MP303

Diagnostic Tools for Gas Turbine

CO and SCR Systems

L. J. Muzio, R. A. Smith Fossil Energy Research Corp.

Laguna Hills, CA

Reinhold 2016 NOx-Combustion Round Table February 1, 2016

Orlando, Florida

MP303 2

Simple Cycle Gas Turbine SCR

Ammonia Injection Grid (AIG) SCR Catalyst

Diffuser Vanes

Flue gas

750-1000°F

• SCR Performance Parameters:

- NOx Reduction

- Ammonia Slip

• Uniform NH3/NOx Profile

at Catalyst Inlet is Critical!

CO Catalyst

Tempering Air

NH3 Dilution Air

NH3

Perforated Plate

MP303 3

Cogeneration Gas Turbine SCR

Ammonia Injection Grid (AIG) SCR Catalyst

• No Diffuser Vanes

• No Perforated Plates

• No Tempering Air

Flue gas

~550-650°F

• SCR Performance Parameters:

- NOx Reduction

- Ammonia Slip

• Uniform NH3/NOx Profile

at Catalyst Inlet is Critical!

CO Catalyst

NH3 Dilution Air

NH3 Steam Tube Banks

MP303 4

Optimizing Gas Turbine SCR Performance

• Troubleshooting - How to Distinguish NH3 Maldistribution from Bypass

• AIG Tuning - Catalyst Inlet NH3/NOx Distribution

• Identifying Flue Gas Bypass

• Catalyst Management/Measuring Catalyst Activity

Topics

MP303

What Can Lead to Non-Compliance:

NH3/NOx Maldistribution, Bypass?

0

2

4

6

8

10

0 2 4 6 8 10

NH

3 S

lip, p

pm

NOx, ppm

Measurement Limit

5

MP303

Stack NH3 vs. NOx

NH3/NOx RMS Effects Bypass Effects

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12 14

NH

3 S

lip, p

pm

@1

5%

O2

dry

NOx, ppm@15%O2 dry

RMS=10% RMS=20% RMS=30%

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12 14

NH

3 S

lip, p

pm

@1

5%

O2

dry

NOx, ppm@15%O2 dry

ByPass=0% ByPass=2.5% ByPass=5% ByPass=7.5%

A simple stack test can distinguish • NH3 Maldistribution

• Flue Gas Bypass

6

MP303

Stack NH3 vs. NOx

NH3/NOx RMS Effects Bypass Effects

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12 14

NH

3 S

lip, p

pm

@1

5%

O2

dry

NOx, ppm@15%O2 dry

RMS=10% RMS=20% RMS=30%

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12 14

NH

3 S

lip, p

pm

@1

5%

O2

dry

NOx, ppm@15%O2 dry

ByPass=0% ByPass=2.5% ByPass=5% ByPass=7.5%

0

2

4

6

8

10

0 5 10 15 0

2

4

6

8

10

0 5 10 15

7

MP303

Stack NH3 vs. NOx

NH3/NOx RMS Effects

Effects Bypass Effects

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12 14

NH

3 S

lip, p

pm

@1

5%

O2

dry

NOx, ppm@15%O2 dry

RMS=10% RMS=20% RMS=30%

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12 14

NH

3 S

lip, p

pm

@1

5%

O2

dry

NOx, ppm@15%O2 dry

ByPass=0% ByPass=2.5% ByPass=5% ByPass=7.5%

How to best generate this data? • Wet Chemical NH3 measurements?

• Continuous NH3 measurements?

8

MP303

TDL Instrumentation

• Testing facilitated using a

continuous TDL NH3

analyzer

• Data set can be generated

in less than a day

• Data available in real time

• Unisearch NH3 TDL • Dual Path

• Two Channel

• Fiber Optic Coupled

9

MP303

NH3-TDL Lines of Site

Gas

Flow

NH3 TDLOptical Paths

10

MP303

TDL NH3 Measurements on a Large Combined Cycle

NH3/NOx RMS Effects Bypass Effects

0

5

10

15

20

25

30

35

40

0 5 10 15 20

NH

3 S

lip

, pp

m@

15

%O

2 d

ry

NOx, ppm dry

RMS=10% RMS=20% RMS=30% Test Data

0

5

10

15

20

25

30

35

40

0 5 10 15 20

NH

3 S

lip

, pp

m@

15

%O

2 d

ry

NOx, ppm dry

Test Data ByPass=0% ByPass=2.5%

ByPass=5% ByPass=7.5%

11

MP303

AIG Tuning

12

MP303

Gas Turbine SCR AIG Tuning

• Tuning is Facilitated by Installing a Permanent Sample Grid at

the Catalyst Exit:

