nox: troubleshooting and optimization of combined cycle scr … · mp306 nox: troubleshooting and...

MP306

NOx: Troubleshooting and Optimization of Combined Cycle SCR

SystemsL. J. Muzio

Fossil Energy Research Corp.Laguna Hills, CA

CEMTek Environmental 2016 Emissions Monitoring Seminar and Training

September 28, 2016Santa Ana, CA

MP3062

Optimizing Gas Turbine SCR Performance

• Troubleshooting - How to Distinguish NH3 Maldistributionfrom Bypass

• AIG Tuning - Catalyst Inlet NH3/NOx Distribution

• Identifying Flue Gas Bypass

• Catalyst Management/Measuring Catalyst Activity

Topics

MP3063

Simple Cycle Gas Turbine SCR

Ammonia Injection Grid (AIG)SCR Catalyst

Diffuser Vanes

Flue gas750-1000°F

• SCR Performance Parameters:- NOx Reduction- Ammonia Slip

• Uniform NH3/NOx Profileat Catalyst Inlet is Critical!

CO Catalyst

Tempering Air

NH3 Dilution Air

NH3

Perforated Plate

MP3064

Combined Cycle 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 Profileat Catalyst Inlet is Critical!

CO Catalyst

NH3 Dilution Air

NH3Steam Tube Banks

MP306

Direct Injection/Dual Function Catalyst

5

Direct Injection of Ammonium Hydroxide

MP306

0

2

4

6

8

10

0 2 4 6 8 10

NH3 Slip, ppm

NOx, ppm

Measurement Limit

Troubleshooting

6

NH3 slip is too high…Why?

MP306

Why?

7

Catalyst Activity (K)?

Reactor Potential?

Flue GasBypass?

Poor NH3/NOxDistribution?

How active the material is in reducing NOxf(material, geometry)

•Ability of the catalyst bed to reduce NOx•RP= K*Asp*Vcat/Qfg

0.0

0.5

1.0

1.5

2.0

2.5

3.0

40 25 10

Minim

um Reactor Poten

tial

Inlet NOx, ppm

NH3 slip=2.5ppm NH3 slip=5 ppm

NOx‐out=5 ppm

Want NH3/NOx uniform across the catalystLocal NH3/NOx>1=NH3 slip

Any bypass by the catalyst increases stack NOx & NH3

0

2

4

6

8

10

0 2 4 6 8 10

NH3 Slip, ppm

NOx, ppm

Measurement Limit

MP306

A simple stack test can distinguish(NH3 Maldistribution/Flue Gas Bypass)

NH3/NOx RMS Effects Bypass Effects

0

5

10

15

20

25

30

35

40

0 2 4 6 8 10 12 14

NH3 Slip, ppm

@15

%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

NH3 Slip, ppm

@15

%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

8

MP306

How to best generate this data?

• Wet Chemical NH3 measurements?

• Continuous NH3 measurements?

9

MP306

TDL Instrumentation

• Testing facilitated using a continuous TDL NH3analyzer

• 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

10

MP306

NH3-TDL Lines of Site

Gas Flow

NH3 TDLOptical Paths

11

MP306

TDL NH3 Measurements on a Large Combined Cycle

NH3/NOx RMS Effects Bypass Effects

12

0

5

10

15

20

25

30

35

40

0 5 10 15

NH3 Slip, p

pm@15

%O2 dry

NOx, ppm@15%O2 dry

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

0510152025303540

0 5 10 15

NH3 Slip, p

pm@15

%O2 dry

NOx, ppm@15%O2 dry

Test Data ByPass=0% ByPass=2.5%

ByPass=5% ByPass=7.5% RMS=10%

MP306

AIG Tuning

13

•What is it?•Making sure that NOx and NH3 are matched up at every location on the catalyst

•How is it Done?•By making NOx measurements at the exit of the catalyst•It is not necessary to measure both NOx and NH3

MP306

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

14

MP306

NH3/NOx Distribution and AIG Tuning

0

2

4

6

8

10

70 80 90 100NOx Reduction, %

NH3 Slip, ppm

New Catalyst

Catalyst NearEnd-of-Life

0

2

4

6

8

10

70 80 90 100

NH3 Slip, ppm

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

15

MP306

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

16

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

0

5

10

15

20

25

30

35

40

RMS (%

)

MP306

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%

17

0

2

4

6

8

10

12

0 1 2 3 4 5 6NH3 slip, ppm

@15

%O2 dry

NOx, ppm@15% O2 dry

K=80/RMS=20% RMS=20%, 50% More Cat

0

2

4

6

8

10

12

0 1 2 3 4 5 6NH3 slip, ppm

@15

%O2 dry

NOx, ppm@15% O2 dry

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

MP306

Outside View of a Permanent Sample Grid on a Large Combined Cycle

Sample probe exit ports

Sample probe lines brought down to grade

18

MP306

Sample Probes Attached to Catalyst Modules

19

MP306

FERCo’s Multipoint Instrumentation

• Samples 48 points in 12-15minutes (4 groups of 12)

• NOx and O2

20

MP306

AIG Design Affects Tuning

21

• 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

MP306

AIG With No Adjustability

22

MP306

AIG: No Adjustability

23

Permanent Probe Grid for Tuning. Difficult to Tune Without !

