Method for producing olefin polymer and polymerization reactor for producing olefin polymer

Abstract

A method for producing an olefin polymer includes: polymerizing a polymerization gas containing an olefin monomer in an agitated horizontal polymerization reactor; extracting the unreacted gas from the gas phase part of the horizontal polymerization reactor; extracting the olefin polymer powder from the horizontal polymerization reactor; separating the unreacted gas from the extracted olefin polymer powder; generating a gas flow containing the unreacted gas separated from the olefin polymer powder outside the horizontal polymerization reactor; and supplying the gas flow containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor. A supply port for supplying the gas flow containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is located downstream of all extraction ports for extracting the unreacted gas from the gas phase part of the horizontal polymerization reactor.

Description

Method for producing an olefin polymer and polymerization reactor for producing an olefin polymer

[0001] The present invention relates to a method for producing an olefin polymer and a polymerization reactor for producing an olefin polymer.

[0002] In the production process of polyolefins, as the catalyst performance has advanced significantly, the necessity of removing catalyst residues, atactic polymers, etc. has been reduced, and currently the gas-phase process is the mainstream.

[0003] As a gas-phase polymerization reactor used in the gas-phase process of olefins such as propylene and ethylene, a polymerization reactor is known that includes a reaction vessel which is the main body of the polymerization reactor, and a stirrer having a stirring shaft and stirring blades fixed on the stirring shaft, which is disposed in the reaction vessel as a means for homogenizing the reaction system including the raw material monomer and the catalyst.

[0004] When producing an olefin polymer by the gas-phase polymerization method using a horizontal polymerization reactor, generally, the catalyst is supplied to the upper stream region in the reaction vessel. The catalyst is in the form of fine particles, and olefins polymerize on the surface and inside of the catalyst fine particles to form olefin polymer particles. The olefin polymer particles grow as the polymerization progresses and gradually move to the downstream of the reactor, and the grown olefin polymer powder is taken out from the downstream side of the reaction vessel. In a horizontal polymerization reactor, usually, the unreacted gas is discharged from the gas phase part to the outside of the reaction system through an unreacted gas extraction pipe, and is re-supplied to the horizontal polymerization reactor via a condenser, a compressor, a raw material supply pipe, etc. The gas extracted from the horizontal polymerization reactor usually unavoidably contains fine powder of the olefin polymer powder.

[0005] Therefore, it has been disclosed that it is advantageous to substantially remove polymer fine particles by using a trap, filter, settler, cyclone, or scrubber, or a combination thereof, before cooling the unreacted gas in a condenser (Patent Document 1, paragraph 0041). Patent Document 1 also discloses that the reactive gas accompanying the olefin polymer powder removed from the downstream side of the reactor is subjected to the suction action of a gas compressor via a gas / solid separation device and flows through an unreacted gas extraction pipe to a cooler / condenser (Patent Document 1, Figure 1, paragraph 0044). Patent Document 1 does not disclose anything about the handling of the removed polymer fine particles. Patent Document 2 discloses that propylene gas, which is the unreacted gas discharged from a horizontal reactor, is led through an exhaust gas line to a cyclone separator, where accompanying particles (olefin polymer powder fine particles) are removed from the propylene gas, and the separated accompanying particles are returned to the upstream side of the horizontal reactor (Patent Document 2, Figure 5).

[0006] Special table number 2001-525242 Japanese patent publication number 63-223001

[0007] As disclosed in Patent Document 1, when the grown olefin polymer powder is withdrawn from the downstream side of the reaction vessel, unreacted gas inevitably remains in the olefin polymer powder. From the viewpoint of improving production efficiency, it is necessary to separate the unreacted gas and return it to the horizontal polymerization reactor for olefin polymerization. However, the inventors have confirmed that, as disclosed in Patent Document 1, returning the unreacted gas separated from the olefin polymer powder to the unreacted gas extraction pipe tends to cause problems such as blockage of the fine particle separator connected to the unreacted gas extraction pipe and adverse effects on instruments and other equipment connected to the unreacted gas extraction pipe. The inventors have considered that the cause of the above problems is that the unreacted gas separated from the grown olefin polymer powder contains fine particles, and when the unreacted gas is returned to the unreacted gas extraction pipe, the amount of fine particles contained in the unreacted gas extracted from the gas phase increases. When problems such as blockage occur, the polymerization process must be stopped for cleaning, making long-term operation difficult.

[0008] The present invention aims to provide a method for producing an olefin polymer and a polymerization reactor for producing an olefin polymer, in view of the problems encountered when returning unreacted gas separated from the grown olefin polymer powder to a horizontal polymerization reactor, and to provide a method for producing an olefin polymer that can suppress the increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase while returning and circulating the unreacted gas separated from the grown olefin polymer powder to the horizontal polymerization reactor.

[0009] As a result of repeated studies to solve the above problems, the present inventors have found that (i) the unreacted gas separated from the olefin polymer powder withdrawn from the horizontal polymerization reactor contains fine particles; and (ii) when the unreacted gas separated from the olefin polymer powder is returned to the horizontal polymerization reactor and circulated, by placing the supply port for returning the gas stream containing the separated unreacted gas to the horizontal polymerization reactor downstream of all the outlets for withdrawing the unreacted gas from the gas phase of the horizontal polymerization reactor, the increase in the amount of fine particles contained in the unreacted gas withdrawn from the gas phase can be suppressed, and long-term operability can be improved; and thus arrived at the present invention. That is, the present invention includes the following aspects.

