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埋地含蜡原油管道运行及停输再启动过程研究

The Research on Operationg and Shutdown and Restart-up of Buried Waxy Crude Oil Pipeline

【作者】 贾永英;

【导师】 刘扬;

【作者基本信息】 大庆石油学院 , 油气储运工程, 2009, 博士

【摘要】 为了实现埋地含蜡原油管道安全运行,本文研究了埋地含蜡原油管道运行及停输再启动过程。在研究过程中,针对含蜡原油特点,建立了含蜡原油正常运行数学模型,建立数学模型时考虑了含蜡原油在输送过程中,会形成蜡沉积,导致管径变小,摩阻增加。根据含蜡原油蜡沉积原理,考虑了结蜡层影响,求解了热边界层及管内原油温度,并给出水力计算公式;在停输过程研究中,建立了埋地含蜡原油管道停输径向及轴向温降数学模型,并给出了模型的求解方法;建立含蜡原油再启动模型时,通过连续性方程、运动方程以及流变性方程建立了压力、流量及剪切力三者相互耦合的再启动数学模型。模型考虑了流体的压缩性、沿管道位置和时间变化的流变性影响,凝油的流变性方程采用宾汉模型,并考虑了屈服应力的逐时变化。通过数值模拟,给出埋地含蜡原油管道运行及停输再启动计算结果,并进行影响因素分析。在管道正常运行工况时,给出质量流量、管道尺寸、管道长度、埋地深度、保温层厚度、再启动日期、入口温度、预热时间、地面传热系数等对原油温度和压降的影响;分析在停输过程中,停输日期、停输时间长短对停输过程的影响;在再启动过程中,给出了再启动压力、压缩影响、流体填充度、初始压缩时间对质量流量、管线压力分布、再启动清除时间的影响。

【Abstract】 For safety of oil pipeline, The work focuses on Operationg and Shutdown and Restart-up of Buried Waxy Crude Oil Pipeline. The Operating math model is built according waxy crude oil characteristic,solidification will preferentially occur on the wall,leading to deposition.This causes undesirable effects,such as an decrease in pipe diameter and an increase in pressure losses. According to deposition mechanisms, This work take into account deposit thickness ,The temperature of thin boundary layer near the wall and the bulk is given; The control equation of crude oil in the Buried Waxy Crude Oil Pipeline during the process of shutdown was established And the approach to calculate the equation by finite element method was given and the max safe shutdown time was calculated;The coupled model of restart-up of waxy crude oil pipeline is studied about continuity equation、motion equation and theology equation. The restart model takes into account the compressibility and longitudinal variations. The theology of the gelled oil is modeled based on Bingham model, yield stress varies with time. Both laminar and turbulent flows are considered in the model According to the result of numerical simulation,analysed the effects of flow rate、pipe size、pipeline length、burial depth、insulation thickness、start date、inlet temperature、preheat time、ground conductivity on operating process; analysed the effects of shutdown date、shutdown length on shutdown process; analysed the effects of start-up pressure,initial compression time、liquid hold-up、compressibity、initial compression time on mass flow rate、pressure、time to clear the gelled oil.

【关键词】 含蜡原油; 正常运行; 停输; 再启动; 流变性; 压缩;
【Key words】 waxy crude oil; operating; shutdown; restart-up; rheological; compressibility;
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