McIlvaine “Hot Topic Hour Hot Topic Hour”

June 30, 2011

Fuel Impacts on Design and

Performance of SCR Catalysts

Presenter:

John Cochran

Performance of SCR Catalysts

CERAM Environmental, Inc.

+1 913 239 9896 

john.cochran@ceram-usa.com
Catalyst Deactivates With 

Time of Ex

posure to Flue Gas

Ko (Original Catalyst Activity) 

ctivity)

Coal/Heavy PCoal Low DusCoal High Dus

 (Relative AcCoal High Dus

Biomass Waste High D

K/Ko K/Ko @ 1

0 2000 4000 6000 8000 10000 12000 14000 16000

Operation [hrs]

Catalyst Design (at hour=0) Must Anticipate Deactivatio

Guarantee Period (e.g., 16,000 hours) to Size Catalys
Catalyst Deactivation is 

Very Site Very Site Specific

K/Ko vs Time 

0 91.00.70.80.9

vity

0.40.50.6

Relative Activ

0.10.20.3

R

0.0

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

Hours of SCR Operation

Varying Based on Fuel Quality and Operations Varying Based on Fuel Quality and Operations
Catalyst Deactivation Mechanisms

 Gaseous Poisons:

 Arsenic Phosphorus

Pt i

Activity)

Coal/HCoal LCoal H



P

o

tass

ium

 Sodium Cadmium

L d

K/Ko (Relative A Bioma

Waste 



Lea

d

 Copper Other Elements 

0 2000 4000 6000 8000 10000 12000 14000 16000

Operation [hrs]

 Foulin

g b

y Solid Compounds

 Gypsum (Calcium Sulfate) and Other Solid Compoun Ammonium Bisulfate (Avoided by Keeping Above Pe

T t) empera

tures

)

 Occurs During... 

 Normal SCR Operation S d Sh d i G h h A id 

Startups an

d Shut

downs as Un

it 

Goes T

hrough

A

cid D
Catalyst Deactivation

 Vanadium-Titania Based Catalyst Deactivates Based on Site S

Based Catalyst Deactivates Based on Site S

 Fuel Quality – Arsenic, Phosphorus, Potassium, Sodium, S

Calcium, etc.

 Comb stion Q alit Combustion Quality – Increased S bstoichiometric Stagin

Increased Substoichiometric Stagin

Quantity of Gaseous Poisons

 # of Startups and Shutdowns

 V di ana um-Tit i an a B d C t l t D ti t Based Catalyst Deactivates Id d t n ependent of

 Catalyst Type – Plate, Honeycomb, Corrugated Fiber Formulation – Different Activities and SO2:3 Conversion  Reference Also “Comparison of Deactivation Rates of Dif

Catalyst Types” by Ed Healy, Southern Company and HanHartenstein, Evonik (now Steag) Presented February 9, 20

h // i h ld i l / bli /47b 6d6 7 8f479388 20d66579738f8/H %20H http://www.reinholdenvironmental.com/public/47bc6d6a7e8f479388a20d66579738f8/Hans%20Harten%20Deactivation%202009.pdf

 Deactivation Resistance Comes From Providing Adequate Re

Potential ( ) RP=K/Av) – There Are No Magic Potions
Case Example 1: Two x 500 MW Unit 

PRB Deactivation Rate History

Being Considered

0.91.0

2 x 500 MW Units - Plate and Honeycomb Catalyst Deactivation Trends

0.70.8

ctivity K/Ko

0 40.50.6

Relative Ac

0.30.4

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50

Time of Exposure to Flue Gas, hours

 Original Supplier’s (Plate by Others) Estimate of Deac

U d B i f C t l tD i

K/Ko Design Basis of Original Plate Supplier Expected Deactivation Trend



Use

d as 

Basis 

for 

C

a

t

alys

t

Design
Case Example 1: Two x 500 MW Unit 

PRB Deactivation Rate History

Being Considered

0.91.0

2 x 500 MW Units - Plate and Honeycomb Catalyst Deactivation Trends

0.70.8

ctivity K/Ko

0 40.50.6

Relative Ac

0.30.4

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50

Time of Exposure to Flue Gas, hours

 Deactivation Rate Assumed by Original Plate Catalyst 

Proven to be Overly Optimistic

K/Ko Design Basis of Original Plate Supplier Expected Deactivation TrendPlate Catalyst Test Results (Original Supplier)

Proven to be Overly Optimistic
Case Example 1: Two x 500 MW Unit 

PRB Deactivation Rate History

Being Considered

0.91.0

2 x 500 MW Units - Plate and Honeycomb Catalyst Deactivation Trends

0.70.8

ctivity K/Ko

0 40.50.6

Relative Ac

0.30.4

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 50

Time of Exposure to Flue Gas, hours

 Deactivation Rate Assumed by Original Plate Catalyst 

Proven to be Overly Optimistic

K/Ko Design Basis of Original Plate Supplier Expected Deactivation TrendPlate Catalyst Test Results (Original Supplier) Honeycomb Catalyst Test Results (2 Sup

