EP4652209A1

EP4652209A1 - Ethylene-based polymer and method of producing an ethylene-based polymer

Info

Publication number: EP4652209A1
Application number: EP24712357.3A
Authority: EP
Inventors: Florian JOGWICK; Christoph TRÜMPER; Robert GÄRTNER; Yi Ye; Nhi DANG
Original assignee: Dow Global Technologies LLC
Current assignee: Dow Global Technologies LLC
Priority date: 2023-02-16
Filing date: 2024-02-05
Publication date: 2025-11-26
Also published as: KR20250149750A; CN120641445A; WO2024173085A1; JP2026505659A

Abstract

Embodiments of the present disclosure are directed to a method of producing an ethylene-based polymer comprising: separating a reactor effluent from a reactor into a gas stream containing unreacted monomers and a polymer stream in a high-pressure separator, separating an off-gas from the polymer stream in a medium-pressure separator, wherein the medium-pressure separator is disposed between the high-pressure separator and a low-pressure separator, sending the off-gas from the medium-pressure separator to a primary compressor, separating a remaining polymer stream from the medium-pressure separator into an off-gas and the ethylene-based polymer in the low-pressure separator, sending the off-gas from the low-pressure separator to a booster compressor, where the booster compressor is disposed between the low-pressure separator and the primary compressor, pressurizing the off-gas from the low-pressure separator in the booster compressor, and sending the pressurized off-gas from the booster compressor to the primary compressor.

Description

ETHYLENE -BASED POLYMER AND METHOD OF PRODUCING AN ETHYLENE-BASED POLYMER

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Application Serial No. 63/485371 filed February 16, 2023, the entire contents of which are incorporated by reference in the present disclosure.

TECHNICAL FIELD

[0002] Embodiments of the present disclosure generally relate to ethylene-based polymers and methods of producing an ethylene-based polymer.

BACKGROUND

[0003] High pressure polymer resins are produced in an autoclave reactor, a tubular reactor, or both, at high pressure, such as greater than or equal to 1000 bars (bar refers to bar gauge unless specified otherwise). In the high pressure polymerization process, the reactor effluent from the reactor may be separated in a high-pressure separator and subsequently in a low-pressure separator. It is found that when the production rate is increased (higher reactor feed rate and/or debottlenecking reactor for higher conversion), the gas entrainment in the polymer stream from the high-pressure separator to the low-pressure separator is increased. This may result in more polymer getting carried over in the low-pressure separator. The polymer carried over may be deposited on the top and the wall of the low-pressure separator and be cross-linked or mixed with high and low melt index contaminants. This may result in increased gel levels in the final products, thus increasing off-grades.

[0004] Gel performance and production rate may be improved by redesigning or replacing the low-pressure separator. However, in some cases, the building structure does not support the new or redesigned low-pressure separator. Moreover, capacity limitations of the booster compressor, which increases pressure for the off-gas from the low-pressure separator, are present even with redesigned low-pressure separators. [0005] Accordingly, there is a continual need for improved methods of producing an ethylenebased polymer, which enhance the production process by reducing gel formation in the low- pressure separator and compensating for capacity limitations in the booster compressor.

SUMMARY

[0006] Embodiments of the present disclosure address to meet this need by providing a medium-pressure separator between a high-pressure separator and a low-pressure separator. The off-gas separated from the medium-pressure separator is sent to a primary compressor. The offgas separated from the low-pressure separator is sent to a booster compressor, which is disposed between the low-pressure separator and the primary compressor. The off-gas from the low- pressure separator is pressurized in the booster compressor, and then sent to the primary compressor. These treatments of off-gases from the medium-pressure separator and the low- pressure separator may reduce gel formation in the low-pressure separator, compensate for booster compressor limitations, and increase the production rate of ethylene-based polymer. By separating the off-gas from the polymer stream in the medium-pressure separator, the medium-pressure separator may lower the gas entrainment to the low-pressure separator and remove the capacity limitation of the booster compressor while improving energy consumption.

[0007] According to one or more aspects of the present disclosure, a method of producing an ethylene-based polymer may comprise separating a reactor effluent from a reactor at a pressure of greater than or equal to 100 bars into a gas stream containing unreacted monomers and a polymer stream in a high-pressure separator, separating an off-gas from the polymer stream at a pressure of from 11 bars to 150 bars in a medium-pressure separator, wherein the medium-pressure separator is disposed between the high-pressure separator and a low-pressure separator, sending the off-gas from the medium-pressure separator to a primary compressor, separating a remaining polymer stream from the medium-pressure separator at a pressure of from 0.1 bars to 10 bars into an off-gas and the ethylene-based polymer in the low-pressure separator, sending the off-gas from the low-pressure separator to a booster compressor, where the booster compressor is disposed between the low-pressure separator and the primary compressor, pressurizing the off-gas from the low-pressure separator in the booster compressor, and sending the pressurized off-gas from the booster compressor to the primary compressor. [0008] Additional features and advantages of the described embodiments will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the described embodiments, including the detailed description which follows and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the drawings enclosed herewith.

[0010] FIG. 1 depicts a flowchart for producing an ethylene-based polymer, according to one or more embodiments described herein;

[0011] FIG. 2 schematically depicts a system for producing an ethylene-based polymer, according to one or more embodiments described herein; and

[0012] FIG. 3 schematically depicts a system for producing an ethylene-based polymer, according to Comparative Examples 3 and 4.

