Gas phase fluidized bed reactor product discharge system

Abstract

An apparatus can include: a reactor comprising: a distributor plate; a reactor neck; a reactor straight section having a height H defined from the distributor plate to the reactor neck; a liquid arranged above the distributor plate and having a liquid height; and a fluidized bed comprising electrically insulating particles; and a product offloading line fluidically connected to the reactor and a product discharge tank, wherein the product offloading line is configured to discharge the electrically insulating particles to the product discharge tank, and wherein the product offloading line is positioned on the reactor straight section at a height ranging from greater than 5% to about 95% of the height H.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of U.S. Provisional Application 63 / 601,431, filed November 21, 2023, entitled “Product Discharge System for Gas Phase Fluidized Bed Reactor,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the gas-phase production of polyolefins. In particular, this disclosure relates to a method for discharging polymer resin products from a fluidized bed reactor. Background Technology

[0004] Polyolefins can be produced using gas-phase polymerization methods. If the method is a gas-phase fluidized bed polymerization method, it may include continuously passing a gaseous stream containing one or more monomers through a fluidized bed of catalyst and grown polymer particles. During polymerization, a portion of the monomers is consumed, and the gaseous stream is heated by the heat of polymerization in the reactor. A portion of the gaseous stream exits the reactor and may be recycled back to the reactor along with additional monomers and additives. At certain intervals in this method, when polyolefin particles have formed in the reactor, they must be removed or vented to maintain a workable bed level and to obtain the desired commercial product. This is preferably done in a cyclic manner, where several batches of particles are vented at a time. Because typical gas-phase reactors operate under pressurized conditions, such as 250, 290, 320, 350 psig or higher, the method of venting the particles must be carried out by transferring the particles to a low-pressure environment for processing into a commercial product. This is a cyclic process involving several steps, some of which may create bottlenecks during the venting process.

[0005] For example, shutdowns or changeovers in gas-phase polymerization reactors can be caused by the buildup of catalyst and polymer on the reactor walls, a phenomenon known as "flaking" and "caking." Another common problem is the buildup of catalyst and polymer on internal distribution plates, injection nozzles (one or more), and / or product discharge nozzles (one or more), a phenomenon known as "clogging" or "plate fouling." Flaking, agglomeration, fouling, and clogging can force a complete reactor shutdown for cleaning and removal of polymer clumps, which can take several days. Various mechanisms have been proposed to explain these phenomena, including electrostatic charge on particles within the reactor, high-temperature zones in the reactor that lead to excessive polymer viscosity, and solids carryover in the recirculated feed stream.

[0006] Some references that may be of interest in this regard include: U.S. Patent Nos. 9,360,453; 8,441,250; 7,985,811; 7,799,876; 7,774,178; 7,634,937; 6,831,140; and 5,462,999; and WO2009 / 014682 and WO222 / 109518. Summary of the Invention Invention Overview

[0008] The system and method for gas-phase polymerization are believed to offer numerous advantages, including reduced flocculing and / or other fouling. This document discloses an exemplary reactor system comprising: a reactor including an adistributor plate; a reactor neck; a reactor straight section having a height H defined from the adistributor plate to the reactor neck; a liquid disposed above the adistributor plate and having a liquid height; and a fluidized bed containing electrically insulating particles; and a product unloading line fluidly connected to the reactor and a product discharge tank, wherein the product unloading line is configured to discharge the electrically insulating particles into the product discharge tank, and wherein the product unloading line is disposed on the reactor straight section at a height corresponding to approximately 5% to approximately 95% of the height H.

[0009] This document further discloses a method comprising: introducing a feed stream containing monomers into a reactor, the reactor comprising: a distributor plate; a reactor neck; a reactor straight section having a height H defined from the distributor plate to the reactor neck; a liquid disposed above the distributor plate and having a liquid height; and a fluidized bed containing electrically insulating particles; polymerizing at least a portion of the monomers to produce additional electrically insulating particles; and extracting a product stream containing at least a portion of the electrically insulating particles from the reactor to a product discharge tank, wherein the product stream is extracted via a product unloading line fluidly connected to the reactor and the product discharge tank, and wherein the product unloading line is disposed on the reactor straight section at a height corresponding to about 5% to about 95% of the height H.

[0010] These and other features and properties of the devices and methods disclosed in this disclosure, as well as their advantageous applications and / or uses, will become apparent from the detailed description below. Brief description of the attached diagram

[0012] To assist those skilled in the art in making and using the subject matter herein, reference is made to the accompanying drawings, in which:

[0013] Figure 1 A schematic diagram of an illustrative gas-phase polymerization system according to certain embodiments of the present disclosure is depicted.

[0014] Figure 2 A schematic diagram of an illustrative gas-phase polymerization system according to certain embodiments of the present disclosure is depicted.

[0015] Figure 3A An exemplary gas-phase polymerization system for preparing polymers, having an improved product emission system according to one or more embodiments, is described.

[0016] Figure 3B An exemplary gas-phase polymerization system for preparing polymers, having an improved product emission system according to one or more embodiments, is described.

[0017] Figure 3C An exemplary gas-phase polymerization system for preparing polymers, having an improved product emission system according to one or more embodiments, is described.

[0018] Figure 4 It is a time-to-emission location diagram for simulating a gas-phase polyethylene reactor according to one or more embodiments.

[0019] Figure 5 It is a time-to-emission location diagram for simulating a gas-phase polyethylene reactor according to one or more embodiments. Invention Details

[0021] This document discloses a gas-phase production method for polyolefins. In particular, this disclosure relates to a method for discharging polymer resin products from a fluidized bed reactor during polyethylene production.

[0022] The words and phrases used herein should be understood and interpreted as having meanings consistent with those understood by one of skill in the art. The consistent use of terms or phrases herein is not intended to imply a specific definition of a term or phrase, i.e., a definition different from the common and conventional meaning understood by one of skill in the art. Where a term or phrase is intended to have a specific meaning (i.e., a meaning beyond the broadest meaning understood by one of skill in the art), such a specific or clarifying definition will be explicitly stated in the specification by way of definition, which provides a specific or clarifying definition for the term or phrase.

[0023] For example, the following discussion contains a non-exhaustive list of definitions for several specific terms used in this disclosure (other terms may be defined or clarified elsewhere herein). These definitions are intended to clarify the meaning of the terms used herein. It is believed that these terms are used in a manner consistent with their ordinary meaning, but definitions are still specified herein for clarity.

[0024] When used herein and unless otherwise specified, the term "Cn" refers to a hydrocarbon (one or more) containing n carbon atoms (one or more) per molecule, where n is a positive integer.

[0025] The indefinite articles “a” or “an” used herein shall mean “at least one” unless otherwise specified or the context clearly indicates otherwise. Thus, embodiments using “α-olefin” include embodiments in which one, two or more α-olefins are used, unless otherwise stated or the context clearly indicates that only one α-olefin is used.

[0026] As used herein, “wt%” means weight percentage, “volume%” means volume percentage, “mol%” means molar percentage, “ppm” means parts per million, and “ppm wt” and “wppm” are used interchangeably and mean parts per million by weight. Unless otherwise stated, all concentrations are expressed based on the total amount of the composition under discussion.

[0027] "Olefin," or "olefinic hydrocarbon," is a linear, branched, or cyclic compound of carbon and hydrogen having at least one double bond. For the purposes of this specification and the appended claims, when a polymer or copolymer is referred to as "containing" an olefin, the olefin present in such polymer or copolymer is the polymeric form of said olefin. For example, when a copolymer is described as having an "ethylene" content of 35% to 55% by weight, it should be understood that the matrix units in said copolymer are derived from ethylene in the polymerization reaction and that said derived units are present at 35% to 55% by weight, based on the weight of said copolymer.

[0028] As used herein, "polyethylene" refers to ethylene homopolymer or copolymer containing at least 86% by weight of ethylene. Unless otherwise stated, the terms "polyethylene polymer," "polyethylene," "ethylene polymer," "ethylene copolymer," and "vinyl polymer" have the same meaning as polyethylene copolymer (e.g., in the case of reference to polyethylene homopolymer, this refers to a polymer formed from ethylene monomers that do not contain comonomer units, such as 100% by weight of ethylene-derived units).

[0029] "Polyethylene grade" refers to discrete polyethylene products with a consistent set of properties, produced using specific catalysts and a unique set of polymerization conditions. As used herein, "polyethylene grade plate" refers to a discrete number of polyethylene products produced in a selected polymerization reaction zone, each possessing a consistent set of properties and produced using specific catalysts and a unique set of polymerization conditions.

