f SIF Beta Phase: Velocity Design with Hydrogen, WP2 - Particle Transportation Tests and CFD Modelling Results, Interim Report

This study conducted theoretical modelling and experimental work to investigate if there were differences in particle transportation behaviour in hydrogen compared to natural gas. It was found that both experimental data and predictions indicate that the majority of particles are currently mobile at the standard maximum natural gas velocity of 20m/s thus an increase in velocity to 70m/s with hydrogen should not result in an increase in particle transportation. The experimental observations are that natural gas can transport particles at lower velocities than hydrogen and this is thought to be due to the higher density of natural gas. The consequence is that at a velocity of 20m/s natural gas would transport all mobile particles as would hydrogen at higher velocities and this means that high velocity hydrogen cannot transport more particles already transported by natural gas.
Therefore, this study indicates that the mitigations, for example filtration requirements and engineering policies and procedures should be unaffected by changing to hydrogen as no change to particle loading is anticipated.
CONCLUSIONS
• Modelling has been undertaken to predict particle flight and rolling velocities in 100% hydrogen and 100% natural gas to support experiments.
    o Initial comparison between the CFD modelling and British Gas modelling indicates results are similar for both particle        rolling and flight velocities for 100% hydrogen at 2barg.
    o For 100% methane, the British Gas model results are 32-38% lower than those predicted by CFD modelling.
• Initial particle transportation experiments have been conducted using a purpose built test facility at Spadeadam to investigate particle transportation in 100% hydrogen and 100% natural gas at 2barg and 40mbarg.
    o Initial experimental results indicate that particle transportation occurred at lower velocities in natural gas than for             hydrogen.
    o From experimental data, rolling and flight of particles occurs over a range of velocities and there is not one specific velocity to instigate rolling or flight.
    o Tests were performed for services in hydrogen. However, a limited amount of sand was observed to travel up the service compared to the mains.
• Both experimental data and predictions indicate that the majority of particles are currently mobile at the standard maximum natural gas velocity of 20m/s (for unfiltered gas) thus an increase in velocity to 70m/s with hydrogen should not result in an increase in particle transportation.
• This study indicates that the mitigations used for natural gas should still be effective for hydrogen service
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.