US3361365A

US3361365A - Oil burner head

Info

Publication number: US3361365A
Application number: US388250A
Authority: US
Inventors: Wilson D Dysart; William J Zollinger
Original assignee: Union Oil Company of California
Current assignee: Union Oil Company of California
Priority date: 1964-08-07
Filing date: 1964-08-07
Publication date: 1968-01-02
Anticipated expiration: 1985-01-02

Description

1968 w. D. DYSART ETAL 3,351,365

OIL BURNER HEAD Filed Aug. 7 1964 2 Sheets-Sheet l E q; IJ

8k m u x UL) H? in:

F'I.l

INVENTORS. WILSON D. DYSART WILLIAM J. ZOLLINGER AT TORNE Y.

1968 'w. D. DYSART ETAL 3,361,365

OIL BURNER HEAD 2 Sheets-Sheet 2 Filed Aug.

INVENTORS.

WILSON o. DYSART BY WILLIAM J. ZOLLINGER ATTORNE;

United States Patent 3,361,365 OIL BURNER HEAD Wilson D. Dysart and William J. Zoliinger, Crystal Lake,

Ill., assignors, by mesne assignments, to Union Gil Company of California, Los Angeles, Calif, a corporation of California Filed Aug. 7, 1964, Ser. No. 388,250 15 Claims. (Cl. 239-4825) This invention relates to burners for hydrocarbons and more specifically relates to an oil burner head of unique configuration whereby efficient combustion is obtained and the noise level during burner operation is lowered. Additionally this invention provides a simplified, easily installed unit with which existing oil burner assembles may be converted to obtain greater efficiency and substantial abatement of soot deposits on the furnace and on burner parts.

It is well appreciated by those skilled in the industry that considerable difficulty has been experienced in providing a burner which can operate efiiciently at optimum conditions in a manner which is conducive to peace and quiet normally required in the average dwelling. While it has been possible to an appreciable extent to modify burner head assemblies so as to gain maximum combustion efiiciency or heat content from the fuel utilized, it has not always been possible to construct a highly eflicient apparatus which is mechanically simple in design, eflicient in operation, and able to perform at a reasonably low noise level.

While the invention is operable in conjunction with any type of hydrocarbon fuel such as oil or gas, the description herein will be simplified by reference to the generally understood type of oil burner using mechanical atomization.

It is an object of this invention to provide a burner head apparatus in which air and fuel may be more efiiciently mixed than has heretofore been possible and in which the control and adjustment of the mixture will present no particular problem.

A further object is that of furnishing a burner head unit which will embody relatively few parts, each individually simple and rugged in construction and capable of operating over long periods of time with substantial freedom from difiiculties.

Another object of this invention is that of providing an assembly capable of ready association with prior art oil burners whereby the efiiciency of the oil burner is improved, deposition of soot is mitigated and the noise level under which it operates substantially reduced.

Various meritorious features of the invention will become apparent from the following description taken in conjunction with the drawings wherein like numerals refer to like parts throughout the several figures and wherein:

FIGURE 1 is a side elevation, partly in section, diagrammatically showing part of a conventional oil burner assembly embodying the improved head;

FIGURE 2 is a side elevation showing one part of the combination of the herein disclosed invention that may be utilized in pre-existing oil burners;

FIGURE 3 is an end view of the apparatus depicted in FIGURE 2;

FIGURE 4 is a sectional view taken along 4-4 of FIGURE 2;

FIGURE 5 is a sectional View taken along 5-5 of FIGURE 4.

FIGURE 6 is a sectional view taken along 6-6 of FIGURE 4 and;

FIGURE 7 is a sectional View taken along 7-7 of FIGURE 4.

