Modelling of Biomass Combustion in Fluidised Beds tai...
Transcript of Modelling of Biomass Combustion in Fluidised Beds tai...
• Energy Technology
• Electrical Engineering
• Environmental Engineering
BIOMODELLING
Modelling of Biomass Combustion in
Fluidised Beds
Timo Hyppänen
Lappeenranta University of Technology
14.1.2010
14.1.20101
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• Environmental Engineering
Content of the presentation
• ERA-NET Project Background
– Goals, benefits
– Organisation
– Work plan
• CFB modeling
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• Environmental Engineering
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Background
• Need to develop environmentally sound ways to
increase utilization of biomass in energy production
• ERA-NET Bioenergy is a network of national R&D
programmes focusing on bioenergy
– Joint call on clean biomass combustion
– Modeling of the combustion process
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Project goals
• Goal is to develop and improve the modelling methods
for biomass combustion in circulating fluidised bed
(CFB) boilers
– fluidization behavior
– combustion properties
– emissions formation
– heat transfer
• Improved models for biomass combustion
• Models enable more accurate development, design and
analysis of CFB boilers utilizing biomass.
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Benefits
• Increased
– capability of using renewable energy
– boiler performance
– efficiency
– availability
• Reduced emissions
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ERANET PROJECT PARTNERS
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• Czestochowa University of Technology, Faculty of
Environmental Engineering and Protection
• Chalmers University of Technology, Department of Energy
and Environment, Division of Energy Technology
• VTT Technical Research Centre of Finland
• Foster Wheeler Energia Oy
• PGE Turow Power Plant
• Lappeenranta University of Technology, LUT Energy
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• Environmental Engineering
• Energy Technology
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PGE Elektrownia Turów S.A.
( Polish Energy Group, Turow Power Plant)
3 x 235 MW CFB hot cyclone
3 x 261 MW CFB compact
Lignite & biomass
BIOMODELLING
•TUROW is a largest CFB utility company
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ERANET PROJECT WORK PLAN
14.1.20108
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• Environmental Engineering
Modelling CFB Fluid Dynamics and
Thermal Behaviour
•Flow of solids and gases
•Fractional material
balances
•Combustion of fuel
•drying
•devolatilization
•char combustion
•Heat transfer
•Gaseous reactions
•Emissions (SOx, NOx)
Reh, L. (2003). China Particuology Vol. 1, No. 5, 185-200.
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O2
Sec.
air
CO
Fuel
TemperatureReh, L. (2003). China Particuology Vol. 1, No. 5, 185-200.
Min
Max
Modelling CFB Fluid Dynamics and
Thermal Behaviour
• Energy Technology
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• Energy Technology
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Modelling of CFB fluid dynamics
•CFD multiphase modelling challenging for CFB
combustion cases (reliability/speed)
•Mass balances must be valid
•Semiempirical model used for averaged flow profiles
– Gas: Momentum equation with drag force
dominating
– Solids: First order model to produce experimental
profiles, potential flow principle
•Mixing of solids and gases is due to nonstationary
and small scale flow structures => Dispersion model
•CFD getting closer to be utilised
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3-D Model Description
• Steady-state combustion model for CFB furnace.
• Fractional material balances of solids.
• 3-D flow modelling of solid and gaseous species.
• 3-D modelling of energy balance.
• Submodels required in balance models.
• fluid dynamics of solid materials and gases
• combustion (drying, devolatilization, char
combustion)
• gaseous reactions
• comminution of solids
• heat transfer
• emission models for SOx and NOx
• Energy Technology
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• Environmental Engineering
• Energy Technology
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CFB3D Model Frame
Fuel, limestone,
make-up
Secondary airs
Gas and solids from outlets
Separator(s)Flue gas, fly ash
Solids
External heat
exchanger(s)
Solids to return leg(s)
Flue gas / fly ash recirculation
Solids,
gas
Furnace outlets
Heat transfer
to wallsCombustion
& other reactions
Heat transfer
within bed
Bottom ash
Primary air
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Three dimensional furnace model
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Example of CFB3D model results.
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Methods – laboratory equipment
Fuel particle conversion Cold models
Pilot-scale
BIOMODELLING
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nc Xkm
t
mr O2c
c
d
d
COefCO Ykt
Y
d
d
)/1/(1 mCOef kk
nrefv ddTAb )/)(/exp(
Model
analyses
CO combustion
Mixing
Char combustion
Volatile,
moist
ure re
lease
Different scales of experiments
and modelling
1D-MODELflue gas
1
n n+1
to stack
Primary airSecondary air
2
n-1
3
n-2
Bench scale Pilot scale Boiler scale
EXPERIMENTAL
SCALES
Models for
phenomena
1-D process
models
3-D process
models
MODELS AND
DESIGN TOOLS
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THANK YOU FOR YOUR ATTENTION!