US2390056A - Oil burner - Google Patents

Description

Dec. 4, 1945. J. c. CLEAVER ET AL OIL BURNER Filed Jan. 9, 1942 5 Sheets-Sheet 1 INVENTOR.

OIL BURNER Filed Jan. 9, 1942 5 Sheets-Sheet 2 Dec. 4, 1945. c. CLEAVEQ ETAL OIL/BURNER Filed Jan. 9, 1942 5 Sheets-Sheet 5 Patented Dec. 4, 19 45 OIL BURNER John C. Cleaver, Whitefish Bay, and Jules Verne t Res'ek, Milwaukee, Wis., assignors to Cleaver- Brooks Company, Milwaukee, Wis., a corporation of Wisconsin Application January 9, 1942, Serial No. 426,138

' 8. Claims.

This invention relates generally to oil burners and especially to an oil burner particularly adapted for use with a multiple pass, horizontal fire tube boiler.

In boilers of this. character, the combustion chamber must be of limited diameter bectuse it is confined to a tube of small diameter. This fact coupled with the fact that a large amount of energy must be obtained from the small diameter combustion chamber creates many problems. These problems are magnified and multiplied by the fact that in multiple pass, horizontal fire tube boilers there is a considerable differential between the pressure of the gases at the entrance and at the exit from the last pass. In order to overcome this pressure loss, it is necessary to introduce the secondary air as well as the primary air at a comparatively high pressure, 1. e., employ forced draft. As a result, in the past, the eiiiciency has been low because the combustion has been improper and incomplete; the boiler has frequently burned out because the combustion was too localized; carbon deposits have been excessive; and in many other respects past constructions have been unsatisfactory.

It is an object of this invention, therefore, to provide a new and improved oil burner particularly adapted for use with a multiple pass, horizontalfire tube, forced draft boiler.

Another object is to introduce air in such manner and in such quantities as to assure complete and thorough combustion of the fuel.

Another object is to provide an oil burner that uniformly distributes the air introduced into the combustion chamber. 7

Another object is to provide an oil burner that gives to the air introduced into the combustion chamber a spiral motion so as to assure thorough mixing of the air and fuel, a longer flame and a whirling flame from which more heat is liberated.

Another object is toprovide an oil burner that introduces air in such manner that eddy currents, carrying the partly combusted fuel particles back upon the burner nozzle and other parts to form carbon deposits, are eliminated.

Still another object is to provide an oil burner that introduces primary air directly about the atomizer to prevent the formation of a sludge and introduces both primary and secondary air uniformly about the entire nozzle and generally inwardly to keep the combustion equally spaced from all sides of the combustion chamber and initially somewhat centralized.

Other objects and advantages will become apparent from. the following detailed description I taken in connection with the accompanying drawings, in which:

Fig. 1 is a view in perspective of an oil burner through the nozzle structure only of the burner.

Fig. 5 is an end view of Fig. 4.

Fig. 6 is a transverse sectional view taken approximately along the line 6-6 of Fig. 7 and showing a modified form of secondary air supply hood.

Fig. 7 is a diametrical sectional view taken approximately along the line 1-1 of Fig. 6.

Fig. 8 is an enlarged view of one element of the hood.

While the invention is susceptible of various modifications and alternative constructions and adaptable for use with various types of boilers, it is herein shown and will hereinafter be described in a preferred form. However, it is not intended that the invention is to be limited thereby to the specific construction disclosed, but it is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention as defined in the appended claims.

As above stated, the oil burner is particularly adapted for use with a boiler of the multiple pass, horizontal tube type. Accordingly, the burner is herein disclosed as applied to a boiler of that construction. Referring particularly to Fig. 1, 5 represents such a boiler, generally cylindrical in shape, mounted upon a suitable base structure 6 which also forms a support for the oil burner, generally designated 1. At its front end the boiler is formed with an outer end wall 8 and an inner end Wall 9 spaced longitudinally of the boiler with respect to the outer end wall. Similarly, at its rear end the boiler is formed with an outer end wall l0 and an inner end wall ll. Extending longitudinally of the boiler approximately centrally thereof is the main or fire tube l2 which opens at its rear end through the inner rear end wall H to the space between the rearend walls of the boiler, and at its forward end passes through both the inner and outer end walls to open outwardly of the boiler for application of the oil-bumer. Also extending longitudinally of the boiler are a first set of tubes l3 on opposite sides of the fire tube l2, a second set of tubes |4 below the maintube l2 and the tubes l3, and a third set of tubes I5 below the tubes [4. The boiler is,-in the spaces between the inner and outer rear end walls and the inner and outer front end walls, provided with suitable baflies l8 and I1 so as to make the main or fire tube 12 the first pass for the heated gases, the set of tubes I3 the second pass, the set of tubes l4 the thirdpass, and the set of tubes IS the fourth pass, the gaseous products of combustion after flowing'through the fourth pass being discharged to the space between the ends 8 and 9 of the boiler below the baffle l1, which space communicates with an exhaust l8.

