NOx: Troubleshooting and Optimization of Combined Cycle SCR Systems L. J. Muzio Fossil Energy Research Corp. Laguna Hills, CA CEMTek Environmental 216 Emissions Monitoring Seminar and Training September 28, 216 Santa Ana, CA
Optimizing Gas Turbine SCR Performance Topics Troubleshooting - How to Distinguish NH 3 Maldistribution from Bypass AIG Tuning - Catalyst Inlet NH 3 /NO x Distribution Identifying Flue Gas Bypass Catalyst Management/Measuring Catalyst Activity 2
Simple Cycle Gas Turbine SCR Ammonia Injection Grid (AIG) SCR Catalyst Perforated Plate Diffuser Vanes CO Catalyst SCR Performance Parameters: - NO x Reduction - Ammonia Slip Uniform NH 3 /NO x Profile at Catalyst Inlet is Critical! Tempering Air Flue gas 75- F NH 3 NH 3 Dilution Air 3
Combined Cycle Gas Turbine SCR No Diffuser Vanes No Perforated Plates No Tempering Air Ammonia Injection Grid (AIG) CO Catalyst SCR Catalyst SCR Performance Parameters: - NO x Reduction - Ammonia Slip Uniform NH 3 /NO x Profile at Catalyst Inlet is Critical! Steam Tube Banks Flue gas ~55-65 F NH 3 NH 3 Dilution Air 4
Direct Injection/Dual Function Catalyst Direct Injection of Ammonium Hydroxide 5
Troubleshooting Measurement Limit 8 NH 3 slip is too high Why? NH3 Slip, ppm 6 4 2 2 4 6 8 NOx, ppm 6
Why? Catalyst Activity (K)? Poor NH3/NOx Distribution? How active the material is in reducing NOx f(material, geometry) 8 Measurement Limit Want NH 3 /NO x uniform across the catalyst Local NH 3 /NO x >1=NH 3 slip NH3 Slip, ppm 6 4 2 2 4 6 8 NOx, ppm Reactor Potential? Ability of the catalyst bed to reduce NO x RP= K*A sp *V cat /Q fg Minimum Reactor Potential 3. 2.5 2. 1.5 1..5 NH3 slip=2.5ppm NH3 slip=5 ppm NOx out=5 ppm Flue Gas Bypass? Any bypass by the catalyst increases stack NO x & NH 3. 4 25 Inlet NOx, ppm 7
A simple stack test can distinguish (NH 3 Maldistribution/Flue Gas Bypass) NH 3 /NO x RMS Effects Bypass Effects 8 6 8 6 4 2 5 15 4 2 5 15 RMS=% RMS=2% RMS=3% ByPass=% ByPass=2.5% ByPass=5% ByPass=7.5% 4 4 NH3 Slip, ppm@15%o2 dry 35 3 25 2 15 5 NH3 Slip, ppm@15%o2 dry 35 3 25 2 15 5 2 4 6 8 12 14 NOx, ppm@15%o2 dry 2 4 6 8 12 14 NOx, ppm@15%o2 dry 8
How to best generate this data? Wet Chemical NH 3 measurements? Continuous NH 3 measurements? 9
TDL Instrumentation Testing facilitated using a continuous TDL NH 3 analyzer Data set can be generated in less than a day Data available in real time Unisearch NH 3 TDL Dual Path Two Channel Fiber Optic Coupled
NH 3 -TDL Lines of Site NH3 TDL Optical Paths Gas Flow 11
TDL NH 3 Measurements on a Large Combined Cycle NH 3 /NO x RMS Effects Bypass Effects NH3 Slip, ppm@15%o2 dry 4 35 3 25 2 15 5 RMS=% RMS=2% RMS=3% Test Data 5 15 NOx, ppm@15%o2 dry NH3 Slip, ppm@15%o2 dry 4 35 3 25 2 15 5 Test Data ByPass=% ByPass=2.5% ByPass=5% ByPass=7.5% RMS=% 5 15 NOx, ppm@15%o2 dry 12
AIG Tuning What is it? Making sure that NO x and NH 3 are matched up at every location on the catalyst How is it Done? By making NO x measurements at the exit of the catalyst It is not necessary to measure both NO x and NH 3 13
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 6 probes depending on AIG design With Permanent Probes Tuning can Typically be done in One Day The NO x Profiles at the Exit of the Catalyst can also Help Identify Bypass 14
