Fluidized bed reactor for gas phase polymerization of olefins

Abstract

A fluidized bed reactor for the gas phase polymerization of olefins, comprising an inner chamber (2) having, in order, at least one lower section (3) and at least one upper section (4), The fluidized bed reactor (1) comprises a gas distribution grid (7) located in the inner chamber (2) and at least partially separating the lower section (3) from the upper section (4); a recycle line (8) configured to supply fluidizing gas to the lower section (3) and having a first end (9) connected to the inner chamber (2) at the upper section (4); a polymer discharge channel (17) configured to discharge the polymer obtained inside the upper section (4) downward in a discharge direction (D); and a partition wall (DW) defining a first region (A) of the inner chamber (2) and located around at least an extension of the polymer discharge channel (17) so as to prevent the fluidizing gas from reaching the first region (A), the partition wall (DW) having a first portion (DW') intersecting the discharge direction (D).

Description

[Technical Field]

[0001] The present invention relates to a fluidized bed reactor for the gas phase polymerization of olefins and to a process for the preparation of olefin polymers. [Background technology]

[0002] Gas-phase polymerization processes are economical processes for preparing polyolefins, such as ethylene or propylene homopolymers or copolymers of ethylene and / or propylene with other olefins. Fluidized-bed reactors for carrying out such processes have long been known. These reactors contain a bed of polymer particles maintained in a fluidized state by the upward flow of a fluidizing gas. Typical reactors include a reactor space in the form of a vertical cylindrical interior. These reactors have a cooler to remove the heat of polymerization, a recycle gas compressor, and, if desired, a recycle gas line equipped with components such as a cyclone to remove fine polymer dust. Monomer consumed by the polymerization reaction is usually replaced by adding make-up gas to the recycle gas stream.

[0003] To ensure a homogeneous distribution of the fluidizing gas in the bed of growing polymer particles, the reactor is fitted with a gas distribution grid, sometimes called a gas fluidization grid or distribution plate. Such a gas distribution grid is a device with openings that distribute the gas flow introduced below the grid to the bed. The grid also serves as a support for the bed when the gas supply is stopped.

[0004] The gas distribution grid can be configured as a perforated or porous plate and may be combined with an upstream flow divider. For example, a roof-like defractor plate can be placed over the openings in the distributor plate, as disclosed in EP 0 697 421 A1, or the openings can be covered with caps, as described in EP 0 600 414 A1. The shape of the gas distribution grid can also differ from that of the plate. EP 0 088 638 A2 discloses a gas distributor for a fluidized bed reactor having a double cone. WO 2008 / 074632 A1 describes a gas distribution grid having an inverted cone shape. Due to the large amount of circulating fluidizing gas and the resulting large size of the gas inlet nozzle, a relatively large volume is required below the gas distribution grid.

[0005] Over time, fines present in the fluidizing gas can accumulate in the space below the reactor grid. These reactive fines can form polymer agglomerates in a stagnant state and eventually become too bulky, thereby endangering the operability and reliability of the reactor system.

[0006] Therefore, there is a need to provide a fluidized bed reactor in which the fine polymer particles carried by the fluidizing gas can be easily returned to the fluidized bed of polymer particles.

[0007] The object of the present invention is to provide a fluidized bed reactor and a process for the preparation of olefin polymers which is able to at least partially overcome the drawbacks of the known art and which is at the same time simple and inexpensive to implement. Summary of the Invention

[0008] According to the present invention there is provided a fluidized bed reactor and a process for the preparation of olefin polymers according to the accompanying independent claims, preferably according to any claim that depends directly or indirectly on the independent claims. [Brief explanation of the drawings]

[0009] The invention will now be described with reference to the accompanying drawings, which show some non-limiting embodiments thereof:

[0010] [Figure 1] FIG. 1 is a schematic diagram and side view of a fluidized bed reactor according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a portion of the fluidized bed reactor of FIG. [Figure 3] FIG. 3 is a plan view of a portion of FIG. 2 with some of the details removed for clarity. [Figure 4] FIG. 4 is a cross-sectional front view of a detail of FIG. [Figure 5] FIG. 5 is a cross-sectional view of a detail of FIG. [Figure 6] FIG. 6 is a cross-sectional view of a portion of FIG. 2 in a different embodiment. [Figure 7] FIG. 7 is a cross-sectional view of a portion of FIG. 2 in yet another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] In Figure 1, the numeral 1 generally designates a fluidized-bed reactor for the gas-phase polymerization of olefins. The fluidized-bed reactor 1 has an inner chamber 2, which has at least one lower section 3 and at least one upper section 4. The fluidized-bed reactor 1 comprises at least one lateral wall 5 having an inner surface 6 that laterally defines (at least partially) the inner chamber, a gas distribution grid 7 located within the inner chamber 2 and separating (at least partially) the lower section 3 from the upper section 4, and a gas recycle line 8 having a first end 9 connected to the inner chamber 2 at the upper section 4 and a second end 10 connected to the inner chamber 2 at the lower section 3.

