RU2574700C1 - Circulating reactor with improved monitoring of flow division - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: circulating reactor includes a first release hole for polymer suspension unloading from the circulating reactor, and a second release hole for polymer suspension unloading from the circulating reactor. The first release hole is located such that the unloaded polymer suspension has polymer concentration equal or higher than average polymer concentration in the circulating reactor. The second release hole is located such that the unloaded polymer suspension has polymer concentration below the average polymer concentration in the circulating reactor. The method includes stages of olefinic monomers, catalytic system and optionally olefine comonomers to the circulating reactor, and monitoring of totals content of the polymer and/or total quantity of the polymer suspension unloaded from the circulating reactor, adjustment of ratio of the polymer suspension unloaded through the first release hole, and the polymer suspension unloaded through the second release hole. Besides the method of monitoring of average holding time of the olefinic polymer, and the second release hole use for monitoring is described.

EFFECT: regulation of polymers concentration in the polymer suspension at the initial phase of the polymerisation process, and during further polymerisation reaction, and effective monitoring of holding time of the olefinic polymer in the circulating reactor.

15 cl, 1 tbl, 3 ex

Description

The present invention relates to a new method for producing an olefin polymer in a loop reactor and / or in a reactor system including a loop reactor, and to a new reactor system including a loop reactor.

The circulation reactor was developed in the 1950s and is now widely used to produce polypropylene and other olefin polymers. In a loop reactor, olefins, such as ethylene and / or propylene, are polymerized in the presence of a hydrocarbon solvent in the suspension phase at elevated pressure and temperature. Then, the polymer suspension is removed from the circulation reactor and, in the case of a cascade polymerization process, is fed to the next reaction vessel, such as a gas phase reactor. Several approaches have been proposed in the art for continuously discharging a polymer slurry from such a loop reactor. In this context, it is well known that the location of the outlet of the circulation reactor is critical for the amount of polymer found in the discharged suspension. For example, EP 1415999 A1 describes a process where the suspension is continuously discharged from a loop reactor and then concentrated in a hydrocyclone. The solvent is recycled to the loop reactor. EP 891990 A2 also describes the continuous discharge of a slurry from a circulation reactor, where the slurry is discharged at a site where the solids concentration is higher than the average solids concentration in the reactor.

However, in many cases, it is preferable to position said outlet so that the discharge suspension has a higher polymer concentration than the average polymer concentration in the suspension in the reactor, it should be noted that such discharge of the polymer may be disadvantageous in some cases. For example, unloading a suspension with a higher concentration of solids than in the suspension in the reactor in the initial phase requires considerable labor and time to increase the polymer concentration in the suspension reactor to a certain level during the initial phase. Additionally, in the case where the loop reactor is part of the cascade reactor, catalyst productivity in the loop reactor may suffer if the olefin polymer holding time is insufficient. In addition, if necessary, precise control of separation in the reactor is conveniently achieved when the polymer concentration in the suspension in the circulation reactor is maintained at a constant level.

Based on the foregoing, one skilled in the art to which the present invention relates will understand that there continues to be a need for an improved olefin polymerization process. In essence, it is desirable to provide simple and effective control of the polymer content in the polymer suspension in the initial phase of the polymerization process and in the subsequent polymerization reaction, and to effectively control the exposure time of the olefin polymer in the circulation reactor.

The finding of the present invention is that the circulation reactor should include a combination of two outlets, i.e., a first and second outlet, and additionally the first outlet should be positioned so that the dischargeable polymer slurry has a polymer concentration of the same or higher than the average the polymer concentration in the circulation reactor, and the second outlet must be positioned so that the discharge polymer suspension has a polymer concentration and lower than the average polymer concentration in the circulation reactor.

Therefore, the present invention in a first aspect relates to a method for producing an olefin polymer in at least one loop reactor, wherein said loop reactor comprises:

(a) at least one lower horizontal segment and / or at least one lower loop,

(b) at least one upper horizontal segment and / or at least one upper loop, and

(c) at least two vertical segments connected by a working connection,

the specified circulation reactor further includes

(d) a first outlet for discharging the 1st polymer slurry from the loop reactor, said 1st polymer slurry comprising an olefin polymer and a liquid phase; the specified first outlet is located so that the discharged polymer suspension had a polymer concentration equal to or higher than the average polymer concentration in the circulation reactor, and

(e) a second outlet for discharging the 2nd polymer slurry from the loop reactor, said 2nd polymer slurry comprising an olefin polymer and a liquid phase; said 2nd outlet is positioned so that the 2nd dischargeable polymer slurry has a polymer concentration lower than the average polymer concentration in the circulation reactor,

the method includes the steps of:

(i) supplying olefin monomers, a catalyst system, and optionally olefin comonomers to a loop reactor to form a polymer slurry in a loop reactor,

(ii) control

(ii1) the total amount of polymer discharged from the loop reactor,

and / or

(ii2) the total amount of polymer suspension discharged from the loop reactor,

and / or

(ii3) the concentration of the polymer in the total polymer suspension discharged from the loop reactor by adjusting the ratio of the first polymer suspension discharged through the first outlet and the second polymer suspension discharged through the second outlet, and

(iii) optionally transferring the total discharged polymer slurry to a second reactor, i.e., to a gas phase reactor.

The method is essentially possible to implement in a circulation reactor, including:

(a) at least one lower horizontal segment and / or at least one lower loop,

(b) at least one upper horizontal segment and / or at least one upper loop, and

(c) at least two vertical segments connected by a working connection,

the specified circulation reactor further includes a first and second outlet openings suitable for unloading a polymer suspension, where

the first outlet is located on the outer periphery of the lower horizontal segment or lower loop of the circulation reactor, and

the second outlet is located on

(i) the inner periphery of the lower horizontal segment of the circulation reactor or the inner periphery of the lower loop of the circulation reactor,

and / or

(ii) the inner periphery of the upper horizontal segment of the circulation reactor or the inner periphery of the upper loop of the circulation reactor.

Accordingly, in one embodiment, the present invention relates to a method carried out in at least one loop reactor, said loop reactor comprising:

(a) one lower horizontal segment,

(b) two lower loops,

(c) one upper horizontal segment,

(d) two upper loops and

(e) two vertical segments,

connected by a working connection, where

two lower loops connect the lower horizontal segment to two vertical segments and two upper loops connect the upper horizontal segment to two vertical segments,

the specified circulation reactor further includes a first and second outlet openings suitable for unloading a polymer suspension, where

the first outlet is located on the outer periphery of the lower horizontal segment or is located on the outer periphery of one of the two lower loops of the circulation reactor, preferably the first outlet is located on the outer periphery of the lower horizontal segment, and

and the second outlet is located on

(i) the inner periphery of the lower horizontal segment of the circulation reactor or the inner periphery of one of the two lower loops of the circulation reactor, preferably on the inner periphery of one of the two lower loops of the circulation reactor,

and / or

(ii) the inner periphery of the upper horizontal segment of the circulation reactor or the inner periphery of one of the two upper loops of the circulation reactor.

Essentially preferably, the second outlet is located on the inner periphery of one of the two lower loops of the loop reactor.

In another embodiment, the present invention relates to a process carried out in at least one loop reactor, wherein said loop reactor does not have horizontal segments. Accordingly, said circulation reactor, i.e., a circulation reactor without horizontal segments, includes

(a) one bottom loop,

(b) one upper loop and

(c) two vertical segments,

connected by a working connection, where

the lower loop and the upper loop connect two vertical segments,

the specified circulation reactor further includes a first and second outlet openings suitable for unloading a polymer suspension, where

the first outlet is located on the outer periphery of the lower loop of the circulation reactor, and

second outlet located

(i) on the inner periphery of the lower loop of the circulation reactor,

and / or

(ii) the inner periphery of the upper loop of the circulation reactor.

Essentially preferably, the second outlet is located on the inner periphery of the lower loop of the circulation reactor.

