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RISK BASED SAFETYDISTANCES FOR HYDROGEN REFUELING STATIONS. Calculations in the Netherlands By: ir. Piet Timmers Ing . Gea Stam. Contents. History and project outline Calculating Safety Distances for HRS Results Conclusions. History and project outline.
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RISK BASED SAFETYDISTANCES FOR HYDROGEN REFUELING STATIONS Calculations in the Netherlands By: ir. Piet Timmers Ing. GeaStam
Contents History and project outline Calculating Safety Distances for HRS Results Conclusions
History and project outline • 2006: ‘Safety distances for hydrogen filling stations’Matthijsen, Kooi, J. of Loss Prevention in the Process Ind. • 2010: ‘Dutch practical guideline’ (NPR 8099) • 2015: PGS35: ‘Hydrogen; installations for delivery of hydrogen to road vehicles’. • 2014: European Directive for deployment of alternative fuel infrastructure (2014/94/EU) appropriate number of hydrogen refueling points. • 2014: “Dutch vision on a Sustainable Fuel Mix” • Intention Dutch Government: >20 public HRS in 2020
Calculating safety distances for HRS • 3rd Party Risk: Risk Based approach. • Rules: “Reference Manual Bevi Risk Assessments” • Locationspecific risk limit = 10-6 per year • Societal risk: indicative limit:
Calculating safety distances for HRS (assumptions) • Calculations based on 1000 kg hydrogen per day • For composite hoses a factor 10 lower failure rate is assumed for scenario ‘breaking of the hose’ (compared to Reference Manual) • 2 buffer storages for delivery are present: • one 440 bar (40 kg) • one 950 bar (20 kg) • Probability of direct ignition is 1 for release of gaseous hydrogen • Probability of direct ignition is 0.9 for release of liquid hydrogen • Weather conditions: mean value for the Netherlands • Discussion: Failure probability of automatic ESD: • Reference Manual: probability 0.001 per use, reaction time 120s • Advisory Board: probability 0.01 per use, reaction time 5s • All calculations done with SAFETI-NL 6.7
Calculating safety distances for HRS (steps) • Define all scenario’s that are relevant • Reference Manual defines the ‘General failure frequency’ • Define relevant factors like fraction per year available or length of pipelines • Calculate the actual failure frequency per year • Calculate the Risk Safety Distances
Conclusions • safety distances, based on PR 10-6 contour, for a HRS (1000 kg per day), is around 35 m. • However, large effect distance (1200m) for inst. release of tank car liquid hydrogen. • Scenario with large effect distance has low frequency (3.5·10-8 per year) so doesn’t contribute significant to safety distance. • Results are used by Dutch Government for prescription of a fixed set of safety distances for HRS. For supply of liquid hydrogen further research is anticipated.