Ethylene-based polymers and methods for producing ethylene-based polymers

Abstract

Embodiments of the present disclosure relate to a process for producing an ethylene-based polymer, the process comprising: separating a reactor effluent from a reactor in a high pressure separator into a gas stream containing unreacted monomers and a polymer stream, 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 the low-pressure separator, passing off-gas from the medium-pressure separator to a primary compressor, separating a remaining polymer stream from the medium-pressure separator into off-gas and ethylene-based polymer in the low-pressure separator, passing off-gas from the low-pressure separator to a booster compressor, and passing off-gas from the high-pressure separator to a secondary compressor. Wherein a booster compressor is disposed between the low pressure separator and the primary compressor, in which the exhaust gas from the low pressure separator is pressurized, and the pressurized exhaust gas from the booster compressor is passed to the primary compressor.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to U.S. application serial number 63 / 485,371, filed February 16, 2023, the entire contents of which are incorporated by reference into this disclosure. Technical Field

[0003] Embodiments of the present disclosure generally relate to ethylene-based polymers and methods of producing ethylene-based polymers. Background Art

[0004] High pressure polymer resins are produced in autoclave reactors, tubular reactors, or both at high pressures such as 1000 bar or greater (bar refers to bar gauge unless otherwise specified). In high pressure polymerization procedures, the reactor effluent from the reactor can be separated in a high pressure separator and subsequently separated in a low pressure separator. It has been found that as production rates increase (higher reactor feed rates and / or de-bottleneck reactors for higher conversions), gas entrainment in the polymer stream from the high pressure separator to the low pressure separator increases. This may result in more polymer being carried over into the low pressure separator. The carried over polymer may deposit on the top and walls of the low pressure separator and crosslink or mix with high melt index contaminants and low melt index contaminants. This may result in an increase in gel content in the final product, thereby increasing off-grade products.

[0005] Gel performance and production rates can be improved by redesigning or replacing the low-pressure separator. However, in some cases, the building structure cannot support a new or redesigned low-pressure separator. Furthermore, even with a redesigned low-pressure separator, there are capacity limitations on the booster compressor that increases the pressure of the exhaust gas from the low-pressure separator.

[0006] Therefore, there is a continuing need for improved methods of producing ethylene-based polymers that enhance production procedures by reducing gel formation in low-pressure separators and compensating for capacity limitations in booster compressors. Summary of the Invention

[0007] The embodiments of the present disclosure address this need by providing a medium-pressure separator between a high-pressure separator and a low-pressure separator. The waste gas separated from the medium-pressure separator is transferred to a primary compressor. The waste gas separated from the low-pressure separator is transferred to a booster compressor, which is arranged between the low-pressure separator and the primary compressor. The waste gas from the low-pressure separator is pressurized in the booster compressor and then transferred to the primary compressor. The treatment of these waste gases from the medium-pressure separator and the low-pressure separator can reduce gel formation in the low-pressure separator, compensate for booster compressor limitations, and increase the production rate of ethylene-based polymers. By separating the waste gas from the polymer stream in the medium-pressure separator, the medium-pressure separator can reduce gas entrainment to the low-pressure separator and eliminate the capacity limitations of the booster compressor, while improving energy consumption.

[0008] According to one or more aspects of the present disclosure, a method for producing an ethylene-based polymer 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 at a pressure greater than or equal to 100 bar, separating waste gas from the polymer stream in a medium-pressure separator at a pressure of 11 bar to 150 bar, wherein the medium-pressure separator is arranged between the high-pressure separator and a low-pressure separator, conveying the waste gas from the medium-pressure separator to a primary compressor, separating the remaining polymer stream from the medium-pressure separator into waste gas and the ethylene-based polymer in the low-pressure separator at a pressure of 0.1 bar to 10 bar, conveying the waste gas from the low-pressure separator to a booster compressor, wherein the booster compressor is arranged between the low-pressure separator and the primary compressor, pressurizing the waste gas from the low-pressure separator in the booster compressor, and conveying the pressurized waste gas from the booster compressor to the primary compressor.

[0009] Additional features and advantages of the described embodiments will be set forth in the detailed description which follows, and in part will be apparent to those skilled in the art from that detailed description or learned by practicing the described embodiments, including the following detailed description and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The following detailed description of specific embodiments of the present disclosure is best understood when read in conjunction with the accompanying drawings.

[0011] Figure 1 depicts a flow diagram for producing ethylene-based polymers according to one or more embodiments described herein;

[0012] Figure 2 schematically depicts a system for producing an ethylene-based polymer according to one or more embodiments described herein; and

[0013] Figure 3 Systems for producing ethylene-based polymers according to Comparative Examples 3 and 4 are schematically depicted.

[0014] It should be understood that the drawings are schematic in nature and do not include some components of systems for producing ethylene-based polymers that are commonly used in the art, such as, but not limited to, temperature transmitters, pressure transmitters, flow meters, level transmitters, pumps, valves, etc. It is well known that these components are within the spirit and scope of the disclosed embodiments. However, operating components (such as those described in this disclosure) may be added to the embodiments described in this disclosure.

