Upstream Research

CO2 Removal from Natural Gas

B. T. (Rusty) Kelley27 April 2004

GCEP Energy WorkshopCarbon Capture & Separation

Stanford University

129-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream ResearchTopics

• ExxonMobil Gas Treating Overview• Membrane Separation• Cyrogenic CO2 Separation• Gas Injection• Possible Research Directions

229-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream ResearchGas Treating and InjectionGas Treating and Injection

Gas Treating

AGEUnit

ClausUnit

TGTUnit

Acid Gas Injection

Sour/Acid Gas InjectionSour/Acid Gas Injection• Alternative to sulfur disposal • Alternative to sulfur disposal • Captures other environmental benefits• Captures other environmental benefits• Can reduce life• Can reduce life--cycle costscycle costs• Potential for improved recovery• Potential for improved recovery

SufurSufur Recovery UnitRecovery Unit

ElementalElementalSulfurSulfur

COCO22,,ResidualResidualSulfur oxidesSulfur oxides

Gas TreatingGas Treating•• SolventsSolvents

––ChemicalChemical––PhysicalPhysical––HybridHybrid

•• MembranesMembranes•• CryogenicCryogenic•• Alkaline saltsAlkaline salts•• BatchBatch

Sour Gas Injection

Sweet GasSweet Gas

329-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream ResearchGas Treating

0.1

1

10

100

0.0001 0.001 0.01 0.1 1 10 100

%H2S

%C

O2

Alkaline saltBatchHybridChemicalCyrogenicMembranePhysical

100 Mscfd

1000 Mscfd

429-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream Research

CompetitiveSorption

Molecular Sieving

Large Pore Zeolite Small Pore Zeolite

CO2CH4

Pore SizeDetermines Selectivity

Surface Functionality Determines Selectivity

Separation Mechanisms

Inorganic Membrane MaterialsFor CO2/CH4 Separation

Silica (SiO2)

Both separation mechanisms in play Pores have hydroxyl groups that sorb water

0.5µmPorous

α−AluminaSupport

.05µm Silica Layer

Zeolites (MxSi1-xAlxO2)

Can operate via either mechanismMembrane fabrication challenging

• Very high CO2/CH4selctivity (>200)

• Good fouling resistance

1 µm

5 µm Thick DDR Zeolite Layer

Porous AluminaSupport

• Very High CO2/CH4selctivity (>100)

• Water stability is an issue

Porous γ−Alumina

Layer

529-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream ResearchCryogenic CO2 Separation

100%Carbon Dioxide

100%Methane

Mixture Critical Locus

Feed

CO2CO2SolidificationSolidification

Pres

sure

Pres

sure

TemperatureTemperature

Upstream Research

PI

Integration with Injection

•• HH22S/SulfurS/Sulfur-- Eliminates Claus/TGT units, sulfur blocksEliminates Claus/TGT units, sulfur blocks

++ Saturated sulfur marketsSaturated sulfur markets+ + Slow development of alternative usesSlow development of alternative uses

•• COCO22-- Some producers may have COSome producers may have CO22 incentivesincentives-- Enhanced oil recovery possibleEnhanced oil recovery possible

CFZ is easily CFZ is easily integrated with integrated with acid gas injectionacid gas injection Dry

Gas

CHCH44, N, N22

H2S, CO2

CFZ

729-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream Research

100 Mscfd, 40% acid gas & 950 psig plant inlet100 Mscfd, 40% acid gas & 950 psig plant inlet

Sweetening Process ScreeningSweetening Process Screening

ChemicalChemical PhysicalPhysical11 CFZCFZ11

Capital InvestmentCapital Investment 1.41.4 1.31.3 1.01.0Annual Operating CostAnnual Operating Cost 1.41.4 1.191.19 1.01.0Plant HorsepowerPlant Horsepower 1.51.5 1.411.41 1.01.0Gas salesGas sales 0.910.91 0.930.93 1.01.0

1 1 ---- from study by independent consultantfrom study by independent consultant

829-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream ResearchAcid & Sour Gas Injection Existing, Planned, or Evaluated

58 tons CO2/Mscf

65% H2S

1% H2S

17% H2S

20% H2S

0.5% H2S

17% H2S

28% H2S

4% H2S

NG

N2N2, NG

1

10

100

1,000

10,000

0 2,000 4,000 6,000 8,000 10,000 12,000

Pressure, psig

Rat

e, M

scfd

Typical sour / acid gas projects (most in USA & Canada)

500 MW power plant flue gas

500 MW power plant CO2

Blue -- Acid gas

Red -- Sour gas

Green -- N2, NG

929-Apr-04 GCEP Energy Workshop -- Carbon Capture

Upstream ResearchPossible Research Directions for CO2 CaptureGCEP goal: Identify and conduct fundamental, pre-commercial

research to overcome barriers that will allowtechnology options to become commercially viable

Challenge: Make electric power production with low specific CO2 emissions cost competitive assuming no non-market incentives

• Fundamental not incremental• Economically competitive not just improved economically• Leveraged and integrated with best efforts to date that have

identified and evaluated CO2 capture technologies• Applicable to multiple future scenarios