ID,FD,PA FANS COMMISSIONING OF BOILER PART -X -ABC OFTHERMAL POWER

In my last blog I have discussed about the lube oil supply unit for fans ,Air heaters and Mills.

Construction features and item including control and instrument in the lube oil system is

more less same .Therefore observing one lube oil commissioning will help to learn the other.

Now we will discuss the commissioning of FANS. The commissioning of six numbers of

FANs are similar however system requirement for commissioning of FANs are different. We

will discuss the common system requirement and the individual requirement of FANs.

Induced Draft Fan

No of Fan                                :  2

Flow   (Approx)                       : 558.2 cu.m/Sec

Pressure (Approx)                  :  485 mmwc

Temperature                           :  150⁰C to 154 ⁰C

Drive                                       :  Motor

Speed                                     :  580 RPM

Motor Rating                           :  3650

Control                                    :  Inlet Damper plus variable  / Hydraulic coupling

                                                   Frequency Drive. (VFD).

Forced Draft Fan

No. of Fan                                                   :  2

Flow    (Approx)                                          :  246 cu.m/Sec

Pressure    (Approx)                                    : 351 mmwc

Temperature                                               :  50 degree C

Drive                                                            : Motor

Speed                                                           : 980 RPM

Control                                                         : Variable Blade Pitch control.

Motor Rating                                               :  1175 KW

The boiler   is also equipped with primary air fan, which form a part of the coal preparation a

and firing system.

PRIMARY AIR FAN

 

No. of Fan                                               :  2

Flow       (approx)                                   :  170.5 cu.m/Sec

Pressure   (approx)                                 :  1183 mmwc

         

Temperature                                           :  50 degreeC

Drive                                                       :  Motor

Speed                                                      :  1480 RPM

Motor Rating                                          :  2450 KW.

Control                                                   :  Variable Blade Pitch

                                                                  control.

(****- All the values given here are of 500MW set of BHEL Make.)

 

All the fan are mounted on concrete deck with suction and discharge duct. Connected to the

Fan flanges. FD Fans and PA fans are provided with Silencer at the suction duct. 

Regulation of Fan from no load to full load is performed by changing the pitch angle of blade

profile on all blades simultaneously during operation. This is achieved through a

sophisticated servo mechanism (Hydraulic Servo Motor externally actuated by a power

cylinder and forced lube-oil system.

In the case of ID Fan, the equipment is driven by variable frequency drive motor coupled

with soft coupling. The regulation of the fan is effected through the inlet dampers located at

the inlet of the fan and variable speed by VFD.

In FD and PA fans, the rotor is supported in antifriction  bearings and cooled by forced

lubricating oil. A thrust bearing is provided to absorb axial loads. Thermometers (RTD &

TI ) are provided in the bearing housing for temperature monitoring.

In ID Fan, the bearings are while metal sleeve type with forced oil lubrication. Fixed bearing

near drive end is designed to absorb the Axial forces. Thermometers are provided in the b

earing housing for temperature monitoring.

Respective O & M manuals to be referred for typical drawing of each fan.

Common Facilities Required for Fans

Safety Rules clearance certificate to be signed at site by all concerned engineers

before commissioning of the fans.
 

It is proposed to commission the fans as per the following proposals.

Oil flushing of lube-oil system is completed in all respect and fresh oil has been filled in the tank.(****)

 (***)- Presently using electronic centrifuge flushing oil can be cleaned up to required

parameter and can be reused as fresh oil. 

Trial run of H.T. Motor carried out for  8 Hrs as per agreed protocol.

Auxiliary cooling water line connected ,flushed with all instrumentation and ready for use.

LT /HT Power supply available and Minimum protection is tested and ready.

Availability of lighting, communication facility at the test area.

 Availability of portable fire extinguishers

Servo control mechanism / VFD system / Hydraulic coupling commissioned and calibrated.

Instruments for Pressure ,Temperature , Blade Pitch Position etc are commissioned and put

in place.

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