Systems and techniques for heating polymer reactor flash line

Abstract

A polyolefin reactor flash line heater system may include a housing, a heating segment, and a transformer. The heating segment is contained within the housing and extends between a first end and a second end. The first end is fluidly coupled to a polyolefin reactor product inlet. The second end is fluidly coupled to a heated product outlet. One or more tube segments are coupled in series between the first end and the second end. The one or more tube segments are formed from an electrically conductive material and have a predetermined diameter to convey a polyolefin reactor flow from the first end to the second end. The transformer is electrically coupled to the first end and the second end and is configured to heat the heating segment by impedance heating. A polymerization system may include a polyolefin reactor coupled to the polyolefin reactor flash line heater system.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] none. Technical Field

[0003] The present disclosure relates to systems and techniques for polymerization, and in particular, to systems and techniques for heating polymer reactor flash lines. Background Art

[0004] Single reactor or multi-reactor system can be used to produce polymer resin, such as polyethylene. For example, a loop slurry reactor or a gas phase reactor can be used to produce polyethylene. The product stream collected from the polymerization system may include residual components, for example, hydrocarbons with polymer flakes or particles. The polymer particles can be separated from the residual hydrocarbons in a flash chamber (also referred to as a separation vessel or separation chamber). Before the product stream enters the flash chamber, the product stream is heated in a flash line steam with steam to vaporize the hydrocarbons.

[0005] There remains a need for new and improved systems and processes for heating a polymer reactor flash line to facilitate separation of polymer particles from residual components. 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 this Summary intended to limit the scope of the claimed subject matter.

[0007] In various aspects, the present disclosure describes a polyolefin reactor flash line heater system, the polyolefin reactor flash line heater system comprising a housing, a heating segment and a transformer. The housing defines a polyolefin reactor product inlet and a heated product outlet. The heating segment is contained within the housing and extends between a first end and a second end. The first end is fluidly coupled to the polyolefin reactor product inlet. The second end is fluidly coupled to the heated product outlet. The heating segment comprises one or more pipe segments coupled in series between the first end and the second end. The one or more pipe segments have a predetermined diameter to convey the polyolefin reactor product from the first end to the second end. The one or more pipe segments are formed of a conductive material. The transformer is electrically coupled to the first end and the second end and is configured to heat the heating segment by impedance heating of the one or more pipe segments.

[0008] In various aspects, the present disclosure describes a polymerization system including a polyolefin reactor having a reactor outlet and a polyolefin reactor flash line heater system. A reactor product inlet of the polyolefin reactor flash line heater system is coupled to the reactor outlet.

[0009] In various aspects, the present disclosure describes a technique for vaporizing hydrocarbons in a polyolefin product stream produced by a polymerization system. The technique includes flowing the polyolefin product stream from a reactor outlet through a polyolefin reactor flash line heater system. The technique further includes applying power to a corresponding heating segment by a corresponding transformer to generate impedance heating to the polyolefin product stream in the corresponding heating segment to reach a predetermined temperature high enough to vaporize at least a portion of the hydrocarbons in the polyolefin product stream.

[0010] This summary of the invention and the following detailed description provide examples and only explain 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

[0011] The following drawings form part of this disclosure and are included to further demonstrate certain aspects of the invention. The 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.

[0012] Figure 1A is a conceptual diagram showing a polyolefin reactor flash line heater system including a housing, a heating segment, and a transformer.

[0013] Figure 1B It is shown Figure 1A A conceptual diagram of multiple heating segments each comprising multiple pipe segments in a polyolefin reactor flash line heater system.

[0014] Figure 1C It is shown Figure 1A Conceptual illustration of a partial cross-section of an enclosure showing the insulation along the wall.

[0015] Figure 1D It is shown Figure 1A Conceptual illustration of a partial cross-section of an insulated pipe segment of a polyolefin reactor flash line heater system.

[0016] Figure 2 is a conceptual block diagram illustrating a polymerization system including a polyolefin reactor fluidly coupled to a flash line heater system.

[0017] Figure 3 is a flow chart illustrating a technique for operating a polymerization system including a polyolefin reactor fluidly coupled to a flash line heater system.

[0018] Although the invention disclosed herein is susceptible to various modifications and alternative forms, only a few specific aspects are shown 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 breadth or scope of the concept of the invention or the appended claims in any way. On the contrary, the drawings and detailed written description are provided to illustrate the inventive concept to a person of ordinary skill in the art and to enable such a person to make and use the inventive concept. DETAILED DESCRIPTION

[0019] 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.

[0020] definition

[0021] 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 Chemical Terminology (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.

[0022] Although compositions and techniques are described as "comprising" various components or steps, unless otherwise specified, the compositions and techniques may also "consist essentially of" or "consist of" the various components or steps.

[0023] The terms "a," "an," and "the" are intended to include plural alternatives, such as at least one. The terms "including," "with," and "having," as used herein, are defined as comprising (ie, open language) unless otherwise noted.

[0024] 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.

