Induced Draft Fan Vs Forced Draft Fan

Before they were applied to air cooled units induced or forced draft fans were applied to boilers for furnishing combustion air and they still are to this day.

Induced draft fan vs forced draft fan. It lives in a much friendlier environment and therefore may be less susceptible. Typically the fd fans control airflow. They will probably always be optional methods for boiler combustion air source. Forced draft fans focus the pressure and volume at the outlet of the fan to push air through a system creating positive air pressure.

Industrial induced draft fans operate by focusing the pressure and volume at the inlet of the fan to pull air through a system. Air is pulled across the finned tube surface. Forced draft fd fans supplying air to the furnace and induced draft id fans removing flue gas. In theory the primary advantage of the forced draft unit is that less power is required.

In a balanced draft boiler you actually have both. The air moving device for an air cooled heat exchanger is commonly an axial flow propeller type fan that either forces the air across the bundles forced draft or pulls it across induced draft. To provide redundancy in case a mechanical unit falls and to provide the basic control achievable by running one fan or two a bundle or set of. Induced draft air cooled heat exchangers.

It s not always either or. All motor coupled industrial blowers fans are supplied with suitable couple set as per blower capacity. The advantage of the forced draft fan is that the fan itself is not in the high temperature acidic environment of the exhaust gases. Id fan will take the hot flue gases from furnace via dust collector dust separation system or fume extraction system and will deliver to chimney.

The induced draft fan pulls things through the furnace and then pushes them out the vent. This is true when the air temperature rise exceeds 54 f 30 c because the fan is pumping denser air. The forced draft fan only sees room air. Forced draft means an exhaust fan placed at the base of the cooling tower which then causes overpressure.

Id fan will handle the flue gases i e. Fans are located above the bundle. I ve used the combustion air fan on boilers both ways induced or forced. Id fan is basically mentioned here for induced draft fan and id fan is always located between dust collector and chimney.

Couple drive induced draft id fans and forced draft f d fans. Axial fans are always used for this type of draft. Induced draft implies an inlet fan placed on top of the cooling tower and the creation of low pressure.