Basically the novel burner head consists in the comthe line the line the line the line "ice bination of two elements. The first is an annulus or endcone having an outlet end, adapted to be connected to a furnace combustion chamber, of smaller inside diameter than the inlet end. The interior surface is grooved or vaned to impart rotational movement to fluids passing therethrough. A second element or air-shield, an embodiment of the invention by itself, is at least partially disposed within the interior of the annulus. This element is a hollow truncated cone having its largest end extending into the larger inlet end of the annulus. The airshield has a series of tapered slots, similar in shape to a right triangle with the base of the triangle being adjacent to the smaller end of the air-shield. Guide means on the exterior surface adjacent and coextensive with the slots provide means by which fluids are introduced into the interior of the air-shield and caused to follow a rotational path conforming to that of the fluids passing through the annulus. Means by which the air-shield may be aligned and fastened in substantially rigid relationship within the annulus completes the apparatus.

Referring specifically to FIGURE 1 wherein the more important elements of a conventional oil burner head assembly are schematically illustrated, the numeral 10 designates the wall of a combustion chamber provided with aperture 12 into which is placed the oil burner blast tube 14 having secured to the end thereof annulus 16. Annulus i6 is a cylindrically shaped member having a spirally vaned interior surface with vanes 20 extending from the inlet side 22 to the outlet end 24. The interior diameter of outlet end 24 of annulus 16 is of somewhat smaller diameter than the interior diameter of inlet end 22. The annulus may be of cast-iron with the ribbing or vanes an integral part thereof, or, alternatively, grooves may be machined on the interior surface of a smooth cast annulus in order to provide raceways 18 through which fluids entering the intake end 22 are passed through the interior of the annulus 16 to the outlet end 24 Where by the fluids are given rotational movement into combustion zone 26. Disposed inside annulus 16 is hollow air-shield 28 having a truncated conical configuration or being cup-like in appearance with the largest diameter of the air-shield being substantially equal to the smallest diameter of the annulus. The air-shield is slidably disposed within the annulus with the larger end thereof entering through the larger end of the annulus and movable toward the smaller end thereof. Air-shield 28 has a number of equally spaced triangular-shaped slots 30 in the conical wall thereof communicating the exterior surface of air-shield 28 to the interior of annulus 16. The slots or apertures 30 are tangential to the smallest diameter surface 32 of the airshield and have shapes similar to right triangles. The greatest Width of the slots is adjacent the smallest diameter of the air-shield. The slots extend a suflicient distance towards the largest or flared end of the air-shield and are of such size so as to permit a sufficient amount of combustion supporting fluid and fuel to be passed therethrough into the interior of the air-shield for effective combustion. The tapered slots have a maximum width of approximately to /s inch and taper to a point near the flared end of the airshield. The length of the slot may be any size, i.e., coextensive with the length of the air-shield, and is limited only by air-shield structural considerations. That is if either the tapered end or widest end of the tapered slot is too near the largest or smallest end of the air-shield respectively, flexibility and structural weakness will resuit in the air-shield. The size of the slots should preferably allow between about 4% and 30% of the amount of air needed for combustion to flow therethrough. Thus, where a six louvered air-shield is used in conjunction with an efiicient blower fan, the amount of air passing through the louver will be about 24% of the total needed for efficient combustion whereas this percentage will decrease as the inefliciency of the blower fan increases.

Juxtaposed to slots 30 are fluid guide means 34 projecting outwardly from the exterior surface of the airshield. Guide means or fins 34 have a louver configuration substantially corresponding to the contour of the exterior surface of the air-shield so that fluids passing over the exterior surface of the air-shield will pass through slots 30 and enter the interior of the air-shield in a spiral fashion, the rotation of the fluids being substantially the same as the rotational movement given the air passing through the annulus. The fin or guide means are coextending in length with the slots and have a proiection height of about to inch with a preferable height of about inch for the normal domestic burner.

