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BYU Deposition Facility. Previous 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 1200 C
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BYU Deposition Facility Previous 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 1
BYU Coupon Holder Cooling Air Coupon w/cooling holes Thermocouple Deposit-ladencombustor exhaustat 1183C Deposit-ladencombustor exhaustat 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 • Deposition decreases with increasing coupon cooling • backside cooling • film cooling on surface 3 3
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 New Range Previous range of experiments 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 New Cone and Tube Connection to base 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 Gas Flow Test coupon 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 • 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 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 = 1250°C • Capture efficiency, surface roughness (Ra), and deposit thickness are measured and calculated with respect to time 10
Recent Results - 1250°CSubbituminous Coal Flyash Coupon 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 (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 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 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 15