(41z) Emergency Block Valve Analysis Using Quantitative Bowtie

Hydrogen is a strong candidate for fueling the Green Energy transition. Hydrogen, like all stores of potential energy, can be dangerous if not handled properly. The most common, and rapidly growing, source of green hydrogen is electrolysis of water. Electrolyzers split the benign water molecule into flammable/explosive hydrogen and concentrated oxygen which can oxidize any nearby material that is susceptible to this common reaction. If the gases that are either generated, or used as a utility, in the electrolysis process escape, a hazardous condition can be generated which may have significant safety consequences. As a result, a commonly employed safeguard is gas detection with automatic shutdowns. This paper will present an overview of the hazards of hydrogen generation through electrolysis, and then presents a case study of the design of a gas detection system for an electrolyzer test facility. The design of the gas detection system included using gas detection mapping approaches from ISA TR 84.00.07 for placement of the required detectors along with use of IEC 61511 for the design of the associated automatic shutdown of the electrolyzer and return to a safe state.