[0025] Values ​​or ranges may be expressed herein as "about", e.g., from "about" a particular value and / or to "about" another particular value. When such values ​​or ranges are expressed, other disclosed embodiments include the specific values ​​narrated, from a particular value and / or to another 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 particular 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.

[0026] 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.

[0027] For purposes of this disclosure, "polymer flakes" when used in the context of a product of a polymerization reactor refers to polymers in the form of powder, fluff, flakes, or the like that are typically produced by a polymerization reactor.

[0028] 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.

[0029] 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. None of the content herein is interpreted as admitting that the inventor is not qualified to precede such disclosures of existing inventions.

[0030] The present disclosure generally relates to systems and techniques for polymerization, and in particular, to systems and techniques for heating polymer reactor flash lines. Polymers can be produced by contacting one or more monomers with a catalyst in a polyolefin reactor. For example, polyethylene can be produced by contacting ethylene with a catalyst in a gas phase reactor or a loop slurry reactor. Polyolefin products, such as polyethylene in a slurry, can be taken out from the reactor and transferred to a flash chamber to separate polymers from residual components such as hydrocarbons. The pressure at which the flash chamber is located is lower than the pressure at which the polyolefin product is taken out from the reactor. The flash line is used to couple the reactor to the flash chamber. In order to promote substantially complete separation of the polymer particles in the flash chamber, the product stream is heated in the flash line to vaporize at least a portion of the residual components, such as substantially the entirety of the hydrocarbons.

[0031] A steam heating system may be used to heat the flash line. However, the use of steam requires the use of steam supply lines, condensate drain lines, and other equipment to generate and deliver the steam. The various steam supply lines and condensate drain lines may become water-logged or water-hammered to the extent that the heater may exhibit reduced functionality and provide insufficient heating.

[0032] In addition, heating needs to be adequately and reliably controlled so that the polyolefin product is not unacceptably modified by heating. For example, in order to keep the polymer in substantially solid particle or flake form and prevent aggregation or sticking, overheating above the softening point or melting point of the polyolefin product should preferably be avoided.

[0033] Systems and techniques according to the present disclosure provide flash line heating using electricity. For example, impedance-type electric heating can be used instead of steam heating to ensure that hydrocarbons are fully vaporized and do not melt or soften the polymer beyond an acceptable point.

[0034] Systems and techniques according to the present disclosure reduce or eliminate the need for steam equipment, including steam supply headers and condensate return headers that are susceptible to water hammer and flooding in flash line heater systems. Pipeline routing is also simplified because geometric constraints associated with the use of steam, such as minimum slope requirements for sub-headers, are no longer necessary limitations.

[0035] In various aspects, the present disclosure describes a polyolefin reactor flash line heater system, the polyolefin reactor flash line heater system comprising a housing, a heating segment and a transformer. The housing defines a polyolefin reactor product inlet and a heated product outlet. The heating segment is contained within the housing and extends between a first end and a second end. The first end is fluidly coupled to the polyolefin reactor product inlet. The second end is fluidly coupled to the heated product outlet. The heating segment comprises one or more pipe segments coupled in series between the first end and the second end. The one or more pipe segments have a predetermined diameter to convey the polyolefin reactor product from the first end to the second end. The one or more pipe segments are formed of a conductive material. The transformer is electrically coupled to the first end and the second end and is configured to heat the heating segment by impedance heating of the one or more pipe segments.

[0036] In various aspects, the present disclosure describes a polymerization system including a polyolefin reactor having a reactor outlet and a polyolefin reactor flash line heater system. A reactor product inlet of the polyolefin reactor flash line heater system is coupled to the reactor outlet.

[0037] In various aspects, the present disclosure describes a technique for vaporizing hydrocarbons in a polyolefin product stream produced by a polymerization system. The technique includes flowing the polyolefin product stream from a reactor outlet through a polyolefin reactor flash line heater system. The technique further includes applying power to a corresponding heating segment by a corresponding transformer to generate impedance heating to the polyolefin product stream in the corresponding heating segment to reach a predetermined temperature high enough to vaporize at least a portion of the hydrocarbons in the polyolefin product stream.

[0038] Figure 1A1 is a conceptual diagram showing a polyolefin reactor flash line heater system 10 including a housing 12, a heating segment 14, and a transformer 16. The housing 12 may house one or more components, such as a heating segment 14. In various aspects, the housing 12 may shield or isolate the external environment from the electricity flowing through the heating segment 14. The housing 12 may also facilitate maintaining a uniform or stable temperature of the heating segment 14, such as by at least partially shielding or isolating the heating segment 14 from temperature fluctuations of the external environment. The housing 12 may be formed by a wall 18. The wall 18 may be formed by any suitable material, such as a metal, alloy, ceramic, glass, or composite material. In some aspects, the housing 12 may be substantially continuous, for example, without defining any other inlet or outlet except those openings or windows associated with the inlet or outlet. In other aspects, the housing 12 may define an opening or window. In some aspects, the flash line heater system 10 may not include a separate housing 12, and the heating segment 14 may be enclosed in a housing associated with a reactor or another component. In some aspects, the flash line heater system 10 may not include any housing, and the heating segment 14 may be exposed to the surrounding environment.

