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Power Sector Western Region Technology Day 11th May 200

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Title: Power Sector Western Region Technology Day 11th May 200


1
Power Sector Western Region
Technology Day
11th May 2009
2
Power Sector Western Region
TECHNOLOGICAL TOOLS
3
Power Sector Western Region
Use of Electrical Torque wrench for
Tightening Boiler Structure Bolts At 1 x 500 MW
Khaperkheda
4
Cycle time reduction in tightening boiler
structure bolts
  • Background
  • At boiler erection site thousands of BOLTED
    JOINTS are to be tightened MANUALLY using DE
    Spanners for snug tightening Torque tightening
    by trip torque type long handle torque spanner.
  • The process of bolting arrangement consumes
    enormous time for achieving desired results,
    including uniform tightening ensuring a
    designed torque value.
  • This process was identified for taking up
    Improvement project because of the following
  • being repetitive in nature
  • time consuming
  • labour intensive
  • having substantial amount of preparatory work to
    be done before the starting actual process (set
    up time)
  • high level of risk involved (some locations for
    actual work place are above 80 meter above ground
    level are to be performed on temporarily
    erected scaffoldings

5
Cycle time reduction in tightening boiler
structure bolts
  • Objective
  • Reduction in time taken for complete bolting
    arrangement necessary for a 500 MW Boiler
    erection (at Khaperkheda site about 40, 000 no.
    M24 Bolts of lengths 70 160 mm are used)
  • Ensuring designed tightness of bolting
    arrangement without further need of cross
    checking by Quality representative
  • Safer working conditions for Operator

6
Cycle time reduction in tightening boiler
structure bolts
  • Evaluation of alternatives
  • 1. Pneumatic torque wrench
  • Benefits
  • Available with leading hand tool manufacturers
    like Bosch, Ingersoll Rand others.
  • Widely used in manufacturing plants (automotive
    assembly lines) where high turnover per day is
    the hour of need (but here the Operator has a
    fixed place jobs move to his operating area one
    after another).
  • These wrenches are comparatively lighter.
  • Drawbacks for us
  • Difficulties in ensuring dry air to the wrench in
    all weather conditions
  • Maintaining desired air pressure at a long
    distance through a compressor
  • Requirement of supports since length of air pipes
    may extend up to 100 meters
  • Thus making the whole arrangement very clumsy
    big.

7
Cycle time reduction in tightening boiler
structure bolts
  • Evaluation of alternatives
  • 2. Hydraulic torque wrench
  • Benefits
  • Available with leading hand tool manufacturers
  • Widely used in manufacturing plants
  • Drawbacks for us
  • Need sophisticated hydraulic equipment (difficult
    to maintain)
  • Require very good quality pressure hoses to feed
    optimum liquid pressure to the wrench limiting
    factors
  • Practically impossible to provide such facilities
    at sites

8
Cycle time reduction in tightening boiler
structure bolts
  • Evaluation of alternatives
  • 3. Electrically operated torque wrench
  • Benefits
  • Such wrenches are popular in assembly lines
    especially where job sizes are bigger operator
    has to move around the job
  • Available with leading hand tool manufacturers
  • Electrical cables are much smaller, lighter
    easily maneuverable
  • Operate at 1 phase ac supply abundantly available
    at all areas of sites

9
Cycle time reduction in tightening boiler
structure bolts
  • Electrically operated torque wrench (contd..)
  • Results of Field Trial
  • M/s Tristar Industrial Tools Pvt limited was a
    source located for making a demo at Khaperkheda
  • Trial was successfully done on 10th April 2009 at
    a height of about 10 meters on Column number 19.
  • Time taken to fully tighten bolted joint by ETW
    was about 15 seconds as against 3 to 4 minutes by
    a handle type Trip Torque Wrench
  • Substantial saving in operation time for the
    activity
  • Saving in manual effort by Operator
  • Positive assurance of Quality of bolted joint.

10
Electric wrench for tightening boiler structure
bolts
Technische Daten DEA Technical data DEA PLARAD
GERMANY Make Technische Daten DEA Technical
data DEA Our selection Type DEA 12 TLX Torque
200 1220 NM Weight 6,8 kg
11
Electric wrench tightening of boiler structure
bolts
12
Electric wrench tightening of boiler structure
bolts
13
Cycle time reduction in tightening boiler
structure bolts
  • Expected Benefits  
  • Tangible
  • Saving in Time - On average saving of about 3
    minutes per bolt
  • Saving in manpower cost
  • No need for Quality representative to ensure
    desired objective of proper tightness
  • Additional helper to hold spanner and a trip
    torque wrench, not required.
  • Intangible
  • Safety of Operating Personnel (Operators others
    assisting him) from any Accidental fall due to
    Slipping
  • Slipping / Falling of the job from temporary
    scaffolding
  • Better safety of personnel on ground from falling
    of long torque wrench etc.

14
Power Sector Western Region

Measurement of Face Run- out of IP LP Rotors by
improvised technique at site
15
Measurement of Face Run- out of IP LP Rotors
  • Normal Practice
  • Normal practice of measurement of face run-outs
    of IP LP Turbine Rotors is
  • To place them on saddle supports and rotate them
    (There is only an arc of contact between the
    saddle and the rotor).
  • A pin is made and inserted in one of the coupling
    holes.
  • A wire rope is wound around the rotor with the
    pin at one end and the crane hook of the EOT at
    the other.
  • Lifting action of the crane hook causes rotation
    of the rotor.
  • To aid in rotation of the rotor, copper sheets
    are placed in between the saddle and the rotor
    and, grease is smeared to reduce friction during
    rotation.

Contd
16
Measurement of Face Run- out of IP LP Rotors
  • Normal Practice (Contd..)
  • The normal method has few problems associated
    with it
  • It is not possible to restrict axial movement of
    the rotor in order to avoid overshooting the
    range of the dial gauge.
  • Area of contact being very small, it requires
    extreme care and control while operating the EOT,
    lest it should cause an irreparable accident and
    lead to loss to both men and material.
  • It has often been noticed that there is quite an
    error between the measurement made at shop and
    those made at site leading to avoidable loss of
    time in correspondence, summoning experts from
    MUs, etc.
  • It gives the feeling of using a very primitive
    and un-reliable method of measurement.
  • Overall, it is never like measuring the run-outs
    by anchoring the rotor on a lathe to take the
    measurements and thats exactly the cause of the
    error.

