JohnJechura jjechura@mines.eduUpdated:January4,2015

HydrogenfromNaturalGasviaSteamMethaneReforming(SMR)

Energyefficiencyofhydrogenfromnaturalgas

Definitionofenergyefficiency Frombasicstoichiometry

CH4 +2H2OCO2 +4H2 Fueltosatisfytheheatrequirements

Fromrealprocesses SMR Steammethanereforming Watershiftreactions Heatintegration CO2 removalorPSA?

2

EnergyEfficiency

outin iEE

Usable energyout ofaprocesscomparedtoall energyinputs

Energyvaluescouldbeheat,work,orchemicalpotential(heatingvalue) HHV(Gross): Fuel+O2 CO2 +H2O(liquid) LHV(Net): Fuel+O2 CO2 +H2O(vapor)

Energyvaluesmayhavetobediscountedwhencombiningdifferenttypes ShouldtheHHVbediscountedwhencombiningwithheatvalues?

HHV LHVBtu/scf Btu/scf kcal/g.mol Btu/scf kcal/g.mol Btu/scf

Hydrogen 324.2 273.8 68.7 325.9 57.7 273.9Methane 1010.0 909.4 213.6 1013.1 191.7 909.1Carbon Monoxide 320.5 320.5 67.6 320.6 67.6 320.6Carbon Dioxide 0.0 0.0 0.0 0.0 0.0 0.0

CompoundGPSA Data Book

HHV LHVDerived from Aspen Plus 2006.5

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BasicStoichiometery CH4 +2H2OCO2 +4H2

2

4

H

CH

mol4mol

NN

Production:

Apparentefficiency(HHVbasis) Justfromstoichiometry:

Includeheatofreaction:

4 68.7 1.291 213.6 4 68.7 1.00

1 213.6 61.3

METHANE

WATERH2-CO2

Q-RXNQ

MAKE-H2

4

Howdoweprovidetheheatofreaction?

2

4

H

CH

4 mol3.11 0.29 mol

NN

Coulduseadditionalmethane 0.29mol fuel/mol reactant(HHVbasis)

Production:

Efficiencyincludingfuel(HHVbasis)

4 68.7 1.01.29 213.6

METHANE

WATER

H2-CO2

Q-RXN

FUEL

AIR

FLUE-GAS

MAKE-H2

BURNER

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SteamMethaneReforming&WaterGasShift

Steam

Natural Gas

Reforming Reactor

High Temperature Shift Reactor

Low Temperature Shift Reactor

Hydrogen Purification

Fuel Gas

Flue Gas

Hydrogen

Methanation Reactor

CO2

Reforming.Endothermiccatalyticreaction,typically2030atm&800880C(14701615F)outlet.

CH4 +H2O CO+3H2 Shiftconversion.Exothermicfixedbedcatalytic

reaction,possiblyintwosteps.

CO+H2O CO2 +H2HTS:345370C(650 700F)LTS:230C(450F)

GasPurification.AbsorbCO2 (amine)orseparateintopureH2 stream(PSAormembrane).

Methanation.ConvertresidualCO&CO2backtomethane.Exothermicfixedbedcatalyticreactionsat370425C(700 800F).

CO+3H2 CH4 +H2OCO2 +4H2 CH4 +2H2O

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SMRAlternateDesigns Traditionalwith2stagesshift

reactors 95%to98%purity

NewerdesignswithPSA(PressureSwingAdsorption)lowercapitalcosts,lowerconversion,butveryhighpurity(99%+)

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ProcessConsiderationsKaes [2000] Molburg & Doctor [2003] Nexant Report [2006] Other

Model as conversion reactor Model as equilibrium reactor.Sulfur compounds converted to H2S & adsorbed in ZnO bed.

Small temperature increase 500 - 800F depending on technology. 700F most typical.Typically up to 725 psi (50 bar)

Reformer 1450 - 1650F exit 1500F 20 - 30 atm (295 - 440 psia)Equilibirium Gibbs reactor with 20F approach (for design).

