US3225813A

US3225813A - Oil burner apparatus

Info

Publication number: US3225813A
Application number: US267379A
Authority: US
Inventors: Bruce R Walsh
Original assignee: Gulf Research and Development Co
Current assignee: Gulf Research and Development Co
Priority date: 1963-03-14
Filing date: 1963-03-14
Publication date: 1965-12-28
Anticipated expiration: 1982-12-28

Description

Dec. 28, 1965 B. R. WALSH v 3,225,813

OIL BURNER APPARATUS Filed March 14, 1963 4 Sheets-Sheet 1 I H 26 L f /z 27 4/ INVENTOR.

8806! E. WAS/7 Dec. 28, 1965 B. R. WALSH 3,225,313

OIL BURNER APPARATUS Filed March 14, 1963 4 Sheets-Sheet 2 6 4 1 A W 88 2% 1 L/ 64 L 94 98 IN VEN TOR.

5/90625'1? 774A 5 BY Dec. 28, 1965 B. R. WALSH OIL BURNER APPARATUS 4 Sheets-Sheet 5 Filed March 14, 1963 [2 P56 CENT F8010! DIOXIDE Pi! CIA/7' CMAQN wax/0F INVENTOR. BAl/CE' I? W4L A P5? CENT cmaav 010x105 Dec. 28, 1965 B. R. WALSH OIL BURNER APPARATUS Filed March 14, 1963 4 Sheets-Sheet 4 4. D E C a i I A 2: a

'7 a .9 /a l2 /3 P5 CENT CARBON DIOXIDE INVENTOR.

ITTORNEY United States Patent Ofifice 3,225,813 Patented Dec. 28, 1965 3,225,813 OIL BURNER APPARATUS Bruce R. Walsh, Wilkinsburg, Pa., assignor to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Delaware Filed Mar. 14, 1963, Ser. No. 267,379 9 Claims. (Cl. 158--4) This application is a continuation-in-part of my copending application Serial Number 183,874, filed March 30, 1962, and now abandoned.

This invention relates to an improved combustion apparatus. The apparatus of this invention provides superior mixing of fuel and air during combustion. Additionally, the apparatus of this invention advantageously modifies the configuration of the flame from a burner nozzle in a manner tending to prevent impingement of said flame upon combustion chamber Walls.

The apparatus of the invention comprises in combination a nozzle, an air tube and a cone, said air tube having a discharge opening and said nozzle disposed coaxially within said air tube at said discharge opening, means for spraying fuel through said nozzle, means for blowing air along said air tube and through said discharge opening, said cone disposed outside said air tube in the region of said discharge opening with the apex of said cone being directed toward the center of said discharge opening, said apparatus adapted so that air from said air tube and fuel from said nozzle approach the surface of the cone and are guided along said surface.

During operation of said apparatus a stream of air is blown toward the outer surface of the cone, an oil spray is also directed toward the outer surface of the cone, said air stream and said oil stream both approach the outer surface of the cone substantially concentrically with respect to the apex of the cone, and said air stream and said oil stream admix with each other in transit toward the base of said cone. Upon ignition, the admixing of air and fuel along the surface of the cone and the proximity of the resulting admixture to the hot surface of the cone result in highly improved combustion. The flame resulting from ignition is compact and envelops substantially the entire outer surface of the cone. However, the flame does not appear to contact or impinge upon the cone surface but rather appears to be spaced slightly apart from the outer surface of the cone along the entire cone length.

It is important that the air discharging from the air tube not be permitted to immediately diverge and thereby flow away from the apex of the cone but rather the air being discharged from the air tube should be induced to converge and thereby be directed toward the apex of the cone in order to obtain maximum advantage of said cone. It has been found that the use of a flat, sharp-edged orifice plate at the discharge end of the air tube produces especially advantageous results in cooperation with a flame cone of this invention by inducing a vena contracta in the air stream as it leaves the air tube, whereby the air stream is naturally induced in the direction of the apex of the flame cone. While other air directing apparatus can be utilized at the discharge end of the air tube to force the air in the direction of the apex of the flame cone, a flat, sharp-edged orifice plate is by far the most superior means for causing the air stream to converge toward the surface of the cone in accordance with this invention.

