PROCESS FOR THE PRODUCTION OF POLYMERS IN THE PRESENCE OF A POLYMERIZATION CATALYST IN A REACTOR ASS

专利摘要:
high-performance reactor system for the polymerization of olefins the present invention relates to a system of reactors for the production of polymers, including a fluidized bed reactor (1), comprising a bottom zone (5), an intermediate zone ( 6) and an upper zone (7), an inlet (8) for the fluidizing gas located in the bottom zone (5), an outlet (9) for the fluidizing gas located in the upper zone (7); the outlet (9) for the fluidizing gas being coupled to the fluidized bed reactor (1) through the inlet (8), through a gas circulation line; means for the separation of solids from gas (2) connected to the said gas circulation line, the equivalent cross-sectional diameter of the upper zone (7) being monotonically decreasing in relation to the direction of the fluidization gas flow through the reactor fluidized bed, the intermediate zone (6) with an equivalent diameter essentially constant in cross section in relation to the direction of the fluidization gas flow through the fluidized bed reactor, the equivalent cross-sectional diameter of the bottom zone (5) being monotonously increasing in relation to the flow direction of the fluidizing gas through the fluidized bed reactor, characterized by the fact that the ratio of the height of the fluidized bed reactor to the equivalent cross-sectional diameter of the intermediate zone of the fluidized bed reactor is 2 to 10, and wherein said upper zone (7) is directly connected to said intermediate zone a (6).
公开号:BR112013021740B1
申请号:R112013021740-5
申请日:2012-03-02
公开日:2020-02-11
发明作者:Günter Weickert；Erik Eriksson；Michiel Bergstra；Klaus Nyfors
申请人:Borealis Ag；
IPC主号:

专利说明:

Descriptive Report of the Invention Patent for PROCESS FOR THE PRODUCTION OF POLYMERS IN THE PRESENCE OF A POLYMERIZATION CATALYST IN A REACTOR ASSEMBLY.
[001] The present invention relates to a fluidized bed reactor assembly for the polymerization of olefinic monomer (s), as well as to a multiple reactor assembly comprising at least one fluidized bed reactor.
Background [002] Gas-phase reactors are normally used for the polymerization of olefins such as ethylene and propylene, as they allow for high relative flexibility in the design of polymers and in the use of various catalytic assemblies. A common variant of gas phase reactors is the fluidized bed reactor. In the production of polyolefins, olefins are polymerized in the presence of a polymerization catalyst in an upstream gas stream. The fluidizing gas is removed from the top of the reactor, cooled in a chiller, typically a heat exchanger, repressurized and fed back to the bottom of the reactor. The reactor typically contains a fluidized bed that comprises the growing polymeric particles, containing the active catalyst located above a distribution plate that separates the bottom and the intermediate or central zone of the reactor. The speed of the fluidizing gas is adjusted in such a way that a quasi-stationary situation is maintained, that is, the bed is maintained in fluidized bed conditions. In a quasi-stationary situation, gas and particle streams are highly dynamic. The required gas velocity depends mainly on the characteristics of the particles and is quite predictable within a given range of scales. Care must be taken so that the gas stream does not discharge the polymer material too much
2/51 of the reactor. This is usually accomplished by a zone called a withdrawal zone. This part in the upper part of the reactor is characterized by an increase in diameter, which reduces the gas speed. Thus, the particles that are transported along the bed with the fluidizing gas settle for the most part in the bed. Yet another fundamental problem with traditional fluidized bed reactors are limitations on cooling and drag capacity, due to the formation of large bubbles. It should be mentioned that the presence of bubbles as such is desirable, since the mixture is intensified in this way. However, the size of the bubble must be much smaller than the diameter of the reactor. Increasing the bed level in conventional fluidized bed reactors to increase the space-time yield leads to an increase in the size of the bubbles and to an unwanted entrainment of material from the reactor. In conventional reactors, there is no way to break the bubbles.
[003] Several models of modified gas phase reactors have been proposed. For example, WO-A-01/87989 proposes a fluidized bed reactor without a distribution plate and an asymmetric supply of the reaction components to the reaction chamber.
[004] M. Olazar describes a spouted bed reactor in Chem. Eng. Technol., 26 (2003), 8, pp. 845-852. In this reactor, a jet of fluids is introduced into a cylindrical or conical container containing solid. Under the right conditions, the jet penetrates the particles upwardly through the nozzle. The recirculation takes place in the outer phase next to the nozzle.
[005] Dual reactor assemblies comprising two reactors are also known. WO 97/04015 describes two coupled vertical cylindrical reactors, the first reactor being operated under rapid fluidization conditions. The first reactor with a bottom or bottom trunk-conical zone and an upper hemispherical zone is
3/51 attached to the second reactor, which is a sedimented bed reactor. Operation under fast fluidization conditions is carried out in a reactor that has an equivalent length / diameter ratio of about 5 or more.
[006] WO-A-01/79306 describes a gas-phase reactor assembly comprising a reactor that includes a distribution network coupled to a cyclone for separating solids and gaseous material. The separated solids are recycled back to the reactor.
[007] WO-A-2009/080660 reports the use of a gas phase reactor assembly as described in WO-A-97/04015, which comprises two interconnected reactors and a separation unit, the first being called a tube ascent and the second reactor, called descent tube. The first reactor is operated under the conditions of rapid fluidization.
[008] However, fluidized bed reactors and double reactor assemblies comprising a fluidized bed reactor described in the prior art still have several disadvantages.
[009] A first problem concerns the obstruction of the underside of the distribution plates, due to the dragging of fines transported with the circulating gas. This effect reduces the operational stability and the quality stability of the polymer. This problem can be partially overcome by slowing the fluidization gas. However, a relatively low fluidization gas speed limits the production rate and can lead to the formation of plates, blocks and lumps in the production of polyolefins. This conflict of objectives has generally been combated by the incorporation of a clearing zone. However, unblocking zones again limit the rate of production of a gas phase reactor of fixed dimensions, as there is a need for additional space above the top of the fluidized bed during operation. In dimension
4/51 industrial locations, the volume of the clearance zone is often more than 40% of the total reactor volume and insofar as it requires the construction of large unnecessary reactors.
[0010] A second problem concerns the formation of bubbles. Conventional fluidized bed reactors typically operate in a bubbling regime. A portion of the fluidizing gas passes through the bed in the emulsion phase, where the gas and solids are in contact with each other. The remaining part of the fluidizing gas passes through the bed in the form of bubbles. The velocity of the gas in the bubbles is greater than the velocity of the gas in the emulsion phase. In addition, the transfer of mass and heat between the emulsion phase and the bubbles is limited, especially for large bubbles that have a high volume to surface area ratio. Despite the fact that bubbles contribute positively to the mixing of powders, the formation of very large bubbles is also undesirable because the gas that passes through the bed in the form of bubbles does not contribute to the removal of heat from the bed in the same way as gas in the emulsion phase, and the volume occupied by the bubbles does not contribute to the polymerization reaction.
[0011] Yet another problem concerns the elimination of slabs, blocks and lumps. Complete absence of plates, blocks and lumps is quite difficult to achieve in conventional reactors. Usually, the plates, blocks and lumps are removed above the distribution plate by additional outlets and receiver units that can be connected and still do not allow complete removal of the plates, blocks and lumps.
[0012] Thus, there is still a need to improve the reactor design. The present invention aims to overcome the disadvantages of reactor designs known in the art and, in particular, it aims to avoid the segregation of fines, at a high production rate. The present invention also aims to avoid areas of
5/51 low productivity in the reactor. In addition, the present invention relates to the proportion of a reactor that allows for high operational stability and at the same time production of polymer with the highest quality. In yet another aspect, the present invention aims to assemble reactors that minimize the formation of plates, blocks and lumps.
Summary of the Invention [0013] The present invention is based on the realization that these problems can be overcome by a fluidized bed reactor that has a smaller cross-sectional area in the upper zone.
[0014] The present invention therefore provides a reactor assembly for the production of polymers that includes a fluidized bed reactor (1) comprising a bottom zone (5), an intermediate zone (6) and an upper zone (7), an inlet (8) for the fluidizing gas located in the bottom zone (5), an outlet (9) for the fluidizing gas located in the upper zone (7);
the outlet (9) for the fluidizing gas being coupled to the fluidized bed reactor (1) through the inlet (8) through a gas circulation line;
means for separating solids from the gas (2) being connected to said gas circulation line;
the diameter of the equivalent cross section of the upper zone (7) being monotonically decreasing in relation to the direction of the fluidization gas flow along the fluidized bed reactor;
the intermediate zone (6) having an equivalent cross-sectional diameter essentially constant in relation to the direction of the fluidization gas flow along the fluidized bed reactor;
characterized by the fact that the ratio of the height of the fluidized bed reactor to the diameter of the equivalent cross section of the intermediate zone of the fluidized bed reactor is 2 to 10; and
6/51 characterized by the fact that the upper zone (7) is directly connected to the intermediate zone (6).
[0015] The present invention further provides a reactor assembly comprising a moving bed reactor (15) that has a lower section (16) and an upper section (17), an inlet (18) for the barrier gas, a inlet (19) for solids and an outlet (20) for gas located in the upper section (17); an outlet (21) for removing solids from the moving bed reactor, the outlet (21) of the moving bed reactor being coupled to an inlet (23) of the fluidized bed reactor (1), with optional solid feeding means ( 22) located between them;
[0016] the gas / solid separation means (2) being coupled to the moving bed reactor (15) through the inlet (19).
