Acetonitrile dehydration equipment and process

Abstract

The invention discloses acetonitrile dehydration equipment and process, and belongs to the technical field of acetonitrile dehydration, the equipment comprises a raw material pretreatment unit, an evaporation kettle, a rectifying tower, a water-carrying agent conveying unit and an integrated water segregator, the raw material pretreatment unit and the water-carrying agent conveying unit are both connected with the evaporation kettle, the evaporation kettle is connected with the rectifying tower, the rectifying tower is connected with the integrated water segregator, and the integrated water segregator is connected with the rectifying tower. The evaporation kettle completes heating and uniform mixing of materials, the water-carrying agent conveying unit achieves accurate and uniform conveying of a water-carrying agent, the integrated water segregator comprises a gas phase inlet pipe, a layering container, a multi-pipeline structure, an electromagnetic valve and an auxiliary layering assembly, and gas phase condensation, liquid layer separation and water-carrying agent recovery are achieved. The energy utilization rate and the material mixing effect are improved, the water separation efficiency and the dehydration quality are improved, all the units are high in synergism and wide in adaptability, deep dehydration of acetonitrile can be stably achieved, and the industrial production requirement is met.

Description

Technical Field

[0001] This invention relates to the field of acetonitrile dehydration technology, and more specifically, to an acetonitrile dehydration device and process. Background Technology

[0002] Acetonitrile, a highly polar organic solvent, has wide applications in chemical synthesis, pharmaceutical intermediate preparation, and electronic cleaning. In these applications, the water content of acetonitrile directly affects its performance and product quality. For example, in pharmaceutical synthesis, excessive water content may lead to incomplete reactions or the formation of byproducts; in electronic cleaning, excessive water content can affect cleaning effectiveness and even damage electronic components. Therefore, dehydration of acetonitrile is an indispensable and crucial step in related production processes.

[0003] Currently, commonly used acetonitrile dehydration technologies in the industry mainly include distillation, adsorption, and extraction. Among them, distillation is one of the most widely used technologies due to its relatively simple operation and ability to achieve continuous production. However, when processing acetonitrile, traditional distillation methods often require multiple distillation operations because acetonitrile and water easily form an azeotropic mixture, making it difficult to achieve deep dehydration through a single distillation. This not only prolongs the processing flow but also consumes a large amount of heating energy, resulting in low processing efficiency and high production costs. While adsorption can reduce the water content of acetonitrile to some extent, the adsorbent it relies on is easily saturated and requires frequent regeneration or replacement. This not only increases the number of operation steps and labor intensity but may also introduce new impurities during regeneration, affecting the purity of acetonitrile. At the same time, adsorbent loss further increases processing costs. Extraction breaks the azeotropic system of acetonitrile and water by adding an extractant, but it requires an additional separation step between the extractant and acetonitrile, prolonging the process chain. Moreover, the selection and dosage control of the extractant are difficult, and if the extractant remains in the acetonitrile, it will adversely affect the subsequent application of the acetonitrile.

[0004] Besides the inherent shortcomings of the process itself, existing acetonitrile dehydration equipment also suffers from numerous structural design flaws. In the raw material pretreatment stage, most equipment only incorporates simple filtration devices without considering preheating the raw materials. This results in the raw materials requiring more heating energy to reach the vaporization temperature after entering the evaporation stage, leading to energy waste. The evaporator, as the core vaporization component, relies heavily on a single stirring structure for mixing the raw materials and the water-carrying agent, resulting in poor mixing uniformity. Some areas have excessively high water-carrying agent concentrations, while others have insufficient concentrations, affecting subsequent vaporization efficiency and distillation results. The water-carrying agent is often directly injected into the evaporator, failing to achieve uniform distribution and further reducing the mixing efficiency between the raw materials and the water-carrying agent. In the water separation stage, existing equipment often employs a simple static stratification method, resulting in low stratification efficiency and a tendency for droplet entrainment due to liquid flow. This leads to incomplete recovery of the water-carrying agent and poor water separation, affecting not only the dehydration quality of acetonitrile but also wasting the water-carrying agent. Summary of the Invention

[0005] The purpose of this invention is to provide an acetonitrile dehydration device and process to solve the above-mentioned problems.

[0006] To achieve the above objectives, an embodiment of the present invention provides the following technical solution: An acetonitrile dehydration device includes a raw material pretreatment unit, an evaporation kettle, a distillation column, a water-carrying agent conveying unit, and an integrated water separator. The raw material pretreatment unit and the water-carrying agent conveying unit are both connected to the evaporation kettle, the evaporation kettle is connected to the distillation column, and the distillation column is connected to the integrated water separator.