[0013] It should be understood that the drawings are schematic in nature, and do not include some components of a system of producing an ethylene-based polymer commonly employed in the art, such as, without limitation, temperature transmitters, pressure transmitters, flow meters, level transmitters, pumps, valves, and the like. It would be known that these components are within the spirit and scope of the present embodiments disclosed. However, operational components, such as those described in the present disclosure, may be added to the embodiments described in this disclosure.

[0014] Reference will now be made in greater detail to various embodiments, some embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts.

DETAILED DESCRIPTION

[0015] DEFINITIONS [0016] As used in this disclosure, a “reactor” refers to a vessel in which one or more chemical reactions may occur between one or more reactants optionally in the presence of one or more catalysts. For example, a reactor may include an autoclave or tubular reactor. One or more “reaction zones” may be disposed in a reactor. As used in this disclosure, a “reaction zone” refers to an area where a particular reaction takes place in a reactor.

[0017] As used in this disclosure, a “separator” refers to any separation device or system of separation devices that at least partially separates one or more chemicals that are mixed in a process stream from one another. For example, a separator may selectively separate differing chemical species, phases, or sized material from one another, forming one or more chemical fractions. Examples of separators include, without limitation, distillation columns, flash drums, knock-out drums, knock-out pots, centrifuges, cyclones, fdtration devices, traps, scrubbers, expansion devices, membranes, solvent extraction devices, and the like. It should be understood that separation processes described in this disclosure may not completely separate all of one chemical constituent from all of another chemical constituent. It should be understood that the separation processes described in this disclosure “at least partially” separate different chemical components from one another, and that even if not explicitly stated, it should be understood that separation may include only partial separation. As used in this disclosure, one or more chemical constituents may be “separated” from a process stream to form a new process stream. Generally, a process stream may enter a separator and be divided, or separated, into two or more process streams of the desired composition.

[0018] As used in this disclosure, the term “polymer” may refer to a polymeric compound prepared by polymerizing monomers, whether of the same or a different type. The generic term polymer thus embraces the term “homopolymer,” usually employed to refer to polymers prepared from only one type of monomer as well as “copolymer,” which refers to polymers prepared from two or more different monomers. The term “interpolymer,” as used herein, refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term interpolymer thus includes copolymers, and polymers prepared from more than two different types of monomers, such as terpolymers.

[0019] As used in this disclosure, the term “polyethylene” or “ethylene-based polymer” may refer to polymers comprising greater than 50% by mole of units which have been derived from ethylene monomer. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of ethylene-based polymer known in the art include Low Density Polyethylene (LDPE); Linear Low Density Polyethylene (LLDPE); Ultra Low Density Polyethylene (ULDPE); Very Low Density Polyethylene (VLDPE); single-site catalyzed Linear Low Density Polyethylene, including both linear and substantially linear low density resins (m- LLDPE); Medium Density Polyethylene (MDPE); and High Density Polyethylene (HDPE).

[0020] As used herein, “high pressure polymer resin” are polymers produced at pressures above 1000 bar and may include high-pressure copolymers or homopolymers. This may include ethylene homopolymer, such as LDPE, or high pressure ethylene copolymer. The term “LDPE” may also be referred to as “high-pressure ethylene polymer” or “highly branched polyethylene” and is defined to mean that the polymer is partly or entirely homopolymerized or copolymerized in autoclave or tubular reactors at pressures above 14,500 psi (100 MPa) with the use of free- radical initiators, such as peroxides (see for example US 4,599,392, which is hereby incorporated by reference). LDPE resins typically have a density in the range of 0.916 grams per cubic centimeter (g/cc) to 0.935 g/cc. Moreover, high pressure ethylene copolymers may include “ethylene acid copolymer”, which is a high pressure polymerized reaction product of ethylene and one or more unsaturated carboxylic acid containing monomers. In embodiments, the unsaturated carboxylic acid containing comonomer may include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, or combinations thereof. The high pressure ethylene copolymers may include ethylene/vinyl acetate (EVA), ethylene ethyl acrylate (EEA), ethylene butyl acrylate (EBA), ethylene methyl acrylate (EMA), ethylene vinyl silane (EVS), ethylene vinyl trimethyl silane (EVTMS), and other copolymers made with “silane-containing” comonomers, copolymers made with dienes (for example, ENB) or polyenes, and ethylene carbon monoxide (ECO), other vinyl monomers (other acrylates) or other terpolymers.

[0021] Similarly, as used in this disclosure, the term “high pressure polymerization process,” may refer to a free radical polymerization process performed at a pressure of at least 1000 bar, and optionally including an initiator or a mixture of initiators.

[0022] As used in this disclosure, the term ”a free radical initiator” may refer to a free radical generated by chemical and/or radiation means. The free radical initiator may be added at the start of the reaction, or it may be added continuously or in stages during the reaction (particularly when the monomer is so added). Examples of suitable free radical initiators include peroxyesters, peroxides, persulfates, perborates, percarbonates, azo compounds and the like. Specific examples of suitable free radical initiators include hydrogen peroxide, tert-butyl peroctoate, tert-butyl peracetate, di(t-butyl) peroxide, lauroyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, 2,2'-azobis [2,4-dimethyl]pentanenitrile, 2-(t-butylazo)-2-methylbutane nitrile, 2-(t-butylazo)-2- 4, dimethylpentanenitrile, azobis(isobutyronitrile), azobis(methylbutyronitrile) (AMBN), tertamyl peroxy 2-ethyl hexanoate and mixtures of any two or more thereof.

[0023] As used in this disclosure, the term “recycle,” may refer to unreacted reactant separated from the polymer in the high-pressure separator, the medium-pressure separator, and/or the low- pressure separator, and returned/compressed to the reactor.

