超音速分离器中天然气凝结特性研究

发布时间：2018-03-21 15:32

本文选题：超音速分离　切入点：凝结成核　出处：《西南石油大学》2015年硕士论文　论文类型：学位论文

【摘要】：天然气中通常含有饱和水和重烃组分,在集输过程中容易凝结为液体,造成设备管线、阀门的堵塞,特别是在有酸性气体存在时还会发生腐蚀,因此脱除天然气中的水和重烃是集输过程中一个必要环节。常规天然气脱水脱烃方法普遍存在设备庞大、投资和操作费用高、再生能耗高、造成环境污染等缺点,同时在沙漠、海洋平台等边远分散地方难以应用,超音速旋流分离技术因具有结构紧凑、无人值守、节约成本和环境友好等优势而具有广阔的应用前景。本论文根据某原料气气质条件,在实验室前期研究的基础上,采用较先进的超音速分离器结构,建立了超音速旋流分离器三维物理模型。通过引入自发凝结模型和湍流模型,在考虑气液相耦合的情况下建立了多组分混合物的凝结过程数值模型,在此基础上进行合理的网格划分和求解算法选择,采用CFD数值模拟技术研究了超音速喷管内流场分布和凝结参数(如过冷度、成核率、过饱和度等)的变化情况,结果表明凝结过程有利于流场的稳定,气体分子在过冷度和过饱和度达到最大时开始聚集并发生凝结；同时对超音速喷管中的温度压力特性进行了分析,获得了在入口温度和压力变化时相关凝结参数的变化规律,分析表明可通过适当降低入口压力和提高入口温度来促进非平衡凝结过程。根据超音速喷管内的凝结规律,在超音速分离器连续相流场的基础上,利用离散相模型模拟得到了液滴在分离器内的三种运动轨迹及离散相参数的分布,表明大多数液滴能被分离出去。同时分析了不同液滴参数、导流叶片数量对分离效率的影响,结果表明液滴直径和叶片数对分离效率影响显著,随着液滴直径和叶片数的增加,液滴所受离心力增加,分离效率也相应增加。对离开超音速分离器的干气露点分析表明所给的超音速分离器结构脱水性能良好,能够满足国内大多数气田开发的需要。
[Abstract]:Natural gas usually contains saturated water and heavy hydrocarbon components, which are easily condensed into liquids during gathering and transportation, resulting in blockage of equipment, pipelines and valves, especially when acidic gases are present. Therefore, removing water and heavy hydrocarbon from natural gas is a necessary link in the process of gathering and transportation. Conventional natural gas dehydration and dehydrocarbon-removal methods generally have many disadvantages, such as huge equipment, high investment and operation cost, high energy consumption for regeneration, environmental pollution, and so on. At the same time, in the desert, Offshore platforms and other remote dispersed areas are difficult to apply. Supersonic swirl separation technology has a broad application prospect because of its advantages of compact structure, unattended, cost saving and environmental friendliness. In this paper, according to the condition of the gas quality of a certain raw gas, on the basis of the previous research in the laboratory, a three dimensional physical model of the supersonic swirl separator is established by adopting the advanced supersonic separator structure. The spontaneous condensation model and the turbulence model are introduced. A numerical model for the condensation process of multicomponent mixtures is established considering the gas-liquid phase coupling. On the basis of this, reasonable mesh generation and algorithm selection are carried out. The variation of flow field distribution and condensation parameters (such as undercooling, nucleation rate, supersaturation, etc.) in supersonic nozzle is studied by using CFD numerical simulation technique. The results show that the condensation process is beneficial to the stability of the flow field. At the same time, the temperature and pressure characteristics of the supersonic nozzle are analyzed, and the change rules of the condensation parameters are obtained when the inlet temperature and pressure change. The analysis shows that the non-equilibrium condensation process can be promoted by lowering the inlet pressure and increasing the inlet temperature. According to the condensation law in supersonic nozzle, on the basis of continuous phase flow field of supersonic separator, the discrete phase model is used to simulate three kinds of droplet motion trajectories and the distribution of discrete phase parameters in the separator. The results show that most of the droplets can be separated, and the influence of the parameters of the droplets and the number of the flow guide blades on the separation efficiency is analyzed. The results show that the diameter of the droplets and the number of the blades have a significant effect on the separation efficiency, and with the increase of the droplet diameter and the number of the blades, The analysis of the dry gas dew point from the supersonic separator shows that the structure of the supersonic separator has good dehydration performance and can meet the needs of most gas fields in China.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE642

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