In the vertical design, the evenly distributed saturated gas flows upward through the electrostatic section of the WESP. An ionizing electrode runs down the centre of each tube. A strong electrical field is generated between the central discharge electrode and the collecting tube.
Electrons are emitted from the discharge electrodes which are charged with a rectified negative high voltage. Due to the high voltage difference, these electrons migrate towards the collecting electrodes: as particles pass through the gap between the discharge electrodes and the tube walls, they are intercepted by negatively charged gas molecules. These negatively charged gas molecules or negative ions accumulate on the particles surface and become fully saturated with negative charge.
As the gas with charged particles passes up the tube, it enters the collection section where there are strong repelling forces. The strong electrical field causes the charged particles and entrained droplets to migrate to the inner surfaces of the tube and consequently to be removed from the gas flow.