涡流澄清技术在污水处理中的应用

介绍了微涡流混凝工艺的核心一涡流反应器的特点及其微涡流凝聚与立体接触絮凝的混凝反应机理.同时介绍了它在上海宝钢革污水回用处理工程中的应用情况:设计时调整澄清池进水装置及部分内部结构,增大反应室体积,在反应室中加入涡流反应器,沉淀区加设斜管.经1年多运行,效果显著,涡流澄清池处理规模增大/水力负荷增大,澄清池出水浊度稳定在3 NTU以下,经V型滤池过滤后出水浊度小于1 NTU,涡流吨水投资在35元以下.     

微涡流混凝工艺的应用及展望

介绍了微涡流混凝工艺的机理,同时对微涡流混凝工艺在给水和污水处理中的应用情况进行了综合论述,展望了微涡流混凝工艺的发展前景。     

换热管涡流检测与抗腐蚀技术的研究

综述了换热管涡流检测工作原理、设计、制造过程及换热管腐蚀原因和提出了相应措施.结果证明措施.结果证明措施是可行的.上述测检与抗腐蚀技术可降低物材损失、减排,又可安全生产、取得很好的经济效益,且它在很多领域很有推广应用价值.     

容器排液时涡流的产生及其防止

西方对于避免产生涡流的最低液位进行探讨。同时对防涡流隔板和防涡流档板的尺寸进行初步分析。     

涡流选粉机使用中应注意的一些问题

涡流选粉机在我国已有２００多家水泥厂使用 ,也有许多成功的经验介绍 ,但有一些用户使用中存在不少问题 ,造成系统产量低、故障多、设备运转率低 ,生产无法正常进行 ,严重影响粉磨系统能力的正常发挥。本文就一些常见问题进行分析探讨 ,供厂家、用户参考借鉴。１涡流选粉机的结构和工作原理涡流选粉机主要由涡壳、导流叶片、涡流转子和传动装置组成 ,其结构如图１所示。其工作原理为 :物料由进料口喂入机内涡流转子上部的撒料盘上 ,传动机构带动涡流转子旋转 ,物料在撒料盘栅格作用下撒向四周碰到挡料板后被充分打散 ,落入选粉区域。由一、…     

气泡-液体闭式射流的大涡与二阶矩模拟

The Large-eddy simulation (LES) with two-way coupling is used to study bubble-liquid two-phase confined multiple jets discharged into a 2D channel.The LES results reveal the large-eddy vortex structures of both liquid flow and bubble motion,the shear-generated and bubble-induced liquid turbulence,and indicate much stronger bubble fluctuation than that of the liquid,the enhancement of liquid turbulence by bubbles.Both shear and bubble-liquid interaction are important for the liquid turbulence generation in the case studied.     

利用高效涡流选粉机改小型磨开流为闭流

1.现 状 我国水泥年生产能力已达到3亿吨,其中小厂水泥产量占总产量的3/4,在众多的小水泥厂中,广泛地使用着φ1.5×5.7m和φ1.83(长度有多种)磨机。怎样提高这两类磨机的产量和降低能耗是水泥工业的重大课题。由于这两类磨机直径比较大,在工艺设计时一般都采用开流系统。实践表明,尽管人们     

电磁涡流检测质量控制中应注意的事项

通过对电磁涡流检测质量控制中最为关键的人员资格、设备器材、技术文件、操作过程四个因素进行分析,总结出应注意的事项和要求,确保电磁涡流检测质量。     

分解炉内气固两相流动特性的数值模拟

采用Eulerian—Eulerian气固两相双流体模型、大涡模拟方法模拟气相湍流流动、颗粒动力学理论模拟颗粒相流动,数值模拟分解炉内气固两相流体的动力特性。用小波分析方法研究分解炉内气固两相湍流特性。在分解炉中心区域形成高浓度-高速度的上升颗粒流、在壁面区域形成高浓度、低速度的下降颗粒流,构成颗粒的内循环流动。     

微涡流处理造气污水新工艺

介绍微涡流处理造气污水新工艺，分析技术和经济特点。通过实际运行，证明是一种较好的处理造气污水的方法，可在化肥行业中推广。     

A New Method of Eddy Diffusivity Calculation for Droplets of a Venturi Scrubber

An analytical model using eddy diffusivity is applied for predicting droplet concentration distribution and liquid film formation in a Venturi scrubber. By comparing experimental data of film formation reported in literature (Viswanathan et al., 1984) and the results obtained from this model, a semi‐empirical correlation for liquid droplets eddy diffusivity is obtained. The validity of this correlation is confirmed by obtaining good agreement between theoretical and experimental data of droplet concentration distribution and film formation in a Venturi scrubber (Viswanathan, 1998; Viswanathan et al., 1984).     

