Industrial Boiler Troubleshooting

Paper from the AFRC 2017 conference titled Industrial Boiler Troubleshooting

Industrial Combustion Symposium AFRC 2017 Matthew Whelan, PE John Zink Company LLC December 13, 2017 Important Notice The information contained in these materials is for informational purposes only and is provided "AS IS", without warranties of any kind. Your use of the information contained herein is at your sole risk. We expressly disclaim any express or implied representations, warranties or guaranties, including without limitation, the implied warranties of merchantability and fitness for a particular purpose. We will have absolutely no liability (whether direct, indirect or consequential) in connection with these materials (and/or the information contained therein) including without limitation, any liability for damage to person or property. We also reserve the right to make subsequent changes to the materials without prior notice. 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For information on patents and trademarks, see johnzinkhamworthy.com/legal-notices ©2017 John Zink Company, LLC **Proprietary & Confidential** 2 Boiler Troubleshooting Presentation Agenda § Challenges § New Tools § Vibration Case Studies § Case Study 1 § Case Study 2 § Legacy Boiler Case Study § Case Study 3 ©2017 John Zink Company, LLC **Proprietary & Confidential** 3 Challenges Industry Goals §NOx Reduction (FGR, Low NOx burner retrofit) §Thermal Efficiency Optimization Challenges §Increased probability of vibration §Legacy Equipment (boilers, controls, etc.) § e.g. Combustion Air Leakage (Field-erect units) ©2017 John Zink Company, LLC **Proprietary & Confidential** 4 New Tools §Practical use of Computation Fluid Dynamics (CFD) Analysis §Normalized and calibrated CFD models §Handheld Devices for Data Capture §Improved Data Analytics, Process Simulation, and Custom Engineered Controls ©2017 John Zink Company, LLC **Proprietary & Confidential** 5 Industrial Boiler Troubleshooting Vibration in Combustion Systems Overview Vibration function of §Pressure pulsations within the system § Typical frequency range 1 Hz - 400 Hz §Stiffness of the structure §Vibration can cause mechanical damage, component failure, loss of reliability ©2017 John Zink Company, LLC **Proprietary & Confidential** 6 Industrial Boiler Troubleshooting Vibration Analysis & Data Collection Data to Collect §High-speed pressure data §Wall structure acceleration and deflection amplitude §Ambient sound measurement §High-speed video capture ©2017 John Zink Company, LLC **Proprietary & Confidential** 7 Industrial Boiler Troubleshooting Vibration Analysis & Data Collection Measurements §Multiple points on system (e.g. furnace, windbox) §Firing rate and process condition variation §Fan-only data ©2017 John Zink Company, LLC **Proprietary & Confidential** 8 Vibration Data Analysis Data conversion §Convert Raw high-speed timeseries pressure data to Processed frequency spectrum data using signal analysis algorithm §e.g. Fast Fourier Transform (FFT) ©2017 John Zink Company, LLC **Proprietary & Confidential** 9 Vibration Data Analysis Analysis Methodology §Analyze raw time-series pressure data §Analyze processed frequency band data for peaks §Compare Raw to Processed Data ©2017 John Zink Company, LLC **Proprietary & Confidential** 10 Vibration Data Analysis Based on findings, potential additional analysis §Structural Analysis §System Natural Frequency Analysis §Equipment Design Review ©2017 John Zink Company, LLC **Proprietary & Confidential** 11 Vibration - Analysis ©2017 John Zink Company, LLC **Proprietary & Confidential** 12 Case Study 1 - Vibration Overview §Application § Industrial Boiler § Single Burner with FGR § Low NOx Burner ©2017 John Zink Company, LLC **Proprietary & Confidential** 13 Case Study 1 - Challenge Vibration §Wall Deflections and shaking §At firing rates >30% §Not resolved with tuning ©2017 John Zink Company, LLC **Proprietary & Confidential** 14 Case Study 1 - Testing Test Locations Methods § High-speed pressure data collection § Measure wall deflection amplitude § Collect data at varying firing rates ©2017 John Zink Company, LLC **Proprietary & Confidential** 15 Case Study 1 - Data Time-Series Data Raw Time-Series Pressure Data, Furnace 12 §High Amplitude 11 10 §Signal is repeatable §Highest Amplitude in Furnace Amplitude (inwc) 9 8 7 6 5 4 3 2 1 0 0 1 2 3 4 5 Time,s ©2017 John Zink Company, LLC **Proprietary & Confidential** 16 Case Study 1 - Data Processed Data Processed Data (FFT), Pressure Oscillation 0.8 §Peaks at 10.4 Hz and 2.6 Hz 0.7 §Peaks do not shift with firing rate Amplitude (inwc) 0.6 0.5 0.4 0.3 0.2 §Peak amplitudes are sharp 0.1 0.0 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 Frequency (Hz) ©2017 John Zink Company, LLC **Proprietary & Confidential** 17 Case Study 1 - Analysis ©2017 John Zink Company, LLC **Proprietary & Confidential** 18 Case Study 1 - Analysis Vibration Data Observations §FGR and Excess Air variation ineffective §Fan speed and damper settings ineffective §Peaks Constant Frequency → Not velocity or flow dependent ©2017 John Zink Company, LLC **Proprietary & Confidential** 19 Case Study 1 - Analysis Potential Source of Acoustic Resonance [System