Determination of the Optimal Blend Ratio of Hydrogen in Natural Gas System Using Physical Properties as Basis

Abstract

The Determination of the optimal blend ratio of hydrogen in natural gas systems using physical properties as a basis is an important research topic given the increasing use of hydrogen as an alternative fuel source. This research aims to determine the optimal blend ratio of hydrogen in a natural gas system using physical properties such as its Composition, Heating Value, Density, and Wobbe index as the basis of evaluation. Samples of consumer-grade Natural gas and clean Hydrogen gas were sourced in Nigeria. Both samples were used for blending and laboratory analysis. The blend volume ratios of Natural Gas (NG) and Hydrogen analyzed were 9:1, 8:2, 7:3, 6:4, & 5:5 using a Gasometer and Gas Chromatography Machine (CG). The experiment results provided valuable insights into the potential feasibility of replacing natural gas systems with a Hydrogen-Natural gas blend. The result obtained indicated about 2.06% reduction in percentage methane content, 26.35% reduction in gas density, 19.97% reduction in heating value (HHV), 5% reduction Wobbe index for every 10% increment of Hydrogen Ratio. This implies that blending carbon-neutral hydrogen gas into the natural gas systems for the purpose of decarbonization requires adequate compensation for expected changes in properties like heating value, flow dynamics, and process handling. The EUROMOT specification recommends that the percentage change in the wobbe index should be within the limit of +4% and -4% as an acceptable limit of interchangeability of fuel gas. Using the EUROMOT specification on Wobbe index, further numerical analysis affirmed that Natural Gas blended with as much as 25.74% Hydrogen can effectively be a substitute for fuel gas systems that are presently using Natural Gas.