[0017] The present invention further provides a process for the production of polymers in the presence of a polymerization catalyst in a reactor assembly that includes a fluidized bed reactor according to the present invention, which comprises the process:
feeding a gas mixture comprising at least one monomer to the bottom zone of said fluidized bed reactor;
removing a combined stream of gas and solids from the upper zone of said fluidized bed reactor, so as to produce a gas stream flowing upwardly within said fluidized bed reactor;
passing said combined stream through the gas / solid separation means;
removing from said gas / solids separation a top stream comprising less than 2% by weight of solids and directing to the bottom the said top stream comprising less than 2% by weight of solids;
7/51 feeding the polymerization catalyst in said fluidized bed reactor;
polymerizing said at least one monomer in the presence of said polymerization catalyst, so as to form a fluidized bed of polymer particles supported by said upwardly flowing gas stream;
characterized by the fact that said fluidized bed occupies at least 70% of the combined volume of the intermediate zone and the upper zone of said fluidized bed reactor.
[0018] In yet another aspect, the present invention provides a process for the production of polymers in the presence of a polymerization catalyst in a reactor assembly, including a fluidized bed reactor (1) comprising a gas inlet section first domain, where the surface velocity of the fluidizing gas is essentially constant, and a second domain that is located above the first domain, where the surface velocity of the fluidizing gas is higher in relation to the surface velocity of the gas in the first domain , an inlet for the fluidizing gas located in a gas inlet section, an outlet for the fluidizing gas located in the second domain, the outlet for the fluidizing gas being coupled to the fluidized bed reactor through a flow line of gas, means for the separation of solids from the gas being connected to the said gas circulation line, which comprises the process:
feeding in the first domain of said fluidized bed reactor, through the gas inlet section, a gas mixture comprising at least one monomer;
feeding polymerization catalyst in said fluidized bed reactor;
polymerizing said at least one monomer in the presence of the polymerization catalyst, so as to form a fluidized bed of polymer particles supported by said upwardly flowing gas stream;
passing said combined stream to gas / solids separation means;
removing from said separation step a top stream comprising less than 2% by weight of solids and directing said top stream comprising less than 2% by weight of solids to said gas inlet section.
Detailed Description of the Invention Definitions [0019] An overview of different types of fluidization and different fluidization regimes is given, for example, in section 17 of the Perry’s Chemical Engineers ’Handbook, vol. 8 (McGraw-Hill, 2008). Perry's Fig. 17-3 shows that conventional bubbling fluidized beds normally operate at surface gas speeds between the minimum fluidization speed and terminal speed. The turbulent beds operate at a gas velocity that is close to the terminal velocity. The transport reactors and circulation beds operate at gas speeds significantly higher than the terminal speed. Bubbling, turbulent and fast fluidized beds are clearly distinguishable and are explained in more detail in Perry’s, pages 17-9 to 17-11, incorporated by reference in this document. The calculation of minimum fluidization speed and transport speed is also discussed in Geldart. Gas Fluidization Technology, page 155 and following, J Wiley & Sons Ltd, 1986. This document is incorporated by reference.
[0020] Fluidized bed reactors are well known in the es
9/51 of the technique. In fluidized bed reactors, the fluidizing gas is passed through the fluidized bed under a determined surface speed. The surface velocity of the fluidizing gas must be greater than the fluidizing speed of the particles contained in the fluidized bed, otherwise fluidization would not occur. However, the surface velocity must be substantially less than the starting speed of pneumatic transport, otherwise the entire bed would be entrained with the fluidizing gas. An overview is given, for example, in Perry's, pages 17-1 to 17-12, or M Pell, Fluidization Gas (Elsevier, 1990), pages 1 to 18, and in Geldart, Gas Fluidization Technology, J Wiley & Sons Ltd, 1986.
[0021] The means for separating solids from gas (2) allows the separation of gas and solids, particularly dust. In the simplest embodiment these means can be a container in which the solids, in particular polymer, settle by gravity. However, generally the gas / solid separation means are at least one cyclone. A cyclone used in the assembly of reactors according to the present invention in its simplest form is a container in which a rotating flow is established. Cyclone design is well described in the literature. Cyclones particularly suitable are described in Kirk-Othmer documents, Encyclopaedia of Chemical Technology, 2nd edition (1966), Volume 10, pages 340-342, which are incorporated by reference herein.
[0022] Cooling means (3) are necessary in view of the exothermic nature of the polymerization reactions. The cooling means will normally be in the form of a heat exchanger.
[0023] The pressurization means (4) allow the adjustment of the speed of the fluidization gas. They are typically compressors.
[0024] The fluidized bed reactor comprises a bottom zone (5), an intermediate zone (6) and an upper zone (7). These zones
10/51 form the effective reaction zone that denotes the space within the fluidized bed reactor designated for the polymerization reaction. However, a person skilled in the art will understand that the polymerization reaction will continue, as long as the catalyst remains active and there is no monomer to polymerize. Thus, chain growth can also occur outside the effective reaction zone. For example, polymer collected in a container will further polymerize.
[0025] The terms bottom, intermediate and upper zone indicate the relative position in relation to the base of the fluidized bed reactor. The vertical fluidized bed reactor extends upwards from the base, in which the cross-section (s) of the fluidized bed reactor is (are) essentially parallel to the base.
[0026] The height of the fluidized bed reactor is the vertical distance between two planes, with the lower plane crossing the lowest point of the bottom zone and the upper plane crossing the highest point of the upper zone. The vertical distance indicates the distance along a geometric axis that forms an angle of 90 ° with the base and also with the two planes, that is, a gas entry zone (if present) must, for the sake of definition, contribute to the height of the fluidized bed reactor. The height of the individual zones is the vertical distance between the planes that limit the zones.
[0027] The term cross section as used here indicates the area of intersection with a plane that is parallel to the base. If not mentioned otherwise, the term cross section term always refers to the internal cross section without internal parts. For example, if the intermediate zone is cylindrical with an outer diameter of 4.04 m and the cylinder wall has a thickness of 0.02 m, the inner diameter will be 4.00 m, as a result of which the cross section will be 2 , 0 x 2.0 x nm ² ~ 12.6 m ² .
11/51 [0028] The term free cross section denotes the area of the total cross section that allows exchange of gases and particles. In other words, in a sectional drawing with the section passing along the plane formed by the interphase plane of the cross section of the bottom zone and the cross section of the intermediate zone, the free cross section is the area that is unobstructed.
[0029] Having an essentially constant cross-sectional diameter indicates an equivalent cross-sectional diameter with a variation of less than 5%.
[0030] Variation must mean the difference between the maximum diameter of the equivalent cross section and the minimum diameter of the equivalent cross section versus the average equivalent diameter. For example, if the maximum equivalent cross-sectional diameter was 4.00 m, the minimum equivalent cross-sectional diameter was 3.90 m and the average equivalent cross-sectional diameter was 3.95 m; the variation would be (4.00 - 3.90) m / 3.95 m = 0.025, that is 2.5%.
[0031] Monotonically decreasing must be understood in a mathematical sense, that is, the average diameter will decrease or be constant in relation to the direction of the fluidization gas flow along the fluidized bed reactor. Monotonically decreasing equivalent cross-section diameter includes two situations, namely, decreasing the diameter of the equivalent cross-section with respect to the direction of the flow of the fluidizing gas through the fluidized bed reactor and also constancy of the diameter of the equivalent cross-section in relation to the direction of the fluidization gas flow. It should be understood, however, that even if a zone with a monotonically decreasing diameter in the direction of flow may have sections with an essentially constant diameter, the diameter at the end downstream of the zone is always smaller than the diameter at the end upstream of the zone .
12/51 [0032] By strictly and monotonically decreasing it is understood that the diameter of the equivalent cross section will decrease in relation to the direction of the fluidization gas flow along the fluidized bed reactor. Thus, if a zone has a rigorous and monotonically decreasing diameter in the direction of flow, therefore, at any point h in the zone the diameter is smaller than at any other point upstream of said point h.
[0033] The expressions monotonically increasing and rigorous and monotonically increasing must be understood accordingly. [0034] Diameter of the equivalent cross section is the normal diameter in the case of a circular cross section. If the cross-section is not circular, the equivalent cross-sectional diameter is the diameter of a circle that has the same cross-sectional area as the non-circular cross-section.
[0035] For the sake of definition, the three reaction zones, the bottom zone, the intermediate zone and the upper zone should differ in terms of their equivalent cross-sectional diameter. In other words, the limit plane that delimits the bottom zone and the intermediate zone must be the plane in which the diameter of the cross section changes from increasing values to essentially constant values. The limit plane that delimits the intermediate zone and the upper zone must be the plane in which the diameter of the cross section changes from essentially constant values to decreasing values. In the subsequent text, diameter is also used in the sense of equivalent cross-sectional diameter for non-circular surfaces.
[0036] Conical geometry plays an important role in the present invention. A cone is a three-dimensional geometric shape that tapers from a flat surface to the apex. This plane will generally be a circle, but it can also be elliptical. All cones also have an axis which is the straight line that passes through the vertex, on which the side surface has a rotational symmetry.
[0037] From a more functional perspective, the fluidized bed reactor according to the present invention includes a gas inlet section, a first domain, in which the surface velocity of the fluidization gas is essentially constant, and a second domain that is located above the first domain, where the surface velocity of the fluidizing gas is higher than the first domain, an inlet for the fluidizing gas located in the gas inlet section, an outlet for the fluidizing gas located in the second domain, the outlet for the fluidizing gas being coupled to the fluidized bed reactor through a gas circulation line, and means for the separation of gas solids that connect to the gas circulation line.
[0038] The gas inlet section is the part of the reactor where the fluidizing gas enters the reactor. In this section, the bed is formed.
[0039] The first domain is the part of the reactor in which the surface velocity of the fluidizing gas is essentially constant.
[0040] The second domain is located above the first domain and is the part of the reactor where the surface velocity of the fluidizing gas is higher in relation to the surface velocity of the gas in the first domain.
[0041] A top stream comprising less than 2% by weight of solids means that 98% or more, by weight, of the stream is present in gaseous form under the conditions normally required for operation.
[0042] Gas speed means the surface speed of the gas. [0043] Gas inlet section denotes the part of the appliance where the feeding takes place and the bed is formed. The gas inlet section, therefore, differs from the so-called first and second domains.
