Compressible liquid diluent in polyolefin polymerization.
Abstract
La presente invención se relaciona con un método para manufacturar una poliolefina y un sistema para implementar el método. El método comprende combinar un catalizador con una mezcla de diluyente que contiene un diluyente y un monómero de olefina en un reactor de polimerización. El diluyente puede comprender propano, butano o isobutano, o una combinación de los mismos. El reactor de polimerización se opera a una presión arriba de una presión crítica del diluyente, pero debajo de la temperatura crítica del diluyente.

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Expires 28 January 2031.
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7 claims: 2 independent, 5 dependent
- 1NOVEDAD DE LA INVENCIÓN_ Habiendo descrito el presente invento, se considera como una novedad y, por lo tanto, se reclama como propiedad lo contenido en las siguientes. REIVINDICACIONES 1. Un método para operar un reactor de poliolefina, que comprende:combinar un catalizador con una mezcla diluyente en un reactor de polimerización, en donde la mezcla diluyente comprende un diluyente y un monómero de defina;operar el reactor de polimerización por arriba de una presión crítica de la mezcla diluyente y por abajo de una temperatura crítica de la mezcla diluyente;y formar una suspensión que comprende partículas de poliolefina y la mezcla diluyente.
- 2El método de conformidad con la reivindicación 1, caracterizado porque (i) el diluyente comprende propano, butano o isobutano, o cualquier combinación de los mismos;o (ii) la mezcla diluyente comprende una mezcla de dos o más hidrocarburos, en donde cada uno de los hidrocarburos tiene independientemente seis o menos carbonos, y en donde la composición de la mezcla se usa para ajustar una presión crítica de la mezcla diluyente. IMPI
- 3El método de conformidad con la reivindicación 1, caracterizado porque comprende remover continuamente las partículas de poliolefina del reactor durante el proceso de polimerización.
- 4El método de conformidad con la reivindicación 1, caracterizado porque comprende inyectar un agente asesino en el reactor para disminuir una tasa de producción.
- 5El método de conformidad con la reivindicación 1, caracterizado porque comprende (i) operar el reactor de i polimerización a una temperatura de entre 77°C (170°F) y 91°C (195°F), a una presión absoluta mayor de 5.2 MPa (750 psi), y en donde el diluyente comprende propano;o (ii) operar el reactor de polimerización a una temperatura de entre 77°C (170°F) y 91°C (195°F), a una presión absoluta de entre 5.5 MPa (800 psi) y 6.2 MPa (900 psi), y en donde el diluyente comprende propano.
- 6Un proceso para manufacturar un producto que comprende una poliolefina, caracterizado porque comprende:manufacturar un producto, por lo menos una porción del cual comprende una poliolefina, en donde la poliolefina se produce por un método que comprende: combinar un catalizador con una mezcla diluyente en un reactor de polimerización, en donde la mezcla diluyente comprende un diluyente y un monómero de olefina;IMPI operar el reactor de polimerización por arriba de una presión crítica de la mezcla diluyente, y por abajo de una temperatura critica de la mezcla diluyente;y formar una suspensión que comprende partículas de poliolefina y la mezcla diluyente.
- 7El proceso de conformidad con la reivindicación 1, caracterizado porque comprende:(i) operar el reactor a una temperatura de entre 77°C (170°F) y 91°C (195°F) , a una presión absoluta superior a 5.2 MPa (750 psi) , y en donde el diluyente comprende propano;o (ii) operar el reactor a una temperatura de entre 77°C (170°F) y 91°C (195°F), a una presión absoluta superior a 3.4 MPa (500 psi), y en donde el diluyente comprende isobutano. ΙΜΡΙ£3> INSTITUTO MEXICANO Ο X- DE LA PROPIEDAD -7 o INDUSTRIAL
Independent claims7
563 paragraphs in 56 sections, as filed
(54) Title: COMPRESSIBLE LIQUID THINNER IN POLYOLEFIN POLYMERIZATION. (54) Title: COMPRESSIBLE LIQUID DILUENT IN POLYOLEFIN POLYMERIZATION.
(57) Summary
The present invention relates to a method for manufacturing a polyolefin and a system for implementing the method. The method comprises combining a catalyst with a diluent mixture containing a diluent and an olefin monomer in a polymerization reactor. The diluent can comprise propane, butane or isobutane, or a combination thereof. The polymerization reactor is operated at a pressure above a critical diluent pressure, but below the critical diluent temperature.
(57) Abstract
Embodiments of the present application provide a method for manufacturing a polyolefin and a system for implementing the method. The method comprises combining a catalyst with a diluent mixture containing a diluent and an olefin monomer in a polymerization reactor. The diluent may comprise propane, butane, or isobutane, or a combination thereof. The polymerization reactor is operated at a pressure above a critical pressure of the diluent, but below the critical temperature of the diluent.
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PATENT TITLE NO. 339043
I KNOW_
ÍKHáá M ÍCÍÍSÍMÍA
Headlines):
Home:
Denomination:
Classification:
Ini
Mexican Institute of Property
Industrial ftfl
CHEVRON PHILLIPS CHEMICAL COMPANY LP
10001 Six Pines Drive, The Woodlands, Texas, 77380, USA
COMPRESSIBLE LIQUID THINNER IN THE POLYMERIZATION OF
POLYOLEFINES.
lnt.CI.8: C08F10 / 00; C08F2 / 14
SOLDITION
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MX / a / 2O12
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i
..... i 1 '
Internal filing date for January 2011
PRIORITY
Number:
12/699,729
Date:
February 2010: Twenty «the reference patent Vencilnien milk becomes conformity with article 23 of I <ntada from the date of pressure.
jilen subscribes the present Title I ce with industrial piety □ (Official Journal of the Federation (D.Ci> 2031 (articles 1 ° 2 ° section V, 6 ° section III, and 59 of the Industrial Property Law).
This patent is valid for twenty unfeasible years, il and will be subject to the payment of the fee to keep alive the: 101/2004, 06/16/2005, 2i or a), subsection iii) 4 ° β articles β *
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1/2006, /05/2009,06/01/2010,
12 ° sections> I and III of the Regulations issued on 07/01/2002, 1! ) 7/2004, I / 07/2004 and 7/09/2007); Articles 1 ', I Instituí 3' and 5 'and 7 ° bis 2 of fey de la 996, 12/26/1997, 11 * 5/1999. 1/2012); Articles 1, 3, Action V. Industrial Property (DOF 1 * 2/1999, BrTV subsection a), sub subsection iii), 16 fraction I and III and
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enerales
Deputies, Coordinator, Divisional Directors, Regional Office Holders, Divisional Deputy Directors, Departmental Coordinators and other subordinates of the Mexican Institute of Property Ijádustnal .. (DOF 12/15/1999, amended on 02/04/2000, 07/29/29 2004, 04/08/2004 and 09/13/2007). '' '
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Issue Date: May 5, 2016
DIVISIONAL TOR FOR EXAMINATION OF PATENT FUND, AREAS, ELECTRICAL AND INDUSTRIAL DESIGN RECORDS AND
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Arenal No. 550, Floor 1.
Col. Pueblo Santa María Tepepan, Xochímiico, CP 16020,
Mexico City
Tei (55) 53 34 07 00 www.impi gpbrnx
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MX / 2016/36552
COMPATIBLE LIQUID THINNER IN
POLYOLEFINS
POLIM ^ j ^ jfoJ
MEXICAN INSTITUTE OF PROPERTY
INDUSTRIAL
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BACKGROUND OF THE INVENTION
The present techniques are generally related to the production of polyolefins. More particularly, the present techniques relate to operating regimes for a polymerization of polyolefins, including the operation of. Polyolefin polymerization reactor systems at pressures greater than a critical pressure of the diluent used in the reactor.
This section is intended to introduce the reader to aspects of the technique that may be related to aspects of the present techniques, which are described and / or claimed below. This description is believed to be useful in providing the reader with the foregoing information to facilitate a better understanding of the different aspects of the present techniques. Therefore, it should be understood that these statements will be read from
0 this point of view and not as admissions to the prior art.
As chemical and petrochemical technologies have advanced, the products of these technologies have grown in prevailing society. In particular, since
IMPI
INSTITUTO MEXICANO have advanced techniques for the union of · simple molecular construction in long chains (or _ polymeric products have been incorporated in an increased way in different daily articles. For example, polyolefin polymers, such as polyethylene, polypropylene, and their copolymers with each other and other monomers, are used for retail and pharmaceutical packaging, food and beverage packaging (such as juice and soda bottles), household containers ( such as buckets and boxes), household items (such as appliances, furniture, rugs and toys), automotive components, pipes, ducts and various industrial products.
Specific types of polyolefins, such as high-density polyethylene (HDPE), have particular applications in the manufacture of injection molded and blow molded objects, such as food and beverage containers, film, and plastic tubing. Other types of polyolefins, such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), isotactic polypropylene (iPP), and syndiotactic polypropylene (sPP) are also suitable for similar applications.
The mechanical requirements of the application, such as tensile stress and density and / or the requirements
<img file="MX339043B_D0010.tif" />
chemicals, such as thermal stability, molecular weight, and
IMPI ,,,,. Mexican iNsrmnp chemical reactivity, can determine polyolefin is appropriate. __ _______
A benefit of polyolefin constructions, as can be deduced from the list of previous uses, is that it is generally not reactive with the articles or products with which it is in contact. This allows polyolefin products to be used in residential, commercial, and industrial contexts, including food and beverage storage and transportation, consumer electronics, agriculture, shipbuilding, and vehicular. The wide variety of residential, commercial, and industrial uses for polyolefins has resulted in substantial demand for raw polyolefins, which can be extruded, injected, weighed, or otherwise formed into a consumable product or component.
To meet this demand, there are different processes by which olefins can polymerize to form polyolefins. These processes can be performed near or in petrochemical facilities, which have ready access for short chain define molecules (monomers and comonomers), such as ethylene, propylene, butene, pentene, hexene, octene, decene and other blocks. of construction of the longest polyolefin polymers. These monomers and comonomers can
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IMPI polymerize in a polymerization reactor ¥<sup>T</sup>$ ^ $ g $ | ^
INDUSTRIAL and / or a gas phase polymerization guide, to form a product that includes solid polymer particulates (polyolefin), which can be called pellets or granules. The pellet may possess one or more melt, physical, rheological, and / or mechanical properties of interest, such as density, melt index (MI), melt flow rate (MFR), copolymer content, comonomer content, modulus, and crystallinity . The reaction conditions within the reactor, such as temperature, pressure, guimic concentrations, polymer production speed, etc., can be selected to obtain the desired properties of the pellet, and through these properties of the pellet, control the properties of the product. for end use.
In addition to one or more of the define monomers, a catalyst may be added to the reactor to facilitate polymerization of the monomers. For example, the catalyst may be a particle added by means of a reactor feed stream and, once added, suspended in the liquid medium within the reactor. An example of such a catalyst in a Zeigler-Natta catalyst containing a tetravalent titanium complex on a silica support. In addition, a diluent can be introduced into
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MEXICAN INSTITUTE the reactor. The diluent can be a hydro dS i such as isobutane, propane, n-pentane, i-nentane. nonppn-i-an ^ and n-hexane, which is liquid at reaction conditions.
However, some polymerization processes cannot employ a separate diluent, such as in the case of selected examples of polypropylene production, where the propylene monomer itself acts as the diluent.
A diluent for the loop process may have a low tendency to dissolve the polymer pellets and maintain adequate circulation in a loop reactor.
The diluent also transfers heat from the polymerization, taking place in the pellet-catalyst particles.
Furthermore, a diluent can have a high vapor pressure and a low heat of polymerization, for ease of devolatilization of the polymer pellet particles, so that the resulting polymer is free of residual diluent.
The discharge from the reactor may include the polymer pellet, as well as non-polymer components, such as the unreacted olefin monomer (and comonomer), diluent, etc. In the case of polyethylene production, the non-polymeric components can include a diluent, such as isobutane, which has a small amount of unreacted ethylene (eg, 5% by weight). This
<img file="MX339043B_D0013.tif" />
discharge current is generally processed
INDUSTRIAL diluent / monomer recovery system, to separate non-polymer components from the reactor pellet.
The recovered diluent, unreacted monomer, and other non-polymer components of the recovery system can be treated, for example, by treatment beds and / or a fractionation system and returned as a purified or treated feed to the reactor. Some of the components may be called or returned to the supplier, such as to an olefin manufacturing plant or oil refinery. As for the recovered polymer (solids), the polymer can be treated to deactivate the residual catalyst, remove trapped hydrocarbons, dry the polymer, and granulate the polymer in an extruder, etc., before the polymer is shipped to the customer.
Liquid phase polymerization reactors can be run at operating intervals that keep the contents in a liquid phase below the critical temperature and pressure of the diluent. However, this may not be optimal for some polymer systems. For example, some polymers can be soluble in liquid diluents under these conditions, causing blockage in the reactor.
In other cases, bubbles may form under current conditions, causing cavitation of the impeller blades
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IMPI for pump blades for loss of circulation. It is driving, forcing production.
cavitation
OF THE PROPUDITY
INDUSTRIAL - expensive repairs already
SHORT DESCRIPTION
OF THE FIGURES
The advantages of the techniques may become apparent upon reading the following detailed description and referring to the figures.
