US3269446A - Electrostatic atomization of liquid fuel - Google Patents

Description

Aug, 30, 1966 F. E. LUTHER LECTROSTATIC ATOMIZATION OF LIQUID FUEL 2 UhGGtSShEBSt 1 Filed May 19, 1965 FIG. 3

lNVENTOR FLOYD E. LUTHER Mung.

FIG. 2

United States Patent Office 3,269,446 ELECTROSTATH? ATGMHZATHUN F LIQUID FUEL Floyd E. Luther, Berkeley, Calif., asslgnor to Chevron Research Company, a corporation of Delaware Filed May 19, 1965, Ser. No. 467,801 tllaims. (til. 158-4) This application is a continuation-in-part of my copending application Serial No. 251,977, filed January 16, 1963, now abandoned.

This invention relates to an atomizing liquid fuel burner and, more particularly, to a device for atomizing liquid fuels and the like by electrostatic atomization.

Fuel atomization at low fuel flow rates has not been widely successful because the extremely small orifices needed to restrict flow at flow rates in the order of onehalf /2) gallon per hour or less are easily clogged by contaminants, debris and fuel degradation products. This has been an area of diligent experimentation with the result that there have been developments of varying degrees of success following widely divergent theories and concepts of atomization. For example, there has been some work in the use of ultrasonic waves to agitate a liquid surface to produce atomized droplets from it. Others have concerned themselves with the application of an external deflecting electric or magnetic field to charged fuel particles and particularly to liquid fuel which has been ionized in a flame.

Electrostatic atomization, wherein the liquid is given an electrical charge of one polarity and attracted to an opposite electrode has also been the subject of considerable effort, but such efforts have been successful only with liquids of relatively high electrical conductivity because of a number of substantial problems to be overcome. Many liquids, such as heating oil, are of very low conductivity and are, therefore, not particularly suited to electrostatic atomization by previously tried methods.

Very substantial voltages are required to impose the charge on liquids of low conductivity and this disadvantage is particularly apparent when direct current is used, with a charge of one polarity imposed on the liquid and with the electrode at another polarity. With the liquid under the constant attractive force of the electrode at opposite polarity, liquid droplets tend to be frequently drawn off from the atomizing head before a sufficient atomizing electrical charge is transferred thereto. Consequently the quality of the atomization suffers. More over, the constant attraction of the electrode draws liquid particles which tend to impinge upon the electrode, thereafter to drip off or be drawn off by ground potential without being properly atomized. The present invention overcomes these difficulties.

With alternating current applied to both the atomizing head and the electrode, satisfactory atomization has been achieved with liquids of relatively high electrical conductivity but when liquids of relatively low conductivity are used atomization occurs only at voltages just below that for corona arcdischarge. Consequently, there is often just a very narrow voltage range within which an alternating current system of this type may be operated and, under ordinary circumstances, it is difficult to keep such system functioning without generating a short circuit, promoting ion flow between the atomizing head and the electrode. The present invention overcomes these dilficulties.

It is, therefore, an object of this invention to provide an apparatus for electrostatic atomization which is capable of producing satisfactory atomization for liquids of relatively low electrical conductivity at voltages considerably below that for corona arc-discharge.

It is a further object of this invention to provide an 3,269,446 Patented August 30, 1966 apparatus for electrostatic atomization which overcomes the defects of fuel impingement on the electrodes.

It is a further object of this invention to provide an apparatus for electrostatic atomization which permits liquids of low conductivity to build up a satisfactory charge before being drawn off by the attracting electrode.

Another object of this invention is to provide a novel electrostatic atomizer for furnace fuel oils.

These and other objects and advantages of this invention will become apparent from the specification following when read in conjunction with the accompanying drawings.