[0010] [1] A method for producing an olefin polymer, comprising: polymerizing a polymerization gas containing an olefin monomer in a stirred horizontal polymerization reactor; removing unreacted gas from the gas phase of the horizontal polymerization reactor; removing olefin polymer powder from the horizontal polymerization reactor; separating unreacted gas from the removed olefin polymer powder; generating a gas stream containing the unreacted gas separated from the olefin polymer powder outside the horizontal polymerization reactor; and supplying the gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor, wherein the supply port for supplying the gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is located downstream of all the outlets for removing unreacted gas from the gas phase of the horizontal polymerization reactor. [2] The method for producing an olefin polymer according to [1], wherein the distance between the downstream end of the downstreammost outlet among the outlets for extracting the unreacted gas and the upstream end of the upstreammost outlet among the outlets for supplying a gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is 7.0% or more of the distance from the upstream end to the downstream end of the horizontal polymerization reactor. [3] The method for producing an olefin polymer according to [1] or [2], wherein the distance between the upstream end of the upstreammost outlet among the outlets for supplying a gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor and the downstream end of the downstreammost outlet among the outlets for extracting the olefin polymer powder from the horizontal polymerization reactor is 11.0% or less of the distance from the upstream end to the downstream end of the horizontal polymerization reactor.[4] A polymerization reactor for producing olefin polymers, comprising: a stirred horizontal polymerization reactor for polymerizing a polymerization gas containing olefin monomers; an unreacted gas extraction pipe for extracting unreacted gas from the gas phase of the horizontal polymerization reactor; a polymer extraction pipe for extracting olefin polymer powder from the horizontal polymerization reactor; a gas recovery machine connected to the polymer extraction pipe for separating unreacted gas contained in the olefin polymer powder from the olefin polymer powder; an ejector connected to the gas recovery machine via a gas recovery pipe for generating a gas stream containing the separated unreacted gas; and a gas stream supply pipe connected to the ejector for supplying the gas stream containing the unreacted gas to the horizontal polymerization reactor, wherein in the horizontal polymerization reactor, the supply port of the gas stream supply pipe is located downstream of all the outlets of the unreacted gas extraction pipe. [5] The polymerization reactor for producing olefin polymers according to [4], wherein the distance between the downstream end of the downstreammost outlet of the unreacted gas extraction piping and the upstream end of the upstreammost supply port of the gas flow supply piping is 7.0% or more of the distance from the upstream end to the downstream end of the horizontal polymerization reactor. [6] The polymerization reactor for producing olefin polymers according to [4] or [5], wherein the distance between the upstreammost end of the supply port of the gas flow supply piping and the downstream end of the downstreammost outlet of the polymer extraction piping is 11.0% or less of the distance from the upstream end to the downstream end of the horizontal polymerization reactor.

[0011] The present invention provides a method for producing an olefin polymer and a polymerization reactor for producing an olefin polymer, which can suppress the increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase while returning the unreacted gas separated from the grown olefin polymer powder to a horizontal polymerization reactor and circulating it.

[0012] Figure 1 is a schematic diagram showing an example of a polymerization reactor for producing olefin polymers according to the present invention. Figure 2 is a schematic diagram illustrating an example of a polymerization reactor for producing olefin polymers according to the present invention.

[0013] The features of the present invention will be described in detail below. The description of the constituent elements described below is an example of an embodiment of the present invention, and the present invention is not limited to the following description unless it exceeds the gist of the invention. In this invention, the "~" indicating a numerical range is used to mean that the numerical values ​​described before and after it are included as the lower limit and upper limit.

[0014] The present invention provides a method for producing an olefin polymer, comprising: polymerizing a polymerization gas containing an olefin monomer in a stirred horizontal polymerization reactor; removing unreacted gas from the gas phase of the horizontal polymerization reactor; removing olefin polymer powder from the horizontal polymerization reactor; separating unreacted gas from the removed olefin polymer powder; generating a gas stream containing the unreacted gas separated from the olefin polymer powder outside the horizontal polymerization reactor; and supplying the gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor, wherein the supply port for supplying the gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is located downstream of all the outlets for removing unreacted gas from the gas phase of the horizontal polymerization reactor.

[0015] Furthermore, the polymerization reactor for producing olefin polymers according to the present invention includes: a stirred horizontal polymerization reactor for polymerizing a polymerization gas containing olefin monomers; an unreacted gas extraction pipe for extracting unreacted gas from the gas phase of the horizontal polymerization reactor; a polymer extraction pipe for extracting olefin polymer powder from the horizontal polymerization reactor; a gas recovery machine connected to the polymer extraction pipe for separating unreacted gas contained in the olefin polymer powder from the olefin polymer powder; an ejector connected to the gas recovery machine via a gas recovery pipe for generating a gas flow containing the separated unreacted gas; and a gas flow supply pipe connected to the ejector for supplying the gas flow containing the unreacted gas to the horizontal polymerization reactor, wherein in the horizontal polymerization reactor, the supply port of the gas flow supply pipe is located downstream of all the outlets of the unreacted gas extraction pipe.

[0016] In conventional technology, returning unreacted gas separated from the grown olefin polymer powder to the unreacted gas extraction piping can easily cause problems such as blockage of the fine particle separator connected to the unreacted gas extraction piping or adverse effects on instruments and other equipment connected to the unreacted gas extraction piping. This is thought to be because when unreacted gas separated from the grown olefin polymer powder is returned to the unreacted gas extraction piping, fine particles are also mixed into the returned unreacted gas, increasing the amount of fine particles contained in the unreacted gas extracted from the gas phase. In contrast, in the present invention, by installing the supply port for returning the gas stream containing unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor downstream of all the outlets for extracting unreacted gas from the gas phase of the horizontal polymerization reactor, it is thought that fine particles mixed into the returned unreacted gas are less likely to flow into the unreacted gas extraction piping, thereby suppressing the increase in the amount of fine particles contained in the unreacted gas extracted from the gas phase. By suppressing the increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase, the fine powder separator connected to the unreacted gas extraction piping becomes less likely to become clogged, malfunctions of instruments and other equipment connected to the unreacted gas extraction piping can be suppressed, and long-term operability can be improved. Furthermore, in this invention, by not returning the unreacted gas separated from the grown olefin polymer powder to the upstream side of the horizontal polymerization reactor, problems such as the gradual accumulation of fine powder at the sliding interface between the stirring shaft and the inner surface of the bearing at the upstream end of the reactor, which causes deterioration of stirring performance due to increased friction load, can also be suppressed. According to this invention, by returning the unreacted gas separated from the grown olefin polymer powder and the fine powder mixed in the unreacted gas to the horizontal polymerization reactor and circulating it, production efficiency can be improved, and equipment in subsequent processes can be prevented from being worn, clogged, or damaged by the fine powder contained in the olefin polymer powder.

