E-POE three-pot continuous polymerization production process innovation structure design

Abstract

Adopt the innovative structure of three polymerizers in series in the continuous polymerization process, according to the different pressure, temperature and viscosity of each polymerizer, adopt different design. The catalyst and reactant inlet of 1# polymerizer is set in the lower part of the polymerizer, adopt static mixer inserted into the close distance of the paddle, the reactant is dispersed uniformly by the paddle, optimize the design of internal cooling pipe and stirrer, select the radial flow of multi-layer two-blade twisted paddle, solve the problem of glue hanging and blocking between the cooling pipe of the reactor; 2#, 3# polymerizer selects the frame shaft composed of internal and external double helical ribbon paddle and square tube, solves the problem of glue holding shaft, sticking, wall sticking and heat exchange, prolongs the operation cycle of polymerization reaction, reduces the gel in the reactor, and expands the existing shortcomings in the production process, speeds up the realization of large-scale industrial production of polyolefin elastomer products in China, meets the domestic demand, improves the overall technical level of China's polyolefin related industry, and becomes an important growth point of high-end polyolefin market.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and relates to a production process and equipment for the continuous production of E-POE polyolefin elastomers. It employs an innovative structure with three different reactors and agitators to adapt to process requirements of varying pressures, temperatures, and viscosities, thereby extending the equipment's operating cycle and increasing production capacity. Background Technology

[0002] There are three core issues in E-POE production: First, the catalyst. The research and development or matching of metallocene catalysts is the most critical issue. Second, α-olefins, which account for approximately 60% of the profit in the POE industry chain. The α-olefin raw materials required for E-POE mainly refer to octene, C8, and other similar raw materials. Third, the E-POE polymerization process, including the process flow for scaling up production, various equipment, parameters, etc., is the focus of this patent.

[0003] The domestic method for continuous production of polyolefin elastomers involves first mixing ethylene, long-chain α-olefins, solvents, and co-catalysts to obtain a mixed raw material. This mixed raw material and catalyst are then fed into a first loop reactor and a second loop reactor connected in series for polymerization to obtain the polyolefin elastomer reaction solution. The reaction solution is washed, filtered, and dried to obtain the polyolefin elastomer.

[0004] There is another domestic research and development project on a new type of polyolefin material. It uses ethylene as the sole raw material and is synthesized using a special catalyst. It does not require the addition of α-olefin monomers such as 1-octene. The project is called Vinyl Polyolefin Elastomer (EPOE). It uses ethylene as a raw material to prepare polyolefin elastomers that meet the requirements of toughening polypropylene, photovoltaic encapsulation films and compatibilizing recycled mixed plastics. EPOE is significantly superior to traditional polyolefins in terms of production cost and product performance. The challenges are expanding production capacity and solving the problem of high viscosity mixing.

[0005] The SCLARIRTECH process abroad includes a tubular reactor and a continuous stirred tank reactor, with a minimum residence time of 2 minutes, a polymerization temperature of approximately 300°C, and a pressure of 10-20 MPa.

[0006] The foreign Exxpol high-pressure polymerization technology is divided into catalyst preparation, polymerization, separation and post-treatment. In the Exxpol process design, the heptane-magnesium / aluminoxane suspension is under ultra-high pressure. The solid catalyst is introduced at different positions in the high-pressure reactor to ensure that the catalyst slurry can be added to the reactor at 100-200 MPa. In order to ensure better dispersion of the catalyst under high pressure, Exxon uses undehydrated silica gel with a particle size of 0.3-1.0 as the support for magnesium / aluminoxane. The size of the catalyst particles is controlled by silica gel particles. The pain point is that the pressure is too high.