NH 3 /NO x Distribution and AIG Tuning RMS=5% RMS=% RMS=15% RMS=25% 8 New Catalyst NH3 Slip, ppm 6 4 2 7 8 9 8 Catalyst Near End-of-Life NH3 Slip, ppm 6 4 2 7 8 9 NOx Reduction, % 15
How Well is Your AIG Tuned? (As Found RMS Values) Most of the GT AIGs we encounter are not tuned very well! 4 35 3 25 RMS (%) 2 15 5 16
How Important is the NH 3 /NO x Distribution? SCAQMD is pushing NO x from 5 to 2 ppm in So. Cal. Assumption is that just adding more catalyst will be the solution RMS=2% Add Catalyst Tune AIG To RMS=% K=8/RMS=2% RMS=2%, 5% More Cat K=8/RMS=% K=8/RMS=2% NH3 slip, ppm @15%O2 dry 12 8 6 4 2 1 2 3 4 5 6 NOx, ppm@15% O2 dry NH3 slip, ppm @15%O2 dry 12 8 6 4 2 1 2 3 4 5 6 NOx, ppm@15% O2 dry Just tuning the AIG allows 2 ppm NO x to be achieved Adding 5% more catalyst helps, but not as much as tuning 17
Outside View of a Permanent Sample Grid on a Large Combined Cycle Sample probe exit ports Sample probe lines brought down to grade 18
Sample Probes Attached to Catalyst Modules 19
FERCo s Multipoint Instrumentation Samples 48 points in 12-15 minutes (4 groups of 12) NO x and O 2 2
AIG Design Affects Tuning 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 21
AIG With No Adjustability 22
AIG: No Adjustability Permanent Probe Grid for Tuning. Difficult to Tune Without! 23
Normalized NH 3 /NO x Profiles As Found Orig. AIG RMS = 35% 5 45 4 35 1.7 1.6 1.5 NH 3 Header NH 3 Header North Wall (ft) 3 25 2 1.4 1.3 1.2 1.1 1.9.8.7.6.5 15.4 5 24 5 Bottom of the Duct
Normalized NH 3 /NO x Profiles Before & After Orig. AIG RMS = 35% All Holes Resized RMS = 16% 5 5 45 45 4 4 35 1.7 1.6 35 1.5 NH 3 Header North Wall (ft) 3 25 1.4 1.3 1.2 1.1 1.9 NH 3 Header North Wall (ft) 3 25 1.4.9.8 2.7.6 2.5 15.4 15.4 5 5 5 Bottom of the Duct 25 5 Bottom of the Duct
Duct Burners Impact AIG Tuning Duct Burners Off (Inlet NO x ppm) Duct Burners On (Inlet NO x ppm) 4 4 35 35 3 3 25 25 2 AIG Difficult to Tune 2 15 NH3 15 5 5 5 26 5
AIG Tuning, 1-D AIG Design; NH 3 /NO x As Found, RMS = 22% Tuned, RMS = 13% y Catalyst Inlet 18 18 16 16 North Wall (ft) 14 12 8 6 4 1.55 1.5 1.45 1.4 1.35 1.3 1.25 1.2 1.15 1.1 1.5 1.95.9.85.8.75.7 North Wall (ft) 14 12 8 6 4 1.55 1.5 1.45 1.4 1.35 1.3 1.25 1.2 1.15 1.1 1.5 1.95.9.85.8.75.7 2 2 4 6 8 Adjustments across the width not possible 2 2 4 6 8 27
AIG Tuning, 1-D AIG Design; Outlet NO x As Found Tuned 6 6 55 55 West Wall (ft) 5 45 4 35 3 25 2 15 15 14 13 12 11 9 8 7 6 5 4 3 2 1-1 Reagent consumption reduced 5% NH 3 West Wall (ft) 5 45 4 35 3 25 2 15 15 14 13 12 11 9 8 7 6 5 4 3 2 1-1 5 5 5 15 2 25 5 15 2 25 28
AIG Tuning, 2-D AIG Design; Outlet NO x AIG Design:2-Zones Horizontally 29
AIG Tuning, Multi Zone AIG Design; NH 3 /NO x As Found, RMS = 19% Tuned, RMS = 5% 3
Direct Injection of Aqueous Ammonia@ Turbine exhaust As Found, RMS = 14% Tuned, RMS = 3% 31
Benefits of AIG Tuning Reduce NH 3 slip at required outlet NO x Reduced Reagent Consumption GT Load As Found Tuned Reagent Reduction MW lb/hr lb/hr % 244 669 633 5 174 4 355 13 29 42 35 17 Reduced Required GT Water Injection GT Water Inj Inlet NO x NH 3 Slip GPM ppm ppm 3 2 3 26 26 3.5 32
Coal SCR: AIG Design Influences Tuning Cross Grids Multi-Zones Flow Flow Into Page Mixer with 1-D Adj. Mixer with Multi Zone Grid Delta Wings mixer mixer mixer mixer Flow Flow Flow
Coal:AIG Design Effects 8 RMS NH3/NOx, % 6 4 2 Delta Wing Static Mixer A Static Mixer B Multi Zone Cross Grids AIG Design