[0039] The housing 12 can define a polyolefin reactor product inlet 20 and a heated product outlet 22. In some aspects, one or both of the polyolefin reactor product inlet 20 or the heated product outlet 22 can be a separate unit connected, coupled or fixed to the housing 12. The polyolefin product stream from the polyolefin reactor can be introduced into the polyolefin reactor flash line heater system 10 via the polyolefin reactor product inlet 20 for heating. For example, the polyolefin reactor flash line heater system 10 can heat the polyolefin product stream to form a heated product stream in which the residual hydrocarbons are at least partially or substantially vaporized. The heated product stream can leave the polyolefin reactor flash line heater system 10 via the heated product outlet 22 and be sent to the flash chamber for further processing. The vaporization of hydrocarbons in the polyolefin reactor flash line heater system 10 can promote or promote the substantially complete separation of polymer flakes or particles in the heated product stream and the residual hydrocarbons in the flash chamber. In some aspects, the product stream includes a slurry of polyolefin particles.

[0040] As the product stream passes through the polyolefin reactor flash line heater system 10, the pressure and / or temperature at the polyolefin reactor product inlet 20 will be different than the pressure and / or temperature at the heated product outlet 22. For example, there may be a pressure drop and a temperature increase at the heated product outlet 22 relative to the polyolefin reactor product inlet 20.

[0041] The heating segment 14 applies heat to the polyolefin product stream. The heating segment 14 is contained in the shell 12 and extends between the first end 24 and the second end 26. The first end 24 is fluidly connected to the polyolefin reactor product inlet 20, and the second end 26 is fluidly connected to the heated product outlet 22, for example, via corresponding pipe joints (piping). The pipe joint may include a single pipe segment or multiple pipe segments, and may be straight, curved, bent, or have any appropriate composite path. In some aspects, the first end 24 may extend to or otherwise directly connect to the polyolefin reactor product inlet 20. Similarly, in some aspects, the second end 26 may extend to or otherwise directly connect to the heated product outlet 22. In some aspects, the shell 12 may not define or be connected to one or both of the polyolefin reactor product inlet 20 or the heated product outlet 22. On the contrary, one or both of the first end 24 and the second end 26 may define or be fixed or connected to the polyolefin reactor product inlet 20 or the heated product outlet 22. In some such aspects, at least a portion of one or both of the first end 24 and the second end 26 can protrude from the interior to the exterior of the housing 12, and the protruding portion can define the polyolefin reactor product inlet 20 or the heated product outlet 22, respectively.

[0042] The heating segment 14 includes one or more tube segments (in series) connected between a first end 24 and a second end 26. Figure 1B ). In some aspects, one or more pipe sections extend between a first end 24 and a second end 26, and at least one of the one or more pipe sections can constitute a heating section 14. In some aspects, different sub-pluralities of pipe sections can constitute corresponding heating sections of multiple heating sections. The heating section 14 can be a single heating section, or one of a plurality of heating sections connected in any suitable combination of series or parallel heating sections. For example, in FIG. 1 , the polyolefin reactor flash pipeline heater system 10 can include a first heating section 14a, a second heating section 14b, and a third heating section 14c.

[0043] One or more pipe segments and ultimately, the heating segment 14 are heated by impedance heating. In impedance heating, there is no separate heating element, and the pipe segment itself generates heat via impedance to the power applied to the length of the pipe segment. One or more pipe segments are formed of a conductive material to permit impedance heating. In various aspects, the conductive material comprises a metal or alloy. In some aspects, the conductive material consists of or includes steel. In some such aspects, the conductive material comprises, consists of, or consists essentially of 304L stainless steel.

[0044] The transformer 16 is electrically coupled to the first end 24 and the second end 26 and is configured to heat the heating segment 14 by resistive heating of one or more pipe segments, for example, by applying a predetermined voltage to the heating segment 14. The same transformer 16 may power different heating segments, or different transformers may power different heating segments. Figure 1A As shown in FIG. 1 , the same transformer 16 can power the first heating segment 14a, the second heating segment 14b, and the third heating segment 14c by being coupled to the collective first end 24 and the second end 26 of the collective heating segment 14. In other aspects, one or more transformers can power one or more respective heating segments, such as being electrically coupled to respective ends of one or more heating segments 14a, 14b, 14c, etc.

[0045] The polyolefin reactor flash line heater system 10 may further include a power source 28 coupled to the transformer 16. If more than one transformer is present, the same power source 28 may power all of the transformers, or each transformer may be powered by a respective power source.

[0046] One or more tube segments may have a predetermined diameter to convey the polyolefin reactor product from the first end 24 to the second end 26. The diameter and length of the tube segments in the heating segment ultimately affect the flow rate through the heating segment 14 and the pressure drop across the heating segment. The geometry of the tube segments in the heating segment 14 may also affect the impedance heating characteristics of the heating segment 14. For example, a transformer may need to apply different voltages to the heating segment to achieve a predetermined heating level for different tube diameters and / or tube lengths. The heat input or temperature control to one or more tube segments or heating segments may be adjusted based on operating conditions and plant conditions.

