Method and apparatus of gas-coal combustion in steam boilers

• US 4,572,084 A
• Filed: 06/02/1983
• Issued: 02/25/1986
• Est. Priority Date: 09/28/1981
• Status: Expired due to Fees

• Current Assignee: University of Florida (State University System of Florida)
• Original Assignee: University of Florida (State University System of Florida)
• Inventors: Green, Alex E. S., Green, Bruce A. S.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/500,394
• Time in Patent Office: 999 Days
• Field of Search: 110/260, 110/261, 110/262, 110/263, 110/264, 110/265, 110/266, 110/347, 431/4, 431/9, 431/182, 431/185, 431/187, 431/173, 431/284, 239/400, 239/406, 239/478, 239/479
• US Class Current: 110/261
• CPC Class Codes: F23C 1/12 gaseous and pulverulent fuel
• CPC Class Codes: F23D 17/005 gaseous or pulverulent fuel

Abstract

Various embodiments of apparatus and methods are disclosed for the conversion of steam boilers from being oil fired to coal and natural gas fired without adversely affecting the normal power density of the boilers or the emission pollution therefrom. In some cases even the resultant coal ash can be modified by injecting a powdered catalyst or phosphate slimes into the flame to produce a fertilizer ash having desirable minerals to enhance the economic value thereof.

Basically all embodiments include a swirling coal-air mixture directed along a path to form a sheath and a swirling gas-air mixture internally thereof with the swirling of the latter being in the same direction and fortifying the motion of the former. A gas-air mixture, swirling or non-swirling, may be supplied outwardly of such sheath to enhance the more complete burning of the coal-air mixture.

Claims

1. In a combustion device for burning a powdered coal-fluid mixture comprising a combustion chamber, first nozzle means communicating with said chamber for spirally swirling said coal-fluid mixture along a path in said chamber to form a hollow sheath of coal-fluid mixture, second nozzle means communicating with said chamber and located generally centrally of said hollow sheath for spirally swirling combustible gas-air mixture in said chamber and within said sheath of coal-fluid mixture in the same direction of swirl to reinforce the swirling motion of said coal-fluid mixture forming said sheath without general mixing therebetween and to promote volatilization and enhance the combustion of said coal-fluid mixture, means for burning said coal-fluid mixture and said gas-air mixture within said chamber, first supply means fluidly communicating with said first nozzle means for providing coal-fluid mixture to said first nozzle means and said chamber, second supply means fluidly communicating with said second nozzle means for providing gas-air mixture to said chamber, said second nozzle means including an elongated insert having upstream and downstream end portions, said downstream end portion of said insert being adjacent said second supply means, a plurality of spaced generally spiral channels in the outer surface of said insert extending from said upstream end portion and terminating in said downstream end portion, said channels communicating between said second supply means and said chamber for spirally swirling said gas-air mixture prior to egressing from said second supply means into said chamber.

2. In a combustion device in accord with claim 1 wherein said coal-fluid mixture is a coal-water slurry.

3. In a combustion device in accord with claim 1 wherein said means for burning said coal fluid mixture is located outwardly of said sheath and includes means for supplying gas-air mixture about said coal-fluid sheath whereby said coal-fluid sheath is more completely combusted.

4. In a combustion device in accord with claim 1 wherein said coal-fluid mixture is a coal-air mixture.

5. In a combustion device in accord with claim 1 wherein said means for burning said coal-fluid mixture is located outwardly of said sheath and includes a chamber into which the coal-fluid mixture is swirled during injection thereof and the path of said coal-fluid mixture is spiraled downwardly so that the coal ash particles may be separated and only fuel rich combustion products from said coal-fluid mixture and gas-air mixture are fed to a boiler or the like.

6. In a combustion device in accord with claim 1 wherein said combustion chamber is elongated and generally disposed vertically, said first and second nozzle means being disposed in the upper portion of said chamber.

