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53 rd Annual ISA Power Industry Division Symposium 7-9 June 2010, Summerlin, Nevada 1 Flue Gas Analysis As A Furnace Diagnostic Tool Doug Simmers- Worldwide.

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Presentation on theme: "53 rd Annual ISA Power Industry Division Symposium 7-9 June 2010, Summerlin, Nevada 1 Flue Gas Analysis As A Furnace Diagnostic Tool Doug Simmers- Worldwide."— Presentation transcript:

1 53 rd Annual ISA Power Industry Division Symposium 7-9 June 2010, Summerlin, Nevada 1 Flue Gas Analysis As A Furnace Diagnostic Tool Doug Simmers- Worldwide Product Manager Rosemount Analytical

2 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada 2# Contents Overview of traditional applications for combustion flue gas analyzers Traditional analyzer technologies New measurement goals Analyzer applications to detect furnace anomalies New analyzer developments

3 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Traditional Application of Flue Gas Analyzers- Optimize Fuel/Air Ratios

4 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Determining CO Breakthrough- how low can your O 2 go Traditional Application of Flue Gas Analyzers- Optimize Fuel/Air Ratios

5 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Traditional Application of Flue Gas Analyzers- Optimize Fuel/Air Ratios % Steam Flow Original Setpoint Actual Data New Setpoint The point of CO breakthrough changes with firing rate. Higher firing rates induce greater turbulence in the burner(s), providing better mixing of fuel and air, and a lower possible excess O 2 setpoint. This curve should be re-established periodically, but more often is not.

6 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada New Measurement Goals- Staged Combustion for NOx Reduction Excess air flow quenches the flame, Lowering reaction temperatures below That required to make NOx Not enough O2 to react into NOx Flue gas O 2 setpoints may be shifted up or down, based on minimizing the amount of NOx and CO produced at the burner

7 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada New Application- Flue Gas Recirculation Controlling Final O 2 Entering The Wildbox Flue Gas 3 % O 2 Windbox Burner Primary Air O2 Probe 21% O 2 18% O 2

8 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada New Measurement Goals- Slag Prevention Ash fusion temperatures vary with flue gas O 2 levels

9 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Application Overview- Large, Multi-burner Furnaces Combustion analyzers are typically placed in the back pass of the furnace, and used to establish the optimum fuel/air ratio, minimize NOx, and also providing diagnostic information about the burner array, classifiers, and coal mills. Probes

10 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Typical flue gas Analyzers In Situ O2 Probe Extractive O2/ combustibles system Point Measurements Averaging, Line-of-sight Measurements Spectroscopy IR for CO Laser IR for CO and O2 (NOx is also possible)

11 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Zirconium Oxide Fuel cell technology is commonly used Output is inverse, and logarithmic. –Cell generates its own signal, which increases at the low O2 levels commonly experienced in combustion processes. –Accuracy actually improves at lower O2 levels. No sampling system required. Passive diffusion- filters last a long time before plugging in high particulate applications Speed of response is fast. Cost effective Sensing cells are robust. Operate well at elevated temperatures Sulfur resistance is good. Cell life can easily exceed 3-5 years. Typical flue gas Analyzers – In Situ Oxygen Probe

12 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Typical flue gas Analyzers In Situ O2 Probe Extractive O2/ combustibles system Point measurements Averaging, line-of-sight measurements Spectroscopy IR for CO Laser IR for CO and O2 (NOx is also possible)

13 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Typical flue gas Analyzers – Close-Coupled Extractive (no sample conditioning) Same ZrO 2 Oxygen sensor Calorimetric combustibles sensor Detects CO breakthrough, but cannot resolve fine PPM CO levels May require frequent maintenance in high particulate applications (coal, biofuels, garbage incineration, etc.) OCX 8800 Launch Presentation July 09, 2009 // Slide 13

14 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Typical flue gas Analyzers In Situ O2 Probe Extractive O 2 / combustibles system Point measurements Averaging, line-of-sight measurements Spectroscopy IR for CO Laser IR for CO and O 2 (NOx is also possible)

15 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Typical flue gas Analyzers – IR or Laser Spectroscopy for CO Most implementations are across-stack, or line-of sight. –Averages across the flue duct. –Difficult to challenge with a known calibration gas. CO is a good absorber of IR about 470nm wave number CO as well as O2 and NOx can be reliably detected with tunable diode laser systems. Typical Installation

16 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Historical Progression of Point O 2 Analysis In Large Multi-Burner Furnaces Early years a single O2 Probe per flue gas duct is sufficient- placement is somewhere near the middle Confused a second O2 probe is added, to get a better average for fuel/air ratio adjustment –The two probes rarely agree, so operators trust the readings from neither probe. –After many calibrations, its understood that both probes are telling the truth, and significant stratification exists in the ductwork More probes are added in order to again get a better O2 average –More stratification is witnessed by the operators, and more confusion ensues –Probes that are particularly out of the norm are often removed from the average (exactly the wrong thing to do)!

