An agitator for acrylic acid production

Abstract

The utility model relates to acrylic acid production technical field especially relates to a kind of stirring equipment for acrylic acid production, including reation kettle main part, the feed inlet being opened in the reation kettle main part top, the discharge outlet being opened in the reation kettle main part bottom, the stirring inner chamber being formed in the reation kettle, the nitrogen inlet being set in reation kettle main part top, the stirring shaft being rotationally arranged in the stirring inner chamber, the stirring drive motor for driving the stirring shaft rotation being set in reation kettle main part, the cooling mechanism for cooling stirring inner chamber being set in reation kettle main part, the stirring paddle being fixedly arranged on the stirring shaft;The utility model is combined by upper part radial flow stirring paddle and lower part axial flow stirring paddle, realizes staged stirring, when material viscosity is lower in reaction initial stage, upper part radial flow paddle can provide strong shear force, ensures that initiator and other materials are quickly and evenly dispersed, avoids that local concentration is too high to cause violent polymerization, guarantees production safety and product quality.

Description

Technical Field

[0001] This utility model relates to the field of acrylic acid production technology, and in particular to a stirring device for acrylic acid production. Background Technology

[0002] Acrylic acid is a basic chemical raw material, mainly used to prepare acrylates, superabsorbent polymers, etc., and is widely used in coatings, textiles, hygiene products, and water-retaining agents. The core equipment in the production, storage, and subsequent reaction processes of acrylic acid is a stirred reactor. Acrylic acid monomers are chemically extremely reactive and have a strong tendency to polymerize. During stirring, especially during polymerization or esterification reactions, there is a violent exothermic phenomenon, and the viscosity of the material increases rapidly from an initial low viscosity state to a high viscosity state of tens of thousands of centipoises. This series of drastic changes in physicochemical properties places extremely stringent requirements on the stirring equipment. Utility Model Content

[0003] The purpose of this invention is to provide a stirring device for acrylic acid production that addresses the shortcomings of existing technologies, ensuring uniform and stable mixing and heat transfer, and preventing the risks associated with acrylic acid polymerization.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows: a stirring device for acrylic acid production, comprising a reactor body, a feed inlet at the top of the reactor body, a discharge outlet at the bottom of the reactor body, a stirring cavity formed within the reactor body, a nitrogen inlet at the top of the reactor body, a stirring shaft rotatably disposed within the stirring cavity, a stirring drive motor disposed on the reactor body for driving the stirring shaft to rotate, a cooling mechanism disposed within the reactor body for cooling the stirring cavity, and stirring blades fixedly disposed on the stirring shaft. The power output end of the stirring drive motor drives and connects to the stirring shaft. The stirring blades include radial flow stirring blades disposed at the upper part of the stirring shaft and axial flow stirring blades disposed at the lower part of the stirring shaft. The side edge of the axial flow stirring blades has a gap with the inner wall of the stirring cavity.

[0005] A further improvement to the above scheme is that the radial flow stirring blade is a turbine stirring blade.

[0006] A further improvement to the above scheme is that the axial flow stirring blades are configured as anchor-type stirring blades.

[0007] A further improvement to the above scheme is that a scraper is provided on the side edge of the axial flow stirring blade, one side of the scraper is fixedly connected to the side edge of the axial flow stirring blade, and the other side edge of the scraper abuts against the inner wall of the stirring cavity.

[0008] A further improvement to the above scheme is that the cooling mechanism includes a cooling cavity disposed between the inner wall of the reactor body and the stirring chamber, a refrigerant inlet and a refrigerant outlet opened on the cooling cavity, a temperature sensor inserted in the stirring chamber, and an alarm device disposed on the reactor body. The refrigerant inlet and the refrigerant outlet are respectively connected to the liquid outlet and liquid inlet of an external refrigerant supply device through pipelines. The temperature sensor is electrically connected to the alarm device.

[0009] A further improvement to the above solution is that the stirring liner is made of stainless steel, and the inner wall of the stirring liner is electropolished.

[0010] A further improvement to the above scheme is that a mechanical seal structure is provided at the connection between the stirring shaft and the main body of the reactor.

[0011] A further improvement to the above scheme is that the stirring drive motor is a variable frequency motor.

