Reactor for olefin gas phase polymerization

Abstract

A reactor for conducting gas-phase olefin polymerization in the presence of a polymerization catalyst is provided, comprising at least a first polymerization zone adapted and arranged for upward flow of growing polymer particles under high velocity fluidization or transport conditions, at least a second polymerization zone adapted and arranged for downward flow of growing polymer particles, and at least one set of bars for introducing feedstock and / or interceptor streams into the reactor, each bar including a hollow space along its length and having a particle-deflecting apex, each bar having an opening arranged along the lower half of its circumference.

Description

[Technical field]

[0001] The present disclosure provides a reactor for carrying out the gas phase polymerization of olefins in the presence of a polymerization catalyst, the reactor comprising at least one set of bars for introducing feedstock and / or cutoff streams into the reactor, and a method for carrying out the gas phase polymerization of olefins in the reactor in the presence of a polymerization catalyst. [Background technology]

[0002] Gas phase polymerization is a polymerization technique that is widely applied for gaseous monomers such as ethylene, propylene, etc. Although it has been established since the 1960s, the high demand for polyolefins has led to continuous efforts to improve the manufacturing process, especially in terms of product quality and throughput. Breakthroughs, especially in terms of controlling the molecular weight distribution of the polymer, are achieved by polymerization in different polymerization zones. Examples of such multi-zone polymerization reactors are disclosed in WO 00 / 02929 A1 and WO 2009 / 080660 A1, which refer to a method for carrying out the gas phase polymerization of (-olefins) in two interconnected polymerization zones, in which the growing polymer particles flow upwards through a first polymerization zone under fast fluidization conditions, leave the first polymerization zone and enter a second polymerization zone, the particles flow downwards through the second polymerization zone in a dense form, and the gas mixture of the first polymerization zone is completely or partially prevented from entering the second polymerization zone by introducing into the upper part of the second polymerization zone a liquid stream having a different composition from the gaseous mixture present in the first polymerization zone.

[0003] Although these multi-zone reactors are well established industrially, it is desirable to have more flexibility in adjusting the composition of the olefin polymer, especially when improving the polymer property balance.WO2018 / 087209A1 therefore proposes a method for producing olefin polymers in the presence of hydrogen in a gas-phase polymerization reactor comprising three or more polymerization zones with different ratios of hydrogen to the sum of olefins in the reaction gas mixture.

[0004] Regardless of the number of polymerization zones, the technology of multi-zone reactors mainly relies on the different compositions of the gas mixtures present in different polymerization zones and the efficient separation of these mixtures. Therefore, it is necessary to create an effective barrier between different polymerization zones to prevent the gas mixture present in one polymerization zone from entering another polymerization zone. As shown in WO 2009 / 080660A1, the separation can be achieved by a blocking flow. However, the effectiveness of such a blocking flow is highly dependent on the appropriate introduction of the corresponding gas or liquid into the reactor to avoid uneven distribution and obtain a uniform blocking flow.

[0005] Another common requirement in the gas phase polymerization of olefins is high monomer conversion and uniform composition and / or molecular weight distribution of the polymer produced. Moreover, avoiding dead spaces that may form in the reactor in areas where the monomer concentration is insufficient to sustain the polymerization is also a constant consideration in the modification of polymerization reactors.

[0006] To promote uniform distribution and achieve high monomer conversion, EP 2 745 925 A1 proposes a settled bed polymerization reactor with multiple inlet levels, with at least one inlet per level for injection of monomer, comonomer, co-reactant and / or inert components, the inlet levels being distributed over the entire height of the reactor, the distance between two inlet levels being equal to or less than 0.25 times the height of the reactor, and the number of inlet levels being at least [reactor height / (0.25 x reactor height)]-1. A degassing method for removing unpolymerized monomer from an olefin polymer is disclosed in EP 0513816 A2, in which an inert purge gas is introduced into a purge vessel via a gas distributor equipped with a lateral extension tube having an opening that allows the inert purge gas to enter the purge vessel.

[0007] Attempts have been made to address the demands associated with uniformly distributing any components (e.g., monomer feed or cutoff stream) introduced into the reactor, but there remains a need to improve the flow of polymer within the reactor, which is prone to interruption by components being introduced into the reactor. To date, industry has been reluctant to use injectors that span the entire width of the reactor. While more uniform distribution can be achieved, injectors present an obstacle to the free flow of polymer particles through the reactor, where the polymer can stop, grow, and form undesirable agglomerates.

[0008] There is therefore a need for the present disclosure to provide a reactor for gas phase polymerization that allows for uniform distribution of all components introduced into the reactor while ensuring free flow of polymer particles through the reactor. Summary of the Invention

[0009] The present disclosure relates to a reactor for carrying out gas phase polymerization of olefins in the presence of a polymerization catalyst, comprising at least one first polymerization zone adapted and arranged for growing polymer particles to flow upwardly under fast fluidization or transport conditions, at least one second polymerization zone adapted and arranged for growing polymer particles to flow downwardly, and at least one set of bars for introducing feed and / or cutoff streams into said second polymerization zone, each said bar comprising a hollow space along its length for conveying the feed and / or cutoff stream within said bar and having a particle deflection top for preventing polymer particles from accumulating on said bar, each said bar having at least one set of bars with openings for distributing said feed and / or said cutoff streams arranged along a lower half of its circumference.