Figure 1 is a block diagram of an example of a polyolefin production process, according to the modalities of the present techniques;
Figure 2 is a general phase diagram for a pure light hydrocarbon, such as propane or isobutane used in the prophetic examples of the present techniques;
Figure 3 is a graph showing the calculated critical temperature and critical pressure ratios for the ethylene content in a propane diluent, according to the prophetic examples of the present techniques;
Figure 4 is a graph showing the calculated critical points at different concentrations of ethylene in propane, according to the prophetic examples of the present techniques;
Figure 5 is a graph showing the points <sup>8</sup> Critical IJML ΡI calculated for different coi * fg ^ GE'jf ^ g3gn ^^^^ g¿S ethylene in a propane diluent containing 1% by weight of
1-hexene, according to the prophetic examples of the present techniques;
Figure 6 is a graph showing the effects on the calculated critical points of the change of the hexene concentration or the addition of hydrogen to a propane / ethylene diluent mixture, according to the prophetic examples of the present techniques;
Figure 7 is a graph showing the calculated semi-super critical or compressible liquid region of the phase diagram, for a propane-based diluent, relative to diluent mixtures of different compositions, according to the prophetic examples of the present techniques;
Figure 8 is a process flow diagram of an example of a reactor system and a diluent / monomer recovery system of the polyolefin manufacturing system of Figure 1, in accordance with the embodiments of the present techniques;
Figure 9 is a diagrammatic representation of the example of the polymerization reactor of Figure 8, showing the flow of the cooling medium through the reactor jackets, in accordance with the embodiments of the present techniques;
<sup>9</sup> IMPI _
Figure 10 is a flow chart iNsdwTo ^ gugg¡gsl & ~ ^
ΓΝΓ) '. NTRIAL example of a cooling system used in the temperature control of the polymerization reactor of Figure 9, according to the modalities of the present techniques;
Figure 11 is a diagrammatic representation of an example of a continuous intake discharge from the polymerization reactor of Figure 8, in accordance with the embodiments of the present techniques;
Figure 12 is a cross section along line 11-11 of Figure 11, showing an arrangement of a ram valve in the continuous intake discharge assembly, in accordance with the modalities of the present techniques;
Figure 13 is a diagrammatic representation of a tangential location for continuous tapping mounting, according to the modalities of the present techniques; and
Figure 14 is a process flow diagram of the extrusion / discharge system of Figure 1, according to the modalities of the present techniques.
DETAILED DESCRIPTION OF SPECIFIC MODALITIES
One or more specific modalities of the present techniques will be described below. In an effort to provide a concise description of these modalities, not all features are described in the specification.
IMPI
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I should apredl<sup>8</sup>^^^, ^^ of a real implementation.
Development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the specific goals of the developer, such as compliance with system-related or business-related constraints. , which can vary from one implementation to another. Furthermore, it should be appreciated that such a development effort could be complex and time consuming, but would nevertheless be a routine design, manufacture and manufacturing task for those skilled in the art who have the benefit of this disclosure.
In the present techniques, the liquid phase of the suspension of the polyolefin polymer in a polyolefin polymerization reactor (for example, in a circuit suspension reactor, autoclave type reactor, continuously stirred reactor vessel, other liquid phase reactors etc.) generally stays above its critical pressure even below its critical temperature. In general, the critical temperature of a solvent is the temperature at which all intermolecular forces drop to zero, and the distinction between a liquid and a gas no longer exists. Critical pressure is the vapor pressure of a solvent at
<img file="MX339043B_D0016.tif" />
IMPI critical temperature. Above the critical temperature below, the liquid phase becomes compressible. Temperature and critical pressure are described in more detail below in Section II.
Advantageously, as described with respect to Figure 2 below, such an operating regime can lead to reduced costs and improved operability associated with the production of polyolefin, for example, polyethylene, polypropylene and their copolymers, etc. Specifically, operation below the critical temperature can prevent sintering of linear low-density polyethylene (LLDPE), which could reduce clogging. Furthermore, operating above the critical pressure of the mixture can prevent the formation of two phases in the diluent, which could prevent the formation of a headspace in the reactor or cavitation of the circulation pump.
Using propane as a diluent in this operating regimen can provide additional benefits. In general, propane mixtures will have a lower density than higher molecular weight diluents, such as isobutane, which could decrease the energy used to circulate (i.e. around the pump fluid) the reactor as much as 3-10 % for the same pump configuration. For example, an isobutane diluent mixture that
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hydrogen, at a temperature it contains approximately
<td>approximately</td><td> 1.5%</td><td>in mol</td>
<td>from approximadam</td><td>entity</td><td>208 ° F</td>
<td>approximately</td><td> 800</td><td>psia,</td>
<td>approximately</td><td> 0.35</td><td>g / cm<sup>3</sup>.</td>
<td>similar propane</td><td>low</td><td>my</td>
(97.7 ° C) and a pressure of can have a density of
Conversely, a mixture of these conditions can only have a density of approximately 0.27 g / cm<sup>3</sup>. Lower density propane may allow higher average reactor solids, as measured by techniques known in the literature. Propane is also less efficient at dissolving LLDPE than isobutane (for example, with a solubility parameter of about 5.3 (cal / cm<sup>3</sup>)<sup>0</sup>’<sup>5</sup> for propane, against approximately 5.9 (cal / cm<sup>3</sup>)<sup>0</sup>’<sup>5</sup> for isobutane), which could improve solvent removal, or expansion, of the low molecular polymer, reducing the potential for clogging in downstream equipment. Furthermore, propane is less soluble in polyethylene (PE) than isobutane. For example, at about 208 ° F and about 800 psia, PE is a propane diluent that could contain approximately 2.8% by weight propane, while PE in an isobutane diluent could contain approximately 6.1% by weight isobutane. The difference in solubility can result in a harder, less adhesive polymer in diluents than
<img file="MX339043B_D0018.tif" />
i IMPI propane against isobutans diluents |., x ¥ Jei -ScuAl;
MEXICAN INSTITUTE
FROM THE FROMiLiAü V * -MS £ Í “INDUSTRIAL may decrease the potential for clogging. For at least these reasons, among others, the present operating techniques with a propane diluent in the compressible liquid regime, can accommodate improved implementation and operation of reactor systems relatively large-scale. For example, circuit suspension reactors with a volume greater than, for example, 70,000 gallons.
In general, the compressible liquid rate, that is, when the liquid phase of the polymer suspension is kept above its critical pressure even below its critical temperature, can be labeled a semi-supercritical or quasi-supercritical fluid. In some cases, the liquid polymer suspension phase is primarily diluent, for example, an inert hydrocarbon. Furthermore, the liquid phase can include monomer, comonomer, hydrogen and other components. The critical pressure and critical temperature of the liquid phase in the polymer suspension will vary as a function of the diluent (s) employed and the concentrations of the components in the liquid phase of the polymer suspension, eg hydrocarbon, diluent, monomer, comonomer, etc. Therefore, the choice of the diluent or the combinations of diluents, used in the
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polymer suspension circulating in the rsua-fíxtostxicteo
OF THE PROPERTY
INDUSTRIAL -
INDUSTRIAL PROPERTY IMPI ¿Kí xiCa® ο can be selected based on a desired critical temperature corresponding, for example, to the operating temperature ranges of the circuit reactor.
The diluent can be an inert hydrocarbon that is a liquid under the reaction conditions, such as isobutane, propane, n-pentane, i-pentane, neopentane, n-hexane, heptanes, cyclohexane, cyclopentane, methylcyclopentane, ethylcyclohexane, isooctane, and the like. . In general, a purpose of the diluent is to suspend the catalyst and polymer particles within the reactor. The diluent can be chosen to provide a desired critical temperature and critical pressure for the liquid phase in the polymer slurry and to facilitate carrying out the operations of the loop reactor in a semi-supercritical region. In addition, a mixture of diluents can be used to adjust the critical pressure of the liquid phase.
The use of diluents in this semi-supercritical regimen can provide a number of advantages over the use of diluents within previous operating regimes. For example, in the production of linear low-density polyethylene (LLDPE), too high an operating temperature can cause clogging due to increased<sup>1</sup> solubility in the diluent or polymer melt,
<img file="MX339043B_D0020.tif" />
among other things. Therefore, it can s
INDUSTRIAL
IMPI
INDUSTRIAL use of supercritical thinners that have too high a critical temperature. In addition, compared to operation below supercritical temperature and pressure, diluents in the present semi-supercritical operation regime generally have some compressibility, which may reduce bubble formation in the circulating suspension in the loop reactor. and provide other benefits. Furthermore, some diluents, such as propane, have lower densities than others, as described above for isobutane, requiring less power from the circulation system.
Furthermore, the solubility of a polyethylene polymer in propane may be less than other diluents, such as isobutane, which could decrease the potential to soften and swell the polymer in the reactor. Finally, operation above critical pressure can facilitate diluent removal / recovery, advantageously decreasing energy efficiency in diluent expansion / recovery downstream of the reactor. More specifically, using a diluent at a higher pressure will generally allow expansion to a lower energy yield, facilitating solvent removal.
However, the ιθ IMPI operation with diluents having a pressure of vap'b ^^ Jg ^^ Jt can also be problematic
INDUSTRIAL propane. For example, the critical pressure for propane is
<img file="MX339043B_D0021.tif" />
approximately 615 psia (4,240.2 kPa) at the critical temperature of approximately 206 ° C, while the critical pressure for isobutane is approximately 530 psia (3,654.2 kPa) at the critical temperature of approximately
<td> 275</td><td>° C. Of</td><td>this way,</td><td>the</td><td>propane</td><td>can</td><td>require more</td>
<td colspan="2">compression</td><td>that isobutane</td><td>and.</td><td>this</td><td>way,</td><td>may require</td>
<td>plus</td><td>Energy</td><td>to pressurize</td><td>the</td><td>propane</td><td>then</td><td>of removal</td>
<td>of</td><td colspan="3">the pellet so</td><td>than</td><td>can</td><td>condense and</td>
recirculate. This disadvantage can be compensated by recovering more than 50% or 80 to 90% by weight, or more than 90% of the recycled diluent at a sufficiently high pressure, so that it can be condensed without compression. Enhanced recovery can be accomplished by operating the separation vessel or cyclone at a relatively high pressure, such as greater than about 180 psia (1,241.05 kPa) and adding heat to the suspension with heated expansion lines (i.e., the reactor line to the tank evaporation or cyclone). The expanded propane can then be condensed in a heat exchanger without further compression.
To facilitate the description of the present techniques, the description is presented in sections. Section I provides an overview of an example of a
<img file="MX339043B_D0022.tif" />
IMPI
, .✓1 -.--. -, NUUblRÍAL production of polyolefin, in which a liquid phase r would be used. Section II describes the use of ~ Semi-supercritical Siluents in the production of polyolefins. Section III describes a polymerization reactor system that can employ semi-supercritical diluents. The section
IV describes the diluent / monomer recovery system that can recover unreacted diluent and monomer from the effluent discharged from the polymerization reactor. Section V focuses on cooling the polymerization reactor. Section VI describes examples of pumping systems for circuit reactors. The section
VII describes a continuous intake system for the removal of the polymer pellets and the diluent from the reactor. Section VIII describes the extrusion / discharge system that converts raw polyolefin particles to polyolefin granules for distribution to the customer.
Although the description may focus on the production of polyethylene and its copolymers, the techniques described can provide benefits when diluents are used in the production of other polyolefins, such as polypropylene, polybutylene, etc. Finally, it should be evident that the different techniques can be implemented in a multiplicity of combinations.
<img file="MX339043B_D0023.tif" />
is IMPI
- -,. .., MEXICAN INSTITUTE
I. Polyolefin production process - r & asa & r
In the production of polyolefin, the polymerization reactor (s), which polymerizes the monomer into polyolefin, and the extruder (s), which convert the polyolefin to polyolefin granules, can be continuous operations.
However, a variety of batch and continuous systems can be employed through the polyolefin process. An example of the nominal capacity for a typical polyolefin plant is approximately 900-1200 million pounds of polyolefin produced per year. Examples of hourly design speeds can be approximately
85,000 to 150,000 pounds of polymerized polyolefin per hour and 145,000 to 165,000 pounds of extruded polyolefin per hour.
Future reactors can produce as much as 280,000 a
320,000 pounds of polymerized polyolefin per hour. A benefit of large reactors may be lower unit costs (i.e. per unit mass, i.e. pound, of polyolefin) for capital investment to build the reactor system, as well as for fixed costs and costs of operation to maintain and operate the reactor, etc.
An example of a manufacturing process 10 for producing polyolefins, such as polyethylene homopolymer, polypropylene homopolymer and / or its copolymers, with others
<img file="MX339043B_D0024.tif" />
IMPI Mexican institute OF PROPERTY
INDUSTRIAL ___ monomers, sq represents on the block diagram of the
Figure 1. Different suppliers 12 can supply raw materials to reactor 14 to the manufacturing system by means of pipes, trucks, cylinders, drums, etc. Suppliers 12 may include off-site and / or on-site facilities, such as, for example, olefin plants, refineries, catalyst plants, and the like.
