The photographs below are for Electrostatic Precipitators (ESPs) for a coal-fired
power plant.
The top photo is of a cold-side ESP. This ESP is located downstream of the power plant's air preheater, which cools the flue gas to approximately 300 oF.
The bottom photo is of a hot-side ESP. The hot-side ESP is located upstream of the air preheater. At this location, the flue gas temperature is approximately 700 oF. Because of the larger flue gas volumetric flow rate at this high temperature compared to downstream of the air preheater, hot-side ESPs are larger than cold-side ESPs.