7. In a combustion device in accord with claim 1 wherein said combustion chamber is elongated and generally disposed vertically, one said first and second nozzle means being disposed in one of the upper and lower portions of said chamber and the other first and second nozzle means being disposed in the other of said upper and lower portions of said chamber.

8. In a combustion device in accord with claim 1 wherein said first nozzle means includes a first elongated passageway having a longitudinal axis and another elongated insert disposed in said first passageway with its longitudinal axis being substantially aligned with said first passageway longitudinal axis, said second nozzle means including a second elongated passageway having a longitudinal axis, said elongated insert being disposed in said second passageway with its longitudinal axis substantially aligned with said second passageway longitudinal axis.

9. In a combustion device in accord with claim 8 wherein said second passageway and elongated insert are located generally centrally of said other elongated insert and spaced inwardly of said outer surface thereof.

10. In a combustion device in accord with claim 9 wherein said means for burning said coal-fluid mixture is located outwardly of said sheath and includes means for supplying combustible gas-air mixture whereby gas-air is external and internal of said sheath.

11. In a combustion device in accord with claim 1 wherein said device includes a pre-combustion chamber, said first nozzle means injecting said coal-fluid mixture generally tangentially into said chamber to form said hollow sheath, said device further comprising a passageway having an inlet opening communicating with said pre-combustion chamber and an exit opening with a boiler or the like for passing fuel rich combustion products from said chamber into a boiler, said second nozzle means and said inlet opening of said passageway being generally in alignment and said sheath of coal-fluid mixture generally surrounding said second nozzle means and said inlet opening.

12. In a combustion device in accord with claim 11 wherein said first nozzle means includes a plurality of spaced injectors extending into the upper portion of said chamber.

13. In a combustion device in accord with claim 11 further comprising means for injecting chemical additives into said chamber thereby scrubbing the combustion products therein to reduce the SO₂ emissions.

14. In a combustion device in accord with claim 11 wherein said first nozzle means is located adjacent the upper portion of said chamber, said second nozzle means being located adjacent the lower portion of said chamber, and said inlet of said passageway being located between said first and second nozzle means.

15. In a combustion device in accord with claim 11 wherein said first nozzle means is located adjacent the upper portion of said chamber, and second nozzle means also being located in said chamber upper portion, said inlet of said passageway being located in the lower portion of said chamber.

16. In a combustion device in accord with claim 1 wherein said combustion chamber is elongated and disposed generally vertically, said first nozzle means being adjacent the upper portion of said chamber for delivering said coal-fluid mixture into said chamber so that the coal ash particles burned from said coal-fluid mixture fall toward the lower portion of said chamber for disposal.

17. In a combustion device in accord with claim 16 further comprising means adjacent said lower portion of said chamber to receive and dispose outwardly of said chamber said coal ash particles.

18. In a combustion device in accord with claim 16 further comprising means communicating with said chamber for passing fuel rich combustion products from said coal-fluid mixture and gas-air mixture outwardly of said chamber and being adapted to be fed to a boiler or the like.