Therefore, in a second aspect, the present invention relates to a polymerization reactor system comprising a plurality of reactor vessels for producing olefin polymers, said polymerization reactor system comprising at least one loop reactor and at least one additional reactor, preferably a gas phase reactor, where the specified circulation reactor includes:

(a) at least one lower horizontal segment and / or at least one lower loop,

(b) at least one upper horizontal segment and / or at least one upper loop, and

(c) at least two vertical segments connected by a working connection,

said circulation reactor further includes first and second outlets suitable for discharging the polymer slurry,

said first and second outlet openings are connected to the second reactor by a pipe,

where additionally

the first outlet is located on the outer periphery of the lower horizontal segment or is located on the outer periphery of one of the two lower loops of the circulation reactor, preferably the first outlet is located on the outer periphery of the lower horizontal segment,

and the second outlet is located on

(i) the inner periphery of the lower horizontal segment of the circulation reactor or the inner periphery of one of the two lower loops of the circulation reactor, preferably on the inner periphery of one of the two lower loops of the circulation reactor,

and / or

(ii) the inner periphery of the upper horizontal segment of the circulation reactor or the inner periphery of one of the two upper loops of the circulation reactor.

In preferred embodiments of the present invention, a loop reactor is used in the polymerization reactor system, as described above in the above method of the present invention, which will now be described in more detail.

Unexpectedly, the inventors of the present invention found that such a method and such a reactor polymerization system allow a person skilled in the art to which the present invention relates to, very easily and in a rather short time to adjust the concentration of polymers in the polymer suspension during the initial phase of the polymerization process and the subsequent polymerization effective control of the exposure time of the olefin polymer in the circulation reactor. Therefore, the method of the present invention, along with the polymerization reactor system of the present invention, can increase the overall productivity of the polymerization process in a loop reactor.

It should be understood that the following preferred embodiments of the present invention or the technical details of the circulation reactor of the present invention also relate to the polymerization reactor system of the present invention, to a method for producing olefin polymers of the present invention in a circulation reactor, along with the use of a second outlet in the circulation the reactor of the present invention for the production of olefin polymers and the use of a combination of the first and second final year at holes in a loop reactor of the present invention to control the average holding time of olefin polymer in a loop reactor above and vice versa (so far as possible). If, for example, it is indicated that the average polymer concentration in the circulation reactor of the present invention is from 15 mass. % to 55 mass. %, then accordingly, the average concentration of the polymer obtained using the reactor system for polymerization of the present invention, the method of the present invention and the olefin polymer obtained by this method, along with applications of the present invention is from 15 wt. % to 55 mass. %

Further, the present invention will be described in more detail:

Used in the description of the present patent application, the term "monomer" in contrast to the term "comonomer" indicates that the "monomer" represents a constituent unit in the chain of the final polymer. Normally, the monomer is at least 50 mass. % polymer, more preferably at least 60 mass. %, even more preferably at least 80 mass. % and most preferably at least 90 mass. %, while the comonomer component units continue to remain part of the polymer.

The suspension comprises a solid phase and a liquid phase, the liquid phase of the present invention may be a liquid or a supercritical fluid. It contains a solvent and reagents, i.e. a monomer, possible comonomers and hydrogen. Used in the description of the present patent application, the term "polymer suspension" indicates that the polymer is the main part of the solid phase, however, other solid particles, such as a catalyst, may be contained.

As used herein, the term “solvent” preferably includes within its scope liquid monomers that are used for polymerization, such as propylene or liquid C ₃ -C ₁₀ hydrocarbons such as propane, n-butane, isobutane, pentane or hexane. In one preferred embodiment of the present invention, the solvent is propane and / or propylene, the latter being substantially preferred when the resulting polymer is polypropylene.

As used herein, the term “1st polymer suspension” refers to a polymer suspension discharged from a first outlet.

As used herein, the term “2nd polymer suspension” refers to a polymer suspension discharged from a second outlet.

Used in the description of the present patent application, the term “total polymer suspension” or “total unloaded polymer suspension”, in contrast to the (whole) polymer suspension in a circulation reactor, is a suspension obtained by combining the first suspension and the liquid phase from the second outlet, that is, the solvent or 2nd polymer system.

The present invention is applicable to any homopolymerization or copolymerization of olefins carried out in a loop reactor and optionally at least one subsequent reactor, such as a gas phase reactor, in which a solvent is used to prepare a polymer suspension comprising an olefin polymer and said solvent. For example, in the circulation reactor of the present invention, propylene can be homopolymerized or copolymerized with at least one of ethylene and / or C ₄ -C ₂₀ alpha olefin or ethylene can be homopolymerized or copolymerized with at least one of C ₃ -C ₂₀ alpha olefin. Preferably, the polymerization is carried out in an inert hydrocarbon solvent.

Accordingly, the present invention, in particular, relates to homopolymerization or copolymerization of propylene or ethylene. In one embodiment, the present invention relates to a method for producing a heterophasic propylene copolymer, in which at least a portion of the matrix or the entire matrix of the heterophasic propylene copolymer is obtained in a circulation reactor, while the elastomeric phase is obtained in a reactor downstream of the reactor in a production line. In one embodiment, the present invention relates to a method for producing a heterophasic propylene copolymer in which a polypropylene matrix is produced in a circulation reactor and the elastomeric phase is polymerized in a subsequent second reactor, such as a gas phase reactor in the presence of a matrix. In another preferred embodiment, the present invention relates to a method for producing a heterophasic propylene copolymer in which a first part of a matrix is produced in a circulation reactor and a second part of the matrix is polymerized in a second reactor, preferably a gas phase reactor. Then, the matrix thus obtained is transferred to one or more (gas-phase) reactors, preferably to two reactors connected in series, in which the elastomeric phase of the heterophase system is polymerized. The method of the present invention also includes, within its scope, production of a crystalline propylene homopolymer or copolymer in a loop reactor and in one or more subsequent (semi) crystalline reactors, preferably one reactor, such as a gas phase reactor located downstream of the loop reactor.

The temperature in the loop reactor is typically from 50 ° C to 110 ° C, preferably from 60 ° C to 100 ° C, and most preferably from 65 ° C to 95 ° C. In the case where ethylene or propylene is homopolymerized in a loop reactor, it is sometimes preferred that the loop reactor is operated under conditions known as “supercritical”, where the working temperature exceeds the critical temperature of the reaction mixture and the working pressure exceeds the critical pressure of the reaction mixture. Under such conditions, the operating temperature is preferably higher than 90 ° C and most preferably higher than 93 ° C. Used in the description of the present patent application, the term "supercritical fluid" refers to a liquid or mixture of liquids at a temperature and pressure exceeding the critical temperature and pressure of the specified liquid or mixture of liquids.

The temperature in the loop reactor can be controlled and controlled using any method known in the art to a person skilled in the art to which the present invention relates.

During the polymerization process, the suspension in the circulation reactor is continuously circulated through the circulation reactor using a circulation pump or other means well known to those skilled in the art to which the present invention relates. As is well known to those skilled in the art to which the present invention relates, the flow rate is such that the polymer does not settle in the reactor and the suspension remains homogeneous.

The polymerization of an olefin, such as the polymerization of propylene and / or ethylene in a loop reactor, is preferably carried out in a suspension phase, thus the polymer particles formed during the polymerization, together with the catalyst fragmented and dispersed in these polymer particles, are suspended in a solvent. As indicated above, the suspension is further mixed by circulation in the reactor, facilitating the transfer of reagents from the solvent to the polymer particles.

In the case of propylene polymerization, the suspension polymerization preferably represents the so-called bulk polymerization. Used in the description of the present patent application, the term "mass polymerization" refers to a method when the polymerization is carried out in a liquid monomer essentially in the absence of an inert solvent. However, as is known to those skilled in the art to which the present invention relates, the monomers used in industrial production are never pure, but always contain aliphatic hydrocarbons as impurities. For example, a propylene monomer may contain up to 5% propane as impurities. Since the propylene consumed in the reaction also recycles from the reaction effluent back to polymerization, inert components tend to accumulate, and therefore, the reaction medium may include up to 40 mass. % of the total mass of the reaction medium, compounds other than monomer. However, it should be understood that this method of polymerization is still included in the scope of the concept of "polymerization in mass", as described above.

The working pressure must be chosen so that the contents of the circulation reactor remained either in a liquid or in a supercritical state. For working with a liquid suspension, a suitable working pressure is in the range from 1 to 150 bar and preferably from 10 bar to 100 bar. For operation with a supercritical suspension, a suitable working pressure is in the range of 50 to 1000 bar and preferably 55 bar to 80 bar.

The pressure in the circulation reactor can be controlled and regulated using any method known from the prior art to a person skilled in the art to which the present invention relates.

