11
Improved Materials For High-Temperature Black Liquor Gasification
James R. Keiser*, J. Peter Gorog**, Roberta A. Peascoe*, James G. Hemrick*, and Camden R. Hubbard*
*Oak Ridge National Laboratory, Oak Ridge, TN **Weyerhaeuser Company, Federal Way, WA
G 22040623* ITP
This Project Builds On A Previous Project
� The previous project addressed refractory structural materials for high-temperature black liquor gasifiers
� As part of the previous project several test systems were built – Smelt immersion test system – Rotary refractory test furnace
� Exposed refractory samples from several high-temperature gasifiers were examined
� Project was completed September 30, 2003
G
,
,
Reactor
Quench
SecondaryAir
Black Liquor
AtomizingSteam
QuenchCirculation
Punp
Green Liquor
Ventu
Venturi
66 GPM270°F 70% DS
13,400 CFM900°F
1,750°F
CoolingWater
Reactor
Quench
SecondaryAir
Black Liquor
AtomizingSteam
QuenchCirculation
Punp
Green Liquor
Ventu
Venturi
66 GPM270°F 70% DS
13,400 CFM900°F
1,750°F
CoolingWater
Ventu
33040623* ITP
Improved Materials For High-Temperature Black Liquor Gasification
Goals: Develop better refractories and other structural components for use under current and future gasification conditions
Challenge: The gasifier’s refractory lining and liquor spray nozzle of the gasifier historically have had unacceptably short lifetimes. More degradation-resistant materials are needed
Benefits: Implementation of combined cycle black liquor gasification is projected to offer up to $6.5 billion in cumulative energy cost savings and a significant reduction in gaseous emissions. In addition, up to 156 billion kWh of distributed energy could be produced
FY05 Activities: Examine exposed refractories; continue laboratory tests of refractories, conduct tests of potential liquor nozzle materials, refine models of gasifiers and liquor nozzles
Participants: Weyerhaeuser Company Chemrec AB, Monofrax Refractories, ANH Refractories, Corhart Refractories Process Simulations Limited, Simulent, Inc,. University of Missouri-Rolla
Reactor
Quench
SecondaryAir
Black Liquor
AtomizingSteam
QuenchCirculation
Punp
Green Liquor
Venturi
66 GPM 270°F 70% DS
13,400 CFM 900°F
1,750°F
CoolingWater
G 44040623* ITP
Improved Materials For High-Temperature Black Liquor Gasification
Barrier-Pathway Approach Barriers Pathways Critical Metrics � Degradation of
gasifier’s refractory lining by reaction with molten alkali salts
� Degradation by wear/corrosion of black liquor nozzles
� Characterize environment through modeling of gasifier vessel and nozzle
� Evaluation refractories exposed in high-temperature gasifiers
� Conduct laboratory tests of refractories
� Evaluate wear-resistant materials for spray nozzles
� Refractory lifetime is increased by at least a factor of two
� New materials allow nozzle lifetime to be increased from a few months to at least twelve months
� 50% capacity increase
Switch to combined cycle black liquor gasification could result in reduction of emissions and more efficient power production
G 55040623* ITP
Main Components Of Gasifier Installed At New Bern
Feed W ater
Reactor
Quench
Sec ondary Air
Black Liquor
Steam
ECO
Atomiz ing Steam
Quench C irculat ion
Punp
Green Liquor
Bottom Section
GasFlow
Venturi Circulation
Venturi
Condsensate Pump
Bleed to Quench
Cooling
Section
Gas
Absorption
Section
Wash
Section
Demister FreshMill W ater
Product Gas to No. 2 Power Boiler
Cooler
Cooler
Weak Wash
Scrubber
No. 2 Power Boiler
Burner No. 1
Burner No. 2
66 GPM 270°F 70% DS
13,400 C FM 900°F
1,750°F
160 GPM 202 °F
No. 6 oil 18 GPM
HVLCLVHC
20,300 CFM 105°F
200,000 850 PSIG
825 °F
G 66040623* ITP
History Of Commercial Black Liquor Gasifier Constructed At Mill In New Bern, NC
� Project Release June 29, 1995
� Start Construction November 1995
� First Product Run December 1996
� Taken out of Service (Shell Failure) December 1999
� Final Decision to Rebuild gasifier April 2002
� Restart Gasifier June 27, 2003
G 77040623* ITP
Original Fused Cast Alumina Lining Replaced The 60% Alumina Brick That Degraded Rapidly
⇒ 150mm (~6”) α+β fused cast alumina
⇒ 1/64” mica sheet
⇒ 150mm (~6”) β fused cast alumina
⇒ 2x1/64” mica sheet
⇒ 1/8” insulating board
⇒ 3/8” fiber blanket
⇒ 3/8” 316L Stainless Steel
G
