6 hesselman large scale combustion testing at schwarze pumpe and b&w – bright stable flame •...
TRANSCRIPT
![Page 1: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/1.jpg)
Lecture 6: Large Scale Combustion TestingBurners / Test Methods
G HesselmannAPP OFWG Capacity Building Course5th & 6th February 2009, Daejeon, Korea
![Page 2: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/2.jpg)
Burner Technology – Air Firing
• Modern low NOx coal burners operate on the principle of air staging
– Coal is rapidly heated in an oxygen deficient region
– Fuel nitrogen reactions favour the formation of N2 (instead of NOx) where there is low O2 availability
– Main combustion air is added sequentially to complete burnout
• Stabilisation is predominantly by aerodynamic measures
– Swirled air streams create a strong internal recirculation zone that draws hot gases into the burner quarl
![Page 3: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/3.jpg)
Burner Design Considerations
• The burner should perform in such a way that the overall combustion efficiency is high (typically less than 5% CIA, 99.8% burnout)
• Flame length and shape should be appropriate for the furnace
• Flame stability limits should be “robust” – e.g. the flame should typically be stabilised in the burner quarl at all normal operating conditions
• Turndown performance should not impact plant operability – typically burners should be able to operate at 40% of design capacity without oil support
• The flame itself should have an overall oxidising envelope to minimise the potential for high temperature corrosion at the furnace walls
• Performance of the burner should be acceptable for a wide range of coals covering the typical range of supply to pulverised coal fired utility plant
![Page 4: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/4.jpg)
Doosan Babcock Mk3 Low NOx Axial Swirl Burner
Core Air
Primary Air and Pulverised Coal
Secondary Air
Tertiary Air
Over 3000 (45GWe) Doosan Babcock Mk3 low NOx burners installed worldwide
![Page 5: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/5.jpg)
Burners for Oxyfuel Firing
• “Simulated Air” Burners– Basic design is the same as for air firing, but the comburrant (air) is replaced by a mixture
of nearly pure oxygen and recycled flue gas– Primary air conditions are constrained by the milling plant
• Gas velocities in the pulverising mill must be high enough to convey the coal• O2 content has an upper limit (21%) to minimise risk of mill fires
– Simulated air burners are likely to be the first to be installed in large utility plant
• Oxyfuel Burners– Design allows for direct injection of O2 via (for example) lances
![Page 6: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/6.jpg)
Pilot Scale Oxyfuel Burner
Pulverised CoalPrimary FGRPrimary O2
Secondary O2
Secondary FGR
![Page 7: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/7.jpg)
Oxyfuel Burner Experience
• Simulated Air– Some experience of large (30MWt, ¾ scale)
burners at Schwarze Pumpe and B&W– Bright stable flame
• Oxyfuel Burners– Coal firing experience limited to pilot scale
(typically 1MWt)– Considerable experience for gas fired oxyfuel
flames in non-utility applications, mostly lower thermal input than required for utility plant
Schwarze Pumpe
B&W
![Page 8: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/8.jpg)
Oxyfuel Burner Experience
• Experimental studies at Chalmers University (Sweden) shows the differences between air and oxyfuel firing in a simulated air burner (100kWt)
• It is important to understand flame structure in order to establish viable burner designs
– There is a need to measure key parameters in the aggressive combustion environment
CO Temperature
![Page 9: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/9.jpg)
Measurements
• Temperature• Velocity
– Absolute Values– Regions of Forward / Reverse Flow
• Gaseous Species– NOx– CO– O2
– Etc• Solid Samples
– Carbon in Ash– Nitrogen release
• Heat Flux
![Page 10: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/10.jpg)
Gas Temperature
Suction Pyrometer / High Velocity Thermocouple
![Page 11: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/11.jpg)
Gas Temperature
• Suction pyrometry is the “correct” way to measure gas temperature in furnaces
– Radiation shields are fragile– Prone to blockage
• High Velocity Thermocouples (HVT) are similar in construction, but have a simple cylindrical radiation shield
– More robust !– Need to correct measured temperature
for radiation losses – measured value is lower than actual
• Simple Unshielded Thermocouples have large radiation losses – indicative temperatures only
– Robust– Fine wire thermocouples minimise
radiation error, but are fragile
800
1000
1200
1400
1600
1800
2000
800 1000 1200 1400 1600 1800 2000
HVT Measured Temperature (C)A
ctua
l Tem
pera
ture
(C)
![Page 12: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/12.jpg)
Gas Velocity
Prandtl Probe
![Page 13: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/13.jpg)
Gas Velocity
5-Hole Pitot Tube
![Page 14: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/14.jpg)
Gas Velocity
Hubbard Probe / S-Type Pitot
![Page 15: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/15.jpg)
Gas Velocity
• Based on standard “clean air” techniques– Ruggedised for combustion environment– Generally incorporated into a water cooled probe
• Simple in principle, very difficult in practice !– Small holes in pitot type devices are prone to blockage– Absolute velocities are low (low ∆P to be measured)– Velocities tend to fluctuate widely and rapidly
• Usually the best that can be achieved is an indication of the region of reverse flow, using the S-type pitot (the most robust of the various probes available)
