Modeling Formic Acid Combustion

Nowadays, the knowledge of the gas-phase chemistry of formic acid is paramount for several industrial sectors, including energy supply and the production of bulk chemicals. In this work, a simplified kinetic mechanism and a detailed kinetic mechanism deriving from a rate-based selection algorithm were developed and tested against experimental data available in the literature. The former contains 141 species and 453 reactions, whereas the latter comprises 90 species and 1047 reactions. A focus on a low initial temperature (i.e., up to 500 K) was provided by comparing the numerical estimations with laminar burning velocity and jet-stirred measurements at several conditions. A good agreement among numerical predictions and experimental data was observed, especially for the simplified kinetic mechanism. The accuracy of the generated mechanism allowed for further analysis of the chemistry of the system, enlightening some determining aspects of the chemistry of formic acid. The produced mechanism can be also intended as per seed mechanism for the generation of kinetic models focused on the chemistry of biofuels. Indeed, the characterization of chemical aspects of formic acid occurring in an oxidative environment is crucial due to its relevance as an energy vector as well as an intermediate compound in the decomposition of larger hydrocarbons and bio-oil

Report on LPG infrastructure impact at the WUI microscale

Preprin

Introduciendo factores externos de riesgo en el análisis de riesgo cuantitativo

El procedimiento convencional para la evaluación cuantitativa de riesgos de instalaciones industriales o áreas industriales, así como la planeación del uso de la tierra en relación a los principales peligros de accidentes deberían incluir escenarios de accidentes generados por factores externos de riesgos. En particular, el efecto dominó (también conocido como escalación  o  encadenados debido a i) lugares cercanos, ii) eventos naturales como terremotos o inundaciones, iii) maloperaciones internacionales que, principalmente, se da por  la interferencia de actos malintencionados. Una  perspectiva de estos problemas se mostrará a continuación y, a la vez, se discutirán los enfoques actuales y futuros disponibles para la evaluación cuantitativa  de estos factores externos de  riesgo en el marco de la evaluación cuantitativa de riesgos (QRA)

Cyber Threats in the Chemical and Process Industry

Presentatio

Idicadores intrínsicamente seguros para las explosiones en la industria de procesos

Los parámetros de seguridad de las sustancias inflamables, medidos por procedimientos estandarizados que, generalmente, se han adoptado para la definición de los índices de seguridad inherente, incluso  si las explosiones de gas industrial, de vapor  o de polvo, son motivo de preocupación. Sin embargo, es bien conocido que la naturaleza de los accidentes con explosiones  son más complejos  en la vida real, que los observados  en el laboratorio, bajo un ambiente controlado. Por otro lado, puede haber consecuencias mucho más severas, cuando se tienen  equipos de diseño o   dinámica de fluidos especiales.   Este trabajo propone nuevos indicadores  de seguridad inherentes a las explosiones basadas en los avances recientes en la seguridad de la combustión y  en las metodologías para el análisis de consecuencias

Hydrogen Refueling Stations: Prevention and Scenario Management. Large Scale Experimental Investigation of Hydrogen Jet-Fires

Hydrogen is becoming an attractive alternative for energy storage and transportation, because of the elevated energy content per unit of mass and possibility to have zero carbon-emission vehicles. For these reasons, hydrogen's share in global market is expected to grow substantially in the coming years. Today, hydrogen-fueled buses and cars are already available, and several refueling stations are operating in different countries around the world. A key role of the deployment of hydrogen fueled-vehicles is the presence of a widespread network of refueling stations, especially close to residential and industrial areas. This fact poses attention to the safety aspects related to hydrogen, with particular interest to its high flammability that can lead to catastrophic consequences for personnel and equipment. As a matter of fact, hydrogen is a comparatively less safe fuel compared to conventional fuels such as gasoline and diesel. Hydrogen infrastructures are characterized by operating pressure up to 1000 bar that, in case of an unintended loss of containments, produce a highly under expanded turbulent jet. If ignited, this hydrogen jet may give rise to very severe scenarios, mainly related to high temperatures and the oriented flows. As recently suggested by Moradi and Groth (Moradi and Groth, 2019), there is a lack of experimental and on-site data for almost all of the storage and delivery technologies relevant to the hydrogen infrastructures. Experimental data is vital to support model validation, especially in the case of the very peculiar combustion process of hydrogen. In this way, a real-scale experimental campaign is proposed to investigate the main characteristic of the hydrogen jet fire resulting from its rapid fired depressurizations. Focus of the experimental campaign is evaluation of safety distance for person and device (i.e. pressurized tanks) in order to avoid critical conditions and domino effects in real refueling station. Different initial conditions, i.e., storage pressures, are exploited, and the resulting jet across specified orifice is investigated. More specifically, temperatures at various locations are measured through an arrangement of thermocouples. Values up to 1200 °C were obtained in the core of the jet. Moreover, it was found that the recorded temperatures, especially those at the outer portion of the jet, are very sensitive to the initial conditions

