Effect of Mixed Hydrogen Natural Gas on the Flow Field of Bypass PIG Using CFD

Hydrogen energy is a new growth point for building a green and low-carbon industrial system and creating industrial transformation and upgrading. Large-scale hydrogen energy supply faces problems, such as lack of infrastructure and high pipeline construction costs. These problems constrain the development of the hydrogen energy industry. Utilizing the existing natural gas pipeline network to mix hydrogen and transport it can improve energy utilization efficiency. Pipeline inspection gauges (PIGs) are widely used for cleaning and internally inspecting pipelines, which is particularly important for energy transportation. The behavior of a PIG in a pipeline is closely related to the transport medium. In this study, based on the GERG-2008 real gas model, a bypass PIG’s flow field simulation model was established according to the actual working conditions. The flow field and driving force of the bypass PIG were studied hydrogen-mixing ratios of 0%–30% in 5% increments. The results showed that under actual operating conditions, the gas flow velocity in the bypass of the PIG increases with increasing hydrogen-mixing ratio; the turbulence kinetic energy in front of the PIG increases, and the driving force of the PIG increases. The tube delivery temperature was positively correlated with the PIG driving force, and the bypass rate was negatively correlated with the PIG driving force. The results can guide the structural design of PIGs and guarantee the smooth running of the pipe cleaning work to ensure the smooth working of mixed hydrogen natural gas pipelines.