污泥裂解过程的形貌学特征参数研究

Research on morphological characteristics of sewage sludge during its pyrolysis process

污泥裂解过程对应的特殊形貌学特征能够反映污泥裂解进行程度,通过全程拍摄处于400℃下的污泥裂解反应进程,得到反应不同阶段的图像序列,对该图像序列借助Image Pro Plus v6.3软件进行数字化处理,可以得到描述图像特征的量化值。通过对比各种形貌特征值后发现,污泥裂解过程中,被关注的区域主体面积(用像素表示)和光密度值呈现规律性变化。随污泥裂解进行,关注的区域主体面积从最初的52 000像素降至最终的35 000像素,污泥图像的基本色红绿蓝(RGB)三通道光密度值从最初的160～180降至最终的70,两者的变化规律与污泥的裂解过程密切相关,并且光密度值能够更加准确地表征污泥裂解进程。通过实验数据拟合,验证了平均光密度和裂解失重率呈线性关系,并且在特定条件下和反应时间的关系满足DoseResp函数,为实现污泥裂解自动化控制提供基础。

In this research sewage sludge was taken photographs frequently with a high speed inirared camera during its whole pyrolysis process which took place at 400℃ to identify its photographic characteristics. Digital image processing was performed with help of software Image Pro Plus （v6.3） to obtain the quantitative parameters describing morphological characteristics of these photographs; and then the correlations between these morphological parameters and the pyrolysis steps were investigated. It was found that the main area of sewage sludge photographs under investigation and the optical densities of R （red） , G （green） and B （blue） of these photographs regularly changed with its pyrolysis process and they were the two target parameters. The concerned area of photographs under investigation reduced from 52 000 pixel to 35 000 pixel from the beginning of the sewage sludge pyrolysis to the end; while the optical densities reduced from 160 -180 to 70 in the same process with an obvious linear relationship to the mass loss during this process. The optical density was proved to be the more accurate parameter to describe the pyrolysis process also by the fact that the curve of averaged optical density of RGB with reaction time well satisfied DoseResp function under the investigation conditions. All of these results cast a light suggesting that image analysis provides an innovative method for sewage sludge pyrolysis characterization and could be potentially used for the process control.