[0015] Reference will now be made in more detail to various embodiments, some of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. DETAILED DESCRIPTION

[0016] definition

[0017] As used in this disclosure, a "reactor" refers to a vessel in which one or more chemical reactions occur between one or more reactants, optionally in the presence of one or more catalysts. For example, a reactor can include an autoclave reactor or a tubular reactor. One or more "reaction zones" can be disposed in a reactor. As used in this disclosure, a "reaction zone" refers to an area in a reactor where a particular reaction occurs.

[0018] As used in this disclosure, "separator" refers to any separation device or system of separation devices that at least partially separates one or more chemicals mixed in a process stream from each other. For example, a separator can selectively separate materials of different chemical, phase, or size from each other to form one or more chemical fractions. Examples of separators include, but are not limited to, distillation columns, flash drums, separation drums, separation tanks, centrifuges, cyclones, filtration devices, traps, scrubbers, expansion devices, membranes, solvent extraction devices, and the like. It should be understood that the separation methods described in this disclosure may not completely separate all of one chemical component from all of another chemical component. It should be understood that the separation methods described in this disclosure "at least partially" separate different chemical components from each other, and 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 components can be "separated" from a process stream to form a new process stream. Typically, a process stream can enter a separator and be divided or separated into two or more process streams with a desired composition.

[0019] As used in this disclosure, the term "polymer" may refer to a polymeric compound prepared by polymerizing monomers of the same or different types. Thus, the general term polymer encompasses the terms "homopolymer," which is typically used to refer to polymers prepared from only one type of monomer, and "copolymer," which refers to polymers prepared from two or more different monomers. As used herein, the term "interpolymer" refers to a polymer prepared by polymerizing at least two different types of monomers. Thus, the general term interpolymer includes copolymers and polymers prepared from more than two different types of monomers, such as terpolymers.

[0020] As used in this disclosure, the term "polyethylene" or "ethylene-based polymer" may refer to a polymer comprising greater than 50 mole percent of units derived from ethylene monomers. This includes polyethylene homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of ethylene-based polymers 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 low density resins and substantially linear low density resins (m-LLDPE); medium density polyethylene (MDPE); and high density polyethylene (HDPE).

[0021] As used herein, "high pressure polymer resin" is a polymer produced at a pressure higher than 1000 bar, and may include high pressure copolymers or homopolymers. This may include ethylene homopolymers (such as LDPE) or high pressure ethylene copolymers. The term "LDPE" may also be referred to as "high pressure ethylene polymer" or "highly branched polyethylene" and is defined to mean a polymer that is partially or completely homopolymerized or copolymerized in an autoclave reactor or tubular reactor at a pressure higher than 14,500 psi (100 MPa) by using a free radical initiator (such as peroxide) (see, for example, US 4,599,392, which is hereby incorporated by reference). The density of LDPE resin is typically in the range of 0.916 grams per cubic centimeter (g / cc) to 0.935 g / cc. In addition, high pressure ethylene copolymers may include "ethylene copolymers", which are high pressure polymerization products of ethylene and one or more monomers containing unsaturated carboxylic acids. In an embodiment, the comonomer containing unsaturated carboxylic acids may include unsaturated monocarboxylic acids, such as acrylic acid, methacrylic acid, or a combination thereof. 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 (e.g., ENB) or polyenes, and ethylene carbon monoxide (ECO), other vinyl monomers (other acrylates), or other terpolymers.

[0022] Similarly, as used in this disclosure, the term "high pressure polymerization procedure" may refer to a free radical polymerization procedure performed at a pressure of at least 1000 bar and optionally including an initiator or a mixture of initiators.

[0023] As used in the present disclosure, the term "radical initiator" may refer to a free radical produced by chemical and / or radiation means. The 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 monomers are added in this manner). Examples of suitable radical initiators include peroxyesters, peroxides, persulfates, perborates, percarbonates, azo compounds, etc. The specific examples of suitable radical initiators include hydrogen peroxide, tert-butyl peroctoate, tert-butyl peracetate, di-tert-butyl peroxide, lauroyl peroxide, cumene hydroperoxide, tert-butyl hydroperoxide, 2,2'-azobis[2,4-dimethyl]valeronitrile, 2-(tert-butylazo)-2-methylbutyronitrile, 2-(tert-butylazo)-2-4-dimethylvaleronitrile, azobis(isobutyronitrile), azobis(methylbutyronitrile) (AMBN), tert-amyl peroxidized 2-ethylhexanoate, and any two or more mixtures thereof.

[0024] As used in this disclosure, the term "recycle" may refer to unreacted reactants that are 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.

[0025] As used in this disclosure, the terms "feed" or "feed flow" or "feed stream" may refer to make-up and / or recycle components, such as ethylene, initiator, or solvent, that are added to a reaction zone.

