| Power plant generates electricity by burning coal mostly at the present time, and more and more fly ash was produced,environment problem was induced To reduce the pollution caused by the large number of that piled up, to reduce the waste of resources which contained in that and its comprehensive utilization has been also attracting more and more attention, we have studied on technology of rotary triboelectrostatic separator for fly ash decarbon. Rotary triboelectrostatic separator can be used to separate mineral particles which size are less than 74 μm with different properties,unburned carbon particles and ash particles scrubed with the scruber and each other,so different polarity charges can be charged inspectively, and separation can be realized in electrostatic field.It has the advantage of dry cleaning,simply operating,and no cost of huge waste water handle system and dehydrate system,and it is attracting more and more attention.This thesis gives a review of the theoretical basis of electrostatic separation and electric separation technology of fly ash; besides the basic physical and chemical properties of fly ash sample and the washability of electrostatic separation for its different particle size fraction are also measured. What’s more, the seven factors such as feed rate, friction wheel speed,in-flow velocity, co-flow velocity which may have some impact on the effect of triboelectrostatic beneficiation are also tested. After that the orthogonal optimization test are experimentized, and the optimal trial condition are obtained.Studying on electric character of unburned carban and ash improved : the small the particle,the big the resistivity, the little the dielectric constant, the little the electron circumfluence, and the bigger the triboelectrification charge-to-mass,so we can realize separation easily;whereas, it can produced worse effect. The single factor exploratory experiment shows charging voltage has no significant effect on the fly ash cleaning, feed rate is relatively obvious, and the remaining five factors, including in-flow velocity, roller rotation speed, co-flow velocity, electrode voltage and width of collecting chambers, have obvious effects, the optimum level for each factor as follows: 0KV, 1.38g/s, 2m/s, 4400r/min, 3m/s,-35 KV,(1, 2, 3 cm). The optimization experiment points out that the efficiency index of benefication of fly ash, yield and loss-on-ignition of products that moved toward negative electrode are appropriate to adopt the quadratic model to fit, besides the significance of the same factor in the models for different response values are also somewhat different but the factor, width of collecting chambers, is always the most significant. The optimum condition as follows(from A to E): 1.2 m/s, 5050 r/min, 2.0 m/s,-35 KV,(1, 2, 3 cm). |
