【作者】 付海明；

【导师】 沈恒根；

【作者基本信息】 东华大学 ， 机械设计及理论， 2006， 博士

【摘要】 过滤净化是环境科学领域存在的较为重要的问题，对粉尘进行过滤净化存在着过滤介质随捕集粉尘的沉积，过滤介质压力损失及能耗随过滤时间剧烈增加，过滤介质需经常清灰及更换等问题，提高粉尘捕集效率、优化过滤运行过程、降低过滤运行成本，减少能耗，研发高效、低阻、易清灰的新型过滤介质是多年来众多学者及科研工作者的追求目标。为此，本课题围绕粉尘过滤净化问题，开展研究，研究重点为减少工业粉尘过滤压力损失及优化选择过滤材料等问题。本课题研究对如何进行优化过滤运行及优化选择和设计过滤介质等问题进行了理论、实验及模拟研究。本课题主要研究内容及研究结果包括：(1)考虑了粉尘颗粒在过滤介质中的沉积，根据质量守恒定律，建立了粉尘浓度在纤维过滤介质分布的数学模型，分别在单纤维捕集系数固定不变及随粉尘沉积质量变化两种情况下，对粉尘浓度分布数学模型进行了理论求解，得出了非稳态捕集效率的理论计算公式，传统过滤理论捕集效率计算公式为本模型理论的特例，通过相关实验研究分析，证明了本数学模型的两种理论求解结果，虽然在形式上有所不同，但计算结果基本一致。(2)通过对传统过滤效率理论计算公式中各影响因素进行分析计算，获得大量的数据，并对其进行回归统计分析，得出了捕集效率计算的经验模型，以便于预测及评价过滤介质的捕集效率，为计算多分散粉尘颗粒捕集总效率，提供了计算方法及途径。(3)建立非稳态压力损失的机理及经验模型，通过对国产纤维滤料的性能测试研究，对模型进行验证，为国产滤料应用于粉尘控制，积累了研究数据及资料。(4)在假设条件下，开发可视化粉尘颗粒物在纤维滤料中沉积的计算机仿真模拟程序，模拟粉尘沉积及过滤过程，研究滤料及粉尘颗粒物特性与过滤性能之间的相互关系，对模拟实验结果与实测结果进行对比，取得必要的修正及参数，便可利用计算机模拟研究替代实验进行过滤介质的优化选择及设计。(5)通过建立的计算机随机沉积模型，采用计算机进行大量的计算，研究不同粒径的颗粒物沉积与不同纤维直径及间距的互相关系等问题，为滤料结构的合理设计创立条件，为开发新型滤料提供理论依据。通过计算机模拟分析，得出了粉尘粒径、纤维直径及过滤介质填充率与捕集效率和压力损失的相关关系，提出梯度滤料具有较好的过滤特性的滤料设计思想。(6)对计算机模拟形成的粉尘层，引入分形理论，研究单分散和多分散粉尘颗粒群的几何特征，用分形维数这一简单的数值，表征复杂的粉尘颗粒物沉积群的形态，研究粉尘层的孔隙率与其粒径及分形维数的关系，探讨粉尘分维数在粉尘控制技术中应用的可行性及应用途经。(7)将新的滤料设计思想应用于新型滤料研发中，研制出具有高效、低阻及易清灰特性的梯度滤料，其压力损失低于覆膜滤料。并将其应用于电厂过滤除尘系统中，解决了过滤运行中能耗过大的问题，为袋式过滤除尘器应用于电厂除尘中积累了经验。更多还原

【Abstract】 Particles deposit continuously on the surface of filter or inside filter media during dust filtration process and may cause filter clogging if they are not removed timely. The pressure drop of filtration and energy consumption would increase or even the filtration process can not conduct if the filter media are completely clogged. The properties of filter media and operation paramers are very important to the dust removal.The objectives of this study were: 1) to find way to enhance dust particles collection efficiency of filter media, 2) to optimize filtration process parameters to reduce pressure drop of filtration and 3) to develop new filter media. To achieve these goals, theoretical calculations, experimental examinations and simulation were carried out. The main research work and findings are as follows:(1) A mathematic model describing dust concentration change with time and space was established, based on the law of mass conservation in a bag house. The general theoretical solutions of collection efficiency were obtained on the conditions of steady or non-steady filtration processes. It is found that the logarithm formula was only a specific solution of the mathematical equation. Experimental results of this work were in agreement with the theoretical calculations.(2) The factors affecting filtration were examined and a statistical model to predict collection efficiency of filter was put forward, which is a useful tool for calculation of overall removal efficiency of dust.(3) An empirical model and a theoretical model describing pressure drop of filtration on the conditions of steady or non-steady filtration processes have also been established in this work. Using experimental set-up of filtration performance measurement, we set up the filtration performance database of filter media made in China.(4) The visual simulation program of particle deposition on filtration media has been developed, which can be used to choose or design filter media for the interest of reducing laboratory work.(5) The correlations of dust collection capacity of fiber and fiber diameters as well as fiber intervals have been investigated by means of the visual simulation program. Based on the simulation results of collection efficiency and pressure drop of filtration for different particle diameters and fiber diameters, the novel gradient filter media were developed.(6) Using fractural theory, we studied the geometry characteristics of dust cake for single-disperse and multi- disperse dust particles. The fractural dimension can be used to describe complicated shape of dust cake. In addition, it can also be used to study the relationship of porosity and dust diameter. The fractural dimension could ne used to control filtration processes.(7) The novel gradient filtration media have been utilized in the dust removal of power plants burning coal successfully, showing better filtration performances (higher efficiency and lower pressure drop than traditional membrane-covered filter media).更多还原