IFRF solid fuel data base:
drop tube experiments and modeling
aOskar
Karlström, aAnders Brink,
aMikko Hupa, b,cLeonardo Tognotti
aÅbo Akademi University, bUniversity of Pisa,
cInternational Flame Research Foundation
(IFRF)
Liekkipäivät January 2012
IFRF solid fuel data base
Uexp
 130 fuels (coal, biomass...)
 130 chars
 Proximate analysis (fvol fchar
fash)
 Ultimate analysis (C, N, O,
H...)
 Porosity, true density, apparent
density
 Mass loss vs. Time
experiments from high heating
rate drop tube reactor
South African coal char
1.0
0.8
0.6
0.4
1223K 4%O2
1223K 12%O2
1473K 4%O2
1673K 4%O2
0.2
0.0
0
1000
t (ms)
2000
http://sfdb.ifrf.net
Objectives
 Compare combustion rates of
chars from biomass, bituminous
coals and anthracite coals
Experiments
 Beech wood char
 Bituminous coal char
 Anthracite char
d ≈ 40 μm
d ≈ 40 μm
d ≈ 40 μm
Experiments
1. Devolatilization tests
1400 °C
100% N2
4m
Chars particles
collected
2. Char combustion
tests
950-1400 °C
3-12% O2
Experiments
South African coal char
1.0
Uexp
0.8
0.6
0.4
1223K 4%O2
1223K 12%O2
1473K 4%O2
1673K 4%O2
0.2
0.0
0
1000
t (ms)
2000
Model
dm p
dt
 d p kpO 2, s
2
n

dm p 1 

 d p k  PO2 , 
2


dt
dt

d
D
p


dm p
n
2
d p  d p ,0 1  U 

U  0.75
Model

dm p 1 

 d p k  pO2 , 
2

dt
dt d p D 

dm p
k  Aa e
mpcp
dT p
dt
n
2
T

DC
(  Ea / RT p )
 hS p T  T p   f h
dm p
dt
n, Aa, Ea
???
p
 T  / 2

0.75
dp

H reac  S p  p  R4  T p4

Multivariable optimization
“Multivariable optimization of reaction order and kinetic
parameters for high temperature oxidation of 10
bituminous coal chars”
Oskar Karlström, Anders Brink, Mikko Hupa, Leonardo
Tognotti
Combustion and Flame 2011
“One-parameter model for the oxidation of pulverized bituminous
coal chars”
Oskar Karlström, Anders Brink, Jaroslaw Hercog, Mikko Hupa,
Leonardo Tognotti
Energy and Fuels 2012
Results
1
1
Anthracite char
d = 39 um
0.5
U
U
0
0.5
Biomass char
d0 = 41 um
0
0
1000
time (ms)
2000
0
0
1000
time (ms)
1
U
Biom. char: n ~ 0.8
0.5
0
0
Bitum. char: n ~ 1
Bituminous coal char
d0 = 42 um
1000
time (ms)
2000
Ant. char:
n~0
2000
Biom. char: n ~ 0.8
Bitum. char: n ~ 1
Ant. char:
2C + O2→ 2 C(O)
C(O) + O2→ CO/CO2
C(O) → CO
2C(O) → CO2 + C
n~0
2C + O2→ 2 C(O)
C(O) + O2→ CO/CO2
C(O) → CO
2C(O) → CO2 + C
k 4   k 2 PO 2 , k3
r  k4
r  k2PO2  k3
Conclusions
 Multivariable optimization approach
successfully applied on the various
chars
 Biomass and bituminous coal chars: n
≈1
 Anthracite chars: n ≈ 0
 Reaction order differences can be
explained by char oxidation
mechanisms
 Surprisingly high reactivity of biomass
Acknowledgement
This work has been partly carried out
within the consortium FUSEC (20112014) :
-Tekes
-Andritz Oy
-Metso Power Oy
-Foster Wheeler Energia Oy
-UPM-Kymmene Oyj
-Clyde Bergemann GmbH
-International Paper Inc.
-Top Analytica Oy Ab.
Further the work is part of the ERANET-