金属多孔介质气固分离器流场数值模拟及结构优化

发布时间：2018-06-19 01:50

本文选题：金属多孔介质 + 过滤　；参考：《西安理工大学》2017年硕士论文

【摘要】：我国能源结构以火电为主,据统计全国在役火电厂平均每年产生1500万吨烟尘以上,因此发展性能优异、运行稳定的除尘设备势在必行。早期的火电厂烟气净化装置很大一部分是袋式除尘器,随着环保标准的提高及金属多孔滤棒制作技术的成熟,利用金属多孔介质过滤器替代袋式除尘器已成为一种趋势。本文以咸阳市某一现役燃煤电厂金属多孔介质除尘器原型为研究对象,针对过滤器内部气流组织不均匀、需要频繁更换滤棒以致设备稳定性大幅降低,而目前工业技术手段很难直接监测过滤器内部流场的问题,利用ANSYS FLUENT 15.0流体仿真软件模拟过滤器流场,找到过滤器出现上述不利因素的原因,并针对原型过滤器存在的气流组织问题,提出结构优化指标和四种优化方案,参考优化方案模拟结果指导工程实践。通过对金属多孔介质气固分离器原型内部气流组织模拟分析,在与实测数据对比验证模拟结果可靠性的基础上,得到以下结果:采用Porous Jump模型处理多孔介质滤棒结果真实可靠。过滤器内部流场的不均匀性导致过滤器滤棒流量分配系数变化较大,滤棒最大流量不均幅值ΔK高达1.47,综合流量不均幅值ΔK=0.131,其中边缘两列滤棒流量分配系数较大。流量分配系数的较大不均匀性在增大过滤器过滤压力的同时也增大了滤棒更换或清灰的频率,十分不利于设备的稳定运行。针对原型过滤器气流组织问题,对改变滤棒长度及进气口高度、滤棒数量及布局、进气口角度与数量以及设置不同滤棒渗透系数四种结构优化方案进行模拟计算,结果表明:四种优化方案的“最佳结构”分别为:滤棒长度L=0.72m,进气口高度T=0.288m;去掉第一、二列滤棒;设置双进气口,呈90零+270零分布;降低第4～8列、第4～6排滤棒渗透系数到7×10-13m2。以上四种方案中“最佳结构”对气流均匀性相关参数—最大流量不均幅值、综合流量不均幅值、气流均匀性指标均有较好优化效果。以最大流量不均幅值ΔK为例,上述四种方案中的“最佳结构”分别较“原型”降低63.27%、17%、51.11%、9.09%。
[Abstract]:The energy structure of our country is dominated by thermal power. According to statistics, the national thermal power plants produce more than 15 million tons of smoke and dust every year, so it is imperative to develop excellent performance and stable operation of dust removal equipment. With the improvement of environmental protection standards and the maturation of metal porous filter rod making technology, it has become a trend to replace bag filter with metal porous medium filter. In this paper, the prototype of metal porous media precipitator in an active coal-fired power plant in Xianyang city is studied. In view of the uneven air distribution inside the filter, the filter rod needs to be changed frequently and the stability of the equipment is greatly reduced. At present, it is very difficult to directly monitor the flow field in the filter by industrial means. Using ANSYS fluent 15.0 fluid simulation software to simulate the flow field of filter, to find out the reasons for the unfavorable factors mentioned above. Aiming at the airflow organization problem of the prototype filter, the structure optimization index and four optimization schemes are put forward, and the simulation results of the optimization scheme are referred to guide the engineering practice. Based on the simulation and analysis of airflow in the prototype of metal porous medium gas-solid separator, the reliability of the simulation results is verified by comparing with the measured data. The following results are obtained: the results of using Porous Jump model to deal with porous media filter rods are true and reliable. The non-uniformity of the flow field in the filter leads to a great change in the flow distribution coefficient of the filter rod. The maximum uneven amplitude of the filter rod flow 螖 K is as high as 1.47, and the integral flow uneven amplitude 螖 K is 0.131. The flow distribution coefficient of the two rows of filter rods at the edge of the filter rod is larger. The larger inhomogeneity of flow distribution coefficient not only increases the filter pressure but also increases the frequency of filter rod replacement or ash removal which is very unfavorable to the stable operation of the equipment. Aiming at the problem of airflow organization of prototype filter, four structural optimization schemes, such as changing the length and inlet height of filter rod, the number and layout of filter rod, the angle and quantity of air inlet and the setting of different permeable coefficient of filter rod, are simulated and calculated. The results show that the "optimum structure" of the four optimized schemes is: the length of the filter rod is 0.72 m, the height of the air inlet is 0.288 m; the first and second row filter rods are removed; the double air intake is arranged with a distribution of 90,270 0; and the column 4 ~ 8 is reduced. The permeable coefficient of the 4th row filter rod is 7 脳 10 ~ (-13) m ~ (2). Among the above four schemes, the "optimal structure" has a good effect on the optimization of the parameters related to the airflow uniformity, namely, the uneven amplitude of the maximum flow rate, the uneven amplitude of the comprehensive flow rate and the air flow uniformity index. Taking the maximum flow uneven amplitude 螖 K as an example, the "optimum structure" of the above four schemes is 63.27% lower than that of the "prototype" and 51.11% and 9.09% lower than that of the "prototype", respectively.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.8

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