[0026] Process for producing ethylene-based polymers

[0027] Embodiments of the present disclosure relate to a method for producing an ethylene-based polymer. The method may include separating a reactor effluent from a reactor into a gas stream containing unreacted monomer and a polymer stream in a high-pressure separator, separating an off-gas from the polymer stream in an intermediate-pressure separator, wherein the intermediate-pressure separator is disposed between the high-pressure separator and a low-pressure separator, passing the off-gas from the intermediate-pressure separator to a primary compressor, separating the remaining polymer stream from the intermediate-pressure separator into the off-gas and the ethylene-based polymer in the low-pressure separator, passing the off-gas from the low-pressure separator to a booster compressor, wherein 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 passing the pressurized off-gas from the booster compressor to the primary compressor.

[0028] Figure 1 Depicted is a flow chart 100 for producing ethylene-based polymers according to one or more embodiments described herein. Figure 1 The method includes steps S110, S120, S130, S140, S150, S160, and S170, wherein the steps may be performed in the order recited (i.e., S110 precedes S120, S120 precedes S130, S130 precedes S140, S140 precedes S150, S150 precedes S160, and S160 precedes S170). Other steps may be additionally included in the method described herein, and the procedures described herein should not be construed as being limited to only Figure 1 steps. Figure 2 A system for producing ethylene-based polymers according to one or more embodiments described herein is schematically depicted.

[0029] refer to Figure 2, the reactor effluent 211 can be produced using a high-pressure reactor 210. In embodiments, the reactor 210 can include an autoclave reactor, a tubular reactor, or both. The polymerization pressure can be in the range of at least 1000 bar, 1000 bar to 5000 bar, 1200 bar to 4000 bar, or 1500 bar to 3500 bar. The polymerization temperature can be in the range of about 140°C to about 330°C. All individual values ​​and subranges within the range of about 140°C to about 330°C are included herein and disclosed herein; for example, the polymerization temperature is in the range of 150°C to 320°C. The reactor effluent 211 can be cooled by a cooler or ejector from a lower pressure portion of the procedure.

[0030] In such Figure 2 In some embodiments shown in , a recycle stream 261 can be provided from a primary compressor 260 to a reactor 210 for further polymerization. The reactor 210 can be positioned downstream of the primary compressor 260. The recycle stream 261 can include ethylene. The recycle stream 261 can also include a free radical initiator.

[0031] 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 preheater (not shown) may be disposed upstream of the reactor 210. The preheater may be disposed between the secondary compressor and the reactor 210. The preheater may heat the recycle stream 261 from the primary compressor 260 to a desired temperature, such as a desired temperature in the range of 60° C. to 180° C., particularly 120° C. to 180° C., or 140° C. to 160° C. Examples of preheaters include, but are not limited to, heat exchangers.

[0032] In some embodiments, a cooler (not shown) can be provided upstream of the reactor 210. The cooler can be provided between the secondary compressor and the reactor 210. The cooler can cool the recycle stream 261 from the primary compressor 260 to a desired temperature, such as in the range of 20°C to 80°C, particularly a desired temperature of 20°C to 60°C. Examples of coolers include, but are not limited to, heat exchangers. After the reaction is completed, the reactor effluent 211 can be decompressed, cooled, or both and then sent to the high-pressure separator 220.

[0033] The reactor effluent 211 from the reactor 210 can include unreacted ethylene monomer, ethylene-based polymer, and optionally additional unreacted comonomer, chain transfer agent, or both. In one or more embodiments, the concentration of ethylene-based polymer in the reactor effluent 211 can 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.%, based on the total amount of the reactor effluent 211. %, 15 wt.% to 40 wt.%, 20 wt.% to 40 wt.%, 10 wt.% to 35 wt.%, 15 wt.% to 35 wt.%, 20 wt.% to 35 wt.%, 10 wt.% to 30 wt.%, 15 wt.% to 30 wt.%, 20 wt.% to 30 wt.%, 10 wt.% to 25 wt.%, 15 wt.% to 25 wt.% or 10 wt.% to 20 wt.%.

[0034] Still refer to Figure 2 (See also Figure 1 In step S110 in the above process, the reactor effluent 211 from the reactor 210 is separated into a gas stream 221 containing unreacted monomers and a polymer stream 222 in the high-pressure separator 220. The system for producing ethylene-based polymers may include multiple high-pressure separators 220. The gas stream 221 containing unreacted monomers is discharged from the high-pressure separator 220 as waste gas.

[0035] The unreacted monomer-containing gas stream 221 can include ethylene, a chain transfer agent and a solvent, optionally a comonomer, and small 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 wax, entrained polymer, or both. In one or more embodiments, the unreacted monomer-containing gas stream 221 can consist essentially of ethylene monomer. In one or more embodiments, the unreacted monomer-containing gas stream 221 can include from 0.1 wt.% to 50 wt.% of a comonomer, such as vinyl acetate. In some embodiments, the unreacted monomer-containing gas stream 221 can include from 1 mol.% to 10 mol.% of a chain transfer agent, including an alkane, olefin, aldehyde, ketone, alcohol, ether, ester, thiol, or phosphine.

