US3897200A

US3897200A - Cyclonic multi-fuel burner

Info

Publication number: US3897200A
Application number: US447613A
Authority: US
Inventors: Herman T Childree
Original assignee: Howe Baker Engineers LLC
Current assignee: Howe Baker Engineers LLC
Priority date: 1974-03-04
Filing date: 1974-03-04
Publication date: 1975-07-29
Anticipated expiration: 1992-07-29

Abstract

This disclosure describes an apparatus that will burn all types of liquid and gaseous fuels or combinations thereof by an improved method that results in greater efficiencies, stability and control. The simple approach in solving the present problems of burning specific fuels has resulted in a very versatile unit suitable for numerous uses and specifically applicable to burn asphaltic fuel compounds such as pitch and 10 pen Asphalt. The disclosure describes an improved heat exchanger to superheat the atomizing medium and the sonic and/or subsonic vortex of the primary atomizing zone assisted by multiple impingement points and cylconic turbulence and low pressure within the diffuser resulting in micron size droplets of fuel that easily vaporize and greatly improve the reaction process to produce a very efficient flame with fuels ranging down to 3* API.

Description

O United States Patent 1 1 1111 3,897,200

Childree July 29, 1975 CYCLONIC MULTI-FUEL BURNER 57 ABSTRACT [75] Inventor: Herman T. Childree, Tyler, Tex. [73] Assignee: Howe Baker Engineers, Inc Tyler Th1s d1sclosure descnbes an apparatus that w ll burn Tex all types of 11qu1d and gaseous fuels or combmanons thereof by an improved method that results in greater [22] Filed: Mar. 4, 1974 efficiencies, stability and control. The simple appreach in solving the present problems of burning spe- [21] Appl' 4476l3 cific fuels has resulted in a very versatile unit suitable for numerous uses and specifically applicable to burn 431/16 431/285 asphaltic fuel compounds such as pitch and 10 pen [51] Int. Cl. F23D 11/44 Asphalt. The disclosure describes an improved heat Field of Search 43 U exchanger to superheat the atomizing medium and the 431/181, 285, 161, 11, 353, 166 sonic and/or subsonic vortex of the primary atomizing zone assisted by multiple impingement points and cyl- [56] References Cited conic turbulence and low pressure within the diffuser UNITED STATES PATENTS resulting in micron size droplets of fuel that easily va- 1 508 491 9/1924 woods 431/243 X porize and greatly improve the reaction process to 23151482 3/1943 Ferris..1:I:I IQ. 431/163 Produce a Very efficiem flame with fuels ranging down 2,548,485 4 1951 Lubbock 431/243 x to 3,217,779 11/1965 Reed et a1 431/285 Primary Examiner-Edward G. Favors Attorney, Agent, or Firm--Char1es M. Woodward 6 Claims, 4 Drawing Figures PATENTED 3, 897, 20G

SHEET 1 CYCLONIC MULTI-FUEL BURNER BACKGROUND or THEINVENTION This invention relates to a combustion process utilizing novel means that subject the fuel to those specific environments that offer a rapid change from liquid to micron droplets to vapor in conjunction with heat and a water-gas reaction that forms Hydrogen and Carbon Monoxide.

Burner assemblies heretofore usedfor the combustion of liquid and gaseous fuels are numerous and each has a specific application for which it is best suited.

Such present burner assemblies generally use mechanical methods of atomizing the fuel. This requires high fuel pressure in combination with very small openings which result in these openings readily becoming plugged and therefore require a considerable amount of maintenance and steadily degrading efficiency.

A novel feature of the present inventive device is the very large area of the fuel tube permitting ready passage of the type of particles which cause plugging of the fuel passageways in present devices. Another novel feature of the device is the ability to ram the fuel tube without removing the unit from the assembly. Still an other novel feature is the use of suitable valving that permits the heated steam or air, whenever the fuel is off, to be flowed through the fuel tubing to either heat it or strip out any formations.

There have been vast improvements in the burner field resulting primarily from the knowledge gained in the research supporting the aerospace industry. However pollution standards and the decreasing natural gas supply have made it imperative that further improvements be made in order to burn those fuels heretofore generally considered not applicable for combustion or not economically attractive.

One design criteria was to provide an assembly that would require very little maintenance and still not be plagued by the small fuel passageways of state of the art devices that require filters, which are impractical with asphaltic fuels.

