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

FINAL COMMISSIONING OF BOILER FEED PUMP ( mdbfp)

Till my last dispatch we have discussed erection and commissioning of Boiler Feed pump including oil flushing of lubrication oil lines ,acid cleaning of the same , hydraulic test of coolers and other integral pipelines. Now we will discuss about Boiler feed pump commissioning as a whole. BFP( MDBFP) is one of the first major equipment need to be commissioned before Boiler light up.

Commissioning includes checking of following activities completion as per drawing and quality plan.

1              Erection completion of feed water lines.

2              Instrumentation stub parts completion.

3              Completion of Alkali/ detergent flushing of feed water system, as well as condensate system and heaters drip system.

4              Cleaning and normalisation of deaerator and feed lines

5              Checking & setting of hangers and supports of feed water lines including BFP suction lines, recirculation lines.

6              Deaerator filling with DM water.

7              Final flushing of the suction lines of Booster Pump & BFP .

Readiness of cooling water system

1 Erection completion of cooling water lines of,                                                                                                                                                                                                                                                                                                                                                                                                    

BFP Motor

                Lubrication  oil coolers and working oil coolers

                Seal water coolers of BP & BFP

2              Commissioning  of the motorised actuators of motor cooling water valve..

3              Checking & setting of hangers & supports of CW lines of CW system and motor cooler.

4              Availability & readiness of cooling water/ system.

5              Flushing of all cooling water lines of CW system and motor cooler.

Completion of  ACW  system and heat exchangers ,Pumps, tanks  ,pipelines with instrumentation.

Electrical and C&I work completion  of Feed Pump , Feed station , control valves ,actuators etc.

1              Meggering of BFP motor

2              Availability of HT supply

3              Ensure proper earthing of BFP motor and instruments panel..

4              Completion of instrumentation (bearing oil press & temp) impulse piping and mounting of

press/ temp gauges, and winding, temp RTDs

5              Filling of Hydraulic coupling sump with fresh oil after oil flushing & cleaning of sump

6              Oil pressure optimization  at motor bearings.

7              Ensure de-coupling of motor with booster pump and hyd. Coupling.

8              Ensure free rotation of motor by hand.

9              Checking of BFP motor protections and CW valve interlock.

10           Charging of CW system and lubrication  oil cooler.

11           Bumping of motor and checking DOR

12           Trial run of BFP motor

13           Monitoring of motor parameters.

                   I.    Motor current and voltage.

                   ii.   Motor winding temperatures.

                   iii.  Bearing temperatures.

Continued to concluding part

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

Oil pipelines are reassembled after acid cleaning is over.

Oil tank and duplex filters are clean.

Oil tank is filled to the required level with recommended oil. Oil should be filled through filter

/centrifuge. Oils of different quality / make should never be mixed. Follow OEM

Recommendation.

Oil pipelines are disconnected from the bearings. The bearings are bypassed by temporarily

interconnecting the inlet and outlet lines of bearings using temporary loops.

Oil lines are properly supported and all temporary supports are cut and removed.

Temporary line filter of stainless steel mesh is provided in the return line before entry to the tank to

avoid entry of dirt into MOT of Hydraulic coupling.

Working oil lines to working oil coolers disconnected at hydraulic coupling end and temporary loops

made as shown in the flushing scheme.

Temporary connections, preferably of transparent hose which can withstand temperature as high as

80⁰ C, are made across the bearings.

Portable centrifuge / electrostatic filtration unit is connected to the MOT of the Hydraulic coupling.

Suction of the unit is connected to the drain of MOT of Hydraulic coupling through suitable hose and  the 

discharge is left inside the Hydraulic Coupling tank through inspection cover.

Required instruments such as pressure and temperature gauges are calibrated and mounted in the

system.

Temperature of 65-75⁰C to be reached during oil flushing through centrifuge heaters.

With MOT of Hydraulic tank already filled with recommended oil, AOP is bump started to check the

direction of rotation of the pump.

After ensuring correct direction of rotation the AOP is run continuously and the system is filled

gradually.

Oil level in the tank is watched till oil flow is established throughout the system. Oil is topped up, if

required.

The system is checked for oil leakages and the leakages, if any, are attended.

Temperature of oil is raised to 65-70 deg Celsius by using the heaters of centrifuge or by external

heaters.

After attaining the elevated oil temperature, heater is switched off and cooling water is admitted in

the cooler to suddenly bring down the oil temperature to get an effect of thermal shock. Oil pipelines

are also tapped with wooden hammers during the period of thermal shock.

Oil temperature is again raised and thermal shock is given. Thermal shocks are repeated till oil

flushing is declared complete as per completion criteria.

