Reactor and reaction process for poly-alpha-olefin production

Abstract

The invention discloses a reactor and a reaction method for poly-alpha-olefin production, belongs to the technical field of poly-alpha-olefin production, and aims to solve the problems of existing tank reactors and tubular reactors. The reactor for poly-alpha-olefin production comprises a shell (10) and an internal cavity (11), the internal cavity (11) comprises a pre-polymerization section (12) and a final polymerization section (13) which are arranged on the left side and the right side, a stirring mechanism (14) is arranged in the pre-polymerization section (12), and a plurality of baffle plates (8) are arranged in the final polymerization section (13). According to the reactor for poly-alpha-olefin production, a tank reactor and a tubular reactor are combined, the advantages of the tank reactor and the tubular reactor are reserved, the defects of the tank reactor and the tubular reactor are overcome, and the reactor has the beneficial effects of high operation flexibility, concentrated retention time distribution and the like; the product quality of the poly-alpha-olefin can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of polyalphaolefin production technology, specifically to a reactor for polyalphaolefin production and a reaction method for polyalphaolefin production. Background Technology

[0002] Poly-alpha-olefin (PAO) is an important synthetic base oil. Due to its excellent oxidation stability, thermal stability, and shear stability, it is considered one of the most important Group IV synthetic lubricant base oils. Medium viscosity PAO generally refers to PAO with a kinematic viscosity greater than 10 mmHg at 100°C. 2 / s, less than 40mm 2 Polyalphaolefin oils with a concentration of 1 / s are widely used as gear oils, engine oils, compressor oils, and aviation oils. Their raw material monomers are linear alpha-olefins (commonly 1-decene).

[0003] Metallocenes are organometallic coordination compounds formed by the linkage of transition metals with cyclopentadiene. Metallocene catalysts have the advantage of a single active site, effectively preventing the difficulty in controlling the molecular weight distribution of oligomers caused by varying olefin growth rates at different catalyst sites. However, metallocene catalysts are expensive to manufacture and require stringent polymerization process conditions, which places higher demands on the operability and stability of the equipment.

[0004] Polymerization equipment generally includes batch polymerization units, tubular polymerization units, tower polymerization units, and other special types of polymerization units (such as screw extruder polymerization units). Batch polymerization units are one of the most commonly used polymerization units. Their advantages mainly include: suitability for gas-liquid-solid mixing over a wide viscosity range, high heat transfer efficiency, flexible input of stirring energy, and high operational flexibility, etc. See Chinese patent document CN218167040U, published on December 30, 2022, entitled "Polyalpha-olefin Lubricating Oil Reaction Apparatus". Tubular polymerization units have advantages including high single-pass conversion rate and concentrated residence time distribution of materials within the reactor, etc. See Chinese patent document CN104031202A, published on September 10, 2014, entitled "Polyacrylic Acid Ink Resin and its Preparation Method". However, both types of polymerization units also have disadvantages. For example, batch reactors have a wide distribution of material residence time, while tubular reactors have low mixing efficiency and low operational flexibility. Summary of the Invention

[0005] To address the problems associated with batch reactors and tubular reactors, this invention provides a reactor and reaction method for the production of polyalphaolefins. The reactor for polyalphaolefin production combines the advantages of batch reactors and tubular reactors, while overcoming their disadvantages. It offers benefits such as high operational flexibility and concentrated residence time distribution, effectively improving the product quality of polyalphaolefins.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] A reactor for producing polyalphaolefins, wherein the reactor is a horizontal cylindrical structure, comprising a shell and an internal cavity, the shell extending in a left-right direction, and the internal cavity containing a prepolymerization section and a final polymerization section arranged in the left and right directions, wherein a stirring mechanism is provided in the prepolymerization section, and the prepolymerization section is connected to a catalyst inlet and a raw material inlet, wherein multiple baffles are provided in the final polymerization section, the multiple baffles being arranged at intervals in the left-right direction, the multiple baffles enabling the fluid to flow alternately along the axial and radial directions of the shell in the final polymerization section, and a product outlet is connected to the right end of the final polymerization section.