Model as equilibrium reactor. 850-1000F (455-540C) inlet1470-1615F (800-880C) outlet

650 - 700F entrance for HTS + LTS 660F entrance 940F (504C) inlet500 - 535F entrance when no LTSEquilibirium Gibbs reactor Fixed 90% CO conversionAll components inert except CO, H2O, CO2, & H2.400 - 450F entrance 400F entranceEquilibirium Gibbs reactor 480-525F (249-274C) outletAll components inert except CO, H2O, CO2, & H2.

Fixed 90% CO conversion

Methanation 500 - 550F entranceEquilibirium Gibbs reactorAll components inert except CH4, CO, H2O, CO2, & H2.

Amine Purification Model as component splitter Model as component splitter MDEA circulation, duty, & work estimates from GPSA Data Book

Treated gas 10 - 15F increase, 5 - 10 psi decrease, water saturated

Treated gas 100F & 230 psi (16 bar) exit

Rejected CO2 atmospheric pressure & water saturated

95% CO2 recoveryPSA Model as component splitter Model as component splitter

100F entrance 90% H2 recovered 75 - 85% recovery for "reasonable" capital costs (higher requires more beds)

H2 purity as high as 99.999% H2 contains 0.001% product stream as contaminant

200 - 400 psig feed pressure for refinery applications4:1 minimum feed:purge gas ratio. Purge gas typically 2 - 5 psig.

Desulfurization Reactors

High Temperature Shift Reactor

Low Temperature Shift Reactor

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HIERARCHY

AMINE

HIERARCHY

HVAL-1

HIERARCHY

HVAL-2

381

CO2

3315

151

FEED

PRODUCT

3814

27328

Q

81519

151

WATER

1628

W Q

23128

37728

34918

Q

42718

20417

21316

Q

3815

Q

W

26014

Q-HEAT1Q

33514HOTPROD

Q

REFORMER

WATPUMP

STEAMGEN

HTS

LTS

COND1

GASCOMP

METHANTR

BasicSMRProcess

Temperature (C)

Pressure (atm)

Remember,directionofarrowindicateswhetherAspenPlus hascalculated,NOTwhetheritisheatin/out

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SMRBasicProcessEnergyRequirements

HIERARCHY

HVAL-1

HIERARCHY

HVAL-2

FEED

PRODUCT

Q

WATER

W Q

Q

Q

Q

CO2

W

REFORMER

WATPUMP

STEAMGEN

HTS

LTS

COND1

GASCOMP

HIERARCHY

AMINE

METHANTR

TREATED TREATED2

HOTPROD

Q

Q

Energy Inputs Energy Removalkcal/hr kW kcal/hr

Steam Boiler 3,742,371 Post Reformer Cooler 2,238,933Reformer 6,332,965 Post HTS Cooler 1,026,525Amine Duty 5,680,514 Post LTS Cooler 2,305,814Methanator Reheat 553,190 Amine Coolers 3,550,321

Sub-total 16,309,040 Product Cooler 800,533Total 9,922,126

BFW Pump 10,959 12.7Gas Compressor 385,571 448.4Amine Power 125,716 146.2

Sub-total 522,246

Total 16,831,286

Heating Values (HHV)kcal/hr kmol/hr kcal/mol

Natural Gas In 21,363,070 100 213.6Product Out 25,938,163 328.6 78.9 H2 Out 292.7

H2 Purity: 89%H2 Production: 2.9

Total Product 25,938,163Total Inputs 38,194,356Efficiency 68%

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HIERARCHY

HVAL-1

HIERARCHY

HVAL-2

FEED

PRODUCT

Q

WATER

W Q

Q

Q

Q

CO2

W

REFORMER

WATPUMP

STEAMGEN

HTS

LTS

COND1

GASCOMP

HIERARCHY

AMINE

METHANTR

TREATED TREATED2

HOTPROD

Q

Q

SMR HeatRecoveryforSteamGeneration

Energy Inputs Energy Removalkcal/hr kW kcal/hr

Steam Boiler 3,742,371 Post Reformer Cooler 2,238,933Methanator Reheat 553,190 Post HTS Cooler 1,026,525

