1 BYU Deposition Facility Previous Turbine Accelerated Deposition Facility (TADF) Design Parameters...
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Transcript of 1 BYU Deposition Facility Previous Turbine Accelerated Deposition Facility (TADF) Design Parameters...
1
BYU Deposition FacilityPrevious Turbine Accelerated Deposition Facility (TADF)
• Design Parameters to match: temp, velocity, angle, materials, particle size, chemistry, and concentration
• Inconel construction allows max jet temperature of 1200C
• Exit velocities up to 300m/s – deposition by inertial impaction
• Target coupons supplied from industry
• Capability for impingement and film cooling
• Match net particle throughput
8000 hrs 0.1 ppmw ≈ 4 hrs 200 ppmw
CoolingAir In
CoolingAir Out
Coupon Holder
Equilibration Tube
Flow Acceleration Cone
Natural Gas Injection(2 of 8 shown)
Natural Gas In
Honeycomb FlowStraightener
Particulate Feed Tube
Main Air In
Particulate andBypassed Air In
Quartz Viewport
Viewport PurgeAir In
Cone-mountedThermocouple
Exit FlowThermocouple
Probes
BYU Coupon Holder
Deposit-laden combustor exhaust
gas @1200C
25 mm diameter TBC-coated
target coupon
Radiation Shield
CoolantEntrance
Cap
Deposit-laden combustor exhaust
gas @1200C
25 mm diameter TBC-coated
target coupon
Radiation Shield
CoolantEntrance
Cap
Cooling Air
ThermocoupleCoupon w/cooling holes
Deposit-ladencombustor exhaust
at 1183CCoupons generally held at 45 angle to flow
Deposit-ladencombustor exhaust
at 1183C
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BYU – Previous TestingDeposition vs. Temperature
• Deposition increases with gas exit temperature
• Insulated tests conducted up to 1150C (i.e., no cooling)
• No deposition below ~950C
Deposition vs. Cooling• Deposition decreases with increasing
coupon cooling• backside cooling• film cooling on surface
10
8
6
4
2
0
Cap
ture
Effi
cien
cy (%
)
5.04.03.02.01.00.0
Blowing Ratio (M)
TBC Bare Metal
3
4
Goal 1:Increase gas temperatures to 1400C
Why?• Mimic H class turbine gas temperatures• Investigate mechanism changes at higher temperatures
• Gas temperature affects particle melting
• Surface temperature affects deposit stickiness & tenacity• Examine deposition threshold temperatures with realistic
blowing ratios• Existing experiments cool surface too much with M=2• Distinguish sweeping effect from surface cooling effect
How?• Build new shell
• Reaction Bonded SiC• Price ~$4500
• Modify coupon holder• New design• Insulate front face
1500
1400
1300
1200
1100
1000
900
800
Gas
Tem
per
atu
re (
°C)
12001150110010501000950900850800
Surface Temperature (°C)
Temperature Range
New Range
Previous rangeof experiments
5
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BYU – Facility Modification
Redesign For 1400CCone and Tube
Reaction bonded SiC (previously Inconel)
New Max Operating Temp = 1500CNo problems with thermal shock on startup and shutdown
New Cone and TubeConnection to base
1.2 m
I.D. = 2.5 cm
SiC Cone
ClampingRing
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BYU – New Coupon Holder
Redesign For 1400CCoupon Holder
Insulating front plate made of SiO2
Redesigned front side to allow insulation to be flush with coupon
Old Holder New Holder plus SiO2 faceplate
Gas Flow
Gas Flow
Test coupon
Inconel Holder
Tube exit
SiO2 Face Plate
Test Coupon
Deposits in Tube
• Deposits build up in the tube over successive runs
• Less ash impacts the coupon• Affects capture efficiency
• Some tests were performed after large amounts of buildup occurred
• Data points considered outliers
• Solution:• Routine cleaning of tube
Deposits
8
Correcting for Ash Deposition in Tube
• Measured mass of deposit in SiC tube– When accounting for the mass deposited in the tube, the
capture efficiencies of the new facility match those of the old facility
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Capture Efficency vs. Temperature
0
1
2
3
4
5
6
7
8
9
1040 1060 1080 1100 1120 1140 1160
Temperature (degC)
Ca
ptu
re E
ffic
ien
cy
(%
)
New
Old
Corrected
Recent Results
• Time-Dependent Test Series• A test series investigating the time-dependent
nature of deposit growth was performed• Tests conducted for 20, 30, 40, and 60 minutes• Tg = 1250°C
• Capture efficiency, surface roughness (Ra), and deposit thickness are measured and calculated with respect to time
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Recent Results - 1250°CSubbituminous Coal Flyash
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50
40
30
20
10
0Tub
e C
aptu
re E
ffici
ency
(%
)
6050403020100
Time (min)
13 micron 4 micron
800
700
600
500
400
300
200
100
0
Ra
(um
)
6050403020100
Time (min)
13 micron 4 micron
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7
6
5
4
3
2
1
0
Dep
osit
Thi
ckne
ss (m
m)
6050403020100
Time (min)
13 micron 4 micron
20
15
10
5
0
Cap
ture
Effi
cien
cy (%
)
6050403020100
Time (min)
13 micron 4 micron
Equilibration TubeCoupon
Recent Results
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Wyoming Powder River Basin Coal Flyash1250C
Recent Results
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• Began temperature-dependent series• Investigate the influence of gas temperature (Tg)
on deposition• Vary Tg (1250°C - 1400°C) while using backside
cooling to keep the initial surface temperature constant
• Only completed a few tests and low end of Tg range
• Using flyash samples from bituminous and subbituminous coals
Recent Results
14
Subbituminous Bituminous
Conclusions
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• Results from the new SiC facility compare well with results from the old inconel facility
• Surface roughness and deposit thickness both increase linearly with time at a given gas temperature while capture efficiency increases non-linearly
• Ash composition affects the manner in which ash deposits on the surface• bituminous (higher melting point) deposits less
evenly and depends more on a localized activation point