Collection Enhancement Mechanism And Application Technology Of Bipolar Transverse Plate Electrostatic Precipitator

Electrostatic precipitators?ESPs?,which can be operated with high collection efficiency,low pressure drop and high capacity,are widely used in power plants,steel manufactories and cement plants,etc.However,the collection efficiency of the conventional ESP in terms of the submicron particles is relatively low,which cannot meet the increasingly stringent environmental emissions standard.Therefore,a bipolar transverse plate ESP was proposed based on the enhancement multi-mechanism of the collection performance,including bipolar charging,aerodynamic separation,electrostatic agglomerator and electrostatic force.In this ESP,there are not only the negative wire-ground plate electrodes,but also the ground wire-negative plate electrodes,which are all transverse to the gas flow.In order to reveal the collection performance and enhancement mechanism of the bipolar transverse plate ESP,following researches are given:It is clear that the electric field distribution is the foundation of the collection performance.According to Gauss flux theorem and superposition law,the theoretical normal expressions of electric field strength distribution of conventional wire-plate electrode and bipolar transverse wire-plate electrode are derived respectively.The results of the theoretical analysis show that the electric field strength and homogeneity between electrodes of the bipolar transverse wire-plate electrode is higher than that of conventional wire-plate electrode.The higher electric field strength,the less re-entrainment and higher migration velocity are.In order to clarify the dust removal enhancement mechanism of the bipolar transverse plate ESP,a flow function is used to establish the velocity distribution of charged particles flow around vertical wall.Then,the collection efficiency expression of the bipolar transverse plate ESP was established by means of the limiting trajectory method under the action of aerodynamic and electrostatic force.When the collection efficiency formula of the bipolar transverse plate ESP is modified,it submits approximately to the Deutsch formula.To verify the enhancement function of the bipolar transverse plate ESP,the comparative experimental study on collection performances of the bipolar transverse plate ESP and the conventional ESP was carried out.The result shows that,the corona current of the bipolar transverse plate ESP is 20⁴0%higher,and its penetration is about 45%less than that of the conventional ESP when the electric field is 2.1³.2kV/cm and the mean gas velocity is 1.5m/s.One of the key technique problems of the bipolar transverse plate ESP for industrial application is electrodes optimization.Therefore,laboratory experiment and electro-hydro dynamics?EHD?simulation of the bipolar transverse plate ESP are carried out to reveal the effect of wire-plate electrode parameters on corona discharging characteristics and flow field distribution.First,when the RS barbed wire and the C-480plate are used as the electrodes,the optimal wire-plate electrode combination is that one C-480 plate corresponds to two RS barbed wires.The wider the wire-plate spacing is,the better electric field homogeneity and corona suppression are.When the wire-plate spacing is 250mm,the corona current of the bipolar transverse wire-plate electrode is30%less than that of the conventional wire-plate electrode.Second,the EHD simulation results show that the secondary flow caused by ionic wind has less influence to primary gas flow in terms of a wide spacing electric field of the wire-plate electrode.The windward center,groove and the leeside of the plate are benefit for collecting dust.Third,the gas velocity parallel to the gas flow is turbulent remarkably,which is benefit for turbulence and electrostatic agglomeration.The experiments and simulations indicate that the optimal wire-plate electrode geometry is that,the wire-plate spacing is200²50mm with two wires located symmetrically at the airflow channel,and the wire-wire spacing is 200²40mm.The theoretical and experimental results of the bipolar transverse plate ESP technology have been proved by successful operation in an industrial sintering flue control.The project operation result shows that the mean emission concentration of the bipolar innovation ESP is reduced from 54 mg/m³ to 25.7 mg/m³,which is effective in dust emission reduction.