A Large Scale Study of the Venting of Confined Explosions into Unobstructed and Congested Flammable Vapour Clouds

Tomlin, GB; Johnson, M. M.

doi:10.3850/978-981-07-5936-0_11-01

Cited by 4 publications

(5 citation statements)

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“…Tomlin and Johnson, 2013), we have strong reasons to believe that DDT also took place for several of the other major industrial vapour cloud explosions, even if accident investigations do not conclude there was DDT, or details have not yet been made public. In fact, given that a strong deflagration requires high flame speeds close to or above the ambient speed of sound and the experimental evidence indicates that transition to detonation is then a very likely outcome, it is hard to conceive of DDT not occurring in most cases.…”

Section: Introductionmentioning

confidence: 92%

Improved far-field blast predictions from fast deflagrations, DDTs and detonations of vapour clouds using FLACS CFD

Hansen¹,

Johnson

2015

Journal of Loss Prevention in the Process Industries

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Section: Introductionmentioning

confidence: 92%

Improved far-field blast predictions from fast deflagrations, DDTs and detonations of vapour clouds using FLACS CFD

Hansen¹,

Johnson

2015

Journal of Loss Prevention in the Process Industries

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“…The flame speed and the shape of the flame front at entry into the congestion can have a significant effect on the explosion severity, cf. the observations by for example Cronin & Wickens (1986), Tomlin & Johnson (2013) and Davis in the RPSEA II project (S. Davis, private communication, 2019). This effect seems to be present in the tests with medium congestion in Fig.…”

Section: Overview Of Resultsmentioning

confidence: 93%

Assessing the influence of real releases on explosions: Selected results from large-scale experiments

Hisken

Mauri

Atanga

et al. 2021

Journal of Loss Prevention in the Process Industries

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The research activities in the project Assessing the Influence of Real Releases on Explosions (AIRRE) included a unique series of large-scale explosion experiments with ignited high-momentum jet releases directed into congested geometries. The primary objective for the AIRRE project was to gain improved understanding of the effect realistic releases and turbulent flow conditions have on the consequences of accidental gas explosions in the petroleum industry, to develop methodology that can facilitate safe and optimal design of process facilities. This paper presents selected results from experiments involving ignition of a highly turbulent gas cloud, generated by a large-scale, pressurised release of natural gas. The paper gives an overview of the effect on maximum explosion overpressures of varying the ignition position relative to the release point of the jet and a congested region placed inside the flammable cloud, with either a high or medium level of congestion. For two of the tests involving a jet release and the medium congestion rig, the maximum overpressures significantly exceeded those obtained in a quiescent reference test. The paper presents detailed results for selected tests in the campaign. The effects on the relevant explosion phenomena from introducing initial turbulence, initial flow momentum and concentration gradients, as generated by the realistic release, are discussed.

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“…A series of large scale experiments involving the interaction of vented confined explosions with an external region of pipework congestion also showed evidence of DDT and the continued propagation of the detonation through unobstructed vapor cloud . This DDT occurred in both ethylene‐air and propane‐air experiments.…”

Section: Vapor Cloud Explosion Experimentsmentioning

confidence: 96%

Why DDT is the only way to explain some vapor cloud explosions

Johnson

Tam

2017

Proc. Safety Prog.

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The possibility that Deflagration to Detonation Transition (DDT) occurs in vapor cloud explosions (VCEs) in industrial accidents has generally only been recognized for very reactive fuels such as hydrogen and ethylene. Assessment of the explosion hazards and risks associated with less reactive fuels such as propane and other alkanes has generally been based around the assumption that, in practice, only a deflagration can occur. This has the benefit that the magnitude of the maximum hazard to surrounding areas is defined by the physical parameters of any congested process region and not by the extent of the vapor cloud, as would be the case if there was a sustained detonation. However, following the Buncefield incident in the UK in 2005, a considerable amount of effort was expended in explaining the major VCE that occurred. This initially involved gathering and interpreting the evidence from the incident but then extended to experimental and theoretical research over two phases and lasting five years. Further research since showed that DDT can be achieved within dense vegetation and regions of pipework with a relatively small extent (of the order of a few meters). The results from this project will be summarized, indicating why the only explanation that is consistent with all of the evidence is a DDT soon after ignition of the cloud, with a sustained detonation then propagating through the majority of the cloud. Reference will be made to other incidents where similar evidence was observed. Awareness of the significance of such evidence will be important in the investigation of future VCEs. In addition, the possibility of DDT needs to be recognized in the methodologies used to assess VCE hazards.

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A Large Scale Study of the Venting of Confined Explosions into Unobstructed and Congested Flammable Vapour Clouds

Cited by 4 publications

References 0 publications

Improved far-field blast predictions from fast deflagrations, DDTs and detonations of vapour clouds using FLACS CFD

Improved far-field blast predictions from fast deflagrations, DDTs and detonations of vapour clouds using FLACS CFD

Assessing the influence of real releases on explosions: Selected results from large-scale experiments

Why DDT is the only way to explain some vapor cloud explosions

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