| Nowadays, it is really serious and inconvenient to the environment and the lives because of fine particles (PM2.5) caused by coal combustion. The problems of haze caused by fine particles should be solved in urgent. It is ineffective to deal with fine particles for traditional dust removal equipment, mounts of it are emitted into the atmosphere, being a huge burden to the environment. Threaten caused by fine particles need to be controlled to get the standard being ruled in new standard of pollutions emission of China. If they grow up into the area which can be removed away by dust removal equipment, there is no need to replace traditional dust removal equipment, agglomeration of fine particles can make the size big enough to be removed by traditional dust removal equipment, which will increase the separation efficiency of fine particles.The technology on condensation and agglomeration of PM2.5 and PM10 is summarized and concluded. Based on previous studies, a method of fine particles agglomeration enhanced by combined effect of humidifying and charging is presented in this thesis. This method can make sure removal of fine particles in effective. Studying the theory and getting the result of test, analyzing the characteristics of gas-solid, gas-liquid flow in different conditions.Firstly, according to the requirements to design and build experiment platform on combining effect of humidifying and charging. Achieving stable conditions, particles charged experiment, humidifying environment experiment and combined effect of humidifying and charging experiment. Changing regular of particle size and characteristics of distribution were analyzed.Secondly, Experiments are done in different conditions, as follows: (1) Particles were charged in the direct-current electric field. In order to improve the agglomerate efficiency and economic effectiveness, particles charged by negative electric field and particles uncharged were mixed. The relation between charging parameters and particle distribution and agglomeration efficiency were summarized. (2) Fine particles in simulation were speared in humidifying environment, got results on changing trend of particles distribution and agglomeration efficiency through experiment. (3) In experiment of combined effect of humidifying and charging, the relation between charging parameters and particles distribution and agglomeration efficiency were analyzed.Finally, combined with theory and data, the fine particles number concentration, removal efficiency in different grades and total removal efficiency can explain the availability and effectiveness. The experimental results show that: In the conditions of pure electric field,number concentration of particles reduce when charged voltage reduce, the total removal efficiency of particles can reach 50%; In the conditions of combined effect of humidifying and charging, the total removal efficiency of particles can reach 65%.The fine particles in the size from 0.260 to 2.385 ?m effect greater than other. The combined effect is increased 40%than the effect of electric field and improves 45% than in humidifying condition. It proved that the experiment increase the size of the particles, and reduce the number concentration of it. The present study indicates that combined effect of humidifying and charging is a highly efficient process for separating fine particles. |
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