含气条件对井下油水分离旋流器性能影响的数值模拟

为探究气体对井下油水旋流器性能的影响规律,针对新型螺旋流道倒锥式旋流器,采用Fluent软件对气液比分别为0.01、0.03、0.05、0.08、0.10时旋流器的油相分布进行模拟分析。通过对比分析发现:不含气时旋流器的分离效率为89.31%;在结构参数和分流比不变的条件下,旋流器分离效率随气液比的增加呈降低趋势,气液比为0.10时,分离效率为36.90%;气液比越大,溢流口的油相体积分数越小,底流口的油相体积分数越大;溢流口和底流口的压力损失随气液比的增大而递减。     

液-液旋流分离器内流场的数值模拟研究

用计算流体动力学(CFD)的数值方法,采用RSM模型对油水分离用液一液水力旋流器的流场进行了数值模拟。单相流场的模拟结果表明,旋流器内的流场结构是强旋转和非对称的三维结构,因而对旋流器的研究(无论是数值模拟还是实验测量)必须是基于三维的;旋流器上游区内流体紊流现象严重,两侧有循环流存在,这都对两相分离不利,应改进结构以改变这种流动形式;其模拟结果与他人实验结果吻合较好,说明该湍流模型和算法是可靠的。另外还对油一水两相流场进行了研究,初步揭示了液一液两相分离的现象,这都为进一步研究旋流器特性参数对分离效率的影响和旋流器的结构优化提供了参考。     

氨油分离器内高效气液分离元件分离性能的数值研究

采用FLUENT软件对氨油分离器中波纹板除雾器和丝网除雾器内的气液两相流场进行数值模拟计算,考察除雾器的结构参数与操作参数对进出口压降和分离效率的影响规律。结果表明:波纹板除雾器的压降随入口气速的增大而增大,随叶片转折角度的增大而减小,分离效率随液滴直径的增大而增大,随入口气速的增大而增大,随叶片转折角度的增大而减小;丝网除雾器的进出口压降随入口气速的增大而增大,分离效率随入口气速的增大而增加,随入口液滴直径的增大而增加;波纹板和丝网组合在一起的整体分离效率提高,且随着液滴直径的增大,整体分离效率上升很快。     

油水旋流分离器内部流场的CFD模拟

采用计算流体力学数值模拟方法研究油水旋流分离器的内部流场,模拟出分离器内轴向速度变化规律,得到钻井液气液旋流器内部流场的特征。分析油水旋流分离器内部油相体积浓度分布,得到了油水旋流分离器内部流场的分布规律和油水两相流的分离特性,为油水旋流分离器的工艺设计提供了参考依据。     

不同操作参数下动态水力旋流器内部油水两相流动的数值模拟

根据计算流体动力学(CFD)的方法,应用Fluent软件对动态水力旋流器内部油水两相流场进行数值模拟,考察了不同入口流量及转筒转速下旋流器内速度场与油水两相的分布情况。结果表明:动态水力旋流器内切向速度呈双涡结构(准自由涡与准强制涡);轴向速度明显小于切向速度且不存在零速度包络面,油相集中于旋流器轴心形成油核,随着流量及转速的增加,各相速度及中心油核浓度均增加。     

水力旋流器流动特性的数值模拟研究

本文采用双流体模型以及RSM雷诺应力湍流模型,以油水混合液为介质,对水力旋流器的油水分离过程进行模拟。研究结果表明:旋流腔为预分离段,使油水两相粒子达到径向上的规律性分布,起到主要分离作用的是锥段,使油水两相分别从不同的出口排出。通过改变水力旋流器的入口段角度,分析入口角度变化为旋流器分离效率的影响,结果表明:旋流器的入口角度对分离性能的影响不可忽略,当β=0°和β=45°时分离效率较高,当β=60°时分离效率最低。     