When the cone is substantially hollow and open at the base thereof a further advantage results in accordance with this invention. When employing a hollow cone having an open base it was found that, by adjusting the axial distance between the cone and the discharge opening of the air tube, an optimum distance can be found at which the extremity of the flame near the base of the cone tends to curve inwardly toward the cone axis. This effect is evidently due to the occurrence of a small but measurable vacuum within a hollow cone having an open base during combustion with the apparatus of this invention. In order to achieve this effect, it is necessary that the surface of the cone above the base be solid and free of perforations since direct intrusion of the flame into the cone interior through an opening on its surface will prevent creation of even a small vacuum within the cone.

The invention will be more completely understood by reference to the accompanying drawings in which: FIG- URE l is an exterior elevation View of the apparatus of the invention, FIGURE '2 is an interior view of the apparatus of FIGURE 1 and shows the air tube-nozzle-cone combination of the invention, FIGURE 8 illustrates an advantageous modification in the View of FIGURE 2, FIGURES 3 and 4 show details of a swirl-type nozzle which type of nozzle is especially suitable for use in the apparatus of the invention, and FIGURES 5, 6, 7 and 9 are graphs of data illustrating the advantage of the apparatus of the invention.

Referring to FIGURES l and 2, air tube 10 is dis posed to receive a stream of air from blower 12, which is attached to motor 14 by means of belt 16. Blower 12 receives atmospheric air through an axial passageway opening 18. The blower forces the air through air tube 10 to the choke 20 at the discharge end thereof. Disk 22 is disposed concentrically within air tube 10 at an intermediate position along its length and upstream from the discharge end thereof. Disk 22 is of a slightly smaller diameter than the internal diameter of the air tube and is spaced from the interior surface of the air tube by means of a plurality of radial prongs 24. Extending axially through disk 22 is an oil conduit 26 through which oil is pumped under a pressure of about to pounds per square inch gauge by means of pump 27. Also extending through disk 22 are electrode leads 23 which terminate With electrodes 259 and are connected to an external power source, not shown. A swirl-type spray nozzle 30 is attached to the discharge end of oil conduit 26 and is substantially axially disposed within choke 20 at the discharge end of air tube 10. Vanes 32 are uniformly distributed along the interior surface of choke 20 and surround nozzle 30. The blower is supported by a base 34.

The air tube-nozzle assembly is disposed to discharge both air and oil into a furnace chamber 38 through an opening 40 in one end wall thereof. The diameter of opening 40 is approximately the same as the diameter of air tube 10 and is complementary to the discharge end thereof. The top of furnace chamber 38 is equipped with an enclosure 45 from the center of which extends a flue stack 42. Within the furnace is a hollow right circular cone 44 whose apex 46 is disposed in front of and close to the discharge end of air tube 10. The cone is disposed so that its axis coincides with an extension of the axis of air tube 10. The apex angle of cone 44 is at least slightly larger than the angle of the spray emitted from nozzle 30 in order to insure that the spray from the nozzle does not avoid the surface of the cone. The base 54 of cone 44 lies on a plane transverse to the longitudinal axis of air tube 10 and nozzle 30. The diameter of base 54 is at least slightly larger than the diameter of the discharge opening of choke 20 in order to insure that the air discharge from the tube does not avoid the surface of the cone.

The distance between apex 46 and nozzle 30 is easily adjustable. The need for such adjustment is readily ascertainable, the furnace 38 being provided with a door 50 having a window 52 for visual observation of the furnace interior during combustion. Cone 44 is supported upon a base plate 47 by means of supporting rod 48 attached at one end to the cone and at the other end to the cone and at the other end to the base plate. Base plate 47 rests upon the floor of the combustion chamber and is slidable with respect to said floor. A threaded bolt 39 having a head portion 41 extends through the wall of combustion chamber 38 and extends transversely through rod 48 in threaded engagement therewith. Rotation of bolt head 41 from the exterior of the combustion chamber provides adjustment of the axial distance between cone apex 46 and nozzle 30.