Examples of possible raw materials 14 include olefin monomers and comonomers (such as ethylene, propylene, butene, hexene, octene, and decene), diluents (such as non-compressible propane (liquid), isobutane, nhexane, and n-heptane), chain transfer agents (such as hydrogen), catalysts (such as catalysts for
Ziegler, Ziegler-Natta catalysts, chromium catalysts and metallocene catalysts), co-catalysts (such as triethylaluminumalkyl, triethylboron and methylaluminoxane) and other additives. In the case of ethylene monomer, examples of the ethylene feedstock can be supplied through a pipe at approximately 800-1450 pounds per square inch (psia) at 45-65 ° F (7.22-18.33 ° C). Examples of the hydrogen raw material that can also be supplied
<td>through</td><td>a</td><td>pipe but</td><td>to</td><td>approximately 900-1000 psia at</td>
<td>90-110 ° F</td><td> (32</td><td>.2-43.33 ° C).</td><td>By</td><td>course there may be a</td>
<td>variety</td><td>of</td><td>terms</td><td>of</td><td>supply for ethylene,</td>
IMPI
<img file="MX339043B_D0025.tif" />
hydrogen and other raw materials 14
A. Feeding system
Suppliers 12 can supply raw materials 14 to a reactor feed system 16, where raw materials 14 can be stored, such as in monomer storage and feed tanks, diluent vessels, catalyst tanks, co-catalyst cylinders, etc. In feed system 16, raw materials 14 can be treated or processed prior to introduction as feed 18 in polymerization reactors. For example, raw materials 14, such as monomer, comonomer, and diluent, can be sent through treatment beds (eg, molecular sieve beds, aluminum packaging, etc.) to remove catalyst poisons. Such catalyst poisons can include, for example, water, oxygen, carbon monoxide, carbon dioxide, and organic compounds containing sulfur, oxygen, or halogens. The olefin monomer and comonomers can be a liquid, gaseous, or supercritical fluid, depending on the type of reactor being fed. Also, it should be noted that only a relatively small amount of fresh replacement diluent can be used as raw material 14, with a majority of the diluent fed to the polymerization reactor recovered from the
IMPI
<img file="MX339043B_D0026.tif" />
reactor effluent.
The feed system 16 can prepare or condition other raw materials 14, such as catalysts, for addition to the polymerization reactors. For example, a catalyst can be activated and then mixed with a diluent (eg isobutane or hexane) or a mineral oil in the catalyst preparation tanks for subsequent release to the polymerization reactor.
Furthermore, the feed system 16 can provide metering and control of the rate of addition of the raw materials 14 in the polymerization reactor, to maintain the desired stability in the reactor and / or to obtain the properties in the polyolefin or the speed of production desired. For example, a flow meter can be used to measure the flow of ethylene to the reactor. Flow meters that can be used include orifice meters or mass flow meters (for example, a Coriolis meter by MicroMotion, Inc. of Boulder, Colorado), or a thermal mass flow meter. Since orifice meters may require steam heating of the ethylene flow for accurate measurement, mass flow meters can provide energy savings in the modalities of the present techniques.
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In addition, in operation, the feed system can also store, treat and dose the recovered reactor effluent to recirculate to the reactor. In fact, the operations in the feed system 16 generally receive the raw material streams 14 and the recovered reactor effluent. In total, the raw materials 14 and the recovered reactor effluent are processed in feed system 16 and fed as feed streams 18 (eg, monomer, comonomer, diluent, catalyst, co-catalyst, hydrogen, additives or combinations thereof) to the reactor system 20.
B. Reactor system
Reactor system 20 may include one or more reactor vessels, such as liquid phase or gas phase reactors. Reactor system 20 may also include a combination of gas and liquid phase reactors.
If multiple reactors form the reactor system 20, the reactors can be arranged in series, in parallel, or in any other appropriate combination or configuration. Furthermore, different reactors can use the same conditions or different conditions to produce different properties in the polymer. The reactors can be operated under different conditions to produce the final products that are a
<img file="MX339043B_D0028.tif" />
IMPI
MEXICAN INSTITUTE combination of polymers of different%<sup>THE</sup>In this way, produce new or optimized end-of-pipe properties. In the polymerization reactor vessels, one or more define monomers are polymerized to form a product that includes polymer particles, which may be referred to as pellets or granules. The pellet may possess one or more melting, physical, rheological, and / or mechanical properties of interest, such as density, melt index (MI), melt flow rate (MFR), copolymer or comonomer content, modulus, impact, hardness and crystallinity. Reaction conditions, such as temperature, pressure, flow rate, mechanical stirring, product uptake, component concentrations, polymer production rate, etc., can be selected to obtain the desired pellet properties.
In addition to one or more define monomers, a catalyst is typically added to the reactor to facilitate polymerization of the monomer. The catalyst may include particles suspended in the fluid medium within the reactor.
In general · Ziegler-Natta catalysts, chromium based catalysts, metallocenes and other well known polyolefin catalysts can be used, as well as cocatalysts
An example of such a catalyst is a
IMPI
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Ziegler-Natta catalyst containing tetravalent titanium on a MgCl support<sub>2</sub>. Another example is a metallocene catalyst on a sulfated silica-alumina support.
Furthermore, the diluent can be fed into the reactor, which can be a liquid phase reactor, to suspend the catalyst and polymer particles during the reaction.
As mentioned above, the diluent can be an inert hydrocarbon that is a liquid at the reaction conditions. However, in the present techniques, the diluent can be a mixture chosen to have a favorable temperature and critical pressure, to carry out the operations in a semi-supercritical regime. For example, in a contemplated embodiment, semi-supercritical propane may be used as the diluent, as described in detail in the following Section II.
A driving device may be present within the reactor in the reactor system 20. For example, within a liquid phase reactor, such as a loop suspension reactor, an impeller may create a turbulent mixing zone within the fluid medium. The impeller can be driven by a motor to drive the fluid medium, as well as any catalysts, polyolefin pellets, or other solid particulates suspended within the medium.<sub>25</sub> ΙΜΡΙ ^ 5
INSTITUTO MEXICANO J fluid, through the closed circuit advantage of using diluent systems — of—<sup>1aQ</sup> prpspni-ps_ techniques, may be a minor motive force used to circulate a suspension through a loop reactor.
This lower driving force may result from the decreased density of some diluents, such as semi-supercritical propane, which may have a density that may be approximately 10% less than the density of isobutane at the same temperature. Due to the lower density, a single larger pump can be used instead of two smaller pumps (in series), thus saving electrical costs. While the electrical cost savings may depend on the relative size of the pumps used, the single pump can save as much as 10-40% on the electrical operating costs on the two pumps. Other pump configurations can be used, including multiple pumps that have the same or a different design, or a simple larger motor that drives multiple impellers. In some embodiments, higher average reactor solids can be obtained, operating in the semi-supercritical or supercritical regions.
C. Diluent / monomer recovery, treatment and recirculation
Discharge 22 of reactors into system 20
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IMPI
MEXICAN INSTITUTE OF PROPERTY
INDUSTRIAL _ may include the polymer pellet as well as non-polar components such as diluent, unreacted monomer / comonomer and residual catalyst. The discharge 22 can be subsequently processed, such as by a diluent / monomer recovery system 24, to separate the non-polymer components 26 (eg, diluent and unreacted monomer) from the polymer pellet 28. The diluent / monomer recovery system 24 can have a low pressure recovery expansion (for example, at about 25 psia) of the diluent / monomer with associated recirculation compression or can eliminate this process step using only a high expansion pressure (for example, at about 180 psia) in a high pressure separation vessel. A high pressure separation vessel allows the solvent to expand into a gas and thereby separate from the polymer pellet. Therefore, the diluent vapors can be condensed and recirculated to the reactor without the use of a gas expansion compressor.
With or without low pressure expansion, the untreated recovered non-polymer components 26 can be further processed, such as by a fractionation system 30, to remove undesirable heavy and light components. Fractional Product Streams
<img file="MX339043B_D0031.tif" />
afterwards they can be returned to the medium system of the feeding system 16. On the other hand, the non-polymer components 26 can be recirculated more directly to the feeding system 16 (as indicated with the reference number 34), passing the fractionation system 30, and in this way, avoiding the energy consumption of the fractionation system 30. In fact, in some embodiments, up to 80-95% of the diluent discharged from the reactor is diverted from the fractionation system en route back to the polymerization reactor. As a result, the size of the fractionation columns and the associated steam consumption in the downstream fractionation system 30 can be reduced by as much as 70-90%.
The pellet 28 can be further processed within the recovery system 24 and in the extrusion / discharge system 36, to prepare it for transport, often as granules (pellets) 38, to customers 40. Although not illustrated, the intermediate polymer granules in recovery system 24, which may contain residual active catalysts, can be returned to reactor system 20 for further polymerization, such as in a different type of reactor or under different reaction conditions. . Polymerization and recovery portions of the diluent from the manufacturing process of
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<sub>28</sub> IMPI Mexican polyolefin institute 10 can be called the reaction end of process 10, v. -1st extrusion / discharge portion 36 of polyolefin process 10 may be called the dry end 44 or finished side of polyolefin process 10.
Polymer pellet 28 may be transported from recovery system 24 by a blower or other electrical-mechanical force to extrusion / discharge system 36. Alternatively, the process pressure itself may be used to transport or carry polymer pellet 28 from the recovery system 24 to the extrusion / discharge system
36. In this technique, the operation of the reactor system 20 and the recovery system 24 is more directly coupled to the extruder / discharge system 36, for example, the pellet can be fed directly to the extruder system of the reactor expansion system. Such direct or closed operational coupling can reduce the residence time of the pellet process 28. In this way, the number of intermediate pellet storage containers (eg silos) and associated blower / compressor systems can also be reduced.
In a tightly coupled system, the reactor system 20 may have a killer agent system configured to inject a catalyst poison, such as
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IMPI an alcohol, water, CO2, to decrease<sup>NSTI</sup>Súá '^^ íSim · ikim ιι · τιιι 1 1 polymerization reaction. Injection of a killer agent can be performed to decrease or stop the production of the polymer, for example, during the service of an extruder.
Once the extruder is fully functional, the additional catalyst or co-catalyst can be injected into the reactor system 20 to resume production.
D. Extrus / Ion charging system
In extrusion / discharge systems 36, the pellet can be extruded to produce polymer granules 38 with the desired mechanical, physical, and melt characteristics. The feed to the extruder may include additives, such as UV inhibitors, flux improvers, and peroxides, among others, which are added to pellet 28 to impart the desired characteristics of granules of extruded polymer 32. An extruder / granulator receives the feed from the extruder, including one or more pellet products 28 and any additives that have been added. The extruder / granulator heats and melts the extruder feed, which can be extruded (eg, by means of a twin screw extruder), through a pressure granulating die, to form the polyoiefin granules. These granules can be cooled in an aqueous system placed at or near the discharge of the
<img file="MX339043B_D0034.tif" />
IMPI
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INDUSTRIAL granulator. The granules can be transported from the granulator to the discharge area using a blower, or they can be transported directly through the granule cooling system to the discharge area.
In general, the polyolefin granules can then be transported to a product unloading area, where the granules can be stored, mixed with other granules, and / or loaded in cars, trucks, bags, etc., for distribution to customers 40. In the case of polyethiene, granules 38 transported to customers
40 may include linear low-density polyethiene (LLDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and improved polyethiene. Different types and grades of polyethylene 38 granules can be marketed, for example, under the trade names Polyethiene Marlex® or Polyethiene MarFlex® from ChevronPhillips
Chemical Company LP, of The Woodlands, Texas, USA.
E. Customers, applications and terminal uses
Polyolefin granules (eg, polyethiene) can be used in the manufacture of a variety of products, components, household items, and other items, including adhesives (eg, hot melt adhesive applications), wires and electrical cables, films agriculture, shrink film, film
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stretchable, alimfts packaging films ^ ae ^ ExitSiuv
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S ftSwícl'S ^ ¿xicSiSTn OF INDUSTRIAL PROPERTY flexible food, milk containers, frozen food packaging, waste liners and cans, grocery store bags, heavy load bags, plastic bottles, safety equipment, coatings, toys and an arrangement of containers and plastic products.
Furthermore, it should be emphasized that polyolefins other than polyethylene, such as polypropylene, can form such components and products by the processes described below.
Finally, the products and components formed from polyolefin granules (for example, polyethylene) 38, can be further processed and assembled for distribution and sale to the customer. For example, a rotomoulded sailboat can be equipped for sale to a customer, or a pipeline can be assembled and buried for the distribution and sale of natural gas.
To form the end products or components of the granules 38, the granules generally undergo further processing, such as blow molding, injection molding, rotational molding, blown film, cast film, extrusion (eg, extrusion of film, pipe and corrugated extrusion, coating / lamination extrusion, etc.), etc. Molding by
<img file="MX339043B_D0036.tif" />
IMPI blowing is a process used to produce parted<sup>WILDEBEEST</sup><give<sup>ESTUARY</sup>^ la ^ tt ^ o hollow. The process may employ blow molding equipment, such as reciprocating screw machines, accumulator head machines, and so on. The blow molding process can be designed to meet customer needs, and to manufacture products ranging from plastic milk bottles to the aforementioned automotive fuel tanks. Similarly, in injection molding, products and components can be molded for a wide range of applications, including containers, food and chemical packaging, toys, automotive, drawers, lids, and closures, to name a few.
