低持液率湿天然气集输管道的水力计算模型

Hydraulic calculation model of low holdup wet natural gas transmission pipeline

与常规的油-气-水三相流动相比,低持液率三相流动混合物由于液体含量极少,因而具有独特的流动特性,使得对其持液率和管输压降的预测更加困难。针对低含液湿天然气的集输特点,根据流体力学的基本原理,建立了用于预测管道内油-气-水三相混合物的持液率和管输压降模型,简化了关于湿壁分数、液-壁摩擦因子、界面摩擦因子、油水混合粘度的经验闭合关系式,提出了液滴夹带的气体流速判断条件,并考虑气液界面之间的非水平特点,给出了曲面气液界面的处理方法。模型的计算结果与室内实验结果吻合较好,能够较准确地预测管道内油-气-水三相混合物的持液率和管输压降等流动参数,对于低持液率湿天然气管道的设计和运营管理等具有很好的指导作用。

Compared with the common oil-gas-water three-phase flow,low holdup three-phase flow has its special flow characteristic due to lowest liquid content which brings more difficulties for predicting the holdup and pressure drop.Aiming at the transmission characteristic of low holdup wet natural gas and based on the basic principle of hydromechanics,the model to predict the holdup and pressure drop for oil-gas-water three-phase flow of pipeline is established.The model simplifies the empirical relations about the wet-wall fraction,liquid-wall friction factor,interfacial friction factor and oil-gas mix viscosity.The model presents the speed judging condition of the gas taken by the liquid based on the low holdup liquid flow characteristic.The model considers the non-horizontal gas-liquid interface and presents the curved surface processing method.The calculation result agrees well with that of in laboratory,which shows that the model is appropriate for predicting the holdup and pressure drop of pipeline and can provide an effective instruction in design and operation of low holdup wet gas pipeline.