Catalyst Feeder and Processes Thereof

The present disclosure provides a catalyst feeder for a polymerization process that uses a solid catalyst. A catalyst feeder includes a housing, a plug disposed radially inside the housing and rotatable relative to the housing, and an end plate coupled to the housing. If the plug is in a first rotational position, each one of a first plurality of magnets coupled, to an axial end of the plug is axially aligned with one of a. second plurality of magnets coupled to a surface of the end plate facing towards the axial end of the plug, thereby moving the plug towards a first seated position in relation to the housing. If the plug is in a second rotational position, the plurality of first magnets and the plurality of second magnets are axially offset from each other, thereby moving the plug towards an unseated position in relation to the housing.

FIELD

The present disclosure relates to catalyst feeders for polymerization processes that use a solid catalyst.

BACKGROUND

Polymerization processes utilize solid catalysts to catalyze the polymerization reaction. Solid catalysts may be fed to a polymerization reactor using a catalyst feeder. A catalyst feeder is a device that provides a batch of solid catalyst (which may also be referred to as a “shot” or “drop”) to the polymerization reactor at controlled intervals. The feed rate of the solid catalyst may be measured in shots, or drops, per minute. An example catalyst feeder may have a housing and a rotatable plug disposed inside the housing. The plug may be filled with catalyst in a filling position and then rotated to a feeding position to feed the catalyst into the reactor. Another fluid may be used to flush the catalyst from the plug during feeding. The plug may be seated in the housing during filling and feeding. The plug may become unseated from the housing during rotation in order to displace or dislodge the flush fluid that is still contained within the plug so that additional catalyst may be loaded into the plug in the filling position.

A spring-loaded pin is used to reseat the plug with the housing at or near the end of plug rotation. However, both the spring and pin are susceptible to being jammed when solid catalyst enters the spring-loaded pin housing. This prevents the plug from reseating and causes failure of the catalyst feeder.

What is needed is a catalyst feeder with a reseating mechanism that is less susceptible to being jammed. There is a need for improved catalyst feeders for polymerization processes that use a solid catalyst.

Some references of particular interest in this regard include: US2012/0275931.

SUMMARY

In some embodiments, a catalyst feeder for a solid catalyst includes a housing. The catalyst feeder includes a plug disposed radially inside the housing and rotatable relative to the housing, the plug having a first plurality of magnets coupled to an axial end of the plug. The catalyst feeder includes an end plate coupled to the housing. The end plate has a second plurality of magnets coupled to a surface of the end plate facing towards the axial end of the plug. If the plug is in a first rotational position, each one of the first plurality of magnets is axially aligned with one of the second plurality of magnets, thereby applying a first magnetic force on the plug in a first axial direction towards a first seated position in relation to the housing. If the plug is in a second rotational position, the plurality of first magnets and the plurality of second magnets are axially offset from each other, thereby applying a second magnetic force on the plug in a second axial direction towards an unseated position in relation to the housing.

In some embodiments, a catalyst feeder for a solid catalyst includes a housing. The catalyst feeder includes a plug disposed radially inside the housing and rotatable relative to the housing. The plug has a first magnet coupled to an axial end of the plug. The first magnet is radially centered on the axial end. An end plate is coupled to the housing, and the end plate has a second magnet coupled to a surface of the end plate facing towards the axial end of the plug. The second magnet is axially aligned with the first magnet, thereby applying a magnetic force continuously on the plug in a first axial direction towards a seated position in relation to the housing.

In some embodiments, a process of using a catalyst feeder for forming a polymer includes positioning a plug in a first rotational position relative to a housing of the catalyst feeder, the catalyst feeder further including an end plate coupled to the housing. The process includes, when the plug is in the first rotational position, providing a first batch of solid catalyst to a first port of the plug. The process includes rotating the plug to a further rotational position relative to the housing. The process includes, when the plug is in the further rotational position, providing a fluid to the first port of the plug to flush the first batch of solid catalyst into a reactor coupled to the housing. The process includes, when the plug is in the further rotational position, providing a second batch of solid catalyst to a second port of the plug. The second port is offset in a circumferential direction from the first port. When the plug is in each of the first and further rotational positions, one or more magnets are coupled to an axial end of the plug and are axially aligned with one or more magnets coupled to a surface of the end plate facing the axial end of the plug to apply a first magnetic force on the plug in a first axial direction towards a first seated position in relation to the housing.

DETAILED DESCRIPTION

The present disclosure relates to catalyst feeders for polymerization processes that use a solid catalyst. In at least one embodiment, catalyst feeders of the present disclosure include a housing, a plug disposed radially inside the housing and rotatable relative to the housing, and an end plate coupled to the housing. If the plug is in a first rotational position, each one of a first plurality of magnets coupled to an axial end of the plug is axially aligned with one of a second plurality of magnets coupled to a surface of the end plate facing towards the axial end of the plug, thereby moving the plug towards a first seated position in relation to the housing. If the plug is in a second rotational position (which may also be referred to as an intermediate rotational position; or as an offset rotational position), the plurality of first magnets and the plurality of second magnets are axially offset from each other, thereby moving the plug towards an unseated position in relation to the housing.

