Development of engineering tools for hydrogen risk assessment

La présente communication vise à décrire les différents outils développés par la R&D Air Liquide en réponse à un besoin des opérationnels quant à la disponibilité d’outils de calcul simples, précis et rapides aussi bien pour le dimensionnement d’applications que pour l’évaluation des risques et conséquences des activités industrielles en lien avec l’hydrogène. La méthodologie pour parvenir aux outils finaux répondant aux attentes des utilisateurs, de profil et d’activité variés, est présentée, ainsi que les approches analytiques sélectionnées.This communication aims at describing the different engineering tools developed by Air Liquide R&D to bring to operational simple, accurate and fast calculation tools, both for the design of applications and for risks and consequences assessment of industrial activities related to hydrogen. The methodology and the selected analytical approaches to build final tools answering to end-users expectations, with varied profiles and activities, are presented

Comparison of helium and hydrogen releases in 1 m3^3 and 2 m3^3 two vents enclosures: Concentration measurements at different flow rates and for two diameters of injection nozzle

International audienceThis work presents a parametric study on the similitude between hydrogen and helium distribution when released in the air by a source located inside of a naturally ventilated enclosure with two vents. Several configurations were experimentally addressed in order to improve knowledge on dispersion. Parameters were chosen to mimic operating conditions of hydrogen energy systems. Thus, the varying parameters of the study were mainly the source diameter, the releasing flow rate, the volume and the geometry of the enclosure. Two different experimental set-ups were used in order to vary the enclosure's height between 1 and 2 m. Experimental results obtained with helium and hydrogen were compared at equivalent flow rates, determined with existing similitude laws. It appears, for the plume release case, that helium can suitably be used for predicting hydrogen dispersion in these operating designs. On the other hand – when the flow turns into a jet – non negligible differences between hydrogen and helium dispersion appear. In this case, helium – used as a direct substitute to hydrogen – will over predict concentrations we would get with hydrogen. Therefore, helium concentration read-outs should be converted to obtain correct predictions for hydrogen. However such a converting law is not available yet

Equipment using a ''static-analytic" method for solubility measurements in potentially hazardous binary mixtures under cryogenic temperatures

International audienceA new apparatus designed to study, at cryogenic temperatures, thermodynamic equilibria of potentially explosive binary systems such as hydrocarbon-oxygen mixtures is described herein. This equipment has an equilibrium cell which was especially designed to minimize hazards while allowing accurate phase equilibrium measurements. Reliability of results, obtained with this equipment has been verified by working on the nitrogen-propane system, for which data are already available in literature, over a large range of compositions and at various temperatures. Four isothermal curves describing liquid phase com- positions at 109.98, 113.77, 119.75 and 125.63 K have been determined. Our experimental data are rep- resented within 2% in compositions and in pressures through the Peng-Robinson equation of state implying Mathias-Copeman alpha function and Huron-Vidal mixing rule. Comparisons to literature allow pointing out: good agreement is observed with Kremer and Knapp data (1983) while the three sets of Poon and Lu data (1974) presenting systematic positive deviation are consequently judged as suspicious

Study of potential leakage on several stressed fittings for hydrogen pressures up to 700 bar

International audienceIn order to improve risk analyses and influence the design of the future H2 systems, an experimental study on 'real' leaks qualification and quantification was performed. In H2 energy applications, fittings appeared as a significant leakage potential and subsequently explosion and flame hazards. Thus, as a part of the 'Horizon Hydrogene Energie' French program, four kinds of commercial fittings usually employed on H2 systems were tested thanks to a new high pressure test bench - designed, setup and operated by INERIS - allowing experiments to be led for H2 pressures until 700 bar. The fittings underwent defined stresses representative of H2 systems lifetime and beyond. The associated leaks - when existing - are characterized in terms of flow rate

Solubilité du propane dans l’oxygène liquide

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Equilibrium Data for the Oxygen + Propane Binary System at Temperatures of (110.22, 120.13, 130.58, and 139.95) K

This article is a part of the Sir John S. Rowlinson FestschriftInternational audience(P, x) vapor-liquid equilibrium (VLE) data for the (O2 + C3H8) binary system were measured using a “static-analytic” method coupled to a gas chromatograph analysis at temperatures of (110.22, 120.13, 130.58, and 139.95) K. Parameters of a proposed thermodynamic profile were adjusted on the basis of experimental VLE data determined in this work, allowing a complete isothermal phase diagram for this hazardous system to be obtained. The vapor-liquid-liquid equilibrium (VLLE) thermodynamic behavior was predicted by modeling and then confirmed by visual observations. On the basis of this work, solubility values of propane in liquid oxygen can be deduced for both the propane-lean and propane-rich liquid phases at temperatures above the melting temperature of pure propane. The device allowing these data to be measured for such a hazardous mixture is also presented, as are the accuracies of the measurements

Numerical modeling of a moderate hydrogen leakage in a typical two-vented fuel cell configuration

