Abstract: The low flow rate of crude oil pipelines is ubiquitous. When the transportation quantity becomes lower than allowed minimum quantity, intermittent transportation technique can be used to solve this problem. In the course of intermittent transportation, if shutdown time is too long and crude oil temperature of pipeline decreases to a certain value, pipeline restart confronts tremendous difficulties, and further probably results in the accidents of pipeline condensation. According to of heating and water power character of pipelines from Tieling to Dalian, based on intermittent transportation, the mathematical models of temperature drop, restart temperature rising and restart pressure were established. By adopting finite difference method, partial differential equation of heat conduction is transferred to linear equations system and comes into solution by iterative method. Taking two sections of pipelines covering Anshan to Da Shiqiao and Da Shiqiao to Xiongyue as examples, simulation calculations of shut-down and restart were conducted. The result shows that pipeline may work safely during winters by this way that pipelines restart and continue work for two days after 8 days shut-down when the oil flow is 23 300 t/d and outgoing temperature is 45 ℃. The method is successfully applied for Tieling-Dalian pipeline.

Key words: Buried pipeline, Intermittent transmission, Numerical simulation, Temperature field

摘要： 原油管道低输量情况普遍存在。当管道输量低于允许最低输量时，如能采用间歇输送工艺则可以有效解决这一难题。在间歇输送过程中如果停输时间过长，管道内原油温度降低到一定值后，就会给管道的再启动带来极大的困难，甚至造成凝管事故。根据铁岭-大连管道的热力及水力特征建立了埋地管道间歇输送温降数学模型、再启动温升数学模型和再启动压力数学模型。采用有限差分方法，把热传导偏微分方程转化为线性方程组后，用迭代法求解。以鞍山到大石桥、大石桥到熊岳两段管道为例进行停输和再启动过程模拟计算。结果表明，当俄油输量为23 300 t/d，出站温度为45 ℃时，该管道在冬季的间歇输送方案是停输8天后再启动输油2天，可保证管道安全过冬。该方案成功地在铁岭-大连管道得到应用。

关键词: 埋地管道, 间歇输送, 数值模拟, 温度场