埋地天然气管道泄漏扩散的模拟研究

发布时间：2018-06-19 10:38

本文选题：埋地天然气管道 + 气体泄漏扩散　；参考：《北京化工大学》2015年硕士论文

【摘要】：天然气的埋地管道运输现已成为最为便捷、经济的运输方式。但当埋地管道因土壤腐蚀、管道老化或者第三方破坏等原因发生穿孔泄漏时,不能及时探测到泄漏点的位置而影响抢险时间,因而探究埋地天然气管道的泄漏扩散规律对于泄漏点的准确定位、泄漏防范等都具有十分重要的意义。本文主要针对埋地天然气泄漏扩散规律进行研究,首先建立了埋地天然气在土壤中泄漏扩散模型,考察各种条件下扩散规律,并对泄漏扩散的影响因素做了详尽的分析讨论。得出以下结论：(1)在埋地天然气管道泄漏扩散模型,管道内径20mm,泄漏孔直径2mm,土壤孔隙率0.48,管道入口压力0.156MPa,泄漏孔处的泄漏量为2.25×104 kg·s-1。埋地的天然气管道在发生泄漏时,主要以渗流扩散的方式,其泄漏扩散云图近似一个圆形。通过对所建立的模型与公开文献中实验数据的对比分析,其相对误差分别在10.78%和26.67%,基本验证模型的准确性。埋地天然气泄漏量及扩散距离随土壤孔隙率、泄漏孔直径以及管道压力的增大而增加；泄漏孔形状对泄漏范围的影响从大到小依次为三角形、正方形、圆形；泄漏孔方向向下时的泄漏扩散距离较小；管道直径和管道埋地深度对泄漏量和扩散距离的影响较小。(2)拟合出埋地天然气泄漏孔泄漏量与管道压力、泄漏孔直径以及土壤孔隙率的关联式如下,其模拟值与拟合公式计算值之间的误差范围约±15%。(3)在上述的研究基础上,进而建立了埋地天然气离开土壤在大气中的扩散模型。模拟结果表明,风速对其纵向扩散距离具有先增加后减小的趋势,其横向扩散距离也有增加的趋势；当风速超过1.5mm·s-1时,高浓度区域都富集在地表附近；建筑物可以增加埋地天然气在大气中的纵向扩散距离,并且建筑物距离泄漏孔越近,其对天然气扩散的提升作用越明显；随着建筑物高度增加,天然气的纵向扩散距离具有先增加后减小的趋势,当建筑物高度在20m左右时对于气体的提升作用最明显。(4)建立了埋地天然气离开土壤后在城市某小区内的扩散模型。当发生埋地天然气泄漏时,天然气易于朝向较为空旷的地方扩散,2min以后其浓度为0.1%～1的扩散范围接近稳定；随风速增加,高浓度甲烷区域变小,其纵向扩散距离也随之减小。
[Abstract]:The buried pipeline transportation of natural gas has become the most convenient and economical transportation mode. However, when the buried pipeline is perforated and leaked due to soil corrosion, pipeline aging or third party damage, the location of the leak can not be detected in time and the rescue time will be affected. Therefore, it is very important to study the leakage and diffusion law of buried natural gas pipeline for accurate location of leakage point and prevention of leakage. In this paper, the laws of leakage and diffusion of buried natural gas are studied. Firstly, the model of leakage and diffusion of buried natural gas in soil is established, and the diffusion law under various conditions is investigated, and the influencing factors of leakage and diffusion are analyzed and discussed in detail. The following conclusions are obtained: (1) the leakage diffusion model of buried natural gas pipeline is: the diameter of pipeline is 20mm, the diameter of leak hole is 2mm, the porosity of soil is 0.48, the inlet pressure of pipeline is 0.156MPa, the leakage amount of leakage hole is 2.25 脳 104kg / s -1. When the buried natural gas pipeline is leaking, the seepage diffusion is the main way, and the leakage and diffusion cloud diagram is approximately a circular one. The relative error of the model is 10.78% and 26.67%, respectively. The accuracy of the model is basically verified by comparing the established model with the experimental data in the open literature. The leakage volume and diffusion distance of buried natural gas increase with the increase of soil porosity, leakage pore diameter and pipeline pressure, and the effect of leakage hole shape on leakage range is triangle, square and circular. The leakage diffusion distance is smaller when the leakage hole is downward, and the influence of pipeline diameter and buried depth on leakage volume and diffusion distance is smaller. The correlation formula of leakage pore diameter and soil porosity is as follows, the error range between the simulated value and the calculated value of the fitting formula is about 卤15. 3) on the basis of the above research, the diffusion model of buried natural gas leaving the soil in the atmosphere is established. The simulation results show that the vertical diffusion distance of the wind speed increases first and then decreases, and the transverse diffusion distance increases, and when the wind speed exceeds 1.5mm s-1, the high concentration area is concentrated near the surface. Buildings can increase the vertical diffusion distance of buried natural gas in the atmosphere, and the closer the building is to the leak hole, the more obvious the effect of building on the gas diffusion is; as the height of the building increases, The vertical diffusion distance of natural gas increased first and then decreased. When the height of the building was about 20m, the effect of gas lifting was most obvious. 4) the diffusion model of buried natural gas after leaving the soil was established. When the buried gas leak occurs, the concentration of natural gas tends to be 0.1%, and the vertical diffusion distance decreases with the increase of wind speed, and the diffusion range of gas tends to be stable after 2 minutes of diffusion to a relatively open place, and with the increase of wind speed, the area of high concentration methane becomes smaller, and the longitudinal diffusion distance decreases.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE88

【参考文献】