Systems and techniques for polymer degassing

Abstract

A purge system for a polymerization system may include a purge column including a stripping zone and a stripping fluid distributor below the stripping zone for injecting a stripping fluid comprising one or more light olefins. And the first replacement region is positioned below the distributor. The second displacement zone is located below the first displacement zone. A nitrogen distributor introduces nitrogen into the second displacement zone. Another purge system for a polymerization system may include a fluidized bed separator and a purge tower. The fluidized bed separator includes a separator inlet, a stripped fluid inlet, a first stripped fluid outlet, and a separator outlet. The purge column includes a sheet inlet, a stripping zone, a stripped fluid distributor located below the stripping zone, a stripped sheet outlet, and a second stripped fluid outlet for a second stripped fluid from the purge column.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] none. Technical Field

[0003] The present disclosure relates to systems and techniques for degassing polymers, and in particular, to systems and techniques for degassing polymer flakes produced by a polymerization system. Background Art

[0004] Single reactor or multi-reactor system can be used to produce polymer resin, such as polyethylene. For example, polyethylene can be produced using a loop slurry reactor or a gas phase reactor. In a gas phase reactor, residual gas may be present in the product stream collected from the polymerization system. For example, the product stream may include polymer flakes or powder with interstitial gas. The product stream can be degassed, for example, by passing nitrogen or light olefins through the polymer product to remove and reduce the residual gas from the reactor.

[0005] There remains a need for new and improved systems and processes for degassing polymer products to remove residual gases. Summary of the invention

[0006] This Summary is provided to introduce various concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify required or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter.

[0007] In various aspects, the present disclosure describes a purge system for a polymerization system. The purge system includes a purge tower, the purge tower including a sheet inlet for introducing a reactor product stream into a stripping zone of the purge tower. The reactor product stream comprises polymer flakes and one or more heavy hydrocarbons. The purge system further includes a stripping fluid distributor in the purge tower below the stripping zone, which is used to inject a stripping fluid comprising one or more light olefins into the stripping zone and is suitable for providing stripped polymer flakes. The purge system further includes a first displacement zone, which is located below the distributor and is configured to at least partially displace a first portion of the residual stripping fluid from the stripped polymer flakes received from the stripping zone. The purge system further includes a second displacement zone below the first displacement zone, which is configured to substantially displace a second portion of the residual stripping fluid from the stripped polymer flakes received from the first displacement zone. For example, after treatment in the second zone, no more than 10 ppmw, no more than 5 ppmw, no more than 2 ppmw, or no more than 0.5 ppmw of stripping fluid may be present in the stripped polymer flakes. The purge system further comprises a nitrogen distributor for introducing nitrogen into the second displacement zone. The purge system further comprises a stripped sheet outlet and a stripping fluid outlet.

[0008] In various aspects, the present disclosure describes a polymerization system including a polymerization reactor and a purge system.

[0009] In various aspects, the present disclosure describes a technique for operating a polymerization system including a polymerization reactor connected to a purge system. The technique includes contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in the polymerization reactor to form a reactor product comprising polymer flakes and residual heavy hydrocarbons. The technique further includes introducing the reactor product into a stripping zone of the purge system. The technique further includes stripping one or more heavy hydrocarbons from polymer flakes of the reactor product in the purge system by distributing a stripping fluid comprising one or more light olefins through the stripping zone to provide stripped polymer flakes. The technique further includes displacing the residual stripping fluid from the stripped polymer flakes in a first displacement zone and a second displacement zone by introducing nitrogen.

[0010] In various aspects, the present disclosure describes a purge system for a polymerization system, the purge system comprising a fluidized bed separator and a purge tower. The fluidized bed separator comprises a separator inlet for introducing a reactor product stream comprising polymer flakes and one or more heavy hydrocarbons into the fluidized bed. The fluidized bed separator further comprises a stripping fluid inlet for introducing a first stripping fluid into the fluidized bed. The fluidized bed separator further comprises a first stripped fluid outlet for a first stripped fluid from the fluidized bed. The fluidized bed separator further comprises a separator outlet for discharging stripped polymer flakes. The purge tower comprises a flake inlet for receiving stripped polymer flakes from the fluidized bed separator into a stripping zone of the purge tower. The purge tower further comprises a stripping fluid distributor located below the stripping zone for injecting a second stripping fluid comprising one or more light olefins into the stripping zone. The purge tower further comprises a stripped flake outlet, and a second stripped fluid outlet for a second stripped fluid from the purge tower.

[0011] In various aspects, the present disclosure describes a polymerization system that includes a polymerization reactor and a purge system that includes a fluidized bed reactor and a purge tower connected to the polymerization reactor.

[0012] In various aspects, the present disclosure describes a technique for operating a polymerization system, the polymerization system comprising a polymerization reactor connected to a purge system, the purge system comprising a fluidized bed reactor and a purge tower connected to the polymerization reactor. The technique includes contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in the polymerization reactor to form a reactor product comprising polymer flakes and residual heavy hydrocarbons. The technique further includes introducing the reactor product into a fluidized bed of a fluidized bed separator. The technique further includes stripping one or more heavy hydrocarbons from the polymer flakes of the reactor product by contacting the polymer flakes with a stripping fluid comprising one or more light olefins in the fluidized bed of the fluidized bed separator to provide stripped polymer flakes. The technique further includes introducing the stripped polymer flakes from the fluidized bed separator into the purge tower. The technique further includes stripping one or more heavy hydrocarbons from the stripped polymer flakes of the reactor product in the purge tower by distributing the stripping fluid through a stripping zone.

[0013] This summary of the invention and the following detailed description provide examples and are only explanations of the present disclosure. Therefore, the foregoing summary of the invention and the following detailed description should not be considered as restrictive. In addition to those set forth herein, additional features or variations thereof may be provided, such as various feature combinations and sub-combinations of these features described in the detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following drawings form part of this disclosure and are included to further illustrate certain aspects of the present invention. The present invention may be better understood by reference to one or more of these drawings in combination with the detailed description of specific embodiments presented herein.

[0015] Figure 1 is a conceptual diagram showing a polymerization system including a polymerization reactor fluidly connected to a purge system including a purge tower.

[0016] Figure 2 is a flow chart showing a technique for operating a polymerization system including a polymerization reactor fluidly connected to a purge system including a purge column.

[0017] Figure 3 is a conceptual diagram showing a polymerization system including a polymerization reactor fluidly connected to a purge system including a purge tower and a fluidized bed separator.

[0018] Figure 4 is a flow chart showing a technique for operating a polymerization system including a polymerization reactor fluidly connected to a purge system including a purge tower and a fluidized bed separator.

[0019] Although the invention disclosed herein is susceptible to various modifications and alternative forms, only a few specific aspects have been illustrated by way of example in the drawings and described in detail below. The drawings and detailed description of these specific aspects are not intended to limit the concept of the invention or the breadth or scope of the appended claims in any way. On the contrary, the drawings and detailed written description are provided to illustrate the concept of the invention to those of ordinary skill in the art and enable such persons to obtain and use the concept of the invention. DETAILED DESCRIPTION

[0020] It is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings.

[0021] definition

[0022] In order to more clearly define the terms used herein, the following definitions are provided. Unless otherwise indicated, the following definitions apply to the present disclosure. If a term is used in the present disclosure but is not specifically defined herein, the definition in the 2nd edition of IUPAC Compendium of Chemical Terminology (1997) can be applied, as long as the definition does not conflict with any other disclosure or definition applied herein, or does not make any claim to which the definition is applied unclear or invalid. If any definition or usage provided by any file incorporated herein by reference conflicts with the definition or usage provided herein, then the definition or usage provided herein shall prevail.

[0023] Although compositions and techniques are described as "comprising" various components or steps, unless otherwise stated, the compositions and techniques may also "consist essentially of" or "consist of" the various components or steps.

[0024] The terms "a / an" and "the" are intended to include multiple alternatives, for example, at least one. Unless otherwise indicated, the terms "including," "with," and "having" as used herein are defined as comprising (ie, open language).

[0025] Various numerical ranges are disclosed herein. When the applicant discloses or claims any type of range, unless otherwise indicated, the applicant's intent is to disclose or claim individually every possible number that such range can reasonably cover, including the endpoints of the range and any subranges and combinations of subranges covered therein. For example, all numerical endpoints of the ranges disclosed herein are approximate unless excluded by a proviso.

