Performance Of Side Flow Electrostatic Precipitation

As an important environmental protection equipment to reduce the air pollution and improve the air quality,the electrostatic precipitator(ESP)has been widely used in the purification of dust pollutants in industrial flue gas.But nearly all ESPs have to be reformed to improve the collection performance nowadays since the particulate emission standard is becoming more and more stringent.Although the ESP has made many progresses in terms of improvement of the power supply mode,optimization of the electrode structure,and transformation of the structure,it’s still difficult to meet the standard emission.In order to further improve the collection efficiency of ESP,a low-speed side flow ESP is proposed.This thesis carries out the following research work:1)Based on aerodynamic method,a theoretical expression of the collection efficiency under the influence of turbulent suspension is established.It is proved that decreasing the gas velocity in the electric field is a better way than increasing the length of the electric field to improve the collection efficiency of ESP.2)In order to solve the problem of unequal distribution of gas flow caused by changes in the direction of gas flow,the velocity and pressure distribution in the side flow ESP is simulated by the computational fluid dynamics software.The results show that the relative RMS value of Electric field gas velocity distribution is 0.35,which does not meet the standard in JB/T 7671.After a rectifying plate with 25% opening ratios is installed between two electric field passageway,and two rectifying plates with 56%opening ratios are installed at the entrance of electric field passageway,the relative RMS value is reduced to 0.2,which meet the standard in JB/T 7671.So the uniform distribution of the flow field of the side flow ESP is achieved,providing a design basis for its engineering application.3)In order to verify the synergistic of side flow ESP,comparison experiments of the collection efficiency are carried out under the same electrode configuration and flue gas flow rate.The talc powder with 11.6μm medium diameter is used in the experiment,The average inlet dust concentration is about 1400 mg/m3,The electric field strength isin the range of 3~4kV/cm.Results show that the emission concentration of side flow ESP is 59% lower than that of the conventional ESP.In order to reflect the purification effect of the side flow ESP on ultrafine dust,change the experiment powder into silica power with 3.5μm medium diameter and extend the electric field strength to2.5~4.5kV/cm,repeat the experiment.Results show that the emission concentration of side flow ESP is 45% lower than that of the conventional ESP.4)The effect of dust re-entrainment on the collection efficiency of ESP is significant.To compare the difference in dust re-entrainment between side flow ESP and conventional ESP,the analysis of the suspension force formula of charged dust particles in electric fields is performed.It is concluded that the levitation force of the dust re-entrainment particles in the electric field is proportional to the square of the gas velocity,which proves that decreasing the gas velocity can significantly reduce the dust re-entrainment.Then the comparison experiment of the dust re-entrainment is carried out.The silica powder with 3.5μm medium diameter is used in the experiment.The average inlet dust concentration is about 1400 mg/m3.The electric field strength is in the range of 2.5~4.5kV/cm.The experimental results have shown that the dust re-entrainment of the side flow ESP is 41% less than that of the conventional ESP under the same electrode configuration and flue gas flow rate.