Additionally, hydrogen may be introduced into the loop reactor to control the molecular weight of the resulting polymer. The amount of hydrogen mainly depends on the catalyst system used and the desired molecular weight or melt flow rate of the MFR _{2 of the} final polymer. Also, one or more comonomers can be introduced into the loop reactor to modify the mechanical properties, density and flexibility of the final polymer and / or to facilitate stable operation during the polymerization reaction in the loop reactor.

Preferably, olefin monomers such as ethylene or propylene (co) are polymerized in a loop reactor in the presence of hydrogen and optionally comonomers to form a polymer.

The average concentration of the polymer suspension in the circulation reactor, as a rule, is from 15 mass. % to 55 mass. % of the total weight of the polymer suspension in a circulation reactor. In one preferred embodiment of the present invention, the average concentration of the suspension in the circulation reactor, as a rule, is from 20 mass. % to 55 mass. % and more preferably from 25 mass. % to 52 mass. % of the total weight of the polymer suspension in a circulation reactor.

The concentration of the polymer in the polymer suspension can be determined using any method known to the person skilled in the art to which the present invention relates. It can be determined, for example, by measuring the density of the suspension using a suitable method known from the prior art, such as measurement using radioactive substances, ultrasonic measurement and the like. Then, the polymer concentration in the suspension can be calculated using the following equation:

Where

w _p is the mass of the polymer fraction in suspension,

ρ _s is the density of the suspension,

ρ _f is the density of the liquid phase and

ρ _p is the density of the polymer.

The catalyst system used in the loop reactor and any subsequent reactor may be any polymerization catalyst system known in the art. Therefore, the catalyst system can be a chromium catalyst, as indicated, for example, in EP 279890 or EP 307907. It can also be a Ziegler-Natta catalyst, such as described, for example, in EP 688794, EP 949274, WO 99/58584 or WO 01/55230. Additionally, the catalyst system may be a metallocene catalyst, as described, for example, in WO 97/28170, WO 00/34341 or WO 2004/029112.

The polymerization reaction of olefin monomers such as propylene or ethylene can be carried out as in any known circulation reactor used for suspension polymerization. In such reactors, the slurry circulates at a high speed through a closed pipe using a circulation pump. Circulation reactors are well known in the prior art and examples are given, for example, in US 4,582,816 A, US 3,405,109 A, US 3,324,093 A, EP 479,186 A and US 5,391,654 A.

Typically, the loop reactor of the present invention is a tubular continuous structure.

In one embodiment of the present invention, the loop reactor includes at least one lower horizontal segment, at least one upper horizontal segment, and at least two vertical segments that are connected by a working connection. For example, the circulation reactor of the present invention includes at least one lower horizontal segment, at least one upper horizontal segment, and at least two vertical segments that are connected by a working connection. In particular, the vertical and horizontal segments can be connected to each other by a working connection using loops, such as loops with a straight or curved configuration, thus ensuring a continuous flow in the circulation reactor, which is essentially free of internal obstacles. Accordingly, the loop reactor preferably includes:

(a) one lower horizontal segment,

(b) two lower loops,

(c) one upper horizontal segment,

(d) two upper loops and

(e) two vertical segments,

connected by a working connection, where

two lower loops connect the lower horizontal segment to two vertical segments and two upper loops connect the upper horizontal segment to two vertical segments. In particular, one of the two lower loops connects the lower horizontal segment to the lower end of the first vertical segment and the other of the two lower loops connects the other end of the lower horizontal segment to the lower end of the second vertical segment, while one of the two upper loops connects one end of the upper horizontal segment with the upper end of the first vertical segment and the other of the two upper loops connects the other end of the upper horizontal segment with the upper end of the second vertical segment a.

However, it should be noted that the configuration and shape of the circulation reactor can vary widely, while providing a tubular continuous structure that defines a closed loop. Therefore, the horizontal segments can also be in the form of continuous loops connecting the two vertical segments together.

Accordingly, the circulation reactor includes:

(a) one bottom loop,

(b) one upper loop and

(c) two vertical segments,

connected by working connection

where the lower loop and the upper loop connect two vertical segments. In particular, the lower loop is connected at one end to the lower end of the first vertical segment and at its other end connected to the lower end of the second vertical segment, while the upper loop at its one end is connected to the upper end of the first vertical segment and the other end is connected to the upper end of the second vertical segment.

Additionally, each horizontal and / or vertical segment may be provided in the form of a continuous segment or in the form of multiple segments. For example, the loop reactor of the present invention may be a vertical loop reactor or a horizontal loop reactor, preferably a vertical loop reactor.

The heat generated during the polymerization reaction, as a rule, is removed using indirect means of heat exchange with a cooling medium, preferably water, such as shirts surrounding at least part of the circulation reactor. The volume of the circulation reactor can vary within wide limits, but, as a rule, ranges from 10 dm ³ to 200 m ³ .

During normal operation in the polymerization process, the polymer slurry is discharged from the loop reactor continuously through one outlet, preferably through a first outlet. Used in the description of the present patent application, the term "normal operation" means that the conditions in the circulation reactor are controlled so as to obtain the desired polymer in the circulation reactor, and the polymer concentration in the polymer suspension reaches a predetermined level. In the case where the operating conditions are not balanced, for example, due to the reduced activity of the catalyst or due to the transition from one polymer to another polymer during normal operation, the discharge from the first outlet may be reduced or increased. However, such regulation only through the use of a single outlet is rather slow and often not suitable for exercising sufficient control of polymerization conditions.

Accordingly, one of the specific requirements of the present invention is that the circulation reactor includes, in addition to the first outlet, a second outlet. The first and second outlet openings are preferably connected to a second reactor, such as a gas phase reactor. Therefore, the first polymer suspension and the second polymer suspension, respectively, can be discharged from the circulation reactor through the first and second outlet openings and transferred to a second reactor, i.e. a gas phase reactor. Preferably, the first polymer slurry from the first outlet and the second polymer slurry from the second outlet are combined above the second reactor through a production line and then transferred together to the second reactor.

The first and second outlet openings may be located at any suitable portion of the loop reactor. However, it should be noted that the first and second outlet openings should be located at different places in the circulation reactor. Only in this case can it be guaranteed that various polymer suspensions will be discharged from both outlets.

Accordingly, it should be understood that the first outlet must be positioned so that the first polymer suspension discharged from the circulation reactor has a polymer concentration of the same or higher than the average polymer concentration in the circulation reactor.

Accordingly, the second outlet should be positioned so that the second polymer suspension discharged from the circulation reactor has a polymer concentration lower than the average polymer concentration in the circulation reactor.

As indicated above, the average concentration of the polymer in the polymer suspension in a circulation reactor, as a rule, is from 15 mass. % to 55 mass. %, preferably from 20 mass. % to 55 mass. % and more preferably from 25 mass. % to 52 mass. % of the total weight of the polymer suspension in a circulation reactor.

Accordingly, it is understood that the first outlet is located in the circulation reactor in such a way that the concentration of polymer in the first polymer suspension at this specific location is the same or higher than the average polymer concentration in the circulation reactor. For example, if the average concentration of the polymer in the polymer suspension in the circulation reactor is about 25 mass. % of the total mass of the polymer suspension in the circulation reactor, the first outlet is positioned so that the concentration of polymer in the first polymer suspension in this specific location is about 25 mass. % or more of the total mass of the polymer suspension in the first polymer suspension.

On the contrary, it is understood that the second outlet is located in the circulation reactor in such a way that the concentration of polymer in the second polymer suspension in this specific location is less than the average concentration in the circulation reactor. For example, if the average concentration of the polymer in the polymer suspension in the circulation reactor is about 25 mass. % of the total mass of the polymer suspension in the circulation reactor, the second outlet is positioned so that the concentration of polymer in the second polymer suspension in this specific location is less than 24 mass. % of the total weight of the polymer suspension in the 2nd polymer suspension.

Therefore, the first outlet is suitably located on the outer periphery of the circulation reactor. Used in the description of the present patent application, the term "outer periphery" refers to that side of the circulation reactor, which forms the open side of the closed loop, that is, the first outlet is located on the outer tubular surface of the circulation reactor. The first outlet may be located on the outer periphery of any of the horizontal segments of the circulation reactor or on the outer periphery of any of the loops of the circulation reactor.