Extrusion processes can also be used. Polyethylene tubing, for example, can be extruded from polyethylene pellet resins and used in a variety of applications because of its chemical resistance, relative ease of installation, durability, and cost advantages, and the like. In fact, plastic polyethylene pipe has achieved significant use for aquifers, gas distribution, storm and sanitary sewers, indoor plumbing, electrical conduits, power and communication pipelines, frozen water pipe and well linings, to name a few applications. In particular,
<img file="MX339043B_D0037.tif" />
IMPI high-density polyethylene (HDPE), the
INDUSTRIAL overall the largest volume of the polyolefin group of plastics used for a pipeline, is rigid, abrasion resistant and flexible (even at freezing temperatures). Additionally, HDPE pipe can be used on a small diameter pipe and pipe up to more than 8 feet in diameter. In general, polyethylene granules (resins) can be supplied for pressure piping markets, such as in natural gas distribution, and for non-pressure piping markets, such as for ducts and corrugated pipes.
Rotational molding is a high-temperature, low-pressure process used to form hollow parts by applying heat to biaxially rotated molds. The polyethylene granule resins generally applicable in this process are the resins that flow in the absence of pressure when they melt to form a bubble-free part. Granules 38, such as certain HDPE resins and
Marlex® MDPE offer such flow characteristics as well as a wide processing window. Furthermore, these polyethylene resins suitable for rotational molding, can exhibit desirable low temperature impact resistance properties, good load bearing, and good ultraviolet (ÜV) stability. Therefore, applications
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INMENTIAL INSTITUTE OF LAWOPIEDAL · for rotationally molded Marlex® resins include agricultural tanks, industrial chemical tanks, drinking water storage tanks, industrial waste containers, recreation equipment, marine products, and many more.
Film extrusion is a technique for making flat plastic films from a variety of granule resins 38. In general, relatively thin gauge films are thermoformed in packaging applications, such as drinking containers, deli containers, product trays , containers for baby towels and margarine cubes. Other markets for polyolefin film extrusion include those that use relatively thick films, for example, around 100-250 thousand of an inch (thousandth), for industrial and recreational applications such as truck bed liners, granules , automotive stowage timbers, playground equipment and boats. A third use for extruded film, for example, is in geomembranes, where a flat film polyethylene material is solidified in large containment systems for municipal waste disposal and mining applications.
The blown film process is a relatively diverse conversion system used for polyethylene.
<img file="MX339043B_D0038.tif" />
The American Society for Testing and Films Less Than Thousands) Thick. However, blown can produce materials millimeters (20 thousandths), and larger. In addition, blow molding can be used in conjunction with monolayer and / or multilayer coextrusion technologies to produce numerous products, such as labeled bottles. Advantageous properties of products produced by the blown film process can include clarity, strength, tear ability, optical properties, and stiffness, to name a few.
The cast film process may differ from the blown film process through the layers rapid quenching and virtual one-way orientation capabilities. These features allow a cast film line, for example, to operate at relatively high production rates, for example, several hundred pounds per hour or more, while producing optical benefits. Food applications and retail packaging take advantage of these resistances. Finally, polyolefin granules can also be supplied for extrusion coating and lamination industry.
Using any type of film extrusion, the
<img file="MX339043B_D0039.tif" />
IMPI, linear low density polyethylene,
INDUSTRIAL is extruded from polyethylene granule resins and is used in a range of applications due to its flexibility, chemical resistance, durability, processability, cost advantages, and the like. These applications may include stretch films for granulating materials, packaging crisps and fresh cut vegetables, shrink wrap and other product packaging. Films made of linear low-density polyethylene have significant success in unusual applications, such as geomembranes. A geomembrane can be used to isolate a storage well, such as a landfill or sewer overflow well, from the surrounding land, protecting land water from contamination. Other applications may include garment bags, bakery films, industrial coatings, and the like.
F. Other power currents
The diluent recirculated (eg propane or isobutane) with a entrained monomer can be returned from the diluent / monomer recovery system 24 (eg corresponding to stream 34 in Figure 1) and sent to the polymerization reactor . The amount of entrained monomer can vary, depending on the polymerization efficiency. For example, the relatively low incorporation efficiency of 1-h
<img file="MX339043B_D0040.tif" />
the amount entrained in the recirculating diluent stream. In the direct recirculation example, the recirculated diluent can be cooled and passed through a heavy drain container, where the heavy components are removed from a bottom discharge and shipped by means of a centrifugal pump, for example, as it is fed to the fractionation system 30. The head of the drain vessel can be further cooled in a heat exchanger and collected in a recirculating diluent accumulation tank to feed into the reactor. A downstream centrifugal pump can deliver the diluent through the recirculating diluent treaters to the loop suspension reactor.
It should be noted that a relatively small amount of fresh diluent (not shown) can be added to fractionation system 30, for example, to make up for diluent losses in the manufacturing process 10.
In addition, the comonomer (eg, 1-hexene) can be added at various points in the recirculating diluent loop for addition to the reactor.
H. Semi-super critical diluents in the production of polyolefins
The present techniques include the use of diluents or
ΙΜΡΙ diluent mixtures at temperatures <sup>INS</sup>
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critical temperature, but at pressures greater than its critical pressures. Under these conditions, the diluent can act as a compressible liquid, which actually changes volume with pressure. For this reason, diluents in this operating regime can be thought of as a semi-supercritical regime. Furthermore, as described above, operation with a propane diluent in a semi-supercritical regime can provide advantages over other diluents operating in this temperature / pressure regime. For example, less reactor clogging occurs due to lower polymer solubility in a propane diluent versus isobutane (eg, about 10% lower solubility) and lower propane solubility in the polymer (generally, about 35% at 45% of the solubility of isobutane in polyethylene). Furthermore, the decreased density of propane versus isobutane (generally approximately 2-10% lower) and viscosity (generally approximately 5-10% lower than isobutane) can decrease the energy requirements for circulation in a loop reactor. (or stirring or mixing, for example, in an autoclave reactor). Finally, the higher vapor pressure of propane against isobutane can improve the removal of the diluent from
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The compressibility of the diluent mixture in the semi-supercritical operating regime can allow the reactor to run with a smoother pressure curve against time, since the volume loss of intermittent product flows out of the reactor will generally be offset by solvent expansion. More specifically, at the compressible rate above critical pressure (for example, approximately 625 psia for pure propane), changes in volume will occur without phase changes that could result in the formation of headspace or cavitation of the bomb.
The semi-supercritical operating regime is described in more detail in the subsections that follow. In subsection A, the general phase behavior of a light hydrocarbon is described. Sub-section B details the effects that additions of ethylene, comonomer and hydrogen have on phase behavior. Sub-section C further defines the semi-supercritical operating regime from the point of view of the modified phase behavior shown in the different diluents.
A. Phase behavior of a light hydrocarbon
The advantages of the operating regimes of the present techniques can be further clarified by
<img file="MX339043B_D0043.tif" />
IMPI examination of hydrocarbon phase behavior, such as those used in diluents for a polyolefin polymerization. The phases of a pure hydrocarbon as a function of temperature and pressure are shown by phase diagram 46 depicted in
Figure 2. Phase diagram 46 has boundary lines separating the regions that correspond to different phases. In the values for the temperature and pressure represented in each line, the two phases on each side of the line are substantially in equilibrium. For example, the liquid-solid boundary 48 marks the transition point at which a hydrocarbon in a solid phase 50 melts into a liquid phase 52, since the input of energy into the system raises the temperature (holding pressure constant ). When the system reaches the transition temperature shown by the liquid-solid line 48, the system temperature remains substantially constant as the phase transition from solid 50 to liquid 52 occurs. If the energy input stops during the phase transition, in general, the phases can continue to exist in equilibrium at such a constant temperature and constant pressure. Once the transition from one phase to another is complete, the continuous power input will again begin to raise the temperature of the system (while the pressure is kept "IMPI substantially constant in this example). mexican instttut<sup>J c</sup> OF THE PROPERTY
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Other lines on the phase diagram of the pure component 46 indicate the gas-liquid limit 54 and the 'gas-solid 56 limit. This last limit, in which a solid will sublimate directly into a gas, only occurs at the temperature and pressure below the hydrocarbon triple point 57. Triple point 57 marks the temperature 58 and pressure 59 at which the three points, gas 60, liquid 52, and solid 50 can exist in equilibrium, while no additional energy is introduced into or removed from the system.
As the temperature and pressure of the hydrocarbon are increased by the input of energy, the hydrocarbon can reach a critical point 64 when a critical temperature 66 and a critical pressure 68 are exceeded.
Specifically, the temperature has exceeded the value to eliminate chemical interactions between the individual hydrocarbon molecules, however, the pressure is too high for the molecules to physically move and separate into a gas phase. At critical point 64, the
<img file="MX339043B_D0044.tif" />
<td colspan="2">separation between a</td><td>phase</td><td>liquid 52 and gas</td><td>60 no longer exists,</td>
<td>Since the</td><td>density</td><td>of</td><td>both phases are</td><td>substantially</td>
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the properties of both, called a supercritical fluid 70.
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Benefits in some applications, employing diluents above critical temperature 66, without exceeding critical pressure 68, or above critical pressure 68 without exceeding critical temperature 66, may also provide substantial benefits. These regions can be considered as semi-supercritical operating regimes. For example, exceeding the critical temperature 66, as long as it does not exceed the critical pressure 68, places the hydrocarbon in the superheated steam operating regime 71.
The above phase description provides an introduction to the use of a supercritical fluid, but it can be seen that the diluent is actually a mixture of the pure light hydrocarbon and a monomer, and may further include a comonomer, such as, for example, hexene, together with a catalyst composition, and, optionally, hydrogen as a chain terminating agent. These additional components can make the phase diagram more complex, depending on the amount of other constituents in the diluent, as described in the next subsection.
B. Examples of calculations of critical temperatures and pressures
The simplified phase behavior of a component
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<img file="MX339043B_D0047.tif" />
pure, as described above, you can
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complex when the additional components of the diluent mixture are added. Such components can include, for example, ethylene, comonomers (such as hexene or butene), and hydrogen. The behavior of such a mixed system can be modeled by commercial engineering design packages, to predict the critical temperature and pressure of the mix. An example of an engineering modeling software package that can be used to model phase behaviors is AspenOne, available from Aspen.
Technology Co. of Cambridge, Massachusetts. The results provided by the modeling software can be used to establish the operating limits of temperature and pressure for operation in the semi-supercritical regime.
The exemplary results described below were obtained as the hydrocarbon, but similar calculations can be used to obtain the operating limits for isobutane, as well as other diluents that can be operated in the semi-supercritical regime, such as pentane and butane, among others.
Furthermore, the nature of the critical point itself makes calculations at the critical point difficult. As a material approaches the critical point, the equilibrium calculation can take a longer period of time, thus the time taken by the
<img file="MX339043B_D0049.tif" />
Stabilizing can be substantial, for example, several hours or even days. In addition, calculations can also use an equation of state to calculate phase equilibrium, which is a close approximation to the measured equilibrium of the mixtures. For this reason, the values given in the examples described below should be understood as approximations.
one. Propane vs. Critical Pressure and Temperature
weight fraction of ethylene
As the ethylene content in a mixture with propane increases, the critical pressure can be increased and the critical temperature can be decreased. Without pretending to be limited by theory, this may be a result of the incorporation of lighter and more easily vaporized ethylene in the mixture with propane.
The effect of adding ethylene to a diluent can be quantifiable, as shown by Figure 3, which is a graph showing the calculated effects of increasing the ethylene content on the temperature and critical pressure of a diluent mixture at propane base. As observed in this graph, an increase can be observed in the critical pressure 76 of the mixture as the ethylene content increases, by increments, from 0 to 0.12 fraction in
<img file="MX339043B_D0050.tif" />
IMPI weight (i.e. 0 to 12 wt%). Conversely, a large drop in critical temperature 78 can occur during the same interval. These changes indicate that the critical point can be reached more easily, as increased amounts of ethylene are added to propane. This can be seen more clearly - in the graph shown in
Figure 4, which represents the calculated critical point of the diluent mixture containing ethylene and propane as the ethylene concentration is changed. In this graph, as the weight fraction of ethylene in propane is increased, indicated by the cross marks 80 along the line, the critical point is shifted to the left, that is, at lower temperatures and higher pressures. In this graph, the lowest calculated critical temperature for the mixture is at approximately a 0.14 weight fraction of ethylene (as indicated by reference number 82) and may be approximately 195 ° F (90.55 ° C). The calculated maximum critical pressure for the mixture is also at a 0.14 weight fraction of ethylene, and may be approximately 755 psia.
Although the calculated values for a mixture of ethylene and propane provide important data to establish the limits for the reaction parameters, linear low density polyethylene can be a copolymer containing ethylene and a comonomer, such as, for example, 1-hexene . By
IMPI
<img file="MX339043B_D0051.tif" />
therefore, calculations were run on mixtures containing
1-hexene in addition to ethylene and propane, as described below.
