Reaction apparatus for the production of aqueous quaternary ammonium salts

Abstract

This utility model belongs to the field of quaternary ammonium salt production technology, specifically relating to a reaction apparatus for the production of aqueous quaternary ammonium salts. The reaction apparatus includes a chloromethane metering tank, a chloromethane vaporizer, a chloromethane buffer tank, and a quaternary ammonium salt reaction vessel connected in sequence. The top of the quaternary ammonium salt reaction vessel is equipped with pipelines connecting to a tertiary amine preheating tank, a water tank, and a high-level solvent tank. The top of the quaternary ammonium salt reaction vessel is also equipped with a pipeline connecting to a condenser, and the bottom of the condenser is equipped with a pipeline returning to the quaternary ammonium salt reaction vessel. This utility model's reaction apparatus for the production of aqueous quaternary ammonium salts employs a combined stirring paddle with vertical baffles and an axially ventilated stirrer, significantly increasing the gas-liquid contact area and accelerating the quaternization reaction process. The use of nitrogen gas blown in from the bottom of the vessel greatly reduces the flow resistance of the material during discharge, achieving smooth material discharge. Simultaneously, impurity filtration and solvent removal and recovery can be completed within the same reaction vessel, simplifying post-processing steps.

Description

Technical Field

[0001] This utility model belongs to the field of quaternary ammonium salt production technology, specifically relating to a reaction device for the production of aqueous quaternary ammonium salt. Background Technology

[0002] Aqueous quaternary ammonium salts, such as dodecyl dimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, and octadecyl trimethyl ammonium chloride, are an important class of cationic surfactants widely used in sterilization, textile softeners, and oilfield chemicals. Their industrial production hinges on the quaternization reaction of tertiary amines with alkylating agents such as chloromethane and benzyl chloride in an aqueous or alcohol-water mixture. In practical applications and production, quaternary ammonium salts are typically present as aqueous solutions with a certain solid content. This is because: the synthesis of quaternary ammonium salts is itself carried out in an aqueous or water-alcohol system, and directly preparing an aqueous solution eliminates the need for post-solid processing steps such as drying and pulverizing, simplifying the process; secondly, the vast majority of quaternary ammonium salts are ultimately used in aqueous systems, directly supplying aqueous solutions eliminates the need for users to undergo the cumbersome process of dissolving solid products (especially since dissolving long-chain quaternary ammonium salts requires heating and high-speed stirring), greatly improving application convenience.

[0003] Current production of aqueous quaternary ammonium salts generally relies on batch stirred reactors. Although a certain amount of alcohol is introduced to replace water as a solvent to reduce the viscosity of the system, the amount of alcohol introduced is limited due to safety and production costs. Therefore, as the reaction proceeds, the concentration of quaternary ammonium salts increases continuously, which can easily lead to "dead zone" or "idle running" and result in a large mixing dead zone. At the same time, the increase in viscosity limits the contact area between gaseous chloromethane and tertiary amines, resulting in a decrease in the reaction rate. Furthermore, high-viscosity materials are difficult to discharge and leave a lot of residue. Utility Model Content

[0004] To overcome the problems of large stirring dead zone and limited gas-liquid contact area in the existing technology, this utility model provides a reaction device for the production of aqueous quaternary ammonium salts.

[0005] The technical solution of this utility model is as follows: A reaction apparatus for producing aqueous quaternary ammonium salts includes a chloromethane metering tank, a chloromethane vaporizer, a chloromethane buffer tank, and a quaternary ammonium salt reaction vessel connected in sequence. The top of the quaternary ammonium salt reaction vessel is provided with pipelines connecting to a tertiary amine preheating tank, a water tank, and a solvent high-level tank. The top of the quaternary ammonium salt reaction vessel is also provided with a pipeline connecting to a condenser. The bottom of the condenser is provided with a pipeline returning to the quaternary ammonium salt reaction vessel. A stirrer is provided inside the quaternary ammonium salt reaction vessel, and vertical baffles are provided on the inner wall of the vessel.

