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Improve fired heaters performance and reliabilty

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Fired heaters are often suffering from high tube metal temperatures and short run lengths. Operators are always worried about hot spots in the furnace. While refineries want to push the heaters hard, the heater starts coking up and very soon, the heater tubes have to be cleaned.
FIS has done extensive research and CFD modelling of heaters in the recent time and has concluded that localized burner flame and hot flue gas currents are responsible for the hot spots on the tubes. FIS has now developed a new patented technology for solving hot spot problems. This technology called Inclined Firing Technology involves orienting the burners at an angle on the floor / wall/ roof to direct the flame away from the tubes. The results of this technology have been extremely good and with a very low investment, the reliability and run length of the heater is improved significantly.

Published in: Technology, Business

Improve fired heaters performance and reliabilty

  1. 1. Furnace Improvements Services Improving Fired Heaters Performance and Reliability Ashutosh Garg Furnace Improvements www.heatflux.com 1
  2. 2. Fired Heaters Furnace Improvements Services Stack Important equipment in refineries and chemical plants High temperature heat transfer Fuel gas fired High tube metal temperature problem Coking Shutdown Damper Finned/ Studded Tubes Breech Convection Section Shield Tubes Radiant Tubes Radiant Section Peep Door Burners www.heatflux.com Floor 2
  3. 3. Operating and Reliability Issues Furnace Improvements Services High tube metal temperatures is the biggest problem in fired heater operation Most of the high tube metal temperatures is due to localized flame impingement. Fired heaters have burners that are fired vertically upright, sideways or downwards. FIS patented technology reorient the burner at a slight angle away from the tubes. Hottest flame and flue gases are moved away from the tubes. www.heatflux.com 3
  4. 4. Benefits of Inclined Firing System Furnace Improvements Services Significant reduction in tube metal temperatures Low coking rates Higher tube life and run lengths Increased capacity possible in most heaters Uniform firing achieved across the tubes www.heatflux.com 4
  5. 5. Furnace Improvements Services Inclined Firing System OUTLET 12'-9" TCD 12'-9" TCD 4' 4'-4 ½” 6' 12'-9" 5' 2'-7" 1/29/2014 4' BCD Burners are INLET inclined at 5-10 deg. www.heatflux.com 2'-7" 4' BCD 5
  6. 6. 5' 5' 4'-6" 5' 5' 6' 5' 5' 4'-6" 35'-6" 35'-6" 5-10deg. INTERHEATER -2 INTERHEATER -1 CHARGE HEATER
  7. 7. Inclined Firing System in a Down Fired Steam Reformer Furnace Improvements Services C BURNER L C BURNER L C BURNER L C BURNER L C BURNER L PROPOSED INCLINED BURNER PROPOSED INCLINED BURN 3.5o 4'-0" 2'-8 1/2" 5'-5" 20'-0 7/8" (SHELL WIDTH) EXISTING 7.0000 113.0000 2'-8 1/2" 4'-0"3.5o 2'-8 1/2" 5'-5" 5'-5" 5'-5" 5'-5" PROPOSED 20'-0 7/8" (SHELL WIDTH) 20'-0 7/8" (SHELL WIDTH) 113.0000 113.0000 4'-0" 2'-8 1/2" 2'-8 1/2" 5'-5" 3.0000 7.0000 2'-8 1/2" 4'-0" 2'-8 1/2" 3.5o 7.0000 7.0000 113.0000 7.0000 20'-0 7/8" (SHELL WIDTH) 113.0000 113.0000 113
  8. 8. HDS Depentanizer Reboiler H-102 Burners 6’-8” (B.C.D) EXISTING C BURNER L C BURNER L 6’-8” (B.C.D) C HEATER L 14’-0 1/4” (T.C.D) C BURNER L 14’-0 1/4” (T.C.D) Furnace Improvements Services www.heatflux.com PROPOSED 8
  9. 9. Depentanizer Reboiler H-205 Burners C BURNER L 11’-8 1/8” (T.C.D) C BURNER L (B.C.D) C HEATER L C BURNER L 11’-8 1/8” (T.C.D) Furnace Improvements Services 5’-6” (B.C.D) COMMON PLENUM EXISTING PROPOSED www.heatflux.com 9
  10. 10. Furnace Improvements Services EXISTING 3962 (P.C.D.) 3200 (P.C.D.) F-4202 F-4201 C BURNER L www.heatflux.com C BURNER L 1372 B.C.D. C BURNER L C BURNER L 762 B.C.D. 10
  11. 11. Proposed Burner Layout in a VC Heater 3200 (P.C.D.) 3962 (P.C.D.) F-4202 F-4201 5.5° .) (TY P ER C BU R N L ER 1372 B.C.D. C BU R N ER L C BU R N L C BU R N L ER 3° .) (TY P 762 B.C.D. Furnace Improvements Services ⌽2350 ⌽1650 FLOOR PLT. FLOOR PLT. www.heatflux.com 11
  12. 12. Case Studies Furnace Improvements Services Two case studies presented in this paper First one – Coker Heater Second one – Crude Heater Both cases had high tube metal temperatures CFD Modeling carried out to demonstrate the benefits of Inclined Firing Can be used with all types of burners and in all types of heaters ( Contact FIS with your specific case ) www.heatflux.com 12
  13. 13. Start CFD Modeling CAD Geometry CAD Geometry & Meshing Boundary Conditions Diverge Solver Converged Solution Optimization Post Processor CFD Analysis Furnace Improvements Services Computational Fluid Dynamics Uses numerical methods and algorithms to study fluid flow Flow patterns in fired heaters, burners, fireboxes 3D models of fired equipment are created End www.heatflux.com 13
  14. 14. Coker Heater Furnace Improvements Services  High tube metal temperature issues  Fuel gas fired low NOx burners www.heatflux.com 14
  15. 15. Heater Geometry Furnace Improvements Services Air inlet Heater Geometry www.heatflux.com Burner Geometry 15