[0012] The beneficial effects of this utility model are as follows: This utility model includes a reaction vessel body, a feed inlet opened at the top of the reaction vessel body, a discharge outlet opened at the bottom of the reaction vessel body, a stirring cavity formed in the reaction vessel, a nitrogen inlet set at the top of the reaction vessel body, a stirring shaft rotatably set in the stirring cavity, a stirring drive motor set on the reaction vessel body for driving the stirring shaft to rotate, a cooling mechanism set in the reaction vessel body for cooling the stirring cavity, and stirring blades fixedly set on the stirring shaft. The power output end of the stirring drive motor drives and connects to the stirring shaft. The stirring blades include radial flow stirring blades set at the upper part of the stirring shaft and axial flow stirring blades set at the lower part of the stirring shaft. The side edge of the axial flow stirring blades has a gap with the inner wall of the stirring cavity. This invention achieves staged mixing through a combination of upper radial flow stirring blades and lower axial flow stirring blades. In the initial stage of the reaction, when the material viscosity is low, the upper radial flow blades provide strong shear force, ensuring rapid and uniform dispersion of initiators and other materials, preventing localized high concentrations that could lead to explosive polymerization. As the reaction progresses and the material viscosity increases dramatically, the lower axial flow blades guide the fluid to generate strong axial circulation, effectively eliminating mixing dead zones and ensuring uniform temperature and concentration within the reactor. Simultaneously, the gap design between the axial flow blades and the inner wall allows for effective operation at high viscosity and, in conjunction with the circulating flow, scours the wall surface to aid heat transfer. The addition of a cooling mechanism further enhances mixing and heat transfer efficiency, fundamentally mitigating the risk of uncontrolled polymerization due to localized overheating, thus ensuring production safety and product quality. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of this utility model.

[0014] Figure 2 This is a cross-sectional view of the present invention.

[0015] Figure 3 This is a schematic diagram of the radial flow stirring blade of this utility model.

[0016] Figure 4 This is a schematic diagram of the axial flow stirring blade of this utility model.

[0017] Explanation of reference numerals in the attached drawings: 1. Reactor body; 11. Feed inlet; 12. Discharge outlet; 13. Nitrogen inlet; 2. Stirring chamber; 3. Stirring shaft; 4. Stirring drive motor; 5. Stirring blade; 51. Radial flow stirring blade; 52. Axial flow stirring blade; 523. Scraper; 6. Cooling mechanism; 61. Cooling cavity; 611. Refrigerant inlet; 612. Refrigerant outlet; 62. Temperature sensor; 63. Alarm device. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings, such as... Figure 1-4 As shown, this utility model provides a stirring device for acrylic acid production, including a reactor body 1, a feed inlet 11 at the top of the reactor body 1, a discharge outlet 12 at the bottom of the reactor body 1, a stirring cavity 2 formed inside the reactor, a nitrogen inlet 13 at the top of the reactor body 1, a stirring shaft 3 rotatably disposed in the stirring cavity 2, a stirring drive motor 4 for driving the stirring shaft 3 to rotate, and stirring blades 5 fixedly disposed on the stirring shaft 3. The power output end of the stirring drive motor 4 drives and connects to the stirring shaft 3. The stirring blades 5 include radial flow stirring blades 51 disposed on the upper part of the stirring shaft 3 and axial flow stirring blades 52 disposed on the lower part of the stirring shaft 3. The side edge of the axial flow stirring blades 52 has a gap with the inner wall of the stirring cavity 2. Both the feed inlet 11 and the discharge outlet 12 of this utility model are provided with valves to facilitate... Operators control the feeding and discharging of materials. The combination of upper radial flow stirring blades 51 and lower axial flow stirring blades 52 achieves staged stirring. In the initial stage of the reaction, when the material viscosity is low, the upper radial flow blades provide strong shear force, ensuring rapid and uniform dispersion of initiators and other materials, preventing excessively high local concentrations that could lead to runaway polymerization. As the reaction progresses and the material viscosity increases sharply, the lower axial flow blades guide the fluid to generate strong axial circulation, effectively eliminating mixing dead zones and ensuring uniform temperature and concentration within the reactor. Simultaneously, the gap design between the axial flow blades and the inner wall allows for effective operation at high viscosity and, in conjunction with the circulating flow, scours the wall surface to aid heat transfer. The addition of a cooling mechanism 6 further enhances mixing and heat transfer efficiency, fundamentally avoiding the risk of runaway polymerization due to localized overheating, thus ensuring production safety and product quality.

[0019] The radial flow stirring blade 51 of this invention is a turbine stirring blade 5, which can generate strong radial jets and intense turbulence at high speeds. It is particularly suitable for the strong dispersion, mass transfer and heat transfer of low-viscosity liquids. In the early stage of acrylic acid reaction, it can disperse the added initiator or comonomer into the entire reactor in a very short time, achieving uniform mixing at the molecular level. This is crucial for controlling the polymerization reaction rate and molecular weight distribution, laying a solid foundation for obtaining high-quality products.

