In-line axial cyclone separators and methods for particle separation

Abstract

Embodiments of an in-line axial cyclone separator comprise: a cylindrical casing having an inlet and outlet disposed at opposite ends; a particle strainer coaxially disposed within the cylindrical casing proximate the outlet; an impeller coaxially disposed within the cylindrical casing and upstream of the strainer; a primary flow path formed in the spacing between the cylindrical casing and the strainer and the impeller; and a particle collection zone disposed downstream of the impeller and being defined by a region within the primary flow path between the strainer and the cylindrical casing.

Description

IN-LINE AXIAL CYCLONE SEPARATORS AND METHODS FOR PARTICLE SEPARATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 665,934 filed June 28, 2024, the contents of which are incorporated in their entirety herein.TECHNICAL FIELD

[0002] Embodiments described herein generally relate to in-line axial cyclone separators, and processes for producing polymer which include in-line axial cyclone separators for removing particles from a high pressure monomer feed.BACKGROUND

[0003] Polymer resin plants utilize rotating equipment that has the potential to release metal particles downstream due to wear. With elevated quality targets established, it is crucial to identify mitigation and control methods to remove metal -containing contaminants from the base resin. One approach is to utilize a conventional in-line strainer to catch solid particles (e.g., metal and wax) from a high pressure monomer feed before reaching the polymerization reactor(s); however, the separation / capture efficiency especially for particle sizes below 75 pm is insufficient. Accordingly, there is a need for improved systems and methods of reducing separation / capture efficiency for smaller particles below 75 pm.SUMMARY

[0004] Embodiments of the present disclosure are directed to an in-line axial cyclone separator that meets this need by including an impeller installed upstream of the strainer as well as improved strainer configurations. In these impeller embodiments, the rotational fluid movement around the longitudinal axis is formed and more solid particles will be pushed toward the inner wall of the cylindrical casing (e.g., pipe internal wall) by the centrifugal force due to their higher density. While the high pressure upgraded monomer (e.g., ethylene) feed is exiting through perforated holes in the strainer, certain amount of particles are retained in the pocket area outside of the strainer and can be removed during turnaround or shutdown.

[0005] In one or more embodiments, the in-line axial cyclone separator comprises: a cylindrical casing having an inlet and outlet disposed at opposite ends; a particle strainer coaxially disposed within the cylindrical casing proximate the outlet; an impeller coaxially disposed within the cylindrical casing and upstream of the strainer; a primary flow path formed in the spacing between the cylindrical casing and the strainer and the impeller; and a particle collection zone disposed downstream of the impeller and being defined by a region within the primary flow path between the strainer and the cylindrical casing.

[0006] These and further embodiments are described in more detail in the following Detailed Description in conjunction with the appended drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

[0008] FIG. 1 is a schematic illustration of the present process for producing polyethylene utilizing an in-line axial cyclone separator according to one or more embodiments of the present disclosure;

[0009] FIG. 2A is a schematic illustration of a separator comprising the conventional inline strainer.

[0010] FIG. 2B illustrates the fluid motion around the strainer of FIG. 2A.

[0011] FIG. 2C illustrates the contour of particle concentration (particle size of 25 pm) around the strainer of FIG. 2 A.

[0012] FIG. 3A is a schematic illustration of an in-line axial cyclone separator having an impeller and conical closed-nose strainer according to one or more embodiments of the present disclosure;

[0013] FIG. 3B illustrates an aspect of the subject matter in accordance with one embodiment.