[0026] Values ​​or ranges may be expressed as "about" in this article, for example, from "about" a specific value and / or to "about" another specific value. When expressing such values ​​or ranges, other disclosed embodiments include the specific values ​​narrated, from the one specific value and / or to the other specific value. Similarly, when a value is expressed as an approximation by using the antecedent "about", it is understood that the specific value forms another embodiment. It is further understood that many values ​​are disclosed herein, and each value is also disclosed herein as "about" the specific value, in addition to the value itself. On the other hand, the use of the term "about" means ±20% of the value, ±15% of the value, ±10% of the value, ±5% of the value, ±3% of the value, or ±1% of the value.

[0027] Therefore, if the applicant chooses to claim less than the full measure disclosed for any reason (e.g., considering references that the applicant may not have known at the time of filing the application), the applicant reserves the right to exclude or exclude any individual member of the group of any such values ​​or ranges that may be claimed as a range or in any similar manner (including any subranges or combinations of subranges within the group). In addition, if the applicant chooses to claim less than the full measure disclosed for any reason (e.g., considering references that the applicant may not have known at the time of filing the present application), the applicant reserves the right to exclude or exclude any individual substituent, analog, compound, ligand, structure or group thereof, or any member of the claimed group.

[0028] For purposes of this disclosure, "polymer flakes" when used in the context of the product of a polymerization reactor refers to polymers in the form of powder, fluff, or flakes typically produced by a polymerization reactor.

[0029] For purposes of this disclosure, "light olefins" refer to olefins having two or three carbon atoms.

[0030] For purposes of this disclosure, "heavy hydrocarbons" refer to hydrocarbons having four or more carbon atoms.

[0031] Although any techniques and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, typical techniques and materials are described herein.

[0032] All publications and patents mentioned herein are incorporated herein by reference for describing and disclosing constructs and methods such as described in publications, which can be used in combination with the present invention as described herein. The publications discussed in full are provided only for their disclosures prior to the filing date of the present application. Any content of this article shall not be interpreted as admitting that the inventor has no right to enjoy the right prior to such disclosures due to prior inventions.

[0033] The present disclosure relates generally to systems and techniques for degassing polymers, and in particular, to systems and techniques for degassing polymer flakes produced by a polymerization system. For example, the polymerization system may include: a polymerization reactor configured to polymerize olefins to produce polyolefin flakes; and a purge system for degassing the polyolefin flakes to remove residual gas carried by the flakes from the polymerization reactor. The polymerization reactor may be a gas phase olefin polymerization reactor, and the residual gas may include heavy hydrocarbons.

[0034] One of the challenges of using gas phase reactors to increase polyolefin productivity comes from the capacity of conventional degassing systems. For example, the degassing system can use nitrogen to purge heavy hydrocarbon polymer flakes from the reactor, and then send the flakes to the finishing area for granulation and transportation. The nitrogen of saturated hydrocarbons can be sent to the compressor / refrigeration system to purify the nitrogen and recover the heavy hydrocarbons. As productivity increases and / or products with lower density are produced, the residence time in the degassing container and the amount of nitrogen used to purge the polymer flakes may limit the productivity of the polymer. In addition to these factors, conventional systems including multiple degassing containers may generate fouling in the pipelines or components within the container, for example, at the rotary feeder located between the degassing containers. This fouling may cause a reduction in productivity and cause the reactor to be shut down to clean the blades of the rotary feeder.

[0035] Instead of or in addition to nitrogen, light olefins may be used for degassing. For example, ethylene may be used as a stripping liquid for degassing the flakes in one or more degassing vessels. The light olefins may then be recycled to the reactor as monomers or comonomers for polymerization. However, during the degassing process, the light olefins themselves may be entrained to some extent in the polymer flakes.

[0036] The loss of light olefins in the polymer product can be reduced by systems and techniques according to the present disclosure. For example, a light olefin separation zone, a nitrogen replacement zone, and a final light olefin removal zone located below the main distributor for injecting light olefin stripping liquid can be used to reduce or minimize light olefin losses. In addition, a controller and a sensor can be used to monitor one or more of the light olefin or nitrogen concentration or pressure and flow distribution at one or more locations or sections in the purge system to reduce or minimize light olefin losses.

[0037] It has further been found that all or at least a portion of the light olefins used as a stripping fluid do not need to be pretreated to remove catalyst poisons prior to using (e.g., recycling) the light olefins for polymerization. For example, at least a portion of the catalyst poisons present in the light olefins can be reduced or removed by residual catalytic activity in the polymer flakes treated or degassed with the light olefins. Thus, the light olefins introduced or recycled to the reactor after use as a stripping fluid may exhibit reduced catalyst poisons or substantially no catalyst poisons.

[0038] In various aspects, the present disclosure describes a purge system for a polymerization system. The purge system includes a purge tower, the purge tower including a sheet inlet for introducing a reactor product stream into a stripping zone of the purge tower. The reactor product stream comprises polymer flakes and one or more heavy hydrocarbons. The purge system further includes a stripping fluid distributor in the purge tower below the stripping zone, which is used to inject a stripping fluid comprising one or more light olefins into the stripping zone and is suitable for providing stripped polymer flakes. The purge system further includes a first displacement zone, which is located below the distributor and is configured to at least partially displace a first portion of the residual stripping fluid from the stripped polymer flakes received from the stripping zone. The purge system further includes a second displacement zone below the first displacement zone, which is configured to substantially displace a second portion of the residual stripping fluid from the stripped polymer flakes received from the first displacement zone. The purge system further includes a nitrogen distributor for introducing nitrogen into the second displacement zone. The purge system further includes a stripped sheet outlet and a stripping fluid outlet.

[0039] In various aspects, the present disclosure describes a polymerization system including a polymerization reactor and a purge system.

[0040] In various aspects, the present disclosure describes a technique for operating a polymerization system including a polymerization reactor connected to a purge system. The technique includes contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in the polymerization reactor to form a reactor product comprising polymer flakes and residual heavy hydrocarbons. The technique further includes introducing the reactor product into a stripping zone of the purge system. The technique further includes stripping one or more heavy hydrocarbons from polymer flakes of the reactor product in the purge system by distributing a stripping fluid comprising one or more light olefins through the stripping zone to provide stripped polymer flakes. The technique further includes displacing the residual stripping fluid from the stripped polymer flakes in a first displacement zone and a second displacement zone by introducing nitrogen.

[0041] In some aspects, a fluidized bed may be used in addition to a purge tower to provide an initial flash for initial separation of gas and flakes from the reactor, as well as heating the flakes. A fluidized bed may also provide a height increase to reach the top of the purge tower, which may be helpful for gas phase processes where the bottom of the reactor is not significantly elevated.

[0042] In various aspects, the present disclosure describes a purge system for a polymerization system, the purge system comprising a fluidized bed separator and a purge tower. The fluidized bed separator comprises a separator inlet for introducing a reactor product stream comprising polymer flakes and one or more heavy hydrocarbons into the fluidized bed. The fluidized bed separator further comprises a stripping fluid inlet for introducing a first stripping fluid into the fluidized bed. The fluidized bed separator further comprises a first stripped fluid outlet for a first stripped fluid from the fluidized bed. The fluidized bed separator further comprises a separator outlet for discharging stripped polymer flakes. The purge tower comprises a flake inlet for receiving stripped polymer flakes from the fluidized bed separator into a stripping zone of the purge tower. The purge tower further comprises a stripping fluid distributor located below the stripping zone for injecting a second stripping fluid comprising one or more light olefins into the stripping zone. The purge tower further comprises a stripped flake outlet, and a second stripped fluid outlet for a second stripped fluid from the purge tower.

[0043] In various aspects, the present disclosure describes a polymerization system that includes a polymerization reactor and a purge system that includes a fluidized bed reactor and a purge tower connected to the polymerization reactor.

[0044] In various aspects, the present disclosure describes a technique for operating a polymerization system, the polymerization system comprising a polymerization reactor connected to a purge system, the purge system comprising a fluidized bed reactor and a purge tower connected to the polymerization reactor. The technique includes contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in the polymerization reactor to form a reactor product comprising polymer flakes and residual heavy hydrocarbons. The technique further includes introducing the reactor product into a fluidized bed of a fluidized bed separator. The technique further includes stripping one or more heavy hydrocarbons from the polymer flakes of the reactor product by contacting the polymer flakes with a stripping fluid comprising one or more light olefins in the fluidized bed of the fluidized bed separator to provide stripped polymer flakes. The technique further includes introducing the stripped polymer flakes from the fluidized bed separator into the purge tower. The technique further includes stripping one or more heavy hydrocarbons from the stripped polymer flakes of the reactor product in the purge tower by distributing the stripping fluid through a stripping zone.

[0045] Figure 1 is a conceptual diagram showing a polymerization system 10 that includes a polymerization reactor 12 fluidly connected to a purge system 14 that includes a purge column 16 .