The fire tube l2, of course, constitutes the combustion chamber and therefore is, over a ortion of its length immediately adjacent the oi burner, provided with a refractory lining l9 to store some of the heat of combustion to expedite combustion and to prevent a burning out of the tube at that point. Preferably, this lining is formed of thin, carborundum tiles, conventional bricks being incapable of withstanding the forced draft of this construction. Further, in order to prevent the fire tube from burning out at this point, it is enclosed in a water jacket 20 which completely surrounds the fire tube and is formed by a tubular member 2| opening at its inner end through and i secured in the inner end wall'9, and extending outwardly through the end wall 8 to the end of the fire tube l2. At its outer end the tubular member 2| terminates in a radially outwardly project- .ing flange 22.

Supplying fuel oil and air to the fire tube I2 is the oil burner, generally designated I. The oil burner is of the centrifugal spray type and is mounted over the front end of the fire tube l2 to discharge fuel oil and air generally horizontally into the fire tube l2. The burner includes means for supplying fuel 011, means for supplying pri- I mary air to aid atomization of the fuel oil, and means for supplying secondary air further aiding in the atomization of the fuel and above all providing the air necessary for combustion. For exemplary purposes, it may be considered that the boiler here shown is of 100-horse power." In such a boiler the fire tube |2 may be assmall as 18 inches in diameter. Oil is supplied to the tube by the burner at the rate of thirty gallons per hour, while secondary air is supplied at the approximate rate of 900 cubic feet per minute. Primary air is supplied at about 5% of the rate of the secondary air, that is, 45 cubic feet per minute.

Inasmuch as the means for supplying the secondary air is connected directly to the tubular member 2| of the water jacket 20 and provides a support for the remainder of the oil burner, it will be described first. This secondary air supply means includes a large blower 25, having a capacity in excess of 900 cubic feet per minute, driven by an electric motor 26. The blower discharges to a hood, generally designated 21, which is formed with an outer peripheral flange 28 and is secured in position bymeans such as. bolts 29 extending through the flanges 22 and 28. The hood 21 comprises annular, radially inwardly extending walls flange portion 34, by means of which it is secured to the. inner wall 30 of the hood 21 through the I medium of bolts or rivets 35, and a longitudinally and somewhat inwardly extending lip portion 38.

5 Incidentally supported by this member 32 is, an

annular refractory material facing 31 for the wall 30. This facing 31 is further retained in position by the fire tube l2 which at its end adjacent the facing "11 is bent radially outwardly to form an annular shoulder 38. A suitable filler 33 is pressed between the facing 31 and the refractory linin l9 at the bend in the fire tube.

The inner member 33 is composed of a first and major part 40 which is securedto the wall 3| of the hood 21 in a suitable manner as by bolts or 0 point 45 so as to have a frusto-conical shape and then inclines outwardly from the point 45. Completing the member 33 is'a second part 46 which is annular and in cross section is generally triangular in shape and is secured by suitable means with its base on the flange portion 43. The maximum diameter of the part 46, like that of the flange portion 43 of the part 40, is somewhat less than the internal diameter of the member 32, and the outer face of the part 48 also slopes somewhat inwardly so as to form with the lip 38 an annular I nozzle passage 41 which is directed somewhat inwardly. The inner face of the part 46 slopes outwardly and constitutes a continuation of the outwardly sloping portion of the part 43, givin to the member 33 a double frusto-conical construc- 4c the bolts 4|, as will later become more apparent.