[0006] Preferably, the agitator is a shaft-ventilated agitator, consisting of a drive assembly, a stirring shaft, and stirring blades. The stirring shaft has a hollow tubular structure with an air inlet at the upper end connected to a chloromethane buffer tank and a gas distributor at the lower end.

[0007] Preferably, the gas distributor is umbrella-shaped with gas outlet holes distributed on its surface to ensure that chloromethane is sprayed out evenly.

[0008] Preferably, the stirring blades are fixed to the surface of the stirring shaft and arranged in three layers from top to bottom: the upper layer is a three-bladed propeller-type stirring paddle, the middle layer is a slanted-blade turbine paddle, and the bottom layer is an anchor-type stirring paddle. The gap between the anchor-type stirring paddle and the inner wall of the vessel is controlled at 10-15cm. The anchor-type stirring paddle fits the contour of the inner wall of the vessel to minimize the material retention space between the blades and the vessel wall, and avoid the material from staying for a long time, which may cause local overheating or incomplete reaction. At the same time, in order to avoid local turbulence, guide holes are provided on the blades. The blade inclination angle of the slanted-blade turbine paddle is 40-60°.

[0009] Preferably, the chloromethane metering tank is connected to the chloromethane delivery pipeline and is located on the weighbridge to control the intake of chloromethane and prevent waste caused by insufficient or excessive reaction. Furthermore, the chloromethane metering tank relies on pressure to ensure that the chloromethane is in a liquid state. Therefore, a pressure detection device and a pressure relief valve are installed on the top of the tank to ensure safety.

[0010] Preferably, the condenser material outlet is provided with a pipeline connected to a solvent recovery tank, and the bottom of the solvent recovery tank is provided with a pipeline connected to a quaternary ammonium salt reactor for the purpose of realizing solvent recovery and utilization; the condenser material outlet is also connected to a vacuum system; the condenser refrigerant is cooling water.

[0011] Preferably, the top of the quaternary ammonium salt reactor is provided with an outlet connected to the tail gas pipeline, and the bottom of the quaternary ammonium salt reactor is connected to the discharge pipeline. The discharge pipeline is provided with a branch that returns to the quaternary ammonium salt reactor, and a circulation pump is provided on the branch. Furthermore, the discharge port is also connected to a nitrogen pipeline. When the system viscosity is high and it is difficult to discharge the material, nitrogen gas is introduced from the bottom of the quaternary ammonium salt reactor and bubbled to discharge the material. This can generate upward disturbance at the bottom of the reactor, break the material sediment layer, reduce the material flow resistance, and promote the material to enter the discharge port more smoothly.

[0012] Preferably, the outlet of the circulating pump is equipped with a filter to filter out any solid impurities present and prevent them from being carried into the final product.

[0013] Preferably, the quaternary ammonium salt reactor has a jacketed structure, with the lower inlet of the jacket connected to the circulating water pipeline and the upper outlet of the jacket connected to the water tank jacket; furthermore, the circulating water route in the device is as follows: the circulating water from the circulating water system flows sequentially through the quaternary ammonium salt reactor jacket, the water tank jacket, the tertiary amine preheating tank jacket, the gasifier shell side, and finally flows back to the circulating water system, and all of the above devices are equipped with temperature detection devices.

[0014] Preferably, the solvent high-level tank is connected to the solvent delivery pipeline for delivering solvent from the pipeline area, and the solvent is a low-carbon alcohol.

[0015] In the aforementioned reaction apparatus for producing aqueous quaternary ammonium salt, pressure detection devices are installed in the chloromethane vaporizer, chloromethane buffer tank, solvent high-level tank, solvent recovery tank, and quaternary ammonium salt reactor. Pressure relief valves are also installed on the top of the solvent high-level tank, solvent recovery tank, chloromethane vaporizer, and quaternary ammonium salt reactor. Liquid level gauges are also installed in the solvent high-level tank, solvent recovery tank, and quaternary ammonium salt reactor to monitor the liquid level inside the apparatus.

