Method for manufacturing polyolefin
Patent Information
- Application Number
- PCT/KR2025/019734
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-14
- Filing Date
- 2025-11-26
- Publication Date
- 2026-09-17
Smart Images
Figure KR2025019734_17092026_PF_FP_ABST
Abstract
Description
Method for manufacturing polyolefin
[0001] Cross-citation with related applications
[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0033166 filed March 14, 2025, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.
[0003] Technology field
[0004] The present invention relates to a method for manufacturing polyolefins, and more specifically, to a method for manufacturing polyolefins that can prevent fouling within the facility by separating highly concentrated wax through the supply of the polyolefin reaction product to a wax filter that separates wax.
[0005] Fouling that occurs during the manufacture of polyolefins hinders the maintenance of consistent thermal conductivity at the substrate walls, making temperature control during polymerization difficult and interfering with the production of products of consistent quality. Therefore, fouling generated during the continuous process must be removed regularly, but this process presents the problem of incurring additional costs and time.
[0006] For this reason, various methods are being proposed to eliminate fouling phenomena occurring during the production process of polyolefins.
[0007] For example, there is a method to reduce fouling by performing pre-polymerization, but this method is not economical in that it requires a separate reactor for pre-polymerization and a separate system to detect sensitive reaction conditions. Another example is coating the metal surface inside the reactor, but this method has the disadvantage that production must be stopped for a long time during the coating process and requires high-cost investment. Yet another example is a method to prevent the formation of locally overheated polymer particles by introducing inert gases such as nitrogen (N2) and helium (He) into the polymerization reactor along with the monomer gas, but this method has the disadvantage of reducing the partial pressure of the monomer inside the reactor, thereby reducing the activity of the catalyst.
[0008] In addition, many methods using antifouling agents have generally been proposed. In metallocene catalyst-based processes, polysiloxane has been used as an antifouling agent, and in chromium catalyst-based processes where fouling caused by the charge of polymer particles is severe, antifouling methods using polysulfone copolymers, polyamines, sulfonic acids, etc. have been proposed. Furthermore, in processes for copolymerizing ethylene / propylene or EPDM using homogeneous catalysts, a method has been proposed to use ethyl aluminum containing chloride groups together with trialkyl aluminum.
[0009] However, such methods have disadvantages, such as requiring high costs, affecting the reaction, or being applicable only to specific catalytic processes. Therefore, there is a need to develop a method that fundamentally prevents fouling through a simple process.
[0010] The present invention aims to solve these problems and provides a method for manufacturing polyolefin that prevents fouling by supplying a reaction product to a wax filter to remove polyethylene wax, which causes fouling in the polyolefin manufacturing process.
[0011] According to one aspect of the present invention, a first step of introducing a feed comprising a monomer, a comonomer, and a solvent into a reactor to produce a reaction product comprising a polyolefin, a solvent, and a wax; a second step of supplying the reaction product to a separator to separate it into a first solution comprising a solvent and a wax and a slurry comprising a polyolefin in the separator, supplying the first stream comprising the first solution to a wax filter and supplying the slurry to a dryer; a third step of drying the slurry in the dryer to obtain a polyolefin, condensing the gaseous component generated by the drying to prepare a second solution, and supplying the second solution to a purification unit. The present invention provides a method for manufacturing a polyolefin comprising: a fourth step of passing the first solution through a wax filter equipped with a plurality of inclined plates spaced apart at a certain interval to separate it into a third solution containing a solvent and a comonomer and the wax, wherein at least a portion of the third stream containing the third solution is recovered to the reactor and the wax forms a highly concentrated wax and is discharged outside the system.
[0012] According to the present invention, a method for manufacturing a polyolefin can be provided in which a reaction product is supplied to a wax filter during the manufacturing process of the polyolefin to prevent fouling by separating the polyethylene wax that causes fouling.
[0013] In addition, according to the present invention, the wax filter is provided with a plurality of inclined plates spaced apart at a certain interval to sequentially separate the wax according to size, thereby significantly reducing the concentration of wax in the reaction product.
[0014] Figure 1 shows a flowchart of a method for manufacturing polyolefin including a wax filter according to an embodiment of the present invention.
[0015] Figure 2 shows a flowchart of a polyolefin manufacturing method according to Comparative Example 1.
[0016] FIG. 3 schematically shows a cross-section of a wax filter according to an embodiment of the present invention.
[0017] FIG. 4 shows the average size and volume (1) of wax particles separated in the third region of a wax filter, the average size and volume (2) of wax particles separated in the second region, and the average size and volume (3) of wax particles separated in the first region, according to an embodiment of the present invention.
[0018] Terms and words used in the description and claims of the present invention shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.
[0019] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.
[0020] The singular form of the noun corresponding to the item may include one or multiple items, unless the relevant context clearly indicates otherwise.
[0021] In the present disclosure, each of the phrases such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.
[0022] The term "and / or" includes a combination of multiple related described components or any of the multiple related described components.
[0023] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish a component from another component and do not limit the components in other aspects (e.g., importance or order).
[0024] In addition, terms such as 'front,' 'rear,' 'top,' 'bottom,' 'side,' 'left,' 'right,' 'top,' and 'bottom' used herein are defined based on the drawings, and the shape and location of each component are not limited by these terms.
[0025] Terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this disclosure, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.
[0026] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.
[0027] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.
[0028] As used herein, the term 'stream' may refer to the flow of fluid within a process, and may also refer to the fluid itself flowing within the piping. Specifically, the stream may simultaneously refer to the fluid itself flowing within the piping connecting each device and the flow of the fluid. Additionally, the fluid may include one or more components among gas, liquid, and solid.
[0029] Unless otherwise specified, the term "upper" as used herein refers to a point at a height of 0% to 10% downward from the top of the device, and specifically may refer to the top in the opposite direction of gravity. Additionally, the term "lower" refers to a point at a height of 90% to 100% downward from the top of the device, and specifically may refer to the bottom in the direction of the wax outlet or gravity.
[0030] In addition, "pressure" as used herein refers to gauge pressure measured under atmospheric pressure conditions.
[0031] The method for manufacturing a polyolefin according to the present invention will be explained below with reference to FIGS. 1 and 3. FIG. 1 is a flowchart of a method for manufacturing a polyolefin according to one embodiment of the present invention, and FIG. 3 is a schematic cross-section of a wax filter according to one embodiment of the present invention.
