scr performance issues: coal---- natural gas...plate scr catalyst extruded ceramic honeycomb scr...
TRANSCRIPT
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MP309b
SCR Performance Issues: Coal----Natural Gas
L. J. MuzioFossil Energy Research Corp.
Laguna Hills, CA
CEMTek Environmental 2018 Emissions Monitoring Seminar and Training
September 12, 2018Santa Ana, CA
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2 MP309b
Key Points
• Gas Turbine SCR Units• How important is AIG tuning?• Tune at modest levels of NOx reduction, or use an
FTIR?• Need a permanent probe grid at the SCR outlet• AIG design affects tuning
• Coal SCR Units• AIG Design Affects Tuning• Impacts at Low Load operation (becoming a major
issue)
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3 MP309b
AIG Tuning: Why is it important?
Coal-fired SCR (NOxin=300 ppm) Gas Turbine SCR (NOxin=25 ppm)
0
2
4
6
8
10
80 85 90 95 100
dNOx, %
NH
3-sl
ip, p
pm
2%
5%
7%
10%
11%
RMS
0
5
10
15
80 85 90 95 100dNOx, %
NH
3-sl
ip, p
pm
3%
6%
9%
11%
14%
RMS
• Performance improvement (can be as important as the catalyst quantity)
• Becoming more important as emission limits decrease
• Catalyst Guarantees are usually based on a given NH3/NOx uniformity (RMS); need to quantify the RMS
Chart1
808079.987181136379.97703516179.880863074680
8584.919531581184.819617930584.696463823384.4950176412100
89.754482804789.582042743489.260276921688.956134226288.4298596095
91.918085428391.664573897291.296181421590.706478145590.1030111008
9493.545906556792.948406181692.276648055291.6421504587
95.641593644795.157378358194.316270669593.620463652492.9837975242
98.597.991072945197.422502149696.657175320696.1478381993
RMS
0.022969332
0.051643434
0.074507144
0.097120444
0.114782368
y
dNOx, %
NH3-slip, ppm
0
0
0.0281886813
0.050499681
0.2619820989
2
0
0.1769500531
0.3966601708
0.6674760525
1.1104562071
2
0.5398923124
0.9190880074
1.6266510495
2.2954608365
3.4527387186
1.2796301432
1.837102
2.647197054
3.9439545581
5.2709785894
2.199
3.1975514818
4.5114548066
5.9886509266
7.3839111413
4.0866355754
5.1514249906
7.0010207979
8.5311004285
9.9311292443
14.2935
15.4126305937
16.662917773
18.34587147
19.4659037998
Sheet1
Sheet1
808079.987181136379.97703516179.880863074680
8584.919531581184.819617930584.696463823384.4950176412100
89.754482804789.582042743489.260276921688.956134226288.4298596095
91.918085428391.664573897291.296181421590.706478145590.1030111008
9493.545906556792.948406181692.276648055291.6421504587
95.641593644795.157378358194.316270669593.620463652492.9837975242
98.597.991072945197.422502149696.657175320696.1478381993
RMS
0.022969332
0.051643434
0.074507144
0.097120444
0.114782368
y
dNOx, %
NH3-slip, ppm
0
0
0.0281886813
0.050499681
0.2619820989
2
0
0.1769500531
0.3966601708
0.6674760525
1.1104562071
2
0.5398923124
0.9190880074
1.6266510495
2.2954608365
3.4527387186
1.2796301432
1.837102
2.647197054
3.9439545581
5.2709785894
2.199
3.1975514818
4.5114548066
5.9886509266
7.3839111413
4.0866355754
5.1514249906
7.0010207979
8.5311004285
9.9311292443
14.2935
15.4126305937
16.662917773
18.34587147
19.4659037998
Sheet2
79.86157325179.865950404479.804901761579.768551353779.6097407819808080
84.786416782284.725227726984.531838454684.373519116284.0054851947100100100
89.448126934789.283490379488.765535556788.39642616187.7524824865
91.638421363991.324881376290.614456917590.063747737589.3698579526
93.484486584193.105624639692.208828829591.548535651390.7903927544
95.254810747294.536438106693.645688798892.905826020592.0410062446
97.991821914697.474998298296.727891650496.011786257295.0002651039
RMS