[0007] Domestic polymer polymerization reactors employ a double-row, six-unit heat exchange tube bundle, with an upper outer ring tube for convergence and high-level inlet and outlet. The agitator uses a five-layer, two-blade CBY-E impeller and a single-layer A310 impeller. The drawback is that when the reaction viscosity is around 1,000–3,000 mPa·s, after 3–6 months of operation, severe gel buildup occurs on the agitator and internal cooling tubes, resulting in high gel content and affecting product quality. See also the gel buildup situation with multiple double-row or 12-unit 3x3 tube bundle heat exchange tube bundles and impellers. Figure 1 , Figure 2 , Figure 3 As shown.

[0008] To achieve efficient and continuous production, this patent proposes an innovative polymerization reactor structure in a three-reactor continuous polymerization process. This structure addresses issues such as agglomeration, sticking to the shaft, and sticking to the walls caused by solvent swelling, allowing the polymerization reaction to continue for an extended period. It also reduces gelation within the reactor and other shortcomings in the production process. This will accelerate the large-scale industrial production of polyolefin elastomer products in my country, meet domestic demand, and improve the overall technological level of my country's polyolefin-related industries. Summary of the Invention

[0009] The innovative structure of the three-tandem continuous polymerization reactors allows for adjustment of the reactor volume based on reaction residence time and flow rate. The liquid level is controlled at 70-85% of the volume, with space at the top for gas evaporation. The evaporated gas is cooled by an external condenser and then reintroduced into the reactor to regulate temperature. The catalyst and reactants are mixed via a static mixer at the lower side of the reactor and then directly connected to the impeller, ensuring rapid dispersion and uniform distribution of the reactants in the solution. Different reactor structures and agitator combinations are used to achieve continuous polymerization depending on the pressure, temperature, and viscosity of each reactor. The E-POE three-tandem continuous polymerization process and structure are described in (see...). Figure 4 , Figure 5 The reaction liquid enters from the lower side of reactor #1, overflows from the upper side opening, enters from the bottom of reactor #2, overflows from the upper side opening, enters from the upper side of reactor #3, and exits from the bottom, thus satisfying the total residence time of the polymerization reaction.

[0010] The No. 1 polymerization reactor is designed for volumes ranging from 1 to 60 m³, pressures from 0.8 to 1.0 MPa, and viscosities from 0.1 to 0.5 Pa·s. Due to the low viscosity, the agitator is a combination of multi-layered two-blade variable-angle torsion impellers and a bottom four-blade inclined impeller to enhance radial flow. The upper and lower layers of the two-blade variable-angle torsion impellers are staggered by 60°, relying on the radial force generated by the impellers to wash away the adhesive adhering to the tubes and reactor wall. To prevent self-polymerization between the heat exchange tubes, six sets of single-row tubes consisting of three inverted U-shaped risers are used to increase the tube spacing and the heat exchange area inside the reactor. The inverted U-shaped risers enter and exit the polymerization reactor through a central pipe, which is then connected to the two outer ring pipes at the bottom of the reactor.

[0011] The No. 2 polymerization reactor is suitable for volumes ranging from 1 to 60 m³, pressures from 0.8 to 1.6 MPa, and viscosities from 0.5 to 4.0 Pa·s. Due to the high viscosity, the agitator uses a central, through-shaft composite section composed of four square tubes. This eliminates the flow dead zone at the central shaft, improving the shaft's rigidity and torsional resistance. Combined with a multi-layered, double-ribbed impeller, the outer helical ribbon propels the liquid upwards, while the inner helical ribbon propels it downwards. An innovative feature is the use of a small gap between the impeller and the reactor wall to solve problems of adhesive sticking to the shaft, adhering to the walls, and promptly cleaning the adhesive on the reactor wall, thus improving the heat exchange efficiency of the jacket.