Distance from Hot Face (mm)
Cum
mul
ativ
e Ph
ase
(%)
88040623* ITP
Core Samples Of The Fused Cast Alumina Lining Were Removed For Inspection
� NaAlO2 found on hot face � Increased Na content found at
back of the working lining and front of backup lining
� No NaAlO2 detected in backup lining
Working Lining: Jargal M Backup Lining: Jargal H
1 inch
0% 10% 20% 30% 40% 50%
60% 70% 80% 90%
100%
1.5 24.5 41.5 61.0
Distance From Hot Face (mm)
Cum
ulat
ive
Phas
e (%
)
α-Al2O3
β-Al2O3
NaAlO2
1 inch
G 99040623* ITP
Material Volume Expansion
(%) Al2O3 -β-Al2O3 31 β’-Al2O3 32 NaAlO2 133
Observed Microstructural Changes Resulted From Reaction With Sodium
~50% Conversion to NaAlO2
~25% Conversion to NaAlO2
<5% Conversion to NaAlO2
Original Structure
Hot
Fac
e
G 1010040623* ITP
When A Crack Was Found In The Gasifier Shell Several Sections Were Removed and Inspected
Dye penetrant tests showed many cracks in the vertical direction
Through-wall crack on the shell was first indication seen by mill personnel
G 1111040623* ITP
Root Causes of Failure Were Identified
�Mill water used during installation likely contained chlorides which contaminated materials adjacent to the shell
�Water condensed on the inside of the shell during start ups and shut downs and dissolved the chlorides
� Cycling of the unit concentrated the chlorides on the shell surface � The chemical expansion of the refractory lining caused high tensile
hoop stress in the shell � The presence of tensile stress and aqueous solution of chlorides
caused Stress Corrosion Cracking (SCC) in the 316L shell � Tensile stress introduced during operation caused some of the
cracks to grow through the shell � Above mechanism repeatedly occurred until the pressure
vessel failed
G 1212040623* ITP
New Bern Gasifier Restoration Project
New Refractory/Shell System Design � Hemispherical Dome � Carbon steel refractory containment which
is not susceptible to Cl- SCC � Crushable metal foam used between
refractory and shell � Fused cast alumina working lining over
high alumina backup lining � Expansion allowance for growth of
refractory based on data collected after one year of operation
G 1313040623* ITP
Strain Monitoring System Assesses Shell Deformation
� Strain gauges mounted at two elevations on the barrel, in the bottom cone and at the top of the dome
�Wires with Vernier scales and LVDTs mounted on two elevations on the barrel
� Inspection orifices (with plugs) on the barrel and dome
Strain gauges tension load
Strain gauges hoop stress
Strain gauges bending load
Strain gauges hoop stress
Wires
Vernier and LVDT
Inspection Orifices
Inspection Orifices
Inspection Orifices
G
9/4/0312:00A M
9/6/12:AM
1414040623* ITP
Typical LVDT Data Analysis � Foam expansion is computed from shell stress � Shell stress is determined from LVDT data
after corrections have to be applied for: – Thermal expansion of wire – Thermal expansion of shell
Upper Upper Stainless Wire
50 75
100 125 150 175 200 225 250 275 300 325 350 375 400
6/16/03 12:00 A M
6/18/03 12:00 AM
6/20/03 12:00 AM
6/22/03 12:00 A M
6/24/03 12:00 AM
6/26/03 12:00 AM
6/28/03 12:00 AM
Tim e
Tem
pera
ture
(F)
1.3000 1.4000 1.5000 1.6000 1.7000 1.8000 1.9000 2.0000 2.1000 2.2000 2.3000 2.4000 2.5000 2.6000 2.7000 2.8000 2.9000 3.0000
Shell Temp
Das Reading
Upper Upper Stainless Wire
50.0 70.0 90.0
110.0 130.0 150.0 170.0 190.0 210.0 230.0 250.0 270.0 290.0 310.0 330.0 350.0
03 00
9/8/03 12:00 AM
9/10/03 12:00 AM
9/12/03 12:00 A M
9/14/03 12:00 A MTim e
Tem
pera
ture
(F)
2.50E+00
2.55E+00
2.60E+00
2.65E+00
2.70E+00
2.75E+00
2.80E+00
2.85E+00
2.90E+00
2.95E+00
3.00E+00
Shell Temp
Wire Temperature
Das Reading
LVDT data tracked well with shell temperature at startup
Effect of shell loading can be seen
Day time - night time temperature variations
G 1515040623* ITP
0 50
100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950
1000
0 5 10 15 20 25 Radial Expansion of Refractory (mm)
Shel
l Hoo
p St
rain
(Mic
roSt
rain
)
0
0.5
1
1.5
2
2.5
3
3.5
Inte
rnal
Stre
ss (M
Pa)Lower Strain Gauge # 211
Lower Strain Gauge # 213
Lower Stainless Wire Upper Strain Gauge # 215
Upper Strain Gauge # 217
Upper Stainless Wire
Radial Refractory Expansion (Data from start-up to Mid April-04)
N24.4
N24.7
N24.6
10/10/03 PMO
N24.5
N242.