In a preferred embodiment of the present invention, the first outlet is located on the outer periphery of the lower horizontal segment or the outer periphery of one of the (two) lower loops of the circulation reactor, preferably on the outer periphery of the lower horizontal segment of the circulation reactor.

Additionally or alternatively, the second outlet is located on the inner periphery of the horizontal segments (lower or upper horizontal segment) or on the loops (lower or upper loop (s)) of the circulation reactor. Used in the description of the present patent application, the term "inner periphery" refers to that side of the circulation reactor that forms the closed side of the closed loop, that is, the second outlet is located on the inner tubular surface of the circulation reactor, namely, on the inner surface of the horizontal segments (lower or upper horizontal segment) or on loops (lower or upper loop (s)) of the circulation reactor.

Accordingly, the second outlet is preferably located on the inner periphery of the lower horizontal segment or located on the inner periphery of the lower (two) loop (s) of the circulation reactor. In one specific embodiment of the present invention, that is, in an embodiment where the circulation reactor includes horizontal segments, a second outlet is located on the inner periphery of one of the two lower loops, i.e. the loops connect the vertical segments to the lower horizontal segment. In another preferred embodiment of the present invention, that is, in the embodiment where the circulation reactor includes horizontal segments, a second outlet is located on the inner periphery of the lower loop, that is, the loop connects two vertical segments.

Accordingly, it is understood that in one particular embodiment of the present invention, that is, an embodiment where the circulation reactor includes horizontal segments, refers to a circulation reactor comprising a first and second outlet for discharging a polymer slurry, where the first outlet is located on the outer periphery of the lower or the upper horizontal segment or on the outer periphery of the lower or upper loop of the circulation reactor, and the second outlet is located on the inside the upper periphery of the lower or upper horizontal segment or the outer periphery of the lower or upper loop of the circulation reactor.

In another preferred embodiment of the present invention, that is, an embodiment where the circulation reactor includes horizontal segments, the circulation reactor includes first and second discharge openings for discharging the polymer slurry, where the first discharge opening is located on the outer periphery of the lower or upper loop of the circulation reactor, and the second the outlet is located on the inner periphery of the lower or upper loop of the circulation reactor.

In another preferred embodiment of the present invention, that is, an embodiment where the circulation reactor includes horizontal segments, the circulation reactor includes first and second discharge openings for discharging the polymer slurry, where the first discharge opening is located on the outer periphery of the lower horizontal segment or the outer periphery of one of the two lower loops of the circulation reactor, preferably on the outer periphery of the lower horizontal segment, and a second outlet it is located on the inner periphery of the upper horizontal segment or the inner periphery of one of the two upper loops of the circulation reactor, preferably on the inner periphery of one of the two upper loops of the circulation reactor.

In another preferred embodiment of the present invention, that is, an embodiment where the circulation reactor includes horizontal segments, the circulation reactor includes first and second discharge openings for discharging the polymer slurry, where the first outlet is located on the outer periphery of the lower loop of the circulation reactor, and the second outlet located on the inner periphery of the upper loop of the circulation reactor.

In another preferred embodiment of the present invention, that is, an embodiment where the circulation reactor includes horizontal segments, the circulation reactor includes first and second discharge openings for discharging the polymer slurry, where the first discharge opening is located on the outer periphery of the lower horizontal segment or on the outer periphery of one of the two lower loops of the circulation reactor, preferably on the outer periphery of the lower horizontal segment, and the second outlet stie disposed on the inner periphery of the lower horizontal segment, or on an outer periphery of one of the two lower circulation loop of the reactor, preferably at the inner periphery of one of the two lower circulation loop of the reactor.

In another preferred embodiment of the present invention, that is, an embodiment where the circulation reactor includes horizontal segments, the circulation reactor includes first and second discharge openings for discharging the polymer slurry, where the first outlet is located on the outer periphery of the lower loop of the circulation reactor and the second outlet is located on the inner periphery of the lower loop of the circulation reactor.

According to the present invention, the second outlet is operated before and / or during and / or after the first outlet. Used in the description of the present patent application, the term "sequentially" outlet openings means that the polymer suspension is discharged from a circulation reactor. Therefore, it is understood that the amount of polymer suspension discharged from the first and second outlet is accordingly optimally adjusted for each, so that a predetermined concentration of polymer in the suspension in the circulation reactor is achieved. As is well known from the prior art to which the present invention relates, the total polymer slurry output from the circulation reactor through the first and second outlet openings can be determined, for example, by using a pressure controller that maintains a constant pressure in the circulation reactor.

As indicated above, the discharged solvent or polymer suspension / slurry is preferably transferred to a second reactor, such as a gas phase reactor. Accordingly, the first and second outlet openings are preferably connected to a second reactor, such as a gas phase reactor, through a pipeline. Even more preferably, the pipe of the first outlet and the pipe of the second outlet are connected to each other at the connection point above the second reactor through a production line and further, the pipe goes from the specified connection point to the second reactor.

When using the circulation reactor of the present invention, including a specific combination of the first and second outlet, it is possible to adjust the amount of the first polymer slurry discharged from the first outlet and the second polymer slurry discharged from the second outlet according to specific needs. Due to this regulation, the amount of polymer in the circulation reactor can be adjusted very easily and quickly at the beginning of the polymerization process or during normal operation of the circulation reactor. Additionally, it is also very convenient to adjust the amount of polymer supplied to the second reactor, along with the concentration of polymer in the total polymer slurry transferred to the second reactor according to specific needs.

In the initial phase in the loop reactor, the first outlet is preferably closed and the second outlet is open. Even more preferably, the discharged liquid phase or the second polymer slurry is transferred to a second reactor. Due to this specific switching (the first outlet is closed, the second outlet is open), the polymer concentration and holding time in the circulation reactor can be increased to a predetermined level / time, by maintaining a constant mass of the stream passing through the circulation reactor. If required, at the same time, the second reactor may already be provided with some polymer slurry discharged from the second outlet.

Typically, in the initial phase from 50 to 100 mass. % Of the 2nd polymer slurry of the total weight of the unloaded polymer slurry is discharged from the second outlet and optionally transferred to a second reactor, such as a gas phase reactor. Preferably, the polymer concentration in the 2nd polymer suspension is more than 0 to 10 mass. % Accordingly, it is clear that the unloaded 2nd polymer suspension contains from 0.1 to 5.0 mass. %, such as from 0.1 to 2.0 mass. % polymer.

During normal operation of the circulation reactor and / or the polymerization reactor system including the circulation reactor, as a rule, the first outlet is (fully) open and the second outlet is closed or only slightly open. In such a situation, it is understood that the total amount of polymer slurry discharged from the loop reactor is mainly discharged through the first outlet, that is, at least 90 masses. %, such as from 90 to 100 mass. %, more preferably at least 95 mass. %, such as from 95 to 100 mass. %, while the rest is discharged through the second outlet. However, in the case when the conditions in the circulation reactor do not change intentionally (for example, due to a decrease in the activity of the catalyst) or should be switched during normal operation from the polymerization of one particular polymer to another specific polymer, the second outlet can be opened, i.e., completely or partially open to allow adjustment of the conditions in the circulation reactor to predetermined ones. Also in this case, the second polymer suspension discharged through the second outlet from the circulation reactor is transferred to the second reactor.

Under such conditions, it is preferable that the amount of the first polymer suspension discharged through the first outlet is from 65 mass. % to 95 mass. % of the total weight of the total discharged polymer suspension. In one preferred embodiment of the present invention, the amount of the first polymer suspension discharged through the first outlet is from 70 mass. % to 90 mass. % of the total weight of the total discharged polymer suspension. For example, the amount of the first polymer suspension discharged through the first outlet is from 75 mass. % to 85% by weight of the total weight of the total polymer suspension discharged.

Accordingly, the amount of the 2nd polymer suspension discharged through the second outlet is 5 mass. % to 35 mass. % of the total weight of the total discharged polymer suspension. In one preferred embodiment of the present invention, the amount of the 2nd polymer suspension discharged through the second outlet is from 10 mass. % to 30 mass. % of the total weight of the total discharged polymer suspension. For example, the amount of the 2nd polymer suspension discharged through the second outlet is from 15 mass. % to 25 mass. % of the total weight of the total discharged polymer suspension.