14/51 [0044] The first domain indicates the part of the fluidized bed reactor, where the surface velocity of the fluidizing gas is essentially constant.
[0045] The second domain is located vertically above the first domain and indicates the part of the fluidized bed reactor where the surface speed of the fluidizing gas is higher than the surface speed of the gas in the first domain.
[0046] Directly connected means that two zones are directly adjacent.
[0047] The top stream is a stream that is taken from the gas / solid separation media, such as a cyclone. When a cyclone is used, the top stream originates from the top stream, that is, not from undercurrent or bottom stream.
Description [0048] A new reactor assembly has several advantages. In a first aspect, there is no clearing zone. This leads to an economic construction. The reactor can be operated so that the bed occupies almost the total volume of the reactor. This allows for greater reactor output / dimensions ratios, leading to substantial cost savings. In addition, the polymer is evenly distributed inside the reactor in the bed area and is accompanied by a better coalescence of gas bubbles. It was also surprisingly found that the local flow of solids to the reactor wall is high, which leads to a constant cleaning of the wall, particularly in the upper zone. In another aspect, it has surprisingly been found that inside the reactor assembly, the entrainment of fines with the fluidizing gas is reduced as the undesirably large bubbles are destroyed. In addition, the heat removal from the polymer as a function of the bed height is more uniform and there is a better dispersion between the gas and the polymer, as in reactors and
15/51 state of the art processes.
[0049] Another important advantage of the present invention is that the separation of the polymer from the fluidizing gas, for example, using a cyclone, can be easily accomplished due to a high concentration of solids in the fluidizing gas. It was surprisingly found that the solids content in the fluidizing gas, after the gas / solid separation, is much lower in the present invention compared to a plant / process, resulting in a feeding to the gas / solid separation media characterized by a lower amount of solids. In other words, the relatively high amount of solids, prior to gas / solids separation, in the present invention surprisingly results in a better degree of solids separation.
[0050] It is preferred that the reactor assembly according to the present invention comprises an inlet for the catalyst or catalyst containing prepolymer. In the simplest embodiment, the catalyst or prepolymer containing catalyst can be fed through the fluidization gas inlet. However, a separate entry for the catalyst or catalyst containing prepolymer allows for a good mixing of the catalyst in the bed. More preferably, the catalyst is fed to the most turbulent zone.
[0051] In one embodiment, the assembly of reactors according to the present invention preferably comprises an outlet for removing plates, blocks and lumps. Although the rate of formation of slabs, blocks and lumps is extremely low, it is not possible to eliminate this formation to zero under all reaction conditions. If present, the outlet for removing slabs, blocks and lumps will preferably be located in the lowest part of the bottom area. In the most preferred embodiment, the outlet will be positioned in the center of the bottom zone. When the bottom zone has a conical shape, the exit will preferably coincide with the vertex
16/51 of the cone.
[0052] In a second embodiment, the exit for the removal of plates, blocks and lumps is accompanied by means for the breaking of plates, blocks and / or lumps. Such means for breaking boards, blocks and / or lumps are commercially available and are discussed, among other things, in Stolhandske, Powder and Bulk Engineering, July 1997 edition, pages 49-57, and Feldman, Powder and Bulk Engineering , June 1987 edition, pages 26-29, both documents being incorporated by reference in this document.
[0053] As explained above, the fluidized bed reactor according to the present invention comprises three zones, a bottom zone (5), an intermediate zone (6) and an upper zone (7).
[0054] In a first and preferred embodiment, the fluidized bed reactor according to the present invention consists of three zones, a bottom zone (5), an intermediate zone (6) and an upper zone (7).
[0055] In a second embodiment, the fluidized bed reactor according to the present invention comprises more than three zones, a bottom zone (5), an intermediate zone (6) and an upper zone (7), and at least one additional zone, where at least one additional zone is located below the bottom zone (5) in relation to the direction of the fluidization gas flow. This additional zone is shown in Fig. 4.
[0056] The diameter of the equivalent cross section of the upper zone is preferably strict and monotonically decreasing in relation to the direction of the fluidization gas stream, that is, generally in an upward vertical direction.
[0057] The intermediate zone of the fluidized bed reactor will typically be in the form of a circular cylinder, which is designated here yes
17/51 only cylinder. However, it is possible that the intermediate zone of the fluidized bed reactor is in the form of an elliptical cylinder. Then, the bottom region is preferably in the form of an oblique cone. Then, more preferably, the upper region is also in the form of an oblique cone.
[0058] From a more functional perspective, the intermediate zone will essentially form the first domain in which the surface velocity of the fluidization gas is essentially constant. The upper zone will essentially form the second domain where the surface velocity of the fluidizing gas is higher than the first domain.
[0059] The upper part of the reactor assembly according to the present invention preferably has a shape such that a stream of gas particles adjacent to the inner wall is created, which stream of gas particles is directed downwardly to the base. This stream of gas particles leads to an excellent distribution of gas particles and an excellent thermal balance. In addition, the high speed of the gas and particles adjacent to the inner wall minimizes the formation of lumps and plates.
[0060] It is further preferred that the ratio of the height of the upper zone to the diameter of the intermediate zone is within the range of 0.3 to 1.5, more preferably 0.5 to 1.2, and even more preferably 0 , 7 to 1.1.
[0061] It is particularly preferred that the reactor assembly according to the present invention includes an upper zone which is cone shaped and an intermediate zone which is cylindrical in shape. The cone forming the upper zone is preferably a straight circular cone and the cylinder forming the intermediate zone is preferably a circular cylinder.
[0062] More preferably, the taper angle of the su zone
18/51 cone-shaped top is 10 ° to 50 °, more preferably 20 to 40 °. As defined above, the taper angle is the angle between the cone axis and the lateral area (Fig. 3).
[0063] The specific taper angles of the upper cone-shaped zone further improve the tendency to reflux of the particles in countercurrent to the fluidizing gas. The resulting single pressure balance leads to an intensive burst of bubbles, as a result of which the space-time performance is further improved. In addition, as mentioned above, the flow velocity in the wall, i.e., the velocity of particles and gas adjacent to the inner wall is sufficiently high to prevent the formation of lumps and plates.
[0064] The reactor assembly according to the present invention preferably has a bottom zone shaped such that the particles distribute the gas along the cross section of the entire bed. In other words, the particles function as a gas distribution network. In the bottom zone, gas and solids are mixed under conditions of high turbulence. Because of the shape of the zone, the velocity of the gas gradually decreases within that bottom zone and conditions change so that a fluidized bed is formed.
[0065] The following specifically preferred reactor geometries can be combined with the first embodiment mentioned above consisting of three zones, a bottom zone (5), an intermediate zone (6) and an upper zone (7), and the second embodiment, which includes at least one additional zone, in which that zone or zones are located / are located below the bottom zone.
[0066] Preferably, the diameter of the equivalent cross section of the bottom zone (5) is monotonically increasing in relation to the flow direction of the fluidizing gas along the fluidized bed reactor
19/51. As the flow direction of the fluidizing gas rises in relation to the base, the diameter of the zone's equivalent cross section increases vertically and monotonically. Monotonic increase must be understood in a mathematical sense, that is, the average diameter will increase or be constant in relation to the direction of the fluidization gas flow along the fluidized bed reactor.
[0067] The diameter of the equivalent cross section of the bottom zone is preferably rigorous and monotonically increasing in relation to the direction of the flow of the fluidization gas along the reactor, that is, generally vertically upward.
[0068] More preferably, the bottom zone is tapered and the intermediate zone is cylindrical.
[0069] The bottom zone preferably has a right circular cone shape and in the middle zone it has the shape of a circular cylinder. Alternatively, the intermediate zone is in the form of an elliptical cylinder and the bottom zone and the upper zone are in the form of oblique cones.
[0070] More preferably, the taper angle of the cone-shaped bottom zone is 5 ° to 30 °, even more preferably, 7 ° to 25 °, and even more preferably, 9 ° to 18 °, whereby the cone angle is the angle between the cone axis and the lateral surface (Fig. 2).
[0071] It is further preferred that the equivalent diameter of the bottom zone increases from about 0.1 to about 1 meter by one meter in height of the bottom zone. More preferably, the diameter increases from 0.15 to 0.8 m / m, and in particular from 0.2 to 0.6 m / m.
[0072] The preferred taper angles lead to better additional fluidization behavior and prevent the formation of stagnation zones. As a result, the quality of the polymer and the stability of the process are improved. Especially, an angle of co
20/51 too wide aity leads to uneven fluidization and poor distribution of the gas within the bed. Although a very narrow angle has no detrimental effect on the fluidization behavior, it nevertheless leads to a larger bottom zone than necessary and is therefore not economically viable.
[0073] However, as mentioned above, in a second embodiment, there is at least one additional zone that is located below the bottom zone. It is preferable that the so-called at least one additional zone, or if there is more than one additional zone, the total of the additional zones, contributes to a maximum of 15% of the total height of the reactor, preferably 10% of the total height of the reactor, and even more preferably, less than 5% of the total height of the reactor. A typical example of an additional zone is a gas inlet zone.
[0074] Preferably, there is an unobstructed passage in the direction of the fluidization gas flow along the fluidized bed reactor, between the bottom zone (5) and the upper zone (7). An unobstructed passageway includes all geometries that allow substantially free gas and particle exchange between and within those zones. An unobstructed passage is characterized by the absence of internal parts, such as distribution plates or grids, resulting in substantially high flow resistivity. An unobstructed passage is characterized by a ratio between the free cross section / total cross section in relation to the separation between the bottom zone and the intermediate zone of at least 0.95, where the free cross section is the area that allows exchange of gases and where the total cross section is the area of the internal cross section of the reactor limited by the wall of the fluidized bed reactor.
