US 3820944 A
Description (OCR text may contain errors)
United States Patent [191 Flournoy et al.
[111 3,820,944 June 28, 1974 OIL BURNER Inventors: Norman E. Flournoy; David A.
Morris, both of Richmond; Raymond Trippet, Highland Springs; Julian H. Dancy, Richmond, all of Va.
Assignee: Texaco Inc., New York, NY. Filed: Nov. 6, 1972 Appl. No.: 303,882
Related U.S. Application Data Continuation-impart of Ser. No. 104,043, Jan. 5, i971, abandoned.
U.S. Cl 431/265, 239/405, 431/183 Int. Cl. F23q 3/00 Field of Search 431/265, 181, 182, 183;
References Cited UNITED STATES PATENTS 2/1971 Walker et al. 43l/l83 Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-T. H. Whaley; C. G. Reis 5 7] ABSTRACT A gun type oil burner with a restriction plate in the barrel upstream of the nozzle and having annularly spaced orifices with swirl effecting flanges thereon to produce a rotational spin of air within the barrel. This vis combined with narrow peripheral orifice slots in the plate, radially outwardly of the first named orifices. The latter project a sheath of .air axially along the inner annular surface of the blast tube which surrounds the rotational swirl of air. Said swirling air mass is then constricted at the burner outlet, at which point atomized fuel is added to form a combustible mixture, which is immediately ignited.
6 Claims, 5 Drawing Figures PAIENTEBJUH28 B74 3; 2 0.94
sum 1 0r 2 XLIEKM PAIENIEDMZB m4 SHEET 2 8F 2 1 OIL BURNER The present is a Continuation-in-Part of an original 1 projects a conical pattern of finely atomized fuel particles into a highly turbulent flow of air which emanates from the end of an elongated blast tube or barrel.
More specifically, the present invention concerns a structural engagement for improving and facilitating the efficiency of combustion by forming a more combustible mixture. Innumerable expedients have been proposed for effecting combustion by producing an ideal intermixture of finely divided fuel particles in the stream of air. This demands for one thing, an extreme fineness of subdivision of the oil particles. It requires also however a high degree of turbulence of the air stream such that atomized fuel particles are instantaneously and uniformly distributed throughout the air stream. I
Similar developments along this line are disclosed and claimed in US. Pat. No. 3,694,136 and US. Pat.
No. 3,664,804. These constructions, along with that of the present invention, relate to what can be colloquially referred to as high head burner. In such a unit the air stream in the blast tube is highly restricted or throttled by a barrier which controlledly meters the stream of air to the burner tip. More importantly, such a structure enables its control and disposition in the form of predetermined jet streams which may be disposed and caused to cooperate to effect maximum turbulence and intermixing with the atomized fuel particles.
The present invention achieves this result in large measure by providing an elongated blasttube. The latter is so constructed that air flowing axially therethrough is passed under relatively high pressure through a series of weirs or apertures. The effect is to form a controlled, high velocityturbulence within the air stream emanating from the tip of the gun barrel or blast tube. 1
' More particularly, the present invention involves the provision of a series of rotationally or tangentially directed orifices for producing a high rotational spin of expanding air in the extremity or discharge end of the gun barrel. These rotationally directed orifices are annularly spaced and located radially outwardly from the central axis of the gun barrel. Further, they are spaced a predetermined distance inwardly from the rim or inner wall thereof. In combination therewith the invention provides an annularly spaced series of apertures or orifices disposed preferably in close proximity to the inner wall of the blast tube, and specifically between the inner wall of the blast tube and the rotationally directing orifices.
Therefore, the last named axially directed orifices direct streams of air exactly parallel to the axis of the blast tube, but essentially along the inner wall thereof.
Since the blast tube is preferably cylindrical in shape, the resulting axial streams provide a relatively high speed blast or jet of air which forms a sheath along the inner surfaces of the blast tube.
Because, moreover, this sheath is desirably relatively narrow in a radial direction it desirably occupies the entire surface of the cylindrical blast tube. The series 2 of orifices are preferably, therefore, in the form of elongated narrow slots.
Applicants do not desire to be bound by any statement of theory. In appears however that the combination of the relatively thin sheath of .high velocity air flowing axially along the surface of the blast tube, together with the spinning or rotational action of the intemal jets of air, facilitates general rotation and thus the high degree of turbulence at the extremity of the burner.
As described in certain of the aforementioned patents, the provision of a frusto conical tip on the extremity of the blast tube enables the rapidly rotating jets of air to be constricted through a relatively narrow orifice or choke. Thus, the effective rotational speed and turbulence are further increased. To this end the end cone of the burner tip tapers in a downstream direction to a restricted central opening, coaxial there with.
With the air stream now constricted and at maximum turbulence, an atomized fuel stream is introduced thereto at a point adjacent to the blast tube narrowed outlet. Simultaneously, the air/fuel mixture is ignited such that the resulting flame assumes a rapidly swirling, though expanding pattern.
