OptimisingOptimisingOptimisingOptimising Power Generation Maintenance using Power Generation Maintenance using Power Generation Maintenance using Power Generation Maintenance using Thermal and CFD modellingThermal and CFD modellingThermal and CFD modellingThermal and CFD modelling
• Warwick Ham
• Boiler Process Engineering Group Leader
• Steinmüller Africa, Bilfinger Power Systems
• South Africa
Summary
• Introduction• Failure statistics• How to improve availability• Using CFD to understand the real causes• Record keeping• Don’t just fix it – Change it!
Introduction
Superheater/Reheater
Feedwater
System
Condenser Cooling Tower
Generator
Stack
Heat- Recovery
System
FGD - Fan
Steam Turbine
Air Preheater
ID - Fan
DeNOx - SCR
Precipitator
De-Ashing
Economizer
Steam Generator
Ash Silo
De-Ashing
Mill
Firing Systems
Coal/Oil/Gas
FD - Fan
FGD
Coal Feeder
HP - Pipes
Introduction
• The Coal Fired Power Generation Cycle
Failure Statistics• The most common types of Failures
– Fatigue– Corrosion Fatigue– Fly Ash Erosion– Falling Object
Damage
0
2
4
6
8
10
12
14
16
18
Num
ber
of B
TF
s
X Power Station - BTF Mechanism
2006
2007
2008
2009
2010
2011
2012
Failure Statistics
• Fly Ash Erosion Failure Locations– Economiser– Reheater– Helical Wall– Division Wall
0
2
4
6
8
10
12
14
16
18
EconomiserDivision wallScrew wallVertical wallSuper heater 1Superheater 2Superheater 3Reheater 1Reheate r 2
Num
ber
of B
TF
s
X Power Station - BTFs per Component
2006200720082009201020112012
Failure Statistics• The most common Fly Ash
Erosion Causes– Operation outside of design
envelope• Excessive startups/shutdown• High ramp rates• Excessively high load
– Operation outside fuel envelope• High Ash• High Moisture• Low CV
– Erosion• High flue gas velocity
Improve Availability – How?• Design
– Realistic specifications
• Operation– Procedures
• Maintenance– Adjust maintenance philosophy to actual
operating conditions
• Understand the mechanisms– System thinking– Detailed CFD investigations
Using CFD – Understanding
• Mill Wear
• Boiler erosion– Pressure Parts – Non Pressure Parts
• Manufacturing Quality
Using CFD – Understanding
• Mill Wear (Video)– Excellent agreement between CFD prediction and actual wear
patterns
Using CFD – Understanding
• Mill Wear– Excellent agreement between CFD prediction and actual wear
patterns
Using CFD – Understanding
• Mill Wear– Improved design
Using CFD – Understanding
• Boiler erosion– Pressure Parts
Using CFD – Understanding• Boiler Pressure Part Erosion
• Localisation• Erosion Rate
Using CFD – Understanding
• Boiler Non Pressure Part ErosionLocalisedRate
Using CFD – Understanding
• Boiler Non Pressure Part Erosion
Using CFD – Understanding• Maintenance Manufacturing Quality
– Spherical header
Using CFD – Understanding
• Manufacturing Quality– Heat treatment
• Spherical header• Heat treatment
procedure
Record keeping – the key• Design records
– Basis• Fuel Range• Operating mode• Lifetime
– Original design assumptions
– Modifications• Maintenance
experience
Record keeping – the key
• Operating records– Procedures
• Maintenance records• Failure RCA
0
2
4
6
8
10
12
14
16
18
Poor workmanship Poor operating Design defect Modifica tion defect Ageing Unknown
Num
ber
of B
TF
s
X Power Station - BTFs Root Cause
2006
2007
2008
2009
2010
2011
2012
Don’t just fix it – Change it!
• Assess original design intent against actual conditions
• Challenge assumptions• Assess operating procedures• Assess maintenance trends• Understand the causes• Develop new design basis
Summary
• Introduction• Failure statistics• How to improve availability• Using CFD to understand the real causes• Record keeping• Don’t just fix it – Change it!