[0012] More precisely, although not necessarily, the gas recycle line 8 is configured to transport the recycled portion of the fluidizing gas from the upper part 4 of the inner chamber 2 through the upper wall 15 and the fluidizing gas through the lateral wall 5 to the lower part 4.

[0013] In particular, the olefins that can be polymerized in the fluidized bed reactor 1 of the present disclosure are specifically, but not limited to, 1-olefins, i.e., hydrocarbons with terminal double bonds. Non-polar olefin compounds are preferred. Particularly preferred 1-olefins are linear or branched C2-C 12 -1-Alkenes, especially linear or branched C2-C, such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 1-decene 10 -Linear or branched C2-C, such as 1-alkene or 4-methylpentene 10 1-alkenes; conjugated and non-conjugated dienes such as 1,3-butadiene, 1,4-hexene, and 1,7-octene. Mixtures of various 1-olefins can also be polymerized. Suitable olefins also include those in which the double bond is part of a cyclic structure, which may have one or more ring systems. For example, 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.

[0014] This fluidized-bed reactor 1 is particularly suitable for the homopolymerization or copolymerization of ethylene or propylene, and is particularly suitable for the homopolymerization or copolymerization of ethylene. Preferred comonomers for propylene polymerization are 40% by weight or less of ethylene, 1-butene, and / or 1-hexene, and preferably 0.5 to 35% by weight of ethylene, 1-butene, and / or 1-hexene. For ethylene polymerization, it is preferable to use C3-C8-1-alkene, particularly 1-butene, 1-pentene, 1-hexene, and / or 1-octene, at a concentration of 20% by weight or less, more preferably 0.01 to 15% by weight, and particularly preferably 0.05 to 12% by weight. Particularly preferred is copolymerization of ethylene with 0.1 to 12% by weight of 1-hexene and / or 1-butene.

[0015] In an advantageous, non-limiting embodiment of the present disclosure, the polymerization is carried out in the presence of an inert gas such as nitrogen, or an alkane having 1 to 10 carbon atoms, such as methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, or n-hexane, or a mixture thereof. Nitrogen gas or propane is preferably used as the inert gas, preferably in combination with other alkanes, if appropriate. In a particularly preferred embodiment of the present disclosure, the polymerization is carried out in the presence of a C3-C5 alkane as a polymerization diluent, and most advantageously in the presence of propane, particularly in the case of ethylene homopolymerization or copolymerization. The reaction gas mixture in the reactor further comprises the olefin to be polymerized, i.e., the main monomer, and one or more optional comonomers. In an advantageous embodiment of the present disclosure, the reaction gas mixture has an inert component content of 30 to 99% by volume, more preferably 40 to 95% by volume, and particularly 45 to 85% by volume. In another advantageous embodiment of the present disclosure, particularly when the main monomer is propylene, no inert diluent is added, or only a small amount is added. The reaction gas mixture may further include additional components such as antistatic agents or molecular weight regulators, such as hydrogen gas. The components of the reaction gas mixture may be fed to the gas-phase polymerization reactor or recycle gas line in gaseous or liquid form and then vaporized within the reactor or recycle gas line.

[0016] According to some non-limiting examples, olefin polymerization can be carried out using any commonly used olefin polymerization catalyst. That is, for example, chromium oxide-based Phillips catalysts, Ziegler or Ziegler-Natta catalysts, or single-site catalysts can be used. For purposes of this disclosure, a single-site catalyst is a catalyst based on a chemically uniform transition metal coordination compound. Furthermore, it is also possible to use a mixture of two or more of these catalysts in the polymerization of olefins. Such mixed catalysts are often referred to as hybrid catalysts. The preparation and use of these olefin polymerization catalysts is generally known.

