What is Forced Draft Cooler?
The Forced Draft Cooler is tubular convective type Heat Exchanger used for cooling of hot gases.
In Sponge Iron Plants the kiln outlet gases are at approx. 900 to 950 °C. These flue gases cannot be let out to atmosphere as it is and are to be de-dusting. Hence, it is mandatory to provide Dust Collecting system. The major problem of providing the Dust Collecting System is the temperature of the flue gases and it becomes necessary to cool the kiln exhaust gases to around 180 to 220 °C.
The best way to accomplish this task is to have air to gas heat exchanger. Although dilution with ambient air / water spray etc. are available for the heat exchanger. Air to gas force draft heat exchanger are the simple, economical & best suited system.
Forced Draft Cooler - System Description
The air to gas Cooler is a tubular heat exchanger where, the hot kiln exhaust gases are made to pass over the tubes and cold atmospheric Air is made to pass through the tubes.
This system saves considerable energy due to lower pressure drop. Also the cleaning of the FD Cooler is easy as the dusty air is made to pass over the tubes. Since there is practically no moving parts in the system and the design is a modular construction, it is easy to install, and economical and easy to maintain. This system is designed for 24 x 7 operations.
Forced Draft Cooler – Advantages
- No water requirement.
- Less power consumption due to low pressure drop of the system
- Low in operating cost – Due to use of ambient air
- Easier to install, clean and maintenance doe to modular system
- Less space required – due to modular construction
Forced Draft Cooler – Design Basis
- F D Cooler is for the cooling of flue gases.
- Flue gas would pass outside the Tubes and cooling air inside the Tubes
- Easier maintenance of the Heating surface
- Lesser Choking of the Tubes
- Low Pressure drop in the flue gas side thereby saving the power consumption I.D. fan
- Modular construction saves precious time in erection
- On line cleaning of system with compressed air Blast
- Over temperature protection
- Warm cooling air can be used by proper tapping to the advantages of the plant to reduce fuel consumption
- Individual Force Draft Cooler (FDC) for individual kiln