A solid catalyst of the present disclosure may be a catalyst suspended in a solvent (e.g., catalyst suspended in an aliphatic solvent) or a solid catalyst can be a catalyst system (e.g., an activated catalyst). A “catalyst system” is a combination of at least one catalyst compound, at least one activator, an optional co-activator, and an optional support material. When “catalyst system” is used to describe such a composition before activation, it means the unactivated catalyst complex (precatalyst) together with an activator and, optionally, a co-activator. When it is used to describe such a pair after activation, it means the activated complex and the activator or other charge-balancing moiety The transition metal compound may be neutral as in a precatalyst, or a charged species with a counter ion as in an activated catalyst system. For the purposes of this present disclosure and the claims thereto, when catalyst systems are described as comprising neutral stable forms of the components, it is well understood by one of ordinary skill in the art, that the ionic form of the component is the form that reacts with the monomers to produce polymers. A polymerization catalyst system is a catalyst system that can polymerize monomers to polymer. Furthermore, catalyst compounds and activators represented by formulae herein embrace both neutral and ionic forms of the catalyst compounds and activators.

Further, a “catalyst compound” may be described as a catalyst precursor, a pre-catalyst compound, catalyst compound or a transition metal compound, and these terms are used interchangeably. A polymerization catalyst system is a catalyst system that can polymerize monomers to polymer. An “anionic ligand” is a negatively charged ligand which donates one or more pairs of electrons to a metal ion. A “neutral donor ligand” is a neutrally charged ligand which donates one or more pairs of electrons to a metal ion. Examples of neutral donor ligands include a neutral Lewis base, such as, for example, amines, alcohols, ethers, ketones, aldehydes, esters, sulfides or phosphines, which can be bonded with a metal center or can still be contained in the complex as residual solvent from the preparation of the metal complexes.

Activator and cocatalyst are also used interchangeably.

Polymerization Process System

FIG.1is a schematic diagram conceptually illustrating a system100used to perform a polymerization process, in accordance with various embodiments. Referring toFIG.1, the system100includes, from upstream to downstream, a catalyst reservoir102and a fluid source104, a catalyst feeder106coupled to the catalyst reservoir102and to the fluid source104, and a polymerization reactor108coupled to the catalyst feeder106. The catalyst reservoir102and the fluid source104are independently coupled to the catalyst feeder106, thereby providing two separate input branches to the catalyst feeder106. Therefore, the catalyst reservoir102and the fluid source104may be referred to as being “in parallel.” The catalyst reservoir102contains a solid catalyst for feeding to the polymerization reactor108. In some examples, the catalyst can be or include any suitable solid catalyst, such as a catalyst supported on a solid support (e.g., a silica support). Some examples of suitable catalysts are discussed below. In some embodiments, the catalyst reservoir102has a gas layer filling a void volume above the solid catalyst.

The fluid source104contains a fluid for flushing the solid catalyst from the catalyst feeder106. In some embodiments, the fluid source104applies a continuous or constant fluid pressure to the catalyst feeder106. In some embodiments, after the fluid is used to flush the solid catalyst from the catalyst feeder106, the flush fluid migrates up and into the catalyst reservoir102. In some examples, the flush fluid can be or include an alkane having from two to 10 carbon atoms, such as two carbon atoms (ethane), three carbon atoms (propane), four carbon atoms (e.g., butane), five carbon atoms (e.g., pentane), six carbon atoms (e.g., hexane), seven carbon atoms (e.g., heptane), eight carbon atoms (e.g., octane), nine carbon atoms (e.g., nonane), or 10 carbon atoms (e.g., decane). In some embodiments, the flush fluid is or includes isobutane, isoheptane, isohexane, other saturated hydrocarbon isomers, or combinations thereof.

As shown schematically inFIG.1, the catalyst feeder106includes a housing110having a catalyst inlet112coupled to the catalyst reservoir102, a flush inlet114coupled to the fluid source104, and a catalyst outlet116coupled to the polymerization reactor108. In some embodiments, the catalyst outlet116is rotated about 30° to about 150°, such as about 60° to about 120°, or about 30°, about 60°, about 90°, or about 120° from the catalyst inlet112. In other words, the catalyst inlet112and the catalyst outlet116are offset about a rotational axis of the catalyst feeder106by about 30° to about 150°, such as about 60° to about 120°, or about 30°, about 60°, about 90°, or about 120°. In some embodiments, the flush inlet114and the catalyst outlet116are aligned on the same axis as shown. In operation, solid catalyst from the catalyst reservoir102is added to the catalyst feeder106through the catalyst inlet112. Then, flush fluid from the fluid source104is added to the catalyst feeder106through the flush inlet114to push the solid catalyst out of the catalyst outlet116and into the polymerization reactor108. An example of a catalyst feeder106is described in more detail below.

In some examples, the polymerization reactor108can be or include a slurry reactor, a gas phase reactor, a loop reactor, a stirred-tank reactor, or combinations thereof The term “slurry reactor” may refer to a three-phase reactor design configured to hold solids suspended in a liquid phase through which a gas is bubbled. The term “gas phase reactor” may refer to a reactor design wherein gas-phase monomers react to form a solid polymer powder. A particular example of a gas-phase reactor is a fluidized bed gas phase reactor, in which the solid polymer powder forms on solid catalyst particles, wherein the solid polymer and catalyst particles are suspended in a fluidized bed via cycle gas (comprising monomer such as ethylene, optional comonomer, as well as optional gases such as nitrogen or other inert carrier gas, inert condensing agents (ICAs), and/or other gases as known in the art of fluidized bed gas phase polymerization). In some examples, the polymerization reactor108may be used to form any suitable polymer, such as polyethylene, polypropylene, and copolymers thereof.