In carrying out this invention there is provided a discharge head which is connected as an electrode in an electrical circuit and which has a surface upon which a film of the liquid to be atomized is formed. The surface is proportioned to provide a suficient time of residence of the film thereon, as the liquid is drawn from an edge of the surface, to enable a liquid of relatively low electrical conductivity to acquire an electrical charge from the discharge head. A second electrode of the circuit is placed adjacent to the edge of the film-forming surface and operates, at least part of the time, at an opposite polarity to that of the discharge head. When the discharge head and the second electrode are of opposite polarity atomized droplets of the liquid are drawn from the discharge head toward the second electrode. Preferably means are provided to prevent the atomized liquid from impinging and accumulating on the second electrode from which it may be drawn off in an unatomized form by gravity or by the ground potential, as indicated heretofore.

In a preferred embodiment of this invention there is provided a discharge head of conical configuration which is preferably disposed with its axis upright and with the conical surface diverging downwardly to a rather sharp annular edge. Fuel is introduced to the outside of the conical surface to flow naturally down toward the location of the highest charge concentration at the sharp, annular edge and to acquire a charge by means of a direct current potential supplied to the discharge head. Disposed below and spaced apart from the discharge head is an annular electrode to which an alternating current potential is supplied. Consequently, the liquid on the atomizing head is in a strong electrical field of one polarity and the electrode is alternately reversing polarities. When the liquid acquires an electrical charge of the polarity of the discharge head, charged droplets are drawn from the annular edge of the head during periods of relative opposite polarity of the annular electrode. Each interval between such alternating periods when the electrode is at the same polarity as the discharge head affords an opportunity for an electric charge to build up in the liquid. In a burner employing such an atomizing device, there is preferably provided a suitable blower to mix the air and atomized fuel intimately and a suitable flame stabilization means to isolate the flame from the immediate atomization zone.

In the drawings:

FIG. 1 is a schematic illustration with wiring diagram of a burner with an electrostatic atomizer embodying features of this invention;

FIG. 2 is an isometric view partially in section of a discharge head forming a part of this invention;

FIG. 3 is a vertical sectional view of the discharge head of FIG. 2;

FIG. 4 is an isometric view partially in section of a modified form of burner assembly embodying features of this invention;

FIG. 5 is an isometric view partly in section of another modification of an atomizer made in accordance with this invention, and

FIG. 6 is a diagrammatic illustration of the relative conductivity of various liquids.

Referring now to the drawings with greater particularity, the atomizing system of my invention is shown in FIG. 1 and may comprise a furnace chamber 2 which may be divided into an atomizing chamber 4 and a combustion chamber 6. Disposed within the atomizing chamber is a liquid discharge head 8 comprising a conical discharge surface 10 formed of electrically conducting material on the cone 11 and over which a liquid film is formed, the liquid being distributed over the conical film-forming discharge by means of a feeder 12 having an annular outlet port 14. Burner oil or other suitable liquid fuel is delivered to the feeder 12 from a source thereof (not shown) by any suitable means such as the conduit 16. The structure of the liquid discharge head 3 will be described in more detail hereinafter but for the present it suffices to state that it includes the feeder 12, the conical film-forming surface 10, and a relatively sharp annular edge 18 formed on the cone 11 at the bottom of surface 11 and toward which the liquid film flows.

Disposed below the liquid discharge head 8 is an attracting electrode 20 which draws oppositely charged oil droplets from the relatively sharp discharge edge 18 of the conical surface 10 to be propelled downwardly, assisted by a low pressure air blower 22, into the zone at the lower end of the atomizing chamber l where the atomized oil droplets are thoroughly mixed with the swirling air. The fuel-air mixture is then directed to the combustion chamber 6 wherein it is ignited, as by the igniter 23.

Preferably there is provided some suitable flame stabilizer which serves to isolate the flame from the zone of the atomizer and this may be accomplished in any suitable manner such as by directing the air-fuel mixture through a venturi 24 which maintains the fiow at a velocity greater than the burning rate so that flame remains within the combustion chamber 6.

Although the apparatus of this invention may be applied to the atomization of liquids generally, it is particularly applicable to the atomization of liquids which have a relatively low electrical conductivity, such as the fuel oil which is commonly used in domestic heating furnaces and which is designated as No. 2 heating oil. As will be observed from the comparison illustrated in FIG. 6, No. 2 heating oil has a conductivity of approximately 1O mho/cm., which is substantially comparable to that of mica. Thus, ordinarily, No. 2 heating oil would be considered an effective electrical insulator.

