12.1 Introduction
Bag filter fans should have variable torque drive application, operating speed of
fan is observed between 60% - 100% depending upon process requirement with
all bag filter fans on VFD and 5 to 7.5% % damper Energy Loss, we may achieve
considerable energy saving and power factor is achieved near to unity during
normal operation of drive.
Dust Collector fans used for cement process to control nuisance dust in the system
& maintained the dust free environment in the plant. Since the air flow & pressure
requirement varies depending on process demand.
Bag Filter has to accommodate this variation by controlling the fan speed by
operating Damper control in the conventional system & Bag filter Fan running on
constant full speed.
Whereas in the VFD concept no damper is required, we can achieve process
required pressure & air flow by controlling speed of BF fan through VFD. Resulting
in saving power, compressor air & increased in bag life.
Details of Hardware requirement of conventional method & VFD concept and
advantages & disadvantages of system initial investment, process operation &
Energy Consumption are as below:
12.2 Conventional Method Details:
Following are the Major Electro Mechanical Hardware’s required to operate Bag
filter fan drive:
a. Mechanical Equipment’s
- Mechanical Damper – Manual damper up to 30KW Rating & above 30KW
Motorised damper required for BF Fans, wherever Manual dampers are in
operation, power loss will be approx. 10% more.
b. Electrical Equipment’s
- IMCC DOL/Star Delta starter Feeder of adequate rating for FAN Motor.
- RDOL Feeder for Motorised Damper Motor
- On account of DOL starter, Higher KW Motor Design
- Local Push Button station for Fan & Damper
With the conventional system & involvement of above Hardware’s during Operation
& Process Control, Practically Experienced the following limitations as under:
a. Mechanical Motorised or Manual Damper
- Damper System Installation time: - additional Damper installation time
required in conventional system - Routine & periodic maintenance of the damper is required & Additional man
hour required for damper periodic maintenance