As illustrated inFIG.1, a system (such as system100) can further include a system controller122to direct the operation of one or more components of system100. The system controller122as illustrated inFIG.1includes a programmable central processing unit (CPU)124which is operable with a memory126(e.g., non-volatile memory) and support circuits128. The support circuits128are conventionally coupled to the CPU124and include cache, clock circuits, input/output subsystems, power supplies, and the like, and combinations thereof coupled to the various components of the system100, to facilitate control thereof. The CPU124is one of any form of general purpose computer processor used in an industrial setting, such as a programmable logic controller (PLC), for controlling various components and sub-processors of the system100. The memory126, coupled to the CPU124, is non-transitory and is typically one or more of readily available memories such as random access memory (RAM), read only memory (ROM), floppy disk drive, hard disk, or any other form of digital storage, local or remote.

Typically, the memory126is in the form of a computer-readable storage medium containing instructions (e.g., non-volatile memory), which when executed by the CPU124, facilitates the operation of the system100. The instructions in the memory126are in the form of a program product such as a program that implements the methods of the present disclosure.

The program code can conform to any one of a number of different programming languages. In one example, the disclosure may be implemented as a program product stored on computer-readable storage media for use with a computer system. The program(s) of the program product define functions of the embodiments (including the methods described herein).

Illustrative computer-readable storage media include, but are not limited to: (i) non-writable storage media (e.g., read-only memory devices within a computer such as CD-ROM disks readable by a CD-ROM drive, flash memory, ROM chips or any type of solid-state non-volatile semiconductor memory) on which information is permanently stored; and (ii) writable storage media (e.g., floppy disks within a diskette drive or hard-disk drive or any type of solid-state random-access semiconductor memory) on which alterable information is stored. Such computer-readable storage media, when carrying computer-readable instructions that direct the functions of the methods described herein, are embodiments of the present disclosure. In some embodiments, the methods set forth herein, or portions thereof, are performed by one or more application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other types of hardware implementations. In some other embodiments, the polishing pad manufacturing methods set forth herein are performed by a combination of software routines, ASIC(s), FPGAs and, or, other types of hardware implementations.

The system controller122is configured to control temperatures, pressures, and flow rates within and between the catalyst reservoir102, the fluid source104, the catalyst feeder106, and the polymerization reactor108. In some embodiments, the instructions used by the system controller122to direct the operation of the system100include control of temperatures, pressures, and flow rates, among other process parameters, effectuated by actuators or other suitable control devices (not shown inFIG.1) communicatively coupled to the controller122so as to enable physical activation of the actuator or other control device. Such instruments for implementing control commands in a physical system are well known in the art of process controls and are not further discussed herein.

Exemplary Catalyst Feeder

FIG.2Ais a top isometric view of an example catalyst feeder206that may be used in the system100ofFIG.1, according to some embodiments. Referring toFIG.2A, the catalyst feeder206generally includes a housing210having a catalyst inlet212, a flush inlet214, and a catalyst outlet216. In some embodiments, the housing210is formed from a steel alloy, such as carbon steel. An actuator218is coupled to the housing210. A shaft220extends from the actuator218and into the housing210where the shaft220is coupled to a plug (shown inFIG.2B) inside the housing210. In some embodiments, the actuator218is a rotary actuator designed to rotate by a fixed angle, such as about 30° to about 150°, such as about 60° to about 120°, or about 30°, about 60°, about 90°, or about 120°. In some other embodiments, the actuator218is an electric motor with program stops set at uniform intervals, such as about 30° to about 150°, such as about 60° to about 120°, or about 30°, about 60°, about 90°, or about 120°. The system controller122controls the actuator218. In some embodiments, the instructions used by the system controller122to direct the operation of the actuator218include rotational positions, actuation rates, and actuation frequency or timing. In operation, the shaft220is rotated by the actuator218. Rotation of the shaft220causes the plug to rotate in relation to the housing210as described in more detail below.

FIGS.2B,2C, and2Dare side cross-sectional views of the catalyst feeder206ofFIG.2A, according to some embodiments. Note that the flush inlet214is oriented out of the page and towards the viewer, and therefore not shown, in the cross-sectional view ofFIGS.2B-2D. Also note that the catalyst outlet216is axially aligned with the flush inlet214and oriented into the page and away from the viewer in the cross-sectional view ofFIGS.2B,2C, and2D, and thus also not shown. Referring toFIG.2B, the catalyst feeder206generally includes a plug230, a liner250surrounding the plug230, and an end plate260coupled to the housing210.

