Qualitative risk analysis of the overhead hydrogen piping at the conceptual process design stage

摘要

Namie, which is a town in Fukushima prefecture in Japan, has started a green innovation project using hydrogen to eliminate CO2 release by 2050 and establish a zero-carbon city. One idea is to develop an overhead hydrogen piping, which is a low-pressure hydrogen supply system, in public spaces. To develop and implement the piping in Namie and other areas, it is important to both develop the process and perform the risk analysis during a preliminary process design stage. The purpose of this study was to qualitatively analyze and identify the critical risks and effective safety measures for the piping. A total of 183 accidental scenarios were identified by using a hazard identification study, and the preventive and mitigation safety measures were summarized. Hydrogen dispersion simulations revealed that low-pressure hydrogen dispersion leaking from small holes and fractured piping in public spaces could result in concerning risks depending on the leak size, direction, position, obstacles, and ignition source. In addition, a shutdown system of the piping was evaluated with a multiphysics modeling simulation, and its importance was discussed to proceed with detailed investigations. Finally, we suggested risk reduction measures based on the concept of inherent safety for the development of low-pressure hydrogen systems, and the findings can be applied to cases such as Namie. nbsp;(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.