自激式除尘器液滴形成机制与微细化调控

At present, the removal efficiency of self-swash dust separator for fine dust is not too high. The droplet’s micronization is the efficient measure of improving the removal efficiency. However, present research mainly explains the interaction process of gas flow and liquid level for macro issues. The effects of fluctuation of gas-liquid two-phase on the droplet formation are ignored. So, it is difficult to guide the regulation and control for droplet’s micronization effectively. Therefore, this project presents the study idea of droplet formation process for studying the fluctuation features of apparent pressure. The dynamic process of droplet formation of self-swash dust separator would be studied, which would adopt the high speed dynamic image analysis technology and gas-liquid two phase flow pressure fluctuation theory. The droplet formation mechanism of self-swash dust separator based on the dynamical features of pressure fluctuation characteristic would be illuminated. Furthermore, the dynamic image would be the visual technological means to direct the regulation and control for droplet’s micronization. The method of regulation and control for droplet’s micronization would be innovated. In the end, the removal efficiency for fine dust of self-swash dust separator would be improved hopefully. The study contents of this project as follows: the pressure fluctuation characteristic of coupled between gas flow and liquid level; the dynamic process and dynamics of droplet’s detachment and its sledging; the physical and chemical effects of droplet formation mechanism on the condition of mining and metallurgy dust dissolved in the cleaning liquid; and the method innovation of the regulation and control for droplet’s micronization.

目前，自激式除尘器对微细粉尘的去除效率还不高，而液滴微细化是提高去除效率的有效手段，但现有研究主要从宏观上阐述自激式除尘器的气液作用过程，忽略了气液两相波动对液滴形成的影响，难以对液滴微细化调控起到有效指导。对此，本项目提出了从表观压力波动特性出发研究液滴形成过程的思路，采用高速动态影像分析技术及气液两相流压力波动理论，研究自激式除尘器液滴形成的动态过程，阐明以压力波动特性为动力学特征的自激式除尘器液滴形成机制；并将动态影像作为指导液滴微细化调控的直观技术手段，创新液滴微细化调控方法，以期提高自激式除尘器对微细粒度粉尘的去除效率。项目研究以下内容：气流与液面耦合的压力波动特性，液滴剥离与二次破碎动态过程及动力学，矿冶粉尘的溶入对液滴形成机制的物理化学影响，以及液滴微细化调控方法创新。

针对自激式除尘器气相压力波动引起除尘器捕集体（液滴、液面和液泡等）间歇性激发，造成除尘过程气液卷吸效果不佳，微细粉尘大量逃逸的现象，项目从捕集体微观角度出发，采用高速动态影像分析技术及气液两相流压力波动理论，对除尘器捕集体产生和演变的动态过程进行了研究。. 通过分析净化腔里气液两相耦合过程中压力变化所富含的丰富信号，挖掘出表征捕集体产生与演变动态过程的信号特征，建立起了以压力波动时序信号、概率密度函数、小波分析结果等为特征的自激式除尘器气液耦合模式的量化模型，阐明了以压力波动信号为特征的捕集体产生与演变的动力学机制。同时，通过对高速摄像仪的图像进行分析，印证了压力信号所表针的捕集体的动态特性，并更为直观的阐释了捕集体产生和动态演变过程中所体现出来的复杂时间和空间结构关系，从微观尺度阐明了由气相压力波动和液相复杂时空结构相耦合的捕集体形成机制。. 在以上理论指导下，项目以液面稳定性调节装置来改变液相的回流速度，进而稳定蓄液箱液面及节流口间隙，调节捕集体间歇性激发的频率，强化气流卷吸液相的耦合过程，使净化腔中形成的捕集体时空分布更为均匀，压缩了粉尘逃逸的通道。. 研究成果体现出较强的科学性和创新性，从气液两相流动的竞争协调特性出发，通过稳定液相的流动性协调了气液两相的耦合关系，解决了两种具有流动性流体间耦合的不稳定性问题，使不稳定耦合引起的捕集体间隙性激发得到调控，有效压缩了烟气中有害物质逃逸的可能时间和空间，突破了由气流冲击液面来产生捕集体为主要原理的净化装备对微细粉尘净化效率不高的技术瓶颈。. 研究成果已在矿冶、采掘、中草药等工业生产中得到试用，提升了自激式除尘设备的各项技术指标，液面波动范围控制在2-3cm，降低了70%-80%；捕集体激发频率提高2-3倍；强化了烧结厂和采石厂的烟气净化，使排放浓度小于最新国家标准（30mg/m3）；提升了中药厂微细药尘（<0.5μm）的净化效率约20%，达到60.3%，具有较好的应用前景。