TURBINE DRIVEN BOILER FEED PUMP COMMNG PART-III ABC OF THERMAL POWER PLANT

Commissioning of Governing System of BFP Turbine

Check that the oil lines from governing rack to governing elements and at the governing rack are as per drawing with proper slope.

Ensure main and auxiliary control valves lift reference indicator is fixed and set to zero position.

Check the damping valve in HP and LP secondary oil lines are kept open by few turns.

Check the filter elements at the control rack of the duplex filter are clean and healthy.

Ensure emergency stop valve open / close limit switches mounted and wired.

Switch off the supply to the following solenoids.

a)         Trip solenoid valves,

b)         Remote reset of trip lever solenoid valve.

c)         Power supply off to the I/H convertors.

Ensure lube oil pump in service and charge governing oil to the governing system.

Ensure all pressure switches and pressure gauges in governing rack are charged and their drain valves are closed.

Reset the turbine locally and ensure following:

a)         Trip oil pressure more than 5.0 kg/cm2.

b)         Stop and control valves in closed condition.

c)         HP and LP secondary oil pressures less than 1.0 kg/cm2

Ensure oil temperature of 45-50 deg C during governing system adjustment.

Opening / closing of emergency stop valve.

Ensure power supply for solenoids (It will be normally in deenergised condition)

Ensure no steam available ahead of ESV and live steam isolating valve in closed condition.

Give open command to ESV and observe the following sequential  operation of solenoid valves .

a)         Both solenoids energises. Oil pressure above piston more than 5 kg/cm2 and below disc 0 kg/cm2 

b)         Solenoid  deenergises oil pressure above piston more than 5 kg/cm2  and below disc more than 5 kg/cm2  .

c)         Solenoid   also deenergises. Oil from above piston starts draining gradually through orifice and ESV opens.

d)         When ESV full open oil pressure below disc is more than 5 kg/cm2  and above piston ‘0’ kg/cm2 . Adjust open limit switch and check feed back available in control room.

By tripping turbine trip lever, ensure tripping/closing of ESV. Check close feed back available in control room.

Reset the turbine from remote by energising corresponding  solenoid  Ensure the same solenoid gets automatically deenergised when trip oil pressure raises more than 4.5 kg/cm2  through pressure switch.

Switch on power supply to HP and LP I/H convertors.

Give 4 mA current to HP I/H convertor with external source or through governor panel.

Ensure HP sec. Oil pressure of 1.5 kg/cm2. If not set the pressure to 1.5 kg/cm2  by adjusting potentiometer in I/H convertor.        

Check that the control valve servomotor pilot is rotating freely and having a slight up and down movements.

Check the main control valve servomotor is just opened, by 0.2 mm. The start of opening can be measured by fixing dial guage on servomotor.

If the start of opening is not correct adjust the adjustment screw of the pilot slide to achieve the start of opening.

Raise the current to I/H conventor to 20 mA. Observe HP sec oil pressure increases to 4.5 kg/cm2 . If not adjust the potentiometer of I/H convertor to achieve the pressure.

Check the main control valve servomotor lift is maximum. If the lift is not correct adjust feed back angle to obtain the full lift.

Check and adjust auxiliary control valve servomotor similarly as done for main control valve .

Record control valve characteristics (from 4 mA to 20 mA to I/H convertor)

1.         Current  mA Vs HP sec oil pressure Vs main control valve lift.

2.         Current to LP I/H convertor mA Vs LP sec-oil pressure Vs Auxiliary control valve lift.

Compare the characteristics and ensure these are in line with governing adjustment diagram/ shop floor test protocol.

Operate the tester for ESV and ensure partial closing of ESV and put back the tester in normal position, ESV opens back to full open position.