• Not feasible to manually traverse a large combined cycle

system for AIG tuning

• Typically need 36 to 60 probes depending on AIG design

• With Permanent Probes Tuning can Typically be done in One

Day

• The NOx Profiles at the Exit of the Catalyst can also Help

Identify Bypass

13

MP303

NH3/NOx Distribution and AIG Tuning

0

2

4

6

8

10

70 80 90 100

NOx Reduction, %

NH

3 S

lip

, pp

m

New Catalyst

Catalyst Near

End-of-Life

0

2

4

6

8

10

70 80 90 100

NH

3 S

lip

, pp

m

RMS=5% RMS=10% RMS=15% RMS=25%

14

MP303

How Well is Your AIG Tuned? (As Found RMS Values)

15

Most of the GT AIGs we encounter are not tuned very well!

0

5

10

15

20

25

30

35

40

RM

S (%

)

MP303

How Important is the NH3/NOx Distribution?

• SCAQMD is pushing NOx from 5 to 2 ppm in So. Cal.

• Assumption is that just adding more catalyst will be the solution

• Just tuning the AIG allows 2 ppm NOx to be achieved

• Adding 50% more catalyst helps, but not as much as tuning

RMS=20% Add Catalyst Tune AIG To RMS=10%

16

0

1

2

3

4

5

6

7

8

9

10

11

12

0 1 2 3 4 5 6

NH

3 s

lip

, p

pm

@1

5%

O2

dry

NOx, ppm@15% O2 dry

K=80/RMS=20% RMS=20%, 25% More Cat

0

1

2

3

4

5

6

7

8

9

10

11

12

0 1 2 3 4 5 6

NH

3 s

lip, p

pm

@1

5%

O2

dry

NOx, ppm@15% O2 dry

K=80/RMS=10% K=80/RMS=20%

MP303

Outside View of a Permanent Sample Grid on a

Large Combined Cycle

Sample probe exit

ports

Sample probe

lines brought

down to grade

17

MP303

Sample Probes Attached to Catalyst Modules

18

MP303

FERCo’s Multipoint Instrumentation

• Samples 48 points in 15

minutes

• NOx and O2

19

MP303

AIG Design Affects Tuning

20

• No Adjustments: Some systems have no

adjustment valves- Bad Idea!

• 1-D: Commonly used design

• Multi Zone: Better

Two Horizontal Zones Horizontal and Vertical Lances Three Horizontal Zones

MP303

AIG With No Adjustability

21

MP303

AIG: No Adjustability

22

Permanent

Probe Grid for

Tuning.

Difficult to

Tune Without !

MP303 23

Normalized NH3/NOx Profiles – As Found

Orig. AIG RMS = 35%

NH3 Header

0 5

Bottom of the Duct

0

5

10

15

20

25

30

35

40

45

50

No

rth

Wa

ll (f

t)

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

NH3 Header

MP303 24

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

No

rmali

zed

Mass F

low

Case 2 - Modified AIG Design, RMS = 0.9%

0.5

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

No

rmali

zed

Mass F

low

Case 1 - Current AIG Design, RMS = 20.6%

CFD RESULTS

North Wall North Wall Top of

Duct

Top of

Duct

Ammonia Enters This Side

MP303 25

Normalized NH3/NOx Profiles – Before & After

All Holes Resized RMS = 16% Orig. AIG RMS = 35%

0 5

Bottom of the Duct

0

5

10

15

20

25

30

35

40

45

50

No

rth

Wa

ll (f

t)

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

0 5

Bottom of the Duct

0

5

10

15

20

25

30

35

40

45

50

No

rth

Wa

ll (f

t)

0.4

0.9

1.4

NH3 Header NH3 Header

MP303

Duct Burners Impact AIG Tuning

Duct Burners Off

(Inlet NOx ppm) Duct Burners On

(Inlet NOx ppm)

AIG Difficult to Tune

NH3

0 5 100

5

10

15

20

25

30

35

40

0 5 100

5

10

15

20

25

30

35

40

26

MP303

AIG Tuning, 1-D AIG Design; NH3/NOx

As Found, RMS = 22% Tuned, RMS = 13%

0 2 4 6 8

Duct Bottom (ft)

0

2

4

6

8

10

12

14

16

18

No

rth

Wa

ll (f

t)

