4/25/2016 Understanding Gas Hydrates and its Utility for Energy - - PDF document

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Understanding Gas Hydrates and its Utility for Energy Solutions

Rajnish Kumar

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Gas hydrates are ice like crystalline material and they shares some of the unique properties of water

• Density of solid water (ice) is lower than liquid water and this

Cooper, A.I., J. Mater. Chem., 2000, 10, 207-234

y ( ) q is one reason why life exist of earth.

• Water molecules have very different boiling point compared to
• ther molecule of similar molecular weight.
• Within the solid ice phase, 13 known phases of ice has been

identified

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4/25/2016 2 Molecular structure of water in different phases

Photographs are from Janda Lab 4/25/2016

• Dr. Rajnish Kumar, NCL ‐ Pune

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Gas hydrates are ice like crystalline material

• Gas hydrates are crystalline non-

stoichiometric compounds consisting p g

• f water and natural gas (CO2, CH4

etc.) physically resembling ice.

• Hydrogen bonded water molecules

(host) create a cage that encloses a guest molecule (typically small molecules like H2, CO2, CH4 ,neo-hexane) I h d f l

• In nature gas hydrates are frequently

encountered under sub sea environment (due to native high pressure and low temperature environment)

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Different guest size results in different hydrate structure

r ≈ 3.95A r ≈ 4.33A r ≈ 3.91 A r ≈ 4.06A r ≈ 5.71A Structure I (sI) 2S.6L.46H2O 512 (S) 51262 (L) Structure H (sH) 3S.2M.1L.34H2O 512 (S) 435663 (M) 51268 (L) r ≈ 3.91A r ≈ 4.73A Structure II (sII) 16S.8L.136H2O 512 (S) 51264 (L)

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Semi-clathrate 2S.XXX.38H2O

Importance of Natural Gas for Energy Solutions

27 27 kg of C ned ned

Coal Coal

21 21 kg of C per GJ of energy obtain per GJ of energy obtain

Oil Natural

1800

(Post industrial revolution)

14 kg 14 kg of C

2005

Wood, muscles power

20xx 1960

0* 0*

gas H2 4/25/2016

• Dr. Rajnish Kumar, NCL ‐ Pune

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Clathrate Hydrates in Nature

• Natural gas is a mixture of mainly methane (90-99%), ethane (0-10%),

propane (0-6%) & CO2 (0-5%) etc.

• Both pure methane and natural gas hydrates exist in the natural world (not
• nly on earth but also on other planets)
• Large quantity of methane hydrate exist on earth either in permafrost or

under the sea bed along continental margin

• Gas hydrates are a good energy resource but it can also be a potential geo

y g gy p g hazard.

• Methane is 21 times more potent green house gas than CO2 and due to rise

in global warming, methane in natural hydrates can decompose and create runaway effect

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Why Study Clathrate Hydrate

• Understanding the hydrate at molecular level and at what is the

right temperature and pressure zone where these hydrates can exist.

Flow Assurance

right temperature and pressure zone where these hydrates can exist.

• Understanding the mechanism of hydrate formation and

decomposition

• Potentially a sustainable energy source while still being a potential

geo hazard and role in global warming

Gas Hydrate As a source of methane /natural gas As a means to develop technology Permafrost-associated natural gas hydrate Deepwater marine natural gas hydrate Gas storage Gas separation Desalination Refrigeration Hydrogen storage Natural gas storage & Methane separation CO separation (CCS) CH4 + CO2/H2S Natural gas production

• Safety in deep oil drilling operations
• Other technological applications and energy solutions like gas

separation, methane storage and transportation

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• Dr. Rajnish Kumar, NCL ‐ Pune

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transportation CO2 separation (CCS) CH4 + O2/N2 CH4 + C2H6 + C3H8 CO2 + H2 N2 + CO2

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Gas hydrates are found below permafrost or the

• cean floor

A hydrate glacier sits on the sea floor, 850 m below the surface* Methane hydrate samples

http:/ / communications uvic ca/ releases/ mr020909ph html http:/ / communications.uvic.ca/ releases/ mr020909ph.html 4/25/2016

• Total Conventional NG: 300

300 – – 370 TCM (around the world) 370 TCM (around the world)

• NGH estimates worldwide: ~ 20,000 TCM

20,000 TCM (mean estimate)

• NGH estimates in India: ~2000 TCM (NGHP estimate)

– Even if 10 % is recoverable 200 TCM 200 TCM – World consumption of Natural Gas per year = 2.4 TCM 2.4 TCM

9

(adapted from Collett, 2002).

