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Delving into the World of Gas Delving into the World of Gas Hydrates Hydrates –– Thermodynamics, Thermodynamics, Kinetics and ApplicationsKinetics and Applications-- from from Potential Energy Source to COPotential Energy Source to CO22Sequestration and Water Sequestration and Water DesalinationDesalination
Sang-Yong Lee Ph DSang Yong Lee, Ph.D.
Chemical & Natural Gas Engineering
Texas A&M University-Kingsville
1
Texas A&M University-Kingsville
OutlineI t d ti t G H d t• Introduction to Gas Hydrate
• Thermodynamics• Applications (Current Research)pp ( )
− Gas Separation− Hydrogen Storage/ Transportation− CO2 SequestrationCO2 Sequestration
• Current Project− Flow assurance
Prediction of Gas Hydrate Equilibria Using Molecular− Prediction of Gas Hydrate Equilibria Using Molecular Dynamic Simulation
− Application of the carbon nanotube for solar cell (with Dr. Amit Verma)(with Dr. Amit Verma)
• Future Research− Desalination
CO2 Separation/Sequestration
2
− CO2 Separation/Sequestration− Natural Gas Production from Hydrate Reservoir− New Kinetic Model
What are Gas HydratesWhat are Gas Hydrates
• Nonstoichiometric crystalline compounds with water and light gases (methane, ethane, propane…)
• General formula:− Gas ·nH2O (n varies from 6 to 8)
C i d f d b h d• Comprised of gas encaged by hydrogen bonding of water moleculesSt bl t l T hi h P diti• Stable at low T high P conditions
• Structure I, Structure II, Structure H
3
Phase Behavior
Gas Hydrate Stable Region
Low T, High P
4
Plugging of Natural Gas Pipeline
• Natural gas hydrate deposits
Seafloor Stability
• Hydrate Plugging in Pipeline
Energy Resource
5
Distribution of Organic Carbon in Earth1
566.6830980
Gas Hydrate (onshore andoffshore)980
1400
offshore)
Recoverable and non-recoverable fossil fuel (coal,oil, natural gas)Soil1400
10000
Soil
Dissolved organic matter inwater
5000 Land biota
Others(Peat, Detritalorganic matter,Atmosphere, Marine biota)
6
1. Lee and Holder, Fuel Processing Technology, 71, 181 (2001)
Messoyakhi (Russia)
Start production: 1970
Composition
C1(98 7%) C2(0 03%)
Nankai (Japan)
Production: 2010 C1(98.7%) C2(0.03%)Composition
C1(94.3%), C2(2.6%)
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Natural Gas Hydrate in the World
Pi t t k b USGS
8
Picture taken by USGS
Gas Hydrate Structure (molecular structure) Picture taken by USGS( )
G
Oxygen in water Sediment
Hydrogen bondPicture taken by USGS
Gas
Gas Hydrate
Individual Cages (cavities)
9
Holder, G. D., Zetts, S. and N. Pradhan, Review in Chemical Engineering, 5., 1.Unit Cell (Structure II)
Individual Cages (cavities)
E. Dendy Sloan, Jr., “Clathrate Hydrate of Natural Gases”, 2nd ed., Marcel Dekker (1996)
ApplicationsApplicationspppp• Energy source1 - Twice as much carbon (per unit
volume) as all other forms of fossil fuel combined
• Gas storage (Hydrogen, Natural gas)2/ Transportation
• Separation of Gas Mixtures3
• CO2 sequestration in the ocean4
• Desalination from Seawater1. Lee and Holder, Fuel Processing Technology, 71, 181 (2001)1. Lee and Holder, Fuel Processing Technology, 71, 181 (2001)2. Zhong and Rogers, Chemical Engineering Science, 55, 4175 (2000)3. Barrer and Ruzicka, Trans. Faraday Soc., 58, 2289 (1962)4. S.-Y. Lee et al., Environmental Science & Technology J., 2003
