Analysis of the screening of hydrogen flares and flames thermal radiation with water sprays

Water spray screening is a mitigation technique to reduce thermal radiation from flames to acceptable levels required by safety regulations. The current literature on water screening is limited to hydrocarbon flames. The main goal of the present study is to bridge this knowledge gap by presenting a methodology to predict the water spray screening performance of hydrogen flames using their actual emission spectra. A wide range of hydrogen flames and water screen scenarios are investigated. The results show that although hydrogen flames' emissivities are relatively lower than hydrocarbons', the radiated heat could pose safety risks and water screening is an effective mitigating method. The study further analyses the total transmissivity of water screens calculated from (i) the actual hydrogen spectrum and (ii) a blackbody spectrum. For optically thick spray screens, the blackbody spectrum widely used for hydrocarbon flames screening, could yield unacceptable overestimations of the total transmissivity.