[0007] As a further improvement of the present invention, the raw material pretreatment unit includes a raw material storage tank, a filter, a column heat exchanger, and a feed pump. The feed pump inlet is connected to the raw material storage tank, the feed pump outlet is connected to the filter inlet, the filter outlet is connected to the inlet of the column heat exchanger, and the column heat exchanger outlet is connected to the evaporation kettle. The filter is used to filter out solid impurities in the raw material. After being preheated by the column heat exchanger, the raw material enters the evaporation kettle and can be rapidly heated to the vaporization temperature. The heat from the column heat exchanger can utilize the waste heat of the evaporation kettle.

[0008] As a further improvement of the present invention, the evaporation vessel includes a vessel body and a vessel cover installed on the upper end of the vessel body. A heating jacket is provided on the vessel body. The heating jacket is used to circulate the heating medium. The material can be heated quickly and evenly through the circulation of the heating medium, and heat loss can be effectively prevented.

[0009] As a further improvement of the present invention, a drive motor with a gearbox is fixedly installed on the upper end of the kettle cover. The output end of the drive motor is connected to a rotating shaft through a coupling. Multiple sets of stirring blades are fixedly installed on the rotating shaft through a bushing. The drive motor can drive the rotating shaft to rotate, thereby promoting the raw materials and water-carrying agent to be fully and evenly mixed through the stirring blades.

[0010] As a further improvement of the present invention, the water-carrying agent conveying unit includes a water-carrying agent storage tank, a metering pump, a conveying pipe, and a ring distributor. The inlet of the metering pump is connected to the water-carrying agent storage tank, and the outlet of the metering pump is connected to the ring distributor through the conveying pipe. The ring distributor is located inside the reactor body, and multiple atomizing nozzles arranged in a ring array are installed at the lower end of the ring distributor. The metering pump can convey the water-carrying agent into the evaporation reactor, and after being circumferentially distributed by the ring distributor, it is evenly sprayed out through the atomizing nozzles, which can further improve the mixing effect between the raw materials and the water-carrying agent.

[0011] As a further improvement of the present invention, the integrated water separator includes a gas phase inlet pipe, with a stratification container and a water-carrying agent outlet pipe respectively arranged at the upper and lower ends of the gas phase inlet pipe. The stratification container is connected to the top outlet of the distillation column, and the lower end of the water-carrying agent outlet pipe is connected to a water-carrying agent recovery container. A water outlet pipe and a circulation pipe are respectively arranged on the upper side of the gas phase inlet pipe, with the height of the circulation pipe being higher than that of the water outlet pipe. A balance pipe is arranged on the lower side of the gas phase inlet pipe. The circulation pipe is connected to a reflux pipe, and the balance pipe is also connected to the reflux pipe. The reflux pipe is connected to the distillation column. The column is connected to the inlet in the middle. Solenoid valves are installed on the water-carrying agent outlet pipe, water outlet pipe, circulation pipe, and balance pipe. An auxiliary stratification component is installed inside the gas phase inlet pipe. The gas phase after distillation in the distillation column enters the gas phase inlet pipe through the stratification container and condenses. Due to the density difference between the water-carrying agent and water, stratification occurs. Water in the upper layer is released through the water outlet pipe, and the water-carrying agent in the lower layer enters the water-carrying agent recovery container through the water-carrying agent outlet pipe for recovery. At the same time, the residual gas phase can enter the reflux pipe through the circulation pipe and return to the distillation column for distillation.

[0012] As a further improvement of the present invention, the auxiliary layering component includes a wire mesh demister fixedly installed at the water outlet pipe and an arc-shaped hydrophobic plate installed at the water-carrying agent outlet pipe. The wire mesh demister can intercept tiny water-carrying agent droplets entrained in the aqueous phase. After the intercepted water-carrying agent droplets converge, they flow downward along the wire mesh back to the lower layer. The connecting shaft utilizes its hydrophobic properties to cause the tiny water droplets in the water-carrying agent to converge into large water droplets on the surface and flow upward along the plate wall back to the upper layer, thereby achieving aqueous phase separation.

[0013] As a further improvement of the present invention, a connecting shaft is rotatably mounted at the center of the wire mesh demister via a bearing. A drive blade is fixedly mounted on the upper end of the connecting shaft near the layered container. The lower end of the connecting shaft is fixedly connected to the arc-shaped hydrophobic plate. An annular gap is left between the edge of the arc-shaped hydrophobic plate and the inner wall of the gas phase inlet pipe. After the gas phase enters the gas phase inlet pipe through the layered container, it drives the drive blade to rotate. On the one hand, this can promote the condensate to flow along the inner wall of the gas phase inlet pipe under the action of centrifugal force, avoiding turbulence caused by the concentrated impact of liquid on the bottom, and reducing droplet entrainment from the source. On the other hand, the connecting shaft drives the arc-shaped hydrophobic plate to rotate, which can accelerate the downward flow of the water-carrying agent for recovery. At the same time, it can make the small droplets entrained in the water-carrying agent quickly gather into large droplets and float up for separation.

