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2011 ACS Rubber Division 180 th Technical Meeting

2011 ACS Rubber Division 180 th Technical Meeting. Kneader Technology for the Direct Devolatilization of Temperature Sensitive Elastomers. Boyd T. Safrit, PhD, PE Andreas E. Diener, Dipl. Ing. Conventional Process. Polymerization exothermic Temperature control important

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2011 ACS Rubber Division 180 th Technical Meeting

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  1. 2011 ACS Rubber Division180th Technical Meeting Kneader Technology for the Direct Devolatilization of Temperature Sensitive Elastomers Boyd T. Safrit, PhD, PEAndreas E. Diener, Dipl. Ing.

  2. Conventional Process • Polymerization exothermic • Temperature control important • Polymer temperature sensitive • Viscosity increases with MW build   • Solution polymerization • Stirred tank reactors • Steam stripping for solvent removal

  3. Conventional Process Solution Polymerization Water / steam consumption, solvent recovery Coagulation Stripping Plant footprint, maintenance Separation Expeller Expander Air handling and emissions Belt dryer Confectioning

  4. Conventional vs. Direct Devolatilization Solution Polymerization Coagulation Main Evaporation Stripping Separation Expeller Finishing Expander Belt dryer Confectioning

  5. Kneader Technology

  6. Kneader Technology

  7. Main Evaporation • Cement feed of 75-90% solvent • Maximum temperature of 100°C • High energy duty for solvent evaporation   • Back mixed kneader reactor • Discharge target of 2-10% solvent • High mechanical energy input

  8. Finishing • Pasty feed of 2-10% solvent • Maximum temperature of 100°C • High viscosity  high mechanical energy  overheating of elastomer   • Plug flow kneader reactor • Discharge target of 200-2000 ppm solvent • Process elastomer as crumbles (or pasty phase)

  9. Two Step Process for Direct Devolatilization • Installed at Fraunhofer Gesellschaft, Schkopau, Germany • Part of larger semi works plant for polymer synthesis, production, and testing

  10. Main EvaporationExperimental • 100 liter single shaft kneader reactor • Residence time of 15 minutes • Shaft speed of 50-80 RPM 300 mbar Pasty Elastomer Elastomer Solution 400 kg/hr 10% BR 100°C Hot Oil Hot Oil 80°C

  11. FinishingExperimental • 200 liter twin shaft kneader reactor • Residence time of 30 minutes • Shaft speed of 60 RPM 60 mbar Crumbly Elastomer Pasty Elastomer 40 kg/hr Hot Oil 80°C Hot Oil

  12. Main EvaporationTemperature Profile Feed Thermal Output Thermal Input Mechanical Input Energy Required

  13. Main EvaporationEnergy Balance SolventEvaporation35 kW 300 mbar ~65 °C (estimated) Elastomer Solution Pasty Elastomer 400 kg/hr 10% BR 100°C 44 kg/hr 90% BR 97°C 8 kW (23%) thermal energy 27 kW (77%) mechanical energy

  14. FinishingEnergy Balance Devolatilization 0.5 kW 60 mbar Pasty Elastomer Crumbly Elastomer 44 kg/hr 90% BR 97°C 40 kg/hr 1000 ppm Solvent 87 °C 4.1 kW thermal energy 4.6 kW mechanical energy

  15. FinishingImproved Mass Transfer Process

  16. FinishingImproved Mass Transfer Process • BR in hexane • Atmospheric pressure

  17. Comparison to Conventional Process • Energy • Environment • Flexibility • Operation • Footprint • Quality

  18. Conclusion • Conventional process for temperature sensitive elastomers • Mature and proven technology • Several key disadvantages • Two step process for direct devolatilization • Kneader reactor technology • Removes water from process • Demonstrated process on semi works scale

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