US3088681A - Atomizing oil burner nozzle - Google Patents

Description

May 7, 1963 w. N. M cuTcHEoN, JR

ATOMIZING on. BURNER uozzm 2 Sheets-Sheet 1 Filed Feb. 1, 1955 INVENTOR. William N. McCutcheon May 7, 1963 w. N. mcu'rcHEoN, JR 3,033,531

ATOMIZING on. BURNER NOZZLE Filed Feb. 1, 1955 2 Sheets-Sheet 2 3,088,681 Patented May 7, 1963 3,088,651 ATOMIZING OIL BURNER NOZZLE William N. McCutcheon, Jr., Crafton, Pa., assignor to Bloom Engineering Company, Inc., Pittsburgh, Pa., a corporation of Pennsylvania Filed Feb. 1, 1955, 521'. No. 485,367 1 Claim. (Cl. 239-427) This invention relates to a new oil burner for industrial furnaces. More particularly, this invention pertains to such a new burner in which the flow of atomized oil may be varied considerably without loss of stability in operation.

In industrial furnace operation utilizing oil burners to heat the furnace interior and work therein or passing therethrough, the achievement of flexible fuel rates and flame stability has always been a problem. Particularly in trying to increase turndown range have such problems arisen and they are especially acute in situations where the combustion air supply to the oil burner is left constant. Moreover, in certain kinds of annealing furnace operations, for example, work is often to be heat treated at one temperature and then after an interim period there is a further heating, often in the same furnace, which may be performed at a lower temperature, as in the case of a drawback treatment. Where such a variation in temperature conditions is to be carried out at different times in the same furnace, on the same or on different workpieces, it is evident that burners which are flexible in terms of fuel turndown ability with consequent variation in temperature, are highly desirable. Heretofore, the oil tumdown range has been quite limited. Hence, if furnace temperature control is sought otherwise as by turning off certain of the burners a loss in uniformity of heating was the result often with consequent detriment to the work being heat treated.

In my new oil burner combination, the foregoing ditficulties have been overcome. Thus, I can achieve a stable flame oil burner operation in industrial furnaces at relatively high turndown yielding relatively low oil rates for a given rating of my new burners. Significantly, relatively great quantities of excess combustion air may be provided at such lower oil rates without disturbing the stability of the flame produced by the burner or the uniformity of any different level of temperature provided by a turndown of such new burners, a plurality of which are usually installed in a single furnace. At turndown rates and with such excess air, my new burners will produce, for example, socalled cold flame on oil for relatively lower temperature operations where such are desired. Further,

my new burner will function effectively as an oil burner alone or it may readily be fabricated in the form of a combination oil and gas burner.

Other objects and advantages of this invention will be apparent from the following description and from the accompanying drawings, which are illustrative only, in which FIGURE 1 is a view in elevation taken on a vertical section through the axis of a preferred embodiment of my new oil burner constructed, for illustration only, in the form of a combination oil and gas burner;

FIGURE 2 is a similar view, somewhat enlarged, at the atomizer tip end of my new burner shown in FIGURE 1 corresponding in plane to a section taken along line II--II of FIGURE 3;

FIGURE 3 is a view of of the new atomizer tip shown in FIGURE 2 looking directly at the inner or furnace end thereof;

FIGURE 4 is a view in section taken along line IVIV of FIGURE 2;

FIGURE 5 is a view of the new burner shown in FIG- URE 1 taken along line VV thereof;

FIGURE 6 is a view in vertical section taken through the axis of a modification of the new atomizer tip shown in FIGURE 2;

FIGURE 7 is a view of the modification shown in FIG- URE 6 looking at the inner end thereof;

FIGURE 8 is a view in vertical section taken through the axis of a further modification of the new atomizer tip shown in FIGURE 2', and

FIGURE 9 is a view of the further modification shown in FIGURE 8 looking at the inner end thereof.