Therefore, in one preferred embodiment of the present invention, the amount of the first polymer suspension discharged through the first outlet is from 65 mass. % to 95 mass. % of the total mass of the total polymer suspension discharged, and the amount of the second polymer suspension discharged through the second outlet is from 5 mass. % to 35 mass. % of the total weight of the total discharged polymer suspension. In another preferred embodiment of the present invention, the amount of the first polymer suspension discharged through the first outlet is from 70 mass. % to 90 mass. % of the total mass of the total polymer suspension discharged, and the amount of the second polymer suspension discharged through the second outlet is from 10 mass. % to 30 mass. % of the total weight of the total discharged polymer suspension. For example, the amount of the first polymer suspension discharged through the first outlet is from 75 mass. % to 85 mass. % of the total mass of the total discharged polymer suspension, and the amount of the 2nd polymer suspension discharged through the second outlet is 15 mass. % to 25 mass. % of the total weight of the total discharged polymer suspension.

The following are typical conditions for controlling discharge from a circulation reactor through the first and second outlet openings of the operating conditions in the circulation reactor and optionally the second reactor.

It is understood that the ratio of the first polymer suspension discharged through the first outlet and the second polymer suspension discharged through the second outlet [PS-01 / PS-02] is at least 1.8 and preferably at least 2.5,

Where

"PS-01" is the amount [given in mass percent] of the 1st polymer slurry discharged through the first outlet, and

"PS-02" is the amount [given in mass percent] of the second polymer slurry discharged through the second outlet.

Preferably, the ratio of the polymer slurry discharged through the first outlet and the second outlet [PS-01 / PS-02] is in the range of 1.8 to 19, more preferably in the range of 2 to 15, even more preferably in the range of 2 to 10 and most preferably in the range of 2 to 7.5,

Where

"PS-01" is the amount [given in mass percent] of the 1st polymer slurry discharged through the first outlet, and

"PS-02" is the amount [given in mass percent] of the second polymer slurry discharged through the second outlet.

For example, the ratio of the polymer slurry discharged through the first outlet and the second outlet [PS-01 / PS-02] is in the range of 3 to 6, such as in the range of 3 to 5.

As indicated above, the first polymer suspension discharged through the first outlet may contain an amount of polymer equal to at least 15 mass. %, more preferably at least 20 mass. % and most preferably at least 25 mass. % of the total mass of the first polymer suspension discharged through the first outlet. In any case, the first polymer suspension contains at least the same amount of polymer as with an average polymer concentration in the circulation reactor

Alternatively, the first polymer suspension discharged through the first outlet may contain an amount of polymer equal to a maximum of 60 mass. %, more preferably a maximum of 58 wt. % and most preferably a maximum of 55 mass. % of the total mass of the first polymer suspension discharged through the first outlet.

Accordingly, it is understood that the first polymer suspension discharged through the first outlet may contain an amount of polymer from 15 mass. % to 60 mass. %, more preferably from 20 mass. % to 58 mass. % and most preferably from 25 wt. % to 55 mass. % of the total mass of the first polymer suspension discharged through the first outlet.

In contrast, the second polymer slurry discharged through the second outlet has a polymer concentration substantially lower than the average polymer concentration in the polymer slurry in the reactor.

In particular, the second polymer suspension, discharged through the second outlet, contains an amount of polymer equal to more than 0.1 mass. % and more preferably at least 0.5 mass. % of the total mass of the second polymer suspension discharged through the second outlet.

Additionally or alternatively, the 2nd polymer suspension discharged through the second outlet may contain a polymer amount of at most 10 masses. % and more preferably a maximum of 5 mass. % of the total mass of the second polymer suspension discharged through the second outlet.

Accordingly, it is understood that the second polymer suspension discharged through the second outlet contains an amount of polymer from 0.1 mass. % to 10 mass. %, more preferably from 0.5 wt. % to 5 mass. % and most preferably from 1 mass. % to 5 mass. % of the total mass of the second polymer suspension discharged through the second outlet. For example, the second polymer suspension discharged through the second outlet contains an amount of polymer from 2 mass. % to 4 mass. %, such as from 2.5 wt. % to 3.5 wt. % of the total mass of the second polymer suspension discharged through the second outlet.

In one preferred embodiment of the present invention, the ratio of the polymer contained in the first polymer suspension discharged through the first outlet, and the polymer contained in the second polymer suspension discharged through the second outlet [P-01 / P-02], is at least 3, more preferably at least 5,

Where

"PS-01" is the amount [given in mass percent] of the 1st polymer slurry discharged through the first outlet, and

"PS-02" is the amount [given in mass percent] of the second polymer slurry discharged through the second outlet.

For example, the ratio of the polymer contained in the first polymer suspension discharged through the first outlet, and the polymer contained in the second polymer suspension discharged through the second outlet [P-01 / P-02], ranges from 3 up to 25, more preferably from 5 to 20, and most preferably in the range from 5 to 15.

As indicated above, the polymer suspension may be discharged from the circulation reactor through the first outlet and / or second outlet, depending on the specific needs. Therefore, in one preferred embodiment of the present invention, the polymer suspension is continuously discharged through the first outlet and the second outlet. In another preferred embodiment of the present invention, the polymer suspension is discharged periodically through the first outlet and the second outlet. In another preferred embodiment of the present invention, the polymer suspension is continuously discharged through a first outlet and periodically through a second outlet. In another preferred embodiment of the present invention, the polymer suspension is discharged periodically through the first outlet and continuously through the second outlet.

Periodic unloading can be carried out, for example, using periodically opening valves, rotary valves, settling elbows and the like. Continuous discharge can be carried out using a working control valve, such as a butterfly valve, whose position is regulated, for example, based on the pressure in the reactor. Such agents are well known to those skilled in the art to which the present invention relates, and can be adapted to the specific needs necessary to carry out the present invention.

As indicated above, the loop reactor is preferably part of a polymerization reactor system comprising a plurality of polymerization reactors to produce olefin polymers, such as the aforementioned olefin homopolymers or copolymers. These polymerization reactors are connected in series. Accordingly, said polymerization reactor system includes in a cascade a loop reactor and at least one additional reactor. The reactor following the loop reactor may be any olefin polymerization reactor, such as, again, a loop reactor or a gas phase reactor, the latter being preferred.

Used in the description of the present patent application, the term "gas phase reactor" refers to a reactor with mechanical stirring or to a fluidized bed reactor. Preferably, the gas phase reactor is a fluidized bed reactor with a gas flow rate of at least 0.1 m / s.

The third polymerization reactor or any subsequent polymerization reactor may be any type of reactor. However, it is preferred that the third or any subsequent reactor for the polymerization of the polymerization reactor system be another gas phase reactor.

In one aspect of the present invention, the polymerization reactor system of the present invention comprises two polymerization reactors, where one polymerization reactor represents the above loop reactor and the other polymerization reactor represents a gas phase reactor. In another preferred embodiment of the present invention, the polymerization reactor system of the present invention includes at least three polymerization reactors, that is, at least a third polymerization reactor follows the aforementioned loop reactor and gas phase reactor. Used in the description of the present patent application, the term "reactor for polymerization" refers to the main places where the polymerization takes place. Therefore, in the case where the polymerization reactor system of the present invention consists of two polymerization reactors, this definition does not exclude the possibility that the entire polymerization reactor system includes, for example, a prepolymerization step in the prepolymerization reactor. Used in the description of the present patent application, the term "consists of" has only a closed meaning in relation to the main polymerization reactors.

In the case where the entire polymerization reactor system and / or the aforementioned loop reactor includes a prepolymerization step in a prepolymerization reactor, the prepolymerization can be carried out with continuous stirring in a reactor vessel or in a loop reactor, preferably in a loop reactor. In the case where the loop reactor is used for prepolymerization, the loop reactor may or may not have one or more of the characteristics of the above loop reactor.

Typically, the prepolymerization reaction is carried out at a temperature of from 0 to 60 ° C, preferably from 10 to 50 ° C, and more preferably from 10 to 45 ° C.

The pressure in the prepolymerization reactor is not critical, but must be high enough to maintain the reaction mixture in the liquid phase. Accordingly, the pressure is from 20 to 100 bar, for example from 30 to 70 bar.

