Effect of acoustic and electric fields on concentration of dust in exhaust gas carried off from metallurgical units

声场和电场对冶金装置废气中粉尘浓度的影响

基本信息

批准号：
09650805
负责人：
KOMAROV Sergey
金额：
$ 2.18万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Agglomeration of particles exposed to sound waves was studied experimentally and theoretically in the present work. The mechanism of acoustic agglomeration is discussed with an emphasis on the particle collision and adhesion. Experiments were carried out under room and high (1300℃) temperatures. In the room temperature experiments, large (Fe, size 75〜90 μm) and fine Mo (averaged diameter 7.26 μm) or FeィイD22ィエD2OィイD23ィエD2 (averaged diameter 14.29 μm) particles were electrically precharged by passing them through a positive (fine particles) and a negative (large particles) corona charger. The charged particles were injected into a vessel within which a standing sound wave was formed and, then, were deposited on a slide. The particle size distribution was analyzed by an optical microscope. In the high temperature experiments, an Ar-OィイD22ィエD2 mixture was blown on to an iron bath (carbon content about 4.2%) melted in a resistance furnace. Simultaneously, a sound wave was propagated to the … More bath surface through the gas phase. Dust emitted during the decarburization reaction was trapped by a quartz or a Mo plate, after which the dust samples were analyzed by a SEM. The sound waves were irradiated by using a set of loudspeakers (1, 3 or 6 units) or a piezocristall generator. The frequency was ranged from 120 to 20776 Hz. Maximal input electrical power was 70 W (set of 6 speakers) and 100 W (piezocristall generator).The results can be summarized as follows. It was found that the particles are agglomerated with each other even neither acoustic nor electric fields applied. Sound waves of low frequency (120〜270 Hz) caused the particle agglomerates to disintegrate (Fe-Mo system). On the other hand, when the particles were exposed to sound on frequencies more than 300 Hz, the particle agglomeration was enhanced. The higher were the sound frequency and intensity, the larger was the effect of acoustic agglomeration. On the whole, charging of the particles resulted in a better agglomeration efficiency as compared with non-charged particles, especially for the Fe-Mo particle system. The results of the high temperature experiments showed the same tendency for an increase in agglomeration efficiency with sound frequency.In analyzing the experimental results, two theoretical considerations were used. The first one is the orthokinetic theory supplemented by a developed model of particle collision which makes possible explaining the particle behavior at low and medium frequencies. The second one is the radiation pressure model which provides a reasonable explanation on the sound effect at high frequencies. The presence of unlike electrical charges on the particle surface enhance attraction force between them. This effect is assumed to be of prime importance when the particles approach to each other to such a short distance that the other forces (inertial and radiation forces) become very small. Less

在当前的工作中，通过实验研究了暴露于声波的颗粒的聚集。讨论了声学集聚的机制，重点是粒子碰撞和粘合剂。实验在房间和高（1300℃）温度下进行。在室温实验中，大型（Fe，尺寸为75-90μm）和细Mo（平均直径7.26μm）或FeI D22IE D22OI D23IE D2（平均直径14.29μm）通过将它们通过正（细颗粒）和大型（大型颗粒）和大型CORONA和CORONA来电气固定在电气上。将带电的颗粒注入到一个容器中，在该容器中形成了常规声波，然后将其沉积在载玻片上。通过光学显微镜分析粒度分布。在高温实验中，将AR-OII D22混合物吹入在电阻炉中融化的铁浴（约4.2％）。同时，通过气相将声波传播到…更多的浴场表面。在脱氧反应期间发出的灰尘被石英或mo板捕获，然后通过SEM分析灰尘样品。使用一组扬声器（1、3或6个单元）或一个压电器发电机来辐照声波。频率的范围为120至20776 Hz。最大输入电力为70 W（一组6个扬声器）和100 W（Piezocristall Generator）。结果可以总结如下。发现这些颗粒甚至施加了声学和电场。低频（120-270 Hz）的声波导致粒子团聚发生（Fe-MO系统）。另一方面，当粒子在300 Hz以上的频率上暴露于声音时，粒子团聚就会增强。声音频率和强度越高，声音聚集的效果越大。总体而言，与非电荷颗粒相比，颗粒的充电会导致更高的聚集效率，尤其是对于Fe-MO粒子系统。高温实验的结果表明，通过声音频率增加了团聚效率的趋势。在分析的实验结果中，使用了两个理论考虑。第一个是由开发的粒子碰撞模型补充的正动理论，可以解释低和中等频率下的粒子行为。第二个是辐射压力模型，该模型在高频下对声音效应提供了合理的解释。与粒子表面上的电荷不同，它们之间的吸引力增强了它们之间的吸引力。当粒子彼此接近如此短的距离，以至于其他力（惯性和辐射力）变得很小时，假定这种效果是很重要的。较少的