0.033152776
0.061170791
0.087961844
0.10933116
0.137728686
y
y
y
dNOx, %
NH3-slip, ppm
0.1730334363
0.1675619945
0.2438727981
0.2893108079
0.4878240227
10
5
5
0.2669790222
0.3434653414
0.5852019317
0.7831011047
1.2431435066
10
5
5
0.6898413317
0.8956370257
1.5430805541
2.0044672988
2.8093968918
1.0769732951
1.4688982797
2.3569288531
3.0453153281
3.9126775592
1.8943917699
2.3679692004
3.4889639631
4.3143304359
5.262009057
2.806486566
3.7044523667
4.8178890015
5.7427174744
6.8237421943
8.7602226067
9.4062521272
10.340135437
11.2352671786
12.4996686201
Sheet3
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4 MP309b
AIG Tuning: How is it Done𝑵𝑵𝑵𝑵𝟑𝟑𝒊𝒊𝒊𝒊𝒊𝒊 = 𝑵𝑵𝑵𝑵𝒙𝒙𝒊𝒊𝒊𝒊𝒊𝒊 − 𝑵𝑵𝑵𝑵𝒙𝒙𝒐𝒐𝒐𝒐𝒐𝒐𝒊𝒊 + 𝑵𝑵𝑵𝑵𝟑𝟑𝒔𝒔𝒔𝒔𝒊𝒊𝒔𝒔𝒊𝒊
• Tune at reduced NH3 injection rate
• Local NH3 slip=0• Just need to measure NOx at the
exit
• For the NOx- in turn off NH3• For GT NOx-in is basically
uniform• Are there issues with this
approach?• Yes
𝑵𝑵𝑵𝑵𝟑𝟑𝑵𝑵𝑵𝑵𝒙𝒙 𝒊𝒊
=𝑵𝑵𝑵𝑵𝒙𝒙𝒊𝒊𝒊𝒊𝒊𝒊 − 𝑵𝑵𝑵𝑵𝒙𝒙𝒐𝒐𝒐𝒐𝒐𝒐𝒊𝒊
𝑵𝑵𝑵𝑵𝒙𝒙𝒊𝒊𝒊𝒊𝒊𝒊
• Use FTIR• Measure NOx-in, NOx-out,
NH3-in, NH3 –out• Are there issues with this
approach?• YES
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5 MP309b
Tuning at Reduced NH3 Injection Rate• For a valid RMS local NH3 slip needs to be near zero• If NH3 slip is present it is not accounted for• RMS will be artificially low
0
2
4
6
8
10
0
2
4
6
8
10
12
14
16
18
20
22
24
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
NH
3 Sl
ip, p
pm
Appa
rent
RM
S,%
NOx, ppm
RMS=5% RMS=10% RMS=15% RMS=25%
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6 MP309b
FTIR Measurements: Site 1
0
5
10
15
20
25
30
35
40
45
0 1 2 3 4 5 6 7
Amm
onia
Slip
, ppm
vdc
Outlet NOX, ppmvdc
NH3 slip 10% RMS NH3 slip 20% RMS NH3 slip 30% RMS
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7 MP309b
FTIR Measurements: Site 2
05
1015202530354045
0 10 20 30 40 50
NH3
-in:F
TIR
Calc
NO
x-in
-NO
x-ou
t+N
H3
slip
NH3 in: FTIR Measurement, ppm
B C D E F Y
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8 MP309b
Permanent Sample Probes Should Be Installed
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9 MP309b
Outside View of a Permanent Sample Grid on a Large Combined Cycle
Sample probe exit ports
Sample probe lines brought down to grade
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10 MP309b
FERCo’s Multipoint Instrumentation
• Samples 48 points in 12-15minutes (4 groups of 12)
• NOx and O2
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11 MP309b
GT:AIG Design Affects Tuning
• No Adjustments: Some systems have no adjustmentvalves- Bad Idea ! ! ! Best RMS~ 17%
• 1-D: Commonly used design
• Multi Zone: Better Direct Injection:
Two Horizontal Horizontal and Three Horizontal
Zones Vertical ZonesReagent
Struggle to get RMS~10%
RMS ~5%
RMS ~3%
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12 MP309b
Coal:AIG Design Affects Tuning
0
2
4
6
8
10
Delta Wing Static Mixer A Static Mixer B Multi Zone Cross Grids
AIG Design
RMS
NH3/
NOx,
%
Flow Into Page
Flow
mixer mixer
Flow
mixer mixer
Flow
Flow
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Flow
Flow Into Page
mixermixer
Flow
Flow Into Page
mixermixer
Flow
Sheet2
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Sheet1
Flow
Flow Into Page
mixermixer
Flow
Flow Into Page
mixermixer
Flow
Sheet2
Sheet3
Sheet1
Flow
Flow Into Page
mixermixer
Flow
Flow Into Page
mixermixer
Flow
Sheet2
Sheet3
Sheet1
Flow
Flow Into Page
mixermixer
Flow
Flow Into Page
mixermixer
Flow
Sheet2
Sheet3
Sheet1
Flow
Flow Into Page
mixermixer
Flow
Flow Into Page
mixermixer
FlowFlow
Sheet2
Sheet3
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13 MP309b
