Apparatus and method for supercritical fluid assisted devolatilization to produce olefin-based polymers

Abstract

The application provides a device and a method for producing olefin-based polymers through supercritical fluid-assisted devolatilization, the device comprising a reaction unit, a devolatilization unit and a refining and recovery unit connected in sequence; the devolatilization unit comprises a static devolatilization module, which comprises a booster pump, a mixer, a heater and a static devolatilizer connected in sequence; the refining and recovery unit comprises a light component removal column and a heavy component removal column connected in sequence; the light component removal column is directly or indirectly connected to the mixer; the device uses light components obtained from the light component removal column for assisted devolatilization, thereby improving the devolatilization effect while reducing the devolatilization conditions; the method is improved on the basis of the solution polymerization method, uses a supercritical assisted devolatilization agent to produce a polymer product with low VOC content and high quality, has a simple process and low energy consumption, and is mild compared with the traditional high-temperature and high-vacuum devolatilization method, thereby greatly solving the problems of degradation and yellowing in the polymer post-processing process.

Description

Technical Field

[0001] This invention belongs to the field of polymer engineering, specifically relating to an apparatus and method for producing olefin-based polymers using supercritical fluid-assisted devolatilization. Background Technology

[0002] Polyolefins and polyolefin elastomers are a large class of widely used plastic products. In particular, polyolefin elastomers (POEs) produced by solution polymerization using a single active center catalytic system can combine the elasticity of rubber and the thermoplasticity of plastics. They have performance advantages that general-purpose polyolefin resins cannot match, and have become a high-value-added polyolefin product widely used in high-end fields such as polymer modification, photovoltaics, footwear materials, and cables.

[0003] Currently, processes used for solution polymerization to produce polyolefins and polyolefin elastomers include Dow Chemical's Dowlex and Insite processes, ExxonMobil's Compact process, and SK's Nexlene process. There is still significant room for improvement in the conversion rates of ethylene and comonomers, and increasing the single-pass conversion rate is crucial for reducing energy consumption and equipment investment. Furthermore, the following issues still exist after the solution polymerization reaction concludes:

[0004] (i) After the polymerization reaction is completed, the solid content of the polymerization reaction liquid is generally only 5% to 30%, and there are a large amount of unconverted raw materials and solvents.

[0005] (ii) Traditional polymer solution devolatilization uses thermal methods, i.e., high temperature and high vacuum conditions. Some systems use dynamic scraping or extruders to fully combine evaporation and surface renewal to remove monomers to a low level. However, this also leads to significant degradation of the polymer under high temperature and long residence time, resulting in a significant decrease in weight-average molecular weight, a widening of molecular weight distribution, and a decrease in comonomer insertion rate. Furthermore, it can also lead to a significant increase in the color number of product particles and a more frequent appearance of particles with black spots, which seriously affects product quality and application scenarios.

[0006] (iii) Due to the high solvent content in the polymerization reaction solution, the resulting polymer melt has a high viscosity, reaching 4000-10000 Pas in some cases. After vacuum flash evaporation, a large number of bubbles are trapped in the devolatilizer, which makes it difficult to meet the conveying requirements of the bottom pump. Furthermore, as the melt pump is pressurized, the bubbles break or are reabsorbed by the melt, causing an impact on the pump. The pump outlet pressure fluctuates significantly, affecting the service life of the melt pump.

[0007] Therefore, during the engineering scale-up process, there are bottlenecks in the selection and manufacturing of equipment such as heat exchangers, devolatilizers, and melt pumps, making the selection of a suitable devolatilization process particularly crucial.

[0008] CN112292201A describes a method and system for polymer production. For the devolatilization process, the polymer needs to be heated to above 260°C via a heat exchanger, and the vacuum level needs to be reduced to 600Pa to 1.5kPaA in the final static devolatilization process. The long-term residence under high temperature conditions will cause significant degradation of the polymer and have a significant impact on the product color.

[0009] CN105008011 describes a volatile matter removal device that incorporates a multi-layer distributor within the devolatilizer to provide residence time for the polymer melt, thereby achieving higher polymer surface renewal and enhancing mass transfer of volatiles. However, this method still relies on high temperature and high vacuum to further remove volatiles by increasing residence time. The design of the multi-layer distributor needs to consider the positive and negative effects of increased residence time on polymer degradation and yellowing, as well as low VOCs. Furthermore, in higher viscosity systems, the polymer flowability on the multi-layer distributor decreases significantly, reducing surface renewal efficiency and the ability to remove volatiles.

[0010] In view of the characteristics and problems of solution-based preparation of polyolefins and polyolefin elastomers, it is necessary to find a process method that can ensure the full removal of volatiles from the polymer melt under mild process parameters, while avoiding polymer degradation, yellowing or even black spots. Furthermore, it is crucial that the process is simple in engineering design, saves investment and energy consumption, and ensures stable long-term operation of the equipment during the operation of the device. Summary of the Invention

[0011] To address the problems existing in the prior art, the present invention aims to provide an apparatus and method for producing olefin-based polymers using supercritical fluid-assisted devolatilization. This apparatus addresses the shortcomings of existing solution polymerization methods for producing olefin-based polymers by optimizing the apparatus structure and utilizing the light components obtained from the light component removal tower for assisted devolatilization. This reduces the devolatilization conditions while improving the devolatilization effect, resulting in high-performance products with promising application prospects.

[0012] To achieve this objective, the present invention adopts the following technical solution:

[0013] In a first aspect, the present invention provides an apparatus for producing olefin-based polymers by supercritical fluid-assisted devolatilization, the apparatus comprising a reaction unit, a devolatilization unit, and a purification and recovery unit connected in sequence;

[0014] The devolatilization unit includes a static devolatilization module; the static devolatilization module includes a booster pump, a mixer, a heater, and a static devolatilizer connected in sequence; a supercritical fluid is formed in the mixer; the refining and recovery unit includes a light-weight removal tower and a heavy-weight removal tower connected in sequence;

[0015] The light-weight removal tower is also directly or indirectly connected to the mixer.

[0016] In this invention, the olefin-based polymer includes polyolefins and / or polyolefin elastomers.

[0017] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0018] As a preferred technical solution of the present invention, the reaction unit includes at least one polymerization reactor, such as one, two or three, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] Preferably, when there are ≥2 polymerization reactors in the reaction unit, they are arranged in series.

[0020] Preferably, the polymerization reactor includes any one or a combination of at least two of the following: a continuous stirred tank reactor, a fully mixed flow model reactor, or a plug flow model reactor.

[0021] As a preferred technical solution of the present invention, the devolatilization unit includes at least one level of static devolatilization module, such as a level 1 static devolatilization module, a level 2 static devolatilization module, a level 3 static devolatilization module, a level 4 static devolatilization module, a level 5 static devolatilization module, or a level 6 static devolatilization module, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, and they are arranged in series, preferably two to four levels of static devolatilization modules.

[0022] Preferably, when the static devolatilization module has at least two stages, it is arranged in series.

[0023] Preferably, the mixer includes any one of a pipeline static mixer, a stirring vessel, an emulsifying pump, or a dynamic mixer, and is preferably a dynamic mixer.