The surface of the cone, between the apex and the base thereof, is smooth and uninterrupted. The cone can be solid or it can be hollow and have a base enclosure 43 shown in cutaway view. Advantageously, the cone is at least partially hollow and does not have a base enclosure so that the hollow zone is exposed to the atmosphere at the base of the cone. When the cone is hollow and open at the base, a partial vacuum tends to form within the cone during combustion of fuel and this partial vacuum advantageously alters the configuration of the flame as compared to the configuration of the flame when employing a solid cone or a hollow cone having a base enclosure. It is important that the surface of the cone above the base be free of perforations since such perforations permit direct flame intrusion into the hollow of the cone, preventing creation of a partial vacuum therein. The apex of the cone can be pointed or it can be rounded into the configuration of a hemisphere, but, in either case, it must be closed and free of perforations. The included angle at the apex of the cone and the diameter of the frustum of the cone are related to the included angle of the conical fuel spray and the diameter of the air discharge opening because both the fuel stream and the air stream must be directed toward the exterior cone surface and have an adequate opportunity to admix in transit along said surface to the base of the cone. Upon combustion, the length of the cone is sufficiently long to permit adequate admixing of air and oil during transit of the flame along the surface of the cone but is preferably sufliciently short to permit the flame to extend slightly beyond the cone.

FIGURE 8 illustrates a highly advantageous modification of the apparatus of FIGURE 2 which is adapted to induce air flow from air tube to converge toward the apex of cone 44 and to prevent the air, upon leaving the air tube, from diverging away from the surface of the cone. The apparatus of FIGURE 8 utilizes a flat orifice plate 100 having a sharp edge 102 defining a circular axial orifice. The apparatus of FIGURE 8 differs from the apparatus of FIGURE 2 only in that flat orifice plate 100 is disposed at the discharge end of air tube 10 in place of choke 20, shown in FIGURE 2, which has a curved interior surface. Flat, sharp-edged orifice plate 100 produces a vena contracta 104 in the air stream inducing the air toward the apex of cone 44. The tests illustrated in FIGURE 9, which are discussed below, show that in the absence of a cone, flat, sharp-edged orifice plate 100 produces highly inferior results during combustion as compared to choke 20 which has a curved internal surface, but that the combination of flat, sharpedged orifice plate 100 together with a cone functions in a significantly superior maner during combustion as compared to the combination of choke 20 and a cone.

Referring to FIGURES 3 and 4, a nozzle body 56 is adapted to receive a swirl stem 66 at one end thereof. Swirl stem 66 is urged into position by means of a plug 58 which seals the interior of nozzle body 56 at threads 62. Plug 58 and swirl stem 66 have flat surfaces that are in sliding engagement at 68 so that the plug 58 and swirl stem 66 can be rotated as well as shifted radially relative to each other. Swirl stem 66 is provided with a cylindrical central stud 70 that is received in a central cylindrical opening 72 in plug 58. The opening 72 is larger than the stud 70 to permit radial movement of the swirl stem 66.

The nozzle body 56 is provided with external threads 74 for threaded connection to fuel oil supply conduit 26. The plug 58 is spaced from nozzle body 56 to define an annular space 78 to which liquid fuel is supplied under pressure from the conduit 26 through a central bore 80 and an intersecting transverse opening 82 in the plug 58.

Swirl stem 66 includes a frusto-conical end portion 84 that seats flush against a frusto-conical internal surface 86 of the nozzle body 56. A swirl chamber 88 is defined between the top of frusto-conical portion 84 of the swirl stern and the nozzle body 56, and a discharge orifice 90 is provided in the nozzle body 56 communicating with the swirl chamber 88. The swirl chamber 88 can be frusto-conical in configuration, as shown, or it can be cylindrical in configuration. The discharge orifice 90 along its axial extent includes an intermediate cylindrical section 92, with the discharge orifice 90 being outwardly flared, as at 94, from the cylindrical section 92 toward its exit end and flared, as at 96, from the cylindrical section 92 toward its inlet end.

