Intermittent DOP esterification reactor

Abstract

This utility model relates to an intermittent DOP esterification reactor, belonging to the field of reactor technology. It includes a reactor body with a heat exchange jacket; a stirring motor is fixedly installed on the top of the reactor body; a stirring device is rotatably installed inside the reactor body, and the stirring device is driven by the output shaft of the stirring motor; the stirring device includes a central shaft, with helical blades fixedly wound around its outer wall; several stirring tubes are arranged in a circular array around the central shaft, surrounding the helical blades; radial stirring blades are fixed to the stirring tubes; a scraper is fixed to the lower edge of the stirring tubes; this utility model adopts a composite stirring structure, where the helical blades can drive the material to form an axial circulating flow, and the radial stirring blades can enhance radial shearing and radial stirring, improving reaction efficiency and product uniformity; a scraper is installed on the outside of the stirring tubes to scrape off material adhering to the inner wall of the reactor, preventing coking; and a support structure with universal balls is installed at the bottom of the central shaft to improve the stability of equipment operation.

Description

Technical Field

[0001] This utility model relates to an intermittent DOP esterification reactor, belonging to the field of reactor technology. Background Technology

[0002] DOP (dioctyl phthalate) is a widely used general-purpose plasticizer in the industrial field. In China, it is mostly produced using a batch esterification process, which uses phthalic anhydride and octanol as raw materials and completes the esterification reaction in a closed reactor under the action of a catalyst.

[0003] Existing reactors mostly employ conventional paddle or anchor stirring structures, which have the following technical drawbacks: 1. During the esterification reaction, the viscosity of the material system gradually increases. A single stirring method is prone to forming a mixing blind zone. The uneven distribution of material temperature and concentration in the reactor will prolong the reaction cycle and affect the esterification rate and quality uniformity of the product. 2. Highly viscous materials tend to adhere to the inner wall of the reactor, forming a coking layer, which not only significantly reduces the heat transfer efficiency of the heat exchange jacket, but also introduces impurities into the product. Utility Model Content In view of the shortcomings of the prior art, the technical problem to be solved by this utility model is to provide an intermittent DOP esterification reactor, which enhances the mixing effect of high-viscosity materials through a composite stirring structure, improves the uniformity of the product, and has a self-cleaning function on the wall surface. The intermittent DOP esterification reactor of this utility model includes a reactor body, which is a vertical tank structure with a straight cylindrical section at the top and a tapered bottom at the bottom. The reactor body is provided with a heat exchange jacket. A stirring motor is fixedly installed at the top of the reactor body, and a stirring device is rotatably installed inside the reactor body. The stirring device is connected to the output shaft of the stirring motor. The stirring device includes a central shaft, which is vertically arranged along the axial direction of the vessel body; spiral blades are fixedly wound around the outer wall of the central shaft; several stirring tubes are arranged in a circular array around the central shaft; the stirring tubes are bent tubular structures, and their two ends are fixedly connected to the upper and lower ends of the central shaft, respectively. The stirring tube is surrounded by the spiral blades, and several radial stirring blades are arranged and fixed on the outer wall of the stirring tube along the axial direction; a scraper is fixed to the lower edge of the stirring tube, and the edge of the scraper is in contact with the inner wall of the vessel.

[0004] Preferably, the top of the vessel is provided with a gas phase outlet and at least one feed port, the lower part of the heat exchange jacket is provided with a heat transfer oil inlet, the upper part of the heat exchange jacket is provided with a heat transfer oil outlet, the bottom of the vessel is also provided with a discharge port, and an electric valve is installed below the discharge port.

[0005] Furthermore, a support frame is provided at the lower end of the central shaft, and a universal ball is installed at the end of the support frame. The spherical surface of the universal ball abuts against the bottom inner wall of the vessel body to support the stirring device.

[0006] Furthermore, the radial stirring blades are rectangular plate-shaped structures, with multiple radial stirring blades arranged at equal intervals on the outer wall of the stirring tube, for radially tumbling and stirring of the material inside the vessel.

[0007] Furthermore, the heat exchange jacket is arranged around the outside of the straight cylindrical section and the conical bottom section of the vessel body.

