BIOMODELLING
Modelling of Biomass Combustion in
Fluidised Beds
Timo Hyppänen
Lappeenranta University of Technology
14.1.2010
• Energy Technology
• Electrical Engineering
• Environmental Engineering
1
14.1.2010
Content of the presentation
• ERA-NET Project Background
– Goals, benefits
– Organisation
– Work plan
• CFB modeling
• Energy Technology
• Electrical Engineering
• Environmental Engineering
2
14.1.2010
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
• Energy Technology
• Electrical Engineering
• Environmental Engineering
3
14.1.2010
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.
• Energy Technology
• Electrical Engineering
• Environmental Engineering
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14.1.2010
Benefits
• Increased
–
–
–
–
capability of using renewable energy
boiler performance
efficiency
availability
• Reduced emissions
• Energy Technology
• Electrical Engineering
• Environmental Engineering
5
14.1.2010
ERANET PROJECT PARTNERS
• 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
• Energy Technology
• Electrical Engineering
• Environmental Engineering
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14.1.2010
BIOMODELLING
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
•TUROW is a largest CFB utility company
• Energy Technology
• Electrical Engineering
• Environmental Engineering
ERANET PROJECT WORK PLAN
• Energy Technology
• Electrical Engineering
• Environmental Engineering
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14.1.2010
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.
• Energy Technology
• Electrical Engineering
• Environmental Engineering
Modelling CFB Fluid Dynamics and
Thermal Behaviour
Max
Sec.
air
Reh, L. (2003). China Particuology Vol. 1, No. 5, 185-200.
• Energy Technology
• Electrical Engineering
• Environmental Engineering
Fuel
O2
Min
CO
Temperature
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
• Energy Technology
• Electrical Engineering
• Environmental Engineering
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
• Electrical Engineering
• Environmental Engineering
CFB3D Model Frame
Gas and solids from outlets
Furnace outlets
Flue gas, fly ash
Separator(s)
Heat transfer
to walls
Combustion
& other reactions
Secondary airs
Heat transfer
within bed
Fuel, limestone,
Solids,
gas
Solids
External heat
exchanger(s)
Solids to return leg(s)
make-up
Primary• Energy
air Technology
• Electrical Engineering
• Environmental Engineering
Bottom ash
Flue gas / fly ash recirculation
Three dimensional furnace model
Example of CFB3D model results.
• Energy Technology
• Electrical Engineering
• Environmental Engineering
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14.1.2010
BIOMODELLING
Methods – laboratory equipment
Fuel particle conversion
Cold models
Pilot-scale
• Energy Technology
• Electrical Engineering
• Environmental Engineering
Different scales of experiments
and modelling
Bench scale
Pilot scale
Boiler scale
EXPERIMENTAL
SCALES
1D-MODEL
flue gas to stack
 v  b exp( A / T )(d / d ref ) n
MODELS AND
DESIGN TOOLS
Model
analyses
Vo
lati
le,
mo
istu
r
re
ele
Mixing
Ch
ar
com
ase
n+1
n-2

CO combustion
n
n-1
dYCO
 kef YCO
dt
k ef  1 /(1 / kCO   m )
bu
stio
n
3
rc 
dmc
n
 kmc X O2
dt
Models for
phenomena
• Energy Technology
• Electrical Engineering
• Environmental Engineering
2
Secondary air
1
Primary air
1-D process
models
3-D process
models
THANK YOU FOR YOUR ATTENTION!
• Energy Technology
• Electrical Engineering
• Environmental Engineering
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14.1.2010