[0010] In some embodiments, the particle deflecting apex of the bar includes a apex edge that extends along the length of the bar.

[0011] In some embodiments, the bottom half of the periphery of the bar has a particle deflection shape that includes a bottom edge that extends along the length of the bar.

[0012] In some embodiments, each bar includes a distribution section for distributing the feed and / or interruption flow and a deflection section forming a particle deflection apex of the bar, the distribution section being preferably tubular.

[0013] In some embodiments, the distribution portion is a tube having a diameter of between 25 mm and 100 mm.

[0014] In some embodiments, the hollow space contained within the bar has a central axis extending along the length of the bar, the opening is located within the lower half of the periphery of the bar, and the angle between a vertical plane (v) passing through the central axis and a plane passing through the opening and the central axis is between 0° and 70°, preferably between 20° and 50°.

[0015] In some embodiments, the diameter of the opening (6) is between 0.5 mm and 10 mm, preferably between 1.5 mm and 5 mm.

[0016] In some embodiments, the particle-deflecting apex of the bar includes a first planar surface and a second planar surface, the intersection of the first planar surface and the second planar surface forming the apex edge, and a dihedral angle between the surfaces is less than 120°, preferably between 10° and 100°, and more preferably between 30° and 80°.

[0017] In some embodiments, the bars of the at least one set of bars are positioned to extend across a portion of the width of the second polymerization zone from one side and extend across a portion of the width of the second polymerization zone from the opposite side, leaving a gap between opposing bars.

[0018] In some embodiments, the reactor further comprises at least one set of supports for supporting the bars, preferably for supporting the bars and introducing a blocking flow.

[0019] In some embodiments, one end of the bar and / or support is adapted to be conformably connected to a wall of the second polymerization zone.

[0020] In some embodiments, the bar and / or support has a surface roughness Ra, measured according to DIN ISO 25178, of less than or equal to 5 μm, preferably between 0.1 μm and 5 μm, in particular between 0.5 μm and 4 μm.

[0021] The present disclosure also provides a bar for introducing a feed and / or a cutoff flow into a multi-zone circulating reactor (MZCR), the bar comprising a hollow space along the length of the bar for conveying the feed and / or the cutoff flow within the bar, having a particle deflection apex for preventing polymer particles from accumulating on the bar, and having openings disposed along the lower half of the circumference of the bar for distributing the feed and / or the cutoff flow.

[0022] The present disclosure also provides a method for carrying out olefin gas phase polymerization in the presence of a polymerization catalyst at a temperature of 20°C to 200°C and a pressure of 0.5MPa to 10MPa in a reactor described in the present disclosure, comprising the steps of feeding one or more olefins to the reactor, contacting the olefins with the catalyst under reaction conditions in at least a first polymerization zone and at least a second polymerization zone, and recovering a polymer product from at least the second polymerization zone, wherein the growing polymer particles flow upward through the first polymerization zone under fast fluidization or transport conditions, leave the first polymerization zone and enter the second polymerization zone, in which the polymer particles flow downward under the action of gravity, leave the second polymerization zone and are at least partially reintroduced into the first polymerization zone, thus circulating between the first polymerization zone and the second polymerization zone, the second polymerization zone comprising a dense polymer particle layer, and feed and / or a shutoff flow are introduced into the second polymerization zone through at least one set of bars.

[0023] In some embodiments, the pressure difference between the pressure of the reaction gas in the second polymerization zone and the pressure of the feedstock and / or the shutoff flow in the hollow space is from 1 to 500 kPa, preferably from 5 to 200 kPa, particularly from 10 to 100 kPa. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 shows a schematic diagram of a multi-zone circulation reactor of the present disclosure, having a first polymerization zone (1), a second polymerization zone (2) containing a layer of dense polymer particles (3), a line for feeding a break stream (4a') and a line for feeding a raw material (4b'). [Diagram 2] FIG. 2 shows a schematic top view of the second polymerization zone (2) showing the bar (4), the support (5) and the reactor wall (7), c showing the centreline of the second polymerization zone (2). [Figure 3a] 1 shows a schematic cross-section of a bar (4) of the present disclosure, where v indicates a vertical plane symmetrically cutting the deflection section (43) and the distribution section (44) of the bar (4), and the arrows indicate the flow direction of the polymer particles. [Figure 3b] FIG. 2 is a schematic bottom view of a bar (4) of the present disclosure showing an opening (6) arranged at the bottom of the bar (4), which is connected to the reactor wall (7) via a flange element (47) at the location where the reactor wall (7) is provided with a nozzle (71), v indicates a vertical plane cutting the bar (4) symmetrically. [Figure 4] FIG. 2 shows a schematic side view of a support (5) of the present disclosure that supports a bar (4) of the present disclosure. [Diagram 5] 1 shows a schematic cross-section of a preferred embodiment of a support (5) of the present disclosure having angles A51, A52, A53 and A54. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] In the course of this disclosure, the inventors have found that by adjusting the design of the bars for introducing the raw materials and / or the cutoff flow into the second polymerization zone of the polymerization reactor, a uniform distribution of the introduced components and a smooth flow of the polymer particles can be obtained, and the quality of the obtained polymer can be further improved.