Conversion of the prepolymer is typically carried out by contacting the catalyst system with one or more olefins such as ethylene and / or propylene and optionally comonomer in such an amount that the prepolymer contains from 0.002 millimoles to 10 millimoles of transition metal per gram.

Alternatively or additionally, the amount of prepolymer per catalyst is preferably 10 to 1000 g per g component of the solid catalyst system, more preferably 50 to 500 g per g component of the solid catalyst system.

One skilled in the art to which the present invention relates will understand that particles of a catalyst system recovered from a continuous stirring prepolymerization reactor do not all contain the same amount of prepolymer. Instead, each particle has its own quantitative characteristics, which depend on the exposure time of this particle in the prepolymerization reactor. Since some particles remain in the reactor for a relatively long period of time, the amount of prepolymer on the different particles is different, and some individual particles may contain an amount of prepolymer beyond the above limits. However, the average amount of prepolymer on the catalyst system is preferably within the above ranges. The amount of prepolymer obtained in the prepolymerization reactor is known in the prior art, inter alia from GB 1,580,635.

The particle size of the prepolymer can be controlled using techniques well known to those skilled in the art to which the present invention relates, such as screening, hydrocyclone or elutriation of small and large particles and the like.

The components of the catalyst system are preferably all introduced in the prepolymerization step. However, the component of the solid catalyst system and the cocatalyst can be fed separately, it is possible to supply only a portion of the cocatalyst in the prepolymerization step, while the remaining portion is introduced in subsequent polymerization steps, such as in said circulation reactor. Also in this case, it is necessary to introduce so much cocatalyst at the pre-polymerization stage so that a sufficient polymerization reaction takes place on it.

Additionally, at the pre-polymerization stage, it is possible to introduce additional components. Accordingly, hydrogen can also be introduced in the prepolymerization step to control the molecular weight of the polymer, as is known to those skilled in the art to which the present invention relates. Additionally, antistatic additives can be added to prevent particles from adhering to each other and to the walls of the reactor.

The prepolymer is discharged from the prepolymerization reactor continuously or intermittently through an outlet and is preferably directly fed to the above-mentioned circulation reactor, directly fed.

In the case where the gas phase polymerization stage is followed by the polymerization stage in the loop reactor, it is preferable to feed the polymer slurry from the loop reactor directly to the gas phase polymerization zone without a flash step between the steps. This type of direct feed is described in EP 887379 A, EP 887380 A, EP 887381 A and EP 991684 A. As used in the description of the present patent application, the term “direct feed” refers to a process in which the contents of a circulation reactor, a polymer slurry containing an olefin polymer and the solvent is fed directly to the next stage in a gas phase reactor. Accordingly, the first polymer suspension discharged from the first outlet and the second polymer suspension discharged from the second outlet are directly fed to a second reactor, i.e., a gas phase reactor. In one embodiment of the present invention, the 1st polymer slurry discharged from the first outlet and the 2nd polymer slurry discharged from the second outlet are directly fed to the second reactor. This can be done, for example, by using pipelines connected to the first and second outlet, respectively, directly to the second reactor or gas phase reactor. However, in a preferred embodiment of the present invention, the first polymer suspension discharged from the first outlet and the second polymer suspension discharged from the second outlet are directly fed to the second reactor, combined above the second reactor through a production line, i.e., a gas phase reactor , and then transferred together to a second reactor. In this case, the pipe of the first outlet and the pipe of the second outlet are connected to each other at the connection point above the second reactor via a production line and additionally, the pipeline goes from the specified connection point to the second reactor, i.e., a gas-phase reactor.

Alternatively, the polymer suspension may also be directed to the flash step, to the further concentration step before being fed to the gas phase polymerization step. Accordingly, the term “indirect feed” as used in the description of the present patent application refers to a process in which the contents of the loop reactor, that is, the polymer slurry, are fed into the gas phase reactor through a separation unit to separate the reaction medium and the reaction medium in the form of gas is removed from the installation. Before feeding the polymer suspension into the gas phase, some components, such as hydrogen, can be completely or partially removed from it using various technical means, such as a separation unit. As used in the description of this patent application, the term “separation unit” refers to a work unit in which some light components, for example hydrogen or optionally nitrogen, can be completely or partially separated from the monomer (s) using various technical means, such as flashing ), membranes, distillation, distillation or condensation in an air-condensing unit.

The gas phase reactor, which is part of the polymerization reactor system, is preferably a fluidized bed reactor or a fast fluidized bed reactor, or a fixed bed reactor, or any combination thereof.

In the case where a combination of gas phase reactors is used, the polymer is transferred from one polymerization reactor to another. Additionally, part or all of the polymer from the polymerization step may be returned to the preceding polymerization step, such as the preceding step in the aforementioned loop reactor and / or the preceding step in the gas phase reactor.

The gas phase reactor, which is part of the polymerization reactor system, preferably operates at a temperature of from 50 to 100 ° C, preferably from 65 to 95 ° C. The operating pressure is preferably from 10 to 40 bar, for example from 15 to 30 bar.

An olefin polymer is produced in a gas phase reactor. For example, propylene monomers are copolymerized with at least one ethylene and / or C ₄ -C ₂₀ alpha-olefin comonomer or olefin monomers such as propylene are homopolymerized.

In one preferred embodiment of the present invention, olefin monomers, such as ethylene or propylene, are homopolymerized in a gas phase reactor with a small amount of hydrogen to produce a polyethylene homopolymer or polypropylene homopolymer. For example, the reaction mixture contains from 60 mol. % to 99 mol. % propylene and from 0.001 mol. % to 3 mol. % hydrogen. The rest consists of inert components such as nitrogen or propane.

In another preferred embodiment of the present invention, olefin monomers such as ethylene or propylene are copolymerized in a gas phase reactor with a small amount of hydrogen to produce a polyethylene copolymer or polypropylene copolymer. For example, the reaction mixture contains from 60 mol. % to 96 mol. % propylene and from 0.001 mol. % to 10 mol. % hydrogen. The rest consists of inert components such as nitrogen or propane.

Summarizing the above, in one essentially preferred aspect, the present invention further relates to a method for producing olefin polymers in the aforementioned loop reactor and / or in the aforementioned polymerization reaction system, the method comprises the steps of:

- supply of olefin monomers and a catalytic system in a circulation reactor to obtain a polymer suspension in a circulation reactor, and

- the control,

(1) the total amount of polymer discharged from the loop reactor,

and / or

(2) the total amount of polymer suspension discharged from the loop reactor,

and / or

(3) the concentration of the polymer in the total polymer slurry discharged from the circulation reactor, by adjusting the ratio of the first polymer slurry discharged through the first outlet, and the second polymer slurry discharged through the second outlet.

A detailed description of the stages of the method according to preferred embodiments of the present invention is given above.

In the case where the method for producing olefin polymers is carried out in a circulation reactor that is part of a polymerization reactor system, the polymer suspension discharged through the first outlet and the second outlet is preferably further sent to a gas phase reactor.

The separation of the flow achieved between the aforementioned loop reactor and the second reactor, that is, a gas phase reactor using the above polymerization reactor system, is typically from 75:25 to 40:60, more preferably from 65:35 to 50:50 and most preferably from 60:40 to 50:50. For example, the separation of the flow achieved between the loop reactor and the gas phase reactor is about 55:45.

Additionally or alternatively, if the polymerization reactor system is used to produce an olefin polymer, then the yield in the above-mentioned circulation reactor is equal to or more than the output in a gas-phase reactor. Preferably, the yield in the above loop reactor is more than 40 mass. % of the total weight of the obtained olefin polymer. Therefore, according to a preferred embodiment of the present invention, the olefin polymer obtained in the above-mentioned circulation reactor is from 50 mass. % to 75 mass. %, preferably from 50 mass. % to 65 mass. %) and most preferably from 50 mass. % to 60 mass. % of the total weight of the obtained olefin polymer. Accordingly, the output in the gas phase reactor is less than 60 mass. % of the total weight of the obtained olefin polymer. Therefore, according to a preferred embodiment of the present invention, the olefin polymer obtained in the above circulation reactor is from 25 mass. % to 50 mass. %, preferably from 35 wt. % to 50 mass. % and most preferably from 40 mass. % to 50 mass. % of the total weight of the obtained olefin polymer.

