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Show SCALING of FLARE FLAME EMISSIONS PRESENTED BY: JAMES SEEBOLD, CHEVRONTEXACO (Retired), Atherton, CA JOHN H. POHL, Virginia Tech/ARI Alexandria, VA PETER GOGOLEK, CANMET Ottawa, Ontario, Canada 1 SCALING REASONS • FLARES REMOTE • DIFFICULT TO SAMPLE • PILOT SCALE FLARES - MEASURED EMISSIONS - EXTRAPOLATE RESULTS • REMOTING SENSING - NEEDS VERIFICATION 2 SCALING • EFFICIENCY • RELATED TO - FLAME STRUCTURE • • • • • AERODYNAMICS STABILITY MIXING LENGTH/VOLUME LIFT-OFF DISTANCE 3 Richardson Number (gd/v2) SEEBOLD FLARE PLOT Ri versus Re Reynolds Number (pdv/u) 4 EER FTF 1-12 IN 5 EER EXP CONDITIONS • • • • • • • • NO WIND OR CONDENSATE STEAM/PILOT FLAME SIZE-1/16, 1-1/2, 3, 6, 12 INCHES TYPES- PIPE, STEAM ASSIST, CONADA, PILOT, PRESSURE, AIR ASSIST, PRESSURE MANUFACTURE-FLARE GAS,McGILL,ZINK GASES-3 IN-C3H8, NH3, C4H6, (CH2)2O, AND H2S WITH N2 V=0.22-428 FT/SEC, LHV= 41-2350 BTU/FT3, 25 GASES ON 0.042 IN-HC, HCO, CO, CL, S, N 6 OTHER • CANMET - 1, 2, 4, 6 INCHES - DILUENT GASES INCLUDING CO2 & N2 • LITERATURE - API 521 (1985) - Straitz, et al (1977, 1978) - Nobel, et al. (1984) 7 FLARE EFFICIENCY • 1-UNBURNED MATERIAL • USUALLY >98 % • CAUSED BY FLAMES WITH - FLAME SPEED < PROPAGATION V= f(Xi, T) - HEAT LOSS > HEAT RELEASE - REDUCED TEMPERATURE - RADIP MIXING, Dedd = u'l 8 SCALING BACKWARDS • COMBUSTION EFFICIENCY - RELATED TO STABILITY (EER) • 3, 6, 12 PIPES, 12 IN COMMERCIAL HEADS • LATER: 1/16, 1/8, ¼, ½, 1, 1-1/2, 2, 2-1/2 • CANMET 1, 2, 4, 6 INCH - RELATED TO FLAME STRUCTURE • • • • ENTRAINMENT RATE LENGTH VOLUME STAND-OFF DISTANCE 9 FLARE COMBUSTION EFFICIENCY HHV/MIN HHV FOR STABILITY 10 HHV (BTU/FT3) FLAME STABILITY EXIT VELOCITY (ft/SEC) 11 API FLAME LENGTH HEAT RELEASE (BTU/HR) 12 FTF DESTRUCTIONEFFICIENCY COMPARISON OF FSF AND FTF EMISSION FSF DESTRUCTION EFFICIENCY 13 14 FLARE ENTRAINMENT X/d 15 EER FSF 1/16-1/8 IN 16 CANMET 1-6 INCH Fuels: NG, Propane, liquids, inerts 17 Karlovitz (1953) STRETCH Tu=Temperature, unburned Tb=Temperature, burned N0=Distance K ( dU / dy ) * o / U No=k/CppSu 18 THREE INEFFICIENCT FLARE MODES • EXTINGUISHED BY RAPID MIXING • INCREASED SURFACE AREA - INCREASED RADIANT HEAT LOSS - INCREASED MIXING - REDUCED TEMPERATURE • • • • MASS BALANCE JET MIXING BUOYANTLY DRIVEN MIXING WAKE MIXING 19 Regime Change at a Single Site 20 INEFFICIENCT FLARES DILUTION-VECTOR FORCE BUOYANCE WIND MOMENTUM RATIO WAKE V, l, fwind Vjet 21 WAKE FLARE V ttran=l/v' t=l/V l 22 INEFFICIENCT FLARE FLAMES • EXTINGUISH BEFORE ITS TIME • DILUTION - CONCENTRATION (DILUTION) - TEMPERATURE - FLAME SPEED<SEPARATION SPEED 23 EFFICIENCY • RELATED TO - - - - FLAME SPEED MIXING EXTERNAL FORCES UTIMATELY NOZZLE SIZE> 3 INCHES 24 FLARE FLAME STABILITY DIAMETER (INCHES) 10000 1000 HHV BTU/ft3 1000 500 100 10 1 0.01 0.1 1 10 100 JHPOHL 18 FEB 04 25 DESTRUCTION EFFICIENCY (%) GAS DESTRUCTION EFFICIENCY HHV/(MINIMUM HHV FOR STABILITY) 26 MAXIMUM STABLE VELOCITY (ft/sec) AIR ASSISTED STABILITY 1/(1+(pv)air/(pv)gas 27 LIFT-OFF DISTANCE NOZZLE VELOCITY*CONC @ VMAX MAXIMUM FLAME SPEED* CONCENTRATION @ V0 28 |