[0014] An acetonitrile dehydration process includes the following steps: S1. After the raw materials are pretreated by the raw material pretreatment unit, they are transported to the evaporation kettle. At the same time, the water-carrying agent conveying unit transports the water-carrying agent to the evaporation kettle to mix with the raw materials. S2. Heat the material to 80-85℃ in the evaporator to vaporize the material and enter the distillation column; S3. After the material is distilled in the distillation column, the gas phase enters the integrated water separator. After condensation, stratification occurs due to the density difference, thus separating water and water-carrying agent.

[0015] As a further improvement of the present invention, the dehydrating agent is dichloromethane, and the mass ratio of dichloromethane to acetonitrile raw material containing water can be adjusted according to the water content of the raw material: when the water content of the raw material is 5%-10%, the mass ratio is 0.8:1; when the water content of the raw material is 10%-15%, the mass ratio is 1.0:1; when the water content of the raw material is 15%-20%, the mass ratio is 1.2:1, and finally the acetonitrile is dehydrated to a water content of less than 1%.

[0016] Compared with the prior art, the advantages of this invention are: (1) In this scheme, a column heat exchanger is set up in the raw material pretreatment unit to preheat the filtered raw material by using the waste heat generated during the operation of the evaporator, which effectively reduces the heating energy consumption of the subsequent evaporation process and reduces the overall energy consumption of the equipment. At the same time, the water-carrying agent conveying unit adopts a structure of ring distributor and atomizing nozzle to atomize the water-carrying agent into fine droplets and spray them evenly into the evaporator. Combined with the rotation of the spiral stirring blade driven by the drive motor, a stirring effect of vertical convection is formed, which greatly increases the contact area between the raw material and the water-carrying agent, promotes the two to be fully and evenly mixed, and avoids problems such as low vaporization efficiency and poor distillation effect caused by uneven mixing, laying a good foundation for the efficient operation of the subsequent dehydration process.

[0017] (2) This solution has high water separation efficiency, stable dehydration quality, and good recovery effect of the water-carrying agent. The auxiliary stratification components set in the integrated water separator improve the water separation effect through multiple dimensions: the gas phase flow drives the blades to rotate, which in turn drives the arc-shaped hydrophobic plate to rotate, causing the condensate to flow along the pipe wall and reducing droplet entrainment; the hydrophobic properties of the arc-shaped hydrophobic plate accelerate the aggregation and floating of water droplets, while promoting the downward flow of the water-carrying agent; the wire mesh demister further intercepts the tiny water-carrying agent droplets entrained in the aqueous phase, ensuring thorough stratification and significantly improving the water separation efficiency. In addition, the design of the balance pipe and the reflux pipe allows the residual gas phase to re-enter the distillation column for further processing, further improving the dehydration quality of acetonitrile and ensuring that the water content of the final product meets the expected requirements; the water-carrying agent can be effectively recovered through the water-carrying agent recovery container, reducing water-carrying agent loss and lowering processing costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the raw material pretreatment unit of the present invention; Figure 3 This is a schematic diagram of the integrated water distributor of the present invention; Figure 4 This is a partial cross-sectional view of the layered container of the present invention; Figure 5 This is a schematic diagram of the structure of the auxiliary layered component of the present invention; Figure 6 This is a schematic diagram of the structure of the water-carrying agent delivery unit of the present invention; Figure 7 This is a partial cross-sectional view of the evaporation vessel of the present invention.

[0019] Explanation of the labels in the diagram: 1. Raw material pretreatment unit; 11. Raw material storage tank; 12. Filter; 13. In-line heat exchanger; 14. Feed pump; 2. Evaporation kettle; 21. Kettle body; 22. Kettle cover; 23. Heating jacket; 24. Drive motor; 25. Rotary shaft; 26. Stirring blades; 3. Distillation column; 4. Water-carrying agent conveying unit; 41. Water-carrying agent storage tank; 42. Metering pump; 43. Conveying pipe; 44. Annular distributor; 45. Atomizing nozzle; 5. Integrated water separator; 51. Gas phase inlet pipe; 52. Layering container; 53. Water-carrying agent outlet pipe; 54. Water-carrying agent recovery container; 55. Water outlet pipe; 56. Circulation pipe; 57. Return pipe; 58. Solenoid valve; 59. Auxiliary layering assembly; 591. Wire mesh demister; 592. Connecting shaft; 593. Arc-shaped hydrophobic plate; 594. Drive blades; 510. Balance pipe. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] Example: Please see Figure 1 An acetonitrile dehydration device includes a raw material pretreatment unit 1, an evaporator 2, a distillation column 3, a water-carrying agent conveying unit 4, and an integrated water separator 5. The raw material pretreatment unit 1 and the water-carrying agent conveying unit 4 are both connected to the evaporator 2. The evaporator 2 is connected to the distillation column 3, and the distillation column 3 is connected to the integrated water separator 5.