Proposed GH exploitation techniques

(a) thermal injection, (b) depressurization, (c) inhibitor or other additive

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Pressure reduction, thermal stimulation or additive addition disturbs the three phase equilibria of natural gas hydrate

Hydrate Hydrate

Pressure

Methane (gas) + Water Methane (gas) + Water Hydrate Hydrate (solid) (solid)

Temperature

(g ) (g ) (liquid) (liquid)

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Sustainable production of methane by molecular replacement

Thermodynamic feasibility Kinetics of replacement Structure stability & Thermodynamic stability

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Schematic of the experimental setup

The current setup has been designed and built with a design pressure of 15 MPa, and temperature range between -15 and 60°C. This setup can study methane hydrate dissociation in a wide range of conditions; like water depth of up to 1500 meters, and typical soil

• verburdens with different methane hydrate saturations

PR PCR GC DAQ Thermocouples PC V5 V3 V4 cv

CR Crystallizer R R i

vent vent V6 SPV

• verburdens with different methane hydrate saturations.

CR R ER

G a s

V1 V2

R Reservoir CV Control Valve PC PC & Controller DAQ Data Acquisition System PCR & PR Pressure Transmitter ER External Refrigerator GC Gas Chromatography SPV Safety Pressure Valve 4/25/2016 13

A set of mass flow meter and pressure controllers simultaneously simulates the marine environment in lab scale setup

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Temperature and pressure controlled high pressure setup for gas hydrate studies

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Bench Scale High Pressure Continuous Setup for Studying Methane Decomposition Kinetics at sub-Sea Environment in Presence of Identified Additives

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Hydrate formation is exothermic

Hydrate formation is a crystallization process

0.14 275.0

G s pt k

Temperature = 273.7 K, P = 10.0 MPa

Typical gas uptake curve for hydrate formation

Gas uptake [mol]

0.04 0.06 0.08 0.10 0.12

Temperature [K]

273.0 273.5 274.0 274.5

Gas uptake Temperature

17

Time [min]

20 40 60 80 100 120

G

0.00 0.02 0.04

T

272.0 272.5

(induction time = 19.0 min)

Chemical Engineering Science, 62, 4268-4276 , 2007

Hydrate formation kinetics shows multiple nucleation event

20 30 40 50 drate conversion (mol%)

100 % saturation 75 % saturation 50% saturation

T-2

3 6 9 12 15 18 10 Water to hyd Time (h) 0.008 0.010 tion er/hr) 100 % saturation 75 % saturation 50% saturation 4/25/2016

Cooling / Heating Coil

T-1 T-3 T 2

3 6 9 12 15 18 0.000 0.002 0.004 0.006 Rate of hydrate format (mol of gas/mol of wate Time (hr) 18

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Conclusion from lab scale measurements

Methane recovery through thermal stimulation alone is possible

• Kinetics of hydrate decomposition is lumped kinetics

Decomposition of methane hydrate and its recovery by depressurization alone (without any thermal stimulation) does not self sustain.

• In absence of thermal stimulation partial recovery of methane is obtained at slower kinetics

CH4 recovery by CO2 replacement is technically feasible, however focus should not only be on the kinetics of methane replacement but also on overall methane recovery methane recovery

Still the question remains, what is the mechanism for such replacement? And what drives the replacement ?

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Understanding gas hydrate & methane recovery at molecular level

• Understanding the structure and cage dynamics of gas

h d t th h t t f th t l ti l t l hydrates through state of the art analytical tools

• Understanding

molecular level replacement kinetics through molecular dynamics simulation

• f

hydrate formation and decomposition.