[0026] The present disclosure therefore provides a reactor for carrying out olefin gas phase polymerization in the presence of a polymerization catalyst, comprising at least one first polymerization zone (1) adapted and arranged for growing polymer particles to flow upwards under fast fluidization or transport conditions, at least one second polymerization zone (2) adapted and arranged for growing polymer particles to flow downwards, and at least one set of bars (4) for introducing feed and / or cutoff streams into said second polymerization zone (2), each bar (4) comprising a hollow space (41) along its length for conveying the feed and / or cutoff stream within the bar (4) and having a particle deflection apex for preventing polymer particles from accumulating on the bar (4), each bar (4) having at least one set of bars (4) having openings (6) for distributing said feed and / or said cutoff streams, arranged along the lower half of the periphery (42) of the bar (4).

[0027] The reactor preferably further comprises a gas-solid separation zone (8) for separating polymer particles from the reaction gas, a connection (9) for connecting the top of the first polymerization zone (1) to the gas-solid separation zone (8), a connection (10) for connecting the bottom of the second polymerization zone (2) to the bottom of the first polymerization zone (1). The reactor of the present disclosure preferably further comprises a gas recycle line (11) connecting the separation zone (8) to the connection (10) and / or to one or more points of reintroduction into the first polymerization zone (1), the gas recycle line (11) preferably further comprising a heat exchanger (12), a compressor (13), a line (14) for feeding the catalyst into the first polymerization zone (1), a line (15) for feeding the monomer into the reactor, and a discharge system (16) for discharging the polymer from the second polymerization zone (2).

[0028] It will be understood by those skilled in the art that the at least first polymerization zone (1) and the at least second polymerization zone (2) of the disclosed apparatus may be connected in different ways and more than two polymerization zones may be employed without departing from the spirit of the disclosure. Suitable structures and combinations are described, for example, in WO00 / 02929 A1 and WO97 / 04015 A1.

[0029] Olefins that can be polymerized in the reactor of the present disclosure are particularly, but not limited to, 1-olefins, i.e., hydrocarbons with terminal double bonds. Non-polar olefinic compounds are preferred. Particularly preferred 1-olefins are linear or branched C2-C 12 -1-Alkenes, in particular linear or branched C2-C, such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, etc. 10 -Linear or branched C2-C, such as 1-alkene or 4-methyl-pentene 10 -1-alkenes; conjugated and non-conjugated dienes such as 1,3-butadiene, 1,4-hexene, 1,7-octene. Mixtures of different 1-olefins can also be polymerized. Suitable olefins also include those in which the double bond is part of a ring structure which may have one or more ring systems. Examples are cyclopentene, norbornene, tetracyclododecene or methylnorbornene, or dienes such as 5-ethylidene-2-norbornene, norbornadiene or ethylnorbornadiene. Mixtures of two or more olefins can also be polymerized.

[0030] The reactor of the present disclosure is useful for homopolymerization or copolymerization of ethylene or propylene, and is particularly useful for homopolymerization or copolymerization of ethylene. The preferred comonomers in propylene polymerization are ethylene, 1-butene and / or 1-hexene at a concentration of at most 40% by weight, preferably 0.5-35% by weight. The preferred comonomers in ethylene polymerization are C3-C8-1-alkenes, particularly 1-butene, 1-pentene, 1-hexene and / or 1-octene at a concentration of at most 20% by weight. The polymerization in which ethylene is copolymerized with 0.1-12% by weight of 1-hexene and / or 1-butene is particularly preferred.

[0031] Due to the special design of the bars (4) for introducing the feed and / or the cutoff flow into the second polymerization zone (2), a uniform distribution of the corresponding components is achieved while maintaining a discontinuous flow of the polymer particles through the reactor. The bars (4) of a set are preferably arranged at different heights in the second polymerization zone (2). The position of the bars (4) in the second polymerization zone (2) can vary depending on the specific function of the bars (4). In this respect, it is preferred that the bars (4) belonging to a set of bars are arranged at the same height.

[0032] The bars (4) used in the reactor according to the present disclosure comprise a hollow space (41) along the length of the bar (4) for conveying the feed and / or the cutoff flow within the bar (4). Each bar (4) has additional openings (6) for distributing the feed and / or the cutoff flow. The openings (6) are arranged along the lower half of the periphery (42) of the bar (4). The openings (6) allow the feed and / or the cutoff flow conveyed within the bar (4) to leave the hollow space (41) within the bar (4) and be distributed within the second polymerization zone (2), each bar (4) preferably comprising a distribution section (44) for distributing the feed and / or the cutoff flow, the distribution section (44) being preferably tubular. The arrangement of the openings (6) along the lower half of the periphery (42) of the bar (4) distributes the feed and / or the cutoff flow uniformly across the entire width of the second polymerization zone (2). The diameter of the tube is preferably between 25 and 100 mm.

