For the operation of local, regional, and national hydrogen networks, both in preparation for maintenance work or in case of emergencies, operators are required to purge pipeline sections of hydrogen. For safety and environmental reasons, flaring of hydrogen is preferred over venting, as venting hydrogen to the atmosphere should be minimized as much as possible. Research conducted within HyDelta 2 shows that the flaring installations currently used for this purpose produce nitrogen oxide emissions [1]. The hypothesis of this study is that controlled flaring installations can be used to reduce the amount of emissions. In the original project description, it was stated that the hypothesis would be tested using a commercially available controlled flaring installation. However, after an extensive market consultation it became clear that no such system was commercially available at the time of the study. To investigate the hypothesis nonetheless, a custom controlled flare installation was designed, built, and tested. This flare system uses a controlled burner that is normally applied in industrial environments. The results of the experimental tests demonstrate that such a burner can be used in a flaring installation to safely neutralize hydrogen from the network, with approximately a tenfold reduction in nitrogen oxide emissions. The addition of nitrogen does not necessarily have a negative impact on emissions. Flame stability remains acceptable up to a level of 34 vol% nitrogen in hydrogen. When the nitrogen content becomes higher, the burner safety system is triggered and the gas supply is shut off. Since the resulting mixture (of nitrogen, air, and hydrogen) is then below the flammability limit, the remaining volume can be safely vented—though this does result in hydrogen emissions. This report is written in a pyramid structure. The first two chapters present the results of the experimental research, distinguishing between the intended use of the flare setup for pure hydrogen combustion and the robustness of the setup for mixtures of hydrogen and nitrogen. The third chapter discusses the test setup, and the final chapter describes the findings of the search for a controlled flare system. The report concludes with a summary of the key conclusions and recommendations for potential follow‑up research.

Dit project is medegefinancierd door TKI Nieuw Gas | Topsector Energie uit de PPS-toeslag onder referentienummer TKI2023-HyDelta.