[0008] A reaction method for producing polyalphaolefins, wherein the reaction method for producing polyalphaolefins employs the aforementioned reactor for producing polyalphaolefins, and the reaction method for producing polyalphaolefins comprises the following steps in sequence:

[0009] Step 1: Inject raw materials into the reactor for the production of poly-α-olefins through the raw material inlet. The raw materials flow to the right end of the final polymerization section. The stirring mechanism is started, and the temperature inside the internal cavity reaches the initial reaction temperature.

[0010] Step 2: Inject the catalyst into the reactor for producing polyalphaolefin through the catalyst feed port and inject the raw material into the reactor for producing polyalphaolefin through the raw material feed port to initiate the polymerization reaction of the raw material and catalyst until the reaction reaches a stable state. The reaction product flows to the right and is discharged from the product outlet.

[0011] The beneficial effects of this invention are as follows: The reactor for polyalphaolefin production combines a batch polymerization unit with a tubular polymerization unit. In the prepolymerization section, the materials are thoroughly mixed by a stirring paddle, and the reactor can adapt to a wider range of operational requirements by a variable frequency motor. Heat exchange coils provide timely heating or cooling for the rapid mixing zone. In the final polymerization section, the backmixing of materials is reduced by channels composed of baffles, resulting in a more concentrated distribution of material residence time. A heat exchange jacket maintains a stable reaction temperature within the final polymerization section. When used for polyalphaolefin production, this invention offers advantages such as high product molecular weight uniformity, a wide range of operational flexibility, and good operational stability. Attached Figure Description

[0012] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0013] Figure 1 This is a schematic diagram of the reactor used for the production of polyα-olefins according to the present invention, where the baffles have an arc-shaped structure.

[0014] Figure 2 This is a schematic diagram of a reactor for producing polyα-olefins according to the present invention, where the baffles have a circular-ring structure.

[0015] Figure 3 It is along Figure 2 Cross-sectional view along the AA direction.

[0016] Figure 4 It is along Figure 2 Cross-sectional view along the BB direction.

[0017] Explanation of reference numerals in the attached figures:

[0018] 1. Catalyst inlet; 2. Raw material inlet; 3. Product outlet; 4. Motor; 5. Output shaft; 6. Agitator; 7. Heat exchange coil; 8. Baffle plate; 9. Heat exchange jacket; 10. Shell; 11. Internal cavity; 12. Prepolymerization section; 13. Final polymerization section; 14. Stirring mechanism; 15. Upper sidewall; 16. Lower sidewall;

[0019] 701. Central axis;

[0020] 801. Center baffle; 802. Edge baffle; 803. Connecting strip; 804. Edge flow channel; 805. Center flow channel. Detailed Implementation

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] For ease of understanding and description, the following description of the present invention uses absolute positional relationships. Unless otherwise specified, the directional term "above" indicates... Figure 1 The direction above, the directional word "down" indicates Figure 1 The lower side of the middle, the directional word "left" indicates Figure 1 The left side of the direction, the directional word "right" indicates Figure 1 The right-hand direction in the text, the directional word "front" indicates perpendicular to. Figure 1 The direction of the paper and pointing inwards from the paper; the directional word "back" indicates perpendicular to the paper. Figure 1 The orientation of the paper is directed towards the outer edge of the paper. This invention is described from the perspective of a reader or user, but the aforementioned directional terms should not be construed as limiting the scope of protection of this invention. Regarding the dimensions and angles of the components, those skilled in the art can determine them specifically based on actual needs or a limited number of experiments.