[0033] Surprisingly, it has been found that uniform distribution can be achieved by arranging the openings (6) in a particular pattern. Thus, in a preferred embodiment of the present disclosure, the bar (4) contains a hollow space (41) having a central axis (411) extending along the length of the bar (4), the openings (6) are located within a portion of the lower half of the outer periphery (42) of the bar (4), and the angle (A41, A41') between a vertical plane (v) passing through the central axis (411) and a plane passing through the openings (6) and the central axis (411) is between 0° and 70°, preferably between 20° and 50°.

[0034] In a preferred embodiment of the present disclosure, the openings (6) of the dispensing portion (44) have a diameter of 0.5 mm to 10 mm, preferably 1.5 mm to 5 mm. Surprisingly, keeping the dimensions of the openings (6) within the claimed ranges makes it possible to avoid clogging of the openings and undesired accumulation of the dispensed components.

[0035] The bar (4) used in the reactor according to the present disclosure has a particle deflection apex to prevent polymer particles from accumulating on said bar (4). Preferably, the particle deflection apex of the bar (4) comprises a top edge (43) extending along the length of the bar (4). Preferably, the particle deflection apex of the bar (4) comprises a first flat surface (46a) and a second flat surface (46b), the intersection of the first flat surface (46a) and the second flat surface (46b) forming said top edge (43), and the dihedral angle (A42) between the surfaces (46a, 46b) is less than 120°, preferably between 10° and 100°, more preferably between 30° and 80°. Preferably, the particle deflection apex of the bar (4)A is formed by a deflection section (45) provided at the top a of the distribution section (44).

[0036] In a preferred embodiment of the present disclosure, the bar (4) not only has a particle-deflecting apex, but the lower half of the outer periphery (42) of the bar (4) preferably has a particle-deflecting shape including a bottom edge to ensure free flow of the polymer particles. In a more preferred embodiment of the present disclosure, the lower half of the outer periphery (42) of the bar (4) has a semi-cylindrical shape.

[0037] To ensure uniform distribution, it is preferred to cover the entire width of the second polymerization reaction (2) with a bar (4).Preferably, the bar (4) is connected to one side of the second polymerization zone (2) and extends into the second polymerization zone (2) towards the opposite side.

[0038] In a preferred embodiment, the bars (4) span the width of the second polymerization zone (2) and extend across it to the opposite side. The bars (4) preferably form a gap between the end of each bar (4) and the opposite reactor wall, preferably of 200 mm or less, more preferably of 10 to 200 mm, even more preferably of 20 to 100 mm, in particular of 30 to 80 mm. Surprisingly, by leaving a small gap between the end of the bar (4) and the reactor wall (7), the flow of the polymer particles can be made more stable.

[0039] Especially for large reactors, the mechanical stability and robustness of the bars (4) are important factors to ensure a long life and a smooth production cycle of the bars (4) and the reactor. Surprisingly, it has been found that the mechanical stability of the bars (4) can be improved by using specially arranged short bars, rather than using a single bar spanning the width of the second polymerization zone (2). Thus, in a particularly preferred embodiment, the bars (4) of a set of bars are arranged to extend only partially across the width of the second polymerization zone (2) from one side of the second polymerization zone (2) and only partially across the width of the second polymerization zone (2) from the opposite side, thereby leaving a gap between the bars (4) on the opposite sides. Preferably, the opposing bars (4) are arranged at the same height in the second polymerization zone (2). Preferably, the length of one bar (4) corresponds to its corresponding length extending from the opposite side of the second polymerization zone (2). Preferably, the gap between the opposing bars (4) is arranged along the center line (c) of the second polymerization zone (2). The center line (c) of the second polymerization zone (2) according to the present disclosure should be understood as any straight line passing through the center of the second polymerization zone (2) at its maximum expansion. The gap between the opposing bars (4) is preferably 200 mm or less, more preferably 10 to 200 mm, even more preferably 20 to 100 mm, in particular 30 to 80 mm.

[0040] The number of sets of bars (4) and their arrangement in the reactor of the present disclosure can be adapted as required. When there are multiple sets of bars (4), the sets of bars (4) are preferably arranged on top of each other, particularly preferably in a staggered manner. The staggered manner used in the present disclosure should be understood as a set of bars (4) being located between the free spaces created by the sets of bars (4) below or above a set of bars (4). Preferably, the bars (4) of each set are arranged at equal intervals so as to be parallel to each other.