[0046] The polymerization reactor polymerizes at least one monomer under the action of a catalyst to produce a polymer product. The polymer product may be in the form of a polymer powder or flakes. For example, at least one monomer may include an olefin, and the polymer product may include a polyolefin. In specific aspects, the olefin is ethylene, and the polyolefin is polyethylene.

[0047] Polymerization reactor 12 can be any reactor suitable for producing a polymer product. Typically, polymerization reactor 12 is operated continuously to produce a continuous stream of polymer product. In some aspects, polymerization reactor 12 is a gas phase reactor. In some aspects, polymerization reactor 12 is a fluidized bed gas phase reactor. In some aspects, polymerization reactor 12 is a liquid phase reactor. In some aspects, polymerization reactor 12 is a loop slurry reactor. Although Figure 1 A single polymerization reactor 12 is shown in FIG. 1 , but in other aspects, the polymerization reactor 12 can include more than one polymerization unit.

[0048] The polymer product (such as polymer flakes) produced by the polymerization reactor 12 may carry residual gas from the reactor 12. For example, one or more heavy hydrocarbons may be entrained or carried away from the reactor with the polymer product. Therefore, it may be necessary to reduce or remove the residual heavy hydrocarbons in the polymer product produced by the polymerization reactor 12.

[0049] In various aspects, the polymer product of residual gas or fluid (e.g., fluid including heavy hydrocarbons) is degassed or stripped using a purge system 14. The purge system 14 can be connected to the outlet of the reactor 12. In various aspects, the polymerization system 10 includes a product withdrawal system 18 that is fluidly connected to the outlet of the reactor 12, and the outlet of the product withdrawal system 18 is ultimately connected to the purge system 14. The product withdrawal system 18 can facilitate purification or densification of the polymer product stream produced by the polymerization reactor 12. The product withdrawal system can include any of the systems known to those skilled in the art that are suitable for transferring a reactor product stream to a degassing system (e.g., a circulating lock hopper system or a continuous output system).

[0050] In various aspects, the purge system 14 includes a purge tower 16. The purge tower may include a housing 20 and a lamella inlet 22 for introducing a reactor product stream in a product line 23 into a stripping zone 24 of the purge tower 16. The housing 20 may be substantially cylindrical in the main portion of the purge tower 16. The housing 20 may have a dome-shaped upper portion and a conical or partially conical lower portion, such as Figure 1 In some such aspects, flake inlet 22 is located at or near the top of purge column 16. The reactor product stream introduced into flake inlet 22 via product line 23 comprises polymer flakes and one or more heavy hydrocarbons.

[0051] The purge system may further include a stripping fluid distributor 26 located below the stripping zone 24 in the purge tower 16 for injecting a stripping fluid into the stripping zone. The stripping fluid may include one or more light olefins and is suitable for providing stripped polymer flakes. The stripping fluid may be introduced from a stripping fluid line 28 (e.g., located at or near the bottom of the purge tower 16). In various aspects, the stripping fluid distributor 26 is located at or near the bottom of the purge tower 16. For example, the stripping fluid distributor 26 may be located above the conical bottom portion of the shell 20 of the purge tower 20.

[0052] The stripping fluid distributor 26 may include one or more openings or nozzles, which may generally point upward to direct the stripping fluid toward the stripping zone above the stripping fluid distributor 26. The stripping fluid distributor 26 may include one or more plates, grids, pipes, pipe fittings or conduits to distribute the stripping fluid. In addition, the stripping fluid distributor 26 may be configured to allow polymer products (such as powders or flakes) to pass through, bypass or surround the stripping fluid distributor 26. For example, the stripping fluid distributor 26 may define a through passage, a through hole or a through opening. In some aspects, the stripping fluid distributor 26 may be arranged around the purge tower 16 or along the periphery of the purge tower, and not located in the central area of ​​the purge tower. In other aspects, the stripping fluid distributor 26 may be arranged at or near the center of the purge tower 16, and not located in the peripheral area of ​​the purge tower 16.

[0053] The purge system 14 may further include a first displacement zone I below the stripping fluid distributor 26. The first displacement zone I is configured to at least partially displace a first portion of the residual stripping fluid from the stripped polymer flakes received from the stripping zone 24. The first displacement zone I may serve as an olefin displacement zone, such as an ethylene displacement zone. Therefore, residual light olefins used as stripping fluid or in the stripping fluid may be displaced from the stripped polymer flakes received in the first displacement zone I. In various aspects, the first displacement zone I may displace ethylene while minimizing ethylene losses below the first displacement zone I, and reducing or minimizing the nitrogen volume of the displaced fluid from the first displacement zone I. Sufficient nitrogen may be introduced from below the first displacement zone to completely or almost completely displace interstitial ethylene from the stripped polymer flakes when the stripped polymer flakes move downward through the first displacement zone. Nitrogen may completely displace ethylene, while only a small amount or a very small amount of nitrogen moves upward into the first displacement zone I. The amount of nitrogen added may slightly exceed the interstitial gas movement rate in the region below the first displacement zone (e.g., in the second displacement zone). An appropriate power device (e.g., a compressor, fan, or blower) may be used to remove the displaced fluid from the first displacement zone I to control the pressure at the removal location to a target of minimizing the presence of nitrogen in the displaced fluid discharged from the first displacement zone I.

[0054] In various aspects, the first displacement zone I is defined by the purge tower 16 itself, e.g., as a lower portion or volume of the purge tower 16. In various aspects, the first displacement zone I is defined by a portion or volume of a displacement unit 30 connected to the purge tower 16. The displacement unit 30 can be permanently mechanically connected to the purge tower 16, e.g., located at or near the bottom of the purge tower 16. In other aspects, the displacement unit 30 is removably connected to the purge tower 16. In some aspects, the first displacement zone I is defined by an upper portion of the displacement unit 30. In some such aspects, the upper portion of the displacement unit 30 is a partial conical section with a narrow end oriented downward.

[0055] The purge system 14 may further include a second displacement zone II located below the first displacement zone I. The second displacement zone II is configured to substantially displace a second portion of the residual stripping fluid from the stripped polymer flakes received from the first displacement zone I. The second displacement zone II may function as a nitrogen displacement zone, for example, receiving nitrogen that ultimately displaces light olefins or residual stripping fluid from the stripped polymer flakes received in the second displacement zone. The second displacement zone II may function as a nitrogen displacement zone, for example, receiving nitrogen that ultimately displaces light olefins or residual stripping fluid from the stripped polymer flakes received in the second displacement zone.

[0056] In various aspects, the second displacement zone II is defined by the purge tower 16 itself, e.g., as a lower portion or volume of the purge tower 16, e.g., below the first displacement zone I. In other aspects, the second displacement zone II is defined by a portion or volume of the displacement unit 30. In some aspects, the second displacement zone I is defined by a portion of the displacement unit 30 that is located below the first displacement zone II. In some such aspects, both the first displacement zone I and the second displacement zone II are defined by the displacement unit 30. In other aspects, the first displacement zone I is defined by the purge tower 16, and the second displacement zone II is defined by the displacement unit 30. In some aspects, the portion of the displacement unit 30 that defines the second displacement zone II is a cylindrical section.

[0057] The purge system 14 may further include a nitrogen distributor 32 for introducing nitrogen into the second exchange zone II. The nitrogen distributor 32 may be an inlet or pipe connected to the lower portion of the purge tower 16 or to a portion of the exchange unit 30 that defines the second exchange zone II. In some aspects, the nitrogen distributor 32 has a similar construction and geometry as described with reference to the stripping fluid distributor 26. The nitrogen distributor 32 allows the polymer product received from the first exchange zone I to move downward or through the second exchange zone II. The nitrogen distributor 32 may receive nitrogen from a nitrogen line 33.

[0058] The purge system 14 further includes a stripped flake outlet 34 for distributing degassed or stripped polymer flakes received from the purge column 16 and / or the displacement unit 30 as a product stream in a product line 36. In various aspects, the stripped flake outlet 34 is connected to a take-off valve 38 for extracting the stripped polymer flakes from the purge column 16 (or ultimately from the purge system 14). The take-off valve 38 can be operated continuously as the polymerization and stripping of the polymer product proceeds. The take-off valve can be connected at or near the bottom of the purge column 16 (where all displacement zones are defined within the purge column 16), or at or near the bottom of the displacement unit 30 (where at least one displacement zone is defined by the displacement unit 30).