[0036] The polymer stream 222 can include an ethylene-based polymer, such as LDPE. The polymer stream 222 can also include ethylene monomer. In one or more embodiments, the concentration of the ethylene-based polymer in the polymer stream 222 can be 50 wt.% to 99 wt.%, 60 wt.% to 99 wt.%, 70 wt.% to 99 wt.%, 50 wt.% to 95 wt.%, 60 wt.% to 95 wt.%, 70 wt.% to 95 wt.%, 50 wt.% to 90 wt.%, 60 wt.% to 90 wt.%, or 70 wt.% to 90 wt.%, based on the total amount of the polymer stream 222.

[0037] High pressure separator 220 operates at a pressure of 100 bar or greater, 150 bar or greater, 200 bar or greater, or 250 bar or greater. In embodiments, high pressure separator 200 operates at a pressure of 650 bar or less, 600 bar or less, 550 bar or less, or 500 bar or less. In embodiments, the reactor effluent 211 from the reactor 210 is separated in the high pressure separator 200 at a pressure of 100 bar to 650 bar, 150 bar to 650 bar, 200 bar to 650 bar, 250 bar to 650 bar, 100 bar to 600 bar, 150 bar to 600 bar, 200 bar to 600 bar, 250 bar to 600 bar, 100 bar to 550 bar, 150 bar to 550 bar, 200 bar to 550 bar, 250 bar to 550 bar, 100 bar to 500 bar, 150 bar to 500 bar, 200 bar to 500 bar, 250 bar to 500 bar, or any and all subranges formed from any of these endpoints.

[0038] In addition, the high pressure separator 220 can operate at a temperature of 140°C to 310°C, 145°C to 310°C, 150°C to 310°C, 140°C to 305°C, 145°C to 305°C, 150°C to 305°C, 140°C to 300°C, 145°C to 300°C, 150°C to 300°C, 140°C to 295°C, 145°C to 295°C, 150°C to 295°C, 140°C to 290°C, 145°C to 290°C, 150°C to 290°C, or any and all subranges formed by any of these endpoints.

[0039] Still refer to Figure 2 (See also Figure 1In step S120 in the process, waste gas 231 is separated from polymer stream 222 in medium-pressure separator 230. Medium-pressure separator 230 may be disposed between high-pressure separator 220 and low-pressure separator 240. Medium-pressure separator 230 may be directly connected to both high-pressure separator 220 and low-pressure separator 240. The system for producing ethylene-based polymers may include a plurality of medium-pressure separators 230.

[0040] By separating the waste gas 231 from the polymer stream 222, the medium pressure separator 230 can reduce gas carryover to the low pressure separator 240 and eliminate capacity limitations of the booster compressor 250 while improving energy consumption.

[0041] The off-gas 231 can include ethylene monomer, optionally comonomer, and 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.% wax, entrained polymer, or both. In one or more embodiments, the off-gas 231 can consist essentially of ethylene monomer.

[0042] The polymer stream 232 can include an ethylene-based polymer, such as LDPE. The polymer stream 232 can also include ethylene. In one or more embodiments, the concentration of the ethylene-based polymer in the polymer stream 232 can 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.

[0043] In one or more embodiments, 0.1 wt.% to 35 wt.%, 0.5 wt.% to 35 wt.%, 1 wt.% to 35 wt.%, 2 wt.% to 35 wt.%, 5 wt.% to 35 wt.%, 0.1 wt.% to 30 wt.%, 0.5 wt.% to 30 wt.%, 1 wt.% to 30 wt.%, 2 wt.% to 30 wt.%, 5 wt.% to 30 wt.%, 0.1 wt.% to 35 wt.%, To 25wt.%, 0.5wt.% to 25wt.%, 1wt.% to 25wt.%, 2wt.% to 25wt.%, 5wt.% to 25wt.%, 0.1wt.% to 20wt.%, 0.5wt.% to 20wt.%, 1wt.% to 20wt.%, 2wt.% to 20wt.%, 5wt.% to 20wt.% of the reactor effluent 211 is transferred to the exhaust gas 231 in the medium pressure separator 230.

[0044] Reference again Figure 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 11 bar or greater, 13 bar or greater, 15 bar or greater, or 20 bar or greater. In embodiments, the off-gas 231 is separated from the polymer stream 222 in the medium pressure separator 230 at a pressure of 150 bar or less, 130 bar or less, or 110 bar or less. In an embodiment, the medium pressure separator 230 operates at a pressure of 11 bar to 150 bar, 13 bar to 150 bar, 15 bar to 150 bar, 20 bar to 150 bar, 11 bar to 130 bar, 13 bar to 130 bar, 15 bar to 130 bar, 20 bar to 130 bar, 11 bar to 110 bar, 13 bar to 110 bar, 15 bar to 110 bar, 20 bar to 110 bar, or any and all subranges formed by any of these endpoints.

[0045] In one or more embodiments, the medium pressure separator 140 can operate at a temperature of 140°C to 310°C, 145°C to 310°C, 150°C to 310°C, 140°C to 305°C, 145°C to 305°C, 150°C to 305°C, 140°C to 300°C, 145°C to 300°C, 150°C to 300°C, 140°C to 295°C, 145°C to 295°C, 150°C to 295°C, 140°C to 290°C, 145°C to 290°C, 150°C to 290°C, or any and all subranges formed by any of these endpoints.