[0014] FIG. 3C illustrates the fluid motion around the in-line axial cyclone separator of FIG. 3 A according to one or more embodiments of the present disclosure;

[0015] FIG. 4A is a schematic illustration of an in-line axial cyclone separator having an impeller and a cylindrical open-nose strainer according to one or more embodiments of the present disclosure;

[0016] FIG. 4B illustrates the fluid motion around the in-line axial cyclone separator of FIG. 4A according to one or more embodiments of the present disclosure;

[0017] FIG. 4C illustrates the contour of particle concentration (particle size of 25 pm) around the in-line axial cyclone separator of FIG. 4A according to one or more embodiments of the present disclosure;

[0018] FIG. 5A is a schematic illustration of an in-line axial cyclone separator having an impeller and a cylindrical open-nose strainer with a diverted flow path according to one or more embodiments of the present disclosure;

[0019] FIG. 5B illustrates the fluid motion around the in-line axial cyclone separator of FIG. 5A according to one or more embodiments of the present disclosure;

[0020] FIG. 5C illustrates the contour of particle concentration (particle size of 25 pm) around the in-line axial cyclone separator of FIG. 5 A according to one or more embodiments of the present disclosure; and

[0021] FIG. 6 is a graphical illustration comparing the separation efficiency at various particle sizes for a separator comprising the convention strainer of FIG. 2A versus the in-line axial cyclone separators depicted in FIG. 3A, FIG. 4A, and FIG. 5A.DETAILED DESCRIPTION

[0022] Specific embodiments of the present application will now be described. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the claimed subject matter to those skilled in the art.

[0023] The term “polymer” refers to a polymeric compound prepared by polymerizing monomers, whether of a same or a different type. The generic term polymer thus embraces the term “homopolymer,” which usually refers to a polymer prepared from only one type of monomer as well as “copolymer,” which refers to a polymer prepared from two or more different monomers. The term “interpolymer,” refers to a polymer prepared by the polymerization of at least two different types of monomers. The generic term interpolymerthus includes a copolymer or polymer prepared from more than two different types of monomers, such as terpolymers.

[0024] "Polyethylene” or “ethylene-based polymer” shall mean polymers comprising greater than 50% by mole of units derived from ethylene monomer. This includes ethylenebased homopolymers or copolymers (meaning units derived from two or more comonomers). Common forms of ethylene-based polymers known in the art include, but are not limited to, 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).

[0025] The term “composition,” as used herein, refers to a mixture of materials that comprises the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0026] The term “supercritical fluid” as used herein, refers to a substance at a temperature and pressure above its critical point, where distinct liquid and gas phases do not exist, but below the pressure required to compress it into a solid.

[0027] The terms “comprising,” “including,” “having,” and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, “consisting essentially of’ excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term “consisting of’ excludes any component, step or procedure not specifically delineated or listed.

[0028] Embodiments are directed an in-line axial cyclone separator including a cylindrical casing having an inlet and outlet disposed at opposite ends, a particle strainer coaxially disposed within the cylindrical casing proximate the outlet, an impeller coaxially disposed within the cylindrical casing and upstream of the strainer, a primary flow path formed in the spacing between the cylindrical casing and the strainer and the impeller, and a particlecollection zone disposed downstream of the impeller and being defined by a region within the primary flow path between the strainer and the cylindrical casing.

[0029] Further embodiments are directed to a process for producing polyethylene using the in-line axial cyclone separator. The process includes: introducing a monomer feed stream includes ethylene monomer and optionally comonomer to a compressor system to generate high pressure monomer feed having a pressure of at least 1,000 bar, or at least 2000 bar, introducing the high pressure monomer feed to the in-line axial cyclone separator, where the in-line axial cyclone separator adjusts the flow rate of the high pressure monomer feed via the impeller, and removes particles from the high pressure monomer feed via the strainer to produce an upgraded high pressure monomer feed, collecting the separated particles in the particle collection zone, and introducing the upgraded high pressure monomer feed to a polymerization reactor to generate the polyethylene.

[0030] Embodiments of the present process for producing polyethylene will now be described. Referring to the system 10 of FIG. 1, monomer feed stream 5 is fed to a compressor system 20 to produce a high pressure monomer feed 22 having a pressure of at least 1000 bar. While not shown, it is contemplated in some embodiments that the monomer feed stream 5 may be pressurized prior to delivery to the compressor system 20. For example, the monomer feed stream 5 may be delivered to the compressor system 20 at a pressure of less than 100 bar, or less than 50 bar, or less than 20 bar. All pressure measurements in the present disclosure are absolute pressure values.