[0059] When the polymer product flows downward through the purge tower 16, the stripping fluid flows upward through the purge tower and collects the heavy hydrocarbons from the polymer flakes to strip the polymer flakes in the heavy hydrocarbons. The purge system 14 includes a stripping fluid outlet 40 to release the used stripping fluid from the purge tower 16. In various aspects, the stripping fluid outlet 40 is located at or near the top of the purge tower 16. For example, the stripping fluid outlet 40 can be located below the dome-shaped top of the shell 20 of the purge tower 16. Because the stripping fluid includes olefins that can be used for polymerization, a suitable power device 15 (e.g., a compressor) can be used to recycle the stripping fluid from the purge system 14 together with the heavy hydrocarbons after stripping back to the reactor 12. If a liquid is formed in the compression step, a pump can also be used to return it to the reactor.

[0060] The purge system 14 may include additional substitution zones. For example, the purge system 14 may further include the third substitution zone III below the second substitution zone II, which is used to substantially displace residual stripping fluid from the polymer flakes after stripping received from the second substitution zone II. The third substitution zone III may serve as a final olefin substitution zone, such as reducing, partially removing or substantially removing the residual light olefins in the polymer flakes received in the third substitution zone III. In some such aspects, the distributor 32 is a first nitrogen distributor, and the purge system 14 further includes a second nitrogen distributor 42, which is used to introduce nitrogen into the third substitution zone III. The second nitrogen distributor 42 may be similar to the first nitrogen distributor 32 described with reference to the second substitution zone II. In various aspects, relatively low flow nitrogen is introduced in the third substitution zone III to reduce, remove or substantially remove the final residual light olefins or stripping fluid in the interstitial gas leaving the second substitution zone. For example, the displacement at the top of the third substitution zone III may be controlled by one or both of a flow controller or a pressure controller. The amount of olefins (e.g., ethylene) in the fluid displaced from the third displacement zone III can be monitored and reduced or minimized by adjusting the nitrogen rate to the first nitrogen distributor 32. The concentration and amount of olefins in the interstitial gas accompanying the flakes discharged from the purge tower 16 can also be monitored.

[0061] In some aspects, the first exchange zone I, the second exchange zone II, and the third exchange zone III are defined in a single exchange unit 30 connected to the bottom of the purge tower. In other aspects, the first exchange zone I, the second exchange zone II, and the third exchange zone III are defined in separate units, for example, separate exchange units that are fluidly connected to each other. In some aspects, the first exchange zone I, the second exchange zone II, and the third exchange zone II are defined in a portion of the purge tower 16, for example, in a continuous lower portion of the purge tower 16.

[0062] In various aspects, the purge system 14 includes one or more outlets for discharging a displaced fluid, such as a fluid including residual stripping fluid. In some such aspects, the purge system 14 includes one or both of a first displacement outlet 44 connected to the first displacement zone I and a second displacement outlet 46 connected to the second displacement zone II for discharging the displaced fluid from the first displacement zone I and the second displacement zone II. The displaced fluid can be collected from the first displacement zone I and the second displacement zone II and transported in a displaced fluid pipeline 49.

[0063] The displaced fluid (including the residual stripping fluid from the first displacement zone I and / or the second displacement zone II) can be destroyed, for example, by treatment in a hydrocarbon destruction device 48. The hydrocarbon destruction device 48 can be configured to incinerate or otherwise destroy hydrocarbons (such as heavy hydrocarbons and / or residual light olefins displaced from the first displacement zone I or the second displacement zone II). The hydrocarbon destruction device 48 may include a flare. In various aspects, the purge system 14 includes a power device 50 (e.g., a compressor, a blower, or a fan) for conveying the displaced fluid to the hydrocarbon destruction device 48. Alternatively, the displaced fluid can be recovered using a suitable separation device known to those skilled in the art (e.g., a pressure oscillation absorption unit or a membrane separation unit).

[0064] The polymerization system 10 may include a controller 52 for controlling one or both of the polymerization reactor 12 or the purge system 14. The controller 52 may be electronically connected to one or more control elements in the polymerization system 10. For example, the purge system 14 may further include one or more of an olefin sensor, a nitrogen sensor, a flow sensor, or a pressure sensor located at one or more predetermined locations of the purge system 14. In various aspects, the controller 52 may send or receive signals to or from at least one sensor 54 (also referred to as an indicator), at least one control element 56, at least one valve 58, and at least one heater 60. The controller 52 may also send or receive signals to or from the reactor 12. The controller 52 may ultimately control one or both of the reactor 12 or the purge system 14, such as by using sensors to sense process conditions at one or more locations and actuating control elements to affect process conditions at one or more locations.

[0065] The at least one sensor 54 may include one, two, or more sensors for sensing one or more parameters or process conditions. For example, the at least one sensor 54 may include one or more of a pressure indicator ("PI"), a flow indicator ("FI"), an analytical indicator ("AI"), or a temperature indicator. The analytical indicator may include an indicator for a specific species, such as a nitrogen analytical indicator (in Figure 1 "N2" in the Figure 1 In various aspects, the olefin indicator comprises an ethylene indicator. The at least one control element 56 may comprise one or more of a pressure controller ("PC") or a flow controller ("FC").

[0066] One or more pipelines (such as, the input or output pipeline of purge system 14) may include one or more sensors or control elements, which may be present in the pipeline, or as a separate unit connected to the pipeline. For example, stripping fluid pipeline 33 may include one or both of valve 58 or heater 60. Nitrogen pipeline 33 may include one or more sensors 54 (e.g., pressure indicator), control element 56 (e.g., flow controller) and valve connected to the first branch of second displacement zone II. Nitrogen pipeline 33 may include one or both of control element 56 (e.g., flow controller) and valve connected to the second branch of third displacement zone III. Product pipeline 36 may include sensor (e.g., analysis indicator). The analysis indicator of product pipeline 36 may include olefin indicator, such as ethylene indicator. Displaced fluid pipeline 49 may include one or more of analysis indicator (e.g., nitrogen indicator), pressure controller, flow indicator and valve, which is located in the first branch of the fluid displaced from the first displacement zone I, or located in the second branch of the fluid displaced from the second displacement zone II.

[0067] The purge system 14 can be used to strip heavy hydrocarbons from the reactor product from the reactor 12 while reducing, minimizing, or substantially preventing the loss of stripping fluid or stripped light olefins. Figure 2 The described techniques are used to operate the purge system 14. However, any suitable technique according to the present disclosure may be used to operate the purge system 14.

[0068] Figure 2 is a flow chart showing a technique for operating a polymerization system 10 that includes a polymerization reactor 12 fluidly connected to a purge system 14 that includes a purge column 16 . Figure 2 The technology is reference Figure 1 The polymerization system 10 of the present invention is described as an example and can be practiced with another suitable system according to the present disclosure. At step 70, the technology includes contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in the polymerization reactor 12 to form a reactor product comprising polymer flakes and residual heavy hydrocarbons. The one or more heavy hydrocarbons may include one or more of 1-butene, 1-hexene, 1-octene, 1-decene, butane or pentane. The catalyst may include a Ziegler-Natta catalyst, a chromium-based catalyst, or a metallocene catalyst.

[0069] At step 72, the technique further includes introducing the reactor product into the stripping zone 24 of the purge system 14. At step 74, the technique includes stripping one or more heavy hydrocarbons from polymer flakes of the reactor product in the purge system 14 by distributing a stripping fluid comprising one or more light olefins through the stripping zone 24 to provide stripped polymer flakes.

[0070] In various fields, one or more olefin monomers used in the polymerization reaction include one or more light olefins for stripping reactor product. For example, after being used for stripping, one or more light olefins can be recycled to the reactor for polymerization as olefin monomers. In some such aspects, one or more olefin monomers are made up of or are substantially made up of one or more light olefins. In various fields, the stripping fluid is made up of or is substantially made up of ethylene. For example, one or more olefin monomers and one or more light olefins can be made up of ethylene or are substantially made up of it. Therefore, technology may include, at step 80, optionally further recycling one or more olefin monomers from the stripping fluid in stripping zone 24 to polymerization reactor 12.

[0071] At step 76, the technique further includes displacing the residual stripping fluid from the stripped polymer sheet by introducing nitrogen in the first displacement zone I and the second displacement zone II. In some aspects, displacing the residual stripping fluid from the stripped polymer sheet (76) includes introducing nitrogen into a first nitrogen inlet in the second displacement zone.

[0072] At step 78, the technique optionally further comprises introducing nitrogen into the third displacement zone III. In some aspects, displacing the residual stripping fluid from the stripped polymer sheet comprises introducing nitrogen into a second nitrogen inlet gas into the third displacement zone III.

[0073] Step 80 may be performed before, during, or after one or both of steps 76 or 78 .