Heretofore atomizers of the emulsion type and the external mixing type were used for all fuels even though the fuel droplets were relatively large and therefore required an extended dwell. time in order to vaporize. These atomizers used air or steam as the atomizing medium without any additional heat input. In some cases the atomizing medium offered no additional advantage and at times actually absorbed heat from the fuel.

The device of the present invention provides those environmental conditions that result in a vastly improved method for burning liquid or liquified fuels.

SUMMARY OF THE INVENTION The principal objectives of the present invention are to provide an improved means for burning gaseous and- /or liquid fuels and is specifically applicable to those fuels presently considered not suitable as useful fuels, such as pitch and asphaltic compounds. The use of a novel and improved heat exchanger to super heat the atomizing medium through the heat usually lost by way of combustor wall radiation offers adequate cooling of the combustor and at the same time the absorbed heat is put into the fuel within the atomizer head in such a manner that the atomization of the fuel is greatly improved.

While the device as disclosed herein will be described in its preferred embodiment as a liquid fuel burner assembly, the device is useable as a gaseous fueled assembly, a liquid fueled assembly or a combination gaseousliquid fuel assembly. Various tests have been conducted using propane, butane or natural gas as a gaseous fuel, and as a liquid fueled combustor device. Excellent results have been obtained using naptha, kerosene, 40 APl Crude Oil, Bunker C and Ten Pen Asphalt. In the preferred embodiment, the combustion air is inspirated into the combustor by the kinetic energy of the gaseousfuel or the kinetic energy of the atomized fuel. However, positive air pressure may be directed into the combustor or around the combustor as secondary air. The presently anticipated application for this device will be as a heat source for furnace applications where suitable draft is available to assist in the supplying of the required combustion air. However, this does not suggest nor indicate that the device as disclosed herein cannot be applicable to other uses.

One test condition used saturated steam at 150 pounds pressure (367F) at a demand of pounds per hour for a Ten Pen Asphalt flow of 660 pounds per hour at a temperature of 400F. The heat exchanger superheated the steam to 800F or an increase of 43 3F. The resulting flame of the asphaltic fuel was very efficient and smoke free. Other tests using lower steam pressures and air pressures were documented with similar results.

Therefore, it is the object of this invention to provide an improved burner apparatus. A further object of the invention is to use the kinetic energy of the gas streams to inspirate a portion of the combustion air. Yet another object ofthe invention is to use the kinetic energy of an atomized fuel to inspirate the air for combustion,

Another object of the invention is to provide a combustor with an internal heat exchanger.

Still another object of the invention is to provide a heat exchanger having means to create turbulence and reduce the film coefficient.

A further object of the invention is to increase the dwell time of the medium in the heat exchanger by causing the flowto spiral around the heated wall.

An additional object of the invention is to make use of a circular gaseous fuel ring.

Another object of this invention is to provide spud openings into the fuel ring at an angle that provides the turbulence required to stabilize the combustion, produces the flame shape required and inspirates the correct amount of primary air.

A further object is to provide a primary air register that causes the primary air to enter the combustor in a tangential manner.

An additional object of the invention is to inject water into the bottom of the heat exchanger so that steam may be generated for specific applications.

Still another 'object of the invention is to conduct Liquified Petroleum into the bottom of the heat exchanger in order to vaporize the fuel needed for burner operation.

A further object of the invention is to provide a large area in the fuel tube to pass the foreign particles contained in the fuel.

Yet another object of the invention is to provide a circular ejector at the point of fuel entry into the atomizing zone. This very low or negative pressure lowers the boiling point of some of the elements making up the I fuel in use. These light ends or released gases are easily burned.

Still another object of the invention is to raise the temperature of the atomizing stream to a point where a water-gas reaction will occur when the atomized fuel comes into contact with the high temperature stream to form hydrogen.

A further object of the invention is to make use of the heated energy in the atomizing medium buy combining it with the fuel during the atomizing process.

Yet another object of the invention is to make use of the air or steam velocity to atomize the fuel.

Another object of the invention is to generate a vortex in the air or steam flow.

Still another object of the invention is to make use of those environmental conditions generated by the tangential flow of the air or steam.

A further object of the invention is to generate the tangential flow opposite to the natural vortex north or south of the equator.

Still another object of the invention is to break up the tangential flowing steam or air and fuel by impinging jets of steam or air.

Another object of the invention is to make use of a resonator placed in the flowing steam of air and fuel.