[0022] Please see Figure 2 The raw material pretreatment unit 1 includes a raw material storage tank 11, a filter 12, a column heat exchanger 13, and a feed pump 14. The inlet of the feed pump 14 is connected to the raw material storage tank 11, the outlet of the feed pump 14 is connected to the inlet of the filter 12, the outlet of the filter 12 is connected to the inlet of the column heat exchanger 13, and the outlet of the column heat exchanger 13 is connected to the evaporator 2. The filter 12 is used to filter out solid impurities in the raw material. After being preheated by the column heat exchanger 13, the raw material enters the evaporator 2 and can be rapidly heated to the vaporization temperature. The heat from the column heat exchanger 13 can utilize the waste heat of the evaporator 2.

[0023] The raw material pretreatment unit 1 is used to filter, remove impurities, and preheat acetonitrile raw materials, providing qualified raw materials for subsequent vaporization. The raw material storage tank 11 is made of 304 stainless steel, possessing excellent corrosion resistance and sealing properties, allowing for long-term storage of acetonitrile raw materials containing water, preventing contact with external impurities or the introduction of contaminants due to material reactions. The filter 12 has a stainless steel shell and an internal filter element made of polypropylene. Polypropylene filter elements have excellent filtration precision, effectively intercepting solid particulate impurities mixed in the raw material, preventing impurities from entering the subsequent evaporation kettle 2 or distillation column 3, avoiding equipment and pipeline blockage or affecting the purity of the dehydrated acetonitrile. The shell and heat exchange tubes of the in-line heat exchanger 13 are both made of stainless steel. Stainless steel heat exchange tubes have high heat transfer efficiency and are resistant to corrosion from the raw material and waste heat medium. Its core function is to use the waste heat generated during the operation of the evaporator 2 to preheat the filtered raw materials, reduce the heating energy consumption of the subsequent evaporation process, and at the same time enable the raw materials to quickly reach a temperature close to vaporization, thereby improving the evaporation efficiency. It can be connected to the water outlet pipe of the heating jacket 23. The feed pump 14 is a stainless steel centrifugal pump. Both the pump body and the impeller are made of corrosion-resistant stainless steel, which can stably transport raw materials and avoid damage to the pump body due to corrosion of the raw materials. The operation of the feed pump 14 is controlled by the PLC control module integrated in the equipment to realize the start-stop and speed regulation. Its power supply comes from the 220V regulated power supply of the equipment's main power distribution box. By controlling the speed, the raw material conveying volume can be adjusted to meet the needs of different processing scales.

[0024] Please see Figure 7 The evaporation vessel 2 includes a vessel body 21 and a vessel cover 22 installed on the upper end of the vessel body 21. A heating jacket 23 is provided on the vessel body 21. The heating jacket 23 is used to circulate the heating medium. The material can be heated quickly and evenly through the circulation of the heating medium, and heat loss can be effectively prevented.

[0025] A drive motor 24 with a gearbox is fixedly installed on the upper end of the lid 22. The output end of the drive motor 24 is connected to a rotating shaft 25 through a coupling. Multiple sets of stirring blades 26 are fixedly installed on the rotating shaft 25 through a bushing. The drive motor 24 can drive the rotating shaft 25 to rotate, thereby promoting the raw materials and water-carrying agent to be fully and evenly mixed through the stirring blades 26.

[0026] The evaporator 2 is the core component for mixing and vaporizing the raw materials and the dehydrating agent. Both the vessel body 21 and the lid 22 are made of 316L stainless steel. 316L stainless steel has higher corrosion resistance and high-temperature resistance, capable of withstanding temperature and pressure changes during material heating, preventing deformation or corrosion of the vessel body. The heating jacket 23 surrounds the outside of the vessel body 21, also made of stainless steel. Heating media such as heat transfer oil or saturated steam can be circulated inside. Through the circulation of the heating medium, the wall of the vessel body 21 is uniformly heated, thereby transferring heat to the internal material, achieving uniform heating and preventing localized overheating that could lead to raw material decomposition or dehydrating agent loss. The drive motor 24 installed on the upper end of the lid 22 is a three-phase asynchronous motor with a gearbox. The motor housing is made of cast aluminum, providing good heat dissipation, and the gearbox reduces electrical discharge. The motor outputs increased speed and torque to ensure stable stirring force for the stirring blades 26. The start / stop and speed of the drive motor 24 are adjusted by the PLC control module according to the state of the material in the vessel. For example, the speed can be increased in the early stage of material mixing to promote mixing, and the speed can be appropriately reduced in the heating and vaporization stage to avoid material splashing. Its power supply comes from the 380V regulated power supply in the main power distribution box of the equipment. The rotating shaft 25 is made of stainless steel and the surface is polished to reduce material adhesion. The rotating shaft 25 is connected to the output end of the drive motor 24 through a coupling to ensure stable power transmission. The stirring blades 26 are made of stainless steel and are spirally distributed on the rotating shaft 25. The number and angle of the blades are optimized to form an upward and downward convection stirring effect when rotating, which promotes the full and uniform mixing of raw materials and water-carrying agents, and provides a guarantee for the efficient vaporization and distillation of the subsequent processes.