17
Measurement of Face Run- out of IP LP Rotors
  • Suggested New Method
  • A simple device is made at site using the
    following material
  • Shaft of 40mm Ø x 1000mm long 1 no.
  • Ball Bearings with Plummer block for above shaft
    2 nos.
  • Supports to anchor the Plummer blocks 2 nos.
  • Cross arm 1 no.
  • Dial Gauges for mounting to X-arm 2
    nos.

18
Measurement of Face Run- out of IP LP Rotors
Fixture developed and used
19
Measurement of Face Run- out of IP LP Rotors
  • Advantages
  • User friendly and costs only Rs.5000/- to make.
  • Does not require too much of a precision in
    machining the shaft.
  • Does away with repeated rotation of the rotor for
    every reading.
  • Reduces the risk of the rotor toppling during
    rotation by EOT crane.
  • Compares well with the values attained at works
    on a lathe.

20
Stator lifting by Strand Jack Method at 1x250MW
Unit8 TATA Trombay
  • This was the 1st time the Generator Stator has
    been lifted by Strand Jack Method in PS-WR. Also,
    this is the 1st for 250MW Stators in the whole of
    BHEL. Picture shows Stator lifted off the Blocks.

21
Stator lifting by Strand Jack Method at 1x250MW
Unit8 TATA Trombay.Contd
  • Stator lifting in progress

22
Stator lifting by Strand Jack Method at 1x250MW
Unit8 TATA Trombay.Contd
  • Stator lifted and being moved inside the A-Row of
    TG Building

23
Stator lifting by Strand Jack Method at 1x250MW
Unit8 TATA Trombay.Contd
  • Stator lifted above the bottom of TG Deck and
    ready to be moved inside for placement.

24
Stator lifting by Strand Jack Method at 1x250MW
Unit8 TATA Trombay.Contd
  • Picture shows the Strand Jack Hydraulic Control
    System

25
Stator lifting by Strand Jack Method at 1x250MW
Unit8 TATA Trombay.Contd
  • Picture shows stator in position
  • The entire operation was completed in 4 hrs from
    the start.

26
Power Sector Western Region
PORTABLE INDUCTION HEATING MACHINE
27
INDUCTION HEATING MACHINE
  • Conventionally, we at BHEL Power Sector Sites
    have been using the Induction Heating Machines of
    EDN Bangalore make. There are certain
    disadvantages of using this equipment listed
    below
  • 1. Too bulky and comes in two parts one the
    Induction Heating Equipment proper and the other,
    the operators panel. Weighs a few tonnes.
  • 2. Due to its bulk, moving the machine to
    different areas of work is an arduous task. Each
    shift of the machine is a 1 ½ days activity.
  • 3. Often, it has been seen that when the machine
    is moved from one location to the other is has
    not been in use for a few months, the next
    re-start is faced with quite a few problems. The
    reason is not known.
  • 4. Getting spares on time for the equipment is a
    big issue. This results in machines with minor
    repairs and requiring spares quarantined.
  • 5. Overall the machine is not user-friendly
  • 6. Costs around Rs. 75 Lakhs per machine

28
Induction Heating Machine -.Contd
29
Induction Heating Machine -.Contd
  • Alternatively, there are machines available in
    the market and being used by our competitors that
    is a vast improvement on the EDN Make machine and
    has the following advantages
  • 1. Very small and easily portable, thus
    rendering easy movement of the machines to
    various locations without loss of vital erection
    cycle time. Requires only a 2-3 hrs for shifting
    and re-connecting. The entire machine is as
    compact as welding transformer and is single
    modular. Weighs approx. 105Kgs.
  • 2. The connections are very simple and does not
    need expertise.
  • 3. Though imported, has a presence in the Indian
    market for the last 3 years and has been used to
    weld pipes of 94mm thick at Sipat. The machine
    can be used to thicknesses in excess of 100mm
    pipes as well. The size of MS Pipe for the
    proposed 660MW Unit with Full Flow is F660 x
    102mm.
  • 4. Costs only Rs.30 Lakhs. For every one machine
    of EDN Make, one can two of this kind.

30
Induction Heating Machine -.Contd
31
Induction Heating Machine -.Contd
32
Power Sector Western Region
Induction Heating for Opening Tightening Casing
fasteners of Steam Turbine
33
Induction Heating for opening tightening
Casing of Steam Turbine
  • Introduction
  • Casing of steam turbines are tightened together
    by using threaded fasteners of M48 to M140 size
    .
  • These fasteners referred commonly as studs and
    cap nuts have to be tightened firmly to withstand
    the high internal pressure and temperature.
  • During the tightening process, specified value of
    elongation has to be achieved so that during
    working at high temperature, the nuts will not
    slacken .
  • A recommended practice for tightening these
    fasteners is heat tightening.

34
Induction Heating for opening tightening
Casing of Steam Turbine
  • Commonly used devices for heating the fasteners
  • Electric heaters - which include heater elements,
    cables, power source /transformer of high
    capacity etc.
  • Gas heaters. This is relatively simpler method
    which uses the specially fabricated bolt heating
    devices - Gas Torches with special nozzles, and
    oxy-acetylene cylinders , compressed air supply
    etc.
  • Main disadvantages of the above two methods
  • Long time taken for the operation
  • Due to the slower rate of heating, effectiveness
    of these methods is less and some other problems
    such as seizure of the threads also occur quite
    frequently.
  • Apart from this, the arrangements required are
    also complex and time wasted in maintenance /
    repairs of the equipment in case of defects is
    quite considerable.

