Recommendations on the prediction of thermal hazard distances from large liquefied natural gas pool fires on water for solid flame models.

Luketa, Anay

doi:10.2172/1011229

Cited by 3 publications

(7 citation statements)

References 20 publications

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“…Therefore, to ensure that any safety assessment did not under predict, it was recommended that LNG pool fires should be modelled with a much higher Surface Emissive Power (SEP) than previous models to account for the lack of smoke shielding compared to previous tests [4]. In addition, the recommendation by Luketa was to model the LNG fire above the whole spill area [7], because it was difficult to predict the extent of the non-burning region without a physical basis. In a later analysis, Luketa and Blanchat suggested that the non-burning region was partly due to a low Damköhler number, where fire extinguishment occurs because diffusion rates are similar or higher than chemical reaction rates necessary to sustain the fire at the pool fire edge [8].…”

Section: Introductionmentioning

confidence: 99%

Modelling large LNG pool fires on water

Betteridge

2018

Journal of Loss Prevention in the Process Industries

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There has been a rising demand for natural gas across the World. In many countries, this demand is being satisfied through an increasing number of marine LNG Carrier (LNGC) deliveries and hence there is a safety requirement to understand the consequences of significant accidents that could lead to the catastrophic failure resulting in a large spill of LNG in a harbor. The impact of thermal radiation on LNGCs, terminal facilities and the public outside the site fence-line from an LNG pool fire on water could extend a long distance according to current empirical models. The Phoenix pool fire experiments were conducted by Sandia laboratories to validate these models for large LNG spills on water. It was observed that the pool fire did not extend across the entire area of an 80 m diameter LNG pool. In addition, the flame height was greater than expected and there was very little smoke obscuration compared to the 35 m tests at Montoir. This combination of physical phenomena made it difficult to use existing models to predict the consequences of thermal radiation, especially when extrapolating to different and potentially larger spill sizes.A recent study using empirical analysis and CFD demonstrated that the thermal updraft of a large fire will drive an inward flow of air and natural gas from the non-burning region with a velocity greater than the burning velocity of the outwardly spreading pool fire. Medium scale tests using a 4 x 1 m LNG pool in a fire tunnel confirmed that an artificially generated air-flow of 2.8 m/s was sufficient to stop the flame spread across the pool and confirmed the previous analysis. This paper describes an empirical model that has been developed based upon this analysis to account for the reduced pool fire size and successfully model the larger flame height that was observed during the Phoenix test. An analysis of large spills using this model showed that the calculated flame view factor was significantly reduced compared to pool fire models that predict that the fire will extend across the whole spill surface. The paper will also discuss the effect of water on combustion and hence provide an explanation for the reduced smoke obscuration that was seen during the Phoenix tests.

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Section: Introductionmentioning

confidence: 99%

Modelling large LNG pool fires on water

Betteridge

2018

Journal of Loss Prevention in the Process Industries

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“…The 56 m test is the largest LNG pool fire performed on water or land to date. The details of the test series and recommendations for hazard analysis are provided in Sandia reports [4] [5]. In addition to the outdoor tests, an indoor test series was performed utilizing a 3-m diameter gas burner in order to develop a flame height correlation.…”

Section: Introductionmentioning

confidence: 99%

The phoenix series large-scale methane gas burner experiments and liquid methane pool fires experiments on water

Luketa

Blanchat

2015

Combustion and Flame

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This paper summarizes a series of large-scale outdoor and indoor LNG pool fire experiments conducted at Sandia National Laboratories in Albuquerque, New Mexico. Two outdoor LNG spills on water with resulting pool fires of 21 m and 56 m in diameter were conductedto improve hazard predictions by obtaining measurements of flame height, smoke production, and burn rate. The experimental data indicates that LNG pool fires on water display different behavior than those on land by producing less smoke. Surface emissive powers of up to 286 kW/m 2 , flames heights of up to 146 m, and burn rates of about 0.147 kg/m 2 s were measured. Discussion is provided on the observed behavior of the two outdoor tests with regards to smoke production, wind effects, and hydrate production. The large-scale indoor experiments used a 3-m diameter gas burner with methane fuel to assess flame height to fire diameter ratios as a function of nondimensional heat release rates for extrapolation to large-scale LNG fires. A flame height correlation was developed from this data.

