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Mitg
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Use of the oxide database in modelling of
multi-component slag viscosities
04.07.2013 Guixuan Wu
Outline
Introduction
Viscosity model
Results
Case study
Outlook
04.07.2013 Guixuan Wu 2
04.07.2013 Guixuan Wu 3
Viscosity
Temperature
Pressure
Composition
Introduction
Marc A. Duchesne: Slagging in entrained-flow gasifiers, 2012.
The idea of current viscosity model
04.07.2013 Guixuan Wu 4
Comp. & Temp.
Associate species
Structure
Viscosity
Gibbs energy
and viscosity-
on a common
structural base
04.07.2013 Guixuan Wu 5
Arrhenius model (modified)
System: SiO2-Al2O3-CaO-MgO-Na2O-K2O
34 different associate species
Data source: SciGlass database and FactSage references
Data search: 62 subsystems with 32 subsystems available
ln η = ln ηideal + ln ηexcess
= ( Xi ∙ ln ηi) + (ln ηself−pol. + ln ηinter−pol.)
where: ln ηi = Ai + Bi T
ln ηself−pol. = A∗j,SiO2+ B
∗j,SiO2 T ∙ (X
nj
SiO2)
ln ηinter−pol. = ( A∗k+ B
∗k T) ∙ Xk ∙ X
nkSiO2
Probability
Si-Al-based ternary
associate species
Si-based associate species
Viscosity model
04.07.2013 Guixuan Wu 6
Associate species model
is employed to predict the
slag structure, which can
be presented by the
relative concentrations of
each associate species.
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.00.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Al2O
3
SiO2
Si2Al
6O
13
CaO
CaSiO3
Ca2SiO
4
CaAl2O
4
CaSi2Al
2O
8
No
rma
lize
d D
istr
ibu
tio
n o
f A
sso
cia
te S
pe
cie
s
XAl2O3/(Al2O3+CaO), Mol fraction
XSiO2=0.300
T=2100oC
SiO2-Al
2O
3-CaO System
CaSiO3
ln ηideal= Xi ∙ (Ai+Bi T)
Ideal viscosity part
04.07.2013 Guixuan Wu 7
S1+S1=S2
S1+S2=S3
… … S1+Sk-1=Sk
self-pol.
S: SiO2
ln ηself−pol. =
A∗j,SiO2+ B
∗j,SiO2 T ∙ (X
nj
SiO2)
Excess viscosity part 1: self-polymerization
of SiO2
L. Wang: Doctoral thesis, KTH, 2009.
04.07.2013 Guixuan Wu 8
Binary system SiO2-CaO or MgO
04.07.2013 Guixuan Wu 9
Na4SiO4 V.S. Na2O
Binary system SiO2-Na2O or K2O
04.07.2013 Guixuan Wu 10
Binary system SiO2-Al2O3
04.07.2013 Guixuan Wu 11
Viscosity sequence: SiO2-Al2O3> SiO2-MgO
>SiO2-CaO>SiO2-Na2O>SiO2-K2O
Comparison of SiO2-based binary systems
04.07.2013 Guixuan Wu 12
Ternary system SiO2-CaO-Na2O
04.07.2013 Guixuan Wu 13
Binary system Al2O3-CaO or Na2O
04.07.2013 Guixuan Wu 14
RAlO2, RAlSiO4, RAlSi3O8 or RAlSi2O6
R: Na, K
MAl2O4, MSi2Al2O8 or M2Al4Si5O18
M: Ca, Mg
Compensation effect of Al2O3
04.07.2013 Guixuan Wu 15
A1N1S1+ S1 = A1N1S2
A1N1S1+ S2 = A1N1S3
… … A1N1S1+ Sk−1 = A1N1Sk
inter-pol.
S: SiO2, A: Al2O3, N: Na2O
Excess viscosity part 2: inter-polymerization
of SiO2
ln ηinter−pol. =
( A∗k+ B
∗k T) ∙ Xk ∙ X
nkSiO2
L. Wang: Doctoral thesis, KTH, 2009.
04.07.2013 Guixuan Wu 16
Ternary system SiO2-Al2O3-CaO or Na2O
04.07.2013 Guixuan Wu 17
Viscosity maximum sequence:
SiO2-Al2O3-K2O>SiO2-Al2O3-Na2O
>SiO2-Al2O3-CaO>SiO2-Al2O3-MgO
Comparison of SiO2-Al2O3-based ternary
systems
04.07.2013 Guixuan Wu 18
Stream
constituents Wt-%
C 7.88E+01
H 5.00E+00
O 8.86E+00
N 1.61E+00
S 6.40E-01
Cl 1.50E-02
Al 6.40E-01
Fe 6.00E-01
Ca 7.20E-01
Mg 2.10E-01
K 1.10E-01
Na 2.50E-01
Si 1.60E+00
Case study: viscosity behavior in gasifier
Marc A. Duchesne: Slagging in entrained-flow gasifiers, 2012.
04.07.2013 Guixuan Wu 19
Case study: introduction of Ca(OH)2
Nr. Of
sample
Components, wt%
Glycol Wood charcoal Straw ash Ca(OH)2
1 70% 25% 5.0% 0.0%
2 70% 25% 4.9% 0.1%
3 70% 25% 4.8% 0.2%
4 70% 25% 4.6% 0.4%
5 70% 25% 4.4% 0.6%
6 70% 25% 4.2% 0.8%
7 70% 25% 4.0% 1.0%
8 70% 25% 3.5% 1.5%
9 70% 25% 3.0% 2.0%
10 70% 25% 2.5% 2.5%
11 70% 25% 2.0% 3.0%
04.07.2013 Guixuan Wu 20
Case study: calculated viscosity
04.07.2013 Guixuan Wu 21
Case study: the optimum charge of Ca(OH)2
04.07.2013 Guixuan Wu 22
System: SiO2-Al2O3-CaO-MgO-Na2O-K2O-FeO-Fe2O3
49 different associate species
Data source: SciGlass database (version 7.2)
Data search: 254 subsystems with 114 subsystems
available
Introduction of new components FeO and
Fe2O3
Mitg
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Thank you very much for your attention!
