The objectives of this Project are set out below:
- Investigation of flame arrestor development, (IGE/SR/22 requires flame arrestors to be used on vents that flow less than 10 m/s.) Investigations should be made to see if these need sourcing for hydrogen and if so, identifying where and how this can be done.
- Calculation of purge tables and purge calculators for hydrogen use as specified in ML2 and other SGN procedures.
- A purge vent design that is clearly different to a natural gas vent that can be used for hydrogen. The vent is not expected to include a flame arrestor but instead produce a flow speed sufficient to prevent burn back during a purge.
- Mitigating unwanted ignition mechanisms including non-sparking hand tools – review non-sparking tools used in the offshore environment and provide recommendations for H100
Benefits
The project will provide learning on the following topics:
- Flame arrestor development, (IGE/SR/22 requires flame arrestors to be used on vents that flow less than 10 m/s.) Investigations should be made to see if these need sourcing for hydrogen and if so, identifying where and how this can be done.
- Calculation of purge tables and purge calculators for hydrogen use as specified in ML2 and other SGN procedures.
- A purge vent design that is clearly different to a natural gas vent that can be used for hydrogen. The vent is not expected to include a flame arrestor but instead produce a flow speed sufficient to prevent burn back during a purge.
- Mitigating unwanted ignition mechanisms including non-sparking hand tools – review non-sparking tools used in the offshore environment and provide recommendations for H100.
Learnings
Outcomes
This project builds on work carried out to date and investigates equipment used to carry out purging of gas networks with a view to providing tooling for commissioning SGN’s H100 Fife project.
Key messages from the project are:
- Current procedures regarding flame arrestors can be kept for hydrogen.
- Purge tables have been produced giving recommended minimum purge speeds for methane and hydrogen according to the PE pipe diameters proposed in the H100 Fife project.
- A purge stack with additional features to assist with hydrogen purging has been developed in this project.
- Current recommendations from SGN’s mainlay procedures on non-sparking tools and ignition prevention will be suitable for hydrogen use.
- A preliminary investigation into the consequences of in-pipe ignitions has been carried out.
- The hazards presented during purging are ignition of the vent, in-pipe ignition and burn back from a vent ignition into the pipe. Although none of these events are likely to occur, ignition of the vent is the most likely and the consequence of this is similar with hydrogen and methane.
Lessons Learnt
This project aimed to provide additional evidence for direct purging hydrogen which may be utilised in the H100 Fife neighbourhood trial. There were no significant problems encountered during this project. Commissioning of the H100 Fife trial will provide further evidence on direct purging hydrogen in real conditions. Based on the evidence from the related project Hypurge and this subsequent project, it is likely direct purging can be deployed on a large scale.