[0024] In this invention, a magnetically driven, high-speed dynamic mixer is used to achieve rapid mixing of supercritical fluid and high-viscosity polymer melt. The diffusion and mutual solubility of the supercritical fluid are driven by external power, and mutual solubility and extraction are achieved within a residence time of less than 1 minute. This reduces the residence time of high-viscosity materials under high temperature and high shear conditions, and significantly improves polymer degradation and yellowing.

[0025] Preferably, the static devolatilizer includes a vertical flash tank.

[0026] Preferably, the top outlet of each static devolatilizer is connected to the light-weight removal tower, and the bottom outlet of each static devolatilizer is connected to the booster pump in the next-stage static devolatilization module.

[0027] As a preferred technical solution of the present invention, the static defoamer is provided with an anti-clogging demister, a liquid distributor and a filter baffle plate arranged from top to bottom inside.

[0028] Preferably, the liquid distributor includes a first liquid distributor and a second liquid distributor.

[0029] Preferably, the number of filter foam baffles is 1 to 10, such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 3 to 6.

[0030] Preferably, the filter baffle is arc-shaped, wherein the arc-shaped edge is connected to the side wall of the static devolatilizer, and the straight edge slopes downward, forming the overflow side.

[0031] Preferably, the angle between the filter baffle and the side wall of the static degassing device is 30-90°, such as 30°, 40°, 50°, 60°, 70°, 75°, 80° or 90°, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 60-75°.

[0032] Preferably, when the number of filter foam baffles is not less than two, adjacent filter foam baffles are arranged on opposite sides.

[0033] Preferably, the vertical projected area of ​​the filter baffle is 30% to 80% of the cross-sectional area of ​​the static degassing device, such as 30%, 40%, 50%, 60%, 70%, or 80%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 50% to 70%.

[0034] In this invention, the vertical projected area of ​​the filter baffle needs to be controlled. If the projected area is too large, the arc-shaped region will be small, resulting in a smaller rising flow channel area for the evaporated gas, which can easily lead to entrainment of impurities in the removed gas phase and blockage of the gas phase system pipeline. If the projected area is too small, the spreading area for the melting melt to fall will be small, making effective surface renewal impossible and hindering further removal of volatiles from the melt.

[0035] Preferably, the overflow side of the filter baffle is provided with sieve holes to form a sieve hole area.

[0036] Preferably, the shape of the sieve hole includes any one or a combination of at least two of the following: circular, elliptical, oval, or strip-shaped, with circular or oval being the most preferred.

[0037] Preferably, the spacing between the sieve holes is 1.5 to 10 times the hole diameter, such as 1.5, 2, 3, 4, 5, 6, 7, 8, 9, or 10 times, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 2.5 to 5 times. Generally, the hole diameter is 5 to 30 mm.

[0038] In this invention, the elliptical shape uses its major axis as the aperture size; the kidney-shaped and strip-shaped shapes use their area equivalent diameter as the aperture size. The selection of aperture size and aperture spacing is crucial. If the aperture size is too large, the specific surface area of ​​the melt falling through the small aperture is relatively small, which is not conducive to the removal of volatiles from the melt. If the aperture size is too small, the pressure drop of the melt through the aperture is large, the thickness of the liquid layer on the sieve plate increases, and it may even overflow downwards through the side, resulting in poor surface renewal and affecting the devolatilization effect. If the aperture spacing is too large, the number of openings in the same area cannot meet the requirements for melt falling. If the aperture spacing is too small, the melt falling through the sieve aperture will re-adhere together due to the extrusion expansion effect, reducing the devolatilization efficiency.

[0039] Preferably, the area of ​​the sieve hole region accounts for 10% to 60% of the area of ​​the filter foam baffle, such as 10%, 20%, 30%, 40%, 50% or 60%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 20% to 40%.

[0040] In this invention, the area of ​​the sieve aperture region needs to be controlled. If the proportion is too large, it will reduce the residence time of the melt on the baffle plate, which is not conducive to the complete removal of bubbles and volatiles; if the proportion is too small, it will not meet the flow area requirements for the melt to fall, resulting in the melt overflowing from the edge, which also cannot effectively filter out bubbles.

[0041] In this invention, the anti-clogging demister captures and settles the liquid in the gas phase through baffles; then, the high-viscosity polymer melt is dispersed into fine droplets through a porous liquid distributor, enhancing surface renewal and ensuring thorough removal of monomers and solvents from the polymer. Simultaneously, to prevent a large amount of vapor evaporation from carrying polymer droplets into the recovery and refining system and clogging the condenser and distillation column, a filter baffle plate allows the melt droplets to remain and spread again on the baffle plate with perforated sieves. After settling and being sheared by the sieve holes, the bubbles break, and the melt falls through the sieve holes onto the next layer of filter baffle plate for further filtration. Furthermore, as the vapor phase evaporated on the lower baffle plate rises and passes through the descending liquid curtain, it further scavenges the melt surface, causing further volatilization of the falling melt. This significantly reduces the bubble content in the final melt pool and significantly improves the operating efficiency and stability of the melt pump.

[0042] As a preferred embodiment of the present invention, the light component outlets of the light component removal tower are independently connected to the mixer in the static devolatilization module.

[0043] Preferably, the light component outlet of the light component removal tower is also connected to the reaction unit.

[0044] Preferably, the light component outlet of the deweighting tower is connected to the reaction unit.

[0045] In a second aspect, the present invention provides a method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, the method being carried out using the apparatus described in the first aspect, the method comprising the following steps:

[0046] (1) The monomer raw materials, solvent and catalyst are introduced into the reaction unit to carry out solution polymerization reaction to obtain the polymerization reaction liquid;

[0047] (2) The polymerization reaction liquid obtained in step (1) enters the devolatilization unit, is mixed with the supercritical auxiliary devolatilization agent and then the devolatilization operation is carried out. The devolatilized gas phase enters the light component removal tower for the first purification. The melt after devolatilization is the polymer product. In the light component removal tower, the obtained light component is condensed and then used as the supercritical auxiliary devolatilization agent for recycling. The obtained tower bottom liquid enters the heavy component removal tower for the second purification.

[0048] In this invention, the method uses the light components from the light component removal tower in the process flow as a supercritical auxiliary devolatilization agent, which is returned to the devolatilization unit to assist in the devolatilization of high-viscosity fluid. The supercritical auxiliary agent diffuses into the polymer melt, promoting the "displacement and transfer" of residual monomers and solvents in the melt. After heating and depressurization flash evaporation, the supercritical fluid and residual monomers are rapidly vaporized and removed, improving the devolatilization effect and efficiency. In addition, since the supercritical fluid has a lower boiling point than residual monomers and solvents, and the latent heat of vaporization is extremely small in the supercritical state, the heating temperature of the melt mixture can be significantly reduced before entering the devolatilizer, generally not exceeding 195°C. After depressurization flash evaporation, the melt temperature in the devolatilization tank is significantly reduced, the residence time of the polymer devolatilization process at high temperature is significantly reduced, degradation and yellowing phenomena are significantly slowed down, and black spots in the product particles are significantly reduced.

[0049] As a preferred technical solution of the present invention, the polymer monomer raw material in step (1) includes ethylene, and any one or at least two combinations of propylene, 1-butene, 1-hexene or 1-octene. Typical but non-limiting examples of such combinations include: combinations of ethylene and propylene, combinations of ethylene and 1-butene, combinations of ethylene, propylene and 1-hexene, etc.