Again referring to FIG. 6, No. 2 heating oil can be treated with an additive to increase its conductivity to approximately 10 mho/cm. without destroying its utility as a fuel oil, but even such a treated oil is much less electrically conductive than liquids which might be considered to have relatively high electrical conductivity, as sea water or tap water, which range around 10' mho/cm. conductivity.

It would appear, then, that liquids of relatively low electrical conductivity would not be susceptible to atomization by electrostatic means because of the inability of such a liquid to take an electrical charge of suflicient amount to cause the liquid to be attracted to an oppositely charged electrode with enough force to produce atomization of it. However, by using the techniques of this invention the atomization of such a liquid can be accomplished.

The particular means of atomizing a liquid fuel electrostatically is a significant feature of this invention and includes a source of alternating current 26 which may be, but is not necessarily, a 110 volt, 60 cycle source. If desired, the input voltage :may be controlled at 28 and connected to high voltage transformers 30 delivering an out put in the order of 45 kv. over conductors 32 and 34. A branch 35 of line 34 is connected to one input terminal of a full-wave rectifier such as the schematically illustrated rectifier 36, the line 32 being connected to the other input terminal.

The primary windings 131 and 131 of transformer 30 are connected in series. The secondary windings 132 and 134 also are connected in series and have between them a center tap to ground as indicated at 135.

With ground taken as the reference datum, or zero potential, during one half cycle of transformer output the conductor 32 will beat a positive potential relative to ground and the conductor 34 will be at a negative potential relative to ground as illustrated by the symbols in FIG. 1. On the other half of the cycle the polarity of the transformer output will be reversed.

If the corresponding primaries and secondaries of the transformer are electrically similar to each other, the difference in potential between ground and the conductor 32 will be equal to the difference in potential between ground and the conductor 34. Therefore, the difference in potential between the output terminals of the transformer will be equal to twice the difference in potential between either output terminal and ground. When the transformer is operating at the portion of the cycle of the A.C. input which causes the conductor 32 to be at a positive potential relative to ground and the conductor 34 to be at a corresponding negative potential, as indicated by the symbols in FIG. 1, the diode 136 passes the positive potential through conductor 32 to the conductor 38, which is electrically connected to the discharge head 8. The diode 137 blocks a short-circuit current flo-w back to the transformer.

When the transformer is operating on the next half of the cycle the conductor 34 becomes positive relative to ground and the conductor 32 becomes negative relative to ground. The diode 137, which is connected to the conductcr 34 through the conductor 35, then passes the positive potential to conductor 38 and the diode 136 blocks the short-circuit return current flow. Therefore, the conductor 38 and hence the discharge head 8 operates continuously at full-wave rectified positive potential.

The conductor 38 may be electrically connected to the discharge head 8 by connecting the conductor to some portion of the interconnected apparatus, such as the delivery conduit 16 which then will be electrically insulated from the furnace chamber as at 39. With the discharge head at a continuous positive potential an oil film on it will acquire a positive charge. The charge will be particularly concentrated at the relatively sharp lower edge 18 of the cone 11.

The conductor 34 is directly connected to the electrode ring 20 which is electrically insulated from the furnace chamber, as at 37. Thus the ring 21) has impressed on it the alternating current potential of the corresponding output terminal of the transformer 30.

The potential difference between the discharge head 8 and the electrode ring 20 alternates between the full potential difference of the transformer output and zero as the ring 21 correspondingly alternates from a negative to a positive potential relative to ground. This may be seen by referring again to FIG. 1. When the conductor 32 is at a positive potential relative to ground and the conductor 34- is at a corresponding negative potential, as indicated by the symbols in FIG. 1, the difference in potential between the discharge head and the ring will be the same as that between the output terminals of the transformer, and also will be twice as great as that between either output terminal and ground.

