Lurgi MegaMethanol

Lurgi MegaMethanol
LurgisMegaMethanolprocessisanadvancedtechnology
forconvertingnaturalgastomethanolatlowcostinlarge
quantities.Itpermitstheconstructionofhighlyefficient
single-trainplantsofatleastdoublethecapacityofthose
builttodate.
Thispavesthewayfornewdownstreamindustrieslike
LurgisMTP processwhichcanusemethanolasacompetitivefeedstock.
The MegaMethanol Concept
TheLurgiMegaMethanol technologyhasbeendeveloped
forworld-scalemethanolplantswithcapacitiesgreaterthan
one million metric tons per year. To achieve such a capacity,
a special process design is needed, incorporating advanced
butprovenandreliabletechnology,cost-optimisedenergy
efficiency,lowenvironmentalimpactandlowinvestment
cost.
Themainprocessfeaturestoachievethesetargetsare:
 Oxygen-blownnaturalgasreforming,eitherincombinationwithsteamreforming,oraspureautothermal
reforming.
 Two-stepmethanolsynthesisinwater-andgas-cooled
reactorsoperatingalongtheoptimumreactionroute.
 Adjustmentofsyngascompositionbyhydrogenrecycle.

Synthesis Gas Production

Thesynthesisgasproductionsectionaccountsformore
than50 %ofthecapitalcostofamethanolplant.Thus,
optimisationofthissectionyieldsasignificantcostbenefit.
Conventionalsteamreformingiseconomicallyappliedin
small and medium-sized methanol plants, with the maximum
single-train capacity being limited to about 3000 mtpd.
Oxygen-blownnaturalgasreforming,eitherincombination
withsteamreformingoraspureautothermalreforming,is
todayconsideredtobethebestsuitedtechnologyforlarge
syngasplants.
Theconfigurationofthereformingprocessmainlydepends
onthefeedstockcompositionwhichmayvaryfromlight
natural gas (nearly 100 % methane content) to oil-associated
gases.Theaimistogenerateanoptimumsynthesisgas,
characterisedbythestoichiometricnumbergivenbelow:

SR=

H2-CO2
CO+CO2

=2.02.1

Natural Gas

Air

Desulfurization

Air separation

Pre-reforming

Autothermal
Reforming

Oxygen

Fuel Gas

Methanol Synthesis

Hydrogen
Recovery

Methanol Production using Lurgi

Autothermal Reforming

Methanol Distillation

Pure Methanol

Autothermal Reforming
Pureautothermalreformingcanbeappliedforsyngas
productionwheneverlightnaturalgasisavailableasfeedstocktotheprocess.
Thedesulfurisedandoptionallypre-reformedfeedstockis
reformedwithsteamtosynthesisgasatabout40barand
higherusingoxygenasreformingagent.Theprocessgeneratesacarbon-freesynthesisgasandoffersgreatoperating
flexibilityoverawiderangetomeetspecificrequirements.
Reformer outlet temperatures are typically in the range
of 9501050 C. The synthesis gas is compressed in a singlecasing synthesis gas compressor with integrated recycle
stagetothepressurerequiredformethanolsynthesis.

Comparedtoitscompetitors,Lurgihasthemostreferences
andexperienceforthisreformingtechnology.Thisprocess
hasbeenimplementedinLurgiplantssincethe1950s.
Significantprogressinoptimisingdesignandassuringplant
availabilitywasachievedattheendofthe1980swhen
reliablesimulationtoolsbecameavailable.
With the help of a proprietary, three-dimensional
ComputationalFluidDynamics(CFD)model,gasflowsand
temperatureprofilesweresimulatedwiththeobjectiveof
designingburnerandreactorasanintegratedunit.

Evenwhenusingpuremethaneasfeedstockforautothermalreforming,itisnecessarytoconditionthesynthesis
gas,asitsstoichiometricnumberisbelow2.0.Themost
economicwaytoachievetherequiredgascompositionis
toaddhydrogen,withdrawnfromthemethanolsynthesis
purgestreambyamembraneunitorapressureswing
adsorption(PSA)unit.

