gary rochelle presentation
Post on 02-Dec-2014
100 Views
Preview:
TRANSCRIPT
6/29/11
1
CO2CapturebyAmineScrubbingBy
GaryT.Rochelle
LuminantCarbonManagementProgram
DepartmentofChemicalEngineering
TheUniversityofTexasatAusJn
RECS
June9,2011
CentralMessages
• AmineScrubbingisTHEtechnologyforCO2capturefromCoalPowerplants
• EnergyconsumpJonbyaminesisapproaching20%oftheplantoutput,apracJcallowerlimit.
• SolventdegradaJon&contaminaJonwillprobablylimitthechemicalcosttolessthan$5/lb.
6/29/11
2
IbelievethatCO2willberegulated
becauseourscienJstshaveshownthatsignificantglobalwarmingisresulJngfromconJnuingemissionsofCO2
CoalCombusJonisanimportantcontrollablesourceofCO2emissions.
CarbonCapture&Storage(CCS)isanimportantopJonforexisJngcoal‐firedpowerplants
SourcesofGlobalWarming(IPCC,2007)
‐1 ‐0.5 0 0.5 1 1.5 2
Netanthropogenic
CO2
CH4,etc
directaerosols
cloudaerosols
solar
Radia%veForcing(W/m2)
6/29/11
3
ModelswithonlynaturalforcingsModelswithbothnatural&anthropogenicforcings
40%ofUSCO2emissionsareFromElectricityGeneraJon
78%
6/29/11
4
6/29/11
5
6/29/11
6
Other Solutions for Coal • Oxy-Combustion
– O2 plant & compression require more energy – Gas recycle, boiler modification for high CO2 – Gas cleanup, compression including air leaks
• Coal Gasification / Combined Cycle – O2 plant, complex gasifier, cleanup, CO2 removal – Not ready for deployment – Relatively more expensive on PRB or lignite – New plants only
• Neither is Tail end: More suitable for new plants – Require higher development cost, time, and risk – Not suitable for on/off to address peaking
6/29/11
7
HistoryRepeatsCaCO3Slurry:::AmineScrubbing
CaCO3 Event Amine 1936 1st commercial plant 1980
1958 Too commercial for Gov. support “Nearly Insurmountable” issues
1991
1960-75 Government funds advanced alts 1990-
1970-85 Govern. & EPRI fund test facilities 2010-
1968 60-250 MW prototypes 2015
1977 500+ MW deployed per regulations First choice dominates
2020
MessagesonEnergy• ReversibilityisKing• GreaterCapacityreducesSensibleQ• SaturaJonStrippingismorereversible
• FasterSolventsEnhanceReversibility• GreaterHeatofAbsorpJonReducesEnergy• GreaterStrippingTismorereversible• EnhancedStrippingismorereversible
• Energyisapproaching50%oftheoreJcal,apracJcallimit
6/29/11
8
Carbonate & Tertiary/Hindered Amines
HO-CH2-CH2-N-CH2-CH2-OH ↔ MDEAH+ + HCO- ׀ 3
CH3 60 kJ/gmol, slow Methyldiethanolamine (MDEA)
CH3 ׀ ׀ HO-CH2-CH2-NH2 + CO2 ↔ AMPH+ + HCO-
׀ 3 CH3 60 kJ/gmol, slow 2-Aminomethylpropanolamine (AMP, KS-1(?))
CO3= + CO2 + H2O ↔ 2 HCO-
3 20 kJ/gmol Carbonate Bicarbonate very slow
+ CO2 ↔ +HPZ-COO-
Piperazine (PZ)
Primary and Secondary Amines 60-85 kJ/gmol, fast
CH2-CH2
HN NH CH2-CH2
2 HO-CH2-CH2-NH2 + CO2 ↔ HO-CH2-CH2-NH-COO- + MEAH+
Monoethanolamine (MEA) MEA Carbamate (MEACOO-)
2 NH3 + CO2 ↔ NH2-COO- + NH4+
Ammonia
6/29/11
9
6/29/11
10
6/29/11
11
Sensibleheatloss–25kwh/tonne• Q=CpΔT/capacity
=3.5J/mol‐K*5K/(0.88moles/kg)
=20kJ/moleCO2,Steamat155oC
Mass transfer coefficients
Bulk gas
Bulk liquid
Gas film Liquid film
22 4/19/2011
KG
CO2 flux = k (∆ CO2)
PCO2, b PCO2, i
[CO2]i
[CO2]b (=PCO2*)
∙(PCO2,b – PCO2*) CO2 flux =
CO2 flux = kg (PCO2,b- PCO2,i) = kl ([CO2]i – [CO2]b) = kg’ (PCO2,i – PCO2*)
Gas-Liquid Interface