Reference is now made to the figures of the drawing wherein one illustrative embodiment of the invention is disclosed in detail. In the drawing, FIG. I is an oblique view of the extremity of the blast tube of a gun type burner embodying the present invention, portions being broken away to show the internal structure as well as to symbolize the cooperation of the various air streams; FIG. 2 is a section taken centrally on the axis of the burner of FIG. 1; FIG. 3 is a transverse section taken on the line 3-3 of FIG. 2; FIG. 4 is a side elevation of the burner assembly and FIG. 5 is an end view thereof, facing the tip of the oil burner.
The present embodiment comprises a blast tube 10 which, as shown in FIGS. 4 and 5, projects from a plenum chamber 12, enclosing a typical rotary or squirrel cage type of fan (not shown) driyen by motor 14. Air flows into the interior of the fan from inlet chamber 16 via openings 18. The ignition controls are largely centered in the box 20 and the liquid fuel is handled by pump 22 and pipe 24.
The general function of the foregoing elements is conventional and thus is not describedin further detail, except to say that the fan is preferably provided with a substantially higher speed and correspondingly higher power drive, such as, for example, to double the speed of the blower. This is necessary, as will hereinafter more fully appear, to maintain flow through the various orifices, of a highly restrictive barrier or partition, to set up high velocity jets or streams of high kinetic energy air.
Referring now to FIGS. 1, 2 and 3, the internal structure comprises insulators 26 and electrodes 28, as well as a central, axial fuel pipe 30, which terminates in nozzle 32. These members are similarly conventional and, as before, the central pipe usually forms a supporting structure for the electrodes and insulators as shown by means of mounting bracket 51.
The latter, in turn, is supported by a partition plate or barrier 34. Said plate is circular in shape to fit the interior of the blast tube, and extends transversely thereacross as shown in FIGS. 1 and 2. Plate 34 is attached to the mounting bracket through a spacer block 52 with screws 53.
Inasmuch as the plate 34 is apertured to receive the fuel tube 30 and the cylindrical insulators 26, these are likewise supported near the extremity of said blast tube. Likewise the entire assembly can be withdrawn from the rear of the blast tube in known manner as de sired.
The main bulk of the air flow through the blast tube is directed through H-shaped apertures 36. Actually, as is more apparent from FIG. 1, these apertures 36 have an effective opening considerably larger than might seem from elevation as viewed in FIG. 3. They are, however, as indicated in FIG. 3, rectangular in shape with the long margins arranged in a general tangential or annular direction. The apertures transverse margins are disposed in an approximate radial direction with respect to the axis of the. blast tube.
The last named or so-called margins of apertures 36 are provided with flanges or swirl vanes which are deformed or pressed out on opposite sides of plate 34 as at 38 and 40 respectively. These flanges both extend in an annular and axial direction with respect to the blast tube and make'approximately the same angle with the plane of plate 34. The result is to direct the high pressure air streams issuing from the upstream side of plate 34, at a high velocity and, at the same time, in a spiral or swirling direction. Inasmuch as tab or flange 40 is pressed downstream, and the inner flange 38 extends in an upstream direction, the net result is a rapidly swirling flow of air through the respective jets, which air flows in a counter-clockwise direction as viewed in FIG. 1.
FIG. 1 illustrates more or less diagrammatically how an air jet streams from one of the several major orifices to form a continuous high speed swirl.
It is also important to note that the construction of the present orifices has a high element of economic attractiveness in view of the fact that the I-I-shaped orifices can be formed by the least expensive sort of stamping operation.
Referring to the aforementioned sheath of air which flows axially along the interior cylindrical wall of the blast tube, attention is directed to the slotted orifices 42. The latter, as will be noted, are relatively narrow, elongated slots arranged in annularly spaced relationship. Obviously they could be arranged in a curved, annular path, for the present purposes; however this has not been found to be necessary. The desired result is realized by the normal tendency of the flat jets of air to follow the curved wall of the blast tube and to expand circumferentially therealong. The overall effect is to create what amounts to a more or less continuous sheath or film of axially flowing air under considerable kinetic force. Further said continuous sheath embraces and encloses the aforementioned rotational spiralling streams of air.
Finally, the combined air drafts strike the inner surface of the frusto conical burner tip designated generally as at 46. Said tip is characterized by an interior frusto conical wall 48 extending substantially inwardly in a radial direction and at the same time, downstream in an axial direction. The tip terminates in central aperture or constriction 50. Therefore, the axially flowing blast of air is turned or deflected inwardly by the surface 48 without being materially impeded or reduced in velocity. It finally emanates as a highly turbulent, spiralling mass from aperture 50.