[0050] Preferably, the solvent in step (1) includes a low-carbon alkane, wherein the low-carbon alkane has 5 to 10 carbon atoms, such as 5, 6, 7, 8, 9 or 10.

[0051] Preferably, the catalyst in step (1) includes a metallocene catalyst or a Zigler-Natta catalyst.

[0052] Preferably, the feed temperature of the solution polymerization reaction in step (1) does not exceed 50°C, for example, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0053] In this invention, the reaction unit is carried out adiabatically, and the heat of reaction released by polymerization is removed by precooling the feed.

[0054] Preferably, the temperature of the solution polymerization reaction in step (1) is 120 to 220°C, such as 120°C, 140°C, 160°C, 180°C, 200°C or 220°C, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0055] Preferably, the pressure of the solution polymerization reaction in step (1) is 3 to 10 MPaG, such as 3 MPaG, 4 MPaG, 5 MPaG, 6 MPaG, 7 MPaG, 8 MPaG, 9 MPaG or 10 MPaG, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0056] Preferably, the residence time of the solution polymerization reaction in step (1) is 5 to 60 min, such as 5 min, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0057] Preferably, the solid content of the polymerization reaction liquid in step (1) is 5% to 30%, such as 5%, 10%, 15%, 20%, 25% or 30%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0058] As a preferred technical solution of the present invention, the supercritical auxiliary devolatilizer in step (2) includes any one or a combination of at least two of ethylene, α-olefins or low carbon number alkanes.

[0059] Preferably, the number of carbon atoms in the α-olefin and the low-carbon alkane does not exceed 10 independently, for example, 5, 6, 7, 8, 9 or 10, but is not limited to the listed values; other unlisted values ​​within this range also apply.

[0060] Preferably, the mass ratio of the amount of supercritical auxiliary devolatilizer added in step (2) to the mass of volatiles in the polymerization reaction liquid is (0.05-5):1, for example, 0.05:1, 1:1, 2:1, 3:1, 4:1 or 5:1, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably (0.2-2):1.

[0061] Volatile matter refers to unreacted monomer raw materials and solvents in the polymerization reaction solution, such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, and C5-C10 alkanes.

[0062] Preferably, the devolatilization operation in step (2) is at least level 1 devolatilization, such as level 1, level 2, level 3, level 4 or level 5, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably level 2 to level 4 devolatilization.

[0063] Preferably, each devolatilization operation includes sequentially pressurizing the polymerization reaction solution, mixing the polymerization reaction solution with the supercritical auxiliary devolatilization agent, heating, and flash evaporation.

[0064] Preferably, the mixing temperature is 120-230°C, such as 120°C, 140°C, 160°C, 180°C, 200°C, or 230°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, with 150-200°C being the preferred temperature.

[0065] Preferably, the mixing pressure is 4 to 15 MPaG, such as 4 MPaG, 6 MPaG, 8 MPaG, 10 MPaG, 12 MPaG or 15 MPaG, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable, preferably 8 to 10 MPaG.

[0066] Preferably, the heating temperature is 150 to 300°C, such as 150°C, 200°C, 250°C or 300°C, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable. Preferably, it is 170 to 240°C, and more preferably, it is no more than 190 to 195°C.

[0067] Preferably, when the devolatilization operation in step (2) has at least three stages, the operating pressure of the first-stage flash evaporation is 0.1–0.6 MPaG, for example, 0.1 MPaG, 0.2 MPaG, 0.3 MPaG, 0.4 MPaG, 0.5 MPaG, or 0.6 MPaG; the operating pressure of the second-stage flash evaporation is 20 kPaA–0.2 MPaG, for example, 20 kPaA, 40 kPaA, 60 kPaA, 80 kPaA, 100 kPaA, etc. 0.15 MPaG or 0.2 MPaG, etc.; the operating pressure for the third-stage flash evaporation and subsequent flash evaporation is 1 to 50 kPaA, such as 1 kPaA, 5 kPaA, 10 kPaA, 20 kPaA, 30 kPaA, 40 kPaA or 40 kPaA, etc., preferably 10 to 50 kPaA, more preferably 30 to 40 kPaA. The selection of the above values ​​is not limited to the listed values, and other unlisted values ​​within their respective ranges are also applicable.

[0068] In this invention, compared with the prior art, the vacuum requirement for the three-stage flash evaporation, i.e. the subsequent flash evaporation, is significantly reduced, which can effectively reduce energy consumption.

[0069] As a preferred technical solution of the present invention, the operating pressure of the light-weight removal tower in step (2) is 0.2 to 0.8 MPaG, for example 0.2 MPaG, 0.4 MPaG, 0.6 MPaG or 0.8 MPaG, etc.; the tower bottom temperature does not exceed 200℃, for example 180℃, 185℃, 190℃, 195℃ or 200℃, etc. The selection of the above values ​​is not limited to the listed values, and other unlisted values ​​are also applicable within their respective value ranges.

[0070] Preferably, the operating pressure of the deweight removal tower in step (2) is atmospheric pressure.

[0071] Preferably, the recovery rate of heavy components in the bottom of the de-heavy tower in step (2) is 0.5% to 2%, such as 0.5%, 1%, 1.5% or 2%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0072] As a preferred technical solution of the present invention, the light components of the light removal tower in step (2) are also returned to the reaction unit to participate in the solution polymerization reaction;

[0073] Preferably, the light components from the de-heavy tower in step (2) are returned to the reaction unit to participate in the solution polymerization reaction.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] (1) The device described in this invention, through the optimization of the existing device structure, alleviates the requirements of high temperature and high vacuum for devolatilization, and has the characteristics of saving energy and mild conditions, which is conducive to improving the quality and performance of polyolefin and polyolefin elastomer products.

[0076] (2) The method described in this invention utilizes the light components in the original light removal tower to transform them into a supercritical state and mix them into the melt. This breaks through the thermodynamic equilibrium limit of polymer and high-boiling-point residual monomers to a certain extent. The residual monomers in the melt are reduced to the required level through static flash evaporation. This solves the dependence of traditional polyolefin and polyolefin elastomer systems on dynamic devolatilization equipment such as screws, simplifies the process flow, saves equipment investment, and avoids the high-temperature shearing of polymers by dynamic equipment, thereby mitigating the effects of yellowing and degradation.

[0077] (3) The device described in this invention also uses the design of the filter baffle to allow the melt carrying bubbles to spread again on the baffle. By staying on the baffle, the bubbles are trapped above the sieve plate or broken by the sieve holes, which reduces the gas content in the melt pool, thereby improving the volumetric efficiency of the melt pump and extending the normal service time of the melt pump.

[0078] (4) The device described in this invention further uses magnetic drive and high-speed dynamic mixer to assist in the mixing of supercritical fluid and melt. Under relatively low temperature conditions, the supercritical fluid and melt are fully relaxed, promoting mass transfer, reducing the residence time of polymer in the devolatilization system, enhancing mass transfer, and facilitating the effective removal of volatiles. Attached Figure Description

[0079] Figure 1 This is a schematic diagram of the apparatus for producing olefin-based polymers using supercritical fluid-assisted devolatilization provided in Example 1;

[0080] Figure 2 This is a schematic diagram of the filter bubble baffle in the apparatus for producing olefin-based polymers with supercritical fluid-assisted devolatilization provided in Example 1.