[0020] The axial flow stirring blade 52 of this utility model is set as an anchor-type stirring blade 5. When rotating, it can powerfully push the high-viscosity acrylic polymer material to circulate up and down along the reactor wall and axis. The resulting flow field is very suitable for the overall mixing of high-viscosity, non-Newtonian fluids. It can effectively break the stratification or stagnation phenomenon caused by high viscosity of the material, and ensure that even in the later stage of the reaction, the heat can be uniformly removed, avoiding the accumulation of heat in the reaction center area. It is a key structural guarantee to prevent the later stage of polymerization runaway.

[0021] The axial flow stirring blade 52 of this utility model is provided with a scraper 523 on its side edge. One side of the scraper 523 is fixedly connected to the side edge of the axial flow stirring blade 52, and the other side edge of the scraper 523 abuts against the inner wall of the stirring cavity 2. In this embodiment, the scraper 523 can be made of flexible wear-resistant materials such as polytetrafluoroethylene or rubber. When the axial flow stirring blade 52 rotates, it can scrape off the high viscosity materials or polymer scale adhering to the inner wall of the reactor in real time, keeping the inner wall clean and ensuring that the heat transfer surface has the highest heat exchange efficiency. At the same time, by continuously scraping, the material layer near the wall is forcibly renewed, and the stagnant materials that may face the risk of polymerization due to prolonged heating are brought into the main flow for mixing, thereby effectively preventing local overheating and coking phenomenon of "hanging on the wall", and further improving the operational stability and self-cleaning ability of the equipment.

[0022] The cooling mechanism 6 of this utility model includes a cooling cavity 61 disposed between the inner wall of the reactor body 1 and the stirring chamber 2, a refrigerant inlet 611 and a refrigerant outlet 612 opened on the cooling cavity 61, a temperature sensor 62 inserted in the stirring chamber 2, and an alarm device 63 disposed on the reactor body 1. The refrigerant inlet 611 and the refrigerant outlet 612 are respectively connected to the liquid outlet and liquid inlet of an external refrigerant supply device through pipelines. Valves can be installed on the refrigerant inlet 611 and the refrigerant outlet 612 for control. The temperature sensor 62 and the alarm device 63 are electrically connected. The cooling cavity 61, i.e., the jacket, constitutes the main heat exchange surface, responsible for continuously removing the heat of reaction. The refrigerant is renewed through an external refrigerant supply device. The temperature sensor 62 inserted in the stirring chamber 2 can directly and quickly sense changes in the core temperature of the material. When the temperature exceeds the safety threshold, the alarm device 63 can immediately issue a warning to the operator, effectively preventing safety accidents caused by excessive temperature.

[0023] The mixing tank of this invention is made of stainless steel, and the inner wall of the mixing tank is electropolished. In this embodiment, the stainless steel material is preferably 316L stainless steel, which can effectively resist the corrosion of acrylic acid and avoid the introduction of metal ions due to equipment corrosion, which may catalyze unnecessary side reactions or polymerization. The electropolishing treatment of the inner wall can greatly reduce the adhesion of materials, making it difficult for high-viscosity acrylic polymer materials to adhere to the reactor wall. This facilitates cleaning after the reaction and reduces the risk of decomposition or polymerization due to material adhering to the wall and long-term heating, thus ensuring the purity of the product and the ease of maintenance of the equipment.

[0024] The connection between the stirring shaft 3 and the reactor body 1 of this invention is equipped with a mechanical seal structure, which can effectively seal the dynamic sealing point between the stirring shaft 3 and the reactor body 1, preventing acrylic acid vapor from leaking into the environment. This not only protects the health and safety of the operators but also eliminates the potential risk of vapor forming an explosive mixture with air. At the same time, the good seal also prevents oxygen in the air from entering the reactor, avoiding adverse effects such as inhibition or initiation of polymerization by oxygen.

[0025] The stirring drive motor 4 of this invention is a variable frequency motor, which allows the operator to flexibly and precisely adjust the speed of the stirring shaft 3 according to the real-time changes in the viscosity of the material during the acrylic acid polymerization process. A high speed can be used in the initial low viscosity stage to achieve strong mixing, while a low speed is used in the later high viscosity stage to avoid motor overload, reduce energy consumption, and maintain a stable mixing effect, perfectly matching the needs of the entire reaction process.

