Development of CCSEM analysis system and study on the fly ash formation during sludge combustion in an incinerator

本研究发展了计算机控制的扫描电子显微镜（CCSEM）污泥半焦测量技术。成功地采集了煤焦中无机颗粒的组成与粒径之间的数据。因此，我们可以获得一个样本的数千个级别的信息。本课题主要研究了以下几个方面的内容：1）颗粒粒径分布的验证和EDS分析2）污泥燃烧实验和CCSEM分析污泥及其特性研究发现，SEM图像的亮度分布影响颗粒粒径分布和化学成分分析的精度。在停留时间为0.8s、氧气浓度为7%、燃烧温度为900 ~ 1500 ℃的条件下，对污泥进行了燃烧实验。结果表明，矿物粒度分布随温度升高而增大。用CCSEM和ICP分析了矿物颗粒的化学组成。Zn、P等元素从1300℃开始挥发。熔融矿物中存在Si-Al-Ca-Fe-P-Mg-O和Si-Al-Ca-Fe-P-Zn-O等固溶体相、石英、CaAl-方解石和磷灰石。

In this study, we developed the technique for sludge char measurement of computer-controlled scanning electron microscope (CCSEM). The data between composition and particle size of inorganic particles in a char was collected successfully. As this result, it would be possible that we obtained the information of several thousand levels for one sample. The following was studied during the period of this project.1)Verification of the particle size distribution and the EDS analysis2)Combustion experiment of the sludge and CCSEM analysis of sludge and its charIt was found that the luminance distribution of the SEM image affected particle size distribution and precision of chemical composition analysis. By the storage of the data, it was possible to find the optimum value of luminance distribution.Combustion experiment of a sludge was carried out at residence time 0.8 seconds, 7% oxygen concentration and the combustion temperatures of 900〜1500℃ Above the combustion temperature of 1300℃ the minerals which were included in a char particle cohered, combined and then melted during combustion. As the result, mineral particle size distribution increased with the temperature. Chemical composition of the mineral particles was analyzed by CCSEM and ICP. The elements such as Zn and P were volatilized from 1300℃. The solid solution phase such as Si-Al-Ca-Fe-P-Mg-O and Si-Al-Ca-Fe-P-Zn-O,quartz,CaAl-Sdicate, and apatite were identified in the molten minerals.