[0032] According to one embodiment of the present invention, a first step of introducing a feed comprising a monomer, a comonomer, and a solvent into a reactor to produce a reaction product comprising a polyolefin, a solvent, and a wax; a second step of supplying the reaction product to a separator to separate it into a first solution comprising a solvent and a wax and a slurry comprising a polyolefin in the separator, supplying the first stream comprising the first solution to a wax filter and supplying the slurry to a dryer; a third step of drying the slurry in the dryer to obtain a polyolefin, condensing the gaseous component generated by the drying to prepare a second solution, and supplying the second solution to a purification unit. The method for manufacturing a polyolefin may include a fourth step of supplying the first solution to a wax filter equipped with a plurality of inclined plates spaced apart at a certain interval to separate the wax into a third solution containing a solvent and a comonomer, and the third solution being discharged as a third stream, at least a portion of the third stream being recovered to the reactor, and the wax forming a highly concentrated wax and being discharged outside the system.
[0033] Polyolefins are polymers made from olefin monomers, which are compounds containing carbon and hydrogen atoms. The most commonly used polyolefins are polyethylene (PE) and polypropylene (PP), which are widely used for various applications due to their advantages, such as high strength, flexibility, chemical resistance, and low cost. During the production process of polyolefins, polyethylene wax may be generated as a byproduct. Since polyethylene wax is adhesive, it can adhere to the produced polyolefin or process equipment, causing fouling. In such cases, process efficiency is reduced, and the quality of the resulting polyolefin may deteriorate. Therefore, the present invention discloses a method for reducing fouling by decreasing the concentration of wax in the stream during the polyolefin manufacturing process, thereby enabling the production of high-quality polyolefin with high efficiency.
[0034] According to one embodiment of the present invention, a method for manufacturing a polyolefin according to the present invention may include a first step of introducing a feed comprising a monomer, a comonomer, and a solvent into a reactor (100) to produce a reaction product comprising a polyolefin, a solvent, and a wax. The feed may include all materials necessary for manufacturing the polyolefin, and may also include other materials in addition to the monomer, comonomer, and solvent.
[0035] Specifically, for the production of polyolefins, a feed containing monomers, comonomers, and a solvent may first be introduced into a reactor, and a polymerization reaction may be performed. The monomers and comonomers introduced into the reactor may react under specific conditions to produce polyolefins. After the reaction is completed, the reaction product may include not only the synthesized polyolefins but also unreacted monomers, unreacted comonomers, solvents, and waxes.
[0036] The above monomer, comonomer, and solvent may be added differently depending on the type of polyolefin to be manufactured.
[0037] For example, the monomer may be ethylene, but is not limited thereto. Also, for example, the comonomer may be selected from the group consisting of propylene, butene, and combinations thereof, but is not limited thereto. Also, for example, the solvent may be selected from the group consisting of hexane, cyclohexane, benzene, and combinations thereof, but is not limited thereto.
[0038] Next, a method for manufacturing a polyolefin according to one embodiment of the present invention may include a second step of supplying the reaction product to a separator (200), separating it in the separator (200) into a first solution containing a solvent and a wax and a slurry containing a polyolefin, supplying the first stream containing the first solution to a wax filter (400), and supplying the slurry to a dryer (300).
[0039] Specifically, the reaction product may include not only the polyolefin polymerized by the reaction but also unreacted comonomers, solvents, and other substances, and may include wax as a byproduct. Since the unreacted comonomers and solvents can be circulated to the reactor and reused in the polyolefin manufacturing process, it is necessary to separate them from the polyolefin for this purpose. The unreacted comonomers and solvents may be present mixed in the first solution, and although the wax is in solid form, it may be included in the first solution due to the difference in specific gravity with the polyolefin when solid-liquid separation is performed. The polyolefin may be included in the slurry, but trace amounts of the unreacted comonomers, solvents, and wax may be included in the slurry.
[0040] The separator (200) can separate the slurry and the first solution by performing solid-liquid separation such as filtration, gravity sedimentation, or centrifugation. The separator (200) can use any method capable of separating the slurry in a solid state and the first solution in a liquid state without limitation. For example, the separator may be a centrifuge or a centrifuge decanter, but is not limited thereto.
[0041] The first solution contains a solvent and unreacted comonomers, which can be circulated and reused in the reactor. However, since the first solution also contains wax, the wax may be circulated along with the solution during the circulation process. The wax may be produced at different concentrations depending on the grade of the polyolefin to be manufactured; if the wax is present at a high concentration in the first solution, the quality of the polyolefin may deteriorate and fouling may occur in the process equipment. The concentration of wax in the first solution can cause fouling as the wax accumulates at a high concentration and continues to circulate, not only in processes where the wax is produced at a high concentration but also in processes where it is produced at a low concentration.
[0042] To prevent this, the first solution is supplied to the wax filter (400) through the first stream (S1), and the wax contained in the first solution can be separated in the wax filter (400) to lower the concentration of the wax.
[0043] Next, a method for manufacturing a polyolefin according to one embodiment of the present invention may include a third step of obtaining a polyolefin by drying the slurry in the dryer (300), preparing a second solution by condensing the gaseous component generated by the drying, and supplying the second solution to a purification unit (500).
[0044] The above slurry may be supplied to the dryer to obtain a polyolefin from which the solvent, unreacted comonomer, wax, etc., have been removed. Since the slurry may contain substances such as the solvent, comonomer, and wax in addition to the polyolefin, it is necessary to remove them for the commercialization of the polyolefin. Since most of the monomer is used in the reaction, it may not be present in the slurry or may be present in trace amounts.
[0045] The above dryer (300) may be, for example, a fluidized bed dryer, but is not limited thereto.