[0017] Advantageous examples of Ziegler-type catalysts preferably contain a titanium or vanadium compound, a magnesium compound, and optionally an electron donor compound and / or a particulate inorganic oxide as support material.

[0018] Ziegler-type catalysts are usually used in the presence of a cocatalyst. Examples of the cocatalyst include organometallic compounds of metals in Groups 1, 2, 12, 13, or 14 of the Periodic Table, especially organometallic compounds of metals in Group 13, especially organoaluminum compounds. Preferred cocatalysts are, for example, organometallic alkyls, organometallic alkoxides, or organometallic halides.

[0019] Advantageous examples of organometallic compounds include lithium alkyls, magnesium or zinc alkyls, magnesium alkyl halides, aluminum alkyls, silicon alkyls, silicon alkoxides, and silicon alkyl halides. More advantageously, the organometallic compounds include aluminum alkyls and magnesium alkyls. Even more advantageously, the organometallic compounds include aluminum alkyls, most advantageously trialkylaluminum compounds, or compounds of this type in which the alkyl group is replaced with a halogen atom, such as chlorine or bromine. Examples of such aluminum alkyls include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diethylaluminum chloride, or mixtures thereof.

[0020] According to some non-limiting embodiments, the fluidized bed reactor of the present disclosure is operated at a pressure of 0.5 MPa to 10 MPa, advantageously 1.0 MPa to 8 MPa, and particularly 1.5 MPa to 4 MPa. The polymerization is advantageously, but not necessarily, carried out at a temperature of 30° C. to 60° C., particularly advantageously 65° C. to 125° C., with temperatures in the upper part of this range being preferred for preparing ethylene copolymers with relatively high density and temperatures in the lower part of this range being preferred for preparing ethylene copolymers with low density.

[0021] According to some non-limiting embodiments, polymerization in a fluidized bed reactor is carried out in a condensed or hypercondensed mode, in which a portion of the circulating reaction gas mixture is cooled below the dew point and returned to the reactor as liquid and gas phases, respectively, or together as a two-phase mixture, further utilizing the enthalpy of vaporization to cool the reaction gas.

[0022] The gas recycle line 8 is configured to supply the lower part 3 of the inner chamber 2 with a fluidizing gas comprising fresh olefin monomer (added along the gas recycle line 8) and a recycle portion (taken from the inner chamber 2) comprising recycled unreacted and / or partially reacted olefin.

[0023] With particular reference to FIG. 2, the gas distribution grid 7 is configured (and in particular comprises a plurality of openings 11 configured in this way) to allow the passage of fluidizing gas from the lower portion 3 to the upper portion 4 of the inner chamber 2 .

[0024] The fluidized bed reactor 1 also comprises a polymer discharge channel 17, which is configured to discharge the polymer obtained inside the upper part 4 from the upper part 4 itself (in particular downwards) in a discharge direction D (in particular through the lower part 3). More precisely, although not necessarily, the discharge direction D is substantially vertical (in particular parallel to the longitudinal extension of the fluidized bed reactor).

[0025] The fluidized bed reactor 1 further comprises a partition wall DW positioned around at least an extended portion of the polymer discharge channel 17 to define a first zone A of the inner chamber 2 and prevent the olefin monomer and the recycled unreacted and / or partially reacted olefin from entering the lower portion 3 and reaching the first zone A through the second end 10. The partition wall DW has at least a first portion DW' that is transverse (particularly perpendicular) to the discharge direction D.

[0026] The second end 10 is configured to supply fluidizing gas to the lower portion 3 in a direction transverse to the discharge direction D. In other words, the second end 10 is configured so that the fluidizing gas leaving the second end 10 moves in a direction transverse to the discharge direction D. In particular, the second end 10 (of the recycle line 8) is configured so that the recycle line 8 supplies the fluidizing gas leaving the second end 10 itself to the lower portion 3 in a direction transverse to (in particular, substantially perpendicular to) the discharge direction D.

[0027] In this way, it has been experimentally observed that the growth of polymer agglomerates in the lower part 3, in particular around the discharge channel 17, is surprisingly reduced. It should be noted that it has also been experimentally shown that the growth of polymer agglomerates is reduced in the region of the dividing wall DW.

[0028] This effect is believed to be due to the shape of the partition wall DW providing less (narrower) space for turbulent eddies and / or stagnation, which in turn favors the accumulation of fine particles. The direction of the fluidizing gas leaving the second end 10 has also been shown to play a role in the present context, in this way the fluid motion is particularly suited to the shape of the surfaces (particularly the partition wall DW).

