SCR Catalyst Management and Improvement to Achieve and ...May 11, 2018 · Entering FGD Net Hg Capture Efficiency by FGD Hg2+ Capture Efficiency Hg0 Oxidation of Hg Hg2+ Hg Re-emission

SCR Catalyst Management

and Improvement to Achieve and

Maintain Mercury Oxidation Levels

Christopher Bertole

Cormetech, Inc.

VGB Workshop “Flue Gas Cleaning 2013”

weckera

Stempel

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




• Background

– MATS







• Summary



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



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



• 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



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



• 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




• Background

– MATS







• Summary



% 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%



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!



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!




• Background

– MATS







• Summary



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)



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)




• Background

– MATS







• Summary



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



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.



Management Plan

w/ DeNOx Potential & Hg Oxidation Performance:

85% DeNOx

Max NH3 slip = 2 ppm



Management Plan

w/ DeNOx Potential & Hg Oxidation

Target 80% Ox. Hg

Action: Inject Halogen



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



Management Plan

w/ DeNOx Potential & Hg Oxidation Target 90% Ox Hg

Action: Initially change 2

layers to Max length

COMET ™ and inject

Halogen



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”

Documents

SCR Catalyst Management and Improvement to Achieve and ...May 11, 2018 · Entering FGD Net Hg Capture Efficiency by FGD Hg2+ Capture Efficiency Hg0 Oxidation of Hg Hg2+ Hg Re-emission