[0030] A "polymer" is a polymer having two or more identical or different repeating units / monomer units or simple units. A "homopolymer" is a polymer having identical units. A "copolymer" is a polymer having two or more different units. A "terpolymer" is a polymer having three different units. The term "different" used to refer to units indicates that the units differ from each other by at least one atom or are isomerically different. The definition of copolymer as used herein includes terpolymers and the like. Similarly, the definition of polymer as used herein includes homopolymers, copolymers, and the like. Furthermore, the terms "polyethylene copolymer," "ethylene copolymer," and "vinyl polymer" are used interchangeably to refer to copolymers comprising at least 50 mol% units derived from ethylene.

[0031] As used herein, “polymerization conditions” refers to conditions that are favorable to the reaction of one or more olefin monomers when they are contacted with an activated olefin polymerization catalyst to produce a polyolefin polymer, including the selection of temperature, pressure, reactant concentration, optional solvent / diluent, reactant mixing / addition parameters, and other conditions within at least one polymerization reactor by a person skilled in the art.

[0032] The nomenclature of elements and their groups used in this paper follows the new notation published in HAWLEYS CONDENSED CHEMICALDICTIONARY, 13th edition, John Wiley & Sons, Inc., (1997) (reproduced therewith with permission from IUPAC), unless reference is made to the previous IUPAC form in Roman numerals (which also appears there), or unless otherwise stated.

[0033] The term "operating temperature (T)" used in this article refers to... op ")" refers to the target operating temperature in the polymerization zone of the gas-phase reactor for producing the desired grade of polyethylene. Operating temperature (T) op The operating temperature (T) is the target reactor temperature within the polymerization condition group related to the desired polyethylene grade. op )Comparison with shutdown temperature (T) k Low threshold quantity. Operating temperature (T) op This is to control the polymerization reaction to prevent the shutdown temperature (T) from being reached. k The threshold value can vary based on one or more of the polyethylene grade, specific reactor configuration, and / or the operator's preference for a particular reactor. In some embodiments, the threshold value is 14. o F (7.8℃), 15 o F (8.3℃), 16 o F (8.9℃) or 17 o F (9.4℃).

[0034] As used herein, “polymerization conditions” refers to conditions that are favorable to the reaction of one or more olefin monomers when they are contacted with an activated olefin polymerization catalyst to produce a polyolefin polymer, including the selection of temperature, pressure, reactant concentration, optional solvent / diluent, reactant mixing / addition parameters, and other conditions within at least one polymerization reactor by a person skilled in the art.

[0035] As used in this article, "reactor system" refers to reactors, pipes, and equipment containing circulating fluid loops, including but not limited to circulating fluid heat exchangers.

[0036] As used herein, "agglomeration" refers to the agglomeration of adjacent polymer particles, where such agglomeration forms polymer clumps within the polymerization zone of the reactor. Agglomeration occurs when one or more sections of the reactor lose effective fluidization or mixing. Insufficient mixing reduces the rate of heat removal from these sections. With reduced heat removal in these sections and the continued reaction, superheating of the polymer can occur. This superheating can cause agglomeration or melting or agglomeration of the polymer material, resulting in the formation of solid matter, or polymer clumps. In some cases (e.g., as described by DeChellis in U.S. Patent No. 5,352,749), fluidization and mixing may disappear throughout the fluidized bed, resulting in large clumps that essentially contain all of the reactor contents.

[0037] As used herein, "scaling" refers to the agglomeration of adjacent polymer particles, where such agglomeration forms resin deposits in orifices, pipes, and / or piping that restrict flow in a reactor system. Distributor plate scaling is one of the leading causes of downtime in commercial fluidized bed polymerization reactor systems. Scaling is generally caused by the deposition of polymer resin in the numerous small orifices of the distributor plate, leading to reduced fluid flow or complete blockage. Good mixing in the fluidized bed is required for uniform temperature control. As the orifices in the distributor plate become partially or completely blocked, the ability of circulating gas to enter the fluidized bed to remove heat from the reactants is reduced. Furthermore, "hot spots" can form in low fluid velocity regions of the fluidized bed (particularly those immediately above partially or completely blocked orifices), leading to agglomeration. Scaling can also occur in circulation lines and / or circulating fluid exchangers.

[0038] As used in this article, "lamping" refers to the agglomeration of adjacent polymer particles, where such agglomeration forms polymer sheets. During lamination, sticky particles aggregate on the surfaces of a reactor system, such as the walls and / or dome of a reactor vessel, forming sheets of polymer particles. Progressive circulation in this process can eventually lead to the growth of these sheets and their fall into the fluidized bed. These sheets can disrupt fluidization, gas circulation, and product extraction from the reactor, and may necessitate reactor shutdown for removal.

[0039] Aggregation methods

[0040] Figure 1 An illustrative gas-phase polymerization system 100 for preparing polymers according to one or more embodiments is depicted. The polymerization system 100 may include a reactor 101 in fluid communication with one or more discharge tanks 155, compressors 170, and heat exchangers 175. The polymerization system 100 may also include more than one reactor 101 arranged in series, in parallel, or independently of other reactors, each reactor having its own associated discharge tank 155, compressor 170, and heat exchanger 175, or alternatively, sharing any one or more of the associated discharge tanks 155, compressors 170, and heat exchangers 175. For simplicity and ease of description, the polymerization system 100 will be further described in the context of a single reactor assembly.

[0041] Reactor 101 may include a cylindrical section 103, a transition section 105, and a velocity reduction zone or dome 107. The cylindrical section 103 is arranged vertically adjacent to the transition section 105. The transition section 105 may expand from a first diameter corresponding to the diameter of the cylindrical section 103 to a larger diameter adjacent to the dome 107. The location or joint where the cylindrical section 103 connects to the transition section 105 is referred to as the "neck" or "reactor neck" 104. The dome 107 has a spherical shape. One or more circulating fluid lines 115 and discharge lines 118 may be in fluid communication with the dome 107. Reactor 101 may include a fluidized bed 112 in fluid communication with the dome 107.

[0042] Generally, the height-to-diameter ratio of the cylindrical section 103 can vary in the range of approximately 2:1 to approximately 5:1. Of course, this range can be varied to larger or smaller ratios, and depends at least in part on the required production capacity and / or reactor size. The cross-sectional area of ​​the dome 107 is typically in the range of approximately 2 to approximately 3 times the cross-sectional area of ​​the cylindrical section 103.

[0043] The velocity reduction zone or dome 107 has a larger inner diameter than the fluidized bed 112. As the name suggests, the velocity reduction zone slows down the gas velocity due to the increased cross-sectional area. This reduction in gas velocity allows particles entrained in the upward-moving gas to fall back into the bed 112, primarily allowing the gas to exit the top of the reactor 101 only via the circulating fluid line 115. The circulating fluid recovered via the circulating fluid line 115 may contain less than about 10% by weight, less than about 8% by weight, less than about 5% by weight, less than about 4% by weight, less than about 3% by weight, less than about 2% by weight, less than about 1% by weight, less than about 0.5% by weight, or less than about 0.2% by weight of entrained particles from the fluidized bed 112.

[0044] The reactor feed via line 110 can be introduced into the polymerization system 100 at any point. For example, the reactor feed via line 110 can be introduced into the cylindrical section 103, the transition section 105, the velocity reduction zone, any point within the circulating fluid line 115, or any combination thereof. Preferably, the reactor feed 110 is introduced into the circulating fluid in the circulating fluid line 115 before or after the heat exchanger 175. In this figure, the reactor feed via line 110 is depicted entering the circulating fluid in the circulating fluid line 115 after the heat exchanger 175. The catalyst feed via line 113 can be introduced into the polymerization system 100 at any point. Preferably, the catalyst feed is introduced into the fluidized bed 112 within the cylindrical section 103 via line 113.

[0045] The circulating fluid via circulating fluid line 115 can be compressed in compressor 170 and then passes through heat exchanger 175, where heat can be exchanged between the circulating fluid and the heat transfer medium. For example, during normal operating conditions, a cool or cold heat transfer medium can be introduced into heat exchanger 175 via line 171, where heat can be transferred from the circulating fluid in circulating fluid line 115 to produce a heated heat transfer medium via line 177 and a cooled circulating fluid via circulating fluid line 115. In another example, during the idling of reactor 101, a warm or hot heat transfer medium can be introduced into heat exchanger 175 via line 171, where heat can be transferred from the heat transfer medium to the circulating fluid in circulating fluid line 115 to produce a cooled heat transfer medium via line 177 and a heated circulating fluid via circulating fluid line 115. The terms "cold heat transfer medium" and "low-temperature heat transfer medium" refer to heat transfer media with temperatures lower than those of the fluidized bed 112 within reactor 101. The terms "warm heat transfer medium" and "hot heat transfer medium" refer to heat transfer media with temperatures higher than those of the fluidized bed 112 within reactor 101. The fluidized bed 112 can be cooled or heated using heat exchanger 175, depending on the operating conditions of the polymerization system 100, such as reactor start-up, normal operation, idle, and shutdown. Exemplary heat transfer media may include, but are not limited to, water, air, glycol, or the like. The compressor 170 may also be located downstream of the heat exchanger 175 or at an intermediate point between several heat exchangers 175.

