Modeling Coal-Particle Fragmentation inside a Moving Bed...
Transcript of Modeling Coal-Particle Fragmentation inside a Moving Bed...
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Modeling Coal-Particle Modeling Coal-Particle
Fragmentation inside a Moving
Bed Gasifier
Dipl.-Ing. Franz Holzleithner
Flow Sheet:
Introduction: COREX ®-Process
Melter-Gasifier:
2Dipl.-Ing. Franz Holzleithner
Motviation:
Particle Size Distribution (PSD) effects:
• Flow of Gas, Liquid Metal and Slag
• Heat Transfer
• Drying
• Pyrolysis
Introduction: Motivation & Objectives
• Gasification
Objectives of the Research-Project:
• Evolution of PSD
• Heat Transfer
• Drying
• Pyrolysis
• Gasification
• Gas-Phase-Reactions
within the modelling domain 3Dipl.-Ing. Franz Holzleithner
For
each
carb
onca
rrie
r
For
each
size
clas
s
Model-Outline
Models for Coal Conversion:
Drying: Single first order reaction, onset of evaporationdependent on water-vapour saturation pressure.
Devolatilization: Volatiles composition: determined by elemental balances(C,H,O,N,S) and closing relations.
Drying:H2O
Devolatilization:CH4, CO, CO2, H2O, H2, Tar, …
(C,H,O,N,S) and closing relations.Kinetics of volatiles release: system of parallel singlefirst order reactions.
Gasification: Shrinking particle behaviour, O2, H2O, CO2
Particle Energy Balance: Heat transfer, heats of reaction
Gasification:
O2, H2O, CO2
CO, CO2, H2, Ash
Model-Outline
Coal Particle Fragmentation:
Five process variables are driving forces:
• Shear stress
• Solids pressure
• Rate of drying
• Rate of devolatilization
Fragmentation-Breakage :
Fragmentation-Attrition:
5Dipl.-Ing. Franz Holzleithner 5Dipl.-Ing. Franz Holzleithner
• Rate of devolatilization
• Rate of gasification
Gasification-Diameter Reduction:
Model-Outline
Coal Particle Fragmentation:
Species-Balance Size Class j:
MassjonGasificati
MassjPyrolysis
MassjDrying
Massjreaction SSSS ,,,,
ɺɺɺɺ ++=
1,,.,. −+ jjBreakagejredDiam MM ɺɺ
Size Classes (SC):
MassjreactionjBreakagejredDiamjredDiam
j SMMMdt
dM,,1.,..,.
ɺɺɺɺ +++−= +
kijb ,
kiSkiK
…Breakage-Matrix, Process k, SC=i,j
…Frequencyfactor, Process k, SC=i
…Process Quantity, Prozess k, SC=i
6Dipl.-Ing. Franz Holzleithner 6Dipl.-Ing. Franz Holzleithner
Energy-Balance Size Class j:
j-1Mj-1
0M0
……… j+1Mj+1
………jMj
NMN
0,, jBreakageMɺ
∑
∑=
= =
SC
i k
ki
ki
kijijBreakage KSbMM
0
5
0,,
ɺ
NjBreakageM ,,ɺ
Enthalpyjreaction
EnthalpyjerHeatTransfjBreakagejjredDiamjjredDiam
j SSHhNhNdt
dH,,,11....
ɺɺɺɺɺ ++++−= ++
Get Data
Heat Transfer
Drying
Devolatilization
Computational Approach 1 Lagrange-Solid:
Output:
Continuum-Solid:
PorosityMass-BalanceMomentum-Balance Time Integration
Solver: CVODE
Loop overSize-Classes
Loop over Carbon Carriers(Iron Carriers analogously)
Gasification
Fragmentation
Send Data
7Dipl.-Ing. Franz Holzleithner 7Dipl.-Ing. Franz Holzleithner
Output:PSD,Sourceterms:Mass,Species,Energy
Continuum-Gas:
Mass-BalanceSpecies-BalanceMomentum-BalanceEnergy-BalanceGasphasereactions
[1] Committee on Reaction within Blast Furnace, Joint Society on Iron and Steel Basic Research, The Iron and Steel Institute of Japan
Blast Furnace Phenomena and Modelling. Elsevier Applied Science, 1987.