[0012] The structure of polymerization reactor #3 is suitable for volumes ranging from 1 to 60 m³, pressures from 10 to 20 MPa, and viscosities from 4.0 to 20 Pa·s. Due to the high pressure and viscosity and poor flowability, a top-side feed and bottom-discharge design is adopted. The reactor body structure features a slender shape with a height-to-diameter ratio of 3 to 5, reducing the thickness of the cylinder to increase the heat exchange area and efficiency of the jacket. The agitator assembly can be based on the structure of reactor #2, with the difference being that the frame shaft of the agitator is lengthened and the number of layers of helical ribbon blades is increased. The rotation direction of the helical ribbon blades is opposite to that of the helical ribbon in reactor #2; the outer helical ribbon pushes the liquid downwards, while the inner helical ribbon pushes it upwards, promoting circulation within the reactor and facilitating the discharge of highly viscous materials. A gear pump is added at the reactor outlet to further propel the flow of materials within the pipe. Attached Figure Description

[0013] Figure 1 : Structural diagram of domestic polymer polymerization reactor

[0014] Figure 2 : 6 sets of double-row tube bundle internal cooling tube assemblies, and a five-layer two-bladed CBY-E propeller + a single-layer A310 propeller, left Figure 1 Upper blade adhesive application status, left Figure 2 The condition of the glue coating on the upper part of the internal cooling pipe, right Figure 2 Low-level blade adhesive application, right Figure 1 The condition of the adhesive coating on the lower part of the internal cooling pipe.

[0015] Figure 3 :Left Figure 1 Layout diagram of 12 sets of internal cooling tubes, left Figure 2 Cold pipe bundle adhesive application status, right Figure 2 The condition of the upper agitator blades coated with adhesive, right Figure 1 The condition of adhesive coating on the lower part of the internal cooling tube bundle.

[0016] Figure 4 Structure of three E-POE continuous polymerization reactors

[0017] The left image shows reactor #1, the middle image shows reactor #2, and the right image shows reactor #3. A gear pump has been added to the inlet pipeline of reactor #3.

[0018] Figure 5 Cross-sectional views of three polymerization reactors and the structure of the agitator.

[0019] The left image shows the No. 1 reactor with a jacketed body, consisting of 6 sets of inverted U-shaped internal cooling tubes composed of 3 single-row vertical pipes, multi-layer two-blade arrangement, and refrigerant inlet and outlet ring pipe arrangement; the middle image shows the No. 2 reactor and the right image shows the No. 3 reactor, both with jacketed bodies, inner and outer double-helical ribbon blades, and a combined cross-section frame shaft structure composed of four square tubes; the difference between the No. 2 and No. 3 reactors is that the inner and outer helical directions are different, as are the cylinder diameter, agitator diameter, and height. Specific implementation party

[0020] The innovative structure of the three-tandem continuous polymerization reactors allows for adjustment of the reactor volume based on reaction residence time and flow rate. The liquid level is controlled at 70-85% of the volume, with space at the top for gas evaporation. The evaporated gas is cooled by an external condenser and then reintroduced into the reactor to regulate temperature. The catalyst and reactants are mixed via a static mixer at the lower side of the reactor and then directly connected to the impeller, ensuring rapid dispersion and uniform distribution of the reactants in the solution. Different reactor structures and agitator combinations are used to achieve continuous polymerization depending on the pressure, temperature, and viscosity of each reactor. The E-POE three-tandem continuous polymerization process and structure are described in (see...). Figure 4 , Figure 5 The reaction liquid enters from the lower side of reactor #1, overflows from the upper side opening, enters from the bottom of reactor #2, overflows from the upper side opening, enters from the upper side of reactor #3, and exits from the bottom, thus satisfying the total residence time of the polymerization reaction.