While the hood 21 is generally annular, the supply of the secondary air is not divided so as to flow in opposite directions about the hood. 0n the contrary, there is interposed in the hood 21 a partition, generally designated 50, composed of a straight portion 5| which extends from the peripheral wall of the hood 21 to the outer periphery of the nozzle passage 41 near the point of reception of the secondary air from .the blower 50 into the hood 21, so as to direct the secondary air circumferentially around the hood in one direction only. The partition 50 includes a second part 52 which is spiral in character and extends from the inner end of the part 5| to the periph- 55 eral wall of, the hood 21 at a. point approximately opposite the inner end of the part 5|. There thus results, as best seen in Fig. 3, a spiraling and gradually tapering passage for the secondary air. The result is that the secondary air is given a 5 whirling motion causing it to be discharged generally tangentially through the nozzle. passage 41 so as to emerge into the fire tube in the form of a whirling cylindrical curtain of air.

The oil burner, as previously stated, is of the 5 centrifugal type and herein comprises a hollow 30 and 3| leaving a comparatively large central shaft is connected in suitable manner Ito-receive opening through the hood.

Mounted in this opening is a construction which forms an air nozzle and is composed oi. an outer annular member 32 and an inner member 33.

- fuel oil from a source under pressure. At its inner end the shaft (see Fig. 4) is provided with a restriction 58- and outwardly of the restriction is formed with internal threads. Threadedly re- The outer member 32 is composed of a radial 7o ce'ived in the end of the tube shaft is a nipple 58 provided with a longitudinal bor or passage 60 of a size conforming generallyto the passage through the restriction 59. The end of the shaft is also formed with external threads so as to receive threadedly thereon a cup 6| forming with the nipple 59 a nozzle for the discharge of fuel oil. The cup has a comparatively thick bottom and a bore centrally of the bottom through which the nipple 59 extends and has a hub portion 62 of somewhat reduced diameter so as to form an external annular shoulder 63. Opening through the base or bottom of the cup at the juncture of the hub and the shoulder 63 are a plurality of radially inwardly directed air passages 64, the Pass ges 64 being disposed at such angle that the center lines of the passages, if extended, would converge at a point lying on the center line of the cup 6| about midway between the bottom and the end thereof. The interior of the cup flares slightly outwardly, as clearly seen in Fig. 4. Attention is drawn to the fact that the nipple 59 and the cup 6| are, because of their threaded engagement with the shaft 55, adjustable longitudinally thereof and thus arealso adjustable longitudinally relative to one another, which has been found desirable to facilitate adjustment of the burner for most efficient operation. The cup is preferably secured in adjusted position by set screws 65.

The oil discharged from the nipple 59 and impinged upon by the jets of' air entering through the passages is further atomized by being thrown by centrifugal force from the edge of the cup 6|. In order that the cup may be rotated at high speed, the shaft 55 is driven by means of an electric motor 68 supported on a hOllSil'lg 69 enclosing the shaft 55. To that end', the shaft has non-rotatably secured thereto a pair of sheaves or pulleys 10, and the motor shaft likewise has non-rotatably secured thereto a pair of sheaves or pulleys II. Running over the pulleys are conventional V-belts 12. The pulleys and the belts are protected by means of a guard plate 13.

The primary air supply means includes a fan I5 fixed on the shaft 55 near the nozzle end of the shaft. The fan operates in a housing 16 just capabl of receiving the fan and'having an axial tubular extension composed of a hub-like portion 11 and a cylindrical member 18 threaded at its inner end to receive a frusto-conical member 19.

The member 18 is secured to this hub-like portion by suitable means (not shown) and projects into the passage formed by the inner member 33 to an extent suchthat the frusto-conical member 79 is within the most restricted portion, that is, to the point 45. The frusto-conical member 19 has a cylindrical portion 80 which is threaded onto the inner end of the member 18 and is secured in adjusted position by a Setscrew 8 I. This frusto-conical member has a minimum internal diameter which is in excess of the maximum diameter of the cup 6 I and thus is spaced radially therefrom to form therebetween an annular passage 92. At the base of its frusto-conical portion,

