环境湿度对PTFE覆膜滤料过滤性能影响研究

发布时间：2018-03-26 18:12

本文选题：PTFE覆膜滤料　切入点：环境湿度　出处：《北京化工大学》2015年硕士论文

【摘要】：燃煤电厂等行业排放的粉尘尤其是PM2.5对环境及人类健康产生极大的负面影响,采用覆膜滤料作为过滤材质的袋式除尘技术可实现对PM2.5的高效捕集。滤饼过滤阻力是影响袋式除尘能耗的重要原因,它主要取决于滤饼结构。空隙率是影响滤饼结构的重要参数,它与颗粒间作用力以及颗粒性质密切相关。烟气的脱硫脱硝等工艺会带入-定量的水,并随着温度的改变而影响烟气湿度,而湿度则会影响颗粒间作用力进而影响滤饼结构。因此研究湿度对颗粒间作用力及除尘性能的影响将对节约袋式除尘能耗有着重要意义。除了湿度滤饼空隙率还受颗粒性质的影响。粒径是描述颗粒的最基本参数,即使同一种颗粒粒径也会有较大差异。因此,研究颗粒粒径在不同环境湿度下对颗粒堆积行为的影响将具有实际意义。本文设计并搭建了一套环境湿度可控且长期稳定的实验装置。从绝对湿度和相对湿度两方面入手,通过测定颗粒群坍塌角考察了湿度对颗粒间作用力的影响；并采用PTFE覆膜滤料作为过滤材质,研究了环境湿度对滤饼过滤阻力、滤饼空隙率以及荷尘量的影响；并在此基础上研究了颗粒粒径在不同环境湿度下对除尘性能的影响。不同环境湿度下的滑石粉颗粒坍塌角实验表明：(1)颗粒间作用力随环境湿度的提高呈线性增长；与相对湿度低于100%时相比,空气饱和(相对湿度100%)时颗粒间粘附力随湿度增长更为迅速。(2)PTFE膜在高环境湿度下具有良好的清灰性能,这为其在高环境湿度下应用于袋式除尘提供了可能。过滤实验结果表明：(1)在滤料及气体固定的情况下,滤饼压降ΔPc可以看作是粉尘浓度c、表面过滤流速Vs、过滤时间,、滤饼空隙率ε和颗粒粒径dp的函数。其中c和t是独立变量,环境湿度、Vs、dp均影响ε。(2)环境湿度增大,颗粒间作用力增强,颗粒堆积更为疏松,滤饼空隙率提高,滤饼过滤阻力明显降低,有效延长了单次过滤周期,提高了荷尘量。对于1250目滑石粉,当环境湿度从0.0028g/g干气(粉尘密度为19.62g/m3)提高到0.0414g/g干气(粉尘密度为30.91g/m3)时,单次过滤周期从609s提高到5634s。但环境湿度对除尘性能的强化作用存在一个最优值,一旦超过这个值,强化作用开始减弱,甚至导致除尘性能恶化。(3)颗粒粒径越小,过滤阻力越高,滤饼阻力增长速率随环境湿度下降越快,说明小颗粒粒径的除尘性能对环境湿度响应更敏感。
[Abstract]:The dust emission from coal-fired power plants and other industries, especially PM2.5, has a great negative impact on the environment and human health. The bag dust removal technology using membrane coated filter material as filter material can realize the high efficiency capture of PM2.5. Filter resistance of filter cake is the important reason that affects the energy consumption of bag dust removal. It mainly depends on the structure of filter cake. Porosity is an important parameter affecting the structure of filter cake, which is closely related to the interaction between particles and the properties of particles. And with the change of temperature, the humidity of flue gas is affected. Therefore, the study of the effect of humidity on the interparticle force and dust removal performance will be of great significance in saving energy consumption of bag dust removal, in addition to the void rate of filter cake with humidity, it is very important to study the effect of humidity on the interparticle force and dust removal performance of filter cake. The particle size is the most basic parameter to describe the particle. Even the same particle size varies greatly. It will be of practical significance to study the effect of particle size on particle accumulation behavior under different environmental humidity. In this paper, a set of experimental equipment with controllable and stable environmental humidity is designed and built. The effect of humidity on intergranular force was investigated by measuring the collapse angle of particle group, and the effect of environmental humidity on filter resistance, porosity and dust loading of filter cake was studied by using PTFE membrane filter material as filter material. On the basis of this, the effect of particle size on dust removal performance was studied under different environmental humidity. The experimental results of collapse angle of talc particles under different ambient humidity showed that the interaction force between particles increased linearly with the increase of environmental humidity. When air saturation (RH) is 100, the adhesion between particles increases more rapidly than when RH is lower than 100. The PTFE film has good ash removal performance under high ambient humidity. This makes it possible to apply it to bag dust removal at high ambient humidity. The filtration experiment results show that: 1) when the filter material and gas are fixed, The filter cake pressure drop 螖 Pc can be regarded as a function of dust concentration, surface filtration velocity, filtration time, cake porosity 蔚 and particle diameter DP, where c and t are independent variables, and the environmental humidity (VsN dp) affects the increase of ambient humidity. With the increase of intergranular force, the accumulation of particles is more loose, the porosity of filter cake is increased, the filter resistance of filter cake is obviously reduced, the single filtration period is effectively prolonged and the amount of dust charged is increased. For 1250 mesh talcum powder, When the ambient humidity was increased from 0.0028g/g dry gas (dust density 19.62g / m 3) to 0.0414g/g dry gas (dust density 30.91g / m 3), the single filter cycle increased from 609s to 5634s. The strengthening effect began to weaken, even leading to the deterioration of dust removal performance. The smaller the particle size, the higher the filtration resistance, and the faster the increase rate of cake resistance with the environmental humidity, indicating that the dust removal performance of the small particle size is more sensitive to the environmental humidity response.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X773;TQ028.8

【参考文献】