The frusto-conical portion 84 of swirl stem 66 is provided with a plurality of circumferentially spaced swirl slots 98 extending longitudinally on the surface thereof that are essentially arranged tangentially with respect to the swirl chamber 88. The slots 98 can be essentially straight as shown or generally helical in configuration. The purpose of the slots 98 is to provide fluid communication between the space 78 and the swirl chamber 88 of restricted cross sectional area and arrangement so that fuel will flow at high velocity into swirl chamber 88 and rotate or swirl about the central axis of the swirl chamber 88. Fuel entering the swirl chamber 88 swirls in the swirl chamber 88 and thence passes, while still rotating, through the discharge orifice 90 to be emitted from the nozzle as a generally conical spray.

During operation of the apparatus shown in the drawings, motor 14 drives blower 12 drawing atmospheric air inwardly through passageway 18 and blowing it through air tube 10 toward the choke 20 at the discharge end thereof. Air disk 22 forces the air to be substantially confined to the region near the walls of tube 10 whereby the flowing air stream assumes a shape corresponding generally to a hollow cylinder. The air is thus caused to pass through peripheral vanes 32 before discharging from the air tube whereby it has a swirl imparted to it upon leaving air tube 10.

Pump 27 forces oil under pressure through conduit 26 whence it enters nozzle 30. In entering nozzle 30 it passes through bore 80, transverse opening 82, annular space 78 and slots 98. Slots 98 cause the oil to swirl in swirl chamber 88 so that it is emitted from the nozzle through discharge orifice 90 as a conical spray of atomized oil droplets. The axial distance between cone 44 and nozzle 30 is adjustable by rotation of head 41 of bolt 39 and cone 44 is disposed so that the conically shaped spray of atomized oil droplets from the nozzle is directed toward the surface of the cone in the region of apex 46 and travels along the cone to base 54 thereof. The air stream from air tube 10 must also be directed toward the surface of cone 44. Therefore the diameter of air choke 20 is less than the diameter of the base 54 of cone 44 or, at least, the pitch of peripheral vanes 32 is established to cause swirling air to converge upon the surface of cone 44, rather than diverge and avoid said surface.

Arcing of electrodes 29, by a suitable electrical means, not shown, causes ignition of the oil spray and atomized, burning oil droplets are sprayed toward apex 46 of cone 44 and travel from the apex to the base 54. The stream of swirling air from air tube 10 is guided along the surface of the cone and intermingles with the stream of burning oil droplets. A high degree of mixing of oil and air occurs during transit along the length of the cone. The presence of the cone sharply alters the type of combustion produced in its absence. In the absence of cone 44, a proliferation of burning oil droplets diverging laterally from the main body of the flame is visible. This phenomenon is probably due to inadequate mixing of the air stream and the oil spray. When the cone is utilized as described there is a complete absence of burning oil droplets diverging from the body of the flame. The absence of the burning oil droplets diverging from the body of the flame is probably due to forced admixture of oil and air and also to the fact that this admixture occurs near a hot surface, tending to induce vaporization of liquid oil droplets.

A further surprising visible change in flame characteristics occurs when employing a cone in that the cone causes a reduction in flame length, thus generally avoiding direct flame impingement upon the opposing furnace wall. This reduction in flame length occurs if the cone is properly spaced from the end of air tube at which spacing the end of the flame, at the sides and the bottom thereof, is observed to turn inwardly at the base of the cone toward the cone axis. A slight vacuum can be measured inside the cone during combustion and it is evidently the existence of this vacuum which induces the flame extremity to bend in the region of the base of the cone in the direction of the longitudinal axis of the cone. The various flame characteristics described are observed through the furnace window 52 and the cone can be positioned in relation to nozzle 30 for optimum combustion characteristics by rotating head 41 of bolt 39.