[0075] This will be explained by way of an example. When the intermediate zone has a cylindrical shape with an internal diameter of 4
21/51 meters, the total cross section is about 2.0 χ 2.0 χ π m ² ~ 12.6 m ² . If the area of the free cross section, that is, the area that allows gas exchange, is at least 12.0 m ² , the criteria for an unobstructed passage will be met. A typical example of an internal part that leads to a small reduction in the cross section that allows gas and solids exchange is a vertical tube. That tube or a plurality of tubes directs the flow and thus has a guide function. However, as the thickness of the pipe wall (and fasteners) only limits the cross section to a very small degree, the exchange of gases and solids will not be essentially limited.
[0076] The fluidized bed reactor assembly according to the present invention can be used for the production of polymers on a commercial scale, for example, with a production capacity between 2 and 40 tons per hour or 10 to 30 tons per hour .
[0077] The reactor assembly according to the present invention preferably includes means for injection of the fluidizing gas, with an injection angle within the range of 120 ° to 150 ° with respect to the vertical axis of the fluidized bed reactor. The vertical axis forms an angle of 90 ° with the base. More preferably, the means for injecting the fluidizing gas allows an injection angle in the range of 130 ° to 140 °.
[0078] Furthermore, the reactor assembly according to the present invention preferably comprises an outlet for the polymer. In the simplest variant of the reactor assembly, the polymer can be removed by the cyclone. The outlet for the polymer is preferably located in the intermediate zone. Most preferably, the outlet is in the form of a nozzle. There will normally be numerous nozzles located in the middle zone.
[0079] Advantageously, the polymer is removed directly from the fluidized bed, which means that the outlet nozzle removes polymer from
22/51 of a level that is above the base of the fluidized bed, but below the upper level of the fluidized bed. It is preferred to remove the polymer continuously, as described in WO 00/29452. However, it is also possible to remove polymer from the circulating gas line which removes the fluidizing gas from the top of the reactor. The polymer is then properly separated from the gas stream, for example, using a cyclone. Also a combination of the two methods described above can be used so that a part of the polymer is removed directly from the bed and another part, from the circulating gas line.
[0080] The circulating gas is cooled in order to remove the heat of polymerization. This is typically done on a heat exchanger. The gas is cooled to a temperature that is lower than that of the bed to prevent the bed from heating up due to the reaction. It is possible to cool the gas to a temperature at which a part of it condenses. When the liquid droplets enter the reaction zone, they are vaporized. The heat of vaporization then contributes to the removal of the reaction heat. This type of operation is called condensate mode and variations of it are described, among other things, in WO-A-2007/025640, US-A-4,543,399, EP-A-699213 and WO-A94 / 25495. It is also possible to add condensing agents to the recycle gas stream, as described in EP-A-696.293. Condensing agents are non-polymerizable components, such as n-pentane, isopentane, n-butane or isobutane, which are at least partially condensed in the chiller.
[0081] When producing olefin polymers in the presence of olefin polymerization catalysts, the surface gas velocity in the intermediate zone is suitably in the range of 5 to 80 cm / s (or from 0.05 to 0.8 m / s).
[0082] The reactor can be used for the polymerization of monomers in the presence of a polymerization catalyst. Monomers
23/51 that can thus be polymerized include olefins, diolefins and other polyenes. The reactor can therefore be used to polymerize ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, styrene, norbornene, vinylnorbornene , vinylcyclohexane, butadiene, 1,4-hexadiene, 4-methyl-1,7octadiene, 1,9-decadiene and mixtures thereof. In particular, the reactor is useful in the polymerization of ethylene and propylene and their mixtures, optionally in combination with other alpha-olefin comonomers having from 4 to 12 carbon atoms.
[0083] In addition to monomers, different coreagents, adjuvants, activators, catalysts and inert components can be introduced into the reactor.
[0084] Any polymerization catalyst can be used to initiate and maintain polymerization. Such catalysts are well known in the art. In particular, the catalyst must be in the form of a particulate solid on which polymerization takes place. Suitable catalysts for the polymerization of olefins are, for example, Ziegler-Natta catalysts, chromium catalysts, metallocene catalysts and final transition metal catalysts. Different combinations of two or more of these catalysts, often referred to as double-site catalysts, can also be used.
[0085] Suitable examples of Ziegler-Natta catalysts and components used in such catalysts are presented, for example, in WO-A-87/07620, WO-A-92/21705, WO-A-93/11165, WOA- 93/11166, WO-A-93/19100, WO-A-97/36939, WO-A-98/12234, WOA-99/33842, WO-A-03/000756, WO-A-03/000757, WO-A-03/000754, WO-A-03/000755, WO-A-2004/029112, WO-A-92/19659, WO-A92 / 19653, WO-A-92/19658, US-A- 4382019, US-A-4435550, US-A4465782, US-A-4473660, US-A-4560671, US-A-5539067, US-A
24/51
5618771, EP-A-45975, EP-A-45976, EP-A-45977, WO-A-95/32994, US-A-4,107,414, US-A-4,186,107, US-A-4,226. 963, US-A-4,347,160, US-A-4,472,524, US-A-4522930, US-A-4530912, US-A-4532313, USA-4657882, US-A-4581342, US-A- 4657882, EP-A-688794, WO-A99 / 51646, WO-A-01/55230, WO-A-2005/118655, EP-A-810.235 and WOA-2003/106510.
[0086] Examples of suitable metallocene catalysts are given in WO-A-95/12622, WO-A-96/32423, WO-A-97/28170, WO-A-98/32776, WO-A-99 / 61489, WO-A-03/010208, WO-A03 / 051934, WO-A-03/051514, WO-A-2004/085499, EP-A-1752462, EP-A-1739103, EP-A-629631, EP-A-629632, WO-A-00/26266, WO-A02 / 002576, WO-A-02/002575, WO-A-99/12943, WO-A-98/40331, EPA-776.913, EP- A-1074557 and WO-A-99/42497.
[0087] Catalysts are normally used with different activators. Such activators are generally organic aluminum or boron compounds, typically aluminum trialkyls, alkyl aluminum halides, alumoxanes. In addition, different modifiers can be used, such as, for example, ethers, alkoxysilanes and esters, and the like.
[0088] In addition, different currents can be used. They include chain transfer agents, such as hydrogen and polymerization inhibitors, such as, for example, carbon monoxide or water. In addition, an inert component is used properly. Such an inert component can be, for example, nitrogen or an alkane having 1 to 10 carbon atoms, such as methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, nhexane or the like. Mixtures of different inert gases can also be used.
[0089] Polymerization is conducted at a temperature and pressure where the fluidization gas remains essentially in the form of
25/51 steam or gas phase. For the polymerization of olefins, the temperature is suitably in the range of 30 to 110 ° C, preferably 50 to 100 ° C. The pressure is suitably in the range of 0.1 to 5.0 MPa (1 to 50 bar), preferably 0.5 to 3.5 MPa (5 to 35 bar).
[0090] The reactor is preferably operated under conditions such that the bed occupies at least 70% of the combined volume of the intermediate zone and the upper zone, more preferably at least 75% and even more preferably at least 80%. The same numbers are maintained for the inventive processes according to the present invention. When the reactor is operated in this way, it turns out that, surprisingly, the bubbles burst at the top of the reactor or are prevented from growing. This is advantageous for several reasons. First, when the volume occupied by the bubbles is reduced, the reactor volume is more effectively used for polymerization and the dead volume is reduced. Second, the absence of large bubbles reduces the entrainment of fines from the reactor. Instead, the polymer that is transported out of the reactor with the fluidizing gas represents the total polymer inside the reactor. Therefore, it is possible to separate the polymer from the fluidization gas, for example, using a cyclone, and remove that polymer as a product or direct it to later polymerization stages. Third, although the polymer is dragged from the reactor together with the fluidizing gas, it is surprisingly easier to separate the polymer from the fluidizing gas than if the amount of polymer was less. Therefore, when the fluidization gas taken from the top of the reactor is passed through a cyclone, the resulting top stream surprisingly contains a smaller amount of polymer than in a conventional fluidized bed reactor equipped with a similar cyclone. Thus, reactor assemblies and processes according to the present invention combine a fluidized bed reactor and means for separating
26/51 solids / gas in a synergistic manner. In addition, the underflow current has better flow properties and is less prone to clogging than in a similar conventional process.
[0091] The fluidization gas taken from the top of the reactor is directed to a separation step. As discussed above, this step is conveniently performed in a cyclone. In a cyclone, the gas stream containing particles enters a cylindrical or conical chamber tangentially to one or more points. The gas exits through a central opening in the upper part of the chamber (top) and the particles, through an opening in the lower part (subflow). The particles are forced by inertia to the cyclone wall from where they fall. Typically, the top contains less than 2% by weight or less than 1% by weight, preferably less than 0.75% and more preferably less than 0.5% by weight of solid material, particularly polymer particles. The subflow normally contains mainly solid material and includes some gas between the particles.
[0092] In a preferred embodiment, the fluidizing gas enters the gas inlet zone below the bottom zone of the fed fluidized bed reactor. In this gas inlet zone, any gas and any polymer or catalyst particles are mixed under turbulent conditions. The speed of the fluidization gas is such that any catalyst or polymer particles contained therein are transferred to the bottom zone. However, polymer agglomerates, such as lumps or plates, fall off and can thus be removed from the reactor. In a typical embodiment of the gas inlet zone, it is a tube normally with a diameter such that the gas velocity is greater than about 1 m / s, such as from 2 to 70 m / s, preferably from 3 to 60 m / s. It is also possible that the gas inlet zone has an increasing diameter in the direction of flow, so that the gas velocity at the top
27/51 or the gas inlet zone is smaller than at the bottom. [0093] In the preferred embodiment discussed above, the gas enters the bottom zone through the gas inlet zone. The gas inlet zone, for the sake of definition, should not be seen as part of the reactor and therefore should not contribute to the height of the reactor. Within the bottom zone, the fluidized bed is formed. The gas velocity is gradually reduced so that at the top of the bottom zone the surface velocity of the gas is from about 0.02 m / s to about 0.9 m / s, preferably from 0.05 to about 0.8 m / s and more preferably from about 0.07 to about 0.7 m / s, such as 0.5 m / s or 0.3 m / s or 0.2 m / s or 0.1 m / s.