The plug230is disposed radially inside the housing210and the liner250. The plug230has a first axial end232facing in a proximal direction in relation to the housing210. The first axial end232is coupled to the shaft220. The plug230may be rotated by the actuator218(e.g., via the actuator218rotating the shaft220, which in turn causes the coupled plug230to rotate). The plug230has a second axial end234facing in a distal direction in relation to the housing210. The second axial end234faces the end plate260. The plug230has an outer surface236connecting the first and second axial ends232,234. First and second ports238,240are disposed through the plug230, each in a generally transverse direction. As shown inFIGS.2B-2D, the first and second ports238,240are offset from each other in a circumferential direction by about 90° (that is, when viewed head-on in a direction along the shaft 220, and analogizing to a clock face, the first port238traverses 6-to-12 (vertical dissection of the clock face) and the second port240traverses 3-to-9 (horizontal dissection of the clock face)). However, in some embodiments, the first and second ports238,240can be offset one from the other by about 30° to about 150°, such as about 60° to about 120°, or about 30°, about 60°, about 90°, or about 120°. Openings in the outer surface236of the plug230corresponding to the first port238are aligned on the same transverse plane; and openings on the outer surface236of the plug230corresponding to the second port240are aligned on the same transverse plane. Openings in the outer surface236of the plug230corresponding to the first and second ports238,240are spaced in a circumferential direction to correspond to the spacing of the catalyst inlet212, the flush inlet214(referring back toFIG.2A), and the catalyst outlet216(also referring back toFIG.2A) in the housing210.

The plug230can be formed from a steel alloy, such as Nitralloy 135. The plug230also or instead can be coated with a nitride layer to resist damage that may occur due to the abrasiveness of the solid catalyst. Further, the plug230may optionally be nitrided to hardness Rockwell C 65.

The materials of construction of the liner250optionally can be the same as the plug230. For instance, the liner250can be formed from a steel alloy, such as Nitralloy 135; also or instead, the liner250can be coated with a nitride layer to resist damage that may occur due to the abrasiveness of the solid catalyst; and/or the liner250can be nitrided to hardness Rockwell C 65.

The end plate260encloses the plug230and the liner250inside the housing210. The end plate260has an axial surface262facing towards the second axial end234of the plug230. In some embodiments, the end plate260is formed from a steel alloy, such as ASTM A105 carbon steel.

In some embodiments, the plug230and the end plate260are each formed at least in part from a magnetic material, such as ferrous steel. In some other embodiments, one of the plug230or the end plate260is magnetic, whereas the other one is non-magnetic. In one example, the plug230is formed from ferrous steel and the end plate260is formed from stainless steel. In some other embodiments, both the plug230and the end plate260are non-magnetic.

One or both of the plug230and the end plate260can have a non-magnetic body with magnetic inserts disposed in the non-magnetic body. In such embodiments, the non-magnetic body may be formed from stainless steel, and the magnetic inserts may be formed from ferrous steel. The inserts enable control of magnetic forces on the plug230as described below independent of the material of the body. In further discussion of the embodiment illustrated inFIGS.2B,2C, and2D, it will be seen that magnetic inserts are employed—and in particular a first plurality of magnets242and second plurality of magnets264. In conjunction with these magnetic inserts, either or both of the plug230and end plate260can be magnetic or non-magnetic, as discussed in context below in connection withFIGS.2B-2Das well as in connection with methods discussed in connection withFIG.3.

The first plurality of magnets242(242a,242b,242c,and242d) is coupled to the second axial end234of the plug230. Magnets242aand242bare shown inFIG.2B(having a first rotational configuration of the plug with the pair of transverse ports238and240); magnets242cand242dare shown inFIG.2D(having a configuration 90° rotationally offset from the first configuration, with respect to the housing210, referred to in connection withFIG.2Das a third or further rotational position). The rotational configuration of the plug230in each ofFIGS.2B,2c,and2D are discussed in more detail below. Returning to the first plurality of magnets242, these magnets242enable control of seating and unseating of the plug230as described in more detail below. In some embodiments, the plug230includes two to eight magnets, such as two to four magnets, such as two magnets, three magnets, or four magnets, or five to eight magnets, such as five magnets, six magnets, seven magnets, or eight magnets. The number of magnets affects the degree of rotation between different rotational positions as described in more detail below. In the illustrated embodiments, the plug230includes four magnets.

The first plurality of magnets242are inset in the second axial end234of the plug230to avoid damage to the magnets that may occur due to contact with the end plate260. In some embodiments, adhesive (e.g., Loctite 620) can be used to couple the first plurality of magnets242to the plug230. The adhesive can have a compressive shear strength greater than 2,000 pounds per square inch (psi), such as about 2,500 psi, after 24 hours when measured at 76° F., according to ISO 10123. Also or instead, the adhesive may have a bonding strength about 1,000 pound-force (lbf) to about 2,500 lbf, such as about 2,000 lbf, for each magnet. In some examples, the adhesive may retain greater than 50% bonding strength up to 250° C., according to ISO 10123.

In some embodiments, the first plurality of magnets242are equally spaced from each other in a circumferential direction. In the illustrated embodiments, the first plurality of magnets242are offset from each other by about 90° (returning to analogy to a clock face, when viewed head-on along the axis of the shaft220, the first plurality of magnets are located at the 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock positions). More generally, the first plurality of magnets242may be spaced apart from each other, independently, by about 5° to about 180°, such as about 5°, about 30°, about 45°, about 60°, about 75°, about 90°, about 105°, about 120°, about 135°, about 150°, or about 180°, or about 30° to about 150°, such as about 45° to about 135°, such as about 60° to about 120°, such as about 75° to about 105°. In some embodiments, the magnets of the first plurality of magnets are spaced apart from each other uniformly in the circumferential direction (such that, of course, the degree of circumferential separation may vary depending upon the number of magnets employed in the first plurality of magnets). In the illustrated embodiments, the first plurality of magnets242are equally spaced in a radial direction from a center axis of the second axial end234of the plug230. In some embodiments, a radius of the first plurality of magnets242measured from the center axis as a fraction of a radius of the second axial end234is about 0.2 to about 0.9, such as about 0.5 to about 0.8, such as about 0.5, about 0.6, about 0.7, or about 0.8.

