Center of research on energy resources & consumption
First Results of an Oxyfuel Combustion Fluidized Bed Luis M Romeo (
[email protected]), Isabel Guedea, Irene Bolea, Ana Gonzalez, Carlos Lupiañez, Javier Pallares, Enrique Teruel, Luis I. Diez
1st OXYFUEL COMBUSTION CONFERENCE, Cottbus, Germany, September 2009
Center of research on energy resources & consumption CIRCE description. Team:
Laboratories: Biomass/coal combustion Oxyfuel combustion CFB looping
Center of research on energy resources & consumption CIRCE description • non-profit private organisation, sponsored by
Utility
Mining
Educational
Government
R&D in energy and thermal and electrical engineering experience in coal & biomass combustion, plant tests & monitoring, laboratory work, simulation, CFD, conventional (PF) and advanced (FBC, IGCC, co-firing) concepts, CO2 capture
Center of research on energy resources & consumption
INDEX CIRCE description Background and objectives Test facility description Test results Conclusions and future work
Center of research on energy resources & consumption Background and objectives 2006 Spanish Science Ministry R+D Call (Energy) (2006-2008) Analyse the technical feasibility of the OXYCO-FIRING technology Co-firing of coal and biomass. Design, construction and start-up a pilot-scale rig (around 100 kWt) Searching an adequate compatibility among traditional fossil fuels and renewable resources (biomass). Blends of coal and biomass
2009, 2010 Spanish Science Ministry R+D Call (Energy) Technical feasibility of high sulphur/low rank coal oxyfuel combustion
CIUDEN (2009-2011) Perform tests in fluidized bed oxyfuel combustion Process simulation
Other projects under evaluation
Center of research on energy resources & consumption Test facility description 90 kWt O2/CO2 bubbling fluidized bed 2.7 m height, 20 cm i.d. FB water-cooled 2 x 200 litres hoppers for fuel feeding (coal, sorbent, biomass) CO2/O2 mixer and flue gas recirculation Preheating of fluidising gas Gas cleaning: cyclone and fabric filter Recycling ratio: from 0% to 80% O2 in the mixture: from 20% to 60%
CO2 recirculation Coal + Biomass O2 Air Separation Unit (ASU)
Air
Electric Power
Flue gases CO2, H2O,...
CO2 Compression and dehydration
CO2 transport and storage
Center of research on energy resources & consumption Test facility description Ciclón Cyclone Lecho fluido Fluidized bed
Intercambiador Heat de exchanger calor
burbujeante
Start-up
Quemador de burner gas
Chimenea
Stack
Sistema de CO2/O2 feeding alimentacion del system comburente
Sistema de Fuel feeding alimentación de system combustible
Ventiladores Fans Filtro Fabricde mangas
Filter
Aero
Cooling system refrigerador
Center of research on energy resources & consumption Test facility description 90 kWt O2/CO2 bubbling fluidized bed
Center of research on energy resources & consumption Test facility description
Center of research on energy resources & consumption Test facility description Initial test plan Coal types
Anthracite, Spanish lignite, …
Biomass
depending coal
Bed temperature
750ºC-825ºC-900ºC
CO2/O2 concentration at inlet
80-40 % / 20-60%
Recirculation ratio
0-80 %
Ca/S molar ratio
1.5-2.1
Coal particle diameter
700/1200 μm
Limestone particle diameter
500/1000 μm
Oxygen in flue gases
3-6 %
Fluidization velocity
0.7-1.0 m/s
Center of research on energy resources & consumption Test Results First tests Low volatile anthracite (57% C; 35% ash; 6% volatile; 2 % moisture; LHV 21400 kJ/kg). Particle diameter coal and limestone around 500 μm. 14 test: 9 air test y 5 oxyfuel test
Air: Typical values of 10% CO2 in flue gases (up to 18%). High CO (1200 ppm) and O2 concentrations Bed temperatures: 800-850ºC; Bed height: 0.5-0.6 m; Fluidization velocity: 0.4-0.7 m/s Poor fluidization and low combustion efficiency: Coal type Increase air mass flow (fluidization velocity). Change coal type
Center of research on energy resources & consumption Test Results Oxyfuel: Similar problems with low combustion efficiency and fluidization Increasing O2 concentration at inlet (40%) Reduction of CO concentration in flue gases (800 ppm) Increase of combustion efficiency and CO2 concentration in flue gases 80,00
900 CO2 concentrations higher than 75%
70,00
880 860
Change in flue gas analizer channel. 40% O2 at inlet
840
60,00
820
Change air-oxyfuel
800
50,00
780
Change oxyfuel-air
CO2 760 O2 740
40,00 30,00
FLUE GAS CONCENTRATIONS
720 700
BED TEMPERATURES
680
20,00
660 12:04
10,00
640
11:44 0,00 2000
2100
2200
2300
2400
620 2500
2600
2700
2800
2900
3000
600 2000
2100
2200
2300
2400
2500
2600
2700
2800
2900
300
Center of research on energy resources & consumption Test Results (last tests) Even combustion behaviour 20% CO2 and 4-8% O2 concentration with air 87% CO2 and 5-10% O2 concentration with oxyfuel 70-30% CO2-O2 concentration an inlet 760-870ºC bed temperatures 100
950 900
750
60
700
50
650
40
600
30
550
20
OXYGEN in flue gas, % ->
10
500 450 2210 0
2270 5
2330 10
2390 15
245020
251025
minutes
0 257030
Center of research on energy resources & consumption Test Results Main oxyfuel problems: Fluidization problems and control (pressure) of flue gas recirculation SINTERING Only in oxyfuel tests (3/5), maximum temperatures around 870ºC Bed agglomeration. Broken in small pieces Bed sintering. Harder and larger than agglomerate.
Center of research on energy resources & consumption Test Results Sintering
Center of research on energy resources & consumption Test Results Sintering
Center of research on energy resources & consumption Test Results
SEM3‐1 18 16 14 12 10 8 6 4 2 0 O
Na
Al
Si
S
K
Ca
Ti
SEM3‐2
2 mm
O (13.8%) Si (21.2%)
Mg
O (15.5%) Al (7.5%) Si (9.1%) Ca (9.4%)
16 14 12 10 8 6 4 2 0 O
Na
Mg
Al
Si
Fe
S
K
Ca
Ti
Fe
O (15.2%) Ca (11.0%) Si (9.6%) K (3.0%) Al (4.5%) Fe (2.6%)
CaSO4 Layer
Center of research on energy resources & consumption Conclusions and future work First tests of fluidized bed oxyfuel combustion Start-up problems solved Sintering and low combustion efficiency (coal and fluidization) Last tests show better fluidization and combustion
Future Test different coal types Avoid sintering and increase combustion efficiency Reduce fluidization problems
Analyse: O2-staging In-bed residence time Fouling. Deposition probe CO2/O2 ratio vs. air combustion. Flue gas recirculation
