Systems and methods for polyethylene recovery with low volatile content

{
  "publication_number": "US10774161B2",
  "country": "US",
  "kind": "B2",
  "title": "Systems and methods for polyethylene recovery with low volatile content",
  "abstract": "The present invention discloses methods for removing volatile components from an ethylene polymer effluent stream from a polymerization reactor, and related polyethylene recovery and volatile removal systems. In these methods and systems, the polymer solids temperature is increased significantly prior to introduction of the polymer solids into a purge column for the final stripping of volatile components from the polymer solids.",
  "claims": [
    "1. A method for removing volatile components from an ethylene polymer effluent stream from an ethylene polymerization reactor, the method comprising: (i) reducing a pressure of the effluent stream to remove a first portion of the volatile components from polymer solids, the polymer solids having a solids temperature from about 10° F. to about 50° F. less than a reaction temperature in the ethylene polymerization reactor; (ii) fluidizing the polymer solids while heating to increase the solids temperature from at least about 10° F. above the solids temperature in step (i) and up to about 20° F. greater than the reaction temperature, and wherein a second portion of the volatile components are removed; and (iii) contacting the polymer solids with a stripping gas to remove a third portion of the volatile components to form a polymer solids stream containing less than 100 ppm by weight (ppmw) of volatile components.",
    "2. The method of claim 1, wherein the ethylene polymerization reactor is a gas phase reactor, and wherein: a volatile content of the ethylene polymer effluent stream is from about 5 to about 25 wt. % volatile components; the pressure in step (i) is reduced to a range from about 2 to about 10 psig; the polymer solids contain from about 0.5 to about 5 wt. % volatile components in step (i) after the first portion of volatile components is removed; the solids temperature in step (i) is from about 10° F. to about 20° F. less than the reaction temperature; and the solids temperature in step (ii) is from at least about 15° F. above the solids temperature in step (i) and up to about 15° F. greater than the reaction temperature.",
    "3. The method of claim 1, wherein the ethylene polymerization reactor is a loop slurry reactor, and wherein: a volatile content of the ethylene polymer effluent stream is from about 35 to about 75 wt. % volatile components; the pressure in step (i) is reduced to a range from about 2 to about 200 psig; the polymer solids contain from about 0.5 to about 10 wt. % volatile components in step (i) after the first portion of volatile components is removed; the solids temperature in step (i) is from about 30° F. to about 50° F. less than the reaction temperature; and the solids temperature in step (ii) is from at least about 15° F. above the solids temperature in step (i) and up to about 15° F. greater than the reaction temperature.",
    "4. The method of claim 1, wherein the polymer solids are fluidized in step (ii) with a fluidizing gas having a temperature from about 10° F. less than to about 20° F. greater than the reaction temperature.",
    "5. The method of claim 4, wherein step (ii) is conducted for a time period in a range from about 1 to about 30 minutes.",
    "6. The method of claim 1, wherein the polymer solids stream contains less than about 40 ppmw of volatile components.",
    "7. The method of claim 1, wherein: the stripping gas further comprises a catalyst deactivating agent; the polymer solids are fluidized in step (ii) with a fluidizing gas that further comprises a catalyst deactivating agent; or the method further comprises a step of introducing a catalyst deactivating agent into the polymer solids stream after step (iii).",
    "8. An ethylene polymerization process comprising: prior to conducting the method for removing volatile components from the ethylene polymer effluent stream of claim 1, contacting a catalyst composition with ethylene and an optional olefin comonomer in the ethylene polymerization reactor under polymerization reaction conditions in a polymerization reactor system to produce the ethylene polymer effluent stream.",
    "9. A method for removing volatile components from an ethylene polymer effluent stream from an ethylene polymerization reactor, the method comprising: (I) contacting the effluent stream with a fluidizing gas at a reduced pressure while heating to remove an initial portion of the volatile components from polymer solids, the polymer solids having a solids temperature from about 30° F. less to about 20° F. greater than a reaction temperature in the ethylene polymerization reactor; and (II) contacting the polymer solids with a stripping gas to remove a final portion of the volatile components to form a polymer solids stream containing less than 100 ppm by weight of volatile components.",