[0031] In one or more embodiments, the monomer feed stream 5 comprises ethylene and may additionally comprise one or more comonomers in combination with the ethylene monomer. Suitable comonomers may include, but are not limited to, ethylenically unsaturated monomers and especially C3-20 alpha-olefins, diolefins, polyenes, as well as polar comonomers. These polar comonomers may include but are not limited to those with carboxylic acid, acrylate, or acetate functionality, for example, methacrylic acid, acrylic acid, vinyl acetate, methyl acrylate, isobutyl acrylate, n -butyl acrylate, glycidyl methacrylate, and monoethyl ester of maleic acid.

[0032] Referring again to FIG. 1, the compressor system 20 may comprise one or more compressors in parallel or in series. As shown in FIG. 1, the compressor system 20 may comprise a primary compressor 24 and a secondary compressor 26 downstream of the primarycompressor 24. The primary compressor 24 may pressurize the monomer feed stream 5 such that the partially pressurized feed stream 28 to the secondary compressor 26 has a pressure of at least 200 bar. In one or more embodiments, the primary compressor 24 may compress the monomer feed stream 5 to a pressure of 200 to 1000 bar, or from 300 to 900 bar. To achieve this compression, the primary compressor 24 may include one or multiple compression stages.

[0033] The secondary compressor 26, which may also be called a hyper compressor, pressurizes the partially pressurized feed stream 28 to a pressure of at least 1000 bar, or at least 2000 bar, or at least 2500 bar, or at least 3000 bar. Like the primary compressor 24, the secondary compressor 26 may include one or multiple compression stages. In one or more embodiments, the secondary compressor 26 may comprise a plunger reciprocating compressor, and can consist of single or multiple compressor stage(s).

[0034] In various embodiments, the high pressure monomer feed 22 exiting the compressor system 20 comprises a pressure of at least 1000 bar, or at least 2000 bar, or at least 2500 bar, or at least 3000 bar. Further, in various embodiments, the high pressure monomer feed 22 exiting the compressor system 20 may alternatively be defined as having a pressure such that the high pressure monomer feed 22 is a supercritical fluid.

[0035] Referring again to FIG. 1, the high pressure monomer feed 22 exiting the compressor system 20 is passed to a separator 30. The high pressure monomer feed 22 may be delivered to the separator 30 at a flow rate ranging from a minimum of 0.1, 0.5, 1.0, 5.0, 10.0, 20.0, 25.0, 30.0, 40.0, or 50.0 m3 / hr to a maximum of 1.0, 5.0, 10.0, 20.0, 25.0, 30.0, 40.0, 50.0, 60, or 100 m3 / hr.

[0036] The separator 30 separates solid particles and droplets from the high pressure monomer feed 22 to generate an upgraded high pressure monomer feed 32 wherein the solid particles are separated by a strainer of the separator 30, and specifically the in-line axial cyclone separator described in detail below.

[0037] In accordance with one or more embodiments, a plurality of separators 30 are provided. The plurality of separators 30 may be provided in series or in parallel in accordance with variance embodiments. In various embodiments, the system 10 may include 1, 2, 3, 4, 5, or more than 5 separators 30. It will be appreciated that a plurality of separators 30 in series allows for progressive purification of the upgraded high pressure monomer feed 32through serial removal of the solid particles and droplets. Similarly, it will be appreciated that a plurality of in-line axial cyclone separators 30 in parallel allows for an increased rate of generation of the upgraded high pressure monomer feed 32 by leveraging multiple separators 30 to remove the solid particles and droplets contemporaneously.

[0038] In one or more embodiments, the high pressure monomer feed 22 is introduced into the separator 30 in a pulsated manner. Specifically, as will be appreciated by one skilled in the art, the high pressure monomer feed 22 exiting the compressor system 20 may not be continuous. For example, a reciprocating compressor may generate a flow with a pulsed or non-steady flow rate. As such, the separator 30 may be configured to handle the pulsated introduction of the high pressure monomer feed 22. It will be appreciated that the volume of the separator 30 relative to the inlet flow pulsation may be used to tune the impact of the pulsed flow by considering the frequency of the compressor in view of the residence time of the high pressure monomer feed 22 within the separator 30.