[0008] The advantages of this utility model compared with the prior art are: 1. This utility model adopts a composite stirring structure. The spiral blades can drive the material to form an axial circulation flow, realizing the material in the reactor to tumble up and down; the radial stirring blades can enhance radial shearing and radial stirring. The two work together to eliminate the mixing blind zone in the reactor, making the temperature and concentration distribution of high viscosity esterification material more uniform, effectively improving reaction efficiency and product uniformity. 2. A scraper that rotates synchronously with the shaft is installed on the outside of the stirring tube, which can continuously scrape off the material adhering to the inner wall of the vessel and the conical bottom wall, avoiding the material from staying for a long time and getting coked. This not only ensures the heat transfer efficiency of the heat exchange jacket, but also reduces the product impurity problem caused by coking on the wall surface, and reduces the cleaning and maintenance cost of intermittent production. 3. The bottom of the central shaft is equipped with a support structure with universal balls, which can support and limit the lower end of the mixing device, reduce the swaying and vibration when the long shaft is running, and improve the stability of the equipment operation. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the structure of this utility model; Figure 2 This is a cross-sectional view of the present invention; Figure 3 This is a schematic diagram of the stirring device. Figure 4 This is a cross-sectional view of the vessel body.

[0010] In the diagram: 1. Stirring motor; 2. Kettle body; 21. Gas phase outlet; 22. Feed port; 23. Heat transfer oil inlet; 24. Discharge port; 25. Heat exchange jacket; 26. Heat transfer oil outlet; 3. Electric valve; 4. Stirring device; 41. Central shaft; 42. Spiral blade; 43. Radial stirring blade; 44. Scraper; 45. Universal ball; 46. Support frame; 47. Stirring tube. Detailed Implementation

[0011] like Figure 1 As shown, this embodiment is achieved through the following technical solution: The vessel body 2 is a vertical tank structure, with a straight cylindrical section at the top and a tapered bottom at the bottom. A heat exchange jacket 25 is fully enclosed on the outside of the vessel body 2, covering both the straight cylindrical section and the tapered bottom section of the vessel body 2. This jacket is used to introduce heat transfer oil to uniformly heat and control the temperature of the material inside the vessel. A heat transfer oil inlet 23 is located at the bottom of the heat exchange jacket 25, and a heat transfer oil outlet 26 is located at the top of the heat exchange jacket 25. The heat transfer oil adopts a counter-current flow method from bottom to top to improve the overall heat transfer efficiency.

[0012] The top plate of the reactor body 2 has a gas phase outlet 21 and two feed ports 22. The gas phase outlet 21 is located on the side of the center of the top plate and is used to discharge the water vapor and low-boiling-point components generated by the esterification reaction, which are then connected to the subsequent condensation and water separation system. The two feed ports 22 are symmetrically distributed on both sides of the stirring motor 1 and are used to feed different raw materials to meet the needs of intermittent feeding. The bottom of the reactor body 2 is provided with a discharge port 24, which is equipped with an electric valve 3 for automated control of the intermittent discharge of reaction products.

[0013] In this embodiment, the stirring motor 1 is fixed to the top of the vessel body 2, and the output shaft of the stirring motor 1 is connected to the upper end of the stirring device 4. The stirring device 4 is rotatably disposed inside the vessel body 2; the stirring device 4 includes a central shaft 41, which is vertically arranged along the axial direction of the vessel body 2, and the upper end of the central shaft 41 is connected to the stirring motor 1 via a coupling; a spiral blade 42 is fixedly wound around the outer wall of the central shaft 41; when the central shaft 41 rotates, the spiral blade 42 can drive the material to form a circulating flow along the axial direction, lifting the bottom material upward and pushing the surface material downward, thereby enhancing the axial mixing effect inside the vessel.

[0014] A number of stirring tubes 47 are arranged in a circular array around the central shaft 41. The stirring tubes 47 are bent tubular structures, and their two ends are fixedly connected to the upper and lower ends of the central shaft 41, respectively. The stirring tubes 47 surround the outside of the spiral blades 42. A number of radial stirring blades 43 are arranged axially and fixed on the outer wall of the stirring tubes 47. The radial stirring blades 43 are rectangular block structures. When the stirring tubes 47 rotate, the radial stirring blades 43 can apply radial shear force to the material, break the laminar flow state of the highly viscous material, and enhance radial mass transfer and heat transfer.