[0094] Furthermore, in the aforementioned preferred embodiment, the surface velocity of the fluidizing gas decreases in the bottom area, preferably so that the value of a, which is the inverse of the square root of the surface velocity, expressed in m / s, a = 1 / v, where v is the surface velocity of the fluidizing gas, increase by a value within the range of 0.66 to 4.4 per one meter in length of the bottom zone. More preferably, the value of a, as defined above, increases by a value within the range of 0.94 to 3.6, even more preferably from 1.2 to 2.5 per one meter in length of the bottom zone. Naturally, the value of a increases in the direction of the fluidization gas flow in the bottom zone, that is, in the upward direction.
[0095] Preferably, the surface velocity of the fluidizing gas decreases monotonically in the bottom zone, remains at a constant level within the intermediate zone and increases monotonically in the upper zone. Especially preferably, the surface speed increases as described above.
[0096] The present invention also relates to an assembly of double reactors for the production of polymers, including a reactor of
Fluidized bed (1), a gas / solids separation medium (2), a moving bed reactor (15), cooling means (3, 24) and pressurizing means (4, 25);
the fluidized bed reactor (1) comprising a bottom zone (5), an intermediate zone (6) and an upper zone (7), an inlet (8) for the fluidizing gas located in the bottom zone (5) and an outlet (9) located in the upper zone (7);
the movable bed reactor (15) having a lower section (16) and an upper section (17), an inlet (18) for the barrier gas, an inlet (19) for the solids and an outlet (20) for gas located in the upper section (17); an outlet (21) for removing solids from the moving bed reactor, the outlet (21) of the moving bed reactor being coupled to an inlet (23) of the fluidized bed reactor (1), with optional solid feeding means ( 22) located between them;
the outlet (9) being coupled to the gas / solid separation means (2), the gas / solid separation means (2) being coupled to the moving bed reactor (15) through the inlet (19);
the intermediate zone (3) having an equivalent cross-sectional diameter essentially constant in relation to the flow direction of the fluidizing gas along the fluidized bed reactor;
the diameter of the equivalent cross section of the upper zone (7) being monotonically decreasing in relation to the direction of the fluidization gas flow along the fluidized bed reactor;
characterized by the fact that the ratio between the height of the fluidized bed reactor and the diameter of the equivalent cross section of the intermediate zone of the fluidized bed reactor is 2 to 10; and characterized by the fact that the upper zone (7) is directly connected to the intermediate zone (6).
[0097] The double reactor assembly is a combination of the reactor assembly described above with a moving bed reactor. All
29/51 the preferred definitions and embodiments, as described above, also apply in relation to the assembly of double reactors. These definitions and preferred embodiments are incorporated by reference in this document.
[0098] The lower section (16) of the moving bed reactor preferably represents the bottom part of the moving bed reactor which contributes to 50% of the total volume of the moving bed reactor. The upper section (17) of the moving bed reactor preferably represents the upper part of the moving bed reactor which contributes to 50% of the total volume of the moving bed reactor.
[0099] The assembly of double reactors according to the present invention has the additional advantages in addition to the advantage of the assembly of reactors described above. It should be mentioned that the advantages of the reactor assembly described above are not lost. In a first aspect, the dual reactor configuration allows simple production of polyolefins with molecular weight distribution adapted by using different reaction conditions in the first and second reactors. In addition, the assembly of double reactors prevents the incorporation of fines into growing polymer particles.
[00100] The double reactor assembly is a combination of the reactor assembly described above with a moving bed reactor. All preferred definitions and embodiments, as described above, also apply in relation to the assembly of double reactors. These definitions and preferred embodiments are incorporated by reference in this document.
[00101] As discussed above, the polymer entrained by the fluidizing gas of the fluidized bed reactor is passed through separation means, preferably by means of a cyclone. The polymer is separated from the gas and a stream of purified gas is removed as a
30/51 top and a stream of solids is removed as a bottom stream. As discussed above, the polymer in the solids stream represents the total polymer within the fluidized bed and therefore can be removed as a product stream and directed to downstream operations, such as, for example, in a moving bed reactor.
[00102] The moving bed reactor according to the present invention has a lower section and an upper section. From a functional point of view, the bottom section is mainly the polymerization and collection section of the polymer produced. The upper section is mainly the section for removing gas from the moving bed reactor. Preferred moving bed reactors are described in more detail in WO-A2004 / 111095 and WO-A-2004/111096, incorporated by reference in this document.
[00103] The moving bed reactor according to the present invention preferably has an inlet for the barrier gas. The inlet for the barrier gas is preferably located in the lower section of the moving bed reactor. More preferably, the entrance to the barrier gas is at a height of less than 40% of the total height of the moving bed reactor. The barrier gas makes it possible to operate the fluidized bed reactor and the mobile bed reactor independently of each other. The flow of the barrier gas prevents fluidization gas from entering the moving bed reactor and disrupting its reaction conditions. The barrier gas also allows easy cooling of the moving bed reactor. In particular, the barrier gas may include liquid components that are vaporized in the moving bed reactor, thereby cooling the bed.
[00104] The moving bed reactor according to the present invention also includes an inlet for solids. This solids inlet is preferably used to feed separate particles into the cyclone. However, it is also possible to initiate polymerization by feeding the prepolymer to the moving bed reactor through the inlet.
31/51 [00105] The moving bed reactor according to the present invention also includes an outlet for the fluidizing gas which is preferably located in the upper section.
[00106] In addition, the moving bed reactor includes an outlet for the removal of solids from the moving bed reactor. This outlet is preferably coupled to a solids inlet of the fluidized bed reactor.
[00107] The feeding of the solids from the mobile bed reactor to the fluidized bed reactor is carried out by means of feeding. In the simplest form, the feeding means is a simple gravity ramp preferably controlled by adjustable valves. However, it is preferable that the feeding is carried out by a screw. Suitable methods for feeding the solids are described in EP-A2090357, EP-A-2090356, EP-A-2082797 and copending European Patent Application No. 10075723.6. These documents are hereby incorporated by reference. Preferably, the feed tube comprises a densification zone between the thread outlet and the fluidized bed reactor, to prevent the fluidizing gas from entering the moving bed reactor through the screw feeder.
[00108] The fluid bed reactor volume / moving bed volume ratio is preferably in the range 50/1 to 3/1, preferably 30/1 to 5/1.
[00109] The polymer, along with a small amount of fluidizing gas is directed to the top of the moving bed reactor. The polymer deposits in the reactor to form a bed of polymer particles. From the bottom of the moving bed, polymer is removed to form a polymer outlet stream from the moving bed reactor. This outlet stream can be removed as a polymer product and directed to downstream operations, or, alternatively and preferably, it can be returned to the fluidized bed reactor.
[00110] At least one monomer is introduced at the bottom of the
32/51 moving bed reactor. Preferably, the monomer is introduced below the level which represents 30% of the total height of the moving bed measured from the bottom of the moving bed. More preferably, the monomer is introduced below the level that represents 20%, even more preferably below the level that represents 10% of the total height of the moving bed.
[00111] The monomer can be the same used in the fluidized bed reactor. Monomers that can thus be polymerized include olefins, diolefins and other polyenes. The reactor can therefore be used to polymerize ethylene, propylene, 1-butene, 1-pentene, 1hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, styrene, norbornene, vinylnorbornene , vinylcyclohexane, butadiene, 1,4hexadiene, 4-methyl-1,7,7-octadiene, 1,9-decadiene and mixtures thereof. In particular, the reactor is useful in the polymerization of ethylene and propylene and their mixtures, optionally in conjunction with other alpha-olefin comonomers having from 4 to 12 carbon atoms.
[00112] Especially preferably, at least one of the polymerized monomers in the moving bed reactor is the same as that polymerized in the fluidized bed reactor. In particular, at least the main monomer, which constitutes at least 50% of the total monomer in the moving bed reactor, is the same monomer that constitutes at least 50% of the total monomer in the fluidized bed reactor.
[00113] It is preferred that polymers with different properties are produced in the moving bed reactor and in the fluidized bed reactor. In a preferred embodiment, the polymer produced in the moving bed reactor has a different molecular weight and, optionally, also a different comonomer content than the polymer produced in the fluidized bed reactor. To achieve this goal, a barrier gas is introduced into the moving bed reactor. The purpose of the barrier gas is to produce a liquid stream (net stream) of gas that flows upwards into the interior.
33/51 of the moving bed reactor. This upwardly flowing gas stream has a composition that is different from the fluidizing gas stream composition. The polymerization in the moving bed is then determined by the composition of the gas stream that flows upwards.
[00114] The components of the barrier gas include the monomer (s) to be polymerized (s), possible chain transfer agent (s) and eventual gas or inert gases. As mentioned above, one or all of the barrier gas components can be introduced into the moving bed reactor as a liquid which then vaporizes into the moving bed. The barrier gas is introduced at the bottom of the moving bed reactor, as described above for the monomer.
[00115] As mentioned above, the gas flows upwardly inside the moving bed reactor. The surface speed of the upwardly flowing gas stream must be less than the minimum fluidization speed of the particles that form the moving bed, otherwise the moving bed would be at least partially fluidized. Therefore, the surface velocity of the gas stream should be from 0.001 to 0.1 m / s, preferably from 0.002 to 0.05 m / s, and more preferably from 0.005 to 0.05 m / s.
[00116] The barrier gas that passes through the moving bed is removed from the upper part of the moving bed reactor by a gas outlet located in the reactor. Most of the fluidizing gas entering the top of the moving bed reactor together with the polymer is removed via the same outlet.
[00117] As the polymer is removed from the base of the bed, the particles move slowly down into the bed. The movement is preferably substantially piston flow, in which the distribution of particle residence times in the reactor is narrow. Therefore, each particle has substantially the same time to
34/51 to undergo polymerization inside the moving bed reactor and no particles passed through the reactor without having time to not polymerize. This is a difference for a perfectly mixed reactor, such as a fluidized bed reactor, in which the residence time distribution is very wide.