19. In a combustion device in accord with claim 18 wherein said coal-fluid mixture is a coal-air mixture.

20. In a combustion device in accord with claim 18 wherein said coal-fluid mixture is a coal-water slurry.

21. In a combustion device for burning a powdered coal-fluid mixture comprising an elongated generally vertical combustion chamber, first nozzle means communicating with said chamber adjacent the upper portion thereof for substantially tangentially introducing adjacent the inside wall of said chamber a swirling motion to said coal-fluid mixture along a downward path in said chamber to form a hollow sheath of coal-fluid mixture, second nozzle means communicating with said chamber and generally centrally of said hollow sheath for swirling a combustible gas-air mixture within said sheath in the same direction of swirl of said sheath to reinforce the swirling motion thereof and to promote volatilization and enhance the combustion of said coal-fluid mixture, means within said chamber for burning said coal-fluid mixture and said gas-air mixture within said chamber to produce fuel rich combustion products and coal ash particles, means adjacent the lower portion of said chamber to receive and dispose outwardly of said chamber the coal ash particles burned from said coal-fluid mixture, means communicating with said chamber for passing fuel rich combustion products from said coal-fluid mixture and gas-air mixture outwardly of said chamber, the fuel rich combustion products being adapted to be fed to a boiler or the like, said second nozzle means including an elongated insert having upstream and downstream end portions, said downstream end portion of said insert being adjacent a supply of said gas-air mixture, a plurality of spaced generally spiral channels in the outer surface of said insert extending from said upstream end portion and terminating at said downstream end portion, said channels communicating between a supply of said gas-air mixture and said chamber for spirally swirling said gas-air mixture prior to egressing from a supply into said chamber within said hollow sheath of said coal-fluid mixture to reinforce the swirling motion thereto and to promote volatilization and enhance the combustion of said coal-fluid mixture.

22. In a combustion device in accord with claim 21 wherein said coal-fluid mixture is a coal-water slurry.

23. In a combustion device in accord with claim 21 wherein said coal-fluid mixture is a coal-air mixture.

24. In a combustion device for burning a powdered coal-air mixture comprising first nozzle means for spirally swirling said coal-air mixture along a path to form a hollow sheath of coal-air mixture, second nozzle means located generally centrally of said hollow sheath for spirally swirling combustible gas-air mixture within said sheath to enhance the combustion of said coal-air mixture, ignition means outwardly of said sheath to burn said coal-air mixture, said ignition means including an annular ignition ring chamber having an annular opening communicating with said first nozzle means, manifold means fluidly communicating with said ignition ring chamber for providing gas-air mixture to said chamber, said first nozzle means including an elongated insert having upstream and downstream end portions and a concentric annular nozzle therearound, said upstream end portion of said insert being adjacent said concentric annular nozzle, a plurality of spaced generally spiral channels in the outer surface of said insert extending from said upstream end portion and terminating at said downstream end portion, said channels communicating between a supply of said coal-air mixture and said concentric annular nozzle for spirally swirling said coal-air mixture prior to egressing from said supply.

25. In a combustion device for burning a powdered coal-fluid mixture having nozzle means for delivery of said coal-fluid mixture including an elongated converging central nozzle and at least one concentric annular nozzle spaced forwardly of the smaller end of said converging central nozzle, ignition ring means associated with said nozzle means including an annular ignition ring chamber having an annular opening communicating with said nozzle means, manifold means fluidly communicating with said ignition ring chamber for providing combustible gas-air mixture to said chamber, the improvement comprising an elongated insert having upstream and downstream end portions, said downstream end portion being adjacent said central nozzle, a plurality of spaced generally spiral channels in the outer surface of said insert extending from said upstream end portion and terminating at said downstream end portion, said elongated insert being located and said channels communicating between a supply of said coal-fluid mixture and said converging central nozzle for spirally swirling said coal-fluid mixture prior to egressing into said converging central nozzle and from said central nozzle whereby a hollow sheath of said coal-fluid mixture is emitted from said central nozzle into said annular ignition ring chamber, said hollow sheath of said coal-fluid mixture being enveloped by said gas-air mixture from said annular ignition ring chamber without any general mixing between said gas-air mixture and said coal-fluid mixture while promoting volatilization and enhancing the generally complete combustion of said coal-air mixture.

26. In a combustion device in accord with claim 25 further comprising a manifold means adjacent said annular nozzle and having a plurality of spaced orifices for injecting chemical additives into the flame thereby scrubbing the flame and its combustion products.

27. In a combustion device in accord with claim 25 wherein said insert has a predetermined cross-section adjacent said upstream end portion, said insert further including a tapered outer wall from said predetermined cross-section to a lesser cross-section at the most downstream end thereof.

28. In a combustion device in accord with claim 27 further including terminating ends of said channels spacedly of said most downstream end of said insert.