International audienceNumerical results are presented from two direct numerical simulations (DNS) where a moderate hydrogen leakage is modeled in a typical two-vented fuel cell configuration. The study mimics one of the experimental investigations carried out on the 1 m$^3$ enclosure with a leak flow rate of 10.4 Nl/min. The injection dimensionless Richardson number is at the order of unity and thus characterizes a plume flow which becomes turbulent due to gravitational accelerations. Two large exterior regions are added to the computational domain to model correctly the exchange between the in/out flows at both vents and the outer environment. Two meshes are used in this study; a first consisting of 250 million cells, while the second has 2 billion cells to ensure the fine DNS resolution at the level of Kolmogorov and Batchelor length scales. The high performance computation (HPC) platform TRUST is employed where the computational domain is distributed up to 5.10$^4$ central processing unit (CPU) cores. A detailed description of the flow structure and the hydrogen dispersion is provided where the sharp effect of the cross-flow on the plume is analyzed. Comparisons versus the experimental measurements show a very good agreement where both the bi-layer Linden regime and the maximal concentration in the top homogeneous layer are correctly reproduced by the DNS. This result is extremely important and breaks the limitations shown previously with statistical RANS approaches and LES models. This study can be considered as a good candidate for any further improvements of the theoretical industrial plume models in general, and for the estimation of the non-constant entrainment coefficient in particular

Preliminary Risk Assessment of Hydrogen Refuelling Stations in a Multifuel Context

International audienceThe MultHyFuel Project [1], funded by the Fuel Cells and Hydrogen Joint Undertaking (FCH JU), aims to achievethe effective and safe deployment of hydrogen as a net-zero alternative fuel, by developing a common strategyfor implementing Hydrogen Refuelling Stations (HRS) in multifuel context. The project contributes to theharmonization of existing regulations code and standards (RCS) for industrial applications by generatingpractical, theoretical and experimental data related to HRS, embedding regulatory and industrial stakeholdersto the project progress.This paper presents a preliminary risk assessment performed for three different hydrogen refuellingconfigurations, presented in project Deliverable 3.1 [2], each intended to be integrated into a multifuel station.In terms of the hydrogen refuelling configurations, we discuss the following points:• detail on typical components of hydrogen refuelling stations, such as compressor, high pressure bufferstorage, cooling system and dispenser,• different modes of supply of hydrogen (high-pressure storage (trailers or bundles), hydrogen production byelectrolysis, and stationary liquid hydrogen storage),• different operating conditions of the dispenser - i.e. flow and pressure - but only delivering compressedgaseous hydrogen.The objective of this preliminary risk assessment is not limited only to the identification of the major hazards -and the consideration of various prevention and protection measures specific to the hydrogen installation - butalso, the mitigation measures to limit the potential of domino effects due to the potential hazards from other fuelswithin the multifuel refuelling station. In this preliminary risk assessment, Hazards Identification (HAZID) forhydrogen was implemented following the three steps below:• the description of typical HRSs,• the characterization of the potential hazards (substance, process...),• and a previous H2 facility incident review to formulate lessons learned.This example preliminary risk assessment illustrates how potential major accident scenarios were identified,and presents proposed prevention or protection measures in order to reduce the occurrence of these scenariosand mitigate the escalation of hazardous events”. In addition, some prevention and protection measures wererecommended when it was not possible to determine if they were universally implemented in HydrogenRefuelling Stations. Finally, knowledge gaps for the determination of Hazardous Area Classifications, likelihoodof hydrogen leaks and extent of consequences were highlighted, in order to be analysed and investigatedexperimentally within future steps of the MultHyFuel Project [1]

Consequences of a 12-mm diameter high pressure gas release on a buried pipeline. Experimental setup and results

When considering the transportation of gas through high pressure pipeline and associated permitting, the 12-mm diameter breach is one of those commonly considered as accidental scenarios and the associated consequences must to be calculated for determining the required safety measures. Up to now this “12-mm” scenario was modeled at the convenience of each risk analyst with no certitude on the real behaviour of the gas in the soil for these types of releases. To obtain concrete information on the “12-mm” scenario considered as the sizing event for safety distances associated to a little breach due to corrosion for instance, AIR LIQUIDE, ENGIE, NATIONAL GRID, PETROBRAS and TIGF decided to launch in 2013 a JIP (Joint Industrial Program) named “CRATER”. The aim of this project was to improve knowledge on the consequences of leakages occurring on buried high pressure pipes, and to determine what were their behaviour and their impact on the soil – i.e. crater formation, or not, according to release parameters – in order to use the appropriate methodology for risk and consequences assessment. Thus by changing several parameters – like nature of gas, initial gas pressure, type of soil … – the threshold between crater formation and gas dispersion in the soil following such leakages was investigated (specifically for methane and hydrogen, flammable and light gases). INERIS was chosen as subcontractor to perform nearly-full scale tests on its experimental site in order to collect reference data, understand phenomena and correctly assess the gas behaviour for accurate risk evaluation

GUIDELINES AND RECOMMENDATIONS FOR INDOOR USE OF FUEL CELLS AND HYDROGEN SYSTEMS

Hydrogen energy applications often require that systems are used indoors (e.g., industrial trucks for materials handling in a warehouse facility, fuel cells located in a room, or hydrogen stored and distributed from a gas cabinet). It may also be necessary or desirable to locate some hydrogen system components/equipment inside indoor or outdoor enclosures for security or safety reasons, to isolate them from the end-user and the public, or from weather conditions. Using of hydrogen in confined environments requires detailed assessments of hazards and associated risks, including potential risk prevention and mitigation features. The release of hydrogen can potentially lead to the accumulation of hydrogen and the formation of a flammable hydrogen-air mixture, or can result in jet-fires. Within Hyindoor European Project, carried out for the EU Fuel Cells and Hydrogen Joint Undertaking safety design guidelines and engineering tools have been developed to prevent and mitigate hazardous consequences of hydrogen release in confined environments. Three main areas are considered; Hydrogen release conditions and accumulation, vented deflagrations, jet fires and including under-ventilated flame regimes (e.g., extinguishment or oscillating flames and steady burns). Potential RCS recommendations are also identified.JRC.F.2-Energy Conversion and Storage Technologie