Jorge M. Plaza The University of Texas at Austin January 10-11, 2008

Outline Previous Work Intercooling effect Conclusions Future Work

Modeling K + /PZ Cullinane K + /PZ (2005) e-NRTL to predict VLE and speciation Equilibrium and interactions regressed in FORTRAN Experimental rate constants and diffusion coefficients Hilliard K + /PZ(2005) Thermodynamics into ASPEN Plus ® Chen Pilot plant testing (2004 – 2006) 4 Campaigns 5m/2.5m, 6.4m/1.6m K + /PZ and 7m MEA Absorber Model developed for K + /PZ (2006)

System Modeling Freguia MEA (2002) - Ratefrac Aspen Plus® rate-based model based on Dang (2001) Equilibrium by Jou et al. (1995) Intercooling for MEA absorber Ziaii MEA (2006) - RateSep TM Developed rate-based model for MEA in Aspen Plus ® based on Freguia (2002), Hikita (1977) and Aboudheir (2002) Plaza K + /PZ(2006 – 2007) Activity based kinetics for 4.5m/4.5m K + /PZ Intercooling with split feed

Approaches to Absorber modeling Kenig et al. Reactive Absorption: Optimal Process Design Via Optimal Modeling. Chem. Eng. Sci. 2001, 56, Rate Based Reaction equilibrium Rate Based Reaction kinetics Enhancement factor Rate Based Reaction kinetics Film Reactions Equilibrium Reaction equilibrium Equilibrium Reaction kinetics

Film Discretization

Absorber Reactions PZCOO - PZ(COO - ) 2 b= OH -, H 2 O, PZ, CO 3 -2, PZCOO - HCO 3 - b=PZ, PZCOO -, OH -

Effect of Intercooling for 4.5m K + /4.5m PZ Gas Out Q Lean Rich 5.48 kmol/s H=15 m D=9.8 m CMR-MTL metal NO-2P 5% V. Liquid Hold up 90% removal 12.7% mol CO 2 (500 MW Plant) Gas in Variable ldg & flow

Intercooling with 4.5m K + / 4.5 m PZ

Rich loading vs. lean loading. 4.5m K + / 4.5 m PZ

T and CO 2 rate profiles 4.5m/4.5 m K + / PZ. Loading = 0.44 No Intercooling

T and CO 2 rate with intercooling 4.5m/4.5 m K + / PZ. L oading=0.44

T and CO 2 rate profiles. 4.5m/4.5 m K + / PZ. Loading = 0.21 No Intercooling

T and CO 2 rate with intercooling. 4.5m/4.5 m K + / PZ Loading=0.21

T and CO 2 rate profiles. 4.5 m K + / 4.5 m PZ. Loading=0.315 No Intercooling

T and CO 2 rate with intercooling. 4.5m/4.5 m K + / PZ Loading=0.315

Effect of Intercooling for 11m MEA Gas Out Q Lean Rich 5.48 kmol/s H=15 m D=10.6 m CMR-MTL metal NO-2P 1% V. Liquid Hold up Variable removal 12.7% mol CO 2 (500 MW Plant) Gas in 0.40 Semi Lean Q 0.46

T and CO 2 rate profiles for no intercooling. 11 m MEA. 85% Removal

T and CO 2 rate profiles with intercooled semilean feed. 11 m MEA. 92.3% Removal

T and CO 2 rate profiles with intercooled semilean feed & intercooling. 11 m MEA. 93.0% Removal

CO 2 removal results for MEA absorber with split feed IntercoolingCO 2 Removal (%) None85.0 Single92.3 Double93.0

Conclusions Optimum intercooling is related with T bulge position Tbulge = pinch then intercooling efficient Tbulge = pinch then intercooling efficient Tbulge away from pinch then not much improvement Tbulge away from pinch then not much improvement

Conclusions For a simple absorber system intercooling allows increase in solvent capacity as high as 45%. Intercooling improves performance for MEA split feed as high as 10% Intercooling offers a benefit in energy consumption in the stripper thanks higher rich solvent loading Intercooling is most effective for operations in the range of 0.27 to 0.40 loading for the lean feed.

Future Work Substitute new Hilliard (2007) thermodynamics Model Aboudheir laminar jet to extract kinetics with RateSep TM Fix ASPEN to represent physical properties : ρ, D, H Regress MEA pilot plant data to validate model