[0046] If the dryer (300) is a fluidized bed dryer, the dryer may include a plurality of heating panels arranged side by side at a certain distance from one side of the dryer to the other, and the slurry may be dried by passing through the heating panels sequentially. Additionally, the dryer may be supplied with a heated gas in a hot state from the bottom to the top, and the slurry may be dried by contacting the heated gas while passing through the heating panels. Specifically, the heated gas supplied to the dryer may pass through a perforated plate located at the bottom of the dryer and flow into the interior of the dryer, and after drying the slurry by passing through a plurality of heating panels provided perpendicularly to the perforated plate on the top of the perforated plate, it may be discharged through a gas outlet at the top of the dryer. In this process, as the heated gas contacts the slurry, the solvent and comonomer remaining in the slurry are vaporized, and the polyolefin can be discharged and obtained. The wax remaining in the above slurry may remain in the polyolefin and be discharged together. The vaporized solvent and comonomer may be discharged through the gas outlet, condensed into the second solution, and supplied to the purification unit through the second stream (S2).
[0047] The heated gas may be a gas capable of drying the slurry without reacting with the slurry. For example, the heated gas may be nitrogen gas (N2).
[0048] Next, a method for manufacturing a polyolefin according to one embodiment of the present invention may include a fourth step of supplying the first solution to a wax filter equipped with a plurality of inclined plates spaced apart at a certain interval to separate the wax into a third solution containing a solvent and a comonomer, and the third solution being discharged as a third stream, at least a portion of the third stream being recovered to the reactor to form the highly concentrated wax and discharged outside the system.
[0049] Since the first solution contains most of the wax included in the reaction product, fouling may occur in the process equipment if the first solution is returned directly to the reactor. Therefore, it is necessary to separate the wax from the first solution to lower the wax concentration of the solution returned to the reactor. To this end, the first solution can be supplied to the wax filter (400).
[0050] The wax filter (400) may include a case frame (10), a solution supply port (20) provided on the upper side of the case frame (or wax filter), a plurality of inclined plates spaced apart at a certain interval inside the case frame (or wax filter), a wax discharge port on the lower side of the case frame (or wax filter), a first area (30), a second area (40), and a third area (50) arranged sequentially, a fourth area (60) for collecting the third solution separated from the wax in the third area, and a solution discharge port (70) provided on the lower side of the other side of the case frame (or wax filter).
[0051] The wax filter (400) may separate the supplied first solution into a third solution containing the solvent and comonomer and a highly concentrated wax containing the wax. The wax filter is divided into a first region, a second region, and a third region according to the particle size of the highly concentrated wax being separated, and the first solution may be separated into a solution and a wax as it passes sequentially through the first region, the second region, and the third region.
[0052] Specifically, the first region (30) may be spaced apart from each other at an angle of inclination of 57˚ to 63˚ with respect to the lower surface of the frame case at intervals of L. The first solution may be supplied to the solution supply port and may be supplied to the first region through the lower end of the first-1 inclined plate, which is the first inclined plate positioned closest to the solution supply port in the first region. The first-1 inclined plate is connected to the upper surface of the case frame to form a barrier, thereby allowing the first solution to be supplied to the first region only through the space formed between the first-1 inclined plate and the lower surface of the case frame (i.e., the lower space of the first-1 inclined plate). On the other hand, since the first solution is supplied only through the lower space of the first-1 inclined plate and passes through the upper space of the first divider plate to be supplied to the second region, the first solution undergoes a process of being separated into solution and wax by passing through the first inclined plate.
[0053] The first solution supplied to the first region (30) may flow from the bottom to the top of the first-1 inclined plate, or the first solution may flow into the space formed between the bottom surface of the case frame and the first inclined plate (i.e., the bottom space of the first inclined plate). The surface of the first inclined plate is provided facing the solution supply port, and while the first solution flows from the bottom to the top along the first-1 inclined plate, the first solution is separated into the first region filtered liquid and the wax due to the difference in density, and the wax may flow to the bottom of the first-1 inclined plate and be discharged through the first region wax outlet provided on the bottom surface of the case frame. Even when the first solution flows into the bottom space of the first inclined plate, the wax may be separated through the same process at a first inclined plate other than the first-1 inclined plate. The wax may be concentrated at the first region wax outlet and discharged as highly concentrated wax. In the first region, the upper and lower ends of the first inclined plates, excluding the first-1 inclined plate, are spaced apart from the upper and lower surfaces of the case frame to form a space, and the first solution and the first region filtrate can pass through this space (i.e., the upper space of the first inclined plate or the lower space of the first inclined plate) and sequentially pass through the first inclined plates. In other words, the first solution can move from the first-1 inclined plate toward the direction of the second region while passing through the first inclined plates, and in the process, it is separated into the first region filtrate and wax due to a difference in density, the first region filtrate is supplied to the second region, and the wax flows toward the lower part of the first inclined plate and is collected at the first region wax outlet to form the highly concentrated wax and discharge it.
[0054] Meanwhile, since the upper ends of the plurality of first inclined plates are constant at the same height and the lower ends of the plurality of first inclined plates are constant at the same height, the first solution passes through the first inclined plates for the same amount of time, so the average size of the wax separated in the first region can be constant.
[0055] Additionally, regarding the first inclined plate, L may be a gap at which the first solution can be separated into solution and wax as it passes through the first inclined plate, for example, 40 mm to 60 mm or 45 mm to 55 mm. If L is less than 40 mm, wax may accumulate between the first inclined plates, blocking the space between them, and the wax may not be separated effectively. Furthermore, if L exceeds 60 mm, the distance (i.e., sedimentation distance) over which wax particles separate from the solution and reach the surface of the first inclined plate increases, which may reduce separation efficiency. Although the rate at which the wax is separated from the first solution and the filtered liquid in the first region is constant, if the sedimentation distance increases, the time it takes for the wax to reach the surface of the first inclined plate increases, and the separation of the wax may not occur efficiently. This same principle may apply to the second and third regions as well.
[0056] In addition, the inclination angle of the first inclined plate may be an angle at which the first region filtrate and the highly concentrated wax can be separated and moved due to the difference in density within the gap of L. In addition, the inclination angle of the first inclined plate may be an angle at which the surface of the first inclined plate lies facing the solution supply port and in the direction of the solution discharge port. The inclination angle of the first inclined plate may be 57° to 63° or 59° to 61° relative to the bottom surface of the frame case (or the bottom surface of the wax filter) when the bottom surface of the frame case (or the bottom surface of the wax filter) is set to 0°. If the inclination angle of the first inclined plate is less than 57°, the time (i.e., residence time) for the wax particles to be separated from the first region filtrate and reach the surface of the first inclined plate may be shortened, but the wax particles may be over-precipitated on the inclined surface of the first inclined plate, causing the space between the first inclined plates to become clogged. In addition, if the angle of inclination of the first inclined plate exceeds 63˚, the residence time becomes longer, which may reduce the separation efficiency.
