Ammonium chloride crystallization system
By controlling the temperature in zones within the ammonium chloride crystallization system and using spiral guide plates, stirring devices, and salting-out agents, the problem of inaccurate temperature gradient control was solved, achieving efficient and stable ammonium chloride crystallization and improving crystal quality and equipment operational stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANDONG LUWEI PHARMA
- Filing Date
- 2025-07-23
- Publication Date
- 2026-07-10
Smart Images
Figure CN224474725U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of ammonium chloride technology, specifically relating to an ammonium chloride crystallization system. Background Technology
[0002] Ammonium chloride, as an important chemical raw material, is widely used in fertilizers, batteries, electroplating, and other fields. In the soda ash process, ammonium chloride is a byproduct of soda ash production, and its crystallization process directly affects product quality and production efficiency. In traditional processes, ammonium chloride crystallization is mostly achieved through cooling crystallization or evaporation crystallization. With increasingly stringent environmental protection requirements and rising energy costs, optimizing the ammonium chloride crystallization process has become a focus of industry attention.
[0003] Traditional single-tank crystallizers often combine cooling and crystallization processes, resulting in imprecise temperature gradient control and uneven supersaturation distribution. This easily triggers explosive nucleation, producing a large number of fine crystals, while limiting the growth of the target large crystals. During crystallization, ammonium chloride solution readily crystallizes and adheres to the inside of the tank, forming hard scale. This not only severely reduces heat transfer efficiency and increases energy consumption but also clogs pipes and valves, forcing frequent equipment shutdowns for cleaning, shortening continuous operating time, and increasing maintenance costs and production capacity loss. Utility Model Content
[0004] This invention provides an ammonium chloride crystallization system with high crystallization efficiency and stable quality.
[0005] The technical solution of this utility model is as follows: an ammonium chloride crystallization system, including a crystallizer, a circulating tank, and a controller; the crystallizer includes a tank body, which is provided with a cooling chamber, a crystallization chamber, and a conical section from top to bottom; a baffle plate is provided between the cooling chamber and the crystallization chamber; a gate valve is provided on the baffle plate; the gate valve is electrically connected to the controller; the tank body is connected to a mother liquor inlet pipe and a salting-out agent inlet pipe; a discharge pipe is provided at the bottom of the tank body; a discharge valve is provided on the discharge pipe; the discharge valve is electrically connected to the controller.
[0006] The cooling chamber is equipped with a cooling coil on the outside of the tank body. The cooling coil is connected to an external circulator and is equipped with an electromagnetic flow meter, which is electrically connected to the controller. The cooling chamber is equipped with a spiral guide plate.
[0007] The gate valve is connected to a branch pipe at the end away from the cooling chamber, and the branch pipe is connected to a crystallizer distributor at the end away from the gate valve. The crystallizer distributor has a strip structure and an opening at the bottom. The crystallizer distributor ensures that the cooled mother liquor / salting agent mixture can be evenly distributed into the crystallization chamber, avoiding inconsistent crystal growth caused by uneven local concentration or temperature.
[0008] The crystallization chamber is equipped with a stirring device, which includes a drive motor located at the bottom of the conical part. The output shaft of the drive motor passes through the conical part and is connected to the stirring shaft. The stirring shaft is equipped with several stirring blades, and several through holes are opened on the stirring blades. A support rod is installed on the stirring shaft, and a scraper is connected to the end of the support rod away from the stirring shaft.
[0009] The tank is also connected to a circulation outlet pipeline. The end of the circulation outlet pipeline furthest from the tank body is connected to a circulation tank, and the other side of the circulation tank is connected to the tank body via a circulation inlet pipeline.
[0010] The circulation tank is located at the bottom of the tank body. Both the circulation inlet pipeline and the circulation outlet pipeline are equipped with circulation pumps and control valves. The control valves are electrically connected to the controller.
[0011] Both the cooling chamber and the crystallization chamber are equipped with temperature sensors, which are electrically connected to the controller.
[0012] Preferably, the circulating pumps installed on the circulating inlet and circulating outlet pipelines are centrifugal pumps.
[0013] Preferably, the top of the tank is also connected to a negative pressure exhaust pipe, which is connected to a tail gas absorption tower. This effectively removes the steam / ammonia generated during the crystallization process and prevents the steam from condensing and dripping back from the top of the equipment.
