【作者】 李阳；

【导师】 付海明；

【作者基本信息】 东华大学 ， 热能工程， 2008， 硕士

【摘要】 在现代工业生产中常产生含尘气体其中大部分是高温含尘气体。这些气体的直接排放不仅会造成环境的严重污染,而且还会对人体健康构成严重的威胁,因此必须在排放前进行处理。颗粒层除尘技术采用具有耐高温、耐磨、耐腐蚀的固体颗粒进行除尘,被认为是最具发展前途的高温除尘技术之一。颗粒层过滤器特点是具有良好的耐高温和耐高压性能,过滤介质不存在腐蚀问题,对气体和灰尘性质不敏感,过滤效率较高。它存在的问题是过滤风速不能太高,在处理相同烟气量时阻力大,过滤面积也比袋式除尘器大,其对细微尘粒的除尘效率不高。国内外对颗粒层过滤除尘技术的研究均处于试验阶段,其系统的理论研究和运行实践尚存在不足。针对以上问题,本文首先搭建固定床颗粒层过滤除尘性能测试实验台,在常温条件下从实验上分析各因素单独变化时过滤效率的变化趋势。在此基础上,采用正交实验设计方法对含尘过滤条件下进行了过滤效率和过滤压降的实验研究。分析实验数据,利用公式拟合和回归的方法得出颗粒过滤层的过滤效率和压力降与过滤速度、过滤时间、颗粒层滤料平均粒径、含尘气体浓度和颗粒层厚度之间的无量纲多元关联式。并与实验数据、理论公式计算值进行比较,结果证明在本实验条件范围内,该回归式可以用来对过滤效率进行预测,为过滤层性能优化选择提供参考。对含尘过滤效率进行理论推导:以经典过滤理论为基础,结合含尘滤料过滤阶段自身特点,建立数学模型,推导得出一套含尘颗粒层过滤效率计算式。该公式与经典过滤效率公式对比,发现都和实验测量值误差较大,需进一步改进。为了优化颗粒层过滤器内部流场,利用目前较流行的CFD模拟软件FLUENT,通过DPM离散相模型进行数值模拟来讨论颗粒层过滤效率及总成压降与其结构参数、过滤特性参数的相关关系。在模拟结果与实验测量值相吻合的基础上,提出优化颗粒层内部流场的方法。最后引用颗粒层过滤总成的渗透率和压降的联合关系式作为其综合性能评价指标,使指标值最高即代表过滤性能最佳。用MATLAB优化工具包对指标表达式进行优化计算,得出指标值最高时对应的过滤系统各参数的最优值。本文的研究结果,尤其是回归的无量纲的多元关联式可以给颗粒层过滤器的设计者提供数据参考,减少重复性劳动。另外,本文探讨的模拟方法可以在过滤器的设计研究中使用,用模拟来简化部分实验环节,从而可以节省大量的人力和物力,提出进一步优化颗粒层过滤技术的方案。更多还原

【Abstract】 In the field of industry production, it always makes waste gas that most is high temperature. If these waste gases that contain dust are direct emitted into environment, it will be harmful for human being and make environment pollution. So it must be disposed by dust remover. The granular bed filtration using the materials which are wearable, acid-resistant and high temperature- resistant is considered as the most promising developmental technique.The characteristic of granular bed filter are wearable, geostatic and high temperature- resistant, its filtrate granule will not be eroded and sensitive to gas and dust. But there are some problem for the filter such as low filtration velocity, high resistance in same dust-gas quantity, more area than bag filter and low filtration efficiency to imperceptibility granule.Internal and overseas, the research for granular bed filtration is in experiment phase now. Its systemic theoretical research is also incomplete. In order to resolve these problems mentioned above, firstly the author set up the testing set of fixed granular bed filter. Then the experiment has been done under normal temperature. From the result the author analyzed the change law of filtration efficiency and pressure drop when each factor which effects filtration efficiency changed solely. In the base of this, the author using orthogonal test to experiment the filtration efficiency and pressure drop. Analyzing the experiment result, a dimensionless efficiency and pressure drop model of filtration velocity, granular bed thickness, fill ratio, granular diameter of filter bed, gas thickness and bed thickness has been obtained by multianalysis and regression method. After comparing this formula with the test data and theoretical calculation, the author draws a conclusion that this formula could be used to predict the filtration efficiency in this experiment condition. At last the author made a theoretical derivation of filtration efficiency under non-stationary condition. Based on classical filtration theory, according the characteristic of non-stationary filtration the author set up the mathematical model and obtained an efficiency formula through deduction. Compared with experiment result, the improvement of the formula should be done in future.To optimizing the inner fluid-field of granular bed filter, this thesis makes use of CFD (FLUENT numerical simulation method) numerical simulation technology, through DPM model to discuss the correlativity between filtration efficiency, the pressure drop and their each structural parameter, granular bed characteristic parameter. On the basis of the simulation conforming to the experiment result, the suggestion to optimizing the inner fluid-field of granular bed is brought forward. Associated relationship model of infiltration rate and pressure drop is advanced to be a general optimization estimate target, the higher that is, the better performance the granular bed filtration has. Optimal parameter values are obtained by adopting the optimization toolbox of MATLAB 6.5.The conclusion of this thesis, especially the dimensionless multiple-factor regression equations can offer instruction to the designers to reduce the repetitious work and enhance the performance of research. The numerical simulation method discussed in this thesis can be used in the design and research of filters, which partly replaces the experiments, largely saves the manpower and material resources, and optimizes the evaluation of bag filter’s performance更多还原