[0024] As used in this disclosure, the term “feed,” or “feed flow,” or “feed stream,” may refer to make-up and/or recycle components, such as ethylene, initiator, or solvent, added to a reaction zone.

METHODS OF PRODUCING AN ETHYLENE-BASED POLYMER

[0025] Embodiments of the present disclosure are directed to methods of producing an ethylene-based polymer. The methods may include separating a reactor effluent from a reactor into a gas stream containing unreacted monomers and a polymer stream in a high-pressure separator, separating an off-gas from the polymer stream in a medium-pressure separator, wherein the medium-pressure separator is disposed between the high-pressure separator and a low-pressure separator, sending the off-gas from the medium-pressure separator to a primary compressor, separating a remaining polymer stream from the medium-pressure separator into an off-gas and the ethylene-based polymer in the low-pressure separator, sending the off-gas from the low- pressure separator to a booster compressor, where the booster compressor is disposed between the low-pressure separator and the primary compressor, pressurizing the off-gas from the low- pressure separator in the booster compressor, and sending the pressurized off-gas from the booster compressor to the primary compressor.

[0026] FIG. 1 depicts a flowchart 100 for producing an ethylene -based polymer, according to one or more embodiments described herein. FIG. 1 includes steps SI 10, SI 20, S 130, SI 40, S 150, S160, and S170, where the steps may be performed in that recited order (i.e., SI 10 prior to S120, S120 prior to S130, S130 prior to S140, S140 prior to S150, S150 prior to S160, and S160 prior to SI 70). Other steps may additionally be included in the methods described herein, and it should not be construed that the processes described herein are limited to only the steps of FIG. 1. FIG. 2 schematically depicts a system for producing an ethylene-based polymer, according to one or more embodiments described herein.

[0027] Referring to FIG. 2, a reactor effluent 211 may be produced with a high-pressure reactor 210. In embodiments, the reactor 210 may comprise an autoclave reactor, a tubular reactor, or both. The polymerization pressure may be in the range of at least 1000 bar, from 1000 to 5000 bar, from 1200 to 4000 bar, or from 1500 to 3500 bar. The polymerization temperature may be in the range of about 140 °C to about 330 °C. All individual values and subranges in the range of about 140 °C to about 330 °C are included herein and disclosed herein; for example, polymerization temperature is in the range of 150 °C to 320 °C. The reactor effluent 211 may be cooled by a cooler or ejector(s) from lower pressure part of the process.

[0028] In some embodiments as shown in FIG. 2, the recycle stream 261 may be provided to the reactor 210 from the primary compressor 260 for further polymerization. The reactor 210 may be disposed downstream of the primary compressor 260. The recycle stream 261 may include ethylene. The recycle stream 261 may further include free radical initiators.

[0029] In some embodiments, a secondary compressor (not shown) may be disposed between the primary compressor 260 and the reactor 210. The secondary compressor may compress the recycle stream 261 from the primary compressor 260. In some embodiments, a pre-heater (not shown) may be disposed upstream of the reactor 210. The pre-heater may be disposed between the secondary compressor and the reactor 210. The pre-heater may heat the recycle stream 261 from the primary compressor 260 to the desired temperature, such as in the range of 60 °C to 180 °C, in particular, 120 °C to 180 °C, or 140 °C to 160 °C. Examples of the pre-heater include, without limitation, a heat exchanger.

[0030] In some embodiments, a cooler (not shown) may be disposed upstream of the reactor 210. The cooler may be disposed between the secondary compressor and the reactor 210. The cooler may cool the recycle stream 261 from the primary compressor 260 to the desired temperature, such as in the range of 20 °C to 80 °C, in particular, 20 °C to 60 °C. Examples of the cooler include, without limitation, a heat exchanger. After finishing the reaction, the reactor effluent 211 may be depressurized, cooled, or both, and then sent to the high-pressure separator 220.

[0031] The reactor effluent 211 from the reactor 210 may include unreacted ethylene monomer, ethylene-based polymer, and optionally additional unreacted comonomers, chain transfer agents, or both. In one or more embodiments, a concentration of ethylene-based polymer in the reactor effluent 211 may be from 10 weight percent (wt.%) to 50 wt.%, from 15 wt.% to 50 wt.%, from 20 wt.% to 50 wt.%, from 10 wt.% to 45 wt.%, from 15 wt.% to 45 wt.%, from 20 wt.% to 45 wt.%, from 10 wt.% to 40 wt.%, from 15 wt.% to 40 wt.%, from 20 wt.% to 40 wt.%, from 10 wt.% to 35 wt.%, from 15 wt.% to 35 wt.%, from 20 wt.% to 35 wt.%, from 10 wt.% to 30 wt.%, from 15 wt.% to 30 wt.%, from 20 wt.% to 30 wt.%, from 10 wt.% to 25 wt.%, from 15 wt.% to 25 wt.%, or from 10 wt.% to 20 wt.% based on the total amount of the reactor effluent 211.

[0032] Still referring to FIG. 2 see also step SI 10 in FIG. 1), the reactor effluent 211 from the reactor 210 is separated into a gas stream containing unreacted monomers 221 and a polymer stream 222 in the high-pressure separator 220. The system of producing an ethylene-based polymer may include a plurality of high-pressure separators 220. The gas stream containing unreacted monomers 221 is discharged from the high-pressure separator 220 as off-gas.