    "10. A polyethylene recovery and volatile removal system comprising: (a) a flash chamber for reducing a pressure of an ethylene polymer effluent stream from an ethylene polymerization reactor and for removing a first portion of volatile components from polymer solids, wherein the flash chamber is configured to form the polymer solids at a solids temperature from about 10° F. to about 50° F. less than a reaction temperature in the ethylene polymerization reactor; (b) a fluidized bed heater for fluidizing the polymer solids and for heating the polymer solids to a solids temperature from at least about 10° F. above the solids temperature in (a) and up to about 20° F. greater than the reaction temperature, wherein the fluidized bed heater is configured to remove a second portion of the volatile components; and (c) a purge column for contacting the polymer solids with a stripping gas, wherein the purge column is configured to remove a third portion of the volatile components to form a polymer solids stream containing less than 100 ppmw (ppm by weight) of volatile components.",
    "11. The system of claim 10, wherein: the system further comprises an extruder for converting the polymer solids stream into solid polymer pellets; and the purge column is configured to form the polymer solids stream containing less than about 40 ppmw of volatile components.",
    "12. The system of claim 10, wherein the system further comprises: an injector for introducing a catalyst deactivating agent into the ethylene polymer effluent stream prior to the flash chamber; or an injector for introducing a catalyst deactivating agent into the polymer solids stream after the purge column.",
    "13. The system of claim 10, wherein: the fluidized bed heater is further configured to fluidize the polymer solids with a fluidizing gas comprising a catalyst deactivating agent and at least one of nitrogen, ethylene, flash chamber gas, or a combination thereof; or the purge column is further configured to contact the polymer solids with the stripping gas and a catalyst deactivating agent.",
    "14. The system of claim 10, wherein the ethylene polymerization reactor is a gas phase reactor, and wherein: a volatile content of the ethylene polymer effluent stream is from about 5 to about 25 wt. % volatile components; the flash chamber is configured to reduce the pressure to from about 2 to about 10 psig; the flash chamber is configured to form the polymer solids at a solids temperature from about 10° F. to about 20° F. less than the reaction temperature; the flash chamber is further configured to form the polymer solids containing from about 0.5 to about 5 wt. % volatile components; and the fluidized bed heater is configured to heat the polymer solids to a solids temperature from at least about 15° F. above the solids temperature in the flash chamber and up to about 15° F. greater than the reaction temperature.",
    "15. The system of claim 10, wherein the ethylene polymerization reactor is a loop slurry reactor, and wherein: a volatile content of the ethylene polymer effluent stream is from about 35 to about 70 wt. % volatile components; the flash chamber is configured to reduce the pressure to from about 2 to about 200 psig; the flash chamber is configured to form the polymer solids at a solids temperature from about 30° F. to about 50° F. less than the reaction temperature; the flash chamber is further configured to form the polymer solids containing from about 0.5 to about 10 wt. % volatile components; and the fluidized bed heater is configured to heat the polymer solids to a solids temperature from at least about 15° F. above the solids temperature in the flash chamber and up to about 15° F. greater than the reaction temperature.",
    "16. The system of claim 10, wherein: the fluidized bed heater is configured to fluidize the polymer solids and to heat the polymer solids with a fluidizing gas having a temperature from about 10° F. less than to about 20° F. greater than the reaction temperature; and the fluidized bed heater is configured for a residence time in a range from about 1 to about 10 minutes.",
    "17. The system of claim 10, wherein: the purge column is configured to contact the polymer solids with the stripping gas having a temperature from about 15° F. less than to about 15° F. greater than the reaction temperature; and the purge column is configured for a residence time in a range from about 20 to about 60 minutes and an operating pressure of from about 0 to about 10 psig.",
    "18. A polymerization reactor system comprising: the polyethylene recovery and volatile removal system of claim 10; and the ethylene polymerization reactor, wherein the ethylene polymerization reactor is configured to contact a catalyst composition with ethylene and an optional olefin comonomer to produce the ethylene polymer effluent stream.",
    "19. The polymerization reactor system of claim 18, wherein: the ethylene polymerization reactor is a loop slurry reactor or a gas phase reactor; and the polymerization reactor system contains at least one reactor in addition to the ethylene polymerization reactor.",
    "20. A polyethylene recovery and volatile removal system comprising: (A) a heated fluidized bed flash chamber for heating and for reducing a pressure of an ethylene polymer effluent stream from an ethylene polymerization reactor, and for removing an initial portion of volatile components from polymer solids, wherein the heated fluidized bed flash chamber is configured to form the polymer solids at a solids temperature from about 30° F. less to about 20° F. greater than a reaction temperature in the ethylene polymerization reactor; and (B) a purge column for contacting the polymer solids with a stripping gas, wherein the purge column is configured to remove a final portion of the volatile components to produce a polymer solids stream containing less than 100 ppmw of volatile components."