A series of tests were conducted to illustrate the advantage of the air tube-nozzle-cone combination of this invention. These tests were made by analyzing samples of flue gas for both carbon dioxide content and smoke. Following is a description of the equipment utilized in making the tests illustrated in FIGURES S, 6 and 7: These tests were made within a combustion chamber 9 inches wide, 12 inches long and 13 /2 inches high, The air tube employed was 4 /2 inches in diameter and its discharge end was coincident with a side wall of the combustion chamber. The nozzle employed was a Monarch F-SO swirl-type pressure nozzle, rated at 1.0 gallon per hour, having a 45 included spray angle and producing a swirling spray shaped as a solid cone of oil droplets. The nozzle was axially disposed within the air tube and its discharge orifice was recessed /8 inch from the discharge opening of the air tube. Unless otherwise noted, in each test an air disk 3 /2 inches in diameter was employed within the air tube. Also, unless otherwise noted, peripheral air vanes were employed at the discharge end of the air tube integral with an air choke having a curved internal surface, such as choke in FIGURE 2, which restricted the air opening diameter at said discharge end to 2% inches. In tests employing a cone, the cone employed had a 60 included angle, was hollow, 4% inches in length and had a base 5% inches in diameter.

Following is a description of the equipment utilized in making the tests illustrated in FIGURE 9: These tests were made in a combustion chamber having a length and width each measuring 11% inches. The air tube employed had a 4 inch inside diameter and its discharge end was coincident with a side wall of the combustion chamber. The nozzle employed was a Monarch F-80 swirltype pressure nozzle, rated at 1.0 gallon per hour, which produces a swirling spray having a 45 included angle and shaped as a solid cone of oil droplets. The nozzle was axially disposed within the air tube and its discharge orifice was recessed inch from the discharge opening thereof. In each test an air disk 3 /2 inches in diameter was employed within the air tube. In certain of the tests an air choke having a curved internal surface and air vanes, such as choke 20 in FIGURE 2, was employed at the discharge end of the air tube and this choke restricted the diameter of the air opening at said discharge end to 2% inches. In other tests, choke 20 was replaced by a flat, sharp-edged orifice plate, such as orifice plate in FIGURE 8, which was disposed directly at the discharge end of the air tube and this orifice plate restricted the air opening diameter at said discharge end to 2% inches. In the tests employing a cone, the apex of the cone was disposed 1 /2 inches from the nozzle discharge orifice. These dimensions show that the discharge orifice of the nozzle and the apex of the cone are disposed on opposite sides of the restricted air opening, with the nozzle discharge orifice and the apex of the cone being removed from the restricted air opening by a distance no greater than the diameter of said restricted air opening. The cone had a 60 included angle, was hollow and had an open base which measured 3 /8 inches in diameter.

The tests are described below and are designated according to the figures in which their results are illustrated. The figures show the results of each test as a graph of smoke spot number v. percent carbon dioxide in a sample of flue gas as determined by the method described in ASTM Standards on Petroleum Products, 1960, page 1041. For purposes of analyzing the test results it is noted'that best results are achieved with a high carbon dioxide content, indicating a high degree of combustion, and a low smoke content. While the percent of carbon dioxide can be increased by reduction of air input, this will have the adverse effect of increasing smoke content. On the other hand, smoke content can be decreased by admitting a large excess of air but this will have the adverse eifect of greatly diminishing carbon dioxide content. Optimum results are achieved with the combination of relatively high carbon dioxide content and relatively low smoke content.

Tests illustrated in FIGURE 5 Curve A of FIGURE 5 was obtained by testing an apparatus as indicated above and generally as illustrated in FIGURES 1 and 2, except that no cone was utilized. In the tests of curve B, the apparatus was modified only by the utilization of a cone having an enclosed base, which base was disposed a distance of 6 inches from the rear wall of the combustion chamber. The test of curve C was a modification of the test of curve B only by the removal of the cone base enclosure to open the hollow interior of the cone to the atmosphere.