the member 19 is provided with a plurality of passages 83 inclined slightly outwardly, as best seen in Fig. 4, and given a scalloped arrangement, as best seen in Fig. 5. The primary air is, by the fan 15, forced into and through the cylindrical member 18, where a part of the air then flows through the passages 64 in the cup 6| to impinge upon and atomize the oil as its flows from the nipple 59. Another portion of, the air supplied by the fan 15 flows through the annular passage 82 formed between the cup 6| and the frustoconical member 19 so as to impinge upon and thereby atomize and direct horizontally th already partially atomized fuel particles as they are thrown by centrifugal force from the cup 6|. Still another portion of the primary air supplied by the fan 15 passes through the passages 83,

further impinging upon the partially atomized fuel oil to break up the remaining particles and further direct the resultant mixture horizontally into the fire tube l2. To provid an intake for the primary air, the housing 69 preferably is formed with an opening 84.

The housing -69 is rigidly attached to and supported by the housing 16. This housing 16 is, in turn, supported on the hood 2'! by means of hinges 8'! so that the entire fuel and primary air supply unit may be swung into or out of position. This gives ready access to the fuel nozzle for cleaning, adjustments, repairs or replacements. Further, when swung out of normal operative position, longitudinal removal of the member 33 may be effected. As best seen in Fig. 1, even the fuel oil supply pipes 89 are jointed at the hinges so as to be swingable with the housings 69 and I6. A suitable latch (not shown) is, of course, provided on the side opposite the hinges 81.

The housing 16 on its wall adjacent the wall 3! of the hood 2! is formed with a small ann'ular bead or flange 85 which serves to space the housing slightly from the flange portion 42 of the inner air nozzle member 33. Opening to the space so formed area plurality of passages 86 communicating with the interior of the hood 2?. Thus some of the secondary air finds its way through the passages 86 and thence outwardly through the passage formed between the member 33 of the air nozzle and the cylindrical member 18, so as to prevent eddy currents from carrying the combustion or the products of combustion back around the members 18 and 19.

,In Figs. 6 to 8, there is disclosed a modified form of hood to be interposed between the fire tube 12 and the blower 25 of the secondary air supply means. Like the hood 21', this modified hood has annular, radially inwardly extending walls 99 and ill connected by a peripheral wall 92 spacingthe walls axially. The hood also has an outer peripheral flange 93 by means of which it may be secured in position by attachment to the flange 22 of the tubular member 2!. The annular walls 99 and 9| have a comparatively large central opening through the hood in which is mounted the air nozzle composed of the parts 32 and 33, as described in connection with the first embodiment.

The hood has an air supply opening 94 for connection to the blower. This opening is so located that the air is discharged generally tangentially into the'hood so as to tend to have a circular motion within the hood. To enhance this circular motion, there is interzposed in the hood a partition, generally designated 95, including a straight portion 95 extending from the peripheral wall 92 inwardly to the central opening in the walls 99 and 9|. Completing the partition is a second portion 91 which is spiral in character and extends from the inner end of the portion 96 to the peripheral wall 92 of the hood at a point approximately 270 from the inner end of portion 96. There thus results, as clearly seen in. Fig. 6, a spiraling and gradually tapering pasinto theflre tube in the form of a whirling cylindrical curtain of air.

J As an aid inimparting this whirling motion.

to the air and particularly in directing it into the nozzle passage, there are disposed in the hood about the central opening a plurality of vanes 98. In the present instance, four such vanes are shown with one terminating at the juncture of the straight and the spiral portions of the partition, and the remainder located at 90 intervals. The vanes are positioned and shaped to act as scoops catching a portion of the air flowing through the spiraling and tapering passage, and directing the air tangentially into and through the air nozzlepassage 41.

Each vane is made from a rectangular piece '0: metal having a width just slightly greater than the spacing of the walls 90 and 9| and a length about twice the width, though the length until the comer I02 is within about one-quarter of the width of the vane from the edge 99.

