【作者】 罗小明；

【导师】 何利民；

【作者基本信息】 中国石油大学 ， 油气储运工程， 2007， 博士

【摘要】 气液两相和多相段塞流广泛存在于石油、化工工业中,由于其流动的间歇性和相分布的复杂性,目前对其研究仍处于探索阶段。本文在内径50mm,长为40m的水平管和微倾斜管中对气液两相和油气水三相段塞流进行了深入系统的研究,对完善多相流理论及实际应用具有十分重要的意义。主要研究内容和结论如下:对段塞流持液率、压力和压差的波动特性进行了深入研究,分析得到段塞单元平均持液率、液塞持液率、液膜持液率、压力及压差的变化规律。通过统计和非线性分析发现:段塞流持液率的概率密度分布为双峰分布,高持液率峰对应于液塞区,低持液率峰对应于液膜区;在压力的概率密度分布中,当压力测试点到管道出口之间的段塞单元数目少时,压力分布出现双峰分布;当压力测试点到管道出口之间的段塞单元数目多时,压力分布出现单峰分布;压差信号分布呈单峰分布。这些特征为流型识别提供了可靠的段塞流标识。通过实验对Kelvin-Helmholtz模型、粘性长波长模型和液塞稳定模型进行了对比分析。采用Kelvin-Helmholtz模型研究油气水三相段塞流的转变边界,发现液相含水率的增加将导致临界液速和临界液位的增加。油气水三相段塞流与环状流转变中发现特殊的滚动波流型,段塞流型为W/O或O/W段塞流型,滚动波流型为相界面没有混合的三层流型,油气水三相段塞流与滚动波流型的转变仅发生在液相含水率为30%~70%的工况下。当液相含水率≤20%或≥80%时,随着气相速度的增加,段塞流直接转变为环状流。在同一折算液速下,随着液相含水率的增加,流型转变对应的折算气速先降低然后再升高,当液相含水率为40%~50%时,流型转变对应的折算气速出现最小值。研究采集信号的特征发现油水两相流的流型分为六种,分层流、混合界面分层流、O/W&W分散流、O/W分散流、W/O&O/W混合流和W/O分散流。并采用无因次量关联的方法,得出了各流型转变边界关联式,与实验数据吻合良好。油气水三相段塞流分为八种子流型:分层段塞流、混合界面分层段塞流、W/O&O/W段塞流、O/W&W段塞流、塞O/W膜O/W&W段塞流、O/W段塞流、W/O&O段塞流和W/O段塞流,并对流型转变进行了深入研究。在油气水三相段塞流型中存在反相现象,反相点的液相含水率在30~40%之间。对水平管和微倾斜管中气液两相和油气水三相段塞流特征参数(液塞速度、液塞长度、液塞频率、长气泡长度和段塞单元长度)进行了系统的研究。液塞速度分布符合高斯分布,分析得到了液塞速度关系式及油水相分布对液塞速度的影响规律。液塞长度符合对数正态分布,随着Frm的增大先减小后增大,在Frm=3.5时出现最小值。液塞长度由气液相折算速度决定,油水相分布对其基本没有影响。液塞频率随着折算气速的增加,液塞频率先减小再增大,存在极小值,并得到液塞频率关系式。长气泡长度和段塞单元长度主要由气液相折算速度决定,倾角和油水相分布对其基本没有影响。更多还原

【Abstract】 Gas-liquid two-phase and multiphase slug flow is commonly encountered in the petroleum and chemical industries. Owing to the intermittence of flow rate and the complexity of phase distribution,the research of slug flow is still in the primary state. This paper studies the gas-liquid two-phase and oil-gas-water three-phase slug flow in the horizontal and slightly inclined pipes, with a diameter of 50mm and a length of 40m. It is very significant to improve the theory of multiphase flow and practical application. The main contents and conclusions of research are following.Going deep into the fluctuation characteristics of liquid holdup, pressure and differential pressure, and the mean liquid holdup within slug unit, the liquid holdup within slug and the liquid holdup within film are analyzed, and the regularity is obtained. By statistical and nonlinear analysis, it can be found that the probability density distribution of the liquid holdup is bimodal distribution. The high liquid holdup peak is in correspondence with liquid holdup within the slug and the low liquid holdup peak is in correspondence with liquid holdup within the film. Moreover, the distribution of pressure is unimodal distribution or bimodal distribution, and the differential pressure distribution is unimodal distribution. These characteristics provide dependable slug identities for flow pattern identification.The theoretical models of Kelvin-Helmholtz, the viscous long wavelength and slug stability are analyzed and compared through experiments. Kelvin-Helmholtz model is adopted to study the transform boundary of oil-gas-water three-phase slug flow, and it can be found that the critical liquid velocity and the critical liquid level will increase with the increasing of the water cut. The roll wave flow pattern is found in the process of transforming from oil-gas-water three-phase slug flow to annular flow. In this case, the liquid distribution of slug flow is W/O or O/W, the roll wave flow is three-layer flow without commixture in interfaces. The region of roll wave and its regularity are studied in depth.By studying the characteristics of the acquired signal, it is found that oil-water two-phase flow can be classified into six flow patterns: stratified flow, mixed interface stratified flow, O/W&W dispersed flow, O/W dispersed flow, W/O&O/W mixed flow, and W/O dispersed flow. Transform boundary correlations of different flow patterns are obtained through dimensionless variable analysis, and they coincided well with experimental data. The oil-gas-water three-phase slug flow is classified into eight flow patterns: stratifying-slug flow, mixed interface stratifying-slug flow, W/O&O/W slug flow, O/W&W slug flow, (slug)O/W-(film)O/W&W slug flow, O/W slug flow, W/O&O slug flow and W/O slug flow. The regularity of phase inversion and flow pattern transform is also studied.The characteristic parameters of gas-water two-phase and oil-gas-water three-phase slug flow in horizontal and slightly inclined pipes such as slug velocity, slug length, slug frequency, length of long bubble and slug unit length are studied systematically. The distribution of slug velocity accords with Gaussian distribution. The relational equation of slug velocity and the influence of oil-water phase distribution to slug velocity are obtained. The distribution of slug length accords with lognormal distribution and it increases at first and then decreases with the increasing of Frm. When Frm=3.5, the minimum slug length appears. The slug length is determined by gas and liquid superficial velocities, and oil-water distribution nearly has no effect on it. With the increasing of superficial gas velocity, the slug frequency decreases firstly and then increases, and there is a minimal value. The relational equation of slug frequency is also obtained. The length of long bubble and the length of slug unit are mainly determined by gas and liquid superficial velocity. Inclination angle and oil-water distribution nearly have no effect on them.更多还原