原油长输管道启动压力研究

降低热输管道的输油温度或实现常温输送，是原油管道节能降耗的有效途径，但在低温下能否顺利启动则是关键。通过对流体管避运过程、非牛顿体触变性及两者关系的研究，导出了牛顿体和非牛顿液体管道中动压力的计算方法，及启动压力与启动流量的相关规律。同时指出，启动压力由三部分组成；液体由静止加速到启支速度的惯性力；液体与管壁间的摩擦力，破坏非牛顿体结构的触变性附加力。计算实例表明，利用屈服值预测屈服假塑性原油管道

A Study on the Restart Pressure of Long-Distance Trunkline

Reducing transfer temperature and/or operation without successive heating in a certain pipeline can substantially reduce the energy consumption. However, the low transfer temperature will probably cause the restart problem,and the restartability will be the focus at the low temperature. By investigating the restart process of liquid pipeline and the thixotropy of non-Newtonian fluid as well as the relationship between them,this paper puts forward an approach to calculating the restart pressure of both Newtonian and non-Newtonian fluid pipeline,and reveals the relationship between restart pressure and flow rate. The paper also points out that the restart pressure consists of three kinds of forces: the inertia force to accelerate fluid to a certain velocity;the friction force between the pipe wall and fluid transported;and the extra stress to break down the structure of thixotropical fluid. The computation results demonstrate that the conventional method,in which yield stress serves as the decisive parameter to calculate the restart pressure of the pipeline with pseudoplastic fluid transported, is too conservative to obtain reasonable restart pressure. By employing the new approach recommended in this paper,the much more accurate restart pressure have been obtained,moreover,the longer the pipeline is,the more the accurate results are.