[0046] After cooling, all or part of the circulating fluid via circulating fluid line 115 can be returned to reactor 101. The cooled circulating fluid in circulating fluid line 115 can absorb the heat of reaction generated by the polymerization reaction. The heat transfer medium in line 171 can be used to transfer heat to the circulating fluid in circulating fluid line 115, thereby introducing heat into the polymerization system 100 rather than removing heat from it. Heat exchanger 175 can have any type of heat exchanger. Exemplary heat exchangers can include, but are not limited to, shell-and-tube, plate and frame, U-tube, and the like. For example, heat exchanger 175 can be a shell-and-tube heat exchanger in which circulating fluid can be introduced to the tube side via circulating fluid line 115 and heat transfer medium can be introduced to the shell side of heat exchanger 175. If desired, several heat exchangers can be used in series, in parallel, or in a series-parallel combination to reduce or increase the temperature of the circulating fluid in stages.

[0047] Preferably, the circulating gas via the circulating fluid line 115 is returned to the reactor 101 and the fluidized bed 112 via a fluid distributor plate ("plate") 119. The plate 119 is preferably installed at the inlet of the reactor 101 to prevent polymer particles from precipitating and agglomerating into solids and to prevent liquid volume from accumulating at the bottom of the reactor 101, and to facilitate easy switching between processes containing liquid from the circulating fluid line 115 and those not containing it, and vice versa. Although not shown, the circulating gas can be introduced into the reactor 101 via the circulating fluid line 115 through deflector plates arranged or positioned at the end of the reactor 101 and between the distributor plate 119.

[0048] The catalyst feed via line 113 can be introduced into the fluidized bed 112 within reactor 101 through one or more injection nozzles in fluid communication with line 113. The catalyst feed is preferably introduced as preformed particles in one or more liquid carriers (i.e., catalyst slurry). Suitable liquid carriers may include mineral oils and / or liquid or gaseous hydrocarbons, including but not limited to propane, butane, isopentane, hexane, heptane, octane, or mixtures thereof. Inert gases (e.g., nitrogen or argon) to the catalyst slurry may also be used to carry the catalyst slurry into reactor 101. In one example, the catalyst may be a dry powder. In another example, the catalyst may be dissolved in a liquid carrier and introduced into reactor 101 as a solution. The catalyst via line 113 can be introduced into reactor 101 at a rate sufficient to sustain the polymerization of monomers (one or more) therein. Hydrogen is added via line 114.

[0049] The fluid via line 161 can be separated from the polymer product recovered from reactor 101 via line 117. The fluid may include unreacted monomers (one or more), hydrogen, induced condensate (ICA), and / or inert materials. The separated fluid may be introduced into reactor 101. The separated fluid may be introduced into circulating fluid line 115. Fluid separation is achieved when the fluid and product leave reactor 101 via line 117 and pass through valve 157 into product discharge tank 155, which may be, for example, a ball valve designed to have a minimum flow restriction when open. Conventional valves 159 and 167 may be located above and below product discharge tank 155. Valve 167 allows product to pass through. For example, to discharge polymer product from reactor 101, valves 157 and 159 may be opened while valve 167 is closed. Product and fluid enter product discharge tank 155. Valve 157 is closed, and the product settles in product discharge tank 155. Valve 159 is then opened, allowing fluid to flow from product discharge tank 155 to reactor 101 via line 161. Valve 159 can then be closed and valve 167 can be opened, allowing any product from product discharge tank 155 to flow into and be recovered via line 168. Valve 167 can then be closed. Although not shown, the product can be introduced via line 168 into multiple purge cabinets or separation units in series, parallel, or a combination of series and parallel connections for further separation of gas and / or liquid from the product. The specific timing of valves 157, 159, and 167 can be implemented using conventional programmable controllers known in the art.

[0050] Reactor 101 may be equipped with one or more vent lines 118 to allow bed venting during start-up, idling, and / or shutdown. Reactor 101 may operate without agitation and / or wall scraping. Circulating fluid lines 115 and the components therein (compressor 170, heat exchanger 175) may be smooth-surfaced and free of unnecessary obstructions so as not to impede the flow of circulating fluid or entrained particles.

[0051] Polymerization conditions vary depending on the monomer, catalyst, catalyst system, and equipment availability. Specific conditions are known or can be readily derived by those skilled in the art. For example, temperatures can range from about -10°C to about 140°C, typically from about 15°C to about 120°C, and more typically from about 70°C to about 110°C. Pressures can range, for example, from about 10 kPag to about 10,000 kPag, for example from about 500 kPag to about 5,000 kPag, or from about 1,000 kPag to about 2,200 kPag.

[0052] catalyst system

[0053] The term "catalyst system" includes at least one "catalyst component" and at least one "activator," or at least one co-catalyst. A catalyst system may also include other components, such as a support, and is not limited to single or combined catalyst components and / or activators. A catalyst system may include any number of catalyst components in any combination as described, and any combination of activators as described.

[0054] The term "catalyst component" includes any compound capable of catalyzing the polymerization or oligomerization of olefins upon proper activation. Preferably, the catalyst component comprises at least one Group 3 to Group 12 atom and optionally at least one leaving group bonded thereto. The term "leaving group" refers to one or more chemical structural moieties bonded to the metal center of the catalyst component, which can be extracted from the catalyst component by an activator to produce a substance active for the polymerization or oligomerization of olefins. Suitable activators are described in detail below.

[0055] In some embodiments, the catalyst component used for polymerization includes polymerization catalysts selected from metallocene catalysts, Ziegler-Natta catalysts, chromium catalysts, atypical single-site catalysts (e.g., pyridyl diamide-transition metal catalysts, bis(2-pentamethylphenylamino)ethyl)amine-transition metal catalysts, Schiff base-transition metal catalysts, etc.) and combinations thereof. In embodiments, the catalyst is a metallocene catalyst, which is particularly susceptible to agglomeration and / or clumping triggered by changes in polymerization conditions. Metallocene catalysts produced in gas-phase polymerization methods produce linear low-density polyethylene (LLDPE). LLDPE prepared using one or more metallocene catalysts is referred to herein as mLLDPE. mLLDPE may comprise 80 to 99.9% by weight of ethylene-derived units and the balance derived from one or more C3 to C4 catalysts. 12 Copolymers of units of α-olefin comonomers (especially one or more of butene, hexene, and octene, and more preferably hexene). Metallocene catalysts include, but are not limited to: Type 1: unbridged dicyclopentadienyl Group 4 and its substituted variants; Type 2: bridged dicyclopentadienyl Group 4 and its substituted variants; Type 3: substituted macroligand hafnium transition metal metallocene catalyst compounds and their substituted variants; and Type 4: dual catalyst systems comprising a bridged dicyclopentadienyl Group 4 metal catalyst and an unbridged dicyclopentadienyl Group 4 metal catalyst.

[0056] As used in this article, the "family" of the periodic table is referred to by the "new" numbering scheme for periodic table families, as used in the CRC Handbook of Chemistry and Physics (edited by David R. Lide, CRC Press, 81st edition, 2000).

[0057] As used herein, the term "activator" refers to any compound or combination of compounds, supported or unsupported, that can activate a catalyst compound or component (e.g., by generating a cationic substance of the catalyst component). For example, this can include extracting at least one leaving group (the "X" group in the unit site catalyst compound / component described herein) from the metal center of the unit site catalyst compound / component. Activators can include Lewis acids, such as cyclic or oligomeric poly(hydrocarbon aluminum oxides) and so-called noncoordinating activators ("NCA") (or, "ionized activators" or "stoichiometric activators"), or any other compound that can convert a neutral metallocene catalyst component into a metallocene cation active for olefin polymerization. Illustrative Lewis acids include, but are not limited to, aluminoxanes (e.g., methylaluminoxane "MAO"), modified aluminoxanes (e.g., modified methylaluminoxane "MMAO" and / or tetraisobutyldialuminoxane "TIBAO"), and alkylaluminum compounds. Ionizing activators (neutral or ionic), such as tris(n-butylammonium)tetra(pentafluorophenyl)boron, can also be used. Additionally, triperfluorophenylboron metalloid precursors can be used. Any of these activators / precursors can be used alone or in combination with other activators / precursors. Various methods for preparing aluminoxanes and modified aluminoxanes are known in the art.

[0058] Catalyst compositions may include support materials or carriers. The terms "support" and "carrier" as used herein are used interchangeably and refer to any support material, including porous support materials such as talc, inorganic oxides, and inorganic chlorides. Catalyst components (one or more) and / or activators (one or more) may be deposited on, contacted with, evaporated from, bonded to, or incorporated into one or more supports or carriers, or adsorbed or absorbed in or on one or more supports or carriers. Other support materials may include resin support materials such as polystyrene, functionalized or cross-linked organic supports such as polystyrene-divinylbenzene polyolefins or polymeric compounds, zeolites, clays, or any other organic or inorganic support materials, or mixtures thereof.

