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Transcript of 6 - Pasman
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LNG: Benefits and Risks, a European and
Dutch Perspective
Hans PasmanEmeritus Delft University of Technology, NL
Research Professor MKOPSC, Texas A&M
Benefits of LNG
LNG in Europe and in Rotterdam, the Netherlands
Example of Dutch QRA for license of terminal
Uncertainties in hazard and risk analysis
WCCE8, Montreal, Canada, 24-27 Aug 2009
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Benefits natural gas seen by Dutch eyes
1940s Cold winters, no gas, no heating
1950s Coal shoveling, few houses with central heating in the Netherlands
1960s Groningen gas; distribution network built
1970s Plans for terminal + tank ships but only peak shaving realized
1980s Continuous flow of income Dutch government; social security
1990s Ever higher efficient household heaters: central heating/hot water
2000s Alternative sources: Norway, Russia, LNG from other sources
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European terminals:
Graph according toWeems and Beck ofKing & Spalding, 2006
Spain, France andBelgium haveconsiderableexperience.
Delays in realization ofproposed terminals dueto long authorizationtrajectories and creditcrunch
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Rotterdam Rijnmond projects: GATE and LionGas
Maasvlakte at the mouth of the Nieuwe Waterweg, Hoek van Holland
4
Location Papegaaiebek
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Rotterdam GATE and LionGas terminal projectionsreproduced with courtesy to Port of Rotterdam
Design LNG terminals
Gate terminal
LionGas terminal
Looking West towards North Sea Looking East towards city of
Rotterdam and industrial harbor area
Note the oil depots and chemical
plants
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Situation ship entry, separation dams, MaasvlakteNearest towns: Hook of Holland, Oostvoorne; beach recreational area
LionGas:Two terrain
parts, separated
by a PET plant,
connected by
pipelines.
2 km
LionGas
Port of Rotterdam port signposting system map 2005
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Actual situation
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Port of Rotterdam Ship admission policy
MARINinstitute and Delft University of Technologyconducted: Ship maneuvering and collision avoidance studies
Detailed investigation of consequences of collision on ship hulland damage to tanks
Results:
Optimization of routing system Rotterdam approach (model SAMSON)
Avoid cross-traffic at high speed
Policy plan with projection of three stages:
Stage 1 (gaining experience, 15 calls or half a year) LNG ships shallarrive between 0:00 4:00 A.M.
Stage 2 (100 calls or two years) more arrival windows
Stage 3 (final) LNG carrier considered as normal traffic
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License procedure LionGas terminal: Seveso II Directive.Safety report, incl standard QRA as part of Env. Impact Assessment
Submission of application to Competent authority: Prov. South-Holland, DCMR
(Rijnmond Central Environmental Protection Agency). License granted Sep 2006
Analysis of nautical grounding and collision risks performed by MARIN and DelftUniversity of Technology:
Event frequency by Ship Traffic Models (30 yr data + model SAMSON)
Penetration depth distribution by model MARCOL
QRA ofspills at ship maneuvering, berthing, unloading, terminal operations and
re-gasification carried out by Royal Haskoning: Purple Book for accident scenarios (today Bevi Manual + SAFETI-NL); safety measures
TNO EFFECTS 5.5 model for LNG spill and evaporation on water with check against
Sandia report 2004-6558
Gas dispersion: Heavy gas model (1st part); neutral gas (2nd part; Gaussian model)
RPT effects and BLEVEs disregarded
When LNG cloud with no confinement present: no overpressure, only fire or flash fire
Exceptions: limited amount of gas (1000 m3) can explode under unloading platform or at
re-gasification plant (15% methane-air; MEM strength 5)
Flame envelope determined by LFL contour at ignition
Heat radiation threshold for 100% lethality: 35 kW/m2
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Dutch risk acceptance criteria
Individual risk:
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Max Cred Acc (MCA), MNonCA and Domino effects:
1. MCA scenarios were calculated: IR and GR remained within limits.
2. MNCA (100 Fire, no effect Fire and explosion cause
damage
Propylene spheres, 450
tonnes, NEREFCO (now
BP) terrain
1150 BLEVE: 0.2 bar at 1036
m, see Purple Book,
2005, hence LNG tanksurvives
Possible damage, no
detailed investigation
Wind mill turbines Ca.100 Failure of blade; no
penetration of concrete
tank hull
Certainly damage
Helicopter platform pilots Location not
decided
Crash, pool fire 0.5 km
radius
Not determined
Mutual domino effects of LNG terminal/tanks with neighboring installations
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EIA with QRA resulted in granting of
license by Prov. South-Holland in 2006
The QRA report mentions
uncertainties but states that in case
of doubt a conservative solution was
chosen
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What about uncertainties in QRA?