[0027] Please see Figure 6 The water-carrying agent conveying unit 4 includes a water-carrying agent storage tank 41, a metering pump 42, a conveying pipe 43, and a ring distributor 44. The inlet of the metering pump 42 is connected to the water-carrying agent storage tank 41, and the outlet of the metering pump 42 is connected to the ring distributor 44 through the conveying pipe 43. The ring distributor 44 is located inside the vessel body 21. Multiple atomizing nozzles 45 arranged in a ring array are installed at the lower end of the ring distributor 44. The metering pump 42 can convey the water-carrying agent into the evaporation vessel 2, and after being circumferentially distributed by the ring distributor 44, it is evenly sprayed out through the atomizing nozzles 45, which can further improve the mixing effect between the raw materials and the water-carrying agent.

[0028] The desiccant conveying unit 4 is used to accurately and uniformly convey desiccant into the evaporation kettle 2. The desiccant storage tank 41 is made of stainless steel, which has good sealing performance and corrosion resistance, and can store desiccant for a long time without causing deterioration. The metering pump 42 is a stainless steel plunger metering pump. Both the plunger and the pump body are made of corrosion-resistant materials. The metering pump 42 has high-precision flow control capability and can accurately adjust the desiccant delivery volume according to the moisture content of the raw material. Its operation is controlled by a PLC control module, and automatic delivery is achieved by setting the flow parameters. The power supply comes from the 220V regulated power supply of the equipment's main power distribution box. The conveying pipe 43 is a stainless steel pipe, and the pipe diameter is set according to the delivery volume. The design ensures smooth and leak-free delivery of the dehydrating agent. The annular distributor 44 is made of stainless steel and is installed on the upper inner side of the vessel body 21. Its annular structure is adapted to the inner wall of the vessel body 21, which can evenly distribute the dehydrating agent to each outlet of the annular distributor 44. The atomizing nozzle 45 is made of ceramic material. Ceramic material is wear-resistant, corrosion-resistant, and has excellent atomization effect. Multiple atomizing nozzles 45 are arranged in a ring array at the lower end of the annular distributor 44, which can atomize the dehydrating agent into fine droplets and spray them into the vessel body 21, increasing the contact area between the dehydrating agent and the raw material, further improving the mixing uniformity of the two, and avoiding excessively high or low concentrations of dehydrating agent in some areas, which would affect the dehydration effect.

[0029] Please see Figures 3-5 The integrated water separator 5 includes a vapor inlet pipe 51. A stratification container 52 and a water-carrying agent outlet pipe 53 are respectively installed at the upper and lower ends of the vapor inlet pipe 51. The stratification container 52 is connected to the top outlet of the distillation column 3. The lower end of the water-carrying agent outlet pipe 53 is connected to a water-carrying agent recovery container 54. A water outlet pipe 55 and a circulation pipe 56 are respectively installed on the upper side of the vapor inlet pipe 51, with the circulation pipe 56 being higher than the water outlet pipe 55. A balance pipe 510 is installed on the lower side of the vapor inlet pipe 51. The circulation pipe 56 is connected to a reflux pipe 57, and the balance pipe 510 is also connected to the reflux pipe 57. The reflux pipe 57 is connected to the middle inlet of the distillation column 3. Next, solenoid valves 58 are installed on the water-carrying agent outlet pipe 53, water outlet pipe 55, circulation pipe 56, and balance pipe 510. An auxiliary stratification component 59 is installed inside the gas phase inlet pipe 51. The gas phase after distillation in the distillation column 3 enters the gas phase inlet pipe 51 through the stratification container 52 and condenses. Due to the density difference between the water-carrying agent and water, stratification will occur. Water in the upper layer is released through the water outlet pipe 55, and the water-carrying agent in the lower layer enters the water-carrying agent recovery container 54 through the water-carrying agent outlet pipe 53 for recovery. At the same time, the residual gas phase can enter the reflux pipe 57 through the circulation pipe 56 and return to the distillation column 3 for distillation.