[0074] Residual stripping fluid carried in the polymer flakes that descend below the stripping zone 24 can be reduced or removed from the purge system 14. For example, at step 82, the technology further includes discharging the residual stripping fluid in the first displacement zone I and the second displacement zone II from the polymerization system 14. In various aspects, the stripped polymer flakes in the first displacement zone I contain less than 25 ppmw of heavy hydrocarbons. In various aspects, the stripped polymer flakes in one or more of the first displacement zone I, the second displacement zone II, or the third displacement zone III contain less than 5 ppmw of stripping fluid. In various aspects, the stripped polymer flakes in the third displacement zone contain less than 2 ppmw of stripping fluid.

[0075] In various aspects, the light olefins (e.g., ethylene) used for stripping are not pretreated for catalyst poisons. In some such aspects, the catalyst poisons present in the light olefins are at least partially deactivated by contacting with the residual catalyst present in the polymer flakes in the purge system 14. For example, it is not necessary to add a catalyst killagent to the product stream received from the reactor 12 via the product line 23 in the purge system 14. In these cases, the amount of untreated olefins (e.g., ethylene) can be controlled by monitoring the polymer flake temperature in the purge tower 20, and if the temperature rises too much, the amount of untreated ethylene sent to the stripping zone is increased to reduce the temperature. In a system where the residual catalyst activity in the polymer flakes received from the reactor 12 is sufficient, the entire fresh ethylene feed stream entering the reactor can be contacted with the residual active catalyst in the stripping zone 24 with flakes, thereby fully removing poisons. Therefore, in some aspects, the treatment bed for removing poisons from the olefins (e.g., ethylene) or recycled hydrocarbons entering can be eliminated. For example, using a reactive polymer to remove poisons from some or all of the fresh light olefin (stripping fluid) feed can reduce, minimize or eliminate the need for light olefin processing beds.

[0076] Therefore, the polymerization system according to the present disclosure (including a polymerization reactor connected to a purge system (including a purge tower)) can be used to reduce or minimize the stripping fluid loss. The present disclosure also provides the use of a fluidized bed separator in combination with a purge tower, as shown in reference Figure 3 and Figure 4 as described.

[0077] Figure 3 1 is a conceptual diagram showing a polymerization system 100 including a polymerization reactor 102 fluidly connected to a purge system 104 including a purge column 106 and a fluidized bed separator 108. The configuration and operation of the polymerization reactor 102 may be similar to those of reference Figure 1 and Figure 2 The polymerization reactor 12 is substantially similar. The polymerization reactor 102 can produce a polymer product stream that is delivered to the purge system 104 via product line 103. The purge system 104 can include a recycle line 110 for recycling the stripped fluid from the purge system 104 to the polymerization reactor 102.

[0078] The fluidized bed separator 108 may be substantially cylindrical and have one or two dome-shaped ends. In various aspects, the fluidized bed separator 108 is formed by a relatively large diameter pipe. In various aspects, the fluidized bed separator 108 includes a separator inlet 112 for introducing a reactor product stream containing polymer flakes and one or more heavy hydrocarbons into a fluidized bed 114 in the fluidized bed separator 108. The fluidized bed separator 108 may further include a stripping fluid inlet 116 for introducing a first stripping fluid into the fluidized bed 114. The first stripping fluid may be introduced via one or both of a stripping fluid recycle line 118 or a fresh stripping fluid line 120. The first stripping fluid may be heated. In some aspects, the purge system 104 includes a heater 121 for heating the stripping fluid introduced into the fluidized bed separator 108. In some aspects, the heater 121 may exist along the recycle line 118 or the fresh stripping fluid line 120. In some aspects, multiple heaters may be positioned along the same stripping fluid supply or recirculation line or along different stripping fluid supply or recirculation lines.

[0079] The fluidized bed separator 108 may further include a first stripped fluid outlet 122 for discharging a first stripped fluid from the fluidized bed 114. For example, a stripping fluid introduced through the stripping fluid inlet 116 may pass through the fluidized bed 114 and strip polymer flakes present in the fluidized bed 114 and exit the fluidized bed 114 as a stripped fluid through the stripped fluid outlet 122. The fluidized bed separator 108 may further include a separator outlet 124 for discharging stripped polymer flakes from, for example, the fluidized bed 114. In various aspects, the separator inlet 112 and the stripping fluid inlet 116 may be located at or near the bottom of the fluidized bed separator 108. In some such aspects, the stripping fluid inlet 116 is located at the bottom of the fluidized bed separator 108, and the separator inlet 112 is located near the bottom of the stripping fluid inlet 116 and above it. In various aspects, the stripping fluid outlet 122 and the separator outlet 124 can be located at or near the top of the fluidized bed separator 108. For example, the stripped fluid outlet 122 can be located at the top of the fluidized bed separator 108, and the separator outlet 124 is located near the top of or below the stripped fluid outlet. Thus, in some aspects, both the polymer flakes and the stripping fluid can rise and pass through the fluidized bed 114, such that the stripping fluid can strip the polymer flakes in the fluidized bed 114.

[0080] In various aspects, the fluidized bed separator 108 can include an expanded section at the top, for example, above one or both of the fluidized bed 114 and the separator outlet 124 for discharging the stripped polymer flakes. The expanded section can reduce the amount of fines entrained in the gas exiting the top of the fluidized bed separator 108.

[0081] The purge tower 106 can be compared with the reference Figure 1 and Figure 2 The purge tower 16 is generally similar. In various aspects, the purge tower 106 includes a sheet inlet 126 for receiving the stripped polymer sheets from the fluidized bed separator 108 into a stripping zone 128 of the purge tower 106. The purge tower may include a stripping fluid distributor 130 located below the stripping zone 128 for injecting a second stripping fluid comprising one or more light olefins into the stripping zone. In some aspects, the stripping fluid distributor 130 is located near the bottom of the purge tower 106. For example, the stripping fluid distributor 130 may be located above the conical bottom portion of the purge tower 106.

[0082] In various aspects, the system 100 may include a power plant 129 (eg, a compressor) for delivering fluid from the fluidized bed separator 114 or from another component to the reactor 102 .

[0083] The second stripping fluid may be delivered to the stripping fluid distributor via the second fresh stripping fluid line 132. The purge column 106 may further include a stripped flake outlet 134. The stripped flake outlet 134 may distribute the degassed or stripped polymer flakes received from the purge column 106 as a product stream in a product line 136. In various aspects, the stripped flake outlet 134 is connected to an output valve 138 for extracting the stripped polymer flakes from the purge column 106 (or ultimately from the purge system 104).

[0084] The purge column includes a second stripped fluid outlet 140 for a second stripped fluid from the purge column 106. Thus, polymer flakes can descend through the stripping zone 128 in the purge column 106 while the stripping fluid ascends through the stripping zone 128 to strip heavy hydrocarbons in the polymer flakes. In various aspects, the flake inlet 126 is located near or at the top of the purge column.

[0085] In some aspects, the fluidized bed separator 108 can be partially or completely located above the purge tower 106. For example, at least a portion of the fluidized bed separator 108 can be located above the top of the purge tower 106. In some aspects, the separator outlet 124 of the fluidized bed separator 108 is located above the top of the purge tower 106. In some aspects, the separator outlet 124 of the fluidized bed separator 108 is located above the separator inlet 126 of the fluidized bed separator 106. Such a configuration can facilitate the flow or transport of polymer flakes exiting the fluidized bed separator 108 for further processing in the purge tower 106. Thus, the purge tower 106 and the fluidized bed separator 108 can strip the polymer flakes continuously or in series.

[0086] In some aspects, the purge system 104 further includes an auxiliary separation unit (e.g., a separation unit including a cyclone separator or a filter) to process the stripped fluid and return any polymer flakes that may escape with the stripped fluid to the purge system 104. For example, the separation unit 144 can be connected to the stripped fluid outlet 140 of the purge tower 108. Similarly, the separation unit 146 can be connected to the stripped fluid outlet 122 of the fluidized bed separator 108. The separated polymer flakes from these auxiliary separation units can be returned to one or both of the purge tower 106 or the fluidized bed separator 108.

[0087] One or more power devices may be used to drive flow in one or more lines or portions of the polymerization system 100 or the purge system 104. For example, the purge system 104 may include a power device 148 (e.g., a compressor, blower, or fan) to maintain a recirculated stripping fluid flow through the fluidized bed separator 108.

[0088] In some aspects, the purge system 104 further includes a purge unit 142 including a poison scavenger composition for treating the stripping fluid introduced into the fluidized bed separator 108. The poison scavenger composition may include at least one component capable of neutralizing or mitigating catalyst poisons that may be present in the stripping fluid.

