Experimental Study on Particle Removal of a Wet Electrostatic Precipitator with Atomization of Charged Water Drops

摘要

The insufficient capacity of a conventional electrostatic precipitator for fine-particle control limited the realization of ultralow emission in coal-fired power plants. Focused on this problem, the study described here reveals the design of a lab-scaled wet electrostatic precipitator (WESP) and the investigation of its removal performance for fine particles. The atomization of charged water drops was adopted to replace the traditional water film and mechanical atomization. Experiments for particle removal were conducted under controlled electric field intensities, water flow rates, residence time, and dust concentrations. The results demonstrated that the charged droplets effectively improved the corona current and particle removal efficiency compared with that of the dry ESP, and the advantage was increasingly apparent with increasing applied voltage and water supply. The efficiency difference between the ESPs with and without charged droplets increased from 1 to 17% as the electric field intensity increased from 2 to 5 kV/cm. Longer residence time coupled with a higher applied voltage led to an improvement in collection performance, while the removal efficiency was elevated to 97.70-99.09% from 89.91-94.94% as they enhanced from 2.14 s and 2 kV/cm to 4.04 s and 5 kV/cm. Moreover, increasing the dust concentration caused two opposite trends: the removal efficiency first increased to an inflection point and then decreased gradually due to the combined mechanisms of particle agglomeration and suppression of the corona current. Notably, the combination of charged water drop atomization and an electric field largely decreased the water consumption while keeping the comparable removal efficiencies with conventional WESPs.