旋风静电除尘器流场分布测试研究

利用五孔探针系统对直筒式旋风静电除尘器模型的三维流场进行了测定与分析。结果表明：随着入口风速、供电电压增加，旋风静电除尘器内气流的切向和径向速度分别增加，各截面轴向速度沿半径的分布基本相似；与旋风除尘器相比，旋风静电除尘器内气流的切向速度和径向速度的变化更为平缓，入口风速为8．5m／s时，在0．3～0．5倍简体直径时，切向速度达最大。     

直筒式旋风脉冲静电除尘器性能研究

实验研究了电压、入口粉尘浓度和入口风速对直筒式旋风脉冲静电除尘器除尘效率的影响,测定了在不同入口风速下除尘器的分级效率.结果表明,脉冲供电能显著提高除尘器的除尘效率和分级效率,在脉冲电压为80 kV、入口粉尘质量浓度为5.0 g/m3N、入口风速为7～10 m/s时,除尘效率在99%以上,并在实验的基础上分析了脉冲供电下除尘器的除尘机理.     

旋风除尘器内部流场的数值研究

通过建立旋风除尘器模型,模拟了排气管插入深度对旋风除尘器的压降、气流的切向速度和轴向速度的影响。研究表明,增加排气管的插入深度会增大旋风除尘器的压力损失,但对其内部压力分布的影响却比较小;增加排气管的插入深度对气体切向速度和轴向速度的影响也比较小,在不同高度上,内外旋流交界处切向速度的最大值都有所增加,这会产生更大的离心力,除尘效率也会因此而提高。     

球柱形旋风除尘器分离性能数值模拟与实验

针对传统柱锥形旋风除尘器存在细颗粒分离效率低的问题,提出了一种新型球柱形旋风除尘器。采用数值模拟和实验研究手段,分析了柱段高度对球柱形旋风除尘器分离特性的影响。模拟结果表明:当球柱形旋风除尘器柱段高度不为零时,随着柱段高度的增加,静压力逐渐变小;球柱形旋风除尘器内流体的切向速度均呈"M"型分布;流体轴向速度随着半径的减小,其绝对值先增大后减小,在中心轴线处又开始增大;流体径向速度均关于中心轴线对称。实验结果表明,当球柱形旋风除尘器柱段高度为150 mm时,总分离效率最高,可达到92.01%。研究结果可为旋风除尘器中细小颗粒分离应用提供指导,对提高5μm以下颗粒分离效率具有重要意义。     

旋风除尘器环形空间气流运动的数值研究

运用计算流体力学软件FLUENT,对旋风除尘器内部流场进行了数值模拟,利用模拟结果对旋风除尘器入口不同位置气流在除尘器顶部的环形空间的轨迹进行了分析研究,探明了气流在环形空间的运动规律和基本特征,阐明了旋风除尘器顶部"尘环"形成的根本原因,指出了粉尘发生短路的原因和多发区域并在此基础上就除尘器的增效问题给出了改进方案.     

离心脉冲静电除尘器内颗粒浓度场测试分析

在离心脉冲静电除尘器研究的基础上 ,进行了离心脉冲静电除尘器内的浓度场的测试分析 ,并得出了在一定入口风速、工作电压、入口粉尘浓度下其颗粒浓度场分布规律及实测回归方程。     

壁面粗糙度对旋风分离器内流场影响的数值模拟

利用计算流体动力学软件FLUENT6.2.16对壁面粗糙度不同的旋风分离器内流场进行了数值模拟,得到了切向速度、轴向速度、径向速度和静压力分布规律。旋风分离器内的切向速度随着壁面粗糙度的增大而明显减小;轴向速度没有明显的规律性变化,只在上部筒体涡核区轴向速度增加,削弱了涡核区滞留现象;在流场大部分区域径向速度随粗糙度的...     

离心脉冲静电除尘器内颗粒浓度场测试分析

在离心脉冲静电除尘器研究的基础上，进行了离心脉冲静电除尘器内的浓度场的测试分析，并得出了在一定入口风速、工作电压、入口粉尘浓度下其颗粒浓度场分布规律及实测回归方程。     

新型低阻高效旋风除尘器性能的模化实验研究

模化方法是将实验室内模型的实验结果推广到实物中去的最有效方法。依据归纳的旋风除尘器近似模化条件，对新型低阻高效旋风除尘器进行了模化实验研究。新型除尘器模化实验结果与工业化实验结果比较表明，该模化方法是成功的。为新型除尘器的系列化结构设计提供依据。     

静电除尘器烟道进口处流场的数值模拟

利用Fluent软件对静电除尘器烟道进口处流场进行了数值模拟,在此基础上提出一种新型的能有效均风的电晕线布置方法.结果表明,两相邻(垂直叠放)烟道进口处的电晕线平行放置时,在强电场力作用下产生的高速离子风会阻碍气流的均匀分布；两相邻烟道进口处的电晕线交叉放置时,可以起到明显的均风效果,更有利于除尘器内气流的均匀分布和提高除尘效率.该方法为静电除尘器的改造和设计提供了一种新的思路.     

