水合物浆体螺旋管多相流动及分离研究

发布时间：2018-07-27 13:21

【摘要】：海洋天然气水合物资源巨大。周守为院士提出了 "海底浅表层非成岩天然气水合物藏固态流化开采技术"新思路,其中必须解决破碎后的"海底水合物混合浆体中泥砂分离问题"。这种混合浆体通常是由矿物质(主要为泥沙)、天然气水合物和海水等三种物质所组成,属于液-固-固多相流分离问题。为了减少水合物混合浆体在输送过程中的能量消耗,必须在海底进行水合物浆体中的泥砂预分离。同时还可以避免出现泥砂沉积而发生管道堵塞的风险。其中螺旋分支管是一种适合于海底多相流分离的结构。本文从多相流体动力学与离散元素法等基础理论出发,采用CFD-DEM耦合仿真研究的方法,针对本文所提出的简化后的带捕砂槽的弧形分支管分离结构开展了以下研究工作:(1)通过查阅国内外文献报告,了解了海底多相流分离研究现状和进展。(2)ECFD-DEM耦合接口程序开发与验证。根据多相流体动力学和离散元素法的基础理论,研究固体颗粒在流体中的力学行为,考虑流体对颗粒旋转力矩的作用,开发FLUENT-EDEM耦合仿真接口程序,并进行实验验证。(3)螺旋管流动特性的数值仿真研究。利用验证后的接口程序,仿真模拟研究水合物或泥砂单颗粒在螺旋管中的运动规律,建立单颗粒在螺旋管截面上运动的轨迹方程;进一步仿真模拟研究水合物浆体在螺旋管中的运动规律。(4)带捕沙槽弧形分支管分离效率研究。根据水合物浆体在螺旋管中流场分布规律,提出螺旋分支管分离结构及其分离效率的计算方法,并将其简化为弧形分支管结构。利用耦合仿真程序,对比研究弧形分支管与带捕沙槽的弧形分支管两种结构的分离效率。(5)带捕沙槽弧形分支管分离参数优化。合理选取关键结构参数及运行参数,确定影响带捕砂槽弧形分支管分离效率的6因素5水平的正交试验方案,通过正交试验优化,得到最佳的结构参数与运行参数的组合,使其具有较高的分离效率。通过上述研究,掌握了水合物浆体在螺旋管中流动时固体颗粒的分布规律,提出了一种带捕砂槽的弧形分支管来分离水合物浆体;通过正交试验优化,得到最佳的结构参数和运行参数匹配,使得带捕砂槽弧形分支管的综合分离效率达到了91.5%,并且其出口 2的水合物颗粒含量高达99.25%。本文的研究为海底天然气水合物浆体的泥砂分离提供了有价值的参考。
[Abstract]:The marine natural gas hydrate resources are huge. Academician Zhou Shouwei put forward a new idea of "solid-state fluidized exploitation technology for gas hydrate reservoir in shallow undersea layer", in which the problem of "separation of mud and sand in mixed slurry of undersea hydrate" must be solved. The mixture is usually composed of minerals (mainly sediment), natural gas hydrate and sea water, which is a liquid-solid multiphase flow separation problem. In order to reduce the energy consumption of hydrate mixture during the transportation process, it is necessary to carry out pre-separation of mud sand in hydrate slurry at the bottom of the sea. At the same time, it can avoid the risk of pipeline blockage caused by mud sand deposition. The helical branch tube is a kind of structure suitable for multi-phase flow separation. Based on the basic theories of multiphase hydrodynamics and discrete element method, the method of CFD-DEM coupling simulation is used in this paper. The following research work has been carried out on the simplified arc branch tube separation structure with sand capture trough proposed in this paper: (1) by consulting the domestic and foreign literature reports, The research status and progress of submarine multiphase flow separation are studied. (2) ECFD-DEM coupling interface program is developed and validated. According to the basic theory of multiphase hydrodynamics and discrete element method, the mechanical behavior of solid particles in fluid is studied, and the FLUENT-EDEM coupling simulation interface program is developed considering the effect of fluid on particle rotation moment. The experimental results are verified. (3) numerical simulation of the flow characteristics of helical tubes. Using the verified interface program, the movement law of hydrate or mud sand single particle in the spiral tube is simulated and studied, and the trajectory equation of the single particle moving on the section of the spiral tube is established. The movement of hydrate slurry in spiral tube was studied by simulation. (4) the separation efficiency of arc branch tube with sand trap was studied. According to the distribution of gas hydrate slurry in helical tube, a method for calculating the separation structure and separation efficiency of helical branched tube is presented, which is simplified as an arc branch tube structure. By using the coupled simulation program, the separation efficiency of arc branch tube and arc branch tube with sediment capture channel is compared and studied. (5) the separation parameters of arc branch tube with sediment capture channel are optimized. The key structural parameters and operation parameters are reasonably selected, and the orthogonal test scheme with 6 factors and 5 levels that affect the separation efficiency of arc branch pipes with sand capture trough is determined. The optimum combination of structural parameters and operation parameters is obtained through orthogonal test optimization. It has higher separation efficiency. Through the above research, the distribution law of solid particles in the flow of hydrate slurry in helical tube is grasped, and a kind of arc branch tube with sand capture trough is proposed to separate hydrate slurry, which is optimized by orthogonal test. The optimum structural parameters and operation parameters are obtained, which makes the comprehensive separation efficiency of the arc branch tube with sand trap reach 91.5, and the hydrate particle content of the outlet 2 is 99.25%. The research in this paper provides a valuable reference for the mud sand separation of gas hydrate slurry.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O359

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