35
Induction Heating for opening tightening
Casing of Steam Turbine
  • Induction heating method for threaded fasteners
  • Induction heating method is being used in other
    site applications such as preheating of joints
    for special welding of alloy steel pipe lines in
    thermal power stations.
  • This method is very quick and effective means for
    heating.
  • By using some modified gadgets, it was found
    suitable for loosening and tightening of the big
    size threaded fasteners of steam turbines, valves
    etc.
  • SAS Nagpur decided to use the induction heating
    method for loosening and tightening of threaded
    fasteners.
  • This method has resulted in saving valuable time
    for dismantling and assembly of steam turbines
    during overhauls. The method is simple and highly
    effective.
  • With the use of induction heating method, the
    problem of seizure of threads necessitating
    cutting and gouging of the nuts and studs, in LMW
    design, has been minimized.

36
Induction Heating for opening tightening
Casing of Steam Turbine
  • Comparison of time required for bolt opening
  • Time saved for overhauling is 3 days .
  • For a 210 MW set this translates into a gain of
    5.04 million units perday i.e approx. Rs. 2
    crore per day
  • For 500 mw set, 12 million units per day
    i.e.approx. Rs.4.8 crore perday

37
LASER ALIGNMENT KIT
OBJECTIVE
  • To carry out various alignment works in Turbine
    erection
  • With high precision.
  • At a reduced cycle time.

WORKS CARRIED OUT
  • Catenary of pedestals
  • Centering of bores of Diaphragms, Pedestals,
    Shaft Seals etc.
  • Alignment of Rotors.

CATENARY OF PEDESTALS
  • Accuracy of 10 Microns achievable.
  • Source equipments to be placed at extreme
    pedestals.
  • Mobile equipment placed in intermediate
    pedestals.
  • Laser is passed thro mobile equipment and
    adjustments carried out as per requirement.

38
LASER ALIGNMENT KIT
Centering of Bores of diaphragms,pedestals,shaft
seals etc
  • Source Laser device fixed in one extreme end
    pedestal
  • Receiver end device fixed in other extreme
    pedestal.
  • Special fixtures used for centering of
    intermediate pedestals.
  • Online adjustment possible.

Alignment of Rotors
  • Can cater to Coupling Dia from 100 mm to 1200 mm.
  • Alignment Device fixed on couplings to be aligned
  • Total misalignment is indicated by just 60 degree
    rotation of Rotors.
  • Misalignment values as well as correction
    required indicated in display.

Salient Advantages
  • Saving in Cycle time.
  • Accuracy of Measurement.
  • Indication of correction factors.

39
LASER ALIGNMENT KIT
CONCLUSION
  • The Laser Alignment kit is a useful equipment
    that is State of the Art in Technology and can be
    used very effectively in Turbine activities at
    high precision and reduced cycle time, as has
    been proved in Kudankulam site.
  • Hence extensive use of this equipment has to be
    practiced.

40
ORBITAL WELDING
  • Purpose To provide leak proof joint between
    Tube to tube sheet in Condenser in addition to
    Forced expansion
  • Process GTAW without filler wire addition
  • SIGNIFICANT ASPECTS
  • Material-Titanium
  • Large Qty of welding
  • Welding in position at site
  • Material supply by Russians
  • TITANIUM TUBES
  • Grade ASTM B 338 Gr2
  • Tube Sheet 35 5 mm thick
  • Material ASTM A516Gr 70 ASTM B 265
    Gr 1 CLAD

41
ORBITAL WELDING
  • Why Titanium is used?
  • Provides excellent resistance to general and
    localized attack under most oxidizing, neutral
    and inhibited reducing conditions in aqueous
    environments.
  • Corrosion Resistance due to stable, protective
    strongly adherent oxide film which forms
    instantly when a fresh surface is exposed to air
    moisture.
  • This film is transparent and not deducted by
    visual means.
  • Titanium resist corrosion by sea water to
    temperature as high as 260 0 C.
  • Even exposed to sea water for many years at a
    depth of over a mile shows no measurable
    corrosion.
  • Provides over 25 years of trouble free sea water
    service for chemical refinery de-salination and
    nuclear industries

42
ORBITAL WELDING
  • Has the ability to resist erosion by high
    velocity sea water
  • The presence of abrasive particles such as sand
    has only a small effect on the corrosion
    resistance of Titanium
  • Production began in the late 1950s
  • Most widely used titanium is commercial pure
    (99.5 Ti)
  • Manufacturing Process
  • Ingot ?slab ? Hot strip ? cold strip ? Slitting ?
    Forming ? TIG Welding ? Stress relieving ? Eddy
    Current Ultrasonic testing

43
ORBITAL WELDING
Physical Testing
Tensile, flare, flattening reverse flattening
Visual Inspection
Cleanliness, ID, OD, Surface condition, end
condition and marking.
Tube to tube sheet joining
Contact Rolling (0 to 5 wall thinning for a
length of 10 mm)
Orbital Welding For highly reliable leak
tightness
Forced Rolling (8 to 10 wall thinning for a
length of 25mm)
44
PROCESS FLOW CHART
Sh 1 of 3
Front / Rear end tube sheet cleaning wire brush
mounted in portable drilling machine followed by
acetone
Visual inspection
Titanium tube insertion
Initial cleaning before contact rolling
Initial contact rolling up to 10mm
45
PROCESS FLOW CHART CONTD
Sh 2 of 3
End facing of tube tube sheet up to 0.05 mm
Welding
Excess length trimming in the rear side
Visual inspection
Rectification of repair work
Final expansion 8 to 10 by lubricating SAE 40
oil
46
PROCESS FLOW CHART CONTD
Sh 3 of 3
Final cleaning by acetone
Dye Penetrant testing
Tube tightness test by MAUS Gun G-150
47
TUBE SPECIFICATION
48
TUBE INSERTION AT KODAMKULAM
49
PROGRAMABLE ORBITAL WELDING MACHINES
FRONIUS MODEL - FPA 2000 (AUSTRIAN MAKE)
50
AFTER TUBE INSERTION
51
TUBE SHEET PROTECTION
52
Welding parameters for FRONIUS MODEL - FPA 2000
Process GTAW (Automatic )No of weld passes
1Argon Gas flow rate
4 to 6 ltr /minPre Gas time
T10 30 Sec Post Gas time
T11 30 Sec Pre Fusion current
I21 90A Pre fusion
current time T21 0.1Sec Pulse
current I22 90A
Time of pulse current T22
100msec
53
USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT
TIGHTNING KIT
OBJECTIVE
  • To adopt a safe State of the Art methodology in
    bolt stretching of coupling bolts of TG Couplings.