[0057] In addition, the highly concentrated wax separated in the first region may have an average particle size of 50 μm or more and less than 100 μm. The highly concentrated wax separated in the first region may have the largest average particle size among the first, second, and third regions.
[0058] The first solution may be supplied to the wax filter at a flow rate of 0.5 mm / s to 1.5 mm / s or 0.8 mm / s to 1.3 mm / s. The flow rate of the first solution may be a speed capable of inducing a flow such that the solution supplied to the solution supply port and present inside the wax filter moves to the other lower side of the wax filter where the solution discharge port is located. If the flow rate of the first solution exceeds 1.5 mm / s, the speed at which the solution passes through the wax filter is faster than the speed at which the wax is separated from the solution, and thus the separation efficiency of the wax particles may decrease. Additionally, if the flow rate of the first solution is less than 0.5 mm / s, the speed at which the solution passes through the wax filter is slower, which may increase the sedimentation efficiency of the wax particles, but the processing capacity may decrease in the same amount of time.
[0059] If the first solution passes only through the first region, 20 wt% to 40 wt% of the wax contained in the first solution may be separated.
[0060] Additionally, specifically, the second area (40) may have a plurality of second inclined plates spaced apart at intervals of 4 L / 10 to 6 L / 10 and at an angle of inclination of 52˚ to 57˚ with respect to the lower surface of the frame case. The first area filtered liquid separated from the first area may be supplied to the second area by passing through the space between the top of the first dividing plate separating the first area and the second area and the upper surface of the case frame (i.e., the upper space of the first dividing plate). Since the first area filtered liquid is supplied only to the upper space of the first dividing plate, the first area filtered liquid supplied to the second area may all be a solution from which wax has been primarily removed by passing through the first inclined plate in the first area. Subsequently, the first area filtered liquid may be supplied to the space formed between the second-1 inclined plate, which is the second inclined plate closest to the first dividing plate in the second area, and the lower surface of the case frame (i.e., the lower space of the second-1 inclined plate). Since the above-mentioned 2-1 inclined plate is connected to the upper surface of the case frame to form a barrier, the filtered liquid of the first area can be supplied to the second area only through the space formed between the lower end of the 2-1 inclined plate and the lower surface of the case frame (i.e., the space at the bottom of the 2-1 inclined plate). On the other hand, since the above-mentioned 1 separating plate is connected to the lower surface of the case frame, the filtered liquid of the first area is supplied only to the space at the bottom of the 2-1 inclined plate by passing through the upper space of the 1 separating plate, and the filtered liquid of the second area is supplied to the second area by passing through the upper space of the second separating plate; thus, the filtered liquid of the first area undergoes a process of being separated into solution and wax by passing through the above-mentioned 2-1 inclined plate.
[0061] The first area filtered liquid supplied to the second area (40) may flow from the bottom to the top of the second-1 inclined plate, or the first area filtered liquid may flow into the space formed between the bottom of the case frame and the second inclined plate (i.e., the bottom space of the second inclined plate). The surface of the second inclined plate is provided facing the first dividing plate, and while the first area filtered liquid flows from the bottom to the top along the second-1 inclined plate, the first area filtered liquid is separated into the second area filtered liquid and wax due to the difference in density, and the wax may flow to the bottom of the second-1 inclined plate and be discharged through the first area wax outlet provided on the bottom of the case frame. Even when the first area filtered liquid flows into the bottom space of the second inclined plate, the wax may be separated and discharged through the same process at the second inclined plate other than the second-1 inclined plate. The wax may be concentrated at the second area wax outlet and discharged as highly concentrated wax. In the second region, the upper and lower ends of the second inclined plates, excluding the second-1 inclined plate, are spaced apart from the upper and lower surfaces of the case frame to form a space, and the first region filter and the second region filter may pass through this space (i.e., the upper space of the second inclined plate or the lower space of the second inclined plate) and pass through the second inclined plate. In other words, the first region filter may move from the second-1 inclined plate toward the direction of the third region while passing through the second inclined plate, and in the process, it may be separated into the second region filter and wax due to a difference in density, the second region filter may be supplied to the third region, and the wax may flow toward the lower part of the second inclined plate to form the highly concentrated wax and be discharged through the second region wax discharge port.
[0062] Meanwhile, since the upper ends of the plurality of second inclined plates are constant at the same height and the lower ends of the plurality of second inclined plates are constant at the same height, the filtered liquid in the first region passes through the second inclined plates for the same amount of time, so the average size of the wax separated in the second region can be constant.
[0063] In addition, the gap between the second inclined plates may be a gap at which the first region filtrate can be separated into solution and wax as it passes through the second inclined plates. If the gap between the second inclined plates is less than 4 L / 10 mm, wax may accumulate between the second inclined plates, blocking the space between the plates, and the wax may not be separated well. In addition, if the gap between the second inclined plates exceeds 6 L / 10 mm, the sedimentation distance may increase, and the separation efficiency may decrease.
[0064] In addition, the inclination angle of the second inclined plate may be an angle at which the solution and wax can be separated and moved due to the difference in density within the gap between the second inclined plates. In addition, the inclination angle of the second inclined plate may be an angle at which the surface of the second inclined plate lies facing the first region and in the direction of the solution outlet. The inclination angle of the second inclined plate may be 52° to 57° or 54° to 56° relative to the bottom surface of the frame case (or the bottom surface of the wax filter) when the bottom surface of the frame case (or the bottom surface of the wax filter) is set to 0°. If the inclination angle of the second inclined plate is less than 52°, the residence time may be shortened, but wax particles may be over-precipitated on the inclined surface of the second inclined plate, causing the space between the second inclined plates to become clogged. In addition, if the inclination angle of the second inclined plate exceeds 57°, the residence time may be prolonged, which may reduce the separation efficiency.
[0065] In addition, the highly concentrated wax separated in the second region may have an average particle size of 15 μm or more and less than 50 μm. The second region may separate wax that is smaller than the average size of the wax particles separated in the first region and larger than the average size of the wax particles separated in the third region.