17 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Average O2 for Fuel/Air Ratio Control Predictive Maintenance Tool Seeking out stratification- Rather than avoid stratification, plant operators are more and more trying to determine what flue gas stratification is telling them. Balancing Burners Detecting Burner Fouling Poor coal distribution/roping Mill to mill variations

18 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Focusing In On The Real Process(es) Each burner and coal mill constitutes a separate process of its own The furnace is an envelope

19 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Burner Diagnostics- Analyzer Placement Is Important Burner columns are easier to identify with a wall-fired furnace Corner to corner variations in a tangentially fired furnace are harder to discern

20 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Changing Measurement Locations Coal-fired boilers –Most boiler manufacturers provide testing ports after the economizer, hopper, which are often utilized for permanently mounted analyzers. –An upstream location ahead of the economizer has advantages –Large particle ash, or popcorn ash is less prominent- abrasion on probes is less. –Stratification is greater, burner column by burner column

21 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Fine Tuning Probe Placement With Variable Insertion

22 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Variable Insertion Probe- looking for the ideal measuring point.

23 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Furnace Diagnostics- Detecting Air Leaks Air Heater Seal Leakage- the delta O2 before and after an air heater helps determine seal leakage

24 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Furnace Diagnostics- Flue duct seal leaks are indicated by outer probes reading higher 3.4 % 2.9 % 3.2 %3.3 % 3.1 % 4.1 %3.8 % Furnace Diagnostics- Detecting Air Leaks

25 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Furnace Diagnostics- Beyond Total Furnace Average 2.9% 3.2 %3.3 % 3.0 % 3.3 %3.4 % 3.1% 3.4 %3.1 % 3.0 % 3.3 %2.9 % Duct A Average Duct B Average Mill average- Burners fed from common pulverizer mills may show similar readings when mill/classifier problems arise. Duct averages can shift left or right with ID fan load changes

26 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Furnace Diagnostics- Soot Blow Problems/Tube breaks O 2 readings will be affected by the dilution of water entering in the furnace –O 2 dry= O 2 wet (1/1-H 2 O –Soot blow/water lance –Tube breaks

27 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Duct Burners for Combined Cycle Combustion Turbines

28 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Duct Burners Increase Steam Production, But Now O 2 Can Be Controlled To A More Efficient Level.

29 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada New Developments In Z r O 2 - Getting New Information From A Reliable Sensor Technology Recovering from process upsets- A Z r O 2 sensor that measures the level of O 2 deficiency during reducing events. O 2 range is depressed -2% to 10% During process upsets into reducing conditions, the operator can see the level of O 2 deficiency, and see if his corrections are adequate Zero % O 2

30 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada New Developments In Z r O 2 - Getting New Information From A Reliable Sensor Technology New Z r O 2 probe sensor that measures CO breakthrough. CO Probe O 2 Probes Boiler load (megawatts) IR CO analyzer

31 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Summary Flue gas analysis has historically provided a good tool for optimizing fuel/air ratios in large furnaces Analyzers help achieve new goals such as NOx reduction and slag reduction. Multi-burner furnaces often have significant flue gas stratification, which is often a cause for operator concern Stratification profiles provide a great diagnostic of upstream processes at the burners and pulverizers –The furnace is just an envelope for the process– each burner is its own process. –Point measurements provide good granularity of upstream burner columns, but more instruments are required in order to get a good average –Line-of-sight measurements are inherently averaging, so fewer are required to get a good total average, but stratification is masked New developments in CO measurements will improve NOx reduction, combustion efficiency, and burner diagnostics.

32 53rd Annual ISA POWID Symposium, 7- 9 June 2010, Summerlin, Nevada Thank You- Questions? Chris Morrissey- S. California Sales Engineer (951) Chris Lesser- RM Regional Sales Manager (303) Dave Anderson- Marketing Manager (949) Doug Simmers- Worldwide Product Manager (330)


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