[0029] In some specific, non-limiting cases, the recycle line 8 comprises a pipe, the stretch of which at the second end 10 extends transversely (particularly at an angle between 20° and 160°, more particularly between 60° and 120°, even more particularly substantially vertically) to the discharge direction D (particularly to the polymer discharge channel 17). In particular, such stretch of pipe of the recycle line 8 is substantially horizontal.

[0030] According to some embodiments not shown, the second end 10 is configured such that a fluidizing gas is supplied to the lower portion 4 through the lateral wall 5 .

[0031] In particular, the partition wall DW is located (at least partially) in the lower part 3 .

[0032] According to some non-limiting embodiments, the partition wall DW is a non-pressure-resistant partition. This means that the volume above the partition wall DW and the volume below the partition wall DW are maintained at the same pressure, preferably by a pressure equalization line, and the partition wall DW does not need to withstand the polymerization pressure in the fluidized bed reactor. In this regard, in some specific cases, monomer and / or clean gas (i.e., free of polymer fines) is fed into the first zone A, so that there is no pressure difference between the two sides of the partition wall (between the first zone A and the second zone B—described in more detail below).

[0033] According to some non-limiting embodiments, opening 11 comprises an opening 11' located less than 40 mm (particularly less than 20 mm, more particularly less than 5 mm) from inner surface 6 of lateral wall 5.

[0034] Advantageously, but not necessarily, the fluidized bed reactor 1 comprises lateral supports 12 that extend in a loop along and in contact with the inner surface 6 (and at least partially support the gas distribution grid 7). The gas distribution grid 7 is (at least) partially arranged on (in particular rests on) the lateral supports 12 and has a peripheral edge 13 that is in contact with the lateral supports 12. The lateral supports 12 have apertures 14, each of which is located below a corresponding opening 11' and is configured to allow the passage of fluidizing gas from the lower part 3 to the upper part 4 of the inner chamber 2 through the corresponding opening 11'. This ensures sufficient mechanical stability of the grid 7 without at the same time hindering passage through the openings 11'.

[0035] It should be noted that in FIG. 3 only a portion (approximately half) of the grid 7 is depicted in order to better show the structure of the lateral supports 12 .

[0036] According to some non-limiting embodiments, the openings 11 are formed so that the flow of the fluidizing gas after passing through the openings 11 is substantially parallel to the plane of the gas distribution grid 7 (in particular, substantially tangential to the gas distribution grid 7, more particularly, substantially horizontal).

[0037] Advantageously, but not necessarily, the opening 11 is a slot. According to some non-limiting embodiments, the width of the slot (opening 11) is greater than its height (in particular, greater than twice its height).

[0038] More precisely, but without any limitation, the opening 11 is made as disclosed in the applicant's patent application WO2008074632.

[0039] Advantageously, but not necessarily, the partition wall DW has at least one second portion DW'' facing the lower portion 3 outside the first area A and connected to the first portion DW' at an obtuse angle b.

[0040] Also, surprisingly, in this way a further reduction in the growth of polymer agglomerates in the lower part 3 is observed.

[0041] In some non-limiting embodiments, the fluidized bed reactor 1 includes an upper wall 15 that defines the top of the inner chamber 2 and is connected to the lateral wall 5, and a lower wall 16 that defines the bottom of the inner chamber 2 and is connected to the lateral wall 5.

[0042] The lower wall 16 is also connected to the partition wall DW (in particular to a first portion DW″ of the partition wall DW) at an obtuse angle a, facing the lower portion 3 outside the first region A. In particular, a second portion DW″ of the partition wall DW is also connected to the lower wall 16.

[0043] Surprisingly, experiments have confirmed that implementing these solutions further reduces the growth of polymer agglomerates within the lower part 3, especially at the junction between the lower wall 16 and the partition wall DW.

[0044] In particular, the first area A is at least partially defined by the lower wall 16 and the partition wall DW.

[0045] Advantageously, but not necessarily, the first portion DW' is substantially horizontal.

[0046] According to some non-limiting embodiments, the obtuse angle a is at least 100°, in particular at least 120° (in particular at most 170°, more particularly at most 150°).

[0047] Additionally or alternatively, the obtuse angle b is at least 100° (particularly less than 150°).

