PUBLICATIONS AND VIDEOS

SUMMARY

Dilution ventilation is the current basis of safety following a flammable gas leak within a gas turbine enclosure, and compliance requirements are defined for methane fuels in ISO 21789. These requirements currently define a maximum flammable gas cloud size within an enclosure, based on methane explosion tests conducted during a HSE Joint Industry Project. These tests involved igniting a stoichiometric mixture of methane and air at a range of volumes within a representative enclosure and measuring the resulting overpressure. The industry standard approach is to assess the ventilation performance of specific enclosure designs against these requirements using CFD modelling.

Gas turbine OEMs are increasingly considering introducing hydrogen/methane fuel mixtures and looking towards operating with hydrogen alone. It is therefore important to review the applicability of current safety standards for these new fuels, as the overpressure resulting from a hydrogen explosion is expected to be significantly higher than that from a methane explosion.

This presentation describes how we have replicated the previous methane explosion tests for hydrogen and hydrogen/methane fuel mixtures, using the explosion modelling tool FLACS. The results are used to propose updated limiting criteria for hydrogen fuels to support ventilation CFD analysis for specific enclosure designs.

This work is part of the deployment of a hydrogen adapted Centrax CX400 gas turbine package in support of the HYFLEXPOWER project. This is the world’s first power-to-hydrogen-to-power industrial-scale technology demonstrator, part funded by the European Commission through the Horizon 2020 framework.