[0033] The gas stream containing unreacted monomers 221 may include ethylene, chain transfer agents and solvents, optionally comonomer, as well minor amounts of additional components, such as less than or equal to 5 wt.%, less than or equal to 1 wt.%, less than or equal to 0.5 wt.%, or less than or equal to 0.1 wt.% of waxes, entrained polymer, or both. In one or more embodiments, the gas stream containing unreacted monomers 221 may consist essentially of ethylene monomer. In one or more embodiments, the gas stream containing unreacted monomers 221 may comprises from 0.1 wt.% to 50 wt.% of comonomer, for example vinyl acetate. In some embodiments, the gas stream containing unreacted monomers 221 may comprises from 1 mol.% to 10 mol.% of chain transfer agent comprising alkanes, alkenes, aldehydes, ketones, alcohols, ethers, esters, mercaptans or phosphines.

[0034] The polymer stream 222 may include ethylene-based polymers, such as FDPE. The polymer stream 222 may further include ethylene monomer. In one or more embodiments, a concentration of ethylene-based polymer in the polymer stream 222 may be from 50 wt.% to 99 wt.%, from 60 wt.% to 99 wt.%, from 70 wt.% to 99 wt.%, from 50 wt.% to 95 wt.%, from 60 wt.% to 95 wt.%, from 70 wt.% to 95 wt.%, from 50 wt.% to 90 wt.%, from 60 wt.% to 90 wt.%, or from 70 wt.% to 90 wt.% based on the total amount of the polymer stream 222.

[0035] The high-pressure separator 220 operates at a pressure of greater than or equal to 100 bars, greater than or equal to 150 bars, greater than or equal to 200 bars, or greater than or equal to 250 bars. In embodiments, the high-pressure separator 200 operates at a pressure of less than or equal to 650 bars, less than or equal to 600 bars, less than or equal to 550 bars, or less than or equal to 500 bars. In embodiments, the reactor effluent 211 from the reactor 210 is separated in the high-pressure separator 200 at a pressure of from 100 bars to 650 bars, from 150 bars to 650 bars, from 200 bars to 650 bars, from 250 bars to 650 bars, from 100 bars to 600 bars, from 150 bars to 600 bars, from 200 bars to 600 bars, from 250 bars to 600 bars, from 100 bars to 550 bars, from 150 bars to 550 bars, from 200 bars to 550 bars, from 250 bars to 550 bars, from 100 bars to 500 bars, from 150 bars to 500 bars, from 200 bars to 500 bars, from 250 bars to 500 bars, or any and all sub-ranges formed from any of these endpoints.

[0036] Moreover, the high-pressure separator 220 may operate at a temperature of from 140 °C to 310 °C, from 145 °C to 310 °C, from 150 °C to 310 °C, from 140 °C to 305 °C, from 145 °C to 305 °C, from 150 °C to 305 °C, from 140 °C to 300 °C, from 145 °C to 300 °C, from 150 °C to 300 °C, from 140 °C to 295 °C, from 145 °C to 295 °C, from 150 °C to 295 °C, from 140 °C to 290 °C, from 145 °C to 290 °C, from 150 °C to 290 °C, or any and all sub-ranges formed from any of these endpoints.

[0037] Still referring to FIG. 2 (see also step S120 in FIG. 1), an off-gas 231 is separated from the polymer stream 222 in a medium-pressure separator 230. The medium-pressure separator 230 may be disposed between the high-pressure separator 220 and the low-pressure separator 240. The medium-pressure separator 230 may be directly connected to both the high-pressure separator 220 and the low-pressure separator 240. The system of producing an ethylene-based polymer may include a plurality of medium-pressure separators 230.

[0038] By separating the off-gas 231 from the polymer stream 222, the medium-pressure separator 230 may lower the gas entrainment to the low-pressure separator 240 and remove the capacity limitation of the booster compressor 250 while improving energy consumption. [0039] The off-gas 231 may include ethylene monomer, optionally comonomer, as well as minor amounts of additional components, such as less than or equal to 5 wt.%, less than or equal to 1 wt.%, less than or equal to 0.5 wt.%, or less than or equal to 0.1 wt.% of waxes, entrained polymer, or both. In one or more embodiments, the off-gas 231 may consist essentially of ethylene monomer.

[0040] The polymer stream 232 may include ethylene-based polymers, such as FDPE. The polymer stream 232 may further include ethylene. In one or more embodiments, a concentration of ethylene-based polymer in the polymer stream 232 may be from 50 wt.% to 95 wt.%, from 55 wt.% to 95 wt.%, from 60 wt.% to 95 wt.%, from 50 wt.% to 85 wt.%, from 55 wt.% to 85 wt.%, from 60 wt.% to 85 wt.%, from 50 wt.% to 75 wt.%, from 55 wt.% to 75 wt.%, from 60 wt.% to

75 wt.%, or from 60 wt.% to 70 wt.% based on the total amount of the polymer stream 232.

[0041] In one or more embodiments, from 0.1 wt.% to 35 wt.%, from 0.5 wt.% to 35 wt.%, from 1 wt.% to 35 wt.%, from 2 wt.% to 35 wt.%, from 5 wt.% to 35 wt.%, from 0.1 wt.% to 30 wt.%, from 0.5 wt.% to 30 wt.%, from 1 wt.% to 30 wt.%, from 2 wt.% to 30 wt.%, from 5 wt.% to 30 wt.%, from 0.1 wt.% to 25 wt.%, from 0.5 wt.% to 25 wt.%, from 1 wt.% to 25 wt.%, from

2 wt.% to 25 wt.%, from 5 wt.% to 25 wt.%, from 0.1 wt.% to 20 wt.%, from 0.5 wt.% to 20 wt.%, from 1 wt.% to 20 wt.%, from 2 wt.% to 20 wt.%, from 5 wt.% to 20 wt.% of reactor effluent 211 is diverted to the off-gas 231 in the medium-pressure separator 230.