基于大涡模拟的旋风分离器内流场数值模拟研究

为了研究旋风分离器内流场的运动状况,借助Fluent软件,采用大涡模拟,基于曲线坐标系的SIMPLEC算法,对切向入口的Stairmand旋风分离器内流场进行了三维数值模拟研究。数值结果表明,大涡模拟适合于三维强旋流的流场模拟,分离器内部的流动空间可分为内、外2个流动区域,在不同的流动区域中,气体压力、速度场的分布有较大的差异。而且压力分布与速度分布不是绝对的轴对称分布。数值模拟结果对其设计优化研究有一定的应用价值。     

直筒型导叶直流式三相旋流器排气管上部内流场的实验研究

使用五孔球探针对一种用于分离锅炉净化烟气中含尘液滴的直筒型导叶直流式三相旋流器排气管上部的气相流场进行了实验测定。得到了这一区域的速度和静压分布。发现了排气管上部筒体中心存在强烈的内旋流;外层气体不断汇入内旋流,内旋流呈轴向加速运动;绝大部分气体不经过排气管外环形空间下行直接由排气管排出。主体段切向速度为Rankine组合涡。     

旋风分离器排气管最佳插入深度的实验与分析

采用实验方法考察物料特性、入口气速、排气管直径、入口截面积4种因素对排气管最佳插入深度的影响。实验结果表明,排气管的最佳插入深度主要受粉料中位粒径和粒径分布的影响,中位粒径越小,包含的小粒径颗粒越多,最佳插入深度越大,而与其他3项参数无关。另外,插入深度在最佳位置附近变化时,效率波动不大,远离最佳位置后,效率大幅下降,并且在大排气管直径,大入口条件下,效率对插入深度更为敏感。短路流和内旋流二次分离的协同作用是形成以上现象的主要原因。     

An Experimental Study of Hopper Evacuation Effects on Multitube Cyclone Performance

An experimental multitube cyclone facility was constructed and experiments conducted to investigate the influence of hopper evacuation on multitube cyclone performance. The effects of the amount of hopper evacuation and the location of hopper evacuation on individual cyclone tube velocities and particle collection efficiency were determined. Cyclone tube velocities increased with increasing hopper evacuation although hopper evacuation location had little effect on the velocities. Particle collection efficiencies were increased from 89.5 percent to approximately 95 percent with 14 percent hopper evacuation from a location near the center of the hopper. Other hopper evacuation locations were not as effective in increasing collection efficiency. These results suggest that, while the increased velocity in the cyclone tubes is an important effect in the improvement of multitube cyclone performance with hopper evacuation, other factors such as redistribution of gas flow within the hopper are also important.     

水力旋流器速度场的PDPA测试研究

应用相位多普勒粒子分析仪(PDPA)对液液水力旋流器模型的内部流场进行了测试,分析了旋流器内部速度场的特点。通过进口流量的变化,测试了该模型的不同截面上的速度场分布情况。测试结果表明:随着流量的增大,旋流器轴截面上的速度都增大,旋流变大,有利于连续相和分散相的分离;旋流器中连续相和分散相速度分布趋势相同,但在管芯处,两者速度滑移明显。     

Numerical investigation of the flow profiles in the electrically enhanced cyclone

A numerical model for simulation of the electrohydrodynamic flow in an electrically enhanced cyclone is presented. A finite element approach was applied to solve the coupled equations for the positive corona-induced electric field. Three-dimensional simulations of gas flow were carried using Reynolds-Averaged Navier-Stokes equations including the Reynolds stress model and the electrohydrodynamic effect. Numerical results show that the change in the flow profile because of the influence of the corona-induced electric field is apparent when the inlet flow rate is low but is negligible at higher flow rates.     

Effect of flow distributors on uniformity of velocity profile in a baghouse

In recent years, the utility industry has turned to baghouses as an alternative technology for particulate emission control from pulverized-coal-fired power plants. One of the more significant issues is to improve poor gas distribution that causes bag failures in baghouse operation. Bag failures during operation are almost impossible to prevent, but proper flow design can help in their prevention. This study investigated vertical velocity profiles below the bags in a baghouse (the hopper region) to determine whether flow could be improved with the installation of flow distributors in the hopper region. Three types of flow distributors were used to improve flow distribution and were compared with the original baghouse without flow distributors. Velocity profiles were measured by a hot-wire anemometer at an inlet velocity of 18 m/sec. Uniformity of flow distribution was calculated by the uniformity value U for the velocity profile of each flow distributor. Experimental results showed that the velocity profile of the empty configuration (without flow distributors) was poor because the uniformity value was 2.048. The uniformity values of type 1 (flow distributor with three vertical vanes), type 2 (flow distributor with one vertical and one inclined vane), and type 3 (flow distributor with two inclined vanes) configurations were reduced to 1.051, 0.617, and 0.526, respectively. These results indicate that the flow distributors designed in this study made significant improvements in the velocity profile of a baghouse, with the type 3 configuration having the best performance.