[0089] although Figure 3 Not shown, the polymerization system 100 may also include a controller, one or more sensors, and one or more control elements, similar to those described with reference to the polymerization system 10 .

[0090] Thus, the purge system 104 can be used to strip heavy hydrocarbons from the reactor product from the reactor 102 while reducing, minimizing, or substantially preventing the loss of stripping fluid or stripped light olefins. Figure 4 However, the purge system 104 may be operated using any suitable technique consistent with the present disclosure.

[0091] Figure 4 is a flow chart showing a technique for operating a polymerization system 100 that includes a polymerization reactor 102 fluidly connected to a purge system 104 that includes a purge column 106 and a fluidized bed separator 108 . Figure 4 The technology is reference Figure 3The polymerization system 100 is described as an example and can be practiced alternatively with another suitable system according to the present disclosure. At step 160, the technology includes contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in the polymerization reactor 102 to form a reactor product comprising polymer flakes and residual heavy hydrocarbons. The one or more heavy hydrocarbons may include one or more of 1-butene, 1-hexene, 1-octene, 1-decene, butane or pentane. The catalyst may include a Ziegler-Natta catalyst, a chromium-based catalyst or a metallocene catalyst.

[0092] At step 162, the technique includes introducing the reactor product into the fluidized bed 114 of the fluidized bed separator 108. At step 164, the technique includes stripping one or more heavy hydrocarbons from the polymer flakes of the reactor product in the fluidized bed 114 of the fluidized bed separator 108 by contacting the polymer flakes with a stripping fluid comprising one or more light olefins to provide stripped polymer flakes. In some aspects, the one or more olefin monomers include one or more light olefins. For example, the light olefins may be suitable for use as monomers in the polymerization reactor 102 and, after being used to strip the polymer flakes, may be transported to the polymerization reactor 102.

[0093] At step 166, the technique includes introducing the stripped polymer flakes from the fluidized bed separator 108 into the purge column 106. At step 168, the technique includes stripping one or more heavy hydrocarbons from the polymer flakes of the reactor product in the purge column 106 by distributing a second stripping fluid through the stripping zone 128 of the purge column 106. The second stripping fluid may include one or more light olefins. The second stripping fluid may be different from the stripping fluid used in the fluidized bed.

[0094] In some aspects, one or more olefin monomers are made up of or substantially made up of one or more light olefins. For example, the same olefin that can be used as a stripping fluid may also be used to prepare a polymer product. In some aspects, one or more light olefins are identical to one or more olefin monomers. In some aspects, one or more olefin monomers and one or more light olefins are made up of ethylene or substantially made up of it. In some aspects, the stripping fluid is made up of or substantially made up of ethylene. In some aspects, ethylene is not pretreated for catalyst poisons, and the catalyst poisons present in the ethylene are at least partially deactivated by contacting with the residual catalyst present in the polymer flakes in the purge system 104. If a poison treatment bed is not used, a small amount of poison scavenger (such as a diluted aluminum alkyl or an aluminum alkyl supported on a solid) can be added to the fluidizing gas fed to the fluidized bed 114 as needed to control the residual activity.

[0095] The use of a fluidized bed or plug fluidized bed in combination with a purge column allows any residual catalytic activity in the polymer to be fully dispersed in the treatment of catalyst poisons that may be present in the stripping fluid. The use of a fluidized bed also allows the flakes discharged from the polymerization reactor 102 to be reheated to a higher temperature to improve downstream stripping. For example, the temperature of the flakes may decrease after being removed from the polymerization reactor 102 and depressurized and the hydrocarbons absorbed into the flakes in the polymerization reactor 102 are devolatilized. In various aspects, the flakes may be heated or cooled to a temperature that substantially matches the reactor temperature or to a temperature that is 10°F higher than the reactor temperature in the fluidized bed separator.

[0096] In various aspects, the technology optionally includes step 170 of further recycling one or more olefin monomers of the stripping fluid from one or both of the fluidized bed 114 of the fluidized bed separator 108 or the stripping zone 128 of the purge tower 106 to the polymerization reactor 102 using an appropriate power device 129 (e.g., a compressor).

[0097] Therefore, according to Figure 4 The technology can be used to reduce or minimize the heavy hydrocarbons in the polymer flakes, while also reducing or minimizing the stripping fluid loss. In various aspects, the stripped polymer flakes in the stripping flake outlet 134 of the purge tower 106 contain less than 25 ppm of heavy hydrocarbons.

[0098] Combining the fluidized bed separator 108 with the purge tower 106 can provide further advantages. For example, the fluidized bed 114 can provide initial flashing to perform preliminary separation and heating of the gas and flakes from the polymerization reactor 102, and provide height increase to reach the top of the purge tower 106. For example, in a gas phase polyolefin process, the bottom of the polymerization reactor 102 may not rise significantly, and additional equipment may otherwise be required to transport the flakes from the bottom of the polymerization reactor 102 or an outlet near the top of the purge tower 106. In addition, the fluidized bed separator can be designed to accept all olefins (e.g., ethylene) flows required to maintain productivity (if necessary), and provide heat input for the flakes during the initial flashing. For example, the fluidized bed 114 can replace the flash gas pipeline or the loose (fluff) flash gas pipeline for the loop slurry process. In this way, the temperature can be returned to the reactor polymerization temperature in the fluidized bed separator 108, such as to offset the temperature drop that may occur during the initial flashing and stripping. The fluidized bed 114 may also be operated at a higher pressure than the purge column 106, or at approximately the same pressure.

[0099] The present invention is described above with reference to multiple aspects and embodiments and specific examples. Based on the above specific embodiments, many variations will occur to those skilled in the art. All such obvious variations are within the full expected scope of the appended claims. Other aspects of the present invention may include, but are not limited to, the following aspects. Many aspects are described as "comprising" certain components or steps, but alternatively, unless otherwise specifically stated, can be "essentially composed of" or "consisting of" those components or steps.

[0100] aspect

[0101] Aspect 1. A purge system for a polymerization system, the purge system comprising:

[0102] a purge column comprising a flake inlet for introducing a reactor product stream comprising polymer flakes and one or more heavy hydrocarbons into a stripping zone of the purge column;

[0103] a stripping fluid distributor located in the purge column below the stripping zone, for injecting a stripping fluid comprising one or more light olefins into the stripping zone and adapted to provide stripped polymer flakes;

[0104] a first displacement zone located below the distributor and configured to at least partially displace a first portion of residual stripping fluid from the stripped polymer sheet received from the stripping zone;

[0105] a second displacement zone located below the first displacement zone and configured to substantially displace a second portion of the residual stripping fluid from the stripped polymer sheet received from the first displacement zone;

[0106] a nitrogen distributor for introducing nitrogen into the second displacement zone;

[0107] an outlet for stripped flakes; and

[0108] Stripping fluid outlet.

[0109] Aspect 2. The purge system according to aspect 1, wherein the nitrogen distributor is a first nitrogen distributor, and the purge system further comprises:

[0110] a third displacement zone located below the second displacement zone for substantially displacing residual stripping fluid from the stripped polymer sheet received from the second displacement zone; and

[0111] A second nitrogen distributor is used to introduce nitrogen into the third substitution zone.

[0112] Aspect 3. The purge system according to aspect 2, wherein the first displacement zone, the second displacement zone, and the third displacement zone are defined in a single displacement unit connected to the bottom of the purge tower.

[0113] Aspect 4. The purge system of aspect 2, wherein the first displacement zone, the second displacement zone, and the third displacement zone are defined in separate units.

[0114] Aspect 5. The purge system according to any one of aspects 1 to 4, further comprising an output valve connected to the stripped flake outlet for extracting the stripped polymer flakes from the purge tower.

[0115] Aspect 6. The purge system as described in any one of Aspects 1 to 5, further comprising a first displacement outlet connected to the first displacement zone and a second displacement outlet connected to the second displacement zone for discharging displaced fluid from the first displacement zone and the second displacement zone.

[0116] Aspect 7. The purge system as described in any one of aspects 1 to 6, further comprising one or more of an olefin sensor, a nitrogen sensor, a flow sensor or a pressure sensor located at one or more predetermined locations of the purge system.

[0117] Aspect 8. The purge system according to any one of aspects 1 to 7, further comprising a hydrocarbon destruction device configured to eliminate hydrocarbons in the fluid displaced from the first displacement zone or the second displacement zone.

[0118] Aspect 9. The purge system of any one of aspects 1 to 8, wherein the sheet inlet is located at or near the top of the purge tower.