[0059] Inorganic oxide supports may include metal oxides of Groups 2, 3, 4, 5, 13, or 14. Preferred supports include silica (which may or may not be dehydrated), pyrolytic silica, alumina, silica-alumina, and mixtures thereof. Other useful supports include magnesium oxide, titanium oxide, zirconium oxide, magnesium chloride, montmorillonite, layered silicates, zeolite, talc, clay, etc. Furthermore, combinations of these support materials may be used, such as silica-chromium, silica-alumina, silica-titanium oxide, etc. Additional support materials may include those porous acrylic polymers described in EP 0 767 184, which are incorporated herein by reference.

[0060] The polymer products (one or more) generated in the reactor can be or include any type of polymer or polymer material. For example, polymer products may include homopolymers of olefins (e.g., homopolymers of ethylene), and / or copolymers, terpolymers, etc., of olefins (particularly ethylene) and at least one other olefin. Exemplary polymers may include, but are not limited to, polyolefins, polyamides, polyesters, polycarbonates, polysulfones, polyacetals, polylactones, acrylonitrile-butadiene-styrene polymers, polyphenylene ethers, polyphenylene sulfides, styrene-acrylonitrile polymers, styrene-maleic anhydride, polyimides, aromatic polyketides, or mixtures of two or more of the above. Suitable polyolefins may include, but are not limited to, those comprising one or more linear, branched, or cyclic C2 to C3 groups. 40 Polymers of olefins, preferably comprising one or more C3 to C4 groups. 40 Olefins, preferably C3 to C4 20 α-olefins, more preferably C3 to C4 10 Polymers of propylene copolymerized with α-olefins. More preferably, polyolefins include, but are not limited to, those containing ethylene, including but not limited to those copolymerized with C3 to C4 olefins. 40 Olefins, preferably C3 to C4 20 Polymers of ethylene copolymerized with α-olefins, more preferably propylene and / or butene.

[0061] polymer products

[0062] Preferred polymers include C2 to C3. 40 Olefins, preferably C2 to C3 20 Homopolymers or copolymers of olefins, preferably α-olefins and another olefin or copolymers of α-olefins (ethylene is defined as an α-olefin for the purposes of this invention). Preferably, the polymer is or includes homopolymer polyethylene, homopolymer polypropylene, propylene copolymerized with ethylene and / or butene, and ethylene copolymerized with one or more of propylene, butene, or hexene and optionally dienes. Preferred examples include thermoplastic polymers such as ultra-low density polyethylene (uLDPE), very low density polyethylene (“VLDPE”), linear low density polyethylene (“LLDPE”), low density polyethylene (“LDPE”), medium density polyethylene (“MDPE”), high density polyethylene (“HDPE”), polypropylene, isotactic polypropylene, highly isotactic polypropylene, syndiotactic polypropylene, random copolymers of propylene and ethylene and / or butene and / or hexene, elastomers such as ethylene propylene rubber, ethylene propylene diene monomer rubber, chloroprene rubber, and blends of thermoplastic polymers and elastomers, such as thermoplastic elastomers and rubber-toughened plastics.

[0063] The polyethylene polymer produced by gas-phase polymerization is characterized by many parameters, including but not limited to density, melt index (I2), and high-load melt index (I).21 Or HLMI), melt index ratio (MIR), number average molecular weight (M n ), weight-average molecular weight (M w z-average molecular weight (M) z ), molecular weight distribution (M) w / M n Or MWD), the ratio of z-average molecular weight to weight-average molecular weight (M z / M w The composition, melt index, and branching index (g') are parameters related to the physical properties of the polymer chain, including but not limited to: chain length, chain length distribution, comonomer distribution between and along the chain, and the length and number of branches on the chain. These physical properties of the polymer chain result in different mechanical properties, making different polyethylene polymers suitable for a wide range of end-use applications.

[0064] Polymerization conditions in the fluidized bed within the polymerization reaction zone can be controlled to produce polyethylene polymers with desired parameter combinations and maintain the stability of the polymerization reaction in the gas-phase reactor. Such polymerization conditions include, but are not limited to, reactor temperature, reactor pressure, ethylene monomer feed rate, comonomer type and feed rate, catalyst type and feed rate, comonomer to ethylene ratio, hydrogen addition rate, amount of one or more induced condensers, amount of one or more continuous additives, and Δmelt initiation temperature (dMIT, see U.S. Patent No. 7,683,140, ​​the contents of which are incorporated herein by reference in their entirety.)

[0065] Polyethylene manufacturers typically identify each polyethylene polymer with a specific set of properties by grade name and / or number. Density and melt index (I2) are usually key parameters associated with each polyethylene polymer grade. For manufacturers, each such polyethylene polymer grade is associated with a specific set of polymerization conditions.

[0066] Continuous additives / static control agents

[0067] In methods for preparing fumed polyethylene, it may be desirable to use one or more electrostatic control agents to help regulate the electrostatic level in the reactor. The electrostatic control agents used here are chemical compositions that, when introduced into a fluidized bed reactor, can influence or drive the static charge (negative, positive, or to zero) in the fluidized bed. The specific electrostatic control agent used can depend on the nature of the static charge, and the choice of electrostatic control agent can vary depending on the polymer being prepared and the unit site catalyst compound used.

[0068] Static control agents such as aluminum stearate can be used. The choice of static control agent can be based on its ability to receive static charge in the fluidized bed without adversely affecting productivity. Other suitable static control agents may include aluminum distearate, ethoxylated amines, and antistatic compositions such as those offered by Innospec Inc. under the trademark OCTASTAT. For example, OCTASTAT 2000 is a mixture of polysulfone copolymer, polymeric polyamine, and oil-soluble sulfonic acid.

[0069] Any of the aforementioned control agents may be used alone or in combination as control agents. For example, a metal carboxylate salt may be combined with an amine-containing control agent (e.g., a metal carboxylate salt with any member of the KEMAMINE® family (available from Crompton Corporation) or the ATMER® family (available from ICI Americas Inc.)).

[0070] Other useful continuous additives include ethyleneimine additives, which, in the embodiments disclosed herein, may include polyethyleneimine having the following general formula: —(CH2—CH2—NH) n - where n can be from about 10 to about 10,000. Polyethyleneimine can be linear, branched, or hyperbranched (i.e., forming a dendritic or arborescent polymer structure). It can be a homopolymer or copolymer of ethyleneimine or a mixture thereof (hereinafter referred to as polyethyleneimine). Although the chemical formula is -(CH2-CH2-NH) n The straight-chain polymer indicated by - can be used as polyethyleneimine, but materials with primary, secondary, and tertiary branches can also be used. Commercially available polyethyleneimine can be a compound with ethyleneimine polymer branches.

[0071] Under normal polymerization conditions, a gas-phase fluidized bed reactor has several distinct regions containing different phases of matter. For example, near the top of the fluidized bed, there is primarily solid particles (e.g., containing polymer resin and / or one or more solid catalyst components) and circulating gas. Near the bottom of the fluidized bed, there is a combination of solid particles (e.g., containing polymer resin and / or one or more solid catalyst components), circulating gas, and liquid. Near the distributor plate, there is typically a combination of liquid and circulating gas. The liquid in the reactor can come from several sources. One source is from the reactor feed, for example, when using an induced condenser such as an inert hydrocarbon (e.g., isomers of butane, pentane, hexane, etc.). Additional liquid can come from the polymer melt, where the polymer being prepared is melted by the heat generated by the exothermic polymerization reaction. Liquid can also be generated when reaction conditions such as pressure and temperature cause some monomers such as ethylene and comonomers such as 1-butene or 1-hexene to condense into a liquid phase. The composition of the liquid in the reactor can vary depending on the specific reactor, but typically includes polyethylene (or other polymer melts), monomers and comonomers, and a catalyst.

[0072] The position of the liquid in the reactor can vary depending on the specific design of the gas-phase fluidized bed reactor. In most reactors, the liquid stagnation is dispersed throughout the reactor as droplets suspended in the gas phase. Polymer particles grow through the continuous adsorption of monomers on the surface. This reaction is exothermic, generating enough heat to form a liquid layer of polymer melt on the particles. The liquid layer can then be stripped by rising gas to form droplets that sweep upwards with the gas flow, or may drip due to gravity, thus creating a circulating liquid phase within the reactor.

[0073] Currently, industrial gas-phase methods for polymer production only discharge the product from the bottom of the reactor. When discharging the polymer product from the bottom of the reactor, a relatively large amount of liquid is also discharged along with the product. As mentioned above... Figure 1 As described in the article, the fluid containing the polymer, unreacted monomers (one or more), hydrogen, induced condenser (ICA), and / or inert material is removed from the reactor, and the liquid is separated from the polymer and reintroduced into the reactor.

