D2e.1 Hydrogen gas velocity in 16 bar grids

In this study, the risks of high-speed operation in future hydrogen networks were addressed. In particular for the future 16 bar(g) networks, the potential harmful effects were considered, not only in a relative manner (benchmark to previous operation with natural gas) but also in an absolute manner.

The pulsation, vibration and noise effects for hydrogen at increased flow velocity are comparable to operation with natural gas. However, while the source strength does not increase, an upward shift in frequency is observed. Field testing even indicates that vibration and radiated noise effects are more favourable with hydrogen. For hydrogen, the risks on flow-induced effects are considered manageable with existing industrial design codes and practices, up to flow speeds of 50 m/s. Beyond this limit, detailed analysis for flow-induced pulsation effects is recommended, to endorse the design. For intrusive equipment (e.g. thermowells), selection and design of hardware ‘fit-for-service’ in high-speed conditions remains mandatory.

Erosion can be a limiting factor for hydrogen transport, particularly when (continuous) high flow velocities are combined with high solid particle concentrations. However, overly conservative assumptions for flow velocity profiles and unrealistically high solid contents shall be avoided. In the present study, more realistic scenarios were developed, indicating upper limits for flow speed, for various realistic values of solid particle concentration. As a general remark, increased flow velocities can be accepted, provided that the hydrogen stream has minimal solid particle fouling. This shall be ensured by clear production and storage processes and adequate filtering. In particular, if solid particle concentrations do not exceed 1 mg/kg, an upper design limit for 50 m/s flow velocity is considered appropriate for 16 barg hydrogen networks.