Energise the remote trip solenoid  and ensure the following.

a)         ESV closed.

b)         Main control valve is closed

c)         Auxiliary control valve is closed.

d)         Trip oil pressure is zero.

continued - PART-IV

TURBINE DRIVEN BOILER FEED PUMP COMMNG PART-II ABC OF THERMAL POWER PLANT

                                                    PART -II ( TDBFP COMMNG)

Continued from PART-I

All local and remote instrumentation for the system is complete.

Insulation of the following completed.

a)         Re-circulation line of main pump.

b)         Suction and discharge line of booster pump and main pump.

c)         Main pump and booster pump body.

Commissioning of valves related to the feed pump system are completed. (Suction isolating valve, discharge isolating valve, re-circulation valve and motor cooling water isolating valve etc)

All instrumentation local ,remote completed , and also Interlock and protection system simulation checking completed.

Commissioning of Oil System and Turning Gear Operation of BFP Turbine( BHEL make)

Oil flushing of lubrication oil system completed and lines  are normalized. ( note:- temporary pipes ,bends etc removed kept it for use of next pump oil flushing next pump 

Turbine is disconnected from gear box and main pump and kept in isolation.

Completion of lube oil inlet lines with throttles / orifices pressure gauges and return lines with view glass and temperature gauges.

Check healthiness of bearing metal temperature detectors of turbine, main pump and booster pump. ( In general we use Platinum RTD ( 100 ohm 0 degree or Ni-Cr-Ni thermo-couple 4.12mv/100 deg increase.) therefore as per visual check with a meter all will show room temperature.

Ensure proper mounting of speed probes and turbine supervisory probes ( axial shift , thermal expansion , overall thermal expansion with dowelling after necessary calibration.)

Ensure the completion of Jacking Oil of lines with throttle valve, NRV ( non return valve) and isolating valve.

Ensure healthy filter elements in MOP, AOP, EOP suction lines, MOP, AOP and EOP discharge lines and JOP suction line.

Oil is filled in MOT through centrifuge to adequate level. ( Servo prime 46 or equivalent from any other company.)

Keep open the vents of lube oil coolers and filter to purge air from the system.

Keep the changeover valve of lube oil cooler and filter in such a way that only one cooler ad filter will be in service.

Drains of lube oil coolers, filters should be in closed position to avoid any loss of oil..

Start one of the oil vapour fans with its suction valve open condition.

Start one of the lube oil pumps ensuring flow through recirculation.

Adjust lube oil header pressure control valve to maintain lube oil pressure of 2.5 kg/cm2 ( approx) after control station.

Adjust lube oil discharge pressure to 10.0kg/cm2(approx) by setting re-circulation control valve.

By operating isolating valve of recirculation control valve, check the safety valve popping and adjust if required.

Check the lube oil flow to the bearing of turbine, main pump and booster pump.

Monitor lube oil duplex filter DP.

Stop the pump and start other lube oil pump and check its discharge safety valve popping and adjust if required.

Stop running pump and start DC EOP. ( Emergency Oil Pump).

Ensure adequate lube oil pressure and flow. Keep DC EOP running for 4 hours to check the healthiness of the system with EOP.

Stop DC EOP and keep lube oil pump in service .

Charge the suction line of JOP from lube oil header.

Start JOP and adjust the safety relief valve to 110 kg/cm2.

Adjust pressure regulating valve to 100 kg/cm2

Adjust the throttle valves in Jacking oil supply to front and rear journal bearings such that the rotor lifts around 0.05 to 0.1 mm. Stop JOP and start again. Check and record the Jacking oil pressures and rotor lifts in the turbine front and rear journal bearings.

Check and ensure the freeness of rotor for rotation by engaging hand barring lever and then stop JOP.

Ensure auto operation of AOP I, AOP II and DC EOP through corresponding pressure switches operation. ( Part of protection checking and auto operation) . Cut in of DCEOP in emergency is most important aspect.

Keep AOP  I in service, AOP  II and EOP on auto.

Oil temperature is  above  40 degree C .

Charge cooling water to cooler and ensure oil temperature control valve auto operation.