When the polarity of the output of the transformer is reversed and the conductor 34 has impressed on it a positive potential relative to ground, the discharge head, through conductors 35 and diode 137 will have impressed on it the same potential relative to ground, both in polarity and amount, as has the electrode ring 20. Therefore, during this half of the cycle there will be no difference in potential between the discharge head and the electrode ring.

It follows from the foregoing that since the liquid at the edge 18 of conical surface 14) is in a position to acquire a positive charge, and an alternating current po tential is impressed on electrode ring 20, there are cyclic alternate periods during which the electrode ring attracts the positively charged liquid from the edge 18. Between these intervals there are corresponding alternate intervals during which there is no attraction between the ring and the discharge head and the film of oil on the conical surface is enabled to build up a charge. Moreover the voltage and spacing between the electrodes 11 and can be arranged so that as the oil droplets drawn from the annular edge 18 approach the electrode ring 20, the charge of the latter is reversed and droplets are repelled away from it, thus preventing the droplets of oil from impinging upon the electrode ring 20 and accumulating thereon. During this time the current of air from the blower 22 will sweep the atomized droplets of oil from the chamber 4 into the combustion chamber 6.

It is not necessary for the above-described operation that the inner wall of the furnace chamber be grounded since the atomization of the fuel oil depends primarily on the difference in potential between the discharge head 8, particularly the annular edge 18, and the electrode ring Ztl. However, it may in some installations be desirable to ground the furnace chamber and such a ground connection is indicated at 81, FIG. 1. It will be noted by reference to this figure and the above description that the electrode ring 24 will have impressed on it an alternating difference in potential relative to ground which will tend to draw off any fuel oil droplets which may accumulate on the ring.

As shown in FIG. 1 the cone 11 is preferably arranged with its axis vertical and with its outer surface it) diverging downwardly so that the sharp edge 18 of maximum charge concentration is located at the bottom to permit the oil film to gravitate thereto naturally. Preferably the electrode ring 20 which, as stated heretofore, is placed adjacent to the edge of the film-forming surface, is spaced elow and concentric with the lower edge 18 to draw oil droplets uniformly therefrom.

Finally, the oil droplets are agitated and intermixed with air, such as from a low pressure blower 22 or the like, and ignited in the combustion chamber 6, some suitable means such as the venturi 24 being provided to stabilize burning so as to prevent invasion of the flame into the atomizing zone 4.

Referring now to FIGS. 2 and 3 there is shown a preferred embodiment of liquid discharge head 8 which will now be described in detail. It will be noted that the cone 11 is truncated, as at 40, and a series of circumferentially spaced cylindrical sectors 42 extend upwardly from the truncated portion with flow passages 43 formed between them. The sectors are preferably relieved by a circum' ferential channel at 44 to provide a circumferential distribution of liquid to the annular flow orifice 14. The cone 11 is preferably secured to a holder 4-6 which has an internal conical surface 48 at the lower end thereof complementary to and spaced from the conical surface 10 to provide the outlet port 14. Threaded, welded or otherwise secured within the holder 46 is a flow distributor 4-9 which is formed with axially disposed distributing conduits 51 communicating with the flow passages 43. A bolt member projects from the lower end of the flow distributor 49 and is threaded into the cone to secure it to the holder 46. Fuel is introduced to the feeder 12 through a conduit 16 which opens into the upper end of the holder 46 above the distributor 49.

Preferably, the base of the cone 11 is relieved to form a bottom surface 54 spaced axially inwardly from the lower edge 18 to provide for an internal conical surface 56 which intersects the conical outer surface 10 so that the annular edge 18 is of maximum sharpness to increase the concentration of electrical charge.

Referring now to FIG. 4, the discharge head 8 is shown in a different type of burner wherein the ring electrode is replaced by a screen 66 of metallic mesh supported on brackets 61 of electrically insulating material. The screen functions both to attract the oil particles from the adjacent edge 18 of the conical surface 10 and to stabilize the flame burning circumferentially around the screen of). In this case, a blower 22 assisted by an air deflector 63 is provided to agitate the air within the burner at low pressure intimately to mix the fuel and air about the screen 60, and the screen acts as a flame barrier.

