Presented at National Boiler Workshop 2015 - Experiences of NTPC Simhadri

2. By:
M.SIVARAMA KRISHNA, GM(O&M)
S.K.PRASAD,Sr.Mgr (O)
CH.PRADEEPKUMAR,Dy.Mgr(O)
EFFICIENTOPERATION &MAINTENANCEOFBOILERS
NATIONAL BOILER WORKSHOP-2015
NTPC SIMHADRI –WELCOME’s

3. FLOW OF PRESENTATION :
 Journey of NTPC
 O & M Best Practices
 Zero Boiler Tube leakage
 LATEST Technology adopted
 Conclusion

4. NTPC VISION
NTPC HAS TO BECOME A 1,28,000 MW COMPANY BY 2032

5. 45,548 MW (Including JV’s)
COAL :38,654MW
HYDRO:5984 MW
GAS:1000MW
RENEWABLE:100MW
INSTALLED CAPACITY

6. NTPC GROUPACCOUNTSFOR16%OFINDIA’STOTAL
INSTALLEDCAPACITYAND25%OFALLINDIA
GENERATIONASON31.03.2015
SUSTAINABLE DEVELOPMENT:A LONG JOURNEY

7. TYPES OF BOILER‘s IN NTPC
 CC, RIFLED TUBE, RADIENT RH TOP SUPPORTED 500MW
SUB CRITICAL BOILER
 ONCE-THRU SUPER-CRITICAL, TWO-PASS, BALANCED DRAFT,
RADIANT RH, TOP SUPPORT 660MW
 TOWER TYPE(SINGLE PASS),ONCE-THROUGH
SINGLE RH BOILER 500MW
 ONCE THROUGH SUPER CRITICAL,
DOUBLRE PASS 800MW

8. FORCED OUTAGE : A MAJOR CHALLENGE
BTL
START UP
DEVIATIONS
OVERHEATING/
CORROSION
WELD
FAILURES
FLUE GAS
EROSION
CHEMICAL
PARAMETER
DEVIATIONS

9. O & M BEST PRACTICES
TO AVOID STARTUP DEVIATIONS
 Standardized all Operation procedures & reviewed
periodically for improvement.
 No SH/RH Spray till Synchronization.
 Proper choice of Mill/Oil gun elevations during start-up
 Maintaining proper Rate of rise of Pressure/Temperature - Avoid
over firing.
 Safety valve floating with oil guns only
 Passing of SH/RH spray valves attended regularly

10. TO AVOID STARTUP DEVIATIONS
 SH/RH Spray limiting interlock to limit temp at De-superheater
outlet falling below saturation temp – implemented in all units
 Monitoring of Economizer outlet temp w.r.t Saturation
temperature at eco I/l pressure during start-up
 Drum Level Control
 Low range FRS control kept in auto during unit start-up
DP across FRS maintained around 5-10 KSC
 CBD is kept open continuously till chemical parameters
are achieved
 Continuous flow of feed water through economizer
during startup is ensured
O & M BEST PRACTICES

11. CHEMISTRY IN STARTUPS
 Maintaining the chemical regime of boilers
Ensure CPU availability and putting both in service
during start-ups
 Frequent sampling of Steam / water at local and SWAS
availability
 PH maintained through Ammonia Dozing.
 Condensate Dumping
 Hot draining as per requirements
O & M BEST PRACTICES

12. WELD JOINT FAILURES
 100% Radiography of joints being done during overhauls
 Radiography of bends during OH for observing any blockages
or deposits
EROSION
 Tube leakage in BTT - Erosion of Burner transition bends
was observed due to Secondary air from wind box -
Application of plastic refractory over Burner transition tube
bends
 Visual Inspection of tubes in Burner zone for signs of
overheating like bulging etc. during OH
O & M BEST PRACTICES

13.  Cutting of Tubes by Grinding machine
 HP Jet cleaning boiler surfaces
 Use of Beveling machine for chamfering
 Plastic refractory over Burner transition tube bends
 Inspection of attemperation spray nozzles
 Economizer repair on maintenance beds outside
INITIATIVES TAKEN @ SIMHADRI

14.  Monitoring metal temperatures – deviations are discussed in DPM
 Monitoring Rate of rise of temp / pressure during startup &
shutdowns thru PI applications
 Pressure setting of wall blowers / LRSBs – Once in three months
 Operation of LRSBs in the presence of maintenance Personnel.
Incase of any mal-operation, blower can be retracted immediately
without any damage.
 Optimization of Wall blower / LRSB Operation
Regular checking of SADC/BT at local and remote positions. Defects
are attended regularly
OPERATION BEST PRACTICES

