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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,[email protected]://process‐safety.tamu.edu
PHMSAGovernment&IndustryR&DForumCleveland,Ohio,November16‐17,2016
Outline• Introduction• LNGSafetyConcerns• LNGSafetyResearchOverview• AreasofStudy
– LNGVaporDispersionandPoolFireModelingwithCFD– LNGVaporCloudControlusingWaterCurtain– LNGVaporandFireMitigationusingExpansionFoam– ExperimentalStudyandCFD SimulationofBundOvertopping
– Source‐TermandPoolSpreadingofSpillonLandandWater
• Conclusions
2
Introduction• Liquefiednaturalgas(LNG):providesflexibilityinnaturalgasindustryfor
storageandinter‐regionaltrade– NewemergingnaturalgasmarketwillaccelerateLNGtradeglobally
• GrowingconcernsonpotentialLNGspillandconsequencearoundfacilities– FurtherresearchonLNGsafetyisrequiredtoensurepublicsafetyandsafeoperation
U.S.naturalgasproductionbysource(trillioncubicfeet)(source:EIA)
LNGimportandexportterminalsapprovedintheU.S.(source:FERC)
3
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
4
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
5
LNG Facility at TEEX• SevenseriesofLNGoutdoorspilltestshavebeenperformedsince2005atLNGtestfacilityattheBraytonFireTrainingField(BFTF)ofTexasA&M EngineeringExtensionService(TEEX),CollegeStation,Texas
6
• 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
8
LNG Vapor Dispersion and Pool Fire
• Field test setup
9
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
12
• LNGunderwaterrelease
Over‐the‐land video camera Underwater video camera
LNG Vapor Dispersion and Pool Fire
13
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
14
Controlling LNG Vapor Cloud using Water Curtain
• Watercurtainisconsideredoneofthemosteffectiveengineeringmethodsinmitigatingvarioustypesofhazards
• NodefinitiveandcomprehensiveguidelineforwatercurtaindesigninLNGvaporcontrol
• DeterminethekeyparametricdependenceofdifferentwatercurtainsincontrollingtheLNGvaporcloud
• Developaneffectiveengineeringguidelineforwatercurtainapplication
15
Controlling LNG Vapor Cloud using Water Curtain
16
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
17
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
19
High Expansion Foam
• upto20Lowexpansion
• 20to200Mediumexpansion
• 200to1000Highexpansion
HighExpansion
MediumExpansion
Vaporhazardmitigation Poolfirecontrol
Studyrequiredtounderstandthephysicalphenomenaanddevelopspecificguidelinesforfoamsystemdesign
Foam=Foamsolution+Air
NFPA11:StandardforLow‐,Medium‐,andHigh‐ExpansionFoam
20
LNG Vapor and Fire Mitigation using Foam
21
LNG Vapor and Fire Mitigation using Foam
22
LNG Vapor and Fire Mitigation using Foam
23
LNG Vapor and Fire Mitigation using Foam
24
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
25
Bund Overtopping• RolesofBund
– Secondarycontainment
– Limitcontamination
– Reducevaporization
– Controlpoolfireimpact
• CapacityofBund– ≥110%*tankcapacity
26
www.polystarcontainment.com
Scenario ‐ Catastrophic Tank Failure
27
Video– CFDSimulationonBundOvertopping incaseofcatastrophictankfailure.
Bund Overtopping
• Labtest
28
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
29
LNG Spill on Water
30
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
31
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
32
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
33
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.
34
Conclusions
35
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
36
37
Thank you!
Questions and Comments?