  ],
  "description_excerpt": "The present disclosure relates to polyethylene recovery and volatile removal systems and to methods for removing volatile components from an ethylene polymer effluent stream from a polymerization reactor, and more particularly, relates to such systems and methods in which the polymer solids temperature is significantly increased prior to introduction of the polymer solids into a purge column for stripping of volatile components from the polymer solids.\n\nIn many systems and methods for volatile component removal, a purge column is utilized, but often the polymer solids temperature entering the purge column is unacceptably low, resulting in poor volatile removal, long residence times, and large column sizes in order to meet a desired final volatile content of, for example, less than 100 ppmw (ppm by weight) of volatile components.\n\nThus, the present invention is generally directed to systems and methods for significantly increasing the temperature of the polymer solids entering the purge column.\n\nThis summary is provided to introduce a selection of 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 be used to limit the scope of the claimed subject matter.\n\nPolyethylene recovery and volatile removal systems are described herein.",
  "cpc": [
    "C08F 6/10",
    "B01J 19/2435",
    "C08F 10/02",
    "C08F 2/14",
    "C08F 2/34",
    "C08F 6/001",
    "C08F 6/005",
    "C08F 6/006",
    "C08F 6/02"
  ],
  "ipc": [
    "B01J 19/24",
    "C08F 2/34",
    "C08F 6/00",
    "C08F 6/10"
  ],
  "assignees": [
    "Chevron Phillips Chemical Co LP"
  ],
  "inventors": [
    "Kenneth A. DOOLEY",
    "Jeffrey S. Lowell",
    "Joseph A. CURREN",
    "Scott E. Kufeld"
  ],
  "filing_date": "2019-01-31",
  "publication_date": "2020-09-15",
  "grant_date": "2020-09-15",
  "priority_date": "2019-01-31",
  "application_number": "US-201916263010-A",
  "family_id": "69771026",
  "cited_by_count": 5,
  "citations": [
    "US2825721A",
    "US3226205A",
    "US3248179A",
    "US3119569A",
    "US3225023A",
    "US3242099A",
    "US3622521A",
    "US3625864A",
    "US3900457A",
    "US3887494A",
    "US3976632A",
    "US4053436A",
    "US4081407A",
    "US4182815A",
    "US4151122A",
    "US4247421A",
    "US4248735A",
    "US4297460A",
    "US4397766A",
    "US4296001A",
    "US4339559A",
    "US4301034A",
    "US4364842A",
    "US4364855A",
    "US4364854A",
    "US4444962A",
    "US4504638A",
    "US4444964A",
    "US4444965A",
    "US4460756A",
    "US4397769A",
    "US4501885A",
    "US4392990A",
    "US4405501A",
    "US4588790A",
    "US5037911A",
    "US4806513A",
    "US4547557A",
    "US4808561A",
    "US4735931A",
    "US4820785A",
    "US4939217A",
    "US4855271A",
    "US4981831A",
    "US5705478A",
    "US4988657A",
    "US5565175A",
    "US5237025A",
    "US5275992A",
    "US5219817A",
    "US5221654A",
    "US5575979A",
    "US5210352A",
    "US5401817A",
    "US5631335A",
    "US5436305A",
    "US5627247A",
    "US5451649A",
    "US5191132A",
    "US5571880A",
    "US5565592A",
    "US5668230A",
    "US5610247A",
    "US5594078A",
    "US5244990A",
    "US5352749A",
    "US5436304A",
    "US5347026A",
    "US5399636A",
    "US5480848A",
    "US5496781A",
    "US5498581A",
    "US5541272A",
    "US5420320A",
    "US5554795A",
    "US5563284A",
    "US5631203A",
    "US5654454A",
    "US5705579A",
    "US6239235B1",
    "US6833415B2",
    "US6300271B1",
    "US6831141B2",
    "US6262191B1",
    "US6355594B1",
    "US6653416B2",
    "US6395666B1",
    "US6613712B1",
    "US6548442B1",
    "US7417097B2",
    "US6833338B2",
    "WO2004000891A1",
    "US7041617B2",
    "US7531606B2",
    "US7109290B2",
    "US20060287442A1",
    "US7294599B2",
    "US7199073B2",
    "US7598327B2",
    "US7026494B1",
    "US7312283B2",
    "US7226886B2",
    "US7517939B2",
    "US7619047B2",
    "US7910689B2",
    "US8080681B2",
    "US7919639B2",
    "US8822608B1"
  ]
}