【作者】 王振华；

【导师】 沈恒根；

【作者基本信息】 东华大学 ， 供热、供燃气、通风及空调工程， 2014， 博士

【摘要】 当前,雾霾引发的空气污染问题危害人们的健康和生活质量,成为社会关注的热点问题,在工业炉窑中如何更有效控制颗粒物的排放成为我国环保领域的研究热点。袋式除尘技术作为含尘烟气净化的重要途径之一,已经在除尘领域得到广泛应用。纤维滤料技术长期以来主要偏重于产品性能技术研究,在与重化工行业快速发展中实施相互匹配的功能化技术研究方面显得落后,滤料技术目前已逐渐表现为束缚袋式除尘技术进一步发展的瓶颈技术。对滤料技术进一步深化研究的根本在于将滤料的技术性研究转化到对滤料的功能化技术研究上,即：把滤料自身性能的研究与滤料应用的环境紧密结合起来,从行业应用的角度进一步深化认识纤维滤料的各种特性和织物构造,进一步提出正确使用滤料的方法和技术改进的途径。针对目前存在的问题,本文主要做了以下相关研究：(1)针对各种滤料主材的耐高温特性进行了试验研究,分别从热稳定性分析和阻燃性角度,尤其对进一步使用的芳砜纶进行了热反应动力学分析。热稳定性试验结果表明,PSA纤维滤料的高温稳定性优于PMIA、PI纤维滤料；玄武岩纱线及复合滤料的高温处理后力学性能优于玻璃纤维纱线及其滤料。高温对滤料表面的纤维结构有一定程度的损伤,纤维出现断裂、炭化、剥离等现象,这是导致纤维力学稳定性降低、滤料高温力学失效的重要原因。对芳砜纶进行的热降解动力学分析得到：采用不同升温速率时,随着升温速率的增大,PSA纤维的初始分解温度及热降解速率最大时的温度均升高；采用Kissinger法比用Flynn-Wall-Ozawa法和Friedman法所得到的活化能高,并得到芳砜纶的热降解动力学方程。(2)对耐高温纤维滤料的耐酸碱失效特性的试验表明：PPS纤维的耐酸和碱腐蚀性能最好,PI纤维的耐酸性优于PSA、PMIA纤维,而耐碱性最差；PSA纤维和PMIA纤维的耐酸稳定性接近,耐碱稳定性上后者好于前者；纤维成网后形成的针刺毡的变化趋势与纤维一致,有一定程度的提高；BAS/PSA复合滤料和GLA/PSA复合滤料的耐碱腐蚀稳定性接近,而前者的耐酸腐蚀稳定性优于后者。酸碱环境会使纤维的表面微观形态、分子官能团结构发生变化,这是导致滤料失效的重要原因。(3)对不同织物构造形式的袋式除尘滤料进行了过滤效率的试验研究,尤其是具有梯度构造的滤料。试验分析了织物构造中纤维细度、纤维比表面积、滤料单位面积质量对过滤效率的影响,同时还对比了不同过滤方式的滤料在试验设定的不同过滤风速、粉尘负荷下的过滤效率。试验结果表明,不论在清洁状态还是含尘状态下,梯度滤料(表层过滤)表面的超细纤维使得其分级效率较高,几乎可以与覆膜滤料的分级效率接近,对粒径大于1.0μm的颗粒物过滤效率接近100%,对颗粒物的分级效率明显优于深层过滤材料。在滤料构造中适当选用比表面积大的纤维(如细旦纤维、异形纤维等),可以有效增加滤料的过滤效率;对不同粒径颗粒物的过滤效率随滤料的克重(厚度)增加均呈上升趋势,且存在最佳克重(厚度)；滤料的构造形式对分级过滤效率有很大影响。(4)将量纲分析理论用于滤料理论过滤效率的建模中,建立基于量纲分析理论的滤料过滤效率的无量纲表达式,提出了定性判定滤料过滤效率的无量纲量,填充率和颗粒物直径与纤维直径的相对尺度。基于量纲分析的结果得出在滤料的构造设计中需提高相对尺度和纤维层的填充率,在袋式除尘滤料的构造设计中采用有梯度的纤维层设计,并在滤料表面引入超细纤维层,为袋式除尘过滤材料的结构设计中采用梯度构造找到理论上的支撑点。(5)利用模糊灰色理论,提出了耐高温纤维性能和滤料织物构造形式的评价,结果表明：四种耐高温纤维性能优劣顺序依次为：聚酰亚胺纤维(PI)、聚苯硫醚纤维(PPS)、芳砜纶纤维(PSA)、芳纶纤维(PMIA),并且其中芳砜纶与聚苯硫醚的性能评价接近,优于芳纶。三种滤料构造形式的优劣顺序依次为：梯度滤料、覆膜滤料、深层滤料,因此在滤料的设计选用时优先采用梯度构造。应用灰色关联评价减少了评价的主观性和盲目性,保证了评价结果的准确可靠及较大的实用性,评价结果以量化形式显示,使不同种类的耐高温纤维和不同构造形式具有可比性,该方法的采用方便了对过滤材料的评价和选型设计。(6)对燃煤电厂电站锅炉采用燃煤掺烧高炉煤气,烟气排放温度接近200℃且腐蚀性较大的工况,进行选用滤料设计选用及试验分析。设计中选用了梯度过滤材料和国产耐高温纤维。结果表明,选用滤料在250℃高温环境下的强度保持率均保持在100%以上,但尺寸稳定性上低于另外两种对比试验的玻纤滤料：在酸性腐蚀环境下的强度保持率都明显高于其他两种滤料；在氧化环境中经纬向的强度保持率均保持在90%以上；过滤性能方面,该选用复合滤料在清洁状态下阻力低于对比的两种滤料,并且在低风速环境下设计滤料在颗粒物捕集效率上高于对比的两种滤料。更多还原