[0066] When the first solution passes through the first region and the second region, 60 wt% to 80 wt% of the wax contained in the first solution can be separated. In the second region, wax with an average particle size of medium is separated, and the largest amount of wax can be separated.
[0067] Additionally, specifically, the third area (50) may be spaced apart from each other at an angle of inclination of 47˚ to 52˚ with respect to the lower surface of the frame case at intervals of 2L / 10 to 4L / 10. The second area filtered liquid separated from the second area may be supplied to the third area by passing through the space between the upper surface of the second dividing plate separating the second area and the upper surface of the case frame (i.e., the upper space of the second dividing plate). Since the second area filtered liquid is supplied only to the upper space of the second dividing plate, the second area filtered liquid supplied to the third area may be a solution from which wax has been removed by passing through the second inclining plate in the second area. Subsequently, the second area filtered liquid may be supplied to the third area by passing through the space formed between the lower surface of the case frame and the third-1 inclining plate, which is the third inclining plate closest to the second dividing plate in the third area (i.e., the lower space of the third-1 inclining plate). Since the above-mentioned 3-1 inclined plate is connected to the upper surface of the case frame to form a barrier, the filtered liquid of the second region can be supplied to the third inclined plate only through the space formed between the lower end of the 3-1 inclined plate and the lower surface of the case frame (i.e., the lower space of the 2-1 inclined plate). On the other hand, since the second separating plate is connected to the lower surface of the case frame, the filtered liquid of the second region is supplied only to the lower space of the 3-1 inclined plate by passing through the upper space of the second separating plate, and the third solution is supplied to the fourth region by passing through the upper space of the third separating plate; thus, the filtered liquid of the third region undergoes a process of being separated into solution and wax by passing through the third inclined plate.
[0068] The second area filtrate supplied to the third area (50) may flow from the bottom to the top of the third-1 inclined plate, or the second area filtrate may flow into the space formed between the bottom of the case frame and the third inclined plate (i.e., the bottom space of the third inclined plate). The surface of the third inclined plate is provided facing the second dividing plate, and while the second area filtrate flows from the bottom to the top along the third-1 inclined plate, the second area filtrate is separated into the third area filtrate and wax due to the difference in density, and the wax may flow to the bottom of the third-1 inclined plate and be discharged through the third area wax outlet provided on the bottom of the case frame. Even when the second area filtrate flows into the bottom space of the third inclined plate, the wax may be separated and discharged through the same process at the third inclined plate other than the third-1 inclined plate. The wax may be concentrated at the third area wax outlet and discharged as highly concentrated wax. In the third region, the upper and lower ends of the third inclined plates, excluding the third-1 inclined plate, are spaced apart from the upper and lower surfaces of the case frame to form a space, and the second region filtrate and the third region filtrate can pass through this space (i.e., the upper space of the third inclined plate or the lower space of the third inclined plate) and pass through the third inclined plate. In other words, the second region filtrate can move from the third-1 inclined plate toward the direction of the fourth region while passing through the third inclined plate, and in the process, it is separated into the third solution and wax due to a difference in density, the third solution is supplied to the fourth region, and the wax flows toward the lower part of the third inclined plate to form the highly concentrated wax and be discharged through the third region wax outlet.
[0069] Meanwhile, since the upper ends of the plurality of third inclined plates are constant at the same height and the lower ends of the plurality of third inclined plates are constant at the same height, the third solution passes through the third inclined plates for the same amount of time, so the average size of the wax separated in the third region can be constant.
[0070] In addition, the gap between the third inclined plates may be a gap at which the second region filtrate can be separated into solution and wax as it passes through the third inclined plates. If the gap between the third inclined plates is less than 2 L / 10 mm, backflow of fine wax particles may occur between the third inclined plates, causing the wax to float rather than fall onto the surface of the third inclined plates, thereby reducing the separation efficiency. Additionally, if the gap between the third inclined plates exceeds 4 L / 10 mm, the sedimentation distance of the wax particles increases, which may reduce the separation efficiency.
[0071] In addition, the inclination angle of the third inclined plate may be an angle at which the solution and wax can be separated and moved due to the difference in density within the gap between the third inclined plates. In addition, the inclination angle of the third inclined plate may be an angle at which the surface of the third inclined plate lies facing the second region and toward the solution outlet. The inclination angle of the third inclined plate may be 47° to 52° or 49° to 51° relative to the bottom surface of the frame case (or the bottom surface of the wax filter) when the bottom surface of the frame case (or the bottom surface of the wax filter) is set to 0°. If the inclination angle of the second inclined plate is less than 47°, the residence time may be shortened, but wax particles may be over-precipitated on the inclined surface of the second inclined plate, causing the space between the second inclined plates to become clogged. In addition, if the inclination angle of the third inclined plate exceeds 52°, the residence time may be prolonged, which may reduce the separation efficiency.
[0072] In addition, the highly concentrated wax separated in the third region may have an average particle size of 0.1 μm or more and less than 15 μm. The third region may separate wax that is smaller than the average size of the wax particles separated in the first and second regions.
[0073] When the first solution passes sequentially through the first region, the second region, and the third region, 80 wt% to 95 wt% of the wax contained in the first solution can be separated.
[0074] Additionally, specifically, the fourth region (60) may be a place where the third solution supplied from the third region is collected. The third solution may be supplied to the fourth region by passing through the space between the top of the third divider separating the third region and the upper surface of the case frame (i.e., the space above the third divider). The third solution may be discharged as the third stream (S3) through the solution outlet (70) after passing through the fourth region.
[0075] The wax filter (400) may filter the wax contained in the solution according to particle size by sequentially decreasing the spacing between the plurality of inclined plates and the angle of inclination as it moves from the first region to the third region. Specifically, as the spacing between the inclined plates and the angle of inclination decrease, the residence time of the solution increases, which can increase the time for the solution and wax to be separated and allow for the separation of smaller particles. By utilizing this, in the first region, the spacing between the inclined plates and the angle of inclination are set large to separate wax with a large average particle size, and wax with a smaller average particle size is gradually separated. Furthermore, the first solution has a high concentration of the wax, and consequently, the viscosity of the first solution is high and waxes with large particle sizes are mixed in. Therefore, if the spacing between the inclined plates is narrow, there is a risk of the spaces between the inclined plates becoming clogged, so the spacing between the inclined plates in the first region must be large. This may mean that if the first solution is supplied directly to the second region or the third region, the spaces between the second inclined plates or the third inclined plates may become clogged by the wax. As the first solution passes sequentially through the first region, the second region, and the third region, the concentration and viscosity of the wax are reduced, so that the wax can be effectively separated even if the gap between the inclined plates is small.
