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OPTIMIZATION OF EXCESS AIR IN COAL FURNACE

Learn how to select and apply optimal excess air, improve combustion efficiency, monitor air ingression, & reduce emissions in coal furnace systems.

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OPTIMIZATION OF EXCESS AIR IN COAL FURNACE

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  1. OPTIMIZATION OF EXCESS AIR IN COAL FURNACE P M V Subbarao Professor Mechanical Engineering Department Selection of Sufficient Air to use the Entropy Vehicles…..

  2. Typical values of Excess Air vs Fuel

  3. Typical Layout of A Model Furnace Hchimney TCh,gas pA = pfan.f Tatm B B A pB = pfan,s Fuel

  4. Air Supply Systems

  5. Energy Potential of Post Combustion Gases Total Thermal Power of post combustion gases: Thermal Power of Chimney gases with heat Exchange to working fluid : Total Thermal Power of gases available for Utility:

  6. Measures of Inefficient Combustion Unburned carbon losses • For every 100 kg of fuel (as received) • QUCL = nc * MC* Calorific Value of Carbon : kJ • QUCL = nc * 12 * 33820 kJ. Incomplete combustion losses • For 100 kg of fuel (as received): • QICL = nCO * MCO * CV of CO. kJ. • QICL = nCO* 28 * 23717 kJ.

  7. Selection of Optimal air for Best Performance Air-Fuel Ratio

  8. Results for Best Efficiency

  9. Effect of Excess Air on Emissions

  10. Selection of Optimal air for Eco-Friendliness

  11. Learning about Impact of Excess Air

  12. Study of Impact of Excess Air

  13. Unified Optimization Methods

  14. Methods to Apply the Optimization

  15. Monitoring of Optimal Excess Air

  16. Air Ingression Due to Better Combustion Conditions

  17. Effect of Air Ingression on Actual Available Excess Air

  18. Excess Oxygen at Furnace Exit

  19. 13 Essentials of Optimum Combustion Fuel Preparation 1. Fuel feed quality and size shall be consistent. 2. Fuel feed shall be measured and controlled as accurately as possible. Load cell equipped gravimetric feeders are preferred. 3. Fuel line fineness >75% passing a 200-mesh screen, and 50 mesh particles <0.1%. Distribution to Burners 4. Primary airflow shall be accurately measured and controlled to ±3% accuracy. 5. Primary air to fuel ratio shall be accurately controlled when above minimum. 6. Fuel line minimum velocities shall be ~ 15m/s. 7. Fuel lines shall be balanced by “Clean Air” test to within 2% of average. 8. Fuel lines shall be balanced by “Dirty Air” test to within 5% of average. 9. Fuel lines shall be balanced in fuel flow to within 10% of average.

  20. 13 Essentials of Optimum Combustion Distribution to Burners 4. Primary airflow shall be accurately measured and controlled to ±3% accuracy. 5. Primary air to fuel ratio shall be accurately controlled when above minimum. 6. Fuel line minimum velocities shall be ~ 15m/s. 7. Fuel lines shall be balanced by “Clean Air” test to within 2% of average. 8. Fuel lines shall be balanced by “Dirty Air” test to within 5% of average. 9. Fuel lines shall be balanced in fuel flow to within 10% of average.

  21. 13 Essentials of Optimum Combustion Combustion 10. Over-fire air shall be accurately measured and controlled to ±3% accuracy. 11. Furnace exit shall be oxidizing; 3% oxygen is preferable. 12. Mechanical tolerances of burners and dampers shall be ±1/4’’. 13. Secondary air distribution to burners shall be within 5-10% of average.

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