The working oil and lub oil circuits are flushed separately by making suitable temporary connections.

Flushing of lub oil circuit is done in sub stages by grouping lines of two to three bearings ( to be

decided at site ) by suitable isolation of lub oil supply lines to other bearings to have adequate

velocity in the pipelines for effective flushing .

The filters are cleaned whenever there is an increase in differential pressure across the filter beyond

0.5 kg/cm² over the normal value. 

Periodicity of oil sampling and filter inspection is mutually decided at site.

Oil flushing of oil lines bypassing the bearings is declared complete based on completion criteria.

Hydraulic test of the pipelines is carried out at a pressure 1.5 times the working pressure with the

help of an external pump or the AOP itself. There should be NO leakage.

Temporary bypass connections / blanks / dummies / are removed and the pipeline connections with

the bearings are normalized.

Flushing of lub oil circuit with bearings included in the flushing circuit is started.

Flushing through bearings is declared complete based on completion criteria.

The oil used for flushing is drained and kept in safe custody. This oil can be used for flushing in

other units if the oil quality is found suitable. While using this used oil for flushing in other units,

filling should be done through centrifuge.

All the bearings are inspected and cleaned.

Fresh oil is filled in the system. Oil pump is run, flow through each bearing adjusted and flow of

return oil through each bearing ensured.

COMPLETION CRITERIA The flushed components are considered clean when the DP across the filter stabilizes and does not rise more than 0.2 to 0.3 ksc over the normal value after eight hours of continuous flushing. Also there should be NO deposition of hard particles in oil filters. Mechanical impurities ( through 0.45 micron filter ) and moisture content in the sample collected from flushing oil should be each less than 100 ppm in three consecutive samples taken at intervals of four hours. Continued to last part BFP commissioning

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

Acid cleaning and oil flushing of LUBRICATION oil line of BFP

OBJECTIVE:-  To obtain clean lubrication oil and dirt free lubrication  oil tank at Hydraulic coupling.

The pipelines shall be disassembled from flange joints after initial layout and welding completion.

Each pipeline shall be acid cleaned by soaking method.

After neutralization and passivation of each pipeline, the pipelines shall be reassembled for oil

Flushing .

Oil flushing for working oil and lub. oil circuits shall be done separately. Necessary temporary

connections shall be done for this purpose. Necessary temporary connection can be done during

erection stage and after flushing temporary connection can be removed and can be used in other

units.

During oil flushing of lub. oil circuit bearings shall be initially kept bypassed using temporary loops.

Subsequently bearings shall also be included in the flushing circuit.

After completion of oil flushing the oil used for flushing shall be drained. Bearings shall be inspected

and cleaned.

Recommended fresh oil shall be topped up in the tank as per OEM manual.

Following inputs required for acid cleaning and subsequent oil flushing.

Availability of DM Water and Service Water.

Availability of following chemicals:

Hydrochloric Acid 30% Min ( IS : 265 : 1993 )

Rodine 213 SPL as inhibitor

Sodium Nitrite

Liquor Ammonia 25% ( IS : 799 – 1990 )

Lime Powder ( IS : 1540 : 1990 -Part II )

Availability of adequate number of wooden plugs

Availability of Service Air

Availability of required grade and quantity of lub. oil

Availability of L.T. Power Supply

Availability of Lab service for efficiency test of inhibitor and for testing of Moisture & Mechanical

impurities in oil .

Availability of adequate lighting and telephone facility in lub oil flushing area

Availability of manpower with tools and consumables like cloth etc

Availability of portable centrifuge / Electrostatic Oil Filtration unit.

Precaution to be taken for fire safety .

Requirement of cooling water if thermal shock  is necessary.

ACID CLEANING ( Soaking method ) -BHEL

The dissembled pipeline pieces are filled with DM water and flushed few times. It is ensured that

there is no leakage through the wooden plug provided at one end of the pipe.

5% Hydrochloric acid with 0.2% inhibitor ( Rodine 213 SPL ) is filled in the pipes. Efficiency test of

the inhibitor is done prior to its use as per NACE procedure.

The solution is allowed to soak in the pipes for 4 (four) hours and then drained in a safe place and

neutralized. This is then disposed of with plenty of service water.

The pipes are flushed with DM water for 5 to 10 minutes.

The pipes are again filled with 2.0% Sodium Nitrite & 5.0% liquor ammonia solution. The solution is 

allowed to soak for 30 minutes and then drained.

The pipe is rinsed with DM water till pH of discharged water is between 6.5 and 7.5.

The internal surface of the pipes is dried with dry compressed air.

