Corrosion in Black Liquor Pyrolysis and Combustion Gas Environments Preet M. Singh Institute of Paper Science and Technology Atlanta, Georgia Colloquium on BL Combustion and Gasification Park City, Utah May 13th, 2003
Recovery Boiler To stack Electrostatic precipitator Boiler Superheater Economizer Black liquor Screen Tubes Air delivery: Tertiary Secondary Primary Smelt
Differences in Fireside Tube Surface Corrosion NonCorrosive Area Corrosive Area
Thermocouples and Gasline for Environment Sampling Filters for Gasline
Instrumentation for Boiler Environment Characterization
Hydrogen Sulfide in RB % in Dry Gases 30 25 20 15 10 5 High Corrosion Area Low Corrosion Area 0 1 foot 1 inch Waterwall surface
Methyl Mercaptan in RB % in Dry Gases 0.6 0.5 0.4 0.3 0.2 0.1 High Corrosion Area Low Corrosion Area 0 1 foot 1 inch Waterwall surface
65% SolidsBlack liquor is sprayed on sidewalls Average Gas Composition at Waterwall Surface Boiler #1 Gas Species High Corr. Area Low Corr. Area N 2 24.8 % 38.6 % CO 2 18.8 % 13.4 % CO 11.7 % 9.2 % H 2 2.4 % 1.4 % O 2 2.9 % 4.4 % CH 4 4.0 % 0.8 % H 2 S 18 % 3.8 % SO 2 /COS 0.2 % 0.18 % Meth. Mercaptan 0.17 % 0.02 %
High Corrosion Of Waterwall Due to Black Liquor Spray in Boiler #1 Black Liquor Pyrolysis on Waterwall Tubes High Local Concentrations of Sulfur Bearing Gases
Recovery Boiler #2
Locations of Cutline Corrosion in a Boiler MidFurnace Corrosion CSteel Tubes High Corrosion Areas Secondary Airports Composite Tubes Rear Wall Auxiliary Burners Liquor Guns Primary Airports Left Wall (North) Front Wall Right Wall (South)
Locations of MidFurnace Corrosion 1 Boiler #4 113 1 115 1 LB 25 RCT 41 RCM 34 RCB 27 RLT RLM RLB 113 115 LF 25 Rear Wall Left Wall Gas Sampling Port Composite Tubes Front Wall (High Corrosion Rate)
Gases at Waterwall Surface Mid Furnace Boiler #5 (North Wall) Gas Species % in High Corr. Area % in Low Corr. Area % 12' Above High Corr N 2 10.60 40.62 46.74 CO 2 14.23 17.71 17.87 CO 27.95 13.57 13.98 H 2 12.04 6.67 5.16 O 2 0.27 0.52 0.55 CH 4 4.42 1.82 1.59 H 2 S 0.91 0.81 0.86 SO 2 /COS 0.20 0.10 0.12 CH 3 SH 0.030 0.023.013 (CH 3 ) 2 S 0.033 0.028 0.033 CS 2 0.0012 0.0018 0.0024 (CH 3 ) 2 S 2 0.0019 0.0012 0.0009 65 68% SolidsBlack liquor
Corrosion in Lower Furnace When black liquor is sprayed or endsup intentionally or unintentionally on waterwalls local pyrolysis of black liquor on waterwall surface Higher concentrations of sulfur bearing gases locally higher sulfidation or corrosion of carbon steel waterwalls in these areas
Corrosion Kinetics
Thermobalance for RB Simulation Tests Quartz spring Cathetometer Platinum wire Gas outlet Furnace Test Coupon Pyrex tube Thermocouple Gas inlet Endcap Mass Flow Meters and Controllers Different Gases
Effect of Temperature
CSteel, SA210 at 320 o C and 400 C in High Corrosion Gases From RB#1 W t. Gain, mg/cm² 60 50 40 30 20 10 0 CSteel, SA210 @ 320 and 400 C in HighRB#1 Gases High RB#1400C High RB#1320C 0 4 8 12 16 Time, days
SA210 in HC Gases at 320 o C
SA210 in HC Gases at 320 o C Element S Fe O Total Spot #1 4.11 95.89 0.0 100.00 At% Spot #3 Spot #6 2.08 97.92 0.00 100.00 10.57 74.54 14.89 100.00
SA210 in HC Gases at 400oC
SA210 in HC Gases at 400 o C Element S Fe O Spot #1 1.55 94.6 0.00 Spot #2 49.53 48.24 0.00 At% Spot #5 Spot #10 51.94 46.72 0.00 6.86 68.02 25.12
