jorge m. plaza the university of texas at austin january 10-11, 2008
TRANSCRIPT
Jorge M. PlazaThe University of Texas at Austin
January 10-11, 2008
OutlinePrevious Work
Intercooling effect
Conclusions
Future Work
Modeling K+/PZCullinane 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 ModelingFreguia 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) - RateSepTM
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
Lj-1
Lj
Gj
Gj+1
Lj-1
Lj
Gj
Gj+1
Lj-1
Lj
Gj
Gj+1
Lj-1
Lj
Gj
Gj+1
Lj-1
Lj
Gj
Gj+1
Rate-based ApproachReaction equilibrium
Rate-based ApproachReaction KineticsEnhancement Factor
Rate-based ApproachReaction KineticsFilm Reactions
Equilibrium ApproachReaction Equilibrium
Equilibrium ApproachReaction Kinetics
Reaction
Mass Transfer
Enh
R RR
Kenig et al. Reactive Absorption: Optimal Process Design Via Optimal Modeling. Chem. Eng. Sci. 2001, 56, 343-350.
Rate BasedReaction equilibrium
Rate BasedReaction kineticsEnhancement factor
Rate BasedReaction kineticsFilm Reactions
EquilibriumReaction equilibrium
EquilibriumReaction kinetics
Gas Film
PG
Pi = H[CO2]i
P*i P*B
[CO2]*i [CO2]*B
Bulk Gas Bulk LiquidInterface
Rxn Film Liquid Film
Film Discretization
Absorber ReactionsPZCOO-
PZ(COO-)2
b= OH-, H2O, PZ, CO3-2, PZCOO-
HCO3-
b=PZ, PZCOO-, OH-
bHPZCOObCOPZ 2
2 2PZCOO CO b PZ COO bH
bHHCObCO 32
Effect of Intercooling for 4.5m K+/4.5m PZ
Gas Out
Q
Lean
Rich5.48 kmol/s
H=15 m D=9.8 m
CMR-MTL metal NO-2P
5% V. Liquid Hold up
90% removal
12.7% mol CO2
(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 CO2 rate profiles 4.5m/4.5 m K+/ PZ . Loading = 0.44
No Intercooling
T and CO2 rate with intercooling 4.5m/4.5 m K+/ PZ. Loading=0.44
T and CO2 rate profiles. 4.5m/4.5 m K+/ PZ. Loading = 0.21
No Intercooling
T and CO2 rate with intercooling. 4.5m/4.5 m K+/ PZ Loading=0.21
T and CO2 rate profiles. 4.5 m K+/ 4.5 m PZ. Loading=0.315
No Intercooling
T and CO2 rate with intercooling. 4.5m/4.5 m K+/ PZ Loading=0.315
Effect of Intercooling for 11m MEA
Gas Out
Q
Lean
Rich5.48 kmol/s
H=15 m D=10.6 m
CMR-MTL metal NO-2P
1% V. Liquid Hold up
Variable removal
12.7% mol CO2
(500 MW Plant)
Gas in
0.40
Semi Lean
Q
0.46
T and CO2 rate profiles for no intercooling. 11 m MEA.
85% Removal85% Removal
T and CO2 rate profiles with intercooled semilean feed. 11 m MEA.
92.3% Removal92.3% Removal
T and CO2 rate profiles with intercooled semilean feed & intercooling. 11 m MEA.
93.0% Removal93.0% Removal
CO2 removal results for MEA absorber with split feed
Intercooling CO2 Removal (%)
None 85.0
Single 92.3
Double 93.0
Conclusions
Optimum intercooling is related with T bulge position
Tbulge = pinch then intercooling efficientTbulge = pinch then intercooling efficient
Tbulge away from pinch then not much Tbulge away from pinch then not much
improvementimprovement
ConclusionsFor 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 WorkSubstitute new Hilliard (2007) thermodynamics
Model Aboudheir laminar jet to extract kinetics with
RateSepTM
Fix ASPEN to represent physical properties : ρ, D, H
Regress MEA pilot plant data to validate model