Prof. Gary T. Rochelle CPE 5.462, 2 MS, 8 PhD Projects/funding for MS or PhD Technology Area CO 2...
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Transcript of Prof. Gary T. Rochelle CPE 5.462, 2 MS, 8 PhD Projects/funding for MS or PhD Technology Area CO 2...
Prof. Gary T. Rochelle
CPE 5.462, 2 MS, 8 PhD
Projects/funding for MS or PhDTechnology Area
CO2 Capture from Flue Gas
( to address Global Climate Change)By Aqueous Absorption/Stripping
Fundamental AreasMass Transfer with Reaction in the Boundary Layer
Applied Aqueous Solution ChemistryAqueous ThermodynamicsAqueous Reaction KineticsApplied Process Simulation
CO2 Emissions by Source (1998)
Coal Elec
Gas Elec.
Petro. E
lec.
Ind. Coal
Ind. Gas
Ind. Petro
.
Trans.
Other
MM
TC
E
0
100
200
300
400
500
System for CO2 Sequestration
Boiler ESP
Flyash
FGD
CaSO4
CaCO3
Abs/Str
DisposalWell
Power
30 psia Steam
CO2
Coal
Net Power
Absorb50°C1 atm
Steam 30 psia
CO2
Strip117°C2 atm
SO2, HCl, NO
10% CO25% O212% H2O
30% MEA
Lean RichH2O
Purge to
Reclaim
MEA Absorption/Simple Stripping
C
Practical Problems• Energy = 20-40% of power plant output
– Steam for stripping– Gas pressure drop
– CO2 Compression
• Amine degradation– 10% of cost – Environmental impact
• Capital Cost– 5 x 50 ft diameter absorbers and strippers– 50 ft packing
Approaches to Practical Problems
• Better Solvents– Faster: promote by piperazine (PZ)– Evolve: Monoethanolamine (MEA)/ PZ
– Lower H: K2CO3/PZ
– Oxygen scavengers
• Better Processes– Vacuum Stripping or Vapor recompression
– CaSO4/K2SO4 Precipitation
• Better contacting– Packing to get G/L area
Fundamental Problems• Model Thermo with high salt (K+) & amine
– Electrolyte NRTL model
– Maximize solvent and CO2 concs
• Measure Mass transfer with chemical reaction
– Find feasible solvent with faster rates
• Measure oxidative degradation/corrosion– Cu++ inhibits corrosion, catalyzes degradation
*COi,CO
CO
PZPZCOOCO
22
2
2 PPH
PZkPZCOOkDFlux
Applied Problems
• Identify Packing with max area at min cost– Characterize and model wetted area
• Innovate flowsheets to minimize Q– Simulate multistage contacting– Simulate Vacuum stripping
• Control complex chemistry to minimize Q
Laboratory Projects
• Mass Transfer with chemical rxn – K2CO3/EDA
– Wetted Wall Column– NMR
• Degradation– Oxidative of Ethylenediamine– Thermal of MEA/PZ
• Solvent Reclaiming– Evaporation of PZ/MEA
– Crystallization of CaSO4 or K2SO4
Pilot Plant Projects
• Validate Models for MEA/PZ– 16.8-inch x 20 ft Absorber/stripper
• Test and Develop Innovative Packing– 16.8-inch x 10 ft PVC Absorber– Low gas velocity
• Demonstrate Process Innovations– Vacuum Stripping– Multistage contacting
Modeling Projects
• Fundamental models for K2CO3/EDA
– Thermodynamics/VLE/Speciation– Mass transfer with Chemical Reaction
• Integrated Absorber and System Models– MEA/PZ– Vacuum Stripping– Multistage stripper
• System optimization/integration– Integrate with Power Cycle
Solvent Alternatives• Functions
– Capacity by reversible reactionThermodynamics and stoichiometry
– Fast mass transfer: kinetics at interface
• Three types of chemistry– CO3
= + CO2 +H2O <> 2 HCO3-
H=5 kcal/gmol, very slow
– R3N + CO2 + H2O <> HCO3- + R3NH+
H=14 kcal/gmol, slow
– 2R2NH + CO2 <> R2N-COO- + R2NH2+
H=22 kcal/gmol, fast
N NH H
O
O
N N
O
OH N
+N
O
OH
H
N N
O
O O
O
K+
K+
O
O OO
O
O
H
H OO
OH
K+
N N
O
OH
O
O
Reaction Chemistry…
+
+ +
…For Potassium Species
…For Piperazine Species
2
+
System Solvent — 3.6 m K2CO3/0.6 m PZ
Mass Transfer
• Report as normalized flux—kg´
• Extract rate constants– Use in conjunction with NMR data– Limited by knowledge of the interface
*, 22
2
2
COiCOCO
PZPZCOOCOPP
H
PZkPZCOOkDFlux
*,
'
22 COiCOG PPkFlux gGG kKk
11
'
1
Wetted Wall Column
Gas inLiquid in
Gas out
Liquid out
ParaffinOil
PCO2
* (Pa)100 1000 10000
No
rmal
ized
Flu
x (m
ol/
Pa-
cm2 -s
)
1e-11
1e-10
5.0 M MEA
3.6 m K+/0.6 m PZ
6.2 m K+/1.2 m PZ
3.6 m K+/0.0 m PZ
Conc. K+/PZ
CO2 Absorption at 60oC
NMR Speciation Analysis
PZ(COO-)2
PZ/H+
PZCOO-/H+
3.6 m K2CO3/0.6 m PZ, T = 333K
Degradation Experiment
Oxidative Degradation
• By Oxygen in flue gas– Monethanolamine make ammonia– Piperazine makes ethylenediamine
• Dissolved metal catalyze– Fe++ – Corrosion inhibitors: Cu++, V+5
• Strip O2, add chelating agents, add oxygen scavengers
LeanSolvent
BlowerTI
TI
TI
TI
Distributor
Recycle CO2
MakeupCO2
Air Vent/makeup
C.W.15oC
CO2
Analyzer
RichSolvent
Pilot Absorber 16.8-inch ID, 20 ft of packing, SS
40 – 60oC
1 atm
Storage
Pilot Stripper16.8-inch ID, 20 ft packing, CS
Lean Solvent
Steam
Distributor
Steam
RichSolvent
CO2
Recycle
Reflux
CW
C.W.15oC
Storage
System Modeling in AspenPlus
Rate-Based contacting: RATEFRAC
Electrolyte Thermodynamics
Mass Transfer with Chemical Rxn
Simultaneous Heat Transfer
Flexible configuration and conditions
MultistageCompressor
W=7.4 kc/mol CO2
CO2130 atm
Q=20 kc/mol CO2
118 C
113 C
Multipressure Stripper
Leanldg=0.34
Richldg=0.46 115 C
4 atm
2.8 atm
2 atm