Source IPST Corrosivity Database Effect of Temperature on Corrosion Rate of 304 SS in Gases Containing Only H 2 S and H 2 1000 304SS in H2S + H2 Gas Mixtures (Partial Pressure of O2 = 0.0) Corrosion Rate (mpy) 100 10 1 0.1 200 300 400 500 600 700 Temperature (oc)
Effect of Gas Composition
Lower Furnace Gas Compositions Used in Laboratory Tests H2 CO2 O2 CH4 CO H2S COS CH3SH CH32S CS2 N2 High Sulfur (HS) 14.7 0.0 6.1 0.00 0.00 5.99 2.04 0.05 0.00 0.00 70.5 Low Sulfur (LS) 4.0 19.7 10.1 0.10 21.80 0.54 0.23 0.00 0.00 0.00 43.6 High Corrosivity w/o O2 (HC) 12.0 0.0 0.0 0.00 0.00 1.18 0.36 0.02 0.00 0.00 87.2 Lower Furnace Recovery Boiler Gases High Sulfur (HS) Low Sulfur (LS) High Corrosivity w/o O2 (HC) 480 o C 320 o C S2 P S2 7.14E10 10 1.68E10 10 4.32E11 P O2 6.12E03 3.92E29 29 3.60E34 34 P S2 3.59E13 2.97E13 2.17E14 14 P O2 6.12E03 3.33E36 36 1.00E36
(HS) High Sulfur Containing RB Gases 40 35 HSGases at 480 o C HSGases at 320 o C 30 Corrosion Rate (mpy) 25 20 15 10 12.1 5 0 0.2 1.4 0.1 1.7 0.9 304L SA210 I625 304L SA210 I625 Alloy
(LS) Lower Sulfur Containing RB Gases 40 35 LSGases at 480 o C LSGases at 320 o C 30 Corrosion Rate (mpy) 25 20 15 10 16.89 5 0 0.68 1.99 0.96 0.84 1.10 304L SA210 I625 304L SA210 I625 Alloy
(HC) Low Oxygen Containing RB Gases 40 35 30 HCGases at 480 o C 36.4 HCGases at 320 o C 29.3 Corrosion Rate (mpy) 25 20 15 10 9.5 13.8 5 0 1.1 1.5 304L SA210 I625 304L SA210 I625 Alloy
Source IPST Corrosivity Database Effect of Sulfur Partial Pressure on Corrosion Rate of 304 SS in Gases Containing Only H 2 S and H 2 at 400 o C 5.00 4.50 4.00 Corrosion Rate of 304 SS at 400 o C as a function of Sulfur Partial Pressure in (H2S + H2) Gas Mixtures Corrosion Rate (mpy 3.50 3.00 2.50 2.00 1.50 1.00 0.50 0.00 1.0E15 1.0E13 1.0E11 1.0E09 1.0E07 1.0E05 1.0E03 Partial Pressure of Sulfur (atm.)
Phase Stability Diagrams for Fe, Ni, and Cr in Presence of O 2 and S 2 at 320 o C log ps2(g) 0 5 FeS2 Predominance Diagram for FeOS System log ps2(g) 0 5 Cr2S3 Predominance Diagram for CrOS System 10 Fe2S3 10 15 20 FeS FeSO4 Fe2(SO4)3 15 20 Cr2(SO4)3 25 30 Fe3O4 Fe2O3 25 30 Cr2O3 35 35 40 40 35 Constant value: T / C = 320.00 30 25 20 15 10 5 0 log po2(g) log ps2(g) 0 40 40 35 Constant value: T / C = 320.00 Predominance Diagram for NiOS System 30 25 20 15 10 5 0 log po2(g) 5 NiS2 Lower Furnace Recovery Boiler Gases High Sulfur (HS) P S2 3.59E13 320 o C P O2 6.12E03 10 15 20 Ni3S2 NiS(A) NiSO4 Low Sulfur (LS) High Corrosivity w/o O2 (HC) 2.97E13 2.17E14 14 3.33E36 36 1.00E36 25 30 Ni(FCC) NiO 35 40 40 35 Constant value: T / C = 320.00 30 25 20 15 10 5 0 log po2(g)
Phase Stability Diagrams for Fe, Ni, and Cr in Presence of O 2 and S 2 at 480 o C log ps2(g) 0 5 10 Fe0.877S FeS Predominance Diagram for FeOS System FeS2 Fe2S3 FeSO4 log ps2(g) 0 5 10 CrS1.17 Cr2S3 Predominance Diagram for CrOS System 15 20 Fe2(SO4)3 15 20 Cr2(SO4)3 25 Fe3O4 25 Cr2O3 30 Fe(A) Fe2O3 30 35 35 40 40 35 Constant value: T / C = 480.00 30 25 20 15 10 5 0 log po2(g) log ps2(g) 0 40 40 35 Constant value: T / C = 480.00 Predominance Diagram for NiOS System 30 25 20 15 10 5 0 log po2(g) Lower Furnace Recovery Boiler Gases High Sulfur (HS) P S2 7.14E10 10 480 o C P O2 6.12E03 5 10 15 20 NiS2 NiS(A) NiS0.84 Ni3S2 NiSO4 Low Sulfur (LS) High Corrosivity w/o O2 (HC) 1.68E10 10 4.32E11 3.92E29 29 3.60E34 34 25 30 Ni(FCC) NiO 35 40 40 35 Constant value: T / C = 480.00 30 25 20 15 10 5 0 log po2(g)
What About Gasifiers?
