机动管线充气排液过程中油-气体两相流阻力特性

机动管线是油料保障的骨干装备,充气排液是管线使用的一项常规作业,随着液体被排出管线,管内液体处于变加速直线运动状态,整个管路的阻力表现出非线性特征,与单相管流有很大区别.掌握管线充气排液过程的阻力特性,可以为管线排空工艺设计提供理论依据,为此提出一种适用于该过程阻力计算的简化模型.该管路分为3段,即单相气体段、单相液体...

Resistance Characteristics of Oil-gas Two-phase Flow for Mobile Pipeline Evacuation Operation

Mobile pipeline plays a great role in the oil supply，and the the pipe evacuation is a regular working. The length of the sections varies with the liquid expelled from the pipeline, and the liquid acceleration is variable, so the resistance of the pipiline system exhibits nonlinear characteristics, which shows more difference against the single phase flow. In order to provide the theoretical basis for the evacuation design, the resistance of pipeline must be accurately predicted. A calculation model is presented for the resistance characteristics in the process of pipeline evacuation. In the proposed model, a pipeline is divided into three sections, including a single-phase gas section, a single-phase liquid section, and a two-phase flow section. The resistance characteristics of the whole pipeline are obtained by calculating the friction resistance of each section. By comparing with the experimental data of various working conditions of mobile pipeline evacuation operation, the calculated result of the proposed model has a good agreement with the experimental data in the first 2/3 time period of evacuation process. In the later 1/3 time period, the resistance of pipeline is mainly caused by gas-liquid two-phase flow, so there are some errors among the calculated values and the experimental values, which may be caused by the estimation of slug frequency and the accelerated pressure drop. The calculation accuracy of the proposed model is analyzed by using the absolute mean value of error. The obvious influential factor is the physical properties of oil products, such as viscosity, density, surface tension, etc., while the influences of pipe diameter, pipe length and gas flow rate are small. The calculated results of the proposed model have a good agreement with the experimental results. The proposed model can be used for the analysis and prediction of the resistance characteristics during the mobile pipeline evacuation operation.