How to Choose Air Pollution Control Equipment For Your Plant

Electrostatic precipitators (ESPs) are air pollution control devices used to collect and remove particulate matter (PM), such as dust, from exhaust and industrial emissions. The ESP is a type of dry scrubber that uses static electricity to remove soot and ash from the emissions before they exit the chimney. 

ESPs use large transformers to produce a static electrical potential difference between the collecting plates and the charging electrodes. As the stack gas passes through the collection plates and electrodes, the charge generated attracts the particulate matter towards the collection plates. The PM is routinely removed from the collection plate and collected in the hoppers below. The particles are either mechanically dislodged or cleaned off by adding water. 

Bag or fabric filters are air filters that use cylindrical fabric bags to trap and remove airborne dust and particulates. As the gas passes through a baghouse, particulates accumulate on the filter’s surface, increasing its efficiency and allowing smaller particles to be collected. Some baghouses can achieve 99.9% efficiency, even for small particulate matter. 

These filters are suitable for various industrial processes, such as power plants, metal processing centers, and foundries, and are part of multi-stage cleaning systems. There are several methods to remove particulate accumulation, such as shaking the bags, introducing airflow in the opposite direction, or pulling compressed air into the baghouse. Particulates fall from the filter fabric to the bottom of the baghouse enclosure, where they are processed and disposed of.

Cyclone dust collectors are air pollution control devices that use centrifugal force to separate dry particulate matter from gaseous emissions. The gas flows in a spiral path inside a cylindrical chamber. This action pushes large particulates against the chamber wall and makes them drop into a collection hopper for later processing and disposal. 

Factories use cyclones for filtration applications of particulates ≥50 μm in diameter, but some models can achieve over 90% efficiency for particulates ≥10-20 μm. Efficiency depends on larger or smaller particulate diameters.

After cyclones, plants use additional filtration devices, such as baghouses, to capture smaller particulates that the gas stream may not have previously separated and collected.

Industrial scrubbers are used to control air pollution in manufacturing and processing facilities and use a physical process called scrubbing to remove particulates and gases from industrial emissions, such as smokestack exhaust. There are two main categories of scrubbers: dry scrubbers and wet scrubbers. 

Dry scrubbers inject neutralizing chemical agents into the emission stream, causing a chemical reaction that neutralizes or converts pollutants into harmless particles. 

Filters within the scrubber chamber collect and remove the spent agents from the cleaned emission gas. We can collect the material after the processes, clean it and reuse the agent. However, if this isn’t feasible, experts will handle and dispose of the waste. 

Wet scrubbers (wet adsorption scrubbers or wet collectors) use liquid solutions, typically water, to collect and remove water-soluble gas and particulate pollutants from industrial emissions. Wet scrubbing involves injecting a liquid solution into a gas stream or passing a gas stream through a liquid solution. The solution absorbs the pollutant and is removed from the gas stream when it comes into contact with the liquid. There are different types of wet scrubbers: bubbling scrubbers, packed beds (or packed towers), and venturi.