Abstract: Secondary air of air classifier has important effects on the classification performances of air classifier. This paper investigated the impacts of secondary air flow change to same material, particles of different sizes and particles of same size, different material classification effect, and proposed a classifying evaluating index—the relative classification precision δ, which could be obtained directly from coarse and fine streams size distribution, to evaluate the quality of classifying effects. The experimental results showed that relative classification precision for particles in fly ash and cement clinker. For the same sized particles, in the case of the same secondary air, the relative classification precision of fly ash with smaller particle diameter was greater than that with larger particle diameter, and the relative classification precision of cement clinker with smaller particle diameter was greater than that with larger particle diameter. For the same sized particles, under the condition of the same secondary air, the relative classification precision of fly ash with smaller proportion was larger than that with larger proportion. Optimum classification performance was obtained under the condition of 150m³/h of secondary air flow and the ratio of 0.168 to main flow air rate, using LNJ-36A air classifier to classify fly ash and cement clinker.

Key words: air classifier, secondary air, relative classification precision, classification performance

摘要： 气流分级机二次风量是影响分级机性能的重要因素。通过实验探究二次风量变化对同种物料、不同粒度段及同种粒度段、不同物料分级效果的影响,并提出一种可以直接从粗、细粉粒度分布中得到的分级评价指标——相对分级精度δ,以此来评价分级效果好坏。实验结果表明,不同粒度段的粉煤灰和水泥熟料在相同二次风量的情况下,粒径较小的粉煤灰,其相对分级精度大于粒径较大的粉煤灰;粒径较小的水泥熟料,其相对分级精度大于粒径较大的水泥熟料;同种粒度段的粉煤灰和水泥熟料,在相同二次风量的情况下,相对密度较小的粉煤灰,其相对分级精度大于密度较大的水泥熟料;利用LNJ-36A气流分级机分级粉煤灰和水泥熟料,二次风流量保持在150m³/h、与主气流流量比例保持在0.168时,分级效果最好。

关键词: 气流分级机, 二次风量, 相对分级精度, 分级性能