[0042] Referring again to FIG. 2, in one or more embodiments, the off-gas 231 is separated from the polymer stream 222 in the medium-pressure separator 230 at a pressure of greater than or equal to 11 bars, greater than or equal to 13 bars, greater than or equal to 15 bars, or greater than or equal to 20 bars. In embodiments, the off-gas 231 is separated from the polymer stream 222 in the medium-pressure separator 230 at a pressure of less than or equal to 150 bars, less than or equal to 130 bars, or less than or equal to 110 bars. In embodiments, the medium-pressure separator 230 operates at a pressure of from 11 bars to 150 bars, from 13 bars to 150 bars, from 15 bars to 150 bars, from 20 bars to 150 bars, from 11 bars to 130 bars, from 13 bars to 130 bars, from 15 bars to 130 bars, from 20 bars to 130 bars, from 11 bars to 110 bars, from 13 bars to 110 bars, from 15 bars to 110 bars, from 20 bars to 110 bars, or any and all sub-ranges formed from any of these endpoints. [0043] In one or more embodiments, the medium-pressure separator 140 operates at a temperature of from 140 °C to 310 °C, from 145 °C to 310 °C, from 150 °C to 310 °C, from 140 °C to 305 °C, from 145 °C to 305 °C, from 150 °C to 305 °C, from 140 °C to 300 °C, from 145 °C to 300 °C, from 150 °C to 300 °C, from 140 °C to 295 °C, from 145 °C to 295 °C, from 150 °C to 295 °C, from 140 °C to 290 °C, from 145 °C to 290 °C, from 150 °C to 290 °C, or any and all subranges formed from any of these endpoints.

[0044] Still referring to FIG. 2 (see also step SI 30 in FIG. 1), the off-gas 231 from the mediumpressure separator 230 is sent to a primary compressor 260. The primary compressor 260 may be disposed downstream of the medium-pressure separator 230. The primary compressor 260 may be directly connected to the medium-pressure separator.

[0045] The primary compressor 260 may comprise single or multiple compressor frames. In some embodiments, the primary compressor 260 may be combined with a booster compressor frame.

[0046] The primary compressor 260 may compress the off-gas 231 from the medium-pressure separator 230. As described below, the primary compressor 260 may further compress the pressurized off-gas 251 from the booster compressor 250.

[0047] Still referring to FIG. 2 (see also step S140 in FIG. 1), a remaining polymer stream 232 is separated into an off-gas 241 and the ethylene-based polymer stream 242 in the low-pressure separator 240. The low-pressure separator 240 may be disposed downstream of the mediumpressure separator 230. The low-pressure separator 240 may be directly connected to the mediumpressure separator 230. The system of producing an ethylene -based polymer may include a plurality of low-pressure separators 240.

[0048] The off-gas 241 may include ethylene monomer, chain transfer agents and solvent, optionally comonomer, such as less than or equal to 5 wt.%, less than or equal to 1 wt.%, less than or equal to 0.5 wt.%, or less than or equal to 0.1 wt.% of waxes, entrained polymer, or both. In one or more embodiments, the off-gas 241 may consist essentially of ethylene monomer. In one or more embodiments, the ethylene-based polymer stream 242 may consist essentially of ethylenebased polymer. [0049] In one or more embodiments, from 0.1 wt.% to 35 wt.%, from 0.5 wt.% to 35 wt.%, from 1 wt.% to 35 wt.%, from 2 wt.% to 35 wt.%, from 5 wt.% to 35 wt.%, from 0.1 wt.% to 30 wt.%, from 0.5 wt.% to 30 wt.%, from 1 wt.% to 30 wt.%, from 2 wt.% to 30 wt.%, from 5 wt.% to 30 wt.%, from 0.1 wt.% to 25 wt.%, from 0.5 wt.% to 25 wt.%, from 1 wt.% to 25 wt.%, from 2 wt.% to 25 wt.%, from 5 wt.% to 25 wt.%, from 0.1 wt.% to 20 wt.%, from 0.5 wt.% to 20 wt.%, from 1 wt.% to 20 wt.%, from 2 wt.% to 20 wt.%, from 5 wt.% to 20 wt.% of reactor effluent 211 is diverted to the off-gas 241 in the low-pressure separator 240.

[0050] In one or more embodiments, the remaining polymer stream 232, which is discharged from the medium-pressure separator 230, is separated in the low-pressure separator 240 at a pressure of greater than or equal to 0.01 bars, greater than or equal to 0.05 bars, greater than or equal to 0.1 bars, or greater than or equal to 1 bar. In embodiments, the remaining polymer stream 232 is separated in the low-pressure separator 240 at a pressure of less than or equal to 10 bars, less than or equal to 9 bars, or less than or equal to 8 bars. In embodiments, the low-pressure separator 240 operates at a pressure of from 0.01 bars to 10 bars, from 0.05 bars to 10 bars, from 0.1 bars to 10 bars, from 1 bar to 10 bars, from 0.01 bars to 9 bars, from 0.05 bars to 9 bars, from 0.1 bars to 9 bars, from 1 bar to 9 bars, from 0.01 bars to 8 bars, from 0.05 bars to 8 bars, from 0.1 bars to 8 bars, from 1 bar to 8 bars, or any and all sub-ranges formed from any of these endpoints.

