覆尘滤袋综合渗透率的分形求解

doi:10.12034/j.issn.1009-606X.218340

摘要/Abstract

摘要： 基于分形理论计算滤袋及滤饼构成的综合渗透率，描述其渗流特性。结合滤饼扫描电镜实验与图像处理技术分析滤饼孔隙结构；利用改进的毛细管模型近似模拟滤饼孔隙通道，根据流体动力学原理得到了滤饼渗透率的分形表达式，并由达西定律计算得覆尘滤袋综合渗透率，并用其对袋式除尘器流场压力分布进行数值模拟。结果表明，滤饼孔隙结构具有自相似特点。覆尘滤袋综合渗透率为(1.615~4.784)×10?12 m2，模拟所得的滤袋内外压差与实验结果的相对误差小于26%。覆尘滤袋综合渗透率计算方法合理，可较好地描述复合多孔介质的渗流特性。

关键词: 分形理论, 袋式除尘器, 滤饼, 渗透率, 数值模拟

Abstract: Composite porous medium was formed of filter bag and filter cake in filtration, in order to accurately obtain the permeability of the composite porous medium and make the permeability boundary conditions in the numerical simulation study fit the actual working conditions, comprehensive permeability of the dust filter bag was introduced to describe the seepage characteristics of the filter bag and the filter cake composite porous medium, and a method was proposed for calculating the comprehensive permeability of composite porous media based on fractal theory and Darcy's law. The filter cake was sampled by the bag filter comprehensive experimental platform, and the SEM images of the filter cake sample were obtained by electron microscopy. The improved capillary model was used to approximate the filter pore channel, and the fractal of the filter cake permeability factor G, the pore area fractal dimension Df and the curved fractal dimension DT were established on the fractal theory. The comprehensive permeability of the dust filter bag was calculated by Darcy's law. The numerical simulation of the flow field pressure distribution of the bag filter was carried out by using the comprehensive permeability of the dust filter bag. The results showed that the filter cake structure had self-similar characteristics, and the fractal theory was used to study the permeability of such loose and fragile porous media. The comprehensive permeability of the dust filter bag calculated in the paper was between 1.615×10?12 and 4.784×10?12 m2 far less than the permeability of the clean filter bag 16.880×10?12 m2. The relative error between the internal and external pressure difference of the filter bag and the experimental result was less than 26%. The calculation method of the comprehensive permeability of the dust filter bag was reasonable, which can better describe the seepage characteristics of the filter bag and the filter cake composite porous medium, and had strong applicability in engineering technology research.

Key words: fractal theory, bag filter, filter cake, permeability, numerical simulation

蔡卫东谭志洪熊桂龙刘丽冰魏林生. 覆尘滤袋综合渗透率的分形求解[J]. 过程工程学报, 2019, 19(5): 997-1005.

Weidong CAI Zhihong TAN Guilong XIONG Libing LIU Linsheng WEI. Fractal solution of comprehensive permeability of dust-covered filter bag[J]. Chin. J. Process Eng., 2019, 19(5): 997-1005.

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