Any suitable furnace structure may be employed, but, for purposes of illustration, there is shown an open top furnace 64 of any suitable material. The fuel line 16 is introduced through the wall of the furnace from which it is electrically insulated, as at 39, and is positioned to hold the electrostatic cone 11 at the desired elevation. The screen is of sufliciently large mesh to pass the oil droplets freely, and it is possible to adjust the voltages and spacing between the screen 60 and the annular edge 18 of the cone so that as the oil droplets approach the screen opening, the charge thereon is reversed so that the wire in the screen repels the droplets and prevents im pingement of them on the wire itself, while the momentum of the droplets helps to carry them through the screen and into the combustion zone.

Referring now to FIG. 5, the embodiment of the atomizer illustrated therein comprises a discharge head 70 in which the film-forming surface 72 is the upper face of a disk 74 of electrically conducting material. The peripheral edge 76 of the disk is made sharp to increase the concentration of electrical charge there.

An element 78 of porous material, such, for example, as a porous sintered metal structure, is secured to the center of the disk, and the conduit 16 delivers the liquid fuel to be atomized to the element 7 S.

The porosity of the element 78 is chosen to permit the liquid fuel to flow through it and exit from around its entire circumference and on to the surface 72 in regulated amounts in accordance with the quantity of the liquid fuel supplied through the conduit 16. A sintered bronze of approximately 25 to 50 micron porosity has been found satisfactory for this purpose for use in atomizers of the capacity required for home heating furnaces. The liquid issuing from the element 78 is spread over the surface 72 in the form of a film.

A ring electrode 20 is positioned below and concentric with the disk 74. The discharge head 70 and electrode 20 are connected in an electrical circuit in the manner indicated for the embodiment illustrated in FIG. 1 and operate to atomize the liquid fuel through the operation of the electrostatic field created between the disk 74 and the electrode 20 as described heretofore.

It may be noted that for the purpose of this invention the physical shape of the film-forming surface is not critical to the proper functioning of the apparatus provided this surface produces film-like amounts of liquid with sutflcient electrical charge to be drawn off from an edge of the surface in atomized form through the interaction of an electrode adjacent to but spaced apart from this edge.

While this invention has been described in connection with preferred embodiments thereof, it is to be understood that the atomizing head and electrode may be employed in various furnace arrangements and with various flame stabilizing means, and that other modifications and improvements to the apparatus may be made without departing from the concept of this invention, the scope of which is defined by the claims :appended hereto.

I claim:

1. An electrostatic atomizer for liquids comprising a discharge head for a liquid to be atomized, means for delivering said liquid to said head, an electrode positioned adjacent to and spaced apart from said head, an electrical circuit including said head and said electrode as terminal electrodes, a source of continuous direct current potential connected to said head to maintain said head at a continuous direct current potential, a source of alternating current potential connected to said electrode, the difference in potential between said head and said electrode cyclically varying an amount sufficient to cause said liquid to be drawn in atomized form from said head during alternate half cycles of the alternating current potential of said electrode.

2. An electrostatic atomizer for liquids comprising a discharge head for a liquid to be atomized, said head formed with at least one thin edge of electrically conductive material, flow means for conducting said liquid to said head at said edge, an electrode disposed in adjacent parallel relationship to and spaced apart from said edge, an electrical circuit including a source of continuous direct current potential connected to said head to maintain said edge continuously at a direct current potential and a source of alternating current potential connected to said electrode, the difference in potential between said edge and said electrode cyclically varying an amount sufficient to cause said liquid to be drawn in atomized form from said edge during alternate half cycles of the alternating current potential of said electrode.

