低低温系统中粉尘颗粒团聚特性研究

Experimental study on agglomeration characteristics of ash particles in low-low temperature flue gas system

由于低低温条件下粉尘颗粒物的团聚效应,实际运行中低低温省煤器和电除尘器容易出现积灰堵塞问题。本文搭建固定床吸附实验台,研究了颗粒物吸附硫酸酸雾后的团聚现象,以及各因素对团聚的影响程度。结果表明:吸附反应后单个颗粒物存在4种表面形态,颗粒物间存在4种团聚形态;硫酸酸雾在颗粒物表面产生一层液膜,使颗粒物间黏附力增强,强化了团聚效果;初始阶段主要发生小颗粒在大颗粒表面的黏附以及小颗粒之间的凝并,随后发生大颗粒之间的团聚;温度降低会提升颗粒物团聚的效果,但提升程度与吸附时间有关;在低低温系统中,温度的小幅变动将会引起团聚效果很大的改变;随着颗粒物粒径的增大,颗粒物的团聚效果减弱,粒径增大至91μm以上时几乎不发生团聚。

Due to agglomeration of ash particles under low-low temperature conditions,ash deposition block occurs very easily in low-low temperature economizer and electrical static precipitator during actual operation.To deal with this issue,the authors built up a fixed-bed adsorption experimental bench and studied the agglomeration of particles adsorbed by sulfuric acid mist and the influence of various factors on the agglomeration.The results show that,there are four kinds of surface morphology of the individual particle and four kinds of agglomeration morphology between the particles.A layer of acid liquid film is formed on the particles'surface,which enhances the adhesion between particles and strengthens the agglomeration effect.In the initial stage,the small particles adhere onto the surface of large particles or the agglomeration between small particles occurs,followed by the agglomeration between large particles.The drop of adsorption temperature improves the agglomeration,but the improvement degree depends on the adsorption time.In the low-low temperature flue gas system,small variations in temperature will cause significant change of the agglomeration.The agglomeration effect decreases with the increasing particle size,and almost no agglomeration occurrs when the particle size increases to above 91μm.