2. Effects of adding 1-hexene and hydrogen to a mixture of ethylene and propane
The results of the critical point calculations for a mixture of ethylene and propane containing 1% hexene, are shown in the graph in Fig. 5. As in Fig. 4, the concentration of ethylene (in fraction in weight) is indicated by cross marks 84 drawn across the line. As shown in this graph, the addition of 1-hexene can change the critical temperature and critical pressure to higher values. The highest critical pressure and the lowest critical temperature are reached at the highest ethylene concentration, 0.14 weight fraction. At this ethylene concentration, the critical pressure can be approximately 763 psia, and the critical temperature can be approximately 200 ° F (93.3 ° C). Higher critical pressures and lower critical temperatures will be presented for mixtures with a higher ethylene content. Occasionally, at high concentrations of ethylene, critical conditions will approach those of pure ethylene.
Then hexene, hydrogen, can have the greatest effect on pressure and critical temperature. For
<img file="MX339043B_D0052.tif" />
IMPI illustrate the effects of hydrogen,
INDUSTRIAL performed on different mixtures containing propane, ethylene, 1-hexene and hydrogen. The results obtained from the calculations are shown in the graph in Figure 6. In this graph, each one of the calculations of the critical point was made from ethylene with a weight fraction of 0.01, indicated by reference number 88, at a weight fraction of ethylene of 0.14, indicated by the reference number
90. The other components were held constant, with calculations running on systems that did not contain hexene or hydrogen (as shown by line 92), 1 wt% hexene without hydrogen (as shown by line
94), 2% by weight hexene without hydrogen (as shown by line 96) and 1% by weight hexene with 1 mole% hydrogen (as shown by line 98). While all additional components affected the critical points and critical temperatures obtained from the calculations, all values were below a pressure of approximately 7 65 psia and above a temperature of approximately 195 ° F (90.5 ° C). These limits can be used in the modalities of the present techniques to adjust the operating limits for the use of semi-supercritical propane. Similar calculations were run for isobutane and showed that the semi-supercritical values were
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C. Region of semi-supercritical operation
The critical pressures and critical temperatures calculated above can be used to define the semi-supercritical operating regime. This regimen can be more clearly illustrated by the graph in Figure 7.
In this graph, the lines calculated for Figure 6 (indicated by reference number 102) are superimposed on a larger pressure and temperature regime. As described with reference to Figure 6, the upper left point on each line with reference 102 indicates a mixture containing a 0.14 weight ethylene fraction, while the lower right point indicates a mixture containing an ethylene fraction at 0.1 by weight. The other components are varied as described with respect to the
Figure 6.
The highest operating temperature that can be practical can be defined by the properties of the resin, as higher temperatures, for example, greater than about 195 ° C, can cause dissolution of the polymer in the diluent or melting of the polymer product.
Any of these effects can cause blockage of the «IMPI reactor. For this reason, in this example, a
INDUSTRIAL practical in operating temperature for a linear low-density polyethylene resin can be around
195 ° F (90.5 ° C). This temperature is indicated on the graph by the line marked 104. As can be seen from the comparison of the calculated results 102 with the line
104, this temperature may also be below the critical temperature of the diluent mixtures. Ethylene concentrations greater than 14% by weight are possible in a loop reactor. However, using these high concentrations would use a reactor temperature lower than 195 ° F (90.5 ° C) to stay in the semi-supercritical region.
In this example, the lowest operating pressure to remain in the regime in the semi-supercritical operation regime can be determined from the calculated results
102. As shown by line 106 on the graph, a lower pressure limit of 765 psia may be above the critical pressure of diluent mixtures. Operating above this pressure decreases the probability that two-phase flow will occur in the reactor due to steam formation, and provides the other benefits described above. On the contrary, the operation
<img file="MX339043B_D0054.tif" />
above both critical points, that is, in the region
IMPI
0 MEXICAN INSTITUTE
FROM supercritical PROPERTY, may be less desirable due to
<img file="MX339043B_D0055.tif" />
polymer density can swell or melt<sup>1</sup> and — übüLlLllí 5 reactor.
An example of an operating regime that can be defined by these temperature and pressure limitations is marked 108 in Figure 7. The high pressures required to operate in this semi-supercritical regime may be above the current operating limits used in many reactors. commercial. Furthermore, polyolefin catalysts can operate more efficiently at high temperatures, for example, greater than about
175 ° C, giving a narrow temperature regime for the reactor. For this reason, large, high-pressure reactors that have precise temperature control (for example, within plus or minus 10 ° C of a target temperature, or within plus or minus 20 ° C of a target temperature) they may be beneficial for the operation in the semi-supercritical regime. Such reactor systems may tend to decrease temperature variations that could be problematic. An example of a reactor system is described in the next section.
III. Polymerization reactor system that can use semi-supercritical diluents
A process flow diagram of a reactor system
<img file="MX339043B_D0056.tif" />
ΙΜΡΙ polymerization 20 and a diluent / monomer recovery system 24 (as described with respect to the
Figure 1) that can be used in the modalities of the present techniques, are represented in Figure 8. As described above, the reactor system 20 can include one or more polymerization reactors, which, instead, can be the same. type or different. Furthermore, in multiple reactor systems, the reactors can be arranged in series or in parallel. Any of the types of reactor that forms the reactor system 20 is produced, a particulate polyolefin product, generically referred to as pellet 28 herein. Although the following examples use a single reactor, the present techniques are applicable to more complex reactor arrangements, such as those involving additional reactors, different types of reactors, and / or alternative arrangement of reactors or types of reactor.
One type of reactor includes reactors within which polymerization occurs within a liquid phase. Examples of such liquid phase reactors include autoclaves, boiling liquid accumulation reactors, circuit suspension reactors (vertical or horizontal), and so on. For simplicity, a circuit suspension reactor 110, which produces polyolefin, such<sub>52</sub> IMPI like polyethylene, polypropylene and their,
INDUSTRIAL discussed in the context of the present techniques, although it will be understood that the present techniques are similarly applicable to other types of liquid phase reactors.
Referring to Figure 8, the circuit suspension reactor 110 is generally comprised of pipe segments connected by bends or smooth elbows. An example of a reactor 110 configuration includes twelve jacketed vertical pipe supports, approximately 24 inches in diameter and approximately 200 feet in length, connected by pipe elbows at the top and bottom of the supports. As described above, reactor 112 jackets are normally provided to remove heat from exothermic polymerization by circulating a cooling medium, such as treated water, through reactor 112 jackets. Diameter reactors larger would be acceptable, but would have less heat transfer area per unit volume of the reactor. In addition, smaller diameter reactors, for example less than about 20 inches, would have a larger relative heat transfer area, but may use a larger reactor and a higher differential pressure of the reactor circulation pump to circulate the reactor contents.
<img file="MX339043B_D0057.tif" />
IMPIOS
Reactor 110 can be used for cyclopolymerization of polyolefin under suspension conditions— in which the insoluble polyolefin particles are formed in a fluid medium and suspended as suspension until removed. A driving device, such as a pump
114, fluid suspension circulates in reactor 110. An example of a pump 114 is an in-line axial flow pump, with the pump impeller positioned within the interior of reactor 110 to create a turbulent mixing zone within the medium. fluid. The impeller can also help propel the fluid medium through the closed loop of the reactor at a rate sufficient to keep solid particulates, such as the catalyst or polyolefin product, suspended within the fluid medium.
The impeller can be driven by a motor 116 or other driving force. In a large reactor 110, for example, greater than about 50,000 gallons, more than one impeller can be used to drive circulation. These impellers can be located on opposite sides of reactor 110 and use separate motors 116. In other embodiments, the impellers can be attached to a single shaft driven by a single, larger motor 116. In any case, the lower density that may be present with some diluents in the semi-supercritical phase, such as propane, can decrease the energy requirements for the
<img file="MX339043B_D0058.tif" />
sma running speed, for example, at about 540%, depending on whether a single motor replaces a two-motor configuration.
The liquid phase of the polymer suspension circulating within reactor 110 can be considered the diluent mixture and can include monomers and comonomers of olefin, diluent, co-catalysts (eg, alkyl, triethylboron, methylaluminoxane, tri-isobutyl aluminum, triethyl aluminum, etc.), molecular weight control agents (eg, hydrogen) and any desired co-reagents or additives. Such olefin monomers and comonomers in general are 1-olefins (i.e. having a double bond between the first two carbons) that have up to 10 carbon atoms per molecule and cannot have ramifications closer to the double bond than position 4 .
Examples of the monomers and comonomers include ethylene, propylene, butene, 1-pentene, 1-hexene, 1-octene, and 1-decene.
Again, typical diluents are hydrocarbons that are inert and liquid under the reaction conditions, and include, for example, isobutane, propane, n-pentane, ipentane, neopentane, n-hexane, cyclohexane, cyclopentane, methylcyclopentane, ethylcyclohexane, isooctane, and Similar. Most of these diluents may be able to run in a semi-supercritical state at<sup>55</sup> IΜ ΡI the TemperatiÍf £ 3 ^; í $ & $ r «gee ^ practices. Additionally, diluents can be combined to obtain precise temperature and pressure control over the semi-supercritical operating rate for a particular catalyst and white polymer system, for example, forming a propane mixture with a small amount of isobutane to adjust the semi-supercritical operating regime.
These components are added to the interior of the reactor through inlets or conduits at specified locations, as represented in feed stream 118, which generally corresponds to one of feed streams 18 in Figure 1. Also, a catalyst, such as those described above, can be added to reactor 110 via a conduit at an appropriate location, as depicted in feed stream 120, which may include a diluent vehicle t which, in general, also corresponds to one of the feed streams 18 in Figure 1. Overall, the added components generally make up a fluid medium within reactor 110 in which the catalyst includes suspended particles.
Reaction conditions, such as temperature, pressure, and reagent concentrations, can be regulated to facilitate properties and speed.
<img file="MX339043B_D0059.tif" />
desired polyolefin in reactor 110, to control the stability of reactor 110, and the like. The temperature can be kept below the level at which the polymer product melts or enters solution. As described above, the practical limit, based on the solubility of a linear low-density polyethylene in propane, may be less than about 200 ° F (93.3 ° C), although if other polymer systems with a mixture of diluent having a higher critical temperature, this temperature may be higher, for example, about 215 ° F (101.6 ° C) for isobutane. As noted, due to the exothermic nature of the polymerization reaction, a cooling fluid can be circulated through jackets 112 around portions of the suspended reactor 110 to remove excess heat, thereby maintaining the temperature within the desired range, generally between 150 ° F to 195 ° F (65 ° C to 91 ° C). The operating temperature range can be kept within this narrow window, to avoid problems with clogging, as described above. In contrast, the typical interval for the difference in temperature between the incoming coolant and the outgoing coolant through a jacket in the reactor (ΔΤ) in a
IΜ ΡI polyolefin reactor, may be approx. ^ Gjj 6.6 ° C) or higher. While this interval may spr. Sufficient, an even narrower range can be used for the semi-supercritical diluents of the present techniques, for example, 5 to 10 ° F (-15 to -12.2 ° C). This may allow for less temperature swing in the slurry as it flows around the reactor. Such a narrow range can be more easily obtained through the use of large reactors, which can have a length to large diameter ratio for a jacketed portion, thereby increasing the internal surface area of the reactor. For example, in one embodiment of the present techniques, the reactor system may be 70,000 to 100,000 gallons in size.
In other embodiments, a smaller reactor with a corresponding increase in coolant flow through jackets 112 can be used to remove excess heat.
Also, the pressure in the reactor can be regulated to keep the diluent or diluent mixture above its critical pressure. For propane as the diluent, an example of an operating range that extends the critical pressure would be at least about 751 psia, and may be within the range of about 800-900 psia. High pressure values for semi-supercritical regime can benefit from reactors that have
<img file="MX339043B_D0060.tif" />
Relatively pressure ratings to operate in the semi-supercritical regime, a reactor and the immediate attached support lines, including the feed and intake lines, can be class 600 or class 900 pipe to overcome higher pressures.
As the polymerization reaction proceeds within reactor 110, the monomer (eg, ethylene) and comonomers (eg, 1-hexene) polymerize to form polyolefin polymers (eg, polyethylene) that are substantially insoluble in the fluid medium at reaction temperature, whereby a suspension of solid particulates is formed within the medium. These solid polyolefin particulates can be removed from reactor 110 by means of a sedimentation support or other means, such as continuous intake, as represented by discharge stream 22. In downstream processing, polyethylene discharged from the reactor can be removed from suspension and purify.
IV. Diluent / monomer recovery system
A. Separation bowl
The discharge 22 from reactor 110 can be sent to the diluent / monomer recovery system 24. In the diluent / monomer recovery system 24, the discharge 22 from reactor 110 can flow through into a heater. <sub>59</sub> IMPI expansion on line 122 and in the container
INDUSTRIAL
In-line expansion heater 122 can be ducted
<img file="MX339043B_D0061.tif" />
jacket using steam or condensed steam in the jacket, for example, as a heating means to provide indirect heating to the discharge 22. In the embodiments, parallel in-line heaters can be used to increase flow and decrease the risk of clogging. In this way, the effluent from the circuit suspension reactor 110 (discharge 22) is heated until its introduction into the separation vessel 124. Also, before the discharge 22 enters the separation vessel 124, water or other poisons from the catalyst 126 can be injected into the discharge 22 as killers, to deactivate any residual catalysts and co-catalysts in the discharge stream 22. Because these injected components are catalyst poisons by definition, they can be completely removed, or at least substantially removed, from any recovered material (eg, monomer or diluent) recycled to reactor 110.