[00118] According to a preferred embodiment in the moving bed reactor, a propylene copolymer is produced which has a higher molecular weight than that of the propylene copolymer produced in the fluidized bed reactor. Then, the barrier gas mixture introduced at the base of the bed contains propylene and comonomer, such as ethylene. In addition, it may contain a small amount of hydrogen. The fluidizing gas contains propylene, comonomer and a relatively high amount of hydrogen. The gas mixture above the moving bed is removed from the upper area of the moving bed reactor. In this way, the molar ratio of hydrogen to propylene in the moving bed can be kept at a lower level than the corresponding ratio in the fluidizing gas. In this way, the molecular weight of the polymer produced in the moving bed reactor is greater than that of the polymer produced in the fluidized bed reactor.
[00119] When adjusting the composition of the barrier gas, the polymer produced in the moving bed reactor may, alternatively, have a lower molecular weight, or alternatively or additionally, have a higher or lower comonomer content than the polymer produced in the reactor fluidized bed. It is, of course, also possible to adjust the conditions so that the same polymer is produced in the two reactors.
[00120] The temperature inside the moving bed reactor can be adjusted according to needs. However, it must be below the sintering temperature of the polymer contained in the reactor. The temperature can be appropriately chosen to be within the range
35/51 from 40 to 95 ° C, preferably from 50 to 90 ° C and more preferably from 65 to 90 ° C, such as 75 or 85 ° C.
[00121] The pressure at the top of the moving bed reactor is preferably close to the pressure at the top of the fluidized bed reactor. Preferably, the pressure is 0.1 to 5.0 MPa (1 to 50 bar), more preferably 0.5 to 3.5 MPa (5 to 35 bar). Especially preferably, the pressure differs by no more than 0.5 MPa (5 bar) from the pressure within the fluidized bed reactor. Even more preferably, the pressure is within the range of 0.3 MPa (3 bar) less than the pressure within the fluidized bed reactor to the same pressure as within the fluidized bed reactor.
[00122] From the process point of view, the intermediate zone of the fluidized bed reactor is maintained under conditions, such that the surface velocity of the gas is 5 to 80 cm / s, preferably 10 to 70 cm / s .
[00123] The polymerization catalyst can be fed directly or it can come from a previous prepolymerization phase, the latter being preferable. The polymerization catalyst is preferably introduced into the intermediate zone through the respective inlet. The withdrawal of the reaction product is preferably continuous as described in WO-A-00/29452.
[00124] In a preferred embodiment according to the present invention, the assembly of reactors according to the present invention further comprises a closed loop reactor upstream of the fluidized bed reactor.
[00125] In the following, the processes according to the present invention are described further. Preferred ranges and dimensions, as discussed above in relation to the reactor, also apply to processes and are incorporated by reference in this document.
[00126] The present invention relates to a process for the production
36/51 polymerization in the presence of a polymerization catalyst in a reactor assembly that includes a fluidized bed reactor as described above. The process comprises feeding a gas mixture comprising at least one monomer to the bottom zone of said fluidized bed reactor;
removing a combined stream of gas and solids from the upper zone of the fluidized bed reactor, so as to produce a stream of gas that flows upwardly within the fluidized bed reactor;
passing said combined stream to the gas / solid separation means;
removing from said gas / solids separation a top stream comprising less than 2% by weight of solids and directing the top stream comprising less than 2% by weight of solids to the bottom zone;
feeding the polymerization catalyst in said fluidized bed reactor;
polymerizing said at least one monomer in the presence of said polymerization catalyst, so as to form a fluidized bed of polymer particles supported by the upwardly flowing gas stream;
wherein the fluidized bed occupies at least 70% of the combined volume of the intermediate zone and the upper zone of said fluidized bed reactor.
[00127] The present invention also relates to a process for the production of polymers in the presence of a polymerization catalyst in a reactor assembly that includes a fluidized bed reactor as described above, which comprises the process of removing a first stream polymer from said separation step;
direct at least part of said first polymer stream
37/51 for a moving bed reactor;
feeding a second gas mixture comprising at least one monomer to said moving bed reactor;
polymerizing said at least one monomer in said moving bed reactor;
removing a second polymer stream from the bottom of said moving bed reactor, thereby establishing a downward moving polymer bed;
directing at least a part of said second polymer stream to said fluidized bed reactor.
[00128] The present invention also relates to a process for the production of polymers in the presence of a polymerization catalyst in a reactor assembly, including a fluidized bed reactor (1) comprising a gas inlet section, a first domain above and adjacent to the gas inlet section, in which the surface velocity of the fluidizing gas is essentially constant, and a second domain being located above and adjacent to the first domain, in which the surface velocity of the fluidizing gas is highest in relation to the surface velocity of the gas in the first domain, an inlet for the fluidizing gas located in a gas inlet section, an outlet for the fluidizing gas located in the second domain, the outlet for the fluidizing gas being coupled to the reactor fluidized bed by means of a gas circulation line, the means for the separation of gas solids being connected to the reference gas circulation line, which comprises the process:
food in the first domain of said fluidized bed reactor, for example
38/51 middle of the gas inlet section, a gas mixture comprising at least one monomer;
feeding the polymerization catalyst in said fluidized bed reactor;
polymerizing said at least one monomer in the presence of said polymerization catalyst, so as to form a fluidized bed of polymer particles supported by said upwardly flowing gas stream;
passing said combined stream to gas / solids separation means;
removing a top stream comprising less than 2% by weight of solids from said separation step and directing said top stream comprising less than 2% by weight of solids to said gas inlet section.
[00129] The processes according to the present invention preferably concern the polymerization of polyolefins. More preferably, the polyolefins are monomers selected from the group of ethylene, propylene and alpha-olefins from C4 to C ₁₂ .
Brief Description of the Drawings [00130] Fig. 1 is a cross-sectional drawing of the reactor assembly that includes a fluidized bed reactor.
[00131] Fig. 2 is a sectional drawing of the bottom area in the shape of a cone. The taper angle is shown being the angle between the cone axis and the lateral surface.
[00132] Fig. 3 is a sectional view of the upper cone-shaped zone.
[00133] Fig. 4 shows an embodiment of a fluidized bed reactor consisting of four zones, bottom zone (5), intermediate zone (6) and upper zone (7), and an additional zone located below the bottom zone.
39/51 [00134] Fig. 5 is a cross-sectional drawing of the double reactor assembly according to the invention.
Reference list cyclone fluidized bed reactor cooling means means for pressurization bottom zone intermediate zone top zone inlet for fluidization gas outlet line for recycling of solids inlet for catalyst or prepolymer outlet for plates, blocks and lumps means for breaking plates outlet for polymer moving bed reactor lower section of moving bed reactor top section of moving bed reactor inlet for injection of a barrier gas (moving bed reactor) inlet for solids (moving bed reactor) outlet for gas ( moving bed reactor) outlet for solids to be recycled feed media for solid recycling input for solid feed / recycling media for cooling (moving bed) media for pressurization (moving bed)
Detailed description in relation to the drawings [00135] The invention will now be explained in relation to the drawings.
40/51 [00136] According to Fig. 1, the reactor assembly according to the invention includes a fluidized bed reactor 1 with a cone-shaped bottom zone 5, a cylindrical intermediate zone 6 and a upper cone-shaped zone 7.
[00137] The assembly of reactors is further equipped with gas / solids separation means 2 and cooling means 3, as well as means for pressurization 4.
[00138] The fluidized bed reactor has an inlet 8 for the fluidizing gas located in the bottom zone 5.
[00139] The fluidized bed reactor further comprises an outlet for the fluidizing gas 9 located in the upper zone 7. Through outlet 9, the fluidizing gas is passed through cyclone 2, the cooling means 3 and the pressurizing means 4 to the gas inlet 8 of the fluidized bed reactor.
[00140] The bottom zone 5 and the intermediate zone 6 (and also the upper zone 7) form an unobstructed passage since there is no distribution plate.
[00141] The diameter of the cross section of the bottom zone 5 is strict and monotonically increasing in relation to the direction of the fluidization gas flow along the fluidized bed reactor. In Fig. 1, the increase in cross-sectional diameter is constant in the vertical direction, as the bottom area is only curved in two dimensions, but not in three dimensions.
[00142] The intermediate zone 6 has the diameter of the cross section constant in relation to the direction of the flow of the fluidization gas along the fluidized bed reactor.
[00143] Additional installations, such as control equipment, are not shown in Fig. 1.
[00144] The cross-sectional diameter of the upper zone 7 is monotonically decreasing in the direction of the fluidization gas flow
41/51 along the fluidized bed reactor.
[00145] Fig. 3 is a sectional drawing of the upper cone-shaped zone.
[00146] Fig. 4 shows an embodiment of a fluidized bed reactor that consists of four zones, bottom zone (5), intermediate zone (6) and upper zone (7), and an additional zone located below the bottom zone.
[00147] The perspective view of Fig. 5 represents the assembly of double reactors according to the invention, as a sectional drawing.
Examples
General conditions used for examples [00148] In examples 1 to 5, the reactor was operated at an absolute pressure of 0.1 MPa (1 bar) and a temperature of 25 ° C. Air was used as the fluidizing gas. The bed was formed of polyethylene particles with an average diameter of about 250 pm. The polyethylene had a specific mass of 923 kg / m ³ and an MFR ₅ of 0.24 g / 10 min.
[00149] The invention was exemplified with a reactor assembly
res having the following propertiesBottom zone height: 1,330 mm Middle zone height: 2,050 mm Upper zone height: 415 mm Diameter of the intermediate zone: 480 mm
[00150] The reactor was made of Plexiglas so that the fluidization behavior and the dimensions of the bubbles inside the bed could be observed visually.