Natural Frequencies that are not velocity dependent] §Helmholtz (Active) §Based on system internal geometry of air and flue gas passages §Structural (Passive) §Based on structure mass, geometry, and bracing ©2017 John Zink Company, LLC **Proprietary & Confidential** 20 Case Study 1 - Conclusions § Attenuate Helmholtz Resonance § Add resistance to flow passages § Strengthen Structure § Add bracing to weakest wall structures ©2017 John Zink Company, LLC **Proprietary & Confidential** 21 Case Study 1 - Results §Changes §Added flow resistance to boiler stack §Added additional stiffeners to structure §Results §Resolved vibration to acceptable level ©2017 John Zink Company, LLC **Proprietary & Confidential** 22 Case Study 2 - Vibration Overview §Application § Industrial Boiler § (3) down-fired burners § Ultra Low NOx Burner Retrofit ©2017 John Zink Company, LLC **Proprietary & Confidential** 23 Case Study 2 - Challenges Vibration § Wall Deflections § Low frequency (<5 Hz) § At firing rates >30% § Not resolved with tuning (e.g. excess air or FGR) § Reports of vibration prior to retrofit ©2017 John Zink Company, LLC **Proprietary & Confidential** 24 Case Study 2 - Testing Test Locations § Methods § High speed pressure data collection § Measure wall deflection amplitude § Test Steps § Firing Rate Variation § Excess Air Variation § FGR Variation ©2017 John Zink Company, LLC **Proprietary & Confidential** 25 Case Study 2 - Data Raw Time - Series Data Raw Data, Pressure Oscillation § Erratic Amplitude (inwc) § Low Frequency § High Amplitude § Matches observed wall vibration § Amplitude unchanged with excess air and FGR variation ©2017 John Zink Company, LLC 0.0 **Proprietary & Confidential** 1.0 2.0 3.0 4.0 5.0 Time,s 26 Case Study 2 - Data Processed Data § No significant frequency peaks § Max Amplitude <15% of raw amplitude § Amplitude not significant ©2017 John Zink Company, LLC **Proprietary & Confidential** 27 Case Study 2 - Analysis ©2017 John Zink Company, LLC **Proprietary & Confidential** 28 Case Study 2 - Analysis Fan Review - Fan only operation §Low amplitude §Fan not an acoustic driver §Combustion is mostly likely source ©2017 John Zink Company, LLC **Proprietary & Confidential** 29 Case Study 2 Structural Analysis § Wall deflection §Calculated (from Pressure force) = ~0.005" §Observed = ~0.15" §Structural natural frequency §Calculated = >25 Hz §Observed = <6 Hz ©2017 John Zink Company, LLC **Proprietary & Confidential** 30 Case Study 2 Conclusions §Potential structural failure §Combustion likely vibration driver §Burner design changes required ©2017 John Zink Company, LLC **Proprietary & Confidential** 31 Case Study 2 Design Changes §Inspect, review, and repair bracing §Change fuel injection pattern ©2017 John Zink Company, LLC **Proprietary & Confidential** 32 Case Study 2 - Results Significant Reduction of Vibration ©2017 John Zink Company, LLC **Proprietary & Confidential** 33 Case Study 3 - Legacy Boiler Overview §Application §Industrial waste boiler §Grate fired solid fuel §Wall-fired NG burners ©2017 John Zink Company, LLC **Proprietary & Confidential** 34 Case Study 3 Challenges §High NOx §Poor thermal efficiency §Particulate (unburned solid fuel) ©2017 John Zink Company, LLC **Proprietary & Confidential** 35 Case Study 3 - Analysis Site Observations §Variable waste fuel (H2O, LHV) §NOx decreased with lower furnace O2 §Some airflow controls manual ©2017 John Zink Company, LLC **Proprietary & Confidential** 36 Case Study 3 - Analysis CFD Analysis §Stratification §Key Incineration Criteria § Minimum Temperature § Minimum Oxygen § Flame shape and Mixing ©2017 John Zink Company, LLC **Proprietary & Confidential** 37 Case Study 3 Root Cause Analysis § NOx § High nitrogen solid fuel § Lower O2 is beneficial § Unburned Particulate § Variable water content and heating value of waste solid fuel § Must maintain minimum bulk furnace temperature § Thermal Efficiency § Lack of instrumentation and control of combustion airflow ©2017 John Zink Company, LLC **Proprietary & Confidential** 38 Case Study 3 - Review §Retrofit Options § Burner Design Alternatives § Optimized Burner Spacing § Air Injection Design Changes §Customized Control Upgrades § Improved Instrumentation, Metering, and Control Logic ©2017 John Zink Company, LLC **Proprietary & Confidential** 39 Case Study 3 - Design Analysis Review Summary ©2017 John Zink Company, LLC **Proprietary & Confidential** 40 Case Study 3 - Upgrades §Solid Fuel Instrumentation and Logic §New online solid fuel water content analysis §Auto-compensate burner firing rate based on water content §Logic to maintain constant bulk furnace temperature ©2017 John Zink Company, LLC **Proprietary & Confidential** 41 Case Study 3 - Upgrades § Combustion Air Metering and Logic § Meter and automate each air zone § Optimum split determined by test § Custom logic implemented to minimize total air and optimize distribution ©2017 John Zink Company, LLC **Proprietary & Confidential** 42 Case Study 3 - Overview For legacy combustion systems, controls and instrumentation upgrades may provide biggest value-add. ©2017 John Zink Company, LLC **Proprietary & Confidential** 43 Questions? ©2017 John Zink Company, LLC **Proprietary & Confidential** 44