[0026] Working principle: Before stirring begins, high-purity nitrogen is introduced into the reactor through nitrogen inlet 13 to displace the air inside. Acrylic acid and catalysts such as initiators are added through feed inlet 11. The variable frequency motor starts, driving the stirring shaft 3 and the staged stirring blades 5 fixed on the shaft to rotate. In the initial stage of the reaction, the material is mainly acrylic acid monomer with low viscosity. The upper radial flow turbine stirring blades 5 play a dominant role, and their high-speed rotation generates strong shearing and turbulence, ensuring that the subsequently added initiators, catalysts, etc., are instantly and uniformly dispersed throughout the reactor. As polymerization proceeds, the viscosity of the material increases sharply, and the lower axial flow anchor stirring blades 5 begin to play a dominant role. Their contours fit tightly against the wall of the stirring cavity 2. It can effectively promote the overall circulation of high-viscosity materials along the reactor wall and axis, completely eliminating the mixing dead zone. At the same time, the scraper 523 on its edge continuously scrapes the inner wall, removes the adhering material in real time and forces the heat exchange boundary layer to renew, ensuring heat transfer efficiency and preventing heat accumulation that could lead to uncontrolled polymerization and explosion. The temperature sensor 62 inserted into the stirring chamber 2 monitors the material temperature in real time and feeds the signal back to the control system. Once the temperature approaches or exceeds the set safety threshold, the control system will immediately increase the flow rate of the refrigerant in the cooling mechanism 6 or reduce the temperature. The refrigerant in the cooling cavity 61 powerfully removes the heat of reaction, ensuring that the reaction always takes place within a safe temperature range. After stirring is completed, the material is discharged through the discharge port 12.

[0027] Of course, the above are only preferred embodiments of this utility model. Therefore, all equivalent changes or modifications made in accordance with the structure, features and principles of this utility model patent application are included in the scope of this utility model patent application.

Claims

1. A mixing device for acrylic acid production, characterized in that: The reactor includes a reactor body (1), a feed inlet (11) at the top of the reactor body (1), a discharge outlet (12) at the bottom of the reactor body (1), a stirring chamber (2) formed inside the reactor, a nitrogen inlet (13) at the top of the reactor body (1), a stirring shaft (3) rotatably disposed inside the stirring chamber (2), a stirring drive motor (4) disposed on the reactor body (1) for driving the stirring shaft (3) to rotate, a cooling mechanism (6) disposed inside the reactor body (1) for cooling the stirring chamber (2), and a stirring blade (5) fixedly disposed on the stirring shaft (3). The power output end of the stirring drive motor (4) drives and connects to the stirring shaft (3). The stirring blade (5) includes a radial flow stirring blade (51) disposed on the upper part of the stirring shaft (3) and an axial flow stirring blade (52) disposed on the lower part of the stirring shaft (3). The side edge of the axial flow stirring blade (52) has a gap with the inner wall of the stirring chamber (2).

2. The stirring equipment for acrylic acid production according to claim 1, characterized in that: The radial flow stirring blade (51) is a turbine stirring blade.

3. The stirring equipment for acrylic acid production according to claim 1, characterized in that: The axial flow stirring blade (52) is configured as an anchor-type stirring blade.

4. The mixing equipment for acrylic acid production according to claim 1, characterized in that: The axial flow stirring blade (52) is provided with a scraper (523) on its side edge. One side of the scraper (523) is fixedly connected to the side edge of the axial flow stirring blade (52), and the other side edge of the scraper (523) abuts against the inner wall of the stirring cavity (2).

5. The mixing equipment for acrylic acid production according to claim 1, characterized in that: The cooling mechanism (6) includes a cooling cavity (61) disposed between the inner wall of the reactor body (1) and the stirring chamber (2), a refrigerant inlet (611) and a refrigerant outlet (612) opened on the cooling cavity (61), a temperature sensor (62) inserted in the stirring chamber (2), and an alarm device (63) disposed on the reactor body (1). The refrigerant inlet (611) and the refrigerant outlet (612) are respectively connected to the liquid outlet and liquid inlet of an external refrigerant supply device through pipelines. The temperature sensor (62) is electrically connected to the alarm device (63).

6. The mixing equipment for acrylic acid production according to claim 1, characterized in that: The mixing liner is made of stainless steel, and the inner wall of the mixing liner is electropolished.

7. The mixing equipment for acrylic acid production according to claim 1, characterized in that: A mechanical seal structure is provided at the connection between the stirring shaft (3) and the reactor body (1).

8. The mixing equipment for acrylic acid production according to claim 1, characterized in that: The stirring drive motor (4) is a variable frequency motor.

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