[0046] Still refer to Figure 2 (See also Figure 1 In step S130), the exhaust gas 231 from the medium-pressure separator 230 is transmitted to the primary compressor 260. The primary compressor 260 can be provided downstream of the medium-pressure separator 230. The primary compressor 260 can be directly connected to the medium-pressure separator.

[0047] The first stage compressor 260 may include a single or multiple compressor frames. In some embodiments, the first stage compressor 260 may be combined with a booster compressor frame.

[0048] The primary compressor 260 may compress the exhaust gas 231 from the intermediate pressure separator 230. As described below, the primary compressor 260 may further compress the pressurized exhaust gas 251 from the booster compressor 250.

[0049] Still refer to Figure 2 (See also Figure 1In step S140 in the above process, the remaining polymer stream 232 is separated into an off-gas 241 and an ethylene-based polymer stream 242 in a low-pressure separator 240. The low-pressure separator 240 may be disposed downstream of the medium-pressure separator 230. The low-pressure separator 240 may be directly connected to the medium-pressure separator 230. The system for producing ethylene-based polymers may include a plurality of low-pressure separators 240.

[0050] The off-gas 241 can include ethylene monomer, chain transfer agent 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.%, entrained polymer, or both. In one or more embodiments, the off-gas 241 can consist essentially of ethylene monomer. In one or more embodiments, the ethylene-based polymer stream 242 can consist essentially of ethylene-based polymer.

[0051] In one or more embodiments, 0.1 wt.% to 35 wt.%, 0.5 wt.% to 35 wt.%, 1 wt.% to 35 wt.%, 2 wt.% to 35 wt.%, 5 wt.% to 35 wt.%, 0.1 wt.% to 30 wt.%, 0.5 wt.% to 30 wt.%, 1 wt.% to 30 wt.%, 2 wt.% to 30 wt.%, 5 wt.% to 30 wt.%, 0.1 wt.% to 35 wt.%, To 25wt.%, 0.5wt.% to 25wt.%, 1wt.% to 25wt.%, 2wt.% to 25wt.%, 5wt.% to 25wt.%, 0.1wt.% to 20wt.%, 0.5wt.% to 20wt.%, 1wt.% to 20wt.%, 2wt.% to 20wt.%, 5wt.% to 20wt.% of the reactor effluent 211 is transferred to the exhaust gas 241 in the low pressure separator 240.

[0052] In one or more embodiments, the remaining polymer stream 232 discharged from the medium pressure separator 230 is separated in the low pressure separator 240 at a pressure greater than or equal to 0.01 bar, greater than or equal to 0.05 bar, greater than or equal to 0.1 bar, 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 less than or equal to 10 bar, less than or equal to 9 bar, or less than or equal to 8 bar. In embodiments, the low pressure separator 240 operates at a pressure of 0.01 bar to 10 bar, 0.05 bar to 10 bar, 0.1 bar to 10 bar, 1 bar to 10 bar, 0.01 bar to 9 bar, 0.05 bar to 9 bar, 0.1 bar to 9 bar, 1 bar to 9 bar, 0.01 bar to 8 bar, 0.05 bar to 8 bar, 0.1 bar to 8 bar, 1 bar to 8 bar, or any and all subranges formed from any of these endpoints.

[0053] In one or more embodiments, the remaining polymer stream 232 is separated in the low pressure separator 240 at a temperature of 130°C to 300°C, 135°C to 300°C, 140°C to 300°C, 130°C to 295°C, 135°C to 295°C, 140°C to 295°C, 130°C to 290°C, 135°C to 290°C, 140°C to 290°C, 130°C to 285°C, 135°C to 285°C, 140°C to 285°C, 130°C to 280°C, 135°C to 280°C, 140°C to 280°C, or any and all subranges derived from any of these endpoints.

[0054] Still refer to Figure 2 (See also Figure 1 In step S150), the exhaust gas 241 from the low-pressure separator 240 is transmitted to the booster compressor 250. The booster compressor 250 can be provided between the low-pressure separator 240 and the first-stage compressor 260. The booster compressor 250 can be directly connected to both the low-pressure separator 240 and the first-stage compressor 260.

[0055] The booster compressor 250 may include a single or multiple compressor frames. In some embodiments, the booster compressor 250 may be combined with a first stage compressor frame.

[0056] In one or more embodiments, the capacity of booster compressor 250 can be less than or equal to 20 wt.% of the reactor effluent 211, less than or equal to 15 wt.% of the reactor effluent 211, or less than or equal to 10 wt.% of the reactor effluent 211. In one or more embodiments, the capacity of booster compressor 220 can be greater than or equal to 0.1 wt.% of the reactor effluent 211, or greater than or equal to 1 wt.% of the reactor effluent 211. In one or more embodiments, the capacity of the booster compressor 250 can be from 0.1 wt.% to 20 wt.% of the reactor effluent 211, from 1 wt.% to 20 wt.% of the reactor effluent 211, from 0.1 wt.% to 15 wt.% of the reactor effluent 211, from 1 wt.% to 15 wt.% of the reactor effluent 211, from 0.1 wt.% to 10 wt.% of the reactor effluent 211, from 1 wt.% to 10 wt.% of the reactor effluent 211, or any and all subranges formed by any of these endpoints.