The vane is welded or otherwise secured with its edge 99 against the wall 9| and extending tangentially with respect to the opening in the wall, the vane being tangent to the opening at the end opposite the end edge loll. The end edge I thus is spaced radially outwardly of the opening and extends completely between the walls 90 and 9| to intercept some of the air flowing through the spiral passage. The proportion of air intercepted of course increases with each vane, considered in a clockwise direction from the inlet 94, with the end edge I09 of the lastvane contacting the spiral portion 91 of the partition to intercept all the air. The air so intercepted is by the rolled portion of the vane directed toward the air passage 41. I

As a result of the manner herein described of supplying both the primary and the secondary air, the difllculties and problems presented in a multiple pass, horizontal tube, forced draft boiler with a fire tube of limited dimension are overcome. the centrifugal action of the rotating cup 6| coupled with the impingement on the fuel oil of the various air streams or jets. Eddy currents about the secondary air nozzle and the fuel nozzle are avoided, thereby limiting the deposit of carbon on those parts. The construction prevents the formation of a sludge in the cup BI and prevents. the flame from being preponderantly on one side of the center of the fire tube. In contrast with the latter operation, the flame is maintained centrally 0f the fire tube and is caused to extend longitudinally over a substantial portion of the tube. This is in part brought about by the primary air, but particularly by the secondary air, because of the motion given to the secondary air as it is discharged to the combustion chamber. This motion of" the air not only maintains the flame centralized and extending a substantial distance longitudinall of the fire tube, but also assures better and more eillcient combustion because of the greater mixing of the secondary air with the combustible mixture and The voil is thoroughly atomized by because the turbulent character of the flame re- 1 leases more heat." v

It has been found that with ya burner embodying the features of this inventioncombustion is much more complete. "The carbon dioxide content of the gaseous products of combustion has been increased from 10%, which is poor, to 14% to 15%, which is excellent. It has also been found that the temperature obtainablein a particular boiler has been increased from 600 to 800 Fahrenheit. The fuel consumption has been reduced about 25%, v

I claim as my invention:

1. An oil burner comprising, in combination, means for discharging fuel oil, means for supplying primary air, and means for supplying secondary air comprising a blower, means forming an air nozzle completely surrounding said fuel oil discharging means, and means interposed between said blower and said air nozzle imparting to the air discharged from the nozzle a helical motion comprising a hood having a peripheral wall and annular end walls providing an annular space about a" central opening, an inlet in the peripheral wall for connection of the hood'to said blower, said inlet being disposed so that the air is discharged circularly about the hood, a partition in said hood providing a spiral tapering passage communicating with said air nozzle throughout the entire circumference thereof, and a plurality of vanes disposed in the annular space equidistantly about the central opening in said hood, each vane being composed of a substantially rectangular piece with the portion to one side of a diagonal rolled and mounted with its rolled end tangential to the central opening and with its straight side edge extending tangentially outward from the opening and with the concavity formed by the'roll facing the air nozzle.

2. An oil burner for use with a horizontal combustion chamber comprising, in combination, means for supplying fuel oil including a horizontally disposed rotar fuel nozzle, comprising a cup from the edge of which the fuel oil is sprayed by'centrifugal force, means supplying primary air for atomizing the fuel supplied by the nozzle including a tubular extension terminating in a frusto-conical member surrounding said cup near the outer end thereof to form an annular air passage in surrounding relationship 'to said cup and terminating in an annular air jet directed horizontally to act on the fuel oil immediately as it leaves the edge of said cup, said frusto-conical member having at the base of its frusto-conical portion a plurality of passages opening therethrough directed forwardly and slightly radially, and means for'supplying secondary air including an annular air nozzle concentric with but of substantially larger diameter than said frustoconical member for discharging air generally horizontally in a cylindrical curtain about the fuel nozzle.

3. An oil burner comprising, in combination, means for supplying secondary air comprising a blower, an annular hood including. an inner annular member outlining withinit a double frustoconical passage diverging in both directions axiall from anintermediate point, and an outer tubular member forming with the inner member an annular passage communicating with the interior of said hood and constituting an air nozzle directed to discharge generall axially; meansfor feeding oil including a tube terminating in a discharge nozzle located coaxially within said inner annular member and through and somewhat beyond the narrowest point of said inner annular member, and means for supplying primar air including a tubular housing portion terminating in a member having a cylindrical flange portion for axially adjustable attachment to the tubular portion and a converging frustoconical portion, said frusto-conical portion terminating in radial spaced relation to said nozzle and longitudinally inwardly of the end thereof and outwardly of the most restricted portion of said inner annular member, said frusto-conical member having at the base of its frusto-conical portion a plurality of forwardly and radially outwardly directed air passages.