[0074] As mentioned above, flocculing and other fouling mechanisms can be quite problematic in such polymerization reactors. For example, particles are thought to agglomerate due to a number of influences, such as viscosity caused by excess reactor temperature, electrostatic charge, and other agglomeration factors. These influences can be even greater in larger polymerization reactors, where the additional mass of particles can present operational challenges, including increased agglomeration and flocculing, as more particles are available to form sheets or clumps within the reactor. For example, polymer product particles near the top of the reactor (e.g., in the reactor dome) tend to be smaller and hotter. Smaller and hotter particles have an increased tendency to stick together to form agglomerates, which can lead to increased fouling through flocculing and agglomeration. As reactor size increases, the number of smaller and hotter particles also increases, further increasing the tendency to form sheets and clumps. Conventional gas-phase fluidized bed reactors have a product discharge system that unloads the product from a position of approximately 0.5% H to approximately 5% H, where H is the height of the straight section of the reactor, defined as the section of the reactor above the distributor plate to the reactor neck. Figures 3A-3C The product discharge system is arranged slightly above the distributor plate to allow for the removal of bulk materials and sheets from the reactor. (Details of H are shown.)

[0075] Not wanting to be limited by theory, the inventors surprisingly discovered that unloading polymer products from additional locations in the straight section of the reactor at positions above 5%H to approximately 95%H has several advantages compared to unloading products from conventional locations at approximately 0.5%H to approximately 5%H, including the removal of smaller, hotter particles, thereby reducing flocculants, agglomerates, and / or other fouling mechanisms within the reactor. Furthermore, when the product discharge port is located at approximately 0.5%H to approximately 5%H, a larger amount of liquid is removed when the product is discharged from the reactor. The liquid portion removed from the reactor is typically conveyed to a liquid recovery system associated with the reactor to separate the polymer melt from other liquid components such as monomers and catalysts, which are then recycled back to the reactor. Liquid recovery systems exhibit low process efficiency in polymer product production because the liquid recovery unit does not contribute to the production of more product and still requires energy to operate. Unloading polymer products from one or more locations in the straight section of the reactor at positions above 5%H to approximately 95%H has the effect of reducing the amount of liquid extracted from the reactor, as the liquid concentration at relatively higher locations in the straight section tends to be lower than the liquid concentration near the distributor plate. The liquid concentration includes the liquid absorbed into the polymer product as well as the free liquid that has condensed. Therefore, extracting the product from a position above 5%H to about 95%H reduces the load on the liquid recovery system, thereby reducing the energy required to operate the liquid recovery system, compared to discharging the product only from a position of about 0.5%H to about 5%H.

[0076] Another advantage of discharging polymers from the reactor in a straight section at a level above 5%H to approximately 95%H is that the particle size distribution of the polymer product can be more easily selected. In reactors where products are discharged only from a level of approximately 0.5%H to approximately 5%H, the particle size distribution of the discharged product depends in part on the reactor run time between product drops, where shorter drop intervals generally produce products with smaller sizes, and longer drop intervals generally produce products with larger sizes. However, the distribution of larger particles decreases with shorter drop times, and conversely, the distribution of smaller particles decreases with longer drop times. Therefore, for conventional product discharge systems discharging approximately 0.5%H to approximately 5%H, the average particle size d50 tends to start at a lower value, which increases as the time between product drops increases. However, the particle size distribution, such as the distribution width or whether the distribution is multimodal, or other characteristics of the particle size distribution, is not necessarily a controllable variable, as the time between product unloading cycles primarily determines the characteristics of the particle size distribution. When polymer products are extracted at one or more locations above 5%H to approximately 95%H and at conventional locations from 0.5%H to approximately 5%H, smaller particles can be removed at the higher locations in the straight section, and larger particles can be removed at the lower locations in the straight section. A control scheme that discharges a subset of smaller particles and a subset of larger particles allows for fine-tuning of the final particle size distribution extracted from the reactor. Bed fluidization can also be controlled by selectively removing larger and smaller particles by observing the pressure drop within the reactor and / or the scaling rate observed in the reactor.

[0077] Another advantage of discharging the polymer from the straight section of the reactor at a position above 5%H to approximately 95%H is that the chunking rate can be more easily controlled. (See above reference.) Figure 1The product can be introduced via line 168 into multiple purge chambers or separation units in series, parallel, or a combination of series and parallel connections for further separation of gases and / or liquids from the product. Under normal operating conditions, a portion of the produced product will be unsuitable for use or sale because it does not meet the required product specifications. For example, larger pieces of the product may not meet the required product specifications and are typically screened into purge chambers in downstream product handling systems. A screen agglomeration rate monitor, configured to monitor the product from line 168 in the downstream product handling system, can be used to inform the process operator or control system of the agglomeration rate in the reactor. In response to the agglomeration rate, the product discharge rate from different locations in the straight section can be adjusted to reduce the agglomeration rate, for example, by removing more smaller particles from locations in the range of above 5%H to approximately 95%H. The screen agglomeration rate monitor can measure the agglomeration rate using any suitable method, including manual observation or automatic monitoring, such as using acoustic monitors or computer vision programs to determine the agglomeration rate, which can then be used as an input signal in control systems, such as distributed control systems (DCS). Then, the control system can activate the control loop and send a signal to discharge the polymer product at a position above 5%H in the straight section to unload the polymer product having a relatively smaller particle size than the particles discharged above 5%H.

[0078] Another advantage of discharging the polymer from the reactor in a straight section at a position above 5%H to approximately 95%H is that it can reduce distributor plate fouling. One source of distributor plate fouling is the carrying of fine particles into the circulating fluid line 115 and / or the exhaust line 118, such as... Figure 1 As shown above, polymer product particles in the upper part of the reactor tend to be smaller, and therefore have a higher tendency to be entrained in the upward-flowing gas in the reactor. Discharging polymer product at a higher position in the straight section allows for the removal of a larger proportion of finer particles, which have a higher tendency to be carried into the circulating fluid and exhaust line. One method of monitoring the carry-over rate of fine particles involves using probes, such as static probes for the circulating gas and / or acoustic probes attached to components (e.g., pipes, heat exchangers, and / or compressors) in the circulating gas loop. The probes can output a signal corresponding to the carry-over rate of fine particles in the circulating fluid and / or exhaust line, which can be used as an input to a control system (e.g., a DCS) that can adjust one or more operating parameters to bring the carry-over rate closer to a setpoint. For example, the control system can command a control valve to discharge polymer product at a position above 5%H in the straight section, thereby unloading polymer product with a relatively smaller particle size than particles discharged below 5%H.

[0079] Figure 2A simplified illustrative gas-phase polymerization system 200 for preparing polymers, with an improved product emission system, is described according to one or more embodiments. The gas-phase polymerization system 200 includes a fluidized bed reactor 202, as previously described, having a distributor plate 220 disposed therein. Figure 2 As shown, the straight section 216 has a height H defined between the distributor plate 220 and the neck 218, where 0%H corresponds to the straight section 216 at the distributor plate 220, 100%H corresponds to the end of the straight section 216 that meets the neck 218, and 50%H corresponds to half the distance between the distributor plate 220 and the neck 218. The product unloading line 204 is arranged such that the product stream is extracted from the straight section 216 at a position corresponding to at least 5%H, preferably greater than 5%H. As described above, arranging the product unloading line 204 at a position of at least 5%H, preferably greater than 5%H, allows for finer control of the polymerization system 200 by controlling the amount of liquid extracted from the fluidized bed reactor 202 and selecting the particle size of the extracted polymer product. For example, the product stream (e.g., as in...) Figure 2 The liquid (measured in line 204 in the diagram) may contain 10% by weight liquid (by volume) or less, for example, in the range from the lower limit of any one of about 0, 0.1, 0.2, 0.5, 0.7, 0.8, 0.9 or 1.0% by weight liquid (by volume) to the upper limit of any one of about 1.5, 2, 3, 4, 5, 6, 7, 8, 9 or 10% by weight liquid (by volume), where the range from any of the aforementioned lower limits to any of the aforementioned upper limits is taken into account. The liquid includes dissolved liquid in the polymer product plus droplets exiting the reactor.