10
Importance of Thermodynamicsp y• Gas Storage (methane, hydrogen) /
TransportationTransportation − Reactor Condition (T, P, concentration)− Storage Conditiong
• Gas Separation− Design (T, P, concentrations for each stage)g ( , , g )
• CO2 Sequestration− Proper location (T, P) for sequestration
• Desalination− Reactor Condition (T, P)
11
Equilibrium Conditions are Needed
ThermodynamicsThermodynamics• van der Waals Model• The Distortion Model (Lee and Holder)2,3,4• The Distortion Model (Lee and Holder)
− Empirical Parameters− Molecular Dynamic Simulationy
• A Thermodynamic Model in Porous Media5
Determine the Gas Hydrate Formation Conditionsy
1. Holder, G. D., Zetts, S. and N. Pradhan, Review in Chemical Engineering, 5., 1.2 S -Y Lee and G D Holder AIChE J Vol 48 161-167 (2002)
Determine the Gas Production Conditions
2. S. Y. Lee and G. D. Holder, AIChE. J., Vol 48, 161 167 (2002).3. S.-Y. Lee and G. D. Holder, Gas Hydrates: Challenges for the Future, Ann. of the
New York Academy of Science, Vol 912, 614-622 (2000).4. S. Zele, S.-Y. Lee and G. D. Holder, J. of Phy. Chem. B, Vol 103, 10250-10257 (1999).5 S -Y Lee et al “Gas Hydrate Formation in Porous Media” AIChE Annual Meeting
12
5. S. Y. Lee et al, Gas Hydrate Formation in Porous Media , AIChE Annual Meeting, Reno, NV (2001).
Phase Equilibriaq• Two or more phases are in equilibrium
(co-existing at the same time)Temperature, Pressure and the Chemical Potentials (µi) of component i in each
h i thphase is the same
h dP
T
Water vaporNatural Gas
hydratei
wateri
vapori µµµ ==
water
Solid gas hydrateT
13
water
Minimum Cell Constant for Each Gas Hydrate(Molecular Dynamic Simulation)(Molecular Dynamic Simulation)
Minimum Energy of Cavity Structure Minimum Energy of Total Structure (Cavity+Gas)
14
Hwang, M.-J., Ph.D Dissertation, University of Pittsburgh (1984).
(Cavity+Gas)
The Distortion Model (Lee-Holder)C i i b di d di h• Cavities can be distorted according to the size of guest molecules1,2
Each single component gas hydrate has− Each single component gas hydrate has different cavity size
Ar HydrateAr Hydratei-C4H10 Hydrate
Each gas hydrate has different ∆µo and ∆ho values
15
1. S.-Y. Lee and G. D. Holder, AIChE. J., Vol 48, 161-167 (2002).2. S. Zele, S.-Y. Lee and G. D. Holder, J. of Phy. Chem. B,
Vol 103, 10250-10257 (1999).
Results (Single component Hydrate)( g p y )100000 Vapor-Ice-Hydrate Vapor-Liquid-Hydrate
10000
a)
Ar
N2ε=1.7%
ε=10.0%
1000
ress
ure
(KPa CH4
CO2
ε=7.2%ε=10.6%
ε=5 3%
100
Pr C2H6
C3H8
ε=5.3%
ε=6.0%
10240 260 280 300 320
H2S ε=7.1%
16
Temperature (K)
Sangyong Lee and Gerald D Holder, AIChE J., 2002
Molecular Dynamic Simulation
Pair potential Fr
(L-J, Kihara)
)(rFr
FFr
)(rFFrF
r
∑ = amF v∑( ) 2,
21),(),( taaayxPyxP yxoonewnew
vvr+=
17
( )2 y
Unit Cell of Empty Gas Hydrate(s-II)
Large Cavity
Water molecule
Small Cavity
18
Mamatha Sudhukar, MS Thesis, Texas A&M University-Kingsville (2006)
∆µ° For St II Gas HydrateFrom MD SimulationFrom MD Simulation
1.8002.000
um
experimental 5% Error,
1 2001.4001.600
quili
briu
J/m
ol
p
simulations
Expon. (experimental)
Isobutane
Distortion Model(empirical parameters)
0.8001.0001.200
ce in
Eq
ergy
, KJ
20% E P
(empirical parameters)
0.2000.4000.600
iffer
enc
Ene 20% Error, Propane
Hydrate
0.0003 3.5 4 4.5 5 5.5 6 6.5 7
D