[0048] With particular reference to FIG. 6, according to some non-limiting embodiments, the partition wall DW is curved. In such cases, the partition wall DW is made up of an infinite number of portions DW′, DW″, … DW that are alternately arranged along the curve. n It can be said that it has

[0049] In contrast, FIG. 7 shows a non-limiting embodiment in which the partition wall DW has only one portion DW'.

[0050] In the embodiment of FIG. 2, the partition wall DW has two parts DW′ and DW″.

[0051] According to some non-limiting embodiments, the fluidized bed reactor 1 comprises a polymer discharge pipe 17' that horizontally defines a polymer discharge path 17 and extends (in particular from the upper part 4) through the lower wall 16. In particular, the partition wall DW intersects with the longitudinal extension of the polymer discharge pipe 17 (on the outer surface of the polymer discharge pipe 17).

[0052] Additionally or alternatively, the partition wall DW (or more precisely, the first part DW' of the partition wall DW, although this is not required) is connected to the outer surface of the polymer discharge pipe 17', so that the first region A is defined by the polymer discharge pipe 17', the partition wall DW and the lower wall 16.

[0053] According to some non-limiting embodiments, the lateral wall 5 extends substantially linearly with respect to the axial direction of the fluidized bed reactor 1 (in particular of the inner chamber 2). More precisely, although not necessarily, the lateral wall 5 extends substantially linearly with respect to the discharge direction D.

[0054] Additionally or alternatively, the lower wall 16 extends substantially transverse to the axial direction of the fluidized bed reactor 1 (in particular of the inner chamber 2). More precisely, although not necessarily, the lower wall 16 extends substantially transverse to the discharge direction D.

[0055] In some specific, non-limiting cases, the lower wall 16 is rounded. In particular, the lower wall 16 has a portion that is substantially perpendicular to the direction D (in the region of the discharge pipe 17′) and a portion that is at a very small angle (less than 1°) to the direction D (connected to the transverse wall 5).

[0056] According to some non-limiting embodiments, the lower portion 3 includes (and in particular consists of) a first region A and a second region B, to which a recycle line 8 is configured to supply fluidizing gas. A partition wall DW separates the first region A from the second region B (and separates the second region B from the first region A).

[0057] In particular, the second zone B is (at least partially) bounded by the partition wall DW, the bottom wall 16 and the grid 7 (and possibly the lateral wall 5 ) and is designed to receive fluidizing gas from the recycle line 8 .

[0058] In particular, the obtuse angles a and b lie within (face) the second region B.

[0059] In some non-limiting cases, the partition wall DW does not have an acute angle on its surface(s) facing the lower part 3 outside said first area A.

[0060] In particular, the partition wall DW is connected to the outer surface of the polymer discharge pipe 17' at an acute angle g facing the first region A of at least 10° (in particular at least 20°, in particular at most 50°, more particularly at most 40°).

[0061] According to some non-limiting embodiments, the polymer discharge pipe 17' is substantially parallel to the lateral wall 5. Additionally or alternatively, the polymer discharge pipe 17' is substantially parallel to the discharge direction D.

[0062] Advantageously, but not necessarily, the polymer discharge pipe 17' comprises an upper opening 18 that is integral with the gas distribution grid 7. In particular, the upper opening 18 of the polymer discharge pipe 17' is arranged in the center of the gas distribution grid 7. More particularly, the polymer discharge pipe 17' is configured to discharge the polymer produced in the upper part 4.

[0063] According to some non-limiting (and not shown) embodiments, the gas recycle line 8 is configured to transport the recycled portion of the fluidizing gas from the upper portion 4 of the inner chamber 2 through the upper wall 15 and the fluidizing gas through the lateral wall 5 to the lower portion 4.

[0064] According to some non-limiting embodiments, the discharge pipe 17' is equipped with a regulating means 21, such as a discharge valve, configured to regulate the mass flow rate of polymer discharged from the reactor 1. The opening of the regulating means 21 is continuously adjusted to maintain a constant height of the fluidized polymer bed in the reactor 1.

[0065] The discharge pipe 17 may be of uniform diameter, but advantageously comprises a portion with a decreasing diameter in the downward direction. The adjusting means 21 is advantageously arranged at the restriction between the larger and smaller diameter portions, as shown in Figure 1.

[0066] An alternative is a discharge system such as that disclosed in the applicant's patent application WO2007071527A1.

[0067] In a specific, non-limiting case, the gas recycle line 8 is provided with (a compressor 19 and) a heat exchanger 20 configured to reduce the heat of the recycle portion.