[0119] Aspect 10. The purge system according to any one of aspects 1 to 9, wherein the stripping fluid distributor is located at or near the bottom of the purge tower.

[0120] Aspect 11. A polymerization system comprising:

[0121] a polymerization reactor; and

[0122] The purge system of any one of aspects 1 to 10, connected to the polymerization reactor.

[0123] Aspect 12. The polymerization system according to aspect 11, wherein the polymerization reactor is a gas phase reactor.

[0124] Aspect 13. The polymerization system according to aspect 12, wherein the polymerization reactor is a fluidized bed gas phase reactor.

[0125] Aspect 14. The polymerization system according to aspect 11, wherein the polymerization reactor is a liquid phase reactor.

[0126] Aspect 15. The polymerization system according to aspect 11, wherein the polymerization reactor is a loop slurry reactor.

[0127] Aspect 16. A technique for operating a polymerization system, the polymerization system comprising a polymerization reactor connected to a purge system as described in any one of aspects 1 to 10, the technique comprising:

[0128] contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in a polymerization reactor to form a reactor product comprising polymer flakes and residual heavy hydrocarbons;

[0129] introducing the reactor product into the stripping zone of the purge system;

[0130] stripping the one or more heavy hydrocarbons from the polymer flakes of the reactor product in the purge system by distributing a stripping fluid comprising one or more light olefins through the stripping zone to provide a stripped polymer flake; and

[0131] Residual stripping fluid is displaced from the stripped polymer sheet in the first displacement zone and the second displacement zone by introducing nitrogen.

[0132] Aspect 17. The technology of aspect 16, wherein displacing residual stripping fluid from the stripped polymer sheet comprises introducing nitrogen into the first nitrogen inlet in the second displacement zone.

[0133] Aspect 18. The technology of aspect 16 or 17, further comprising introducing nitrogen into the third substitution zone.

[0134] Aspect 19. The technology of aspect 18, wherein displacing residual stripping fluid from the stripped polymer sheet comprises introducing nitrogen into the second nitrogen inlet in the third displacement zone.

[0135] Aspect 20. The technology of any one of aspects 16 to 19, wherein the one or more olefin monomers include the one or more light olefins.

[0136] Aspect 21. The technology of aspect 20, wherein the one or more olefin monomers consist of or consist essentially of the one or more light olefins.

[0137] Aspect 22. The technology of any one of aspects 16 to 21, further comprising recycling the one or more olefin monomers from the stripping fluid in the stripping zone to the polymerization reactor.

[0138] Aspect 23. The technology of any one of aspects 16 to 22, further comprising discharging the one or more heavy hydrocarbons from the stripping fluid in the first displacement zone and the second displacement zone of the polymerization system.

[0139] Aspect 24. The technology of any one of aspects 16 to 23, wherein the stripping fluid consists of or consists essentially of ethylene.

[0140] Aspect 25. The technology of aspect 24, wherein the ethylene is not pretreated for catalyst poisons, and wherein catalyst poisons present in the ethylene are at least partially deactivated by contact with residual catalyst present in the polymer sheet in the purge system.

[0141] Aspect 26. The technology of any one of aspects 16 to 25, wherein the one or more heavy hydrocarbons include one or more of 1-butene, 1-hexene, 1-octene, 1-decene, butane, or pentane.

[0142] Aspect 27. The technology of any one of aspects 16 to 26, wherein the catalyst comprises a Ziegler-Natta catalyst, a chromium-based catalyst, or a metallocene catalyst.

[0143] Aspect 28. The technology of any one of aspects 17 to 27, wherein the stripped polymer flakes in the first displacement zone contain less than 25 ppmw of the heavy hydrocarbons.

[0144] Aspect 29. The technology of any one of aspects 17 to 28, wherein the stripped polymer flakes in one or more of the first displacement zone, the second displacement zone, or the third displacement zone contain less than 5 ppmw of the stripping fluid.

[0145] Aspect 30. The technology of any one of aspects 19 to 29, wherein the stripped polymer flakes in the third displacement zone contain less than 2 ppmw of the stripping fluid.

[0146] Aspect 31. A purge system for a polymerization system, the purge system comprising:

[0147] A fluidized bed separator comprising:

[0148] a separator inlet for introducing a reactor product stream comprising polymer flakes and one or more heavy hydrocarbons into the fluidized bed;

[0149] a stripping fluid inlet for introducing a first stripping fluid into the fluidized bed,

[0150] a first stripped fluid outlet for a first stripped fluid from the fluidized bed,

[0151] a separator outlet for discharging the stripped polymer flakes; and

[0152] A purge tower comprising:

[0153] a flake inlet for receiving the stripped polymer flakes from the fluidized bed separator into the stripping zone of the purge column,

[0154] a stripping fluid distributor located below the stripping zone for injecting a second stripping fluid comprising one or more light olefins into the stripping zone,

[0155] The stripped flakes outlet, and

[0156] A second stripped fluid outlet is provided for a second stripped fluid from the purge column.

[0157] Aspect 32. The purge system of aspect 31, further comprising an output valve connected to the stripped flake outlet for extracting the stripped polymer flakes from the purge tower.

[0158] Aspect 33. The purge system of aspect 31 or 32, wherein the sheet inlet is located near the top of the purge tower.

[0159] Aspect 34. The purge system of any one of Aspects 31 to 33, wherein the separator outlet of the fluidized bed separator is located above or above the top of the sheet inlet of the purge tower.

[0160] Aspect 35. The purge system of any one of Aspects 31 to 34, wherein the separator outlet is located above the separator inlet of the fluidized bed separator.

[0161] Aspect 36. The purge system of any one of Aspects 31 to 35, wherein the stripping fluid distributor is located near the bottom of the purge tower.

[0162] Aspect 37. The purge system of any one of aspects 31 to 36, further comprising a heater for heating the stripping fluid introduced into the fluidized bed separator.

[0163] Aspect 38. The purge system of aspect 37, wherein the heater is configured to return the temperature of the flakes exiting the fluidized bed separator to within 10° F. of the polymerization temperature of the polymerization reactor.

[0164] Aspect 39. The purge system according to any one of aspects 31 to 38, wherein the purge tower according to aspect 1 further comprises:

[0165] a first displacement zone located below the distributor and configured to at least partially displace a first portion of residual stripping fluid from the stripped polymer sheet received from the stripping zone;

[0166] a second displacement zone located below the first displacement zone and configured to substantially displace a second portion of the residual stripping fluid from the stripped polymer sheet received from the first displacement zone; and

[0167] A third displacement zone is disposed below the second displacement zone and is configured to substantially displace residual stripping fluid from the stripped polymer sheet received from the second displacement zone.

[0168] Aspect 40. The purge system according to any one of aspects 31 to 39, further comprising a removal unit comprising a poison scavenger composition for treating a stripping liquid introduced into the fluidized bed separator.

[0169] Aspect 41. A polymerization system comprising:

[0170] a polymerization reactor; and

[0171] The purge system of any one of Aspects 31 to 40, connected to the polymerization reactor.

[0172] Aspect 42. The polymerization system according to aspect 41, further comprising a recycle line for recycling the stripped fluid from the purge system to the polymerization reactor.

[0173] Aspect 43. A technique for operating a polymerization system, the polymerization system comprising a polymerization reactor connected to a purge system as described in any one of aspects 31 to 42, the technique comprising:

[0174] contacting one or more olefin monomers with a catalyst in the presence of one or more heavy hydrocarbons in the polymerization reactor to form a reactor product comprising polymer flakes and residual heavy hydrocarbons;

[0175] introducing the reactor product into the fluidized bed of the fluidized bed separator;

[0176] stripping the one or more heavy hydrocarbons from the polymer flakes of the reactor product in the fluidized bed of the fluidized bed separator by contacting the polymer flakes with a stripping fluid comprising one or more light olefins to provide stripped polymer flakes;

[0177] introducing the stripped polymer flakes from the fluidized bed separator into the purge column; and

[0178] The one or more heavy hydrocarbons are stripped from the stripped polymer flakes of the reactor product in the purge column by distributing the stripping fluid through the stripping zone.

[0179] Aspect 44. The technology of aspect 43, wherein the one or more olefin monomers include the one or more light olefins.

[0180] Aspect 45. The technology of aspect 44, wherein the one or more olefin monomers consist of or consist essentially of the one or more light olefins.

[0181] Aspect 46. The technology as described in any of Aspects 43 to 45, further comprising recycling the one or more light olefins of the stripping fluid from one or both of the fluidized bed of the fluidized bed separator or the stripping zone of the purge tower to the polymerization reactor.