[0030] The auxiliary stratification component 59 includes a wire mesh demister 591 fixedly installed at the water outlet pipe 55 and an arc-shaped hydrophobic plate 593 installed at the water-carrying agent outlet pipe 53. The wire mesh demister 591 can intercept tiny water-carrying agent droplets entrained in the aqueous phase. After the intercepted water-carrying agent droplets converge, they flow down along the wire mesh back to the lower layer. The connecting shaft 592 utilizes its hydrophobic properties to cause the tiny water droplets in the water-carrying agent to converge into large water droplets on the surface and flow up along the plate wall back to the upper layer, thereby achieving aqueous phase separation.

[0031] A connecting shaft 592 is rotatably mounted at the center of the wire mesh demister 591 via a bearing. A drive blade 594 is fixedly mounted on the upper end of the connecting shaft 592 near the layered container 52. The lower end of the connecting shaft 592 is fixedly connected to the arc-shaped hydrophobic plate 593. An annular gap is left between the edge of the arc-shaped hydrophobic plate 593 and the inner wall of the gas phase inlet pipe 51. After the gas phase enters the gas phase inlet pipe 51 through the layered container 52, it drives the drive blade 594 to rotate. On the one hand, it can promote the condensate to flow along the inner wall of the gas phase inlet pipe 51 under the action of centrifugal force, avoid the turbulence caused by the concentrated impact of liquid on the bottom, and reduce the entrainment of droplets from the source. On the other hand, the connecting shaft 592 drives the arc-shaped hydrophobic plate 593 to rotate, which can accelerate the downward flow of the water-carrying agent for recovery. At the same time, it can make the small droplets entrained in the water-carrying agent quickly gather into large droplets and float up for separation.

[0032] The integrated water separator 5 is used to condense, separate, and recover the water-carrying agent from the vapor phase after distillation. The vapor inlet pipe 51, separation container 52, water-carrying agent outlet pipe 53, water outlet pipe 55, circulation pipe 56, balance pipe 510, and reflux pipe 57 are all made of stainless steel to ensure resistance to temperature changes and corrosion from the condensate during condensation. The water-carrying agent recovery container 54 is also made of stainless steel and stores the recovered water-carrying agent for subsequent recycling. The solenoid valves 58 are stainless steel body solenoid valves with corrosion-resistant valve cores. Each solenoid valve 58 is connected to a PLC control module via wires. The control module controls the switching based on signals such as the liquid level and separation status within the integrated water separator 5. For example, when the aqueous phase reaches a set height, the solenoid valve 58 on the water outlet pipe 55 opens to drain; when the water-carrying agent reaches the recovery limit, the solenoid valve 58 on the water-carrying agent outlet pipe 53 opens for recovery. The solenoid valves 58 are powered by a 24V DC regulated power supply from the main power distribution box of the equipment to ensure stable operation. In the stratification component 59, the wire mesh demister 591 is made of stainless steel wire mesh, which has good mechanical strength and corrosion resistance. It can intercept tiny water-carrying agent droplets entrained in the aqueous phase. The intercepted droplets converge and flow down the wire mesh back into the lower water-carrying agent. The connecting shaft 592 is made of stainless steel and is rotatably mounted at the center of the wire mesh demister 591 via bearings. Corrosion-resistant bearings are selected to reduce rotational friction. The arc-shaped hydrophobic plate 593 is made of polytetrafluoroethylene (PTFE). PTFE has excellent hydrophobic properties, which allows tiny water droplets entrained in the water-carrying agent to converge into larger droplets on its surface and flow up the plate wall back into the upper aqueous phase. At the same time, the arc-shaped structure design can accelerate the downward flow of the water-carrying agent. The drive blade 594 is made of stainless steel and is installed at the upper end of the connecting shaft 592 near the stratification container 52. When the gas phase enters the gas phase inlet pipe 51 from the stratification container 52, the airflow can drive the drive blade 594 to rotate, thereby driving the connecting shaft 592 and the arc-shaped hydrophobic plate 593 to rotate synchronously.

[0033] It should be noted that components such as liquid level sensors, density sensors, temperature sensors, and condensation equipment can be installed on the integrated water distributor 5 according to actual needs.

[0034] Working principle: When using this acetonitrile dehydration equipment, first turn on the main power supply of the equipment and set the operating parameters of each unit through the PLC control module. In the raw material pretreatment stage, the water-containing acetonitrile raw material stored in the raw material storage tank 11 in the raw material pretreatment unit 1 is transported to the filter 12 by the feed pump 14. After being filtered by the polypropylene filter element inside the filter 12 to remove solid impurities from the raw material, it flows into the column heat exchanger 13. The column heat exchanger 13 uses the residual heat generated in the previous operation of the evaporator 2 to preheat the filtered raw material, so that the raw material temperature is close to the subsequent vaporization temperature. The preheated raw material is transported to the vessel body 21 of the evaporator 2 through the pipeline.