Ordinarily, however, the projection height will generally approach the same dimension as the greatest width of the slot. Air-shield 28 is fashioned of a relatively thin corrosion resistant metal such as stainless steel of about 14 to 28 gauge and has a substantially smooth interior and exterior surface except for projecting fins or guides 34. While the slots may be punched out of the air-shield and separate spirally shaped fins or air guide means secured adjacent the slot on the exterior surface of the air-shield, it is preferred to make two cuts in the air-shield with the subsequent bending out of that portion of the conical wall congruent with the slot to form the louver design as illustrated. It is preferred to space the slots at intervals of about 60 around the periphery of the shield but smaller or greater spacing may be used. One end of support means 36, preferably formed of bent metal rods is secured to the exterior surface of the air-shield as by spot welding or silver brazing. The other end of supporting members 36 are secured to coupling 42 adapted to be slidably disposed on nozzle adapter 44 or fuel pipe 46. The supportin members 36 may be of any shape so long as they are fashioned to provide ample clearance for ignition electrode 38 and atomizing nozzle 40. Sufficient clearance between nozzle 48 and nozzle adapter 44 is provided so that coupling 42 is movable axially thereof thereby allowing air-shield 23 to be freely slidable within end-cone 16. Coupling 42, after setting, is held in fixed position at any predetermined position by means of set screw 47. Alternatively, and preferably, the distance between the back end of the air-shield and nozzle orifice fixed and placement of the airshield within the annulus is accomplished by moving the nozzle, nozzle adapter and air-shield as a unitary structure thusly maintaining a pre-selected fixed distance between the nozzle orifice and back-end of the air-shield. Although a preferred method has been illustrated, the air-shield may be supported within the annulus by other means, as by supporting means secured to the blast tube, nozzle, oil supply conduit, annulus, etc.

In operation air is forced through blast tube 14, by means not shown, towards the combustion chamber and depending upon the position of air-shield 28 within annulus 16, a portion of the air necessary for combustion enters the annulus 16 and passes into combustion zone 26 in a turbulent fashion, rotational movement being given the air by ribs or vanes 20. The amount of air entering the combustion chamber through the annulus will of course depend upon the position of air-shield 28 within the annulus. Another portion of the air will impinge upon the exterior surface of air-shield 28 and will be diverted, in similar rotational manner as the air pass ing through annulus 16, by fins 34 through slots or apertures 34) into the interior of air-shield 28. Another portion of air will be admitted through the open back end of air-shield 28 along with atomized fuel delivered under pressure through fuel pipe 46 through atomizing nozzle 40. Packing material 43 and 50 is provided around the blast tube 14 at the combustion chamber wall so that atmospheric air is not drawn into combustion zone 26 Referring to FIGURE 2, there is depicted the novel unitary air-shield 28 which may be used in pre-existing burners with or without the type of annulus heretofore described. In this embodiment a different type of supporting structure for the air-shield is provided. The supporting members 36' in this instance are three obliquelybent rods. However, it is to be understood that these members may take any configuration so long as they do not interfere with the nozzle head or ignition electrode of the oil burner apparatus.

Referring to FIGURE 3 the louver design of the slots or apertures 30 is readily apparent. While six louvers have been shown 60 apart, the apparatus is not to be so limited in that the benefits of this invention may be obtained by using fewer slots although it has been found that six louvers provide the necessary combustion efiiciency, cleanliness and noise level reduction.

Referring to FIGURE 4 it is apparent that each of the fluid guide means 34 project outwardly from the exterior surface of the air-shield 28 and has its greatest projection at the smallest diameter of the air-shield finally tapering into the contour of the exterior surface of air-shield 28.

The spiral-shape in conformance with the contour of the give the incoming air passing into the interior of the conically shaped air-shield a clockwise or counterclock wise rotational movement. However, if the ribs or vanes of the annulus impart a clockwise rotational movement to the air, the fins 34 of the air-shield 28 should likewise impart a similar movement to the fluids entering into the interior of the air-shield.

The relative sizes of the end-cone and air-shield will of a course depend on the size of ofl burner unit in which they ar to be installed. While reference has been made to the smaller type of unit commonly found in residential use,

the hereinbefore described apparatus will also find industrial utility. Thus where the invention is to be utilized on a domestic type burner having a 34% inch blast tube with a fuel delivery rate of about 2.5 g.p.h., and a fan of adequate size to furnish the necessary amounts of combustion air, the end-cone will normally have an exterior diameter suflicient in size to accommodate the blast tube and an outlet interior diameter of about 2%. The overall length of the annulus will be about 1 /2 inches and the ribs or vanes on the interior surface will generally have a crest height of about /2 inch and have a pitch of about 5". The air-shield of 22 gauge stainless steel will have a flared-end exterior diameter of about 2 /1" with the opposite end having an exterior diameter of about The conical surface will form about a 45 angle with respect to a plane normal to the end surfaces of the airshield and should preferably have at least six louvers 60 apart. The crest height of each louver measured from the exterior surface of the air-shield will generally be about and the length of each louver will generally be about 1 the slot or aperture length being about less than the louver length.