[0076] In addition, the materials of the first, second, and third inclined plates may be materials capable of separating the solution and wax in each area due to a difference in density. Specifically, the material of the inclined plate may be a material capable of inducing the wax separated from the solution to slide by gravity and be collected on the lower surface of the frame case after reaching the surface of the inclined plate, without being separated from the surface of the inclined plate. Specifically, the material of the inclined plate may be stainless steel (SUS) or polypropylene (PP).
[0077] In addition, the thickness of the first inclined plate, the second inclined plate, and the third inclined plate may be such that it does not affect the separation of the solution and the wax, and specifically, it may be 1.5 mm to 3 mm.
[0078] In addition, the first inclined plate, the second inclined plate, and the third inclined plate may be provided in a number sufficient to separate the solution and the wax in proportion to the amount of solution supplied to each area, and specifically, there may be 50 to 200 of them.
[0079] In addition, the third solution, which is the filtrate discharged from the wax filter, is a solution from which most of the highly concentrated wax has been removed, and may have a wax concentration such that it does not cause fouling even when recovered to the reactor.
[0080] Specifically, the concentration of wax in the third solution may be 0.9 wt% or less, more specifically 0.3 wt% or less, and more specifically 0.01 to 0.3 wt% or less. The concentration of wax in the third solution is expressed as a mass ratio of wax content based on the mass flow rate of the third stream (100 wt%). If the concentration of wax in the third solution exceeds 0.9 wt%, the amount of wax flowing into the dryer increases, and flow instability of the sludge within the dryer may occur due to the adhesiveness of the wax. Additionally, if the concentration of wax in the third solution exceeds 0.9 wt%, fouling may occur in the dryer, piping, and purification section, etc.
[0081] If the concentration of wax in the third stream exceeds the above range, fouling may occur in various parts of the equipment, such as the third stream, reactor, separator, and wax separator. If the concentration of wax exceeds the above range, the amount of wax remaining in the slurry increases, which may cause fouling inside the dryer. Specifically, the fouling may be a phenomenon where the wax remains on the walls of the piping, in dead zones within the piping, or on valves, thereby obstructing the smooth flow of the stream. Additionally, the fouling may be a phenomenon where the wax forms lumps inside the dryer, blocking the holes of the perforated plates provided inside the dryer. Furthermore, the fouling may be a phenomenon where the wax forms lumps in the purification section, blocking the sieves of the columns. Therefore, the concentration of wax in the third solution must be maintained so as not to exceed the above range.
[0082] The third solution may be discharged from the wax filter into the third stream through the solution outlet. The third stream may undergo a circulation process in which it is recovered to the reactor, reused in the reactor, and then supplied to the separator. This circulation process may occur continuously during the course of the process. In this process, the third stream may be branched so that only a certain flow rate is circulated to the reactor and the remainder is supplied to the purification unit.
[0083] Meanwhile, at least a portion of the third stream (S3) may be branched and circulated to the reactor, while the remainder of the third stream may be supplied to the purification unit through the third-1 stream (S3-1). Specifically, if the mass flow rate of the third stream exceeds a certain range, the excess flow rate, which is the excess portion, may be supplied to the purification unit through the third-1 stream (S3-1). That is, the excess flow rate refers to the flow rate branched from the third stream and supplied to the purification unit. The third solution flowing through the third stream may contain trace amounts of the wax, but may contain low levels of impurities such as moisture or oxygen because it is not exposed to the outside of the process equipment. On the other hand, the solution purified and discharged from the purification unit may contain almost no wax, but may contain high levels of impurities such as moisture or oxygen because it is exposed to the outside. If high levels of impurities are present, a large amount of scavengers are consumed to remove them, the reaction efficiency for polyolefin synthesis decreases, and the quality of the polyolefin may deteriorate.
[0084] The above excess flow rate may be 15 wt% to 25 wt% of the total mass flow rate of the third stream. Since the concentration of wax contained in the third-1 stream (S3-1) is the same as the concentration of wax in the third solution, it is possible to keep the concentration of wax contained in the third-1 stream (S3-1) low, at 0.9 wt% or less relative to the mass flow rate of the third-1 stream (S3-1) (100 wt%). Furthermore, as previously explained, the amount of impurities contained in this third-1 stream (S3-1) may be such that even when the third-1 stream (S3-1) is supplied to the reactor through the purification unit, the impurities do not affect the production of the polyolefin.
[0085] In addition, a method for manufacturing a polyolefin according to one embodiment of the present invention may include purifying a solution supplied from the second stream (S2) or the third-first stream (S3-1) in the purification unit (500) to separate the wax, comonomer, and solvent, supplying a fourth solution containing the solvent and comonomer separated in the purification unit to the reactor through the fourth stream (S4), and discharging the wax out of the system.
[0086] The purification unit (500) is equipped with a filter and a distillation column capable of further separating the wax, and can purify the wax, solvent, and comonomer from the solution supplied to the purification unit. First, when the second stream (S2) or the third-1 stream (S3-1) is supplied to the purification unit (500), a process for separating the wax from the solution can be performed. In the process of separating the wax, any method capable of separating the wax contained in trace amounts in the solution can be used without limitation. Afterward, the solution from which the wax has been removed can be sequentially supplied to a distillation column for separating the solvent and comonomer to separate the solvent and comonomer. The solvent and comonomer separated in this way may be in a state where the wax has been almost completely removed, and can be mixed again with the fourth solution and recovered to the reactor (100) through the fourth stream (S4) to be used for the manufacture of polyolefin.
[0087] In addition, the mass flow rate of the solution supplied to the purification unit (500) may be nearly the same as the mass flow rate of the solution purified in the purification unit and supplied to the reactor. In the purification unit, only the wax is removed from the solution supplied from the second stream (S2) and the third-1 stream (S3-1), and then supplied to the reactor, thereby allowing the solvent and comonomer to be supplied back to the reactor with almost no loss. Therefore, the additional supply amount of the solvent and comonomer can be reduced, thereby reducing the cost of manufacturing polyolefin.