Referring to the drawings, a preferred embodiment of my invention is illustrated in FIGURES l to 5, inclusive. Therein, one of my new burners 10 is shown extending through the side wall of an industrial furnace 11 to heat the interior thereof and work therein usually to a relatively high temperature as in the case, for example, of the heat treating of metal. The furnace walls may be lined with refractory 12 having openings therethrough for refractory port blocks 13 in which such new burners 10 are positioned. The outer face of furnace 11 may be covered with steel plates (not illustrated) with provision for securing the burners 10 thereto.

Port block 13 is provided with a central opening or port 14 flaring toward the interior of the furnace and in axial registry with a mounting opening recess 15 into which a cylindrical lip 16 of burner 10 may extend for mounting purposes. The surface of port 14 constitutes a part of furnace wall 17 and therewith will gcneraliy be heated to incandescence in the course of an operation of a furnace 11 employing my new burner 10.

The generally cylindrical member 16 may be provided with an integral dependent portion 18 the interior of which forms a groove for a pilot light tube 19 extending through an opening 20 in the rear wall of the body 21 of burner 10. Pilot tube 19 may be screwed in that opening as shown. Pilot tube 19 may be provided with a lighting hole 22 for lighting a small pilot stream of premixed air and fuel gas suitable therefor in a manner known to those skilled in the burner art.

Body 21 of burner 10 has an upwardly extending combustion air chamber 23 into which combustion air is admitted through a tapped opening 24 for engagement by a combustion air pipe. The combustion air space 25 within chamber 23 extends downwardly past a battle rib 26 extending across a part of chamber 23 and joins an annular combustion air space 27 the forward or furnace end of which is defined by a flaring partition 23 through which a plurality of combustion air holes 29 extend. Holes 29 have their respective axes in converging generally conical relation to the axis of the new burner. An axial opening 30 extends through burner 10 and at the forward end thereof is in registry with the interior of a nozzle 31 having an inner or furnace end flange 32. Laterally extending flange 32 is provided with a rear face 33 which is preferably flaring in the direction of the furnace.

The position of nozzle 31 is such that the respective axes of the combustion air openings 29 preferably intersect the outer surface of nozzle 31 behind periphery 34 of flange 32. The annular combustion air passage between periphery 34 and the nearest surface outwardly thereof appears to act to retain flame agansit inner face 61 of flange 32 even when the new oil burner is turned down as much as 10 to 1 or more. In the case of a burner having a maximum capacity flow of 5 gallons of oil per hour, a it) to l turndown would reduce that flow to one-half a gallon of that oil per hour. At the same time, under by invention, the combustion air and atomizing air can be left constant at the maximum capacity flow rate without concern for disappearance of the flame or for movement thereof away from inner face 61.

An inner wall 35 surrounds a recess 36 joining the axial openings 30. An oil tube 37 passes, in the illustrated embodiment, through openings 30 and intermediate recess 36 into nozzle 31. The oil tube 37 is coincident with the axis of burner and of nozzle 31. A fitting 38 surrounds the rear end of oil tube 37 and is provided with a flange 39 secured to the rear of body 21 of burner 10. A tapped opening 40 in fitting 38 is adapted to have a pipe screwed thereinto to conduct an atomizing agent for the oil such as atomizing air, usually at a somewhat higher pressure than the pressure of combustion air entering chamber 23, into the interior of fitting 38 and from thence through openings and 36 into the interior of nozzle 31 and around the outside of oil tube 37.

While my invention relates to a new atomized oil burner device, it also may readily be constructed in the form of a combination oil and gas burner. Thus, a tapped opening 62 may be connected to a valved fuel gas pipe to admit such fuel gas to the interior of fitting 38 and nozzle 31 when such burner 10 is to be shifted over to operation as a gas burner. In that case the oil flow to oil tube 37 will generally be cut off and such oil tube may, if desired, be removed by unscrewing orifice member 41, withdrawing both it and oil tube 37 and substituting a plug for 41 in fitting 38. Gas may also be conveyed to the burner by interposing a three-way valve in the pipe connected to opening so that valve can be turned to either admit atomizing air when my new burner is on oil cycle with tube 37 in place, or to admit fuel gas to the interior of nozzle 31 when putting the burner on gas cycle. On either cycle, combustion air enters through openings 29 to form a combustible mixture at flange 32.

