特高压GIL管廊竖井中SF6泄漏特性的数值模拟研究

Numerical Simulation Study on SF6 Leakage Characteristics in Shaft of UHV GIL Pipe

SF6气体作为管廊事故泄漏的隐患,目前在工程中受到越来越多的关注。由于管廊运输距离远、结构复杂,采用试验测量的方法可行性差,故采用数值模拟的方法进行研究。文中针对气体绝缘输电线路(gas insulated transmission line,GIL)管廊中的事故泄漏工况,考虑自然对流,进行三维建模,利用有限元计算进行了管廊竖井内SF6时间及空间分布特性的数值计算研究。结合苏通GIL综合管廊工程特点,研究了泄漏气体在管廊竖井内的空间分布特性,不同风速对泄漏气体排出时间的影响,以及在一定泄漏时长内竖井空间截面处气体体积分数的变化规律。结果表明:泄漏持续时,泄漏口附近体积分数最高,管廊左右两侧的竖井的SF6体积分数明显高于其他区域;泄漏气体在重力及主流作用下,团状高体积分数泄漏气体向竖井后下方转移;不同风量条件下,SF6体积分数分布基本相同;泄漏前期竖井最高体积分数迅速下降,泄漏后期体积分数缓慢下降;风机台数越少,SF6体积分数降至阈值以下需要时间更长。

SF6 gas,as a hidden danger of pipe leakage,has attracted more and more concern in engineering.The numerical simulation method is adopted for the study due to long transmission distance and complicated structure of the pipe and weak feasibility of the test and measurement method.For the accident leakage condition in the gas insulated transmission line(GIL)pipe,the 3-D model is set up by considering natural convection and the numeral calculation study of time and spatial distribution feature of SF6 in the pipe shaft by the use of definite element calculation.The spatial distribution feature of the leakage gas in the pipe shaft is studied with combination of the project feature of Sutong GIL integrated pipe.The influence of different wind speeds on the discharge time of the leaking gas and the variation rule of the gas concentration at the spatial section of the shaft in a certain leak time are also studied.It is shown by the result that in case of continuous leakage,the concentration near the leakage port is the highest,and the SF6 concentration of the shaft on the left and right sides of the pipe is significantly higher than that of other areas.Under the action of gravity and mainstream,the leakage gas with high concentration is transferred to the lower rear of the shaft.Under different air volume conditions,the concentration distribution of SF6 is basically identical.The high・est concentration of the shaft decreases rapidly in the early stage and gradually in the later stage.The small the number of fans is,the longer it takes for the SF6 concentration to fall below the threshold.