[0057] Still refer to Figure 2 (See also Figure 1 In step S160 ), the exhaust gas 241 from the low-pressure separator 240 is pressurized in the booster compressor 250 .

[0058] The booster compressor 250 can compress the exhaust gas 241 from the low-pressure separator 240. In one or more embodiments, the booster compressor 250 can increase the pressure of the exhaust gas 241 from the low-pressure separator 240 to the suction pressure of the first-stage compressor 260.

[0059] In one or more embodiments, the booster compressor 250 can increase the pressure of the offgas 241 from the low pressure separator 240 to at least 10 bar, at least 11 bar, at least 12 bar, at least 13 bar, at least 14 bar, or at least 15 bar, such as 60 bar.

[0060] Still refer to Figure 2 (See also Figure 1 In step S170 in the process, the pressurized exhaust gas 251 from the booster compressor 250 is delivered 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.

[0061] As described above, the primary compressor 260 compresses the exhaust gas 231 from the medium-pressure separator 230. The primary compressor 260 may further compress the pressurized exhaust gas 251 from the booster compressor 250.

[0062] The primary compressor 260 may deliver a recycle stream 261 to the reactor 210. The recycle stream 261 may include 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 a combination thereof. The recycle stream 261 may also include additional comonomers, chain transfer agents, and free radical initiators.

[0063] Example

[0064] 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 present disclosure or the appended claims in any way.

[0065] Embodiment 1 of the present invention and Embodiment 2 of the present invention

[0066] Figure 2 A system 200 for producing ethylene-based polymers according to Inventive Example 1 and Inventive Example 2 is schematically depicted. In Inventive Example 1 and Inventive Example 2, Aspen Plus V10 from Aspen Technology was used to simulate high pressure polymerization of ethylene. Figure 2As shown in , the reactor effluent 211 from the reactor 210 is transferred to the high-pressure separator 220. In the high-pressure separator 310, the reactor effluent 211 is separated into a gas stream 221 containing unreacted monomers and a polymer stream 222. The polymer stream 222 is transferred to the medium-pressure separator 230. In the medium-pressure separator 230, the polymer stream 222 is separated into an off-gas 231 and a polymer stream 232. In Example 1 of the present invention, the pressure of the medium-pressure separator 230 is set to 30 bar. 1500 kg / hr of the polymer stream 222 is transferred to the off-gas 231 from the medium-pressure separator 230. In Example 2 of the present invention, the pressure of the medium-pressure separator 230 is set to 100 bar. 500 kg / hr of the polymer stream 222 is transferred to the off-gas 231 from the medium-pressure separator 230. The polymer stream 232 is transferred to the low-pressure separator 240. The polymer stream 232 is separated into waste gas 241 and ethylene-based polymer (polyethylene) 242. The capacity of the booster compressor 250 is designed to be 1850 kg / hr. Tables 1 and 2 list the temperature, pressure, flow rate, and composition of each stream.

[0067] Table 1: Example 1 of the present invention

[0068] Material flow 211 221 222 231 232 241 242 Temperature (℃) 270 250 250 248 248 247 247 Pressure (bar) 2414 200 200 30 30 1.5 1.5 Flow rate (kg / hr) 30000 18955 11045 1000 10045 1038 9007 composition Ethylene 0.7 1 0.19 1 0.1 1 0 Ethylene-based polymers 0.3 0 0.81 0 0.9 0 1

[0069] Table 2: Example 2 of the present invention

[0070] Material flow 211 221 222 231 232 241 242 Temperature (℃) 270 250 250 249 249 247 247 Pressure (bar) 2500 200 200 100 100 1.51 1.51 Flow rate (kg / hr) 30000 18955 11045 500 10545 1538 9007 composition Ethylene 0.7 1 0.19 1 0.15 1 0 Ethylene-based polymers 0.3 0 0.81 0 0.85 0 1

[0071] Comparative Examples 3 and 4

[0072] Figure 3 Schematically depicted is a system 300 for producing ethylene-based polymers according to Comparative Examples 3 and 4. In Comparative Examples 3 and 4, high-pressure polymerization is simulated. The reactor effluent 311 from the reactor is sent to a high-pressure separator 310. In the high-pressure separator 310, the reactor effluent 311 is separated into a gas stream 312 containing unreacted monomers and a polymer stream 313. The polymer stream 313 is sent to a low-pressure separator 320. The polymer stream 313 is separated into a gas stream 321 containing unreacted monomers and an ethylene-based polymer (polyethylene) 322. The capacity of the booster compressor disposed downstream of the low-pressure separator 320 is designed to be 1850 kg / hr. Tables 3 and 4 list the temperature, pressure, flow rate, and composition of each stream.

