共查询到18条相似文献,搜索用时 140 毫秒
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《化工学报》2016,(5)
精馏塔板上的气液两相流动对传质效率有重要影响。根据实验数据拟合得到平均气含率关联式,将其加入动量源项,采用Fluent软件对1.2 m直径的组合导向浮阀塔板上的气液两相流动进行CFD模拟,考察了塔板上的气液两相流动状况。清液层高度的模拟结果与实验数据关联式相吻合,验证了模拟的正确性。对塔板上液相的非理想流动进行了分析,通过对反向流进行量化和统计计算出反向流体积分数(即反向流体积占塔板总体积的百分比)。3块不同浮阀排布塔板的反向流体积分数时均值的计算结果表明,梯形浮阀和矩形浮阀的排布方式对反向流影响很大,通过合理排布能够使工业塔板的反向流体积分数时均值从22.0%下降到19.4%,降幅达到11.8%。本研究结果可望对塔板的设计和优化提供指导。 相似文献
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对组合导向浮阀塔板进行了水力学实验,测定了2块直径1m、不同浮阀排布的组合导向浮阀塔板的雾沫夹带和相关水力学数据。根据实验塔板的结构和尺寸参数建立几何模型,采用Fluent 6.3.26软件对板上气液两相流动进行CFD模拟,考察了塔板上的气液两相流动状况。清液层高度和雾沫夹带的模拟结果与实验结果吻合较好,验证了模拟的准确性。对两块不同浮阀排布的组合导向浮阀塔板的雾沫夹带和板上液体反向流进行了分析,结果表明在适当位置用导向能力更强的梯形浮阀代替矩形浮阀可有效降低雾沫夹带率和液体反向流比例,雾沫夹带率的实验值和模拟值分别降低了13.4%和10.6%,液体反向流比例降低了12.8%。研究结果表明,通过CFD模拟可望指导两种浮阀的合理排布和塔板的优化设计。 相似文献
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采用计算流体力学方法对直径为2 600 mm的工业规模双溢流立体传质塔板板上气液二相流动进行了模拟研究。计算了不同工况下收缩流和扩张流2种流型的液相流场分布,得到了双溢流塔板收缩流和扩张流2种流型的板上气液二相流场分布规律。通过将清液层高度的CFD结果和经验公式的计算结果进行对比,验证了所建模型的正确性。模拟计算结果表明:边降液管收缩流板面液相流动较均匀,近似于均匀的收缩流,不存在回流区;中降液管扩张流板面液相流动不均匀,靠近塔板中心流速较快,塔板弓形区存在着回流现象;板孔处的帽罩区液层较其他地方小,液相体积分数较其他地方低,扩张流受气相的影响较收缩流大。 相似文献
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<正>由于气体的搅动,筛孔塔板上的流动是极其复杂的气液两相流。目前两相流理论尚不成熟,未见运用此理论对塔板流速场的研究报道,Zhang和Yu的研究虽考虑了气相对液相流动的影响,但由于利用单相流理论,计算结果与实际情况有较大偏差。本文利用Elghobashi等建立的两相流双流体模型,建立了塔板上气液两相流二维流速场计算模型。在此基础上,通过调整模型参数,考虑了液层高度对塔板上返流区二维流型的影响,建立了模型参数值与液层高度的关系,实现了考虑液层高度影响的二维流动——拟三维流动的模拟。计算结果与Porter的实验结果基本相符。 相似文献
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本研究对筛孔型精馏塔板上的空气-水两相流进行了模拟,模拟方法采用基于开源软件平台OpenFOAM的双流体模型框架。模拟体系选用Solari-Bell经典实验体系,研究了不同操作条件下的气液两相流动参数,包括清液层高度、气相速度、液相速度和塔板压降等,模拟结果与实验结果的变化趋势基本一致。基于CFD模拟结果,分析了不同工况下塔内气液两相速度场与气含率分布等流动参数,结果表明本工作可以较好地捕捉塔板上的气液流动特征。进一步地,讨论了应用OpenFOAM模拟精馏塔内气液两相流动的若干影响因素,在此基础上分析了气液错流体系相间曳力对模拟结果的影响,实现了与使用商业软件模拟结果相接近的预测效果,验证了使用OpenFOAM模拟精馏塔体系的可行性。 相似文献
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基于分相流模型的气液两相流流量测量 总被引:1,自引:1,他引:0
从伯努利方程出发,基于分相流模型,推导出气液两相流流过文丘里管的流量公式.在分析了两相流通过节流装置的实际流动情况后,作者认为气液两相滑移比是影响流量公式误差的一个重要因素.在理论与实验研究的基础上,作者提出了气液两相流流过文丘里管的滑移比经验关联式.利用作者提出的滑移比经验关联式和分相流模型的流量公式测量两相流流量,体积流量误差的均方根小于5.1%,表明该方法适用流过文丘里管的两相流流量测量,尤其对于两相流动激烈的两相相互作用区域,流量误差满足测量的要求. 相似文献
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Computational fluid dynamics (CFD) has recentlyemerged as an effective tool for the investigation of the hydraulic parameters and efficiency of tray towers. The computation domain was established for two types of oriented valves within a tray and meshed into two parts with different grid types and sizes. The volume fraction correlation concerning inter-phase momentum transfer source was fitted based on experimental data, and built in UDF for simulation. The flow pattern of oriented valve tray under different operating conditionswas simulated under Eulerian-Eulerian framework with realizable k-ε model. The predicted liquid height from CFD simulation was in good agreement with the results of pressure drop and volume fraction correlations. Meanwhile, the velocity distribution and volume fraction of the two phases were demonstrated and analyzed, which are useful in design and analysis of the column trays. 相似文献
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Taleb Zarei Masoud Farsiani Jamshid Khorshidi 《Korean Journal of Chemical Engineering》2017,34(1):150-159
In order to better understand the hydrodynamics of valve trays, air-water operation in an industrial scale tower with 1.2 m of diameter, consisting of two 14% valve trays, was studied. Experimental results of clear liquid height, froth height, average liquid holdup, dry pressure drop, total pressure drop, weeping and entrainment were investigated, and empirical correlations were presented. Then, a three-dimensional computational fluid dynamics (CFD) simulation in an Eulerian framework for valve tray with ANSYS CFX software was done. The drag coefficient, which was used in the CFD simulations, was calculated from the data obtained in the experiments. The simulation results were found to be in good agreement with experimental data at this industrial scale. The objective of the work was to study the extent to which experimental and CFD simulations must be used together as a prediction and design tool for industrial trays. 相似文献