In other embodiments, the killer agents can be injected into reactor 110 in amounts that may be sufficient to partially deactivate the catalyst in reactor 110 and thereby decrease the rate of polymer production. Such partial deactivation, so IMPI moderation, mini-death, can be useful.
INDUSTRIAL production speeds between a reactor and a termination line, if the termination line is undergoing service, for example, during the change of a packing or a filter, among others. As reactor output is decreased, the solids storage capacity of separation vessel 124, or other downstream units, may be sufficient to store the produced polymer until the finish line can be returned to full production.
In separation vessel 124, most of the non-solid components of reactor discharge 22 are removed as overhead vapor in expansion gas 128. In one embodiment of the present techniques, separation vessel 124 may be a separator cyclonic. In other embodiments, the separation container 124 may be exclusively an open container. In the production of polyethylene, the vapor may be primarily the diluent, such as propane, isobutane, or other diluents mentioned above. It can also contain most of the unreacted monomer (for example, ethylene) and other light components, as well as the unreacted comonomer (for example,
1-hexene, butene, 1-pentene, 1-octene and 1-decene) and other heavy components (eg hexane and oligomers). In
<img file="MX339043B_D0062.tif" />
general light or light components
INDUSTRIAL «1 IMPI
INDUSTRIAL as light components with lower boiling points than the diluent used. In contrast, heavy or heavy components can be defined as components that have boiling points greater than the boiling points of the diluent. An example of an approximate composition of the expansion gas 128 may be 84% by weight of propane, 5% by weight of ethylene and 11% by weight of other components (eg comonomer). A level or volume of the pellet can be maintained in the separation container 124 to give an additional residence time of the pellet in chamber 124 to facilitate the separation of the liquid and vapor entrained in the porous pellet particles.
Expansion gas 128 can be processed in equipment, such as a bag filter 130 or other types of equipment, including cyclones, etc., to remove entrained pellet solids 129 to return to separation vessel 124 or equipment downstream, such as the purge column described above. The expanded gas 128 can also travel through other processing units, such as, for example, a deoxygenation bed. Also, the expansion gas 128 can be cooled or condensed in a heat exchanger (eg shell and tube construction) before
<img file="MX339043B_D0063.tif" />
... I- s recirculate to the feeding system 15nstQut ^ J £ xic »¿> si
Γ> Ε INDUSTRIAL PROPERTY
IMP qNSTÍhrr®i «INDEXES OF THE PROFIF.r INDUSTR fractionation 30 (as described with respect to Figure
one). To reduce steam consumption in fractionation system 30, expansion gas 128 can be bypassed from fractionation system 30 and return more directly to reactor 110 via feed system 16 (not shown).
Solids (polymer) in separation vessel 124 are extracted with a small amount of stripped diluent (and monomer) and sent to a purge column
132 via solids discharge 134. Solids discharge line 134 may include valve configurations that allow polymer to flow down through the line, while reducing the potential for steam to flow between the Separation 124 and purge column 132. For example, one or more rotary or cycle valves 133 may be arranged on the solids discharge line 134. In other configurations, the discharge to the purge column 132 may include the appropriate valve configurations, a pulsation chamber, or simply a conduit, etc. Note that some modes provide a continuous pellet discharge from the expansion chamber, which eliminates one or more relatively large cycle valves and the consumption of
<img file="MX339043B_D0064.tif" />
Asociado associated energy. These techniques are
Publication US 2006/0287442, included herein by reference in its entirety.
B. Purge column
The feeding of primary solids to the column of
<td>bleed 132</td><td>is</td><td>typically</td><td>the</td><td>solids discharge</td><td> 134</td>
<td>(pellet</td><td>of</td><td>polyolefin)</td><td colspan="2">coming out of the container</td><td>of</td>
<td>separation</td><td> 124 .</td><td>A purpose</td><td>of</td><td>purge column 132</td><td>is</td>
<td>remove the</td><td colspan="3">residual hydrocarbon</td><td colspan="2">of solid streams</td>
input and provide a substantially clean polymer pellet 136. The pellet 136 can be transported or taken to the extrusion / discharge system 36 for conversion to pellets 38 (as described with respect to Figure 1) and for distribution and sale as a polyolefin pellet resin to customers 40. In general, treated polymer particles discharged from purge column 132, such as polymer pellet 136, can be processed in a conventional finishing operation, such as a screw extruder, in extrusion / discharge system 36.
In the illustrated purge column system example, nitrogen can be injected into the purge column
132 for removing residual hydrocarbons by means of head discharge 138. This discharge 138 can be sent through a bag filter 140 to
<img file="MX339043B_D0065.tif" />
entrained fines, which can be returned to purge column 138. In other embodiments, bag filter 140 may be replaced with other types of process units, such as, for example, a cyclone separator, or may be removed entirely. After the bag filter 140, the discharge
138 it can be sent through a separation unit 142, such as a membrane recovery unit, a pressure balancing adsorption unit, a cooling unit, etc., to recover the nitrogen by means of the nitrogen stream 144, and to discharge a separated hydrocarbon stream 146 as it is fed to fractionation system 30. Separation unit 142 may be known as a Diluent Nitrogen Recovery Unit (DNRU). In addition, fresh nitrogen can be added to the discharge circuit to account for nitrogen losses in the purge column system 132. The hydrocarbon stream 146 discharging from the separation unit 142 makes available the hydrocarbon feed that can be processed to give the olefin-free diluent used in the catalyst preparation.
C. Alternative configurations
A variety of configurations can be used in the diluent / monomer recovery system 24. By
IMPI
<img file="MX339043B_D0066.tif" />
For example, the solids discharge 134 separation 124 can be sent to another reactor (for example, a gas phase reactor) instead of the purge column 132. If it is discharged to another reactor, the catalyst poison 126 cannot be injected current upstream at discharge 22, and in this way, residual active catalysts can remain for further purification.
In another configuration, blowdown column 132 can be used as an extruder feed tank in extrusion / discharge system 36 (described with respect to Figure 1). Bag filter 140 and separation unit
142 associated with purge column 132 can be relocated to extrusion / discharge system 36 to accommodate this use. In this way, the high process pressure in the separation vessel 124 can be used to transport the pellet particles in the solids discharge 134 to the extrusion / discharge system 36, eliminating a blower system (and associated electrical consumption) used traditionally for conveying pellet 136 to the extrusion / discharge system. Furthermore, heat can be maintained in the pellet particles, as the particles are not subjected to the typical nitrogen cooling effect in a conventional blower transport circuit. In this way, less can be used
feed heating of the pellet particlesIartTejQMíasiiANg!
m THE PROPERTY industrial downstream extruder. Finally, the process pressure in the separation vessel 124 can be used to transport the pellet particles in a dense phase transport arrangement, thereby decreasing the speed of the flowing particles and reducing transport damage to the particles. .
V. Cooling of the reactor
To facilitate the use of a semi-supercritical diluent for the production of, for example, linear low-density polyethylene, the cooling system can be designed to decrease the temperature differential (ΔΤ) between the inlets (inlet cooling medium) and Outlets (outlet cooling medium) from the reactor jacket, at approximately 10 to 20 ° F or approximately 5 to 10 ° F. This would be beneficial as the operational temperature range that can be used to keep the diluent in the semi-supercritical phase, while not exceeding the very narrow polymer melting temperature. For example, the use of a large reactor may result in a high heat transfer area for the reactor jacket (for example, due to a high length / diameter ratio (1 / d) of the reactor), which could help to decrease the ΔΤ.
Additional modifications may be beneficial in the
<img file="MX339043B_D0067.tif" />
IMPI cooling system of the temperature differential reactor between the inlet and outlet of the refrigerant. For example, a higher speed cooling system (for example, 20-30 feet per second versus more traditional 10 feet per second) can increase the heat removed from the reactor. In other words, increasing the speed of the cooling medium can increase heat transfer through the reactor jacket, and thus help maintain a more constant temperature in the reactor.
Increasing the speed of the cooling medium can be accomplished by selecting a larger reactor cooling water pump, or by decreasing the cross-sectional area of the reactor jacket perpendicular to the flow of the cooling medium, for example. In some embodiments, a larger reactor size (and associated with the increase in the heat transfer area of the reactor jacket) may be sufficient to achieve the lower temperature differential obtained and a more constant reactor temperature. Such a reduction in the temperature differential can be realized even, for example, with the increase in the size of the cooling pump (which could reduce the unit electrical consumption of the reactor system).
MEXICAN INSTITUTE r> E LA RROPItliAT INDUSTRIAL
<img file="MX339043B_D0068.tif" />
A. Reactor in circuit suspension
Figure 9 depicts an example of a polymerization reactor 110 that can be used in the system shown in Figure 8. This figure shows a flow pattern of the countercurrent of the cooling medium through the jackets of the 112A-H reactor. Again, circuit reactor 110 is generally comprised of pipe segments connected by flexing or smooth elbows. · A driving device, such as pump 114, circulates the fluid suspension into reactor 110. An example of a bomb
114 it is an in-line axial flow pump, with the pump impeller positioned inside the reactor 110. A cooling system 150 removes the heat from the circuit reactor 110 by means of the reactor jackets 112A-H.
Cooling system 150 provides a cooling supply 152 (eg, treated water) and processes a cooling return 154.
As the polymerization reaction proceeds within reactor 110, the reaction conditions can be controlled to facilitate the desired degree of polymerization and the desired reaction rate, while maintaining the temperature below which the polymer product would melt or dissolve. As mentioned, due to the
<img file="MX339043B_D0069.tif" />
exothermic nature of the reaction of © ancla rlÍKe ^ ii ^ a ó '
INDUSTRIAL PROPERTY 112A-H cooling jackets can be provided around portions of the closed loop system through which the cooling fluid circulates as needed to remove excess heat (reaction heat), whereby temperature is maintained within the desired range, generally between approximately 165 ° F to 195 ° F (73.8 ° C to 90.5 ° C), such as approximately 175 ° F to 190 ° F (79.4 ° C to 87.7 ° C) in the modalities of the present techniques.
In general, the reactor temperature varies linearly with changes in the operating conditions of the reactor system. For example, the heat generated in the reactor by exothermic polymerization can be linear with the rate of polyolefin production (ie, pounds per hour of polymerized polyolefin). In this way, the reactor temperature, which is an indication of the energy or heat in the reactor, varies linearly with the production rate. Control of the typical reactor temperature may involve a proportional integral derivative algorithm (PID). Other advanced techniques can be used in place of, or in addition to, the PID algorithm.
IMPI
<img file="MX339043B_D0070.tif" />
B. Reactor cooling system
A process flow diagram of a cooling system 150 for circuit suspension reactor 110 of Figure 9 is depicted in FIG. 10. Cooling system 150 provides a cooling supply
152 to the 112A-H reactor jackets. Cooling system 150 receives a return of refrigerant 154 from the
<td>jackets</td><td>of the</td><td colspan="2">112A-H reactor.</td><td>Can be used</td><td>a</td><td>variety of</td>
<td colspan="2">refrigerants</td><td>for</td><td>remove or</td><td>add heat</td><td>to the</td><td>system of the</td>
<td>reactor.</td><td>In</td><td>this</td><td>modality</td><td>illustrative,</td><td>I know</td><td>use steam</td>
condensate (demineralized water) as the refrigerant. Coolant return 154 carries heat removed from the reactor. The refrigerant system 150 transfers this heat to a useful cooling medium, such as water from the cooling tower or seawater. Cooling system releases chilled refrigerant supply
152 to the reactor jackets. In the modalities, the
<td>temperature</td><td>of</td><td>supply</td><td>of</td><td>refrigerant</td><td>152 can swing</td>
<td>105 ° F to</td><td> 150°</td><td>F of 165</td><td>° F</td><td>at 185 ° F or</td><td>105 ° F to 185 ° F. THE</td>
<td>temperature</td><td>of the</td><td>return</td><td>of</td><td>refrigerant</td><td>typical 154 may</td>
<td>swing from</td><td> 160°</td><td>F to 180 ° F</td><td>or</td><td colspan="2">175 ° F to 195 ° F or 160 ° F to</td>
195 ° F.
The flow of refrigerant through the cooling system 150 and through the cha
<img file="MX339043B_D0071.tif" />
112A-H can be circulated, for example, by a centrifugal pump, as illustrated by cooling pump 156.