[0023] like Figure 1 and Figure 2 As shown in the embodiment of the present invention, a reactor for the production of polyalphaolefins is a horizontal cylindrical structure. The reactor for the production of polyalphaolefins includes a shell 10 and an internal cavity 11. The shell 10 extends in the left-right direction (i.e., the axis of the shell 10 extends in the left-right direction). The internal cavity 11 contains a prepolymerization section 12 and a final polymerization section 13 arranged in the left and right directions. A stirring mechanism 14 is provided in the prepolymerization section 12. The prepolymerization section 12 is connected to a catalyst inlet 1 and a raw material inlet 2. A plurality of baffles 8 are provided in the final polymerization section 13. The plurality of baffles 8 are arranged at intervals in the left-right direction. The plurality of baffles 8 enable the fluid to flow alternately in the final polymerization section 13 along the axial direction and radial direction of the shell 10. The right end of the final polymerization section 13 is connected to a product outlet 3.

[0024] The reactor for polyalpha-olefin production adopts a two-stage structure, consisting of a prepolymerization stage 12 (equivalent to a batch reactor) and a final polymerization stage 13 (equivalent to a tubular reactor). This reactor combines the advantages of both batch and tubular reactors while overcoming their disadvantages, offering benefits such as high operational flexibility and concentrated residence time distribution, effectively improving the quality of polyalpha-olefin products.

[0025] like Figure 1 and Figure 2As shown, the stirring mechanism 14 includes a motor 4, an output shaft 5, and a stirring paddle 6 connected in sequence. The stirring paddle 6 is generally a turbine paddle, and its diameter is 0.2 to 0.8 times the diameter of the prepolymerization section 12. Depending on the blade type, the stirring paddle 6 can be a radial flow paddle or an axial flow paddle. The stirring paddle 6 can ensure the uniformity of the material in the prepolymerization section and prevent localized explosive polymerization.

[0026] For example, the impeller 6 can be a radial flow impeller. In this case, the stirring mechanism 14 includes a motor 4, an output shaft 5, and an impeller 6 connected sequentially from top to bottom. The motor 4 is located outside the housing 10, above the housing 10. The output shaft 5 is vertical and passes through the housing 10. The impeller 6 is located inside the prepolymerization section 12. The motor 4 is a variable frequency motor with a speed of 0 r / min to 1200 r / min. The output shaft of the variable frequency motor is connected to the impeller, or it can be connected via a reducer and coupling. The variable frequency capability of the motor 4 makes the input stirring power an adjustable parameter. The stirring power should be adjusted according to the reaction exothermic rate and the material flow rate to ensure thorough stirring.

[0027] The shell 10 is an integral structure. The shell 10 contains a left end wall, a side peripheral wall and a right end wall connected from left to right. The catalyst inlet 1 is located in the middle of the left end wall of the shell 10 in the vertical direction. The catalyst inlet 1 and the stirring paddle 6 are directly opposite each other. The raw material inlet 2 is located at the lower end of the side peripheral wall. The output shaft 5 and the raw material inlet 2 are directly opposite each other vertically. The product outlet 3 is located at the upper part of the right end wall of the shell 10.

[0028] The prepolymerization section 12 is also equipped with a heat exchange coil 7. The heat exchange coil 7 extends in the vertical direction and has a spiral structure. The heat exchange coil 7 is sleeved outside the agitator 6. The upper end of the heat exchange coil 7 is higher than the upper end of the agitator 6, and the lower end of the heat exchange coil 7 is lower than the lower end of the agitator 6.

[0029] The central axis 701 of the heat exchange coil 7 coincides with the axis of the output shaft 5. The number of turns in the heat exchange coil 7 is 5-50. The spiral diameter of the heat exchange coil 7 is 0.2-0.8 times the diameter of the prepolymer section 12. The coil diameter of the heat exchange coil 7 is 10mm-100mm. A cold medium injection device and a hot medium injection device are externally connected to the heat exchange coil 7. The cold medium injection device and the hot medium injection device can inject cold medium or hot medium into the heat exchange coil 7 as needed.

