Holdup and characteristic velocity in a Hanson mixer–settler extraction column

The hydrodynamic behavior of a pilot plant Hanson mixer–settler extraction column has been studied for three different liquid–liquid systems with and without mass transfer conditions. The dispersed phase axial holdup profile is investigated and an empirical correlation for prediction of dispersed phase holdup is recommended in terms of physical properties of liquid systems and operating conditions. A comparison between several correlations and experimental results shows that Pratt equation is more suitable for prediction of slip velocity because of its simplicity. On this basis, an empirical correlation is derived for prediction of characteristic velocity in terms of physical properties of liquid systems and operating conditions.     

Solvent extraction —Past and future—

In these modern times, with the amazing progress of science, manufacturing processes are constantly changing and improving. In the production of vegetable oils, however, a system dating back to Biblical times is still being used. Will solvent extraction be able to supplant the press system?     

CFD并行计算技术的研究进展

综述了并行计算技术在计算流体动力学(CFD)中的研究及应用进展,介绍了CFD并行化的关键技术研究近况,包括网格处理技术、并行化算法技术以及并行计算平台的研究进展.最后讨论了CFD并行技术的发展方向.     

泰勒—库特反应器流场演变的CFD研究

本文建立了泰勒—库特反应器流场的CFD模型,模拟研究了反应器内筒不同转速下,环隙流场结构的演变。结果显示,当转速为0.274 rad/s,环隙流场为库特泊肃叶流;当转速从0.315 rad/s升高至0.684 rad/s时,环隙流场从层流泰勒涡流转变为波流泰勒涡流。本文研究为泰勒—库特反应器在不同领域的应用奠定了流体力学基础。     

Economic analysis in product design——A case study of a TCM dietary supplement

An approach for the economic analysis of chemical product design is proposed. It takes into account of customers' preference on product quality and economic considerations such as pricing, profit, market share, capital investment, and operating cost. The activities needed to support business decision making – identifying product quality, estimating product cost, calculating financial metrics, and performing make–buy analysis – are discussed.The design of a Ganoderma lucidum dietary supplement, a traditional Chinese medicinal(TCM) product, is used to illustrate all the activities in this approach.     

CFD-based optimization and design of multi-channel inorganic membrane tubes☆

As a major configuration of membrane elements,multi-channel porous inorganic membrane tubes were studied by means of theoretical analysis and simulation.Configuration optimization of a cylindrical 37-channel porous inorganic membrane tube was studied by increasing membrane filtration area and increasing permeation efficiency of inner channels.An optimal ratio of the channel diameter to the inter-channel distance was proposed so as to increase the total membrane filtration area of the membrane tube.The three-dimensional computational fluid dynamics(CFD) simulation was conducted to study the cross-flow permeation flow of pure water in the 37-channel ceramic membrane tube.A model combining Navier–Stokes equation with Darcy's law and the porous jump boundary conditions was applied.The relationship between permeation efficiency and channel locations,and the method for increasing the permeation efficiency of inner channels were proposed.Some novel multichannel membrane configurations with more permeate side channels were put forward and evaluated.     

Gas permeation — module design and arrangement

Gas permeation by means of membranes is a very simple operation in chemical engineering, and its technical use is already possible in some cases. The dThis paper points out the criteria which enable us to estimate whether the flow pattern in the module is of importance under the given conditions of opFurthermore, suitable module arrangements for enrichment of air with oxygen and of biogases or landfill gases with methane are presented and compared rThis paper also deals with the method of operating with a low pressure on the permeate side, which is frequently mentioned in connection with gas permeFinally, the influence of the Joule-Thomson effect on the separation characteristic is discussed. An example demonstrates that if this effect is not taThe paper analyses flow pattern in gas permeation modules and module arrangements. The analysis leads to the conclusions that in most technically relevThe optimal module arrangements for two important cases, enrichment of oxygen from air and production of methane from biogas, are one- or two-stage casThe question whether the application of vacuum at the permeate side is economical or not has been discussed for the case of methane production from bio     

Steady-state operation analysis of an ideal heat integrated distillation column

A systematic approach for the steady-state operation analysis of chemical processes is pro-posed.The method affords the possibility of taking operation resilience into consideration during thestage of process design.It may serve the designer as an efficient means for the initial screening ofalternative design schemes.An ideal heat integrated distillation column(HIDiC),without any reboileror condenser attached,is studied throughout this work.It has been found that among the various va-riables concerned with the ideal HIDiC,feed thermal condition appears to be the only factor exertingsignificant influences on the interaction between the top and the bottom control loops.Maximuminteraction is expected when the feed thermal condition approaches 0.5.Total number of stages andheat transfer rate are essential to the system ability of disturbance rejection.Therefore,more stagesand higher heat transfer rate ought to be preferred.But,too many stages and higher heat transfer ratemay increase the load of the compres     