[0017] In this invention, "fine powder" refers to polymer powder that passes through a sieve with a mesh size of 210 μm when the olefin polymer powder is passed through the sieve. The grown olefin polymer powder has an average particle size of approximately 500 μm to 1300 μm. The average particle size here is determined by sieving the powder using sieves with different mesh sizes and calculating the mass of the powder remaining on each sieve.

[0018] The olefin polymers produced using the stirred horizontal polymerization reactor of the present invention include olefin homopolymers and olefin copolymers containing two or more olefin polymerization units. The olefin monomer used to produce the olefin polymer is not particularly limited, but α-olefin monomers having 2 to 20 carbon atoms are preferably used. Specific examples of α-olefin monomers having 2 to 20 carbon atoms include ethylene, propylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 1-nonene, 1-octene, 1-heptene, 1-hexene, 1-decene, 1-undecene, and 1-dodecene. From the viewpoint of suitably applying the present invention, the olefin monomer may be an olefin containing propylene. The method for producing the olefin polymer of the present invention may involve the homopolymerization of propylene, or copolymerization of propylene with one or more α-olefin monomers having 2 to 20 carbon atoms, different from propylene.

[0019] The present invention involves polymerizing a polymerization gas containing olefin monomers, and employs a gas-phase polymerization method. The polymerization gas is the gas of olefin monomers, which are the raw materials for olefin polymers, but hydrogen may also be included as a gas involved in polymerization. Gas-phase polymerization is a polymerization process in which polymerization is carried out in the gas phase in substantially the absence of a liquid phase. It is sufficient that the phase in which polymerization is carried out is substantially the gas phase, and a liquid may be present to the extent that it does not depart from the gist of the present invention. Examples of this liquid include a liquid containing liquefied monomers for heat removal, and inert hydrocarbons such as hexane used as a solvent when supplying the catalyst. Reactions in the liquid phase in which a catalyst diluted in a solvent is supplied and then reacts with the liquefied monomer dissolved in the solvent are also included in the gas-phase polymerization of the present invention.

[0020] In the present invention, a polymerization gas containing an olefin monomer may be polymerized in the presence of a catalyst. The catalyst is not particularly limited as long as it can be used for polymerization of olefin monomers, and for example, Ziegler catalysts and metallocene catalysts can be used. Other components such as co-catalysts, such as organoaluminum compounds, may be supplied separately from the catalyst from the co-catalyst supply port, or they may be supplied from the catalyst supply port as components of the catalyst after being in contact with Ziegler-type solid catalyst components or metallocene complex components. Furthermore, the catalyst may be supplied to the reaction vessel as a powder, or it may be supplied after being diluted with an inert solvent such as a liquid saturated hydrocarbon or mineral oil.

[0021] The polymerization conditions, such as temperature and pressure, for the gas-phase polymerization method using the polymerization gas containing the olefin monomer of the present invention are not particularly limited and can be arbitrarily set according to the raw material monomer. For example, when the raw material monomer is propylene, the reaction temperature, polymerization pressure, and residence time in the reaction vessel are as follows: The reaction temperature has a lower limit of preferably 0°C or higher, more preferably 30°C or higher, and particularly preferably 40°C or higher, and an upper limit of preferably 100°C or lower, more preferably 90°C or lower, and particularly preferably 80°C or lower. The polymerization pressure has a lower limit of atmospheric pressure or higher, preferably 600 kPaG or higher, more preferably 1000 kPaG or higher, and particularly preferably 1600 kPaG or higher, and an upper limit of preferably 4200 kPaG or lower, more preferably 3500 kPaG or lower, and particularly preferably 3000 kPaG or lower. The residence time in the reaction vessel is arbitrarily adjusted according to the reactor configuration and product index, but is generally set within the range of 30 minutes to 10 hours. The stirring speed of the agitator is adjusted as needed according to the reactor configuration, size, product index, etc., but generally it is set to 10 mins per minute. －１ ~50 min －１ It is set within the range.

[0022] The polymerization reactor for producing olefin polymers and the method for producing olefin polymers according to the present invention will be further described below with reference to the drawings. Figure 1 is a schematic diagram showing an example of the polymerization reactor 100 for producing olefin polymers according to the present invention. The reactor body, a stirred horizontal polymerization reactor 1, is shown as a schematic cross-sectional view. The horizontal polymerization reactor 1 is long and narrow, equipped with partition walls 1a and 1b, and is generally installed in a horizontal position as shown in Figure 1. The polymerization reaction, in which a polymerization gas containing olefin monomers is polymerized, takes place in the space between partition walls 1a and 1b inside the stirred horizontal polymerization reactor 1. In Figure 1, the partition wall 1a on the upstream side of the reactor is the upstream end 3 of the reactor, and the partition wall 1b on the downstream side of the reactor is the downstream end 4 of the reactor. Although not shown, if the partition walls have a curved shape, the vertices of each curved surface become the upstream end and downstream end of the reactor.

[0023] The stirred horizontal polymerization reactor 1 is equipped with a stirrer 2. The stirring shaft 2a of the stirrer 2 is positioned to penetrate the partition walls 1a and 1b of the horizontal polymerization reactor 1, and multiple stirring blades 2b for stirring are attached inside the horizontal polymerization reactor 1. The stirring blades 2b mix the polymer particles with other substances introduced into the horizontal polymerization reactor 1. One end of the stirring shaft 2a is supported so as to be able to rotate around the axis by being inserted into a bearing, and the other end of the stirring shaft 2a is connected to a drive device such as a motor by penetrating the outer wall of the reactor.

[0024] The stirring blade 2b is a component that applies stirring force to the reaction materials within the reactor. The shape of the stirring blade 2b is not particularly restricted and may be, for example, blade-shaped, screw-shaped, etc. Other settings of the stirring blade, such as dimensions (length, width, thickness), position on the stirring shaft, azimuth angle around the stirring shaft, and inclination angle with respect to the direction of rotation, are also not particularly restricted and can be set appropriately considering the stirring force, material conveying force in the flow direction, etc. Typically, the stirrer 2 is positioned so that the stirring shaft 2a of the stirrer 2 overlaps with the longitudinal central axis of the internal space of the reactor body. By rotating the stirring blade of the stirrer within the polymerization reaction space, polymerization can be carried out efficiently and uniformly while stirring the starting materials and reaction products. The stirrer can move the polymer particles downstream of the horizontal polymerization reactor while growing the polymer particles.