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A 3‐D two‐fluid CFD model in the Eulerian‐Eulerian framework was developed to predict the hydrodynamics and heat and mass transfer of sieve trays. Interaction between the two phases occurs via interphase momentum and heat and mass transfer. The tray geometries are based on the large rectangular tray of Dribika and Biddulph and FRI commercial‐scale sieve tray of Yanagi and Sakata. In this work a CFD simulation is developed to give predictions of the fluid flow patterns, hydraulics, and mass transfer efficiency of distillation sieve trays including a downcomer. The main objective has been to find the extent to which CFD can be used as a design and prediction tool for real behavior, concentration and temperature distributions, and efficiencies of industrial trays. Despite the use of simple correlations for closure models, the efficiencies obtained are very close to experimental data. The results show that values of point efficiency vary with position on the tray because of variation of affecting parameters, such as velocities, temperature and concentration gradients, and interfacial area. The simulation results show that CFD can be used as a powerful tool in tray design and analysis, and can be considered as a new approach for efficiency calculations and as a new tool for testing mixing models in both phases. CFD can be used as a “virtual experiment” to simulate tray behavior under operating conditions. 相似文献
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Taleb Zarei Ehsan Abedini Rahbar Rahimi Jamshid Khorshidi 《Korean Journal of Chemical Engineering》2017,34(4):969-976
This paper addresses an investigation on the hydrodynamic behavior of a new type of cap trays called conical cap tray (ConCap tray). A 3-D computational fluid dynamics model was developed to predict the hydrodynamics of the ConCap tray which is operated in the spray regime. The model considers two phase flow of gas and liquid in a VOF-like code framework. The homogeneous multiple size group model (MUSIG model) and shear stress transport (SST) turbulence model were implemented. Detailed insights into the hydrodynamic behavior of the inside of the cones were obtained. The relation between velocity, pressure and cross section area of the flow inside the cone also was formulated. The computational fluid dynamic (CFD) results show that the pressure variation in the cones forces the liquid on the tray to be highly turbulent, which leads to deform the interface to break up. Effect of different riser heights was also studied by CFD simulations. The results show that the riser height has a significant role in the hydrodynamics of the tray, especially in uniform gas distribution in the tray and reducing weeping rates. 相似文献
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We have studied the hydrodynamics of a reactive distillation sieve tray column in which catalyst containing wire-gauze envelopes are disposed along the liquid flow direction. The gas and liquid phases are in cross-current contact on the tray. Experiments were carried out to determine the clear liquid height on the tray as a function of tray geometry and operating conditions. The transient gas–liquid hydrodynamics on the tray was simulated using CFD techniques. The agreement between the experiments and CFD simulations was found to be very good, suggesting that CFD simulations can be used for design and scale-up purposes. 相似文献
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用VOF法模拟导向立体传质塔板罩内两相流 总被引:4,自引:4,他引:0
利用计算流体力学中的VOF方法对导向立体传质塔板(CTST-8)罩内气液两相流场进行了数值模拟,用Fluent的前处理软件gambit建立物理模型,在速度梯度大的地方采用局部加密网格,根据计算结果进行网格的自适应。用Fluent 6.1 对CTST-8在板孔气速为8.4 m/s,清液层高度为25 mm的工况下进行数值模拟。模拟结果显示了罩内流场的三维特性,并反映出罩内流场的相含率分布,速度分布以及压强分布等。将罩内压强的测量结果与模拟结果进行对比,两者吻合较好。说明本文数值模型具有较好的精度,可以用于CTST-8罩内两相流场的预测。 相似文献
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Sieve trays are widely used in fractionating devices like tray distillation towers existing in separation and purification industries. The weeping phenomenon that has a critical effect on the efficiency of tray towers was studied by a numerical model and some experiments. The experiments were carried out in a pilot scale column with the diameter of 1.22 m that includes two test trays and two chimney trays. Weeping rates and some hydraulic parameters were measured in sieve trays with the hole area of 7.04%. Furthermore, the total weeping rate and weeping rate in inlet and outlet halves of the test tray were determined. It was also used an Eulerian–Eulerian computational fluid dynamics (CFD) method for the present study. The model was able to predict the dry tray pressure drop, total pressure drop, clear liquid height, froth height, and weeping rate simultaneously. Furthermore, the obtained CFD results were in a good agreement with the experimental data in terms of pressure drop and the model properly predicted several hydraulic parameters like the liquid weeping behavior along the tray. 相似文献