Changes in Coal Boiler Operations
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14 MP309b
Changes in Coal Boiler Operations
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15 MP309b
More Cycling-More Time at Low load
0 5 10 15 20 25 30 35Wall Closest to Boiler (ft) Flow Toward Page
0
5
10
15
20
25
30
35
40
Nor
th W
all (
ft)
0.80.820.840.860.880.90.920.940.960.9811.021.041.061.081.11.121.141.161.181.2
Full Load (RMS=3.2%)
0 5 10 15 20 25 30 35Wall Closest to Boiler (ft) Flow Toward Page
0
5
10
15
20
25
30
35
40
Nor
th W
all (
ft)
0.10.20.30.40.50.60.70.80.911.11.21.31.41.51.61.71.81.9
Low Load (RMS=51.2%)
• Historically Tuning was done at Full Load• Now Tuning should at least be checked at Low loads
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16 MP309b
Low Load : ABS Formation/Catalyst Deactivation (Two ABS Formation Mechanisms)
Bulk Dewpoint (like fog forming)
NH3+SO3+H2O NH4HSO4
NH3+H2SO4 NH4HSO4XNH3 (ppm) * XSO3 (ppm) = 2.97 * 1025 * exp (-54,950/RT)
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17 MP309b
Operation Below Bulk Dew Point
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0 20 40 60 80 100 120 140Hours
K/K 0
1st Layer 2nd Layer
525°F
600°F650°F
700°F
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18 MP309b
Low Load : ABS Formation/Catalyst Deactivation
Progressing Formation of ABS in Catalyst Pores
Flue Gas Flow
ABS
Catalyst Surface
ln (P/Peq) = 2.33 * 10-4 / γ T (cm-1 K-1)
Thomson’s Eq.
ABS Surface Tension
Capillary Condensation
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19 MP309b
Operation With Capillary Condensation
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0 5 10 15 20 25 30 35 40 45 50 55 60
Rela
tive
Cata
lyst
Act
ivity
(K/K
0)
Time (Hours)
Plate SCR Catalyst Extruded Ceramic Honeycomb SCR Catalyst
• Depending on T,NH3,SO3 will only fill up certain pores sizes with ABS
• Deactivation will level off
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20 MP309b
ABS Deactivation is Recoverable
0.00
0.20
0.40
0.60
0.80
1.00
1.20
0 20 40 60 80 100 120 140Hours
K/K 0
1st Layer 2nd Layer
525°F
600°F650°F
700°F
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21 MP309b
Summary
• AIG Tuning (Nat. Gas)• How well is your AIG tuned?• Do you need an accurate RMS value (catalyst
guarantees)?• AIG Tuning Approach
• NOx Measurements at the SCR exit• Permanent probe grid• Variance to allow SCR operation at lower dNOx• Yields accurate RMS
• FTIR• permanent probe grid • Make sure data follows SCR fundamentals
• Coal Units (Load Cycling)• Check AIG tuning at low loads• Change low load combustion for better NOx
distribution• Modify AIG to accommodate both full and low load• Assess ABS catalyst issues-Tools Exist!
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22 MP309b
Questions?
mailto:[email protected]
SCR Performance Issues: Coal----Natural GasKey PointsAIG Tuning: Why is it important?AIG Tuning: How is it DoneTuning at Reduced NH3 Injection RateFTIR Measurements: Site 1FTIR Measurements: Site 2Permanent Sample Probes Should Be InstalledOutside View of a Permanent Sample Grid on a Large Combined CycleFERCo’s Multipoint InstrumentationGT:AIG Design Affects TuningCoal:AIG Design Affects TuningChanges in Coal Boiler OperationsChanges in Coal Boiler OperationsMore Cycling-More Time at Low loadLow Load : ABS Formation/Catalyst Deactivation (Two ABS Formation Mechanisms)Operation Below Bulk Dew PointLow Load : ABS Formation/Catalyst DeactivationOperation With Capillary CondensationABS Deactivation is RecoverableSummarywww.ferco.com�[email protected]