3. An electrostatic atomizer for liquids comprising a discharge head having a surface to receive a liquid film thereon and with said surface terminating in a substantially sharp peripheral edge of electrically conducting material with said edge disposed in a plane, an electrode positioned adjacent to said edge and disposed in a plane ,in substantially parallel relationship to and spaced apart from the said plane of said edge, means for depositing a film of liquid on said surface, means for conducting said liquid to said edge, and an electrical circuit including said head and said electrode as terminal electrodes and comprising a source of continuous direct current potential connected to said head and a source of alternating current potential connected to said electrode, the difference in potential between said head and said electrode cyclically varying an amount suificient to cause said liquid to be disengaged in atomized form from said edge during alternate half cycles of the alternating current potential of said electrode.

said edge, an electrode in the form of a ring disposed in a plane in adjacent parallel relationship to the said plane of said edge and spaced apart from said edge, a source of direct current potential connected to said surface and maintaining said surface continuously at a direct current potential, a source of alternating current potential connected to said ring, the difference in potential between said edge and said ring cyclically varying an amount sufficient to cause said liquid to be drawn in atomized form from said edge during alternate half cycles of the alternating current potential of said electrode.

5. A11 electrostatic atomizer comprising a discharge head for a liquid, said discharge head having an external conical liquid flow surface of electrically conductive material and arranged with the axis of said conical surface upright and said conical surface diverging downwardly and terminating in a substantially sharp lower edge, liquid flow means adapted to distribute a liquid around said conical surface above said lower edge, said flow surface conducting said liquid to said edge, a source of direct current potential connected to said conical surface and maintaining said surface continuously at a direct current potential, an electrode in the form of a ring spaced adjacent to and below said lower edge with the axis of said ring in coaxial alignment with the said axis of said conical surface, a source of alternating current potential connected to said ring, the difference in potential between said edge and said ring cyclically varying an amount sufiicient to cause said liquid to be drawn in atomized form from said edge during alternate half cycles of the alternating current potential of said ring,

6. An electrostatic atomizer comprising a discharge head including a base of electrically conductive material, said base having an external conical surface arranged with the axis thereof upright and terminating in a lower edge disposed in a horizontal plane at the maximum diameter of the cone, a holder for said base, said holder having an internal annular surface narrowly spaced from said external conical surface to provide an annular flow port therebetween, means for supplying liquid to said flow port to flow over said conical surface and to said lower edge, a source of continuous direct current potential connected to said base and maintaining said base continuously at a direct current potential, an electrode in the form of a ring disposed in a horizontal plane spaced below and in parallel relationship to the said plane of said lower edge and with said ring in coaxial relationship with the axis of said cone, a source of alternating current potential connected to said ring, the difference in potential between said edge and said ring cyclically varying an amount sufficient to cause said liquid to be drawn in atomized form from said edge during alternate half cycles of the alternating current potential of said ring.

7. A fuel burner comprising a furnace chamber, a discharge head for a liquid fuel in said furnace chamber, said discharge head having an external conical liquid flow surface terminating in a lower edge at the maximum diameter of said conical surface, means forming flow ports adapted to distribute a liquid fuel around said conical surface to flow to said lower edge, said flow surface being of electrically conductive material, conduit means for delivering liquid fuel to said flow ports, a source of direct current potential connected to said conical surface to maintain said surface continuously at a direct current potential, an electrode ring spaced below and adjacent to said lower edge, a source of alternating current potential connected to said electrode ring, the potential difference between said edge and said ring cyclically varying an amount sufficient to cause said liquid to be drawn in atomized form from said edge during alternate half cycles of the alternating current potential of said ring, and means for directing a current of air through said chamber.

8. A fuel burner comprising a furnace chamber having an atomizing zone and a combustion zone, a discharge head for a liquid fuel in the atomizing zone of said furnace, said discharge head having an electrically conductive external conical flow surface for said liquid fuel and arranged with its axis upright and terminating in a lower edge with said lower edge disposed in a plane at the maximum diameter of the cone, means forming flow ports adapted to distribute said liquid fuel around said conical surface to flow toward and onto said lower edge, conduit means for delivering liquid fuel to said flow ports, a source of direct current potential connected to said discharge head, an electrode ring positioned in a plane disposed in spaced-apart parallel relationship to the plane of said lower edge and with said ring in coaxial alignment with the axis of said conical surface, a source of alternating current potential connected to said electrode ring, an air bloiwer communicating with said furnace chamber to direct a current of air through said furnace chamber, flame stabilizing means separating said atomizing zone and said combustion zone, the potential difference between said edge and said electrode ring cyclically varying an amount sufiicient to cause said liquid fuel to be disengaged in atomized form from said edge during alternate half cycles of the alternating current potential of said electrode ring.