Relative importance of the lift force on heavy particles due to turbulence driven secondary flows

Saffman lift forces on dense particles due to gradients in both streamwise and cross-stream velocities in a downward, fully developed turbulent square duct flow at Re_τ = 360 are studied using large eddy simulations. Volume fraction of the dispersed phase is low enough (≤ 10^− 5) that the one-way coupling approach is reasonable, i.e., two-way coupling and particle-particle collisions are not considered. Eulerian and Lagrangian approaches are used to treat the continuous and dispersed phases, respectively. Subgrid stresses are modeled with the dynamic subgrid kinetic energy model of Kim and Menon [W.W. Kim and S. Menon. Application of the localized dynamic subgrid-scale model to turbulent wall-bounded flows, AIAA 97-0210, 1997.]. The particle equation of motion includes drag, lift forces due to both the streamwise and cross-stream velocity gradients, gravity, and is integrated using the fourth-order accurate Runge-Kutta scheme. Dependence of particle drag and lift forces on duct cross-sectional location and particle response time is demonstrated using the mean value contours and probability density functions (PDFs) of particle forces. It is shown that the streamwise component of the mean drag force experienced by particles of all response times is a deceleration force, i.e. on average, fluid streamwise velocity lags the particle streamwise velocity. Secondly, the two wall-normal (or lateral) components of the mean drag force are oriented such that the particles experience a net mean force toward the duct corners. PDFs of particle drag force components show that smaller response time particles experience a wider range of drag force about the mean value, as compared to the more inertial particles. Contours of mean wall-normal lift forces due to streamwise velocity gradients show that this force predominantly acts toward the duct walls and that the maximum lift force occurs close to the walls. PDFs of lift force due to streamwise velocity gradients show that the range of fluctuations increases with particle response time, but the dependence on particle response time is weaker compared to drag force. Lift forces due to cross-stream velocity gradients are at least an order of magnitude smaller than lift forces due to streamwise velocity gradients and are found to decrease in their range of fluctuations with particle response time. It is demonstrated that lift forces due to secondary flow velocity gradients are not as important as those due to streamwise velocity gradients in a square duct flow.     

颗粒尾涡增强湍流的大涡模拟以及气固两相流中湍流变动的数值模拟

The turbulence enhancement by particle wake effect is studied by large eddy simulation （LES） of turbulent gas flows passing a single particle. The predicted time-averaged and root-mean-square fluctuation velocities behind the particle are in agreement with the Reynolds-averaged Navier-Stokes modeling results and experimental results. A semi-empirical turbulence enhancement model is proposed by the present-authors based on the LES resuits. This model is incorporated into the second-order moment two-phase turbulence model for simulating vertical gas-particle pipe flows and horizontal gas-particle channel flows. The simulation results show that compared with the model not accounting for the particle wake effect, the present model gives simulation results for the gas turbulence modulation in much better agreement with the experimental results.     

Modeling and Large Eddy Simulation of Deflagration Dynamics in a Closed Vessel

The paper describes a large eddy simulation model of gaseous deflagration in a closed vessel and simulation results for stoichiometric hydrogen–air premixed combustion initiated at the center of a closed 6.37m³ spherical vessel. The model is based on the large eddy simulation approach to turbulence modeling and the gradient method to model the mass burning rate in premixed combustion. The method for simulated flamefront thickness reduction is suggested, and its performance is investigated. The solutionadaptive mesh refinement is used to decrease the CPU time required for simulation. The simulated deflagrationpressure dynamics is in agreement with published experimental data, and the flamefront velocity is in agreement with simulation results obtained according to the lumped parameter model for the same experiment.     

旋风管分离器流场模拟研究

旋风管作为多管式旋风分离器的主要元件,已经成为气固两相分离的重要研究对象,主要用于处理气量较大且对分离效率要求较高的工况。本文采用大涡模拟的方法考察了分离器内切向与轴向速度分布形态的影响。模拟结果表明：在一定程度上加长排气管的插入深度对分离效率的提升是有益的;旋风管筒体太长对分离效率的提高作用不大;增大排气管直径有助于降低降压。     

气液鼓泡床内的液体流速分布

引言 鼓泡床是一种重要的气液或气液固多相反应器.液体循环流动是鼓泡床的一个重要流体力学特征,从20世纪50年代人们就开始对此进行了比较系统的实验研究[1-6].这个特征对鼓泡床的流体返混行为、气含率、气液界面积以及传热传质系数都有很大影响,特别是液体返混行为可以由液体循环特性直接决定.如何准确地描述和预测鼓泡床中的液体流速沿径向的分布,关系到鼓泡床反应器的设计、放大和优化.因此,许多年来它一直是人们致力探讨的重要课题之一[7-8].     

颗粒的湍流扩散

<正>1引言 在淤浆输送、流态化、分离、搅拌等化工过程中,经常涉及颗粒在湍流中的扩散,对这类问题,一般先确定颗粒的湍流扩散系数,然后用类似Fi。k定律的梯度扩散定律处理。因此,如何确定颗粒的湍流扩散系数是解决问题的关键。目前有关颗粒湍流扩散系数的计算公式主要适用于小颗粒,如常用的Hinze-Tchen公式     

薄膜微型电感器等效电路分析

提出了磁性薄膜电感器的改进型等效电路模型。基于改进型等效电路,通过有限元法对薄膜电感器进行仿真研究,分析电感器的各个结构参数以及材料的特性参数对电感器整体性能的影响,并讨论了涡流效应和磁性薄膜对薄膜电感器特性的影响。结果表明选用较高电阻率的磁性薄膜和优化磁路设计,是薄膜电感器设计中必须考虑的问题。