[0041] In a preferred embodiment, the bars (4) used in the reactor according to the present disclosure are used to introduce a barrier flow (e.g., a barrier flow provided by a line (4a')) into the second polymerization zone (2) to prevent the gas mixture present in the first polymerization zone (1) from entering the second polymerization zone (2). These barrier flow bars are preferably located at the top of the second polymerization zone (2), and the number of sets of bars (4) for introducing the barrier flow is at least one set, preferably 2-5 sets, more preferably 2-3 sets, and each set of barrier flow bars is located at the same height. Each barrier flow bar preferably comprises 2-20 pieces, more preferably 4-12 pieces. Different sets of bars (4) for introducing the barrier flow are preferably located at different heights in the top of the second polymerization zone (2), and the distance between each set of bars is preferably 100-3000 mm, more preferably 300-1000 mm. The barrier flow may be a gas barrier flow, a liquid barrier flow, or a gas / liquid barrier flow.

[0042] In further preferred embodiments, the second polymerization zone (2) comprises a layer of dense polymer particles (3). In these embodiments, the bars (4) for introducing the interruption streams are preferably arranged below the surface of the dense polymer particle layer (3). In particularly preferred embodiments, the interruption streams are immersed in the layer of dense polymer particles (3). The distance between the uppermost set of interruption streams and the surface of the layer of dense polymer particles (3) is preferably greater than 100 mm, preferably greater than 500 mm.

[0043] In an alternative preferred embodiment of the present disclosure, the bars (4) are used to introduce the feedstock, for example supplied by line (4b'), into the second polymerization zone (2). These feedstock bars (4) are preferably arranged at different heights in the second polymerization zone (2), in particular below the lowest cutoff flow bar (4) (4a). The number of sets of bars (4) for introducing the feedstock into the second polymerization zone (2) is preferably 1-20 sets, more preferably 3-10 sets. Each set of feedstock bars (4) preferably includes 1-10 bars (4), preferably 2-7 bars (4). The feedstock preferably includes the monomer to be polymerized and any one or more other components, preferably selected from the group consisting of inert components, comonomers and hydrogen, preferably in a ratio of 5:95-100:0.

[0044] In a further preferred embodiment, the reactor according to the present disclosure comprises at least 1 set, preferably 2-5 sets, more preferably 2-3 sets of bars (4) for introducing a blocking flow, and 1-20 sets, preferably 3-10 sets of bars (4) for introducing raw materials.

[0045] To ensure mechanical stability of the bars, the reactor according to the present disclosure preferably further comprises at least one set of supports (5) supporting the bars (4). The supports are preferably in direct contact with the bars (4). The supports (5) are preferably arranged below the supports (4). To ensure sufficient support, the supports (5) are preferably arranged perpendicular to the bars (4). In a preferred embodiment, the supports (5) are used in particular to support the bars (4) for introducing a blocking flow.

[0046] The length of the support (5) can be selected depending on the size of the reactor. In some embodiments, the support (5) extends across the entire width of the second polymerization zone (2). In other embodiments, particularly for larger reactors, the support (5) extends partially across the width of the second polymerization zone (2) from one side and partially across the width of the second polymerization zone (2) from the opposite side, preferably with the opposite supports (5) at the same height. This results in a gap between the opposing supports (5). The gap between the opposing supports (5) is preferably 600 mm or less, preferably 500 mm or less.

[0047] The support (5) is attached to the reactor wall (7) and extends horizontally from the wall. It is therefore necessary to limit the weight of the support (5) whilst ensuring sufficient mechanical stability to support the bar (4). Surprisingly, these two objectives can be achieved by selecting a specially designed support (5). In a preferred embodiment, the cross-sectional area of ​​the support (5) decreases along at least a part of its length. Preferably, the end of the support (5) with the smallest cross section is the end furthest from the connection location on the reactor wall (7).

[0048] In a preferred embodiment, the supports (5) are used in particular to support the bars (4) for introducing the interruption flow, the ratio of interruption flow bars to supports (5) being preferably between 2:1 and 10:1, more preferably between 2:1 and 4:1. The ratio of interruption flow bars to supports (5) allows sufficient mechanical stability while ensuring an undisturbed flow of the polymer particles in the second polymerization zone (2).

[0049] Although the support (5) may be necessary to provide sufficient mechanical stability, the support is an additional obstacle in the flow of the polymer particles. Therefore, special care was taken when designing the support (5) to minimize its impact on the polymer flow. Thus, in a preferred embodiment, the shape of the support (5) is adapted to prevent accumulation and ensure free flow of the polymer particles. In a preferred embodiment, the support (5) is rhomboidal. In a further preferred embodiment, the support (5) is in the form of a hexagonal prism extending horizontally from the wall (7) of the reactor according to the present disclosure. Preferably, the support (5) is of a shape having two upper faces (5a, 5b) and two side faces (5a, 5b) that are preferably arranged parallel to each other and that span an angle A51 of less than 90°. The angle A53 between the top face (5a, 5b) and the side face (5c, 5d) and / or the angle A54 between the bottom face (5e, 5f) and the side face (5c, 5d) are greater than 90° to ensure the polymer particles slide down, the angle A52 of the bottom face (5e, 5f) being less than 90°. It is also preferred that the side faces (5c, 5d) are arranged in line with the flow direction of the polymer particles. The special design of the support (5) ensures an unhindered flow of the polymer particles and prevents the formation of dead spaces in the polymer zone.