[0025] The polymerization reaction may be carried out in the presence of a catalyst, and the horizontal polymerization reactor may be equipped with catalyst component supply piping. A catalyst component supply port may be provided at the upper and upstream side in the direction of gravity of the horizontal polymerization reactor 1, and the catalyst component supply port is connected to catalyst component supply pipes 5 and 6 (one pipe may be used if necessary). The catalyst component introduced from the catalyst component supply pipes 5 and 6 is mixed with polymer particles by the stirring blades 2b, and polymerization begins. The catalyst component supply pipes 5 and 6 can be installed at any position as long as they do not deviate from the spirit of the present invention. In a stirred horizontal polymerization reactor, when the catalyst is supplied to the upstream side of the reactor, polymer particles can efficiently move downstream of the horizontal polymerization reactor while growing due to the polymerization of the polymerization gas.

[0026] Furthermore, multiple liquefied monomer-containing liquid supply ports may be provided at appropriate intervals above the horizontal polymerization reactor 1 in the direction of gravity and downstream of the catalyst component supply port. Each liquefied monomer-containing liquid supply port is connected to the liquefied monomer-containing liquid supply pipe 7. The heat of polymerization generated during polymerization may be removed by the heat of vaporization of the liquefied monomer-containing liquid containing liquefied propylene, a raw material, supplied from the liquefied monomer-containing liquid supply pipe 7. The liquefied monomer-containing liquid introduced from the liquefied monomer-containing liquid supply pipe 7 into the horizontal polymerization reactor 1 vaporizes to become a polymerization gas, which is then polymerized while being mixed with polymer particles by the stirring blades 2b.

[0027] On the other hand, multiple raw material monomer gas supply ports may be provided at appropriate intervals in the lower part of the horizontal polymerization reactor 1 in the direction of gravity and in the region opposite to the liquid supply port for the liquefied monomer-containing liquid. Each raw material monomer gas supply port is connected to the raw material mixed gas supply pipe 8.

[0028] The horizontal polymerization reactor 1 used in the present invention is equipped with an unreacted gas extraction pipe 9 for extracting unreacted polymerization gas (referred to as "unreacted gas" in the present invention) from the gas phase of the horizontal polymerization reactor. Multiple outlets (9-1, 9-2) for the unreacted gas extraction pipes may be provided at appropriate intervals above the horizontal polymerization reactor 1 in the direction of gravity and downstream of the catalyst component supply port. Each outlet (9-1, 9-2) of the unreacted gas extraction pipe is connected to the unreacted gas extraction pipe 9. In Figure 1, two outlets (9-1, 9-2) for the unreacted gas extraction pipes are shown, but the number of outlets for the unreacted gas extraction pipes may be one or three or more.

[0029] The unreacted gas extracted from the gas phase inevitably contains fine particles. Therefore, the polymerization reactor for producing olefin polymers according to the present invention may include a fine particle separator 10 connected to the unreacted gas extraction pipe 9 for separating the fine particles contained in the unreacted gas. Examples of the fine particle separator 10 include cyclone separators and bag filters. The fine particle separator 10 may be a cyclone separator because it is possible to return the recovered fine particles to the horizontal polymerization reactor, and it has high separation capacity and a large processing capacity. Furthermore, the method for producing olefin polymers according to the present invention may include separating fine particles from the unreacted gas extracted from the gas phase. The unreacted gas extracted from the gas phase may have its fine particles separated by the fine particle separator before a portion of it is condensed in the condenser described later.

[0030] The polymerization reactor for producing olefin polymers according to the present invention may include a condenser 11 connected to an unreacted gas extraction pipe 9, and a gas-liquid separation tank 12 connected to the condenser 11. In the method for producing olefin polymers according to the present invention, the unreacted gas extracted from the gas phase of the horizontal polymerization reactor may be partially condensed in the condenser 11 and separated into a liquid phase and a gas phase in the gas-liquid separation tank 12.

[0031] The polymerization reactor for producing olefin polymers according to the present invention may include a raw material monomer supply pipe 13 connected to a gas-liquid separation tank 12. The liquid phase of the gas-liquid separation tank 12 may be connected to a liquefied monomer-containing liquid supply pipe 7. A pump 16 may be provided between the liquid phase of the gas-liquid separation tank 12 and the liquefied monomer-containing liquid supply pipe 7. The gas phase of the gas-liquid separation tank 12 may be connected to a raw material mixed gas supply pipe 8. A compressor 15 may be provided between the gas phase of the gas-liquid separation tank 12 and the raw material mixed gas supply pipe 8. A raw material supply pipe 14 may be connected to the raw material mixed gas supply pipe 8.

[0032] The raw material monomer may be supplied to the gas-liquid separation tank 12 via the raw material monomer supply pipe 13. Other raw materials (such as comonomers and hydrogen) may be supplied to the reaction system via the raw material supply pipe 14 if they are gases, or via the raw material monomer supply pipe 13 if they are liquids. The liquid phase of the gas-liquid separation tank 12 may be resupplied to the horizontal polymerization reactor 1 via the liquefied monomer-containing liquid supply pipe 7 by the driving force of the pump 16 in order to remove the heat of polymerization. Thus, the method for producing olefin polymers of the present invention may include removing the heat of polymerization by the heat of vaporization of the liquefied monomer. On the other hand, the gas phase of the gas-liquid separation tank 12 may be mixed with hydrogen or α-olefin for molecular weight adjustment from the raw material supply pipe 14, pressurized by the compressor 15, and resupplied to the horizontal polymerization reactor 1 via the raw material mixed gas supply pipe 8 installed at the bottom of the horizontal polymerization reactor 1 in the direction of gravity.

