Research On The Leakage Of Buried Gas Pipeline And Diffusion Regularity

According to the requirements of "twelfth five-year" plan about natural gasdevelopment, natural gas consumption in China will reach230billion cubic meters in2015, and gas penetration will be further improved. According to the current policyabout utilization of natural gas and the demand on gas consumption market in China,natural gas pipeline construction will have an orgasm. Losses caused by leakage of gasand security problems, should be valued. In order to solve these two problems, the studyabout calculation of leakage and diffusion regularity are urgent issues. The purpose ofthis paper is to analysis the relationship between buried gas pipeline’s leakage and theoriginal formula of leakage, the diffusion regularity of leaking gas through soil and theinfluence of external conditions on the diffusion regularity.In the study of calculating of the leakage, the concept of soil density is introducedand the soil is divided into Natural soil, compacted soil and agglomerate soil. Under thecondition of three kinds of soil, determine the leakage of pipeline with different leakageaperture and under different working pressure, and compared it with the leakage ofordinary pipe, and the theoretical calculation values from original model. The leakage ofpipeline buried by compacted soil is less15%~25%than unburied pipeline. When thedensity of soil is larger and this soil is in a state of agglomeration, this number is about95%.In the research on diffusion regularity of leaking gas, recognize gas’s flow in thesoil as seepage theory. On the basis of having a strong understanding of Darcy’s law andthe theory of porous media, measure the internal resistance coefficient and viscousresistance coefficient of compacted soil and determine soil porosity.Regard leak model of gas pipeline in a typical road as example, establish physicalmodel, mesh, and get methane’s concentration distribution after simulating the leak of avariety of conditions with the use of CFD numerical simulation software. Analyze theinfluence that soil has on diffusion, and wind speed, temperature, buried depth and otherexternal conditions has on diffusion. We find that the leakage gas of buried pipeline ismore likely to be gathered and the risk area in higher methane concentration is bigger.Results can help engineers understand the laws of buried pipeline’s leakage gas and size according to the monitoring of methane concentration, approximately determiningdangerous range, thus more effective emergency rescue measures. In the last, the paperprospects the future work of this topic.