气流床煤气化水系统中絮凝物的絮凝及分形特性

Flocculation process and fractal character of the floc in water system of entrained bed coal gasification

以气流床煤气化细渣与超纯水配制的悬浊液为煤气化黑水的模拟水样,借助工业絮凝剂研究了细渣的絮凝过程。考察了絮凝剂添加量、水样p H值、絮凝时间、搅拌时间等条件对絮凝效果的影响规律。通过热台显微镜观测了悬浮物在水溶液中的絮凝过程,引入分形理论对絮凝物絮凝过程图像进行分析,结合悬浮物浓度测试,揭示分形维数变化所表征的絮凝效果。实验结果表明絮凝体分形维数与絮凝后悬浮物浓度呈现负相关性,即分形维数越大,絮凝后的悬浮物浓度越小;絮凝物的分形维数随絮凝时间增加先增大后减小;絮凝体分形维数和絮凝体球度、角度之间存在指数关系,且相关性较大,分形维数会随絮凝体的角度增加而增大;絮凝体分形维数指标可用于絮凝物絮凝过程的研究。

The simulated samples of coal gasification blackwater are made up of fine slags of entrained-bed coal gasifi-cation and the ultrapure water. The flocculation of the fine slags is investigated with certain industrial flocculants. Theeffects of the amount of flocculant,p H value of the samples,flocculanting time,and stirring time are studied. The ther-mo-stage microscope is used to observe the flocculation of fine slags in simulated samples. The fractal theory was intro-duced to analyze the flocs images of flocculation process. The results show that the fractal dimension of the floc and theconcentration of suspended solid flocculation negatively correlate,that is,the greater fractal demension,the smaller theconcentration of suspended solids after flocculation. The fractal dimension of the flocs with flocculation time increasesfirst and then decreases. There is the exponential relation for both the number of flocs fractal dimension and floc angle.The fractal dimensions of the floc increase with the increasing angle. Therefore fractal dimension of the flocs can beused for the study of flocculation.