Download - Refractory Wear During Gasification
Refractory Wear During Gasification
Larry Baxter1, Shrinivas Lokare1, Humberto Garcia2, Bing Liu1
Clearwater Coal Conference
Clearwater, FL
June 2, 2009
Gasification in the Literature
Research by Country
Levelized Cost of Power
GE Energy Radiant
Coal
Cryogenic Oxygen
Slag/Fines
Water
High Pressure
Steam
Radiant Syngas Cooler
Radiant Quench Gasifier
SyngasScrubber
Solids
Saturated Syngas 398OF
Quench Chamber
2,500OF
1,100OF
419OF
Coal
Cryogenic Oxygen
Slag/Fines
Water
High Pressure
Steam
Radiant Syngas Cooler
Radiant Quench Gasifier
SyngasScrubber
Solids
Saturated Syngas 398OF
Quench Chamber
2,500OF
1,100OF
419OF
Coal Slurry63 wt.%
95% O2
Slag/Fines
Syngas 410°F, 800 Psia
Composition (Mole%):H2 26%CO 27%CO2 12%H2O 34%Other 1%H2O/CO = 1.3
Design: Pressurized, single-stage, downward firing, entrained flow, slurry feed, oxygen blown, slagging, radiant and quench cooling
To Acid Gas Removalor
To Shift
ConocoPhillips E-Gas™
Coal Slurry63 wt. %
Stage 2
95 % O2Slag
Quench
Char
Slag/Water Slurry
Syngas Syngas1,700°F, 614 psia
Composition (Mole%):H2 26%CO 37%CO2 14%H2O 15%CH4 4%Other 4%H2O/CO = 0.4
(0.78)
(0.22)
Stage 12,500 oF614 Psia
To Fire-tube boiler
Design: Pressurized, two-stage, upward firing, entrained flow, slurry feed, oxygen blown, slagging, fire-tube boiling syngas cooling, syngas recycle
To Acid Gas Removalor
To Shift
Shell Gasification
Syngas350°F, 600 Psia
Composition (Mole%):H2 29%CO 57%CO2 2%H2O 4%Other 8%H2O/CO = 0.1
DryCoal
Design: Pressurized, single-stage, downward firing, slagging, entrained flow, dry feed, oxygen blown, convective cooler
Convective CoolerSoot Quench& Scrubber
95% O2 HP Steam
650 oF
Steam
Source: “The Shell Gasification Process”, Uhde, ThyssenKrupp Technologies
Syngas Quench2
To Acid Gas Removalor
To Shift
HP Steam
Slag
Gasifier2,700 oF615 psia
Transient Model Formulation
……
Gas
and
Par
ticle
Flo
w D
irect
ion
1
2
n
N -1
N
123 … …m M
gasi
fier
wall
slag/ash
… …m M
… …m M
… …m M
… …m M
……
Gas
and
Par
ticle
Flo
w D
irect
ion
1
2
n
N -1
N
123 … …m M
gasi
fier
wall
slag/ash
… …m M
… …m M
… …m M
… …m M
part
icle
traj
ecto
ry
Simulation – Gas Phase
Simulation – Gas Phase
Efficiency Calculation
Impaction Efficiency Improvement
1321 )()()(1)( aStkdaStkcaStkbStk
a b c dPotential Flow 0.1238 1.34 -0.034 0.0289Viscous Flow 0.0868 1.9495 -0.457877 -0.047
Corrosion potential
K Cl
S
Si Ca Fe
Chlorides condensation is a major step in corrosion initiation
Complex Inorganic Chemistry
Complex Inorganic Chemistry
Mole Fraction SiO 2
Tem
per
atu
re /C
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 11100
1300
1500
1700
1900
Allen & SnowSchuhmann & EnsioBowen & SchairerGreig
2 Liquids
Cr
Tr
Liquid
Fe 2
SiO
4
1205 ˚C
1928 ˚C
Al2O3-CaO-SiO2 Chemistry
0.2 0.3 0.41340
1360
1380
1400
1420
1440
1460
Me
ltin
g P
oin
t (oC
)
CaO Weight Fraction
Liquid
Solid
Al2O3/SiO2 = 0.34
Refractory-Slag Model