[0039] Referring again to FIG. 1, the upgraded high pressure monomer feed 32 exiting the separator 30 is passed to a polymerization reactor 40 to generate the polyethylene from the upgraded high pressure monomer feed 32. While any high pressure polymerization reactor may be used in accordance with the present disclosure, examples of specific reactors and reactor types are provided to fully describe the process for producing polyethylene, but the same should not be considered as limiting. In one or more embodiments, the polymerization reactor 40 may be a free radical polymerization reactor. Further, in one or more embodiments a polymerization initiator 44 may be added to the polymerization reactor 40.

[0040] The polymerization reactor 40 may include one or more autoclave reactors or tubular reactors. The pressure in each autoclave or tubular reactor zone may be from 1000 to 4000 bar, or from 1500 to 3600 bar, or from 2000 to 3200 Bar. The polymerization temperature in each tubular reactor zone may be from 100 to 400 °C, or from 150 to 360 °C, or from 180 to 340° C. The polymerization temperature in each autoclave reactor zone may be from 150 to 300, more typically from 165 to 290, and even more typically from 180 to 280° C.

[0041] Referring to FIG. 1, a reactor effluent 42 from the polymerization reactor 40 comprises polyethylene generated in the polymerization reactor 40 as well as unreacted components of the upgraded high pressure monomer feed 32. It will be appreciated thatif polymerization initiator 44 is provided to the polymerization reactor 40 the same may also be present in the reactor effluent 42.

[0042] Referring to FIG. 2A, a separator 230 comprising an in-line conventional particle strainer 234 is depicted. The separator 230 includes a cylindrical casing 232 having an inlet and outlet disposed at opposite ends, and a particle strainer 234 coaxially disposed within the cylindrical casing 232 proximate the outlet. Furthermore, the separator 230 comprises a primary flow path 236 formed in the spacing between the cylindrical casing 232 and the particle strainer 234, and a particle collection zone 238 being defined by a region within the primary flow path 236 between the particle strainer 234 and the cylindrical casing 232. As shown, the particle collection zone 238 is at least partially downstream of the particle strainer 234.

[0043] Various diameters are contemplated for cylindrical casing based on the desired flow area. For example, the diameter may range from a minimum of 0.1, 0.5, 1.0, 2.0, 3.0, or 4.0 inches to a maximum of 1.0, 2.0, 3.0, 4.0, or 5.0 inches.

[0044] Various shapes of particle strainer 234 are considered suitable. For example, the particle strainer 234 may include a cone shape or a cylindrical shape. Furthermore, the nose of the particle strainer may be open and closed.

[0045] Moreover, the particle strainer 234 have a plurality of surface openings. The number of surface openings may vary as well as the spacing between openings may vary. In one embodiment, the surface openings may occupy from 5 to 25% of the total surface area of the particle strainer 234. In another embodiment, the surface openings may have a diameter of 1 to 5 mm.

[0046] As shown in FIG. 2B, Computational Fluid Dynamics (CFD) was used to simulate the fluid flow around the separator 230. The flow pathlines move parallel in the upstream of the particle strainer 234 and make sharp turns when entering the perforations of the particle strainer 234. The flow accelerates when exiting due to a smaller outflow area. Since particle strainer 234 has a closed front end, the incoming flow moves towards the wall of the cylindrical casing 232. This leads to high flow velocity between the walls of particle strainer 234 and the cylindrical casing 232, and therefore reduces its separation efficiency.

[0047] Referring to the particle concentration contour curve of FIG. 2C, the trajectory of particles (size of 25 pm is used as an example) in the separator 230 is shown. Due to its smallStokes number, e.g., a Stokes number less than 1, which is associated with small particle diameter, particles tend to follow the primary flow path 236 and most of the particles exit the particle strainer 234 without being captured in the particle collection zone 238. As a result, the particle strainer 234 is less effective for separation of smaller particles, e.g., particles having a size less than 75 pm.