42/51
Table 1 (Examples 1 to 5)
1 2 3 4 5 fluidization gas flow [m ³ / h] 65195 130bed height *[mm] 1,100 2,100 1,500 degree of bed filling ** [%] 49 94 stable stable stable lump removal stable lump removal stable
starting from the plane that separates the lower and intermediate zones ** in relation to the volume of the intermediate and upper zones
Example 1 [00151] The reactor, as described above, was operated so that the flow rate of the fluidizing gas was 65 m ³ / h and the bed height was 1,100 mm (which corresponds to about 49% of the combined volume intermediate and upper zones), from the bottom of the cylindrical section. The gas flow corresponds to a surface gas velocity of 10 cm / s.
[00152] It can be seen that the size of the bubbles increased when the bubbles reached the top of the bed.
Example 2 [00153] The procedure of Example 1 was repeated, with the exception that the bed height was 2,100 mm (corresponding to 94% of the combined volume of the intermediate and upper zones). In this case too, the reactor could be operated in a stable manner for hours. The polymer carried by the fluidizing gas could easily be
43/51 separated from the gas in a separation vessel in which the polymer was left to settle and a clean fluidizing gas stream containing less than 1% by weight of particles was obtained. The polymer recovered in the separation vessel was a representative sample of the total polymer. Thus, no segregation of polymer fines could be observed.
[00154] It can be seen that, although small bubbles were present in the fluidized bed, large bubbles with a diameter greater than half the diameter of the bed were absent.
Example 3 [00155] The procedure of Example 1 was repeated, except that the gas flow was 195 m ³ / h, corresponding to a surface gas velocity of 30 cm / s. The reactor operation was stable and without problems. During the operation, lumps weighing about 12 grams were introduced into the upper part of the fluidized bed. On average, within a period of about 400 seconds the lumps traveled along the bed to the bottom of the reactor and it was possible to remove them through the tube in an upright position at the bottom.
Example 4 [00156] The procedure of Example 1 was repeated, except that the gas flow was 130 m ³ / h, corresponding to a surface gas velocity of 20 cm / s. During the operation, lumps weighing about 12 grams were introduced into the upper part of the fluidized bed. On average, within a period of about 700 seconds the lumps traveled along the bed to the bottom of the reactor and could be removed by the pipe in an upright position at the bottom.
Example 5 [00157] The procedure of Example 4 was repeated, except that the bed height was 1,500 mm. The polymer carried by the fluidizing gas could be easily separated from the gas in a
44/51 separation, in which the polymer was left to settle and a clean fluidizing gas stream containing less than 1% by weight of particles was obtained. During the operation, lumps weighing about 12 grams were introduced into the upper part of the fluidized bed. On average, within a period of about 2,700 seconds the lumps traveled along the bed to the bottom of the reactor and could be removed by the pipe in an upright position at the bottom.
Example 6 [00158] The invention was further exemplified with a reactor made of steel, having the following dimensions:
Height of bottom area: 1,680 mm
Diameter at the bottom of the bottom zone: 175 mm
Height of the intermediate zone: 2,050 mm
Upper zone height: 670 mm
The diameter of the intermediate zone: 770 mm [00159] The operation of the reactor was stable and without problems.
[00160] The reactor described above was used for the copolymerization of ethylene and 1-butene at a temperature of 80 ° C and a pressure of 2.0 MPa (20 bar). The height of the fluidized bed, calculated from the bottom of the intermediate zone, is 2,100 mm.
[00161] Ethylene homopolymer (MFR ₂ = 300 g / 10 min, specific mass of 974 kg / m ³ ) produced in a closed circuit reactor and still containing the dispersed active catalyst was introduced into the reactor through an inlet located in the bottom zone at a rate of 40 kg / h. Ethylene, hydrogen and 1-butene were continuously introduced into the circulating gas line so that the concentration of ethylene in the fluidizing gas was 17 mol%, the ratio of 1-butene to ethylene was 100 mol / kmol and the hydrogen to ethylene ratio was 15 mol / kmol. The fluidization gas memory was nitrogen. The gas flow was adjusted so that the surface velocity
45/51 of the gas in the cylindrical part of the reactor was 15 cm / s. The resulting copolymer could be easily removed through an outlet at a rate of 80 kg / h.
[00162] The fluidization gas removed from the top of the reactor was passed through a cyclone. The polymer separated from the gas was mixed with the aforementioned homopolymer stream and, thus, returned to the fluidized bed reactor.
Comparative Example 7 [00163] For comparison, a conventional fluidized bed reactor (hemispherical bottom, cylindrical body, conical part connected to another cylindrical zone forming an unblocking zone) was used, equipped with a fluidization grid.
Height of gas inlet zone
(below the fluidization grid): 1,080 mm Diameter of the cylindrical part: 800 mm Height of cylindrical part(above the fluidization grid) 1,870 mm Conical height *: 2,270 mm Clearing zone height: 1,730 mm Clearance zone diameter: 1,600 mm
connected to the cylindrical part of the clearance zone [00164] The yield was the same as in Example 6. However, the combined volume of the reaction zone (0.94 m ³ ), the clearance zone (4.12 m ³ ) and the conical section that joins the two zones mentioned above (2.66 m ³ ) was about 7.7 m ³ , which greatly exceeds the total volume of the design of Example 6, which was 1.7 m ³ .
Example 8 [00165] The assembly of reactors comprising a moving bed reactor was used in the polymerization of propylene, as follows: [00166] Polymer sludge containing unreacted propylene and ho
46/51 propylene mopolymer with an MFR10 fluidity index of 0.42 g / 10 min was introduced into the reactor operated at 85 ° C and 3.0 MPa (30 bar), so that the polypropylene feed rate was 36 kg / h and the polymer concentration in the sludge, about 50% by weight. Additional propylene and hydrogen, as well as nitrogen as an inert gas, were fed to the reactor so that the propylene content was 73 mol% and the hydrogen to propylene ratio was 186 mol / kmol. The production rate of the fluidized bed reactor was 44 kg / h. The surface velocity of the fluidizing gas in the fluidized bed reactor was 25 cm / s. The bed height, calculated from the bottom of the intermediate cylindrical zone, was 2,100 mm.
[00167] The reaction mixture of the fluidized bed reactor was removed through an outlet in the top cone and introduced into a second mobile gas phase reactor operated at a temperature of 85 ° C and a pressure of 2.0 MPa ( 20 bar). Additional propylene was introduced into the moving bed reactor in the middle of the lower cylindrical section. The hydrogen to propylene ratio at the bottom of the moving bed reactor was 0.75 mol / kmol. The production rate of the reactor was 8 kg / h. The polymer was then reintroduced into the bottom cone of the fluidized bed reactor, using a screw feeder.
[00168] The polypropylene was removed from the fluidized bed reactor through the outlet located at the bottom of the cylindrical section, at a rate of 88 kg / h.
Comparative Example 9 [00169] The procedure of Example 6 was repeated, except that the bed height was adjusted to 1,100 mm, calculated from the bottom of the intermediate zone. The rate of production of the copolymer in the fluidized bed reactor was then 21 kg / h, so that a total of 61 kg / h of copolymer were removed from the fluidized bed reactor. The reduction in the total polymer production rate compared to the
47/51
Example 6 was thus 19 kg / h.
In the following paragraphs, preferred embodiments of the invention are described:
[00170] 1. A reactor assembly for the production of polymers, including a fluidized bed reactor 1 comprising a bottom zone 5, an intermediate zone 6 and an upper zone 7, an inlet 8 for the fluidizing gas located in the bottom zone 5, an outlet 9 for the fluidizing gas located in the upper zone 7;
the outlet 9 for the fluidizing gas being coupled to the fluidized bed reactor 1 through the inlet 8 via a gas circulation line;
means for separating solids from gas 2 that connect to the gas circulation line;
the diameter of the equivalent cross section of the upper zone 7 being monotonically decreasing in relation to the flow direction of the fluidization gas along the fluidized bed reactor;
the intermediate zone 6 having an equivalent cross-sectional diameter essentially constant with respect to the direction of the fluidization gas flow along the fluidized bed reactor;
characterized by the fact that the ratio between the height of the fluidized bed reactor and the diameter of the equivalent cross section of the intermediate zone of the fluidized bed reactor is 2 to 10; and in which the upper zone 7 directly connects to the intermediate zone 6.
[00171] 2. A reactor assembly for the production of polymers according to clause 1, in which the upper zone 7 is cone-shaped and the intermediate zone 6 is cylindrical.
[00172] 3. A reactor assembly for the production of polymers according to clause 2, in which the angle of the cone of the upper zone in the form of a cone 7 is from 10 ° to 50 °.
[00173] 4. A reactor assembly according to any
48/51 one of the preceding clauses, in which the bottom zone 5 of the fluidized bed reactor 1 is monotonically increasing in relation to the direction of the fluidization gas flow along the fluidized bed reactor and in which there is an unobstructed passage in the direction of the fluidization gas flow along the fluidized bed reactor from the bottom zone 5 to the top zone 7.
[00174] 5. A reactor assembly for the production of polymers according to any of the preceding clauses, which further comprises an inlet 11 for the catalyst or catalyst containing prepolymer.
[00175] 6. An assembly of reactors for the production of polymers according to clause 4 or 5, which also includes an outlet 12 for the removal of plates, blocks and lumps.
[00176] 7. A reactor assembly for the production of polymers according to clause 6, in which the outlet 12 for the removal of plates, blocks and lumps is located in the bottom zone 5.
[00177] 8. An assembly of reactors for the production of polymers according to clause 7, further comprises means 13 for the breaking of plates, blocks and / or lumps.
[00178] 9. A reactor assembly for the production of polymers according to any of the preceding clauses, in which the ratio between the height of the upper zone and the diameter of the equivalent cross section of the intermediate zone is in the range of 0.3 to 1.5.
[00179] 10. A reactor assembly for the production of polymers according to clauses 4 to 8, in which the taper angle of the bottom area in the shape of a cone 5 is from 5 ° to 25 °.