[0088] The wax separated in the above purification unit and the wax separated in the wax filter can be discharged outside the system.
[0089]
[0090] The present invention will be explained in more detail below through examples and comparative examples. However, the following examples are intended to illustrate the present invention, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and spirit of the present invention, and the scope of the present invention is not limited only to these examples.
[0091] Examples
[0092] To manufacture high-density polyethylene (HDPE), a feed containing ethylene as a monomer, butene as a comonomer, and hexane as a solvent was introduced into the reactor to carry out the reaction. After the reaction was completed, the reaction product was supplied to the separator to separate it into a solid phase containing high-density polyethylene in the form of a slurry and a liquid phase (first solution) containing solvent, wax, and unreacted comonomer. The separator separated the solid phase and the liquid phase using a dewatering screw press, which is a centrifugal dewatering machine.
[0093] The slurry separated in the above separator is supplied to the above dryer, and hot nitrogen gas is injected from the bottom of the above dryer to dry the slurry, and the vaporized liquid component is condensed to separate it into a solution containing a solvent and wax (second solution) and dried high-density polyethylene, the second solution is supplied to the purification unit, and the high-density polyethylene is discharged out of the system to obtain.
[0094] The first solution separated in the separator was supplied at a speed of 0.7 mm / s to the wax filter, which was sequentially equipped with a first region, a second region, and a third region. In the wax filter, the first region had six first inclined plates arranged at intervals of 50 mm with an angle of 60˚ with respect to the lower surface of the case frame. As the first solution passed through the first region, it was separated into a highly concentrated wax with an average particle size of 50 μm and a first region filtrate; the highly concentrated wax was discharged out of the wax filter, and the first region filtrate was supplied to the second region.
[0095] In the wax filter, the second region is formed by 12 second inclined plates arranged at intervals of 25 mm with an angle of 55˚ relative to the lower surface of the case frame. As the filtrate of the first region passes through the second region, it is separated into highly concentrated wax with an average particle size of 15 μm and the filtrate of the second region; the highly concentrated wax is discharged out of the wax filter, and the filtrate of the second region is supplied to the third region.
[0096] In the wax filter, the third region is formed by 24 third inclined plates arranged at intervals of 12.5 mm with an angle of 50˚ relative to the lower surface of the case frame. As the filtrate from the second region passes through the third region, it is separated into fine highly concentrated wax with an average particle size of less than 15 μm and a third solution; the highly concentrated wax is discharged out of the wax filter, and the third solution is discharged into a third stream through an outlet located at the lower end of the wax filter. The highly concentrated wax separated in the wax separator is discharged outside the system.
[0097] The third solution is collected in the fourth area and discharged into the third stream through the solution outlet, and the third stream is branched so that a portion is recovered to the reactor and the remainder is supplied to the purification unit.
[0098] The second and third solutions supplied to the purification unit were separated into a solvent, a comonomer, and a wax; the wax was discharged out of the system, and the solvent and comonomer were recovered into the reactor.
[0099] Comparative Example 1
[0100] The process was performed identically in the example, except that a wax filter was not used.
[0101] Comparative Example 2
[0102] The process was performed in the same manner, except that a wax filter equipped with only the first region was used in the example.
[0103] Comparative Example 3
[0104] The process was performed in the same manner, except that a wax filter equipped with only the first and second regions was used in the example.
[0105] Comparative Example 4
[0106] The process was performed in the same manner, except that a wax filter equipped with only the third region was used in the example.
[0107] Table 1 below indicates the degree to which wax is separated from the first solution and whether fouling occurs within the wax filter according to the configuration of the wax filter in the examples and comparative examples. Additionally, FIG. 1 is a flowchart showing the overall process of manufacturing a polyolefin in the example, and FIG. 2 is a flowchart showing the overall process of manufacturing a polyolefin without using the wax filter in Comparative Example 1. Additionally, FIG. 3 is a schematic diagram showing a cross-section of the wax filter, and FIG. 4 shows the average particle size and volume of wax separated in the first region of the wax filter of the example ( FIG. 4(1)), the average particle size and volume of wax separated in the second region ( FIG. 4(2)), and the average particle size and volume of wax separated in the third region ( FIG. 4(3)).
[0108] Classification Wax Filter Composition Wax Removal Rate (%) Wax Concentration of Solution 1 (wt%) Wax Concentration of Solution 3 (wt%) Fouling Presence Area 1 Area 2 Area 3 Example OOO 90 30.3X Comparative Example 1 XXX 0 33X Comparative Example 2 OXX 30 32.1X Comparative Example 3 OOO X 70 30.9X Comparative Example 4 XXX 90 30.3O
[0109] Referring to Table 1, in the example using a wax filter equipped with the first, second, and third regions, it can be confirmed that 90% of the wax contained in the first solution is removed, and the wax concentration of the third solution is 0.3 wt%. This means that even if the third solution is recovered and reused in the reactor, no fouling occurs in the process equipment. Additionally, Figure 4 shows the distribution of wax separated in each region based on the total wax (100 wt%) contained in the first solution in the example. In Figure 4 (3), the average size of the wax particles is 50 μm or larger and the volume of separation is moderate, whereas in Figure 4 (2), the average size of the wax particles is 15 μm to 50 μm and the volume of separated wax is the largest. This indicates that there are the most wax particles of medium size in the first solution. Furthermore, Figure 4 (1) shows that the average size of the wax particles is less than 15 μm, and the volume of separated wax decreases as the size is small and the amount is small.
[0110] On the other hand, in Comparative Examples 1 to 3, which use a wax filter that includes only a part of the first to third regions or do not use a wax filter at all, it can be observed that there are differences in the concentration of wax in the third solution and / or whether fouling occurs. In Comparative Examples 1 and 4, it can be observed that the wax concentration of the third solution is high and that fouling occurs within the wax separator. This means that when a wax filter that does not include the first region is used, the wax concentration of the first solution cannot be processed in the second and third regions, and consequently, fouling occurs within the wax separator. Furthermore, in Comparative Examples 2 and 3, no fouling occurs within the wax separator because wax with large particle sizes is primarily separated in the first region. However, in Comparative Examples 2 and 3, the wax concentration of the third solution is high, which may cause fouling in other parts of the equipment, such as the dryer and piping. Additionally, when comparing the comparative examples, it can be observed that the wax removal rate decreases as the composition of the wax filter decreases.
