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

在本研究中，我们开发了计算机控制扫描电子显微镜（CCSEM）测量污泥焦炭的技术。成功地采集了炭中无机颗粒的组成与粒度之间的数据。根据这个结果，我们有可能获得一个样品几千个水平的信息。在这个项目期间研究了以下内容。1)粒度分布验证及EDS分析2)污泥燃烧实验及污泥及其chard的CCSEM分析发现，SEM图像的亮度分布影响粒度分布及化学成分分析的精度。通过数据的存储，可以找到亮度分布的最佳值。对某污泥进行了停留时间0.8秒、氧气浓度7%、燃烧温度900 ~ 1500℃条件下的燃烧实验。在燃烧温度1300℃以上，煤焦颗粒中所含矿物在燃烧过程中发生凝聚、结合、熔融。结果表明，矿物粒度分布随温度的升高而增大。用CCSEM和ICP分析了矿物颗粒的化学成分。锌、磷等元素从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、石英、钙矾石和磷灰石等固溶相。

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.