US 3694136 A
Description (OCR text may contain errors)
United States Patent Flournoy et al.
[ OIL BURNER  Inventors: Norman E. Flournoy; Julian l-l. Dancy, both of Richmond; Raymond Trippet, Highland Springs, all of Va.
 Assignee: Texaco Inc.
 Filed: Oct. 5, 1970  Appl. No.: 78,069
521 u.s.c1 ..431/265,43l/l82  Int. Cl ..F23q 3/00 58 Field of Search ..431/1s1, 182, 183, 185,265;
 References Cited UNITED STATES PATENTS De Lanceym, 431/265 X [451 Sept. 26, 1972 3,143,159 8/1964 Smithson ..43l/265X PrimaryExaminer-Edward G. Favors Attorney-Thomas H. Whaley, Carl G. Reis and L. H. Phelps, Jr.
[5 7] ABSTRACT A gun type oil burner having a metering plate with adjustable orifices arranged between the burner tip and the burner fan in which the adjustable orifices are peripherally disposed along the inner surface of the blast tube and are axially lined with radial and spirally arranged channels on the inside of the frusto conical tip of the burner.
4 Claims, 7 Drawing Figures PATENTED 1972 3,694,136
. SHEET 1 [1F 3 PATENTED E I972 3.694.136
sum 2 OF 3 FIG. 2
on. BURNER The present invention relates to an oil burner and more specifically to a burner of the so-called gun type wherein a spray nozzle for liquid fuel projects a conical pattern of finely atomized fuel particles into a highly turbulent flow of air emanating from a blast tube.
More specifically, the invention concerns a structural arrangement for improving and facilitating the efficiency of combustion. Hitherto innumerable expedients have been proposed for effecting combustion. In general, these have sought to produce the ideal intermixture of finely divided liquid fuel particles in a stream of air. This demands not only an extreme fineness of subdivision of the oil particles but a high degree of turbulence or intermixing, such that the particles are uniformly and fully distributed throughout the oxygen stream.
The present invention achieves this effect in large measure by providing a blast tube in which the air draft flowing axially therethrough is subdivided into annularly spaced, separate metered columns of air just inside the inner surface of the blast tube. Preferably the columns are formed by passing the air through orifices or jets from a higher into a lower pressure zone in order to form directed air jets. These segregated and metered streams of air are, in effect, jets, and they are directed into separate channels formed on the inner face of the frusto-conical choke at the end of the blast tube.
To do this, the extremity of the blast tube is provided with an end cone tapering in a downstream direction, and having a restricted central opening coaxial with the blast tube. The inner surface, however, is formed with a series of spirally arranged channels so that the air impacting the channels is rotated spirally about the axis of the blast tube as it moves outwardly through the orifice in the end cone. Also, each channel independently receives one of the air columns. The net result is high turbulence in the area of the liquid fuel spray and, accordingly, improved and more efficient combustion.
Referring now to the figures of the drawing wherein the one illustrated embodiment of the invention is disclosed in detail,
FIG. 1 is an oblique view of the blast tube of a gun type burner embodying the present invention, portions being broken away to show the internal structure,
FIG. 2 is a diametrical section taken on the axis of the burner of FIG. 1,
FIG. 3 is a transverse section thereof taken on the line 3-3 ofFIG. 2,
FIG. 4 is a section taken on the line 4--4 of FIG. 2,
FIG. 5 is similar to FIG. 4 of a modified construction, and
FIGS. 6 and 7 are elevations of two plates which make up the adjustable orifice arrangement of FIG. 5.
The embodiment shown comprises a blast tube 10 excluding the conventional remainder of the gun type burner assembly, such as,-for example, the blower motor, ignition control, pumps, etc., which are familiar to those skilled in the art. Nevertheless, it is to be understood that the blast tube projects from a burner of typical construction which is supplied from its right hand extremity with a pressurized flow of air from a suitable high pressure fan or blower not shown. Similarly, liquid fuel is supplied thru a central coaxial conduit I2 supported by frame 14, as indicated, and
bearing at its left hand extremity a nozzle. 16. The frame also carries insulators l8 and electrodes 20 for initiating combustion. The entire internal structure of nozzle and ignition electrodes is, in turn, located and supported in the blast tube by an air plate assembly.
