Method and device for determining relative gas concentration of hydrogen-doped natural gas long-distance pipeline

The invention relates to the field of oil and gas storage and transportation, in particular to a natural gas hydrogen-doped long-distance pipeline gas relative concentration determining method and device. The method comprises the following steps: determining the relative concentration of hydrogen at a certain height position in the pipeline according to the molecular mass, temperature and Boltzmann constant of hydrogen and the absolute concentrations of natural gas at different height positions in the pipeline; based on molecular dynamics, hydrogen concentration distribution under different gravitational accelerations and different height conditions is simulated, and the simulated relative concentration of hydrogen at a certain height position in the pipeline is obtained; a diffusion equation considering gravity field correction is constructed, and the relative concentration of hydrogen changing along with time is determined; and comprehensively determining the relative concentration of the hydrogen at a cert