[0182] Aspect 47. The technology of any one of Aspects 43 to 46, wherein the stripping fluid consists of or consists essentially of ethylene.

[0183] Aspect 48. The technology of aspect 47, wherein the ethylene is not pretreated for catalyst poisons, and wherein catalyst poisons present in the ethylene are at least partially deactivated by contact with residual catalyst present in the polymer sheet in the purge system.

[0184] Aspect 49. The technology of any one of aspects 43 to 48, wherein the one or more heavy hydrocarbons include one or more of 1-butene, 1-hexene, 1-octene, 1-decene, butane, or pentane.

[0185] Aspect 50. The technology of any one of aspects 43 to 49, wherein the catalyst comprises a Ziegler-Natta catalyst, a chromium-based catalyst, or a metallocene catalyst.

[0186] Aspect 51. The technology of any one of aspects 43 to 50, wherein the stripped polymer flakes in the stripped flake outlet of the purge column comprises less than 25 ppmw of the heavy hydrocarbons.

Claims

1. A cleaning system for a polymerization system, the cleaning system comprising: a purge column including a flake inlet for introducing a reactor product stream comprising polymer flakes and one or more heavy hydrocarbons into a stripping zone of the purge column; a stripping fluid distributor located in the purge column below the stripping zone for injecting a stripping fluid comprising one or more light olefins into the stripping zone and adapted to provide stripped polymer flakes; a first displacement zone located below the distributor and configured to at least partially displace a first portion of the stripping fluid remaining in the stripped polymer sheet received from the stripping zone; a second displacement zone disposed below the first displacement zone and configured to substantially displace a second portion of the residual exfoliation fluid in the exfoliated polymer sheet received from the first displacement zone; a nitrogen distributor, used to introduce nitrogen into the second replacement zone; a peel sheet outlet; and Stripping fluid outlet.

2. The purge system according to claim 1, wherein the nitrogen distributor is a first nitrogen distributor, and the purge system further comprises: a third displacement zone located below the second displacement zone for substantially displacing the stripping liquid remaining in the stripped polymer sheet received from the second displacement zone; as well as The second nitrogen distributor is used to introduce nitrogen into the third replacement zone. 3 . The cleaning system according to claim 2 , wherein the first displacement zone, the second displacement zone, and the third displacement zone are defined in a single displacement unit connected to the bottom of the cleaning tower.

4. The cleaning system according to claim 1, further comprising: a first displacement outlet connected to the first displacement zone; and a second displacement outlet connected to the second displacement region for discharging the displaced fluid from the first displacement region and the second displacement region.

5. The cleaning system of claim 1, further comprising one or more of an olefin sensor, a nitrogen sensor, a flow sensor, or a pressure sensor located at one or more predetermined locations of the cleaning system.

6. The cleaning system of claim 1, wherein the sheet inlet is located at or adjacent to the top of the cleaning tower.

7. The cleaning system of claim 1, wherein the stripping fluid distributor is located at or adjacent to the bottom of the cleaning tower.

8. A polymerization system, comprising: a polymerization reactor; and The cleaning system according to claim 1, which is connected to a polymerization reactor.

9. The polymerization system according to claim 8, wherein the polymerization reactor is a fluidized bed gas phase reactor, a liquid phase reactor or a loop slurry reactor.

10. A method of operating a polymerization system comprising a polymerization reactor connected to the cleaning system of claim 1, the method comprising: contacting one or more olefin monomers with a catalyst in a polymerization reactor in the presence of one or more heavy hydrocarbons to form a reactor product comprising polymer flakes and residual heavy hydrocarbons; introducing the reactor product into the stripping zone of the cleaning system; stripping one or more heavy hydrocarbons from polymer flakes of a reactor product in a purge system by distributing a stripping fluid comprising one or more light olefins into a stripping zone to provide a stripped polymer flake; and The residual stripping liquid is displaced from the stripped polymer sheet by introducing nitrogen gas into the first displacement zone and the second displacement zone.

11. The method of claim 10, further comprising introducing nitrogen gas into the third displacement zone.

12. The method of claim 10, wherein the one or more olefin monomers comprise one or more light olefins.

13. The method of claim 12, wherein the one or more olefin monomers consist of or consist essentially of the one or more light olefins.

14. The process of claim 10, further comprising recycling the one or more olefin monomers of the stripping fluid from the stripping zone to the polymerization reactor.

15. The method of claim 10, wherein the stripping fluid consists of or consists essentially of ethylene.

16. The process of claim 15, wherein the ethylene is not pretreated for catalyst poisons and wherein catalyst poisons present in the ethylene are at least partially deactivated by contact with residual catalyst present in the polymer flakes in the washing system.

17. The method of claim 10, wherein the one or more heavy hydrocarbons include one or more of 1-butene, 1-hexene, 1-octene, 1-decene, butane, or pentane.

18. The method of claim 10, wherein the exfoliated polymer flakes in the first displacement zone contain less than 25 ppmw of heavy hydrocarbons.

19. The method of claim 11, wherein the exfoliated polymer sheet in one or more of the first displacement zone, the second displacement zone, or the third displacement zone comprises less than 5 ppmw of the exfoliation fluid.

20. The method of claim 19, wherein the exfoliated polymer sheet in the third displacement zone contains less than 2 ppmw of the stripping solution.

21. A cleaning system for a polymerization system, the cleaning system comprising: Fluidized bed separator, comprising: a separator inlet for introducing a reactor product stream comprising polymer flakes and one or more heavy hydrocarbons into the fluidized bed, a stripping fluid inlet for introducing a first stripping fluid into the fluidized bed, a first stripping fluid outlet for a first stripping fluid from the fluidized bed, a separator outlet for discharging the exfoliated polymer flakes; and Cleaning tower, including: a flake inlet for receiving stripped polymer flakes from the fluidized bed separator into the stripping zone of the washing tower, a stripping fluid distributor located below the stripping zone for injecting a second stripping fluid comprising one or more light olefins into the stripping zone, peel sheet outlet, and A second stripping fluid outlet is provided for a second stripping fluid from the wash column.

22. The cleaning system of claim 21, wherein the sheet inlet is adjacent to the top of the cleaning tower.

23. The cleaning system of claim 21, wherein a separator outlet of the fluidized bed separator is located above a separator inlet of the fluidized bed separator and above a sheet inlet of the cleaning tower.

24. The purge system of claim 21, wherein the stripping fluid distributor is adjacent to a bottom of the purge tower.

25. A polymerization system consisting of: Polymerization reactor; and The cleaning system according to claim 21, which is connected to a polymerization reactor.

26. The polymerization system according to claim 25, wherein the polymerization reactor is a fluidized bed gas phase reactor, a liquid phase reactor or a loop slurry reactor.

27. The polymerization system of claim 25, further comprising a recycle line for recycling the stripping fluid from the purge system to the polymerization reactor.

28. A method of operating a polymerization system comprising a polymerization reactor coupled to the cleaning system of claim 21, the method comprising: contacting one or more olefin monomers with a catalyst in a polymerization reactor in the presence of one or more heavy hydrocarbons to form a reactor product comprising polymer flakes and residual heavy hydrocarbons; introducing the reactor product into a fluidized bed of a fluidized bed separator; stripping one or more heavy hydrocarbons from polymer flakes of a reactor product by contacting the polymer flakes with a stripping fluid comprising one or more light olefins in a fluidized bed of a fluidized bed separator to provide stripped polymer flakes; introducing polymer flakes peeled off in the fluidized bed separator into a washing tower; as well as One or more heavy hydrocarbons are stripped from the stripped polymer flakes of the reactor product in the purge column by distributing a stripping fluid into the stripping zone.

29. The method of claim 28, wherein the one or more olefin monomers comprise one or more light olefins.

30. The method of claim 28, wherein the one or more olefin monomers consist of or consist essentially of the one or more light olefins.

31. The process of claim 28, further comprising recycling one or more light olefins from the stripping fluid in one or both of the fluidized bed of the fluidized bed separator or the stripping zone of the purge column to the polymerization reactor.

32. The method of claim 28, wherein the stripping fluid consists of or consists essentially of ethylene.

33. The process of claim 28, wherein the ethylene is not pretreated for catalyst poisons and wherein catalyst poisons present in the ethylene are at least partially deactivated by contact with residual catalyst present in the polymer flakes in the cleaning system.

34. The method of claim 28, wherein the one or more heavy hydrocarbons include one or more of 1-butene, 1-hexene, 1-octene, 1-decene, butane, or pentane.

35. The method of claim 28, wherein: The stripped polymer flakes in the stripped flake outlet of the purge column contain less than 25 ppmw of heavy hydrocarbons.

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