Fire safety characteristics of natural gas with hydrogen admixture

The increasing pressure to decarbonise energy production leads to the need to use low or zero carbon fuels or energy carriers. One of the promising fuels of the future is hydrogen, which is carbon-free if renewable energy sources are used for its production. However, the capacity for hydrogen production is currently insufficient to make it applicable on a large scale. Adding hydrogen to natural gas allows for a reduced carbon footprint without costly modifications to pipeline distribution network. However, changing the composition of gas in transport and distribution facilities requires a thorough assessment of the impact on operational safety. Fire safety of flammable mixtures is commonly assessed on the basis of explosive limits and other parameters. Although methods are available to calculate these parameters based on the composition of the mixtures being evaluated, the final safety assessment should rely on actual measured values. The scope of this work is to determine the explosion limits of natural gas from the transit system and changes in the limits caused by the addition of hydrogen at the concentration levels of 10% and 20% (v/v). Obtained experimental results were further compared with theoretically calculated values. Attention was also paid to the change in maximum explosion pressure, maximum pressure rise rate and oxygen concentration limits (LOC). As a result, valuable data on the expansion of the explosion limits of natural gas after the addition of hydrogen are presented.