含蜡原油热输管道管壁结蜡厚度的计算

根据石蜡沉积机理,考虑到在含蜡原油热输管道的实际运行中油温高、热流强度大、油流粘度比较小、剪切弥散的作用非常小,因此石蜡在管壁处的沉积主要是由于分子扩散形成的。应用Fick扩散方程来计算石蜡沉积扩散速率,并根据含蜡原油比热容随温度变化的一般规律,采用热力学与动力学相结合的方法推导出了计算含蜡原油热输管道管壁结蜡厚度的计算公式,并用对分法对公式进行求解,得到了管壁结蜡厚度与运行时间以及输送距离之间的关系,并画出了其关系曲线。采用该计算方法能够计算出任意时刻管道沿线任一点处的管壁结蜡厚度,模拟了沿管线长度管壁结蜡厚度的分布规律。此方法为确定管道的经济清蜡方案及保证管道安全运行提供了一定的理论依据。

Calculation of the Paraffin Deposit Thickness on the Wall in Hot Wax Bearing Crude Pipeline

According to the paraffin deposit mechanism, with consideration of the high temperature, strong heat fluid, and low viscosity when crude oil is flowing in practical heat pipeline, the cause of paraffin deposit on pipe wall is formed mainly by molecular diffusion.Fick diffusion equation was used to calculate the speed of paraffin diffusion. According to the general law of specific ,- heat capacity varying with temperature, computing formula of calculating paraffin deposit thickness was derived from combining the thermodynamics and dynamics. Bisection method was used to solve the formula and the relation could be obtained among deposit thickness, running time and transporting distance as well as the relation plot. It is concluded that the method can be used to calculate the thickness of paraffin deposit in anyplace at anytime and imitate the distribution law along the long pipeline. Meanwhile, it serves as a theoretical basis of planning an economic project in cleaning paraffin and ensures the pipeline running safely.