Method, system and apparatus for firing control

• US 20090029300A1
• Filed: 07/25/2007
• Published: 01/29/2009
• Est. Priority Date: 07/25/2007
• Status: Active Grant

• Current Assignee: Lummus Technology Inc.
• Original Assignee: Lummus Technology Inc.
• Inventors: Ponzi, Peter R., Gartside, Robert J., Bertola, Francesco
• Granted Patent: US 8,408,896 B2
• Time in Patent Office: Days
• US Class Current: 431/12
• CPC Class Codes: F23C 5/08 Disposition of burners
• CPC Class Codes: F23D 14/08 with axial outlets at the burner head
• CPC Class Codes: F23D 14/10 with elongated tubular burner head
• CPC Class Codes: F23D 14/60 Devices for simultaneous control of gas and combustion air
• CPC Class Codes: F23D 14/64 with injectors
• CPC Class Codes: F23L 2900/07002 Injecting inert gas, other than steam or evaporated water, into the combustion chambers
• CPC Class Codes: F23L 7/00 Supplying non-combustible liquids or gases, other than air, to the fire, e.g. oxygen, steam
• CPC Class Codes: F23N 1/002 using electronic means F23N1/04 - F23N1/10 take precedence
• CPC Class Codes: F23N 1/022 using electronic means
• CPC Class Codes: F23N 2221/10 Analysing fuel properties, e.g. density, calorific
• CPC Class Codes: F23N 2235/06 at the air intake
• CPC Class Codes: F23N 2237/08 two or more different types of fuel simultaneously

Abstract

Disclosed herein is a method of controlling the air to fuel ratio in a burner containing a venturi assembly. The venturi includes an air inlet, a primary fuel inlet with a converging section, a throat portion downstream from the converging section, a diverging section downstream from the throat portion, an outlet, and a secondary gas inlet disposed downstream from the converging section and upstream from the outlet. The method comprises introducing fuel into the fuel inlet, receiving air through the air inlet by inspiration, and feeding a gas through the secondary gas inlet, the flow rate and content of the gas fed through the secondary gas inlet being selected to result in a desired air to fuel ratio through the outlet. A method of firing a heater, a burner, a furnace and firing control systems also are disclosed.

Claims

1. A method of controlling the air to fuel ratio in a burner comprising a venturi assembly having an upstream air inlet, a converging portion with a primary injection fuel inlet, a throat portion downstream from the converging portion, a diverging portion downstream from the throat portion, an outlet, and a secondary gas inlet disposed downstream from the converging portion and upstream from the outlet, the method comprising introducing fuel into the primary injection fuel inlet, receiving air through the air inlet by inspiration, and feeding a gas through the secondary gas inlet, the flow rate and content of the gas fed through the secondary gas inlet being selected to result in a desired air to fuel ratio through the outlet.

2. The method of claim 1, wherein the fuel has a heating value in the range of about 100 BTU/stdcuft to about 1200 BTU/stdcuft.

3. The method of claim 2, wherein the fuel is a conventional fuel or a synthesis gas, and the conventional fuel and synthesis gas can be fed interchangeably.

4. The method of claim 1, wherein the gas fed through the secondary gas inlet is fuel.

5. The method of claim 1, wherein the gas fed through the secondary gas inlet is an inert gas.

6. The method of claim 1, wherein fuel and an inert gas are interchangeably fed through the secondary gas inlet.

7. The method of claim 1, wherein a mixture of fuel and an inert gas are fed through the secondary gas inlet.

8. The method of claim 1, wherein the secondary gas inlet is disposed downstream from the throat portion.

9. The method of claim 1, wherein the venturi assembly includes a tubular portion downstream from the diverging portion, and the secondary gas inlet is formed on the tubular portion.

10. The method of claim 1, further comprising altering at least one of flow direction and flow velocity downstream from the secondary gas inlet.

11. The method of claim 10, wherein altering at least one of flow direction and flow velocity is effected with a flow resistance component.

12. The method of claim 1, wherein the burner is a hearth burner.

13. The method of claim 1, wherein the burner is a wall burner.

14. The method of claim 1, wherein an induced draft fan is included downstream from the outlet.

15. The method of claim 1, wherein a damper is included upstream of the venturi assembly to provide additional control of the flow rate of air through the air inlet.

16. The method of claim 1, wherein fuels having a volumetric heating value in the range of 100 to 1200 Btu/stdcuft can be used interchangeably.

17. A method of firing a heater having at least one burner comprising a venturi assembly having an upstream air inlet, a converging portion with a primary injection fuel inlet, a throat portion downstream from the converging portion, a diverging portion downstream from the throat portion, an outlet, and a secondary gas inlet disposed downstream from the converging portion and upstream from the outlet, the method comprising introducing fuel into the primary injection fuel inlet, the fuel inspirating air into the air inlet, and feeding a gas through the secondary gas inlet, wherein a mixture of air and fuel in a selected air to fuel ratio exits the venturi assembly through the outlet.

18. The method of claim 17, wherein low heating value fuel and high heating value fuel can be used interchangeably.

19. The method of claim 17, wherein the gas comprises fuel.

20. The method of claim 17, wherein the gas comprises an inert gas.

21. The method of claim 17, wherein the venturi assembly has a resistance component positioned downstream from the secondary gas inlet.