[0016] Specifically, the working principle of the aforementioned reaction apparatus for producing aqueous quaternary ammonium salts is as follows: The chloromethane metering tank is placed on a weighbridge to weigh and measure the amount of liquid chloromethane used, avoiding excessive addition and waste. The liquid chloromethane enters the chloromethane vaporizer, is converted into a gaseous state, and is temporarily stored in the chloromethane buffer tank. This process stabilizes the gas pressure. At the same time, the tertiary amine preheating tank heats the tertiary amine raw material to a suitable reaction temperature, reducing the initial viscosity. Water and alcohol solvents are stored in water tanks and solvent high-level tanks, respectively, to prepare for feeding. Meanwhile, nitrogen is used to purge air from the device. When the reaction is started, the raw materials (tertiary amine, water, and alcohol solvent) enter the quaternary ammonium salt reactor through the corresponding pipelines, the temperature is raised to 40-60℃, and nitrogen gas is introduced. The pressure is controlled and maintained at 0.3-0.5MPa. Stirring is started to ensure that the liquid materials are mixed evenly. Then, chloromethane is introduced into the quaternary ammonium salt reactor. Chloromethane enters the hollow shaft of the shaft-ventilated stirrer through the pipeline from the chloromethane buffer tank and is sprayed out from the umbrella-shaped gas distributor at the bottom. The drive component of the stirrer drives the three-layer stirring blades (upper three-blade propeller, middle inclined blade turbine, and bottom anchor stirring blade) to rotate. With the help of the vertical baffles on the inner wall of the reactor, the gas-liquid mixing effect is enhanced to ensure that the materials are evenly distributed. At the same time, the circulation pump is turned on to start the large circulation. During the circulation process, the filter is used to filter out any solid impurities that are generated or present. During the reaction, the tertiary amine and chloromethane in the quaternary ammonium salt reactor undergo a quaternization reaction at a suitable temperature. As the reaction progresses, the system releases heat. The vaporized alcohol and water enter the condenser and are condensed before returning to the bottom of the quaternary ammonium salt reactor. At this time, the three layers of stirring blades continue to play a role, working together to ensure that the high-viscosity system is mixed evenly and to avoid the occurrence of stirring dead zones. After the reaction is complete, the pressure is released, the vacuum pump in the vacuum system is turned on, and the vacuum valve is adjusted to evaporate the alcohol portion of the reaction system. Under reduced pressure, the boiling point of the solvent decreases, and alcohol solvents (such as ethanol, isopropanol, etc.) will preferentially vaporize. The vapor enters the condenser through the top pipe. During the heating process, the temperature and vacuum level inside the reactor are continuously monitored to ensure that the temperature does not exceed the thermal decomposition temperature of the quaternary ammonium salt to prevent the product quality from being affected. When the temperature inside the quaternary ammonium salt reactor stops rising and there is no significant increase in liquid in the solvent recovery tank, the vent valve is slowly opened to restore the vacuum level inside the reactor to atmospheric pressure. Product samples are then taken for testing. Based on the test results, hot water is added from the water tank to adjust to the required solid content. Stirring is continued until homogeneous. The connection valve between the nitrogen pipeline and the discharge port is opened, and nitrogen enters from the bottom of the reactor. Bubbling and disturbance break up the material sediment layer, reduce flow resistance, and facilitate the smooth entry of the material into the discharge pipeline for discharge, which then transports the material to the subsequent processing section.

[0017] Compared with the prior art, the beneficial effects of this utility model are as follows: (1) This utility model adopts a three-layer combined stirring paddle with a vertical baffle, combined with a shaft-ventilated stirring and an umbrella-shaped gas distributor, which significantly improves the gas-liquid contact area, accelerates the quaternization reaction process, and solves the problems of uneven mixing and low reaction rate in traditional devices.

