LNG Safety Excellence: A Decade of Efforts by the Mary Kay O’Connor Process Safety Center

Dr.M.SamMannan,PE,CSP,DHCRegentsProfessorandExecutiveDirectorHolderofT.MichaelO’ConnorChairI

MaryKayO’ConnorProcessSafetyCenterArtieMcFerrinDepartmentofChemicalEngineering

TexasA&M UniversitySystemCollegeStation,Texas77843‐3122,USA(979)862‐3985,mannan@tamu.eduhttp://process‐safety.tamu.edu

PHMSAGovernment&IndustryR&DForumCleveland,Ohio,November16‐17,2016

Outline• Introduction• LNGSafetyConcerns• LNGSafetyResearchOverview• AreasofStudy

– LNGVaporDispersionandPoolFireModelingwithCFD– LNGVaporCloudControlusingWaterCurtain– LNGVaporandFireMitigationusingExpansionFoam– ExperimentalStudyandCFD SimulationofBundOvertopping

– Source‐TermandPoolSpreadingofSpillonLandandWater

• Conclusions

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Introduction• Liquefiednaturalgas(LNG):providesflexibilityinnaturalgasindustryfor

storageandinter‐regionaltrade– NewemergingnaturalgasmarketwillaccelerateLNGtradeglobally

• GrowingconcernsonpotentialLNGspillandconsequencearoundfacilities– FurtherresearchonLNGsafetyisrequiredtoensurepublicsafetyandsafeoperation

U.S.naturalgasproductionbysource(trillioncubicfeet)(source:EIA)

LNGimportandexportterminalsapprovedintheU.S.(source:FERC)

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LNG Safety Concerns

LNGProperties• Flammableasafuel

– Flammablelimitrangesapproximately5‐15v/v%inair

• Cryogenicliquidforeaseofstorageandtransportation– Extremelycold,boilingpointis

‐162˚C(‐263˚F)– Expands600timesinvolume

duringvaporization– Difficulttodispersedueto

heavier‐than‐airbehaviorbelow‐114˚C (‐173˚F)

HazardsandRegulations• Mainhazards

Flammablevaporcloud Poolfire

• Standardsandregulations 49CFRPart193

Define“exclusionzones”intermsofvapordispersion(1/2LFL)andfirethermalradiation(5kW/m2)

NFPA59A(2013) Requiremitigationmeasurestoreduceriskstoatolerablelevel

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LNG Safety Research at MKOPSC• InvolvedinresearchfortheimprovementsofLNGsafety,securityand

spillresponsesince2005• Researchprogram,sponsoredby BPGlobalGasSPU, QatarNational

ResearchFoundation,and othersincludes– LNGvapordispersionandpoolfire

• LNGvapordispersionandpoolfireCFD modelingandvalidation– Safetymeasuresfordispersionandfirecontrol

• ApplicationofwatercurtaintodisperseLNGvaporcloud• ApplicationofexpansionfoamandalternatesystemstocontrolLNGvaporandfire

– Riskanalysisofbundovertopping– Source‐termandpoolspreadingofspillonlandandwater

• Combinationoftheoreticalunderstandingwithfield/labteststomaketheresearchapplicabletothecurrentindustryneeds

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LNG Facility at TEEX• SevenseriesofLNGoutdoorspilltestshavebeenperformedsince2005atLNGtestfacilityattheBraytonFireTrainingField(BFTF)ofTexasA&M EngineeringExtensionService(TEEX),CollegeStation,Texas

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• Averagetotalvol.ofLNGused:41m3

• Averagespillrate:0.36~1m3/min• Datameasured

– Windspeed,direction,temperature,humidity,atmosphericheatflux

– LNGflow,level,temperature– LNGvaporturbulence,speed,concentration,temperature

– LNGfiretemperature,heatflux•Pit 1: Small Pit ‐ 3m x 3m x 1.22 m•Pit 2: Large Pit ‐ 10m x 6.7m x 1.22m•Pit 3: L‐shaped trench•Pit 4: Marine Pit ‐ 2.44 m x 6.7 m x 6.7 m 

LNG Vapor Dispersion and Pool Fire Modeling with CFD

7

LNG Vapor Dispersion and Pool Fire 

• Highdemandexistsforperformingsite‐specificriskanalysisofcomplexscenariosinLNGfacilitiesandterminals