Proven to be Overly Optimistic

 Subsequent Replacements With Honeycomb Catalyst F

Different Suppliers Confirms Both Types Deactivate BSame Trend
Case Example 2: 600 MW Unit Burning 

Eastern Bituminous High Arsenic/Low Calciu

0.9

1

Relative Activity Vs Time

600 MW Unit With High Arsenic and Low CaO

Fuels Burned Different Than 

0 60.70.80.9

K/Ko)

Originally Specified Resulting in 

Extreme Deactivation

0 30.40.50.6

elative Activity (K

0

0.10.20.3

Re Honeycomb Catalyst Test Results

Corrugated Fiber Catalyst Test ResultsProjected DeactivationExpected Activity for Specified Fuel (16khr)Current Deactivation Trend (16khr)

0

0 5,000 10,000 15,000 20,000

Exposure to Flue Gas (hrs)

 Original Deactivation Rate Underestimated Based on C

S ifi i Specification

 Catalyst Test Results For Honeycomb and Corrugated 

Confirms Both Types Deactivate Based on The Same T
Why is Estimating Catalyst

Deactivation So Important

 If Deactivation is Underestimated 

 Catalyst is Undersized I bl f M ti NO R l d A i Sli P 

Incapable o

f

Meeting NOx 

Remova

l an

d

Ammon

ia Slip 

P

at Some Point During the Guarantee Period

 Deficient Performance is Either Tolerated or an Early Out

(Unscheduled) is Required for Catalyst Addition (Unscheduled) is Required for Catalyst Addition

 Catalyst Management Costs are Underestimated

 Understanding and Managing Reactor 

Potential Critical to Minimize Risk Potential Critical to Minimize Risk

 Examples Help to Illustrate Risk
Reactor Potential

Can be represented by 

P = K/AV

K = catalyst activity, Nm

3/m

2h or Nm/h

AV = catal

yst area velocit

y, Nm/h (normalized 

operating gas flow, Nm

3/h divided by total installed 

catalyst surface area, m

2

)
DeNOx Demand Reactor Potent

 DeNOx Demand = The reactor potenti

to meet NOx removal and ammonia slirequirements at the specified operating 

at the specified operating 

 Calculated based on NO

X removal requ

NH

3 slip, SCR distributions, and boiler 

conditions (flow temperature pressure conditions (flow, temperature, pressure

 Independent of catalyst design life (i.e. 

for 16,000 or 24,000 hour catalyst life)

 Id d t n

depen

den

t

of C t l t T F l 

f

C

a

t

a

lys

t

Type, 

Formu

l

a

Manufacturer
DeNOx Demand, Reactor Potential, & Catalyst De

1. Determine DeNOx D

1. DeNOx demand (Preq) is the amount of reactor potential necessary to achieve N

and ammonia slip performance based on fixed operating conditions (flows temand ammonia slip performance based on fixed operating conditions (flows, tem
DeNOx Demand, Reactor Potential, & Catalyst De

2 E ti t C t l t D ti ti (

K

/

K )

1. Determine DeNOx D

2. E

stimate 

C

atalyst Deactivation (K

e

/

K

o)

Varies as Function of Design Life

1. DeNOx demand (Preq) is the amount of reactor potential necessary to achieve N

and ammonia slip performance based on fixed operating conditions (flows temand ammonia slip performance based on fixed operating conditions (flows, tem

2. Catalyst deactivation is estimated based on fuel quality, combustion parameters
DeNOx Demand, Reactor Potential, & Catalyst De

3. Determine Initial Reactor Potential

2 E ti t C t l t D ti ti (

K

/

K )

3. Determine Initial Reactor Potential

Required (P

o)

1. Determine DeNOx D

2. E

stimate 

C

atalyst Deactivation (K

e

/

K

o)

Varies as Function of Design Life

1. DeNOx demand (Preq) is the amount of reactor potential necessary to achieve N

and ammonia slip performance based on fixed operating conditions (flows temand ammonia slip performance based on fixed operating conditions (flows, tem

2. Catalyst deactivation is estimated based on fuel quality, combustion parameters3. Based on DeNOx demand and deactivation the initial reactor potential (Po) is d
DeNOx Demand, Reactor Potential, & Catalyst De

3. Determine Initial Reactor Potential

2 E ti t C t l t D ti ti (

K

/

K )

3. Determine Initial Reactor Potential

Required (P

o) 4. Determine Cat

fn(Ko, geometry, 

1. Determine DeNOx D

2. E

stimate 

C

atalyst Deactivation (K

e

/

K

o)

Varies as Function of Design Life

1. DeNOx demand (Preq) is the amount of reactor potential necessary to achieve N

and ammonia slip performance based on fixed operating conditions (flows temand ammonia slip performance based on fixed operating conditions (flows, tem

2. Catalyst deactivation is estimated based on fuel quality, combustion parameters3. Based on DeNOx demand and deactivation the initial reactor potential (Po) is d4. Catal

yst volume is determined based on Po, catal

yst activity,

geometry, SO

2 to 

y , y y, g y, 

2 

rate, and various gas conditions and constituents
Comparison of Catalyst Design Case

1.6

)