When the illustrated burner is on oil cycle, fuel in the form of liquid oil will enter a strainer passage 42 and pass through a union 43 into orifice member 41 which is screwed into a tapped opening in the back of fitting 38. An O-ring 44 may be utilized to seal the connection between member 41 and fitting 38. Member 41 as shown is furnished with a sized orifice passage 45 which extends therein for connection to the entry end of the inside of oil tube 37. Generally a light oil, up through No. 4 grade, will be utilized as fuel particularly if such oil is not preheated. On the other hand, my new burner will work with No. 5 and heavier bunker oils which generally are preheated when used as industrial oil burner fuels. On oil cycle, atomizing air will enter the interior of fitting 38 through opening 40 and pass upwardly through central opening 46 in the forward end of fitting 38 and from thence to the openings 30 and 36 into the interior of nozzle 31 around the outside of oil tube 37. The forward end of oil tube 37 discharges such oil in liquid form, as more clearly shown in FIG URES t2 and 3, into a fuel chamber 47 in my new ato- 4 mizer tip 48.

Atomizer tip 48 in the preferred embodiment is provided with a single central axial opening 49 extending through an internal wall or partition 50. The crosssectional area of oil hole 49 is larger than the crosssectional area of orifice 45, although, if desired, orifice control of the liquid oil being admitted to the burner may be performed by an orifice sizing of oil hole 49 in place of providing such orifice in member 41 in the manner illustrated. At the discharge or forward end of oil hole 49, a cup bore 51 is provided. As shown, the fuel chamber 47, the oil hole 49 and the cup 51 may readily be machined by drilling in forming my new atomizer tip 48. The base of cup 51 may be in the form of frusto-conical surface 52 extending between the edge of oil hole 49 and the greater diameter cylindrical surface portion of cup 51.

Through the sides of tip 48, a plurality of rear atomizing openings 53 are provided. Preferably, the axes of the openings 53 are in tangential arrangement relative to oil hole 49 as may be seen by looking at FIGURE 3. Further, in the illustrated embodiment, the axes of the openings 53 lie in a plane at right angles to the axis of atomizer tip 48 and burner 10. Such rear atomizing openings may also be formed in a radial manner relative to oil hole 49. Further, the axes of the openings 53 may be at any angle other than relative to the axis of tip 48. The inner or discharge ends 54 of open ings 53 are located in the base of cup 51 adjacent the discharge end of oil hole 49.

In addition, a forward set of atomizing openings 55 are also provided in my new atomizer tip. These open ings 55 are illustrated in the form of three-sided radial slots having a bottom 56 and sides 57, the slope of the bottom surface 56 in the illustrated embodiment being at an angle of about 45 to the axis of the atomizer tip 48. Atomizer tip 48 is also provided with a generally conical front face 58 which in the illustrated embodiment is at an angle of about 30 to a vertical plane normal to the axis of tip 48.

Inner surface 58 is positioned so as substantially to seat against a correspondingly sloped interior face 59 in nozzle 31. Discharge through flange 32 is provided for by a central opening 60 extending axially therethrough. Opening 60 is of lesser diameter than the diameter of tip 48 so that the overlapping portions of surfaces 58 and 59 in effect form four-sided passages as the radially outer ends of the forward atomizing openings 55 in tip 48. Hence, when liquid oil is discharged through oil hole 49, it is atomized by atomizing air issuing from the respective sets of openings 53 and 55 and admixes with combustion air admitted through openings 29 in such manner that whether my new burner is running at maximum oil flow or at reduced oil flow, the flame produced will be stable and will remain next to inner face 61 of flange 32 even without change in combustion air supply, or atomizing air supply, or in both. So leaving the combustion air constant means, of course, that with a turndown such as in a new burner, the combustion air supplied when the lower turned-down oil flow rate will be greatly in excess of that needed for theoretical combustion and, yet, such excess air will not disturb the operation of the burner and will actually be advantageous in those cases, for example, where a so-called cold flame of lower temperature is desired.

