Hydrogen jet vapor cloud explosion: A model for predicting blast size and application to risk assessment

Abstract

Releases of hydrogen at elevated pressures form turbulent jets in unconfined & uncongested regions may trigger vapor cloud explosion (VCE) as well as jet fire hazards. In the case of a delayed ignition of an unconfined & uncongested jet the turbulence induced by the jet release can lead to flame speeds sufficient to produce damaging blast loads, even in the absence of confinement or congestion. The VCE hazard posed by such high‐pressure hydrogen releases is not well‐recognized. The authors have previously presented test data and computational fluid dynamic (CFD) modeling analyses which characterize high pressure hydrogen releases and the associated VCE hazard in unconfined & uncongested regions. The current paper provides an overview of this VCE hazard. It presents both CFD simulations and a new simplified method. The new method determines the blast strength based on a blast curve method (i.e., TNO multienergy or BST) with the strength index correlated to the mass flow rate of the accidental release. The paper discusses also the implications of such events for building siting analyses and risk assessments. © 2018 American Institute of Chemical Engineers Process Process Saf Prog 37:397–410, 2018

Gone with the wind: Ventjet is a new engineering model for atmospheric dispersion

“…The high-pressure hydrogen horizontal tests described above, Daubech et al 15,16 Additional FLACS modeling of ambient temperature 2 in. subsonic methane horizontal releases (294 K methane and air temperature, F stability 1.9 m/s, Surface roughness 0.18 m) has also been performed to further test the validity of the ground effect approach for modeling the ground effect, across a range of velocities at 10 and 226 m/s (Mach 0.02 and 0.5), Figures 13 and 14.…”

“…At further out locations, this would not have been true due to buoyancy and ground effects discussed later in this paper, where these test results are discussed in more detail. Figure 7 shows the comparison between the data, FLACS simulations16 and Ventjet modeling results. Ventjet with α 1 = 0.08 provides the best fit.…”

“…Left frame corresponds to the description of the experimental facility of Daubech 15,16 : the upper picture shows the experimental rig (including the gas reservoir storage and the release point), whereas the lower picture shows a sketch of the same experimental rig. The right frame shows the comparison between the experimental data, FLACS, and Ventjet modeling results…”

Stochastic modeling and analysis of vapor cloud explosions domino effects in chemical plants

“…More in general, the authors of [37] examine the effect of the geometrical shape of the flammable cloud on the explosion, analyzing a constant volume of clouds with different height-width ratios and length-width ratios. Other works, as in [13], focus on the prediction of the VCE blast resulting from the leakage of a specific material.…”

Risk Assessment Method Combining Independent Protection Layers (IPL) of Layer of Protection Analysis (LOPA) and RISKCURVES Software: Case Study of Hydrogen Refueling Stations in Urban Areas

“…Recently, various risk assessment software programs have been used to determine the safety distance and risk of explosion through simulation analysis studies on hydrogen facilities [22,23]. For example, a study was conducted to determine the safety distance of a hydrogen refueling station facility by calculating the jet flame length using HyRAM [24], and a study was conducted to identify and establish hydrogen explosion locations using the FLACS-CFD software [25]. In addition, studies have been conducted to analyze the damage effect of jet flames using Phast and Safeti [26,27].…”