Fundación Ciudad de la Energía Ponferrada 9 th to 13 th September 2013 Organised by: Hosted by:
NOx emissions experiences in a 30 MWth Circulating Fluidized Bed boiler under oxy combustion conditions Manuel Gómez a, Jesús Ramos a, Benito Navarrete a, Francisco Muñoz a, Beatriz Gil a, Pedro Otero a, Reijo Kuivalainen b, Teri Hiltunen b a Fundación Ciudad de la Energía, II Avenida de Compostilla, nº 2, Ponferrada (León), 24404, Spain b Foster Wheeler Energia Oy, Relanderinkatu 2, FI-78201 Varkaus, Finland
NO x Types Thermal Fuel Prompt NO x = NO + NO 2 N 2 O as separate component
Objective Study of NO and N 2 O emissions at s 30 MWth CFB installation working under both air and oxycombustion conditions
Experimental Installation FLY ASH SILO LIMESTON E SILO AMMONIA TANK FLY ASH FEEDING SYSTEM BOILER FEED WATER FUE GAS FLY ASH RECIRCULATION LIMESTONE SAND FUEL FEED SAND SILO FUEL SILO LIMESTONE FEEDING SYSTEM SAND FEEDING SYSTEM FUEL FEEDING SYSTEM FLY ASH SYSTEM MIXER MIXER MIXER PRIMARY OXIDANT FAN SECUNDARY OXIDANT FAN PRIMARY OXIDANT SECUNDARY OXIDANT NATURAL GAS START-UP BURNER SKID OXYGEN BOTTOM ASH
Instrumentation O 2 NO/N 2 O measurement Cyclon+Bag Filter AIR FLUE GAS RECIRCULATION
Stability Period bed temperature (ºC) STABLE O 2 excess (vol.% wet basis) Steam flow (kg/h) PERIOD flue gas flow (kg/h) SO 2 (ppmv) coal flow (t/h)
NO/N 2 O determination Bed Temperature NO N 2 O
Operating variables influencing NO and N 2 O emission Temperature Limestone addition Load Oxygen content in the oxidant (FGR ratio) Primary/secondary oxidant distribution
Fuel 1- Anthracite Proximate analysis (wt. %) Moisture content (as 4.95 received) Ash (dry basis) 34.14 Volatiles (dry basis) 7.57 Fix carbon (dry basis) 58.28 Ultimate analysis (wt. % dry basis) C 58.27 H 1.95 N 0.79 S 0.98 HHV (Kcal/kg, wet basis) 5040
Testing conditions Air/oxy modes Different bed temperatures Different limestone injection rates High load operation 3-5 excess oxygen (vol. % db) Primary/secondary oxidant ratio = 0.8-0.9 (exceptionally 0.6-0.7)
300 300 250 250 AIR OXY NO ppmv wet 200 150 100 50 200 150 100 50 0 840 860 880 900 920 940 Temperature ( C) 0 1 2 3 4 Ca/S molar ratio
300 300 250 250 AIR OXY N 2 O ppmv wet 200 150 100 50 200 150 100 50 0 840 860 880 900 920 940 Temperature ( C) 0 1 2 3 4 Ca/S molar ratio
Fuel 2- Blend: Anthracite/Petcoke (70/30 % weight) Proximate analysis (wt. %) Moisture content (as 4.83 received) Ash (dry basis) 24.65 Volatiles (dry basis) 8.05 Fix carbon (dry basis) 67.30 Ultimate analysis (wt. % dry basis) C 66.29 H 2.42 N 1.06 S 2.24 HHV (Kcal/kg, wet basis) 8381
Testing conditions Air/oxy modes Different bed temperatures Different limestone injection rates High load operation 3-5 excess oxygen (vol. % db) Primary/secondary oxidant ratio = 0.80-0.90 (exceptionally 0.6-0.70)
300 300 250 250 AIR OXY NO ppmv wet 200 150 100 50 200 150 100 50 0 840 860 880 900 920 940 Temperature ( C) 0 1 2 3 4 Ca/S molar ratio
300 300 250 250 AIR OXY N 2 O ppmv wet 200 150 100 200 150 100 50 50 0 840 860 880 900 920 940 Temperature ( C) 0 1 2 3 4 Ca/S molar ratio
NH 3 injection 25 % weight water solution Oxy-combustion conditions Limestone injection 3-5 % excess oxygen (vol. % db) Different bed temperatures Primary/secondary oxidant ratio = 0.8-0.9 (exceptionally 0.6 0.7)
NH 3 injection Selected point
NO ppmv wet 300 250 200 150 100 50 T = 920 T = 904 T = 892 T = 890 T = 888 T = 865 0 0 2.3 3.4 4.6 Kg NH 3 /h T = 855
N 2 O ppmv wet 300 250 200 150 100 50 0 0 2.3 3.4 4.6 T = 920 T = 904 T = 892 T = 890 T = 888 T = 865 T = 855 Kg NH 3 /h
Preliminary Conclusions NO dominates NO x emission NO emission increases with temperature increase N 2 O emission decreases with temperature increase NO emission increases with limestone addition increase High limestone addition rates do not affect N 2 O emission NH 3 injection decreases NO emission NH 3 injection does not affect N 2 O emission
Future research work Validation of these preliminary results Influence of operating conditions Heterogeneous reactions (solid-gas phases) Other fuels. Same behaviour?
Acknowledgement The work presented is co-financed under the FP7 FLEXIBURNCFB and the EEPR09-CCS- COMPOSTILLA projects. The European Union is not responsible for any use that may be made of the information contained therein.
THANK YOU VERY MUCH FOR YOUR ATTENTION For further information, please contact Manuel Gómez, manuel.gomez@ciuden.es