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Kinetic and Thermodynamic Data for MEA and MEA/PZ. By: Ross Dugas January 11, 2008. Scope of the Presentation. Introduction to MEA/PZ Objectives Background on Mass Transfer Apparatus - Wetted Wall Column Kinetic and Thermodynamic Comparisons MEA and MEA/PZ systems Conclusions
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Kinetic and Thermodynamic Data for MEA and MEA/PZ By: Ross Dugas January 11, 2008
Scope of the Presentation • Introduction to MEA/PZ • Objectives • Background on Mass Transfer • Apparatus - Wetted Wall Column • Kinetic and Thermodynamic Comparisons • MEA and MEA/PZ systems • Conclusions • Future Work
Why use 7m MEA/2m PZ? • Faster rates – kinetics • Less packing • Richer solutions • Lower energy requirements • Increased capacity – VLE • Lower liquid flow rates • Lower energy requirements
MEA/PZ/CO2 Reactions 2 Monoethanolamine (MEA) MEA Carbamate Protonated MEA Piperazine (PZ) Protonated PZ Carbamate
Objectives • Measure kinetics and equilibrium of 7m MEA and 7m MEA/2m PZ solutions over a wide range of CO2 loadings • Absorber Conditions (40, 60˚C) • Stripper Conditions (80, 100˚C) • Model data using Aspen RateSep
Notes on Mass Transfer • CO2 absorption is liquid film controlled • Generally • Rates dependent on √k2 • Effective mass transfer will not increase by √[Am] • DCO2 and HCO2 change with [Am] • Mass transfer rates dependent on wetted area • Not klo or film thickness • Liquid holdup has a very small effect on rates • Special Conditions • May be klocontrolled – instantaneous reaction or diffusion of reactants and products • At long contact times • At high loading, high temperature, fast reagents, low klo (viscosity)
+ Hilliard ● Jou (1995) ▲ Dugas
● Hilliard ▲ Dugas
● Aboudheir – Laminar Jet Absorber ▲ Dugas – Wetted Wall Column
● 7m MEA/2m PZ ▲ 7m MEA
Conclusions • VLE measurements from Dugas, Hilliard, and Jou (1995) matched for 7m MEA over a wide range of CO2 loadings. Dugas and Hilliard agree for 7m MEA/2m PZ. • 7m MEA/2m PZ has about 45% greater CO2 capacity. • Discrepancies in Dugas and Aboudheir (2002) rate data can probably be explained by mass transfer phenomenon. • 7m MEA/2m PZ shows slightly faster rates than 7m MEA.
Future Work • Reconcile differences with Aboudheir MEA data • Obtain more rate data for 7m MEA, 7m MEA/2m PZ and PZ systems • Absorber conditions (40 and 60˚C) • Stripper conditions (80 and 100˚C) • Explore other MEA/PZ systems • Effect of total concentration, MEA:PZ ratios • Measure diffusion coefficients of MEA and PZ species • Model the WWC with Aspen RateSep using experimental data
Questions? Ross Dugas ross@che.utexas.edu