埋地热油管道停输后周围土壤温度场的数值模拟

为精确模拟管道周围土壤温度场,建立了埋地热油管道周围土壤温度场数学模型.在模型中,根据管外不同位置处土壤受热油管道散热影响的大小,将管外热影响区域简化为矩形并分为两部分,其中第一部分为距管外壁0.5 m内的环形烘干区域.针对该模型,编制了有限元程序计算管道周围土壤温度分布.计算结果表明,管外径426 mm、管内油温65.0℃、管道埋深处自然地温9.0℃时,矩形热影响区域的水平边界距管中心距离在13 m左右;若管道停输40 h,仅管道周围1.1 m内的土壤温度发生变化,为管道停输再启动的安全性评价提供了科学依据.

Numerical simulation of the temperature field in the soil around a buried hot oil pipeline after shutdown

The mathematical model of the temperature field in the soil around the pipeline is established in order to accurately simulate the temperature field.In the model,the thermal influence zone in the soil around the pipeline is simplified as a rectangle and it is divided into two parts.The first part is the dried annular region outside the pipeline whose thickness is 0.5 m.A finite element program is developed for solving this mathematical model.The calculation result of a case shows that,when the outside diameter of the pipeline is 426 mm,the temperature of the oil in the pipeline is 65.0 ℃ and the natural temperature of the soil at the depth of the pipeline axis is 9.0 ℃,the horizontal edges of the thermal influence zone are about 13.0 m from the pipeline axis,and the drop of soil temperature only occurs in the region of 1.1 m from the pipeline axis within 40 h after pipeline shutdown,which provides a reliable basis for the evaluation of the safety of the restart of buried waxy crude pipelines after shutdown.