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Guest Diameter, APavan Sai Kumar, MS Thesis, Texas A&M University-Kingsville (2007)
Hydrogen StorageHydrogen Storage• Hydrogen: an alternative for the fast depleting petroleum yd oge a a te at e o t e ast dep et g pet o eu
resources• Hydrogen: A clean burning fuel with security of supply
STORAGE METHOD CONCERN AREASTORAGE METHOD CONCERN AREA
Compressed form at ~250 bar Safety Li id f t 20 K Li fi ti i i t iLiquid form at 20 K Liquefication is energy intensiveAdsorption on metal alloys Low wt % ( 2-4 wt %) of HydrogenAdsorption on to carbon nano fibers Not provenp p
Gas Hydrates High pressure needed at ambient temperature, but can be stored at p ,ambient pressure at 100 K ( above liquid N2 temperature )
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Discovery of Hydrogen Gas Hydratey y g y• Mao et al. synthesized a hydrogen
clathrate hydrate (2004)clathrate hydrate (2004)− that holds 50 g/litter hydrogen by volume of
5.3wt% stable up to 145K at ambient pressure. • THF+H2 Hydrate
− 10MPa at 277K• TBAB+H2 Hydrate
− 8K higher than THF+H2 hydrate
Thermodynamic Model is needed to predict the equilibrium
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to predict the equilibrium Condition
Predicting H2 Hydrates’ Phase EquilibriumDifficulty:Difficulty:• Existing van der Waals- Platteeuw (vdW)-based
models are useful only for singly occupied hydratesy g y p y• Experimentally, very difficult to determine Cij due to
high P (200MPa) and low T (below 250K).
Hydrogen
Hydrogen
Oxygen
Hydrogen bond
Large Cavity (distorted)
Small Cavity (distorted)
Oxygen
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(distorted) (distorted)
J. Lee, P. Yedlapalli, S.-Y. Lee*, Journal of Physical Chemistry B, 110, 2332-2337, 2006
Details of Ab Initio CalculationsParameter Small cavity Large cavityy g y
Range No. Of
points
Range No. Of
pointsp p
r, Å 1.6-6.0 12 1.6-6.0 12
ξ, degrees -40 - +40 5 -40 - +40 5ξ g
φ, degrees -40 - +40 5 -40 - +40 5
α, degrees 0-180 3 0-120 3g
β, degrees 0-180 3 0-360 4
γ, degrees 0-180 3 0-120 3γ g
Number of
Configurations
8100×2
=16,200
10800×2
=21600
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J. Lee, P. Yedlapalli, S.-Y. Lee*, Journal of Physical Chemistry B, 110, 2332-2337, 2006
Calculated Dissociation Pressures for H HydratePressures for H2 Hydrate2500
Predicted Diss. Pr., barDissociation Pr bar
1500
2000
r, ba
r
Expt. Diss. Pr., bar T, K Expt. Predicted78 0.1 0.4080 1 0 54
Dissociation Pr, bar
500
1000
soci
atio
n P 80 1 0.54
150 128.35200 670.46250 2000 1999 98
0
500
0 50 100 150 200 250 300
Dis
s 250 2000 1999.98
-5000 50 100 150 200 250 300
T, K
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J. Lee, P. Yedlapalli, S.-Y. Lee*, Journal of Physical Chemistry B, 110, 2332-2337, 2006
Calculated Dissociation Pressures for H2-CH4-THF Hydrate
6
8P
a)
2 4 y
4
6ss
ure
(MP
0
2Pre
s
276 278 280 282 284 286 288 290
Temperature (K)Equilibrium prediction for the H2-CH4-THF hydrates with 6 mole% of THF in the aqueous phase. H2, and C1 in vapor phase: Filled square- 34.74 , and 65.26mol%; Filled triangle-69 71 and 30 29mol%; Filled circles: 89 13 and
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Filled triangle-69.71 and 30.29mol%; Filled circles: 89.13 and 10.87 mol%.