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1.4

1.45

1.5

1.55

Riverside Springs Unit 4 SCRBaseline NH3/NOx Distribution,

Catalyst Inlet

RMS = 22%

0 2 4 6 8

Duct Bottom (ft)

0

2

4

6

8

10

12

14

16

18

No

rth

Wa

ll (f

t)

0.7

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

1.25

1.3

1.35

1.4

1.45

1.5

1.55

Riverside Springs Unit 4 SCRNH3/NOx Distribution, Adjustment #1

Catalyst Inlet

RMS = 13%

Adjustments

across the

width

not possible

NH3

27

MP303

AIG Tuning, 1-D AIG Design; Outlet NOx Port Westward

0 5 10 15 20 25

Duct Bottom (ft)

0

5

10

15

20

25

30

35

40

45

50

55

60

We

st

Wa

ll (f

t)

Test 01, Full Load, 8-6-2012Raw NOx Profile

Filename: Port Westward NOx01

Flow into the page

-1

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

RMS = 163%

Port Westward

0 5 10 15 20 25

Duct Bottom (ft)

0

5

10

15

20

25

30

35

40

45

50

55

60

West W

all

(ft)

Test 09, Full Load, 8-8-2012Raw NOx Profile

Filename: Port Westward NOx09

Flow into the page

-1

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

RMS = 82%

As Found Tuned

Reagent

consumption

reduced 5%

NH3

28

MP303

AIG Tuning, Multi Zone AIG Design; NH3/NOx

As Found, RMS = 19% Tuned, RMS = 5%

29

MP303

Benefits of AIG Tuning

30

• Ability to meet NOx and NH3 slip requirements

• Reduce NH3 slip at required outlet NOx

• Reduced Reagent Consumption

• Reduced Required GT Water Injection

GT Load As Found Tuned Reagent Reduction

MW lb/hr lb/hr %

244 669 633 5

174 410 355 13

29 42 35 17

GT Water Inj Inlet NOx NH3 Slip

GPM ppm ppm

30 20 3

26 26 3.5

MP303

Bypass

31

MP303

NOx Profiles Can Also Help Detect Bypass

Base Year Two Years later

0 10 20 300

10

20

30

40

50

60

70

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

0 10 20 300

10

20

30

40

50

60

70

Possible

Bypass

32

MP303

NOx Profiles Can Also Help Detect Bypass

Possible

Bypass

0 10 200

10

20

30

40

50

60

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

33

MP303

Catalyst Management

34

MP303

Catalyst Management

• Tracking catalyst activity and NH3/NOx distribution

• Ensure continued environmental compliance

• Plan for catalyst replacements

0.0

0.2

0.4

0.6

0.8

1.0

0

5

10

15

0 50,000 100,000 150,000

K/K

o

NH

3 S

lip

, pp

m

Operating Hours

RMS=10% RMS=20% RMS=22.5% K/Ko

5%/10k Hrs

35

MP303

Catalyst Management

Catalyst management for a combined cycle SCR system entails

tracking key parameters so you know when the catalyst must be

changed.

These Parameters are:

1. Catalyst Activity (K, m/hr)

2. Reactor Potential (RP, dimensionless)

36

MP303

Catalyst Activity

• Catalyst Activity determines how well a catalyst is performing

regarding NOx reduction.

• Typical poisons in a combined cycle SCR include sodium and

phosphorous.

• Na: GT water injection, water for aqueous NH3 production,

ambient sources (ocean air).

• P: GT lube oil

37

MP303

Reactor Potential

• Although catalyst activity is important, the key parameter

for determining SCR performance is the reactor potential

RP.

• RP is essentially the activity multiplied by the total catalyst

surface area per unit of exhaust gas.

• RP is important because it reflects the effects of both

catalyst activity and area velocity.

RP = (K)(Asurface) = K

Q Av

38

MP303

Catalyst Activity

• Laboratory activity measurements historically has been a key

step in catalyst management

• Until recently there were no standard testing guidelines for GT

SCR or CO catalyst. This led to variations among laboratories.

• EPRI recently released a Guideline for testing Gas Turbine SCR

and CO catalyst

• Available at the EPRI Website (Report 3002006042)

39

MP303

EPRI GT SCR/CO Testing Guidelines

40

• Developed by an

industry consortium

• SCR Catalyst: Outlines

Standardized Test

Methods

• Activity, K

• DNOx @ NH3 slip

limit

• CO Catalyst

• Chemical and Physical

Analysis

MP303

Measure RP Insitu

• While sending samples to a lab for activity measurements

historically has been a key step in catalyst management, it is no

longer necessary.

