Research On High Specific Resistance Dust Collection With Electrostatic Precipitator By Ultrasonic Atomization Humidifying And Cooling

Electrostatic precipitator, one of the main devices for controlling dust pollution, is widely used in thermal power generation, cement, steel and other industrial production process as its unique advantages like little energy consumption, high collection efficiency, handling large gas volume, wide scope of application, high degree of automation and stable and reliable operation. However, because of increasingly stringent environmental standards and new soot emission standard of our country, further improving the collection efficiency of electrostatic precipitator for dust and satisfying the new soot emission standard are important issue of ESP technology.Flue gas conditioning technology is widely used in the field of electrostatic precipitator and it can effectively increase the purification effect of dust especially high resistivity dust. However, there is still a lack of comprehensive and systematic exposition about the impact of the flue gas temperature and moisture on the effect of electrostatic precipitator dust collection, it is necessary for the future theoretical research and experimental analysis. Experiment studies the volt-ampere characteristic variation characteristics of the dust with no load under the conditions of different temperature and moisture content, and the effect of dust temperature and moisture content on the generation of anti-corona, surface density of corona current, and dust collection efficiency. It measures the specific resistance of dust in the given condition, in order to fundamentally validating the reason why temperature and moisture content have effect on the dust collection.When the temperature is150℃which is at its peak dust specific resistance, Results of humidifying dust show that surface density of current when dust starts anti-corona tend to rise with the dust moisture content, so we can know that dust humidification have contributed to charging of dust particles, reducing the specific resistance of dust and improving the efficiency of dust collection. The lower dust moisture content is, the higher dust specific resistance will be, the more obvious anti-electric field generated in the dust collecting plate after deposition will be, and the smaller the corresponding optimal voltage and the best collection efficiency will be. With the gradual thickening of the dust layer, the surface density of the corona current decreases, and the best power supply voltage rises, it due to the weakening of dust collecting field strength, the optimal dust collecting efficiency gradually declines. According to the experimental results, however, when the temperature of dust is150℃, although the specific resistance of humidified dust is reduced by two orders of magnitude, the dust is still a high specific resistance dust. When the moisture content23.73%, dust removal efficiency is highest, the optimal dust removal efficiency is70.57%.The initial anti-corona electric field intensity of high specific resistance dust reduces as the dust temperature rise. It shows that with the lowering of temperature, a higher voltage may be applied to the pole which almost does not produce a spark discharge and makes the dust particle charged fully. When the temperature is increasing, the surface density of corona current is decreasing, the dust collecting electric field intensity is reducing and the collection efficiency is declining, anti-corona of high specific resistance dust leads to the decreasing of its collection efficiency rapidly. In the conditions of same moisture content, the surface density of corona current increases with the increasing of temperature, and the higher specific resistance is, the large level of density increase. It shows that when the high specific resistance dust collection is in a lower temperature, the value of number of current density is small, the generation of anti-corona is effectively easy and the effect of high specific resistance dust collection is notable. The result of experiment shows that when the temperature is lowered to120℃, the dust specific resistance declines to below1011Ω·m and no longer belong to the high specific resistance dust, the dust collection efficiency is greatly improved at least16.76%compare to the conditions of 150℃and the same moisture content. When the temperature is reducing to below120℃and continue to declining, although the dust removal efficiency is still improving,but it begin to flatten.Through the experimental research about the impact of flue gas temperature and moisture content on the dust collection performance of electrostatic precipitator, it is of an important practical significance to the design of the filter structure and the selection of operation parameters, and the exploration of targeted technical measures about future improving the precipitator dust collection performance.