[0030] Along the direction of the agitator 6 from top to bottom, the distance between two adjacent coils of the heat exchange coil 7 gradually decreases; similarly, along the direction of the agitator 6 from bottom to top, the distance between two adjacent coils of the heat exchange coil 7 gradually decreases. That is, in the vertical direction, the coil density in the region of the heat exchange coil 7 corresponding to the agitator 6 is greater than the coil density in the region far from the agitator 6, thereby improving the heat exchange rate in the rapid mixing zone.

[0031] The function of the baffle plate 8 is to ensure that the materials (catalyst and raw materials) are in full contact within the final polymerization section 13, reduce the flow dead zone, and increase the turbulence of the fluid, thereby reducing the degree of backmixing of the materials and ensuring the concentration of the molecular weight distribution of the product.

[0032] like Figure 1 As shown, the baffle 8 can have an arc-shaped structure, with multiple baffles 8 alternately connected to the upper sidewall 15 and lower sidewall 16 of the shell 10. That is, the edge of the baffle 8 contains sequentially connected bowstring and bowback sections. The bowstring sections of the baffle 8 alternately face upwards and downwards, while the bowback sections alternately face downwards and upwards. The bowback sections of the baffle 8 are alternately and sealed and fixedly connected (e.g., by welding) to the upper sidewall 15 and lower sidewall 16 of the shell 10. The spacing between two adjacent baffles 8 can be 0.2 to 5 times the inner diameter of the final polymerization section 13. The baffles 8 can be in an upright state, and their height is 0.5 to 0.98 times the inner diameter of the final polymerization section 13.

[0033] Along the left-to-right direction, the upper ends of two adjacent baffles 8 connected to the lower sidewall 16 of the housing 10 gradually descend. For example, Figure 1 It contains seven baffles 8, arranged from left to right as follows: first baffle, second baffle, third baffle, fourth baffle, fifth baffle, sixth baffle, seventh baffle, and eighth baffle. The upper end of the fourth baffle is lower than the upper end of the second baffle, and the upper end of the sixth baffle is lower than the upper end of the fourth baffle. The baffles 8 can be planar, corrugated, sawtooth, etc., and can be upright or inclined. The setting angle of the baffles 8 should be adjusted and optimized according to the flow field simulation results.

[0034] Or, such as Figures 2 to 4 As shown, the baffle 8 can be in the form of a circular-annular structure. For example, the baffle 8 includes a central baffle 801 and an edge baffle 802 arranged alternately in the left-right direction. The central baffle 801 is circular and is connected to the housing 10 by a connecting strip 803. An edge flow channel 804 is formed between the central baffle 801 and the housing 10. The edge baffle 802 is annular and is connected to the housing 10 by its outer circumference. A central flow channel 805 is formed at the center of the edge baffle 802.

[0035] The prepolymerization section 12 is fitted with a heat exchange jacket 9, which is connected to a heat exchange device. This device circulates heat exchange fluid into the jacket 9, allowing the fluid to exchange heat with the material in the final polymerization section 13. The cooling medium introduced into the jacket 9 provides heat dissipation and cooling. By grouping components and using baffles, zoned temperature control can be achieved, thus maintaining a stable material reaction temperature. The heat exchange jacket 9 can be grouped or integrated, and its heat exchange configuration can be adjusted according to the material flow rate and the molecular weight of the desired product.

[0036] The baffle plate 8 can be solid or hollow. The upper end of the baffle plate 8 can be serrated. When the baffle plate 8 is hollow, the interior of the baffle plate 8 is connected to the interior of the heat exchange jacket 9. Since the baffle plate 8 has a large contact area with the material, the heat exchange efficiency can be improved.

[0037] The reactor for producing polyalphaolefins also includes temperature and pressure sensors disposed in the internal cavity 11 to enable segmented monitoring of reaction temperature and pressure. The ratio of the total length to the inner diameter of the shell 10 is greater than 10, and the ratio of the length of the final polymerization section 13 to the length of the prepolymerization section 12 can be 2.5 to 5 (e.g., 3).

