Design and Effect Evaluation of a Hydrogen–Natural Gas Mixing Device at Jingbian Compressor Station

Hydrogen gas is an environmentally friendly alternative energy source with zero emissions, making it highly valuable for replacing fossil fuels and reducing carbon emissions. One effective method of transporting hydrogen gas is by injecting it into existing natural gas pipelines. In this research, we focus on the Jingbian compressor station. This station is used for hydrogenation, blending hydrogen with the natural gas flowing through the pipelines. We propose a suitable process for hydrogen blending and design a mixing device to facilitate this process. To evaluate the mixing effect of the blended gas, we conducted numerical simulations to analyze the velocity and concentration distribution along the continuous section of the hydrogen blending pipeline. The results indicated that achieving a hydrogen branch length of 1/2 the diameter of the natural gas main pipe and a hydrogen flowrate of 10% resulted in a nonuniformity of hydrogen concentration at L = 30D of less than 0.05. Furthermore, when the hydrogen concentration was set at 3%, 10%, and 30%, the hydrogen concentration in the cross section of the pipe gradually approached the expected concentration as the mixed gas flowed. It is worth noting that during transportation of hydrogen-containing natural gas to the outlet, the velocity distribution on the cross section remained asymmetric, potentially leading to measurement errors. However, the use of a flow conditioner resulted in a further reduction in hydrogen nonuniformity and minimized velocity fluctuations, resulting in a small and uniformly distributed flow, which is advantageous for accurate measurement and transportation purposes.