[0047] Figure 1B It is shown Figure 1A 1. A conceptual diagram of a plurality of heating segments 14a, 14b and 14c, each comprising a plurality of pipe segments 30, in a polyolefin reactor flash line heater system 10. Each of the heating segments may include the same or different numbers of pipe segments. The pipe segments in the corresponding heating segments may have the same or different pipe diameters, pipe wall thicknesses and pipe lengths. For example, the pipe segment 14a includes two long pipe segments and one short pipe segment.

[0048] In various aspects, an adjacent pair of pipe segments 30a and 30b of the plurality of pipe segments are fluidly coupled by a U-bend 32 to form an undulate between the first end 24 and the second end 26. The U-bend 32 may have the same diameter as one or both of the adjacent pipe segments 30a and 30b, or may be narrower or wider than one or both of the adjacent pipe segments 30a and 30b. Figure 1B, the second heating segment 14b includes a pair of pipe segments 30a and 30b connected by a U-bend 32. The pipe segments of this pair of pipe segments 30a, 30b can be present in one or more heating segments. In some aspects, a pair of pipe segments 30a, 30b can extend across adjacent heating segments. For example, one of the pipe segments 30a and 30b can be part of the first heating segment 14a, and the other of the pipe segments 30a and 30b can be part of the second heating segment 14b.

[0049] In some aspects, the housing 12 further includes insulating material, for example, to reduce or minimize heat loss from the polyolefin reactor flash line heater system 10. The insulating material may be placed along or near the wall 18 of the housing or around the pipe segment 30.

[0050] Figure 1C It is shown Figure 1A 1. Conceptual illustration of a partial cross-section of a housing showing insulation layer 34 along wall 18. Figure 1D It is shown Figure 1A 1 , a conceptual diagram of a partial cross-section of an insulated pipe segment 30 of a polyolefin reactor flash line heater system, including a pipe wall 36 surrounded by an insulating layer 34. The insulating layer along either wall 18 or pipe wall 36 or both may be continuous or discontinuous and may be provided as separate patches or units, or as a substantially continuous layer. A system as described in aspect 6, wherein the insulating layer may include any suitable insulating material, such as glass or ceramic. In some aspects, the housing 12 is a rectangular parallelepiped (e.g., Figure 1A ), the cuboid has a thermal insulation layer 34, which is present on each inner surface of the housing 12. The thermal insulation layer 34 can surround the plurality of pipe segments 30, for example, surround each pipe segment, or surround selected pipe segments among the plurality of pipe segments 30. In some aspects, one or more U-bends 32 are also surrounded by the thermal insulation layer 34.

[0051] Back to Figure 1B, the first heating segment 14a may include a first plurality of tube segments. The first plurality of tube segments may each have the same predetermined first diameter. The transformer 16 may be a first transformer, and the system may further include a second transformer electrically coupled to the second heating segment 14b and configured to heat the second heating segment 14b by impedance heating of a second plurality of tube segments of the second heating segment. The second heating segment 14b enclosed in the housing 12 may be fluidically coupled to the first heating segment 14a. The second plurality of tube segments may have a second diameter that is greater than the first diameter of the first plurality of tube segments of the first heating segment 14a. In some aspects, the second transformer has a higher operating voltage than the first transformer. Therefore, for example, when the second diameter of the second plurality of tube segments of the second heating segment 14b is greater than the first diameter of the first plurality of tube segments of the first heating segment 14a, a voltage greater than the voltage applied to the first heating segment 14a may be applied to the second heating segment 14b.

[0052] In some aspects, adjacent heating segments can be electrically insulated from each other. For example, the first heating segment 14a can be electrically insulated from the second heating segment 14b and / or the second heating segment 14b can be electrically insulated from the third heating segment 14c. For example, when different voltages are applied to different heating segments, an electrical insulator 38 can be present between adjacent heating segments 14a and 14b and / or between heating segments 14b and 14c.

[0053] The electrical insulator 38 may be provided in any suitable shape, for example a plate, a disk, a cube, a cylinder or any suitable two-dimensional or three-dimensional shape. The electrical insulator 38 may include any suitable electrically insulating material, for example glass, ceramic or the like.

[0054] In some aspects, different sub-segments of the same heating segment can be heated by more than one transformer. In some such aspects, electrical insulators 38 can be present at intermediate locations along the heating segment (e.g., as shown in FIG. Figure 1A For example, the intermediate position may be located between two or more tube segments of the heating segment.

[0055] In some aspects, adjacent heating segments are coupled by one or more flow structures. For example, a first heating segment 14a may be fluidly coupled to a second heating segment 14b by a U-bend 32. Providing U-bends between heating segments or between pipe segments in a heating segment may promote the compactness of the housing 12 and the polyolefin reactor flash line heater system 10 as a whole. For example, various pipe segments and heating segments may form undulations to remain within a relatively compact volume in the housing 12 relative to the length of the unbent pipe segment or heating segment.

[0056] Pipe segments or heating segments with different diameters can be connected by an expander or a reducer. In various aspects, the system 10 further includes a first expander 40 that gradually expands from a first diameter of the first heating segment 14a to a second diameter of the second heating segment 14b (wherein the diameter of the second heating segment 14a is larger than the diameter of the first heating segment 14a).