【Abstract】 The performance of the filter material is an important factor for long-term stable operation of bag dedusting system, so the study of filter material structure characteristics is of great significance. In thermal power plants boiler dust removal, for example, the filtration technology gradually transforms from the electric to bag-type dust collector, which puts forwards higher requirements on the high temperature filter material of filtering efficiency, service life, etc. So the technology of filter material research is very necessary.This thesis focuses on the following elements:(1) Experiments were taken to study the high-temperature characteristics of various filter materials respectively, from the analysis of the thermal stability and flame retardance angle, especially for further use of PSA kinetics analysis conducted heat. Experimental results showed that the thermal stability, high temperature stability PSA fiber filter is better than PMIA, PI fiber filter; basalt yarns and high temperature processing of the mechanical properties of the composite filter is superior to glass fiber yarn and media. High temperature on the surface of the fiber structure of filter media has a certain degree of damage, fiber breakage occurs, charring, peeling phenomenon, which is an important cause of lower fiber mechanical stability, high temperature mechanical filter failure. Thermal degradation kinetics analysis conducted polysulfonamide get:When using different heating rates, with increasing heating rate, initial PSA fiber temperature and thermal decomposition temperature of the maximum degradation rate were increased; using Kissinger method than using Flynn-Wall-Ozawa and Friedman methods obtained the activation energy is high, and get polysulfonamide thermal degradation kinetics.(2) Important factors such as high temperature and chemical factor affecting the reliability of the bag filter run were tested and analysed. The antitemperature experiments showed that PSA had better high temperature stability than PMIA and PI fiber media; basalt yarn and fabric had better high temperature stability than glass yarn and fabric. The chemical experiments showed that PPS had the best acid and alkali resistant; the acid resistant of PI was better than PSA and PMIA; the acid resistant of PSA and PMIA were close and the after had better alkali resiatant; the alkali resiatant of BAS/PSA and GLA/PSA were close and the former had better acid resiatant. The fabric had the same trend with the fibers after they were net together.The fiber surface morphology and molecular structure change in high temperature or chemical environment, which were important reasons leading to media failure.(3) In order to verify the performanceof gradient structure of filter material filter and reveal the rarionality of existing fiber fineness and thickness, tests of the filtration efficiency of the dust filter bag of different types of fabric structure were experimented. The effect of the fiber fineness, specific surface area, mass per unit area to the filtration efficiency were analysed, and also compares the filtration efficiency of different filters type under setting different filtration velocity and dust load. The results showed that in both clean and dust state, the gradient filter material filter with the surface of ultra-fine fiber on the surface made the classification efficiency is higher, which can be close to the effect of filter material classification efficiency. To the particle size which is greater than1.0microns particle filtering efficiency is close to100%, which is obviously better than the deep filtration material classification efficiency. The results showed that the use high specific surface area fiber (eg. superfine fiber) can increase the filtration efficiency and the filtration efficiency increased with the mass per unit area (thickness) and there exist an optimnum thickness.(4) At the same time, the dimension analysis theory was used to filter efficiency of filter material theory model and based on the theory of dimension analysis filter efficiency of filter material dimensionless expression, this paper put forward the filter efficiency of filter material qualitative determination dimensionless quantity, filling ratio and the particle diameter and the relative measure of fiber diameter.Through the analysis of fiber fineness affecting the performance of filter media, the new structure filter-gradient filter found support points in theory. The superfine fiber layer used in the fabric increase the filtration efficiency at the same time still can reduce the dosage of fiber effectively.(5) Evaluation of high-temperature fiber fabric filter performance and structural forms was established by using fuzzy gray theory. The results showed that:four kinds of high-temperature performance merits of the order of fiber:polyimide fiber (PI), polyphenylene sulfide fiber (PPS), PSA fiber (PSA), aramid fiber (PMIA), and in which the performance evaluation of polyphenylene sulfide and polysulfonamide was close, better than PMIA. Advantages and disadvantages of the three forms of media construct order:gradient filter, membrane filter media, deep filter, the filter is designed so when the priority selection gradient structure. Application of gray correlation evaluation reduces the subjectivity of evaluation and blindness, to ensure the accuracy and reliability and practicality of a larger evaluation results, the evaluation results are shown in quantized form, so that different forms of high temperature resistant fibers and different types of structures comparable the method adopted to facilitate the evaluation and on the filter material selection and design.(6) Consider the condition of coal fired power plant boiler using coal mixing burning blast furnace gas and flue gas temperature is close to200℃, the applicability of the filter material was tested. The results showed that the breaking strength retention rate was100%in250℃, but the high temperature dimensional stability was worse than the comparive glass fabrics; the acid resistance was better than the other two; the strength retention rate was above90%in the oxidation condition; filtration efficiency to5.0μm particles were above99.99%under low airflow. In a word, the choosen media has application for the sepecial conditon.更多还原