[0015] A scraper 44 is fixed to the lower edge of the stirring tube 47. The edge of the scraper 44 is in contact with the inner wall of the vessel body 2 and can scrape the inner wall of the conical bottom. During the stirring process, the scraper 44 rotates synchronously with the shaft, continuously scraping the highly viscous material adhering to the wall surface back into the main material, thus preventing the material from being heated and coking for a long time.

[0016] A support frame 46 is fixed to the lower end of the central shaft 41. A universal ball 45 is installed on the outer end of the support frame 46. The spherical surface of the universal ball 45 abuts against the bottom inner wall of the vessel body 2, which can form radial support and limit the lower end of the stirring device 4, reduce the radial sway when the long stirring shaft is running at high speed, reduce equipment vibration and noise, and improve operational stability. At the same time, the universal ball 45 is of the rolling contact type, with small wear during operation and does not hinder the circumferential rotation of the stirring device 4.

[0017] The working process of this embodiment is as follows: 1. During the batch esterification production of DOP, phthalic anhydride, octanol raw materials and catalyst are fed into the reactor body 2 through the feed port 22; heat transfer oil is introduced into the heat exchange jacket 25 through the heat transfer oil inlet 23 to gradually heat up the materials in the reactor. After heat exchange, the heat transfer oil flows out from the heat transfer oil outlet 26 and enters the external circulation heating system. 2. Start the stirring motor 1, which drives the central shaft 41 to rotate at a constant speed. The spiral blades 42 rotate with the shaft to drive the material to form an axial circulation flow. At the same time, the stirring tube 47 drives the radial stirring blades 43 to rotate synchronously, applying radial shear to the material. This ensures that the material is fully mixed under the combined action of axial and radial forces, guaranteeing a uniform temperature and concentration field inside the reactor and promoting a stable esterification reaction. The gaseous water and low-boiling substances generated during the reaction are discharged from the top gaseous outlet 21 and enter the subsequent condensation and water separation device. 3. During the stirring process, the scraper 44 continuously scrapes the inner wall of the conical bottom of the vessel 2, scraping the material adhering to the wall back to the main material body, avoiding the material from staying for a long time and getting coked by heat, and ensuring the heat transfer efficiency of the heat exchange jacket. 4. Once the esterification reaction reaches the set time, open electric valve 3 to discharge the material, and then proceed with the next batch of material feeding to complete the intermittent production cycle.

Claims

1. A batch DOP esterification reactor, characterized in that, Includes a vessel body (2), which is provided with a heat exchange jacket (25); a stirring motor (1) is fixedly installed on the top of the vessel body (2), and a stirring device (4) is rotatably installed inside the vessel body (2), which is connected to the output shaft of the stirring motor (1) via a drive. The stirring device (4) includes a central shaft (41), which is vertically arranged along the axial direction of the vessel body (2); a spiral blade (42) is fixedly wound around the outer wall of the central shaft (41), and several stirring tubes (47) are arranged in a circular array around the central shaft (41). The stirring tubes (47) surround the outer side of the spiral blade (42), and several radial stirring blades (43) are arranged and fixed along the axial direction on the outer wall of the stirring tubes (47); a scraper (44) is fixed at the lower edge of the stirring tube (47), and the edge of the scraper (44) is in contact with the inner wall of the vessel body (2). The lower end of the central shaft (41) is provided with a support frame (46), and the end of the support frame (46) is equipped with a universal ball (45), the spherical surface of the universal ball (45) abutting against the bottom inner wall of the vessel body (2).

2. The batch DOP esterification reactor according to claim 1, characterized in that, The top of the vessel body (2) is provided with a gas phase outlet (21) and at least one feed port (22), the lower part of the heat exchange jacket (25) is provided with a heat transfer oil inlet (23), the upper part of the heat exchange jacket (25) is provided with a heat transfer oil outlet (26), the bottom of the vessel body (2) is also provided with a discharge port (24), and an electric valve (3) is installed below the discharge port (24).

3. The batch DOP esterification reactor according to claim 1, characterized in that, The radial stirring blades (43) are rectangular plate-shaped structures, and multiple radial stirring blades (43) are arranged at equal intervals on the outer wall of the stirring tube (47).

4. The batch DOP esterification reactor according to claim 3, characterized in that, The stirring tube (47) is a bent tube structure, and its two ends are fixedly connected to the upper and lower ends of the central shaft (41).

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