T型管内油水分离特性的CFD-PBM数值模拟

目前关于T型管内油水分离特性的数值模拟大多采用Euler-Euler多相流模型,考虑管内油滴粒径分布及其对油水分离特性影响的研究工作尚未见报道。对T型管内的油水两相流动情况和分离特性进行了CFD-PBM数值模拟,并进行了室内实验以验证模拟结果的准确性。结果表明,T型管内油滴粒径随流体流动方向具有逐渐增大的趋势;增大来液中的油滴粒径分布可以有效提高油水分离效率,反之当来液中的油滴粒径较小时,油水两相在T型管内不易分离,相分配比始终与分流比几乎相同;分流比、Reynolds数等操作条件对油水分离效率的影响程度与油滴粒径密切相关,应慎重选取适当的操作条件以保证T型管的油水分离效率。     

T型管内油水分离特性的CFD-PBM数值模拟

目前关于T型管内油水分离特性的数值模拟大多采用Euler-Euler多相流模型,考虑管内油滴粒径分布及其对油水分离特性影响的研究工作尚未见报道。对T型管内的油水两相流动情况和分离特性进行了CFD-PBM数值模拟,并进行了室内实验以验证模拟结果的准确性。结果表明,T型管内油滴粒径随流体流动方向具有逐渐增大的趋势;增大来液中的油滴粒径分布可以有效提高油水分离效率,反之当来液中的油滴粒径较小时,油水两相在T型管内不易分离,相分配比始终与分流比几乎相同;分流比、Reynolds数等操作条件对油水分离效率的影响程度与油滴粒径密切相关,应慎重选取适当的操作条件以保证T型管的油水分离效率。     

矩形螺旋通道气液两相流流动和传热特性数值研究

采用Eulerian模型对矩形截面螺旋通道内气液两相流进行数值模拟,研究了螺旋通道内不同轴向位置气液两相流动的速度分布、相分布和温度分布特性,并分析无量纲螺距对速度分布、温度分布、单位长度压降和换热系数的影响。对水动力模型数值结果与实验结果、传热模型数值结果与实验关联式进行对比,结果表明:在一定范围内,无量纲螺距的增加使得速度场、温度场变化梯度增大,同时壁面换热系数稍有增大;超过无量纲螺距临界值,速度场和温度场的变化梯度随无量纲螺距的增加而减小;随着无量纲螺距的增加,单位长度平均压降稍有增加,并且增加的幅度逐渐减小;无量纲螺距对相分布特性几乎无影响;随着入口截面含气率的增加,单位长度平均压降和换热效果提高。     

不同入口形式的固液分离旋流器壁面磨损研究

基于计算流体力学(CFD)软件Fluent中的颗粒随机轨道模型(DPM),对两种入口形式的固液分离旋流器的壁面磨损进行数值模拟的比较,结果表明:单入口式固液分离旋流器顶板的最大磨损位于方位角140°~210°,环形空间壁面最大磨损位于方位角120°和190°,底流口附近壁面最大磨损在周向方向180°的底流口上方1~2mm位置;双入口式旋流器的壁面磨损呈对称分布,最大磨损在底流口位置,顶板壁面最大磨损在两个入口区域,顶板外层最大磨损位于方位角80°~110°和260°~290°,环形空间壁面最大磨损位于方位角120°和300°;相同条件下,双入口式旋流器顶板和环形空间的壁面磨损小于单入口式旋流器顶板和环形空间的壁面磨损;而对于底流口附近的壁面磨损,双入口式固液分离旋流器底流口附近的壁面磨损略大。     

数值研究液-液水力旋流器内颗粒浓度分布特性

根据计算流体力学(CFD)的原理和方法,应用Fluent软件对液-淡水力旋流器内部颗粒浓度分布进行数值模拟,得到了不同进口流量和不同进料浓度下旋流器内各个截面上浓度分布情况.结果表明:旋流器内各截面上浓度变化曲线呈现抛物线型;进口流量越大,在管壁处浓度值越小,油滴不断向管芯聚集;进料浓度越大,在旋流器的大部分区域中,浓...     