[0033] The polymerization reactor for producing olefin polymers according to the present invention includes a polymer extraction pipe 17 for extracting olefin polymer powder from the horizontal polymerization reactor, a gas recovery machine 18 connected to the polymer extraction pipe 17 for separating unreacted gas contained in the olefin polymer powder from the olefin polymer powder, an ejector 20 connected to the gas recovery machine 18 via a gas recovery pipe 19 for generating a gas flow containing the separated unreacted gas, and a gas flow supply pipe 21 connected to the ejector 20 for supplying the gas flow containing the unreacted gas to the horizontal polymerization reactor, wherein in the horizontal polymerization reactor 1, the supply port (21-1) of the gas flow supply pipe 21 is located downstream of all the outlets (9-1, 9-2) of the unreacted gas extraction pipe. The polymerization reactor for producing olefin polymers according to the present invention may further include an olefin polymer powder recovery machine 23 connected to the gas recovery machine 18.

[0034] The present invention provides a method for producing an olefin polymer, which includes withdrawing the olefin polymer powder from the horizontal polymerization reactor. The polymer particles are mixed and react as they move from the upstream to the downstream end of the horizontal polymerization reactor, generating olefin polymer powder. The olefin polymer powder is then withdrawn from the reaction system using the polymer withdrawal pipe 17. In the present invention's method for producing an olefin polymer, the olefin polymer powder may be withdrawn from the polymer powder bed formed in the horizontal polymerization reactor.

[0035] In the polymerization reactor for producing olefin polymers of the present invention, the polymer extraction pipe 17 may be provided to extract olefin polymer powder from the polymer powder bed formed in the lower part of the gravity direction downstream of the horizontal polymerization reactor to the outside of the reaction system. An extraction port (17-1) for extracting olefin polymer powder may be provided in the lower part of the horizontal polymerization reactor in the gravity direction and near the downstream end of the reaction. There may be two or more extraction ports of the polymer extraction pipe 17, but all of them shall be connected to a gas recovery unit 18. If there are two or more extraction ports of the polymer extraction pipe 17, two or more gas recovery units may be used. Each of the two or more extraction ports may be connected to a different gas recovery unit.

[0036] The present invention relates to a method for producing an olefin polymer, which includes separating unreacted gas from the extracted olefin polymer powder. As described above, the extracted olefin polymer powder inevitably contains unreacted gas, but it is necessary to separate the unreacted gas from the extracted olefin polymer powder. The extracted olefin polymer powder is separated from the unreacted gas, for example, using a gas recovery machine.

[0037] In the gas recovery machine 18 connected to the polymer extraction pipe 17, which separates unreacted gas contained in the olefin polymer powder from the olefin polymer powder, for example, by blowing up new olefin gas 24 from the bottom, the unreacted gas 22 contained in the olefin polymer powder is blown up to the top, separating the unreacted gas from the olefin polymer powder. The unreacted gas separated from the olefin polymer powder may contain fine particles. The unreacted gas separated from the olefin polymer powder, together with the new olefin gas 24 blown up by the gas recovery machine, is introduced into the gas recovery pipe 19 connected to the gas recovery machine. On the other hand, the olefin polymer powder from which the unreacted gas has been removed may be taken out of the gas recovery machine 18 and recovered into the olefin polymer powder recovery machine 23.

[0038] The present invention provides a method for producing an olefin polymer, which includes generating a gas stream containing unreacted gas separated from the olefin polymer powder outside the horizontal polymerization reactor. The unreacted gas separated from the olefin polymer powder is recovered by joining with new olefin gas blown up by a gas recovery unit. In order to return the recovered gas to the horizontal polymerization reactor, a gas stream containing the unreacted gas separated from the olefin polymer powder is generated outside the horizontal polymerization reactor. Specifically, an ejector may be used to generate the gas stream.

[0039] The ejector 20, connected to the gas recovery machine 18 via a gas recovery pipe 19, generates a gas flow containing unreacted gas separated from the olefin polymer powder introduced into the gas recovery pipe 19. The ejector 20 generates a gas flow containing unreacted gas separated from the olefin polymer powder by a mechanism that draws in the recovered gas (a mixture of unreacted gas and new olefin gas) in the gas recovery pipe 19 through the Venturi effect, for example, by flowing a high-pressure drive gas 25 through a constricted portion in the center of the ejector 20. The ejector is not particularly limited as long as it can generate a gas flow containing unreacted gas separated from the olefin polymer powder, and conventionally known structures can be appropriately selected and used. The ejector may consist of an intake port for the substance to be aspirated, a discharge conduit, and a drive gas nozzle.

[0040] The pressure difference between the outlet pressure of the gas recovery unit 18 and the pressure of the drive gas flow in the ejector can be appropriately selected to generate a gas flow containing unreacted gas separated from the olefin polymer powder. The pressure difference may be, for example, 0.1 MPaG to 0.2 MPaG. The flow velocity of the generated gas flow containing unreacted gas separated from the olefin polymer powder can be appropriately selected to sufficiently recover the unreacted gas introduced into the gas recovery unit. The flow velocity of the gas flow may be, for example, 8 m / s to 10 m / s. The high-pressure drive gas used in the ejector may be gas that has been compressed to high pressure using a compressor after being extracted from the gas phase section.

[0041] The present invention provides a method for producing an olefin polymer, which includes supplying a gas stream containing unreacted gas separated from the olefin polymer powder to a horizontal polymerization reactor. The supply port for supplying the gas stream containing unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is set to be located downstream of all the outlets for removing unreacted gas from the gas phase of the horizontal polymerization reactor.

