The earliest date attempt of filtering suspended particles from gases and aerosols was first made by a scientist named Dr. Frederick Cottrell in the years 1906. The invention of the device, thus, is a result of this man’s attempt and the world owes to him big time. Evidence for his work is the US Patent 895, 729, which was filed in 1097 stating the work.
The patent described how suspended particles could be removed from every kind of industrial fume, smoke, and dust using high voltage electrodes. An interesting part of Cottrell’s patent reveals how the technique can be used for the destruction of fog and mist on land and also in water.
How does this device work?
Dirty flue gas is allowed to pass through two electrodes in the electrostatic precipitator. These electrodes are wrapped in metal wires and placed inside a pipe. The receiving electrode is negatively charged and the emitting electrode is positively charged.
The particles in the flue gas that passes through the device are attracted by the negative charges and attain the negativity. These particles are then attracted by the positively charged electrode due to their difference in charges. What comes out is only clean, fresh air.
The particles are removed using collecting plates at regular intervals via shaking, brushing, or automated cleaning processes like rapping. Some devices have additional fabric filters, which help in the removal of large-size soot particles.
Why is static electricity effective on smoke?
No matter how strongly you support the notion that smoke is gas, the fact cannot be denied that it is an aerosol. Yes, most aerosols contain liquid droplets. You’ve seen them in perfumes and air fresheners.
But, smoke as an aerosol contains soot particles instead. Whatever be it, smoke is liable to the influence of static electricity. These particles can be charged and removed from the flue gas. The high voltage which is applied can ionise the particles and separate them from the source.
What are the types of electrostatic precipitators available in the market?
The designs vary in the sense that they can separate particles of different size and chemical make-up from different volumes and types of flue gas. For instance, if a power plant burns excessive coal, the device has to be designed keeping in mind the chemical composition of the same.
Yet again, there are power plants that need to lower the emission of sulphur dioxide and ash which are generated during production processes. Devices for this purpose should be upscale in size.
Further, it also depends on the law of the area in which the device is being used. If the rules for air pollution control are very stringent, power plants running in the area might require multiple devices working simultaneously to clean air.
Lastly, the accessories are important, too. For instance, if your factory processes demand a huge amount of dust and smoke to be cleaned at frequent intervals, the device must be designed in such a way that it supports automated rapping systems.
What are the typical applications of the device?
• Gas production plants.
• Cement and limestone production plants.
• Iron and steel production plants.
• Chemical and metallurgical production plants.
• Coal boilers.
• Biomass fired boilers.
• Sludge incinerators.
The end story is, if there’s a device that can keep industrial air pollution under control, it definitely has to be an electrostatic precipitator. It’s efficacious, economical, and very much advantageous. It’s an invention devised exclusively for Mother Nature with love.