Yet another object of the invention is to provide a turbulator device to generate additional turbulence within the combustor.

The above and other objects and novel features not specifically set forth above will become readily apparent from the following description and accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view showing in cross section an embodiment of the invention.

FIG. 2 is an elevational view showing in cross section one embodiment of the atomizer.

FIG. 2 A is a sectional view of an alternate diffuser providing for impingement of the flow.

FIG. 3 is a cross sectional view of another embodiment of the atomizer head.

DESCRIPTION OF THE EMBODIMENT Referring now to the drawings and particularly to FIG. 1, there is illustrated an embodiment of a burner assembly for carrying out certain objects of this invention wherein is shown a typical furnace floor 10, to which is attached a burner support bracket 12, which carries burner assembly 14 having a ceramic head and hot gas diffuser 16 extending through floor 10, the assembly comprising a heat exchanger 18 having spaced inner and

outer walls

20, 22 with a packing material 24 positioned therebetween and retained by upper and

lower packing retainers

26, 28, retainer 26 forming a communication means with upper manifold 30 which is connected to an atomizing medium supply by port 32. Retainer 28 provides a communication means to lower manifold 34 and atomizing medium exit port 36, conduit 38 and connecting tee 40, to which is connected conduit 42 to carry the heated atomizing medium to the atomizer head 44. Conduit 42 surrounds fuel conduit 46 which also communicates with atom: izer head 44. Atomizer head 44 has an exit nozzle 48 and turbulator 50. A main gas fuel ring 52 having angled ports 54 is connected to a fuel supply by conduit 56. A primary air register opening 58 is provided for the burner. The pilot igniter is shown at 60, and flame sensor viewing tube and sensor at 62, 64 respectively.

The operation of the embodiment as illustrated in FIG. 1 under a typical condition to fulfill a specific requirement can be described assuming that an atomizing mediumis connected to port 32, the main gas conduit 54 is connected to a control valve and the liquid fuel conduit 46 is connected to a preconditioned fuel supply by way of a manual control valve. The pilot ignitor 58 and the flame sensor 62 are not a part of this disclosure and will not be discussed further other than to note that the pilot is lit and the flame is sensed by the sensor which is connected to prescribed safety control system old in the art.

The atomizing medium is pressured into the port 32. Flow is established through port into the manifold 30, through the heat exchanger packing 24 into the bottom manifold 34 by way of the retainer 26, the heat exchanger 18 and the packing support 28. The atomizing medium leaves the manifold 34 by way of the passageway 36 and flows into the atomizer tee by way of the conduit 38. The atomizing medium flows to the atomizer head by way of the conduit 42. The flow of the atomizer medium is around the fuel conduit 46 as it flows toward the head 44. The atomizing medium flows through its respective passageways in the head 44 and establishes a vacuum within the liquid fuel tube 46.

The medium exhausts from the nozzle 48 and into the combustor by way of the turbulator 52. When the atomizing flow has been established the main gas valve is opened and ignition is immediate by way of the pilot flame. As the main flame heats the combustor wall 20 the heat is transferred into the atomizing medium flowing in heat exchanger 18 by the effect of the packing. This packing 24 is of a conductive material such as ceramic or metallic balls or any shape that would move the heat from the combustor wall and place it into better contact with the flowing atomizing medium. This unique construction has a definite advantage in increasing the heat transfer resulting from the turbulence generated in the heat exchanger by non-lineal flow and the elimination of the film coefficient on the heated surface by conduction. The temperature of the atomizing medium continues to increase until a heat balance has been reached. Proper design establishes the final temperature by dictating those areas and velocities required based on the heat radiator and the receiver at a given point or operating condition. Water may be injected to generate steam to serve as an atomizing medium.

When the atomizing medium has reached the proper temperature, the preconditioned liquid fuel is admitted into the conduit 46. The fuel, subjected to the vacuum generated in fuel conduit 46 by the discharge of the surrounding atomizing medium in conduit 42, also receives heat by transfer from the surrounding heated atomizing medium. The lowered pressure resultant from the atomizing medium discharge from the circular ejector, lowers the boiling point of the fuel. thus permitting the light ends in the fuel to boil off at a lower temperature and increasing the efficacy of the heat transfer. As the liquid fuel discharges from the conduit 46 it is subjected to the low pressure resultant therefrom and then the sonic velocity tangential flow. This causes a shearing effect on the molecules of fuel, while the delta pressures of the angled sonic shock waves forming around and immediately downstream of the exit of conduit 46 and, the multiple flow directions existing in the high velocity tangential atomizing medium aid in atomizing and mixing. In addition, the effect of the density transition as the heavy fuel is centrifically forced toward the outer parameter of the tangential flow, causes additional shearing of the liquid. The turbulence generated when the sonic flow changes to subsonic flow also provides additional atomization to produce micron droplets of fuel that greatly reduces the dwell time required for the transition from liquid to a vapor state.