[0042] The horizontal polymerization reactor 1 includes a gas flow supply pipe 21 connected to the ejector 20, which supplies a gas flow containing the unreacted gas to the horizontal polymerization reactor. In the horizontal polymerization reactor 1, the supply port (21-1) of the gas flow supply pipe 21 is positioned downstream of all the outlets (9-1, 9-2) of the unreacted gas extraction pipe. By positioning the supply port (21-1) of the gas flow supply pipe 21 in this manner, it is possible to suppress the entry of fine powder mixed with the unreacted gas returned by the gas flow into the unreacted gas extraction pipe, thereby suppressing an increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase. Furthermore, even if fine powder is mixed in with the unreacted gas, the fine powder can be effectively utilized to grow into olefin polymer powder. The supply port of the gas flow supply pipe 21 may be located at the top in the direction of gravity in the horizontal polymerization reactor 1, in order to prevent blockage of the gas flow supply pipe even when gas is supplied intermittently, and to promote the growth of fine powder. The supply port of the gas flow supply pipe 21 may be one or more. Even if there are multiple supply ports of the gas flow supply pipe 21, the supply ports of the gas flow supply pipe 21 should be installed downstream of all the outlets of the unreacted gas extraction pipe.

[0043] The arrangement of the supply port of the gas flow supply pipe 21 and all the extraction ports of the unreacted gas extraction pipe 9 in the horizontal polymerization reactor 1 will be described in detail with reference to FIG. 2. From the viewpoint of easily suppressing an increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase portion, the most downstream end 30 of the extraction port (9-2) which is the most downstream among the extraction ports (9-1, 9-2) of the unreacted gas extraction pipe 9, and the most upstream end 31 of the supply port (21-1) which is the most upstream among the supply ports of the gas flow supply pipe 21, the distance (d1) therebetween may be 7.0% or more, may be 7.3% or more, and may be 7.6% or more with respect to the distance (L) from the upstream end to the downstream end of the horizontal polymerization reactor. The upper limit value of d1 with respect to L is not particularly limited. From the viewpoints of suppressing the bias of unreacted gas extraction, suppressing an increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase portion, and promoting the growth of fine powder, it may be 10.0% or less. Here, the most downstream end 30 of the extraction port (9-2) is the most downstream end of the opening of the extraction port in the horizontal polymerization reactor, and the most upstream end 31 of the supply port (21-1) is the most upstream end of the opening of the supply port in the horizontal polymerization reactor. Further, the distance from the upstream end 3 to the downstream end 4 of the horizontal polymerization reactor means the length of a straight line connecting the intersection 34 of the wall surface of the upstream partition wall 1a facing the polymerization reaction space side and the longitudinal central axis 33 of the polymerization reaction space and the intersection 35 of the wall surface of the downstream partition wall 1b facing the polymerization reaction space side and the longitudinal central axis 33 of the polymerization reaction space. The distance (L) from the upstream end to the downstream end of the horizontal polymerization reactor corresponds to the length of the space where the polymerization reaction is carried out. Note that the calculated value of d1 with respect to L is rounded off to the fourth decimal place and expressed as a percentage value.

[0044] The distance (d1) between the most downstream end 30 of the extraction port (9-2) which is the most downstream among the extraction ports (9-1, 9-2) of the unreacted gas extraction pipe 9 and the most upstream end 31 of the supply port (21-1) which is the most upstream among the supply ports of the gas flow supply pipe 21 may be adjusted as appropriate, but from the viewpoint of easily suppressing an increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase portion, it may be 1000 mm or more. The upper limit value of this value is not particularly limited, but may be 5000 mm or less.

[0045] From the viewpoint of being easily able to suppress an increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase portion, the distance (d2) between the most upstream end 31 of the supply port (21-1) that is the most upstream among the supply ports of the gas flow supply pipe 21 and the most downstream end 32 of the extraction port (17-1) that is the most downstream among the extraction ports of the polymer extraction pipe 17 may be 11.0% or less, and may be 10.8% or less, with respect to the distance (L) from the upstream end to the downstream end of the horizontal polymerization reactor. The lower limit value of d2 with respect to L is not particularly limited. This is because unreacted gas and fine powder will both grow into polymer powder if circulated within the polymerization reaction system. From the viewpoint of promoting the growth of fine powder, the supply port of the gas flow supply pipe 21 may be installed upstream of the extraction port of the polymer extraction pipe 17. Even when there are a plurality of supply ports of the gas flow supply pipe 21, all of the supply ports of the plurality of gas flow supply pipes 21 may be installed upstream of the extraction port of the polymer extraction pipe 17. From the viewpoint of promoting the growth of fine powder, the distance (d2) between the most upstream end 31 of the supply port (21-1) that is the most upstream among the supply ports of the gas flow supply pipe 21 and the most downstream end 32 of the extraction port (17-1) that is the most downstream among the extraction ports of the polymer extraction pipe 17 may be 5.0% or more with respect to the distance (L) from the upstream end to the downstream end of the horizontal polymerization reactor. Note that the most downstream end 32 of the extraction port (17-1) is the most downstream end of the opening of the extraction port in the horizontal polymerization reactor. Note that the calculated value of d2 with respect to L is rounded off at the fourth decimal place and expressed as a percentage value.

[0046] The distance between the most upstream end of the supply port that is the most upstream among the supply ports for supplying the gas flow containing fine powder separated from the olefin polymer powder to the horizontal polymerization reactor and the most downstream end of the extraction port that is the most downstream among the extraction ports for extracting the olefin polymer powder from the horizontal polymerization reactor may be adjusted as appropriate, but may be 5000 mm or less. Also, from the viewpoint of promoting the growth of fine powder, this lower limit value may be 500 mm or more.

[0047] In the method for producing an olefin polymer of the present invention, the arrangement of the supply port for supplying a gas stream containing unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor, the outlet for removing unreacted gas from the gas phase of the horizontal polymerization reactor, and the outlet for removing the olefin polymer powder from the horizontal polymerization reactor may be the same as the arrangement of the supply port of the gas stream supply pipe 21, the outlet of the unreacted gas removal pipe 9, and the outlet of the polymer removal pipe described in the polymerization reactor for producing an olefin polymer of the present invention.