The air plate assembly, which forms an important part of the present invention, comprises an inner air plate 22 which is shown in somewhat greater detail in FIGS. 2 and 4 to which is attached an outer control plate 24 which is held flatwise thereon by machine screws 26 shown in FIG. 4. Both of the plates are circular, with a peripheral diameter approximately equal to that of the interior diameter of the tube 10 so that they may fit snugly therein and can be slid into position axially from the rear end of the gun barrel in the usual way.
The details of the air plate assembly, as shown more clearly in FIGS. 2-4 are characterized by peripheral, annularly spaced recesses 28 cut into the periphery of air plate 22. In the specific embodiment disclosed, the recesses 28 comprise U" shaped grooves which face radially outward of the circular disc 22 and are equally spaced along its periphery. Therefore, annularly spaced columns of air under pressure are released through these recesses along the inner surface of the burner tube 10 in an axial direction. So thatthe quantity of air passing through, as well as, the form of the columns or jets of air can be varied, the control plate 24 is also provided with peripheral recesses or apertures'of identical shape and configuration. As a result, by rotating the cover plate or disc 24 with respect to the disc 22, the form and area of the vertical apertures may be selectively varied in accordance with a predetermined pattern. Rotational adjustment of the two plates is enabled by fasteners 26 previously mentioned which threadedly engage the plate 22 and pass thru suitable slots 30 in the cover plate 24.
The plate assembly, as previously intimated, is also apertured to receive the ignition insulators l8 and the fuel tube 12 of the burner nozzle 16. For example, suitable elongated apertures 32 about the insulators l8 permit relative adjustment of the two plates. Thus the operator, by known ways, simply by loosening fasteners 26 can rotate the two plates 22 and 24 with respect to one another to select the appropriate air through the end cone. This, in substance, provides a series of annularly spaced, adjustable jet orifices which, combined with a substantial air pressure on the upstream side of the orifice plate, discharges spaced columnar jets of air. Also, a few additional annularly spaced apertures 34 are provided to supply a necessary fraction of air through to the central part of the tube and about the nozzle 16 for blowing the ignition spark and cooling the nozzle.
Referring now to the end cone or air nozzle, this comprises a frusto-conical member 36 which engages the downstream extremity or tip of the blast tube of the burner as at 38 and is provided with a central aperture of substantially lesser diameter than that of the burner tube.
FIGS. S-7 show an alternate design of the air plate which is effective at low flow rates. The air passages 42 and 44 are smaller and their adjustment is less critical.
As previously mentioned, the choke or end cone is frusto-conical in shape and tapered inwardly in a downstream direction to facilitate the outward flow of a compact jet stream of turbulent air.
The inner surface of the end cone is provided, as previously stated, with a series of radial, and at the same time, spirally directed channels on its inner surface. This is effected by plates or dividers 40 which project from the. inner surface of the end cone in an inwardly extending axial direction, at the same time extending from a point at the inner surface of said tube barrel, radially inwardly therefrom, but at an acute angle to the radius of the barrel. V
Stated in another way, the several plates 40 each are arranged to direct the air impinging therebetween in a conical plane toward the axis of the barrel and the extremity of the air cone but at a slight angle to the true radius of the cone. Since each of the channels thus formed makes a similar angle with its radius, the various streams of air released by the channels, therefore, are all spiralled in essentially the same rotational direction. Moreover,- since the mass of air flow is directed a substantial distance radially inwardly, its rate of flow is correspondingly increased so that it leaves the frusto-conical end of the burner tip as a whirling jet in a high state of turbulence.