In operating an oil-burner employing our improved head the air-shutter will generally be in the full open position thereby necessitating air flow regulation by placement of the air-shield within the annulus. The amount of air entering the combustion zone through the annulus or around the outer surface of the air-shield will generally be between 2060% and will preferably be regulated solely by the placement of the air-shield within the annulus so as to have clean combustion with a minimum of excess air. As heretofore pointed out the amount of combustion air entering the combustion zone through the slots in the air-shield will generally be between about 430% while about 20-60% will enter the open back-end of the airshield along with atomized fuel. However, the amount of combustion air entering through the open back-end of the air-shield is ideally about 40% of the total amount of air needed for clean combustion.

In the average domestic burner the air-shield will be placed about in front of the atomizing nozzle for optimum efiiciency and quiet operation. However, the exact placement of the air-shield will depend upon the type of end-cone in which it is disposed and upon the spray pattern, and orifice opening of the nozzle. The number and size of slots in the air-shield will also affect placement of the air-shield and will influence efliciency to some extent. It has been found that the larger the slots, within practical ranges, the greater the noise reduction will be. However, an increase in slot size will tend to promote incomplete combustion and thusly contribute to inefiicient smoke control. The number of slots in the air-shield has been found to directly affect carbon deposits on the interior surface of the air-shield. A cleaner air-shield interior will be possible by the provision of additional slots thereby making frequent cleaning unnecessary. A satisfactory optimum will generally be reached with the provision of at least six equally spaced slots in the air-shield. The air-shield thus controls to a certain extent the volume and direction of a part of the combustion air, will rotate the air for better mixing with the fuel and will control early vaporization and combustion of the fuel to provide a stable flame. It has been unexpectantly found that the temperature of the air-shield of our invention is higher than the conventional air-shield under identical operating conditions. Thus, any foreign organic matter which ordinarily would partially block the slots or apertures of the conventional air-shield is effectively burned ofl on the air-shield of this invention thereby eliminating the necessity of frequent cleaning.

A series of noise-reduction tests was conducted wherein the apparatus of this invention was compared to other prior art burner heads. The test procedure consisted in the placement of a microphone, connected to a soundlevel meter, approximately two feet from the front of an average furnace having a gun-type oil burner. The microphone was secured in place so that the same furnace to microphone distance would be maintained for the entire series of tests. Each of the hereinafter described burner head assemblies were tested under substantially the same conditions. That is the burner was operated under like conditions and smoke level readings taken, prior to noise level recording, to ascertain that substantially the same conditions existed for each of the tests. In order to obtain the most practical data, a filter network was employed in conjunction with the noise recording instruments so as to filter out those sounds having frequencies below 200 c.p.s. since generally those sounds having a frequency above 200 c.p.s. are the most annoying and undesirable in furnace operation. 0

The test apparatus consisted in testing varlous component combinations of burner heads under the foregoing conditions. Thus, a full vane end-cone, non-vaned endcone, conventional louver design air-shield, and tapered louver design air-shield were tested in various combinations. The tapered louver air-shield represents the apparatus of this invention heretofore described. The conventional louver air-shield is one having the identical conical configuration of the air-shield of this invention except that the louvers in the airshield are of constant opening width and not tapered as shown in our apparatus. Another significant distinction between the louver designs is that the fin or guide of the conventional louver does not follow the contour of the exterior surface of the air-shield, and bulges at each end of the slot or aperture so as to form a slight recess in the fin or guide surface. A full vaned end-cone is one whose interior surface has spirally shaped grooves or ribs as heretofore described, whereas a nonvaned end cone is one whose interior surface is practically smooth. The following table illustrates the data obtained for the indicated combinations.