[0081] Among them, 1-first polymerization reactor, 2-second polymerization reactor, 3-first-stage static devolatilization module, 4-second-stage static devolatilization module, 5-third-stage static devolatilization module, 6-light weight removal tower, 7-heavy weight removal tower, 10-booster pump, 20-mixer, 30-heater, 40-static devolatilizer. Detailed Implementation

[0082] To better illustrate the present invention and facilitate understanding of its technical solutions, the present invention is further described in detail below. However, the following embodiments are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0083] In one specific embodiment, the present invention provides an apparatus for producing olefin-based polymers by supercritical fluid-assisted devolatilization, the apparatus comprising a reaction unit, a devolatilization unit, and a purification and recovery unit connected in sequence.

[0084] The devolatilization unit includes a static devolatilization module; the static devolatilization module includes a booster pump, a mixer, a heater and a static devolatilizer connected in sequence; a supercritical fluid is formed in the mixer.

[0085] The refining and recovery unit includes a light-weight removal tower and a heavy-weight removal tower connected in sequence.

[0086] The light-weight removal tower is also directly or indirectly connected to the mixer.

[0087] Furthermore, the reaction unit includes at least one polymerization reactor.

[0088] Furthermore, in the reaction unit, when there are ≥2 polymerization reactors, they are arranged in series.

[0089] Furthermore, the polymerization reactor includes any one or a combination of at least two of the following: a continuous stirred tank reactor, a fully mixed flow model reactor, or a plug flow model reactor.

[0090] Furthermore, the devolatilization unit includes at least one level of static devolatilization module, preferably two to four levels of static devolatilization module.

[0091] Preferably, when the static devolatilization module has at least two stages, it is arranged in series.

[0092] Furthermore, the mixer includes any one of a pipeline static mixer, a stirring vessel, an emulsifying pump, or a dynamic mixer, preferably a dynamic mixer.

[0093] Furthermore, the static devolatilizer includes a vertical flash tank.

[0094] Furthermore, the top outlet of each of the static devolatilization units is connected to the light-weight removal tower, and the bottom outlet of each of the static devolatilization units is connected to the booster pump in the next stage static devolatilization module.

[0095] Furthermore, the static defoamer is provided with an anti-clogging demister, a liquid distributor, and a filter baffle plate arranged sequentially from top to bottom inside.

[0096] Furthermore, the liquid distributor includes a first liquid distributor and a second liquid distributor.

[0097] Furthermore, the number of filter foam baffles is 1 to 10, preferably 3 to 6.

[0098] Furthermore, the filter baffle is bow-shaped, wherein the arc-shaped edge is connected to the side wall of the static devolatilizer, and the straight edge slopes downward.

[0099] Furthermore, the angle between the filter baffle and the sidewall of the static devolatilizer is 30–90°, preferably 60–75°.

[0100] Furthermore, when the number of filter foam baffles is not less than two, adjacent filter foam baffles are arranged on opposite sides.

[0101] Furthermore, the vertical projected area of ​​the filter baffle is 30-80% of the cross-sectional area of ​​the static devolatilizer, preferably 50-70%.

[0102] Furthermore, the overflow side of the filter baffle is provided with sieve holes to form a sieve hole area.

[0103] Furthermore, the shape of the sieve hole includes any one or a combination of at least two of the following: circular, elliptical, oval, or strip-shaped, preferably circular or oval.

[0104] Furthermore, the spacing between the sieve holes is 1.5 to 10 times the sieve diameter, preferably 2.5 to 5 times.

[0105] Furthermore, the area of ​​the sieve hole region accounts for 10-50% of the area of ​​the filter bubble baffle, preferably 20-40%.

[0106] Furthermore, the light component outlets of the light component removal tower are independently connected to the mixers in the static devolatilization module.

[0107] Furthermore, the light component outlet of the light component removal tower is also connected to the reaction unit.

[0108] Furthermore, the light component outlet of the deweighting tower is connected to the reaction unit.

[0109] The following are typical but non-limiting embodiments of the present invention:

[0110] Example 1

[0111] This embodiment provides an apparatus for producing olefin-based polymers using supercritical fluid-assisted devolatilization. A schematic diagram of the apparatus is shown below. Figure 1 As shown, based on the apparatus in a specific embodiment, wherein:

[0112] The reaction unit comprises two polymerization reactors connected in series, both of which are batch reactors, and are respectively named First Polymerization Reactor 1 and Second Polymerization Reactor 2; each batch reactor has a total volume of 39 m³. 3It has a diameter of 3200mm and a height of 4000mm; it is equipped with an internal agitator, and the inner wall of the batch reactor and the agitator blades are polished to a precision of Ra<0.8μm. The batch reactor is equipped with an external insulation jacket, and the insulation medium is heat transfer oil.

[0113] The devolatilization unit includes three static devolatilization modules connected in series, named sequentially as first-level static devolatilization module 3, second-level static devolatilization module 4, and third-level static devolatilization module 5.

[0114] The static devolatilization module includes a booster pump 10, a mixer 20, a heater 30, and a static devolatilizer 40 connected in sequence.

[0115] The mixer 20 is a dynamic mixer, and the static devolatilizer 40 is a vertical flash tank, which is equipped with an anti-clogging demister, a liquid distributor and a filter baffle from top to bottom.

[0116] The number of filter foam baffles is 3, and the structural diagram of the filter foam baffles is as follows: Figure 2 As shown.

[0117] The angle between the filter baffle and the side wall of the static devolatilizer 40 is 75°.

[0118] The vertical projected area of ​​the filter baffle is 70% of the cross-sectional area of ​​the static devolatilizer 40.

[0119] The sieve holes are circular in shape, with a diameter of 20 mm and a spacing of 55 mm.

[0120] The area of ​​the sieve aperture region accounts for 30% of the area of ​​the filter foam baffle.

[0121] Both the light-weight removal tower 6 and the heavy-weight removal tower 7 are floating valve plate towers, with 30 plates for both the light-weight removal tower 6 and the heavy-weight removal tower 7. The associated condensers and reboilers are conventional shell-and-tube heat exchangers.

[0122] Application Example 1

[0123] This application example provides a method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, the method being carried out using the apparatus described in Example 1, and the method comprising:

[0124] (1) Ethylene, 1-butene, isooctane and Zigler-Natta catalyst solution are mixed and cooled to 0°C, and then fed into the first polymerization reactor 1. The feed rate of ethylene is 9200 kg / hr, the feed rate of 1-butene is 19000 kg / h, the feed rate of isooctane is 70000 kg / h, and the catalyst solution is added at a rate of 70 kg / h. The reaction temperature in the first polymerization reactor 1 is controlled at 150°C and the pressure is 7.0 MPaG. When the first polymerization reactor 1 is full and overflows, it is pumped to the second polymerization reactor 2. The reaction temperature in the second polymerization reactor 2 is controlled at 160°C and the pressure is 7.0 MPaG. After the reaction is completed, a polymerization reaction liquid with a solid content of 12% is obtained.