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“…Scaling results from the analyses of Verfondern and Dienhart [22] we estimate this quantity of LNG would occupy a diameter of 14.0 m and the pool would last 12.3 seconds on the deck. If the fire column height were 87 m (shorter than for H2 because methane is less buoyant), then the flame surface, for this duration, would have an emissive power of 286 kW/m 2 , which is what has been measured in the Phoenix LNG pool fire tests [56].…”

Section: Pool Firesmentioning

confidence: 67%

“…The result of the instantaneous spill and ignition is to produce a very tall fire. Tall fires do exist, as shown in Figure 10 for a 10-m diameter LNG (consisting of 99% methane) pool fire from the recent Sandia Phoenix tests [56]. The average concentration of hydrogen within the 105 m tall and 15 m diameter combustion column would be 41.9%, well within the LFL -UFL range for hydrogen.…”

Section: Pool Firesmentioning

confidence: 93%

“…To bring together the concepts that have been discussed thus far for fuel buoyancy, pool formation, fuel combustion, and fire radiation, it is useful to compare and contrast two hypothetical accident scenarios where the entire 1200 kg LH2 fuel complement of the SF-BREEZE and the energy equivalent in LNG is instantaneously spilled and ignited on the Top Deck of the vessel. This is a pool fire scenario, which has been the subject of many studies given its importance in fuel and fire safety [52][53][54][55][56][57]. It was of initial interest to the SF-BREEZE project, because aluminum was used as the material for the Top Deck (to reduce weight), but aluminum is not a structurally strong as steel in traditional (diesel) fires, which initially raised some concerns.…”

Section: Pool Firesmentioning

confidence: 99%

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Comparison of the safety-related physical and combustion properties of liquid hydrogen and liquid natural gas in the context of the SF-BREEZE high-speed fuel-cell ferry

Klebanoff

Pratt

LaFleur

2017

International Journal of Hydrogen Energy

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We review liquid hydrogen (LH2) as a maritime vessel fuel, from descriptions of its fundamental properties to its practical application and safety aspects, in the context of the San Francisco Bay Renewable Energy Electric Vessel with Zero Emissions (SF-BREEZE) high-speed ferry. Since marine regulations have been formulated to cover liquid natural gas (LNG) as a primary propulsion fuel, we frame our examination of LH2 as a comparison to LNG, for both maritime use in general, and the SF-BREEZE in particular. Due to weaker attractions between molecules, LH2 is colder than LNG, and evaporates more easily. We describe the consequences of these physical differences for the size and duration of spills of the two cryogenic fuels. The classical flammability ranges are reviewed, with a focus on how fuel buoyancy modifies these combustion limits. We examine the conditions for direct fuel explosion (detonation) and contrast them with initiation of normal (laminar) combustion. Direct fuel detonation is not a credible accident scenario for the SF-BREEZE. For both fuels, we review experiments and theory elucidating the deflagration to detonation transition (DDT). LH2 fires have a shorter duration than energyequivalent LNG fires, and produce significantly less thermal radiation. The thermal (infrared) radiation from hydrogen fires is also strongly absorbed by humidity in the air. Hydrogen permeability is not a leak issue for practical hydrogen plumbing. We describe the chemistry of hydrogen and methane at iron surfaces, clarifying their impact on steel-based hydrogen storage and transport materials. These physical, chemical and combustion properties are pulled together in a comparison of how a LH2 or LNG pool fire on the Top Deck of the SF-BREEZE might influence the structural integrity of the aluminum deck. Neither pool fire scenario leads to net heating of the aluminum decking. Overall, LH2 and LNG are very similar in their physical and combustion properties, thereby posing similar safety risks. For ships utilizing LH2 or LNG, precautions are needed to avoid fuel leaks, minimize ignition sources, minimize confined spaces, 1

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Recommendations on the prediction of thermal hazard distances from large liquefied natural gas pool fires on water for solid flame models.

Cited by 3 publications

References 20 publications

Modelling large LNG pool fires on water

Modelling large LNG pool fires on water

The phoenix series large-scale methane gas burner experiments and liquid methane pool fires experiments on water

Comparison of the safety-related physical and combustion properties of liquid hydrogen and liquid natural gas in the context of the SF-BREEZE high-speed fuel-cell ferry

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