7 types of equipment for controlling air pollution in factories

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7 types of equipment for controlling air pollution in factories

The choice of factory air-pollution control equipment depends on several factors: the required removal efficiency; pollutant characteristics such as temperature, humidity, solubility, particle size, concentration and quantity; and the production process. Equipment suited to different pollution problems can therefore be classified as follows:

1. Dust settling chambers ( Setting chamber)  These are large chambers or vessels in which passing dust settles to the floor under its own weight. They suit large, coarse or heavy particles and are generally used for preliminary treatment ( Primary treatment) before a more efficient system.

2. Cyclones ( Cyclone)  These collect dust using centrifugal force. Ordinary cyclones effectively collect particles sized 50 microns ( 0.05 mm) and larger. High-efficiency cyclones ( High efficiency cyclone) effectively collect smaller particles approximately 10 microns and larger. Examples of applications include sawmills, animal-feed mixing plants, silos, rice-husk ash and dust from metal grinding.

3. Fabric filtration systems ( Bag filter)  These remove fine particles by filtering them through fabric bags. The bags may be specially woven cotton or synthetic fabric. Applications include dust from chemical and rubber mixing; wood and metal sanding; lead melting; metal melting requiring high removal efficiency; cement dust; sandblasting; and mixing or grinding powdered raw materials where high collection efficiency is needed.

4. Electrostatic dust collection systems ( Electrostatic precipitator)  These collect fine dust similarly to Bag filter and suit large facilities such as cement plants and steelworks. These systems must be imported from abroad.

5. Water spray systems ( Spray chamber) These are low-efficiency systems for removing dust or gases, used to collect coarse particles such as rice-husk ash and metal-melting dust where the plant is far from residential communities.

6. Packed-bed collection systems ( Packed scrubber)  These remove gaseous pollutants or medium-sized particles. Typical uses include acid fumes from electroplating, chemical vapors that can be absorbed or dissolved in the sprayed scrubbing liquid, dust and chemical fumes from metal melting, and odor control in fishmeal plants.

7. Venturi scrubbing systems ( Venturi scrubber)
- These operate by passing a flow of polluted air ( Wastegae) through a narrow passage ( Venturi tube) at very high speed ( 15,000-20,000 fpm) while liquid is sprayed to wash out or absorb pollutants almost immediately.
- Their pollutant removal efficiency is classed as high, for gaseous pollutants or very fine particles.