Analyzing effective factors on leakage-induced hydrogen fires

Currently, novel energy resources are receiving increasing attention as a response to the limitation in fossil fuels as well as their adverse effects on human health. Hydrogen, one of the most abundant elements on the earth, can be regarded as a new energy source to replace fossil fuels. Therefore, safety assessment of the relating processes is very crucial by increasing use of hydrogen as a fuel source. In this regard, consequence analysis for risk assessment and power reduction is very important. The present study aims at modeling hydrogen dispersion along with consequence analyses for such events as jet fire and flash fire. The model was validated by using the data derived from a study on hydrogen leakage in supply pipelines in the laboratory of the University of Pisa. Modeling results reveal that ambient conditions will impose a milder impact on leakage consequences if internal pressure is high in release source. The safe distance was also estimated to be 14 m. Dispersion consequence modeling was performed, followed by the evaluation of the effect of environmental (i.e., stability, ambient temperature, surface roughness, wind speed, and humidity) and process (i.e., vessel temperature and pressure, leakage diameter, and releasing point height) parameters on maximum size flammable vapor cloud and maximum level jet fire radiation on the ground. The size of flammable vapor cloud (consequence dispersion index) and the maximum flux of radiation were affected by process parameters more than ambient parameters. Leakage diameter and the vessel pressure were found to have the highest impact on the operational parameters.