[0018] (2) This utility model uses nitrogen bubbling to assist in material discharge. The nitrogen gas blown in from the bottom of the vessel effectively "fluidizes" the deposited material, greatly reducing the flow resistance and achieving smooth material discharge. At the same time, impurity filtration and solvent removal and recovery can be completed in the same reactor, simplifying the post-processing steps. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the reaction apparatus for producing aqueous quaternary ammonium salts according to this utility model; Figure 2 This is a schematic diagram of the stirrer in this utility model.

[0020] In the diagram: 1. Chloromethane metering tank; 2. Quaternary ammonium salt reactor; 21. Stirrer; 211. Drive assembly; 212. Stirring shaft; 213. Stirring blades; 214. Gas distributor; 22. Vertical baffle; 3. Solvent high-level tank; 4. Water tank; 5. Tertiary amine preheating tank; 6. Chloromethane buffer tank; 7. Chloromethane vaporizer; 8. Solvent recovery tank; 9. Condenser; 10. Nitrogen pipeline; 11. Tail gas pipeline; 12. Discharge pipeline; 13. Chloromethane delivery pipeline; 14. Solvent delivery pipeline; 15. Vacuum system; 16. Circulation pump; 17. Filter. Detailed Implementation

[0021] The specific technical solution of this utility model will be further described below with reference to the accompanying drawings.

[0022] like Figures 1-2 As shown, the reaction apparatus for producing aqueous quaternary ammonium salt according to this utility model includes a chloromethane metering tank 1, a chloromethane vaporizer 7, a chloromethane buffer tank 6, and a quaternary ammonium salt reaction vessel 2 connected in sequence. The top of the quaternary ammonium salt reaction vessel 2 is provided with a pipeline connected to a tertiary amine preheating tank 5, a water tank 4, and a solvent high-level tank 3. The top of the quaternary ammonium salt reaction vessel 2 is also provided with a pipeline connected to a condenser 9. The bottom of the condenser 9 is provided with a pipeline for returning to the quaternary ammonium salt reaction vessel 2. A stirrer 21 is provided inside the quaternary ammonium salt reaction vessel 2. The stirrer 21 is a shaft-ventilated stirrer. A vertical baffle 22 is provided on the inner wall of the vessel.

[0023] The agitator 21 consists of a drive assembly 211, an agitator shaft 212, and agitator blades 213. The agitator shaft 212 is a hollow tubular structure with an air inlet at the upper end connected to the chloromethane buffer tank 6, and a gas distributor 214 at the lower end. The gas distributor 214 is umbrella-shaped with air outlets distributed on its surface. The agitator blades 213 are fixed to the surface of the agitator shaft 212 and are arranged in three layers from top to bottom: the upper layer is a three-bladed propulsion agitator, the middle layer is a slanted blade turbine agitator, and the bottom layer is an anchor-type agitator.

[0024] The chloromethane metering tank 1 is connected to the chloromethane delivery pipeline 13, and the chloromethane metering tank 1 is located on the weighbridge; the solvent high-level tank 3 is connected to the solvent delivery pipeline 14.

[0025] The material outlet of condenser 9 is connected to a pipeline that connects to solvent recovery tank 8. The bottom of solvent recovery tank 8 is connected to a pipeline that connects to quaternary ammonium salt reactor 2. The material outlet of condenser 9 is also connected to vacuum system 15.

[0026] The quaternary ammonium salt reactor 2 has an outlet at the top connected to the tail gas pipeline 11, and a discharge port at the bottom connected to the discharge pipeline 12. The discharge pipeline 12 has a branch that returns to the quaternary ammonium salt reactor 2, and a circulation pump 16 is installed on the branch. The discharge port is also connected to the nitrogen pipeline 10. The nitrogen pipeline 10 also has a branch that connects to the top of the quaternary ammonium salt reactor 2. A filter 17 is installed at the outlet of the circulation pump 16.

[0027] The operation of the shaft-ventilated agitator in the above-mentioned device is the same as described in CN105478047A, and will not be repeated here.