Proposal 1: 'Conservative' Design Case (0.65 K/Ko @16 khr)

1.4

or Potential (K/AVRequired Reactor Potential Guaranteed Life

1.2

Relative Reacto

1.0

 Pro

posal 1 Has the Most Conservative K/Ko Basis 

(0.65 

0.8

0 4000 8000 12000 16000 

Hours ofOperation

p (
Comparison of Catalyst Design Case

1.6

)

Proposal 1: 'Conservative' Design Case (0.65 K/Ko @16 khr)Proposal 2: 'Aggressive' Design Case (0.72 K/Ko @16 khr)

Variance in Reactor Potential

Consists of Volume, Surface

Area and/or K Differences

1.4

or Potential (K/AV Required Reactor Potential Guaranteed Life Area and/or K Differences

1.2

Relative Reacto

1.0

 Pro

posal 2 is Based on a More Aggressive Deactivation R

0.8

0 4000 8000 12000 16000 

Hours ofOperation

p gg 

 Approximately 10% Difference in Catalyst Volume Who is Right?
Case A: Proposal 1 Deactivation Rate Co

1.6

)

Proposal 1: 'Conservative' Design Case (0.65 K/Ko @16 khr)Proposal 2: 'Aggressive' Design Case (0.72 K/Ko @16 khr)

1.4

or Potential (K/AV0.72 K/Ko Based Proposal 2 Operating at 0.65 K/Ko @16 khr Required Reactor Potential Guaranteed Life

1.2

Relative Reacto

1.0

Reduced Catalyst Life Since

Proposal 2 Was Undersized

 Should a K/Ko of 0.65 Actuall

y Occur Pro

posal 2 Would 

0.8

0 4000 8000 12000 16000 

Hours ofOperation

y p

and Meet Performance for Less Than 11,000 Hours

 Early Outage Required or Reduced Performance Must be 
Case B: Proposal 2 Deactivation Rate Co

1.6

)

Proposal 1: 'Conservative' Design Case (0.65 K/Ko @16 khr)Proposal 2: 'Aggressive' Design Case (0.72 K/Ko @16 khr)

1.4

or Potential (K/AV0.65 K/Ko Based Proposal 1 Operating at 0.72 K/Ko @16 kh

Required Reactor Potential Guaranteed Life

1.2

Relative Reacto Increased Catalyst Life

1.0

 Should a K/Ko of 0.72 Actuall

y Occur Pro

posal 1 Would 

0.8

0 4000 8000 12000 16000 20000 24000 28000

Hours ofOperation

y p

and Meet Performance for More Than 24,000 Hours (>3 

 Catalyst Management Costs Greatly Reduced
Unstaged PRB Fired Units Catalyst Deactivation

Group 1: PRB Unit Catalyst Activity Test R

1.01.20.60.8

tive Activity K/Ko

0.2

Rela 0.4

0.0

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000 

Exposure to Flue Gas, hours

Plant 7 PC Plant 8 PCPlant 9 Cyclone Plant 10 PC

 “Unstaged” PRB Units Indicate a K/Ko @ 16,000 hou

Plant 9 Cyclone Plant 10 PCPlant 11 PC Plant 12 CyclonePlant 13 Cyclone Plant 14 CycloneGeneral Deactivation Trend - Unstaged PRB Units

g @

 Wide Variation of Results Dependent on Many Operat

Variables
Catalyst Deactivation for "Deeply Staged" PRB Units

Group 2: PRB Unit Catalyst Activity Test Re

1.01.2

o

Catalyst Deactivation for "Deeply Staged" PRB Units

0.60.8

ative Activity K/K

0.20.4

Rel

Plant 1 PC Plant 2 PCPlant 3 Cyclone Plant 4 CyclonePlant 5 Cyclone Plant 6 PCOther Deeply Staged General Trend Plant 6 PC General Trend

0.0

0 5,000 10,000 15,000 20,000 25,00

Exposure to Flue Gas, hours

py g

 Combustion Conditions Greatly Affect PRB Application Deactivation Rates Combustion Conditions Greatly Affect PRB Application Deactivation Rates Broad Consensus of Results for “Deeply Staged” Units Confirm Severe Deactivat Highly Risky if Plant 6 Alone Was Selected as a Reference Unit to Support Propo A Plant 6 Based Catal

y g st Desi

gn Will Last Less Than One Year on a 24,000 Hour 

Deep Deactivation Seen for Broader Experience
Summary

 Deactivation Rates Vary Widely Dependent on Site Specifics

 Fuel Quality, Combustion Parameters, and Boiler Duty Cycle 

Affect Catalyst Deactivation Rates

 Vanadium-Titania Based Catalysts All Deactivate at the Same Ra

Site Specifics

 Underestimating or Aggressive Sizing Compromises SCR Perfor

Underestimating or Aggressive Sizing Compromises SCR Perfor

Effective Catalyst Management

 Risk of Early Outage for Catalyst Additions Risk of Deficient Performance

 Initial SCR Project Design Should Carefully Consider Reactor Po

Determine the Risk Profile of Various Proposals

 Aggressive Catalyst Designs Can Result in Operations Diffic

Increased Cost