[0125] (2) The polymerization reaction liquid obtained in step (1) enters the primary static devolatilization module 3, is pressurized to 10 MPaG by booster pump 10, preheated to 195℃, and then depressurized to 0.6 MPaG by pressure reducing valve. The flash-evaporated gas phase enters the light phase removal tower 6. The concentrated melt enters the secondary static devolatilization module 4, is pressurized to 10 MPaG by booster pump 10, and is mixed with 1-butene recycled from the light phase removal tower 6 at a rate of 4000 kg / h. After the two materials are mixed, the temperature and pressure exceed the critical temperature and critical pressure of 1-butene, and the supercritical 1-butene melts. The residual solvent and monomers in the melt dissolve out, and then the mixture is heated to 195°C by heater 30 and then depressurized to atmospheric pressure. At this time, the volatiles in the melt are fully vaporized and enter the light volatiles removal tower 6. The melt after the second-stage static devolatilization enters the third-stage static devolatilization module 5, where the melt is further pressurized to 12 MPaG and then fully mixed with 1000 kg / h of recycled 1-butene. It is then heated to 195°C and depressurized to 50 kPaA by regulating valve. The gas phase obtained by flash evaporation enters the light volatiles removal tower 6, and the melt after the third-stage devolatilization is discharged from the device to obtain polyolefin elastomer.

[0126] The operating pressure of the light component removal tower 6 is controlled at 0.47 MPaG, the top temperature is 47℃, and the bottom temperature is 190℃. The bottom liquid after light component removal enters the heavy component removal tower 7. The operating pressure of the heavy component removal tower 7 is controlled at atmospheric pressure, and the bottom temperature is 160℃.

[0127] Application Example 2

[0128] This application example provides a method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, the method being carried out using the apparatus described in Example 1, and the method comprising:

[0129] (1) Ethylene, 1-butene, n-hexane and CGC catalyst solution are mixed and cooled to 0°C, and then fed into the first polymerization reactor 1. The feed rate of ethylene is 9200 kg / hr, the feed rate of 1-butene is 19000 kg / h, the feed rate of n-hexane is 70000 kg / h, and the catalyst solution is added at a rate of 50 kg / h. The reaction temperature in the first polymerization reactor 1 is controlled at 145°C and the pressure is 5.0 MPaG. When the first polymerization reactor 1 is full and overflows, it is pumped to the second polymerization reactor 2. The reaction temperature in the second polymerization reactor 2 is controlled at 160°C and the pressure is 5.0 MPaG. After the reaction is completed, the polymerization reaction liquid is obtained.

[0130] (2) The polymerization reaction liquid obtained in step (1) enters the primary static devolatilization module 3, is pressurized to 10 MPaG by booster pump 10, preheated to 220℃, and then depressurized to 0.6 MPaG by pressure reducing valve. The flash vapor phase enters the light phase removal tower 6; the concentrated melt enters the secondary static devolatilization module 4, is pressurized to 10 MPaG by booster pump 10, and is mixed with 1-butene recycled from the light phase removal tower 6 at a rate of 4000 kg / h. After the two materials are mixed, the temperature and pressure exceed the critical temperature and critical pressure of 1-butene, and the supercritical 1-butene melts. The residual solvent and monomers in the melt dissolve out, and then the mixture is heated to 220°C by heater 30 and then depressurized to atmospheric pressure. At this time, the volatiles in the melt are fully vaporized and enter the light volatiles removal tower 6. The melt after the second-stage static devolatilization enters the third-stage static devolatilization module 5, where the melt is further pressurized to 12 MPaG and then fully mixed with 1000 kg / h of recycled 1-butene. It is then heated to 220°C and depressurized to 50 kPaA by regulating valve. The gas phase obtained by flash evaporation enters the light volatiles removal tower 6, and the melt after the third-stage devolatilization is discharged from the device to obtain the polyolefin elastomer.

[0131] The operating pressure of the light component removal tower 6 is controlled at 0.47 MPaG, the top temperature is 47℃, and the bottom temperature is 140℃. The bottom liquid after light component removal enters the heavy component removal tower 7. The operating pressure of the heavy component removal tower 7 is controlled at atmospheric pressure, and the bottom temperature is 160℃.

[0132] Application Example 3

[0133] This application example provides a method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, the method being carried out using the apparatus described in Example 1, and the method comprising:

[0134] (1) Ethylene, 1-octene, n-hexane and CGC catalyst solution are mixed and cooled to 0°C, and then fed into the first polymerization reactor 1. The feed rate of ethylene is 9200 kg / hr, the feed rate of 1-octene is 19000 kg / h, the feed rate of n-hexane is 70000 kg / h, and the catalyst solution is added at a rate of 40 kg / h. The reaction temperature in the first polymerization reactor 1 is controlled at 155°C and the pressure is 5.0 MPaG. When the first polymerization reactor 1 is full and overflows, it is pumped to the second polymerization reactor 2. The reaction temperature in the second polymerization reactor 2 is controlled at 160°C and the pressure is 5.0 MPaG. After the reaction is completed, the polymerization reaction liquid is obtained.

[0135] (2) The polymerization reaction liquid obtained in step (1) enters the first-stage static devolatilization module 3, is pressurized to 10 MPaG by booster pump 10, preheated to 235°C, and then depressurized to 0.6 MPaG by pressure reducing valve. The flash vapor phase enters the light phase removal tower 6. The concentrated melt enters the second-stage static devolatilization module 4, is pressurized to 10 MPaG by booster pump 10, and then heated to 235°C by heater 30. At this time, n-hexane enters the supercritical state, and is then depressurized to atmospheric pressure. At this time, the volatiles in the melt are fully vaporized and enter the light phase removal tower 6. The melt after the second-stage static devolatilization enters the third-stage static devolatilization module 5, is further pressurized to 12 MPaG, and then fully mixed with 1000 kg / h of recycled n-hexane. It is then heated to 235°C, depressurized to 10 kPaA by regulating valve, and the flash vapor phase enters the light phase removal tower 6. The melt after the third-stage devolatilization is discharged from the device to obtain the polyolefin elastomer.

[0136] The operating pressure of the light component removal tower 6 is controlled at 0.47 MPaG, the top temperature is 47℃, and the bottom temperature is 170℃. The bottom liquid after light component removal enters the heavy component removal tower 7. The operating pressure of the heavy component removal tower 7 is controlled at atmospheric pressure, and the bottom temperature is 160℃.

[0137] Example 2

[0138] This embodiment provides an apparatus for producing olefin-based polymers using supercritical fluid-assisted devolatilization. The apparatus is the same as that in Embodiment 1, except that the pore size of the filter foam is 20 mm and the pore spacing is 20 mm.

[0139] Application Example 4

[0140] This application example provides a method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, the method being carried out using the apparatus in Example 2, and the method being the same as in Application Example 1.

[0141] Example 3

[0142] This embodiment provides an apparatus for producing olefin-based polymers using supercritical fluid-assisted devolatilization. The apparatus is the same as that in Embodiment 1, except that the area of ​​the sieve aperture region accounts for 70% of the area of ​​the filter foam baffle.

[0143] Application Example 5

[0144] This application example provides a method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, the method being carried out using the apparatus in Example 3, and the method being the same as in Application Example 1.