[0014] Preferably, the inclination angle of the spiral guide plate is 45°-60°.
[0015] Preferably, the outlet end of the mother liquor feed pipeline is connected to an atomizing nozzle, and a Y-type filter is installed in front of the atomizing nozzle.
[0016] Preferably, it also includes a seed crystal container, which is located at the top of the cooling chamber. The pipeline connecting the seed crystal container to the container body is equipped with a metering pump. A laser diffraction particle size analyzer is installed on the side wall of the crystallization chamber to monitor the crystal particle size distribution in real time. Both the laser diffraction particle size analyzer and the metering pump are electrically connected to the controller.
[0017] Compared with the prior art, this utility model has the following advantages:
[0018] 1. This utility model clearly divides the tank into a cooling chamber and a crystallization chamber using a baffle plate and a gate valve, thereby achieving temperature gradient control. The cooling chamber focuses on efficient cooling, while the crystallization chamber focuses on crystal growth, ensuring that they do not interfere with each other.
[0019] 2. The cooling coils in the cooling chamber and the external circulation provide efficient indirect cooling. The spiral guide plate extends the flow path of the mother liquor in the cooling chamber, increasing the contact time and uniformity with the cooling medium, resulting in more thorough cooling. Mother liquor atomization significantly increases the specific surface area, substantially enhancing heat and mass transfer efficiency with the cooling medium or salting-out agent. Electromagnetic flow meters and temperature sensors monitor the cooling medium flow rate and temperature in each zone in real time, linking with the controller to achieve precise and dynamic control of the cooling process.
[0020] 3. Quantitative addition of a salting-out agent (such as NaCl) effectively reduces the solubility of ammonium chloride, significantly promotes nucleation and crystal growth, and improves crystallization yield. The through-hole design of the blades greatly reduces stirring resistance, significantly reducing drive energy consumption while ensuring mixing effect. The scraper at the end of the support rod moves closely to the wall of the crystallization chamber, effectively preventing crystal deposition and scaling on the wall and bottom, ensuring heat transfer effect and effective equipment volume, reducing the frequency of kettle cleaning, and extending the operating cycle.
[0021] 4. A laser diffraction particle size analyzer monitors the particle size distribution of crystals within the crystallization chamber, providing feedback for key processes. When a crystal particle size is detected to be smaller than the target value, the controller automatically activates the metering pump in the seed tank to precisely add seed crystals into the crystallization chamber. This effectively suppresses excessive primary nucleation, promotes directional growth of crystals on existing seed crystals, significantly improves the uniformity of product crystal particle size, reduces the proportion of fine crystals, and enhances product quality.
[0022] 5. The crystal slurry at the bottom of the crystallization chamber enters the circulation tank through the circulation outlet pipe, and is then pumped back to the upper part of the crystallization chamber by a centrifugal pump through the circulation inlet pipe. This circulation maintains the full suspension and mixing of the crystal slurry in the crystallization chamber, prevents crystal sedimentation, promotes mass transfer between crystals and solution, and makes the temperature and concentration in the crystallization chamber more uniform. Attached Figure Description
[0023] Figure 1 This is a schematic diagram of the structure of this utility model.
[0024] In the diagram, 1. Tank body; 2. Cooling chamber; 3. Crystallization chamber; 4. Conical section; 5. Baffle plate; 6. Discharge pipe; 7. Mother liquor feed pipe; 8. Salting-out agent feed pipe; 9. Spiral guide plate; 10. Branch pipe; 11. Crystallization liquid distributor; 12. Drive motor one; 13. Stirring shaft; 14. Stirring blades; 15. Support rod; 16. Scraper; 17. Circulating liquid outlet pipe; 18. Circulating tank; 19. Circulating liquid inlet pipe; 20. Circulating pump; 21. Control valve; 22. Negative pressure exhaust pipe; 23. Seed crystal tank; 24. Cooling coil. Detailed Implementation
[0025] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this utility model.