In some embodiments, the first plurality of magnets242are permanent magnets. The term “permanent magnet” refers to a material that produces a persistent magnetic field without the need for an external source of magnetism or electrical power. Permanent magnets may be formed from ferromagnetic materials and alloys including materials such as iron, nickel, cobalt, and/or rare-earth metals. In some embodiments, the first plurality of magnets242are formed from rare-earth metals, such as neodymium (e.g., neodymium iron boron (NdFeB), neodymium grade 52, etc.). In some embodiments, the first plurality of magnets242have a high resistance to demagnetization that may occur at high temperature, such as greater than 95% resistance to demagnetization at temperatures below about 176° F. In some other embodiments, the first plurality of magnets242are electromagnets. In some embodiments, an axial cross-section of each magnet of the first plurality of magnets242has a round shape or a square shape. In some embodiments, dimensions of the first plurality of magnets242are about 0.25 inches to about 0.75 inches, such as about 0.5 inches, independently, in diameter, length, width, and/or height. In some embodiments, a surface area of each magnet of the first plurality of magnets242is about 0.5 in2to about 1 in2, such as about 0.5 in2to about 0.75 in2, such as about 0.75 in2to about 1 in2, such as about 0.785 in2.

The liner250is disposed radially inside the housing210. Axial ends of the liner250are open. The liner250has an inner surface252facing the outer surface236of the plug230The liner250has openings corresponding to each of the catalyst inlet212, the flush inlet214, and the catalyst outlet216. In the description that follows, the position and sealing of the plug230during seating and unseating is described with respect to the liner250. However, in some examples, the liner250may be omitted. Therefore, for purposes of describing the position and sealing of the plug230with respect to other components of the catalyst feeder206, the housing210and liner250may be used interchangeably without further recitation.

The second plurality of magnets264(264a,264b) is coupled to the axial surface262of the end plate260The second plurality of magnets264enables control of seating and unseating of the plug230as described in more detail below. Although only first and second magnets264a-264bare illustrated in the cross-sectional view ofFIGS.2B-2D, the end plate260includes four magnets. The second plurality of magnets264are spaced apart the same as the first plurality of magnets242. The polarity of the second plurality of magnets264is the same as the polarity of the first plurality of magnets242such that alignment between opposing magnets on the plug230and the end plate260causes the opposing magnets to be repelled. Aspects described herein in relation to the first plurality of magnets242may apply to the second plurality of magnets264without further recitation.

As shown inFIG.2B, the plug230is in a first rotational position in relation to the housing210. When the plug230is in the first rotational position, the first port238is aligned with the catalyst inlet212, and the second port240is aligned with each of the flush inlet214and the catalyst outlet216. In the first rotational position, the plug230is disposed in a first seated position in relation to the liner250. In the first seated position, the plug230is positioned fully in the proximal direction in relation to the housing210. In the first seated position, the plug230is spaced fully away from the end plate260. In some embodiments, axial spacing between the second axial end234of the plug230and the axial surface262of the end plate260is about 90 mil (2.286 mm) to about 100 mil (2.54 mm) in the first seated position. In the first seated position, the outer surface236of the plug230contacts the inner surface252of the liner250. In the first seated position, the plug230is sealed with the liner250through the contacting surfaces.

When the plug230is in the first rotational position, each magnet of the first plurality of magnets242of the plug230is axially aligned with a corresponding magnet of the second plurality of magnets264of the end plate260. As shown inFIG.2B, the pair of first magnets242a,264aare aligned, and the pair of second magnets242b,264bare aligned When the magnets of the first and second plurality of magnets242,264are aligned, a first magnetic force is applied on the plug230in a first axial direction towards the first seated position in relation to the liner250. That is, since the magnets242and264are of the same polarity, they repel each other (the first magnetic force is a repulsive magnetic force), maintaining the plug230axially spaced from the end plate260, as shown inFIG.2B. In some embodiments, based on example separation distances described herein, the first magnetic force is greater than about 5 lb per magnet pair, such as about 5 lb to about 20 lb, or greater than about 10 lb, such as about 10 lb to about 20 lb, or greater than about 15 lb, such as about 15 lb to about 20 lb, such as about 16 lb per magnet pair.

