SOUTHERN R SEARCH E
I N S T I T U T E
Hg Oxidation Compared for Hg Oxidation Compared for Three Different Commercial SCR Catalysts Three Different Commercial SCR Catalysts
Thomas K. Gale, George A. Blankenship, and W. Scott Hinton Thomas K. Gale, George A. Blankenship, and W. Scott Hinton Southern Research Institute Southern Research Institute Jared W. Cannon, Southern Company Jared W. Cannon, Southern Company Bruce W. Lani, U.S. Department of Energy Bruce W. Lani, U.S. Department of Energy
Acknowledgements
T This project was funded by US Department of Energy National Energy Technology Laboratory's Innovations for Existing Plants Program. T Through cooperative agreement number DEFC26-04NT41900. T We would also like to thank Haldor Topsoe Inc., Cormetec Inc., and Hitachi Corp. for supplying samples of their commercial catalysts for this comparison.
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Outline
T Experimental
S S S S S Furnace and Reactor Catalyst Test Facility Commercial Catalysts Basis for Comparison Test Conditions
T Hg Oxidation as a Function of:
S HCl / NH3 / Temperature
T SO3 Formation Comparison T Conclusions
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Furnace and Reactor
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Catalyst Test Facility
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Honeycomb, Plate, and Hybrid Commercial Catalysts
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Basis for Comparison
350 300 250
NOx ppm
200
Plate-type Honeycomb-type Hybrid-type
150
100
50
0
8:24:00 AM 9:36:00 AM 10:48:00 AM 12:00:00 PM 1:12:00 PM 2:24:00 PM 3:36:00 PM 4:48:00 PM 6:00:00 PM 7:12:00 PM 8:24:00 PM
Time
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Time to Steady State
14000 12000
Inserted Catalyst
HgT Hgo
Hg Concentration (ng/m )
3
10000 8000 6000 4000 2000 0 5:00 PM 6:00 PM 7:00 PM 8:00 PM
Stable Conditions
9:00 PM
10:00 PM
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Time of Day (hr:min)
Test Conditions
Parameter Range for Test Campaign Temperature 650 to 800 °F Flow Rate ~7.5 slpm deNOx >95% deNOx at a ratio of NH3/NO = 1 Gas Concentrations (dry basis, other than H2O) N2 O2 CO2 NO NH3 SO2 HCl H2 O Hg° ~72% by volume ~5 % by volume ~15% by volume 300 ppmv 0.0 ppmv or 300 ppmv 500 ppmv or 1000 ppmv 2 to 100 ppmv ~8% by volume 10 μg/m3
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
DeNOx vs HCL Concentration
100 90 80 70
deNOx (%)
60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 110
Hybrid Honeycomb Plate
HCl Concentration (ppmv)
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Hg Oxidation Across Plate Catalyst at 700 oF
1.0 with NH3 0.8 R2 = 0.999 wo NH3 R2 = 0.858
Hg /Hg
o
T
0.6
0.4
0.2
0.0 0 10 20 30 40 50 60 70 80 90 100 110
HCl (ppmv)
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Hg Oxidation Across Hybrid Catalyst at 700 oF
1.0 0.9 with NH3 0.8 0.7
T
R2 = 0.93 wo NH3 R2 = 0.93
0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 10 20 30 40 50 60 70 80 90 100 110
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Hg /Hg
o
HCl (ppmv)
Hg Oxid. Across Honeycomb Catalyst at 700 F
o
1.0 0.9 0.8 0.7
T
with NH3 R2 = 0.890 wo NH3 R2 = 0.588 w/NH3 @ 750 oF wo/NH3 @ 750 oF
0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 10 20 30 40 50 60 70 80
Hg /Hg
o
90
100
110
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
HCl (ppmv)
Temperature dependence of mercury oxidation
1.0 0.9 0.8 0.7
T
Plate w/NH3 Plate wo/NH3
@ 2 ppm HCl
Plate w/NH3 Hybrid w/NH3 Honeycomb w/NH3
0.6 0.5 0.4 0.3 0.2 0.1 0.0 625 650 675 700 725 750 775
Hg /Hg
o
@ 25 ppm HCl
800
825
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Temperature (oF)
Effect of Ammonia in the Presence of 300 ppmv NO
1.0 0.9 0.8 0.7
T
1 ppmv HCl R2 = 0.997 2 ppmv HCl
0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375
Hg /Hg
o
NH3 (ppmv)
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Effect of NO on Hg Oxidation
1.0 0.9 0.8 0.7
T
with 300 ppmv NO without NO
0.6 0.5 0.4 0.3 0.2 0.1 0.0 0 10
In the Absence of NH3
Hg /Hg
o
20
30
40
50
60
70
80
90
100
110
HCl Concentration (ppmv)
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
Comparison of SO3 Formation
40
Plate w/NH3 Plate wo/NH3 SO3 Concentration (ppmv)
30
Hybrid w/NH3 Hybrid wo/NH3 Honeycomb w/NH3 Honeycomb wo/NH3
20
10
0 0 20 40 60 80 100 120
Mercury Control Mercury Control Technology Conference Technology Conference December 2006
HCl Concentration (ppmv)
Conclusions
T All three catalysts performed similarly for mercury oxidation and SO2/SO3 conversion. T NH3 may inhibit Hg oxidation at Power Plants with very little HCl in the flue gas. T NH3 had little effect with higher HCL levels. T Absence of NH3 allowed significantly more SO2/SO3 conversion, independent of HCl. T Increased mercury oxidation can be obtained across an SCR catalyst by increasing HCl concentrations, regardless of temperature, catalyst type, or the presence of ammonia, and without increasing SO2/SO3 conversion.
Mercury Control Mercury Control Technology Conference Technology Conference December 2006