Natural Gas

Air

Desulfurization

Air Separation

Process Steam

Steam-reforming

Autothermal
Reforming

Purge
Gas

Methanol Synthesis

Oxygen

Methanol Production using

Lurgi Combined Reforming

Methanol Distillation

Pure Methanol

Combined Reforming
Forheavynaturalgasesandoil-associatedgases,the
requiredstoichiometricnumbercannotbeobtainedbypure
autothermalreforming,evenifallhydrogenavailableis
recyled.Fortheseapplications,theLurgiMegaMethanol
conceptcombinesautothermalandsteamreformingasthe
mosteconomicwaytogeneratesynthesisgasformethanol
plants.Afterdesulfurisation,afeedgasbranchstreamis
decomposedinasteamreformerathighpressure
(3540bar)andrelativelylowtemperature(700800 C).
Thereformedgasisthenmixedwiththeremainderofthe
feedgasandreformedtosyngasathighpressureinthe
autothermalreactor.Thisconcepthasbecomeknownas
theLurgiCombinedReformingProcess.
Themainadvantageofthecombinedreformingprocess
oversimilarprocessalternativesisthepatentedfeedgas
bypassofthesteamreformer.
Formostnaturalgases,lessthanhalfofthefeedgasis
routedthroughthesteamreformer,theoverallprocess
steam requirements also being roughly halved compared
withotherprocesses,whichuseanautothermalreformer

downstreamofthesteamreformerwithoutsuchabypass.
The lower process steam consumption translates into
reducedenergyrequirementsandlowerinvestment.
The Lurgi Combined Reforming Process is also ideal to
generatesynthesisgasfortheFischer-Tropschsynthesis.
TheworldslargestplantofthistypewasbuiltbyLurgiin
SouthAfrica.Thesynthesisgascapacityofthisplantwould
besufficienttoproduceabout9,000mtpdmethanol.

Gas-Cooled Reactor
(second reactor)

Water-Cooled
Reactor (first reactor)
Saturated
Steam

PC

LC

Boiler
FeedWater
Preheated
Syngas

Gas inlet

Catalyst
Support
Manhole
Product Gas
Outlet

Catalyst
Discharge
Syngas Inlet

Start-up
Steam

The Lurgi MegaMethanol Process

Catalyst
Discharge

Methanol Synthesis
Efficientsyngas-to-methanolconversionisessentialforlowcostmethanolproduction.Inaddition,optimumutilisation
ofreactionheatofferscostadvantagesandenergysavings
fortheoverallplant.Fromtheverybeginningofthelowpressuretechnologyera,Lurgihasequippeditsmethanol
plantswithatubularreactorwhichtransferstheheatof
reactiontoboilingwater.
TheLurgiMethanolReactorisbasicallyaverticalshelland
tubeheatexchangerwithfixedtubesheets.Thecatalystis
accommodatedintubesandrestsonabedofinertmaterial.Thewater/steammixturegeneratedbytheheatof
reactionisdrawnoffbelowtheuppertubesheet.Steam
pressurecontrolpermitsexactcontrolofthereactiontemperature. This isothermal reactor achieves very high yields
at low recycle ratios and minimizes the production of
by-products.

The first reactor, the isothermal reactor, accomplishes

partialconversionofthesyngastomethanolathigher
spacevelocitiesandhighertemperaturescomparedwith
single-stage synthesis reactors. This results in a significant
size reductionofthewater-cooledreactorcomparedto
conventional processes, while the steam raised is available
at a higherpressure.
The methanol-containing gas leaving the first reactor is
routed to a second downstream reactor without prior
cooling.Inthisreactor,coldfeedgasforthefirstreactoris
routedthroughtubesinacountercurrentflowwiththe
reactinggas.Thus,thereactiontemperatureiscontinuously
reducedoverthereactionpathinthesecondreactor,and
theequilibriumdrivingforceformethanolsynthesismaintained over the entire catalyst bed. The large inlet gas
preheater normally required for synthesis by a single
water-cooledreactorisreplacedbyarelativelysmalltrim
preheater.

BasedontheLurgiMethanolReactorandthehighlyactive
methanol catalyst with its capability to operate at high
spacevelocities,Lurgihasrecentlydevelopedadualreactor
systemfeaturinghigherefficiency.Theisothermalreactor
iscombinedinserieswithagas-cooledreactor.

