TURBINE DRIVEN BOILER FEED PUMP -ABC OF THERMAL POWER PLANT

Check clearances of Thrust bearing of BFP and Booster Pump-Feller Gauge / Dial Gauge.

Ensure specified clearances between guide slips & key (at the bottom of pump casing), and then 

welding of key block on base frame-Vernier/ Tape.

Hydraulic testing of coolers (waterside) - Pressure Gauge. should be calibrated

Note: Coolers if already hydro tested at manufacturing works and test certificates available, need not be hydro tested at site.

Completion of welding and NDE of welds of following lines:

a.   

       a       BFP discharge line.

.   b. BFP suction line.

c

.    c. Booster Pump Suction line.

d. 

     d.  Booster Pump discharge line

Ensure pre heat treatment and post-weld heat-treatment of weld

Ensure that the entire pipeline is supported by permanent supports before making the last four joints 

of  BOOSTER PUMP & MAIN PUMP suction and discharge.

Ensure that the piping doesn’t exercise any pull on pump nozzles. This is extremely important in the 

case of BFP suction & discharge, which are welded joints). This is true for any nay major or minor 

rotating machine . That means final connection to be done when  piping is in free float. This can be 

achieved  if all the pipelines are erected as per drawing and permanent supports are adjusted as per 

drawing value. In fact in BFP we check that pipe lines can be moved by hand only without any 

difficulty. Same philosophy is applicable for BOOSTER PUMP also . However BOOSTER PUMP 

connection is through fastners only therefore can be manipulated easily so not critical as MAIN 

PUMP. Instances are available that after final connection alignment was disturbed so much that 

pipeline was cut and re-weld after necessary correction. This area is major bone of contention 

between piping engineer and pump engineer.

Distances and alignment readings between coupling half faces of Booster Pump & Gear box, Gear

box & Drive turbine shaft, Drive turbine shaft & BFP after completing pipe connections.

Welding of key block on base frame after ensuring specified clearance between guide slips & key (At

the bottom of pump casing.

Small bore pipeline connection of oil lines of drive turbine , Cooler lines oil and water , Sealing lines

of pumps  Govering system installation and other steam lines to be connected and completed. Final

connection to be done after ensuring , oil flushing ,steam blowing ,water flushing ,chemical cleaning

etc is completed as per requirement under laid down procedure .Any short cuts will bring problems

afterwards .That is during stabilisation of units.

Necessary instrumentation on oil tank ,oil lines , bearings ,gear boxes and pumps are calibrated and

installed  as per drawing. Specially Turbovisory instruments for drive turbine , governing control

system are installed carefully.

PROCESS FOR PRE COMMISSIONING AND COMMISSIONING 

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continued to part -iii

TURBINE DRIVEN BOILER FEED PUMP EREC. &COMMNG -ABC OF THERMAL POWER PLANT

As  stated in earlier posts there are three Boiler Feed Pumps (3x 50%) in a thermal power station of 500MW and above. 2x50% turbine driven BFP ( normally working when unit is running above certain load ) and other is 1x50 % MDBFP  which usually runs during start up .

We have already explained in last few blogs about erection and commissioning of MDBFP . For TDBFP pumps are same whether it is booster pump or main pump. Instead of MOTOR driven we have variable speed turbine with disconnecting coupling both sides . In this blog we will discuss only the turbine as pumps are similar.

 Technical data of Turbine

a.  Maximum output                                         7575  KW

b.  Design rating 

        (Economical rating)                                  5732 KW

c.  Speed                                                            5275 RPM

d.  Speed range                                                  1494-5750 RPM

e.  Initial Steam Pressure                                   6.33 ata.

f. Initial steam Temperature                              289.6 0 C.

g.  Exhaust pressure                                           0.1064 ata.

Oil System

a.  Lube oil pump                                              2 Nos

b.  Emergency Oil pump                                   1 No.

c.  Jacking Oil Pump                                         1 No.

d. Oil vapour extractor fans                              2 Nos

PROCESS  : ERECTION CHECK

Foundation checking of elevation ,plan that is different pocket holes and other measurable items as per given approved drawing . This the protocol for taking foundation from civil vendor for erection  purpose .(elevation within+5mm/-10mm). 

Check that depth and verticality of each pocket is OK. Checking to be done by water level /dumpy level/ total station.

Distance from fixed reference axis e.g. A-row, B-row Columns.  (1mm / metre,  5mm Max.)- Establishing centre line as given in the drawing by putting distances from fixed point . This can be done by measuring tapes or by total stations .

Marking of equivalent axes on foundation. Plumb Bob / total station.

Fitting of half couplings to all equipment after ensuring corresponding fits.  For taper coupling, ensure around 80% contact between shaft & coupling.

Blue matching the top surface of foundation frame with corresponding bottom surfaces of equipment with around 80% contact.

Positioning and alignment of all equipment on the foundation. Measure distance between coupling half faces of following equipments by Vernier / Micrometer / Tape

            Booster Pump and Gearbox

            Gearbox and Drive turbine

            Drive turbine and BFP.

Grouting of Foundation Bolts. Check that nut has full contact with foundation frame after tightening.

Leveling and alignment of equipment  by jack bolts (within 0.1 mm / M). Dumpy / Precision Spirit level) and different thickness packer plates.

Foundation frame grouting. Now a days grouting is done with ready mix concrete of 25kg bags main supplier is ACC, PAGEL ,FOXROC etc. This is a specialised job it is advisable to do concreting in presence of suppliers representative to avoid any complicacy afterwards. Please insist on test certificate and cube testing on one day and three day sample. This may delay the process however by passing any of the test may complicate the situation afterwards. Major checks of equipment are already told during my earlier blog. Please go through it.

Alignment (lateral and angular) between booster pump & gearbox, gearbox & Drive turbine shaft, Drive turbine shaft & BFP, Measure distances between coupling flanges. This is done without any pipe connection ( water line ,oil line and steam line ). This is pre final reading and after doing final connection final reading to be taken. However during course of erection this reading is checked to find the effect of connection. Dial Gauge/Micrometer.

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Continued  to part –ii ( TDBFP)