22. The method of claim 17, wherein the heater has a plurality of hearth burners and a plurality of wall burners and the fuel has a low heating value, further comprising feeding at least a portion of said low heating value fuel through at least one additional port positioned in at least one of a first location adjacent to the hearth burners and a second location in the wall of the heater below the wall burners and above the hearth burners.

23. A burner including a venturi assembly comprising an air inlet, a converging portion with a primary injection fuel inlet, a throat portion downstream from the converging portion, a diverging portion downstream from the throat portion, an outlet, and a secondary gas inlet disposed downstream from the converging portion and upstream from the outlet.

24. The burner of claim 23, further comprising a resistance component disposed downstream from the secondary gas inlet.

25. The burner of claim 24, wherein the resistance component is disposed proximate the outlet.

26. The burner of claim 23, wherein the burner is a hearth burner.

27. The burner of claim 23, wherein the burner is a wall burner.

28. The burner of claim 23, further comprising a damper disposed upstream of the venturi assembly.

29. The burner of claim 23, wherein the secondary gas inlet is configured to be connected to a supply line of at least one of a fuel and an inert gas.

30. The burner of claim 23, wherein the secondary gas inlet is configured to be connected to both a fuel supply line and an inert gas supply line.

31. The burner of claim 24, wherein the resistance component alters at least one of flow direction and flow velocity.

32. The burner of claim 23, wherein the burner comprises a plurality of venturi assemblies having a secondary gas inlet disposed downstream from the converging portion and upstream from the outlet.

33. A firing control system for controlling the air to fuel ratio in a burner assembly including at least one venturi assembly comprising an air inlet, a converging portion with a primary injection fuel inlet, a throat portion downstream from the converging portion, a diverging portion downstream from the throat portion, an outlet, and a secondary gas inlet disposed downstream from the converging portion and upstream from the outlet,

the firing control system comprising a first flow control device configured to control fuel inlet flow at the primary injection fuel inlet, a second flow control device configured to control gas inlet flow to the secondary gas inlet, and a fuel analysis component configured to determine whether the fuel at the fuel inlet has a lower heating value or a higher heating value.

34. The firing control system of claim 33, wherein at least one of the first and second flow control devices is a valve.

35. The firing control system of claim 33, wherein at least one of the first and second flow control devices is a pressure regulator.

36. The firing control system of claim 33, further comprising a damper for assisting in control of the air inlet flow rate.

37. A firing control system for a furnace comprising a hearth, a side wall, and a burner assembly with at least one burner including a venturi assembly comprising an air inlet, a converging portion with a primary injection fuel inlet, a throat portion downstream from the converging portion, a diverging portion downstream from the throat portion, an outlet, and a secondary gas inlet disposed downstream from the converging portion and upstream from the outlet,

the firing control system comprising a first flow control device configured to control fuel inlet flow to the primary injection fuel inlet and a second flow control device configured to control inlet flow to the secondary gas inlet.

38. The firing control system of claim 37, wherein the flow rates through the first and second flow control devices are varied depending upon at least one of the composition of the fuel, the heating value of the fuel, the oxygen content at the heater outlet, and the desired air flow rate through the venturi assembly.

39. The firing control system of claim 38, further comprising a first set of staged burner ports on at least one of the hearth and the wall, and a second flow control device configured to control inlet flow to the first set of staged burner ports.

40. The firing control system of claim 39, further including a third flow control device configured to control inlet flow of a low heating value fuel to a second set of staged burner ports adjacent the first set of staged burner ports.

41. The firing control system of claim 38, further including a fuel analysis component configured to determine at least one of the composition and heating value of the fuel being fed to the primary injection fuel inlet.

42. The firing control system of claim 41, wherein the first and second flow control devices are controlled by the fuel analysis component.

43. A firing control system for a furnace comprising a hearth, a side wall, a furnace fuel inlet, and a burner comprising a venturi assembly with a first fuel inlet and a second fuel inlet,

the firing control system comprising an oxygen analysis component configured to determine the post-combustion oxygen content of the furnace, the oxygen analysis component being used to adjust the relative fuel flow rates to the first and second fuel inlets of the venturi assembly.

44. A firing control system for a furnace comprising a hearth, a side wall, and a burner with a furnace fuel inlet and a supplemental fuel inlet,

the firing control system comprising a fuel analysis component configured to determine whether the fuel at the fuel inlet has a lower heating value or a higher heating value, the fuel analysis component being used to control the flow rate of fuel to at least one of the furnace fuel inlet and the supplemental fuel inlet.

45. A furnace comprising a plurality of hearth burners, a plurality of wall burners, a first set of staged burner ports for at least one of the plurality of hearth burners and the plurality of wall burners, and a second set of staged burner ports adjacent the first set, wherein only the first set of staged burner ports is used with higher heating value fuels, and wherein both the first and second sets of staged burner ports are used with lower heating value fuels.

46. The furnace of claim 45, wherein the hearth burners and wall burners are configured to interchangeably operate with higher heating value fuels and lower heating value fuels.