[0145] Example 4

[0146] This embodiment provides an apparatus for producing olefin-based polymers using supercritical fluid-assisted devolatilization. The apparatus is the same as that in Embodiment 1, except that the area of ​​the sieve aperture region accounts for 10% of the area of ​​the filter foam baffle.

[0147] Application Example 6

[0148] This application example provides a method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, the method being carried out using the apparatus in Example 4, and the method being the same as in Application Example 1.

[0149] Comparative Example 1

[0150] This comparative example provides an apparatus for producing olefin-based polymers, which is similar to the apparatus in Example 1, except that:

[0151] (1) The light component outlet of the light component removal tower 6 is not connected in a loop with the devolatilization unit;

[0152] (2) The static devolatilization module consists only of a booster pump 10, a heater 30 and a static devolatilizer 40 connected in sequence.

[0153] Comparative Application Example 1

[0154] This comparative example provides a method for producing olefin-based polymers, the method being carried out using the apparatus described in Comparative Example 1, the method comprising:

[0155] (1) Ethylene, 1-butene, isooctane and Zigler-Natta catalyst solution are mixed and cooled to 0°C, and then fed into the first polymerization reactor 1. The feed rate of ethylene is 9200 kg / hr, the feed rate of 1-butene is 19000 kg / h, the feed rate of isooctane is 70000 kg / h, and the catalyst solution is added at a rate of 70 kg / h. The reaction temperature in the first polymerization reactor 1 is controlled at 150°C and the pressure is 7.0 MPaG. When the first polymerization reactor 1 is full and overflows, it is pumped to the second polymerization reactor 2. The reaction temperature in the second polymerization reactor 2 is controlled at 160°C and the pressure is 7.0 MPaG. After the reaction is completed, a polymerization reaction liquid with a solid content of 12% is obtained.

[0156] (2) The polymerization reaction liquid obtained in step (1) enters the first-stage static devolatilization module 3, is preheated to 250°C, and then depressurized to 0.6 MPaG through a pressure reducing valve. The flash vapor phase enters the light phase removal tower 6. The concentrated melt enters the second-stage static devolatilization module 4, is pressurized to 4.0 MPaG by a booster pump 10, heated to 250°C, and then depressurized to 20 kPaA. The flash vapor phase enters the light phase removal tower 6. The melt after the second-stage static devolatilization enters the third-stage static devolatilization module 5, the melt is further pressurized to 4.0 MPaG, heated to 260°C, and depressurized to 1 kPaA through a regulating valve. The flash vapor phase enters the light phase removal tower 6. The melt after the third-stage devolatilization is discharged from the device to obtain the polyolefin elastomer.

[0157] The operating pressure of the light component removal tower 6 is controlled at 0.47 MPaG, the top temperature is 47℃, and the bottom temperature is 190℃. The bottom liquid after light component removal enters the heavy component removal tower 7. The operating pressure of the heavy component removal tower 7 is controlled at atmospheric pressure, and the bottom temperature is 160℃.

[0158] Comparative Application Example 2

[0159] This comparative example provides a method for producing olefin-based polymers, the method being carried out using the apparatus described in Comparative Example 1, the method comprising:

[0160] (1) Ethylene, 1-butene, isooctane and Zigler-Natta catalyst solution are mixed and cooled to 0°C, and then fed into the first polymerization reactor 1. The feed rate of ethylene is 9200 kg / hr, the feed rate of 1-butene is 19000 kg / h, the feed rate of isooctane is 70000 kg / h, and the catalyst solution is added at a rate of 70 kg / h. The reaction temperature in the first polymerization reactor 1 is controlled at 150°C and the pressure is 7.0 MPaG. When the first polymerization reactor 1 is full and overflows, it is pumped to the second polymerization reactor 2. The reaction temperature in the second polymerization reactor 2 is controlled at 160°C and the pressure is 7.0 MPaG. After the reaction is completed, a polymerization reaction liquid with a solid content of 12% is obtained.

[0161] (2) The polymerization reaction liquid obtained in step (1) enters the first-stage static devolatilization module 3, is preheated to 195°C, and then depressurized to 0.6 MPaG through a pressure reducing valve. The flash vapor phase enters the light phase removal tower 6. The concentrated melt enters the second-stage static devolatilization module 4, is pressurized to 10 MPaG by a booster pump 10, is heated to 195°C, and then depressurized to atmospheric pressure. The flash vapor phase enters the light phase removal tower 6. The melt after the second-stage static devolatilization enters the third-stage static devolatilization module 5, is further pressurized to 12 MPaG, is heated to 195°C, and then depressurized to 50 kPaA through a regulating valve. The flash vapor phase enters the light phase removal tower 6. The melt after the third-stage devolatilization is discharged from the device to obtain the polyolefin elastomer.

[0162] The operating pressure of the light component removal tower 6 is controlled at 0.47 MPaG, the top temperature is 47℃, and the bottom temperature is 190℃. The bottom liquid after light component removal enters the heavy component removal tower 7. The operating pressure of the heavy component removal tower 7 is controlled at atmospheric pressure, and the bottom temperature is 160℃.

[0163] Comparative Example 2

[0164] This comparative example provides an apparatus for producing olefin-based polymers, which is the same as the apparatus in Example 1, except that the light component outlet of the light component removal tower 6 is not connected in a loop to the devolatilization unit.

[0165] Comparative Application Example 3

[0166] This comparative application example provides a method for producing olefin-based polymers, the method being carried out using the apparatus of Comparative Example 2, the method comprising:

[0167] (1) Ethylene, 1-butene, isooctane and Zigler-Natta catalyst solution are mixed and cooled to 0°C, and then fed into the first polymerization reactor 1. The feed rate of ethylene is 9200 kg / hr, the feed rate of 1-butene is 19000 kg / h, the feed rate of isooctane is 70000 kg / h, and the catalyst solution is added at a rate of 70 kg / h. The reaction temperature in the first polymerization reactor 1 is controlled at 150°C and the pressure is 7.0 MPaG. When the first polymerization reactor 1 is full and overflows, it is pumped to the second polymerization reactor 2. The reaction temperature in the second polymerization reactor 2 is controlled at 160°C and the pressure is 7.0 MPaG. After the reaction is completed, a polymerization reaction liquid with a solid content of 12% is obtained.

[0168] (2) The polymerization reaction liquid obtained in step (1) enters the first-stage static devolatilization module 3, is pressurized to 10 MPaG by booster pump 10, preheated to 250°C, and then depressurized to 0.6 MPaG by pressure reducing valve. The flashed vapor phase enters the light phase removal tower 6. The concentrated melt enters the second-stage static devolatilization module 4, is pressurized to 10 MPaG by booster pump 10, heated to 250°C, and then depressurized to 20 kPaA. The flashed vapor phase enters the light phase removal tower 6. The melt after the second-stage static devolatilization enters the third-stage static devolatilization module 5, is further pressurized to 12 MPaG, heated to 260°C, and depressurized to 1 kPaA by regulating valve. The flashed vapor phase enters the light phase removal tower 6. The melt after the third-stage devolatilization is discharged from the device to obtain the polyolefin elastomer.