[0038] Since the uniformity of product molecular weight determines product quality, the residence time of materials within the reactor should be concentrated. Tubular polymerization units, which can achieve this, suffer from poor mixing and low operational flexibility, while batch polymerization units, which offer excellent mixing, suffer from inconsistent residence time distribution. In the reactor for polyalpha-olefin production described in this invention, in the prepolymerization section 12, a stirring paddle ensures thorough mixing of materials; a variable frequency motor allows the combined unit to adapt to a wider range of operational requirements; and heat exchange coils provide timely heating or cooling for the rapid mixing zone. In the final polymerization section 13, a channel composed of baffles reduces backmixing, thus concentrating the residence time distribution of materials. A heat exchange jacket maintains a stable reaction temperature within the final polymerization section. The combined reactor of this invention, when used for polyalpha-olefin production, offers advantages such as high product molecular weight uniformity, high operational flexibility, and good operational stability.

[0039] The following describes a reaction method for the production of polyalphaolefins. This method utilizes the reactor described above for polyalphaolefin production and includes the following steps:

[0040] Step 1: Inject the raw material (decene) into the reactor for the production of poly-α-olefin through the raw material inlet 2. The raw material overflows from left to right in stages until it flows to the right end of the final polymerization section 13 and reaches the working liquid level. The stirring mechanism 14 starts stirring the raw material. The motor speed is set according to the stirring requirements until the flow is stable. Then, the heat medium is injected into the heat exchange coil 7 and the temperature of the heat medium in the heat exchange coil 7 is adjusted so that the temperature in the internal cavity 11 reaches the initial reaction temperature.

[0041] Step 2: Inject the catalyst into the reactor for polyalphaolefin production through the catalyst inlet 1 and the raw material into the reactor for polyalphaolefin production through the raw material inlet 2 to initiate the polymerization reaction of the raw material and the catalyst until the reaction reaches a stable state. After the reaction is successfully initiated, switch the heat exchange coil 7 to a cold medium to cool the material and prevent explosive polymerization. The reaction product PAO flows to the right and is discharged from the product outlet 3, which can realize continuous production. The baffle plate 8 can prevent blockage when high viscosity PAO flows, and at the same time ensure that there is no back mixing between the chambers.

[0042] In step 1, a heat medium is introduced into the heat exchange coil 7. The temperature of the heat medium is 0℃~250℃ (e.g., 25℃~250℃), and the initial reaction temperature of the polymerization reaction is 20℃~100℃. The rotational speed of the motor 4 can be 500r / min~800r / min (e.g., 600r / min).

[0043] In step 2, after the reaction is successfully initiated, a cold medium is introduced into the heat exchange coil 7. The temperature of the cold medium is 0℃~20℃, the residence time of the material in the combined reaction device is 1 hour~9 hours, and the reaction pressure is 0.1MPa~0.7MPa. The operation mode is continuous polymerization reaction.

[0044] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, substitutions of equivalent components, or equivalent changes and modifications made within the scope of protection of the present invention, should still fall within the scope of the present invention. Furthermore, the technical features, technical features and technical solutions, and technical solutions in the present invention can be freely combined and used.

Claims

1. A reactor for the production of polyalphaolefins, characterized in that, The reactor for producing polyalphaolefins is a horizontal cylindrical structure. The reactor for producing polyalphaolefins contains a shell (10) and an internal cavity (11). The shell (10) extends in the left and right direction. The internal cavity (11) contains a prepolymerization section (12) and a final polymerization section (13) arranged in the left and right directions. A stirring mechanism (14) is provided in the prepolymerization section (12). The prepolymerization section (12) is connected to a catalyst inlet (1) and a raw material inlet (2). Multiple baffles (8) are provided in the final polymerization section (13). The multiple baffles (8) are arranged at intervals in the left and right direction. The multiple baffles (8) enable the fluid to flow alternately in the axial and radial directions of the shell (10) in the final polymerization section (13). The right end of the final polymerization section (13) is connected to a product outlet (3).