Withal, my new oil burner has a relatively high capacity for its size. Thus, in such a new burner for a rated capacity at maximum oil flow of about 600,000 B.t.u. per hour, inner face 61 will generally be not more than about 3 inches from the face of wall 28 entered by nozzle 31. And, the diameter of tip 48 need not exceed five-eighths of an inch in diameter and the diameter of the cup need not exceed about one-fourth of an inch. The aggregate cross-sectional area of the rear atomizing openings 53 will generally be less than the aggregate mean cross-sectional area of the forward atomizing openings 55. The sum of the aggregate cross-sectional areas of both sets of openings 53- and 55 will be large enough for the supplying of sufiicient atomizing air (which, for example, may be at one p.s.i.g. and be of a quantity corresponding to as much as ten percent of the quantity of combustion air utilized at maximum oil flow) for all atomizing functions to be performed in the operation of my new oil burner under all conditions of operation.

A modification of my new atomizer tip in my new oil burner combination is illustrated in FIGURES 6 and 7. Therein, parts corresponding generally in construction and in functioning to atomizer tip 48 of FIGURES 2 and 3 are provided respectively with the same reference numetals with the addition of a prime factor thereto. Thus, in the modification of FIGURES 6 and 7, the oil holes 49' are three in number with an aggregate cross-sectional area which would correspond in general to the cross-sectional area of oil hole 49 for a burner of about the same capacity. In the modification of FIGURES 6 and 7, further, the oil holes 49' have their discharge ends intersecting the discharge ends of the rear atomizing agent holes 53' where the first admixture of fuel oil and atomizing air takes place before that admixture meets the second stream of atomizing air supplied by the forward openings 55'.

A further modification of my new atomizer tip is illustrated in FIGURES 8 and 9. Therein, parts corresponding generally in construction and in functioning to atomizer tip 48 of FIGURES 2 and 3 are provided respectively with the same reference numerals with the addition of a double prime factor thereto. The further modification 48" is also like the modification 48 but has four oil holes 49", four atomizing openings 53" and four forward atomizing air admission slots 55".

Various modifications may be made in details of my invention without departing from the spirit thereof and the scope of the appended claims.

I claim:

In an atomizer for a burner for a furnace or the like, said burner having a fixed nozzle with a central discharge opening therethrough, in combination, an oil tube, a unitary cylindrical atomizer tip connected to the end of said oil tube, an oil receiving chamber in the rearward end of said tip, the forward end of said tip being in the general form of a right circular conical frustum, a cylindrical cup in the forward end of said tip extending axially from the interior through the front thereof with the walls of said cup intersecting the conical sides of said frustum, said sides of said frustum comprising alternate sector-like inner face portions and radially extending atomizing medium grooves, said portions being of one slope outwardly and rearwardly and said grooves having bottoms of a steeper slope outwardly and rearwardly around the entire periphery of said sides, said grooves being of uniform Width, the laterally inward edges of said portions and grooves being respectively coincident with the edge of said cup, said portions being adapted to index against the back edge of said discharge opening, a plurality of straight axially extending oil passages providing communication between said chamber and the bottom of said cup, a like plurality of atomizing medium passages extending from the outer cylindrical side of said tip to the bottom of said cup with the axes of said atomizing medium passages intersecting the axes of said oil passages respectively, said axes of said rearward atomizing medium passages being in a plane substantially normal to the axis of said tip and tangential to a circle subscribed around the axis of said tip of a lesser diameter than the diameter of said cup, and means for supplying atomizing medium to said atomizing medium passages and grooves.

References Cited in the file of this patent UNITED STATES PATENTS 1,071,381 Anthony Aug. 26, 1913 1,462,395 Thompson July 17, 1923 1,512,132 Phahl Oct. 21, 1924 1,536,046 Anthony May 5, 1925 1,567,482 Anthony Dec. 29, 1925 2,393,887 Clements Jan. 29, 1946 2,812,212 Rogers et al. Nov. 5, 1957 FOREIGN PATENTS 322,257 Great Britain Dec. 5, 1929 669,368 Great Britain Nov. 4, 1953

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