Study On The Law Of Leakage And Diffusion Of Natural Gas Pipeline

As economic growth, the rapid growth of demand for natural gas in our country annually which promote the rapid development of the gas pipeline. And the importance of pipeline running safety is becoming more and more prominent. Due to the corrosion perforation, third-party damage and its own reasons, the operating pipeline often occurs gas leak in our country. Leakage can cause poisoning, fire, explosion and other accidents, endanger the safety of national energy transport, and lead to economic losses and casualties. Small hole leakage accounted for a large proportion among the leakage accident. However, at present, most detection method for detecting small holes with low accuracy. And missed or false detection often occur. Especially, because the environment is noisy, leakage signal is chaotic, it is difficult to detect for buried pipeline leakage. Therefore, the research on the laws of small leakage of gas pipeline can provide theoretical basis for scientific positioning, accident prevention and emergency rescue. It has great significance for the safe of pipeline and the protection of property.Firstly, based on percolation theory and diffusion theory, small leakage of the buried pipeline was analyzed in this paper. And the mathematical model of small hole leakage in the underground space was established. Besides, combined with the Fick diffusion theory,it also analysis the soil properties and soil properties on the influence of gas diffusion. Then, using dimensional analysis to solve the Fick diffusion model, it is concluded the gas diffusion concentration. It hope to reveal the law of the buried gas pipeline leak under different soil properties and rainfall environment, the research can lead to improve the safety of the pipeline transport. Finally, through example calculations, it draws the conclusion that the leakage aperture size, the moisture content of soil and the soil type are all important factors affecting the rue of diffusion. Moreover, the rate of diffusion is greater in more loose and more dry soil, and it takes shorter time for gas to spread to the ground and reach its explosive limits.In addition, this article also research the small hole leakage of overhead pipeline. The Gaussian model is solved, to explore the influence of leakage aperture, atmospheric stability, wind speed, pressure on diffusion of pipeline leakage. And using Fluent software to simulate small hole leakage of aerial pipeline under different leakage aperture, wind speed and leakage location. The results showed that the diffusion concentration is proportional to the pressure and aperture size; The wind speed up the gas diffusion; The more stable atmosphere, the less conducive to the spread; Obstacles affect the diffusion range seriously; Compared with the hole which on the top of pipeline, the leakage will lead to bigger harm when the hole on the below or on the sidewall surface of pipeline.