[0080] To facilitate the removal of less liquid and smaller particles from the reactor during the unloading cycle (dripping cycle), the product unloading line 204 may be positioned above the distributor plate 220 in the fluidized bed reactor 202, above the liquid level within the fluidized bed reactor, or at a position approximately halfway above the fluidized bed (e.g., measured from the bottom of the fluidized bed). This can be expressed as a percentage of the height H of the straight section 216. Typically, the product unloading line 204 may be arranged along the vertical length of the reactor, corresponding to approximately 0.1% to approximately 95% of the height H of the straight section 216. For example, the product unloading line 204 can be arranged along the vertical length of the reactor above the distributor plate 220 at a height corresponding to X% of the height H of the straight section 216, where X can be a lower limit of any one of about 0.1, 0.5, 1, 5, 8, 10, 15, 20, 30, 40, 50, 60, 70, 80, or 90 to an upper limit of any one of about 0.5, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 95, wherein the range from any of the aforementioned lower limit to any of the aforementioned upper limit (provided the upper limit is greater than the lower limit) is considered, for example, about 10% to about 95% of H; or about 50% to about 75% of H; or about 50% to about 95% of H; or about 70% to about 95% of H; or about 90% to about 95% of H. Although Figure 2 Not shown, but it should be understood that polymer products can also be extracted from fluidized bed reactor 202 using conventional product unloading line locations corresponding to 5% or less of H.

[0081] It should be noted that the height of the product discharge line along the reactor will affect the dynamic pressure within the product discharge line to move the polymer within it. Therefore, generally, the higher the discharge line, the lower the dynamic pressure within it. Lower dynamic pressure may reduce the product tank filling efficiency per product drop. Therefore, it may be beneficial to utilize the product discharge line height to balance the lower dynamic pressure encountered at greater heights with the reduced liquid discharge volume enjoyed at greater heights.

[0082] In some embodiments, the product unloading line 204 may include a dielectric coating, such as titanium dioxide, silica, and / or alumina, on its interior; other examples include polymer coatings (e.g., epoxy resins, natural or synthetic rubbers, urethane-based polymers, polyvinyl chloride, acrylic-based polymers, etc.). Furthermore, it is contemplated that any equipment connected to the product unloading line 204 may be equipped with such a dielectric coating, such as portions or all of a discharge tank (e.g., discharge tank 206), and / or portions of the wall of reactor 202 near the unloading line 204, and any and all valves along the unloading line 204. As an alternative to the dielectric coating on the unloading line 204, an inner tube or other conduit made of any or more of the dielectric materials just discussed may be arranged within the unloading line 204 for conveying particles within the product unloading line 204.

[0083] The flow into the discharge tank 206 via the product unloading pipeline 204 can be controlled by at least one valve (e.g., such as...). Figure 2 (As shown along line 204). Once the desired amount of product has been unloaded from the reactor, the valve can be closed and the discharge tank 206 isolated. Gas can be extracted from the discharge tank 206 using line 210, and optionally a portion of the gas can be purged as feed stream 212 (e.g., sent to a flare or other processing outside the reaction system), and the remaining gas can be reintroduced into the reactor 202 via return line 214. Return line 214 can be located on a straight section 216 corresponding to approximately 80%H to approximately 100%H, provided that return line 214 is arranged in the straight section 216 above product unloading line 204. Product feed stream 208 can be extracted from discharge tank 206 and sent to a product processing unit for further processing, such as separating additional gases and / or liquids from the polymer product and other finishing operations known in the art.

[0084] Furthermore, in various embodiments, multiple product unloading lines can be utilized, each fluidly connected to the reactor at a corresponding percentage of height H along the straight section 216. Each product unloading line can be located at any height discussed above in conjunction with product unloading line 204. For example, a first product unloading line can be fluidly connected to the reactor at a first height corresponding to 10-50% of the fluidized bed height H; and a second product unloading line can be fluidly connected to the reactor at a second height corresponding to 50-95% of H. It should be understood that each of the first and second heights can be independently within any percentage of H described above with respect to line 204; and furthermore, a third, fourth, or more product unloading lines can be used (each also at a corresponding height within the previously disclosed range of %H).

[0085] For example, Figure 3A An exemplary gas-phase polymerization system 300 for preparing polymers, having an improved product discharge system according to one or more embodiments, is depicted. The gas-phase polymerization system 300 includes a fluidized bed reactor 302, as previously described. The fluidized bed reactor 302 includes a straight section 324 having a height H defined between a distributor plate 316 and a reactor neck 322. Figure 3A As shown, the first product unloading line 304 is positioned at a height of approximately 0.5%H to 5%H on the straight section 324 corresponding to the location of the conventional product discharge system. The second product unloading line 306 is positioned above the first product unloading line 304 and spaced apart from it by a height "X". The position of the second product unloading line 306 on the straight section 324 can be approximately 5%H to approximately 95%H; preferably, the second product unloading line 306 is also located below the height of the return line 328, such as... Figure 3A As shown.

[0086] Each of the first product unloading line 304 and the second product unloading line 306 is fluidly connected to the interior of the reactor, such that each product unloading line can extract the product stream from a corresponding position on the straight section 324 of the reactor. Once the desired amount of product has been unloaded from the reactor via the first product unloading line 304, the second product unloading line 306, or a combination thereof, the valve corresponding to each product unloading line can be closed and the discharge tank 312 isolated. Gas can be extracted from the discharge tank 312 using line 308, and optionally a portion of the gas can be purged as feed stream 326 (e.g., sent to a flare or other processing outside the reaction system), and the remaining gas can be reintroduced into the fluidized bed reactor 302 via return line 328. Return line 328 can be located on the straight section 324 at a position corresponding to about 80%H to about 100%H, provided that return line 328 is preferably arranged in the straight section 324 above the second product unloading line 306. A recirculating gas purging line 320 (e.g., Figure 1 The circulating fluid line 115 described herein is used to purge the remaining gas, liquid and / or product from the first product unloading line 304, the second product unloading line 306 or a combination thereof.

[0087] Figure 3B An alternative illustrative gas-phase polymerization system 300 for preparing polymers, with an improved product emission system according to one or more embodiments, is described. The gas-phase polymerization system 300 includes a fluidized bed reactor 302, as previously described. Figure 3B As shown, the first product unloading line 304 and the second product unloading line 306 are separated by a height "Y", where "Y" is greater than the height of the product unloading line from the product unloading line. Figure 3A The "X".

[0088] Figure 3CAn alternative illustrative gas-phase polymerization system 300 for preparing polymers, with an improved product emission system according to one or more embodiments, is described. The gas-phase polymerization system 300 includes a fluidized bed reactor 302, as previously described. Figure 3C As shown, system 300 includes a first product unloading line 304, a second product unloading line 306 located at a height "X" above the first product unloading line 304, and a third product unloading line 330 located at a height "Y" above the first product unloading line 304.

[0089] Further reference Figures 3A-3C To facilitate the unloading of less liquid from the reactor during the unloading cycle (drip cycle), product unloading valves associated with each of the first product unloading line 304, the second product unloading line 306, and / or the third product unloading line 330 are opened, and the product is extracted into the product chamber 312. The product unloading valves associated with each product unloading line can be individually controlled so that the unloaded product has the desired properties as described above, including, for example, selecting the particle size of the extracted product. Once the drip cycle is complete, the product unloading valves are closed, and the polymer product is transferred to a product blow tank 314 and extracted as a product stream 318, which may optionally be sent to a finishing section for further processing known in the art (e.g., blending with one or more additives, extrusion, and granulation, etc.). A circulating purge gas 320 may be introduced to purge any remaining product from each product unloading line.

[0090] The product discharge system may include product discharge valves arranged on each product discharge line and controllers for controlling the position of the product discharge valves. Optionally, the product discharge system may also include instruments for measuring the properties of the product discharged from each location in the reactor. For example, the instruments may measure temperature, density, particle size distribution, liquid volume percentage, solid volume percentage, or any other desired physical property. The instruments may include temperature probes, density measuring devices, particle size measuring devices such as optics, and combinations thereof. In embodiments, the product discharge system is integrated into a control system, such as a local control system or a distributed control system.

[0091] A Distributed Control System (DCS) is a computer-based control system used to monitor and control processes in a chemical plant. DCS can be used to control a wide variety of processes, including, for example, distillation columns, reactors, and pumps, and can be integrated across several units, allowing multiple units to be controlled simultaneously in response to a single signal. A DCS typically consists of several components, including: sensors: these devices measure the physical properties of the process, such as temperature, pressure, and flow rate; controllers: these devices use data from the sensors to calculate necessary adjustments to the process; actuators: these devices execute control commands from the controllers, such as opening or closing valves; and a Human-Machine Interface (HMI): this is a graphical user interface that allows operators to monitor and control the process. DCS uses various types of logic control, such as PID controllers, ladder logic, and sequential function charts, to control the process. The logic control is programmed into the DCS software and used to ensure that the equipment operates within predetermined limits.

[0092] For example, a controller associated with a product discharge system or DCS can send a control signal to open one or more product unloading valves to initiate a product drip cycle. During the product drip cycle, the instrument reports the physical properties of the product within the unloading line to the controller or DCS, such as particle size distribution, temperature, liquid percentage, or any other useful physical properties. The controller or DCS can monitor the physical properties of the product and compare the measured properties with setpoint properties, and in response, adjust the position of one or more product unloading valves.