[0021] Table 1: Functions and operating conditions of each reactor Reactor Function Operating conditions Viscosity Key control parameters First Cauldron Prepolymerization (initiating reaction) Low temperature (50-80℃), low pressure lower Catalyst concentration, ethylene / α-olefin ratio The second cauldron Main aggregation (chain growth) Medium temperature (80-120℃), medium pressure rise Residence time, gradient addition of comonomers Third pot Termination reaction and chain structure adjustment High temperature (120-150℃), high pressure Reaching peak Terminator addition and molecular weight distribution adjustment

[0022] The No. 1 polymerization reactor is designed for volumes ranging from 1 to 60 m³, pressures from 0.8 to 1.0 MPa, and viscosities from 0.1 to 0.5 Pa·s. Due to the low viscosity, the agitator is a combination of multi-layered two-blade variable-angle torsion impellers and a bottom four-blade inclined impeller to enhance radial flow. The upper and lower layers of the two-blade variable-angle torsion impellers are staggered by 60°, relying on the radial force generated by the impellers to wash away the adhesive adhering to the tubes and reactor wall. To prevent self-polymerization between the heat exchange tubes, six sets of single-row tubes consisting of three inverted U-shaped risers are used to increase the tube spacing and the heat exchange area inside the reactor. The inverted U-shaped risers enter and exit the polymerization reactor through a central pipe, which is then connected to the two outer ring pipes at the bottom of the reactor.

[0023] The No. 2 polymerization reactor is suitable for volumes ranging from 1 to 60 m³, pressures from 0.8 to 1.6 MPa, and viscosities from 0.5 to 4.0 Pa·s. Due to the high viscosity, the agitator uses a central, through-shaft composite section composed of four square tubes, which eliminates the flow dead zone at the central shaft, improving the shaft's rigidity and torsional resistance. Combined with a multi-layered, double-ribbed impeller, the outer helical ribbon propels the liquid upwards, while the inner helical ribbon propels it downwards. An innovative feature is the use of a small gap between the impeller and the reactor wall to solve problems of adhesive sticking to the shaft, adhering to the walls, and promptly cleaning the adhesive on the reactor wall, thus improving the heat exchange efficiency of the jacket.

[0024] The structure of polymerization reactor #3 is suitable for volumes ranging from 1 to 60 m³, pressures from 10 to 20 MPa, and viscosities from 4.0 to 20 Pa·s. Due to the high pressure and viscosity and poor flowability, a top-side feed and bottom discharge method is adopted. The reactor body structure adopts a slender shape with a height-to-diameter ratio of 3 to 5, reducing the thickness of the cylinder to increase the heat exchange area and efficiency of the jacket. The agitator assembly can be based on the structure of reactor #2, the difference being that the frame shaft of the agitator is lengthened and the number of spiral ribbon blades is increased. The spiral ribbon blades rotate in the opposite direction to the spiral ribbon in reactor #2; the outer spiral ribbon pushes the liquid downwards, while the inner spiral ribbon pushes it upwards, promoting circulation within the reactor and facilitating the discharge of highly viscous materials.

[0025] The reactants in reactor #3 have high viscosity and poor flowability. A gear pump is added to the outlet pipeline of the reactor to drive the flow of materials inside the pipeline.

[0026] in conclusion: The innovative structural design of the E-POE three-stage continuous polymerization reactor can meet the pressure, temperature and viscosity requirements of different reactors, and is suitable for expanding production scale. The No. 1 reactor effectively solves problems such as glue buildup between the agitator and the internal cooling tube, high gel content, and wall adhesion in traditional processes by improving the design of the agitator and internal cooling tube, thus extending the equipment's operating cycle and improving product quality. ·The No. 2 and No. 3 reactors adopt a slender reactor body with a height-to-diameter ratio greater than 3. They are equipped with a central shaftless composite section consisting of 4 square tubes and an inner and outer double spiral ribbon agitator to solve the problems of mixing high-viscosity materials and material sticking to the shaft. This design provides important technical support for the industrial production of polyolefin elastomers in my country, and is expected to promote technological progress in my country's polyolefin-related industries and meet domestic demand for high-performance polyolefin elastomers.