S.-Y. Lee, P. Yedlapalli, J. Lee*, Journal of Physical Chemistry B, 110, 26122 -26128, 2006
SummarySummary• By integrating ab-initio calculation with
statistical thermodynamics a newstatistical thermodynamics, a new calculation procedure to predict the equilibrium condition of Hydrogen gasequilibrium condition of Hydrogen gas hydrate has been developed
• A single hydrogen cluster concept has g y g pbee applied.
26
Gas Separation Using Gas Hydrate ith ti lwith nano-particles
• Advantages− Separation of close-boiling compounds
e.g.propane-propylene mixture, ethane-ethylene mixture
− Elimination of additional gas hydrate formation process in gas storage using hydratehydrate.
27
Composition of Flue Gas• Flue gas from a power plant consists of CO (15 20• Flue gas from a power plant consists of CO2 (15 – 20
mol %), O2 (5 to 9 mol %), and trace gases such as SO2, CO with the balance N2.
100000
10000e (K
Pa) N2 Hydrate
CO2 hydrate is stable hil N h d t i10000
Pres
sure
CO2 Hydrate
while N2 hydrate is stable
1000270 275 280 285 290 295
28
270 275 280 285 290 295Temperatuare (K)
Process Development(Gas Separation Using Gas Hydrate)(Gas Separation Using Gas Hydrate)
N2+CO2 gas hydrate
30000
35000
3 batch reactors•Thermodynamics
25000
30000
Pa)
GasHydrate
3 batch reactors (The Lee-Holder Model)
• Kinetic Model
15000
20000
ress
ure
(KP
(The Collision Theory)
•Process Design
5000
10000
Pr
- Number of Stages
-Optimum T P0
0 0.2 0.4 0.6 0.8 1
XNitrogen
Optimum T, P
- Residence time
29
XNitrogen
Note: values are calculated usingthe Lee-Holder model
COCO22 SequestrationSequestration22 qq• CO2 concentration in the atmosphere
increases dramatically:− 7.4 GtC in 1997− 26 GtC in 2100 (Report DOE/ER-30194, Vol 2, 1993)
G l• Goal− Sequester 1 GtC/year in 2023 and 4 GtC/year in 2050
• Gas Hydrate• Gas Hydrate− CO2 Separation from Flue Gas Using Hydrate− Geologic Sequestrationg q− Ocean Sequestration
30
Concept for Producing Sinking CO2 Particles5 5005
10
500
1000A 1000m
HydrateC it
CO2 hydrate density ~10% denser than seawater.C it b d
15
20MPa
)
1500
2000 m)
Seawater
Composite(10% Conversion)
Composite can be denser than seawater at <<3000 m evenwith < 100% conversion of
25Pr
essu
re (M
2500 Dep
th (m
3000m
CO2 at 4oCt 00% co e s o o
CO2 to hydrate.
30
35
3000
3500
B3000m
400.97 0.99 1.01 1.03 1.05 1.07 1.09
4000
31
Density (g/cc)( ) ( )( ) ( ) hhcwwchw
hcwwhwcomposite xMMnx
xMMnxρρρρ
ρρρ
/)/(/)/(
++−++−
=
Experiments Using the ORNL Seafloor Process SimulatorORNL Seafloor Process Simulator
70-L Hastelloy, high pressure vesselMax = 20.6 MPa or
Temperature control(-2°C to 7°C) in an explosion-proof cold room
~2000 m H2Oproof cold room
Gas/liquid delivery and recovery systemsVessel has access ports
32
y yVessel has access ports for instrumentation and observation
Experimental Arrangementand Injector Design Details of mixing zoneand Injector Design
Water
Liquid CO2
WaterLiquid CO2
Liquid CO2
PT
Water
Borescope system
Hydrate–CO2–water composite stream
ORNL Seafloor Process Simulator(70 L hi h l)
Water
33
composite stream(70-L high pressure vessel)
1S.-Y. Lee et al., Environmental Science & Technology J., 2003
Carbon sequestrationq(Future Scenario for Ocean Sequestration)
Direct ocean CO injectionDirect ocean CO2 injection
750 m
3000 m
34
Geologic Sequestration in CO2 Hydrate Sediment
•Stable Conditions of CO22 Hydrate in the sediment can be calculated using asediment can be calculated using a thermodynamic model•Arctic permafrost region or Ocean sediments
Water
35
CO2 Gas Hydrate
Possible Scenario for Geologic S t tiSequestration
• Separation of CO2 from flue gas using gas p 2 g g ghydrate separation
• Inject CO2 hydrate slurry into the gas 2reservoir.