[0050] The geometry of the support can be further optimized. In a preferred embodiment, the length of the first top surface (5a) is equal to the length of the second top surface (5b). Also, the length of the first side surface (5c) may be equal to the length of the second side surface (5d) and / or the length of the first bottom surface (5e) may be equal to the length of the second bottom surface (5f).

[0051] The different angles of the support (5) may be adapted to prevent accumulation of polymer particles. In one embodiment, angles A51 and A52 may be the same. In an alternative embodiment, angles A51 and A52 may be different. For optimal slip-off, angle A51 is preferably larger than angle A52. Preferably, angle A51 is between 10° and 80°, more preferably between 50° and 70°. More preferably, angle A52 is between 10° and 50°, preferably between 20° and 40°.

[0052] The bars (4) and the supports (5) extend from the wall (7) of the reactor. In the course of this disclosure, it was found that the respective connection points of the bars (4) and the supports (5) to the reactor wall (7) can further impede the polymer flow and locally fluidize the polymer particles, thereby interrupting the regular flow of the polymer particles along the second polymerization zone (2). Therefore, one end of each of said bars (4) and / or supports (5) is advantageously adapted to be conformably connected to the wall (7) of the reactor. Conformably connected to the wall means that the end of the bar (4) or the support (5) is connected to the wall, said end having a shape such that a continuity of the inner surface of the reactor is provided, and any part of the bar (4) or support (5) extending from the inner surface of the reactor inside the reactor has the shape of the bar (4) or support (5). In a preferred embodiment, the connection of the bars (4) and / or supports (5) is achieved by introducing each said bar (4) and / or support (5) into the reactor through a nozzle (71) integrated in the reactor wall (7) and by conformally fixing the bars (4) and / or supports (5) in the nozzle (71) by means of an adapter, preferably in the form of a flange element (47). Fixing the bars (4) and / or supports (5) in this way avoids irregularities in the connection area and ensures a smooth connection.

[0053] By selecting a suitable material for the bars (4) and / or the support (5), the flow of the polymer particles, in particular the flow in the second polymerization zone (2), can be further improved. In a preferred embodiment of the present disclosure, the bars (4) and / or the support (5) are made of a metal, preferably selected from the group consisting of low temperature steel and stainless steel. In this way, both mechanical stability and a suitable surface finish to ensure a smooth flow of the polymer particles can be ensured. In order to avoid further interference of the gas flow as well as the polymer flow in the second polymerization zone (2), it is preferred that the bars (4) and / or the support (5) have a surface roughness Ra, measured according to DIN ISO 25178, of 5 μm or less, preferably 0.1 μm to 5 μm, in particular 0.5 μm to 4 μm.

[0054] The reactor of the present disclosure may be part of a larger assembly, such as a series of reactors. In a particularly preferred embodiment, the reactor is further connected to another reactor, in particular a fluidized bed reactor (FBR). Such a suitable combination in series includes a fluidized bed reactor followed by a reactor according to the present disclosure, or a reactor according to the present disclosure followed by a fluidized bed reactor. In this way, the reactor according to the present disclosure can be integrated into a series of reactors designed for ethylene polymerization and a series of reactors designed for propylene polymerization.

[0055] In another aspect, the present disclosure provides a bar for introducing a feed and / or a cutoff flow into a polymerization reactor, in particular a multi-zone circulation reactor (MZCR), comprising a hollow space along the length of the bar for conveying the feed and / or the cutoff flow within the bar, having a particle deflection top for preventing polymer particles from accumulating on the bar, and having openings arranged along the lower half of the circumference of the bar for distributing the feed and / or the cutoff flow. The bar preferably comprises a distribution section, preferably in the form of a tube with openings for distributing the feed and / or the cutoff flow. These openings are arranged along the lower half of the circumference of the bar to ensure uniform distribution over the entire width of the reactor. Surprisingly, it has been found that by arranging the openings in a specific pattern, uniform distribution is achieved. Thus, in a preferred embodiment of the present disclosure, the openings are arranged within a specific region defined by an angle of preferably 0° to 70°, more preferably 20° to 50° with respect to a vertical plane symmetrically cutting the distribution section.

[0056] In a preferred embodiment of the present disclosure, the diameter of the opening is 0.5 mm to 10 mm, preferably 1.5 mm to 5 mm, and a deflection section is provided at the top of the bar to prevent accumulation of particles at the top of the bar. The deflection section preferably includes a first flat surface and a second flat surface that span an angle of less than 120°, preferably an angle of 10° to 100°, and more preferably an angle of 30° to 80°.

