Air Cleaning Devices in a Smoke Generating Factory

Queryasked by Gopalkrishna Suryakanth

We have a factory manufacturing various auto-mobile parts. The manufacturing processes generate smoke and fumes of various types (different particle size, different chemical compositions etc.) Can you please tell what are the devices available for cleaning air?

Solutionby Gharpedia

The smokes which are generated in a factory as a result of various processes create an uncomfortable environment for employees and also contribute to air pollution. Hence, there is an inevitable need for purifying the air. Many air cleaning devices are available in the market, which purifies the air and increases its quality to make the factory work-friendly as well as environment-friendly.

Sizes of substances to be eliminated are a major factor in the selection of air cleaning devices. Coarse solids can be removed by screens. Particles down to 10-micron m in diameter can be settled out in settling chambers by expanding the cross section for velocity reduction to less than 10 ft/s. Particles between 10 and 200-micron m can be removed in cyclone separators, with an efficiency of 50 to 90%. Particles 10-micron m in diameter or smaller may be removed with filters made of cloth, metal, or glass fiber. But air or gas velocities leaving such filters are low. For dry fiber filters, efficiency may be only about 50%. The efficiency of such filters, however, may be increased by application of a viscous coating, such as oil with low volatility. Filters made of cloth usually are tubular bags, which trap particles as air or gas passes through. Bag filters remove 99% of particles larger than 10-micron m. Wet scrubbers or collectors remove particles 1 to 5-micron m in size. These devices also may remove water-soluble gases. Wet scrubbers are often used to clean air from kilns, roasters, and driers. They also are used for processes producing fine dust, films, vapours, and mists in food, chemical, foundry, metalworking, and ceramic industries. Ionizable aerosols and particles down to 0.1-micron m in size can be removed by electrostatic precipitators with an efficiency of 80 to 99%. These devices ionize particles in a gas passing through high-voltage electrodes.