Low Temperature Gasifier Environment Gas Component Methane Ethane Propene Propane Hydrogen sulfide Methyl Mercaptan Dimethyl sulfide Dimethyl disulfide Hydrogen sulfide Carbon monoxide Carbon dioxide Water vapor Chemical formula CH4 C2H6 C2H4 C3H6 H2S CH3SH (CH3)2S (CH3)2S2 H2 CO CO2 H2O (v) % Wet basis 0.9862 0.0526 0.0987 0.0395 1.4789 0.0122 0.0012 0.0008 44.6459 9.9051 15.2311 27.5481
7day results 7day Weight gain vs. alloy weight gained (mg/cm^2) 120 100 80 60 40 20 0 304 304b 310 7mo 601I 50Cr50Fe alloy
Acknowledgments Dr. Safaa AlHassan Jorge Perdomo Jamshad Mahmood, Tony Clandra DOE (DEFC36 FC3695GO10092) AF&PA ORNL 85XSY627V Mill Personnel IPST Member Companies
Transformation of Major Sulfur Species Devolatilization Time Char Reactions Na 2 CO 3, NaOH, Na 2 O, NaCl Organo Sulfur Na 2 S 2 O 3 Na 2 S Na 2 SO 4 Elemental Sulfur Na 2 SO 3 H 2 S Organo SGasesS Na 2 S V. Sricharoenchaikul, W.J. Frederick and T. M. Grace, J of Pulp and Paper Sci. Vol. 23, No. 8, Aug. 1997
Formation of Mercaptans, Organosulphides and Organodisulfides During BL Pyrolysis RCH 3 S S CH R 3 RCH 2 S x CH 2 R R CH S 3 R CH 3 SH RCH 2 S x H RCH SH SH RCH S H RCH=CHR RCH SH SH SH RCH S SH V. Sricharoenchaikul, W.J. Frederick and T. M. Grace, J of Pulp and Paper Sci. Vol. 23, No. 8, Aug. 1997
Thermobalance for RB Simulation Tests Quartz spring Cathetometer Platinum wire Gas outlet Furnace Test Coupon Pyrex tube Thermocouple Gas inlet Endcap Mass Flow Meters and Controllers Different Gases
Tests in Gasifier Atmosphere Based on MTCI data Particulate matter not included. Log po 2 = 23.53 Log ps 2 = 9.06 Gas Components Mixed 8% H2S in N2 H2 CH4 CO CO2 122 ppm Methyl Mercaptan in N2 12 ppm Dimethyl Sulfide in N2 8 ppm Dimethyl Disulfide in N2 Nitrogen Volume % 19 45 1 10 15 1 1 1 7
High Temperature Gasification High Temperature Operates above melting point of smelt Entrained flow reactor Molten smelt corrosion is an extreme problem * From Chemrec Corporation
Low Temperature Gasification Operates below melting point of smelt H 2 S/reducing environment Fluidized bed reactor Steam Reforming Expected Gaseous Corrosion Sulfidation * From Georgia Pacific Corp.
Metals Tested Sample Fe Cr Ni Mo Si Mn C Other components Carbon Steel Balance 0.5 304L Balance 19 10 0.03 310 Balance 25.45 19.37 0.4 0.63 1.63 0.04 0.170 Cu; 0.021 P; 0.0004 S 7MO Balance 26.48 4.92 1.45 0.25 0.44 0.025 0.180 N; 0.018 P; 0.0005 S Alloy 601 I 14.83 22.16 60.72 0.37 0.27 0.03 1.260 Al, 0.360 Cu 0.001 S 50 Cr 50 Fe 50 50 50 Cr 50 Ni 50 50
Lower Furnace Corrosion o stack Electrostatic precipitator Boiler Superheater Economizer Black liquor spray Smelt Screen Tubes Air delivery: Tertiary Secondary Primary
Corrosion in Black Liquor Combustion Environments Corrosion Rate (mpy) 40.00 35.00 30.00 25.00 20.00 15.00 10.00 Corrosion Rate as a Function of Ratio of P s2 /P O2 and Oxygen Partial Pressures 304L 320oC 304L 480oC SA210 320oC SA210 480oC Alloy625 480oC Alloy625 320oC 5.00 0.00 15.0 10.0 5.0 0.0 5.0 10.0 15.0 20.0 25.0 Log Ratio of (P S2 /P O2 )