Claims

1. The innovative structure of the E-POE three-tandem continuous polymerization process utilizes different combinations of volumes, vessel structures, and agitators based on the varying pressure, temperature, viscosity, and reaction residence time of each vessel to achieve continuous polymerization. In each vessel, the liquid level is controlled at 70-85% of its volume, with space at the top for gas evaporation. The evaporated gas is cooled by an external condenser and then reintroduced into the vessel to regulate temperature. The catalyst and reactants from vessel #1 are mixed via a static mixer at the lower side port and then directly connected to the impeller, allowing the reactants to be quickly dispersed by the impeller and evenly distributed in the solution. The reaction liquid overflows from the upper side port, enters the bottom of vessel #2, overflows again from the upper side port, enters the upper side of vessel #3, and exits at the bottom, satisfying the total residence time requirement for the polymerization reaction.

2. The polymerization reactor structure of the E-POE three-reactor continuous polymerization production process according to claim 1, characterized in that: The structure of the No. 1 polymerization reactor is suitable for volumes ranging from 1 to 60 m³, pressures ranging from 0.8 to 1.0 MPa, and viscosity ranges from 0.1 to 0.5 Pa·s. Due to the low viscosity, the agitator is a combination of multi-layer two-blade variable-angle twisted impellers and a bottom four-blade inclined impeller to enhance radial flow. The upper and lower layers of the two-blade variable-angle twisted impellers are arranged at a 60° offset. The radial force generated by the impellers washes away the adhesive adhering to the tubes and reactor wall. Six sets of single-row tubes composed of three inverted U-shaped risers are used to expand the tube spacing, increase the heat exchange area inside the reactor, and prevent the formation of self-polymers between the heat exchange tubes. The inverted U-shaped risers enter and exit the polymerization reactor through a connecting pipe, and are connected to the two outer ring pipes at the bottom of the reactor.

3. The polymerization reactor structure of the E-POE three-reactor continuous polymerization production process according to claim 1, characterized in that: The No. 2 polymerization reactor is suitable for volumes ranging from 1 to 60 m³, pressures ranging from 0.8 to 1.6 MPa, and viscosity ranges from 0.5 to 4.0 Pa·s. Due to the high viscosity, the agitator uses a central, non-through-shaft composite section shaft composed of four square tubes, which can eliminate the flow dead zone at the central shaft, improve the shaft's rigidity and torsional resistance. It is equipped with a multi-layered inner and outer double-ribbed impeller, where the outer helical ribbon pushes the liquid upward and the inner helical ribbon pushes the liquid downward. The innovative feature is the use of a small gap between the impeller and the reactor wall to solve the problems of adhesive sticking to the shaft, adhesion, and wall adhesion, allowing for timely cleaning of adhesive on the reactor wall and improving the heat exchange effect of the jacket.

4. The polymerization reactor structure of the E-POE three-reactor continuous polymerization production process according to claim 1, characterized in that: The structure of polymerization reactor #3 is suitable for volumes ranging from 1 to 60 m³, pressures ranging from 10 to 20 MPa, and viscosity ranges from 4.0 to 20 Pa·s. Due to the high pressure and viscosity and poor fluidity, it adopts a top-side feeding and bottom-discharging method. The reactor body structure adopts a slender shape with a height-to-diameter ratio of 3 to 5, reducing the thickness of the cylinder and increasing the heat exchange area and heat exchange effect of the jacket. The agitator combination can be based on the structure of reactor #2, the difference being that the frame shaft of the agitator is lengthened and the number of spiral ribbon blades is increased. The spiral ribbon blades rotate in the opposite direction to the spiral ribbon in reactor #2. The outer spiral ribbon presses the liquid downwards, while the inner spiral ribbon pushes it upwards, promoting circulation flow inside the reactor and facilitating the discharge of high-viscosity materials.

5. The polymerization reactor structure of the E-POE three-reactor continuous polymerization production process according to claim 1, characterized in that: The reactants in reactor #3 have high viscosity and poor flowability. The problem of poor flowability is solved by adding gear pumps to the inlet and outlet pipelines of the reactor.

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