By Marcus Hilliard Gary T. Rochelle The University of Texas at Austin
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Transcript of By Marcus Hilliard Gary T. Rochelle The University of Texas at Austin
By Marcus Hilliard Gary T. Rochelle The University of Texas at
Austin
A Predictive Thermodynamic Model for an Aqueous Blend of Potassium
Carbonate, Piperazine, and Monoethanolamine for Carbon Dioxide
Capture from Flue Gas By Marcus Hilliard Gary T. Rochelle The
University of Texas at Austin This research addresses the use of
carbon capture from coal fired power plants to reduce factors
contributing to global warming Our aim is to understand the
fundamental thermodynamic behavior associated with the
post-combustion chemical absorption process Chemical Solvents
Monoethanolamine (MEA) Increase in capacity, faster rates,
robustness MEA/Piperazine (PZ) K2CO3/PZ background carbon capture
technologies process - aqueous absorption
Cooler 2-4 mol H2O/mol CO2 Clean Gas 1% CO2 process - aqueous
absorption Absorber 4060oC 1 atm Stripper 100120oC 1-2 atm Rich
Solvent Lean Solvent Flue Gas 10% CO2 Reboiler needs for
thermodynamics
Mass Transfer Driving force Capacity Speciation [amine] kinetics
Calorimetry Cp DHabs Volatility AmineP* with solvent
characterization through rigorous modeling research objective
Development of a rigorous thermodynamic model for the
H2O-K2CO3-MEA-PZ-CO2 sub-component base systems Cullinane (2005)
Tosh et al. (1959) Numerous Authors UNIFAC Bishnoi (2000)
Perez-Salado Kamps et al.(2003) Derks et al. (2005) Jou et al.
(1995) Dang (2001) and Okoye (2005) aqueous chemistry Complex Mass
Transfer with Chemical Reactions
CO2 Solubility Liquid Phase Vapor Phase Amine Volatility aqueous
chemistry NMR Speciation Specific Heat aspen plus 2006.5 framework
Enthalpy Phase Equilibrium
Aqueous Chemistry elecNRTL model Activity coefficient model in
Aspen Plus 2006.5
Rigorously represents liquid and vapor phases Reference state
convention: Inf. Dil. Aqu. phase for molecular solutes (i.e. CO2)
and ions Pure liquid for molecular solvents (i.e. H2O and MEA) By
adjusting binary interaction parameters Through sequential
non-linear regressions with multiple, independent data sets
international collaboration
Apparatus at NTNU High P CO2 Solubility (100 120 oC) Calorimeter
(40 120 oC) Measured by Inna Kim (NTNU) Apparatus at UT ATM P
Reactor (30 70 oC) (multi-component vapor phase analysis reactor)
Differential Scanning Calorimeter: Specific Heat Capacity & PZ
Solubility NMR Speciation (Chem dept.) Measured by Steve Sorey and
Jim Wallin X-ray Diffraction (Chem dept.) Crystallization
Identification Measured by Vince Lynch experimental design -
overall
52 Systems 9,757 data points sequential regression CO2 Solubility
in 7m MEA at 40 oC
Austgen (1989) Freguia (2002) Jou et al. (1995) This work Lee et
al. (1976) - corrected CO2 Solubility in 2 and 5 m PZ at 40 - 60
oC
Solid Pt & Curves : 2 m PZ Open Pt & Curves : 5 m PZ CO2
Solubility in 5 m K+/2.5 m PZ
60 40 oC 80 oC 60 40 MEA Volatility in 7 m MEA at 40oC
64 ppmv Austgen (1989) This work MEA Volatility at 40oC ~15 % 5 m
K+ + 7 m MEA ~50 ppmv
7 m MEA + 2 m PZ 7 m MEA 5 m K+ + 7 m MEA + 2 m PZ PZ Volatility in
2 m PZ at 40oC
Hilliard (2005) 25 ppmv This work PZ Volatility at 40oC ~30 % 2 m
PZ ~20 ppmv 5 m K+ + 2 m PZ
7 m MEA + 2 m PZ 5 m K+ + 7 m MEA + 2 m PZ CO2 Solubility in 7m MEA
at 60oC Differential Capacity
Austgen (1989) Freguia (2002) Jou et al. (1995) Differential
Capacity This work Lee et al. (1976) - corrected Differential
Capacity wrt PCO2 (0.01 1.0 kPa) at 60oC
H2O-MEA-CO2 H2O-MEA-PZ-CO2 H2O-K2CO3-MEA-PZ-CO2 H2O-K2CO3-PZ-CO2
H2O-K2CO3-MEA-CO2 H2O-PZ-CO2 C13 NMR Speciation for 7 m MEA at
40oC
MEA + MEAH+ MEACOO-1 MEA HCO3-1 + CO3-2 Solid Pt: Poplsteinovo
(2004) Open Pt: This work Solid Curves: This work H1 NMR Speciation
for 1.5 m PZ at 40oC
PZ + PZH+1 H+1PZCOO-1 + PZCOO-1 PZ PZ(COO-1)2 Points: Ermatchkov et
al. (2003) Curves: This work Enthalpy of CO2 Absorption in 7 m MEA
at 40 and 120oC
Kim and Svendsen (2007) 40oC This Work Enthalpy of CO2 Absorption
in 2.4 m PZ at 40 and 120oC
Kim (2007) 40oC This Work Enthalpy of CO2 Absorption Predictions at
40 and 120oC
7 m MEA 2.4 m PZ 6 m K m PZ 5 m K m PZ Specific Heat Capacity
Results for loaded 7 m MEA
H2O a = 0.0 a = 0.139 a = 0.358 a = 0.541 MEA Specific Heat
Capacity Refinement for loaded 7 m MEA Specific Heat Capacity
Refinement for loaded 2 m PZ SLE Results for Mixtures of H2O-PZ
using DSC
Liquid Solution Bishnoi (2002) 10 m PZ PZ (s) 25 m PZ This work 20
m PZ PZ6H2O (s) unit cell of K2PZ(COO)2 COO- complex SEM image
PZ
Crystal Size: 0.43 x 0.33 x 0.08 mm K SLE Results for K+ + PZ
Solutions
KHCO3 (s) K2PZ(COO)2 (s) 5 m K m PZ 5 m K m PZ 6 m K m PZ Systems
Exhibiting SLE Behavior for K+ + PZ Solutions
6 m K m PZ 5 m K m PZ 5 m K m PZ In this work: Developed a new VLE
apparatus = PCO2, PAmine, PH2O At typical lean absorber conditions:
PMEA = 64 ppmv PPZ = 25 ppmv Amine blends illustrate an enhanced
capacity over MEA Enthalpy of CO2 absorption increased in
temperature Successfully measured Cp in loaded solutions between 40
and 120oC Cp of CO2 may be negligible in loaded MEA and PZ Inferred
a possible operating region for CO2 capture utilizing aqueous
PZ.Identified and determine the solubility of K2PZ(COO)2 present in
K+/PZ solutions Created a consistent rigorous thermodynamic model
that adequately predicts solubility, volatility, speciation, and
calorimetry in the base sub-component H2O-K2CO3-MEA-PZ-CO2 systems
within Aspen Plus summary This concludes my presentation
Thank you for your attention.