Induced Draft Fan

                ID Fan stands for induced draft fan. ID Fan is very important auxiliary of the boiler in the thermal power plant. It is used to remove the waste gases from the boiler after the combustion of the coal in the boiler. The ID Fan sucks the gases from the boiler and releases to the outside environment after collection of the ash and dust particles in  the electrostatic precipitators through the chimney. The ID fan creates the negative pressure so that the smoke inside will be suck through the path provided. ID fan are synchronous motors and works on the principle of VFD (Variable frequency drive)

                 A variable-frequency drive (VFD) (also termed adjustable-frequency drive, variable speed drive, AC drive, micro drive orinverter drive) is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage. The speed of the fan should be varying depending on the supply of the air to the boiler for combustion and always the boiler should maintain the negative pressure to avoid the flame to come out of the boiler which is done by the ID fan.

                 Proper operation of ID Fan is very much important as the postive pressure in boiler will reduce the life time of the boiler and flame will get out of the boiler and also more negative pressure in the boiler  will put off the flame and interrupts the plant operation also leads to the reduction of life time of the boiler.VFD is very much important to save a lot of energy as the speed of the fan can be varied according to the demand, if VFD is not present and a fixed speed device is used the speed will remain same even though the demand is not there. This wastes a lot of  power.