煤粉炉中痕量元素迁移影响因素的研究

A Study on the Influencing Factors of Migration of Trace Elements in a Pulverized Coal-fired Boiler

采用Z - 82 0 0型原子吸收分光光度计和VF - 32 0型X射线荧光光谱仪 ,定量测定了 1台 2 2 0t/h煤粉炉中原煤、底渣、飞灰中 8种痕量元素的含量。基于改进的Meij相对富集系数 ,从底渣和飞灰两个方面 ,系统分析了温度、含氧量、飞灰粒径、痕量元素自身性质以及煤种特性对迁移规律的影响。研究结果表明 :炉膛温度升高能加快部分痕量元素的挥发 ;Cr和Mn在飞灰、底渣中含量相当 ,但两者相对富集系数明显不同 ;含氧量低并非促进所有痕量元素挥发 ;Pb、Cd、Zn、Cr在底渣和飞灰中含量并不一定都与各自的沸点成单一的关系 ;飞灰粒径越小 ,痕量元素富集系数越大 ,各痕量元素随飞灰粒径减小的变化趋势并不相同等。

By using a Z-8200 atomic absorption spectrophotometer and a VF-320 X-ray fluorescent spectrograph the content of nine trace elements in raw coal, bottom slag and fly ash was measured quantitatively in a 220 t/h pulverized coal-fired boiler. On the basis of an improved relative enrichment factor of Meij and from the perspective of two aspects, namely, bottom slag and fly ash, a systematic analysis was performed of the influence of various factors on the law of migration. Such factors include: temperature, oxygen content, fly ash diameter, the properties of trace elements per se and the characteristics of coal rank. The results of the analysis indicate that an rise in furnace temperature can quicken the volatilization of some of the trace elements. The content of Cr and Mn in fly ash and bottom slag is comparable, but the two elements differ markedly in respect of relative enrichment factor. Low oxygen content does not always promote the volatilization of all trace elements. The content of Pb, Cd, Zn and Cr in the bottom slag and fly ash does not assume a linear relationship with their respective boiling points. The smaller the diameter of the fly ash, the greater the enrichment factor of the trace elements. The tendency of variation of various trace elements with the decrease in fly ash diameter has been found to be not identical for different trace elements.