36
Gas Production from Hydrate DepositGas Production from Hydrate DepositGas Hydrate Equilibrium Line
1000000CO2
CH4 + CO2
100000
CO2 hydrate is more stable than
CH4 hydrate
CO2
10000ure
(KPa
)
C 4 yd ate
CH4
• Favorable ∆H for hydrate 1000
Pres
su
• Favorable ∆H for hydrate formation/dissociation
∆H = -81 KJ/gmol (7oC)( )nOHCOOHnCO 2222 →′+
1000
Data obtained from
pure gases
37
∆H = -81 KJ/gmol (7oC)
∆H = 57 KJ/gmol (7oC)( ) OnHCHOHCH n 2424 +→
100260 265 270 275 280 285 290 295 300 305
Temperature (K)
pure gases
Importance of Kineticsp• Gas Storage (methane, hydrogen) and
transportationtransportation− Faster formation of gas hydrate− Calculation of Residence time
• CO2 Sequestration− Faster formation of gas hydrateg y
• Desalination− Prediction of the conversion rate at a given T,
P condition.
Prediction and/or Control the reaction
38
rate
A New Kinetic Model• A new molecular collision model• A new molecular collision model
− Based on the molecular collision theory GasWater
2/12 8
⎞⎜⎜⎛ + BA mmkTdNNZ
Water Water
2/11 ⎞⎛ kT
2 8⎠
⎜⎜⎝
=BA
BABAAB mm
kTdNNZ π
Hydrate Formation Rate22
21
⎟⎠⎞
⎜⎝⎛=
mkTNdZ AAA
π Hydrate Formation Ratem
watergaswaterwatern
ZZ
ZZTPTPr ⎟
⎠
⎞⎜⎜⎝
⎛⎟⎠
⎞⎜⎜⎝
⎛∝ −−)()( 1|212α
totaltotal ZZ ⎠⎝⎠⎝
Net Formation rate = Formation rate –Dissociation rate
39
GasGas
Dissociation rate
Assumptions For a New ModelAssumptions For a New Model
• Hydrate formation rate is a function of:− Number of gas-water collisions in the aqueous
phase.The Maxwell energy distribution gives− The Maxwell energy distribution gives• probability of the successful hydrate formation
collisions
40
New Kinetic Model
⎤⎡ ⎞⎛⎞⎛ 11
⎥⎥⎥
⎦
⎤
⎢⎢⎢
⎣
⎡
⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛
⎟⎟⎠
⎞⎜⎜⎝
⎛−
⎟⎟⎟
⎠
⎞
⎜⎜⎜
⎝
⎛
⎟⎟⎠
⎞⎜⎜⎝
⎛= −
watergaswatergasRTE
hydrate CCkTCCkTLder21
21
2/ 88µπ
µπε
• Activation Energy
⎥⎦⎢⎣ ⎠⎝⎠⎝ mequilibriusystem
gy− Methane: 90.25 kJ/mol− Ethane: 90.3 kJ/mol
41
Comparison Proposed Model with E i t l D t (C H )
C2H6 Hydrate Formation Rate
Experimental Data (C2H6)
C2H6 Hydrate Formation RateTemp (K) Pressure (MPa) Exp (mol/s) Calculated (mol/s) error (%)
274 1.68 7.778E-06 7.441E-06 4.33276 0.83 5.833E-06 7.257E-06 24.40
1.79 7.083E-06 7.763E-06 9.60279 1.49 7.778E-06 7.901E-06 1.59282 2.19 8.889E-06 8.526E-06 4.08
1 89 8 333E-06 8 333E-06 0 001.89 8.333E-06 8.333E-06 0.00
Steric Factor : 1/14252.06
42
ConclusionConclusionConclusionConclusion• Thermodynamic model for gas hydrate
A li ti• Applications• Hydrogen Storage• CO2 Sequestration
•Separation of CO2 from flue gas•Ocean Sequestration•Geologic Sequestration•Swapping method
43
On Going ProjectsOn-Going Projects• Prediction of the Gas Hydrate EquilibriumPrediction of the Gas Hydrate Equilibrium
using Molecular Dynamic Simulation• Modeling of Hydrate Formation Rate with g y
Kinetic Inhibitors• Application of Carbon Nanotube for solar pp
Cell (with Dr. Amit Verma,PI)
44
Hydrate PreventionHydrate Preventionyd ate e e t oyd ate e e t o• Above hydrate formation condition
B i th i li− Burring the pipeline− Well head Heat addition− Insulation− Insulation
• Remove of the free water and vapor water using triethylene glycol or molecularusing triethylene glycol or molecular sieve.