[0073] Table 3: Comparative Example 3

[0074] Material flow 311 312 313 321 322 Temperature (℃) 270 250 248 247 247 Pressure (bar) 2414 200 30 1.5 1.5 Flow rate (kg / hr) 30000 20057 9943 1837 8106 composition Ethylene 0.73 1 0.19 1 0 Ethylene-based polymers 0.27 0 0.81 0 1

[0075] Table 4: Comparative Example 4

[0076] Material flow 311 312 313 321 322 Temperature (℃) 270 250 248 247 247 Pressure (bar) 2500 200 30 1.5 1.5 Flow rate (kg / hr) 30000 18955 11045 2038 9007 composition Ethylene 0.7 1 0.19 1 0 Ethylene-based polymers 0.3 0 0.81 0 1

[0077] As shown in Tables 1 to 4, the flow rates of the exhaust gas from the low-pressure separator in Inventive Examples 1 and 2 (1038 kg / hr and 1538 kg / hr) were lower than the flow rates of the exhaust gas from the low-pressure separator in Comparative Examples 3 and 4 (1837 kg / hr and 2038 kg / hr). This indicates that the medium-pressure separators in Inventive Examples 1 and 2 reduced the flow rate of the exhaust gas from the low-pressure separator by separating the exhaust gas from the medium-pressure separator.

[0078] When the capacity of the booster compressor was designed to 1850 kg / hr, Comparative Example 4 could not process the exhaust gas from the low-pressure separator. In addition, the increased flow rate of the exhaust gas from the low-pressure separator did not allow the low-pressure separator to be designed with a higher vapor velocity, which increased the possibility of polymer carryover.

[0079] Furthermore, as shown in Tables 1 to 4, the production rates of the ethylene-based polymers of Inventive Examples 1 and 2 (9007 kg / hr and 9007 kg / hr) were greater than the production rate of the ethylene-based polymer of Comparative Example 3 (8106 kg / hr). This indicates that separating the off-gas from the medium-pressure separator increases the production rate while reducing the likelihood of gelation in the low-pressure separator. Although the production rate of the ethylene-based polymer of Comparative Example 4 is the same as that of Inventive Examples 1 and 2, as described above, Comparative Example 4 cannot process the off-gas from the low-pressure separator when the booster compressor capacity is designed to 1850 kg / hr.

[0080] A first aspect of the present disclosure may relate to a method for producing an ethylene-based polymer, the method comprising: separating a reactor effluent from a reactor into a gas stream containing unreacted monomers and a polymer stream in a high-pressure separator at a pressure greater than or equal to 100 bar, separating waste gas from the polymer stream in a medium-pressure separator at a pressure of 11 bar to 150 bar, wherein the medium-pressure separator is arranged between the high-pressure separator and a low-pressure separator, conveying the waste gas from the medium-pressure separator to a primary compressor, separating the remaining polymer stream from the medium-pressure separator into waste gas and the ethylene-based polymer in the low-pressure separator at a pressure of 0.1 bar to 10 bar, conveying the waste gas from the low-pressure separator to a booster compressor, wherein the booster compressor is arranged between the low-pressure separator and the primary compressor, pressurizing the waste gas from the low-pressure separator in the booster compressor, and conveying the pressurized waste gas from the booster compressor to the primary compressor.

[0081] A second aspect of the present disclosure may include the first aspect, wherein 0.1 wt.% to 35 wt.% of the reactor effluent is transferred to the off-gas in the medium pressure separator.

[0082] A third aspect of the present disclosure may include any of the first or second aspects, wherein 0.1 wt.% to 20 wt.% of the reactor effluent is transferred to the off-gas in the medium pressure separator.

[0083] A fourth aspect of the present disclosure may include any one of the first to third aspects, wherein 0.1 wt.% to 35 wt.% of the reactor effluent from the reactor is transferred to the off-gas in the low-pressure separator.

[0084] A fifth aspect of the present disclosure may include any one of the first to fourth aspects, wherein 0.1 wt.% to 20 wt.% of the reactor effluent from the reactor is transferred to the off-gas in the low-pressure separator.

[0085] A sixth aspect of the present disclosure may include any one of the first to fifth aspects, wherein the high-pressure separator operates at a temperature of 140°C to 290°C.

[0086] A seventh aspect of the present disclosure may include any one of the first to sixth aspects, wherein the medium pressure separator operates at a temperature of 130°C to 290°C.

[0087] An eighth aspect of the present disclosure may include any one of the first to seventh aspects, wherein the low-pressure separator operates at a temperature of 130°C to 280°C.

[0088] A ninth aspect of the present disclosure may include any one of the first to eighth aspects, wherein the capacity of the booster compressor is less than or equal to 20 wt.% of the reactor effluent.

[0089] A tenth aspect of the present disclosure may include any one of the first to ninth aspects, wherein the capacity of the booster compressor is less than or equal to 10 wt.% of the reactor effluent.

[0090] An eleventh aspect of the present disclosure may include any one of the first to tenth aspects, wherein the booster compressor increases the pressure of the exhaust gas from the low-pressure separator to a suction pressure of the primary compressor.

[0091] A twelfth aspect of the present disclosure may include any one of the first to eleventh aspects, wherein the booster compressor increases the pressure of the exhaust gas from the low-pressure separator by at least 10 bar.

[0092] A thirteenth aspect of the present disclosure may include any one of the first to twelfth aspects, wherein the ethylene-based polymer includes low-density polyethylene (LDPE).

