05 04 Tom Blanchat Presentation

8/18/2019 05 04 Tom Blanchat Presentation

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By: ,

By: ,

17 th INTERNATIONAL CONFERENCE & EXHIBITIONON LIQUEFIED NATURAL GAS (LNG 17)

LNG SHIP INSULATION EXPERIMENTS USING

LARGE LNG POOL FIRE BOUNDARYCONDITIONSBy: Thomas Blanchat, Charles Morrow, and Michael Hightower

Sandia National Laboratories April 17, 2013

17 th INTERNATIONAL CONFERENCE & EXHIBITION ONLIQUEFIED NATURAL GAS (LNG 17)


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P rogram objective:Improve understanding of large LNG spills and

the impact on hazards to the public

Large LNG Pool Fires:Goal is to reduce uncertaintyin thermal hazard predictionsfor large-scale LNG pool fires(~100 m).

Cascading Damage:Goal is to assess cryogenicand thermal damage to anLNG ship from a spill event.

Synergy between testing andsimulation.

LNG pool fire test

CFD simulation of LNG pool fire,512 CPUs, 2.5 M elements

Experiment (land based)


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Large LNG Pool Fire Testing

• Conduct scaled fire height to diameter tests in controlled

conditions

• Construct a large experimental area to conduct up to 100m indiameter LNG pool fires on water

• Conduct large-scale LNG pool fire tests (30m, 70m, and 100mdiameter) to determine large LNG pool fire hazards, including:

– Large pool fire behavior, physics, and characteristics – Surface emissive power (flame radiant energy) – Fuel vaporization rate (pool size) – Flame height and diameter (view factor)

• From the test data obtained, obtain data to improve existing firemodels to enable better estimates of LNG pool fire properties andbehavior at scales of interest (up to 500 m diameter) with

complicated conditions and geometries


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Fire Dynamics at Large ScaleJP8 – 2 m (SNL) JP8

– 3 m (SNL) JP8 – 20 m (China Lake)

LNG - 10 m SNL 2005 LNG - 35 m 1987 Montoir 1987 LNG ~200 m

????

Methane has unique chemical reaction pathways resulting in an order ofmagnitude less soot production.


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Construction

LNG experiment site – West view – 9-6-2008


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Large Scale TestConfiguration

• polyurethane foam and concrete lined reservoir – 5.2 m liquid depth• aluminum cover with insulating concrete• aluminum discharge plugs mate with SS pipe flange/elbows• reinforced concrete pipes (91 m long) connect to spill diffuser• 6 ton winches open plugs

Urethane foam andcarbon mesh


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Large Scale Test Configuration

• 1250 m 3 capacity LNG reservoir• 120 m diameter water pool (2 m depth,

lined)• 3 discharge pipes (15 in, 24 in, 36 in)• spill diffuser at pool center• 11 m 3 capacity LN 2 trailer (inertion)

• Instrument towers (12) 110 m, 160 m, and210 m (from pool centerline)

• Data Acquisition Systems (5)• Reservoir

– Liquid level (1 pressure, 1 floats) – Temperature (8 TCs)

• Pool – Spill Area (overhead video (2) – Heat flux to surface (13 DFTs) – Water temperature (36 TCs)

• Plume – Height (12 cameras) (4 high speed, 2

infrared) – Spectrometers (4) (400-800 nm, 1300-

4800 nm) – Heat flux (radiometers: narrow-angle

(28), wide-angle (12)• Meteorology

– 3D ultrasonic wind speed/direction (4) – ambient pressure/temperature/RH (1)

N (340°

)

EW

S


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LNG Fire Dynamics at Large Scale

The pool diameter does not determine the flame width on open water.

LNG - 10 mSNL 2005

LNG - 21 m SNL2/2009

LNG - 83 m SNL12/2009

For the 10 m test:Spot SEP ave ~190 kW/m 2(optically – thin, radiation vectornot saturated)


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Surface Emissive Power vs. Pool DiameterHeavy Hydrocarbons Compared to LNG (with large scale test data )

1000

AccidentScale

On Land

TestScale

Dpool (m)

Dpool SEP(m) (kW/m 2)10 19021 27783 286*

LNG Test #1@SS (390-510s)Dpool 21 1 mW flame 22 3 mHflame 35 3 mBurn Rate 0.15 0.01kg/m 2sWind Speed 4.8 0.8 m/s

LNG Test #2@SS (250-300s)Dpool 83 4 mW flame 56 12 mHflame 146 8 mWind Speed 1.6 0.2 m/s


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LNG Cargo Tank Insulation Fire Damage Testing and Relief ValveCapacity Analysis


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Test Scope

• Review cargo tanker details that are susceptible to flame impingement and thermalinsult

• Capture the critical physics (to 1 st order) and simplify construction details to allowrepresentative testing between various types

• Obtain or determine thermal properties for prototypic materials – Small sample measurements of density, specific heat, thermal conductivity or data from manufacturer – Obtain prototypic insulation materials

• Perform insulation decomposition tests – Various cargo types (Moss and membrane) with various insulation systems – Comparable tests at medium scale – Data from tests will be used to develop/validate models for thermal simulations to inform of damage

potential at prototypic scale

• Perform experiments to address the concern that cryogenic insulation(installed to preserve the cold conditions of LNG cargo) could degrade in theevent of a large-scale LNG spill and fire.