[0026] Example 1
[0027] like Figure 1 As shown, this embodiment provides an ammonium chloride crystallization system, including a crystallizer, a circulating tank 18, and a controller. The crystallizer includes a tank body 1, which has a cooling chamber 2, a crystallization chamber 3, and a conical section 4 arranged sequentially from top to bottom. A baffle plate 5 is arranged between the cooling chamber 2 and the crystallization chamber 3, and a gate valve is installed on the baffle plate 5. The gate valve is electrically connected to the controller. The tank body 1 is connected to a mother liquor inlet pipe 7 and a salting-out agent inlet pipe 8. The outlet end of the mother liquor inlet pipe 7 is connected to an atomizing nozzle, and a Y-type filter is installed in front of the atomizing nozzle. A discharge pipe 6 is arranged at the bottom of the tank body 1, and a discharge valve is installed on the discharge pipe 6. The discharge valve is electrically connected to the controller. A negative pressure exhaust pipe 22 is also connected to the top of the tank body 1, and the negative pressure exhaust pipe 22 is connected to the tail gas absorption tower. This effectively removes the steam / ammonia generated during the crystallization process and prevents the steam from condensing and dripping back after reaching the top of the equipment.
[0028] The cooling chamber 2 is equipped with a cooling coil 24 on the outside of the tank 1. The cooling coil 24 is connected to an external circulator and is equipped with an electromagnetic flow meter. The electromagnetic flow meter is electrically connected to the controller. The cooling chamber 2 is equipped with a spiral guide plate 9 with an inclination angle of 60°.
[0029] A branch pipe 10 is connected to the end of the gate valve away from the cooling chamber 2. The end of the branch pipe 10 away from the gate valve is connected to a crystallizer distributor 11. The crystallizer distributor 11 has a strip structure and an opening at the bottom. The crystallizer distributor ensures that the cooled mother liquor / salting agent mixture can be evenly distributed into the crystallization chamber, avoiding inconsistent crystal growth caused by uneven local concentration or temperature.
[0030] The crystallization chamber 3 is equipped with a stirring device, which includes a drive motor 12 located at the bottom of the conical part 4. The output shaft of the drive motor 12 passes through the conical part 4 and is connected to the stirring shaft 13. The stirring shaft 13 is equipped with a number of stirring blades 14, and a number of through holes are opened on the stirring blades 14. A support rod 15 is installed on the stirring shaft 13, and a scraper 16 is connected to the end of the support rod 15 away from the stirring shaft 13.
[0031] Tank 1 is also connected to a circulation outlet pipe 17. The end of the circulation outlet pipe 17 away from tank 1 is connected to a circulation tank 18. The other side of the circulation tank 18 is connected to tank 1 through a circulation inlet pipe 19.
[0032] The circulation tank 18 is located at the lower part of the tank body 1. The circulation inlet pipe 19 and the circulation outlet pipe 17 are both equipped with circulation pumps 20 and control valves 21. The control valves 21 are electrically connected to the controller. The circulation pumps 20 installed on the circulation inlet pipe 19 and the circulation outlet pipe 17 are both centrifugal pumps.
[0033] Both the cooling chamber 2 and the crystallization chamber 3 are equipped with temperature sensors, which are electrically connected to the controller.
[0034] It also includes a seed crystal tank 23, which is located on top of the cooling chamber 2. The pipeline connecting the seed crystal tank 23 to the tank body 1 is equipped with a metering pump. A laser diffraction particle size analyzer is installed on the side wall of the crystallization chamber 3 to monitor the crystal particle size distribution. Both the laser diffraction particle size analyzer and the metering pump are electrically connected to the controller. The laser diffraction particle size analyzer is a common structure available on the market.
[0035] Working process: The mother liquor enters the tank 1 through the mother liquor feed pipe 7. An atomizing nozzle is installed at the end of the pipe to disperse the mother liquor into fine droplets, increase the contact area with the cooling medium, and enhance the heat exchange effect.
[0036] The mother liquor enters the cooling chamber 2 and is indirectly cooled by the cooling coil 24. The spiral guide plate 9 extends the flow path of the mother liquor to ensure uniform heat exchange. The mother liquor enters the crystallization chamber 3 through the gate valve. The salting-out agent (such as NaCl) is quantitatively injected into the tank 1 through the salting-out agent feed pipe 8. After mixing with the mother liquor, it reduces the solubility of ammonium chloride and promotes crystallization. The mother liquor gradually crystallizes under the action of stirring. Through holes are opened on the stirring blades 14 to reduce stirring resistance and reduce energy consumption. A laser diffraction particle size analyzer monitors the crystal particle size distribution. When the particle size is smaller than the target value, the controller automatically triggers the seed tank, which adds seed crystals to the crystallization chamber 3 through a metering pump to promote crystal growth.