[0057] Another aspect of the present disclosure provides a method for carrying out olefin gas phase polymerization in the presence of a polymerization catalyst at a temperature of 20°C to 200°C and a pressure of 0.5MPa to 10MPa in a reactor according to the present disclosure, comprising the steps of feeding one or more olefins to the reactor, contacting said olefins with said catalyst under reaction conditions in at least a first polymerization zone (1) and at least a second polymerization zone (2), and recovering a polymer product from at least said second polymerization zone (2), wherein growing polymer particles flow upward through said first polymerization zone (1) under fast fluidization or transport conditions, leave said first polymerization zone (1) and enter said second polymerization zone (2), in which said polymer particles flow downward under the action of gravity, leave said second polymerization zone (2) and are at least partially reintroduced into said first polymerization zone (1), thus circulating between said first polymerization zone (1) and said second polymerization zone (2), and said second polymerization zone (2) comprises a dense polymer particle layer. The process is further characterized in that the feed and / or the cutoff stream are introduced into the second polymerization zone (2) via at least one set of bars (4).

[0058] In a preferred embodiment of the process, the polymerization is a homopolymerization of ethylene or a copolymerization of ethylene with one or more other olefins selected from the group consisting of 1-butene, 1-hexene and 1-octene, or the polymerization is a homopolymerization of propylene or a copolymerization of propylene with one or more olefins selected from the group consisting of ethylene, 1-butene, 1-hexene and 1-octene.

[0059] Preferably, the method for producing an olefin polymer comprises homopolymerizing an olefin or copolymerizing an olefin with one or more other olefins in the presence of a polymerization catalyst at a temperature of 20°C to 200°C and a pressure of 0.5 MPa to 10 MPa, wherein the polymerization is carried out in the reactor of the present disclosure.

[0060] The reactor of the present disclosure can be operated at pressures of 0.5 MPa to 10 MPa, preferably 1.0 MPa to 8 MPa, in particular 1.5 MPa to 4 MPa, and these pressures, like all pressures given in this disclosure, must be understood as absolute pressures, i.e. pressures with the size MPa (abs). The polymerization is preferably carried out at temperatures of 30°C to 160°C, in particular at temperatures of 65°C to 125°C.

[0061] In a preferred embodiment of the present disclosure, the pressure difference between the pressure of the reaction gas in the second polymerization zone (2) and the pressure of the raw materials and / or the cutoff flow in the hollow space (41) is 1 to 500 kPa, preferably 5 to 200 kPa, in particular 10 to 100 kPa.

[0062] In a preferred embodiment of the present disclosure, the velocity of the feed and / or cutoff flow passing through the bottom opening (6) of the bar (4) is between 1 and 50 m / s, preferably between 5 and 40 m / s, in particular between 10 and 20 m / s.

[0063] The polymerization in the reactor can also be carried out in a condensed or supercondensed mode, in which a portion of the circulating reaction gas mixture is cooled below the dew point and returned to the first polymerization zone as liquid and gas phases, respectively, or together as a two-phase mixture, further utilizing the enthalpy of vaporization to cool the reaction gas.

[0064] In a preferred embodiment, the polymerization is carried out in the presence of an inert gas such as nitrogen, an alkane having 1 to 10 carbon atoms such as methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, or a mixture thereof. As the inert gas, nitrogen or propane is preferably used, preferably in combination with other alkanes. In a particularly preferred embodiment, the polymerization is carried out in the presence of a C3-C5 alkane as a polymerization diluent, most preferably in the presence of propane, especially in the case of homopolymerization or copolymerization of ethylene. In a preferred embodiment of the present disclosure, the content of inert components in the reaction gas mixture is 30 to 99% by volume, more preferably 40 to 95% by volume, and especially 45 to 85% by volume. In another preferred embodiment of the present disclosure, especially when the main monomer is propylene, no inert diluent is added or only a small amount is added.

[0065] The reaction gas mixture in the apparatus further comprises the olefin to be polymerized, i.e. the main monomer, and one or more optional comonomers. The reaction gas mixture may further comprise additional components such as antistatic agents or molecular weight regulators, such as hydrogen. The components of the reaction gas mixture may be added in gaseous or liquid form to the polymerization zone or gas circulation line and then vaporized in the polymerization zone or gas circulation line.

[0066] The polymerization of olefins can be carried out using any commonly used olefin polymerization catalyst. This means that the polymerization can be carried out using Ziegler or Ziegler-Natta catalysts, Phillips catalysts based on chromium oxide, or single-site catalysts. For the purposes of this disclosure, single-site catalysts are catalysts based on chemically uniform transition metal coordination compounds. Furthermore, mixtures of two or more of these catalysts can also be used to polymerize olefins. Such mixed catalysts are generally called hybrid catalysts. The preparation of these catalysts and their use in olefin polymerization are known.

[0067] Preferred catalysts are of the Ziegler or Ziegler-Natta type, preferably comprising a compound of titanium or vanadium, a compound of magnesium, and optionally an electron donor compound and / or a particulate inorganic oxide as support material.

[0068] Ziegler or Ziegler-Natta type catalysts are usually polymerized in the presence of a cocatalyst. Preferred cocatalysts are organometallic compounds of metals of Groups 1, 2, 12, 13 or 14 of the Periodic Table of the Elements, in particular organometallic compounds of metals of Group 13, especially organoaluminum compounds. Preferred cocatalysts are, for example, organometallic alkyls, organometallic alkoxides, organometallic halides.

