离心脉冲静电除尘器流场分布测试研究
摘 要
本文较全面地检索了国内外有关静电与旋风除尘技术的文献资料，测试研究了脉冲供电时直筒式离心脉冲静电除尘器内部的流场分布，得出了各种不同实验条件下三维流场分布规律及入口风速和脉冲供电电压对流场分布的影响，并就进一步弄清离心脉冲静电除尘器内部整体流场的分布规律及其除尘机理和优化结构设计参数提出几点建议。实验研究得到的主要结论如下：
〈1〉无供电情况下的离心脉冲静电除尘器相当于筒体中间带有一根金属线的普通旋风除尘器。内部气流的切向速度和径向速度沿筒体壁向方向大体上先增大后减小，轴向速度分布则无规律可循。且径向速度随着入口风速的增大在中心涡核处开始出现小部分沿筒体壁向方向的径向流。
〈2〉在脉冲电压为45Kv的条件下，切向速度随着入口风速的增大而增大；轴向速度的整体变化比较平缓，并呈现出一定的规律性；径向速度的分布曲线近似水平直线。
〈3〉在入口风速为8.5
的条件下，脉冲电晕电压越高，相应的切向速度越小，轴向速度越大，径向速度变化不明显。随着半径的增大，切向速度基本上逐步变小，轴向速度先减小后又逐步增大，径向速度的分布曲线则比较平稳。
〈4〉与普通旋风除尘器相比，离心脉冲静电除尘器内部流场的分布规律有所改善，更有利于除尘。这可能是因为电晕极线和电风的影响使得除尘器内部流场的湍流度反而减小，要证实这一点还有待于进一步通过实验深入研究。
关键词 离心脉冲静电除尘器；除尘机理；脉冲供电；流场测试；五孔球形探针
Experimented Study of the Flow Field Distribution inside CIESP
Abstract
In this paper, many literatures on electrostatic precipitation and cyclone technology were consulted in an all-round way, and the flow field distribution inside a straight-tube cyclone impulse electrostatic precipitator (CIESP) was measured on condition of impulse voltage. Finally, the law of the three-dimension flow field distribution and the effects of entry velocity and impulse voltage were found under different conditions. To further study the law of the whole flow field distribution and dust removal mechanism of CIESP and optimize parameters of the structure, some suggestions were also put forward here. Conclusions based on the tested results can be summarized as follows:
<1> A CIESP is equivalent to an ordinary cyclone with a central discharge wire in the tube body at 0 Kv voltage. The tangential velocity and radial velocity inside air flow are reduced after increasing on the whole in the direction along the tube body wall, and the distribution of the axial velocity is in complete confusion. Besides, a small part of radial current along the tube body wall is found on the centre of the whirlpool as an increase in entry velocity .
<2> On condition of impulse voltage 45 Kv, an increase in entry velocity is found to boost the tangential velocity, and the whole change of the axial velocity is more gentle and demonstrates certain regularity, and the distribution curve of the redial velocity is also found like to be horizontal line.
<3> Under the circumstances that the entry velocity is 8.5m/s, the higher impulse corona voltage is, the smaller the corresponding tangential velocity is, and the larger the axial velocity is, but the change of the radial velocity is not obvious. With the increase of the radius, the tangential velocity is reduced progressively and basically, and the axial velocity increases progressively after reducing first, but the distribution curve of radial velocity becomes more steady.
<4> Compared with ordinary cyclone, the law of the flow field distribution inside CIESP is improved to some extent, which benefits dust removal. This may be due to the effects made by corona wire and electric wind, which reduce the turbulance degree of the flow field inside CIESP. But investigations must be further carried through all kinds of experiments to verify this hypothesis.
Keywords: cyclone impulse electrostatic precipitator;
dust removal mechanism; impulse power supply;
flow field measurement; five-hole probe