[0037] The crystal slurry at the bottom of crystallization chamber 3 enters the circulation tank 18 through the circulation outlet pipe 17, and is then transported to the top of crystallization chamber 3 by a centrifugal pump, forming an internal circulation. The circulation inlet pipe 19 and circulation outlet pipe 17 are coated with polytetrafluoroethylene (PTFE) to reduce the risk of ammonium chloride crystal adhesion. The concentration of the crystal slurry discharged from the discharge valve is periodically manually checked, and the crystal slurry is discharged when the concentration reaches the set value.
[0038] Although the present invention has been described in detail with reference to the accompanying drawings and preferred embodiments, it is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the present invention, and all such modifications or substitutions should be within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. An ammonium chloride crystallization system, characterized in that, The system includes a crystallizer, a circulating tank (18), and a controller. The crystallizer includes a tank body (1), which is provided with a cooling chamber (2), a crystallization chamber (3), and a conical section (4) from top to bottom. A baffle plate (5) is provided between the cooling chamber (2) and the crystallization chamber (3). A gate valve is provided on the baffle plate (5), and the gate valve is electrically connected to the controller. The tank body (1) is connected to a mother liquor feed pipe (7) and a salting-out agent feed pipe (8). A discharge pipe (6) is provided at the bottom of the tank body (1), and a discharge valve is provided on the discharge pipe (6), which is electrically connected to the controller. The cooling chamber (2) is equipped with a cooling coil (24) on the outside of the tank (1) corresponding to the cooling chamber (2). The cooling coil (24) is connected to the external circulator. An electromagnetic flow meter is installed on the cooling coil (24). The electromagnetic flow meter is electrically connected to the controller. The cooling chamber (2) is equipped with a spiral guide plate (9). A branch pipe (10) is connected to one end of the gate valve away from the cooling chamber (2). A crystallizer distributor (11) is connected to one end of the branch pipe (10) away from the gate valve. The crystallizer distributor (11) is a strip structure and has an opening at the bottom. The crystallization chamber (3) is equipped with a stirring device, which includes a drive motor (12) located at the bottom of the conical part (4). The output shaft of the drive motor (12) passes through the conical part (4) and connects to the stirring shaft (13). The stirring shaft (13) is equipped with several stirring blades (14). Several through holes are opened on the stirring blades (14). A support rod (15) is installed on the stirring shaft (13). A scraper (16) is connected to one end of the support rod (15) away from the stirring shaft (13). The tank body (1) is also connected to a circulation outlet pipe (17). The end of the circulation outlet pipe (17) away from the tank body (1) is connected to a circulation tank (18). The other side of the circulation tank (18) is connected to the tank body (1) through a circulation inlet pipe (19). The circulating tank (18) is located at the bottom of the tank body (1). The circulating inlet pipe (19) and the circulating outlet pipe (17) are both equipped with a circulating pump (20) and a control valve (21). The control valve is electrically connected to the controller. Temperature sensors are installed in both the cooling chamber (2) and the crystallization chamber (3), and the temperature sensors are electrically connected to the controller.
2. The ammonium chloride crystallization system as described in claim 1, characterized in that, The circulating pumps (20) installed on the circulating inlet pipeline (19) and the circulating outlet pipeline (17) are both centrifugal pumps.
3. The ammonium chloride crystallization system as described in claim 1, characterized in that, The top of the tank (1) is also connected to a negative pressure exhaust pipe (22), which is connected to the tail gas absorption tower.
4. The ammonium chloride crystallization system as described in claim 1, characterized in that, The inclination angle of the spiral guide plate (9) is 45°-60°.
5. The ammonium chloride crystallization system as described in claim 1, characterized in that, The outlet end of the mother liquor feed pipeline (7) is connected to an atomizing nozzle, and a Y-type filter is installed in front of the atomizing nozzle.
6. The ammonium chloride crystallization system as described in claim 1, characterized in that, It also includes a seed tank (23), which is located on the top of the cooling chamber (2). The pipeline connecting the seed tank (23) and the tank body (1) is equipped with a metering pump. A laser diffraction particle size analyzer is installed on the side wall of the crystallization chamber (3). Both the laser diffraction particle size analyzer and the metering pump are electrically connected to the controller.