Dust Removal Mechanism And Experimental Research In Tube Wet Electrostatic Precipitation

As the main source of fine particles,coal-fired power plants need to be reformed for cleaner and more efficient,and coal-fired power plants are fully into the"ultra-low emissions"stage.Due to high efficiency,low energy consumption,large capacity and other advantages,wet electrostatic precipitator(WESP)has been encouraged to use in our country.Although WESP has better effect on the removal of fine particles,there still exists dry spot,channeling and unstable operation in engineering applications.In order to find solutions,this paper presented a new type of dust collection plate--stainless steel,and a tube WESP was built,then the dust removal mechanism and performance of WESP under the electrode configuration were studied.Firstly,the dust removal mechanism was analyzed in WESP.According to the Deutsch formula and the removal mechanism under the electrostatic and droplets,the calculation formula of dust collection efficiency and effective driving speed in WESP were given respectively.Then,an experimental scale WESP system was set up.The V-I characteristics in the electrostatic field were studied with the wire-net electrode configuration.Under unload,this study analyzed the current density in the electrostatic field,then the effects of positive and negative polarity,atomization of supply water,wire materials and gas velocity on the V-I characteristics were studied separately.The results showed that wire-net electrode configuration had stable electric field,low inception voltage,uniform electric field and higher corona current.Finally,the effects of applied voltage,gas velocity,inlet mass concentration,wet and dry on dust collection efficiency and pressure drop were studied.The results showed:The collection efficiency of Wet ESP was higher than Dry ESP.At applied voltage of 22.0kV,gas velocity of 0.8m/s,liquid gas ratio of 0.0214L/m~3,and atomization pressure of 0.25MPa,the collection efficiency of bentonite with the median diameter of 4.55?m was 99.968%in WESP,and the dust outlet concentration was as low as 5mg/m~3,which met the“ultra-low emission”requirements;at the same time,it had high removal efficiency to the fine atomization droplets,all about 99%;the pressure loss was in the range of 440-850Pa when the gas velocity was 0.8-1.5m/s.