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Understanding gas hydrate at molecular level through state of the art analytical tools: measurement on solid hydrate phase Solid state NMR Solid state NMR

Tmin= -120oC Pmax= ~ few MPa

Quantitative technique for Cage occupancy

Raman Spectroscopy

X-ray Diffraction

Tmin= -150oC Pmax~ few MPa (rare)

Structure determination

Raman Spectroscopy

Tmin= -190oC Pmax~ few GPa

Qualitative technique for Cage occupancy

determination

21

Different guest size results in different hydrate structure

r ≈ 3.95A r ≈ 4.33A r ≈ 3.91 A r ≈ 4.06A r ≈ 5.71A Structure I (sI) 2S.6L.46H2O 512 (S) 51262 (L) Structure H (sH) 3S.2M.1L.34H2O 512 (S) 435663 (M) 51268 (L) r ≈ 3.91A r ≈ 4.73A Structure II (sII) 16S.8L.136H2O 512 (S) 51264 (L)

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N2 C3H8

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2917 cm

• 1

2906 cm

• 1

Intensity (a.u.)

Large to small cage ratio in SI is 3:1, and in SII is 1:2

Methane with a sII former

2940 2930 2920 2910 2900 2890 2880

Wavenumber (cm

• 1)

2915 cm

• 1

a.u.)

Methane hydrate in sI

2960 2940 2920 2900 2880 2860 2840

Intensity (a Wavenumber (cm

• 1)

2904 cm

• 1

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Distribution of natural gas in the hydrate phase

AIChE J. 54,2132-2144, 2008.

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Calculation of cage occupancy through Raman and NMR Spectroscopy

Kumar et al. AIChE, 2008 CO2 + C3H8 mixed hydrate- SII

Long term kinetic stability of resultant hydrate

Intensity (a.u.)

10 20 30

2Theta CO2 hydrate - SI

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Understanding methane recovery at molecular level through MD simulation

• All atomistic molecular dynamics simulations can give

– intrinsic kinetics of hydrate decomposition y p – One such simulation has identified a unique decomposition pattern

• MD will help in identifying the methane replacement mechanism in

presence of CO2 and other small gases (nitrogen is a potential candidate) for better methane recovery.

– CO2-N2 mixture is important because flue gas from thermal power stations also needs to be sequestrated

• MD simulation can help design and speed test additives which can be

screened before carrying out an expensive experimentation in the lab.

– We have tested few additives in gas phase and few in liquid phase

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MD Simulations points toward a layer by layer decomposition Bulk Water 100 bar Hydrate Cages (3 x 3 x 6 unit cells)

30 40 50 60 70 80 90 100

• f water molecules moved out

Row 1 Row 2 Row 3 Row 4 Row 5 Row 6

30 40 50 60 70 80 90 100

SPC/E TIP4P

Z Y X Bulk Water

500 1000 1500 2000

Time (ps)

• 10

10 20 30

Percentage of

500 1000 1500 2000

Time (ps)

• 10

10 20 30

The Journal of Physical Chemistry C, 117, 2013, 12172-12182 4/25/2016 28

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Evaluation of optimum gas molecule which can replace methane in natural gas hydrate: MD Simulations

ε = 0.085 σ = 0.373 ε = 1.23 σ = 0.353 ε = 2.3 σ = 0.373 ε = 4.0 σ = 0.373 . ε = 1.23 σ = 0.6

ε in KJ/mol; σ in nm; Snap shots were taken after 2ns of run time

Physical Chemistry Chemical Physics, 2015, 17, 9509-9518

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Additive design and validation: MD and Experimentation

Additive + water 500 ps

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2000 ps

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Methane hydrate formation kinetics

512 62 512 512 63

270 K, 800 Bar

5 6 512 64

270 K, 100 Bar Black 512 Red 51262 Green 51263 Blue 51264

Gas hydrate formation in oil and gas pipelines: A nuisance

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Courtesy of SINTEF SINTEF, Norway , Norway

Hydrates may stick on pipeline walls… and block flow

Deadly accidents accidents and plant damages damages from improper hydrate plug removal in the order of millions of $$ $$ Hydrate plugs Hydrate plugs move with high velocity (300 km/hr)

33

Cost at one oil field Cost at one oil field: $10 million/day 10 million/day

Thermodynamic inhibitors has limited applicability

34

• C. Koh, Chem Soc Rev 2002 31 157-167

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KHI can be more cost effective at higher water cut

• Development and test of crystal inhibitor with

two key properties

• Inhibition of crystal nucleation and inhibition
• f crystal growth
• Control of nucleation in proteins, inhibition of

urinary stone formation, inhibition of ice formation in living tissues during cryo- protection, control of crystal size in ice creams

35

(courtesy STATOIL, Norway)

Hydrate formation occur not only on the interface but also in bulk water

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Hydrates formed in presence of small percent of surface modifier (in this case an hydrate inhibitor) shows zig-zag growth pattern … There is no link between the hydrate layer and The aqueous water

Hydrates in presence

• f higher concentration

q layer underneath

• f kinetic inhibitor

does not nucleates on the water – gas interface rather it nucleates some where in the gas phase with a very strange phenomena (Bridge effect?)

