烧结过程中碱金属脱除及在颗粒物中的富集行为

Behavior of alkali metal removal and enrichment in particles during sintering process

通过工业全流程采样分析烧结过程碱金属平衡,通过烧结杯实验研究K和Na的脱除行为及其影响因素,查明K和Na在不同粒径的颗粒物中的富集特性及赋存状态。研究结果表明:在烧结过程中,K和Na的脱除率分别为22.86%和8.70%,脱除的K和Na主要进入机头灰中,其次为机尾灰;燃料配比和碱度对碱金属脱除的影响最大,随着燃料配比和碱度提高,K和Na的脱除率增大,K和Na的脱除主要发生在料层中下部,烧结料层表层和底部的K和Na的脱除率低;K和Na随烟气进入颗粒物中,随着烟气颗粒物粒径减小,碱金属的质量分数和富集比增大,K和Na在第四电场灰中的富集比分别达279.86倍和43.17倍,在气溶胶颗粒中则分别达248.77倍和50.13倍;K和Na易与Cl元素汽化-凝结形成化合物,因而主要以氯化物存在于颗粒物中。

Alkali balance in sintering process was investigated through analyzing the samples collected from the wholeindustrial process. Sinter pot tests were conducted to study the removal behaviors of K, Na and relevant influencingfactors. The enrichment characteristics and occurrence states of K and Na in particles with different grain sizes wereanalyzed. The results show that the removal rates of K and Na are respectively 22.86% and 8.70% during the wholesintering process. Removed K and Na firstly go into the head ESP dust and then into the end ESP dust. Improving theratio of fuel and basicity can increase the removal rates of K and Na. Additionally, the removal rates of K and Na are lowin the upper layer and the lowest layer of the whole sintering bed, while the maximum removal rate is found in themiddle-lower layer. K and Na go into particles along with gas flue. The content and enrichment ratios of K and Na inparticles increase with the decrease of the particle size, and the enrichment ratios of K and Na reach 279.86 times and43.17 times in the fourth electric field ash, and 248.77 times and 50.13 times in aerosol particle compared with those inraw materials. K and Na mostly exist in the form of chlorides in particles because they may form compounds with Clelement by vaporization- condensation.