• NospecificguidelineonhowtoaddresscomplexscenarioswithCFD

• ImprovetheunderstandingofphysicalprocessofLNGvapordispersionandpoolfire

• StudykeyparametersofmodelingLNGvapordispersionandpoolfirewithCFDcodes

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LNG Vapor Dispersion and Pool Fire 

• Field test setup

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LNG Vapor Dispersion and Pool Fire 

10

LNG Vapor Dispersion and Pool Fire 

11

Ti = 0.2

0.033

0.05

0.025

0.008

0.017

0.042

Comparison of gas concentration contours and effect of turbulence induced by the dike

LNG Vapor Dispersion and Pool Fire 

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• LNGunderwaterrelease

Over‐the‐land video camera Underwater video camera

LNG Vapor Dispersion and Pool Fire 

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FDSExperiment

Pulsation behavior of the fire compared with experiment

Source R3 (kW/m2) R4 (kW/m2)Experiment 2.5 5.0

FDS-Deardorff3.1

(+22%)5.5

(+11%)FDS-Smagorinsky

3.5 (+39%)

6.4 (+28%)

Deardorff turbulence model results in better accuracy of radiation prediction

Flame temperature comparison with experiment

R3 (-2, -2, 0.9) m R4 (-2.2, -0.1, 0.9) m

LNG Vapor Cloud Control using Water Curtain

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Controlling LNG Vapor Cloud using Water Curtain

• Watercurtainisconsideredoneofthemosteffectiveengineeringmethodsinmitigatingvarioustypesofhazards

• NodefinitiveandcomprehensiveguidelineforwatercurtaindesigninLNGvaporcontrol

• DeterminethekeyparametricdependenceofdifferentwatercurtainsincontrollingtheLNGvaporcloud

• Developaneffectiveengineeringguidelineforwatercurtainapplication

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Controlling LNG Vapor Cloud using Water Curtain

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Facility: Brayton Fire Training Field

Pit 1 (3m x 3m x 1.22m) filled with water up to 1.2m

Wooden confinement(1.52m x 1.52m x 0.31m)

3 types spray: Fan, Conical and FogFan type Fog typeConical type

Experiment design

Controlling LNG Vapor Cloud using Water Curtain

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Conc. at 3 different height with/wo full cone type

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

22.5

25.0

‐1.0

‐0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

14.5

15.0

CH4con

c., % (v

/v)

downwind distance, m

No Spray z=0.5m FC Spray z=0.5m

No Spray z=1.2m FC Spray z=1.2m

No Spray z=2.1m FC Spray z=2.1m

LNG Spill edge Full Cone (FC) water curtain 

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

22.5

25.0

27.5

‐1.0

‐0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

10.5

11.0

11.5

12.0

12.5

13.0

13.5

14.0

14.5

15.0

CH4con

c., % (v

/v)

downwind distance, m

No Spray z=0.5m FF Spray z=0.5m

No Spray z=1.2m FF Spray z=1.2m

No Spray z=2.1m FF Spray z=2.1m

LNG Spill edge Flat Fan (FF) water curtain 

0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.0

0 30 60 90 120

150

180

210

240

270

300

Chan

ge in te

mpe

rature, deg C

Relative test time, sec

Test 1: Full ConeAverage: 4.5 C

Test 3: Mist  (down)Average: 6.5 C

Test 2: Flat FanAverage: 2.5 C

Change in water spray temperature reading

Droplet Size:  Mist Cone < Full Cone < Flat FanHeat Transfer Rate : 

Flat Fan < Full Cone < Mist Cone

Conc. at 3 different height with/wo flat-fan type1 2 3

Controlling LNG Vapor Cloud using Water Curtain

18 18

• ForcedDispersionatRM=5.32&12.76

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30 35

Gasconcentration[v/v]

DownwinddistancefromLNGsource[m]naturaldisp forceddispRm=5.32 forceddispRm=12.76

Z=0m

LNGW.C.

