17 th INTERNATIONAL CONFERENCE & EXHIBITION ON 17 th INTERNATIONAL CONFERENCE & EXHIBITION LIQUEFIED NATURAL GAS (LNG 17) ON LIQUEFIED NATURAL GAS (LNG 17) LNG SHIP INSULATION EXPERIMENTS USING LARGE LNG POOL FIRE BOUNDARY <Title of Presentation> <Title of Presentation> CONDITIONS By: <Author Name>, <Organization> By: <Author Name>, <Organization> By: Thomas Blanchat, Charles Morrow, and Michael Hightower <Date> <Date> Sandia National Laboratories April 17, 2013
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 uncertainty in thermal hazard predictions for large-scale LNG pool fires (~100 m). Cascading Damage: LNG pool fire test Goal is to assess cryogenic and thermal damage to an LNG ship from a spill event. Synergy between testing and simulation. CFD simulation of LNG pool fire, 512 CPUs, 2.5 M elements Experiment (land based)
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 in diameter LNG pool fires on water • Conduct large-scale LNG pool fire tests (30m, 70m, and 100m diameter) 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 fire models to enable better estimates of LNG pool fire properties and behavior at scales of interest (up to 500 m diameter) with complicated conditions and geometries
Fire Dynamics at Large Scale JP8 – 3 m (SNL) JP8 – 20 m (China Lake) JP8 – 2 m (SNL) ???? LNG - 10 m SNL 2005 LNG - 35 m 1987 Montoir 1987 LNG ~200 m Methane has unique chemical reaction pathways resulting in an order of magnitude less soot production.
Construction LNG experiment site – West view – 9-6-2008
Large Scale Test Urethane foam and carbon mesh Configuration • 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
Large Scale Test Configuration S • Instrument towers (12) 110 m, 160 m, and 210 m (from pool centerline) • Data Acquisition Systems (5) • Reservoir – Liquid level (1 pressure, 1 floats) E – Temperature (8 TCs) • Pool W – Spill Area (overhead video (2) – Heat flux to surface (13 DFTs) – Water temperature (36 TCs) • Plume N (340 ° ) – Height (12 cameras) (4 high speed, 2 infrared) – Spectrometers (4) (400-800 nm, 1300- • 1250 m 3 capacity LNG reservoir 4800 nm) • 120 m diameter water pool (2 m depth, – Heat flux (radiometers: narrow-angle lined) (28), wide-angle (12) • 3 discharge pipes (15 in, 24 in, 36 in) • Meteorology • spill diffuser at pool center – 3D ultrasonic wind speed/direction (4) • 11 m 3 capacity LN 2 trailer (inertion) – ambient pressure/temperature/RH (1)
LNG Fire Dynamics at Large Scale LNG - 10 m LNG - 21 m SNL LNG - 83 m SNL SNL 2005 2/2009 12/2009 For the 10 m test: Spot SEP ave ~190 kW/m 2 (optically – thin, radiation vector not saturated) The pool diameter does not determine the flame width on open water.
Surface Emissive Power vs. Pool Diameter Heavy Hydrocarbons Compared to LNG (with large scale test data) Dpool SEP (kW/m 2 ) (m) On Land 10 190 21 277 * 83 286 LNG Test #1 @SS (390-510s) Test Accident D pool 21 ± 1 m W flame 22 ± 3 m Scale Scale H flame 35 ± 3 m Burn Rate 0.15 ± 0.01 kg/m 2 s Wind Speed 4.8 ± 0.8 m/s LNG Test #2 @SS (250-300s) D pool 83 ± 4 m W flame 56 ± 12 m H flame 146 ± 8 m Wind Speed 1.6 ± 0.2 m/s 1000 D pool (m)
LNG Cargo Tank Insulation Fire Damage Testing and Relief Valve Capacity Analysis
Test Scope • Perform experiments to address the concern that cryogenic insulation (installed to preserve the cold conditions of LNG cargo) could degrade in the event of a large-scale LNG spill and fire. • The degradation of the insulation systems could cause initially undamaged tanks to become damaged, resulting in additional spills and larger and/or longer fires. Methodology • Review cargo tanker details that are susceptible to flame impingement and thermal insult • Capture the critical physics (to 1 st order) and simplify construction details to allow representative 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
Cargo Tank Insulation Systems PUF/PRF composite panel Polystyrene panel Polyurethane panel Moss-type tanker Membrane-type tanker
Test Apparatus Test Assembly Enclosure (stainless steel members, Pyrotherm wall panels) Lamp Assembly (1 MW potential)
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) No96 Composite • insulation mask (heated area 864 mm x 864 mm) • steel plate representing Moss weather cover or membrane outer hull (~16 mm, 5/8 ” ) • gap representing hold space or ballast space (~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 MKIII Outer hull Inner hull steel plate steel plate Insulation system Radiant Polystyrene heat lamp array Air gap LN 2 tank
GTT (Membrane) Panel Fabrication MK III polyurethane foam panels No96 perlite-filled plywood boxes
Moss Panel Fabrication PUF/PRF Composite Polystyrene 500 500 SL1 SL2 PL1 PL2 PL4 PL5 SL3 PL3 PL6 400 400 300 300 5 2 200 200 100 height (mm) 100 height (mm) 0 1 3 0 -100 -100 -200 -200 -300 4 6 -300 -400 -400 -500 -500 -400 -300 -200 -100 0 100 200 300 400 500 -500 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 width (mm) depth (mm)
Steel plate and mask Water- cooled radiometer Lamps Test Assembly inside enclosure (removable partial top for inserting test panel)
Typical Test Data and Insulation Thermal Response Pre-test Cooldown Thermal Exposure and Insulation Response
Summary of Test Results The following key observations were made: 1. The steel plate acting as a weather cover or outer hull temperature approached 1100 ⁰ C and the insulation layers closest to the steel plate have reached 800 ⁰ C near the end of the test. 2. In general, there was negligible heat flux into the aluminum tank that represents the cargo tank during any of the tests. Only after the thermal front passed through the layer 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 gauges attached to the tank and by evaluating the change in the liquid nitrogen boil-off rate in the LN2 tank. 4. Actual heat flux data for each insulation system tested is proprietary.
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 to 10 kW/m 2 onto the cargo tank. • There is a minimal likelihood of a Moss LNG cargo tank being damaged from a fire due to vapor over pressurization.
Potential for Overpressure or Thermal Damage to Adjacent Cargo Tanks - Membrane • The outer hull steel and the inner hull steel will see temperatures close to 1000ºC and 600ºC, respectively, significantly reducing structural integrity. • However, the heat flux into the LN2 tank was very low, and the thermal wave for both membrane insulation systems had not reached the LN2 tank 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 may exceed 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 the insulation 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 integrity performance of the cargo tank insulation system.
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