A novel feature of this unique method of atomizing is the direction of the tangential flow of the atomizing medium. The normal vortex direction north of the equator is counterclockwise and south of the equator the normal flow is clockwise. Better atomization is obtained when the vortex is forced in a direction opposite to that of normal flow. This does not suggest or indicate the flow could not be the same direction as the normal flow.

Another important factor and novel feature of the unique method of atomizing liquid fuel is the use of the heated atomizing medium, the high velocity gained by it through heating and the ability of transferring this heat into the fuel.

It will be noted that the combustor is devoid of the usual combustor block. Exhaustive tests have established the fact that such a block is not required with the present novel embodiment. This does not mean that a ceramic could not be used within the combustor if the effect on the heat transfer can be tolerated. It will also be noted that an excess air register is not illustrated. Although the register is necessary in most applications, its usefulness in describing the basic operation of the inventive deviceis not necessary.

The angled gas ports as illustrated in FIG. 1 at 54 perform major functions. The angle has an effect on the turbulence generated in the combustor to hold the gas generated flame front at a specific point within the combustor. Also the angle of these ports greatly effects the mixing of the air and fuel and controls the type of flame entering the furnace when operating on gas only. Likewise, the kinetic energy of these multiple ports inspirates primary air into the combustor. Additional primary air is inspirated by the kinetic energy of the atomizedfuel. The amount of primary air is controlled by the position of the register 58 as it blocks or restricts the flow of air through the port 66.

It is also feasible to provide for an alternate location for main gas injection at the top of the assembly. This may be accomplished by installing multiple angled tubes at a point where they terminate in the combustor so that they pass through the ceramic head and have their inlet on the external surface of the burner shell. Multiple gas nozzles are piped to these inspirator tubes and positioned so that the gas flow from the nozzles will enter the tube and inspirate air. The multiple pipes supplying the nozzles terminate in a suitable manifold. Valving is made available so that the assembly can be started and tested with the fuel ring. When the liquid fuel is ignited the gas is transferred to the top injection point and uses the radiant heat of the oil flame to keep the atomizing medium hot.

When the embodiment is used without the atomizer head it is necessary by proper valving or repiping to direct the flow of main gas through the heat exchanger. Care should be exercised to insure that the temperature does not reach the cracking temperature of the fuel in use.

Likewise, liquified petroleum gas can be directed through the heat exchanger so that it may serve as a vaporizer for the LPG. Liquid propane and butane have been tested and documented with excellent results.

Referring to FIG. 2 there is illustrated an embodiment of an atomizer head wherein 46 is the liquid fuel conduit centrally located within the atomizing

medium conduit

42, 44 is the atomizer head, 48 is the exit nozzle, 68 is the atomizing medium plenium. 70 is the impingement nozzle annulus, 72 illustrates the typical multiple impingement openings, 74 is the diffuser. 76 is the atomized fuel, 78 is the circular nozzle throat, 80 is the primary atomizing, low pressure. and expansion zone, 82 is the tangential generating slot directed to cause the generation of a vortex opposite to the natural vortex, 84 is the vortex generating plate and 46A illustrates an alternate location for the fuel conduit.