X=31m

82.3%

X=23m

25.8%

X=5.5m

ForcedDispersion(t=200s)(RM =5.32) ForcedDispersion(t=200s)(RM =12.76)

15%

0%

7.5%

LNG Vapor and Fire Mitigation using Expansion Foam

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High Expansion Foam 

• upto20Lowexpansion

• 20to200Mediumexpansion

• 200to1000Highexpansion

HighExpansion

MediumExpansion

Vaporhazardmitigation Poolfirecontrol

Studyrequiredtounderstandthephysicalphenomenaanddevelopspecificguidelinesforfoamsystemdesign

Foam=Foamsolution+Air

NFPA11:StandardforLow‐,Medium‐,andHigh‐ExpansionFoam

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LNG Vapor and Fire Mitigation using Foam

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LNG Vapor and Fire Mitigation using Foam

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LNG Vapor and Fire Mitigation using Foam

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LNG Vapor and Fire Mitigation using Foam

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The idea of intermittency I(L) was used to determine average flame lengthThe average flame length was 16.34 m for the fire without foam application, which is the flame length with an intermittency of 0.5

Experimental Study and CFD Simulation of Bund Overtopping

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Bund Overtopping• RolesofBund

– Secondarycontainment

– Limitcontamination

– Reducevaporization

– Controlpoolfireimpact

• CapacityofBund– ≥110%*tankcapacity

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www.polystarcontainment.com

Scenario ‐ Catastrophic Tank Failure

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Video– CFDSimulationonBundOvertopping incaseofcatastrophictankfailure.

Bund Overtopping

• Labtest

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Snapoftheovertoppingprocess:(a)0.0s;(b)0.1s;(c)0.2s;(d)0.3s.

Bund Overtopping

SetupofbundovertoppingtestatBraytonFireTrainingField

• Fieldtest

Source‐Term and Pool Spreadingof Spill on Land and Water

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LNG Spill on Water

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L‐ShapedTrench

Experimental setup for release of LN2 on water

High‐speed Image from flow visualization experiment 

LNG release in L‐Shaped Trench, Release duration – 1200 s

LNG Spill on Land

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Time=0.05sec Time=0.39sec

Time=0.61sec Time=0.62sec Time=0.67sec

Publications• B.R.Cormier,R.Qi,G.W.Yun,Y.Zhang,M.S.Mannan,“ApplicationofComputationalFluidDynamicsfor

LNGVaporDispersionModeling:AKeyParametersStudy”,JournalofLossPreventionintheProcessIndustries,22(3),332‐352,2009.

• R.Qi,D.Ng,B.R.Cormier,M.S.Mannan,“NumericalSimulationsofLNGVaporDispersioninBraytonFireTrainingFieldTestswithANSYSCFX”,JournalofHazardousMaterials,183(1),51‐61,2010.

• R.Qi,M.Albaker,O.Basha,R.Hassiba,M.S.Mannan,T.Olewski,S.Waldram,“Qatar,LNG,SpillExperimentsandProcessSafety”,AdvancesinGasProcessing,Elsevier,349‐357,2010.

• J.A.Suardin,R.Qi,B.R.Cormier,M.A.Rana,Y.Zhang,M.S.Mannan,“ApplicationofFireSuppressionMaterialsonSuppressionofLNGPoolFires”,JournalofLossPreventionintheProcessIndustries,24(1),63‐75,2011.

• R.Qi,P.K.Raj,M.S.Mannan,“UnderwaterLNGReleaseTestFindings:ExperimentalDataandModelresults”,JournalofLossPreventionintheProcessIndustries,24(4),440‐448,2011.

• R.Qi,D.Ng,M.S.Mannan,“BraytonFireTrainingFieldLNGSpillTestsandAnalysis”,TobesubmittedtoJournalofHazardousMaterials.

• Rana,M.A.,Y.Guo,etal.(2010)."UseofwaterspraycurtaintodisperseLNGvaporclouds."JournalofLossPreventionintheProcessIndustries23(1):77‐88

• Rana,M.A.andM.S.Mannan(2010)."ForceddispersionofLNGvaporwithwatercurtain."JournalofLossPreventionintheProcessIndustries23(6):768‐772.

• G.Yun,W.Rogers,M.S.Mannan(2009)“RiskassessmentofLNGimportationterminalsusingtheBayesian–LOPA methodology”,JournalofLossPreventionintheProcessIndustries22,91–96

• Yun,G.,D.Ng,etal.(2011)."KeyFindingsofLiquefiedNaturalGasPoolFireOutdoorTestswithExpansionFoamApplication."Industrial&EngineeringChemistryResearch50(4):2359‐2372.

