【作者】 吴东月；

【导师】 王超；

【作者基本信息】 天津大学 ， 检测技术与自动化装置， 2012， 博士

【摘要】 油、水两相流广泛存在于原油的开采及输送过程中。含油率是油、水两相流动过程中一个非常重要的参数。本文对利用双U型Coriolis质量流量计和同轴电导传感器测量油、水两相流的持油率以及测量持油率与实际含油率之间关系进行了研究,本文主要完成工作有:1.利用Coriolis质量流量计测量油、水两相流持油率的实验发现:装置参考含油率与测量持油率的比值Y随着含油率的增加,呈现一种先变大后变小的规律。由于U型管的结构复杂,不能从理论上直接分析倒U型规律是否为U型管Coriolis质量流量计测量油、水两相流的固有规律。接下来,本文从油、水两相流的流动机理及质量流量计测量原理出发,对U型管Coriolis质量流量计测量油、水两相流持油率进行了三维计算流体力学(Computational Fluid Dynamics, CFD)仿真研究。仿真得到的持油率与含油率之间的关系也存在与实验测量结果相似的变化规律,表明了利用U型管Coriolis质量流量计测量油、水两相流的持油率与实际含油率间确实存在这种先增大后减小的规律。2.在考察现有电导传感器结构基础上,设计了带有保护电极的同轴电导传感器及测量系统,并对同轴电导传感器的结构尺寸进行了优化设计。之后利用按照优化的结构、尺寸加工的同轴电导传感器对油、水两相流进行了实验研究。将同轴电导传感器测量结果代入不同的模型计算持油率,发现在含油率低于50%时,使用Maxwell模型测量持油率与参考含油率之间的偏差最小,均在2%以内;含油率在50%~70%之间,使用Maxwell模型与Brrugenman模型的均值作为测量值效果较好,测量持油率与含油率的偏差在6%以内。3.对垂直安装的同轴电导传感器测量油、水两相流的持油率与含油率之间的关系进行了研究。实验发现垂直上升管与垂直下降管中,都存在含油率与持油率的比值Y随着含油率的增加由大于1变为小于1的变化规律。进一步分析表明该规律是由垂直管道中油、水两相流的分布引起的,是垂直管中测量持油率与含油率关系的固有规律。更多还原

【Abstract】 Oil-water two-phase flow is widely present in the exploitation and transport of crude oil. Oil volume fraction is a significant parameter in the oil-water two-phase flow measurement. The oil holdup was measured by the Coriolis mass flowmeter and the coaxial conductivity sensor in this paper. Besides, the relationship between the real oil volume fraction and the oil holdup measured was investigated. The main contributions of this paper are shown as followed:1. The oil holdup of the oil-water two-phase flow was experimentally measured using Coriolis mass flowmeter. The ratio between the real oil volume fraction and the oil holdup measured exhibited a reverse U-shape characteristic with the increase of oil volume fraction, which increases at first and then decreases. Due to the complex geometry of the U tube, it was impossible to theoretically analyze this phenomenon in the Coriolis mass flowmeter. However, based on the flow dynamic of the oil-water two-phase flow and the principle of Coriolis mass flowmeter, 3D Computational Fluid Dynamics (CFD) of the U-shaped Coriolis mass flowmeter was carried out. The results from 3D CFD showed similar trend with the experimental results, which proves that the reverse U-shape between the oil volume fraction and the oil holdup is the intrinsic characteristic of the U tube Coriolis mass flowmeter.2. Based on the investigation on the geometry of the conductivity sensor used now, a coaxial conductivity sensor with guard electrodes and the corresponding measurement system were designed. Besides, the geometry of the conductivity sensor was optimized. The coaxial conductivity sensor was manufactured as optimized. In order to verify the applicability of the coaxial sensor, a series of oil-water two-phase flow tests was conducted in vertical upward and downward pipes on the multiphase flow test rig at Tianjin University. The measurement results of the coaxial conductivity sensor were used to calculate the oil volume fraction using different models. When the oil volume fraction was lower than 50%, the minimum error between the oil holdup measured and the real oil volume fraction could be obtained by the Maxwell model, which is within 2%. When the oil volume fraction was between 50% and 70%, best performance can be gotten using the mean value between the Maxwell model and Brrugenman model, the error of which is within 6%. The relationship between the oil holdup and the oil volume fraction of the oil-water two-phase flow was investigated using the vertical installed coaxial conductivity sensor. A trend happened both in the vertical upward and downward flow: with the increase of the oil volume fraction, the ratio between the real oil volume fraction and the oil holdup measured changed from larger than 1 to smaller than 1. This rule is caused by the oil-water distribution in the vertical pipe. It is an inherent phenomenon when measuring the oil volume fraction and the oil holdup in the vertical pipe.更多还原