[0111] In addition, referring to Comparative Example 4, when the first solution is supplied directly to the third region without being supplied to the first region, there is no significant difference in the wax removal rate; however, since all the high-concentration wax contained in the first solution must be separated in the third region, fouling occurs within the wax separator and the wax removal efficiency may decrease. This demonstrates that wax can be separated most efficiently when the first, second, and third regions are used sequentially.
[0112] [Explanation of the symbol]
[0113] 100 reactors 200 separators
[0114] 300 Dryer 400 Wax Filter
[0115] 500 Refining Department
[0116] 10 case frames 20 solution supply ports
[0117] 30 Area 1 40 Area 2
[0118] 50 Area 3 60 Area 4
[0119] 70 solution outlet
Claims
1. A first step of introducing a feed comprising a monomer, a comonomer, and a solvent into a reactor to produce a reaction product comprising a polyolefin, a solvent, and a wax; A second step of supplying the above reaction product to a separator to separate it into a first solution containing a solvent and wax and a slurry containing a polyolefin in the separator, supplying the first stream containing the first solution to a wax filter, and supplying the slurry to a dryer; A third step of drying the slurry in the above dryer to obtain a polyolefin, condensing the gaseous component generated by the drying to prepare a second solution, and supplying the second solution to a purification unit; and A method for manufacturing a polyolefin comprising: a fourth step of supplying the first solution to a wax filter equipped with a plurality of inclined plates spaced apart at a certain interval to separate the wax into a third solution containing a solvent and a comonomer, wherein the third solution is discharged as a third stream, at least a portion of the third stream is recovered to the reactor, and the wax forms a highly concentrated wax and is discharged outside the system.
2. In Paragraph 1, The above wax filter is, A first region in which a plurality of first inclined plates are spaced apart with a spacing of L; A second region in which a plurality of second inclined plates are spaced apart with a spacing of 4L / 10 to 6L / 10; and A third region comprising a plurality of third inclined plates spaced apart with a spacing of 2L / 10 to 4L / 10; and The first solution passes sequentially through the first region, the second region, and the third region, and A method for manufacturing a polyolefin in which L is 40 mm to 60 mm.
3. In Paragraph 2, The inclination angle of the first inclined plate is 57˚ to 63˚ with respect to the lower surface of the wax filter, and The inclination angle of the second inclined plate is 52˚ to 57˚ with respect to the lower surface of the wax filter, and A method for manufacturing a polyolefin in which the inclination angle of the third inclined plate is 47˚ to 52˚ with respect to the lower surface of the wax filter.
4. In Paragraph 2, The average size of the highly concentrated wax particles separated in the first region is 50 μm or more to less than 100 μm, and The average size of the highly concentrated wax particles separated in the second region is 15 μm or more to less than 50 μm, and A method for producing a polyolefin in which the average size of the highly concentrated wax particles separated in the third region is 0.1 μm or more and less than 15 μm.
5. In Paragraph 1, The first solution is supplied to a solution supply port provided on one side of the upper part of the wax filter, and As the first solution flows from the bottom to the top of the first inclined plate, it is separated into the wax and the first region filtrate due to the difference in density, the first region filtrate flows to the top of the first inclined plate, and the wax flows to the bottom of the first inclined plate and is discharged through the first region wax outlet provided at the bottom of the first region. The first region filtrate is supplied to the upper part of the second region and flows from the lower part to the upper part of the second inclined plate, and is separated into the wax and the second region filtrate due to the difference in density, the second region filtrate flows to the upper part of the second inclined plate, and the wax flows to the lower part of the second inclined plate and is discharged through the second region wax outlet provided at the bottom of the second region. A method for manufacturing a polyolefin in which the filtered liquid of the second region is supplied to the upper part of the third region and flows from the lower part to the upper part of the third inclined plate, and is separated into the wax and the third solution by a difference in density, the third solution is discharged through a solution outlet provided at the lower part of the other side of the wax filter, and the wax flows from the upper part to the lower part of the third inclined plate and is discharged through a third region wax outlet provided at the lower part of the third region.
6. In Paragraph 1, A method for manufacturing a polyolefin in which the first solution is supplied to the wax filter at a flow rate of 0.5 mm / s to 1.5 mm / s.
7. In Paragraph 1, A method for manufacturing a polyolefin in which the above wax filter separates and discharges 80 wt% to 95 wt% of the wax contained in the first solution from the first solution.
8. In Paragraph 1, The above third stream is branched so that at least a portion is recovered to the reactor, and the remainder is supplied to the purification unit for the recovery of solvent and comonomer through the third-1 stream. A method for producing a polyolefin in which the flow rate branched from the flow rate of the third stream and supplied to the purification unit is 15 wt% to 25 wt% of the mass flow rate of the third stream.
9. In Paragraph 8, The above purification unit purifies the solution supplied from the second stream or the third-1 stream to separate the wax, comonomer, and solvent, and A method for producing a polyolefin in which a fourth solution containing the solvent and comonomer separated in the purification section is supplied to the reactor through a fourth stream, and the wax is discharged out of the system.
10. In Paragraph 1, The above polyolefin is high-density polyethylene (HDPE), and A method for manufacturing a polyolefin in which the monomer is ethylene.
11. A first region in which a first inclined plate having an inclination of 57˚ to 63˚ with respect to the lower surface of the wax filter is spaced apart by a distance of L; A second inclined plate having an inclination of 52˚ to 57˚ with respect to the lower surface of the wax filter, a second region spaced apart with a spacing of 4L / 10 to 6L / 10; and A third region comprising a third inclined plate having an inclination of 47˚ to 52˚ with respect to the lower surface of the wax filter, spaced apart with a spacing of 2L / 10 to 4L / 10; and A solution containing polyolefin wax sequentially passes through the first region, the second region, and the third region, wherein in the first region, highly concentrated wax having an average particle size of 50 μm or more and less than 100 μm is separated, in the second region, highly concentrated wax having an average particle size of 15 μm or more and less than 50 μm is separated, and in the third region, highly concentrated wax having an average particle size of 0.1 μm or more and less than 15 μm is separated. The above L is a polyolefin wax filter with a length of 40 mm to 60 mm.