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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

pera

ture

(°C

)

12001150110010501000950900850800

Surface Temperature (°C)

Temperature Range

New Range

Previous rangeof experiments

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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 HolderRedesign 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

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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

0123456789

1040 1060 1080 1100 1120 1140 1160

Temperature (degC)

Cap

ture

Eff

icie

ncy

(%)

NewOldCorrected

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

0Tube

Cap

ture E

fficien

cy (%

)

6050403020100Time (min)

13 micron 4 micron

800700600500400300200100

0

Ra (u

m)

6050403020100

Time (min)

13 micron 4 micron

876543210

Depo

sit T

hickn

ess (

mm)

6050403020100Time (min)

13 micron 4 micron

20

15

10

5

0

Captu

re E

fficien

cy (%

)

6050403020100Time (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

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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