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Published bySpencer Rich Modified over 9 years ago
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10/11/2011 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.
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10/11/2011 – p. 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
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10/11/2011 – p. 3 Conventional Process Solution Polymerization Stripping Separation Confectioning Coagulation Expeller Expander Belt dryer Water / steam consumption, solvent recovery Air handling and emissions Plant footprint, maintenance
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10/11/2011 – p. 4 Conventional vs. Direct Devolatilization Solution Polymerization Stripping Separation Confectioning Coagulation Expeller Expander Belt dryer Main Evaporation Finishing
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10/11/2011 – p. 5 Kneader Technology
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10/11/2011 – p. 6 Kneader Technology
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10/11/2011 – p. 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
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10/11/2011 – p. 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)
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10/11/2011 – p. 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
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10/11/2011 – p. 10 Main Evaporation Experimental 100 liter single shaft kneader reactor Residence time of 15 minutes Shaft speed of 50-80 RPM Elastomer Solution 400 kg/hr 10% BR 100°C Pasty Elastomer Hot Oil 80°C 300 mbar Hot Oil
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10/11/2011 – p. 11 Finishing Experimental 200 liter twin shaft kneader reactor Residence time of 30 minutes Shaft speed of 60 RPM Pasty Elastomer Crumbly Elastomer 60 mbar 40 kg/hr Hot Oil 80°C Hot Oil
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10/11/2011 – p. 12 Main Evaporation Temperature Profile Thermal Input Mechanical Input Thermal Output Energy Required Feed
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10/11/2011 – p. 13 Main Evaporation Energy Balance Solvent Evaporation 35 kW 27 kW (77%) mechanical energy Elastomer Solution 300 mbar ~65 °C (estimated) 400 kg/hr 10% BR 100°C Pasty Elastomer 44 kg/hr 90% BR 97°C 8 kW (23%) thermal energy
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10/11/2011 – p. 14 Finishing Energy Balance 60 mbar Devolatilization 0.5 kW 4.6 kW mechanical energy Pasty Elastomer 40 kg/hr 1000 ppm Solvent 87 °C 44 kg/hr 90% BR 97°C Crumbly Elastomer 4.1 kW thermal energy
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10/11/2011 – p. 15 Finishing Improved Mass Transfer Process
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10/11/2011 – p. 16 Finishing Improved Mass Transfer Process Finisher sizeCapacityfinal VOCtotal volatiles 7 liter2.5 kg/hr< 10 ppm5000 ppm 30 liter30 kg/hr< 50 ppm5000 ppm 100 liter50 kg/hr< 50 ppm5000 ppm 200 liter50 kg/hr< 15 ppm5000 ppm BR in hexane Atmospheric pressure
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10/11/2011 – p. 17 Comparison to Conventional Process Energy Environment Flexibility Operation Footprint Quality
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10/11/2011 – p. 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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