[0028] The working principle of the aforementioned reaction apparatus for producing aqueous quaternary ammonium salts is as follows: The chloromethane metering tank 1 is placed on a weighbridge to weigh and measure the amount of liquid chloromethane used, avoiding excessive addition and waste. The liquid chloromethane enters the chloromethane vaporizer 7, is converted into a gaseous state, and is temporarily stored in the chloromethane buffer tank 6. This process can stabilize the gas pressure. At the same time, the tertiary amine preheating tank 5 heats the tertiary amine raw material to a suitable reaction temperature, reducing the initial viscosity. Water and alcohol solvents are stored in the water tank 4 and solvent high-level tank 3, respectively, to prepare for feeding. Meanwhile, nitrogen is used to remove air from the device. When the reaction is started, the raw materials (tertiary amine, water, and alcohol solvent) enter the quaternary ammonium salt reactor 2 through the corresponding pipelines, the temperature is raised to 40-60℃, the volume ratio of water to alcohol solvent is controlled at 7:3, and nitrogen gas is introduced to control the pressure to be maintained at 0.3-0.5MPa. The stirrer 21 is turned on to ensure that the liquid materials are mixed evenly. Then, chloromethane is introduced into the quaternary ammonium salt reactor 2. The chloromethane enters the hollow shaft of the shaft-ventilated stirrer 21 through the chloromethane buffer tank 6 and is sprayed out from the umbrella-shaped gas distributor 214 at the bottom. The drive component 211 of the stirrer 21 drives the three-layer stirring blades 213 (upper three-blade propeller, middle inclined blade turbine, and bottom anchor stirring blade) to rotate. With the help of the vertical baffle 22 on the inner wall of the reactor, the gas-liquid mixing effect is enhanced to ensure that the materials are evenly distributed. At the same time, the circulation pump 16 is turned on to start the large circulation, and the filter 17 is used to filter the solid impurities generated or present during the circulation process. During the reaction, the tertiary amine and chloromethane in the quaternary ammonium salt reactor 2 undergo a quaternization reaction at a suitable temperature. As the reaction progresses, the system releases heat. The vaporized alcohol and water enter the condenser 9 and are condensed before returning to the bottom of the quaternary ammonium salt reactor 2. At this time, the three-layer stirring blades 213 continue to play a role in ensuring that the high-viscosity system is mixed evenly and avoiding the occurrence of stirring dead zones. After the reaction is complete, the pressure is released, the vacuum pump in the vacuum system 15 is turned on, and the vacuum valve is adjusted to evaporate the alcohol portion in the reaction system. Under reduced pressure, the boiling point of the solvent decreases, and alcohol solvents (such as ethanol, isopropanol, etc.) will preferentially vaporize. The vapor enters the condenser 9 through the top pipe. During the heating process, the temperature and vacuum degree inside the reactor are continuously monitored to ensure that the temperature does not exceed the thermal decomposition temperature of the quaternary ammonium salt and to prevent the product quality from being affected. When the temperature inside the quaternary ammonium salt reactor 2 no longer rises and there is no significant increase in liquid in the solvent recovery tank 8, the vent valve is slowly opened to restore the vacuum degree inside the reactor to normal pressure, and product samples are taken for testing. According to the test results, hot water is added from the water tank 4 to adjust to the required solid content. Stirring is continued until uniform. The connection valve between the nitrogen pipeline 10 and the discharge port is opened, and nitrogen enters from the bottom of the reactor. Bubbling and disturbance break the material sediment layer, reduce flow resistance, and facilitate the material to enter the discharge pipeline 12 for discharge. The material is then transported to the subsequent processing section. The solvent in the solvent recovery tank 8 can be reused in the quaternary ammonium salt synthesis process after testing. In the aforementioned apparatus, circulating water is used to provide the operating heat. The circulating water route is as follows: circulating water from the circulating water system first enters the jacket of the quaternary ammonium salt reactor 2, then flows sequentially through the jacket of the water tank 4, the jacket of the tertiary amine preheating tank 5, and the shell side of the chloromethane vaporizer 7, finally flowing back to the circulating water system. The quaternary ammonium salt reactor 2, water tank 4, tertiary amine preheating tank 5, and chloromethane vaporizer 7 are all equipped with temperature detection devices to monitor the temperature of materials or media within each device in real time, ensuring temperature stability during the reaction and material pretreatment processes. Furthermore, the chloromethane vaporizer 7, chloromethane buffer tank 6, solvent high-level tank 3, solvent recovery tank 8, and quaternary ammonium salt reactor 2 are all... Pressure detection devices are installed to monitor the internal pressure of each device in real time, preventing abnormal pressure from causing safety risks or affecting the reaction process. Pressure relief valves are installed on the top of solvent high-level tank 3, solvent recovery tank 8, chloromethane vaporizer 7, and quaternary ammonium salt reactor 2. When the pressure in the corresponding device exceeds the safety threshold, the pressure relief valve automatically opens to release pressure, preventing damage to the device due to overpressure and ensuring production safety. Liquid level gauges are installed in solvent high-level tank 3, solvent recovery tank 8, and quaternary ammonium salt reactor 2. The liquid level gauges can monitor the liquid level of materials in each device in real time, making it easy for operators to grasp the material inventory, accurately control the feeding, reaction, and discharging processes, and ensure stable operation of the device.