• Inhibitor − Thermodynamic (typically alcohol or glycol)− Kinetic Inhibitor
45
− Anti-agglomerant
Plug Formation via Aggregation in an Oil-dominated System
Time
46
Prevention of PluggingPrevention of Plugging
• Thermodynamic Inhibitor (40 – 60 wt%)y ( )− Adding methanol
• Kinetic Inhibitor (0.2 – 2.0 wt%)( )− Poly(N-Vinylcaprolactam)− Poly(N-Vinylpyrrolidone)/(N-Vinylcaprolactam)
lcopolymer− Poly(N-Vinylpyrrolidone)
Antiagglomerant• Antiagglomerant− Shell-type AA ((1)water soluble (2) oil soluble)
47
Future Project• Gas Separation• Desalination• Control the reaction rate using surfactantg• Natural gas product from Hydrate deposit• CO2 sequestration (swapping)2 q ( pp g)
48
Gas Separation (CO2+N2)Gas Separation (CO2 N2)• Separation of CO2 from a flue gas
Equilibrium pressure
Power Plant
N2
Activated Carbon
Height
Power Plant
Height
Flue gas
Gas hydrate
Pressure
Heat ExchangerCompressor
Flue gas CO2+N2
CO2+N2
49
Compressor
DesalinationGas Hydrate(salting out) Gas
Salty Water
( g ) Gas
+Gas Potable
Water
Water with High Salt Concentration
50
Control the reaction rate using surfactant• Hydrate formation within nano particles• Hydrate formation within nano-particles.• Hydrate particle sizes are controlled by nano-particle
sizes.
Hydrate formation in a reversed micele
51
9 nano-meters
Can the New Model Also Predict the Amount of Gas Production?
Sediment
NO!!!
Ice
Gas HydrateWater
Dissociated Gas Has
52
Gas HydrateDissociated Gas Has been Trapped and can not escape
Research NeededResearch Needed• To predict the production quantity
Connectivity of Pores− Connectivity of Pores• To predict the production rate
− Kinetics of the dissociation of gas hydrates
Percolation Theory•Hosen-Kopelman Algorithmp g
Reservoir simulation
53
Reservoir simulation
Acknowledgement• Dean, Gerald D. Holder, U of Pittsburgh• Professor Jae W. Lee, The City College of New York, CUNY • Professor James C. Holste, Texas A&M
D Y i F M k T A&M• Dr. Yuri F. Makogon, Texas A&M • Dr. Olivia R. West, Oak Ridge National Laboratory• Dr. Costas Tsouris, ORNL,• Mr. Robert Warzinski, NETL• Mr. Sivacharanreddy Peddyreddy, Texas A&M U – Kingsville
M P S i K R d• Mr. Pavan Sai Kumar Redy, Texas A&M U - Kingsville• Mr. Prasad Yedlapalli, CCNY, CUNY
54