[0048] The polymerization reactor for producing olefin polymers according to the present invention may further include a mechanism for returning the fine powder recovered by a fine powder separator 10, which is connected to the unreacted gas extraction pipe 9 and separates the fine powder contained in the unreacted gas, back to the horizontal polymerization reactor 1. The polymerization reactor for producing olefin polymers according to the present invention includes an ejector that generates a gas stream containing the separated fine powder, connected to the fine powder separator 10 via a fine powder recovery pipe, and a fine powder gas stream supply pipe connected to the ejector that supplies the gas stream containing the fine powder to the horizontal polymerization reactor. In the horizontal polymerization reactor, the supply port of the fine powder gas stream supply pipe may be installed downstream of all the outlets of the unreacted gas extraction pipe. By also arranging the supply port of the fine powder gas stream supply pipe downstream of all the outlets of the unreacted gas extraction pipe, it becomes easier to suppress the increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase. Furthermore, the supply port of the fine powder gas stream supply pipe may be installed upstream of the outlet of the polymer extraction pipe 17. The supply port of the fine powder gas flow supply piping may be provided separately from the supply port of the gas flow supply piping 21. Alternatively, the fine powder gas flow supply piping may be merged with the gas flow supply piping connected to the gas recovery machine connected to the polymer extraction piping. In this case, the supply port of the fine powder gas flow supply piping may be the same as the supply port of the gas flow supply piping 21.

[0049] The polymerization reactor for producing olefin polymers according to the present invention may be equipped with sensors such as thermometers and pressure gauges to monitor the state of the reactor body, and other equipment as needed, in the horizontal polymerization reactor. In addition, a separation chamber having a diameter larger than the diameter of the gas discharge pipe may be provided at the connection port (extract port) between the unreacted gas extraction pipe and the reactor to reduce the amount of fine powder entering the unreacted gas extraction pipe.

[0050] The polymerization reactor for producing olefin polymers of the present invention may be applied to continuous polymerization in which raw material monomers are continuously supplied into a reaction vessel and the polymer produced is extracted while the polymerization reaction proceeds. When performing multi-stage polymerization using the polymerization reactor for producing olefin polymers of the present invention, two or more stirred horizontal polymerization reactors may be connected to perform multi-stage polymerization, or the stirred horizontal polymerization reactor used in the present invention may be connected to other polymerization reactors.

[0051] The present disclosure will be described in more detail below using examples, but the present invention is not limited to these examples. In these examples, propylene polymerization was carried out continuously over a long period of time using a horizontal polymerization reactor that produces propylene polymers by gas-phase polymerization.

[0052] 1. Example 1 A polymerization reactor for producing olefin polymers, schematically shown in Figure 1, was used, and continuous polymerization was carried out over a long period of time under the following polymerization conditions. (1) Configuration of the stirred horizontal polymerization reactor A horizontal gas-phase polymerization reactor was used, which had a container body with a distance (L) of 15210 mm from the upstream end to the downstream end of the horizontal polymerization reactor and an inner diameter of 2900 mm of the reactor body, and a stirrer equipped with a stirring shaft to which stirring blades were attached. The rotation speed of the stirring shaft was 16 min －１(2) As shown in diagram 1 of the arrangement of the supply port of the gas flow supply piping, the outlet of the unreacted gas extraction piping, and the outlet of the polymer extraction piping, the supply port (21-1) of the gas flow supply piping 21 was located downstream of all the outlets (9-1, 9-2) of the unreacted gas extraction piping 9, and upstream of the outlet (17-1) of the polymer extraction piping 17. The distance (d1) between the downstream end 30 of the downstream outlet (9-2) of the unreacted gas extraction piping 9 and the upstream end 31 of the upstream supply port (21-1) of the gas flow supply piping 21 was 1160 mm, which was 7.6% of the distance (L) of the horizontal polymerization reactor from the upstream end to the downstream end, which was 15210 mm. Furthermore, the distance (d2) between the upstream end 31 of the upstream supply port (21-1) of the gas flow supply piping 21 and the downstream end 32 of the downstream outlet (17-1) of the polymer extraction piping 17 was 1640 mm, which was 10.8% of the distance (L) of 15210 mm from the upstream end to the downstream end of the horizontal polymerization reactor. (3) Gas flow velocity The gas flow containing unreacted gas separated from the olefin polymer powder was supplied to the horizontal polymerization reactor under control to a flow velocity of 8 m / s to 10 m / s. (4) Polymerization conditions Polymerization temperature 60°C to 70°C Polymerization pressure 2.2 MPaG to 2.5 MPaG Propylene homo-gas phase polymerization and propylene ethylene random gas phase polymerization (5) Cumulative operating time Cumulative operating time: 2 years

[0053] (6) Test results: Even after two years of cumulative operating time, no blockage occurred in the fine particle separator connected to the unreacted gas extraction piping, demonstrating long-term operation. Traces of fine particle flow were observed in parts of the gas flow supply piping.

[0054] 2. Comparative Example 1 In Figure 1, a polymerization reactor for producing olefin polymers was used with the same configuration as in Example 1, except that the gas flow supply pipe 21 was connected before the fine particle separator 10 of the unreacted gas extraction pipe 9. Continuous polymerization was carried out over a long period of time under the same polymerization conditions as in Example 1. As a result, after 12 months of cumulative operation, a blockage occurred in the fine particle separator connected to the unreacted gas extraction pipe, and operation was stopped to clean the fine particle separator and other parts that had accumulated. Traces of fine particle flow were observed in part of the gas flow supply pipe.

[0055] 3. Comparative Example 2 In Figure 1, the position of the supply port (21-1) of the gas flow supply pipe 21 was changed to be approximately midpoint between the two outlets (9-1) and (9-2) of the unreacted gas extraction pipe 9. Except for this change, a polymerization reactor for producing olefin polymers with the same configuration as in Example 1 was used, and continuous polymerization was carried out over a long period of time under the same polymerization conditions as in Example 1. As a result, after 18 months of cumulative operation, a blockage occurred in the fine particle separator connected to the unreacted gas extraction pipe, and operation was stopped to clean the fine particle separator and other components that had accumulated. Traces of partial flow of fine particle were observed in the gas flow supply pipe.

