Theoretical And Experimental Approach On Charged Droplets With High Charge-mass Ratio Generated By Jet In Electrostatic Field

The flue gas emitted from the process of the industry production containing the dust which was harmful to the human and environment should be purified. Conventional wet scrubbers have more than 90 percents of the dedust efficiency on dust more than 10μm. But for the dust smaller than 10μm especially for the respiratory dust smaller than 5μm which was harmful to the human , their dedust efficiency is very low. The pressure drop of some scrubbers is quite high. For instance, Venturi scrubber have great resistance. This paper seeks to explore critical technology which is urgently needed in the flue gas dedust and desulfurization technology in the field of air pollution control, how to get high charge-mass ratio droplets .Based on the non-Rayleigh phenomena that the jet will be accelerated with the assistant of pressed air and break up into charging droplets with super-high charge-mass ratio in the electrostatic field, we studied it by two theories of jet breakup and charging and analyzed the structure and force bearing inside the charging two-phase jet.Rayleigh theory is based on the jet bursting into catenarian non-continuous droplets, whereas the jet spray passing through the electrodes will break up into great uneven groups of charged droplets. There is a big bifurcation that the jet firstly burst up into droplets and then the droplets being charged or the jet firstly be charged and break up into droplets when this non-Rayleigh phenomenon being studied. And the later hypothesis that the jet firstly be charged and break up into droplets was adopted in this paper.The article theoretically established the relations that induction charge of droplets with the property of the liquid, the voltage applied on the electrode, the size of the nozzle, liquid flow and air flow. The electrified jet breakup theory of two-phase flow was discussed, including nozzle design, electrostatic affecting on the jet, the relation of average size of the droplets. The compressed air was used in the experiment to accelerate the jet which was gas-liquid two-phase flow in the static electric field. The effect of the pressure and velocity on the form of the droplet was analyzed by the two-phase flow theory. The theory of field charging ,discharging of charged body, induction charging of liquid in the two-phase flow and equivalent electric circuit was applied to establish the math-physics model of electrified jet break up into charged droplets .The experiment results show that influence factors of charges of two-phase flow spray have applied voltage, radius of the electrode, induction ring spacing from the nozzle and jet speed, the theoretical expression of jet breakup of spray can explain the spray current is related to the factor mentioned. The experimental results is extraordinary consistent with the theoretical results.The collecting theory that charged droplets acting on the dust under multi-mechanisms actions is established, including electric cohesion, particle-diffusion, inertia collision and interception charged droplets of dust particles collected theory.