• Yun,G.,D.Ng,etal.(2011).“KeyObservationsofLiquefiedNaturalGasVaporDispersionFieldTestwithExpansionFoamApplication”Industrial&EngineeringChemistryResearch50 (3),pp1504–1514

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Publications• Kim,B.K.,Ng,D.,Mentzer,R.A.,&Mannan,M.S.(2012).ModelingofWater‐SprayApplicationinthe

ForcedDispersionofLNGVaporCloudUsingaCombinedEulerian–Lagrangian Approach.Industrial&EngineeringChemistryResearch,51(42),13803–13814.

• Kim,B.K.,Mentzer,R.A.,&Mannan,M.S.(2014).NumericalstudyonphysicalmechanismsofforceddispersionforaneffectiveLNGspillmitigation.IndustrialandEngineeringChemistryResearch,53(22),9488–9498.

• Kim,B.K.,Ng,D.,Mentzer,R.A.,&Mannan,M.S.(2013).KeyparametricanalysisondesigninganeffectiveforcedmitigationsystemforLNGspillemergency.JournalofLossPreventionintheProcessIndustries,26(6),1670–1678.

• Gopalaswami,N.,Laboureur,D.M.,Mentzer,R.A.,&Mannan,M.S.(2016).Quantificationofturbulenceincryogenicliquidusinghighspeedflowvisualization.JournalofLossPreventionintheProcessIndustries,42,70–81.

• Gopalaswami,N.,Mentzer,R.A.,&SamMannan,M.(2015).Investigationofpoolspreadingandvaporizationbehaviorinmedium‐scaleLNGtests.JournalofLossPreventionintheProcessIndustries,35,267–276.

• Gopalaswami,N.,Vechot,L.,Olewski,T.,&Mannan,M.S.(2015).Small‐scaleexperimentalstudyofvaporizationfluxofliquidnitrogenreleasedonice.JournalofLossPreventionintheProcessIndustries,37,124–131.

• Ahammad,M.,Liu,Y.,Olewski,T.,Vechot,L.,&Mannan,M.S.(2016).ApplicationofComputationalFluidDynamics(CFD)inSimulatingFilmBoilingofCryogens.Industrial&EngineeringChemistryResearch,acs.iecr.6b01013.

• Ahammad,M.,Olewski,T.,Vechot,L.,&Mannan,M.S.(2016).ACFD basedmodeltopredictfilmboilingheattransferofcryogenicliquids.JournalofLossPreventionintheProcessIndustries44,247‐254

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Publications• Zhang,B.,Liu,Y.,Olewski,T.,Vechot,L.,&Mannan,M.S.(2014).Blanketingeffectofexpansionfoamon

liquefiednaturalgas(LNG)spillagepool.JournalofHazardousMaterials,280,380–388.• Zhang,B.,Harding,B.,Liu,Y.,&Mannan,M.S.(2016).LiquefiedNaturalGasVaporHazardMitigation

withExpansionFoamUsingaResearch‐ScaleFoamGenerator.IndustrialandEngineeringChemistryResearch,55(20),6018–6024.

• Harding,B.,Zhang,B.,Liu,Y.,Chen,H.,&Mannan,M.S.(2016).Improvedresearch‐scalefoamgeneratordesignandperformancecharacterization.JournalofLossPreventionintheProcessIndustries,39,173–180.

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Conclusions

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Understand complex phenomena of LNG vapor dispersion and 

pool fire

Understand complex phenomena of LNG vapor dispersion and 

pool fire

Understand water curtain mechanisms to disperse the LNG 

cloud

Understand water curtain mechanisms to disperse the LNG 

cloud

Understand the mitigation effect of foam on LNG vapor and fire scenarios

Understand the mitigation effect of foam on LNG vapor and fire scenarios

Assess the risk of LNG overtopping and provide recommendations for 

dike design

Assess the risk of LNG overtopping and provide recommendations for 

dike design

Understand the LNG spill phenomena and develop accurate source term and pool spreading model

Understand the LNG spill phenomena and develop accurate source term and pool spreading model

Acknowledgements• Dr.BinZhang• LNGSafetyTeamofMKOPSC

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Thank you!

Questions and Comments?