HyPurge
The HyPurge project aimed to explore the comparative challenges in purging gas network pipes to hydrogen compared to purging to Natural Gas.
A comparative study has been carried out investigating the purging performance of hydrogen and methane on pipe diameters across the range of sizes to be used by SGN in the H100 Fife project.
Wealth of Data achieved
Over 750 direct purges, or purge related tests have been carried out during this project.
The most significant discovery of the project is that the very low density of hydrogen does not make direct purging between air and hydrogen impossible or even difficult. In many cases direct purging a system in like for like conditions is more efficient for hydrogen than for methane. At the time of writing, it is believed that this is due to the higher coefficient of diffusion for hydrogen.
Comparing the Purge
- Hydrogen purges are generally more efficient than Natural Gas purges - the total volume of air-fuel mixture created in a purge involving hydrogen is likely to be less than one involving Natural Gas.
- Hydrogen purges are generally more flammable than Natural Gas purges - the flammable volume of air-fuel mixtures created inside the pipe during a purge involving hydrogen is likely to be greater than one involving Natural Gas.
- The total volume of flammable air-fuel mixtures generated outside of the pipe during a purge involving hydrogen is likely to be less than one involving Natural Gas - the upper flammable limit does not prevent vented fuel becoming flammable once it mixes with air outside of the pipe.
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