In operation the atomizing medium is flowing through conduit 42 and fuel is flowing down conduit 46. This method insures adequate tracing for specific applications. The flow of the atomizing medium enters the plenum 68 and the flow is divided into the number of flow paths, on an area ratio basis, that is required for the specific head design. One path ratio is through the annulus 70 where it communicates with the multiple impingement nozzles 72. These are terminated in the wall of the diffuser 74, however, the sonic flow, although warped by the angled exit, forms an impingement point within the diffuser. Another path for the atomizing medium is through the tangential slot 82 that is located in the swirl plate 84. As the atomizing medium exhausts from the tangential slot 82 a vortex or tangential flow is generated within the cavity 86 having a swirl opposite in direction to the normal flow. As the transition section 88 of vortex cavity 86 becomes smaller the vortex flow velocity is increased until a critical pressure ratio is reached. At this point the flow velocity is sonic. As the rotating atomizing medium leaves the nozzle 78 formed by the fuel tube 46 and the head 44 sonic shocks are formed as the compressed atomizing medium attempts to shock down to subsonic velocities. These shocks are circular and angled corresponding to the tangential flow. Also at the center of this vortex the pressure is below atmosphere. Likewise, the manner of placing the fuel tube 46 in the center of the opening of head 44 to form an annular nozzle 80 creates in essence a circular ejector. The combination of these phenomena provides an ideal low pressure primary area into which the liquid fuel is deposited. In essence this lowers the boiling point of the fuel depending upon the vapor pressure of those elements that make up the fuel in use. In this primary zone 80 the liquid fuel is subjected to sonic conditions and severe pressure changes that tend to shear the fuel molecules, while the density variations within the atomizing medium and the liquid fuel causes it to be moved toward the outer edge of the vortex where it is subjected to the sonic shocks that continue to cause molecular shear. As the diffuser 74 accomplishes a form of controlled expansion and begins to convert some of the total pressure to static pressure, the atomized fuel is forced into sonic impingement by the multiple flows from the angled nozzles 72 within the diffuser body 74. Any rotational flow is immediately stopped and the mixture is again subjected to the violent action of the impinging sonic jets.

As the atomized fuel is exhausted from the atomizer head through exit nozzle 48, the fuel droplets are in the micron size and quickly convert from liquid to vapor for immediate and trouble free combustion.

A modification of the embodiment of FIG. 2 is illustrated in FIG. 2A. It depicts an alternate diffuser having an action effecting the impingement flow whereby the impingement area is larger, the static pressure is higher and the velocity is greater than sonic. Like reference numbers denoting like parts, 46 is the fuel tube, 244 is the atomizer head, 248 is the diffuser exhaust exit, 270 is the impingement nozzle inlet annulus, 76 is the atomized fuel, 78 is the nozzle throat of

vortex cavity

86, 292 is the impingement nozzle inlet throat and 272 is the impingement nozzle diffuser section. The atomizer operation is identical to that already described except that the expansion of the sonic velocity flow downstream of the throat 292 in the diffuser section 272 is controlled in such a manner that the velocity pressure is converted into static pressure and the velocity is increased above sonic. Although the flow is warped due to the angled exit, the amount of atomizing efficiency is increased.

The atomizer head as illustrated in FIG. 3 is identical to the previous atomizers except it does not have any impingement nozzles nor does it have a diffuser 74.

As illustrated in the figures at 46A is an alternate method of admitting fuel to the atomizer head for specific fuel applications.

The turbulator body 50 is not shown on any of the atomizer heads FIGS. 2, 2A or 3. It is a needed item but is not considered a novel feature and will not be discussed further.

The embodiments as disclosed and described herein have been tested with excellent results on the following fuels using air and again using steam as the atomizing medium. These were naphtha, kerosene, carbon black oil, 40 API crude, 24 API crude, 19 API crude, Bunker C" and Ten Pen Asphalt. The amount of air or steam per pound of fuel required for the present invention was less than normally used in state of the art devices and the preheat fuel temperatures were lower.

From test data and observations the efficiencies during the static firing tests resulted in the following advantages over present known devices.

Less pollution, greater stability, better turndown, and the ability to successfully use those fuels that to date have not been considered as useful fuels.

The ability of the atomizer to form micron droplets makes it very useful for application using fuels that presently require ambient air temperatures. However, the atomizing method as disclosed herein requires less atomizing medium Weight flow per pound of fuel, less fuel pressure and produces greater combustion efficiencies that result in a greater heat release. For some applications the atomizer will pump the fuel by the action of the circular ejector. Test indicate that it is possible to produce an emulsion with the water vapor and fuel oil merely by the effect of the sonic energy within the atomizer. A metered amount of water can be injected into the fuel for additional emulsion water content.

Further studies provide an additional use for atomizing a coal dust slurry. The atomizing feature can easily be modified for oxygen injection for coal dust or other applications.

For specific applications the fuel is caused to flow tangentially as it enters the atomizing head by use of a swirl vane within the fuel tube.

Although particular embodiments of the invention have been illustrated and described, changes and modifications will become apparent to those skilled in the art and it is intended to cover in the appended claims all such changes and modifications as come within the true spirit and scope of the invention.

