Study on leakage and ventilation scheme of gas pipeline in tunnel

Due to poor ventilation conditions in the tunnel, if gas pipeline leaks, the consequence of the accident will be more serious. Therefore, in order to avoid the explosion in the rush-repair process, the gas in the tunnel needs to be discharged. Thus, it is necessary to study the leakage law and ventilation scheme of gas in the tunnel. Based on the computational fluid dynamics (CFD) theory, this paper takes Yanyingshan tunnel of China-Myanmar gas pipeline for instance, Fluent software is used to establish the leakage model of the gas pipeline and fan model in the tunnel. The influence of different factors on the leakage diffusion law and the influence of fan locations and number of fans on gas concentration are analyzed. It can be concluded that: (1) Leakage location, leakage area and pipeline pressure have great influence on the gas leakage and diffusion, leakage hole direction and leakage form have little influence on the gas leakage and diffusion. (2) Set the block valve at both ends of the tunnel can effectively reduce the duration of leakage jet. (3) In order to make ventilation efficient, the fan should be arranged in a higher position and needs to be at a distance from the top of the tunnel. (4) Parallel use of two fans has better ventilation effect than single fan.