Start JOP and open turning gear valve.          

Once the rotor picks up speed, turning gear valve may be closed for checking the rotor for possible rubbing at end gland seals, heat shields, oil gaurds etc., while coasting down.

If the rotor is found smooth till it comes to standstill, turning gear valve may be opened full.

Turning gear speed of around 200 RPM and smooth running.

Observe and record bearing metal temperatures, vibrations, eccentricity etc.and run for 8 hours. stop turning gear and observe coasting down etc,

MOP = MAIN OIL PUMP 

AOP =  AUXILIARY OIL PUMP

JOP  =  JACKING OIL PUMP

DC EOP = EMERGENCY OIL PUMP ( DIRECT CURRENT) 

CONTINUED TO PART -III

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TURBINE DRIVEN BOILER FEED PUMP COMMNG PART-I-ABC OF THERMAL POWER PLANT

PART-I

Before starting the pre-commissioning activities of BFP ( TD – TURBINE DRIVEN)  equipments need to be individually checked for readiness upto a limit point.

Booster pump, Gearbox, Turbine, BFP and associated system are erected as per recommended drawing and readings are recorded for ready reference.

Acid cleaning and oil flushing completed for lube oil and working oil, Jacking oil and governing oil piping as per test procedure and lines are normalized. The procedure has already been discussed in my earlier blogs.

Detergent flushing of feed water suction, discharge and recirculation piping are completed and all piping normalized. These flushing is being done in parts as MDBFP comes first at initial stage that time pipelines for TDBFP may not be ready. Therefore a scheme to be made to undertake this job without interrupting the commissioning activities. This should be kept in mind. Otherwise to complete the line and do the cleaning in one go is the best.

All piping supports are loaded to the rated value and all temporary supports removed from the pipeline.

Deaerator and FST filled with Fresh DM water. FST level switches and Deaerator level switches are checked. In fact these switches are calibrated during MDBFP trial run. Rechecked during TDBFP commissioning.

Flushing of following pipe lines completed.

Cooling water lines of Booster pump and BFP (Seal Water cooler and seal body)

Balancing leak off lines of main pump.

Turbine exhaust hood spray line.

Turbovisory instruments  for turbine ( i.e expansion measurement of turbine  

Vibration , temperature ,pressure etc calibrated and installed .

Steam blowing of pipelines again in phased manner is to be completed. It is noticed that steam lines of TDBFP are not get ready during steam blowing activity of the unit. This is to be done at later date therefore a scheme of drawing steam and drain to condenser /flash tank to be made and executed as per the scheme.

Insulation of turbine and pipelines is completed.

Erection of gland steam supply piping complete. Supports, steam blowing and insulation complete.

Turbine drain piping and all steam piping drain lines are complete. For initial rolling orifice plates in drains are removed to avoid chocking.

Turbine exhaust piping complete with supports upto condensor.

Bursting diaphragm is erected and healty.

Gland leak off piping erection complete to condensor (including supports and insulation)

All motorized valves related to turbine including live steam isolation valves, turbine drain valves are commissioned.

Gland steam pressure controller commissioned available for operation.

Governing valves erected and protection devices like overspeed trip device, hand trip device are mounted properly.

Feed water suction strainer erected in position in clean condition with DP indicator commissioned.

Instrument and service air line for the Feed pump system erected and the air is made available for operation.

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CONTINUED TO PART-II

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)

BOILER FEED PUMP ERECTION AND COMMISSIONING FINAL PART-ABC OF THERMAL POWER PLANT

TYPICAL INTERLOCK & PROTECTION REQUIRED FOR BFP COMMISSIONING

Ensure completion, installation and readiness of all instrumentation works, as per instrumentation

schedule, on BFP/ Booster pump/ Motor/ Hydraulic coupling/ de- aerator.                         

                                               

Calibration, setting and testing of primary instruments.                