[0093] In various implementations, the controller can operate the product unloading valve (which may also be referred to as the product discharge valve) in several ways. For example, the controller can control the product unloading valve to alternate between "top" and "bottom" product drips, thereby opening the product unloading valve on the unloading line arranged in the higher part of the reactor and the product unloading valve on the unloading line arranged in the lower part of the reactor alternately. Alternatively, the controller can control the product unloading valve to discharge a desired volume or mass from the top position of the reactor and from the bottom position of the reactor. In this approach, the controller, such as a PID controller, opens the product unloading valve by a certain amount, such that the desired product mass / volume distribution is extracted from the reactor. Additionally, the controller can control the product unloading valve to perform a desired number of bottom or top product drips or control the number of alternating product drips between the bottom and top. In such an approach, the controller can alternate between the number of drips from the top and bottom, for example, one bottom drip followed by one top product drip, or two bottom product drips followed by two top product drips, or one bottom product drip followed by three top product drips.

[0094] The size of the unloading valve from the reactor can be designed such that the discharge rate of the product flowing through the unloading valve is at least 0.01 tonnes of particles per second, for example, in the range of 0.05 to 0.1 tonnes of particles per second. Alternatively, it can be 0.01 to 0.05 tonnes of particles per second, 0.05 to 0.1 tonnes of particles per second, 0.1 to 0.2 tonnes of particles per second, or any range therebetween. In an embodiment, the diameter of the unloading valve is in the range of 6 inches (152 mm) to 20 inches (508 mm). Alternatively, it can be 6 inches (152 mm) to 8 inches (203.2 mm), 8 inches (203.2 mm) to 14 inches (355.6 mm), 14 inches (355.6 mm) to 20 inches (508 mm), or any range therebetween.

[0095] The particles emitted through the system contain solid polymer products (such as any polymer products described herein). In some cases, the particles may primarily contain solid polymer products and may also include small amounts of one or more solid catalyst components.

[0096] Furthermore, although the discussion in this paper primarily concerns fluidized bed polymerization reactors, it is believed that the principles described herein can also be applied to other industrial fluidized bed environments.

[0097] Additional implementation plan

[0098] Therefore, this disclosure relates to methods for discharging polymer resin products from a fluidized bed reactor. The methods and systems may include any of the various features disclosed herein, including one or more of the following embodiments.

[0099] Implementation Scheme 1. An apparatus comprising: a reactor, including: a distributor plate; a reactor neck; a reactor straight section having a height H defined from the distributor plate to the reactor neck; a liquid disposed above the distributor plate and having a liquid height; and a fluidized bed comprising a plurality of particles (optionally wherein the particles comprise a polymer product); and a product unloading line fluidly connected to the reactor and a product discharge tank, wherein the product unloading line is configured to discharge the particles to the product discharge tank, and wherein the product unloading line is disposed on the reactor straight section in a range of greater than 5% to about 95% of the height H (e.g., at about 10%, 15%, 20%, 25%, 3%) of the height H. The lower limit of any one of 0%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% to the upper limit of any one of height H, which is approximately 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95%, wherein the range from any of the aforementioned lower limit to any of the aforementioned upper limit is envisioned, considering the range from any of the aforementioned lower limit to any of the aforementioned upper limit, such as 20% to 50%H, or 25% to 35%H, or 30% to 70%H, or 35% to 55%H, or 20% to 80%H, etc.) at height.

[0100] Implementation Scheme 2. The apparatus of Implementation Scheme 1 further includes a return line fluidly coupled to the product discharge tank and the reactor straight section, wherein the return line is located on the reactor straight section at a position corresponding to approximately 80% to approximately 100% of the height H, and wherein the return line is located on the reactor straight section above the product unloading line.

[0101] Implementation Scheme 3. The device of any one of Implementation Schemes 1-2 further includes a second product unloading line fluidly coupled to the reactor and the product discharge tank and / or the second product discharge tank, wherein the second product unloading line is positioned on the straight section of the reactor at a height between the first product unloading line and the return line.

[0102] Implementation Scheme 4. The apparatus of Implementation Scheme 2 further includes a second product unloading line fluidly coupled to the reactor and the product discharge tank and / or the second product discharge tank, wherein the second product unloading line is arranged on the straight section of the reactor at a height corresponding to less than about 5%H.

[0103] Implementation Scheme 5. The apparatus of Implementation Scheme 4 further includes a third product unloading line fluidly coupled to any one of the reactor and the product discharge tank, the second product discharge tank and / or the third product discharge tank, wherein the third product unloading tank is located on the straight section of the reactor at a height between the second product unloading line and the return line.

[0104] Implementation Scheme 6. The apparatus of Implementation Scheme 3, wherein the product unloading line and / or the second product unloading line comprises a dielectric material disposed on the inner surface of the product unloading line.

[0105] Implementation Scheme 7. The apparatus of Implementation Scheme 6, wherein the dielectric material comprises at least one material selected from titanium dioxide, silicon dioxide, aluminum oxide, and combinations thereof.

[0106] Implementation Scheme 8. The device of any one of Implementation Schemes 1-6, wherein the product discharge tank has a top and a bottom, wherein the product discharge tank includes an inlet at the top that is fluidly connected to the product unloading line, and wherein the product discharge tank includes an outlet that is fluidly coupled to the product spray tank.

[0107] Implementation Scheme 9. A method comprising: introducing a feed stream containing a monomer into a reactor, the reactor comprising: a distributor plate; a reactor neck; a reactor straight section having a height H defined from the distributor plate to the reactor neck; a liquid disposed above the distributor plate and having a liquid height; and a fluidized bed comprising a plurality of particles (optionally wherein the particles comprise a polymer product); polymerizing at least a portion of the monomer to produce additional particles; and extracting a product stream containing at least a portion of the particles from the reactor to a product discharge tank, wherein the product stream is extracted via a product unloading line fluidly connected to the reactor and the product discharge tank, and wherein the product unloading line is disposed on the reactor straight section at a height H of greater than 5% to about 95%. Within a range (e.g., at a height of approximately 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% of height H, from a lower limit to an upper limit of approximately 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% of height H, where the range from any of the aforementioned lower limit to any of the aforementioned upper limit is envisioned, considering the range from any of the aforementioned lower limit to any of the aforementioned upper limit, such as 20% to 50%H, or 25% to 35%H, or 30% to 70%H, or 35% to 55%H, or 20% to 80%H, etc.).

[0108] Implementation Scheme 10. The method of Implementation Scheme 9 further includes extracting a second product stream via a second product unloading line fluidly coupled to the reactor and the product discharge tank and / or the second product discharge tank, wherein the second product unloading line is arranged on the straight section of the reactor at a height corresponding to less than about 5%H.

[0109] Implementation Scheme 11. The method of Implementation Scheme 10, wherein the product stream and the second product stream are simultaneously extracted from the reactor.

[0110] Implementation Scheme 12. The method of Implementation Scheme 10, wherein the product stream and the second product stream are extracted from the reactor separately.

[0111] Implementation Scheme 13. The method of Implementation Scheme 10, wherein the product unloading line and / or the second product unloading line comprises a dielectric material disposed inside the product unloading line.

[0112] Implementation Scheme 14. The method of Implementation Scheme 13, wherein the dielectric material comprises at least one material selected from titanium dioxide, silicon dioxide, aluminum oxide, and combinations thereof.

[0113] Implementation Scheme 15. The method of Implementation Scheme 10, wherein the reactor further comprises: a dome positioned above the neck of the reactor; a circulating fluid line fluidly coupled to the dome and the bottom of the distributor plate; and means for monitoring the carry-over rate of the particles from the dome into the circulating fluid line.

[0114] Implementation Scheme 16. The method of Implementation Scheme 15, wherein the device for monitoring the carryover rate includes a circulating gas static probe and / or an acoustic probe.

[0115] Implementation Scheme 17. The method of Implementation Scheme 15 further includes extracting the product stream from the product unloading line in response to the carryover rate of the particles.

[0116] Implementation Scheme 18. The method of Implementation Scheme 10 further includes measuring the agglomeration rate of the particles and extracting the product stream from the product unloading line in response to the agglomeration rate of the particles.

[0117] Implementation Scheme 19. The method of Implementation Scheme 18, wherein measuring the agglomeration rate of the particles includes using an acoustic probe and / or a computer vision system.

[0118] Implementation Scheme 20. The method of Implementation Scheme 9, wherein the reactor further includes a return line fluidly coupled to the product discharge tank and the reactor straight section, wherein the return line is located on the reactor straight section at a position corresponding to about 80% to about 100% of the height H, and wherein the return line is located on the reactor straight section above the product unloading line.

[0119] Implementation Scheme 21. The method of any one of Implementation Schemes 9-20, wherein the particles comprise a polymer product.

[0120] Implementation Scheme 22. The method of Implementation Scheme 21, wherein the polymer product comprises an ethylene homopolymer or a copolymer of ethylene with one or more olefin comonomers.