[0048] In light of the need for greater separation efficiency, the present embodiments utilize and upstream impeller as well as further strainer designs to meet this need. Referring to FIG.3 A, the in-line axial cyclone separator 330 includes a closed-nose strainer, in this case, a cone shape similar to the particle strainer 234 detailed above. The in-line axial cyclone separator 330 includes an impeller 340 arranged upstream of the particle strainer 334. The impeller 340 imparts rotational movement for the purpose of separating the heavy solid particles from a liquid mixture.

[0049] Various parameters for the impeller 340 are considered suitable. In one embodiment, the impeller is an axial impeller. The axial impeller may include a having a plurality of blades, The ratio of axial flow to tangential flow is controlled by the pitch of the impeller blade. Pitch ranges from 20 to 80 degrees wherein the blade shape may vary and the blade length may vary. Moreover, the impeller may include various diameters, while being constrained by the diameter of the cylindrical case i.e., pipe. Furthermore, it is contemplated that the impeller 340 is disclosed at various distances upstream of the strainer 334.

[0050] To further increase separation efficiency for smaller particles (e.g., less than 75 pm), the in-line axial cyclone separator 430 may include an open-nose cylindrical particle strainer 434 downstream of the impeller 340 as shown in FIG. 4A. Without being limited by theory, the open-nose cylindrical strainer 434 and its associated larger particle collection zone 238 to retain and remove solid particles.

[0051] Various parameters of the open-nose cylindrical strainer 434 are considered suitable. For example, open-nose cylindrical strainer 434 may have an outer diameter of 60 to 90% of the diameter of the cylindrical casing 232 i.e., pipe. Moreover, the open-nose cylindrical strainer 434 may have an inner diameter of 60 to 90% of the outer diameter open-nose cylindrical strainer 434. Based on these diameters, the particle collection zone 238 may have an axial space between the open-nose cylindrical strainer 434 and the cylindrical casing 232.

[0052] As shown FIG. 4B, the flow field around the open-nose cylindrical particle strainer 434 is shown. The particle-free fluid exits the particle strainer 434 through its open nose.

[0053] Referring to the particle concentration contour curve of FIG. 4C, the trajectory of particles (size of 25 pm is used as an example) is shown. As stated above, the open -nose cylindrical particle strainer 434 yields a bigger particle collection zone 238 for solid particle accumulation to effectively remove particles and prevent their resuspension.

[0054] To further the separation performance, the in-line axial cyclone separator 530, which also include an open-nose cylindrical particle strainer 534, also include a flow diverter 539 extending from an outer surface of the particle strainer 534. This flow diverter 539 creates a secondary diverted flow path 536. Without being limited by theory, the flow diverter 539 results in a circuitous flow path that enables more solid particles to be collected in the particle collection zone 238. This secondary diverted flow path 536 is illustrated in FIGS. 5B and 5C.

[0055] Various design parameters are considered suitable for the flow diverter 539. For example, the flow diverter 539 (also called “jacket”) may have an outer diameter of 60 to 90% of the diameter of the cylindrical casing 232 i.e., pipe. The diameter of the open-nose cylindrical particle strainer 534 may have a may have an outer diameter of 60 to 70% of the diameter of the cylindrical casing 232 i.e., pipe. Based on these diameters, the particle collection zone 238 may have an axial space between the open-nose cylindrical strainer 534 and the cylindrical casing 232. Moreover, the open-nose cylindrical strainer 534 have a plurality of surface openings. The number of surface openings may vary as well as the spacing between openings may vary. In one embodiment, the surface openings may occupy from 5 to 25% of the total surface area of the open-nose cylindrical strainer 534.

[0056] Referring again to the process of FIG. 1, the in-line axial separators of FIGS 3 A, 4 A, and 5A may separate solid particles from high pressure monomer feed 22 having a density ratio of particle / liquid larger than 5.

