US 3700173 A
An improved diffuser for liquid fuel fired burners wherein the diffuser has a frusto-conical surface located in the combustion-supporting air path with widely spaced slots formed in the frusto-conical surface to divide the surface into several distinct frustums to direct combustion-supporting air into the fuel spray as independent streams for the complete mixing thereof. The tabs from which the slots are formed are bent forward at substantially an 80 DEG angle with respect to the frusto-conical surface to direct the air streams into the fuel spray in a tangential manner.
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Description (OCR text may contain errors)
United States Patent Ketchum, Jr.
14 1 Oct. 24, 1972 [541 DIFFUSER 3,367,385 2/1968 Dunn ..239/402.5  Inventor, ElmerKetchumJrPontiacMich 3,469,790 9/1969 Duncan, ..239/402.5
 Assignee: Combustion Engineering Inc., Windsor, Conn.
 Filed: Dec. 30, 1970  App1.N0.: 102,810
 U.S. Cl. ..239/405, 239/425.5, 239/498  Int. Cl. ..B05b 7/10  Field of Search ..239/4195, 422, 405, 402.5, 239/498, 425.5
 References Cited UNITED STATES PATENTS 2,976,919 3/1961 Sanborn .;.....239/49s x 2,840,152 6/1958 Reed ..239/498 2,901,032 8/1959 Brola ..239/405 X 3,211,207 10/1965 Luft "2319/4025 3,229,9l5' 1/1966 Yahnke ..239/405 Primary Examiner-Lloyd .L. King Attorney-Carlton F. Bryant, Stephen A. Schneeberger, Eldon H. Luther, Robert L. Olson, John F. Carney, Richard H. Berneike and Lawrence P. Kessler 57 ABSTRACT An improved diffuser for liquid fuel fired burners wherein 'the diffuser has a frusto-conical surface located in the combustion-supporting air path with widely spaced slots formed in the frusto-conical surface to divide the surface into several distinct frustums to direct combustion-supporting air into the fuel spray as independent streams for the complete mixing thereof. The tabs from which the slots are formed are bent forward at substantially an 80 angle with respect to the frusto-conical surface to direct the air streams into the fuel spray in a tangential manner.
I 7 Claims, 2 Drawing Figures PATENTEDUBT 24 I972 INVENTOR. ELMER KETCHUM, Jr. BY 4 g 5 1 DIFFUSER BACKGROUND OF THE INVENTION Fluid fuel fired burners of high capacity require proper mixing of combustion-supporting air and the liquid fuel in order to promote efficient burning. This proper mixing of fuel and combustion-supporting air must be accomplished over the full burner operating range for maximum burner efiiciency. Apparatus to accomplish a more complete mixing of fuel and air are continually being sought due to increasing desire of burner users to go to greater turn-down ratios. (wider range of fuel pressures).
Liquid fuel burners commonly have a nozzle generating a conical shaped spray of atomized fuel discharging through a burner port into a swirling stream of air. To improve the mixing action to facilitate rapid and complete combustion, diffusers have been provided in the air stream to direct a portion of the air into the fuel spray and to promote the swirling action thereof. The diffusers have generally been of conical configuration having narrow, slotted, radial deflecting vanes (such as shown in US. Pat. Nos. 1,434,406 and 2,669,296). With a multiplicity of uniform closely spaced openings of the diffuser, however, the combustion-supporting air will tend to reform into a homogeneous mass as it strikes the fuel spray so that efficient mixing over a wide burner operating range is not possible.
SUMMARY OF THE INVENTION It is the object of this invention to provide a novel diffuser which directs the combustion-supporting air so as to cause it to intersect atomized liquid fuel spray as independent streams to accomplish a more complete mixing thereof over a wider burner operating range. The diffuser has widely spaced slots formed in a frustoconical surface positioned in the path of the combustion-supporting air. The slots are positioned to divide the frusto-conical surface into. several distinct frustums. Slots of the outermost frustum V-shaped, while the slots of the inner frustums are substantially square The tabs from which the slots are formed are bent forward at substantially an 80 angle relative to the frusto-conical surface so as to direct the air from the frustums tangentially into the fuel spray as independent streams. I
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevation of the diffuser according to this invention in relation to a typical burner arrangement.
FIG. 2 is a side elevation of the diffuser along the line 2--2 of FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENT thereof so as to divide the surface 28 into a peripheral frustum made up of a series of interconnected square fins 32 (in this instanceQeight in number). The tab-like portion 34- from which the V-shaped slots 30 are formed are bent forwardly at an angle of substantially with respect to the surface 28.
. Located within the square fins 32 are square-shaped slot 36 having the tab-like portion 38 from which they are formed bent forwardly at an angle of substantially 80 with respect to the frusto-conical surface 28. The surface 28 also has a series of square slots 40 interspaced between the slots 36 and at a different radial distance thereon from that of the slots 36. The tab-like portions 42 from which each of the openings 40 is formed are also bent forward at an angle of substantially 80 with respect to the surface 28. The series of square-shaped slots 36 and the series of square-shaped slots 40 are located so as to effectively divide the frusto-conical surface 28 into distinct interior frustums,
the frustum containing the slots 36 overlapping the frustum containing the V-shaped notches 30.
The square shape of the slots 36 and 40 and their spacing about the frust'o-conical surface 28 of the diffuser 12 as well as the V-shaped slots 30 about the periphery thereof, and the distinct frustums effectively formed by the diflering radial positioning of the slots, results in the combustion-supporting air being difiused into individual flow streams. The tab-like portions 38, 42 and 34, respectively direct these air streams tangentially into the aspirated fluid fuel flow from the liquid fuel gun 24' as independent flow streams from the distinct frustums. As a results, better intermixing of the liquid fuel and combustion-supporting air is accomplished to promote more efficient burner. operation over a wider burner operating range. 7
While this preferred embodiment of the invention has been shown and described, it will be understood that it is merely illustrative and that changes may be made without departing from the scope of the invention as claimed.
What is claimed is: v
1. An improved diffuser for liquid fuel fired burners having liquid fuel admission means emitting fuel therefrom located in a combustion-supporting air stream, said diffuser comprising: a support means; a frusto-conical surface on said support means; at least a series of widely spaced slots adjacent the outer periphery of said frusto-conical surface; at least a series of widely spaced slots adjacent the inner periphery of said frusto-conical surface; and tabs extending from said slots adjacent said outer and inner peripheries of said frusto-conical surface, said tabs being bent forwardly of said slots whereby said combustion-supporting air stream is divided into a plurality of independent, distinct air streams directed into said fuel emitted from said liquid fuel emission means.
2. The apparatus of claim 1 wherein said support means is mounted with respect to said liquid fuel admission means of said burner so as to accurately position said diffuser relative to said liquid fuel admission means in the combustion-supporting air stream,
3. The apparatus of claim 2 wherein said support means is a sleeve which is-positioned so as to surround said liquid fuel admission means.
4. The apparatus of claim 3 wherein said slots adjacent to the outer periphery of said frusto-conical surface are of a V shape so as to divide said frusto-conical surface into a series of interconnected square fins.
5. The apparatus of claim 3 wherein said slots adjacent the inner periphery of said frusto-conical surface are of a substantially square shape.