Model-Outline
Parameter Estimation for Coal Conversion Submodels:
Necessary since parameters are heaviliy
dependent on coal/coke type
Drying, Pyrolysis, Gasification:
Experiments have been performed
by IEHK-RWTH Aachen.
Coal Particle Fragmentation:
Experiments have been performed by ARP/ECV GESMBH (Leoben)
First Simulations-Boundary Conditions
Geometry and Boundary Conditions:Solid-Inlet:
3 Carbon Carriers (1 Coke, 2 Coals)
1 Iron Carrier + Additives
4 Size Classes (1mm-5mm-16mm-31.5mm), homogeneous mixture
Inlet-Temperatures: 25°C and 800°C
Mass flow rate-Outlet: acc. to CO Massflow Rate
Solid-Inlet
99
Mass flow rate-Outlet: acc. to CO Massflow Rate
Gas Inlet:
Massflow Rate: 50 kg/s,100% CO
Temperature: 3000 °C
Considered Processes:
• Heating
• Drying
• Pyrolysis
• Particle fragmentation
• Homogeneous reactions (Water-Gas-Shift-Reaction, Methane and Tar decomposition)
• Heating of prereduced Iron Carrier + Additives (solid and inert)
Gas-Inlet
First Results
Volume Fraction of Gas [-]: Sauter‘s Diameter-Carbo n Carriers [m]:
with Particle Fragmentation
Important for flow of liquid metal and slag.
10Dipl.-Ing. Franz Holzleithner
Particle Size Distribution-Volumefraction of Size Clas ses [-]:
(Averaged over all charged Carbon Carriers)
1 mm 5 mm 16 mm 31.5 mm
First Results
Mean Coal Temperature [°C]:
(Averaged over Coals and Particle Sizeclasses)
w/o Particle Fragmentation: with Particle Fragmentati on:
Coal Gas Coal Gas
11Dipl.-Ing. Franz Holzleithner
First Results
Coal - Particle Temperature [°C]:
Coal 1:1 mm 5 mm 16 mm 31.5 mm
with Particle Fragmentation
Coal Gas Coal Gas Coal Gas Coal Gas
12Dipl.-Ing. Franz Holzleithner
Coal 2:
1 mm 5 mm 16 mm 31.5 mm
Coal Gas Coal Gas Coal Gas Coal Gas
Status and Outlook
Completed:
• Models (3D-domain):
Fragmentation, Heat Transfer, Drying, Pyrolysis, Gas ification (O 2,H2O,CO2),
Homogeneous Reactions
• Validation of Single Particle Model (TGA-Measurement s)
• Validation of Fragmentation Model (Drying and Pyrolys is)
13Dipl.-Ing. Franz Holzleithner
Outlook (Follow-Up-Project 07.2012-07.2015):
• Inclusion of solids charging
• Inclusion of an existing solids flow model
• Inclusion of models for iron ore-particles (final reducti on and melting)
• Inclusion of models for calcination of additives
• Inclusion of models for flow of liquid iron and slag
• Inclusion of raceway
• Simulation of 3D-Slowly Moving Fixed Bed of an existing COREX®-MG
The research program of the Competence Center for Excellent Technologies in “Advanced Metallurgical and Environmental Process Development” (K1-MET) has been financially supported within the Austrian competence centreprogramme COMET (Competence Center for Excellent Technologies) by the Federal Ministry of Economy, Family and Youth; by the Federal Ministry for Transport, Innovation and Technology; by the provinces of Upper Austria, Styria and Tyrol, by the Styrian Business Promotion Agency and by the Tiroler Zukunftsstiftung.
grant-aided by
Acknowledgment
grant-aided by
14Dipl.-Ing. Franz Holzleithner