4. An oil burner comprising, in combination, means for supplying secondary air including means forming an annular chamber and having an inner annular member outlining within it a double frusto-conical passage diverging in both directions axially from an intermediate point and having means constituting a secondary air nozzle directed to discharge generally axially, means for supplying primary air including a tubular housing portion located coaxially of the double frust -conical passage and extending just beyond the restricted intermediate point of the passsage, and means for feeding fuel oil located coaxially within said tubular housing portion including a hollow tube through which the oil is fed, a rotatable cup having an opening in the center of the bottom thereof and an annular series of air passages opening through the bottom at the periphery thereof, said passages extending obliquely inwardly on center lines diverging at a point on'thecenter line of said cup within said cup, and an axially bored nipple mounted in the discharge end of said tube and the opening in the center of the bottom of said cup to terminate within said cup, said nipple and said cup being relatively adjustable axially to vary the point of convergence of the center lines of said air passages relative to the discharge end of said nipple and said nipple and said cup being adjustable axially relative to said tubular housing portion to adjust the axial position of the discharge edge of said cup relative to the end of said tubular housing portion.

5. An oil burner comprising, in combination, means for supplying secondary air including an annular hood having an annular member outlining within it a double frusto-conical passage diverging in both directions axially from an intermediate point, means for feeding 011 including a tube terminating in a" discharge nozzle located coaxially within said annular member and through and somewhat beyond the narrowest point of said annular member, and means for supplying primary air including a tubular housing portion terminating in a cylindrical flanged portion for axially adjustable attachment to the tubular housing portion and a converging frustoconical portion, said frusto-conical portion terminating in radially spaced relation to said nozzle and longitudinally inwardly of the end thereof said frusto-conical member having in its frustoconical portion a plurality of forwardly and radially outwardly directed air passages positioned to direct air currents generally parallel with I the outer frusto-conical face of said annular member.

projecting through,

6. An .oil burner comprising, in combination,

means for discharging fuel oil, means for supplying primary-air, and means for supplying secondary air comprising a blower, means forming an air nozzle completely surrounding said fuel oil discharging means, and means interposed between said blower and said air nozzle imparting to the air discharged from the nozzle a helical motion comprising a hood having a peripheral wall and annular end walls providing an annular space about a central opening, an inlet in the peripheral wall for connection of the hood to said lower, said inlet being disposed so that the air s discharged circularly about the hood, a partition in said hood providing a spiral tapering passage communicating with said air nozzle throughout the entire circumference thereof, and a plurality of vanes disposed in the annular space equidistantly about the central opening in said hood, each vane at its radially outermost portion extending substantially across the annular space and rolled with increasing concavity as it approaches the central opening in said hood.

7. An oil burner comprising, in combination, means for discharging fuel oil, means for supplying primary air, and means for supplying secondary air comprising a blower, means forming an air nozzle completely-surrounding said fuel oil discharging means, and means interposed between said blower and said air nozzle imparting to the air discharged from the nozzle a helical motion comprising a hood having a peripheral wall and annular end walls providing an annular space about. a central opening, an inlet in the peripheral wall for connection of the hood to said blower, said inlet being disposed so that the air is discharged circularly about the hood, a partition in said hood providing a spiral tapering passage communicating with said air nozzle throughout the entire circumference thereof, and a plurality of vanes disposed in the annular space equidistantly about the central opening in said hood, each vane being concavely curved to direct the air tangentially and longitudinally through said air nozzle.

8. An oil burner comprising, in combination, means for discharging fuel oil, means for supplying primary air, and means for supplying secondary air comprising a blower, means forming an annular, uninterrupted air nozzle completely surrounding said fuel oil discharging means, and means interposed between said blower and said air nozzle imparting to the air a rotary motion as it is discharged from the nozzle including an annular hood concentric with said air nozzle and having a peripheral opening for the admission of secondary air, and a partition having a straight portion extending from the peripheral wall of said hood at a point adjacent the peripheral opening inwardly to said air nozzle in a direction partially to overlie the peripheral opening for directing the infiowing secondary air in one direction only circumferentially ofsaid hood, and a curved portion secured at one end to the inner JOHN C. CLEAVER. JULES VERNE RESEK.

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