[0035] Simultaneously, the water-carrying agent conveying unit 4 starts, and the metering pump 42, according to the set flow parameters, conveys the water-carrying agent in the water-carrying agent storage tank 41 to the annular distributor 44 through the conveying pipe 43. After being evenly distributed by the annular distributor 44, the water-carrying agent is atomized into fine droplets through multiple atomizing nozzles 45 at its lower end and sprayed into the vessel body 21 of the evaporator 2 to contact the raw materials. Subsequently, the drive motor 24 of the evaporator 2 starts under the control of the PLC control module, driving the rotating shaft 25 to rotate through the coupling. The stirring blades 26 on the rotating shaft 25 rotate synchronously with the rotating shaft 25, stirring the raw materials and water-carrying agent in the vessel body 21 to promote thorough and uniform mixing. At the same time, the heating jacket 23 is circulated with heating medium, which transfers heat to the mixture through the wall of the vessel body 21, causing the material temperature to gradually rise to the set vaporization temperature. The vaporized material forms a gas phase and enters the distillation column 3 through the pipeline between the evaporator 2 and the distillation column 3.

[0036] After the gas phase enters the distillation column 3, it undergoes distillation separation within the column 3 through the action of the trays or packing to remove some water and impurities. The distilled gas phase flows out from the top outlet of the distillation column 3 and enters the layered container 52 of the integrated water separator 5, and then flows into the gas phase inlet pipe 51. Inside the gas phase inlet pipe 51, the gas phase comes into contact with the pipe wall and cools down, condensing to form a liquid. Due to the density difference between the water-carrying agent and water, the condensed liquid gradually separates into layers within the gas phase inlet pipe 51. At this point, the auxiliary stratification component 59 begins to operate: during the gas phase flow, the drive blades 594 rotate, and the drive blades 594, through the connecting shaft 592, drive the arc-shaped hydrophobic plate 593 to rotate synchronously. On the one hand, this causes the condensate to flow along the inner wall of the gas phase inlet pipe 51 under centrifugal force, preventing the liquid from concentrating and impacting the bottom to generate turbulence, thereby reducing droplet entrainment. On the other hand, the rotation of the arc-shaped hydrophobic plate 593 accelerates the downward flow of the lower water-carrying agent, and its hydrophobic properties cause the tiny water droplets entrained in the water-carrying agent to converge into larger water droplets on the surface, which then float upwards along the plate wall to the upper water phase. The wire mesh demister 591 further intercepts the tiny water-carrying agent droplets entrained in the upper water phase. After the intercepted droplets converge, they flow downwards along the wire mesh back to the lower water-carrying agent, ensuring thorough stratification.

[0037] After stratification, the PLC control module controls the solenoid valve 58 on the water outlet pipe 55 to open based on the signal fed back by the liquid level sensor, and the water in the upper layer is discharged from the equipment through the water outlet pipe 55; at the same time, it controls the solenoid valve 58 on the water-carrying agent outlet pipe 53 to open, and the water-carrying agent in the lower layer flows into the water-carrying agent recovery container 54 through the water-carrying agent outlet pipe 53 for recovery, which is convenient for subsequent recycling; the small amount of uncondensed gas phase remaining in the gas phase inlet pipe 51 enters the reflux pipe 57 through the circulation pipe 56, and the balance pipe 510 is used to balance the pressure between the gas phase inlet pipe 51 and the reflux pipe 57, so that the residual gas phase can flow smoothly back to the middle inlet of the distillation column 3 through the reflux pipe 57 for distillation again, ensuring that the acetonitrile is fully dehydrated, and finally obtaining an acetonitrile product with low water content.

[0038] The dehydrating agent is dichloromethane, and the mass ratio of dichloromethane to acetonitrile raw material containing water can be adjusted according to the water content of the raw material: when the water content of the raw material is 5%-10%, the mass ratio is 0.8:1; when the water content of the raw material is 10%-15%, the mass ratio is 1.0:1; when the water content of the raw material is 15%-20%, the mass ratio is 1.2:1, and finally the acetonitrile is dehydrated to a water content of less than 1%.

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0040] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An acetonitrile dehydration device, characterized in that: It includes a raw material pretreatment unit (1), an evaporator (2), a distillation column (3), a water-carrying agent conveying unit (4), and an integrated water separator (5). The raw material pretreatment unit (1) and the water-carrying agent conveying unit (4) are connected to the evaporator (2), the evaporator (2) is connected to the distillation column (3), and the distillation column (3) is connected to the integrated water separator (5).