[0051] In one or more embodiments, the remaining polymer stream 232 is separated in the low-pressure separator 240 at a temperature of from 130 °C to 300 °C, from 135 °C to 300 °C, from 140 °C to 300 °C, from 130 °C to 295 °C, from 135 °C to 295 °C, from 140 °C to 295 °C, from 130 °C to 290 °C, from 135 °C to 290 °C, from 140 °C to 290 °C, from 130 °C to 285 °C, from 135 °C to 285 °C, from 140 °C to 285 °C, from 130 °C to 280 °C, from 135 °C to 280 °C, from 140 °C to 280 °C, or any and all sub-ranges formed from any of these endpoints.

[0052] Still referring to FIG. 2 see also step S150 in FIG. 1), the off-gas 241 from the low- pressure separator 240 is sent to a booster compressor 250. The booster compressor 250 may be disposed between the low-pressure separator 240 and the primary compressor 260. The booster compressor 250 may be directly connected to both the low-pressure separator 240 and the primary compressor 260. [0053] The booster compressor 250 may comprise single or multiple compressor frames. In some embodiments, the booster compressor 250 may be combined with a primary compressor frame.

[0054] In one or more embodiments, a capacity of the booster compressor 250 may be less than or equal to 20 wt.% of reactor effluent 211, less than or equal to 15 wt.% of reactor effluent 211, or less than or equal to 10 wt.% of reactor effluent 211. In one or more embodiments, a capacity of the booster compressor 220 may be greater than or equal to 0.1 wt.% of reactor effluent 211, or greater than or equal to 1 wt.% of reactor effluent 211. In one or more embodiments, a capacity of the booster compressor 250 may be from 0.1 wt.% to 20 wt.% of reactor effluent 211, from 1 wt.% to 20 wt.% of reactor effluent 211, from 0.1 wt.% to 15 wt.% of reactor effluent 211, from 1 wt.% to 15 wt.% of reactor effluent 211, from 0.1 wt.% to 10 wt.% of reactor effluent 211, from 1 wt.% to 10 wt.% of reactor effluent 211, or any and all sub-ranges formed from any of these endpoints.

[0055] Still referring to FIG. 2 (see also step SI 60 in FIG. 1), the off-gas 241 from the low- pressure separator 240 is pressurized in the booster compressor 250.

[0056] The booster compressor 250 may compress the off-gas 241 from the low-pressure separator 240. In one or more embodiments, the booster compressor 250 may increase the pressure of the off-gas 241 from the low-pressure separator 240 up to the suction pressure of the primary compressor 260.

[0057] In one or more embodiments, the booster compressor 250 may increase the pressure of the off-gas 241 from the low-pressure separator 240 to at least 10 bars, at least 11 bars, at least 12 bars, at least 13 bars, at least 14 bars, or at least 15 bars, for example 60 bars.

[0058] Still referring to FIG. 2 (see also step SI 70 in FIG. 1), the pressurized off-gas 251 from the booster compressor 250 is sent to the primary compressor 260. The primary compressor 260 may be disposed downstream of the booster compressor 250. The primary compressor 260 may be directly connected to the booster compressor 250. [0059] As described above, the primary compressor 260 compress the off-gas 231 from the medium-pressure separator 230. The primary compressor 260 may further compress the pressurized off-gas 251 from the booster compressor 250.

[0060] The primary compressor 260 may send the recycle stream 261 to the reactor 210. The recycle stream 261 may comprise the off-gas 231 from the medium-pressure separator 230, the off-gas 241 from the low-pressure separator 240, the pressurized off-gas 251 from the booster compressor 250, or combinations thereof. The recycle stream 261 may further include additional comonomers, chain transfer agents, and free radical initiators.

EXAMPEES

[0061] The following examples illustrate one or more additional features of the present disclosure. It should be understood that these examples are not intended to limit the scope of the disclosure or the appended claims in any manner.

[0062] Inventive Examples 1 and 2

[0063] FIG. 2 schematically depicts a system 200 for producing an ethylene-based polymer, according to Inventive Examples 1 and 2. In Inventive Examples 1 and 2, the high pressure polymerization was simulated for ethylene using Aspen Plus VI 0 from Aspen Technology. As shown in FIG. 2, the reactor effluent 211 from the reactor 210 was sent to the high-pressure separator 220. The reactor effluent 211 was separated into the gas stream containing unreacted monomers 221 and the polymer stream 222 in the high-pressure separator 310. The polymer stream 222 was sent to the medium-pressure separator 230. The polymer stream 222 was separated into the off-gas 231 and the polymer stream 232 in the medium-pressure separator 230. In Inventive Example 1, the pressure of the medium-pressure separator 230 was set at 30 bars. The 1500 kg/hr of the polymer stream 222 was diverted to the off-gas 231 from the medium-pressure separator 230. In Inventive Example 2, the pressure of the medium-pressure separator 230 was set at 100 bars. The 500 kg/hr of the polymer stream 222 was diverted to the off-gas 231 from the medium-pressure separator 230. The polymer stream 232 was sent to the low-pressure separator 240. The polymer stream 232 was separated into the off-gas 241 and the ethylene-based polymer (polyethylene) 242. The capacity of the booster compressor 250 was designed at 1850 kg/hr.

Tables 1 and 2 list temperature, pressure, flow rate and composition of each stream.