15. BOILER TUBE LEAKAGES AT SIMHADRI
Year Tube Leakage (No) Tube Leakage (%)
2011-12 3 0.64
2012-13 9 1.64
2013-14 10 1.37
2014-15 8 1.03
2015-16 0 0.00
Previous Financial year
same period
3 1.10
*No tube leakage in the first three months of the last overhauls

16. Area Cause / Mechanism Remedial actions based on past failures
1. S -Panel
EROSION Thickness survey & visual inspection of
all Z-Panel, intersection and all
manhole door tubes.
WELD DEFECT DPI of Peep hole door plates welds.
100% radiography of repair joints.
ATTACHMENT WELD
FAILURE
100% DPI in fin welding at repair
joints.
ACTION PLANS FOR ZERO BTL

17. Area Cause / Mechanism Remedial actions based on past failures
2
WATER
WALL &
HANGER
TUBES
EROSION
(SB Steam)
Thickness survey and visual inspection of
Tube & Burner bends.
Soot blower alignment checking.
Checking of hanger tube shielding and
replacement.
SHORT TERM OVER
HEATING
(Starvation)
Ensuring plugs during tube repair.
Flushing of bottom ring header by
draining at 10 Kg/Cm2.
ATTACH MENT
WELD
100% DPI in fin welding at repair joints.
Weld failure To take care while cutting the tube
ACTION PLANS FOR ZERO BTL

18. Area Cause / Mechanism Remedial actions based on past failures
3 ROOF
TUBES
EROSION Penthouse cleaning and seal plate
checking.
Inspection of roof tubes from furnace
side.
4 PLATEN
SH /
DIVISIONA
L PANEL /
SPACER
TUBES
WELD
FAILURE
100% radiography of repair joints,
Alignment of coils
Random DP and radiography of other
joints.
RUBBING
(coil)
Inspection of spacer tubes, girdling
loops and binding loops.
Inspection of tubes near cleats during
every O/H
Healthiness of Clamp & stopper.
ACTION PLANS FOR ZERO BTL

19. Area Cause /Mechanism Remedial actions based on past failures
5
RE-
HEATER
OVER
HEATING
(Starvation due to
blockage.)
Vertical tubes to be cut by
grinding and capping.
Steam cleaning of new tubes
before welding.
Oxide scale measurement.
Sponge ball checking of RH tubes for
identifying blockages
Use of Metal caps
WELD
FAILURE
Radiography of shop & erection joints
including DMW
100% DPT & RT in areas of degradation.
ATTACH MENT Cleat welding being done..
ACTION PLANS FOR ZERO BTL

20. Area Cause/Mechanism Remedial actions based on past
failures
6 RH VENT
/ DRAIN
STUB
WELD
FAILURE
DP of startup vent / drain stubs of
Re heater is being done.
7 ECONOMI
SER
FLUEGAS
EROSION
Thickness survey and visual
inspection.
Cassette baffles and shielding
inspection.
WELDFAILURE 100% radiography of repair joints.
Similar erection welds to be
inspected by DP & RT.
ACTION PLANS FOR ZERO BTL

21. Area Cause / Mechanism Remedial actions based on past
failures
8 LTSH
Flue Gas
Erosion
Visual inspection and thickness survey.
Shielding of manhole door bends &
bifurcation tubes.
Proper Refractory application.
Checking of cassette baffles.
weld
joint Failure
Random and RT of other welds.
100% radiography of repair welds.
Manhole door
attachment weld
failure
DP at manhole door bends.
Proper clamping of shield.
Visual inspection of fins in LRSB area.
ACTION PLANS FOR ZERO BTL

22. OTHER BEST PRACTICES
ENERGY & EFFICIENCY MAPPING OF
a) Draught systems
b) Compressed air systems
c) Milling system
d) CW system
e) Ash handling
f) Coal handling plant.

23. LATEST TECHNOLOGIES ADOPTED
 ASLD(ACOUSTIC STEAM LEAK DETECTORS)
 PADO
 PI SYSTEM
 SCADA
 FLAME CAMERAS
 ACOUSTIC PYROMETERS

29. BEVELING MACHINE