2. The acetonitrile dehydration equipment according to claim 1, characterized in that: The raw material pretreatment unit (1) includes a raw material storage tank (11), a filter (12), a column heat exchanger (13), and a feed pump (14). The inlet of the feed pump (14) is connected to the raw material storage tank (11), the outlet of the feed pump (14) is connected to the inlet of the filter (12), the outlet of the filter (12) is connected to the inlet of the column heat exchanger (13), and the outlet of the column heat exchanger (13) is connected to the evaporator (2).

3. The acetonitrile dehydration equipment according to claim 2, characterized in that: The evaporation vessel (2) includes a vessel body (21) and a vessel cover (22) installed on the upper end of the vessel body (21). A heating jacket (23) is provided on the vessel body (21), and the heating jacket (23) is used for circulating heating medium.

4. The acetonitrile dehydration equipment according to claim 3, characterized in that: The upper end of the lid (22) is fixedly installed with a drive motor (24) with a reduction gearbox. The output end of the drive motor (24) is connected to a rotating shaft (25) through a coupling. Multiple sets of stirring blades (26) are fixedly installed on the rotating shaft (25) through a bushing.

5. The acetonitrile dehydration equipment according to claim 4, characterized in that: The water-carrying agent delivery unit (4) includes a water-carrying agent storage tank (41), a metering pump (42), a delivery pipe (43), and a ring distributor (44). The inlet of the metering pump (42) is connected to the water-carrying agent storage tank (41), and the outlet of the metering pump (42) is connected to the ring distributor (44) through the delivery pipe (43). The ring distributor (44) is located inside the vessel body (21), and multiple atomizing nozzles (45) arranged in a ring array are installed at the lower end of the ring distributor (44).

6. The acetonitrile dehydration equipment according to claim 5, characterized in that: The integrated water separator (5) includes a gas phase inlet pipe (51), with a stratification container (52) and a water-carrying agent outlet pipe (53) respectively provided at the upper and lower ends of the gas phase inlet pipe (51). The stratification container (52) is connected to the top outlet of the distillation column (3), and the lower end of the water-carrying agent outlet pipe (53) is connected to a water-carrying agent recovery container (54). A water outlet pipe (55) and a circulation pipe (56) are respectively provided on the upper side of the gas phase inlet pipe (51), and the height of the circulation pipe (56) is higher than that of the water outlet pipe (55). A balance pipe (510) is provided on the lower side of the gas inlet pipe (51). The circulation pipe (56) is connected to the reflux pipe (57), and the balance pipe (510) is also connected to the reflux pipe (57). The reflux pipe (57) is connected to the middle inlet of the distillation column (3). Solenoid valves (58) are installed on the water-carrying agent outlet pipe (53), water outlet pipe (55), circulation pipe (56), and balance pipe (510). An auxiliary stratification component (59) is installed inside the gas inlet pipe (51).

7. The acetonitrile dehydration equipment according to claim 6, characterized in that: The auxiliary layering component (59) includes a wire mesh demister (591) fixedly installed at the water outlet pipe (55) and an arc-shaped hydrophobic plate (593) installed at the water-carrying agent outlet pipe (53).

8. The acetonitrile dehydration equipment according to claim 7, characterized in that: The wire mesh demister (591) has a connecting shaft (592) rotatably mounted at its center via a bearing. The upper end of the connecting shaft (592) is fixedly mounted with a drive blade (594) near the layered container (52). The lower end of the connecting shaft (592) is fixedly connected to the arc-shaped hydrophobic plate (593), and an annular gap is left between the edge of the arc-shaped hydrophobic plate (593) and the inner wall of the gas phase inlet pipe (51).

9. An acetonitrile dehydration process, based on the acetonitrile dehydration treatment equipment according to any one of claims 1-8, characterized in that: Includes the following steps: S1. After the raw material is pretreated by the raw material pretreatment unit (1), it is transported to the evaporation kettle (2). At the same time, the water-carrying agent transport unit (4) transports the water-carrying agent to the evaporation kettle (2) and mixes it with the raw material. S2. Heat the material to 80-85°C in the evaporator (2) so that the material vaporizes and enters the distillation column (3). S3. After the material is distilled in the distillation column (3), the gas phase enters the integrated water separator (5). After condensation, the material stratifies due to the density difference, thus achieving the separation of water and water-carrying agent.

10. The acetonitrile dehydration process according to claim 9, characterized in that: The dehydrating agent is dichloromethane, and the mass ratio of dichloromethane to acetonitrile raw material containing water can be adjusted according to the water content of the raw material: when the water content of the raw material is 5%-10%, the mass ratio is 0.8:1; when the water content of the raw material is 10%-15%, the mass ratio is 1.0:1; when the water content of the raw material is 15%-20%, the mass ratio is 1.2:1, and finally the acetonitrile is dehydrated to a water content of less than 1%.

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