燃气灰口铸铁管道风险评价及泄露扩散模拟

发布时间：2019-07-02 16:21

【摘要】：在我国城市燃气发展初期,因局限于当时的管道技术和管材的使用,灰口铸铁管被广泛使用。随着城镇燃气被置换为天然气以及城市建设的快速发展,灰口铸铁管因抗拉强度、抗弯曲能力较差,具有脆性缺陷,连续铸管工艺造成管材有沙眼、层皮、不圆等自身缺陷而引发的问题也越来越突出,加上施工质量和安全管理不到位,近几年,灰口铸铁管频繁出现漏气、断裂等现象。因此,燃气灰口铸铁管道的风险评价成为国内城市燃气管道安全研究的重点之一。本文将风险管理理论和现代综合评价理论相结合对燃气灰口铸铁管道进行风险评价。通过对灰口铸铁管道特性、事故的统计分析,对灰口铸铁管道失效风险进行辨识,确定影响管道的风险因素；选用专家评议法和管道指数评分法建立失效发生可能性的指标体系；选用层次分析法对指标权重进行计算；在管道失效后果严重性分析中,对可能波及的范围和程度进行分析,从中确定出管道事故后果严重性的各种指标。从而,建立了完整的燃气灰口铸铁管道的半定量风险评价体系。利用Fluent软件对燃气泄漏扩散过程进行了数值模拟。研究了泄漏口直径d、管道内压力p、风速v及风向对泄漏后果的影响。结果表明随着当量直径的增大、管道内压强的增大,释放量和爆炸危险区域均增大；外部风向的改变以及风速大小都直接影响甲烷的浓度分布,逆向风最为不利,其他方向的外来风都会加强甲烷的扩散,且风速越大扩散加剧。本论文不仅对燃气灰口铸铁管道风险进行了评价,并通过Fluent数值模拟对燃气灰口铸铁管道泄漏影响问题进行了深入研究,使燃气灰口铸铁管道事故后果影响因素中的泄漏影响更加直观具体,为燃气灰口铸铁管道泄漏事故的应急救援提供科学依据。
[Abstract]:In the early stage of urban gas development in China, ash cast iron pipe was widely used because of its limitation to the use of pipeline technology and pipe at that time. With the replacement of urban gas for natural gas and the rapid development of urban construction, gray cast iron pipe has more and more serious problems caused by its own defects such as trachoma, layer skin, non-circle and so on because of its tensile strength, poor bending resistance and brittleness defects. In addition, the construction quality and safety management are not in place. In recent years, gray cast iron pipe frequently appears air leakage, fracture and so on. Therefore, the risk assessment of gas gray cast iron pipeline has become one of the key points of urban gas pipeline safety research in China. In this paper, the risk assessment of gas gray cast iron pipeline is carried out by combining risk management theory with modern comprehensive evaluation theory. Through the statistical analysis of the characteristics and accidents of gray cast iron pipeline, the failure risk of gray cast iron pipeline is identified and the risk factors affecting the pipeline are determined. The index system of failure possibility is established by expert evaluation method and pipeline index scoring method, and the index weight is calculated by AHP. In the severity analysis of pipeline failure consequences, the scope and degree of possible contagion are analyzed, and various indexes of the severity of pipeline accident consequences are determined. Thus, a complete semi-quantitative risk assessment system for gas gray cast iron pipeline is established. The process of gas leakage and diffusion is simulated by Fluent software. The effects of leakage diameter d, pressure p, wind speed v and wind direction on the consequences of leakage are studied. The results show that with the increase of equivalent diameter, the pressure in the pipeline increases, the release amount and explosion risk area increase, the change of external wind direction and wind speed directly affect the concentration distribution of methane, the reverse wind is the most unfavorable, and the outward wind in other directions will strengthen the diffusion of methane, and the larger the wind speed is, the worse the diffusion of methane will be. In this paper, not only the risk of gas gray cast iron pipeline is evaluated, but also the influence of gas gray cast iron pipeline leakage is deeply studied by Fluent numerical simulation, which makes the leakage influence among the influencing factors of gas gray cast iron pipeline accident more intuitionistic and concrete, and provides scientific basis for emergency rescue of gas gray cast iron pipeline leakage accident.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU996

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