N24.21/19/04 PMO
G 1616040623* ITP
Progress To Date
� This project builds on a recently completed project on gasifier materials
� Exposures of test refractories in molten smelt have continued
� Four refractories exposed in the New Bern gasifier have been examined
� Based on analysis results, a refractory recommendation has been made
� A system has been built for testing wear-resistant nozzle materials
� Subcontracts have been placed for gasifier and nozzle modeling
G 1717040623* ITP
A Laboratory Test Facility Permits Exposure Of Refractory And Metallic Samples To Molten Salts
G 1818040623* ITP
Many Types Of Refractories Have Been Tested
� Commercially available refractories
� Experimental or developmental refractories from commercial supplies
� Experimental refractories produced by subcontractors
� Experimental refractories developed in our laboratory
� Commercial refractories with commercial and experimental coatings
Based on results of immersion tests, three test refractories were recommended for exposure in the rebuilt gasifier
G 1919040623* ITP
The New Bern Gasifier Was Inspected In Mid-January After 6½ Months Of Operation
Refractory lining near bottom of barrel portion of gasifier vessel. Note red lines indicating apparent cracks on most blocks except for two in the second row (upper right).
G 2020040623* ITP
Core drilling was done with kerosene instead of water as the lubricant/coolant to avoid dissolving water-soluble corrosion products.
Core-Drilled Samples Were Collected From The Primary Refractory And Three Test Materials
G 2121040623* ITP
Cross-Sections Of The Core-Drilled Samples Revealed Significant Differences
Fusion-cast magnesia-alumina refractory
Bonded magnesia-alumina refractory (outlined at left)
Fusion-cast alumina refractory
Alternate fusion cast alumina refractory
G 2222040623* ITP
The Electron Microprobe Provided Elemental Maps Of The Core-Drilled Refractory Samples
S
AlNa
S
AlNa
S
AlNa
SSS
AlAlAlNaNaNa
Overlaid elemental maps of sodium, sulfur and aluminum for the fusion α/β refractory (upper) and a fusion-cast magnesia-alumina spinel (lower).
G 2323040623* ITP
Conclusions From Examination Of Core-Drilled Refractory Samples
� The fusion-cast α/β-alumina showed less spalling than any refractory previously used for the vessel lining
� Cracking was evident through about the first half of the fusion-cast α/β-alumina bricks that were examined
� The fusion-cast magnesia-alumina spinel showed less cracking and penetration of sodium than the fusion-cast α/β-alumina
� The alternate fusion-cast α/β-alumina and the bonded magnesia-alumina bricks reacted more extensively
G 2424040623* ITP
Current Black Liquor Injection Nozzle Mixes Steam And Liquor But Exit End Of Holes In
Nozzle Suffer Significant Wastage
Cross section of black liquor nozzle Delivery end of nozzle showing wastage
G 2525040623* ITP
The New Nozzle Allows Insertion Of Wear-Resistant Test Materials
Inserts of various wear-resistant ceramic and metallic materials are being fabricated and will be tested in this system
G 2626040623* ITP
Modeling Studies Of Gasifier Components Are Planned
� A subcontract has been placed with Simulent Incorporated for modeling of the black liquor nozzle
� A subcontract has been placed with Process Simulations Limited for CFD modeling of fluid flow in the gasifier
� Both subcontracts are receiving matching funds from the Canadian government
� Thermochemical modeling will be conducted at ORNL to study interactions between the refractories and the gasifier environment
G 2727040623* ITP
Future Plans � Smelt immersion testing of various refractories will continue
– Primary candidates – address orientation effects & microstructural effects
– Surface-treated refractories – Other alternate materials
� Refractory scheduled to be removed from the gasifier in September will be analyzed – Primary lining – Three test materials
� Tests of wear-resistant nozzle materials will be conducted
�Modeling of gasifier components will be continued
G 2828040623* ITP
Commercialization Plans
� Close cooperation is continuing with the designer/developer of the high-temperature gasification process used in the New Bern gasifier
� Refractory materials identified in the ORNL-led studies are likely to be used in the scaled-up system being built in Piteå, Sweden
� A patent application has been submitted for a coating process that provides increased lifetime of refractory bricks in molten alkali salts
� A patent application has been drafted for use of the fusion-cast magnesia-alumina spinel in black liquor gasifiers