• Today an owner operator can take control of catalyst

management with the CatalysTraK®, a system that measures

catalyst activity and RP in-situ.

• Insitu tests are performed at actual full scale operating

conditions

• Tests can be conducted at any time, no outage required

• Performed during an annual compliance test

• At any time there may be an issue with catalyst performance

• Applicable to both NOx and CO catalyst

41

MP303

Similar to the lab approach for SCR catalyst, NOx reduction is

measured across a small cross section (test section) of the

catalyst bed. A small supplemental ammonia injection grid

(AIG) is permanently mounted upstream of the test section.

CatalysTraK® System Components

42

MP303

CatalysTraK® System Components

Additionally, an inlet gas sampling probe is installed directly

upstream of the AIG, and an outlet gas sampling probe is

installed immediately downstream of the catalyst bed at the

test section. The supplemental AIG is used to increase the

NH3/NOx level and provide excess ammonia across the

catalyst test section.

The RP calculation then is

based on the maximum

NOx reduction measured

across this catalyst test

section.

43

MP303

CatalysTraK® Supplemental Injection Grid

Supplemental injection

grids located upstream

of both CO and NOx

Catalysts.

44

MP303

CatalysTraK® Access Ports on a Small Combined Cycle

CO Measurement Access Ports

45

MP303

CatalysTraK® History

CatalysTraK® was originally developed for coal-fired SCR’s.

These systems are characterized by multiple catalyst layers.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000 22000 24000

Operating Hours

Rea

cto

r P

ote

nti

al

All Layers

Layer 1

Layer 2

Layer 3

Minimum Total RP

46

MP303

CatalysTraK® Application to Turbines

One issue related to the application of CatalysTraK® to a GT

SCR is that these systems have a single layer of catalyst and it

contains all of the reactors RP.

Thus when the catalyst is relatively new, the measured NOx

reduction across a layer of GT catalyst can be greater than

99%. This can make it difficult to accurately determine the

reactor potential RP.

47

MP303

CatalysTraK® Application to Turbines

The bottom line: Early in a catalyst’s life, the CatalysTraK®

measurement may have a higher degree of uncertainty

associated with RP, but at that point in the catalyst’s lifecycle it is

not critical that the RP be precise. This is also an issue in

laboratory testing of new GT SCR catalyst!

0

1

2

3

4

5

6

7

0 1 2 3 4 5

Re

acto

r P

ote

nti

al

Outlet NOx, ppm @3% O2 dry

RPmin=2.3(RMS<10%)

48

MP303

CatalysTraK® Reactor Potential Results

CatalysTraK® tests run over two years show the RP is well

above the minimum level required.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Year 1 Year 2

Avera

ge R

eacto

r P

ote

ntial

49

MP303

CO Catalyst Testing

As with SCR catalyst, CO catalyst performance also degrades

over time. Historically core samples are drilled out or pulled

from test panels and tested in a lab. The test involves just

measuring the amount of CO oxidation that occurs across the

sample, while simulating full-scale temperature and space

velocity.

Why not just measure the oxidation across the actual CO

catalyst bed while it is operating?

50

MP303

CatalysTraK® CO Catalyst Test Results

The tests run over two years show CO oxidation rates of

between 96% and 98%.

0

10

20

30

40

50

60

70

80

90

100

Year 1 Year 2

Ave

rag

e %

CO

Oxid

atio

n

51

MP303

Summary

• Simple stack measurements (NH3 vs NOx) can distinguish Gas

Bypass from NH3/NOx maldistribution

• Facilitated by using a continuous TDL analyzer to make the NH3

measurements

• AIG tuning facilitated using a permanent probe grid at the catalyst

exit

• With a probe grid and multipoint sampling, AIG tuning

completed in one day

• AIG Design affects how well a unit can be tuned

• NOx profiles at the SCR outlet can also help diagnose areas of Gas

Bypass

52

MP303

Summary (Continued)

• Historically, lab tests have been used to monitor the

performance of both SCR and CO catalysts over time.

• EPRI recently released GT SCR/CO testing guidelines

(Report 3002006042)

• Recent tests showed both SCR and CO catalysts can easily

be characterized in-situ.

• The in-situ technique is simple.

• It can be done easily during the annual compliance test,

does not require an outage, and provides an opportunity to

obtain a more comprehensive data set.

53

MP303 54

www.ferco.com

lmuzio@ferco.com

rsmith@ferco.com

Questions?