In particular, it is understood that the present invention also relates to a method for controlling the average aging time of an olefin polymer obtained in the aforementioned loop reactor and / or in a loop reactor of the above polymerization reaction system. In particular, the method comprises the steps of:

a) supplying olefin monomers, a solvent and a catalytic system to the aforementioned circulation reactor and / or circulation reactor, which is part of the above polymerization reactor system to obtain a polymer suspension,

(b) control,

(1) the total amount of polymer discharged from the loop reactor,

and / or

(2) the total amount of polymer suspension discharged from the loop reactor,

and / or

(3) the concentration of the polymer in the total polymer slurry discharged from the circulation reactor, by adjusting the ratio of the first polymer slurry discharged through the first outlet, and the second polymer slurry discharged through the second outlet.

A detailed description of the stages of the method according to preferred embodiments of the present invention is given above.

In view of the above, the present invention in an additional aspect relates to the use of a second outlet located on the aforementioned circulation reactor for monitoring

(1) the total amount of polymer discharged from the loop reactor,

and / or

(2) the total amount of polymer suspension discharged from the loop reactor,

and / or

(3) the concentration of the polymer in the total polymer suspension discharged from the circulation reactor by controlling the discharge of the liquid phase through the second outlet.

In one preferred embodiment of the present invention, combinations of the first and second outlet located in the aforementioned reactor are used to control the average exposure time of the olefin polymer in the aforementioned reactor.

The present invention will now be described with reference to the following illustrative Examples.

EXAMPLES

A. Preparation of the catalyst

A solid catalyst component was prepared according to Example 8 of WO 2004/029112, except that diethylaluminium chloride was used instead of diethylaluminium as the aluminum compound.

B. Polymerization

a) Example of the present invention 1 (IE1):

The above catalyst was continuously fed into the prepolymerization reactor at a rate of 1.6 g / h. The prepolymerization reactor was a stirred tank reactor with a volume of 45 dm ³ and operating as liquid-filled at a temperature of 30 ° C and a pressure of 54 bar. Before feeding the catalyst stream, it was combined with a stream containing triethylaluminium (TEA) and dicyclopentyl dimethoxysilane (DPDMS), so that the molar ratio of TEA / Ti was 262 and the molar ratio of DPDMS / TEA was 10. The flow was about 36 g / h and the stream propylene, so that the average exposure time was 0.3 hours.

The suspension from the prepolymerization reactor was sent to a circulation reactor with a volume of 150 dm ³ and which was operated at a temperature of 80 ° C and a pressure of 52 bar. Propylene was fed into the loop reactor at a feed rate of 205 kg / h. Fresh hydrogen was not supplied, and all of the hydrogen came from the prepolymerization reactor. The propylene homopolymer productivity was 29 kg / h and the melt flow rate of MFR ₂ was 14 g / 10 minutes.

The polymer slurry from the loop reactor was directly fed to the first gas phase reactor, operating at a temperature of 90 ° C and a pressure of 24 bar. The suspension was discharged through two outlet openings. Through the first outlet unloaded 80 mass. % of the suspension of the total weight of the total unloaded suspension, where the concentration of the polymer of the ball is the same as in the reactor, that is, through the first outlet located on the outer periphery of the lower horizontal segment of the circulation reactor. Through the second outlet unloaded 20 mass. % of the suspension of the total weight of the total discharged suspension, that is, the suspension discharged through a second outlet located on the inner periphery of the lower horizontal segment of the circulation reactor. The suspension discharged through the second outlet had a polymer concentration of about 3 mass. % of the total mass of the suspension discharged through the second outlet.

In addition to the polymer suspension discharged from the circulation reactor to the gas phase reactor, propylene and hydrogen were fed, and nitrogen was also supplied as an inert gas, so that the propylene content was 86 mol. % and the ratio of hydrogen to propylene was 3.8 mol. / kmol. The productivity of the reactor was 23 kg / h, and the polymer discharged from the reactor had a melt flow rate of MFR _{2 of} 16 g / 10 minutes, so that the separation of the flow between the circulation and gas-phase reactor was 55/45.

The performance data in the circulation reactor, the solids content in the total suspension discharged from the first outlet and the second outlet, the separation of the flow between the phase in the circulation reactor and the phase in the gas-phase reactor are shown in Table 1.

b) Example of the present invention 2 (IE2):

The polymerization was carried out according to Example of the present invention 1, except that the flow of hydrogen was changed, so that the melt flow rate MFR _{2 of the} obtained propylene homopolymer was 11 g / 10 minutes after the circulation reactor and 14 g / 10 minutes after the gas phase reactor, respectively.

The performance data in the circulation reactor, the solids content in the total suspension discharged from the first outlet and the second outlet, the separation of the flow between the phase in the circulation reactor and the phase in the gas-phase reactor are shown in Table 1.

c) Example of the present invention 3 (IE3):

The polymerization was carried out according to Example of the present invention 1, except that the flow of hydrogen was changed, so that the melt flow rate MFR.2 of the obtained propylene polymer was 10 g / 10 minutes after the circulation reactor and 12 g / 10 minutes after the gas phase reactor , respectively. Additionally, ethylene was fed into the reactors, so that the ethylene content in the propylene copolymer was 1.8 mass. % after the circulation reactor and 2.5 wt. % after a gas phase reactor of the total weight of the propylene copolymer.

The performance data in the circulation reactor, the solids content in the total suspension discharged from the first outlet and the second outlet, the separation of the flow between the phase in the circulation reactor and the phase in the gas-phase reactor are shown in Table 1.

d) Comparative example 1 (CE1):

The polymerization was carried out according to Example of the present invention 1, except that the second outlet was not used.

The performance data in the circulation reactor, the solids content in the total suspension discharged from the first outlet, the separation of the flow between the phase in the circulation reactor and the phase in the gas-phase reactor are shown in Table 1.

e) Comparative Example 2 (CE2):

The polymerization was carried out according to Example of the present invention 3, except that the second outlet was not used. Additionally, ethylene was fed into the reactors, so that the ethylene content in the propylene copolymer was 2 mass. % after the circulation reactor and 3.4 wt. % after a gas phase reactor of the total weight of the propylene copolymer.

The performance data in the circulation reactor, the solids content in the total suspension discharged from the first outlet, the separation of the flow between the phase in the circulation reactor and the phase in the gas-phase reactor are shown in Table 1.

As can be seen from Table 1, the polymerization of olefin monomers in a cascade of polymerization reactions as a result of the separation of the flow between the circulation reactor and the gas phase reactor in a ratio of about 46/54, if the circulation reactor operates with a single outlet. In contrast, if the circulation reactor operates with a combination of two outlet openings located at different places in the circulation reactor, that is, the first outlet and the second outlet, the polymerization of olefin monomers results in a separation of the flow between the circulation reactor and the gas phase reactor in a ratio of about 55/45. Accordingly, the circulation reactor provided with the first and second outlet openings according to the present invention allows the flow separation between the circulation reactor and the gas phase reactor to be shifted towards the circulation reactor.

Claims (15)