[0068] Advantageously, but not necessarily, the recycle line 8 is provided with a make-up line 22 for feeding fresh olefin monomer, molecular weight regulator, and optionally inert gas (in particular to the main pipe 23 of the recycle line 8). More precisely, but not necessarily, the make-up line 22 is configured to feed fresh olefin monomer, molecular weight regulator, and optionally inert gas (and antistatic agents, migration improvers, etc.) upstream of the compressor 19 (in particular between the upper part 4 and the compressor 19, more particularly upstream of the heat exchanger 20).

[0069] Advantageously, but not necessarily, the second end 10 of the recycle line 8 and the partition wall DW are configured such that the (flow of) fluidizing gas exiting the second end 10 (and in particular entering the lower portion 3, more particularly entering the second region B) is substantially tangential to at least a portion of the partition wall DW (in particular the first portion DW′ and / or the second portion DW″).

[0070] In this way, it has been surprisingly observed experimentally that the production of agglomerates at the partition wall DW is reduced even more consistently.

[0071] These effects have been thought to be due to the continuous cleaning of the surface of the partition wall DW by the movement of the fluidizing gas.

[0072] According to some non-limiting embodiments, the gas distribution grid 7 has substantially the form of the horizontal surface of a truncated (and inverted) cone.

[0073] According to a further aspect of the present invention, there is also provided herein a process for preparing an olefin polymer, comprising homopolymerizing an olefin or copolymerizing an olefin with one or more other olefins in the presence of a polymerization catalyst (particularly at a temperature of 20 to 200°C, particularly at a pressure of 0.5 to 10 MPa), wherein the polymerization is carried out in a fluidized bed reactor 1 as disclosed above.

[0074] According to some non-limiting embodiments, the fluidized bed reactor 1 is equipped with a polymer discharge pipe 17 through which polymer is continuously discharged.

[0075] According to some non-limiting embodiments, polymerization conditions are those conventionally employed in gas-phase reactors for olefin polymerization, i.e., temperatures in the range of 60 to 120°C and pressures in the range of 5 to 40 bar. Gas-phase polymerization processes can be combined with conventional techniques operating in slurry, bulk, or gas phase to carry out continuous multistage polymerization processes. Thus, upstream or downstream of the polymerization apparatus of the present invention, one or more polymerization stages operating in a loop reactor, a conventional fluidized-bed reactor, or a stirred-bed reactor can be provided. Specifically, gas-phase polymerization reactors with interconnected polymerization zones, such as those described in EP 782 587 and EP 1 012 195, can be advantageously located upstream or downstream of the apparatus of the present invention.

[0076] The gas phase polymerization process allows for the preparation of a large number of olefin powders with optimal particle size distributions, including a small amount of fines. The α-olefins advantageously polymerized by the process of the present disclosure have the formula CH═CHR, where R is hydrogen or a hydrocarbon radical having 1 to 12 carbon atoms. Examples of the resulting polymers are as follows: High density polyethylene (HDPE having a relative density greater than 0.940) including ethylene homopolymers and ethylene copolymers with α-olefins having 3 to 12 carbon atoms; Low density (LLDPEs with a relative density of less than 0.940) and very low and ultra low density (VLDPEs and ULDPEs with a relative density of 0.880 to less than 0.920) linear polyethylenes composed of ethylene copolymers with one or more α-olefins having 3 to 12 carbon atoms; elastomeric terpolymers of ethylene and propylene with small proportions of dienes or elastomeric copolymers of ethylene and propylene with a content of units derived from ethylene of about 30 to 70% by weight; Isotactic polypropylene, a crystalline copolymer of propylene with ethylene and / or other α-olefins, having a content of units derived from propylene of more than 85% by weight; Isotactic copolymers of propylene and α-olefins, such as 1-butene, having an α-olefin content of up to 30% by weight; impact propylene polymers obtained by sequential polymerization of propylene and mixtures of propylene and ethylene containing up to 30% by weight of ethylene; Atactic polypropylene, an amorphous copolymer of propylene and other α-olefins containing more than 70% by weight of units derived from ethylene and / or propylene.

[0077] The gas phase polymerization process disclosed herein is not limited to the use of any particular polymerization catalyst family, and can be carried out in any exothermic polymerization reaction using any catalyst, whether supported or unsupported, and whether in prepolymerized form or not.