Therefore, in operation, a high pressure mass of air in the chamber just upstream of the partition plate 34 blasts through H-shaped apertures 36. Said apertures initiate a main central flow of air with a high degree of rotational spin which represents considerable kinetic energy. Simultaneously a flat, narrow sheath of air flowing axially fromapertures 42 sheathes the interior wall of the blast tube.
While it is not desired herein to be bound by a statement of theory, it appears that the sheath of axially flowing gas at the wall, in effect, facilitates the high velocity spinning action of the central flow. In essence, the swirling stream is segregated from the frictional resistance inherent in rotational flow across the interior surface of the blast tube. Thus, in effect, suspended in a somewhat friction free environment the spinning action is greatly enhanced. Also the movement of the spinning mass in an axially downstream direction is obviously promoted by the rapidly moving axial jet stream forming the surface sheath.
To shape the burner flame pattern to fit relatively long cylindrical combustion chambers, central orifices 54 are added whereby to lengthen the spiral of the air flow pattern.
In any event, the constriction of the choke or orifice formed by the frusto conical tip of the burner finally merges the entire series of streams into an even more rapidly rotating mass of highly turbulent air. Into said mass the atomized liquid fuel spray from the nozzle 32 is projected in a generally conical stream whereby to be efficiently mixed therewith.
Irrespective the theoretical considerations involved, the net result has been found to be a substantial improvement in the combustion which follows intermixing of fuel to define the combustible mixture.
The following example tends to illustrate the effect of the present invention as applied to a standard burner. In accordance with the investigation, said standard burner was first subjected to testing, and was thereafter modified in accordance with the present invention. The tests were then repeated.
The modifications consisted exclusively in removing the swirl producing vanes of the original burner and substituting the partition member precisely as disclosed in the figures of the present drawing. A further change was the substitution of a 3,450 RPM drive motor, for the 1,725 RPM drive motor, to maintain the plenum pressure necessary to permit orifice flow sufficient to reach comparable air-fuel ratios.
The air plate or barrier used in the present embodiment had a 4 inch diameter, thus enabling it to fit the interior wall of the cylindrical blast tube. The H- apertures were sized, in the plane of the plate with dimensions of /8 inches by inches. The peripheral slots were as shown, eight in number, having a width of l/ 1 6 inch, and were approximately /2 inches long in a peripheral direction.
Following are the results of the comparative smoke number tests on the two burners wherein A represents the Paragon burner as received and B the modified burner as above:
Smoke Number Excess AirPercentage A 4 21 A O 43 B 0 I4 We claim:
1. In a gun type burner having an elongated cylindrical walled blast tube, including opposed upstream and outlet ends, and being communicated at said upstream end with a source of air, said blast tube being adapted to form a swirling air stream prior to intermixing into said stream of a liquid fuel, whereby to provide a combustible mixture comprising highly atomized fuel particles and air, and means at the outlet end of said blast tube for igniting the swirling combustible mixture, and a fuel nozzle positioned substantially coaxially of said blast tube, being communicated with a source of liquid fuel and having a fuel discharge port disposed adjacent to said blast outlet tube outlet end,
an air plate disposed transversely of said blast tube at the upstream end thereof forming a partition thereacross,
said air plate having at least one air flow directing aperture spaced radially outwardly from the central axis of said blast tube, but inwardly from said tube cylindrical wall, said aperture having radial margins provided with air swirl effecting flanges projecting therefrom, and including vanes arranged in the same swirl producing direction whereby to form air passing therethrough into high velocity streams rotating toward said tube outlet, relatively narrow orifice slots formed in said air plate positioned between said at least one air flow directing aperture and said blast tube wall, said orifice slots being relatively narrow in a radial direction but'elongated in an annular direction,
said narrow orifice slots being annularly spaced to form a high velocity blast of air along the inner cylindrical wall of said blast tube, thereby defining a circumferential sheath about said swirling air stream,
the downstream end of said blast tube including a constricted opening having a lesser diameter than the diameter of said blast tube, and being further defined by an end wall extending inwardly from said tube inner wall, whereby to choke the combined air streams prior to addition of fuel thereto for forming a combustible mixture.
2. In an apparatus as defined in claim 1, wherein said constricted opening in said blast tube end is disposed substantially concentric with said tube.
3. In an apparatus as defined in claim 1, wherein said constricted opening in said blast tube end includes a conical wall extending outwardly toward and connected with said tube inner wall.
4. In an apparatus as defined in claim 1, wherein said fuel nozzle discharge port is positioned intermediate said constricted opening and said air plate.
5. In an apparatus as defined in claim 1, including air orifice means disposed inwardly of said orifice slots to direct air coaxially of said blast tube inwardly of said swirling air stream.
6. In an apparatus as defined in claim 1, wherein said at least one air flow directing aperture in said plate comprises a plurality of said apertures disposed about i said plate to form a plurality of high velocity streams rotating in a common direction.