GENERAL COUPLINNGS IN TG
HP Tubine to IP Turbine IP Turbine to LP
Turbine LP Turbine to Generator Shaft
REQUIREMENT
The coupling bolts which are like pins, having a
clearance of 0.03mm diametrically, have to be
stretched up to 0.55 mm ,depending on the bolt
dimensions to ensure uniform tightening .
54
USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT
TIGHTNING KIT
Prevalent practice
Nut of the Coupling bolt is tightened by a box
spanner Leverage applied on end of the spanner by
EOT crane through slings. Differential expansion
monitored by Dial Gauge positioned at bolt ends.
Sources of Error
Dial gauge at the nut end has to be fitted with a
long extension rod,which may lead to error in
reading. Disturbances in the nut also can lead to
erratic readings.
Safety element
The whole stretching operation dependent on skill
of the Fitter and EOT Crane operator Fine
movements in EOT Crane not possible Danger of
slipping/shearing always present.
55
USE OF HYDRAULIC OPERATED TORQUE CONTROLLED BOLT
TIGHTNING KIT
RECOMMENDATION
Hydraulically operated Torque controlled Bolt
tightening kit can be used. Manufacturing Unit to
specify Torque tightening values of individual
couplings.
ADVANTAGES
No error in reading. Uniformity in bolt
stretching Safe for the working personnel Safe
for the equipment
56
Power Sector Western Region
IMPROVED PROCESSES
57
ALL-VOLATILE OXYGENATED TREATMENT
  • AVT The basic idea of AVT is to minimize
    corrosion erosion corrosion in the low
    temperature region by using deaerated high purity
    water with elevated PH. The actual PH range
    depend on cycle metallurgy
  • In absence of Oxygen, the primary reaction of
    iron dissolution is inhibited by increasing PH.
  • The solubility of ferrous hydrazine rises
    with increase in temperature and then decreases
    with steep drop to the solubility of magnetite
    between 200 250 0C. This results in undesirable
    magnetite deposit in this temperature range.


58
ALL-VOLATILE OXYGENATED TREATMENT
  • To maintain the solubility of ferrous hydroxide
    in feed water below or equal to that of magnetite
    at 250 0C and to exclude the possibility of over
    saturation, a minimum PH of 9.6 should be
    maintained. A PH of 10 would be even better.
  • Hydrazine acts both as a O2 scavenger
    corrosion inhibitor by formation of ferrous oxide
    hydrate.
  • OXYGENATED TREATMENT
  • This process uses oxygenated high purity water to
    minimize corrosion erosion corrosion in the
    feed water train.
  • Oxygen, Hydrazine peroxide, air are used as
    oxidants


59
ALL-VOLATILE OXYGENATED TREATMENT
  • Oxygen level should be 30-50 ppb for drum units
    and 30-150 ppb for Once Through Units.
  • Ph level shall be 9-9.6 at Drum units and
    8-8.5 for Once Through Units
  • In oxygenated system, p rotective layer
    consists of Magnetite(FE3O4) and Hematite(FE2O3)
    layers
  • For temperature ranges upto 250 0C the
    addition of oxygen allows the formation of oxide
    protective layer which have a very low corrosion
    product release rate in the following water


60
ALL-VOLATILE OXYGENATED TREATMENT
  • AL L VOLATILE TREATMENT (AVT)
  • Ferrous or mixed feedwater train
  • Cation conductivity 0.2-0.4 µS/cm
  • pH 8.8 9.6 (Dependent on feedwater
    metallurgy)
  • Fe 10ppb N2H4 ( gt3x02)
  • O2 lt5ppb
    NH3 ( 0. 15-2 . 3 ppm)


  • Fe lt2 ppb O2 ( gt30 ppb )
    O2 ( gt30 ppb )
  • NH3 ( 20 -70 ppb )
  • OXYGENATED TREATMENT (OT)
  • All ferrous feedwater train
  • Cation conductivity lt 0. 15 µS /cm
  • pH 8.0 8.5

61
LP BYPASS SYSTEM
  • LP BYPASS SYSTEM
  • MODIFICATION CARRIED OUT IN OLD LPBP SYSTEM
  • In case of Turbine trip, direct command will be
    issued to LP Bypass valves for opening upto 45
    for 3 secs.
  • It is expected that within this 3 secs., the
    spray valves will open and the spray water
    pressure will be achieved.
  • However, if the spray water pressure has not
    reached a value of 5 kg/cm2 within 3.5 secs., or
    the condenser wall temperature has become more
    than 90 0C, the LP Bypass trip command will be
    issued

62
LP BYPASS SYSTEM
  • The sensing of pressure is done by installation
    of additional pressure transmitters at the
    downstream of spray water valves
  • The modification was implemented first in
    Vindhyachal U10 and two occasions since the
    modification, the turbine has tripped and LP
    Bypass valves opened within 5 secs thereby saving
    the boiler trip
  • LBPB SYSTEM FOR NEW 250 MW SETS
  • To address this issue, now BHEL, Hwr has gone for
    a new High Pressure LP Bypass system which has
    much better response time. Such system have been
    supplied at 1 x 250 MW Parli, 1 x 250 MW Paras, 4
    x 250 MW JPL and 2 x 250 MW Bhilai sites.

63
LP BYPASS SYSTEM
  • The logic provided for the operation of the LB
    Bypass valves are similar to that of the older
    low pressure LPBP valves. However, the following
    are the new features of High Pressure LPBP valves
  • The LPBP valves on sensing increase HRH Pressure,
    automatically opens without looking for adequate
    water pressure
  • For the water injection spray control valves, two
    curves have been implemented, one for control and
    the other for protection based on down stream
    pressure of LPBP valves.