Apparatus Vaned Nou- Conven- Tapered Decibels end-cone vaned endtional airlouver aircone shield shield (a) X X 60 59. 3 60. 4 (d) X X 56. 5

It is thusly seen that combination (b) in the above table, representing our invention, produced that lowest operating noise level. It is noteworthy that a diflerential of approxim-atetly three decibels is equivalent to about a 50% reduction in noise level. The results of similar tests on at least six different furnaces substantiated the noise reduction capabilities of our apparatus.

While theoretically a stoichiometric amount of air or oxygen need only be furnished to realize complete combustion of a fuel, it is necessary to avoid smoke or soot deposition to provide an additional amount or excess of air or oxygen because of inefiicient mixing of fuel and air. This additional air is excess combustion air and can be determined by analyzing flue gases for carbon dioxide. The amount of excess combustion 'air influences heating plant efficiency since this additional amount of air lowers the flame temperature, which reduces the ability of combustion product gases to transfer their heat in the heat exchanger portion of the heating plant, and increases the volume of combustion products thereby producing inefiicient heat transfer due to a greater volume of gases passing through the exchanger too rapidly. Thus it is desirable to keep the amount of excess air to a minimum consistant with low smoke levels.

A series of tests was conducted in order to ascertain the eflectiveness of our improved burner head assembly. A conventional furnace was equipped with a gun-type oil burner and various burner head designs were tested under similar conditions and the amount of carbon-dioxide in the flue gases was determined by the use of a C0 analyzer. As previously mentioned the percentage of CO in the combustion gases determines the amount of excess air present. Each test consisted in operating the burner under identical smoke level conditions as determined by the con ventional Bacharach smoke testing technique. The results of these tests are tabulated below.

It is readily apparent that the combination of a tapered louver air-shield and vaned end-cone is conducive to elficient combustion since the amount of excess :air is relatively low. While the conventional air-shield rates slightly lower in this respect, the small increase in eificiency is far outweighed by the attendant increase in noise level.

We have described this invention fully and completely with special emphasis upon several preferred embodiments of the invention. We wish it to be understood that within the scope of the appended claims this invention may be practiced otherwise than as specifically described herein.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An oil burner head which consists in the combination including:

(a) an annulus having an air inlet-end and an outlet end, the outlet end being of smaller diameter than said inlet end;

(b) means on the interior surface of said annulus whereby air passing through said annulus is given rotational movement;

(c) a truncated cone-shaped, open ended, hollow airshield, the larger end of which is disposed within said annulus, the diameter of said end being substantially equal in diameter to the outlet end of said annulus;

(d) slots in the wall of said air-shield, said slots having their greatest width adjacent the smallest diameter of said air-shield; and

(e) fluid guide means on the exterior surface of said air-shield adjacent said slots to give rotational movement to fluid passing through said slots in the same direction as air passing through said annulus.

2. A burner head in accordance with claim 1 wherein said air-shield is slidably disposed within said annulus and means to substantially rigidly fix said air-shield within said annulus at a selected point on the longitudinal axis of said annulus.

3. The burner head in accordance with claim 2 wherein the means on the interior of said annulus to impart rotational movement to said air are spirally shaped ribs extending from the inlet to the outlet ends of said annulus.

4. The burner head in accordance with claim 3 wherein said ribs are adapted to give a clock-wise rotational movement to said air as viewed from a point in front of and exterior to said outlet end.

5. The burner head in accordance with claim 4 wherein said fluid guide means on the exterior surface of said air-shield are projecting, tapered fins, the plane of each fin substantially corresponding to the contour of the exterior surface of said air-shield, and the ends of said fins coincident with the smallest diameter of said air-shield having the greatest projection height with respect to the exterior surface of said air-shield.

6. The burner head in accordance with claim 3 wherein said fluid guide means on the exterior surface of said air-shield are louvers formed by bending outward from the exterior surface of said air-shield that portion of the wall of the air-shield congruent with said slots, said louvers substantially corresponding to the contour of the exterior surface of said air-shield.