![Page 16: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/16.jpg)
Gaseous Species and Solid Sampling
Doosan Babcock Water Quench Probe
![Page 17: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/17.jpg)
Gaseous Species and Solid Sampling
• Water quench probe– Rapid cooling of gas/solids at probe tip freezes combustion reactions– Water flushes solids to collection vessel– Quench not needed for just gases– Can also use HVT probe for gas sampling
• Robust and reliable method
• Gases analysed using conventional CEM-type analysers– Specify appropriate measurement range– Consider interactions between species – e.g. NOx measurement error at high CO levels– Be aware of what is measured – e.g. NOx analysers convert NO to NO2 and measure NO2
to give “NOx”, but can give “NO” if the converter is turned off; they do not measure N2O
![Page 18: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/18.jpg)
Gaseous Species and Solid Sampling
Wet chemistry sampling for Ammonia
![Page 19: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/19.jpg)
Heat Flux
Total Heat Flux Probe
![Page 20: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/20.jpg)
Heat Flux
Radiant Heat Flux Probe – Ellipsoidal Radiometer
![Page 21: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/21.jpg)
Heat Flux
• Difficult to measure absolute values of total heat flux– Deposition of ash on probe acts as an insulator; indicated heat flux reduces with time– Calibration of probes is expensive – requires a black-body furnace– Useful technique to get relative measure of radiation from a flame
• Ellipsoidal radiometer– Not sufficiently robust for large coal firing applications– Blockage of “window” by particulate material– Fouling of inner surface causes calibration drift– Calibration of probes is expensive – requires a black-body furnace
![Page 22: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/22.jpg)
Emerging Technologies
T O2 CO
Laser Tomography
![Page 23: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/23.jpg)
Emerging Technologies
• Multiple laser paths cross the measurement domain, arrange for paths to intersect• Laser measurement of average property along path
– Temperature– O2,CO, CO2, H2O– Self-calibrating– Semi-continuous
• Mathematical analysis generates profile
• Many practical issues– Laser alignment– Attenuation of laser signal due to particulate material– Not demonstrated for in-flame measurements
![Page 24: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/24.jpg)
Emerging Technologies
• Aggressive atmospheres (CO, H2S, molten ash) can lead to high rates of metal loss
• Oxyfuel combustion has the potential to create an environment that is more corrosive than for air firing
– Higher levels of CO– Higher levels of H2S– Higher peak temperature
Wall Corrosion
![Page 25: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/25.jpg)
Emerging Technologies
Corrosion ProbeSniffer Port
Probe Tip
CL
CL
CL
HOT GAS SIDE
1 ¼” 1 ¼”
3”
CL
CL
CL CL
CL
COLD SIDE
ThreadedTapping
6 mmMembrane
Thermocouple Guide
WeldInlay
Probe Tip
CL
CL
CL
HOT GAS SIDE
1 ¼” 1 ¼”
3”
CL
CL
CL CL
CL
COLD SIDE
ThreadedTapping
6 mmMembrane
Thermocouple Guide
WeldInlay
Probe Tip
Wall Corrosion / Sniffer Port
Long term corrosion tests on large boiler plantMeasure gaseous species at wall, and metal loss from test coupon
![Page 26: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/26.jpg)
Practical Issues
Furnace Measurements – Practical Considerations
• Restricted Access– limited access points,– restricted space– limited galleries– movement of equipment
• Environmental conditions– Dust / Fume– Temperature– Noise– Light
• Services– Power– Cooling water– Compressed Air
![Page 27: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/27.jpg)
Practical Issues
![Page 28: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/28.jpg)
Practical Issues
Probe Handling
Photo’s show probing gallery on Doosan Babcock’s test facility – probes are typically 6m to 10m long, 75mm diameter, stainless steel, water filled – i.e. heavy. Issues for manual handling.
![Page 29: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/29.jpg)
Safety
• Access/Egress• Multi - level Working• Fall of Person/Objects• Slips and Trips• Confined Space• Restricted Means of escape/rescue• Contact with Process• Electricity• Fire + Explosion• Vibration• Lifting Operations• Vehicles• Manual Handling
• Mobile or Fixed Plant• Adjacent Live Plant or Equipment• Environmental• Weather• Temperature• Lighting• Noise• Hazardous Substances• Asbestos• Dust / Fume• Lone Working• Interfacing with Third Parties
![Page 30: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/30.jpg)
Safety
• Pre-Test Site Visit– Know what to expect when you arrive on site
• Risk Assessment – review on arrival– Assess hazards, and identify mitigation– Review – things are likely to have changed between your pre-test visit and testing
• Method Statement– Define clearly what procedures you are going to follow
• ‘Toolbox Talk’– Ensure that all members of the test team know what the hazards are, what to do in an
emergency, etc
![Page 31: 6 Hesselman Large Scale Combustion Testing at Schwarze Pumpe and B&W – Bright stable flame • Oxyfuel Burners – Coal firing experience limited to pilot scale (typically 1MWt)](https://reader031.vdocuments.net/reader031/viewer/2022022503/5aaf82b37f8b9a6b308d658e/html5/thumbnails/31.jpg)
Useful References
• Chedaille & BraudIndustrial Flames. Volume 1. Measurements in Flames.International Flame Research Foundation (IFRF)ISBN 0 7131 3265 5
• ICT Quick reference GuideInnovative Combustion Technologies Incwww.innovativecombustion.com
• Risk Assessment Guide – Industrial Emission MonitoringSource Testing Associationwww.S-T-A.org