Claims

1. A reaction apparatus for producing aqueous quaternary ammonium salts, characterized in that, The reactor includes a chloromethane metering tank (1), a chloromethane vaporizer (7), a chloromethane buffer tank (6), and a quaternary ammonium salt reactor (2) connected in sequence. The top of the quaternary ammonium salt reactor (2) is equipped with a pipeline connected to the tertiary amine preheating tank (5), the water tank (4), and the solvent high-level tank (3). The top of the quaternary ammonium salt reactor (2) is also equipped with a pipeline connected to the condenser (9). The bottom of the condenser (9) is equipped with a pipeline that returns to the quaternary ammonium salt reactor (2). A stirrer (21) is installed inside the quaternary ammonium salt reactor (2). The stirrer (21) is a shaft-ventilated stirrer. A vertical baffle (22) is installed on the inner wall of the reactor.

2. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 1, characterized in that, The stirrer (21) consists of a drive assembly (211), a stirring shaft (212), and stirring blades (213). The stirring shaft (212) is a hollow tubular structure with an air inlet at the upper end connected to the chloromethane buffer tank (6) and a gas distributor (214) at the lower end.

3. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 2, characterized in that, The gas distributor (214) is umbrella-shaped with gas outlet holes distributed on its surface.

4. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 2, characterized in that, The stirring blades (213) are fixed on the surface of the stirring shaft (212) and are arranged in three layers from top to bottom: the upper layer is a three-bladed propulsion stirring blade, the middle layer is a slanted blade turbine blade, and the bottom layer is an anchor-type stirring blade.

5. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 1, characterized in that, The chloromethane metering tank (1) is connected to the chloromethane delivery pipeline (13), and the chloromethane metering tank (1) is located on the weighbridge.

6. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 1, characterized in that, The material outlet of the condenser (9) is provided with a pipeline connected to the solvent recovery tank (8), the bottom of the solvent recovery tank (8) is provided with a pipeline connected to the quaternary ammonium salt reactor (2), and the material outlet of the condenser (9) is also connected to the vacuum system (15).

7. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 1, characterized in that, The top of the quaternary ammonium salt reactor (2) is provided with an outlet connected to the tail gas pipeline (11), and the bottom of the quaternary ammonium salt reactor (2) is connected to the discharge pipeline (12). The discharge pipeline (12) is provided with a branch that returns to the quaternary ammonium salt reactor (2), and a circulation pump (16) is provided on the branch. The discharge port is also connected to the nitrogen pipeline (10).

8. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 7, characterized in that, The nitrogen pipeline (10) is also provided with a branch line that connects to the top of the quaternary ammonium salt reactor (2).

9. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 7, characterized in that, A filter (17) is installed at the outlet of the circulating pump (16).

10. The reaction apparatus for producing aqueous quaternary ammonium salts according to claim 1, characterized in that, The solvent high-level tank (3) is connected to the solvent delivery pipeline (14).

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