64
LP BYPASS SYSTEM
  • If the actual water injection flow is less than
    flow corresponding the protection flow, then the
    LPBP valves closes on water injection flow
    protection.
  • The following problems have been noticed in the
    new system
  • As per the water injection curve, a continuous
    water flow is required to the system which is
    unnecessary and wasteful.
  • The spray water flow element and flow transmitter
    is showing 0 reading upto 50 of spray control
    valve opening.
  • The problem has been taken up with BHEL, Haridwar

65
LP BYPASS SYSTEM
  • Conclusions
  • The new High Pressure system is working
    satisfactorily and therefore, the boiler tripping
    due to reheater protection in the new system has
    been avoided in the recently commissioned units.
  • By implementing the modification in the old units
    as done at NTPC Vindhyachal U9, 10, the problem
    of the old units can also be resolved.

66
Power Sector Western Region
BEST PRACTICES
67
Best Practices, TSX PSWR
CARD BOARD BLASTING OF LUB OIL AND CONTROL OIL
LINES OF STEAM TURBINES
  • GENERAL PRACTICE
  • Only mechanical cleaning is done before start of
    oil flushing for lub oil and control oil system
    of steam turbines.
  • BEST PRACTICE
  • Exhaustive card board blasting along with
    mechanical cleaning is carried out for all the
    control and lub oil system before start of oil
    flushing.
  • This practice is being followed in almost all the
    sites now.
  • ADVANTAGES
  • Effective cleaning and time reduction.

68
Best Practices, TSX PSWR
USE OF PORTABLE CENTRIFUGE DURING LUB OIL
FLUSHING OF ROTARY MACHINES
  • GENERAL PRACTICE
  • Generally oil flushing were carried out at
    ambient temperature without any centrifuging
    arrangement for rotary machines such as BFP, ID
    Fans, FD Fans and Mills.
  • BEST PRACTICE
  • Oil flushing is carried out with portable oil
    centrifuge having in-built heating arrangement .
  • ADVANTAGES
  • Effective cleaning and time cycle reduction.

69
Best Practices, TSX PSWR
CHEMICAL CLEANING OF PRE BOILER SYSTEM WITH CEP
  • GENERAL PRACTICE
  • Carried out by using temporary pumps, tanks and
    piping along with boiler acid cleaning setup
  • BEST PRACTICE
  • Existing CEP and Hotwell are used for the purpose
    of circulation in the entire system
  • ADVANTAGE
  • Effective cleaning of the entire system with
    minimum number of temporary loops
  • Cost and time cycle reduction

70
Best Practices, TSX PSWR
USE OF DEAERATOR AS MIXING TANK FOR PRE-BOILER
FLUSHING
  • GENERAL PRACTICE
  • Mixing tanks and associated pipings are arranged
    for carrying out the pre boiler flushing
    activities.
  • BEST PRACTICE
  • For industrial sets, Deaerator itself is used as
    mixing tank for carrying out chemical cleaning of
    pre-Boiler system.
  • This results in cost and time cycle reduction.

71
Best Practices, TSX PSWR
CHEMICAL CLEANING OF BOILER (WW, SH) AND MS LINES
IN INDUSTRIAL PROJECTS
  • GENERAL PRACTICE
  • Stages are Alkali boilout, Acid cleaning and
    passivation
  • BEST PRACTICE
  • Alkali flushing, Citric acid cleaning,
    passivation of the entire system
  • ADVANTAGE
  • Chemical cleaning activities can be completed
    even before Boiler light up
  • Since both SH and MS lines are acid cleaned
    steam blowing cycle is considerably reduced
  • Cost and time cycle reduction

72
Best Practices, TSX PSWR
CHEMICAL CLEANING OF HSD AND NAPHTHA LINES IN CCPP
  • GENERAL PRACTICE
  • Cleaned by card board blasting
  • BEST PRACTICE
  • Citric acid cleaning with passivation
  • ADVANTAGE
  • Where the length of HSD and Naphtha lines is
    more than 500 meters cardboard blasting shall not
    be very effective. Hence, citric acid cleaning is
    a most effective way of ensuring cleanliness of
    the entire piping
  • Time cycle reduction and trouble free operation

73
Best Practices, TSX PSWR
USE OF THERMIC FLUID HEATER FOR COMMISSIONING
ACTIVITIES IN GREEN FIELD PROJECTS
  • GENERAL PRACTICE
  • Auxiliary boiler is used for generation of steam
    for pre-commissioning activities like flushing of
    Boiler Feed Line, Condensate Lines, Drip Lines
    etc.
  • BEST PRACTICE
  • Thermic fluid heater is used in green field
    projects in place of auxiliary boiler for
    carrying out chemical cleaning activities.
  • This results in cost and time saving.

74
Best Practices, TSX PSWR
ACID CLEANING WITH EDTA
  • GENERAL PRACTICE
  • Generally HCL is used for acid cleaning of main
    boiler.
  • BEST PRACTICE
  • HCL is replaced by EDTA for all green field
    projects especially, where auxiliary steam is not
    available.
  • This is safe, environment friendly and reduces
    time cycle.

75
Best Practices, TSX PSWR
PROVISION OF ADDITIONAL INTERSTAGE VALVES
FOR STEAM BLOWING
  • GENERAL PRACTICE
  • Interstage valves are not used during steam
    blowing operations resulting in three to four
    days shut down for start of subsequent steam
    blowing operations.
  • BEST PRACTICE
  • Additional temporary valves are used at Main
    Steam HP Bypass lines, CRH Lines during steam
    blowing operations.
  • This has resulted in cycle time reduction.

