Study And Application Of Fiber Filter Material Based On High-temperature Purification Of Flue Gas

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.