滤饼过滤过程的计算机模拟程序设计

详细介绍了滤饼过滤过程中各物理量的计算公式、计算机模拟程序的设计 ,为滤饼过滤过程的研究提供了一种新的研究方法     

空气过滤形成滤饼的模拟研究

提出了一个新的模型,用于预测空气过滤中捕集效率和滤饼层空隙率。模型中粒子的产生符合正态分布,其落点符合随机均匀分布。模型预测的捕集效率随粒径和孔径比的增大而增大,滤饼层空隙率随粒径和孔径比的增大而减小。粒子的分散度对滤饼结构的影响较小。     

纤维过滤滤饼孔隙率计算机模拟

基于受限扩散模型,建立纤维介质表面粉尘颗粒沉积形成滤饼的模拟模型。粉尘颗粒在远离过滤介质的控制面上释放,假设对流扩散运动为颗粒输送和沉积的主要机理。定义Pe数为颗粒对流作用与扩散运动的比值,讨论不同Pe数对滤饼孔隙率的影响。对Pe数范围为0.25~1600进行模拟计算结果表明,Pe数对滤饼的孔隙率影响显著。当颗粒的扩散运动强于对流运动,颗粒沉积形成的滤饼为较为松散的结构,当Pe数较大时,颗粒沉积形成的滤饼为较为紧密的堆积结构。此外,考虑到实际过滤过程中粉尘颗粒大多为非等径粒子,也对多分散粒子对滤饼形成及孔隙率的影响作了分析。     

恒压过滤滤饼孔隙率分布

在解过滤偏微分方程的基础上导出了滤饼孔隙率分布，对影响孔隙率分布的因素进行了讨论，指出恒压过滤时滤饼孔隙率分布不仅与物料的可压缩性有关，还与料浆浓度及操作条件有关，孔隙率分布的实测结果与理论预测值吻合较好。     

过滤介质滤饼可剥落性研究

本文通过实验研究，考察了滤饼的颗粒性质、饱和度、厚度、操作压差、滤布性质等因素对这过滤介质卸饼性能的影响，提出了评定过滤介质滤饼可剥落性实验方法的建议。     

滤饼过滤理论与实践:过去、现在和未来

本文综了当前滤饼过滤理论的发展过程,包括Ｒｕｔｈ＆Ｃａｒｍａｎ的早期工作。Ｔｉｌｅｒ－Ｓｈｉｒａｔｏ过滤方程以及日前一些行之有效的理论观点,着重强调了滤饼沉积过程中逐层分析的概念及相关的计算方法,同时对这些理论运用于实践中的可行性进行了评述。     

离心过滤中滤饼含液量影响因素的研究

本文对离心过滤中影响滤饼含液量的主要因素进行分析。选择细粒级的五种物料，在三足式过滤离心机上做脱液实验，获得的脱水和动力学试验数据，经因次分析，计算机处理，得到实验条件下滤饼含液量Ｗｔ的准数方程：研究结果表明：影响滤饼含液量的因素，首先是物料的物理性质：固体密度ρｓ，颗粒表面积体积平均粒径ｄｓｖ和悬浮液粘度μｓｕｓｐ；其次是操作参数：转鼓角速度ω，脱液时间ｔ和滤饼厚度ｈ。实验条件：Ｆｒ＝１０４８～１５１０，ｄｓｖ＝１．２９～２４．８μｍ，μｓｕｓｐ＝１～１０ｍＰａ·ｓ     

滤饼孔隙率的模拟研究

采用计算机模拟方法,对滤饼中颗粒的凝聚机理进行简化,将所过滤的物料外形形态简化为球形颗粒,进行计算机程序设计,模拟物料在纤维过滤介质中过滤形成滤饼的过程,模拟得出滤饼结构,并进行孔隙率计算,在简化模型的基础上,分析滤饼孔隙率,滤饼厚度以及固体颗粒粒径的相关关系,探索滤饼结构研究的新方法及新途径。     

计算机模拟醋酸纤维纺丝液的过滤过程

通过恒压过滤理论与高分子浓溶液的粘度特性对醋酸纤维纺丝液的过滤过程做了理论推导,通过计算机对纺丝液固含量、过滤温度、过滤压力等工艺参数对纺丝液过滤过程的影响做了模拟和分析。结果表明：纺鳇液圃含量升高后体系粘度会增加,同时过滤速率明显降低;升高过滤温度后纺丝液粘度有所下降,过滤速率将增大;纺丝液的过滤常数会随压差的升高而增大,过滤速率也随之所提高。     

气压过滤的成饼动力学及其滤饼的分形结构

用自制的实验室型气压过滤机并结合滤饼内部结构的测试,研究了气压过滤的成饼动力学及其滤饼结构的分形特征。结果表明,气压过滤条件下,虽然过滤压差较大,但成饼阶段仍遵循Darcy定律;气压过滤的滤饼结构为一分段Sierpinski分形,其分维数值介于1.775～1.885之间。     

Parameter Estimation for Incompressible Cake Filtration: Advantages of a Modified Fitting Method

There is a widely used linear strategy to determine the parameters specific cake resistance and filter medium resistance in incompressible cake filtration. In this article, it is intended to demonstrate that this strategy has some disadvantages and should be replaced by an alternative nonlinear approach which yields more exact results. Even though the gains in precision are small for most cases, the nonlinear strategy is favored because it involves no extra effort and is grounded in the same physical theory as the original approach. This claim is based on a broad simulation study using noisy data with known parameter values to compare both fitting strategies and judge their accuracies.     

Decreasing Filter Cake Resistance by Using Packing Structures

Packed beds used in absorption columns are evaluated to determine whether they can also be beneficial for cake‐forming filtrations. To assess this, model systems are characterized and separated by using a dead‐end filter cell. Filtrations are conducted with different packings; the filtrate amount over time and resulting turbidity are evaluated. Packings increase the filter cake resistance and the separation time of the cakes formed with approximately incompressible solids. However, they exhibit a positive effect on the filtration of a more complex, compressible substance; the process is not only accelerated, but also the quality of the obtained filtrate is not compromised. These results demonstrate potential in the use of packed beds for the filtration of complex biogenic suspensions.     

Simultaneous Granulation and Drying of Filter Cake

There are normally two possible routes for converting a wet cake obtained from a filter or centrifuge into a granular end product: drying followed by mechanical compaction; wet granulation followed by drying. A third way, simultaneous granulation and drying, has been investigated and has been in use now for several years for the production of a granular end product. It has the following advantages over wet granulation followed by drying: the process is able to accommodate a wide range of moisture contents and the bulk density of the end product is higher. The advantages over drying followed by mechanical compaction are the need for only one process step and the superior shape of the particles (more spherical, less sensitive to attrition).     

成饼过滤中过滤介质阻力与堵塞研究的进展

过滤介质是过滤作业的基本部件,由于在过程中不断地被堵塞,介质阻力不断增加,过滤性能逐渐下降,以致于不能再继续使用。因此研究其被堵塞的机理和降低、减少堵塞的措施就成为改善过滤作业的重要课题。综合了26篇有关文献,介绍了成饼过滤介质堵塞的机理、被堵塞过滤介质阻力的大小、影响过滤介质堵塞的主要因素等几方面的近期研究进展。