A case study of fire and explosion risk at hydrogen facilities, an ignition probability study

Abstract

Hydrogen is an essential energy carrier, making it very important for the global energy decarbonization process. Because of limited knowledge of ignition mechanisms, its elevated ignition risk compared to other gases present is a big issue for safety design. This can result in expensive over-caution or insufficient safety precautions, which can compromise the successful deployment of renewable energy solutions. The SAFEN JIP (Safe Energy Carriers) was made to address these knowledge gaps. The primary aim of the SAFEN model is to calculate realistic ignition probabilities for quantitative risk analysis (QRA) in facilities that handle hydrogen. To achieve this, the model needs to be tested to evaluate its performance and efficacy. This involves assessing how well the SAFEN model functions when applied to larger-scale geometries and more detailed scenarios.

In this thesis, the implementation of the SAFEN ignition probability model in the CFD software KFX-RBM is checked. KFX-RBM is further used to simulate hydrogen leaks in various geometries. The geometries used are a 40’ ISO container, a hydrogen refueling station, and a process plant. The geometries were simulated with two different leak rates, 0.1 kg/s and 1 kg/s, and the location of the leak varied from the middle to the corner of the geometry to see if it affected the total ignition probability. For comparison, simulations with methane leaks have also been performed. The simulation of the 40’ ISO container resulted in an ignition probability of 3.4 % for the 0.1 kg/s leak rate and 3.72 % for the 1 kg/s leak rate. For the hydrogen refueling station, the 0.1 kg/s leak rate gave an ignition probability of 3.48 %, while the 1 kg/s leak rate gave an ignition probability of 4.67 %. Finally, the process plant showed an ignition probability of 3.01 % for the 0.1 kg/s leakage and 5.66 % for the 1 kg/s leakage.

This thesis contributes to the knowledge of hydrogen ignition probability in various geometries and leak scenarios, presenting new information for improving safety precautions when handling hydrogen.