                  

 Pressure gauges/ switches/ transmitters calibration and installation and wiring up to JB.                              

 Temp gauges/ switches/ transmitters calibration and installation up to JB.                           

                  

 Level gauges/ switches/ transmitters.                  

               

Limit switches.                 

Installation of JBs, cabling & termination in local and control room.                          

Readiness of control supply to Panels:                                                                  

Availability of LT & HT supplies   and readiness of electrical protection instruments.         

Readiness of mechanical system.                                                                                            

 Oil system                         

 De=aerator                       

Compressed air system.               ( Compressed air is required for pneumatic valve operation.     

Charging and testing of panels.                 

Commissioning of motorized  valves,  actuators & pneumatic re circulation valve.                              

Checking of Interlocks, protections & Alarms:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    .                              

                (i)   Calibration of speed control device like scope tube /thyrister control etc                       

                (ii)  Oil pressure low                       

                (iii)  Suction valve open                                

                (iv)  De-aerator level low                             

                (v)   Feed pump suction/ discharge temperature high.                   

                (vi)  Balancing leak off pressure. high                     

                (vii)  Re circulation valve open                    

                viii)  Bearings vibrations high (wherever provided)                          

                ix)   Remote/ local tripping          

                TRIAL RUN OF HYDRAULIC COUPLING

               

               

Readiness of lubrication oil & working oil coolers and availability of cooling water.

Charge lubrication  oil and working oil coolers.

Checking of HC interlocks & protections

Ensure alignment of Hydraulic coupling with BFP motor.

Ensure proper  earthing of Hydraulic coupling.

Check oil level in hydraulic coupling sump.

Start AOP and monitor lubrication oil header pressure.

Start trial run of Hydraulic coupling.

Check regulating oil pressure and set, if required.

Monitor all parameters of hydraulic coupling; Gauges are available /mounted on the equipment

                   I.   Lubrication oil and Regulating oil pressure.

                   ii.   Motor current.

                   iii.  Hydraulic coupling bearings temperatures.

                   iv.  Lubrication oil temp at L. O. cooler inlet and outlet.

                   v.   Working oil temp at W.O. cooler inlet and outlet.

                   vi.  Motor winding temps.        

TRIAL RUN OF BFP

               

               

1      Ensure free rotation of BFP by hand before coupling.                                                                                                                               

2      Ensure completion of alignment:                                                                                                                              

                     I.    Motor & Booster pump

                     ii.    Motor & hydraulic coupling.

                     iii.   Hydraulic coupling & BFP

Special attention to be given on pipe line final connection.Pipes to be ensured as free body  through

hanger adjustment.  No tension on pipes is permitted otherwise alignment  will be disturbed.

3              Flushing of mechanical seal cooling water lines for BP as well as BFP & Mechanical seal water

cooler cooling water lines.

4              Optimisation of oil flow through bearings by using orifice plates

5              Running of AOP

6              Charging of all system:  

                (i)  Lubrication oil/ working oil coolers

                (ii)  Seal water coolers

                (iii) Suction valve opening 

                (iv)  Re circulation valve (Isolation  valve) opening

                (v)  Charging of C&I local panels

7              Fill de=aerator and maintain normal level.  

 8              Interlocks & protections checking.

9              Start BFP.

10           Monitor all parameters of BFP and motor;

                    I.    Current

                    ii.    BFP suction pressure.

                    iii.   BFP discharge pressure.

                    iv.   Balancing leak off pressure.

                    v.    De-aerator level.

                    vi.   BFP suction/ discharge Differential Temperature.

                    vii.   Lubrication oil/ working oil pressures and temps.

                    viii.  Booster pump/ BFP/ Motor/ Hydraulic Coupling bearings and drain oil temps. 

                    ix.   Cooling water temps.

                    x.    Seal water/ seal water coolers temps.

                    xi.    Motor winding temps.

                    xii.   Bearing vibrations.