[0069] Preferred organometallic compounds include lithium alkyls, magnesium or zinc alkyls, magnesium alkyl halides, aluminum alkyls, silicon alkyls, silicon alkoxides and silicon alkyl halides. More preferably, the organometallic compounds include alkylaluminums and alkylmagnesiums. Even more preferably, the organometallic compounds include alkylaluminums, most preferably trialkylaluminum compounds, or compounds of this type in which the alkyl groups are replaced by halogen atoms, such as chlorine or bromine. Examples of such aluminum alkyls are trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum or diethylaluminum chloride, or mixtures thereof.

[0070] In a further preferred embodiment of the present disclosure, the polymerization is in a reactor that is part of a series of polymerization reactors, and one or more of the polymerizations in other gas phase reactors of the series of polymerization reactors may also be polymerizations according to the present disclosure. Suitable combinations of such polymerization reactors include a fluidized bed reactor followed by a reactor according to the present disclosure, or a reactor according to the present disclosure followed by a fluidized bed reactor.

Claims

1. 1. A reactor for carrying out gas phase polymerization of olefins in the presence of a polymerization catalyst, comprising at least one first polymerization zone (1) adapted and arranged for growing polymer particles to flow upward under fast fluidization or transport conditions, at least one second polymerization zone (2) adapted and arranged for growing polymer particles to flow downward, and at least one set of bars (4) for introducing feed and / or cutoff streams into said second polymerization zone (2), each said bar (4) comprising a hollow space (41) along its length for conveying the feed and / or cutoff stream within the bar (4) and having a particle deflection top for preventing polymer particles from accumulating on said bar (4), each said bar (4) having openings (6) for distributing said feed and / or said cutoff stream, arranged along the lower half of its periphery (42).

2. 2. The reactor of claim 1, wherein the particle-deflecting apex of the bar (4) comprises a top edge (43) extending along the length of the bar (4) and / or the lower half of the periphery (42) of the bar (4) has a particle-deflecting shape comprising a bottom edge (43) extending along the length of the bar (4).

3. 3. The reactor according to claim 1 or 2, wherein each bar (4) comprises a distribution section (44) for distributing the feed and / or the interruption flow and a deflection section (45) forming a particle deflection apex of the bar (4).

4. 3. The reactor according to claim 1 or 2, wherein the hollow space (41) contained in the bar (4) has a central axis (411) running along the length of the bar (4), the openings (6) are arranged in a lower half portion of the outer periphery (42) of the bar (4), and the angle (A41, A41') between a vertical plane (v) passing through the central axis (411) and a plane passing through the openings (6) and the central axis (411) is between 0° and 70°.

5. 3. The reactor of claim 2, wherein the particle deflection apex of the bar (4) comprises a first planar surface (46a) and a second planar surface (46b), the intersection of the first planar surface (46a) and the second planar surface (46b) forming the apex edge (43), and a dihedral angle (A42) between the surfaces (46a, 46b) is less than 120°.

6. 3. The reactor according to claim 1 or 2, wherein the bars (4) of the at least one set of bars are arranged to extend across a portion of the width of the second polymerization zone (2) from one side and to extend across a portion of the width of the second polymerization zone (2) from the opposite side, leaving a gap between opposing bars (4).

7. A reactor described in any one of claims 1 to 6, further comprising at least one set of supports (5) for supporting the bars (4) for introducing a blocking flow, and / or one end of the bars (4) and / or supports (5) is adapted to be form-fittingly connected to a wall (7) of the second polymerization zone (2).

8. A bar for introducing a feed and / or a cutoff flow into a multi-zone circulating reactor (MZCR), the bar comprising a hollow space along the length of the bar for conveying the feed and / or the cutoff flow within the bar, having a particle deflection apex for preventing polymer particles from accumulating on the bar, and having openings disposed along the lower half of the circumference of the bar for distributing the feed and / or the cutoff flow.

9. A process for carrying out olefin gas phase polymerization in the presence of a polymerization catalyst at a temperature of 20° C. to 200° C. and a pressure of 0.5 MPa to 10 MPa in a reactor according to claim 1 or 2, comprising the steps of feeding one or more olefins to the reactor, contacting said olefins with said catalyst under reaction conditions in at least a first polymerization zone (1) and at least a second polymerization zone (2), and recovering a polymer product from at least the second polymerization zone (2), wherein the growing polymer particles are transported upward through the first polymerization zone (1) under fast fluidization or transport conditions. , leaves said first polymerization zone (1) and enters said second polymerization zone (2), in which said polymer particles flow downwards under the effect of gravity, leave said second polymerization zone (2) and are at least partially reintroduced into said first polymerization zone (1), thus circulating between said first polymerization zone (1) and said second polymerization zone (2), said second polymerization zone (2) comprising a dense polymer particle layer, and said feed and / or said cut-off flow being introduced into said second polymerization zone (2) via at least said set of bars (4).

10. 10. The process according to claim 9, wherein the pressure difference between the pressure of the reaction gas in the second polymerization zone (2) and the pressure of the feed and / or the breakwater flow in the hollow space (41) is from 1 to 500 kPa.

Images