ATLAS MegaMethanol plant

Temperature [C]

Inaddition,reactioncontrolalsoprolongstheservicelife
ofthecatalystinthewater-cooledreactor.Ifthemethanol
yieldinthewater-cooledreactordecreasesasaresultof
declining catalyst activity, the temperature in the inlet
sectionofthegas-cooledreactorwillrisewitharesulting
improvement in the reaction kinetics and, hence, an increased
yieldinthesecondreactor.
Aftercoolingandseparationofthepurgegas,thecrude
methanolisprocessedinthedistillationunit.Inthehydrogenrecoveryunit,H2 isseparatedfromthepurgegasand
recycledtothesyngasloop.TheremainingCH4-richgas
fractionisusedasfuelgas.

280

270

260

250

240
0

0,2
Reaction

0,4

0,6

0,8

1
Catalyst height

Cooling water

Temperature [C]

Water-Cooled Reactor

300

200

100

0
0

0,2
Reaction

0,4
Cooling gas

Temperature Profile Gas-Cooled Reactor

0,6

0,8

1
Catalyst height

ThemostimportantadvantagesoftheCombinedSynthesis
Convertersare:
 Highsyngasconversionefficiency.Atthesame
conversionefficiency,therecycleratioisabouthalfof
theratioinasingle-stage,water-cooledreactor.
 Highenergyefficiency.About0.8tof5060barsteam
pertonofmethanolcanbegeneratedinthereactor.
Inaddition,asubstantialpartofthesensibleheatcanbe
recoveredatthegas-cooledreactoroutlet.
 Low investment cost. The reduction in the catalyst volume
forthewater-cooledreactor,theomissionofthelarge
feedgas preheater and savings resulting from other
equipmentduetothelowerrecycleratiotranslateinto
specificcostsavingsofabout40 %forthesynthesisloop.
 Highsingle-traincapacity.Single-trainplantswithcapacitiesof5000mt/dayandabovecanbebuilt.

Areal view of ATLAS

MegaMethanol plant

Methanol Distillation
The crude methanol is purified in an energy-saving 3-column
distillationunit.
With the 3-column arrangement, the low boilers are removed
inthepre-runcolumnandthehigherboilingcomponents
areseparatedintwopuremethanolcolumns.Thefirstpure
methanolcolumnoperatesatelevatedpressureandthe
second column at atmospheric pressure. The overhead
vapours of the pressurised column heat the sump of the
atmospheric column. Thus, about 40 % of the heating
steamand,inturn,about40 %ofthecoolingcapacityare
saved.Thesplitoftherefiningcolumnintotwocolumns
allowsforveryhighsingle-traincapacities.

Economics of the MegaMethanol Concept

Economics of MegaMethanol

References

Feedstockcostandcapital-relatedchargesarethemajor
parametersforproductioncost.Thetablebesideillustrates
thefeedstockconsumption,thecapitalinvestmentandthe
resultingproductioncostforaconventionalsteamreformingplantandMegaMethanolplant.Theresultsshowthat
thehighefficiencyoftheprocessandthelowcapitalinvestmentcostofaMegaMethanolplantpermitasignificant
reduction of the methanol cost.The resulting long-term,
stable and low methanol prices may pave the way for a
wideruseofmethanol,bothintheenergysectorandasa
feedstockinthepetrochemicalsector.

Uptotheendof2009,Lurgihasreceived10contractsfor
MegaMethanolplants,withcapacitiesrangingbetween
0.67and2.3milliontonsperyear.

Conventional
MegaMethanol
Steam Reforming
Concept
Capacity

mtpd

Natural Gas Demand

based on LHV
MMBtu/mt

2500

5000

30

28.5

Capex**

100

130

Opex

100

97

Production Cost

100

79

** O2 over the fence

Lurgiisaleadingtechnologycompanyoperatingworldwide
inthefieldsofprocessengineeringandplantcontracting.
Basedonsyngas,hydrogenproductionandcleanconversion
technologiesforfuelsorchemicalsLurgioffersinnovative
solutionsthatallowtheoperationofenvironmentallycompatibleplantswithcleanandenergy-efficientproduction
processes.
Itstechnologicalleadershipisbasedonproprietaryandexclusivelylicensedtechnologieswhichaimtoconvertallcarbon
energyresources(oil,coal,naturalgas,biomass,etc.)inclean
products.

312e/06.10/10

LurgiisamemberoftheAirLiquideGroup.

Lurgi GmbH
Lurgiallee 5 60439 Frankfurt am Main Germany
Phone: +49 (0) 69 5808-0 Fax: +49 (0) 69 5808-3888
E-mail: communication@lurgi.com Internet: www.lurgi.com