As shown inFIG.2C, the plug230is in a second rotational position (which may be referred to as an intermediate rotational position or an offset rotational position) in relation to the housing210. The second rotational position is between the first rotational position (shown inFIG.2B) and a third rotational position (shown inFIG.2D). Between the first rotational position to the second rotational position, the plug230is rotated by about 15° to about 75°, such as about 30° to about 60°, such as about 30°, about 45°, or about 60°. For example, as shown inFIG.2C, the plug230is rotated 45° from the first rotational position. When the plug230is in the second rotational position, the first and second ports238,240are not aligned with the catalyst inlet212, the flush inlet214, or the catalyst outlet216. In the second rotational position, the plug230is disposed in an unseated position in relation to the housing210. In the unseated position, the plug230is positioned fully in the distal direction in relation to the housing210. In the unseated position, the plug230is positioned fully towards the end plate260such that the second axial end234of the plug230is in contact with a bumper266extending from the axial surface262of the end plate260in the proximal direction in relation to the housing210. The bumper266prevents the second axial end234of the plug230from directly contacting the axial surface262of the end plate260to prevent stiction therebetween. In some embodiments, axial spacing between the second axial end234of the plug230and the axial surface262of the end plate260is less than about 10 mil (0.254 mm) in the unseated position. In the unseated position, the plug230is no longer sealed with the liner250.

When the plug230is in the second rotational position, the plurality of first magnets242and the plurality of second magnets264are axially offset from each other. When the magnets25of the first and second plurality of magnets242.264are not aligned, a second magnetic force is applied on the plug230in a second axial direction towards the unseated position in relation to the liner250. The second magnetic force is an attractive force between the first plurality of magnets242and the end plate260and/or the second plurality of magnets264and the plug230. In some embodiments, based on example separation distances described herein, the second magnetic force is greater than about 5 lb per magnet, such as about 5 lb to about 20 lb, or greater than about 10 lb, such as about 10 lb to about 20 lb, or greater than about 15 lb, such as about 15 lb to about 20 lb, such as about 18 lb per magnet. When the plug230and the end plate260are both non-magnetic, the magnetic flux resulting from the first and second plurality of magnets242,264applies zero magnetic force on the plug230.

As shown inFIG.2D, the plug230is in a third rotational position (which may also be referred to as a further rotational position) in relation to the housing210. In embodiments in accordance withFIGS.2A-2D, in the third rotational position shown inFIG.2D, the plug230is rotated 90° from the first rotational position (shown inFIG.2B). When the plug230is in the third rotational position, the first port238is aligned with each of the flush inlet214and the catalyst outlet216, and the second port240is aligned with the catalyst inlet212. In the third rotational position, the plug230is disposed in a second seated position in relation to the housing210. In the second seated position, the plug230is positioned fully in the proximal direction in relation to the housing210. In the second seated position, the plug230is spaced fully away from the end plate260. In the second seated position, the outer surface236of the plug230contacts the inner surface252of the liner250. In the second seated position, the plug230is sealed with the liner250through the contacting surfaces.

When the plug230is in the third rotational position, each magnet of the first plurality of magnets242of the plug230is axially aligned with a corresponding magnet of the second plurality of magnets264of the end plate260. As shown inFIG.2D, the third and fourth magnets242cand242dof the plug230are aligned with the first and second magnets264aand264b, respectively, of the end plate260. When the magnets of the first and second plurality of magnets242,264are aligned, or realigned in this case, the first magnetic force is again applied on the plug230in the first axial direction towards the second seated position in relation to the liner250.

Axial movement of the plug between the seated and unseated positions as described above can be controlled based on one or more properties of the first and second plurality of magnets242,264such as magnetic strength, spacing, cross-sectional shape, cross-sectional area, or combinations thereof. Improved magnetic control of axial movement of the plug230can enable a reduction in the continuous or constant fluid pressure applied by the fluid source104. This improved magnetic control of axial movement of the plug230can also enable catalyst to be fed from the catalyst feeder206at or near a continuous rate. The term “continuous” may refer to a system that operates without interruption or cessation.

Exemplary Method of Use

FIG.3is a diagram illustrating a process300of using a catalyst feeder for forming a polymer, according to some embodiments. The process300is described below using the catalyst feeder206ofFIGS.2A-2Dfor illustrative purposes only. The process300may be implemented using any suitable catalyst feeder.

At operation302, the plug230is positioned in the first rotational position (shown inFIG.2B). In the first rotational position, the plug230is in the first seated position as described above.

At operation304, when the plug230is in the first rotational position, a first batch of solid catalyst is provided to the first port238of the plug230. In addition, in the first rotational position, a first volume of flush fluid is provided to the second port240of the plug230.

At operation306, the plug230is rotated to a second rotational position (shown inFIG.2C). During rotation to the second rotational position, the plug230is moved towards the unseated position. In some examples, the plug230may move an axial distance of about 80 mil (0.080 inches, or 2.032 mm) to about 100 mil (0.100 inches, or 2.54 mm) between the seated and unseated positions. Unseating of the plug230during rotation is able to displace or dislodge the first volume of flush fluid contained in the second port240. Movement of the plug230to the unseated position may be caused by magnetic attraction between the first plurality of magnets242and the end plate260, magnetic attraction between the second plurality of magnets264and the plug230, and/or excess pressure applied by the flush fluid between the contacting surfaces of the plug230and the liner250. When the plug230and the end plate260are both non-magnetic, the first and second plurality of magnets242,264are unable to induce the magnetic attraction forces and movement of the plug230to the unseated position is caused by excess pressure alone.

At operation308, the plug230is rotated to the third rotational position (shown inFIG.2D). During or after rotation to the third rotational position, the plug230is moved towards the second seated position. Movement of the plug230to the second seated position is caused by alignment of, and the resulting magnetic repulsion between, the first and second plurality of magnets242,264.