  16. 16. Results Furnace Improvements Services The flow pattern of flue gases is shown using  Velocity Vectors  Path Lines The temperature profile in the heater is shown using  Temperature Contours The flame profile is shown using  CO envelope of 2000 ppm www.heatflux.com 16
  17. 17. Velocity Vectors (ft/s) Zoomed View Furnace Improvements Services Plane @ Primary tip www.heatflux.com 17
  18. 18. Velocity Vectors (by temperature) (F) Furnace Improvements Services Plane @ Primary tip www.heatflux.com 18
  19. 19. Temperature Contours (°F) Furnace Improvements Services Plane @ Primary tip www.heatflux.com 19
  20. 20. Tube Metal Temperature Contours Furnace Improvements Services (°F) www.heatflux.com 20
  21. 21. Refractory Temperature Contours (°F) www.heatflux.com Furnace Improvements Services 21
  22. 22. Flames Shape (Iso-Surface of CO 2000 ppm) B-1 (°F) B-2 B-3 Colored by Temperature Furnace Improvements Services B-4 22
  23. 23. Inclined Firing Furnace Improvements Services Air inlet Heater Geometry Burners are inclined by 7.5 deg towards the walls www.heatflux.com Burner Geometry 23
  24. 24. Velocity Vectors Furnace Improvements Services Inclined Firing Plane @ Primary tip (ft/s) www.heatflux.com 24
  25. 25. Temperature Contours Furnace Improvements Services Inclined Firing (°F) Plane @ Primary tip www.heatflux.com 25
  26. 26. Tube Metal Temperature Contours Furnace Improvements Services Inclined Firing (°F) www.heatflux.com 26
  27. 27. Iso-Surface of CO 2000 ppm Furnace Improvements Services Inclined Firing (°F) B-1 B-2 B-3 B-4 Colored by Temperature www.heatflux.com 27
  28. 28. Vertical Up Firing VS. Inclined Firing Furnace Improvements Services Flow Profiles www.heatflux.com 28
  29. 29. Vertical Up Firing VS. Inclined Firing Furnace Improvements Services Temperature www.heatflux.com 29
  30. 30. Vertical Up Firing VS. Inclined Firing Furnace Improvements Services Flame Profile www.heatflux.com 30
  31. 31. Conclusion Furnace Improvements Services Inclined firing resulted in reduction of tube metal temperatures by about 40-50 F Elimination of flame impingement Longer life of tubes Longer heater run lengths www.heatflux.com 31
  32. 32. Case Study-2-Crude Heater Furnace Improvements Services  Client facing flame impingement and high tube metal temperatures in radiant section  FIS recommended inclined burner firing system to eliminate flame impingement  Carry out CFD Modeling of the Burners and Radiant Section to demonstrate the benefit of inclined burner firing system www.heatflux.com 32
  33. 33. Existing Burner Arrangement Furnace Improvements Services EXISTING FLOOR & PLENUM ARRANGEMENT www.heatflux.com 33
  34. 34. Inclined Firing System Burner Arrangement www.heatflux.com Furnace Improvements Services 34
  35. 35. Velocity vectors (ft/s) ° Base case vs. Inclined Firing System Furnace Improvements Services 50 ft 36 ft 19 ft 0 ft height in ft www.heatflux.com 35
  36. 36. Temperature Contours Base Case VS. inclined firing system Base case Furnace Improvements Services Inclined Firing System www.heatflux.com 36
  37. 37. Temperature contours(°F) at 10 ft section- Base Case VS. inclined firing system At 10 ft Base case www.heatflux.com Furnace Improvements Services At 10 ft Inclined Firing System 37
  38. 38. Temperature contours (°F) at 15 ft section- Base Case VS. inclined firing system Furnace Improvements Services 1 At 15 ft Base case www.heatflux.com At 15 ft Inclined Firing System 38
  39. 39. CO mass fraction contours (PPM) at 10 ft section- Base Case VS. inclined firing system Furnace Improvements Services 1 At 10 Ft Base Case www.heatflux.com At 10 Ft. Inclined Firing System 39
  40. 40. CO mass fraction contours (PPM) at 15 ft section- Base Case VS. inclined firing system Furnace Improvements Services 1 At 15 Ft. Base Case www.heatflux.com At 15 Ft. Inclined Firing System 40
  41. 41. Base Case VS. inclined firing system Furnace Improvements Services Flow on radiant tubes Quarter section view • Pathlines shows the flow towards radiant section for the base case at entrance of heater • However for inclined firing system flow does not interact to radiant tubes at entrance of heater
  42. 42. Iso surface of CO mf 2000 PPM colored by temperatures (o F) Base Case VS. Inclined Firing System Base Case Top View www.heatflux.com Furnace Improvements Services Inclined Firing System 42
  43. 43. Iso surface of CO mass fraction 2000 PPM colored by flame height (ft) Base case VS. www.heatflux.com Furnace Improvements Services Inclined Firing System 43
  44. 44. Radiant wall temperatures (°F) Furnace Improvements Services For h =100 Btu/ft2-h and T=800 °F Base design www.heatflux.com Modified design 44
  45. 45. Summary Furnace Improvements Services Inclined Firing is proven in solving high tube metal temperatures problems CFD Modeling helped in demonstrating the benefit in performance improvement FIS is ready to evaluate your heater if it is a suitable candidate for inclined firing at no cost. www.heatflux.com 45
  46. 46. Furnace Improvements Services We hope you will find our presentation helpful and informative. www.heatflux.com 46

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