[0057] The polyolefin reactor flash line heater system 10 may further include a third heating segment 14c enclosed in the housing 12 and fluidly coupled to the second heating segment 14b. The third heating segment 14c may include a third plurality of pipe segments. In some aspects, the third plurality of pipe segments have a third diameter greater than the second diameter of the second plurality of pipe segments 14b. In some aspects, the polyolefin reactor flash line heater system 10 may further include a third transformer, the third transformer being electrically coupled to the third heating segment 14c and configured to heat the third heating segment by impedance heating of the third plurality of pipe segments. In some such aspects, the third transformer has an operating voltage higher than that of the second transformer. Therefore, for example, when the third diameter of the third plurality of pipe segments of the third heating segment 14c is greater than the second diameter of the second plurality of pipe segments of the second heating segment 14b, a voltage greater than the voltage applied to the second heating segment 14b may be applied to the third heating segment 14c.

[0058] While one or more heating segments may include a corresponding plurality of tube segments, in other embodiments, one or more heating segments may include a single corresponding tube segment.

[0059] The third heating segment 14c may be electrically insulated from the second heating segment 14b. For example, an electrical insulator 38 may be present between the second heating segment 14b and the third heating segment 14c.

[0060] The third heating segment 14c can be fluidly coupled to the second heating segment 14b by a U-bend. In some aspects, the polyolefin reactor flash line heater system 10 further includes a second expander (similar to the first expander 40, but with appropriate input and output diameters) that gradually expands from the second diameter of the second heating segment 14b to the third diameter of the third heating segment 14c.

[0061] The polyolefin reactor flash line heater system 10 may include a sensor 42 to sense a process parameter. The sensor 42 may include a temperature sensor, a pressure sensor, a flow sensor, a hydrocarbon sensor, or any other sensor. For example, one or more corresponding heating segments 14 may include a corresponding sensor. One, more than one, or all heating segments may include a corresponding sensor. Similarly, one or more corresponding pipe segments may include a corresponding sensor.

[0062] The polyolefin reactor flash line heater system 10 may include a controller 44. The controller 44 may be configured to control at least one transformer 16 to heat at least one heating section 14 to a predetermined temperature high enough to vaporize the entirety of substantially hydrocarbons in the polyolefin product stream. In various aspects, the predetermined temperature is lower than the melting point of the polyolefin in the polyolefin product stream. In some such aspects, the predetermined temperature is lower than the softening point of the polyolefin in the polyolefin product stream.

[0063] Thus, the polyolefin reactor flash line heater system 10 may be used to heat a polyolefin product stream such that the hydrocarbons are at least partially, or preferably substantially completely, vaporized without negatively affecting the quality or properties of the polymer flakes or particles.

[0064] Figure 2 is a conceptual block diagram showing a polymerization system 50 including a polymer reactor 52, which is fluidly coupled to a polyolefin reactor flash line heater system 10. The flash line heater system is further coupled to a flash chamber 54. For example, a second end of the polyolefin reactor flash line heater system 10 is coupled to the flash chamber 54. A polyolefin product stream from the reactor 52 is introduced into the polyolefin reactor flash line heater system 10 for heating. For example, the polyolefin reactor 12 can be a polyolefin reactor having a reactor outlet, and a reactor product inlet 20 of the polyolefin reactor flash line heater system 10 is coupled to the reactor outlet. In some such aspects, the polyolefin product stream includes a polyolefin slurry comprising polyolefin particles and residual hydrocarbons.

[0065] The heated product stream from the flash line heater system 10 is introduced into the flash chamber 54 for separation. For example, the flash chamber 54 can be located downstream of the polyolefin reactor flash line heater system 10 and coupled to the heated product outlet 22 of the heater system. The pressure of the flash chamber 54 is generally lower than the pressure in the polyolefin reactor flash line heater system 10 or the polyolefin reactor 52, which promotes complete vaporization of the polymer particles or flakes and complete separation from the hydrocarbons. For example, polyolefins such as polyethylene can be separated from hydrocarbons.

[0066] In all aspects, Figure 1A Polyolefin reactor flash line heater system 10 or Figure 2 The polymerization system 50 can use reference Figure 3 However, these systems may be operated using any suitable technique according to the present disclosure. Although the systems and aspects are described with reference to polyethylene production, the systems and aspects may be used in other polymerization processes where flash line heating may be required.

[0067] Figure 3 is a flow chart illustrating a technique for operating a polymerization system 50 including a polyolefin reactor 52 fluidly coupled to a flash line heater system 12 for vaporizing hydrocarbons in a polyolefin slurry produced by the polymerization system. Figure 3 The technology is reference Figure 1A A polyolefin reactor flash line heater system 10 and Figure 2 The aggregation system 50 is described as an example and may alternatively be practiced using any suitable system in accordance with the present disclosure.