[0056] [Discussion of the Examples] In Comparative Example 1, the agitated horizontal polymerization reactor, similar to Patent Document 1 (JP 2001-525242), returned the gas stream containing unreacted gas separated from the olefin polymer powder to the front of the fine particle separator 10 in the unreacted gas extraction pipe 9. As a result, fine particles mixed in with the returned unreacted gas flowed in, increasing the amount of fine particles contained in the unreacted gas extracted from the gas phase, which made it easy for blockage to occur in the fine particle separator connected to the unreacted gas extraction pipe. In the agitated horizontal polymerization reactor of Comparative Example 2, the gas stream containing unreacted gas separated from the olefin polymer powder was returned to approximately the midpoint between the two outlets (9-1) and (9-2) of the unreacted gas extraction pipe 9. As a result, fine particles mixed in with the returned unreacted gas easily flowed into the unreacted gas extraction pipe of outlet (9-2), which is located downstream from the point where the unreacted gas was returned. This increased the amount of fine particles contained in the unreacted gas extracted from the gas phase, and it is thought that blockages were more likely to occur in the fine particle separator connected to the unreacted gas extraction pipe.

[0057] In the stirred horizontal polymerization reactor of Example 1, the supply port for returning the gas stream containing unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is installed downstream of all the outlets for extracting unreacted gas from the gas phase of the horizontal polymerization reactor. This makes it difficult for fine powder mixed in with the returned unreacted gas to flow into the unreacted gas extraction piping, thereby suppressing an increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase, and thus suppressing blockage of the fine powder separator connected to the unreacted gas extraction piping. According to the present invention, by returning the unreacted gas separated from the grown olefin polymer powder to the horizontal polymerization reactor and circulating it, the increase in the amount of fine powder contained in the unreacted gas extracted from the gas phase can be suppressed. This suppresses blockage of the fine powder separator connected to the unreacted gas extraction piping and malfunctions of instruments and other equipment connected to the unreacted gas extraction piping, improving long-term operability and productivity, and demonstrating industrial usefulness.

[0058] 100 Polymerization reactor 1 Reaction vessel 1a, 1b Partition 2 Stirrer 2a Stirring shaft 2b Stirring blade 3 Upstream end of reactor 4 Downstream end of reactor 5 Catalyst component supply piping 6 Catalyst component supply piping 7 Liquefied monomer-containing liquid supply piping 8 Raw material mixed gas supply piping 9 Unreacted gas extraction piping 9-1, 9-2 Outlet of unreacted gas extraction piping 10 Fine particle separator 11 Condenser 12 Gas-liquid separator 13 Raw material monomer supply piping 14 Raw material supply piping (comonomer, hydrogen, etc.) 15 Compressor 16 Pump 17 Polymer extraction piping 17-1 Outlet of polymer extraction piping 18 Gas recovery machine 19 Gas recovery piping 20 Ejector 21 Gas flow supply piping 21-1 Supply port of gas flow supply piping 22 Unreacted gas contained in olefin polymer powder 23 Olefin polymer powder recovery machine 24 New olefin gas 25 Driving gas 30 The downstream end of the downstream outlet of the unreacted gas extraction piping 31 The upstream end of the upstream supply port of the gas flow supply piping 32 The downstream end of the downstream outlet of the polymer extraction piping 33 The longitudinal central axis of the polymerization reaction space 34 The intersection of the wall surface of the upstream partition facing the polymerization reaction space and the longitudinal central axis of the polymerization reaction space 35 The intersection of the wall surface of the downstream partition facing the polymerization reaction space and the longitudinal central axis of the polymerization reaction space

Claims

1. A method for producing an olefin polymer, comprising: polymerizing a polymerization gas containing an olefin monomer in a stirred horizontal polymerization reactor; removing unreacted gas from the gas phase of the horizontal polymerization reactor; removing olefin polymer powder from the horizontal polymerization reactor; separating unreacted gas from the removed olefin polymer powder; generating a gas stream containing the unreacted gas separated from the olefin polymer powder outside the horizontal polymerization reactor; and supplying the gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor, wherein the supply port for supplying the gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is located downstream of all the outlets for removing unreacted gas from the gas phase of the horizontal polymerization reactor.

2. The method for producing an olefin polymer according to claim 1, wherein the distance between the downstream end of the downstream outlet for removing the unreacted gas and the upstream end of the upstream supply port for supplying a gas stream containing the unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor is 7.0% or more of the distance from the upstream end to the downstream end of the horizontal polymerization reactor.

3. The method for producing an olefin polymer according to claim 1 or 2, wherein the distance between the upstream end of the supply port on the uppermost side of the supply port for supplying a gas stream containing unreacted gas separated from the olefin polymer powder to the horizontal polymerization reactor and the downstream end of the extraction port on the lowermost side of the extraction port for extracting the olefin polymer powder from the horizontal polymerization reactor is 11.0% or less of the distance from the upstream end to the downstream end of the horizontal polymerization reactor.

4. A polymerization reactor for producing olefin polymers, comprising: a stirred horizontal polymerization reactor for polymerizing a polymerization gas containing olefin monomers; an unreacted gas extraction pipe for extracting unreacted gas from the gas phase of the horizontal polymerization reactor; a polymer extraction pipe for extracting olefin polymer powder from the horizontal polymerization reactor; a gas recovery machine connected to the polymer extraction pipe for separating unreacted gas contained in the olefin polymer powder from the olefin polymer powder; an ejector connected to the gas recovery machine via a gas recovery pipe for generating a gas stream containing the separated unreacted gas; and a gas stream supply pipe connected to the ejector for supplying the gas stream containing the unreacted gas to the horizontal polymerization reactor, wherein in the horizontal polymerization reactor, the supply port of the gas stream supply pipe is located downstream of all the outlets of the unreacted gas extraction pipe.

5. The polymerization reactor for producing olefin polymers according to claim 4, wherein the distance between the downstream end of the downstream outlet of the unreacted gas extraction piping and the upstream end of the upstream supply port of the gas flow supply piping is 7.0% or more of the distance from the upstream end to the downstream end of the horizontal polymerization reactor.

6. The polymerization reactor for producing olefin polymers according to claim 4 or 5, wherein the distance between the upstream end of the supply port on the upstream side of the gas flow supply piping and the downstream end of the extraction port on the downstream side of the polymer extraction piping is 11.0% or less of the distance from the upstream end to the downstream end of the horizontal polymerization reactor.

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