CFD方法在固定床反应器传热研究中的应用

固定床反应器是一种常见的化学和生化反应器,由于内部结构十分复杂,固定床内的局部流动和传热过程研究一直是一个颇具挑战性的问题。有效参数法是长期以来固定床传热研究的常用方法,但是由于对固定床内温度场缺乏准确的了解,目前为止许多基于有效参数法的传热模型的普适性仍然存在问题。计算流体力学（CFD）的数值模拟方法是近年来应用于固定床流动和传热研究的一种新的研究方法,它通过数值方法求解流动和传递的微分方程组而获得流场和温度场。CFD数值模拟方法能够提供精确的局部流动和传递信息如速度分布、压力分布、温度分布、组分浓度分布等。本文综述和分析了CFD方法在固定床反应器的流动和传热研究领域的最新进展,讨论了CFD方法在该领域的应用前景。     

CFD在精馏分离中的应用

计算流体力学(CFD)是研究精馏塔内气液两相流动和传质的重要工具.本文介绍了板式塔和填料塔内气液流动状况,塔板上和填料层的流体力学模型,论述了国内外CFD技术在精馏塔流场模拟方面的应用,指出了CFD技术在精馏领域的发展方向,对于板式塔,应充分考虑气液两相间的相互作用,对于填料塔,应根据填料的具体形状建立每个孔道的流体力学方程,进行更接近实际的三维两相流模拟.     

Measurement and CFD simulation of single-phase flow in solvent extraction pulsed column

A CFD (computational fluid dynamics) model of a solvent extraction pulsed column has been developed and run with a single water phase. The results are compared with experimental measurements taken on a pilot scale column using PIV (particle image velocimetry).The pulsed column investigated had disk-doughnut internals and was operated under pulsing intensities ranging from 10 to 32.5 mm/s. PIV measurements of velocity were used to validate the CFD model and to characterise the pulsing flow of a single phase through the column. The CFD modelling was performed for the same geometry and operating conditions using a 2D computational grid and a low Reynolds Number k-ε turbulence model. An improved velocity prediction was achieved by adding a gap between the doughnut internal and the pulsed column wall. The combined measurements and predictions give insight into the effect of the geometry internals on the flow hydrodynamics in the pulsed column.     

Simulation of oscillatory baffled column: CFD and population balance

In the present work, an attempt has been made to combine population balance and a CFD approach for simulating the flow in oscillatory baffled column (OBC). Three-dimensional Euler-Euler two-fluid simulations are carried out for the experimental data of Oliveira and Ni [2001. Gas hold-up and bubble diameter in a gassed oscillatory baffled column. Chemical Engineering Science 56, 6143-6148]. The experimental data include the average hold-up profile and bubble size distribution in the OBC. All the non-drag forces (turbulent dispersion force, lift force) and the drag force are incorporated in the model. The coalescence and breakage effects of the gas bubbles are modeled according to the coalescence by the random collision driven by turbulence and wake entrainment while for bubble breakage by the impact of turbulent eddies. Predicted liquid velocity and averaged gas hold-up are compared with the experimental data. The profile of the mean bubble diameter in the column and its variation with the superficial gas velocity is studied. Bubble size distribution obtained by the model is compared with the experimental data.     

含垂直列管束内构件鼓泡塔的CFD模拟

针对含有密集垂直列管束内构件的气液鼓泡塔,在两相Euler二维轴对称k-ε模型中,分别考虑气相和液相受到的列管阻力。通过引入相应的动量源、湍动源以及耗散源建立带列管内构件的鼓泡塔二维CFD模型。模型能清晰、准确地描述带列管束鼓泡塔中气液流动的特征:"烟囱效应"以及分布器影响区延长。计算得到的气含率以及液速的二维分布在宽泛的表观气速(0.12～0.62 m·s^-1)范围内与实验值相符。     

二维鼓泡床内气泡尺寸分布的实验与CFD模拟

在有机玻璃制成的二维鼓泡床(0.20m×0.02m×2.00m)内,采用摄像法对空气－自来水的气液两相体系的气泡尺寸分布进行了考察。以商业计算流体力学软件ANSYS CFX 10.0为平台,在双流体模型的基础上,采用k-ε湍流模型和GRACE曳力模型对气液鼓泡床内流体动力学行为进行了多相流CFD数值模拟。结果表明 MUSIG(Multiple Size Group)模型实现了对多气泡体系内气泡尺寸分布特性的考察,气泡尺寸分布的模拟结果与实验结果吻合得较好,从而说明了考虑了气泡聚并破碎的MUSIG模型能很好地反映出鼓泡床内气泡尺寸分布特性。     

Design of a fully thermally coupled distillation column based on dynamic simulations

A dynamic simulation of a fully thermally coupled distillation column is conducted for the design of a possible operation scheme, and its performance is examined with an example process of butanol isomer ternary system. The outcome of the dynamic simulation indicates that the column can be operated by using a 3 × 3 control structure. The structure consists of three controlled variables of the compositions of overhead, bottom and side products and three manipulated variables of the flow rates of reflux and steam and liquid split ratio between a main column and a prefractionator. This paper was presented at The 5th International Symposium on Separation Technology-Korea and Japan held at Seoul between August 19 and 21, 1999.     