MP30624

Normalized NH3/NOx Profiles – As Found

Orig. AIG RMS = 35%

NH3 Header

0 5Bottom of the Duct

0

5

10

15

20

25

30

35

40

45

50

Nor

th W

all (

ft)

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

MP30625

Normalized NH3/NOx Profiles – Before & After

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


0

5

10

15

20

25

30

35

40

45

50

Nor

th W

all (

ft)

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

10

15

20

25

30

35

40

45

50

Nor

th W

all (

ft)

0.4

0.9

1.4

NH3 Header NH3 Header

MP306

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

MP306

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

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

0 2 4 6 80

2

4

6

8

10

12

14

16

18

Nor

th W

all (

ft)

0.70.750.80.850.90.9511.051.11.151.21.251.31.351.41.451.51.55

Catalyst Inlet

0 2 4 6 80

2

4

6

8

10

12

14

16

18

Nor

th W

all (

ft)

0.70.750.80.850.90.9511.051.11.151.21.251.31.351.41.451.51.55

y

Adjustments across the widthnot possible

27

MP306

AIG Tuning, 1-D AIG Design; Outlet NOx

0 5 10 15 20 250

5

10

15

20

25

30

35

40

45

50

55

60

Wes

t Wal

l (ft)

-10123456789101112131415

0 5 10 15 20 250

5

10

15

20

25

30

35

40

45

50

55

60

Wes

t Wal

l (ft)

-10123456789101112131415

As Found Tuned

Reagent consumption reduced 5%

NH3

28

MP306

AIG Tuning, 2-D AIG Design; Outlet NOx

29

AIG Design:2-Zones Horizontally

MP306

AIG Tuning, Multi Zone AIG Design; NH3/NOx


30

MP306

Direct Injection of Aqueous Ammonia@ Turbine exhaust


31

MP306

Benefits of AIG Tuning

32

• Reduce NH3 slip at required outlet NOx

• Reduced Reagent Consumption

• Reduced Required GT Water Injection

GT Load As Found Tuned Reagent ReductionMW lb/hr lb/hr %244 669 633 5174 410 355 1329 42 35 17

GT Water Inj Inlet NOx NH3 SlipGPM ppm ppm30 20 326 26 3.5

MP306

Coal SCR: AIG Design Influences Tuning

Flow Into Page

Flow

mixer mixer

Flow

mixer mixer

Flow Flow

Cross Grids Multi-Zones

Mixer with 1-D Adj. Mixer with Multi Zone Grid Delta Wings

MP306

Coal:AIG Design Effects

0

2

4

6

8

10

Delta Wing Static Mixer A Static Mixer B Multi Zone Cross Grids

AIG Design

RMS

NH3/

NOx,

%

MP306

Bypass

35

MP306

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

36

MP306

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

37

MP306

Catalyst Management

38

MP306

Catalyst Management

• Tracking catalyst activity and NH3/NOx distribution

• Ensure continued environmental compliance

• Plan for catalyst replacements

39

MP306

Measuring Catalyst Activity

• There are Laboratory Protocols for testing SCR catalyst

• Coal

• Natural Gas (Gas Turbine Systems)

40

MP306

Measuring Catalyst Activity: Coal

41

VGB Guidelines EPRI Protocol

MP306

Measuring Catalyst Activity: GT SCR/CO

42

• Until recently there were no standard testing guidelines for GT SCR or CO catalyst. This led to variations among laboratories.

• Last year EPRI issued a guideline for testing GT SCR & CO Catalyst

• Available at the EPRI Website (Report 3002006042)

MP306

Catalyst Management

• Tracking catalyst activity and NH3/NOx distribution• Insure continued environmental compliance• Plan for catalyst replacements

43

134,540

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0

1

2

3

4

5

6

7

8

9

10

0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000

K/Ko

NH3 Slip, ppm

Operating Hours

NH3‐slip NH3 slip Limit End of LifeAmonia Slip RMS=25% K/K0Activity History

RMS=25%123,864

RMS=10%

MP306

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

44

MP30645

In Situ Catalyst Activity Measurement*

Traditional Lab Measuremett• Typically one per year

KLab = -AVdesign ln(1-∆NOx)Lab

@NH3/NOx=1.2

FERCo’s CatalysTrak®*

• in situ measurement• No outage required

KIn-situ = -AVactual ln(1-∆NOx)full scale@NH3/NOx>1 locally

* Patented Process

MP30646

In Situ CatalysTrakTM Measurements: Individual Layers

First 4-years of operation beginning in 2005

700 MW unit

E. bituminous coal

SCR on-line May 2002

Seasonal operation

Two reactors

3 + 1 configuration

Initial load: 3 layers honeycomb catalyst

Layer 1 replaced with plate catalyst prior to 2006 ozone season

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 5000 10000 15000 20000 25000

Operating Hours

Rel

ativ

e R

eact

or P

oten

tial (

RP/

RPo

)

Layer 1Layer 2Layer 3 2005 2006 2007 2008

CatalysTraK® was originally developed for coal-fired SCR’s. These systems are characterized by multiple catalyst layers.

MP30647

Volume of Data: Laboratory vs. In Situ

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 5000 10000 15000 20000 25000

Operating Hours

Labo

rato

ry R

elat

ive

Act

ivity

(K/K

o)

Layer 2Layer 3

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 5000 10000 15000 20000 25000

Operating Hours

Rel

ativ

e R

eact

or P

oten

tial (

RP/

RPo

)

Layer 2Layer 3

Annual Laboratory Analysis On-Demand CatalysTrakTM Measurements

MP306

CatalysTraK® Supplemental Injection Grid

Supplemental injection grids located upstream of both CO and NOxCatalysts.

48

MP306

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

Ave

rage

Rea

ctor

Pot

entia

l

49

MP306

CO Catalyst Testing

As with SCR catalyst, CO catalyst performance also degrades over time.

Laboratory CO tests 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

MP306

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

rage

% C

O O

xida

tion

51

MP306

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 NH3measurements

• 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

MP306

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

MP30654

[email protected]

Questions?

nox: troubleshooting and optimization of combined cycle scr … · mp306 nox: troubleshooting and...

Documents