76
Best Practices, TSX PSWR
CONTINUOUS STEAM BLOWING IN CCPP
  • GENERAL PRACTICE
  • Puffing method is used due to limitation of fuel
    firing system
  • BEST PRACTICE
  • Continuous blowing method (30 minutes) is used
    in stages
  • ADVANTAGE
  • Effective cleaning and time cycle reduction

77
Best Practices, TSX PSWR
HIGHER STEAM BLOWING PARAMETERS
  • GENERAL PRACTICE
  • Steam blowing is carried out at 40 Kg / sq cm
    and 300 350 deg C
  • BEST PRACTICE
  • Steam blowing carried out at 50 Kg / sqcm and
    370 400 deg C
  • ADVANTAGE
  • Effective cleaning due to higher disturbance
    factor at elevated parameters
  • Time cycle reduction

78
Best Practices, TSX PSWR
USE OF FRESH LUB OIL BOTH FOR FLUSHING AND REUSE
IN ALL INDUSTRIAL SETS
  • GENERAL PRACTICE
  • Flushing oil is used for oil flushing operation,
    fresh oil is used for normal operation
  • BEST PRACTICE
  • After cleaning of entire lub oil system by
    cardboard blasting fresh oil is used both for
    flushing and normal use
  • ADVANTAGE
  • Cost and time cycle reduction

79
Best Practices, TSX PSWR
AIR LEAK TEST OF LUB OIL, CONTROL OIL, AND
CONTROL FLUID SYSTEM
  • GENERAL PRACTICE
  • No separate test conducted before start of
    flushing resulting in leakage of oil / fluids
  • BEST PRACTICE
  • Entire system is pressure tested with compressed
    air at 5 to 6 Kg/sqcm before start of flushing
    operation
  • ADVANTAGE
  • Leakage of oil and control fluid is minimised
  • Cost and time cycle reduction

80
Best Practices, TSX PSWR
GENERATOR SEAL OIL FLUSHING
  • GENERAL PRACTICE
  • Seal oil flushing is done for the site erected
    pipes upto the inlet nozzle in the end shield
  • BEST PRACTICE
  • Pre-fabricated pipes from the end shield upto
    seal ring inlet are also included in the final
    stage of flushing.
  • ADVANTAGE
  • Avoids damage to Generator seal from the
    entrapped foreign material.

81
Best Practices, TSX PSWR
HYDRAULIC TEST OF LUB OIL, CONTROL OIL AND SEAL
OIL LINES
  • GENERAL PRACTICE
  • Jacking oil pumps were used for carrying out
    hydraulic test of lub oil, control oil and seal
    oil line after flushing.
  • BEST PRACTICE
  • AC seal oil pimp is used for the purpose of
    hydraulic test of the above system.
  • ADVANTAGE
  • Avoids damage to Jacking oil pumps.

82
Best Practices, TSX PSWR
CONDENSER MASS FLUSHING
  • GENERAL PRACTICE
  • Cleaning of condenser is normally carried out
    during steam dumping operation
  • BEST PRACTICE
  • Condenser tubes are thoroughly flushed through
    high pressure jets (fire fighting water) before
    commissioning of CEP
  • ADVANTAGE
  • Duration of steam dumping operation reduced
  • Cost and time cycle reduction

83
Best Practices, TSX PSWR
CLEANING OF VACUUM PUMP SUCTION LINES
  • GENERAL PRACTICE
  • No structured cleaning is envisaged except
    draining the system through drain valves (NB50)
    during initial commissioning of vacuum pumps
  • BEST PRACTICE
  • Vacuum pumps suction lines are throughly cleaned
    through cardboard blasting before commissioning
    of vacuum pumps
  • ADVANTAGE
  • Smooth trouble free operation
  • Damage of vacuum pumps due to entry of foreign
    material is avoided

84
Best Practices, TSX PSWR
OLTC COMMISSIONING
  • GENERAL PRACTICE
  • OLTC is commissioned normally after attaining
    continuous operation of unit, i.e., CW system has
    been put into service for prolonged period
  • BEST PRACTICE
  • OLTC is commissioned either
  • Immediately after running of CW pump or
  • Before conductance of PG test after thorough
    cleaning of condenser tubes
  • ADVANTAGE
  • Collection efficiency of balls increase
  • Trouble free condenser operation

85
Best Practices, TSX PSWR
SELF CONTAINED BEARING COOLING ARRANGEMENT AT EPC
PROJECT
  • GENERAL PRACTICE
  • Lub oil coolers for ID, FD and PA Fans are kept
    charged through the bearing cooling water system
  • BEST PRACTICE
  • In EPC project where due to certain
    circumstances there is a delay in commissioning
    of Cooling Water system a separate self contained
    cooling arrangement (Sintex tank, pumps and
    suitable hoses) to facilitate initial
    commissioning
  • ADVANTAGE
  • Trial operation of all major boiler auxiliaries
    can be completed by this method leading to time
    cycle reduction

86
Best Practices, TSX PSWR
PRE ERECTION CHECKING OF BUS-DUCTS
  • General Practice
  • Bus-ducts are cleaned and erected
  • Commissioning jobs taken up later
  • Best Practice
  • While at ground, check tightness of all
    electrical connections of heaters, thermostats
    etc
  • Check heaters healthiness and adjust thermostat
    tripping points easily now
  • Check drain pad holes before lifting so that any
    corrections, if required can now be done easily
  • Trial assembly of Bus-duct structure on ground
    before erection
  • Avoids difficulty in commissioning /
    troubleshooting


87
Best Practices, TSX PSWR
TURBINE X-CRITERIA
  • General Practice
  • In X1 criteria for turbine rolling, main steam
    inlet temperature to turbine has been used for
    criteria calculation. During any boiler trip and
    restart, X1 criteria gets fulfilled even though
    boiler outlet temperature is less. This leads to
    cold steam entering the turbine.
  • .
  • .Best Practice
  • Additional criteria X11 introduced using
    Temperature before HP bypass.

88
Best Practices, TSX PSWR
ADDITIONAL TRIPPING DURING ATT
  • General Practice
  • Tripping criteria during conductance of ATT does
    not include many vital trip inputs
  • .
  • .Best Practice
  • Conditions like MFT, Turbine Bearing temperature
    VH, axial shift VH, vacuum low, cold gas temp
    trip, seal oil temp trip etc are added

89
Best Practices, TSX PSWR
COMMISSIONING OF ATRS, ATT AUTOSYNCHRONIZER
  • General Practice
  • Normally, ATRS, ATT and Auto-synchroniser are
    getting commissioned as pending points and not as
    a part of normal plant commissioning.
  • So after the pending point is cleared,
    customer is normally not using the system.
  • Best Practice
  • We are putting efforts for commissioning these
    system in the first rolling
  • synchronisation itself.
  • Recently at Bhilai and Tata Trombay, ATRS and
    Auto-synchroniser have been commissioned during
    first few start-ups.
  • At Tata Trombay, ATT is also commissioned.