[0068] At step 60, the technique includes flowing the polyolefin product stream from the reactor outlet of the reactor 52 through the polyolefin reactor flash line heater system 12. In some aspects, flowing (60) includes flowing the polyolefin product stream from the reactor outlet through the polyolefin reactor flash line heater system 10 continuously.

[0069] Technology is further included in step 62, by corresponding transformer 16, electric power is applied to corresponding heating section 14, to produce impedance heating to polyolefin product stream in corresponding heating section 14, make it reach high enough to make the predetermined temperature of at least a portion of hydrocarbon vaporization in polyolefin product stream.In some respects, predetermined temperature is high enough to make the overall vaporization of hydrocarbon substantially in polyolefin product stream.In some respects, predetermined temperature is lower than the melting point of polyolefin in polyolefin product stream.In some respects, predetermined temperature is lower than the softening point of polyolefin in polyolefin product stream.Provide the temperature lower than softening point and can reduce or prevent the adhesion or aggregation of polyolefin particles.

[0070] In various aspects, the polyolefin is polyethylene, and wherein the hydrocarbon comprises one or more of isobutane, hexene, or ethylene.

[0071] The pressure is typically dropped from the reactor outlet through the polyolefin reactor flash line heater system 10. For example, the pressure at the reactor outlet can be 300 to 500 psig. In various aspects, the pressure at the heated product outlet can be less than 300 to 500 psig, such as about 150 psig.

[0072] Controller 44 may control one or both of steps 60 or 62, such as by permitting or stopping or controlling the rate at which the polyolefin product stream flows through the polyolefin reactor flash line heater system 10. For example, controller 44 may control one or more valves to control the flow of the polyolefin product stream.

[0073] In all aspects, Figure 3 The technique may further include sensing, by the controller 44, a temperature of the corresponding heating segment 14 at step 64. For example, the controller 44 may receive a signal indicating the temperature from the sensor. The technique may further include, by the controller, comparing the temperature to a set point at step 66. The technique may further include, by the controller, sending a control signal to the transformer 16 in response to the comparison to adjust the heating of the corresponding heating segment 14 at step 68. For example, sending a control signal to the transformer 16 by the controller 44 in response to the comparison (68) may cause the transformer 16 to do one or more of the following: (1) start heating of the corresponding heating segment 14, (2) increase heating thereof, (3) decrease heating thereof, (4) maintain heating thereof, or (5) stop heating thereof.

[0074] At step 70, Figure 3 The technique may further include flowing the heated product stream from the polyolefin flash line heater system 10 to a flash chamber 54, wherein the polyolefin particles or flakes may be substantially completely separated from the residual hydrocarbons by flashing.

[0075] Thus, systems and techniques according to the present disclosure may be used to electrically heat a flash line to facilitate complete separation of polymer from residual hydrocarbons in the flash chamber.

[0076] 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.

[0077] aspect

[0078] 1. A polyolefin reactor flash line heater system, the polyolefin reactor flash line heater system comprising:

[0079] a housing defining a polyolefin reactor product inlet and a heated product outlet;

[0080] a heating segment contained in the housing and extending between a first end fluidly coupled to the polyolefin reactor product inlet and a second end fluidly coupled to the heated product outlet, the heating segment comprising one or more tube segments coupled in series between the first end and the second end, the one or more tube segments having a predetermined diameter to convey the polyolefin reactor product from the first end to the second end, the one or more tube segments being formed of an electrically conductive material; and

[0081] A transformer is electrically coupled to the first end and the second end and is configured to heat the heating segment by resistive heating of the one or more tube segments.

[0082] 2. The system of claim 1, further comprising a power supply coupled to the transformer.

[0083] 3. The system of aspect 1 or 2, wherein an adjacent pair of the one or more pipe segments are fluidly connected by a U-bend to form an undulation between the first end and the second end.

[0084] 4. The system of any one of aspects 1 to 3, wherein the conductive material comprises steel.

[0085] 5. The system of any of aspects 1 to 4, wherein the conductive material consists of or consists essentially of 304L stainless steel.

[0086] 6. The system of any one of aspects 1 to 5, wherein the housing further comprises an insulation layer.

[0087] 7. The system of aspect 6, wherein the insulating layer comprises glass.

[0088] 8. The system of aspect 6 or 7, wherein the housing is a rectangular parallelepiped having the thermal insulation layer on each inner surface of the housing.

[0089] 9. The system of any of aspects 6 to 8, wherein the thermal insulation layer surrounds the one or more pipe segments.

[0090] 10. The system of any one of aspects 1 to 9, wherein the heating segment is a first heating segment, wherein the one or more tube segments include a first plurality of tube segments, wherein the predetermined diameter is a first predetermined diameter, wherein the transformer is a first transformer, and wherein the system further comprises:

[0091] a second heating segment enclosed within the housing and fluidly coupled to the first heating segment, the second heating segment comprising a second plurality of tube segments having a second diameter greater than the first diameter of the first plurality of tube segments; and

[0092] A second transformer is electrically coupled to the second heating segment and is configured to heat the second heating segment by resistive heating of the second plurality of tube segments.

[0093] 11. The system of aspect 10, wherein the second transformer has a higher operating voltage than the first transformer.