2. The reactor for poly-α-olefin production according to claim 1, characterized in that, The stirring mechanism (14) includes a motor (4), an output shaft (5) and a stirring paddle (6) connected from top to bottom. The motor (4) is located above the housing (10) and the stirring paddle (6) is located inside the prepolymer section (12).

3. The reactor for poly-α-olefin production according to claim 2, characterized in that, The output shaft (5) is in an upright position, the catalyst inlet (1) and the agitator (6) are directly opposite each other, and the output shaft (5) and the raw material inlet (2) are directly opposite each other.

4. The reactor for poly-α-olefin production according to claim 2, characterized in that, A heat exchange coil (7) is also provided in the prepolymer section (12). The heat exchange coil (7) has a spiral structure and is sleeved outside the agitator (6). The upper end of the heat exchange coil (7) is higher than the upper end of the agitator (6), and the lower end of the heat exchange coil (7) is lower than the lower end of the agitator (6).

5. The reactor for poly-α-olefin production according to claim 4, characterized in that, The central axis (701) of the heat exchange coil (7) coincides with the axis of the output shaft (5). The number of turns of the heat exchange coil (7) is 5 to 50. The spiral diameter of the heat exchange coil (7) is 0.2 to 0.8 times the diameter of the prepolymer section (12).

6. The reactor for poly-α-olefin production according to claim 4, characterized in that, Along the direction of the agitator (6) from the top to the agitator (6), the distance between two adjacent coils of the heat exchange coil (7) gradually decreases; along the direction of the agitator (6) from the bottom to the agitator (6), the distance between two adjacent coils of the heat exchange coil (7) gradually decreases.

7. The reactor for poly-α-olefin production according to claim 1, characterized in that, The baffle (8) has an arc-shaped structure, and multiple baffles (8) are alternately connected to the upper sidewall (15) and lower sidewall (16) of the shell (10).

8. The reactor for poly-α-olefin production according to claim 7, characterized in that, Along the direction from left to right, the upper ends of the two adjacent baffles (8) connected to the lower sidewall (16) of the shell (10) gradually descend.

9. The reactor for poly-α-olefin production according to claim 1, characterized in that, The baffle (8) includes a central baffle (801) and an edge baffle (802) arranged alternately in the left and right directions. The central baffle (801) has a circular structure and is connected to the shell (10) through a connecting strip (803). The edge baffle (802) has an annular structure and is connected to the shell (10) by the outer circumference of the edge baffle (802).

10. The reactor for poly-α-olefin production according to claim 7 or 9, characterized in that, The prepolymer section (12) is covered with a heat exchange jacket (9), and the baffle (8) is a hollow structure. The interior of the baffle (8) is connected to the interior of the heat exchange jacket (9).

11. A reaction method for the production of polyα-olefins, characterized in that, The reaction method for producing polyalphaolefins uses the reactor for producing polyalphaolefins as described in claim 4, and the reaction method for producing polyalphaolefins includes the following steps in sequence: Step 1: Inject raw materials into the reactor for the production of poly-α-olefins through the raw material inlet (2). The raw materials flow to the right end of the final polymerization section (13). The stirring mechanism (14) is started, and the temperature in the internal cavity (11) reaches the initial reaction temperature. Step 2: Inject the catalyst into the reactor for producing poly-α-olefins through the catalyst feed port (1) and inject the raw material into the reactor for producing poly-α-olefins through the raw material feed port (2) to initiate the polymerization reaction of the raw material and the catalyst until the reaction reaches a stable state. The reaction product flows to the right and is discharged from the product outlet (3).

12. The reaction method for producing poly-α-olefins according to claim 11, characterized in that, In step 1, a heat medium is introduced into the heat exchange coil (7), the temperature of which is 0℃~250℃, and the initial reaction temperature of the polymerization reaction is 20℃~100℃; In step 2, a cold medium is introduced into the heat exchange coil (7), and the temperature of the cold medium is 0℃~20℃.

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