[00180] 11. An assembly of reactors for the production of polymers according to any of the preceding clauses, which further comprises an outlet 14 for the polymer.
[00181] 12. A reactor assembly according to any
49/51 one of the preceding clauses, which further comprises a moving bed reactor 15 having a lower section 16 and an upper section 17, an inlet 18 for the barrier gas, an inlet 19 for solids and an outlet 20 for localized gas in the upper section 17; an outlet 21 for removal of solids from the moving bed reactor, the outlet 21 of the moving bed reactor being coupled to the inlet 23 of the fluidized bed reactor 1, with optional solids feeding means 22 located between them;
the gas / solids separation means 2 being coupled to the moving bed reactor 15 through the inlet 19.
[00182] 13. A reactor assembly according to the clause
12, which further comprises at least one outlet 14 for the polymer in the fluidized bed reactor and / or in the moving bed reactor.
[00183] 14. A reactor assembly in accordance with any of the preceding clauses, which further comprises a closed circuit reactor upstream of the fluidized bed reactor.
[00184] 15. A process for the production of polymers in the presence of a polymerization catalyst in a reactor assembly that includes a fluidized bed reactor according to any of clauses 1 to 14, which comprises the process:
feeding to the bottom area of the fluidized bed reactor a gas mixture comprising at least one monomer;
removing a combined stream of gas and solids from the upper zone of the fluidized bed reactor, so as to produce a stream of gas that flows upwardly within the fluidized bed reactor;
passing the combined stream to gas / solid separation media; removing a top stream comprising less than 2% by weight of solids from the gas / solids separation and directing the top stream comprising less than 2% by weight of solids to the bottom zone; feed polymerization catalyst to the fluidized bed reactor;
50/51 polymerizing said at least one monomer in the presence of said polymerization catalyst, so as to form a fluidized bed of polymer particles supported by said upwardly flowing gas stream;
characterized by the fact that said fluidized bed occupies at least 70% of the combined volume of the intermediate zone and the upper zone of said fluidized bed reactor.
[00185] 16. A process according to clause 15 for the production of polymers in the presence of a polymerization catalyst in a reactor assembly that includes a fluidized bed reactor according to clause 12, which comprises the process of removing a first polymer stream from said separation step;
directing at least a part of said first polymer stream to a moving bed reactor;
feeding to the said moving bed reactor a second gas mixture comprising at least one monomer;
polymerizing said at least one monomer in the moving bed reactor;
withdrawing a second polymer stream from the bottom of said moving bed reactor thereby establishing a moving downward polymer bed;
directing at least a part of said second polymer stream to the fluidized bed reactor.
[00186] 17. A process for the production of polymers in the presence of a polymerization catalyst in a reactor assembly, which includes a fluidized bed reactor 1 comprising a gas inlet section a first domain above and adjacent to the section gas inlet, where the surface velocity of the fluidizing gas is essentially
51/51 constant, and a second domain located above and adjacent to the first domain, where the surface velocity of the fluidizing gas is higher in relation to the surface velocity of the gas in the first domain, an entrance to the localized fluidizing gas in a gas inlet section, an outlet for the fluidizing gas located in the second domain, the outlet for the fluidizing gas being coupled to the fluidized bed reactor through a gas circulation line, the means for the separation of gas solids being connected to the said gas circulation line, which comprises the process:
feeding in the first domain of said fluidized bed reactor, through the gas inlet section, a gas mixture comprising at least one monomer;
feed polymerization catalyst in said fluidized bed reactor;
polymerizing said at least one monomer in the presence of the polymerization catalyst, so as to form a fluidized bed of polymer particles supported by said upwardly flowing gas stream;
passing said combined stream to gas / solids separation means;
removing a top stream comprising less than 2% by weight of solids from said separation step and directing said top stream comprising less than 2% by weight of solids to said gas inlet section.

权利要求:
Claims (11)
[1]
1. Process for the production of polymers in the presence of a polymerization catalyst in a reactor assembly that includes a fluidized bed reactor (1) comprising a bottom zone (5), an intermediate zone (6) and an upper zone (7), an inlet (8) for the fluidizing gas located in the bottom zone (5), an outlet (9) for the fluidizing gas located in the upper zone (7);
the outlet (9) for the fluidizing gas being coupled to the fluidized bed reactor (1) through the inlet (8) through a gas circulation line;
means for separating solids from the gas (2) being connected to the gas circulation line;
the diameter of the equivalent cross section of the upper zone (7) being monotonically decreasing in relation to the direction of the fluidization gas flow along the fluidized bed reactor, where the diameter of the monotonically decreasing equivalent cross section means that the diameter of the cross section equivalent will decrease or be constant in relation to the direction of the fluidization gas flow through the fluidized bed reactor;
where the ratio between the height of the upper zone and the diameter of the equivalent cross section of the intermediate zone is within the range of 0.7 and 1.1;
the intermediate zone (6) having an equivalent cross-sectional diameter essentially constant in relation to the direction of the fluidization gas flow along the fluidized bed reactor;
the diameter of the equivalent cross section of the bottom zone being monotonically increasing in relation to the direction of the fluidization gas flow along the fluidized bed reactor, in which the diameter of the monotonically equivalent cross section is increasing
[2]
2/5 te means that the average diameter increases or is constant in relation to the flow direction of the fluidization gas along the fluidized bed reactor;
wherein monotonically decreasing equivalent cross-sectional diameter means that the equivalent cross-sectional diameter will decrease or be constant in relation to the direction of the fluidization gas flow through the fluidized bed reactor;
characterized by the fact that the ratio between the height of the fluidized bed reactor and the diameter of the equivalent cross section of the intermediate zone of the fluidized bed reactor is 2 to 10;
where the limit plane that delimits the bottom zone and the intermediate zone is the plane in which the diameter of the equivalent cross section changes from increasing values to essentially constant values;
where the limit plane that delimits the intermediate zone and the upper zone is the plane in which the diameter of the equivalent cross section changes from essentially constant values to decreasing values;
wherein said upper zone (7) is directly connected to the intermediate zone (6);
wherein there is an unobstructed passage in the direction of the fluidization gas flow along the fluidized bed reactor from the bottom zone (5) to the upper zone (7);
the process comprising:
feeding in the bottom area of the reactor of said fluidized bed a gas mixture comprising at least one monomer;
removing a combined stream of gas and solids from the upper zone of said fluidized bed reactor, so as to produce a stream of gas that flows upwardly within said reactor
[3]
3/5 fluidized bed;
passing said combined stream to the gas / solid separation means;
removing a top stream comprising less than 2% by weight of solids from said gas / solids separation and directing to the bottom zone said top stream comprising less than 2% by weight of solids;
feeding the polymerization catalyst in said fluidized bed reactor;
polymerizing said at least one monomer in the presence of said polymerization catalyst, so as to form a fluidized bed of polymer particles supported by said upwardly flowing gas stream;
wherein said fluidized bed occupies at least 70% of the combined volume of the intermediate zone and the upper zone of said fluidized bed reactor; and a part of said upwardly flowing gas stream forms an emulsion phase with the polymer particles and the remainder passes through the bed in the form of bubbles.
2. Process, according to claim 1, characterized by the fact that it comprises:
removing a first polymer stream from said separation step;
directing at least a portion of the first polymer stream to a moving bed reactor;
feeding to the said moving bed reactor a second gas mixture comprising at least one monomer;
polymerizing said at least one monomer in said moving bed reactor;
remove a second polymer stream from the bottom of the meal
[4]
4/5 fast moving bed reactor thus establishing a moving bed of descending polymer; and directing at least a part of said second polymer stream to said fluidized bed reactor.
3. Process according to claim 1 or 2, characterized by the fact that the surface velocity of the gas in the intermediate zone is greater than the minimum fluidization speed and less than the terminal velocity.
Process according to any one of claims 1 to 3, characterized in that the angle of the cone in the upper cone-shaped zone (7) is 10 ° to 50 °.
[5]
Process according to any one of claims 1 to 4, characterized in that it further comprises an inlet (11) for the catalyst or catalyst containing prepolymer.
[6]
6. Process according to claim 4 or 5, characterized by the fact that it also comprises an outlet (12) for removing slabs, blocks and lumps.
[7]
7. Process according to claim 6, characterized by the fact that the outlet (12) for removing slabs, blocks and lumps is located in the bottom zone (5).
[8]
8. Process according to any one of claims 1 to 7, characterized by the fact that it further comprises means (13) for breaking plates, blocks and / or lumps.
[9]
Process according to any one of claims 1 to 8, characterized by the fact that the ratio between the height of the upper zone and the diameter of the equivalent cross section of the intermediate zone is within the range of 0.3 to 1.5 .
[10]
Process according to any one of claims 1 to 9, characterized in that the taper angle of the cone-shaped bottom zone (5) is 5 ° to 25 °.
5/5
[11]
Process according to any one of claims 1 to 10, characterized by the fact that it further comprises a moving bed reactor (15) that has a lower section (16) and an upper section (17), an inlet (18 ) for barrier gas, an inlet (19) for solids and an outlet (20) for gas located in the upper section (17); an outlet (21) for removing solids from the moving bed reactor, the outlet (21) of the moving bed reactor being coupled to the inlet (23) of the fluidized bed reactor (1), with optional solids feeding means (22 ) located between them;
the gas / solids separation means (2) being coupled to the moving bed reactor (15) through the inlet (19).

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法律状态:
2019-02-05| B07A| Technical examination (opinion): publication of technical examination (opinion) [chapter 7.1 patent gazette]|

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2019-12-03| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2020-02-11| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 02/03/2012, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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EP11001744.9A|EP2495037B1|2011-03-02|2011-03-02|High throughput reactor assembly for polymerization of olefins|

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EP11001744.9|2011-03-02|

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PCT/EP2012/000960|WO2012116844A1|2011-03-02|2012-03-02|High throughput reactor assembly for polymerization of olefins|

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