90
Best Practices, TSX PSWR
DC EOP AND SOP LATCH RELAY
  • General Practice
  • Lub Oil pressure low switch starts DC EOP
    through max system SLC latch relay contract..
  • .
  • Best Practice
  • SLC latch relay contract in DC EOP and SOP
    cabinet looped so that lub oil pressure low
    switch contact starts DC EOP and SOP directly,
    bypassing MAX system SLC ON.
  • This safeguards machine in the event of AC as
    well as failure of max system

91
Best Practices, TSX PSWR
AUTOSYNCHRONIZATION
  • General Practice
  • As per circuit configuration, auto synchronizer
    after fulfilling its set condition directly
    closes the Generator circuit breaker..
  • .Best Practice
  • Additional contact of check synchronization
    relay wired up in auto synchronization circuit.
    Here autosynchroniser setting are coordinated
    with setting of check synchronizing relay so that
    autosynchroniser and check synchronization relay
    operates at the same time.
  • This helps in safeguarding the machine during
    malfunctioning of autosynchronizer.

92
Best Practices, TSX PSWR
AUTOSYNCHRONIZER TESTING
  • General Practice
  • As per normal practice, autosynchronizer is
    tested and its output command is verified within
    the panel terminals..
  • Best Practice
  • Autosynchronizer is tested in cold condition
    with supply of PT voltages through injection kit
    and actual Generator breaker closing (ensuring
    that isolators are open)
  • This helps in optimization of autosynchronizer
    setting more correctly and also total circuit
    gets checked.

93
Best Practices, TSX PSWR
USE OF MULTIPLE FILTRATION MACHINES FOR
TRANSFORMER DRYOUT
  • General Practice
  • One Oil filtering machine (about 6 KL capacity)
    engaged for dryout
  • Best Practice
  • More than one such machine put in parallel
    operation to optimally utilise transformer drain
    header flow capacity
  • Advantage
  • Cycle time reduced around 50

94
Best Practices, TSX PSWR
TURBINE BEARING METAL TEMPERATURE CHECKING
  • General Practice
  • As per normal practice, cabling from bearing
    metal temperature JB to control room/Cold
    Junction Compensation(CJC) JB are checked after
    installation of thermocouple in bearings..
  • .Best Practice
  • Before installation of thermocouples in bearing,
    signal upto DCS checked by heating the
    thermocouple tag wise.
  • This ensures correctness of connection, readings
    and also ambiguity of polarity change is avoided.

95
Best Practices, TSX PSWR
DAVR DUMMY LOAD TESTING
  • General Practice
  • As per normal practice, the AVR/DAVR dummy load
    testing is carried out at site with the help of
    500W lamp or any available resistive load..
  • .Best Practice
  • Dummy load testing is carried out with same type
    of resistive load which is identical in ratio to
    that of factory testing. With this type of
    testing, exact and identical readings with
    factory can be ensured.
  • Customer as well as commissioning engineer gets
    better confidence on DAVR working.

96
Best Practices, TSX PSWR
PAINTING OF TRANSFORMERS AND BUS-DUCTS
  • General Practice
  • Painting works for busducts and transformers are
    attempted at very late stages
  • Becomes difficult because of shutdown requirement
    and thus opportunity may not be there
  • Best Practice
  • At least Station transformer and its busducts
    may be painted immediately after erection
    completion (before first charging). This
    transformer hardly goes into shutdown later
  • Better to paint the other transformers and
    busducts as well as soon as possible before
    charging
  • However, customer opinion / permission may be
    required since they may insist on painting only
    after all works are completed

97
Best Practices, TSX PSWR
SEQUENCE STARTUP OF HT DRIVES
  • General Practice
  • All HT drives are generally started individually
    during first commissioning of the drives
  • This lead to a pending point as we do not get
    suitable opportunity to commission the HT drives
    in sequence mode
  • Best Practice
  • All the HT drives to be started in sequence
    during first startup of the any HT drive

98
Power Sector Western Region
Process improvements Adopted During Overhaul by
PSWR-SAS Nagpur
99
Introduction
  • Implementation of Best Practices during
    Overhauling
  • of T.G. has resulted into the following -
  • Overhauling cost reduction.
  • Reduce overhauling periods.
  • Improvement in quality.
  • Introduce latest technologies.
  • Improve customer satisfaction

100
Implementation of Best practices
  • Use of latest technology like induction heating
    for dismantling and assembly of turbine.
  • Unit de-synchronization at 480 ºC of HP shaft
    temp by decreasing the load before shut down..
  • Turbine oil pump stop at 125ºC (HPS temp).
  • Barring gear stop at 125ºC (HPS temp).
  • To initiate overhauling activities as soon as
    machine comes to barring gear.
  • Decoupling of Generator rotor from turbine
    rotor and put back turbine rotor in barring.
  • Start dismantling of generator and O/H
    activities thereafter.

101
Review by Site and follow-up from HQ
  • Site reviews all activities minutely
  • Time taking processes, idle times between
    activities, delay in arranging spares and
    mobilization of experts from units etc are
    identified well in advance.
  • HQ also involves in reviewing processes and all
    important issues and HQ inputs are duly
    incorporated on activity planning at site.
  • Reduction in overhauling duration to the target
    schedule is attributed to meticulously planning
    and follow-up of critical activities, which is
    accomplished in a shortest duration.

102
Strategic Planning
  • List out the History of past problems
  • Pre-overhaul survey record.
  • Analyze Present running behavior.
  • Input from MOUs and utilities.
  • Timely arrange experts service from MOUs
  • Milestone based review.
  • Mobilization of resources 3 days before start of
    Overhaul.
  • Scheduling of sequential parallel activities
  • Identification of idle time to avoid them by
    detailed planning in advance
  • All the anticipated spares required for
    completion of the overhauling work arranged at
    T.G. Floor before start of the work.

