Hydrogen Ignitions – Wildly Differing Opinions, and Reasons Why Everyone Could Be Right

In collecting background material for the recent CCPS book “Guidelines for Determining the Probability of Ignition of a Released Flammable Mass”, the wide variability of experiences, opinion and data on the topic of ignition probabilities of hydrogen releases was striking.  This discord was apparent even for pure hydrogen; one can only imagine the complexities involved with ignitions of mixtures of hydrogen with hydrotreating feedstock, or ignitions of hydrogen-containing synthesis gas streams.  This paper discusses the literature on the subject, including experiments that suggest why people might reasonably have these vastly different views on the subject. Given that the range of opinions for a given situation commonly range from 1% to 100% probability of ignition, getting a better understanding of the phenomena is critical to providing better guidance for a variety of risk analyses such as Quantitative Risk Assessment (QRA) and Layers of Protection Analysis (LOPA).