Study of Air‐Liquid Flow Patterns in Hydrocyclone Enhanced by Air Bubbles

In order to improve the oil‐water separation efficiency of a hydrocyclone, a new process utilizing air bubbles has been developed to enhance separation performance. Using the two‐component phase Doppler particle analyzer (PDPA) technique, the velocities of two phases, air and liquid, and air bubble diameter were measured in a hydrocyclone. The air‐liquid mixing pump can produce 15 to 60 μm‐diameter air bubbles in water. There is an optimum air‐liquid ratio for oil‐water separation of a hydrocyclone enhanced by air bubbles. An air core occurs in the hydrocyclone when the air‐liquid ratio is more than 1 %. The velocities of air bubbles have a similar flow pattern to the water phase. The axial and tangential velocity differences of the air bubbles at different air‐liquid ratio are greater near the wall and near the core of the hydrocyclone. The measured results show that the size distribution of the air bubbles produced by the air‐liquid mixing pump is beneficial to the process where air bubbles capture oil droplets in the hydrocyclone. These studies are helpful to understand the separation mechanism of a hydrocyclone enhanced by air bubbles.     

Studies on the performance of a hydrocyclone and modeling for flow characterization in presence and absence of air core

Hydrocyclones are getting more and more interest from various industries. They are widely used to separate particulates from liquid at high throughput because of their advantages like simple structure, low cost, large capacity and small volume, require little way of maintenance and support structure. Modeling of complex and multiphase flow behavior inside the hydrocyclone is done usually with the help of computational fluid dynamic study. Current study involves experimental investigation of separation performance characteristics of the hydrocyclone using new design parameters. For experimental purpose, a new hydrocyclone was designed with insertion of solid rod, at central portion of conical section of hydrocyclone, inside the hydrocyclone . By which air core could be eliminated effectively and hydrocyclone performance is improved. This effect may be observed due to reduction of radial and axial components of velocity and turbulence in the area near the entrance of the vortex finder. Therefore, the flow field characteristics inside the hydrocyclone with no air core become more suitable for separation. Also the effect of flow rate, vortex finder depths, air core and particle interaction were studied experimentally. A new arrangement was suggested to eliminate the air core formed inside the hydrocyclone. In this case, effect of diameter and height of solid rod inserted inside the hydrocyclone with changing total inlet flow rate was studied experimentally. Three-dimensional geometry and meshing of hydrocyclone is created in Gambit, preprocessor of commercial software—Fluent, for hydrodynamic study.     

Performance of a New Geometry of Deoiling Hydrocyclones: Experiments and Numerical Simulations

A new geometry of liquid‐liquid hydrocyclones is proposed seeking to perform the separation of oil emulsified in water. The hydrocyclone performance was investigated by means of a factorial experimental design (2³) leading to a total of ten experiments. The results enabled the determination of empirical mathematical models that describe capacity, total separation efficiency, and flow ratio as a function of oil concentration in the feed inlet, operating pressure drop, and presence or absence of a vortex finder in the geometry. Numerical simulations were also carried out to further understand the flow field characteristics in the studied hydrocyclone.     

多进口旋流器流场特征及分离性能

为了改善单进口旋流器稳定性差、分级效率低等问题,本文提出了多进口旋流器结构。通过数值模拟方法,在恒定入料工况下,对比分析了单、二、三、四进口旋流器的流场特征和分离性能。研究结果表明：增加旋流器进口数量,会对旋流器流场和分离性能产生积极影响,有利于旋流流场径向压力的增大,且进口数量为偶数时,流场径向静压力增强效果更好;旋流器柱段区域流场切向速度增大,有利于强化旋流器分离能力。同时使用Mixture耦合RSM模型预测了离散相CaCO₃颗粒的分离效率,结果表明多进口旋流器可以在低速度入口条件下完成离散相的高精度分离。入料速度为3m/s的工况条件下,多进口旋流器分离50μm、57.5μm颗粒的底流分配率较单进口旋流器分别提升了10.60%、5.59%,对抑制旋流器溢流产品错配率和提高分级精度有积极的影响。因此,增加旋流器进口数量,可以有效提升旋流分级效率和分离精度。     