• The degradation of the insulation systems could cause initially undamagedtanks to become damaged, resulting in additional spills and larger and/orlonger fires.

Methodology


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Cargo Tank InsulationSystems

Membrane-type tanker

PUF/PRF composite panel

Polystyrene panel

Moss-type tanker

Polyurethane panel


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Test Apparatus

Lamp Assembly (1 MW potential)

Test Assembly Enclosure(stainless steel members,Pyrotherm wall panels)


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Test Enclosure Test Assembly X-section(1 m x 1 m x ~2 m deep)

• 4 lamp holder assembly (1.2 m x 1.2 m)• insulation mask (heated area 864 mm x864 mm)• steel plate representing Moss weathercover or membrane outer hull (~16 mm,5/8

)• gap representing hold space or ballastspace (~1300 mm)• insulation system (membrane or Moss,~300-500 mm thick)•

Al tank (38 mm wall thickness, LN 2 filled)• top exhaust, N 2 purge

Radiantheat lamp

array

Inner hullsteel plate Insulation

system

LN2 tank Air gap

Outer hullsteel plate

No96 Composite

Polystyrene

MKIII

GTT (M b )


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GTT (Membrane)Panel Fabrication

No96 perlite-filled

plywood boxes

MK III polyurethane foam panels


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Moss PanelFabrication

-500

-400

-300

-200

-100

0

100

200

300

400

500

-500 -400 -300 -200 -100 0 100 200 300 400 500

h e i g

h t

( m m

)

width (mm)

1

4 6

5

3

2

-500

-400

-300

-200

-100

0

100

200

300

400

500

0 2 0 4 0 6 0 8 0 1 00 1 20 1 40 1 60 1 80 2 00 2 20 2 40 2 60 2 80 3 00 3 20

h e

i g h t

( m m

)

depth (mm)

PL3PL2PL1SL3SL2SL1 PL4 PL6PL5

PUF/PRFComposite

Polystyrene


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Test Assembly

Steel plateand mask

Water-cooled

radiometer

Lamps

insideenclosure

(removablepartial top for

inserting testpanel)


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Typical Test Data and Insulation Thermal Response

Pre-test Cooldown

Thermal Exposure and Insulation Response


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Summary of Test ResultsThe following key observations were made:

1. The steel plate acting as a weather cover or outer hull temperature approached

1100⁰

C and the insulation layers closest to the steel plate have reached 800⁰

C nearthe end of the test.

2. In general, there was negligible heat flux into the aluminum tank that represents thecargo tank during any of the tests. Only after the thermal front passed through thelayer closest to the aluminum tank was there an increase in flux.

3. The heat flux value shown into the LN2 tank were obtained using heat flux gaugesattached to the tank and by evaluating the change in the liquid nitrogen boil-off ratein the LN2 tank.

4. Actual heat flux data for each insulation system tested is proprietary.


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Potential for Overpressure or Thermal Damage to Adjacent Cargo Tanks - Moss

• In a 40 minute exposure, all of the styrene will vaporize.• Radiative heat flux from the ~1100 ⁰ C weather cover is greatly reduced

due to smoke production.• Participating media heat transfer and free convection heat transfer

analysis for a Moss LNG cargo tank, support a heat flux estimate of up to10 kW/m 2 onto the cargo tank.

• There is a minimal likelihood of a Moss LNG cargo tank being damagedfrom a fire due to vapor over pressurization.


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Potential for Overpressure or Thermal Damage to Adjacent Cargo Tanks - Membrane

• The outer hull steel and the inner hull steel will see temperatures close to1000ºC and 600ºC, respectively, significantly reducing structural integrity.

• However, the heat flux into the LN2 tank was very low, and the thermalwave for both membrane insulation systems had not reached the LN2tank at the end of the nominal 40 minute thermal tests.

• Pressure may rise in the inter-hull space (without venting, 1.5 barg in 30

min), slow enough that relief valves can protect this space.• Expansion of gases from thermally-decomposing materials will increase

pressure internal to the insulation systems; this pressure increase mayexceed the relief and venting capacity of this volume.

• It is likely that membrane tanks will distort during a large fire, based on

softening of the inner hull and pressure buildup from vaporization of theinsulation system producing pressure sufficient to deform the membrane.• However, we believe that distortion of the inner and outer hulls will be the

larger cascading damage driver, not the thermal and pressure integrityperformance of the cargo tank insulation system.


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Summary

All insulation systems showed some degradation, and some showed better performancethan others. The smallest heat flux at the aluminum tank containing liquid nitrogen (asurrogate for the LNG cargo tank) was ~0 kW/m 2. The largest heat flux at the aluminumtank was ~5 kW/m 2.

The following key observations were made:

1. Heat flux of ~5 kW/m2

will not cause high temperature/direct damage of the cargotank.2. LNG fire-induced boil off does not exceed the venting capacity of the cargo tank

relief valves.3. LNG-induced fire heat flux creates high temperatures (~1000-1100 ⁰ C) on the ship

steel.4. All insulation systems will see degradation and reduction in mechanical strength .5. LNG-induced high insulation temperature will lead to material pyrolysis,

degradation, and flue gas formation.


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05 04 Tom Blanchat Presentation

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