103
Generator work starts within 36 hrs of
De-synchronization
  • 0000 hrs De-synchronization (HP shaft temp at
    480 Deg.C)
  • 17.5 hrs Barring gear stop (HP shaft temp at
    400 Deg C)
  • 17.5 hrs. to 20.5 hrs
  • AOP stop
  • Lub oil to brg. 5,6,7 blanked brg. 4 minimized
  • LP-Gen coupling decoupling
  • Hand barring will continue during this period
  • 20.5 hrs B/G re-started
  • With this practice Generator rotor thread out
    work starts within 36 hrs of de-synchronization.

104
Procedure for decoupling of LP-Generator in hot
conditions
  • Turbine is on Turning Gear. JOP in service, AOP
    in service.
  • Loosening of pedestal cover bolts, removal of
    Vibration probes.
  • Close turning gear valve to reduce the speed.
    Simultaneously loosen and remove pedestal cover
    bolts.
  • When Turbine speed becomes zero. Stop AOP while
    JOP is continuously kept in service. Continue
    Hand Barring.
  • Remove pedestal 4 cover. Close Lubricating oil
    throttle valve to the minimum possible.
  • Simultaneously blank lub oil supply to bearing
    5,6 and 7 by putting gasket in lub oil supply
    line. (parallel, by 3 gangs). Keep watch on
    bearing 1,2 and 3 metal temperature and
    simultaneously do hand barring.

105
Procedure for decoupling of LP-Generator in hot
conditions
  • Put tin sheet/polythene to cover on bearing 4.
    Start EOP and continue hand Barring.
  • Loosen LP-Generator coupling bolts and decouple
    LP-generator by continuing hand barring.
  • Shift generator rotor away from turbine Stop EOP
    and Adjust brg. 4 lubricating oil throttle valve
    to normal. Put pedestal cover back and start EOP
    barring gear.
  • Dismantling prepare for rotor thread out.
  • At the time of rotor thread out, stop turning
    gear again and stop EOP. Remove pedestal 4 cover.
  • After thread out put pedestal 4 cover back.
    Turbine on Barring gear with AOP in service till
    HP shaft temp comes to 125 deg C .
  • Note Jacking oil pump is throughout kept in
    service.

106
PSWRs Best records on TG overhauls
  • Overhauling of IP-LP Turbine Generator
    including LP Turbine blades MPI have been
    carried out in record lowest time of 8½ days
    barring to barring. (13 days Bar to Bar) on year
    2007 at 250MW U2 Dahanu TPS.
  • Overhauling of LP Turbine Generator have been
    carried out in record lowest time of 9 days
    barring to barring. (15 days Bar to Bar) on year
    2005 at 250MW U2 Dahanu TPS . This was achieved
    as an exceptional case to avoid power problem
    in Mumbai.
  • Overhauling of HP- LP Turbine Generator
    including HP rotor replacement HP/IP coupling
    hole reaming, LP free standing blades MPI NFT
    along with bearings 1,2 4 replacement have
    been carried out in record lowest time of 13
    days baring to barring. (18 days Bar to Bar) on
    year 2006 at 250MW U1 Dahanu TPS.

107
PSWRs Best records on TG overhauls
  • Overhauling of IP-LP Turbine Generator
    including LP Turbine blades MPI NFT have been
    carried out in record lowest time of 12 days
    barring to barring. (17 days Bar to Bar) in year
    2008 at 250MW U2 Dahanu TPS.
  • Unit-3 HP Module overhauled in 14 days barring
    to barring (19days bar to bar) in year 2006 at
    200MW U-3 KSTPS NTPC Korba.
  • Capital Overhauling of HP-IP-LP Turbine
    Generator including HP rotor replacement HP/IP
    coupling hole reaming, LP free standing blades
    MPI NFT have been carried out in record lowest
    time of 35 days barring to barring in year 2008
    at 500MW U8 NTPC VSTPS Vindhyachal .

108
Schedule comparison
109
Conclusion
  • A benchmark on record minimum duration in KWU
    design TG set overhaul could be achieved.
  • It was the determination, commitment, monitoring
    and follow-up of associated activities that
    ascertained to achieve a challenging target.
  • Working out activities well in advance with
    subcontractor agencies/ partners and round the
    clock execution of job with new strategies helped
    to meet schedule deadlines.
  • Work can be started as soon as machine comes to
    Barring gear.
  • Cooling Down period can be saved relatively by 4
    days during the Generator overhauling.

110
Power Sector Western Region
IMPROVED SITE FACILITIES
111
Porta Cabins - to overcome delay in site
mobilisation
  • Award of Enabling works and its construction
    takes considerable time, after receipt of confirm
    order. This delays posting of site staff and
    material management including posting of
    Construction Manager.
  • PSWR has decided to procure Porta Cabins with all
    amenities as replacement of Conventional Site
    office sheds.
  • This will be provided in all new sites like
    Satpura, Mauda, Chandrapur, Raigarh,
    Vindhyachal, Bela Ideal Energy including all
    forthcoming sites.
  • NIT has been floated and tender is likely to be
    finalized by end April 2009.

Exploring Heights
..................... Setting Standards
.................... Marching Towards
Excellence Power Sector Western Region
01/02/2013
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113
Porta Cabins - to overcome delay in site
mobilisation
  • Advantages of Porta Cabins
  • Quick mobilization
  • Quick realization of mobilization advance from
    customer
  • Quick demobilization
  • Flexibility in use can be installed as per the
    site condition
  • Environmental friendly due to cleanness easy
    maintenance
  • Provide better facility to site staff
  • Light weight (Easy in handling and
    transportation)
  • Aesthetic look.
  • Durable and Termite proof
  • Seismic-resistant
  • Economical in long term because of repetition
  • Thermal Insulation

Exploring Heights
..................... Setting Standards
.................... Marching Towards
Excellence Power Sector Western Region
01/02/2013
113
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