7. The burner head in accordance with claim 5 wherein said air-shield has six equi-distant louvers.

8. The burner head in accordance with claim 7 wherein said louvers extend substantially from the smallest diameter to the largest diameter of said air-shield.

9. The burner head in accordance with claim 8 wherein said means to rigidly fix said air-shield within said annulus are obliquely bent members, the oblique short end of said member being fastened to the exterior surface of said airshield and the other end being connected to a coupling fashioned to be slidably disposed on the oil supply conduit of the oil burner, and means to secure said coupling to said conduit.

10. The burner head in accordance with claim 9 wherein said annulus and air-shield are disposed adjacent to and forwardly of the atomizing nozzle connected to said oil supply conduit.

' 11. Apparatus for burning hydrocarbon fuel discharged under pressure from an atomizing nozzle attached to the end of a fuel supply conduit comprising a burner head having a hollow annulus with an inlet end and an outlet end, said inlet end adapted to be disposed adjacent to and forwardly of said nozzle, said outlet end adaptedto communicate with a combustion chamber, theinterior.

diameter of said outlet end being of smaller diameter than said inlet end, the interior surface of said annulus having spirally shaped grooves suflicient in depth to provide raceways for fluids passing throughthe interior thereof whereby rotational movement is imparted to said fluids;

a truncated, cone-shaped, open-ended, hollow air-shield, the larger end of which is slidably disposed within said annulus, the diameter of said end being substantially equal in diameter to the outlet end of said annulus, said airshield having six equi-distant apertures in the conical wall thereof, said apertures being of substantially triangular shape, with their greatest width adjacent the smallest diameter of said air-shield, said apertures being substantially coextensive with the length of said air-shield; outwardly projecting tapered fins, coincident with the exterior contour of said air-shield, on the exterior surface of said airshield formed by bending the conical wall of said airshield, congruent with said apertures, said fins having their greatest projection height adjacent said nozzle and adapted to give rotational movement to fluids passing through the interior of said air-shield in the same direction as the fluids passing through said annulus; means on the exterior surface of said air-shield extending and secured to a movable coupling adapted to be rigidly secured on said fuel supply conduit rearwardly of said nozzle whereby the larger end of said air-shield may be positioned at any predeterminedpoint within said annulus forward of said nozzle.

12. An air-shield for use in oil burner heads comprising an open-ended, truncated, cone-shaped cup the larger end of which is adapted to be disposed within the annulus and forward of the atomizing nozzle of an oil burner, the diameter of said end being substantially equal in diameter to the outlet end of said annulus, said cup having a plurality of tangential slots in the conical wall thereof, each of said slots being tapered and having a substantially triangular shape, the base of the triangle being adjacent the smallest diameter of said cup; tapered fluid guide means on the exterior surface of said cup adjacent said slots, said guide means projecting away from the exterior surface of said cup and substantially corresponding with the exterior contour of said cup whereby fluids passing over the exterior surface of said cup are introduced into the interior of said cup in rotating turbulent fashion.

13. The air-shield in accordance with claim 12 wherein the size and number of said slots are suflicient to furnish at least 5% of the oxygen needed for efiicient combustion.

14. The apparatus of claim 3 wherein said ribs extend outwardly from the interior surface of said annulus to the surface of an imaginary cylinder formed by the axial projection of said outlet opening, the outermost projection of said vanes defining an unobstructed cylindrical passage the length of said body having a diameter equal to the diameter of said outlet opening.

15. The apparatus defined in claim 11 wherein said grooves define ribs extending outwardly from the interior surface of said annulus to the surface of an imaginary cylinder formed by the axial projection of said outlet opening, the outermost projection of said vanes defining an unobstructed cylindrical passage the length of said body having a diameter equal to the diameter of said outlet opening.

References Cited UNITED STATES PATENTS 2,396,867 3/1946 Mason 158-15 3,211,207 10/1965 Luft 158-76 EVERETT W. KIRBY, Primary Examiner.