[0093] A fourteenth aspect of the present disclosure may include any one of the first to thirteenth aspects, wherein the ethylene-based polymer includes a high pressure ethylene copolymer.

[0094] A fifteenth aspect of the present disclosure may relate to an ethylene-based polymer produced by the method according to any one of the first to fourteenth aspects.

[0095] It should be noted that one or more of the following claims utilize the term "wherein" as a transition phrase. For purposes of defining the present technology, it should be noted that this term is introduced in the claims as an open transition phrase that is used to introduce a recitation of a list of features of a structure and should be interpreted in a manner similar to the more commonly used open preamble term "comprising." For purposes of defining the present technology, the transition phrase "consisting of may be introduced in the claims as a closed preamble term that limits the scope of the claim to the enumerated components or steps and any naturally occurring impurities. For purposes of defining the present technology, the transition phrase "consisting essentially of may be introduced in the claims to limit the scope of one or more claims to the stated elements, components, materials, or method steps and any non-stated elements, components, materials, or method steps that do not materially affect the novel characteristics of the claimed subject matter. The transition phrases "consisting of" and "consisting essentially of" may be construed as subsets of open transition phrases, such as "comprising" and "including," such that any use of an open phrase to introduce a statement of a list of elements, components, materials, or steps should be construed to also disclose statements of that list of elements, components, materials, or steps using the closed terms "consisting of" and "consisting essentially of." For example, a statement that a composition "comprising" component A, component B, and component C should be construed to also disclose a composition "consisting of component A, component B, and component C" as well as a composition "consisting essentially of component A, component B, and component C." Any quantitative value expressed in this application may be considered to include open embodiments that conform to the transition phrases "comprising" or "comprising" as well as closed or partially closed embodiments that conform to the transition phrases "consisting of" and "consisting essentially of."

[0096] As used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly indicates otherwise. The verb "to include" and its cognate 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 that are not explicitly referenced.

[0097] In addition, when providing amount, concentration or other value or parameter as range, preferred range or higher preferred value and lower preferred value list, it should be understood that specifically disclose all ranges formed by any upper range limit or preferred value and any lower range limit or preferred value, no matter whether separately disclosed range.When numerical range is enumerated herein, unless otherwise stated, otherwise the range is intended to include its endpoint value and all integers and fractions within the range.When limiting the range, it is not intended that the scope of the present invention is limited to the specific value listed.When indicating that a certain component exists in the range from 0, the component is an optional ingredient (that is, may exist or may not exist).When present, the optional component can be at least 0.1 weight % of a composition or copolymer.

[0098] When the terms "known to those skilled in the art," "conventional," or synonymous words or phrases are used herein to describe materials, methods, or machines, these terms mean that the materials, methods, and machines that were conventional at the time this application was filed are encompassed by the present embodiments.

[0099] It will be understood that any two quantitative values ​​assigned to a characteristic may constitute a range for that characteristic, and that all combinations of ranges formed by all said quantitative values ​​for a given characteristic are contemplated in the present disclosure. The subject matter of the present disclosure has been described in detail and by reference to specific embodiments. It will 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 for that particular embodiment or any other embodiment. Further, it will be apparent to those skilled in the art that various modifications and changes may be made to the described embodiments without departing from the spirit and scope of the claimed subject matter.

Claims

1. A method for producing an ethylene-based polymer, the method comprising: separating the reactor effluent from the reactor in a high-pressure separator at a pressure greater than or equal to 100 bar into a gas stream containing unreacted monomer and a polymer stream; separating off-gas from the polymer stream in a medium-pressure separator at a pressure of 11 to 150 bar, wherein the medium-pressure separator is disposed between the high-pressure separator and the low-pressure separator; passing the exhaust gas from the medium-pressure separator to a first-stage compressor; separating the remaining polymer stream from the medium-pressure separator into an off-gas and the ethylene-based polymer in the low-pressure separator at a pressure of 0.1 bar to 10 bar; passing the exhaust gas from the low-pressure separator to a booster compressor; wherein the booster compressor is arranged between the low-pressure separator and the first-stage compressor; pressurizing the exhaust gas from the low-pressure separator in the booster compressor; as well as The pressurized exhaust gas from the booster compressor is delivered to the primary compressor.

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

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

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

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

6. A process according to any preceding claim, wherein the high pressure separator operates at a temperature of 140 degrees Celsius (°C) to 290°C.

7. A process according to any preceding claim, wherein the medium pressure separator is operated at a temperature of from 130°C to 290°C.

8. A process according to any preceding claim, wherein the low pressure separator is operated at a temperature of from 130°C to 280°C.

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

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

11. A method according to any preceding claim, wherein the booster compressor increases the pressure of the exhaust gas from the low pressure separator to the suction pressure of the first stage compressor.

12. A method according to any preceding claim, wherein the booster compressor increases the pressure of the off-gas from the low-pressure separator by at least 10 bar.

13. The method of any preceding claim, wherein the ethylene-based polymer comprises low density polyethylene (LDPE).

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

15. An ethylene-based polymer produced according to any preceding claim.

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