The wet electrostatic precipitator is used to remove sub-micron particulates, tars, condensable and acid mist as a final polishing device in an air pollution control system where an upstream dry ESP, fabric filter or wet scrubber cannot capture the sub-micron particulates due to their small size.
The fundamental purpose of the precipitation equipment is to remove suspended aerosols, acid mists and fine particulates from the gas stream of a boiler or other process to control air pollution.
A wet electrostatic precipitator is typically installed after a wet flue gas desulfurization (WFGD) system in the utility industry or after a wet scrubber in industrial applications where the flue/process gas has been cooled to moisture saturation, such as coal-fired power plants, refineries, chemical and petrochemical plants, steel and sugar mills, mining and fertilizer plants to name a few industries where Wet ESPs have been installed.
Although dry and wet ESP collection systems are conceptually similar, wet electrostatic precipitators require more corrosion resistant materials since they operate in a cooled, saturated process gas where acid gases have been condensed to a mist. Wet electrostatic precipitators are useful in obtaining low visible opacity through the removal of acid mists, aerosols and sub-micron particulates. Cleaning of the wet electrostatic precipitator occurs through intermittent washing versus mechanical rapping. There is also no re-entrainment losses or back corona problems in a Wet ESP unlike a Dry ESP. Wet electrostatic precipitators for most industrial applications are vertical up-flow using either square, hex or round collecting tubes. For larger gas flows a horizontal flow design with plate type collecting electrodes are used. Hamon Research-Cottrell can provide both tubular and plate wet electrostatic precipitator designs and will select an appropriate construction material providing long life, resistance to corrosion and reliability.
Wet electrostatic precipitator removal efficiency depends upon several parameters – gas composition, gas velocity, collection surface area, corona power, treatment time, particle size, and electrical sectionalization. The Hamon Research-Cottrell wet electrostatic precipitator can achieve very high removal efficiencies, typically exceeding 90% in a single collection field and over 99% using multiple collecting fields. Taking into consideration all of the various design parameters as well as the nature of the process gas to be treated is critical to designing a cost-effective wet ESP that can meet required emission guarantees. From design to manufacturing, each Hamon Research-Cottrell ESP is engineered to meet the requirements of the project and provide long-term reliable service.
Since Dr. Frederick Cottrell developed the first wet electrostatic precipitator to control sulfuric acid mist from a copper smelting process over a century ago, Wet ESP technology has become well-established in both industrial and utility applications around the world.
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