What I claim is:

l. A burner assembly comprising, in combination. inlet and outlet manifolds, an annular heat exchanger defined by inner and outer walls interposed between and in communication with said manifolds. one wall of said heat exchanger defining a combustor section whereby an atomizing medium flowing through said heat exchanger is heated by transfer of heat from said combustor section through said one wall prior to intro.- duction to an atomizing means, atomizing means for imparting a high velocity tangential vortex to the atomizing medium to react it longitudinally and tangentially on a fuel for aerodynamically mixing the heated atomizing medium intimately with a fuel within said combustor section and to produce molecular shear in the fuel resultant in an atomized fuel having substantially micron size droplets.

2. The burner assembly defined in claim 1 wherein said heat exchanger is packed with a discrete heat conductive material having a shape aiding in the transfer of heat from the said combustor defining wall outwardly into the annulus defined by said walls to impart turbulence to the atomizing medium flow therethrough and thus improve the efficiency of the heat absorption by the medium.

3. The burner defined in claim 1 including, in addition, air register means spaced from but in communication with said combustor section, a gaseous fuel injector ring positioned adjacent the inlet end of said combustor section and interposed between said combustor section and said air register means, said injector ring having spaced parts therein directed inwardly from the vertical whereby the kinetic energy of the fuel gas jets inspirates the primary air for combustion.

4..The burner assembly as defined in claim 1 wherein said atomizing means is centrally located at a point within said combustor so that the atomized fuel is injected in an area where the flame front will be stabilized, said atomizing means comprising an outer conduit in communication with an atomizing head and defining a conduit for the atomizing medium to enter said atomizing head, a fuel tube positioned interiorly of said atomizing medium conduit and extending within said atomizing head to a point wherein a portion of said head and said tube cooperatively define a fuel nozzle, vortex generating means interposed between said atomizing medium conduit and said fuel nozzle and communicating with a vortex cavity defined by a portion of said atomizing head between said vortex generating means and said fuel nozzle, the fuel thus being atom ized by the high velocity vortex generated atomizing medium in the area downstream of said nozzle.

5. The burner assembly as defined in claim 4 wherein said vortex generating means includes a swirl plate interposed between said atomizing medium conduit and the area downstream of said fuel nozzle and opening to the vortex cavity said swirl plate having at least one fines a transition section decreasing in area until the fuel exit nozzle is formed between the atomizer head and the fuel tube upstream of a diffuser section

Claims

1. A burner assembly comprising, in combination, inlet and outlet manifolds, an annular heat exchanger defined by inner and outer walls interposed between and in communication with said manifolds, one wall of said heat exchanger defining a combustor section whereby an atomizing medium flowing through said heat exchanger is heated by transfer of heat from said combustor section through said one wall prior to introduction to an atomizing means, atomizing means for imparting a high velocity tangential vortex to the atomizing medium to react it longitudinally and tangentially on a fuel for aerodynamically mixing the heated atomizing medium intimately with a fuel within said combustor section and to produce molecular shear in the fuel resultant in an atomized fuel having substantially micron size droplets.

4. The burner assembly as defined in claim 1 wherein said atomizing means is centrally located at a point within said combustor so that the atomized fuel is injected in an area where the flame front will be stabilized, said atomizing means comprising an outer conduit in communication with an atomizing head and defining a conduit for the atomizing medium to enter said atomizing head, a fuel tube positioned interiorly of said atomizing medium conduit and extending within said atomizing head to a point wherein a portion of said head and said tube cooperAtively define a fuel nozzle, vortex generating means interposed between said atomizing medium conduit and said fuel nozzle and communicating with a vortex cavity defined by a portion of said atomizing head between said vortex generating means and said fuel nozzle, the fuel thus being atomized by the high velocity vortex generated atomizing medium in the area downstream of said nozzle.

5. The burner assembly as defined in claim 4 wherein said vortex generating means includes a swirl plate interposed between said atomizing medium conduit and the area downstream of said fuel nozzle and opening to the vortex cavity said swirl plate having at least one vortex generating channel therein positioned to cause flow tangentially opposite to the natural vortex.

6. The burner assembly as defined in claim 4 wherein a portion of said fuel nozzle which defines the vortex cavity downstream of said vortex generating means defines a transition section decreasing in area until the fuel exit nozzle is formed between the atomizer head and the fuel tube upstream of a diffuser section.