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Aspen RateSep Absorber Model for CO 2 Capture CASTOR Pilot Plant IFP – Lyon, France

Aspen RateSep Absorber Model for CO 2 Capture CASTOR Pilot Plant IFP – Lyon, France. by: Ross Dugas January 11, 2008 (ross@che.utexas.edu). Scope of the Presentation. Objective Introduction Data Improvements in Aspen Density Viscosity Thermodynamics – Heat of Formation, Heat Capacity

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Aspen RateSep Absorber Model for CO 2 Capture CASTOR Pilot Plant IFP – Lyon, France

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  1. Aspen RateSep Absorber Model for CO2 Capture CASTOR Pilot PlantIFP – Lyon, France by: Ross Dugas January 11, 2008 (ross@che.utexas.edu)

  2. Scope of the Presentation • Objective • Introduction • Data Improvements in Aspen • Density • Viscosity • Thermodynamics – Heat of Formation, Heat Capacity • Kinetics • Model Parameters • kg, kL, liquid holdup, film discretization, etc. • Results • Conclusions

  3. Objective • Create an Aspen RateSep model to simulate absorber pilot plant data from the CASTOR project • CO2 profiles, Temp profiles • The absorber model will aid in the evaluation and optimization of operating conditions • liquid rate, lean loading, gas temperature, packing height, packing type, etc.

  4. Introduction • CASTOR Project • 12 experimental runs • 1.1 meter diameter absorber • Four 4.25 meter beds of IMTP-50 (17m total) • MEA Concentration: 30 – 33 wt% (CO2-free basis) • Lean Loading: 0.16 - 0.28 mol/mol • Lean Flow Rate: 13 – 24 m3/m2h • TLEAN = 40C TFG ≈ 48C • yCO2 = 10 – 12% (Saturated basis) • QFG ≈ 5000 Nm3/h

  5. Data Improvements – Density • Aspen defaults incorrectly predicted decreasing density with increasing loading • Adjust Aspen parameters • Weiland (1998), 30-35 wt%, 40-80C correlations • Parameters for MEA redefined • MEAH+/MEACOO- and MEAH+/HCO3- defined

  6. Data Improvements – Viscosity • Aspen defaults underestimated viscosity • Adjust Aspen parameters • Weiland (1998), 30-35 wt%, 40-80C correlations • Parameters for MEA redefined • MEAH+, MEACOO- and HCO3- defined

  7. Data Improvements –Heat of Formation • Heat of absorption was inconsistent within Aspen • 5 reactions (Freguia (2002)) • Keq data - Van't Hoff equation • Heat of formation data in Aspen • Heat of formation defined at 25C • updated: MEAH+, MEACOO-, HCO3-, CO3-2

  8. Data Improvements –Heat Capacity • Cp used to match ∆Habs at higher temperatures • 40, 60, 80, 100, 120C • Cp of MEAH+ and MEACOO- set to Cp of MEA • Empirically known from heat exchangers

  9. Data Improvements – ∆Habs • ∆Habs – Keq equations vs Aspen (∆Hform, Cp) parameters • CO2 Loading - 0.2, 0.3, 0.4, 0.45, 0.5 • Temperature – 25, 40, 60, 80, 100, 120C • Discrepancy of ±3% • Improves energy-material balance consistency

  10. Data Improvements – Kinetics • Over 25 sources of MEA kinetics for dilute, unloaded solutions • Currently only 1 data source for highly concentrated, highly loaded MEA solutions • Aboudheir (2002), laminar jet absorber • Rate constants from dilute, unloaded systems don't directly apply to CASTOR conditions • Aboudheir data was verified by matching to dilute, unloaded literature data • Activity coefficient and DCO2 corrections

  11. Aboudheir data presented on unloaded basis

  12. Data Improvements – Kinetics • Ionic strength effect quantified and implemented into Aspen kinetics

  13. Aspen RateSep 1.1 m diameter 17m of IMTP-50 packing Aspects Considered Solvent Degradation Heat Loss Number of Stages Reaction Film Discretization Pressure Drop Interfacial Area Liquid Holdup Gas Film MT Coefficient (kG) Liquid Film MT Coefficient (kL) Model Parameters

  14. Model Parameters • Reaction Film Discretization • RateSep feature allows the reaction film to be subdivided. • Reaction rates calculated for each segment • Reaction film broken into 6 non-equal segments • Larger segments near bulk liquid • Smaller segments near gas-liquid interface

  15. Model Parameters • Pressure Drop • Billet-Schultes pressure drop model to determine ∆P in packing • Matched very well with data • ≈ 70% of measured ∆P attributed to packing • Implemented into Aspen • >80% capacity factor – high vapor rates • Interfacial Area • CASTOR tests • ae = f(QL, VsG, ρG) • ae≈1.5ap

  16. Model Parameters • Liquid Holdup • Gamma topography with 400mm transparent column • hL = f(μL, VsL, ρL, aG) • Gas Film MT Coefficient (kG) • Calculated from Onda (1968) • Liquid Film MT Coefficient (kL) • A value of 5x10-4 m/s • Absorber operated >80% capacity

  17. Case 1A

  18. Case 1A

  19. Conclusions • An Aspen RateSep absorber model was created using CASTOR dimensions • Improved thermodynamic, kinetic and physical property data for H2O-MEA-CO2 system were implemented into the Aspen model • The absorber model was not adjusted to fit experimental performance. • The absorber model did a very good job of predicting the temperature and CO2 profiles of the CASTOR data

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