An example of a design basis for a cooling pump
156 is a released differential pressure of approximately 50 to 60 pounds per square inch (psig) of 50 to 30 million pounds per hour of refrigerant. The refrigerant rate can set the elevation of the maximum cooling temperature, for example, about 10 ° F or about 20 ° F. An example of a configuration of the 112A-H reactor jackets [Figure 8) is two parallel operated double-piping exchangers operated in parallel, with the inner piping (the reactor) having approximately 22 inches internal diameter, and the outer pipe (the jacket) that is approximately 28 inches in internal diameter. In this example, the total heat transfer area of the reactor jackets
112A-H on the eight supports is approximately 5,000 square feet. In another embodiment of the present techniques, the reactor may have twelve supports and, at the same 22-inch ID, a surface area of approximately 7,500 square feet. Larger reactors can provide more surface area, for example, a 70,000 gallon reactor can provide a
<img file="MX339043B_D0072.tif" />
IMPI 15,000 square foot cooling area W'.Sg'J ^ íloñEnAD
Refrigerant circulation can be a hydraulically complete, closed-loop system. An accumulation drum 155 can be used in the cooling circuit (i.e. at or near the pump suction
156) to maintain fluid in the total circuit and reduce fluctuations in cooling system pressure by compensating for hydraulic pressure caused by fluctuations in cooling temperature. In this way, the pressure can be kept substantially constant in the suction of the pump 156, controlling the level and pressure of the accumulation drum 155.
The flow rate of the total coolant through the cooling system and the reactor jackets can be maintained at a constant rate and can be measured on a flow element 158. The flow element 158 can represent, for example, an orifice plate. flow installed in the cooling pipe. A control system can calculate the circulation flow rate based on the orifice size and the measured downstream and upstream pressures. The indication of the flow rate of the flow element 158 can be received by the flow controller 160, which can be a control block in a distributed control system (DCS). By
<img file="MX339043B_D0073.tif" />
example, a distributed control system to control a reactor is the Honeywell control system
TDC-3000. To maintain a constant total flow, the output of flow controller 160, using a control signal
166, can adjust the position of valve 162 on a flow diversion line 164. Typically, it is desirable to minimize movement of valve 162 position to avoid cyclical operation on the cooling pump
156. In this way, additional means at other points in the system can help keep the refrigerant circulation flow rate constant.
During normal operation of a suspension reactor with circuit 110, heat is removed from the reactor contents and heat is exchanged in cooler 168, which may represent one or more coolers. Heat is removed from the coolant in cooler 168 to cool the coolant supply 152 to the reactor jackets
112A-H. Cooler 168 may be, for example, a shell and tube heat exchanger or a plate and frame heat exchanger. A cooling medium, such as cooling tower water or seawater, flows through the cooler opposite the refrigerant, removing heat through the heat transfer surface area, but without mixing with the refrigerant. The flow of the medium
<img file="MX339043B_D0074.tif" />
4 cooling
IMI is represented in this example emp 1 or irgifrírroStl
PE THE FAOlhtDAU INDUSTRIAL cooling water 172 and cooling water return 174. A cooling tower (not shown) can process the circulating cooling medium by removing heat from the cooling water return 174 and providing the water supply from chilled chilled
172. In this way, the water in the cooling tower removes the heat from the refrigerant, which instead removes the heat from the reactor 110. In one example, cooler 168 represents six plate and frame exchanger coolers operating in parallel, with each plate and frame exchanger having approximately 200 stainless steel (304) plates and approximately 1600 square feet of heat transfer surface, with the heat transfer coefficient varying from about 100 to about
300 Btu / h / sq. Ft / ° F, as a function of refrigerant flow rate and suspension flow rate and other variables. Heat removed from the reactor can be approximately 15.5 million Btu per cooler, assuming a design pressure drop of approximately 3 psig on the coolant side. For temperature control, coolant controller 176 (coolant temperature controller) maintains the temperature of the coolant supply to the reactor jacket. The
<img file="MX339043B_D0075.tif" />
valve 170 (and refrigerant controller 176 sends to adjust the positions of potentially other valves).
SAW. Circuit reactor pump
The present techniques provide the use of guide impellers in the circuit reactor pump circulating the reactor contents. The addition of guide impellers can improve pump efficiency, reduce electrical consumption, and decrease normalized electrical usage by increasing the rate of polyolefin production on pumps that lack guide impellers. In addition, efficiency improvements on pumps with guide impellers can be obtained using mixed flow pumps, as described in the following sections.
A. Guide drives
In addition to the improved pump efficiency, the implementation of the guide impellers can improve various performance characteristics of the circuit reactor and the circuit reactor pump compared to pumps without guide impellers. For example, pumps that use guide impellers may have head pressures that range from 5 to 25% higher than pumps that are guide impellers. As described below, pumps with
IMPI guide boosters can provide iNsanLuteoexicA.'toa <sup>LL</sup> DE LA MOHEDA!)
INDUSTRIAL circulation, high pump differential pressure and high expected solids operating capacity in the circuit reactor, among others. These characteristics of the pump can allow high production rates of polyolefin polymers from large reactors. In the case of a 70,000-gallon, 24-inch outside diameter (OD) circuit reactor, the use of guide impellers on the reactor pump can provide polyolefin production in the range of 1.0 to 1.2 trillion pounds of polyolefin per year. Guide impellers can be used in new installations or as a replacement during series production of existing circuit reactor pumps to increase pump head and suspension speed, which can facilitate a higher level of solids (for example, greater than about 45%).
Guide drives can be used, for example, on circuit pumps that have a nominal OD in the range of 20 inches to 32 inches. These pumps can have 240-300 head feet at 35,000-40,000 gallons per minute (gpm) with an improvement in pump efficiency in the range of 1-4% for pumps without guide impellers. Guide impellers allow a larger reactor, for example 55,000 gallons or more, to have the same
<img file="MX339043B_D0076.tif" />
<img file="MX339043B_D0077.tif" />
IMPI,
INSTITUTO MEXICANO running speed than one more reactor, example, 35,000 gallons or less. For example · a 30-inch hnmha that has guiding impellers can provide adequate circulation in a 45,000-55,000-gallon reactor, while a 30-inch pump without guiding impellers cannot provide adequate circulation. Other configurations that can be used in the reactors of the present techniques can include larger pump diameters (eg, 40 inches or more) or use two reactor pumps, and so on.
In general, three to six guide impellers can be employed, with each impeller having a relative impeller angle in the range of 0 to 30 degrees. The relative impeller angle is the angle of the guide impeller relative to the angle of the leading edge of the pump impeller.
In other words, the relative impeller angle is the difference in the average angle of the guide impeller outlet and the leading angle of the pump vane relative to the plane of rotation of the impeller. In general, a higher positive number of the relative impeller angle means that the reactor suspension is rotated less by the pre-rotated guide impellers, while, in general, a smaller or negative number means that the suspension is rotated more. The direction of the pre-rotated rotation of the
<img file="MX339043B_D0078.tif" />
θ MEXICAN INSTITUTE., ....,,, OF THE PROPERTY suspension is in the opposite direction of the inijdo-oíic propeller pump.
A typical guide driver can be welded to the wall of the reactor line upstream of the pump driver. The placement of the guide impellers can be
0.1 to 2 pipe diameter upstream of pump impeller. Guide impellers can be placed close to the impeller shaft and upstream of the reactor flange
<td>which connects to</td><td>the</td><td>suction pump</td><td>. In</td><td>this</td><td>case the</td>
<td>dismantling</td><td>the</td><td>suction pipe</td><td>of</td><td colspan="2">the pump can</td>
<td>be provided</td><td colspan="2">where the drivers of</td><td>guide</td><td>I dont know</td><td>prolong</td>
<td>downstream</td><td>of</td><td>the flange.</td><td></td><td></td><td></td>
In one example, the guide drives start at approximately 24 inches in length, 6-7 inches in height, and 0.6-0.9 inches in thickness. The guide impellers can be bent and bent so that the guide impellers are substantially parallel to the flow direction and the discharge end is at the desired relative angle, while continuing along the inside of the suction pipe of the bomb. The upstream edge of the guide impellers may be tilted so that if debris or large fragments of polymer (e.g. string polymer or springs) are caught in the upstream edge, the debris or fragments may tend to slip
<img file="MX339043B_D0079.tif" />
IMPI
INSTITUTO MEXICANO advantageously towards the center of the pipe free of the guide impellers.
B. Improvements to the reactor pump
Circuit reactors are often scaled in size to a constant diameter, to maintain a relatively constant ratio of heat transfer area to volume.
For large loop reactors, for example 55,000 gallons or more, the length of the flow loop and the pressure drop of the suspension flowing around the loop can be significant, which could lead to sedimentation of the suspended polymer and particles of catalyst. To facilitate suspension of the particles in the diluent, various techniques can be used to provide sufficient reactor pump capacity. These techniques may include the use of multiple axial flow pumps, pumps that have guide valves, pumps that use large diameter thrusters (eg, 24 inches or more), low clearance between the thruster and the reactor wall ( eg 0.125 inch or less) or high rotational speed pumps (eg greater than about 200 RPM). These techniques can be used simply or in combination to improve flow in the reactor.
Additional improvements in pumping efficiency <sup>80</sup> Ϊ Me Ρ I can be achieved by using mixing. A mixed flow pump can have the characteristics of an axial flow pump (for example, having the suspension flow through the impeller and into the pump elbow) and a radial flow pump (for example, where the pumped fluid or suspension enters the pump eye and leaves the outside radius of the pump, for example degrees out of the plane of the inlet stream). In a mixed flow pump, the suspension stream can leave the impeller at an angle of deviation from the direction of the inlet flow to the outside radius of the pump, although generally not at the typical 90 degrees of a radial flow. The pump casing downstream of the impeller / impeller, then converts the backflow to an axial direction and then around an elbow. Compared to a pump that uses only guide impellers, the mixed flow pump can provide more pump head and facilitate the construction of longer, and thus larger, circuit reactors (for example, by increasing the size of the reactor from approximately 55,000 gallons to more than approximately 70,000 gallons). Also, the flow rate of a mixed flow pump can be less than pumps that have only guide impellers, which can decrease stress on the polymer pellet.
IMPI
<img file="MX339043B_D0080.tif" />
1 and generate mixed or efficiency
VII.
less fine in the impellers and lower consumption
Continuous intake of, _,, INDUSTRIAL reactor. Guide fiuj pumps can allow more energy.
discharge of reactor effluent
Figures 11-13 illustrate a continuous take-off mechanism for reactor discharge 22. Referring to Figure 11, a continuous take-off mechanism 180 is shown, positioned at one elbow of the reactor pipeline in circuit suspension
110. Continuous tap mechanism 180 includes a tap cylinder 182, a suspension removal line 184, an emergency stop valve 185, a proportional motor valve
186 to regulate flow and an expansion line 187. For example, when the diluent inlet is kept substantially constant, and proportional to engine valve 186, it can be used to control the continuous extraction rate that can maintain the total pressure of the reactor within designated designated points.
Referring to Figure 12, which illustrates a cross section taken along the section line
11-11 of Figure 11, a smooth, curved pipe elbow having a continuous tapping mechanism 180 is shown. In this way, the elbow of the illustrated cutlery can be considered an elbow carrying an accessory. As shown,
<img file="MX339043B_D0081.tif" />
ΙΜΡΪ The mechanism includes a tapping cylinder 182 which is attached, in this case, at a right angle to a tangent to the outer surface of the elbow. In addition, coupling to cylinder 182 is suspension withdrawal line 184. A ram valve 188 is placed within intake cylinder 182, which may have at least two purposes. First, you can provide a cleaning mechanism for the intake cylinder if, for example, it becomes clogged with the polymer.
Second, it can serve as a shutoff valve for mounting the full continuous intake.
Pickup cylinder 182 can be attached tangentially to the bend of the elbow, just before the suspension flow changes upward as illustrated in Figure
13. The opening can be elliptical with respect to the inner surface, for example, and additional elongation can be implemented to improve solids uptake. A variety of orientations of the socket cylinder union 182 can be implemented. For example, the socket nozzle can be located 45 degrees around the outside of the elbow, as shown in Figure 12. The angle around the outside of the elbow can be 0 to 90 degrees from the lowest point of the elbow downstream of the two elbows connecting a pair of supports.
Modeling calculations indicate that it can be located
ΙΜΡΙ '^ 3 |> ^, an improved site between around 20 and
INDUSTRIAL Sja ** W ^^ of this elbow. Also, the nozzle can be oriented from 0 to 90 degrees from the line perpendicular to a tangent drawn from the outside of the elbow. For comparison, Figures 11 and 12 illustrate a 90 degree orientation, and the
Figure 13 illustrates 0 degrees. The direction of orientation is in the direction of flow, as shown in Figure 11.
Orientations are possible outside of flex in the circuit, but may be less efficient. The intake nozzle can also be slightly extended in the flow, with the end cut perpendicular or at an angle. If the nozzle is cut at an angle, it is inserted so that the nozzle would be level with the reactor wall at the outer radius. For example, the nozzle can be cut at a 45 degree angle, with the shorter side of the nozzle flush with the elbow wall and the longer side adhering to the flow in the reactor.
Continuous uptake of a product suspension from a define polymerization reaction carried out in a loop reactor allows operation of the reactor at a higher average solids concentration than with conventional settling support (s) used for intermittent discharge the polymer pellet from a reactor. For example, the production of predominantly polymers of
<img file="MX339043B_D0082.tif" />
IMPI <sup>84</sup> -ISSSS ethylene (polyethylene) in a diluent of iáfS'EFBfánoT' — in general, has been limited to a maximum concentration ttc solids in the reactor of approximately 40-45 weight percent (%
p) with the configuration of the sedimentation support. However, continuous intake (CTO) has been found to allow a significant increase in the solids concentration of the average reactor. As a result, the solids concentration greater than 50% by weight in the reactor, could be implemented with continuous intake.