EU benchmark project ASSURANCE 2000 has confirmed wide spread in QRA
results (orders of magnitude): scenarios large source of variability.
Largest and smallest 10-5
IR risk contour
Comparison of Group Risk results of 6 (experienced)
teams participating in the exercise.
Other sources dispersion and explosion models, and failure frequencies
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EU project ARAMIS tried to remedy scenario definition: bowties: FTA-CE-ET
Even then difficult to predict escalations: small fire large leak big
release; damaged tanks / ship hull presents confinement.
Can BLEVE be excluded?
Failure rates: Influences by management qualityand human error; data
availability including confidence intervals
Source terms, consequence models produce spread in results. Which model
is sufficiently accurate: (FLACS, LES), model certification?
Fire: SEP 250 kW/m2, decrease with scale?
Explosion effects: increase with scale?
What about uncertainties in QRA? (2)
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Uncertainty explosion effects:
Largest uncertainty is effect after delayed
ignition. Cold LNG vapor is not very reactive, but what
about scale effects?
Scale effects in VCE have been investigated in
the 90s MERGE, EMERGE, JIP with only
limited success (Buncefield VCE was again asurprise not a reactive substance, no wide
explosion limits, not much confinement). Do we
know all mechanisms involved?
Does CH4 differ that much from C4H10 or C8H18?
It differs quantitatively not qualitatively.
Reactivity, run-up distances, flame-turbulence
interaction
Many researchers feel that tests so far have
been on too small a scale: J HazMat 140 (2007)
1981 Coyote test: No flash-backto the source
yellow range:possibly heatexplosion
0 10 20 30 40 50 60 70 80 90 1000
10
20
30
40
50
60
70
80
90
1000
10
30
40
100
Propene C3H6 [Vol.-%]
N2[Vol
.-%] O
2[Vol.-%
]
stoich
iometricC3
H6+1.5
O2->
3CO
+3H2
stoichio
metric
C3H6
+3O2
->3CO
+3H2
O
stoichiometric
C3H
6
+4.5O2
->3CO2
+3H2O
range ofdeflagrative explosion,
5 bar abs, 200 C
rangeof
deton
ative
explosion
soot
isformedhere
(41vol.-%up
to75vol.-%
)
propene/air-mixtures
90
50
60
70
80
20
0 10 20 30 40 50 60 70 80 90 100
0
10
20
30
40
50
60
70
80
90
1000
10
20
60
70
90
100
Methane CH4 [Vol.-%]
N2[
Vol
.-%] O
2[Vol.-%
]
yellow range:possibly heatexplosion
80
50
30
40
methane/air-mixtures
stoichio
metric
CH 4
+2O
2->
CO2
+2H
2O
stoich
iometric
CH 4
+1.5O
2->
CO
+2H
2O
sootformation
starts
at55vol.-%CH4
range of detonativeexplosion
range
of
deflagrative
explosion,
5barabs,25
C
stoichi
ometri
cCH4
+0.5O2
->CO+
2H2
Project SAFEKINEX, 20 l vessel
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Conclusions The scale of LNG operations in the world is rapidly growing to fulfill the need of
energy supply. The process of liquefying, transportation, storage and re-gasification has been
so far without significant incidents and the technology is considered safe.
Risk assessments are conducted at various places building on existing
knowledge gained for a large part in the early 80s in relatively small scale tests.
Methane is a low reactive hydrocarbon but shows all the features of its fellowhydrocarbons when pressed hard enough.
In view of the huge quantities present and corresponding combustion energy
potential it is recommendable to test present assumptions in larger scale tests.
Scenarios should be thought through in a multi-disciplinary team with an open
mind and paying attention to possible escalation of at first insignificant failure.
High quality safety management offers of course good protection but we have
to safeguard against drift in organizations