The lines are filled with lub. oil and uniform oil film is achieved through out the internal surface of

the pipe. The ends of the pipes are kept properly capped till the pipes are reassembled.

XXX- All the operation is done at water treatment plant because acid handling facilities will be better

There. If that facilities are not there then temporary facility to be developed at site as acid mixture

Cannot be discharged in the drain.

continued to part -v


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

PART –III

Continuation from PART-II

Placement of pump pedestal  & grouting with ready mix grout.

Mounting of pump on the pedestal

Mounting of booster pump & alignment with BFP motor

BP/BFPs bearings checking, clearance setting and box-up

Mechanical seals checking/inspection and mounting of BP/BFP (Both for DE/NDE)

Alignment of pump with hydraulic coupling complete.

Completion of mechanical  seal cooling water lines, Auxiliary cooling water line  ,placement of coolers after Hydraulic testing.

Installation of seal water cooler.

Following erection checks to be carried  during the process of erection.

Position  & elevation of foundation (elevation within+5mm/-10mm). Check that depth and verticality of each pocket is OK.

Distance from fixed reference axis e.g. A-row, B-row Columns. (1mm / metre,  5mm Max.)

Marking of equivalent axes on foundation.

Blue matching of the packers to have a minimum of 80% of contact area between each other and with bottom of foundation frame.

Ensure that machined surfaces and surfaces exposed to grouting in foundation frame    

    

are free from paint, rust, scale.

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.

Measure distance between  coupling half faces of

               -Booster Pump and motor

               -Motor and Hydraulic coupling

              - Hydraulic coupling and Main Pump.

Alignment (lateral and angular) between Booster pump & Motor, Motor & Hydraulic coupling,

             

Hydraulic coupling & BFP. Measure distances between coupling flanges.

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

Joints. (i.e  Booster Pump suction and discharge and Main pump suction and discharge).

Distances and alignment readings between coupling half faces of BFP & Hydraulic coupling,

Hydraulic coupling & motor, Motor & Booster pump after completing pipe connections.              

We have till date described only MDBFP for TD BFP except prime mover every thing will be same. Next Part i.e PART IV we will discuss about TDBFP in brief.

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

        Typical  data of BHEL make Boiler Feed Pump and its motor is given below briefly.

A.  Booster  Feed Pump

a. Direction of rotation                                         Anticlockwise  (viewed on NDE)

b. Suction temperature ; C                                                           161.8 deg c

c. Suction pressure                                                                          8.43 ata

d.Discharge Pressure                                                                     25.65 ata

e.Flow rate, m³/hr                                                                          1143.7 

f. Efficiency  %                                                                                   81

g.Speed rev/m                                                                                  1494

h.Power absorbed, KW                                                                  662

i.  Driver/Pump flexible coupling                                            Euroflex, India

B. Boiler Feed Pump

a.  Suction Flow                                                                                894960 kg/hr

b. Suction pressure                                                                         26.85  ata

c.  Discharge Pressure                                                                    209.19 ata

d.  Speed rpm                                                                                    5465

e. Power consumption KW                                                          6233

f. Efficiency                                                                                        81%

g.  Normal recirculation flow                                                       250  m³/hr.    

C. Hydraulic  Coupling

a.  Manufacturer                                                                               VOITH

c.  Rotation seen in direction of power flow                         CCW

              

d.  Motor Speed rpm                                                                      1494

f.  Primary Speed ‘rpm’                                                                 5089

g.  Full load slip                                                                                 2.24%

i. Max. output speed ‘rpm’                                                          5820 

k. Oil tank filling                                                                             2500 litres.

Auxiliary  oil Pump

     Power                                                                                         30 KW

     Rated speed                                                                            2945 rpm

     Voltage                                                                                     415 V

     Frequency                                                                                 50 Hz

     Protection                                                                                  IP 55

The details above are for 500 MW units . It is prudent to verify with OEM ( original equipment Manufacturer specification during working .

Activities related to Boiler feed pump erection and commissioning (MD)

Preparation of foundation for  PUMP ,MOTOR and HYDRAULIC  COUPLING ( i.e checking of center line with respect to known co-ordinates , checking of  pocket dimensions , Level of the foundations etc .Also check the foundation of coolers .Also record the data in protocol for further decision

Placement of motor and hydraulic coupling on the foundation .