[0169] The operating pressure of the light component removal tower 6 is controlled at 0.47 MPaG, the top temperature is 47℃, and the bottom temperature is 190℃. The bottom liquid after light component removal enters the heavy component removal tower 7. The operating pressure of the heavy component removal tower 7 is controlled at atmospheric pressure, and the bottom temperature is 160℃.

[0170] Comparative Application Example 4

[0171] This comparative application example provides a method for producing olefin-based polymers, the method being carried out using the apparatus of Comparative Example 2, the method comprising:

[0172] (1) Ethylene, 1-butene, isooctane and Zigler-Natta catalyst solution are mixed and cooled to 0°C, and then fed into the first polymerization reactor 1. The feed rate of ethylene is 9200 kg / hr, the feed rate of 1-butene is 19000 kg / h, the feed rate of isooctane is 70000 kg / h, and the catalyst solution is added at a rate of 70 kg / h. The reaction temperature in the first polymerization reactor 1 is controlled at 150°C and the pressure is 7.0 MPaG. When the first polymerization reactor 1 is full and overflows, it is pumped to the second polymerization reactor 2. The reaction temperature in the second polymerization reactor 2 is controlled at 160°C and the pressure is 7.0 MPaG. After the reaction is completed, a polymerization reaction liquid with a solid content of 12% is obtained.

[0173] (2) The polymerization reaction liquid obtained in step (1) enters the first-stage static devolatilization module 3, is pressurized to 10 MPaG by booster pump 10, preheated to 195°C, and then depressurized to 0.6 MPaG by pressure reducing valve. The flashed vapor phase enters the light phase removal tower 6. The concentrated melt enters the second-stage static devolatilization module 4, is pressurized to 10 MPaG by booster pump 10, heated to 195°C, and then depressurized to atmospheric pressure. The flashed vapor phase enters the light phase removal tower 6. The melt after the second-stage static devolatilization enters the third-stage static devolatilization module 5, is further pressurized to 12 MPaG, heated to 195°C, and depressurized to 50 kPaA by regulating valve. The flashed vapor phase enters the light phase removal tower 6. The melt after the third-stage devolatilization is discharged from the device to obtain polyolefin elastomer.

[0174] The operating pressure of the light component removal tower 6 is controlled at 0.47 MPaG, the top temperature is 47℃, and the bottom temperature is 190℃. The bottom liquid after light component removal enters the heavy component removal tower 7. The operating pressure of the heavy component removal tower 7 is controlled at atmospheric pressure, and the bottom temperature is 160℃.

[0175] Results Test

[0176] The VOC content, yellowness index, weight-average molecular weight, and black spot rate in the polymer products obtained from Application Examples 1-6 and Comparative Application Examples 1-4 were measured respectively, under the following specific test conditions:

[0177] The VOC content in the obtained product was determined using an Agilent 7820A gas chromatograph under the following conditions: capillary column (DB-5, 30m × 0.25mm × 0.25μm), initial temperature 60℃, held for 1 minute; increased to 80℃ at a rate of 10℃ / min, held for 1 minute; then increased to 250℃ at a rate of 15℃ / min, held for 8 minutes; carrier gas was high-purity N2, split ratio 30:1, split flow rate 39mL / min; carrier gas flow rate 20mL / min, initial waiting time 2min, injection temperature 250℃, detector was FID, detector temperature 260℃, injection volume 0.2μL.

[0178] The yellowness index was measured using a yellowness index meter; the weight-average molecular weight was measured using GPC chromatography; and the black spot rate in the pellets after pelleting was determined using an OC particle black spot impurity detector.

[0179] The relevant measurement results are shown in Table 1.

[0180] Table 1

[0181]

[0182]

[0183] As can be seen from Table 1, the present invention uses supercritical fluid-assisted devolatilization and, by further optimizing the structure of the static devolatilizer, effectively reduces the severity of the process conditions. Furthermore, the polymer products obtained in Application Examples 1-3 are of high quality, with VOC content below 1000 ppm, yellowness index below 0.2, weight-average molecular weight variation less than 5000, and black spot rate in the pellets below 0.1%. In Application Example 4, the pore spacing of the filter foam sieve was only one time the pore diameter, resulting in a VOC content of 3140 ppm in the obtained product. In Application Example 5, the open area ratio was too large, resulting in a VOC content of 1500 ppm in the obtained product. In Application Example 6, the open area ratio was too small, affecting the complete removal of bubbles and volatiles, causing the VOC content of the obtained product to rise to 2200 ppm.

[0184] In Comparative Application Example 1, no supercritical fluid was used to assist devolatilization, nor was the static devolatilizer structure optimized or improved. Using existing equipment and process conditions resulted in a significant decrease in product quality. Similarly, in Comparative Application Example 2, no supercritical fluid was used to assist devolatilization, and the static devolatilizer structure was not optimized or improved. Although the process conditions of this invention were used for production and devolatilization, the product quality decreased even more severely. In Comparative Application Example 3, only the structure of the static devolatilizer was optimized and production and devolatilization were carried out using existing process conditions. Compared to Application Examples 1-3, the improvement in product quality was limited. In Comparative Application Example 4, no supercritical fluid was used for assisted devolatilization; only the static devolatilizer structure was optimized. Even when using the process conditions of this invention for production and devolatilization, the improvement in product quality was still limited.

[0185] The present invention has been illustrated through the above embodiments with respect to the apparatus and detailed method, but the present invention is not limited to the above apparatus and detailed method, that is, it does not mean that the present invention must rely on the above apparatus and detailed method to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the operation of the present invention, additions of auxiliary operations, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An apparatus for producing olefin-based polymers using supercritical fluid-assisted devolatilization, characterized in that, The device includes a reaction unit, a devolatilization unit, and a refining and recovery unit connected in sequence. The devolatilization unit includes a static devolatilization module; the static devolatilization module includes a booster pump, a mixer, a heater, and a static devolatilizer connected in sequence; a supercritical fluid is formed in the mixer; the refining and recovery unit includes a light-weight removal tower and a heavy-weight removal tower connected in sequence. The outlet of the light component in the light component removal tower is also directly or indirectly connected to the mixer. The static devolatilizer contains, from top to bottom, an anti-clogging demister, a liquid distributor, and a filter baffle. The filter baffle is arc-shaped, with its arc-shaped edge connected to the side wall of the static devolatilizer and its straight edge sloping downwards. The overflow side of the filter baffle has sieve holes, forming a sieve hole area. The spacing between the sieve holes is 1.5 to 10 times the hole diameter, and the area of ​​the sieve hole area accounts for 20 to 40% of the area of ​​the filter baffle.

2. The apparatus according to claim 1, characterized in that, The reaction unit includes at least one polymerization reactor.

3. The apparatus according to claim 2, characterized in that, In the reaction unit, when there are ≥2 polymerization reactors, they are arranged in series.

4. The apparatus according to claim 2, characterized in that, The polymerization reactor includes a continuously stirred tank.

5. The apparatus according to claim 1, characterized in that, The devolatilization unit includes at least one level of static devolatilization module.

6. The apparatus according to claim 5, characterized in that, The devolatilization unit includes 2 to 4 levels of static devolatilization modules.

7. The apparatus according to claim 5, characterized in that, When the static devolatilization module has no less than two stages, it is set in series.

