SCR Catalyst Management
and Improvement to Achieve and
Maintain Mercury Oxidation Levels
Christopher Bertole
Cormetech, Inc.
VGB Workshop “Flue Gas Cleaning 2013”
Page 2 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Presentation Outline
• Background
– MATS
– SCR Hg Oxidation Co-Benefit
– Key Differences Between Hg and NOx Control
• Catalyst Management for NOx, Hg, SO3 Control
– Assess Unit Requirements
– Characterize Installed Catalyst
– Select Optimal Catalyst Action
• Summary
Page 3 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Presentation Outline
• Background
– MATS
– SCR Hg Oxidation Co-Benefit
– Key Differences Between Hg and NOx Control
• Catalyst Management for NOx, Hg, SO3 Control
– Assess Unit Requirements
– Characterize Installed Catalyst
– Select Optimal Catalyst Action
• Summary
Page 4 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
MATS Mercury and Air Toxics Standard
• Focuses on:
– Hg
– HCl (as a surrogate for acid gas HAP)
– Filterable PM (as a surrogate for non-Hg HAP metals)
• Requires compliance by 2015
– Published in US Federal Register on February 16, 2012
– Provides utilities with 3-year period to achieve compliance
– 1 additional year is available (i.e., comply by 2016), if needed for
technology installation
• Limits stack Hg emissions for existing units to:
– 1.2 lbs Hg/Tbtu
– 30 operating day rolling average basis
Page 5 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
①Elemental
③Particle bound
②Oxidized
(Hg0)
(Hg2+)
(Hg(p)) FGD Hg Capture
Air
Heater
Particulate Control Device
FGD
Stack
DeNOx and
Hg Oxidation
by Halogens
Boiler
SCR APH
SCR Co-Benefit for Hg Removal
ESP FGD
Page 6 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
• DeNOx – Performance requirements
for the SCR are typically well
defined due to sole role of
the SCR for NOx reduction
• Hg – Performance requirements for the
SCR typically not as well defined
due to roles of downstream
equipment in total compliance
Air
Heater
Particulate Control Device
FGD
Stack
DeNOx and
Hg Oxidation
Boiler
SCR APH
Key Differences for Hg vs. NOx Hg Control Requires a Full System View
Page 7 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Key Differences for Hg vs. NOx More Factors Influence Hg Oxidation
DeNOx
– Key Parameters
• NOx inlet
• Efficiency
• Slip
• Temperature
• SO2 conversion (formulation)
• Fuel contaminants
K/Ko
• Reactor condition
• O2, H2O, SO2 (lower impact)
Hg
– Key Parameters
• NOx inlet
• Efficiency
• Slip
• Hg oxidation Performance Threshold
• Temperature
• SO2 conversion (formulation)
• Fuel contaminants K/Ko
• Reactor condition
• Halogen (Fuel or additive)
• Layer position (NH3)
• CO
• O2, H2O, SO2 (can be larger impact)
NH3 Performance
Threshold
Page 8 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
• Hg Oxidation KHgOx/AV defines:
- Capacity for X% Hg oxidation
• Activity, KHgOx, depends on:
- Catalyst composition and age
- Flue gas conditions (+HCl, HBr, NH3, CO, SO2, HC)
• AV = Area Velocity = (Gas Flow) / (Total GSA)
• First order rate equation can be applied for Hg
oxidation tests, but be careful! This K value is strongly
condition dependent!
HgOxAV
KHgOx
%1ln
Key Differences for Hg vs. NOx Hg Ox Catalyst Potential, K/AV
Page 9 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Presentation Outline
• Background
– MATS
– SCR Hg Oxidation Co-Benefit
– Key Differences Between Hg and NOx Control
• Catalyst Management for NOx, Hg, SO3 Control
– Assess Unit Requirements
– Characterize Installed Catalyst
– Select Optimal Catalyst Action
• Summary
Page 10 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
% Removal Required
@ 1.2 lb/TBTU 40%-70%
70%-80%
80%-87%
87%-92%
92%-96%
96%-98% Source: Utah Geological Survey
Key factors: Hg in Coal (% Removal @ 1.2 lb/TBTU emission)
Chinese coals Hg content range: 1-60 lb/Tbtu
(ref: H emissions & speciation coal fired power plants,
Wang et al., 2009)
70-80%
70-92%
80-98%
70-96%
Page 11 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Source: Utah Geological Survey
~ 20-200 ppmw
~ 2500-4500 ppmw (@
SC
R o
utlet)
Key factors: Chlorine in Coal
Typical Chinese coal range for HCl = 63-118 ppmw
(ref. Wang et al. 2009), but Br appears to be higher.
Low!
High and Low!
