Packed Beds for Processing Associated and Stranded Gas

Jonathan Lee, Chukwuma Anyigor

School of Chemical Engineering and Advanced Materials

Newcastle University.

Intensification

Talk Outline

• Associated and Stranded Gas

• Options for Stranded Gas

• Gas Processing Plant

• Process Intensification for Stranded Gas

21/5/2014 PIN meeting, Newcastle

FPSO – Shell Prelude

21/5/2014 PIN meeting, Newcastle

Gas

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• Abundant Reserve - (161 x 1012 m3)

• Low Carbon fuel (compared to coal/oil)

• Expensive to transport

• Typically contains:- C1 – C6 hydrocarbons- acid gases (H2S and CO2)- water- nitrogen and trace impurities

• 40 - 60% of the world’s natural gas is stranded gas.

Associated Gas

21/5/2014 PIN meeting, Newcastle

oil field

Associated Gas

• In 2009 150 billion m3 of associated gas were flared1.

• Equivalent to 25% of United States and 30% of EU gas consumption.

• Uses could include- Power generation- Enhanced Oil Recovery- Petrochemicals

Stranded Gas - I

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Gas that has been produced and processed but is geographically isolated from a market

http://www.factbook2011.eni.com/

Stranded Gas - II

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100 km

Sokoto

EmbaymentChad Basin

Benue Trough

Apambra

Basin

Bida

Basin

Trans-Saharan gas pipeline

Options for Stranded Gas

21/5/2014 PIN meeting, Newcastle

Remote Gas

Supply

Major Gas

Market

Adapted from Wood, Ref 2.

Pipeline

Liquified Natural Gas

Gas to Liquid

Gas to Wire

Compressed Natural Gas

Gas to Solids

Gas pipe ≈ 2 - 4 million dollars per mile

Options for Stranded Gas

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• Khalilpour3 considered three options:– Liquified natural gas (LNG)

– Compressed natural gas (CNG)

– Gas to liquids (GTL)

• Historical data for capital and operating costs were used.

• Assumption was made that pipeline specification gas was available at market price.

• Oil price and gas price treated as ranged, random variables.

Options for Stranded Gas

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1 nautical mile = 1.85 km 1 x 1012 ft3 = 28.3 x 109 m3

10000

9000

8000

7000

6000

5000

4000

3000

2000

1000

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Dis

tan

ce t

o m

arke

t (n

auti

cal m

iles)

Reservoir Recoverable Feed Gas Capacity (cubic feet x 1012)

Gas To Liquid (GTL)

Compressed Natural Gas (CNG)

Liquified Natural Gas (LNG)

Can Process Intensification move any of these boundaries?

Gas Processing

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Gas from well

Acid gas water

nitrogen

NGL liquids

Sales Gas

Acid Gas Removal

Absorption processesPressure swing adsorption

Cryogenic distillationMembrane separation

Gas Dehydration

Absorption using glycolPressure swing adsorption

Mercury Removal

Adsorption

Nitrogen Rejection

Cryogenic distillationPressure swing adsorption

NGL Recovery

Turbo-expander and demethanizer

Gas Processing

• All the options for stranded gas involve some processing– Pipeline: All

– LNG: All

– CNG: All

– Gas to wire: acid gas removal, mercury removal

– Gas to liquid: acid gas removal, mercury removal

– Gas to solid: acid gas removal, mercury removal, NGL recovery.

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Acid Gas Removal Using Amines

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LP steam

Sour gas

Rich amine Le

an a

min

e

Sweet gas

Acid gas

Sweet gas

7000 kPa

600 kPa

Ab

sorb

er

Reg

ener

ato

r

Intensified Adsorber

• Gas field producing 1.4 billion cubic meters per year (at STP).

• Reduce the sulfur content to pipeline spec of 10 ppm(molar).

• Rich amine loading of 0.4 molCO2 per mol amine. 30 mass% amine solution.

• The ∆P in the column and rotating packed bed are the same.

• e = 97%, a = 250 m2 m-3

• Mass transfer coefficient (KGa) in the packed column is 0.02 s-1

• Mass transfer coefficient (KGa) in the RPB from the data of Jassim4

21/5/2014 PIN meeting, Newcastle

Intensified Adsorber

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0

1

2

3

4

5

6

7

0

500

1000

1500

2000

2500

3000

3500

4000

0 1 2 3 4 5 6 7 8 9 10

Ro

tati

ng

Pa

ck

ed

Be

d P

ow

er

(MW

)

Ab

so

rbe

r V

olu

me

(m

3)

Acid gas content (mol%)

Rotating Packed Bed

• Capital cost savings have to offset the added operating cost of the RPB.

• Use higher concentration amine solutions in the RPB

Gas to Liquid (GTL)

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Desulphurizednatural gas

Reformer

Syngas to dimethyl ether

Fischer Tropsch

Transported using LPG infrastructure

Transported using liquid fuel infrastructue

Syngas

Intensified GTL

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micro channel reformer

fuel gas + air

hydrocarbon+ steam

LH mm»

combustion catalyst

reforming catalyst

micro channel Fischer Tropsch reactor

cooling water

syngas

FT catalyst

syngas

liquid fuels

steam

flue gas

• Intensification of the heat transfer process leads to compact reactors• Technology commercialized by Velocys and CompactGTL

Gas to Solids

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LiquifiedNatural Gas

Compressed Natural Gas

Gas Hydrates

Temperature -162˚C ambient -10˚C

Pressure 1 bar 206 bar 1 bar

Gas content of 1 m3 at STP

600 m3 200m3 160m3

Gas Hydrate

Water molecules hydrogen bonded in a cage around a gas molecule

Gas to Solids

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Water + surfactant

gas

10 ˚C, 60-90 bar

• Process is thermodynamically driven by pressure.

• Rate of hydrate formation is thought to be mass transfer controlled and could be intensified.

Windmeier and Oellrich5

Conclusions

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• Utilizing stranded gas is a complex problem with many technical solutions

• Feasible options for stranded/associated gas need to be evaluated and niches for the application of Process Intensification identified.

• Process flow rates are large even for small fields.

• It is an area with potential for process intensification.

Thank you for listening

21/5/2014 PIN meeting, Newcastle

Any Questions?

References

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1. http://www.worldbank.org/en/topic/sustainabledevelopment

2. Wood D, Mokhatab S, 2008, “Gas monetiziation technologies remain tantalizingly on the brink”, World Oil, 229, 15

3. Khalilpour R, Karimi I A, 2012, “Evaluation of utilization alternatives for stranded natural gas”, Energy, 40, 317-328

4. Jassim M, Rochelle G, Eimer D, Ramshaw C, 2007, “Carbon Dioxide Adsorption and Desorption in Aqueous Monoethanolamine Solutions in a Rotating Packed Bed”, Ind.Eng.Chem.Res., 46, 2823-2833.

5. Windmeier C, Oellrich L R, 2014, “Visual observation of methane hydrate formation and dissociation process”, Chemical Engineering Science, 109, 75-81.