A new multi‐scale model based on CFD and macroscopic calculation for corrugated structured packing column

A multi‐scale approach with the combination of computational fluid dynamic (CFD) and macroscopic calculation methods has been proposed to predict the hydrodynamics behavior in the corrugated structured packing column. On the basis of the concept of the representative unit, the three‐dimensional (3‐D) volume of fluid (VOF) model of the structured packing is applied in the small scale simulation, and the stream split fraction coefficients and effective wetted area ratio are calculated. The unit network model, which is a mechanistic model, is applied in large scale calculation basing on the small scale results. The liquid holdup distribution in the entire column can be available by this multi‐scale method. A comparison between the simulation results and the experimental data of our previous work is given to validate the present model. The multi‐scale model is proved to be prospective to assist the analysis and design of structure packing columns in chemical engineering. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3119–3130, 2013     

隔板塔气体调配装置数值模拟及实验研究

针对隔板塔中隔板两侧气体分配比难以调节的问题,提出了一种新型隔板塔气体调配装置。利用计算流体力学软件STAR-CCM+对该装置的性能进行了模拟分析,并经实验研究对模拟结果进行验证;对不同塔径下升气槽个数进行了模拟研究。结果表明:该气体调配装置能够有效地调节气体在隔板两侧的分配,并且气体通过该装置后分布较均匀,成功实现了气相在隔板塔内的分配控制,实验结果和模型模拟值符合良好。     

基于CFD流场模拟的反应釜结构设计

反应釜是制药化工产品生产的主要设备之一,常以搅拌的形式出现。本文研究了搅拌器相关设计参数对反应釜内流场的影响,并以此为依据改进反应釜结构。首先通过工程设计方法得到小型制药搅拌釜的初始设计方案,利用CFD技术对搅拌釜内的流场进行数值模拟研究,所得结果与文献中的结果基本一致。然后调整反应釜搅拌器的安装高度与搅拌转速等设计参数,与初始设计方案进行模拟结果对比分析,根据混合效果与驱动输入功率等设计要求,修改设计参数得到更优的设计方案。     

On the development of flow pattern in a bubble column reactor: Experiments and CFD

A comprehensive analysis of the development of flow pattern in a bubble column reactor is presented here through extensive LDA measurements and CFD predictions. In the LDA measurements, the simultaneous measurements of 2D velocity-time data were carried out at several radial locations and many axial cross-sections of the column for two different spargers. The profiles of mean axial liquid velocity, fractional gas hold-up and bubble slip velocity showed excellent agreement between the predictions and the experimentally measured values. The experimental results showed that the mean tangential velocity varies systematically in the radial as well as along the axial co-ordinates. The turbulence parameters viz. turbulent kinetic energy, energy dissipation rate and eddy diffusivity were also analysed. The estimated values of local energy dissipation rate obtained using eddy isolation model were used for establishing the energy balance in the column. The experimental data were used for the estimation of normal and shear stress profiles. For the case of single point sparger, just above the sparger region, the bubble plume was seen to have a strong tangential component of motion thereby yielding higher gas hold-up slightly away from the centre. This visual observation was well captured in profiles of all the hydrodynamic parameters obtained from the experimental data. CFD simulations of the mean velocities, gas hold-up and turbulent kinetic energy compared well with the experimental results.     

CFD modeling of the effect of absorbent size on absorption performance of a packed bed column

This paper reports a study on the ability of the computational fluid dynamics (CFD) modeling for analyzing the fluid flow hydrodynamics and absorption in a packed bed column. The water absorption by silica gel absorbents in an experimental packed bed was investigated, and the absorption performance of two different sizes of absorbent was studied. A series of experiments were carried out for five setups which are different in the weight ratio of the employed big to small absorbents. The CFD modeling was carried out for all five experimental setups. The predicted results show that by more replacing of the big absorbents with the small ones the water absorption increased. On the other hand, a greater pressure drop was observed as more small absorbents were used. The predicted absorption rates were compared with the measured values and on average a consistency within 11.6% was observed.