BYU Deposition Facility Previous Turbine Accelerated Deposition Facility (TADF) Cooling Air In Design Parameters to match: temp, velocity, angle, materials, particle size, chemistry, and concentration Cooling Air Out Coupon Holder Exit Flow Thermocouple Probes Equilibration Tube Flow Acceleration Cone Cone-mounted Thermocouple Natural Gas Injection (2 of 8 shown) Viewport Purge Air In Quartz Viewport Natural Gas In Particulate and
Bypassed Air In Honeycomb Flow Straightener Main Air In Particulate Feed Tube 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 1 BYU Coupon Holder Cooling Air Cap Coolant Entrance Radiation Shield Coupon w/cooling holes Thermocouple
25 mm diameter TBC-coated target coupon Deposit-laden Deposit-laden combustor exhaust combustor exhaust gas @1200C at 1183C Deposit-laden combustor exhaust at 1183C Coupons generally held at 45 angle to flow 2 BYU Previous Testing Deposition 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 10 6 4
2 0 0.0 3 TBC Bare Metal 8 Capture Efficiency (%) Deposition decreases with increasing coupon cooling backside cooling film cooling on surface 1.0 2.0 3.0 Blowing Ratio (M) 4.0 3 5.0
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 4 Temperature Range 1500 Gas Temperature (C) 1400
New Range 1300 1200 1100 Previous range of experiments 1000 900 800 800 850 900 950 1000 1050 1100 1150 1200 Surface Temperature (C)
5 BYU Facility Modification I.D. = 2.5 cm Redesign For 1400C Cone and Tube Reaction bonded SiC (previously Inconel) New Max Operating Temp = 1500C No problems with thermal shock on startup and shutdown 1.2 m Clamping Ring SiC Cone Connection to base New Cone and Tube 6 BYU New Coupon Holder Redesign For 1400C Coupon Holder Insulating front plate made of SiO2 Redesigned front side to allow insulation to be flush with coupon SiO2 Face Plate
Inconel Holder Test coupon Gas Flow Test Coupon Gas Flow Tube exit Old Holder New Holder plus SiO2 faceplate 7 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 Deposits Data points considered outliers
Solution: Routine cleaning of tube 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 Capture Efficiency (%) Capture Efficency vs. Temperature 9 8 7 6 5 New Old Corrected 4 3 2 1 0 1040 1060
1080 1100 1120 1140 1160 Temperature (degC) 9 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 = 1250C Capture efficiency, surface roughness (Ra), and deposit thickness are measured and calculated with respect to time 10 Recent Results - 1250C Subbituminous Coal Flyash 700 600 8 Deposit Thickness (mm)
10 20 30 40 50 60 Time (min) Equilibration Tube 11 Recent Results Wyoming Powder River Basin Coal Flyash 1250C 12 Recent Results Began temperature-dependent series Investigate the influence of gas temperature (Tg) on deposition Vary Tg (1250C - 1400C) 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 13 Recent Results Subbituminous Bituminous 14 Conclusions 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 nonlinearly 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 15
Take a look at ThinkIB…all of the studies should be shared with you. ***If it were me, I would look to studies that cover multiple Learning Outcomes, OR a topic you find more interesting than others***
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