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Air Pollution Control Device for Rolling Mill Coal Fired Ducts & Bends:Ducts and Bends are required to convey flue gases from point of suction to the chimney and connect various equipments like Cyclone, Scrubber, ID Fan and Chimney. Their sizes are based on flue gases volume & temperature. A Damper is usually provided at the suction point.
Cyclone: A high efficiency Cyclone separator is provided to capture dust particles. Flue gases after cooling in a Heat Recovery Unit are introduced in a tangential entry in the multiple tubes of the involute cyclone. Due to centrifugal forces dust particles settle at the bottom cones while flue gases exit the cyclone through the centre tube. Collected dust particles are periodically removed.
Scrubber: A Wet Scrubber is provided for treatment of gases in an Oil / Gas fired Re-rolling Furnace. In a Wet Scrubber the flue gases are introduced from side entrance at near the bottom of the shell. Then water is pumped from the storage tank
below the scrubber and is sprayed from the top through a sprinkler arrangement. Flue Gases move through the contact plate where the wetted dust particles settle. As the flue gases move up the scrubber, pollutants such as CO2, SO2 & NOx get absorbe d in water. Cleaned Flue Gases then move up and after passing through a mist eliminator where moisture in gases is removed, exit the scrubber. The dust as well as the gaseous pollutants are carried to the bottom tank with water. Here a dose of caustic / lime is provided to maintain the pH of the water. A three portioned tank also allows for settling of suspended solids in water which are then periodically cleaned and stored in HDPE bags in accordance with Hazardous Waste Management Rules. (Larger units may need separate Effluent Treatment Plants to properly treat water for re-circulation).
ID Fan: ID Fan provides necessary driving force to convey flue gases from suction point to top of the chimney. The volume sucked overcomes the total resistance offered by equipment and duct with the help of fluid horse power provided by ID Fan driven by suitable motor.
Stack (Chimney): The generated gases are passed through chimney of suitable height and diameter. The chimneys are provided and based on volume of flue gases temperature, dispersion desired, composition of gases and legal provisions for height. Discharge Characteristics as Per Norms
- Dust : Less than 150 mg/ Nm3
- Temp : Less than 80-100 C
- Gases : Traces of SO2, NOx, CO2 CO
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