[0064] Table 1 - Inventive Example 1

[0065] Table 2 - Inventive Example 2

[0066] Comparative Examples 3 and 4

[0067] FIG. 3 schematically depicts a system 300 for producing an ethylene-based polymer, according to Comparative Examples 3 and 4. In Comparative Examples 3 and 4, the high pressure polymerization was simulated. The reactor effluent 311 from the reactor was sent to the high- pressure separator 310. The reactor effluent 311 was separated into the gas stream containing unreacted monomers 312 and the polymer stream 313 in the high-pressure separator 310. The polymer stream 313 was sent to the low-pressure separator 320. The polymer stream 313 was separated into the gas stream containing unreacted monomers 321 and the ethylene-based polymer (polyethylene) 322. The capacity of the booster compressor disposed downstream of the low- pressure separator 320 was designed at 1850 kg/hr. Tables 3 and 4 list temperature, pressure, flow rate and composition of each stream. [0068] Table 3 - Comparative Example 3

[0069] Table 4 - Comparative Example 4

[0070] As shown in Tables 1-4, the flow rate of the off-gas from the low-pressure separator in Inventive Examples 1 and 2 (1038 kg/hr and 1538 kg/hr) were lower than those of Comparative Examples 3 and 4 (1837 kg/hr and 2038 kg/hr). This shows that the medium-pressure separator in Inventive Examples 1 and 2 lowers the flow of the off-gas from the low-pressure separator by separating the off-gas from the medium-pressure separator.

[0071] When the capacity of the booster compressor was designed at 1850 kg/hr, Comparative Example 4 could not handle the off-gas from the low-pressure separator. Moreover, the increased flow of the off-gas from the low-pressure separator did not allow to design the low-pressure separator with higher vapor velocity, which increases polymer carry-over potential.

[0072] Moreover, as shown in Tables 1-4, the production rate of ethylene-based polymer of Inventive Examples 1 and 2 (9007 kg/hr and 9007 kg/hr) were greater than those of Comparative Example 3 (8106 kg/hr). This shows that the separation of the off-gas from the medium-pressure separator improves the production rate while reducing the potential for gelling in the low-pressure separator. While the production rate of the ethylene-based polymer of Comparative Example 4 was the same as the production rate of the ethylene -based polymer of Inventive Examples 1 and 2, as described above, Comparative Example 4 was not able to handle the off-gas from the low- pressure separator when the capacity of the booster compressor was designed at 1850 kg/hr.

[0073] A first aspect of the present disclosure may be directed to a method of producing an ethylene-based polymer comprising: separating a reactor effluent from a reactor at a pressure of greater than or equal to 100 bars into a gas stream containing unreacted monomers and a polymer stream in a high-pressure separator, separating an off-gas from the polymer stream at a pressure of from 11 bars to 150 bars in a medium-pressure separator, wherein the medium-pressure separator is disposed between the high-pressure separator and a low-pressure separator, sending the off-gas from the medium-pressure separator to a primary compressor, separating a remaining polymer stream from the medium-pressure separator at a pressure of from 0.1 bars to 10 bars into an off-gas and the ethylene-based polymer in the low-pressure separator, sending the off-gas from the low-pressure separator to a booster compressor, where the booster compressor is disposed between the low-pressure separator and the primary compressor, pressurizing the off-gas from the low-pressure separator in the booster compressor, and sending the pressurized off-gas from the booster compressor to the primary compressor.

[0074] A second aspect of the present disclosure may include the first aspect, wherein from 0.1 wt.% to 35 wt.% of reactor effluent is diverted to the off-gas in the medium-pressure separator.

[0075] A third aspect of the present disclosure may include either of the first or second aspects, wherein from 0.1 wt.% to 20 wt.% of reactor effluent is diverted to the off-gas in the mediumpressure separator.

[0076] A fourth aspect of the present disclosure may include any of the first through third aspects, wherein from 0.1 wt.% to 35 wt.% of reactor effluent from the reactor is diverted to the off-gas in the low-pressure separator.

[0077] A fifth aspect of the present disclosure may include any of the first through fourth aspects, wherein from 0.1 wt.% to 20 wt.% of reactor effluent from the reactor is diverted to the off-gas in the low-pressure separator. [0078] A sixth aspect of the present disclosure may include any of the first through fifth aspects, wherein the high-pressure separator is operating at a temperature of from 140 °C to 290 °C.

[0079] A seventh aspect of the present disclosure may include any of the first through sixth aspects, wherein the medium-pressure separator is operating at a temperature of from 130 °C to 290 °C.

[0080] An eighth aspect of the present disclosure may include any of the first through seventh aspects, wherein the low-pressure separator is operating at a temperature of from 130 °C to 280 °C.

[0081] A ninth aspect of the present disclosure may include any of the first through eighth aspects, wherein a capacity of the booster compressor is less than or equal to 20 wt.% of reactor effluent.

[0082] A tenth aspect of the present disclosure may include any of the first through ninth aspects, wherein a capacity of the booster compressor is less than or equal to 10 wt.% of reactor effluent.

[0083] An eleventh aspect of the present disclosure may include any of the first through tenth aspects, wherein the booster compressor increases the pressure of the off-gas from the low- pressure separator up to suction pressure of the primary compressor.

[0084] A twelfth aspect of the present disclosure may include any of the first through eleventh aspects, wherein the booster compressor increases the pressure of the off-gas from the low- pressure separator at least 10 bars.

[0085] A thirteenth aspect of the present disclosure may include any of the first through twelfth aspects, wherein the ethylene-based polymer comprises Low Density Polyethylene (LDPE).

[0086] A fourteenth aspect of the present disclosure may include any of the first through thirteenth aspects, wherein the ethylene-based polymer comprises high pressure ethylene copolymer. [0087] A fifteenth aspect of the present disclosure may be directed to the ethylene-based polymer produced from methods of any of the first through fourteenth aspects.

