10/11/2011 2011 acs rubber division 180 th technical meeting kneader technology for the direct...
TRANSCRIPT
10/11/2011
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.
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
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
10/11/2011 – p. 4
Conventional vs. Direct Devolatilization
Solution Polymerization
Stripping
Separation
Confectioning
Coagulation
Expeller
Expander
Belt dryer
Main Evaporation
Finishing
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
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)
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
10/11/2011 – p. 10
Main EvaporationExperimental
100 liter single shaft kneader reactor Residence time of 15 minutes Shaft speed of 50-80 RPM
ElastomerSolution
400 kg/hr10% BR100°C
PastyElastomer
Hot Oil80°C
300 mbar
Hot Oil
10/11/2011 – p. 11
FinishingExperimental
200 liter twin shaft kneader reactor Residence time of 30 minutes Shaft speed of 60 RPM
PastyElastomer
CrumblyElastomer
60 mbar
40 kg/hr
Hot Oil80°C
Hot Oil
10/11/2011 – p. 12
405060708090
100
1 2 3 4 5 6
Tem
pera
ture
(C
) Main Evaporation
Temperature Profile
Thermal Input
Mechanical Input
Thermal Output
Energy Required
Feed
10/11/2011 – p. 13
Main EvaporationEnergy Balance
SolventEvaporation
35 kW
27 kW (77%)mechanical energy
ElastomerSolution
300 mbar~65 °C (estimated)
400 kg/hr10% BR100°C
PastyElastomer44 kg/hr90% BR
97°C
8 kW (23%)thermal energy
10/11/2011 – p. 14
FinishingEnergy Balance
60 mbarDevolatilization0.5 kW
4.6 kWmechanical energy
PastyElastomer
40 kg/hr 1000 ppm Solvent87 °C
44 kg/hr90% BR
97°C
CrumblyElastomer
4.1 kWthermal energy
10/11/2011 – p. 16
FinishingImproved Mass Transfer Process
Finisher size Capacity final VOC total volatiles
7 liter 2.5 kg/hr < 10 ppm 5000 ppm
30 liter 30 kg/hr < 50 ppm 5000 ppm
100 liter 50 kg/hr < 50 ppm 5000 ppm
200 liter 50 kg/hr < 15 ppm 5000 ppm
BR in hexane Atmospheric pressure
10/11/2011 – p. 17
Comparison to Conventional Process
Energy Environment Flexibility Operation Footprint Quality
0
500
1000
1500
2000
2500
kW
h/t
[Ru
bb
er]
Stripping andconvective drying
Direct evaporation
Energy Consumption
24%
100%