Henry’s Law: PCO2i= He * [CO2]i
6/29/11
12
Gas Film Reaction Film Diffusion Film
Bulk Gas Bulk Liquid
PCO2,b PCO2,i
G-L Interface
[CO2]i
[CO2]b
(PCO2*)
fast chemical rxn
23 4/19/2011
Pseudo 1st order kinetics
CO2 removal = area∙KG(∆PCO2)≈f(area,kg’) Packing Solvent
EsJmateareafromk’g• Lnmeank’gΔP=2.4e‐3mol/s‐m2
– Lean:2.2e‐6*(0.012–0.005)*105– Rich:5e‐7*(0.12‐0.05)*105
• Absorberpackingvolume– 1.9e3m3for800MW,250M2/M3
• 0.9tonneCO2/MW‐hr– 25X25X13.5m– 1.5m/sgasvelocity
• Exergylost/moleCO2– RTln(0.12/0.05)=14kwh/tonneCO2
6/29/11
13
6/29/11
14
GreaterTstrip&ΔHCO2reduceWeq
MEA120°C
PZ
Singlestageflashat90‐150°CCompressionto150barLeanPCO2=0.5kPaat40°C
90°C 150°C
6/29/11
15
6/29/11
16
6/29/11
17
6/29/11
18
0
2
4
6
8
10
0 0.2 0.4 0.6 0.8 1 1.2
k g' av
g (x
107
mol
/pa∙
s∙m
2 )
CO2 Capacity (mol CO2/kg solvent) 4/19/2011 35
Amino Acids
SarK
PZ Derivatives
Primary Amine
MEA
EDA Hindered Amines
2-PE
5/5 MDEA/PZ
PZ based solvents
PZ
2MPZ
Two-dimension comparison of solvents
FastSolvents
Amine (m)Capacity -∆Habs
@PCO2 =1.5kPa kg,
’avg x1e-7
@40 °C
DegT(oC)k1=3e‐6s
mol/kg solv kJ/mol mol/s·Pa·m2 3e‐9s‐1
PZ 8 0.79 70 8.5 163
1-MPZ 8 0.83 67 8.4 148
MDEA/PZ 5/5 0.99 70 8.3 138
2-MPZ/PZ 4/4 0.84 70 7.1 155
MDEA/PZ 7/2 0.80 68 6.9 138
2-MPZ 8 0.93 72 5.9 151
HEP 7.7 0.68 69 5.3 130
MEA 7 0.47 82 4.3 120
6/29/11
19
SlowSolvents
Amine (m)Capacity -∆Habs
@PCO2 =1.5kPa kg,
’avg x1e-7
@40 °C
DegTk1=3e‐9s‐1
mol/kg solv kJ/mol mol/s·Pa·m2 oC
PZ 8 0.79 70 8.5 163
MEA 7 0.47 82 4.3 120
DGA® 10 0.38 81 3.6 132
AEP 6 0.66 72 3.5 121
2-PE 8 1.23 73 3.5 120
MAPA 8 0.42 84 3.1 114
AMP 4.8 0.96 73 2.4 137
MessagesonSolventManagement• ThermalDegradaJon
– LimitsmaxStripperT– TMEA<TMDEA<TAMP<TPZ
• FreeRadicalAutooxidaJon– Iffast,inabsorber::ifslow,inheatexchanger– Alkanolamine>terJary>Hindered>cyclic(PZ)– CatalyzebyFe+2,Cu+2,Mn+2
– Inhibitbyperoxide/radicalscavengers,terJaryamine
• VolaJlityofaminesanddegradaJonproducts– Absorberwaterwashmaywork– Reducedbyhydrophilicgroups&speciaJon– NitrosaminesfromNO2/NO2
‐+secondaryamine– ReclaimingrequiredforcoalimpuriJes
6/29/11
20
5MechanismsforThermalDegradaJon
• 1.CarbamatePolymerizaJon‐MEA• 2.CyclicUrea‐Ethylenediamine
• 3.ArmSwitching/EliminaJon‐TerJaryAmine
• 4.SN2RingOpening–Piperazine• 5.BlendSynergism–Piperazine/MEA
6/29/11
21
O2solubility&MassTransfer
0.E+0
2.E‐5
4.E‐5
6.E‐5
2.E‐04 2.E‐03 2.E‐02
AmineOxida
%on
(mol/m
olCO2)
OxygenRateConstant(s‐1)
Total
Absorber
ExchangerSump
PZ
MEAMDEA
6/29/11
22
VolaJlityIssues
• AminevolaJlity– InH2O– InloadedsoluJon– AsamethylateddegradaJonproduct,e.g.1.4dimethylpiperazine,methylamine
• OxidaJonproducts– HEI– Formamide– Ammonia– NitrosaminefromsecamineandNO2/NO2
‐
Amine Volatility (Pa) at 40 oC Amine Ldg = 0 Ldg: PCO2=500 Pa
@ 40oC
5m MDEA/5m PZ 0.17/3.43 0.16/0.51
7m MDEA/2m PZ 0.56/0.91 0.42/0.21
8m PZ (8.8) 0.78
12m EDA 87 1
7m MEA 10 2.7
5m AMP 14.2 11.2
6/29/11
23
Conclusions
• AmineScrubbingcanbeDeployedby2019• ImprovedAmineSolventsandProcesses
– ReduceEnergyfrom400%to200%ofMinimumW– ProvideStable,BenignSolvents– SimplifysystemstoreducecapitalCost
• AsLimestoneSlurryRulesFGDauer30yrs;AmineScrubbingwilldominateCO2capture.
• OthertechnologiesareunlikelytocompeteforPost‐combusJoncapture.
top related