[0078] The polymerization reaction can be carried out in the presence of a highly active catalyst system such as a Ziegler-Natta catalyst, a single-site catalyst, a chromium-based catalyst, or a vanadium-based catalyst.

[0079] Unless expressly stated otherwise, the contents of the references (articles, books, patent applications, etc.) cited in this document are incorporated herein in their entirety. In particular, the above-mentioned references are incorporated herein by reference.

Claims

1. A fluidized bed reactor for gas-phase polymerization of olefins, wherein the fluidized bed reactor (1) has an inner chamber (2) having, in order, at least one lower part (3) and at least one upper part (4), and the fluidized bed reactor (1) has at least one lateral wall (5) having an inner surface (6) that at least partially partitions the inner chamber (2) in the lateral direction, and a gas distribution grid (7) located inside the inner chamber (2) that at least partially separates the lower part (3) from the upper part (4), and the inner The apparatus comprises a reuse line (8) having a first end (9) connected to the inner chamber (2) at the upper part (4) of the chamber (2), and a second end (10) connected to the inner chamber (2) at the lower part (3) of the inner chamber (2); a polymer discharge passage (17) configured to discharge the polymer obtained inside the upper part (4) in the discharge direction (D) from the upper part (4) itself; and a lower wall (16) that partitions the lower part of the inner chamber (2) and is connected to the side wall (5), The reuse line (8) is configured to supply a fluidized gas containing fresh olefin monomer and a reuse portion containing reused unreacted and / or partially reacted olefin monomer to the lower part (3) of the inner chamber (2), The gas distribution grid (7) is configured to allow the fluidized gas to pass from the lower part (3) to the upper part (4) of the inner chamber (2), The fluidized bed reactor (1) further comprises a partition wall (DW) positioned around at least a portion of the polymer discharge channel (17) and, together with the lower wall (16), at least partially partitions the first region (A) of the inner chamber (2) and is configured to prevent the fresh olefin monomer and the reused unreacted and / or partially reacted olefin monomer flowing into the lower part (3) through the second end (10) from reaching the first region (A). The partition wall (DW) has at least one first portion (DW') that intersects the discharge direction (D), faces the lower part (3) outside the first region (A), and is connected to the lower wall (16) at a first obtuse angle (α), The fluidized bed reactor, wherein the second end (10) is configured to supply the fluidized gas to the lower part (3) in a direction intersecting the discharge direction (D).

2. The fluidized bed reactor according to claim 1, wherein the partition wall (DW) has at least a second portion (DW'') that is connected to the first portion (DW') at a second obtuse angle (β) outside the first region (A) and facing the lower portion (3), the first portion (DW') is horizontal, the second obtuse angle (β) is at least 100°, and the first obtuse angle (α) is at least 100°.

3. The polymer discharge passage (17) is partitioned laterally and includes a polymer discharge pipe (17') extending from the upper part (4) through the lower wall (16), the partition wall (DW) is connected to the outer surface of the polymer discharge pipe (17'), so that the first region (A) is partitioned by the polymer discharge pipe (17'), the partition wall (DW) and the lower wall (16), and the lower part (3) includes the first region (A) and the second region (B), and The fluidized bed reactor according to claim 1, wherein the partition wall (DW) separates the first region (A) from the second region (B) and is connected to the outer surface of the polymer discharge pipe (17') at an acute angle (γ) of at least 10° facing the first region (A), and further comprises an upper opening (18) integrated with the gas distribution grid (7) and is parallel to the side wall (5), and the gas distribution grid (7) has the shape of a truncated cone side.

4. The fluidized bed reactor according to claim 1, wherein the second end (10) of the reuse line (8) and the partition wall (DW) are configured such that the fluidized gas exiting the second end (10) is tangential to at least a portion of the partition wall (DW), the reuse line (8) is provided with a heat exchanger (20) configured to reduce the heat of the reuse portion, and further, a supply line (22) is provided for supplying the fresh olefin monomer, molecular weight modifier, and inert gas, antistatic agent, and transfer improver.

5. A method for preparing an olefin polymer, comprising homopolymerizing an olefin or copolymerizing an olefin with one or more other olefins in the presence of a polymerization catalyst, wherein the polymerization is carried out in a fluidized bed reactor (1) according to any one of claims 1 to 4, and the fluidized bed reactor (1) comprises a polymer discharge pipe (17') from which the polymer is continuously discharged.

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