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S i d T k R i h i l i d Hydrate Formation conditions: Gas used: Pure CH4; Pressure: 5.0 MPa; Temperature: 274.15 K

Lab scale setup to experimentally identify the additives

Stirred Tank Reactor with optical window

Hydrate Based Gas Separation (HBGS) Process for separating a gas mixture

Feed gas

CO2 depleted gas phase (CO2/ H2)

+

Water

Hydrate crystallization under suitable temperature and pressure CO2 enriched hydrate phase

40 Kang, S.-P., and H. Lee, Environ. Sci. Technol., 34, 4397-4400 (2000)

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Path to commercialization

Static Mixer

Energy Intensive; not suitable for large volumes Energy Intensive; not suitable for large volumes Solid hydrate formation in static mixer Good for P & T measurement Good for additives selection 4/25/2016

• Dr. Rajnish Kumar, NCL ‐ Pune

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Two major challenges 1. Improvement in kinetics of hydrate formation and water to hydrate conversion 2. Effect of impurities like fly-ash, SO2, H2S on separation efficiency Influence of additives on hydrate formation kinetics

42

Gas uptake in bulk water Gas uptake in fixed bed Kumar A, Sakpal T, Linga P , Kumar R. Fuel., 105, 664 - 671 (2013). Bulk water Bulk water + SDS

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• Dr. Rajnish Kumar, CSIR ‐ NCL

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Influence of different contact media in presence of additives on hydrate based gas separation (HBGS) process

Kumar, A., Sakpal, T., Linga, P ., Kumar, R. Chemical Engineering Science (2014) DOI: 10.1016/j.ces.2014.09.019 Kumar, A., Kumar, R. Energy and Fuel (2015) DOI: 10.1021/acs.energyfuels.5b00664 4/25/2016

• Dr. Rajnish Kumar, CSIR ‐ NCL

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Acknowledgements

Funding Partners (Gas Hydrate Research)

• Department of Science and Technology (DST)
• CSIR

12th five year plan (Tapcoal) Students working in the group 1.

• Mr. Vikesh Singh Baghel (M.E, now with Halliburton)

2.

• Dr. Asheesh Kumar (PhD Student, Now with NUS)

3 Mr Nil sh Ch dh r (PhD St d nt)

• CSIR – 12th five year plan (Tapcoal)
• Gas Authority of India Limited (GAIL)

(Process Development)

• Department of Bio-Technology (DBT)
• CSIR – 12th Five Year Plan (Indusmagic)

Scientific Partners (Gas Hydrate Research)

• Dr. Suman Chakrabarty (NCL, India)
• D S di R

(N ith Sh ll) 3.

• Mr. Nilesh Choudhary (PhD Student)

4.

• Mr. Gaurav Bhattacharya (PhD Student)

5.

• Mr. Subhadip Das (PhD Student)

6.

• Mr. Vivek Bermecha (PA-II)

7.

• Dr. Omkar Singh Kushwaha (Research Assistant)

8.

• Mr. Amit Arora (PhD Student at IIT – Roorkee)

9.

• Dr. Ponnivalavan Babu (PhD at NUS)
• 10. Dr. Hari Prakash (PhD at NUS)
• 11. Mr. Tushar Sakpal (PA-II, now at TU Delft)
• 12. Ms. Prajakta Nakate (PA-II, Now at TU Delft )
• Dr. Sudip Roy (Now with Shell)
• Dr. Praveen Linga (NUS, Singapore)

(Process Development)

• Dr. Sanjay Nene (NCL, India)
• Dr. Prashant Barve (NCL, India)

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Thank you !

http://academic.ncl.res.in/k.rajnish

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