Duct burner diffuser

Information

  • Patent Grant
  • 6468073
  • Patent Number
    6,468,073
  • Date Filed
    Tuesday, June 12, 2001
    23 years ago
  • Date Issued
    Tuesday, October 22, 2002
    22 years ago
Abstract
A diffuser for a gas duct burner having a fuel pipe and a plurality of stabilizers includes a plate having first and second spaced apart ends defining a length, and first and second spaced apart sides defining a width. The plate has a first portion having a uniform width which is disposed adjacent to the stabilizer and a second portion having a variable width.
Description




TECHNICAL FIELD OF THE INVENTION




The present invention relates to combustion equipment and more particularly to an improved diffuser for a gas duct burner.




BACKGROUND OF THE INVENTION




In order to increase combustion in a duct burner downstream of a gas turbine, it is desirable to increase the mixing rate of the fuel and turbine exhaust gas (TEG) in order to stabilize the flame and create a low velocity zone. Enhanced combustion results in a decrease in the amount of carbon monoxide generation. Techniques have been utilized for improving combustion and lowering carbon monoxide generation through the use of stabilizers and diffusers. Stabilizers entrain fuel within an ignition zone, and diffusers create an obstruction in the flow stream to create a wake flow. However, enhanced downstream mixing rates and lower carbon monoxide generation is not sufficiently achieved by present designs.




A need has thus arisen for an improved diffuser for the generation of smaller and out of plane vortices to enhance the downstream mixing of fuel and TEG which also reduces carbon monoxide generation.




SUMMARY OF THE INVENTION




In accordance with the present invention, a diffuser for a gas duct burner having a fuel pipe and a plurality of stabilizers is provided. The diffuser includes a plate having first and second spaced apart ends defining a length, and first and second spaced apart sides defining a width. The plate has a first portion having a uniform width which is disposed adjacent to a stabilizer and a second portion having a variable width.











BRIEF DESCRIPTION OF THE DRAWINGS




For a more complete understanding of the present invention and for further advantages thereof, reference is now made to the following Description of the Preferred Embodiments taken in conjunction with the accompanying Drawings in which:





FIG. 1

is a top plan view of duct burner illustrating the present diffuser;





FIG. 2

is a side elevational view of the duct burner illustrated in

FIG. 1

showing the present diffuser;





FIG. 3

is a perspective view of a stabilizer shown in

FIG. 2

illustrating the present diffuser; and





FIGS. 4-6

illustrate the stabilizer of FIG.


2


and further embodiments of the present diffuser.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring simultaneously to

FIGS. 1 and 2

, a duct burner used with the present diffuser is illustrated, and is generally identified by the numeral


10


. Multiple duct burners


10


may be utililized in a combustion system, and are disposed downstream of a gas turbine generator producing a TEG stream and upstream of a steam generator. Duct burner


10


includes a fuel pipe


12


which receives fuel from a source (not shown) under control of control devices


14


. Disposed along fuel pipe


12


are multiple stabilizers


16


. Stabilizers


16


include a plurality of apertures


18


which are aligned with apertures (not shown) within fuel pipe


12


for allowing fuel to exit from fuel pipe


12


in the region surrounded by stabilizers


16


. Stabilizers


16


function to promote complete combustion of the gas exiting from fuel pipe


12


.




Referring now to

FIGS. 2 and 3

, an important aspect of the present invention is the use of diffusers


20


. Diffusers


20


extend outwardly from stabilizers


16


on both sides of fuel pipe


12


. Diffusers


20


in combination with stabilizers


16


function to mix gas and the TEG stream in order to stabilize the flame. Diffusers


20


generate smaller and out of plane vortices to enhance the downstream mixing as well as lower carbon monoxide generation. Increased vortex generation occurs between adjacent diffusers


20


to increase eddy flow in a plane orthogonal to the plane where mixing occurs caused by stabilizers


16


. Diffusers


20


increase the shielding of the initial combustion zone downstream from the TEG stream and increase the downstream mixing rate due to the out of plane vortices produced by the shape of diffusers


20


thereby lowering carbon monoxide generation.