[0057] In accordance with one or more embodiments the solid particles may be copper, bronze, steel, iron, zinc, aluminum, or any other metallic species. In one or more specific embodiments as shown in FIG. 1, the solid particles may be filings or other wear products from one or more unit operations processing the components of the monomer feed stream prior to introduction to the in-line axial cyclone separator 30. For example, the solid particlesmay comprises copper or bronze particles worn away from components of the compressor system 20.

[0058] In one or more embodiments, the solid particles comprise a longest dimension of less than 1,000 microns. In various further embodiments, the solid particles comprise a longest dimension of less than 500 microns, less than 200 microns, less than 150 microns, or less than 100 microns. It will be appreciated that smaller particle sizes present unique challenges in their removal or separation from a stream, which are exacerbated by the high pressures of the current system. However, it will also be appreciated that the processes as discussed in the present disclosure address such challenges in a unique and novel way through implementation of the in-line axial cyclone separator 30 between the compressor system 20 and the polymerization reactor 40.

[0059] In accordance with one or more embodiments, the droplets removed from the high pressure monomer feed 22 may include waxes. Typically, the waxes are low molecular weight polyethylene that form as droplets or small particles in an ethylene stream. Without being bound by theory, the waxes may assist in securing solid particles in the particle collection zone 238.

[0060] Polymers

[0061] In one or more embodiments, the polymerization reactor 40 generates low density polyethylene (LDPE); however, it is also contemplated as suitable for other ethylene -based polymers, for example, ethylene acid copolymers.

[0062] In one embodiment, the LDPE has a density from 0.900 to 0.950, more typically from 0.916 to 0.932 and even more typically from 0.918 to 0.926, grams per cubic centimeter (g / cc or g / cm3) prepared according to ASTM D4703 and measured according to ASTM D792, Method B, within one hour of sample pressing. In one embodiment, the LDPE has a melt index (L) from 0.1 to 40 g / 10 mins, or from 0.2 to 25 g / 10 mins measured in accordance to ASTM D-1238 (method B) at 190 °C and at 2.16 kg load. In some embodiments, the LDPE may have a lower I2 from 0.1 to 10 g / 10 mins, or from 0.1 to 1 g / 10 mins. Alternatively, the LDPE may have a higher I2 from 5 to 40 g / 10 mins, or from 10 to 25 g / 10 mins, or from 15 to 25 g / 10 mins.

[0063] Applications

[0064] The polyethylene formed in accordance with the presently disclosed processes may be employed in a variety of conventional thermoplastic fabrication procedures to produce useful articles, including, for example, films; molded articles, such as blow molded, injection molded, or rotomolded articles; foams; wire and cable, fibers, extrusion coatings, and woven or non-woven fabrics.TEST METHODS

[0065] Melt index (MI)

[0066] Melt Index (I2) was measured in accordance to ASTM D-1238 (method B) at 190 °C and 2.16 kg load.

[0067] Density

[0068] Density measurements were performed according to ASTM D4703.

[0069] Discrete Particulate Model (DPM) using the Computational Fluid Dynamics (CFD) software

[0070] The CFD software utilized was ANSYS Fluent 19.1 and the simulations utilized a steady state, k-epsilon model for fluid flow. In the DPM, the continuous phase is solved using Navier-Stokes equations. At the same time, the discrete phase is simulated by tracking a large number of particles passing through the calculated continuous flow field. The discrete phase can exchange momentum, mass, and energy with the continuous phase. This method can be made much simpler by ignoring the interaction of particles with each other. This DPM is suitable for fluid flow with low solid concentration (<10% by mass) as in the present embodiments. As shown below in Table 3, the separation efficiency at various particles was computed via the ANSYS software.EXAMPLES

[0071] The following Examples are offered by way of illustration and are presented in a manner such that one skilled in the art should recognize are not meant to be limiting to the present disclosure as a whole or to the appended claims.