Heat Sub-total 4,295,561 Post LTS Cooler 2,305,814Sub-total 5,571,272

Reformer 6,332,965Amine Duty 5,680,514 Amine Coolers 3,550,321

Sub-total 16,309,040 Product Cooler 800,533Total 9,922,126

BFW Pump 10,959 12.7Gas Compressor 385,571 448.4Amine Power 125,716 146.2

Sub-total 522,246

Total 16,831,286

Heating Values (HHV)kcal/hr kmol/hr kcal/mol

Natural Gas In 21,363,070 100 213.6Product Out 25,938,163 328.6 78.9 H2 Out 292.7

H2 Purity: 89%H2 Production: 2.9

Total Product 25,938,163Net Inputs 33,898,795Efficiency 77%

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ReformerFurnaceDesign

HydrogenProductionbySteamReformingRayElshout,ChemicalEngineering,May2010

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HIERARCHY

DirectFiredHeatersforReformer&AmineUnit

Energy Inputs Energy Removalkcal/hr kW kcal/hr

Steam Boiler 3,742,371 Post Reformer Cooler 2,238,933Methanator Reheat 553,190 Post HTS Cooler 1,026,525

Heat Sub-total 4,295,561 Post LTS Cooler 2,305,814Reformer Flue Gas 648,651

Reformer 6,332,965 Sub-total 6,219,923Amine Duty 5,680,514

Sub-total 16,309,040 Amine Coolers 3,550,321Product Cooler 800,533

BFW Pump 10,959 12.7 Total 10,570,777Gas Compressor 385,571 448.4Amine Power 125,716 146.2

Sub-total 522,246

Total 16,831,286

Heating Values (HHV)kcal/hr kmol/hr kcal/mol Efficiency

Natural Gas In 21,363,070 100 213.6Reformer Fuel Gas 8,184,406 38.3 213.6 77%Amine Unit Fuel Gas 6,659,083 31.2 213.6 85%

Total 36,206,559 169.5

Product Out 25,938,163 328.6 78.9 H2 Out 292.7

H2 Purity: 89%H2 Production: 1.7

Total Product 25,938,163Net Inputs 36,728,805Efficiency 71%

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HIERARCHY

PreHeattheReformerFeed?

Energy Inputs Energy Removalkcal/hr kW kcal/hr

Steam Boiler 3,742,371 Post Reformer Cooler 2,238,933Methanator Reheat 553,190 For Feed Preheat -1,200,000

Heat Sub-total 4,295,561 Post HTS Cooler 1,026,525Post LTS Cooler 2,305,814

Reformer 5,132,965 Reformer Flue Gas 1,673,228Feed Preheat 1,200,000 Sub-total 6,044,500Amine Duty 5,680,514

Sub-total 16,309,040 Amine Coolers 3,550,321Product Cooler 800,533

BFW Pump 10,959 12.7 Total 10,395,354Gas Compressor 385,571 448.4Amine Power 125,716 146.2

Sub-total 522,246

Total 16,831,286

Heating Values (HHV)kcal/hr kmol/hr kcal/mol Efficiency

Natural Gas In 21,363,070 100 213.6Reformer Fuel Gas 7,978,680 37.3 213.6 64%Amine Unit Fuel Gas 6,659,083 31.2 213.6 85%

Total 36,000,833 168.5

Product Out 25,938,163 328.6 78.9 H2 Out 292.7

H2 Purity: 89%H2 Production: 1.7

Total Product 25,938,163Net Inputs 36,523,078Efficiency 71%

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SMRAlternateDesigns

Traditionalwith2stagesshiftreactors 95%to98%purity

NewerdesignswithPSA(PressureSwingAdsorption)lowercapitalcosts,lowerconversion,butveryhighpurity(99%+)

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AlternateHydrogenPurificationProcesses

HydrogenProductionbySteamReformingRayElshout,ChemicalEngineering,May2010

16

W Q

Q

Q

Q

W

Q

Q

SEP

UseofPSAforProductPurification

Energy Inputs Energy Removalkcal/hr kW kcal/hr

Steam Boiler 3,742,371 Post Reformer Cooler 2,238,933Feed Preheat 1,200,000 For Feed Pre-Heat -1,200,000Reformer 5,132,965 Post HTS Cooler 1,026,525