9. A fuel burner comprising a furnace chamber having an atomization zone and a combustion zone, a discharge head for a liquid fuel in said atomization zone, said disge head formed with a substantially thin discharge edge, conduit means for delivering liquid fuel to said aaeaaae discharge head to be discharged at said discharge edge, a source of continuous direct current potential connected to said discharge head, an air blower directed to discharge air into said furnace chamber, a metallic screen of suitable mesh to pass fuel droplets placed adjacent to and spaced apart from said edge in parallel relationship therewith and separating said atomization and said combustion zones, a source of alternating current potential connected to said screen, the potential difierence between said edge and said screen cyclically varying an amount sulncient to cause said fuel to be drawn from said edge in atomized form during alternate half cycles of the alternating current potential of said screen.

16. An electrostatic atomizer for liquids comprising a discharge head, a horizontally disposed disk of electrically conductive material on said discharge head and having an upper surface formed thereon, said disk having a substantially sharp peripheral edge, said edge disposed in a horizontal plane, means for conducting a liquid to said discharge head, means for distributing said liquid over the said upper surface of said disk to flow to said peripheral edge, an electrode in the form of a ring disposed in a plane in adjacent parallel relationship to and spaced below the said plane of said peripheral edge and with the axis of said ring in alignment with the axis of said disk, a source of continuous direct current potential connected to said disk, at source of alternating current potential connected to said electrode, the difference in potential between said edge and said ring cyclically varying an amount suflicient to cause said liquid to be drawn in atomized form from said edge during alternate half cycles of the alternating current potential of the said ring.

References Cited by the Examiner UNITED STATES PATENTS 2,525,347 10/1950 Gilman 3173 2,893,893 7/1959 Crouse 158-28 3,167,109 1/1965 Wobig l5828 JAMES W. WESTHAVER, Primary Examiner.

Claims (1)

1. 7. A FUEL BURNER COMPRISING A FURNACE CHAMBER, A DISCHARGE HEAD FOR A LIQUID FUEL IN SAID FURNACE CHAMBER, SAID DISCHARGE HEAD HAVING AN EXTERNAL CONICAL LIQUID FLOW SURFACE TERMINATING IN A LOWER EDGE AT THE MAXIMUM DIAMETER OF SAID CONICAL SURFACE, MEANS FORMING FLOW PORTS ADAPTED TO DISTRIBUTE A LIQUID FUEL AROUND SAID CONICAL SURFACE TO FLOW TO SAID LOWER EDGE, SAID FLOW SURFACE BEING OF ELECTRICALLY CONDUCTIVE MATERIAL, CONDUIT MEANS FOR DELIVERING LIQUID FUEL TO SAID FLOW PORTS, A SOURCE OF DIRECT CURRENT POTENTIAL CONNECTED TO SAID CONICAL SURFACE TO MAINTAIN SAID SURFACE CONTINUOUSLY AT A DIRECT CURRENT POTENTIAL, AN ELECTRODE RING SPACED BELOW AND ADJACENT TO SAID LOWER EDGE, A SOURCE OF ALTERNATING CURRENT POTENTIAL CONNECTED TO SAID ELECTRODE RING, THE POTENTIAL DIFFERENCE BETWEEN SAID EDGE AND SAID RING CYCLICALLY VARYING AN AMOUNT SUFFICIENT TO CAUSE SAID LIQUID TO BE DRAWN IN ATOMIZED FORM FROM SAID EDGE DURING ALTERNATE HALF CYCLES OF THE ALTERNATING CURRENT POTENTIAL OF SAID RING, AND MEANS FOR DIRECTING A CURRENT OF AIR THROUGH SAID CHAMBER.

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