[0094] 12. The system of aspects 10 or 11, wherein the first heating segment is electrically insulated from the second heating segment.

[0095] 13. The system of any one of aspects 10 to 12, wherein the first heating segment is fluidly coupled to the second heating segment by a U-bend.

[0096] 14. The system of any one of aspects 10 to 13, wherein the system further comprises a first expander that gradually expands from the first diameter of the first heating segment to the second diameter of the second heating segment.

[0097] 15. The system of any one of aspects 10 to 14, wherein the system further comprises:

[0098] a third heating segment enclosed within the housing and fluidly coupled to the second heating segment, the third heating segment comprising a third plurality of tube segments having a third diameter greater than the second diameter of the second plurality of tube segments; and

[0099] A third transformer is electrically coupled to the third heating segment and is configured to heat the third heating segment by impedance heating of the third plurality of tube segments.

[0100] 16. The system of aspect 15, wherein the third transformer has a higher operating voltage than the second transformer.

[0101] 17. The system of aspects 15 or 16, wherein the third heating segment is electrically insulated from the second heating segment.

[0102] 18. The system of any one of aspects 15 to 17, wherein the third heating segment is fluidly coupled to the second heating segment by a U-bend.

[0103] 19. The system of any one of aspects 15 to 18, wherein the system further comprises a second expander that gradually expands from the second diameter of the second heating segment to the third diameter of the third heating segment.

[0104] 20. The system of any of aspects 1 to 19, wherein one or more respective heating segments comprise respective temperature sensors.

[0105] 21. The system of any of aspects 1 to 20, wherein one or more respective pipe segments comprise respective temperature sensors.

[0106] 22. The system of any one of aspects 1 to 21, further comprising a controller configured to control at least one transformer to heat at least one heating segment to a predetermined temperature high enough to vaporize substantially all of the hydrocarbons in the polyolefin product stream.

[0107] 23. The system of aspect 22, wherein the predetermined temperature is below the melting point of the polyolefin in the polyolefin product stream.

[0108] 24. The system of aspect 23, wherein the predetermined temperature is below a softening point of the polyolefin in the polyolefin product stream.

[0109] 25. A polymerization system, comprising:

[0110] a polyolefin reactor having a reactor outlet; and

[0111] The polyolefin reactor flash line heater system of any one of aspects 1 to 24, wherein the reactor product inlet of the polyolefin reactor flash line heater system is coupled to the reactor outlet.

[0112] 26. The polymerization system of aspect 25, further comprising a flash chamber located downstream of the polyolefin reactor flash line heater system and coupled to the heated product outlet of the heater system.

[0113] 27. A method of vaporizing hydrocarbons in a polyolefin product stream produced by the polymerization system of aspect 25 or 26, the method comprising:

[0114] flowing the polyolefin product stream from the reactor outlet through the polyolefin reactor flash line heater system; and

[0115] Power is applied by a respective transformer to a respective heating segment to resistively heat the polyolefin product stream in the respective heating segment to a predetermined temperature high enough to vaporize at least a portion of the hydrocarbons in the polyolefin product stream.

[0116] 28. The method of aspect 27, comprising continuously flowing the polyolefin product stream from the reactor outlet through the polyolefin reactor flash line heater system.

[0117] 29. The method of aspects 27 or 28, wherein the predetermined temperature is high enough to vaporize substantially all of the hydrocarbons in the polyolefin product stream.

[0118] 30. The method of any one of aspects 27 to 29, wherein the predetermined temperature is below the melting point of the polyolefin in the polyolefin product stream.

[0119] 31. The method of aspect 30, wherein the predetermined temperature is below a softening point of the polyolefin in the polyolefin product stream.

[0120] 32. The method of any one of aspects 27 to 31, wherein the polyolefin is polyethylene, and wherein the hydrocarbon comprises one or more of isobutane, hexene, or ethylene.

[0121] 33. The method of any one of aspects 27 to 32, wherein the pressure at the reactor outlet is 300 to 500 sig.

[0122] 34. The method of any one of aspects 27 to 33, wherein the pressure at the heated product outlet is about 150 psig.

[0123] 35. The method of any one of aspects 27 to 34, further comprising:

[0124] The controller senses the temperature of the corresponding heating segment;

[0125] comparing, by the controller, the temperature to a set point; and

[0126] A control signal is sent by the controller to the transformer in response to the comparison to adjust heating of the corresponding heating segment.

[0127] 36. The method of aspect 35, wherein sending the control signal by the controller to the transformer in response to the comparison causes the transformer to initiate heating of the corresponding heating segment.

[0128] 37. The method of aspects 35 or 36, wherein sending the control signal to the transformer by the controller in response to the comparison causes the transformer to increase heating of the corresponding heating segment.

[0129] 38. The method of aspects 35 to 37, wherein sending the control signal to the transformer by the controller in response to the comparison causes the transformer to reduce heating of the corresponding heating segment.

[0130] 39. The method of aspects 35 to 38, wherein sending the control signal to the transformer by the controller in response to the comparison causes the transformer to cease heating of the corresponding heating segment.