8. The apparatus according to claim 1, characterized in that, The mixer includes either a pipeline static mixer or a dynamic mixer.

9. The apparatus according to claim 8, characterized in that, The mixer is a dynamic mixer.

10. The apparatus according to claim 1, characterized in that, The static devolatilizer includes a vertical flash tank.

11. The apparatus according to claim 1, characterized in that, The top outlet of each static devolatilizer is connected to the light-weight removal tower, and the bottom outlet of each static devolatilizer is connected to the booster pump in the next stage static devolatilization module.

12. The apparatus according to claim 5, characterized in that, The liquid distributor includes a first liquid distributor and a second liquid distributor.

13. The apparatus according to claim 5, characterized in that, The number of filter foam baffles is 1 to 10.

14. The apparatus according to claim 13, characterized in that, The number of filter foam baffles is 3 to 6.

15. The apparatus according to claim 5, characterized in that, The angle between the filter foam baffle and the side wall of the static devolatilizer is 30~90°.

16. The apparatus according to claim 15, characterized in that, The angle between the filter baffle and the side wall of the static devolatilizer is 60~75°.

17. The apparatus according to claim 5, characterized in that, When the number of filter foam baffles is not less than two, adjacent filter foam baffles are arranged on opposite sides.

18. The apparatus according to claim 5, characterized in that, The vertical projected area of ​​the filter foam baffle is 30-80% of the cross-sectional area of ​​the static devourer.

19. The apparatus according to claim 18, characterized in that, The vertical projected area of ​​the filter foam baffle is 50-70% of the cross-sectional area of ​​the static devourer.

20. The apparatus according to claim 5, characterized in that, The shape of the sieve holes includes any one or a combination of at least two of the following: circular, elliptical, oval, or strip-shaped.

21. The apparatus according to claim 20, characterized in that, The sieve holes are circular or oval in shape.

22. The apparatus according to claim 5, characterized in that, The spacing between the sieve holes is 2.5 to 5 times the hole diameter.

23. The apparatus according to claim 5, characterized in that, The outlet of the light component from the light component removal tower is also connected to the reaction unit.

24. The apparatus according to claim 5, characterized in that, The outlet of the light component from the deweighting tower is connected to the reaction unit.

25. A method for producing olefin-based polymers using supercritical fluid-assisted devolatilization, characterized in that, The method is performed using the apparatus as described in any one of claims 1-24, and the method includes the following steps: (1) The monomer raw materials, solvent and catalyst are introduced into the reaction unit to carry out solution polymerization reaction to obtain the polymerization reaction solution; (2) The polymerization reaction liquid obtained in step (1) enters the devolatilization unit, is mixed with the supercritical auxiliary devolatilization agent and then the devolatilization operation is carried out. The devolatilized gas phase enters the light component removal tower for the first purification. The melt after devolatilization is the polymer product. In the light component removal tower, the light component obtained is condensed and then used as the supercritical auxiliary devolatilization agent for recycling. The obtained tower bottom liquid enters the heavy component removal tower for the second purification.

26. The method according to claim 25, characterized in that, The monomer raw materials for step (1) include ethylene, and any one or a combination of at least two of propylene, 1-butene, 1-hexene or 1-octene.

27. The method according to claim 25, characterized in that, The solvent in step (1) includes low-carbon alkanes, wherein the number of carbon atoms in the low-carbon alkanes is 5 to 10.

28. The method according to claim 25, characterized in that, Step (1) The catalyst includes a metallocene catalyst or a Ziegler-Natta catalyst.

29. The method according to claim 25, characterized in that, The feed temperature for the solution polymerization reaction in step (1) shall not exceed 50°C.

30. The method according to claim 25, characterized in that, The reaction temperature of the solution polymerization reaction in step (1) is 120~220℃.

31. The method according to claim 25, characterized in that, The pressure of the solution polymerization reaction in step (1) is 3~10 MPaG.

32. The method according to claim 25, characterized in that, The residence time for the solution polymerization reaction in step (1) is 5 to 60 minutes.

33. The method according to claim 25, characterized in that, The solid content of the polymerization reaction liquid in step (1) is 5-30%.

34. The method according to claim 25, characterized in that, The supercritical auxiliary devolatilizer in step (2) includes any one or a combination of at least two of ethylene, α-olefins or low-carbon alkanes.

35. The method according to claim 34, characterized in that, The number of carbon atoms in the α-olefin and the low-carbon alkane each independently does not exceed 10.

36. The method according to claim 25, characterized in that, In step (2), the mass ratio of the amount of supercritical auxiliary devolatilizer added to the volatiles in the polymerization reaction solution is (0.05~5):

1.

37. The method according to claim 36, characterized in that, In step (2), the mass ratio of the amount of supercritical auxiliary devolatilizer added to the volatiles in the polymerization reaction solution is (0.2~2):

1.

38. The method according to claim 25, characterized in that, The devolatilization operation in step (2) is at least a level 1 devolatilization.

39. The method according to claim 38, characterized in that, The devolatilization operation in step (2) is a 2-4 level devolatilization.

40. The method according to claim 38, characterized in that, Each devolatilization operation includes sequentially pressurizing the polymerization reaction solution, mixing the polymerization reaction solution with the supercritical auxiliary devolatilizer, heating, and flash evaporation.

41. The method according to claim 40, characterized in that, The mixing temperature is 120~230℃.

42. The method according to claim 41, characterized in that, The mixing temperature is 150~200℃.

43. The method according to claim 40, characterized in that, The mixing pressure is 4~15 MPaG.

44. The method according to claim 43, characterized in that, The mixing pressure is 8~10 MPaG.

45. The method according to claim 40, characterized in that, The heating temperature is 150~300℃.

46. ​​The method according to claim 45, characterized in that, The heating temperature is 170~230℃.

47. The method according to claim 46, characterized in that, The heating temperature is 190~195℃.

48. The method according to claim 38, characterized in that, When the number of devolatilization stages in step (2) is not less than 3, the operating pressure of the first-stage flash evaporation is 0.1~0.6MPaG, the operating pressure of the second-stage flash evaporation is 20kPaA~0.2MPaG, and the operating pressure of the third-stage flash evaporation and subsequent flash evaporations is 1~50kPaA.

49. The method according to claim 48, characterized in that, The operating pressure for the third-stage flash evaporation and subsequent flash evaporations is 10~50 kPaA.

50. The method according to claim 49, characterized in that, The operating pressure for the third-stage flash evaporation and subsequent flash evaporations is 30~40 kPaA.

51. The method according to claim 25, characterized in that, The operating pressure of the light-light removal tower in step (2) is 0.2~0.8MPaG, and the tower bottom temperature does not exceed 200℃.

52. The method according to claim 25, characterized in that, The operating pressure of the deweight removal tower in step (2) is atmospheric pressure.

53. The method according to claim 25, characterized in that, The recovery rate of heavy components in the bottom of the de-heavy tower in step (2) is 0.5-2%.

54. The method according to claim 25, characterized in that, The light components from the light removal tower in step (2) are also returned to the reaction unit to participate in the solution polymerization reaction.

55. The method according to claim 25, characterized in that, In step (2), the light components from the de-heavy tower are returned to the reaction unit to participate in the solution polymerization reaction.

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