Sub-total 10,075,336 Post LTS Cooler 1,776,046Reformer Flue Gas 1,674,739

BFW Pump 10,959 12.7 Total 5,516,243Gas Compressor 385,571 448.4

Sub-total 396,529

Total 10,471,865

Heating Values (HHV)kcal/hr kmol/hr kcal/mol Efficiency

Natural Gas In 21,363,070 100.0 213.6Reformer Fuel Gas 7,984,234 37.4 213.6 64%

Total 29,347,304 137.4

Tail Gas Out 8,075,157 165.9 48.7Product Out 18,074,861 263.0 68.7 H2 Out 263.0

H2 Purity: 100%H2 Production: 1.9

Total Product 18,074,861Total Inputs 29,743,834Efficiency 61%

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HIERARCHY

W Q

Q

Q

Q

W

Q

Q

SEP

UseofPSAforProductPurification

Energy Inputs Energy Removalkcal/hr kW kcal/hr

Steam Boiler 3,742,371 Post Reformer Cooler 2,238,933Feed Preheat 1,200,000 For Feed Pre-Heat -1,200,000Reformer 5,132,965 Post HTS Cooler 1,026,525

Sub-total 10,075,336 Post LTS Cooler 1,776,046Reformer Flue Gas 2,250,289

BFW Pump 10,959 12.7 Total 6,091,793Gas Compressor 385,571 448.4

Sub-total 396,529

Total 10,471,865

Heating Values (HHV)kcal/hr kmol/hr kcal/mol Efficiency

Natural Gas In 21,363,070 100.0 213.6Reformer Fuel Gas 951,511 4.5 213.6

Sub-total 22,314,582 104.5

Tail Gas Out 8,075,157 165.9 48.7 57%Total 30,389,739

Product Out 18,074,861 263.0 68.7 H2 Out 263.0

H2 Purity: 100%H2 Production: 2.5

Total Product 18,074,861Total Inputs 22,711,111Efficiency 80%

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IntegratedProcess

HydrogenProductionbySteamReformingRayElshout,ChemicalEngineering,May2010

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Whatshouldbethepriceofhydrogen? Hydrogensalesshouldcoverallcostsplus

profit

Rawmaterialcosts(primarilynaturalgas)

Electricity Otheroperatingexpenses(staff,) Recoveryofcapitalinvested

Minimumistocovercostofnaturalgas&power

Example Naturalgas$4.36permillionBTU(asofMarch30,2011)=$3.68perkmolCH4

Electricity6.79/kWhr(for2010perEIAforIndustrialcustomers)

PSAproductionscenario 104.5kmol/hrCH4 $385perhr 461.1kW $31perhr 263kmol/hrH2 $0.79perkg

Electrolysiscomparison 80%electrolysisefficiency&90%compressionefficiency

$3.80perkg

o $6.80perkgwithcapitalcostsincluded

ARealisticLookatHydrogenPriceProjections,F.DavidDotyMar.11,2004(updatedSept21,2004)

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OtherReferences

RefineryProcessModeling,1st ed.GeraldL.KaesKaesEnterprises,Inc.,2000

HydrogenfromSteamMethaneReformingwithCO2CaptureJohnC.Molburg&RichardD.DoctorPaperfor20th AnnualInternationalPittsburghCoalConference,September1519,2003http://www.netl.doe.gov/technologies/hydrogen_clean_fuels/refshelf/papers/pgh/hydrogen%20from%20steam%20methane%20reforming%20for%20carbon%20dioxide%20cap.pdf

EquipmentDesignandCostEstimationforSmallModularBiomassSystems,SynthesisGasCleanup,andOxygenSeparationEquipment;Task1:CostEstimatesofSmallModularSystemsNRELSubcontractReport,workperformedbyNexantInc.,SanFrancisco,CAMay2006http://www.nrel.gov/docs/fy06osti/39943.pdf

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