Curves 9, B and C of FIGURE 5 clearly show the improvement attainable when utilizing a cone in combination with a swirling-type fuel nozzle and air tube and further show that by far the best results are achieved when the cone employed .is hollow and is open at the base.

Tests illustrated in FIGURE 6 Curves A, B and C show the effect of varying the distance between the nozzle and the cone. In the test of curve A no cone was employed. In the tests illustrated in curves B and C a hollow cone having an open base was employed with the base being disposed 5 inches and 6 inches, respectively, from the rear wall of the furnace. Curves B and C show that adjustment of the distance between the cone and the nozzle is critical to the achievement of best results, and further show that for best results to be achieved the cone must be sufiiciently close to the nozzle to accomplish a high degree of mixing of air and oil near the surface thereof.

Tests illustrated in FIG URE 7 tests employing a cone an improvement in combustion was achieved but in the test employing a flat disk rather than a cone a deleterious effect upon combustion characteristics occurred. Curve C shows the results of a test employing a hollow cone having an open base which is disposed 6 inches from the rear furnace wall. In the test of curve C the air disk was removed from the air tube but the vanes and choke assembly was employed. It is noted that the removal of the air disk from the air tube produced inferior results as compared to an identical test in which the air disk was present. In this regard, see FIGURE 5, curve C, and FIGURE 6, curve C, for comparison. Curve D shows the results of a test employing a cone whose open base is disposed 6 inches from the rear furnace wall wherein the air disk was employed but the vanes and choke assembly was removed from the air tube. It is noted that the removal of the vanes and choke assembly from the air tube produced inferior results as compared to an identical test in which the vanes and choke assembly was present. See FIGURE 5, curve C, and FIGURE 6, curve C, for comparison. Curve E shows the results of a test employing a hollow, open base cone whose surface is uniformly perforated over its entire extent and whose base is disposed 6 inches from the rear furnace wall. It is seen that the use of a perforated cone had a deleterious effect upon combustion.

Tests illustrated in FIGURE 9 In each of the tests of curves A and B, a choke having a curved internal surface and attached vanes, such as choke 20 of FIGURE 2, was utilized at the discharge end of the air tube. In the test of curve A no flame cone was employed while a flame cone was employed in the test of curve B. It is seen that improved results were achieved by the use of a flame cone. In each of the tests of curves C and D a flat, sharp-edged orifice plate, such as orifice plate 100 of FIGURE 8, was utilized at the discharge end of the air tube in place of the choke having the curved internal surface. In the test of curve C no flame cone was employed while a flame cone was employed in the test of curve D. It is seen that in the absence of a flame cone, the flat, sharp-edged orifice plate is greatly inferior to the choke having the curved internal surface but that the orifice plate-flame cone combination is substantially superior to the curved surface choke-flame cone combination. Therefore, there is a greater interdependence of function between the flame cone and the orifice plate than there is between the flame cone and the curved surfaced choke.

Various changes and modifications may be made without departing from the spirit of this invention and the scope thereof as defined in the following claims.

I claim:

1. An apparatus comprising in combination swirling fuel spray nozzle means for producing a swirling spray of atomized oil droplets, said spray nozzle means having a discharge orifice, an air tube, a cone having an apex and a base, said nozzle means disposed coaxially within said air tube, said cone disposed outside and aligned with said air tube with its apex directed toward said air tube, disk means slightly smaller in diameter then said air tube disposed concentrically within said air tube upstream from said nozzle means for forcing the air flowing in said air tube to be substantially confined to the region near the wall of said air tube, air directing means disposed at the discharge end of said air tube for directing an air stream from said air tube toward the surface of said cone, said air directing means defining an air tube discharge opening, both the discharge orifice of said nozzle means and the apex of said cone disposed at a distance from said air tube discharge opening which is no greater than the diameter of said air tube discharge opening, the apex angle and the base of said cone being sufliciently large that the swirling spray of atomized oil droplets from said nozzle means and the air stream from said air tube discharge opening are both concentrically directed toward said cone, said apparatus adapted so that said air stream and said spray of atomized oil droplets admix with each other in proximity to the surface of said cone during transit toward the base thereof.