Page 12 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Key Factors Impacting Hg Emissions
with SCR Co-Benefits Mercury
Emissions
Hg0 Hg2+
Entering FGD
Net Hg Capture
Efficiency by FGD
Hg2+ Capture
Efficiency Hg Re-emission Hg0 Hg2+
Outlet from SCR
Oxidation of Hg
across APH
Hg Removal by
Particulate Control
Hg0 Hg2+
Inlet to SCR
Oxidation of Hg0
by SCR
HCl and HBr in
flue gas
SCR temperature
and flow (load)
HCl (and HBr)
in coal Added HCl or HBr
Flue gas: H2O,
SO2, CO, NH3, etc. Total Hg in Coal SCR catalyst Hg
oxidation activity
Catalyst Design &
Layer Mgmt Catalyst age
(each layer)
Catalyst Geometry and
condition (plugging, etc)
Catalyst Formulation for
DeNOx, SO2 ox, Hg ox
DeNOx and Hg ox
deactivation prediction SCR
FGD
SCR catalyst
Hg & Halogens in
APH & PC
Key
(ACI Separate)
Seasonal Impacts
(temperature, load)
%Hg oxidation needed and obtained
from SCR depends on many factors!
Page 13 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Presentation Outline
• Background
– MATS
– SCR Hg Oxidation Co-Benefit
– Key Differences Between Hg and NOx Control
• Catalyst Management for NOx, Hg, SO3 Control
– Assess Unit Requirements
– Characterize Installed Catalyst
– Select Optimal Catalyst Action
• Summary
Page 14 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Test Reactor Capabilities
• Collected Hg oxidation data
for development, designs,
deactivation studies, and
quality assurance since 2002.
• Allows characterization of
catalyst of any type/vintage.
Courtesy of:
Continuous
Hg analyzer
Cormetech Mercury Activity Test Reactor System
Coming Soon: FALL 2013! Cormetech pilot reactor with Hg oxidation test capability
(reactor can load up to 4 full length/cross-section layers)
Page 15 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Layer Dependency Influenced by Temperature and Halogen Level
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0 20 40 60 80 100 120
Ra
tio
K
Hg
Ox/A
V
To
p/L
ow
er
HCl [ppmvda]
400C
340C
DeNOxAV
K%1ln HgOx
AV
KHgOx
%1ln
- Due NH3 inhibition, Hg oxidation potential depends on layer position.
- The degree of dependency is dependent on temperature and halogen content.
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.0 1.0 2.0 3.0HBr [ppmvda]
400C
For Illustration
@ MR=1 f(variable MR)
Page 16 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Presentation Outline
• Background
– MATS
– SCR Hg Oxidation Co-Benefit
– Key Differences Between Hg and NOx Control
• Catalyst Management for NOx, Hg, SO3 Control
– Assess Unit Requirements
– Characterize Installed Catalyst
– Select Optimal Catalyst Action
• Summary
Page 17 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Catalyst Design Balance
K/AV Needs (NOx)
SO3 Costs
Mitigation Cost
Corrosion
Visible Plume
NH3 Slip
NOx Removal
Life
Historical:
Catalyst is formulated to achieve
DeNOx requirements, while
meeting SO2 oxidation constraints.
Moving forward:
Catalyst is formulated to achieve
DeNOx and Hg oxidation requirements,
while meeting SO2 oxidation constraints.
K/AV Needs (NOx, Hg)
SO3 Costs
Mitigation Cost
Corrosion
Visible Plume
NH3 Slip, Halogens
NOx, Hg Removal
Life
Page 18 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Catalyst Improvements
Constants
Temp C 403
NOx ppm 107
O2 % 3.5
H2O % 14
SO2 ppm 345
HCl ppm 8
Need for advanced catalysts is driven by
Hg oxidation requirements of a given unit!
Comparison between COMET and Standard catalyst
samples here was done at same SO2 oxidation level.
Page 19 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Management Plan
w/ DeNOx Potential & Hg Oxidation Performance:
85% DeNOx
Max NH3 slip = 2 ppm
Page 20 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Management Plan
w/ DeNOx Potential & Hg Oxidation
Target 80% Ox. Hg
Action: Inject Halogen
Page 21 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Management Plan
w/ DeNOx Potential & Hg Oxidation Target: 90% Ox. Hg
Action: Initially change
2 layers to Max length
COMET ™ and repeat
for layer 3
Page 22 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Management Plan
w/ DeNOx Potential & Hg Oxidation Target 90% Ox Hg
Action: Initially change 2
layers to Max length
COMET ™ and inject
Halogen
Page 23 VGB Workshop “Flue Gas Cleaning 2013”
Rotterdam, Netherlands
Summary
• Catalyst additions and replacements can be managed to
maintain Hg oxidation in a manner analogous to that for
DeNOx, but with a few key differences:
– Performance threshold (dependency on downstream equipment)
– Layer dependency
• Layer location and NH3 inlet to each layer must be considered
– More factors are needed in setting design conditions
• HCl, HBr, CO
• More significant impacts of Temperature, O2, and H2O
• Understanding these dependencies, factors, requires
thorough demonstrated testing capability, catalyst
technology and application know-how.
can help you evaluate and meet Hg Emissions Goals
Thank You!
Questions/Discussion
Christopher Bertole
Cormetech, Inc.
VGB Workshop “Flue Gas Cleaning 2013”
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