It should be emphasized that in a commercial operation, a point increase as low as a percentage in solids concentration is of primary significance.
Such an increase, for example, allows higher rates of polyethylene production, and thus generally provides an increase in standardized energy efficiency. Furthermore, less liquid in the discharge of reactor 22 can give less load in the downstream recovery and fractionation systems 22 and 24, and thus reduce downstream energy consumption. Furthermore, this technique can present savings in electrical consumption, since the discharge from the continuous intake removes finer from the reactor than conventional discharge. With less particle surface area in the reactor, the fluid mixture can operate at a lower viscosity (for example, as much as 10% less), providing easier circulation<sup>INS</sup>í® ™ ílíSÍ¡DA & e
INDUSTRIAL
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INDUSTRIAL through the reactor, and thus, less demand for pumping
<img file="MX339043B_D0083.tif" />
and the associated horsepower requirements (eg, as much as 10% less).
The concentration of solids in the modalities of the present techniques, can be increased on the reactions that use isobutane diluents, through the use of semi-supercritical propane as a diluent, for example, by 5-10%. The lower solubility of polyolefin in propane against isobutane, described above, or other diluents, and the lower density of propane against isobutane, described above, may contribute to this improvement. Decreasing the solubility can allow a further increase in the polyolefin solids without increasing the reactor clogging of the dissolved polymer.
For example, the embodiments of the present techniques may allow a solids concentration of about 55% by weight or greater to be used. Furthermore, decreasing the density of propane against isobutane can decrease the energy used to keep solids suspended while circulating in the reactor.
Increasing the solids carrying capacity of the reactor also increases the ability to operate the reactor at a higher space-time yield (eg 2.6 or
<img file="MX339043B_D0084.tif" />
product
IMPI „ <sub>r</sub> MEXICAN INSTITUTE
O Ό OE THE PROPERTY
INDUSTRIAL LARGEST) measured in pounds of polymeric product produced per hour per gallon of reactor volume or equivalent measures. Such an increase in spacetime throughput, in conjunction with a reduced incidence of reactor clogging can result in increased polyolefin production and throughput in reactor 10.
VJII. Extrusion / discharge system
Referring to Figure 14, a process flow diagram of the extrusion / discharge system 36 of Figure 1 is depicted. In this embodiment, the polyolefin pellet
136 from purge column 132 of Figure 8 can be transferred directly, for example, using a dilute phase blower, to the extruder for processing. However, since the upstream blowdown column 132 can also function as the extruder feed tank, the conveyor system for conveying pellet 136, and thus the associated electrical consumption of the blower in the conveyor system, can removed as described with respect to Figure 8 above. Also, in this configuration, pellet 136 may be hotter (eg, 150 ° F to 180 ° F) than if it were to run through the cooling effect (eg, cooled to 80-100 ° F) of nitrogen or air in a transportation system. The use of hot pellet 136 can decrease the energy used by
IMPI
<img file="MX339043B_D0085.tif" />
melt the incoming pellet temperature of the final melting pellet for those of the energy input the extruder 190 to heat and
136. Specifically, the higher the temperature constant speed extruders can increase.
Purge column 132 can be isolated from extruder 190 by a closing hopper 192 configured to prevent steam from flowing from purge column 132 into extruder 190. Closing hopper 192 can be configured using a number of devices, such as valves motor, rotary valves, storage space and the like.
In the mode shown in Figure 14, the closing hopper
192 it can be made from two rotary valves 194 that enclose a section 196 of the vertical line connecting the blowdown column 132 to the extruder 190. The rotary valves
194 they can feed the polyolefin pellet 136 to the extruder 190, where the extruder heats, melts, and pressurizes the polyolefin pellet 136. The pellet 136 of the purge column 132 can be dosed to the extruder 190 with a variety of meters, such as a type of smart flow meter, master feeder type, etc.
In addition, additives 198 can be injected into pellet stream 136 at an addition rate that can be based on a specified ratio at the rate of
<img file="MX339043B_D0086.tif" />
IMPI
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INDUSTRIAL
198 to pellet 136 oara Generating a mass flow recipe of the additive slave feed pellet can be specified on a desired valve, for example, for each polyolefin grade or product, and to give the desired properties of downstream polyolefin granules. Furthermore, the addition of additive 198 can be performed with a liquid additive system, weight loss feeders, and the like. In some embodiments, one or more of the weight loss feeders can be used to dose a pre-mixed additive package fed from a volumetric container, for example, to extruder 190 via pellet stream 136, a hopper from the extruder, directly to the extruder 190, etc.
With the removal of storage silos between the purge column and associated pellet residence time, the polymerization rate (as described with respect to Figure 8) can be more closely coupled in operation with the extrusion rate ( see figure
14). Techniques can be implemented in the operation of polymerization reactor 110 in reactor system 20 (Figure 8) to allow reactor 110 to return to the polyolefin pellet production rate, for example, to accommodate difficulties in the system. by _ _ MSTTTVTO MEXICANO
9 OF THE PROPERTY
INDUSTRIAL ____ _____ extrusion / discharge downstream 36 that may have been
<td>wealthy</td><td>by</td><td>the</td><td>capacity</td><td>of</td><td>accumulation of</td><td>a silo of</td>
<td>pellet.</td><td>By</td><td colspan="2">example if</td><td>the</td><td>extruder 190 se</td><td>interrupts</td>
<td colspan="2">temporarily,</td><td>the</td><td>reactor</td><td>of</td><td>polymerization</td><td>110 can</td>
undergo mini-kill or partial kill, where a relatively small portion (eg, parts per billion range) of catalyst poison, such as carbon monoxide, is injected into reactor 110 to temporarily kill the polymerization. In this way, if a temporary interruption of the extruder 190 or other equipment occurs in the extrusion / discharge system 36, the discharge of the polyolefin pellet 136 is temporarily stopped or reduced from the discharge 22 of the reactor 110 due to the lack for polymerization in reactor 110. Therefore, residence time in purge column 132 may be adequate to retain inlet pellet 136 until extruder operation is restarted.
In other embodiments, one or more silos (not shown) can be used for temporary storage of the reactor pellet. These silos can include an extruder pellet silo and, optionally, one or more pellet storage silos. While additional silos can decrease the use of complex control schemes to balance production rates between
<img file="MX339043B_D0087.tif" />
IMPI qn MEXICAN INSTITUTE <sup>J</sup> FROM PROPERTY reactor 110 and extruder 190, these can increase plant construction and operating costs, for example, by increasing the energy demand for blowers to transport the pellet between silos.
In general, extruder 190 can melt, homogenize, and pump the polyolefin polymer and additives through a granulator 200, which may include, for example, a sieve packing and a heated die head, which granulates the mixture. of the pellet and additives.
Also, the granulator blades (i.e. under water) can cut the molten polyolefin extrudate through the die into granules. Granules can be quenched with 202 water and can travel in a granule-water suspension
204 from granulator 200 to a granule dehydration dryer 206. Dryer 206 can separate free water and then dry the remaining surface water of the granules by centrifugal force. The dried granules
208 can be unloaded, for example, on the scalded screen
210, which removes the largest and smallest-sized granules from the granules in specification 212.
Water 202 can be supplied to granulator 200 from a water tank 214 by means of a centrifugal pump 216 and a cooler 218 (eg, a shell and tube heat exchanger). Water 219 withdrawn from the granule dryer
ΙΜΡΙ
<img file="MX339043B_D0088.tif" />
Q 1 MEXICAN INSTITUTE <sup>J</sup> -<sup>1</sup>- OF THE PROPERTY
206 it can be returned to the water tank 214. The polyolefin granules ”212 that come out of the scalded screen 210 can fall by gravity through the rotary valve 220 in a dense phase pneumatic conveying line 222, for example, and transported to the silos Granule silos 224. Granule silos may include storage tanks, mixers, out-of-spec storage tanks, etc. In the illustrated embodiment, blower packing 226 provides nitrogen and / or air 228 to transport granules 212 via conveying line 222 to granule silos 224. Polyolefin granules 226 can be loaded onto rail carriages 228. , hopper cars, trucks, big bags, bags, etc. Granules 226 can be loaded onto rail carriages 228, for example, using a multi-duct, air-assisted gravity-type loading system. Such a system can allow the hopper cart to be automatically loaded at a rate greater than the polymerization and extrusion production rate. In this way, the additional time generated by the higher discharge rates can be exploited to provide the time to move the hopper cars or rail cars after filling, and to choose the next empty cart 228.
While the techniques described above can
<img file="MX339043B_D0089.tif" />
IMPL being susceptible to different modifications or alternative forms, the specific modalities have been shown by way of example in the figures. However, it should be understood that the techniques are not intended to be limited to the particular forms described. In fact, the techniques encompass all modifications, equivalents, and alternatives that fall within the spirit and scope of the techniques, as defined by the following appended claims.
IMPI
<img file="MX339043B_D0090.tif" />
Contents56
102 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5 Sheet 6 Sheet 7 Sheet 8 Sheet 9 Sheet 10 Sheet 11 Sheet 12 Sheet 13 Sheet 14 Sheet 15 Sheet 16 Sheet 17 Sheet 18 Sheet 19 Sheet 20 Sheet 21 Sheet 22 Sheet 23 Sheet 24 Sheet 25 Sheet 26 Sheet 27 Sheet 28 Sheet 29 Sheet 30 Sheet 31 Sheet 32 Sheet 33 Sheet 34 Sheet 35 Sheet 36 Sheet 37 Sheet 38 Sheet 39 Sheet 40 Sheet 41 Sheet 42 Sheet 43 Sheet 44 Sheet 45 Sheet 46 Sheet 47 Sheet 48 Sheet 49 Sheet 50 Sheet 51 Sheet 52 Sheet 53 Sheet 54 Sheet 55 Sheet 56 Sheet 57 Sheet 58 Sheet 59 Sheet 60 Sheet 61 Sheet 62 Sheet 63 Sheet 64 Sheet 65 Sheet 66 Sheet 67 Sheet 68 Sheet 69 Sheet 70 Sheet 71 Sheet 72 Sheet 73 Sheet 74 Sheet 75 Sheet 76 Sheet 77 Sheet 78 Sheet 79 Sheet 80 Sheet 81 Sheet 82 Sheet 83 Sheet 84 Sheet 85 Sheet 86 Sheet 87 Sheet 88 Sheet 89 Sheet 90 Sheet 91 Sheet 92 Sheet 93 Sheet 94 Sheet 95 Sheet 96 Sheet 97 Sheet 98 Sheet 99 Sheet 100 Sheet 101 Sheet 102
26 members in 8 offices
Priority claims9
| Document | Office | Kind | Date |
|---|---|---|---|
| 12699729 | United States of America | – | |
| 69972910 | United States of America | A | |
| 69972910 | United States of America | A | |
| 2011022812 | United States of America | W | |
| 2011022812 | United States of America | W | |
| 12699729 | – | – | – |
| US1122812 | – | – | – |
| US20100699729 | – | – | – |
| WO2011US22812 | – | – | – |
Members26
| Document | Office | Kind | |
|---|---|---|---|
| US2011190465A1 | United States of America | A1 | |
| CA2788618A1 | Canada | A1 | |
| WO2011097119A1 | World Intellectual Property Organization (WIPO) | A1 | |
| MX2012009014A | Mexico | A | |
| CN102741302A | China | A | |
| EP2531534A1 | European Patent Office (EPO) | A1 | |
| RU2012137216A | Russian Federation | A | |
| US8871886B1 | United States of America | B1 | |
| US2014329977A1 | United States of America | A1 | |
| US2014343236A1 | United States of America | A1 | |
| US9120886B2 | United States of America | B2 | |
| US2015329650A1 | United States of America | A1 | |
| EP2531534B1 | European Patent Office (EPO) | B1 | |
| CN102741302B | China | B | |
| MX339043BThis record | Mexico | B | |
| US9358515B2 | United States of America | B2 | |
| US2016251459A1 | United States of America | A1 | |
| US2016346750A1 | United States of America | A1 | |
| US9605095B2 | United States of America | B2 | |
| US2017158784A1 | United States of America | A1 | |
| CA2788618C | Canada | C | |
| US9809660B2 | United States of America | B2 | |
| US9962670B2 | United States of America | B2 | |
| BR112012019358A2 | Brazil | A2 | |
| EP2531534B2 | European Patent Office (EPO) | B2 | |
| BR112012019358B1 | Brazil | B1 |
1 legal event, as the office reported them to INPADOC
Events
| Event | Code | |
|---|---|---|
| Grant or registrationFG | FG |
Numbers
- Publication
- 339043
- Publication, DOCDB
- 339043
- Publication, EPODOC
- MX339043
- Application
- 2012009014
- Application, DOCDB
- 2012009014
- Application, EPODOC
- MX20120009014
Titles
- Spanish
- DILUYENTE LIQUIDO COMPRESIBLE EN LA POLIMERIZACION DE POLIOLEFINAS.
Classification
- CPC, 7
- B01J8/005
- B01J19/1837
- B01J2219/00094
- B01J2219/00162
- B01J2219/00272
- C08F10/00
- B01J19/0013
- IPC, 3
- C08F10 00
- C08F2 14
- B29C48 30