[0088] It is noted that one or more of the following claims utilize the term “wherein”, “where” or “in which” as a transitional phrase. For the purposes of defining the present technology, it is noted that this term is introduced in the claims as an open-ended transitional phrase that is used to introduce a recitation of a series of characteristics of the structure and should be interpreted in like manner as the more commonly used open-ended preamble term “comprising.” For the purposes of defining the present technology, the transitional phrase “consisting of’ may be introduced in the claims as a closed preamble term limiting the scope of the claims to the recited components or steps and any naturally occurring impurities. For the purposes of defining the present technology, the transitional phrase “consisting essentially of’ may be introduced in the claims to limit the scope of one or more claims to the recited elements, components, materials, or method steps as well as any non-recited elements, components, materials, or method steps that do not materially affect the novel characteristics of the claimed subject matter. The transitional phrases “consisting of’ and “consisting essentially of’ may be interpreted to be subsets of the open-ended transitional phrases, such as “comprising” and “including,” such that any use of an open ended phrase to introduce a recitation of a series of elements, components, materials, or steps should be interpreted to also disclose recitation of the series of elements, components, materials, or steps using the closed terms “consisting of’ and “consisting essentially of.” For example, the recitation of a composition “comprising” components A, B, and C should be interpreted as also disclosing a composition “consisting of’ components A, B, and C as well as a composition “consisting essentially of’ components A, B, and C. Any quantitative value expressed in the present application may be considered to include open-ended embodiments consistent with the transitional phrases “comprising” or “including” as well as closed or partially closed embodiments consistent with the transitional phrases “consisting of’ and “consisting essentially of.”

[0089] As used in the Specification and appended Claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly indicates otherwise. The verb “comprises” and its conjugated forms should be interpreted as referring to elements, components or steps in a non-exclusive manner. The referenced elements, components or steps may be present, utilized or combined with other elements, components or steps not expressly referenced. [0090] Further, when an amount, concentration, or other value or parameter is given as either a range, preferred range or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range. When a component is indicated as present in a range starting from 0, such component is an optional component (i.e., it may or may not be present). When present an optional component may be at least 0.1 weight % of the composition or copolymer.

[0091] When materials, methods, or machinery are described herein with the term “known to those of skill in the art”, “conventional” or a synonymous word or phrase, the term signifies that materials, methods, and machinery that are conventional at the time of filing the present application are encompassed by this description.

[0092] It should be understood that any two quantitative values assigned to a property may constitute a range of that property, and all combinations of ranges formed from all stated quantitative values of a given property are contemplated in this disclosure. The subject matter of the present disclosure has been described in detail and by reference to specific embodiments. It should be understood that any detailed description of a component or feature of one or more embodiments does not necessarily imply that the component or feature is essential to the particular embodiment or to any other embodiment. Further, it should be apparent to those skilled in the art that various modifications and variations can be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

Claims

1. A method of producing an ethylene-based polymer comprising: separating a reactor effluent from a reactor at a pressure of greater than or equal to 100 bars into a gas stream containing unreacted monomers and a polymer stream in a high-pressure separator; separating an off-gas from the polymer stream at a pressure of from 11 bars to 150 bars in a medium-pressure separator, wherein the medium-pressure separator is disposed between the high-pressure separator and a low-pressure separator; sending the off-gas from the medium-pressure separator to a primary compressor; separating a remaining polymer stream from the medium-pressure separator at a pressure of from 0.1 bars to 10 bars into an off-gas and the ethylene-based polymer in the low-pressure separator; sending the off-gas from the low-pressure separator to a booster compressor; where the booster compressor is disposed between the low-pressure separator and the primary compressor; pressurizing the off-gas from the low-pressure separator in the booster compressor; and sending the pressurized off-gas from the booster compressor to the primary compressor.

2. The method of claim 1, wherein from 0.1 weight percent (wt.%) to 35 wt.% of reactor effluent from the reactor is diverted to the off-gas in the medium-pressure separator.

3. The method of claim 1 or claim 2, wherein from 0.1 wt.% to 20 wt.% of reactor effluent from the reactor is diverted to the off-gas in the medium-pressure separator.

4. The method of any preceding claim, wherein from 0.1 wt.% to 35 wt.% of reactor effluent from the reactor is diverted to the off-gas in the low-pressure separator.

5. The method of any preceding claim, wherein from 0.1 wt.% to 20 wt.% of reactor effluent from the reactor is diverted to the off-gas in the low-pressure separator.

6. The method of any preceding claim, wherein the high-pressure separator is operating at a temperature of from 140 Celsius (°C) to 290 °C.

7. The method of any preceding claim, wherein the medium-pressure separator is operating at a temperature of from 130 °C to 290 °C.

8. The method of any preceding claim, wherein the low-pressure separator is operating at a temperature of from 130 °C to 280 °C.

9. The method of any preceding claim, wherein a capacity of the booster compressor is less than or equal to 20 wt.% of reactor effluent.

10. The method of any preceding claim, wherein a capacity of the booster compressor is less than or equal to 10 wt.% of reactor effluent.

11. The method of any preceding claim, wherein the booster compressor increases the pressure of the off-gas from the low-pressure separator up to suction pressure of the primary compressor.

12. The method of any preceding claim, wherein the booster compressor increases the pressure of the off-gas from the low-pressure separator at least 10 bars.

13. The method of any preceding claim, wherein the ethylene -based polymer comprises Tow Density Polyethylene (TDPE).

14. The method of any preceding claim, wherein the ethylene -based polymer comprises high pressure ethylene copolymer.

15. The ethylene-based polymer produced from any preceding claim.