IGEM/SR/23 Review of Thermal Radiation and Noise for Hydrogen Venting

IGEM/SR/23 (“Venting of natural gas”) provides recommendations for the conceptual design, operation and safety aspects of permanent, temporary and emergency venting of natural gas. The document was originally developed many years ago and the current edition dates to 1995. The document is due to be reviewed and updated for application to natural gas, but the aim of this study is not to review the applicability of the document for natural gas, but to assess the possible impact of 100% hydrogen on specific aspects of the existing guidance.
A key element of the guidance concerns the safe dispersion distances for natural gas, as vents are intended to provide a means of safely dispersing gas in the atmosphere, without ignition. Guidance on safe dispersion distances for venting are provided in Section 6.6, accompanied by graphs showing the relationship between the mass flow rate through the vent and the safe (horizontal) dispersion distance. Details of the model used to predict the dispersion distances are given in Appendix 1. However, for dispersion, the guidance in IGEM/SR/23 has been superseded by similar guidance on hazard distances for unignited releases in IGEM/SR/25 (“Hazardous area classification of natural gas installations”) [2]. A comprehensive review of the applicability of IGEM/SR/25 to hydrogen is already underway for the LTS Futures project and is not duplicated here.
However, IGEM/SR/23 contains guidance on other important aspects relevant to the safe design and operation of vents which are not addressed elsewhere in the IGEM suite of standards; in particular, guidance on hazard ranges for thermal radiation (in the event of an unplanned ignition of the venting gas) and noise.
The main aim of this report is to assess the potential impact of replacing natural gas with 100% hydrogen on the guidance in IGEM/SR/23 concerned with thermal hazards, with a secondary objective of assessing the available information to comment on the possible influence of hydrogen on noise.