[0072] Laboratory Test

[0073] Particle separations were conducted using a laboratory set-up. The inlet feed was an aqueous sample having 0.1 wt.% of copper particles, which were obtained from prior plant runs. Referring to Table 1 below, the feed was delivered at initial starting flow rate of 0.7m3 / hr, denoted in the table as IX. For flow rates such as 1.25X, the flow rate is 0.875 m3 / hr (=0.7 m3 / hr X 1.25). As shown in Table 1, additional flow rates were tested for the other laboratory runs. The starting flow area (IX) within the pipe was 0.785 inch2, the starting angular velocity (IX) was 32 rad / sec, the starting centrifugal force (IX) was 128 N, but various additional flow areas, angular velocities, and centrifugal forces were tested. The diameter of the strainers were 0.4 inches and 0.8 inch in diameter, and the pipe diameter was 0.5 inches and 1.0 inches respectively.

[0074] CFD Simulations

[0075] Additionally, CFD simulations were conducted using the parameters provided in Table 1. The feed concentration, initial flow rate, initial angular velocity, and the initial centrifugal force correspond to the values of the laboratory test.

[0076] Table 1ND=not determined* The 0.031% value is the averaged value of the outlet concentration for Inventive Example 1 (0.019% and0.042%) in Table 2

[0077] Table 2

[0078] Table 3

[0079] Referring to FIG. 6 and Table 3, the separation efficiency of the Comparative Example is less than 50% for particle sizes of 25 pm, whereas the separation efficiency is greater than 50% for particle sizes of 25 pm. Moreover, for the open-nose Inventive Examples 2 and 3, the separation efficiency is greater than 50% for particle sizes of 15 pm.

[0080] It will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims. More specifically, although some aspects of the present disclosure may be identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

Claims

CLAIMS1. An in-line axial cyclone separator comprising: a cylindrical casing having an inlet and outlet disposed at opposite ends; a particle strainer coaxially disposed within the cylindrical casing proximate the outlet; an impeller coaxially disposed within the cylindrical casing and upstream of the strainer; a primary flow path formed in the spacing between the cylindrical casing and the strainer and the impeller; and a particle collection zone disposed downstream of the impeller and being defined by a region within the primary flow path between the strainer and the cylindrical casing.

2. The in-line axial cyclone separator of claim 1, wherein the strainer is an open -nose strainer.

3. The in-line axial cyclone separator of claim 1, wherein the strainer is a closed-nose strainer.

4. The in-line axial cyclone separator of any one of claims 1 to 3, wherein the strainer comprises a cone shape.

5. The in-line axial cyclone separator of any one of claims 1 to 4, wherein the strainer comprises a cylindrical shape.

6. The in-line axial cyclone separator of any one of claims 1 to 5, wherein the particle collection zone is at least partially downstream of the strainer.

7. The in-line axial cyclone separator of any one of claims 1 to 6, wherein the strainer comprises a flow diverter extending from an outer surface of the strainer and configured to define a secondary flow path.

8. A method of separating particles in a liquid mixture using the in-line axial cyclone separator of any one of claims 1 to 6.

9. A polymerization system comprising: at least one compressor; the in-line axial cyclone separator of any one of claims 1 to 6 disposed downstream of the compressor; and a polymerization reactor disposed downstream of the in-line axial cyclone separator.

10. A process for producing polyethylene comprising: introducing a monomer feed stream comprising ethylene monomer and optionally comonomer to a compressor system to generate high pressure monomer feed having a pressure of at least 1,000 bar, or at least 2000 bar; introducing the high pressure monomer feed to the in-line axial cyclone separator of any any one of claims 1 to 7, wherein the in-line axial cyclone separator adjusts the flow rate of the high pressure monomer feed via the impeller, and removes particles from the high pressure monomer feed via the strainer to produce an upgraded high pressure monomer feed; collecting the separated particles in the particle collection zone; and introducing the upgraded high pressure monomer feed to a polymerization reactor to generate the polyethylene.

11. The process of claim 10, wherein the monomer feed stream is a supercritical fluid.

12. The process of claim 10 or 11, wherein the particles comprises metallic particles, waxes, or combinations thereof.

13. The process of any one of claims 10 to 12, wherein the polyethylene is low density polyethylene (LDPE).

14. The process of any one of claims 10 to 13, wherein a density ratio of particle to liquid in the high pressure monomer feed is greater than 5.

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