1. A method of producing an olefin polymer in at least one loop reactor, wherein said loop reactor comprises:
(a) at least one lower horizontal segment and / or at least one lower loop,
(b) at least one upper horizontal segment and / or at least one upper loop, and
(c) at least two vertical segments,
connected by working connection
the specified circulation reactor further includes:
(d) a first outlet for discharging the 1st polymer slurry from the loop reactor, said 1st polymer slurry comprising an olefin polymer and a liquid phase; the specified first outlet is located so that the 1st discharge of the polymer suspension had a polymer concentration of the same or higher than the average polymer concentration in the circulation reactor, and
(e) a second outlet for discharging the 2nd polymer slurry from the circulation reactor, said 2nd polymer slurry comprising an olefin polymer and a liquid phase; said 2nd outlet is positioned so that the 2nd dischargeable polymer slurry has a polymer concentration lower than the average polymer concentration in the circulation reactor,
the method includes the steps of:
(i) feeding the olefin monomers, catalyst system, and optionally olefin comonomers to the loop reactor to form a polymer slurry in the loop reactor; and
(ii) control
(ii1) the total amount of polymer discharged from the loop reactor,
and / or
(ii2) the total amount of polymer suspension discharged from the loop reactor,
and / or
(ii3) the concentration of the polymer in the total polymer slurry discharged from the circulation reactor by adjusting the ratio of the 1st polymer slurry discharged through the first outlet, and the 2nd polymer slurry discharged through the second outlet, the ratio of the 1st polymer slurry, discharged through the first outlet, and the 2nd polymer suspension discharged through the second outlet [PS-01 / PS-02] is at least 1.8, preferably at least 2.5,
Where
"PS-01" is the amount [given in mass percent] of the 1st polymer slurry discharged through the first outlet, and
“PS-02” is the amount [given in mass percent] of the 2nd polymer slurry discharged through the second outlet. 2. The method according to p. 1, where
(a) the 1st polymer suspension and the 2nd polymer suspension are discharged through the first and second outlet openings, respectively, and are sent directly to the second reactor, i.e. without washing,
or
(b) the 1st polymer suspension and the 2nd polymer suspension are combined and then transferred to a second reactor. 3. The method according to p. 1 or 2, where in addition to the second reactor, preferably a gas phase reactor, the resulting polymer is different from the polymer obtained in the circulation reactor, and the separation of the flow achieved between the circulation reactor and the second reactor, that is, the mass ratio of the polymer, obtained in the circulation reactor, and the polymer obtained in the second reactor is from 75:25 to 40:60. 4. The method according to any one of the preceding paragraphs, where the average concentration of the polymer in the polymer suspension in a circulation reactor is from 15 mass. % to 55 mass. %, preferably from 20 mass. % to 55 mass. % and more preferably from 25 mass. % to 52 mass. % of the total weight of the polymer suspension in a circulation reactor. 5. The method according to any one of the preceding paragraphs, where in the case of control from 65 mass. % to 95 mass. % of the total mass of the total discharged polymer suspension is the 1st polymer suspension discharged through the first outlet, and from 5 mass. % to 35 mass. % of the total weight of the total discharged polymer suspension is the 2nd polymer suspension discharged through the second outlet. 6. The method according to any one of the preceding paragraphs, where the 2nd polymer suspension discharged through the second outlet has a polymer content
(a) more than 0.1 mass. % and more preferably at least 0.5 mass. % of the total mass of the 2nd polymer suspension discharged through the second outlet, and / or
(b) a maximum of 10 mass. % and more preferably a maximum of 5 mass. % of the total mass of the 2nd polymer suspension discharged through the second outlet. 7. The method according to any one of the preceding paragraphs, where
(a) the 1st polymer suspension is discharged periodically or continuously through the first outlet
and
(b) the 2nd polymer suspension is discharged periodically or continuously through a second outlet. 8. The method according to any one of the preceding paragraphs, where the first outlet is located on the outer periphery of the circulation reactor and / or the second outlet is located on the inner periphery of the circulation reactor. 9. The method according to any one of the preceding paragraphs, where the circulation reactor includes:
(a) one lower horizontal segment,
(b) two lower loops,
(c) one upper horizontal segment,
(d) two upper loops and
(e) two vertical segments,
connected by a working connection, where two lower loops connect the lower horizontal segment to two vertical segments and two upper loops connect the upper horizontal segment to two vertical segments,
the first outlet is located on the outer periphery of the lower horizontal segment or is located on the outer periphery of one of the two lower loops of the circulation reactor, preferably the first outlet is located on the outer periphery of the lower horizontal segment,
and the second outlet is located on
(i) the inner periphery of the lower horizontal segment of the circulation reactor or the inner periphery of one of the two lower loops of the circulation reactor, preferably on the inner periphery of one of the two lower loops of the circulation reactor,
and / or
(ii) the inner periphery of the upper horizontal segment of the circulation reactor or the inner periphery of one of the two upper loops of the circulation reactor. 10. The method according to any one of the preceding claims 1 to 8, where the circulation reactor includes:
(a) one bottom loop,
(b) one upper loop and
(c) two vertical segments,
connected by a working connection, where the lower loop and the upper loop connect two vertical segments,
the first outlet is located on the outer periphery of the lower loop of the circulation reactor, and
the second outlet is located on
(i) the inner periphery of the lower loop of the circulation reactor, and / or
(ii) the inner periphery of the upper loop of the circulation reactor. 11. The method according to any one of the preceding paragraphs, where optional
(a) the first and second outlet openings are connected to the second reactor through a separate pipe
and / or
(b) the pipe of the first outlet and the pipe of the second outlet are connected to each other at the connection point above the second reactor through a production line and then the pipeline goes from the specified connection point to the second reactor. 12. A polymerization reactor system comprising a plurality of reactor vessels for producing olefin polymers, said polymerization reactor system includes in a cascade at least one loop reactor and at least one additional reactor, preferably a gas phase reactor,
where the specified circulation reactor includes:
(a) at least one lower horizontal segment and / or at least one lower loop,
(b) at least one upper horizontal segment and / or at least one upper loop, and
(c) at least two vertical segments connected by a working connection, said circulation reactor further includes first and second outlets suitable for discharging a polymer suspension,
said first and second outlet openings are connected to the second reactor by a pipe,
where additionally
the first outlet is located on the outer periphery of the lower horizontal segment or located on the outer periphery of the lower loop of the circulation reactor,
and
the second outlet is located on
(i) the inner periphery of the lower horizontal segment of the circulation reactor or the inner periphery of the lower loop of the circulation reactor,
and / or on
(ii) the inner periphery of the upper horizontal segment of the circulation reactor or the inner periphery of the upper loop of the circulation reactor. 13. The polymerization reactor system according to claim 12, where the pipeline of the first outlet and the pipe of the second outlet are connected to each other at the connection point above the second reactor via a production line and then the pipeline goes from the specified connection point to the second reactor. 14. A method for controlling the average aging time of an olefin polymer obtained in a loop reactor or in a loop reactor of a polymerization reactor system, said loop reactor comprising:
(a) at least one lower horizontal segment and / or at least one lower loop,
(b) at least one upper horizontal segment and / or at least one upper loop, and
(c) at least two vertical segments,
connected by working connection
the specified circulation reactor further includes:
(d) a first outlet for discharging the 1st polymer slurry from the loop reactor, said 1st polymer slurry comprising an olefin polymer and a liquid phase; said first outlet is positioned so that the first polymer suspension to be discharged has a polymer concentration equal to or higher than the average polymer concentration in the circulation reactor, and (e) the second outlet for discharging the second polymer suspension from the circulation reactor, The 2nd polymer suspension comprises an olefin polymer and a liquid phase; said 2nd outlet is positioned so that the 2nd dischargeable polymer slurry has a polymer concentration lower than the average polymer concentration in the circulation reactor,
the method includes the steps of:
(i) feeding the olefin monomers, catalyst system, and optionally olefin comonomers to the loop reactor to form a polymer slurry in the loop reactor; and
(ii) control
(ii1) the total amount of polymer discharged from the loop reactor, and / or
(ii2) the total amount of polymer suspension discharged from the loop reactor,
and / or
(ii3) polymer concentration in the total polymer suspension discharged from the loop reactor,
adjusting the ratio of the 1st polymer suspension discharged through the first outlet, and the 2nd polymer suspension discharged through the second outlet. 15. The use of a second outlet located on a circulation reactor and / or polymerization reactor system comprising a circulation reactor and a second reactor for monitoring
(1) the total amount of polymer discharged from the loop reactor, and / or
(2) the total amount of polymer suspension discharged from the loop reactor,
and / or
(3) polymer concentration in the total polymer suspension discharged from the loop reactor,
controlling the discharge of the liquid phase or the 2nd polymer suspension through the second outlet and optionally moving it to the second reactor,
said circulation reactor includes:
(a) at least one lower horizontal segment and / or at least one lower loop,
(b) at least one upper horizontal segment and / or at least one upper loop, and
(c) at least two vertical segments,
connected by working connection
said circulation reactor includes:
(d) a first outlet for discharging the 1st polymer slurry from the loop reactor, said 1st polymer slurry comprising an olefin polymer and a liquid phase; the specified first outlet is located so that the 1st discharge of the polymer suspension had a polymer concentration of the same or higher than the average polymer concentration in the circulation reactor, and
(e) a second outlet for discharging the 2nd polymer slurry from the circulation reactor, said 2nd polymer slurry comprising an olefin polymer and a liquid phase; said 2nd outlet is positioned so that the 2nd discharged polymer slurry has a polymer concentration lower than the average polymer concentration in the circulation reactor.