管输过程中天然气水合物沉降规律计算研究

天然气水合物具有气含率高、污染低、储量大等优点,具有良好的发展前景,因此对天然气水合物进行研究很有必要。以海底输送管道为研究背景,在多相流模型的基础上,建立了基于有限体积法的天然气水合物气-固两相流问题的数学模型,并进行了数值计算与分析,得出了直径差(管径与通流直径之差)与距管道入口距离之间的关系。设定管道入口流速和管径规格为定值,通过直径差分析了管道中水合物的堆积位置。计算结果表明,在其他条件不变的情况下,随着距管道入口距离的增加,直径差的变化规律符合Gauss曲线函数,并对此进行了拟合,得到了Gauss函数方程,利用此方程在给定管道位置的情况下能计算直径差。最后,通过改变管径大小进行了模拟和分析,得知Gauss函数方程也适用于不同管径的管道,可为预测水合物在管道中的堆积位置以及提高天然气水合物输送效率提供理论依据。

Study on the Law of Natural Gas Hydrate Sedimentation in the Process of Pipeline Transportation

Natural gas hydrate was becoming more and more important in Chinese energy structure, which had the advantages of high gas content, low pollution and large reserves. Therefore, it was necessary to study natural gas hydrate. Aiming at the common blockage problem in transmission pipeline for natural gas hydrate, on the background of subsea level pipelines and based on the multiphase flow model, the calculating and analyzing natural gas hydrate mathematical model was established in gas solid two phase flow based on finite volume method. And the relationship was obtained between the difference of the diameter (the diameter of the pipe and the through-flow diameter) and the distance from inlet. When the inlet flow velocity and the diameter of the pipe were fixed, the stack position of the gas hydrate in the pipeline was analyzed with the difference of the diameter. Calculation results showed that with the other conditions remaining unchanged, as the increase of the distance from the pipe inlet, the change rule of the difference of the diameter was in accord with Gauss curve. Then the change rule was fitted and Gauss function equation was obtained, which could calculate the difference of diameter under a given position of pipe. Finally, through changing the diameter size of pipeline, the simulation and analysis were carried out, whose results showed that Gauss function equation also applied in pipelines with different diameters. A theoretical basis for predicting the stack position was provided in the pipeline and improving the transport efficiency of natural gas hydrate.