At operation310, when the plug230is in the third rotational position as shown inFIG.2D, a second volume of flush fluid is provided to the first port238to push the first batch of solid catalyst out of the first port238(delivered at operation304, that is, when the plug230was in the first rotational position as shown inFIG.2B). In some embodiments, the first batch of solid catalyst is fed directly to a polymerization reactor coupled to the housing210. When the plug230is in the third rotational position, a second batch of solid catalyst is provided to the second port240. Then, as the plug230rotates back to the first rotational position, a third volume of flush fluid is provided to the second port240, thereby pushing the second batch of solid catalyst out of the second port240. The process can repeat continuously through ongoing rotation of the plug230.

For instance, the process300can be repeated to feed a batch of catalyst through the catalyst feeder206at preset rotational positions of the plug230. In certain embodiments, the rotational positions are set at about 30° to about 150°, such as about 60° to about 120°, or about 30°, about 60°, about 90°, or about 120°. The term “batch” refers to a volume of solid catalyst that fills the first port238at operation304when the plug230is in the first rotational position, and is subsequently removed from the first port238(e.g., via flush fluid provided when the plug230is in the third rotational position, at operation310); and/or the term “batch” can refer to the volume of solid catalyst that fills the second port240, e.g., at operation308, and is subsequently removed from the second port240, e.g., via flush fluid provided to the second port240upon return of the plug230to the first rotational position. In some embodiments, the process300is used to feed two to six batches of catalyst per minute, such as two, three, four, five, or six batches per minute.

Alternative Catalyst Feeder

FIG.4is a side cross-sectional view of another example catalyst feeder406that may be used in the system100ofFIG.1, according to some embodiments. Aspects of the catalyst feeder406that are not specifically described below are the same as corresponding aspects of the catalyst feeder206.

As shown inFIG.4, the plug230and the end plate260each have only a single magnet, in contrast the first and second plurality of magnets shown inFIGS.2B-2D. A first magnet442is coupled to the second axial end234of the plug230. The first magnet442is radially centered on the second axial end234. A second magnet464is coupled to the axial surface262of the end plate260. The second magnet464is radially centered on the axial surface262. Because each of the first and second magnets442,464are radially centered, axial alignment between the first and second magnets442,464is maintained continuously throughout rotation of the plug230. The polarity of the second magnet464is the same as the polarity of the first magnet442such that the first and second magnets442,464are repelled from each other. The result is a magnetic force being applied continuously on the plug230in the first axial direction towards a seated position in relation to the liner250. In some embodiments, such as when using permanent magnets that are in axial alignment, the magnetic force has a constant value.

Because the magnetic repulsion force is applied continuously to the plug230, movement of the plug230to the unseated position occurs only when pressure applied to the plug230by the flush fluid in the second axial direction exceeds the level of the magnetic repulsion force in the first axial direction. In operation, a first pressure less than the magnetic repulsion force is applied to the plug230by the flush fluid in each of the first and third rotational positions. A second pressure greater than the first pressure is applied to the plug230by the flush fluid during rotation (e.g., in the second rotational position between the first and third rotational positions). The first and second pressures are applied to the plug230over the same cross-sectional area. The magnetic strength and spacing of the first and second magnets442,464are selected such that the force exerted by the second pressure exceeds the level of the magnetic repulsion force, thereby moving the plug230to the unseated position, whereas the force exerted by the first pressure is inadequate to unseat the plug230. Therefore, the first and second magnets442,464are configured to provide a force to reseat the plug230in relation to the liner250in each of the first and third rotational positions as described above.

It will be appreciated that also or instead, any magnet described herein could be an electromagnet, e.g., such that current can be selectively applied to either or all such magnets in order to selectively activate a magnetic field at such magnet(s). In this way, the electromagnet(s) could be activated to cause a repulsive magnetic force when desired to move the plug230into the seated position (e.g., by causing repulsive force between magnets442and464in the feeder406; and/or between first plurality of magnets242and second plurality of magnets264in the feeder206), and/or selectively activated to cause an attractive magnetic force between such magnet pairs, causing the plug230to move into the unseated position.

Catalyst Compounds

A feeder in accordance with any embodiment described herein is suitable for feeding a variety of polymerization catalysts suitable for use in a slurry reactor, a gas phase reactor, a loop reactor, a stirred-tank reactor, or combinations thereof. Such catalysts include, without limitation, a catalyst compound having a metal atom, such as a Group 3 through Group 12 transition metal (e.g., Ziegler-Natta catalysts and/or metallocene catalysts, chromium catalysts, and the like). Chromium or Chromium-based catalysts are a particular example (e.g., for use in connection with slurry and/or gas phase fluidized bed polymerization processes). Chromium-based catalysts include chromium oxide (CrO3) and silylchromate catalysts. Such catalysts and polymerization processes have been described, for example, in U.S. Patent Application Publication No. 2011/0010938 and U.S. Pat. Nos. 7,915,357, 8,129,484, 7,202,313, 6,833,417, 6,841,630, 6,989,344, 7,504,463, 7,563,851, 8,420,754, and 8,101,691.

