Gas Turbine SCR Performance Optimization and Management

Transcription

1 Gas Turbine SCR Performance Optimization and Management T. D. Martz, L. J. Muzio Fossil Energy Research Corp. Laguna Hills, CA McIlvaine Hot Topic Hour February 1, 13 1

2 Gas Turbine SCR Systems Simple Cycle GT SCR 75-5 F

3 Gas Turbine SCR Systems Combined Cycle GT SCR 3

4 Today s Gas Turbine SCR Topics Troubleshooting - FERCo is a trusted 3 rd party engineering services company - Extensive background with SCR (design, modeling, full scale testing) - Developed a process model for SCR design and troubleshooting Catalyst Inlet NH 3 /NO x Distribution and AIG Tuning - Why NH 3 /NO x distribution is important - How AIG tuning can extend catalyst life - FERCo s approach to AIG tuning SCR Catalyst Management - What is it? - How is it done? - Why is it done?

5 Troubleshooting 1 1 Compliance Test 1 NH3-slip, ppm Compliance Window NH 3 slip is too high Why? NOx, ppm 5

6 Why? Catalyst Activity (K)? Reactor Potential? F(material, geometry) Condition of active sites NH3-slip, ppm Compliance Window Compliance Test Ability of the catalyst bed to reduce NO x RP= K * A sp * V cat / Q fg NOx, ppm Poor NH3/NOx Distribution? Uniform NH 3 /NO x profile is critical Local NH 3 /NO x >1 creates NH 3 slip Flue Gas Bypass? Any leakage around the catalyst increases stack NO x & NH 3

7 Activity, NH3 Distribution, or Bypass? FERCo utilizes a process model to compare expected SCR performance to actual performance (see curves below) A single data point is not sufficient for identifying the problem 1 NH3-slip, ppm 1 1 Compliance Test Expected (RMS=%) RMS=3% Bypass NOx, ppm 7

8 Perform Additional Tests NH3-slip, ppm NOx, ppm

9 Flue Gas Bypass? NH3-slip, ppm NOx, ppm Compliance Test Expected (RMS=%) RMS=3% Bypass NH 3 slip at high NO x suggests flue gas bypass Poor NH 3 /NO x distribution does not explain NH 3 slip at high NO x levels 9

10 Catalyst Inlet NH3/NOx Distribution and AIG Tuning

11 NH 3 /NO x Distribution and AIG Tuning RMS=5% RMS=% RMS=15% RMS=5% New Catalyst NH3 Slip, ppm 7 9 Near Catalyst End-of-Life NH3 Slip, ppm Catalyst Aging NOx Reduction, %

12 Sample Probe Grid Expedites Tuning AIG tuning is difficult without a probe grid at the catalyst exit The costs for installing a probe grid will be recovered in the long run: - No scaffolding or manlift required for testing ($, safety issues) - Reduced test times (no manual probe) - Reduced testing contractor costs - More data 5MW simple cycle SCR With a grid of 5 sample probes (5 x ) 1

13 Sample Probe Grid Expedites Tuning 13

14 Sample Probe Grid Expedites Tuning A sample grid is especially important for larger units (e.g., more than 3 wide) 35MW combined cycle SCR with a 3-point sample grid ( x ) 1

15 FERCo s Multipoint Instrumentation - Samples points in 15 minutes - NOx and O 15

16 AIG Design Influences Tuning Some systems have no AIG adjustment valves bad idea! No flexibility to account for 1) duct velocity gradients, ) duct NOx gradients, or 3) lance-to-lance ammonia flow gradients Most systems have one-dimensional adjustability NH3 Vertical adjustability can handle only vertical velocity or inlet NOx gradients Ideal design: multiple zone adjustability Multiple zones allow treatment of localized gradients 1

17 AIG Tuning, MW Gas Turbine SCR As-Found Riverside Springs Unit SCR Baseline NH3/NOx Distribution, Catalyst Inlet NH3/NOx Distribution Adjusted Riverside Springs Unit SCR NH3/NOx NH3/NOx Distribution, Distribution Adjustment #1 Catalyst Inlet One-Dimensional, Vertical AIG NH3 North Wall (ft) North Wall (ft) Duct Bottom (ft) RMS = % Adjustments across the width not possible 17 Duct Bottom (ft) RMS = 13%

18 AIG Tuning, 35MW Combined Cycle SCR As-Found Outlet NOx (ppm) NH 3 consumption reduced by 5% Optimized Outlet NOx (ppm) One-Dimensional, Vertical AIG NH West Wall (ft) 35 3 West Wall (ft) Duct Bottom (ft) 1 Adjustments across the width not possible Duct Bottom (ft)

19 Duct Burners Impact AIG Tuning Duct Burners Off (Inlet NO x ppm) Duct Burners On (Inlet NO x ppm) AIG Tough to Tune NH

20 AIG Tuning, MW Gas Turbine SCR, 9 Turn As-Found Normalized NH3/NOx Distribution Adjusted Normalized NH3/NOx Distribution Multiple zones, skewed based on flow modeling Height (ft) 1 Height (ft) Width (ft) Width (ft) RMS = 3% Corners adjusted RMS = 13%

21 SCR Catalyst Management 1

22 SCR Catalyst Management What is catalyst management? - Keeping track of catalyst activity to ensure continued compliance How is catalyst management done? - Periodically determining the activity of the catalyst in the reactor - Laboratory analysis (if a sample can be obtained) - In situ analysis (later discussion topic) - Utilize catalyst management software for planning Why is it done? - Forecast when catalyst additions or replacements are necessary - Provide sufficient lead time to procure catalyst (-9 months)

23 Catalyst Activity Degrades With Time NH3 Slip Model K/K NH3 Slip, ppm 1..,,,,, 1, Operating Hours K/Ko Monitoring ammonia slip is also critical 3

24 In Situ Catalyst Activity Measurement* Traditional Lab Measurement Typically one per year Currently no test protocol K Lab = -A Vdesign ln(1-δno x ) FERCo s CatalysTrak * in situ measurement No outage required K In-situ = -A Vactual ln(1-δno x ) full locally * Patented Process

25 Questions? 5