Syngas Tsyn Forced Convection Radiation
Air Tair Free Convection Radiation
Refractory
Slag
Deposited Ash
Steel Shell
Slag Importance
1300 1350 1400 1450 1500 1550 16000.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
Corr
osi
on R
ate
(m
m/h
r)
Temperature (oC)
With Slag Flow Without Slag Flow
Refractory Wear with Time
0.8
0.6
0.4
0.2
0.0
0.00 0.04 0.08 0.12 0.16 0.20 0.24
1000hr
1500hr
Refractory Wear Depth (m)
L (
m)
500hr
0.1 0.2 0.3 0.4 0.5 0.61000
1200
1400
1600
1800
2000
Slag Cold-face Temperature
Solid Region
Melti
ng T
em
pera
ture
(oC
)
CaO Weight Fraction
Liquid Region
Sensitivity to CaO content
0.1 0.2 0.3 0.4 0.5 0.60.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Corr
osi
on R
ate
(m
m/h
r)
CaO Weight Fraction
Refractory Chemical Corrosion
1440 1460 1480 1500 1520 15400.000
0.001
0.002
0.003
0.004
0.005
0.006
0.007
Co
rro
sio
n R
ate
(m
m/h
r)
Temperature (oC)
0.1kg/m2s
0.2kg/m2s
Spalling Mechanisms
Overall Refractory WearChemical dissolution rates depend in complex ways on diffusivities, viscosities, chemical reactions, and temperature.
Spalling mechanisms and rates are not well understood, with quantitative models being mostly empirical.
Net dissolution rates disproportionately depend on minor slag and refractory components, involving complex inorganic chemistry.
Spalling Mechanisms
Spalling
Corrosion
Spalling Mechanisms
1
234
56
Chemistry (weight %)
Point
1 2 3 4 5 6
- Al 6.9 27.3 1.7 2.8 7.5 5.7
- Si 23.9 0.2 0.1 0.1 40.2 3.8
- Fe 20.8 31.7 23.6 0.2 1.5 0.5
- Ca 1.5 - - - 0.5 -
- Cr 0.1 1.5 42.7 62.1 1.5 53.0
Crystalline Phases hercynite, fayalite, enstatite, Iron sulfide, iron cordierite, hermatite
iron-alumina spinel
iron-chrome spinel
Chromia/alumina solid solution Fe-depleted slag Al build-up with Si
Refractory/Slag Profile
Distance from Hot Face (mm)
Bulk Chemistry (wt pct) X-Ray Crystalline Phases
Cr2O3 Al2O3 SiO2 CaO Fe
H.F. to 2.3 80.0 10.8 5.4 0.3 1.6 P= Cr2O3
Tr=M*Cr2O4
6.9 84.2 10.2 3.9 0.3 0.4 P= Cr2O3
Tr=M*Cr2O4
11.4 83.9 10.7 3.2 0.4 0.4 P= Cr2O3
Tr=M*Cr2O4
34.3 83.5 10.4 2.8 0.6 0.4 P= Cr2O3
43.3 83.9 9.3 2.3 0.5 0.2 P= Cr2O3
52.7 85.7 10.5 0.9 0.2 0.2 P= Cr2O3
57.2 86.1 10.5 0.2 0.0 0.2 P= Cr2O3
127 87.4 9.4 0.2 0.2 0.2 P= Cr2O3
Conclusions
• Chemical dissolution and spalling account for most refractory wear.
• Both mechanisms depend on temperature, slag/refractory composition, and slag flow rates, approximately in that order.
• Temperature dependence arises from both transport and solubility issues.
• Both immersion and spinning cup analyses provide good corrosion information, but neither simulates practical systems.
• Temperature, not peak deposition rates, determine maximum corrosion location.
Acknowledgements
• PhD and post-doc students Shrinivas Lokare, Bing Liu developed many of the submodels.
• Partial financial support from U.S. Department of Energy contract DE-AC07-05ID14517 and from corporate sponsors.