boiler operation and maintenance experiences
TRANSCRIPT
By:
M.SIVARAMA KRISHNA, GM(O&M)
S.K.PRASAD,Sr.Mgr (O)
CH.PRADEEPKUMAR,Dy.Mgr(O)
EFFICIENT OPERATION & MAINTENANCE OF BOILERS
NATIONAL BOILER WORKSHOP-2015
NTPC SIMHADRI –WELCOME’s
FLOW OF PRESENTATION :
Journey of NTPC
O & M Best Practices
Zero Boiler Tube leakage
LATEST Technology adopted
Conclusion
NTPC VISION
NTPC HAS TO BECOME A 1,28,000 MW COMPANY BY 2032
45,548 MW (Including JV’s)
COAL :38,654MW
HYDRO:5984 MW
GAS:1000MW RENEWABLE:100MW
INSTALLED CAPACITY
NTPC GROUP ACCOUNTS FOR 16% OF INDIA’S TOTAL INSTALLED CAPACITY AND 25% OF ALL INDIA
GENERATION AS ON 31.03.2015
SUSTAINABLE DEVELOPMENT:A LONG JOURNEY
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
FORCED OUTAGE : A MAJOR CHALLENGE
BTL
START UP DEVIATIONS
OVERHEATING/CORROSION
WELD FAILURES
FLUE GAS EROSION
CHEMICAL PARAMETER DEVIATIONS
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
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
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
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
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
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
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
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
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
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 / DIVISIONAL 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
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 WELD FAILURE
Cleat welding being done..
Random DP near cleat area.
ACTION PLANS FOR ZERO BTL
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
ECONOMISER
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
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
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.
LATEST TECHNOLOGIES ADOPTED
ASLD(ACOUSTIC STEAM LEAK DETECTORS)
PADO
PI SYSTEM
SCADA
FLAME CAMERAS
ACOUSTIC PYROMETERS