Fragments Generated During Liquid Hydrogen Tank Explosions

Liquid hydrogen (LH2) may be employed to transport large quantities of pure hydrogen or be stored onboard of ships, airplanes and trains fuelled by hydrogen, thanks to its high density compared to gaseous compressed hydrogen. LH2 is a cryogenic fluid with an extremely low boiling point (-253°C at atmospheric pressure) that must be stored in double-walled vacuum insulated tanks to limit the boil-off formation. There is limited knowledge on the consequences of LH2 tanks catastrophic rupture. In fact, the yield of the consequences of an LH2 tank explosion (pressure wave, fragments and fireball) depend on many parameters such as tank dimension, filling degree, and tank internal conditions (temperature and pressure) prior the rupture. Only two accidents provoked by the rupture of an LH2 tank occurred in the past and a couple of experimental campaigns focussed on this type of accident scenario were carried out for LH2. The aim of this study is to analyse one of the LH2 tank explosion consequences namely the fragments. The longest horizontal and vertical ranges of the fragments thrown away from the blast wave are estimated together with the spatial distribution around the tank. Theoretical models are adopted in this work and validated with the experimental results. The proposed models can aid the risk analysis of LH2 storage technologies and provide critical insights to plan a prevention and mitigation strategy and improve the safety of hydrogen applications

Modelling of Fireballs Generated After the Catastrophic Rupture of Hydrogen Tanks

The interest towards hydrogen skyrocketed in the last years. Thanks to its potential as an energy carrier, hydrogen will be soon handled in public and densely populated areas. Therefore, accurate models are necessary to predict the consequences of unwanted scenarios. These new models should be employed in the consequence analysis, a phase of risk assessment, and thus aid the selection, implementation, and optimization of effective risk-reducing measures. This will increase safety of hydrogen technologies and therefore favour their deployment on a larger scale. Hydrogen is known to be an extremely flammable gas with a low radiation flame compared to hydrocarbons. However, luminous fireballs were generated after the rupture of both compressed gaseous and liquid hydrogen tanks in many experiments. Moreover, it was demonstrated that conventional empirical correlations, initially developed for hydrocarbon fuels, underestimate both dimension and duration of hydrogen fireballs recorded during small-scale tests (Ustolin and Paltrinieri, 2020). The aim of this study is to obtain an analysis of hydrogen fireballs to provide new critical insights for consequence analysis. A comparison among different correlations is conducted when predicting fireball characteristics during the simulation of past experiments where both gaseous and liquid hydrogen tanks were intentionally destroyed. All the models employed in this study are compared with the experimental results for validation purposes. Specific models designed for hydrogen can support the design of hydrogen systems and increasing their safety and promote their future distribution

The ARGO Project: assessing NA-TECH risks on offshore oil platforms

Abstract Analysis of natural and anthRopoGenic risks on Offshore platforms (ARGO) is a 3-years project, funded by the Italian Ministry of Economic Development. The project, coordinated by AMRA, a permanent Research Centre for the development of innovative technologies applied to environmental problems, aims at providing technical-support for the analysis of natural and anthropogenic risks on offshore oil-platforms. ARGO has developed methodologies for the probabilistic analysis of industrial accidents triggered by natural events (NA-TECH) on offshore platforms. The final analysis of the ARGO Project suggest a constant monitoring of exploitation activity, fluids re-injection and storage using high technology networks

Experiencia en cierre percutaneo de comunicaciones interarticulares en edad pediátrica guiado con sondas transesofágicas para adultos

La ecocardiografía transesofágica es un método de diagnóstico por imágenes ampliamente utilizado y recomendado como guía en el cierre percutáneo de una comunicación interauricular tipo ostium secundum.  En pacientes de edad pediátrica, se prefiere el uso de una sonda de tamaño apropiado que pueda ser insertada y manipulada con seguridad, y generalmente se aconseja el uso de sondas pediátricas en pacientes con pesos menores a 20 Kg.Estudio de serie de casos y observacional. Entre octubre de 2006 y diciembre de 2014, fueron intervenidos en nuestro Servicio 21 pacientes con comunicaciones interauriculares y pesos entre 15 y 20 kg. En todos ellos se utilizó sonda transesofagica para adultos. Los pacientes tenían una edad promedio de 5,09 años (rango 4-7 años) siendo el 90% de sexo femenino (19 pacientes). El peso promedio al momento del procedimiento fue de 18,37 kg (rango 15,1-20 kg). El tiempo que la sonda transesofágica estuvo colocada fue de 35,5 minutos (rango 21 -75 minutos). Se pudo completar el cierre percutáneo en todos los casos. Durante el procedimiento, a las 24 horas y a mediano-largo plazo, no se registraron complicaciones relacionadas al uso de sondas transesofágicas para adultos en estos pacientes pediátricos.De acuerdo a nuestra experiencia, el  monitoreo para cierre percutáneo de una comunicación interauricular tipo ostium secundum con sonda de ecocardiografía transesofágica para adultos en pacientes pediátricos con pesos entre 15 y 20 kg puede realizarse con seguridad y eficacia