Numerical Analysis of Drops Coalescence and Breakage Effects on De-Oiling Hydrocyclone Performance

This work investigated the effects of breakage and coalescence on de-oiling hydrocyclone performance utilizing Computational Fluid Dynamics (CFD). It was found that an increase in the entrance flow rate with low entrance oil concentration not only did not increase the separation performance of the hydrocyclone but it also decreased the separation efficiency. On the contrary, the hydrocyclone performance was enhanced with increasing the inlet velocity. Furthermore, a comparison between the standard design and the conical inlet chamber design was drawn in terms of separation efficiency for low entrance oil concentration; the results depicted that the conical design had higher separation efficiency.     

油井采出液预分水用轴向水力旋流器的实验研究

高含水油井采出液的高效预分水是目前油气集输处理领域面临的关键难题之一,轴向水力旋流器因具有结构紧凑、分离效率高等优点而得到了国内外的广泛关注。本文针对自主研发的油井采出液预分水用轴向水力旋流器开展了室内实验研究。与切向水力旋流器对比,轴向水力旋流器不仅分离效率更高,而且油出口处的油滴聚结长大近1.8倍,在分水率高于50%的情况下,水出口处的含油浓度低于1000mg/L;轴向水力旋流器压降较低,且压降比与分流比呈线性相关。分流比、含水率和流量对分离性能均有显著影响,其中分流比的变化直接影响油核的大小和稳定性,室内样机的最佳分流比为0.45,当含水率为90%、处理量为1.00m³/h时分水率与含油浓度分别为62.9%和432.8mg/L;含水率高于75%时分离性能良好;室内样机的最佳流量为1.50m³/h。自主研发的轴向水力旋流器不仅满足性能要求,而且在操作弹性、可控性方面较切向水力旋流器均有一定的提升。     

Mathematical modelling of a hydrocyclone for the down-hole oil–water separation (DOWS)

In this study, a mathematical model is developed to predict the efficiency of a down-hole oil–water separation hydrocyclone. In the proposed model, the separation efficiency is determined based on droplet trajectory of a single oil droplet through the continuous-phase. The droplet trajectory model is developed using a Lagrangian approach in which single droplets are traced in the continuous-phase. The droplet trajectory model uses the swirling flow of the continuous-phase to trace the oil droplets. By applying the droplet trajectory, a trial and error approach is used to determine the size of the oil droplet that reaches the reverse flow region, where they can be separated. The required input for the proposed model is hydrocyclone geometry, fluid properties, inlet droplet size distribution and operational conditions at the down hole. The model is capable of predicting the hydrocyclone hydrodynamic flow field, namely, the axial, tangential and radial velocity distributions of the continuous-phase. The model was then applied for some case studies from the field tested DOWS systems which exist in the literature. The results show that the proposed model can predict well the split ratio and separation efficiency of the hydrocyclone. Moreover, the results of the proposed model can be used as a preliminary evaluation for installing a down-hole oil–water separation hydrocyclone system in a producing well.     

导叶式旋流器内油滴的聚结破碎及影响因素

利用流场测试实验和模拟计算对导叶式旋流器的内部流场和湍流性能进行研究,得到导致旋流场中油滴发生聚结破碎现象的内因为时均速度梯度引起的黏性剪切力和湍流流动引起的高剪切应力及湍动能,并分析了油滴破碎的主要发生部位。同时为宏观考察导叶式旋流器内油滴聚结与破碎相对作用强弱,验证了旋流器的分离性能作为表征量的可行性,并在此基础上,利用导叶式旋流器的分离性能实验结果对油滴聚结破碎发生的外因进行研究,结果表明导向叶片的结构参数（叶片数和叶片出口角）和旋流器的操作参数（入口流速、溢流率、分散相入口浓度和操作温度）均会影响到油滴在旋流器中的存在和运动形态。