[0131] 40. The method of any one of aspects 27 to 39, wherein the polyolefin product stream comprises a polyolefin slurry.

Claims

1. A polyolefin reactor flash line heater system, the polyolefin reactor flash line heater system comprising: a housing defining a polyolefin reactor product inlet and a heated product outlet; a heating segment contained in the housing and extending between a first end fluidly coupled to the polyolefin reactor product inlet and a second end fluidly coupled to the heated product outlet, the heating segment comprising one or more tube segments coupled in series between the first end and the second end, the one or more tube segments having a predetermined diameter to convey the polyolefin reactor product from the first end to the second end, the one or more tube segments being formed of an electrically conductive material; as well as A transformer is electrically coupled to the first end and the second end and is configured to heat the heating segment by resistive heating of the one or more tube segments.

2. The system of claim 1, further comprising a power supply coupled to the transformer.

3. The system of claim 1, wherein an adjacent pair of the one or more pipe segments are fluidly coupled by a U-bend to undulate between the first end and the second end.

4. The system of claim 1, wherein the conductive material comprises steel.

5. The system of claim 1, wherein the housing further comprises an insulation layer.

6. The system of claim 5, wherein the insulating layer comprises glass.

7. The system of claim 5, wherein the housing is a rectangular parallelepiped having the thermal insulation layer on each inner surface of the housing.

8. The system of claim 1, wherein the heating segment is a first heating segment, wherein the one or more tube segments include a first plurality of tube segments, wherein the predetermined diameter is a first predetermined diameter, wherein the transformer is a first transformer, and wherein the system further comprises: a second heating segment enclosed within the housing and fluidly coupled to the first heating segment, the second heating segment comprising a second plurality of tube segments having a second diameter greater than the first diameter of the first plurality of tube segments; as well as A second transformer is electrically coupled to the second heating segment and is configured to heat the second heating segment by resistive heating of the second plurality of tube segments.

9. The system of claim 8, wherein the second transformer has a higher operating voltage than the first transformer.

10. The system of claim 8, wherein the system further comprises a first expander that gradually expands from the first diameter of the first heating segment to the second diameter of the second heating segment.

11. The system of claim 8, wherein the system further comprises: a third heating segment enclosed within the housing and fluidly coupled to the second heating segment, the third heating segment comprising a third plurality of tube segments having a third diameter greater than the second diameter of the second plurality of tube segments; as well as A third transformer is electrically coupled to the third heating segment and is configured to heat the third heating segment by impedance heating of the third plurality of tube segments.

12. The system of claim 11, wherein the third transformer has a higher operating voltage than the second transformer.

13. The system of claim 11, wherein the system further comprises a second expander that gradually expands from the second diameter of the second heating segment to the third diameter of the third heating segment.

14. The system of claim 1, wherein one or more respective heating segments include respective temperature sensors.

15. The system of claim 1, further comprising a controller configured to control at least one transformer to heat at least one heating segment to a predetermined temperature high enough to vaporize substantially all of the hydrocarbons in the polyolefin product stream.

16. The system of claim 15, wherein the predetermined temperature is below the melting point of the polyolefins in the polyolefin product stream.

17. A polymerization system, comprising: a polyolefin reactor having a reactor outlet; as well as The polyolefin reactor flash line heater system of claim 1, wherein the reactor product inlet of the polyolefin reactor flash line heater system is coupled to the reactor outlet.

18. The polymerization system of claim 17, further comprising a flash chamber located downstream of the polyolefin reactor flash line heater system and coupled to the heated product outlet of the heater system.

19. A method of vaporizing hydrocarbons in a polyolefin product stream produced by the polymerization system of claim 17, the method comprising: flowing the polyolefin product stream from the reactor outlet through the polyolefin reactor flash line heater system; as well as Power is applied by a respective transformer to a respective heating segment to produce resistive heating of the polyolefin product stream in the respective heating segment to a predetermined temperature high enough to vaporize at least a portion of the hydrocarbons in the polyolefin product stream.

20. The method of claim 19, wherein the predetermined temperature is high enough to vaporize substantially all of the hydrocarbons in the polyolefin product stream.

21. The method of claim 19, wherein the predetermined temperature is below the melting point of the polyolefins in the polyolefin product stream.

22. The method of claim 19, wherein the polyolefin is polyethylene, and wherein the hydrocarbon comprises one or more of isobutane, hexene, or ethylene.

23. The process of claim 19, wherein the pressure at the reactor outlet is 300 to 500 psig, and wherein the pressure at the heated product outlet is about 150 psig.

24. The method of claim 19, further comprising: The controller senses the temperature of the corresponding heating segment; comparing, by the controller, the temperature to a set point; as well as A control signal is sent by the controller to the transformer in response to the comparison to adjust heating of the corresponding heating segment.

25. The method of claim 24, wherein the controller sends the control signal to the transformer in response to the comparison, causing the transformer to perform one or more of the following: (1) start heating of the corresponding heating segment, (2) increase heating of the corresponding heating segment, (3) reduce heating of the corresponding heating segment, or (4) stop heating of the corresponding heating segment.

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