The Experimental Research On The Performance Of Synthetic Fibres For High Temperature Flue Gas Filtration

The research is mainly about the performance of synthetic fibres using in high temperature flue gas filtration. The synthetic fibres are the main raw materials of the filter media for bag filter, and the performance of which, such as heat resistance & corrosion resistance, flame retardant, will make a significant influence on the service life of filter media.This paper firstly summarizes and analyzes the properties of flue gas, main factors affecting the performance of fibres from various industrial kilns, and the application status of different fibres. Based on the existing fibre testing method for fibre's performance home and abroad, a reasonable and specific test method is designed to meet the typical problems of fibres in application. More comprehensive research and an exploratory study are taken on the performance of polysulfonamide fibre (PSA fibre for short), which has domestic intellectual property rights, to make PSA fibre more competitive.As filtration media is vulnerable to corrosion when the gas temperature below is dew point, polyphenylene sulfide (PPS) fibre, aromatic polyamide (PMIA) fibre, polyimide (PI) fibre and polysulfonamide (PSA) fibre, which are commonly used in high temperature exhaust filtration, are choose as sample. Using sulfuric acid, hydrochloric acid, sodium hydroxide and other chemical reagents, fibre destructive test is performed under different temperature and concentration condition, through which main performance indicators of fibre can be measured and compared, thus the corrosion resistance of different fibres is concluded. The results show that corrosion-resistant performance of fibre is related with fibre chemical structure, chemical reagent type, concentration, and testing temperature. PPS fibre has the best chemical resistance among these fibres, which is less affected by environmental factors. The fibres, whose polymer is made by polycondensation, take place hydrolysis reaction easily in a certain temperature and pH environment, resulting in the strength decreased sharply. The acid resistance of PI fibres at 85℃is better than that of PMIA fibre, which is approximately equal to that of PSA fibre. PI fibre is sensitive against alkali corrosion and will dissolve in alkali liquid quickly at high temperature. PMIA fibre has alkali resistance a few better than that of PSA fibre.A fibre combustion device is designed for fibres' burning and a flue gas analysis equipment is used to measure the composition and concentration of combustion gas of different fibres. The results show that the decomposition products of fibres are basically decided by their chemical structure. Four fibres are aromatic fibre, whose combustion gas composes mainly of CO; NO_x also appears in the combustion gas of PMIA fibre, PSA fibre and PI fibre because of containing amide (—NHCO—)groups. PPS fibre and fibre PSA respectively containing thiophenyl (—C—S—) and sulfone (—SO₂—), which also contain SO₂. With the temperature increasing, CO concentrations were normal distribution curve, NO_x changes in a series of cascade curve, and SO₂ shows like wavy curve. The maximum descending sequence is PMIA fibre, PI fibre, PSA fibre, PPS fibre in turn and that of NO_x is PMIA fibre, PSA fibre, PI fibre. The releasing of SO₂ from PPS fibre is more than that of PSA fibre.In order to improving the corrosion-resistant performance of PSA fibre, the way of PTFE emulsion impregnating in different concentrations is adopted, and after that, PSA fibre is still destructive tested. The results show that corrosion resistance time of PSA fibre is extended and the strength decline slowly down through impregnation. This is because the surface of PSA fibre wrapped with a layer of PTFE particles, using PTFE excellent chemical resistance to corrosion. There are many factors influence the optimized performance of PSA fibre, such as PTFE emulsion quality, concentration, treatment and other relevant.The research is of the bag filter fibre technologies in-depth, the results of which has an important practical value and engineering guidance for project and promotes the progress of the technology of filter materials' fibre.