Grouting of motors & HC with ready mix grout ( conbextra GP 2 , SIKKA etc)

Motor winding RTDs( Resistence Temperature detector), Instrumentation checking completion  

Motor cooling waters lines completion

Alignment of motor & hydraulic. Coupling

Hydraulic coupling instrumentation completion

Mounting of scoop tube actuator

Checking and clearance setting of motor bearings.

continued to PART _III

TIPS ON CONDENSER ERECTION AND START BOILER FEED PUMP ERECTION --PART -I

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order since then. In between I had an operation on my left shoulder for infected cyst removal . I am still 

recovering from it. 

condenser.

-The joining plates between the water chambers should be welded and checked before lowering of condenser intervals.

-The corners of the neck joint with LP turbine should be checked to ensure completeness.

-The welding of the stiffeners with the main tube plate should be done only after welding  of all support plates with the shell and stiffness has been completed.

-Welding sequence should be reversed for every layers of welding.

-During pre-assembly of bottom plates / side walls & dome walls it is advisable to put a packer below the joint so that during welding the plates straighten out.

-Not more than four welders should be deployed during the welding of the internals. Adequate supervision should be exercised to ensure proper welding sequence.

-It is desirable that after 50% of the welding of internals has been completed the alignment of the tube plates is rechecked. Subsequent welding sequence should be decided based on the observation made.

-During tubing in case the tube is not going freely the holes of the tubes support plates may be reamed suitably.

HYDRAULIC TEST OF WATER BOXES

The condensers are subjected to a hydraulic pressure test on the cw side. For this purpose, the cw inlet and outlet pipes must be blanked using suitable hydro-test flanges and the manholes using the original covers. The water box covers must be mounted ready for operation and a protective coating must have been applied to the water boxes.

The hydro-test can also be done by closing the butterfly valves in the inlet and outlet of condensers. This apart from also ensuring the tightness of B.F. valves and expansion joints, reduce the time cycle as the temporary test flanges need not be erected.

After the hydro test, drain the cw.

BOILER FEED PUMP

There are  3x50% Boiler feed pumps in a major power station  i.e. 500MW and above  with 02 number  Turbine Driven and one number motor driven. Motor driven pump is located in between operating floor and zero meter floor (8.5m) . Turbine driven pumps are located on operating floor ( near B row column). Motor (10 MW  approx) squirrel cage  constant speed  with Hydraulic coupling for variable speed is coupled in between main pump and booster pump. Around 10 MW capacity single cylinder variable speed turbine  is used turbo driven BFP.

Details of specification will be available with OEM’s O&M manual and erection manual. I will give a very short description of these pumps which may get overlooked during erection and commissioning.

- Main pump will have butt weld discharge connection. Suction connection can be butt weld or  flanged connection.

- Booster pump will have flanged connection both in suction and discharge.

-One pump can handle approx 65% of  unit rated  load flow and head  .

-Trip speed of steam turbine will be 10% above the design speed of boiler feed pump.

-Minimum recirculation of booster pump and main pump is around 25% of design flow.

- All pumps and accessories of MDBFP and TDBFPs are interchangeable.

- Fabricated base plates are used for booster pump , gear box ,main pump, hydraulic coupling  etc

- During parallel operation of MDBFP and TDBFP the difference of flow in any one pump should be less than 5%.

continued to part -ii
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CONDENSER - AUXILIARIES OF STG SETS CONCLUDING PART -ABC OF THERMAL POWER PLANT

   Following checks are made  during the course of erection of condenser.

- Welding checks as per welding manual  consist of welder test, consumables selection and processes as per OEM. This is very relevant as condenser is having huge quantity of welding jobs at different stages of erection. Therefore all the details of welding specially sequence of welding is very important or there will be distortion in forming the box. OEM specify the sequence in their manual.

- Level Position of hot well w.r.t. Transverse and longitudinal axes of turbine as well as front & rear water box ends of condenser and Bottom plate openings and alignment of bottom plates w.r.t. to Turbine axis.

- Level and alignment of bottom plate relative to turbine axes within  ½  degree slope.

-Sag checking of tube plates and also flange checking of water box and chamber.

-Length in between Tube Plate at locations, covering full area of tube plates.

-Distance between sidewalls and height & verticality of Sidewalls.
- Position of Support Plates. Hole alignment of tube plates and tube support plates.
- Verticality of hinge door assembly. Tolerence should be as per drawing.
- Verticality of hinge door assembly.
Location of spring units and setting of condenser slope.
Alignment of L.P Cylinder opening with Condenser.
-Dimensions of the dome walls from turbine longitudinal and transverse axes.
-Nozzle orientations as per drawing.
-Orientation of condensate spray nozzle.
-Check position, level and alignment of heater.
- Mock up test on separate tube plate including air leak test on mock up set up.
- Setting of expander for required tube thinning as per the procedure given by OEM.

  Condenser Tubing under progress

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