Collection efficiency As we all know, bag filter has a higher collection efficiency than electrostatic filter bags, particularly serious impact on the human body of heavy metals and submicron dust particles capture more effective. Usually dust removal efficiency of up to 99.99 or more, the concentration of dust emissions to stabilize below the 50 mg / N mm³, even up to 10 mg / N m³ or less, almost zero emissions. Power industry from the current coal-fired boiler applications, the bag house emission can guarantee 30 mg / N m³ or less. Hohhot boiler flue gas purification plant two 200 MW unit uses a bag filter, the result of long-term tester automatic monitoring system results from the CEMS and authoritative testing unit manual sampling tests, the emission concentrations were lower than 27 mg / N m³. With the further improve the national environmental standards and an increasing number of power plants fueled with low-sulfur coal (or via a highly efficient desulfurization), the electrostatic bag house, even if compliance is becoming increasingly difficult. While its highly efficient bag filter filtering mechanism determines its influence from the combustion of coal physical and chemical properties change, with a stable collection efficiency. The method of collection for the current national environmental emission standards and emission costs, bag house economic benefits are obvious. Third, the impact of system changes on the bag house Coal fired power plants is relatively stable, but they can not avoid encountering when coal or coal quality changes; boiler systems is a frequent changes and regulation system, out of the physical and chemical properties from the boiler flue gas, dust concentration, temperature and other parameters can not guarantee does not change. This series of changes for different dust can cause distinct changes. The following were compared from several major areas: 1, send, Fan wind changed, changes in the boiler outlet dust concentration Of bag filter: changes in the concentration of dust bag filter bag only cause load changes, resulting in cleaning frequency change (automatic adjustment). Fouling dust concentration on high-speed bag fast, high frequency corresponding cleaning, cleaning frequency is low and vice versa, while the emission levels will cause no change. Electrostatic precipitator: dust concentration change directly affects the dust load power, and therefore directly affect the collection efficiency of the electrostatic precipitator, and ultimately reflected in the change of emission concentration. Generally increases the concentration of dust collection efficiency, emission concentration will increase accordingly; reduce the concentration of dust collection efficiency decreases, the concentration of emissions will be reduced accordingly. 2, boiler soot same amount, delivery, induced draft fan air volume change Of bag filter: Due to changes in air volume caused by changes in direct filtration velocity, which causes a change in resistance of the device, but no effect on the collection efficiency. Increase the amount of equipment to increase wind resistance, induced draft fan output increases; on the contrary contribute to reducing the induced draft fan. Air volume change does not have much influence on the device, but the collection efficiency of the electrostatic bag house wind amount of change is clear: an electrostatic bag house. If the air volume increases, the electrostatic bag house field wind speed increased dust in the electric field of the residence time is shortened, although the electric field enhances the effective displacement stroke disturbance forward speed charged dust, but not enough to cover the dust caused by high wind speed in an electric field in stay time is shortened and the negative impact brought about by increased secondary dust, thus reducing the collection efficiency is very obvious; on the contrary, increased collection efficiency, but increased slightly. 3, temperature changes Of bag filter: flue gas temperature is too low, condensation may cause a “paste bag” and the casing corrosion, high temperature flue gas temperature exceeds the filter allows easy “burn bag” damaged bag. However, if the temperature changes in the media to withstand a temperature range, it will not affect the collection efficiency. Temperature-induced adverse consequences in extreme temperatures (Accident / abnormal state), so the bag filter must be provided with effective protection measures to limit temperature control. Electrostatic bag house: flue gas temperature is too low, condensation can cause corrosion or high voltage creepage housing, but the collection efficiency is good; the flue gas temperature, dust resistivity increase is not conducive to dust. Therefore, flue gas temperature directly affects the collection efficiency, and the impact is more obvious. 4, physical and chemical composition of flue gas (or coal burning) change Physical and chemical composition of flue gas has no effect on the collection efficiency of bag filter: on the bag filter. But if all the media contained in the flue gas has a component corrosion damage will directly affect the life of the filter. Electrostatic bag house: flue dust than a direct result of physical and chemical composition change in resistance, thus affecting the collection efficiency, but also a great influence. The most direct impact of the content of sulfur oxides in the flue gas, sulfur content is usually higher oxygen compounds, dust the lower the resistivity, the easier it is collecting dust collection efficiency is high; the contrary, the collection efficiency is low. Also smoke in the chemical composition (such as silicon, aluminum, potassium, sodium and other content) changes will cause significant changes in collection efficiency. 5, air distribution Of bag filter: collection efficiency and air distribution is no direct relationship, that does not affect the collection efficiency of air distribution. But dust inside the local flow distribution should be uniform, not too much deviation, otherwise they will be due to local uneven load caused by wear and tear or partial jet broken bags, bag filter affect normal life. Electrostatic bag house: Electrostatic filter bag are very sensitive field of air distribution, air distribution is good or bad a direct impact on the level of collection efficiency. In the electrostatic bag house performance evaluation, the RMS index of air distribution is usually one important index for an electrostatic bag house is good or bad. 6, air preheater air leakage and duct system Of bag filter: oxygen tolerance for poor performance will affect the filter bag life, such as: RYTON filter, but the collection efficiency is not affected. Since the system is mixed cold air volume increase due to increased resistance of the system. Electrostatic bag house: no significant change in resistance of the device, but the system air volume increased to improve the collection efficiency of the electric field Winds influence.