[0121] Embodiment 23. The method of Embodiment 22, wherein the one or more olefin comonomers are selected from 1-butene, 1-hexene, and 1-octene. To facilitate a better understanding of the invention, the following examples of certain aspects of some embodiments are provided. These examples should in no way be construed as limiting or restricting the entire scope of this disclosure.

[0122] Example

[0123] In this embodiment, sample data from the gas-phase fluidized bed reactor is used as input for computational fluid dynamics computer simulations. Simulations are performed at different heights of the product nozzle discharge positions along the vertical height of the reactor. The simulations are used to calculate the estimated resin discharge time at each nozzle discharge position, the estimated resin temperature difference at the discharge position compared to the median bed temperature across the entire bed, and the estimated liquid loading of the product. Gas-phase fluidized bed reactors are typically operated in a "wet" environment, where, for the specific resin product grade and / or type of catalyst used, reactor conditions and feed composition are set such that a portion of the gas phase condenses back into the liquid (this is sometimes referred to as condensation mode operation of such reactors). In this embodiment, resin vs. bed temperature simulations are performed using three condensation assumptions: 25, 20, and 15 wt% condensation.

[0124] The simulation results are shown in Table 1. In Table 1, the nozzle discharge position is the vertical height (in feet) above the distributor plate (defined as 0 ft). % of the straight section is the percentage of the discharge nozzle height relative to the height H of the straight section of the gas-phase fluidized bed reactor, and may also be referred to as %H, as done throughout this disclosure. The estimated resin discharge time is the time period (in seconds) used for discharging resin (e.g., the time for discharging a batch or a single "dumping" of resin via the discharge line(s) before the valves on the discharge line(s) are closed). Effective capacity is an estimated amount of product that can be discharged from the nozzle position relative to a control (defined as having 100% effective capacity) for comparison. As the nozzle position height increases, the discharge power decreases, resulting in a decrease in the capacity of product discharged from the reactor. The estimated liquid load is the amount of liquid absorbed into the solid product particles, reported as the weight of the total weight of solids and liquids measured at the discharge nozzle.

[0125] Table 1

[0126]

[0127] In addition, for various %H values, a plot of expected emission time vs. emission height (as %H) was drawn, and plotted on... Figure 4 In the middle; similarly, Figure 5 A similar plot is presented, showing expected emission time versus altitude (in feet). (By reviewing...) Figure 4 and Figure 5 The model estimates, along with the control and model discharge times reported in Table 1 for cases 1-4, indicate that discharging the product from higher positions in the reactor corresponds to hotter and drier product particles. For example, in case 4, the discharge temperature was observed to be close to the median bed temperature, while in case 1, the discharge temperature was relatively cooler than the median bed temperature. Furthermore, the liquid loading was lower in case 4 compared to the control. It was further observed that the temperature variation was relatively stable for each of the 15 wt%, 20 wt%, and 25 wt% condensation cases. For the cases tested, case 3 offered the relatively highest performance compared to cases 1, 2, and 4, where the liquid loading was close to that of case 4, while having almost the same effective capacity as case 2. This reflects a good balance between slower discharge (at greater heights) and greater prevention of agglomeration (discharging particles with relatively higher temperatures at greater heights, and further with relatively lower liquid loadings), and indicates that a particularly advantageous location for the product unloading line is at a height ranging from approximately 25%H to approximately 35%H.

[0128] While the invention and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations may be made herein without departing from the spirit and scope of the invention as defined by the appended claims. The scopes of the various features and properties disclosed herein are listed as progressively narrowing scopes. However, it should be understood that any lower endpoint of any scope may be paired with any upper endpoint of the same feature or property, and such pairing is also intended as disclosed herein. All patents, testing procedures, and other documents referenced in this application are fully incorporated herein by reference to allow for all rights of such incorporation. Furthermore, the scope of this application is not intended to be limited to specific embodiments of the processes, machines, apparatuses, methods, and / or steps described in the specification. As will be readily understood by those skilled in the art from the disclosure of this invention, according to the invention, processes, machines, apparatuses, methods, and / or steps, whether currently existing or later developed, can perform substantially the same function or achieve substantially the same results as the corresponding embodiments described herein. Therefore, the appended claims are intended to include such processes, machines, apparatuses, methods, and / or steps within their scope.

Claims

1. Equipment, including: The reactor includes: Distributor board; Reactor neck; A reactor straight section having a height H defined from the distributor plate to the reactor neck; Liquid arranged above the distributor plate and having a liquid height; and Fluidized beds containing multiple particles; and A product unloading line is fluidly connected to the reactor and the product discharge tank, wherein the product unloading line is configured to discharge the particles into the product discharge tank, and wherein the product unloading line is positioned on the straight section of the reactor at a height ranging from more than 5% to about 95% of the height H.

2. The apparatus of claim 1, further comprising a return line fluidly coupled to the product discharge tank and the reactor straight section, wherein the return line is located on the reactor straight section at a position corresponding to about 80% to about 100% of the height H, and wherein the return line is located on the reactor straight section above the product unloading line.

3. The apparatus of claim 2, further comprising a second product unloading line fluidly coupled to the reactor and the product discharge tank and / or the second product discharge tank, wherein the second product unloading line is positioned on the straight section of the reactor at a height between the first product unloading line and the return line.

4. The apparatus of claim 2, further comprising a second product unloading line fluidly coupled to the reactor and the product discharge tank and / or the second product discharge tank, wherein the second product unloading line is positioned on the straight section of the reactor at a height corresponding to less than 5%H.

5. The apparatus of claim 4, further comprising a third product unloading line fluidly coupled to the reactor and any one of the product discharge tank, the second product discharge tank and / or the third product discharge tank, wherein the third product unloading tank is positioned on the straight section of the reactor at a height between the second product unloading line and the return line.

6. The apparatus of claim 1 or any one of claims 2-5, wherein one or more of the product unloading lines comprise a dielectric material disposed on the inner surface of the product unloading lines.

7. The device of claim 6, wherein the dielectric material comprises at least one material selected from titanium dioxide, silicon dioxide, aluminum oxide, and combinations thereof.

8. The device of claim 1 or any one of claims 2-7, wherein the product discharge tank has a top and a bottom, wherein the product discharge tank includes an inlet at the top that is fluidly connected to the product unloading line, and wherein the product discharge tank includes an outlet that is fluidly coupled to the product spray tank.

9. Methods, including: A feed stream containing monomers is introduced into a reactor, the reactor comprising: Distributor board; Reactor neck; A reactor straight section having a height H defined from the distributor plate to the reactor neck; Liquid arranged above the distributor plate and having a liquid height; and Fluidized bed containing multiple particles; At least a portion of the monomer is polymerized to produce additional electrically insulating particles; and A product stream containing at least a portion of the electrically insulating particles is extracted from the reactor to a product discharge tank, wherein the product stream is extracted via a product unloading line fluidly connected to the reactor and the product discharge tank, and wherein the product unloading line is positioned on a straight section of the reactor at a height ranging from more than 5% to about 95% of the height H.

10. The method of claim 9, further comprising extracting a second product stream via a second product unloading line fluidly coupled to the reactor and the product discharge tank and / or the second product discharge tank, wherein the second product unloading line is positioned on the straight section of the reactor at a height corresponding to less than 5%H.

11. The method of claim 10, wherein the product stream and the second product stream are simultaneously extracted from the reactor.

12. The method of claim 10, wherein the product stream and the second product stream are extracted from the reactor respectively.

13. The method of claim 9 or any one of claims 10-12, wherein one or more of the product unloading lines comprise a dielectric material disposed inside the product unloading lines.

14. The method of claim 13, wherein the dielectric material comprises at least one material selected from titanium dioxide, silicon dioxide, aluminum oxide, polymer coatings, and combinations thereof.

15. The method of claim 10, wherein the reactor further comprises: A dome arranged above the neck of the reactor; Fluid coupling to the circulating fluid lines at the bottom of the dome and the distributor plate; and A device for monitoring the carryover rate of the electrically insulating particles from the dome into the circulating fluid pipeline.

16. The method of claim 15, wherein the device for monitoring the carryover rate comprises a circulating gas static probe and / or an acoustic probe.

17. The method of claim 15, further comprising extracting the product stream from the product unloading line in response to the carrying rate of the electrically insulating particles.

18. The method of claim 10, further comprising measuring the agglomeration rate of the electrically insulating particles and extracting the product stream from the product unloading line in response to the agglomeration rate of the electrically insulating particles.

19. The method of claim 18, wherein measuring the agglomeration rate of the electrically insulating particles comprises using an acoustic probe and / or a computer vision system.

20. The method of claim 9, wherein the reactor further comprises a return line fluidly coupled to the product discharge tank and the reactor straight section, wherein the return line is located on the reactor straight section at a position corresponding to about 80% to about 100% of the height H, and wherein the return line is located on the reactor straight section above the product unloading line.

Images