2. The apparatus of claim 1 wherein said cone is sufliciently short to permit the flame produced upon ignition of the air-oil mixture to extend beyond the base of the cone.

3. The apparatus of claim 1 wherein said air directing means comprises a flat sharpedged orifice plate disposed at the discharge end of said air tube.

4. The apparatus of claim 1 including means for supplying fuel under pressure to said nozzle means.

5. The apparatus of claim 1 including means for blowing air through said air tube.

6. The apparatus of claim 1 wherein said cone is substantially hollow and open at the base thereof.

7. The apparatus of claim 1 including means for adjusting the axial distance between said cone and said air tube.

8. The apparatus of claim 1 including a combustion chamber wherein said cone is disposed within said combustion chamber.

9. The apparatus of claim 1 wherein said air directing means is provided with air swirling vanes.

References Cited by the Examiner UNITED STATES PATENTS 525,261 8/1894 Cross 158-73 1,466,186 8/1923 Pidgeon 158-4 2,019,815 11/1935 Holtham 158-78 2,473,769 6/ 1949 Schinman 158-76 2,486,137 10/1949 Evans 158-75 FOREIGN PATENTS 522,485 12/ 1938 Great Britain.

FREDERICK L. MATTESON, JR., Primary Examiner.

MEYER PERLIN, JAMES W. WESTHAVER,

Examiners.

Claims

1. AN APPARATUS COMPRISING IN COMBINATION SWIRLING FUEL SPRAY NOZZLE MEANS FOR PRODUCING A SWIRLING SPRAY OF ATOMIZED OIL DROPLETS, SAID SPRAY NOZZLE MEANS HAVING A DISCHARGE ORIFICE, AN AIR TUBE, A CONE HAVING AN APEX AND A BASE, SAID NOZZLE MEANS DISPOSED COAXIALLY WITHIN SAID AIR TUBE, SAID CONE DISPOSED OUTSIDE AND ALIGNED WITH SAID AIR TUBE WITH ITS APEX DIRECTED TOWARD SAID AIR TUBE, DISK MEANS SLIGHTLY SMALLER IN DIAMETER THEN SAID AIR TUBE DISPOSED CONCENTRICALLY WITHIN SAID AIR TUBE UPSTREAM FROM SAID NOZZLE MEANS FOR FORCING THE AIR FLOWING IN SAID AIR TUBE TO BE SUBSTANTIALLY CONFINED TO THE REGION NEAR THE WALL OF SAID AIR TUBE, AIR DIRECTING MEANS DISPOSED AT THE DISCHARGE END OF SAID AIR TUBE FOR DIRECTING AN AIR STREAM FROM SAID AIR TUBE TOWARD THE SURFACE OF SAID CONE, SAID AIR DIRECTING MEANS DEFINING AN AIR TUBE DISCHARGE OPENING, BOTH THE DISCHARGE ORIFICE OF SAID NOZZLE MEANS AND THE APEX OF SAID CONE DISPOSED AT A DISTANCE FROM SAID AIR TUBE DISCHARGE OPENING WHICH IS NO GREATER THEN THE DIAMETER OF SAID AIR TUBE DISCHARGE OPENING, THE APEX ANGLE AND THE BASE OF SAID CONE BEING SUFFICIENTLY LARGE THAT THE SWIRLING SPRAY OF ATOMIZED OIL DROPLETS FROM SAID NOZZLE MEANS AND THE AIR STREAM FROM SAID AIR TUBE DISCHARGE OPENING ARE BOTH CONCENTRICALLY DIRECTED TOWARD SAID CONE, SAID APPARATUS ADAPTED SO THAT SAID AIR STREAM AND SAID SPRAY OF ATOMIZED OIL DROPLETS ADMIX WITH EACH IN PROXIMITY TO THE SURFACE OF SAID CONE DURING TRANSIT TOWARD THE BASE THEREOF.