Metallocene catalyst compounds as used herein include bridged and unbridged metallocene compounds with ligands such as substituted or unsubstituted cyclopentadienyl moieties (including those substituted with ring structures such that the ligand has multiple rings as in the case of indenyl and/or fluorenyl moieties). The literature is replete with examples of metallocene catalysts for polymerization, including, e.g., U.S. Pat. Nos. 5,516,848 and 8,088,867; as well as WO2016/171810; and see generally the patents and publications collected in Paragraph [0020] of US2019/0040168.

Other suitable catalyst compounds include iron complexes, such as those also described in US2019/0040168, e.g., per Paragraph [0023] thereof.

Further, combinations of any of the foregoing, and/or multiples of the same class of catalyst (e.g., multiple metallocene catalysts) can be used in connection with feeders in accordance with the present description. The catalysts can be supported or unsupported (e.g., as described in the various references already mentioned, and in particular regarding supports as described in Paragraphs [0080] to [0095] of US2019/0040168); and optionally can include activators and/or co-catalysts (e.g., alkylalumoxanes) as is also known in the art of polymerization. In this regard, see, for example, U.S. Pat. Nos. 5,041,584; 9,340,630; 8,404,880; 8,975,209; 5,942,459; 8,658,556; 6,211,105; 5,153,157; 5,453,410; as well as WO 98/43983; EP 0 573 120 B1; WO 94/07928; and WO 95/14044.

Polymerization Processes

The present disclosure relates to polymerization processes where monomer (such as ethylene), and optionally comonomer, are contacted with a catalyst system comprising an activator and at least one catalyst compound, as described above. The catalyst compound and activator may be combined in any order, and are combined prior to contacting with the monomer.

As also noted previously, polymerization processes of the present disclosure can be carried out in any suitable manner. Any suitable suspension, homogeneous, bulk, solution, slurry, or gas phase polymerization process can be used. Such processes can be run in a batch, semi-batch, or continuous mode. Homogeneous polymerization processes and slurry processes can be used. As used herein, the term “slurry polymerization process” means a polymerization process where a supported catalyst is employed and monomers are polymerized on the supported catalyst particles in a diluent/solvent. At least 95 wt % of polymer products derived from the supported catalyst are in granular form as solid particles (not dissolved in the diluent).

Suitable diluents/solvents for polymerization include non-coordinating, inert liquids. Examples include straight and branched-chain hydrocarbons, such as isobutane, butane, pentane, isopentane, hexanes, isohexane, heptane, octane, dodecane, and mixtures thereof; cyclic and alicyclic hydrocarbons, such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof, such as can be found commercially (Isopar™); perhalogenated hydrocarbons, such as perfluorinated C4-10alkanes, chlorobenzene, and aromatic and alkylsubstituted aromatic compounds, such as benzene, toluene, mesitylene, and xylene. Suitable solvents also include liquid olefins which may act as monomers or comonomers including ethylene, propylene, 1-butene, 1-hexene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-octene, 1-decene, and mixtures thereof. In at least one embodiment, aliphatic hydrocarbon solvents are used as the solvent, such as isobutane, butane, pentane, isopentane, hexanes, isohexane, heptane, octane, dodecane, and mixtures thereof; cyclic and alicyclic hydrocarbons, such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane, and mixtures thereof. In another embodiment, the solvent is not aromatic, such as aromatics are present in the solvent at less than 1 wt %, such as less than 0.5 wt %, such as less than 0 wt % based upon the weight of the solvents.

Polyolefin Products

The present disclosure also relates to polyolefin compositions, such as resins, produced by the catalyst systems of the present disclosure. Polyolefins of the present disclosure can have no detectable aromatic solvent.

In at least one embodiment, a process includes utilizing a catalyst system of the present disclosure to produce propylene homopolymers or propylene copolymers, such as propylene-ethylene and/or propylene-alphaolefin (such as C3to C20) copolymers (such as propylene-hexene copolymers or propylene-octene copolymers) having an Mw/Mn of greater than about 1, such as greater than about 2, such as greater than about 3, such as greater than about 4.

In at least one embodiment, a process includes utilizing a catalyst system of the present disclosure to produce olefin polymers, such as polyethylene and polypropylene homopolymers and copolymers. In at least one embodiment, the polymers produced herein are homopolymers of ethylene or copolymers of ethylene, for example, having from about 0 and 25 mole % of one or more C3to C20olefin comonomer (such as from about 0.5 and 20 mole %, such as from about 1 to about 15 mole %, such as from about 3 to about 10 mole %). Olefin comonomers may be C3to C12alpha-olefins, such as one or more of propylene, butene, hexene, octene, decene, or dodecene, such as propylene, butene, hexene, or octene. Olefin monomers may be one or more of ethylene or C4to C12alpha-olefin, such as ethylene, butene, hexene, octene, decene, or dodecene, such as ethylene, butene, hexene, or octene.

Overall, the present disclosure provides catalyst feeders that have a reseating mechanism that is less susceptible to being jammed and that provides improved magnetic control of plug axial movement, as compared to conventional catalyst feeders.

The phrases, unless otherwise specified, “consists essentially of” and “consisting essentially of” do not exclude the presence of other steps, elements, or materials, whether or not, specifically mentioned in this specification, so long as such steps, elements, or materials, do not affect the basic and novel characteristics of the present disclosure, additionally, they do not exclude impurities and variances normally associated with the elements and materials used.