Referring to

FIG. 3

, diffuser


20


includes a plate


22


. Plate


22


includes a first portion


24


and a second portion


26


. First portion


24


is attached to stabilizer


16


and has a uniform width between spaced apart sides


24




a


and


24




b


. Second portion


26


of diffuser


20


has a variable width extending between spaced apart sides


26




a


and


26




b


. Plate


22


has an overall length extending between ends


22




a


and


22




b


. It therefore can be seen that the width of plate


22


changes between ends


22




a


to end


22




b


from a uniform width to a variable width.

FIG. 3

illustrates diffuser


20


having a triangular shaped second portion


26


. Second portion


26


is generally configured as an equilateral triangle. First portion


24


and second portion


26


of plate


22


may be continuous in construction, and, alternatively, two separate portions


24


and


26


may be interconnected together to form plate


22


. Portion


24


of plate


22


includes a plurality of apertures


28


for increasing vortex flow.




Referring now to

FIG. 4

, stabilizer


16


is illustrated together with a further embodiment of the present diffuser, generally identified by the numeral


32


. Diffuser


32


includes a plate


34


having a first portion


36


and a second portion


38


. First portion


36


of plate


34


has a uniform width extending between sides


36




a


and


36




b


. Second portion


38


of plate


34


includes a variable width extending between sides


38




a


and


38




b


. Second portion


38


of plate


34


is similar in configuration to second portion


26


of plate


22


(FIG.


3


), but has a truncated triangular configuration. Diffuser


32


decreases in width from end


34




a


to end


34




b


. First portion


36


and second portion


38


of plate


34


may be fabricated from a continuous sheet of material or separately fabricated and subsequently interconnected.




Referring now to

FIG. 5

, a further embodiment of the present diffuser is illustrated, and is generally identified by the numeral


40


. Diffuser


40


includes a plate


42


having a general arcuate configuration. Plate


40


includes a first portion


44


and a second portion


42


. First portion


44


has a uniform width extending between sides


44




a


and


44




b


. Second portion


46


of plate


42


has a variable width extending between sides


46




a


and


46




b


. The overall length of plate


42


extending between ends


42




a


and


42




b


has a variable width. End


42




b


of plate


42


has an arcuate configuration.




First portion


44


and second portion


46


of plate


42


may be fabricated from a continuous sheet of material or separately fabricated and subsequently interconnected.




Referring now to

FIG. 6

, a further embodiment of the present diffuser is illustrated, and is generally identified by the numeral


50


. Diffuser


50


includes a plate


52


having a first portion


54


and a second portion


56


. First portion


54


has a uniform width extending between sides


54




a


and


54




b


. Second portion


56


has a variable width extending between side


56




a


and


56




b


. The width of second portion


56


increases in a direction outwardly of stabilizer


16


. The overall length of plate


52


extending between ends


52




a


and


52




b


is variable. Second portion


56


of plate


52


is configured in an inverted position from second portion


26


of plate


22


of diffuser


20


(FIG.


3


), and comprises an equilateral triangle having a base spaced apart from first portion


54


of plate


52


.




As can be seen, diffusers


20


,


32


,


40


, and


50


each have a portion of uniform width and a portion of variable width extending over the length of the diffuser. The portion of variable width creates an additional vortex to enhance downstream mixing, increase the shielding of the initial combustion zone from the TEG stream which results in lower carbon monoxide generation.




It therefore can be seen that the present invention provides for an improved diffuser which generates out of plane vortices to enhance downstream mixing in a duct burner. The present diffuser provides increased shielding, and coupled with the out of plane vortex generation, results in lower carbon monoxide generation.




Whereas the present invention has been described with respect to specific embodiments thereof, it will be understood that various changes and modifications will be suggested to one skilled in the art and it is intended to encompass such changes and modifications as fall within the scope of the appended claims.



