Abstract:
This study aims to clarify the methane emission characteristics and influencing factors at city gate stations. Using the High Flow Sampler (Hi-Flow) method, component-level methane emissions were measured on-site at 11 typical city gate stations. Statistical analyses were conducted to identify emission source composition and driving factors. Results indicate that valves and instruments are the primary sources of methane emissions at city gate stations, with a highly uneven distribution: components with emission rates above 1 mg/s account for only 2.78% of the total but contribute 89.65% of overall emissions. The estimated methane emission factor is 48.82 kg/(station·year) for city gate stations, significantly lower than comparable international values. Correlation analysis reveals that methane emission rates are highly associated with operating years and the number of components, but show weaker correlations with station scale and inlet pressure. These findings provide data support for local methane emission factor estimation and for the identification and targeted management of high-emission components at city gate stations.