to the feed end of the discharge pump 7 via pipes. A frame 9 is fixedly connected to the crystallizer 1. A motor 10 is fixedly connected to the frame 9. One end of the output shaft of the motor 10 extends into the crystallizer 1 and is fixedly connected to a stirring shaft 11. Multiple stirring blades 12 and auxiliary arms 13 are fixedly connected to the outside of the stirring shaft 11. A connecting arm 14 is movably connected to one end of the auxiliary arm 13. A scraper 15 is fixedly connected to one end of the connecting arm 14.

[0022] like Figures 2-6 As shown, the end of the auxiliary arm 13 away from the stirring shaft 11 is provided with a positioning groove 20, which provides installation space for the connecting arm 14 and limits the bidirectional swing of the connecting arm 14. A fixed shaft 21 is fixedly connected to the inner side of the positioning groove 20, which provides a foundation for the connection between the auxiliary arm 13 and the connecting arm 14. One end of the connecting arm 14 is provided with a connecting groove 22 and is rotatably connected to the fixed shaft 21. The other end of the connecting arm 14 is provided with an installation groove 23 and is fixedly connected to the scraper 15. The connecting arm 14 is inclined to one side relative to the auxiliary arm 13, with an inclination angle of 30 degrees. Based on the eccentric arrangement of the fixed shaft 21, the rotatable end of the connecting arm 14 is eccentrically set relative to the rotation center of the stirring blade 12. The swing of the connecting arm 14 is controlled by the forward and reverse rotation of the stirring shaft 11 and the centrifugal force, thereby controlling the contact and separation between the scraper 15 and the inner wall of the crystallizing tank 1.

[0023] like Figure 4 As shown, scraper 15 is made of polytetrafluoroethylene.

[0024] It should be noted that this utility model is a continuous evaporation crystallization device for sodium salts. During the preparation of the crystal slurry, the prepared sodium salt solution is first fed into the crystallization tank 1 through the feed end 16. Simultaneously, the vacuum device 3 is turned on to maintain a certain vacuum level inside the crystallization tank 1, lowering the boiling point of the solution. Hot water enters the jacket heat exchange chamber between the jacket cylinder 8 and the outer wall of the crystallization tank 1 from the jacket water inlet end 18, transferring heat to the solution inside the tank. The cooled water flows out from the jacket water outlet end 19, is reheated by the heater 5, and then pumped back to the jacket water inlet by the circulation pump 6. End 18, heating in this cycle, the water in the tank evaporates continuously under vacuum and heating conditions, the water vapor enters the condenser 4 from the top pipe of the crystallizer 1, is cooled into liquid water and flows into the receiving tank 2, while the non-condensable gas is removed by the vacuum equipment 3. As the water continues to evaporate, the sodium salt concentration in the solution becomes higher and higher. Once it exceeds the saturation, the salt will precipitate in the form of crystals. The slurry containing crystals (crystal slurry) is discharged from multiple discharge ends 17 at the bottom of the crystallizer 1 and sent to the next process for solid-liquid separation by the discharge pump 7.

[0025] Additionally, during preparation, a secondary arm 13 is fixed to the stirring shaft 11. At the end of the secondary arm 13, a connecting arm 14 that can rotate around the shaft is mounted via a fixed shaft 21. The connecting arm 14 is offset to one side at a 30-degree angle relative to the secondary arm 13. The scraper 15 is fixed to the outermost end of the connecting arm 14. The stirring shaft 11 is driven by the motor 10 and can rotate forward or backward. When the equipment is in normal crystallization mode, the stirring shaft 11 rotates forward. At this time, under the combined action of centrifugal force and crystal slurry flow resistance, the scraper 15 will swing away from the tank wall around the fixed shaft 21, causing the scraper 15 to move in the direction away from the tank wall. A gap a few millimeters wide is left between the inner walls so that the scraper 15 does not normally contact the tank wall, thus avoiding wear caused by constant friction against the tank wall. When the operator needs to clean the tank wall after running for a period of time, the motor 10 can be reversed to reverse the stirring shaft 11. After reversal, the direction of the centrifugal force and the resistance of the crystallizing slurry to the scraper 15 also reverses. At this time, the scraper 15 will be pushed by the centrifugal force. Because the length of the stirring shaft 11, the auxiliary arm 13, the connecting arm 14, and the scraper 15 on the same horizontal axis is greater than the radius of the crystallizing tank 1, one end of the scraper 15 will abut against the inner wall of the crystallizing tank 1 and will not be able to continue rotating.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A continuous evaporation and crystallization apparatus for sodium salts, characterized in that: The system includes a crystallizer (1) and a receiving tank (2), a vacuum pump (3), a condenser (4), and a heater (5). A jacketed cylinder (8) is fixedly connected to the outside of the crystallizer (1). A feed end (16) is also fixedly connected to the outside of the crystallizer (1) via the jacketed cylinder (8). Multiple discharge ends (17) are fixedly connected to the lower end of the crystallizer (1) via the jacketed cylinder (8). The feed end (16) and the discharge end (17) are respectively connected to the inner cavity of the crystallizer (1). A jacketed water outlet end (19) is fixedly connected to the outside of the jacketed cylinder (8). A jacketed water inlet end (18) is fixedly connected to the lower end of the jacketed cylinder (8), which is connected to the jacketed heat exchange cavity formed between the jacketed cylinder (8) and the outer wall of the crystallizer (1). The receiving tank (2) is connected to the input end of the vacuum equipment (3) and the gas output end of the condenser (4) through pipes respectively. The top of the crystallizing tank (1) is connected to the gas input end of the condenser (4) through pipes. The liquid input end of the heater (5) is connected to the jacket water outlet (19) through pipes. The liquid output end of the heater (5) is connected to the jacket water inlet (18) through the circulation pump (6). Multiple discharge ends (17) are connected to the feed end of the discharge pump (7) through pipes. A frame (9) is fixedly connected to the crystallizing tank (1). A motor (10) is fixedly connected to the frame (9). One end of the output shaft of the motor (10) extends into the crystallizing tank (1) and is fixedly connected to the stirring shaft (11). Multiple stirring blades (12) and auxiliary arms (13) are fixedly connected to the outside of the stirring shaft (11). A connecting arm (14) is movably connected to one end of the auxiliary arm (13), and a scraper (15) is fixedly connected to one end of the connecting arm (14).

2. The continuous evaporation and crystallization equipment for sodium salts according to claim 1, characterized in that: The auxiliary arm (13) has a positioning groove (20) at one end away from the stirring shaft (11), and a fixing shaft (21) is fixedly connected to the inside of the positioning groove (20).

3. The continuous evaporation and crystallization equipment for sodium salts according to claim 2, characterized in that: One end of the connecting arm (14) is provided with a connecting groove (22) and is rotatably connected to the fixed shaft (21). The other end of the connecting arm (14) is provided with an installation groove (23) and is fixedly connected to the scraper (15).

4. The continuous evaporation and crystallization equipment for sodium salts according to claim 3, characterized in that: The connecting arm (14) is tilted to one side relative to the auxiliary arm (13) at an angle of 30 degrees.

5. The continuous evaporation and crystallization equipment for sodium salts according to claim 1, characterized in that: The scraper (15) is made of polytetrafluoroethylene.

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