Claims
  • 1. A diffuser for a gas duct burner having a fuel pipe and a stabilizer, the fuel pipe having a longitudinal axis, the diffuser comprising:a plate having first and second spaced apart ends defining a length and first and second spaced apart sides defining a width; said plate having a first portion adapted to be disposed adjacent to the stabilizer and having a uniform width; and said plate having a second portion having a variable width extending along said plate length, said plate second portion creating a vortex flow having an axis of rotation generally perpendicular to the pipe axis.
  • 2. The diffuser of claim 1 wherein said width of said second portion decreases from said first portion of said plate to said second end of said plate.
  • 3. The diffuser of claim 1 wherein said width of said second portion increases from said plate first portion to said second end of said plate.
  • 4. The diffuser of claim 1 wherein said second portion of said plate has a triangular shape.
  • 5. The diffuser of claim 1 wherein said second portion of said plate has a semicircular shape.
  • 6. A diffuser for a gas burner having a fuel pipe and a stabilizer, the fuel pipe having a longitudinal axis, the diffuser comprising:a first member having a first end adapted to be disposed adjacent to the stabilizer, said first member having a second end spaced apart from said first end, and first and second sides extending between said first and second ends, said first and second sides being spaced apart by a uniform distance; and a second member having a first end disposed adjacent to said second end of said first member and a second end spaced apart from said first end, and first and second sides extending between said first and second ends and being spaced apart by a variable distance between said first and second ends said members creating a vortex flow having an axis of rotation generally perpendicular to the pipe axis.
  • 7. The diffuser of claim 6 wherein the distance between said first and second sides of said second member decreases from said first end to said second end thereof.
  • 8. The diffuser of claim 6 wherein the distance between said first and second sides of said second member increases from said first end to said second end thereof.
  • 9. The diffuser of claim 6 wherein said second member has a shape of an equilateral triangle.
  • 10. The diffuser of claim 6 wherein said second member has a shape of a truncated triangle.
  • 11. The diffuser of claim 6 wherein said second member has a shape of a semicircle.
  • 12. A gas duct burner comprising:a fuel pipe having an axis; a plurality of stabilizers disposed along said fuel pipe, each of said stabilizers creating a vortex flow having an axis of rotation generally parallel to said fuel pipe axis; a plurality of diffusers, one of said plurality of diffusers being disposed adjacent to one of said plurality of stabilizers, each of said diffusers creating a vortex flow having an axis of rotation generally perpendicular to said fuel pipe axis; said diffusers each including a plate having first and second spaced apart ends defining a length and first and second spaced apart sides defining a width; said plate having a first portion disposed adjacent to said stabilizer and having a uniform width; and said plate having a second portion having a variable width extending along said plate length.
  • 13. The diffuser of claim 12 wherein said width of said second portion decreases from said first portion of said plate to said second end of said plate.
  • 14. The diffuser of claim 12 wherein said width of said second portion increases from said plate first portion to said second end of said plate.
  • 15. The diffuser of claim 12 wherein said second portion of said plate has a triangular shape.
  • 16. The diffuser of claim 12 wherein said second portion of said plate has a semicircular shape.
  • 17. A method for fuel mixing in a gas duct burner having a fuel pipe, the fuel pipe having an axis, a plurality of stabilizers disposed along the fuel pipe and a plurality of diffusers disposed adjacent to the plurality of stabilizers comprising:creating a vortex flow axis of rotation between adjacent ones of the plurality of diffusers in a plane generally perpendicular to a plane containing a vortex flow axis of rotation created by the stabilizers, the plane containing the vortex flow axis of rotation created by the stabilizers being generally parallel to the fuel pipe axis.
US Referenced Citations (5)
Number Name Date Kind
3044754 Skerkoske et al. Jul 1962 A
4737100 Schnell et al. Apr 1988 A
4767319 Vosper Aug 1988 A
5820365 Oppenberg et al. Oct 1998 A
6301875 Backlund Oct 2001 B1
Foreign Referenced Citations (1)
Number Date Country
89611 May 1985 JP
Non-Patent Literature Citations (2)
Entry
Drawing No. 395452-02, Rev. A Forney Corporation, Copyright 1998.
Drawing No. 389545-01, Rev. B Forney Corporation, Copyright 1995.