An important feature of the present invention, as indicated more or less diagrammatically in FIG. 1, is the location of the air plate assembly so thatthe separate and individual, annularly spaced columns of air each impinge directly and separately into the central portion of one of the-channels on the inner face of the end cone.
While applicant does not wish to be bound by a statement of theory it is felt that the provision of separate jets of air projected into-the spirally arranged channels of the burner tip provides a novel and effective way of maintaining .a high efficiency transition of the air flow into a highly turbulated, spirally flowing draft of air downstream of the end cone. Thetotal air flow is thus given a more turbulent motion by this method than by methods of other oil burners.
In point of fact, tests have shown that this design affords excellent flame shape and uniform temperature distribution throughout the combustion chamber. The following table gives a comparison between the conventional commercial burner (A) using an end cone and an internal air deflector, and a burner modified in accordance with the present invention by substituting the air plate assembly and end cone as called for herein (B). Also, in order to permit operation with the restriction introduced by the air plate, burner (B) was further modified by driving the air fan at 3,450 RPM as against a 1,725 RPM rotational speed of the fan in burner (A).
EXCESS AlR PERCENTAGE SMOKE NO. A 18 3.6 B l9 0 Also, inaccordance with-the present invention, by maintaining a substantial pressure, as, for example, 2.0 inches of H 0, upstream of the air plate, the burner inherently overcomes heavy pulsations which are common in many installations of the conventional commercial burners. It is believed, although applicant does not wish to be bound by this statement of theory, that the high pressures form a base area, highly resistant to pulsation.
Stated, therefore, in another way, the combination of adjustable jet orifice plate, with the substantial upstream air pressure necessary to drive columnar jets of air thru the plate has a multiple function of both resisting burner pulsation, and, in combination with registering spiral channels in the burner tip, effecting improved combustion.
We claim: 1
Lin a gun type oil burner having' 'a gun barrel or 'blast tube supplied with a blast of air under substantial pressure, a fuel nozzle coaxially arranged in the vicinity of the downstream extremity of said gun barrel and supplied with liquid fuel to form a predetermined pattern of highly atomized fuel particles and means for igv niting said fuel, the improvement which comprises a circular air plate assembly transversely occupying the interior of said blast tube upstream of said nozzle, and provided with a plurality of annularly spaced orifices arranged adjacent to the periphery thereof, said peripheral orifices being adjustable for metering and controlling air flow therethrough,
said air pressure in said blast tube being sufficient to provide a series of annularly spaced, independent, axially flowing jet columns of pressured air through said orifices and along the inner wall of said blast tube,
the end of said gun barrel comprising a frusto-conical member inclined in a downstream direction and having a coaxial, restricted central aperture on the inner surface of said frusto-conical member, and having separate, annularly spaced channels extending from the inner wall of said gun barrel to said central aperture and in a frusto-conical direction and at an acute angle to the radius thereof in corresponding directions to cause said air to flow in a spiral direction through the extremity of said burner tip,
' said radial channels in the end cone and said air plate assembly being so arranged that the said independent columns of air formed by said air plate assembly, impinge the central portion of each of said channels.
2. A gun type burner as called for in claim 1 wherein said circular air plate assembly comprises a plurality of coaxially arranged plates havingannular, peripherally spaced orifices adapted to register in one angular position thereof, and
means for rotationally adjusting said plates relative to one another, such as to enable predetermined restriction of the effective opening of said orifices.
3. A gun type oil burner as defined in claim 1 wherein the annularly spaced orifices adjacent to the periphery. of said circular air plate assembly comprise radially inwardly extending recesses from the peripheral margin thereof, such that the inner wall of the blast tube forms a portion of the margin of each said orifice.
4. A gun type oil burner as defined in claim 1 wherein said circular air plate assembly is provided with adjustable orifice means in the central portion thereof, adapted to provide a limited flow of air to the central part of the blast tube about the fuel nozzle.