Bypass 35
NO x Profiles Can Also Help Detect Bypass 7 Base Year Possible Bypass 7 Two Years later 6 6 15 5 14 13 5 12 11 4 9 4 8 7 3 6 5 3 4 3 2 2 1 2 2 3 2 3 36
NO x Profiles Can Also Help Detect Bypass Possible Bypass 6 5 4 3 2 15 14 13 12 11 9 8 7 6 5 4 3 2 1 2 37
Catalyst Management 38
Catalyst Management Tracking catalyst activity and NH 3 /NO x distribution Ensure continued environmental compliance Plan for catalyst replacements 39
Measuring Catalyst Activity There are Laboratory Protocols for testing SCR catalyst Coal Natural Gas (Gas Turbine Systems) 4
Measuring Catalyst Activity: Coal VGB Guidelines EPRI Protocol 41
Measuring Catalyst Activity: GT SCR/CO 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 32642) 42
Catalyst Management Tracking catalyst activity and NH 3 /NO x distribution Insure continued environmental compliance Plan for catalyst replacements NH3 slip NH3 slip Limit End of Life Amonia Slip RMS=25% K/K Activity History 1. 9.9 8.8 NH3 Slip, ppm 7 6 5 4 RMS=25% 123,864 RMS=% 134,54.7.6.5.4 K/Ko 3.3 2.2 1.. 2, 4, 6, 8,, 12, 14, 16, Operating Hours 43
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 NO x and CO catalyst 44
In Situ Catalyst Activity Measurement* Traditional Lab Measuremett Typically one per year K Lab = -A Vdesign ln(1- NO x ) Lab @NH3/NOx=1.2 FERCo s CatalysTrak * in situ measurement No outage required K In-situ = -A Vactual ln(1- NO x ) full scale @NH3/NOx>1 locally * Patented Process 45
In Situ CatalysTrak TM Measurements: Individual Layers CatalysTraK was originally developed for coal-fired SCR s. These systems are characterized by multiple catalyst layers. Relative Reactor Potential (RP/RPo) 1..9.8.7.6.5.4.3.2. Layer 1 Layer 2 Layer 3 25 26 27 28 First 4-years of operation beginning in 25 7 MW unit E. bituminous coal SCR on-line May 22 Seasonal operation Two reactors 3 + 1 configuration Initial load: 3 layers honeycomb catalyst Layer 1 replaced with plate catalyst prior to 26 ozone season. 5 15 2 25 Operating Hours 46
Volume of Data: Laboratory vs. In Situ Annual Laboratory Analysis On-Demand CatalysTrak TM Measurements Laboratory Relative Activity (K/Ko) 1..9.8.7.6.5.4.3.2 Layer 2 Layer 3 Relative Reactor Potential (RP/RPo) 1..9.8.7.6.5.4.3.2 Layer 2 Layer 3... 5 15 2 25. 5 15 2 25 Operating Hours Operating Hours 47
CatalysTraK Supplemental Injection Grid Supplemental injection grids located upstream of both CO and NO x Catalysts. 48
CatalysTraK Reactor Potential Results CatalysTraK tests run over two years show the RP is well above the minimum level required. 5. 4.5 Average Reactor Potential 4. 3.5 3. 2.5 2. 1.5 1..5. Year 1 Year 2 49
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? 5
CatalysTraK CO Catalyst Test Results The tests run over two years show CO oxidation rates of between 96% and 98%. 9 Average % CO Oxidation 8 7 6 5 4 3 2 Year 1 Year 2 51
Summary Simple stack measurements (NH 3 vs NO x ) can distinguish Gas Bypass from NH 3 /NO x maldistribution Facilitated by using a continuous TDL analyzer to make the NH 3 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 NO x profiles at the SCR outlet can also help diagnose areas of Gas Bypass 52
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 32642) 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
Questions? www.ferco.com lmuzio@ferco.com 54