29. In a combustion device in accord with claim 25 wherein said insert includes an outlet disposed in the end of said downstream end portion, a passageway communicating between said outlet and a supply of gas-air mixture for delivering a central core of said gas-air mixture centrally within said hollow sheath of said coal-fluid mixture to enhance the combustion thereof in said annular ignition chamber.

30. In a combustion device in accord with claim 29 further comprising a manifold means adjacent said annular nozzle for injecting chemical additives into the flame thereby scrubbing said flame and its combustion products.

31. In a combustion device in accord with claim 30 further comprising a plug having a plurality of spaced and spiral channels in the outer surface thereof and positioned in said passageway whereby said gas-air mixture being injected centrally of said hollow sheath is spirally swirling.

32. In the combustion device in accord with claim 31 wherein said spirally swirling gas-air mixture reinforces the motion of said spirally swirling sheath of coal-fluid mixture.

33. In a combustion device in accord with claim 25 further comprising means for delivering a central core of said gas-air mixture centrally within said hollow sheath of said coal-fluid mixture without any general mixing between said gas-air mixture and said coal-fluid mixture to more completely combust said coal-fluid mixture.

34. In a combustion device in accord with claim 33 further comprising a plug having a plurality of spaced and spiral channels in the outer surface thereof and positioned between a supply of gas-air mixture and said convering central nozzle whereby said gas-air mixture being injected centrally of said hollow sheath is spirally swirling.

35. In a combustion device in accord with claim 34 wherein said channels of said insert and plug are directed in a predetermined direction whereby said spirally swirling gas-air mixture reinforces the motion of said spirally swirling sheath of coal-fluid mixture.

36. In a combustion device in accord with claim 33 further comprising a manifold adjacent said annular nozzle for injecting chemical additives into the flame thereby scrubbing the flame and its combustion products.

37. In a combustion device in accord with claim 36 further comprising a plug having a plurality of spaced and spiral channels in the outer surface thereof and positioned between a supply of gas-air mixture and said converging central nozzle whereby said gas-air mixture being injected centrally of said hollow sheath is spirally swirling.

38. In a combustion device in accord with claim 37 wherein said channels of said insert and plug are directed in a predetermined direction whereby said spirally swirling gas-air mixture reinforces the motion of said spirally swirling sheath of coal-fluid mixture.

39. In a combustion device in accord with claim 25 further comprising a plug having a plurality of spaced and spiral channels in the outer surface thereof and positioned between a supply of gas-air mixture and said converging central nozzle, whereby said gas-air mixture being injected centrally of said hollow sheath is spirally swirling.

40. In a combustion device in accord with claim 39 wherein said channels of said insert and plug are directed in a predetermined direction whereby said spirally swirling gas-air mixture reinforces the motion of said spirally swirling sheath of coal-fluid mixture.

41. In a combustion device for burning a powdered coal-air mixture comprising a combustion chamber, first nozzle means for spirally swirling said coal-air mixture along a path in said chamber to form a hollow sheath of coal-air mixture, second nozzle means located generally centrally of said hollow sheath for spirally swirling combustible gas-air mixture in said chamber and within said sheath in the same direction of swirl to reinforce the swirling motion of said sheath and to promote volatilization and enhance the combustion of said coal-air mixture, ignition means for burning said coal-air mixture and said gas-air mixture within said chamber, supply means fluidly communicating with said first nozzle means for providing coal-air mixture to said chamber, manifold means fluidly communicating with said second nozzle means for providing said gas-air mixture to said chamber, said first nozzle means including an elongated insert having upstream and downstream end portions, said downstream end portion of said insert being adjacent said supply means, a plurality of spaced generally spiral channels in the outer surface of said insert extending from said upstream end portion and terminating in said downstream end portion, said channels communicating between said supply and said chamber for spirally swirling said coal-air mixture prior to egressing from said supply means into said chamber.