US2103958A - Fuel burner - Google Patents

Description

Dec. 28, 1937. I 'rf B. sTlLLMAN v 10i-5,958

FUEL BURNER Filed May 22, 1935 mww mmmmmmw INV ENT OR.

- Patented Dec. 28,` 1937 PATENT oF'FlcE aioasss FUEL BURNER Thomas B. Stillman, South Orange, N. J., as

signor vto The Babcock & Wilcox Company,

Newark, N. J., a corporation of New Jersey appaianoA May 2z, 1935, serial No. .22,702

13 Claims. (Cl. 299-141) 5 In one well known type of liquid fuel burner,

known as the mechanical atomizing type, the fuel is introduced under pressure into a whirling chamber in which it is subjected to a centrifugal effect and is atomized on issuing through adischarge orice. Inasmuch as the degree of atomization effected is dependent upon the pressure of the fuel on entering the whirling chamber, it has usually been found necessary to maintain the pressure of the entering fuel above 100 lbs. per sq. in. to secure a degree of atomization adequate for good combustion conditions. .Convsequently most mechanical atomizing burners have a relatively narrow range of fuel capacities from maximum to minimum and are not ordinarily adapted for usein installations having low fuel capacity requirements.

The main object of my invention is the provision of a liquid fuel burner of the mechanical atomizing type which is capable of operation over a wide range of fuel capacities with a high fuel burning efficiency in a furnace of high capacity. A further object is the provision of a fuel burner of the type described which-is capable of operation as either a long flame or short flame burner,

with the change from either type to the other being easily and quickly effected without interrupting the operation of the' burner.

The various features of novelty which characterize my inventionv are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, Vits operating advantages and specificv objects attained by its use, reference should be had to the laccompanying 40 drawing and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Of the drawing: l Y Fig. 1 isa sectional elevation of a liquid fuel burner constructed in accordance with my invention; Fig. 2 is an enlarged view of the discharge head shown in Fig. 1; l Figs. 3 and 4 are front and rear views respectively of the sprayer member shown in Fig. 2;

Fig. 5 is a front View of the nozzle member; o

and

Fig. 6 is a sectional elevation of the fuel burner shown in Fig. l mounted in a furnace wall.-

l The improved liquid fuel burner of my invetion is intended to be arranged to discharge through a circular fuel burner opening Ill in a furnace Wall Il. A metallic cone member I2 having blades y I3 on its inner periphery to effect rotation of the combustion air is positioned in the wall opening Ill with its smaller end nearer to the inner'side of the furnace wall II. The burner opening is flared from the inner end of the cone member by means of molded tile I4 held in position by a grid I5. On the outer end 10 of the cone member is mounted an air register I6, having a circular series of air doors I1 con. trolled by a handle I8 mounted in a cover plate I9. The `cover plate I9 carries a hub 20 centrally thereof in which is mounted an axially 15 adjustable distance piece 2l. On the furnace or inner end of the distance piece is carried a conical impeller plate 22, having acircular series of blade members 23 arranged to effect rotation of the entering air from the air register. 20

-Within the distance piece ,2| is arranged a burner barrel 2li,y on the furnace or inner end of which is vmounted the dischargehead of the burner. On the outer end of the distance piece is adjustably mounted a detachable coupling 25 member 25, which holdsy a supply connection 26 for a high pressure gaseous uid, -such as steam at a relatively high pressure, in position to communicate with an annular channel 21 formed between .a central fuel pipel 28 and.v the barrel 30 24, and a liquid fuel supply connection 29 in position to communicate with the outer end of the pipe 28.

The discharge head of the burner includes a circular nozzle member 30 formed with a reduced 35 tubular outer portion 3l having a liquid sealed connection to the furnace end of the fuel pipe 28. The nozzle member has a pair of concentrically arranged circular series of parallel passages 32 and ,33 respectively, the radially inner 4o y passages 32 communicating with the fuel pipe 28, while the radially outer passages 33 communicate with the channel 21. A circular sprayer imember 34, as shown in Figs. 1-4, contacts with the furnace end of the nozzle member., and is 45 formed with a central conical whirl chamber 35. The at outer face of the sprayer member is formed with a series of symmetrically arranged angularly spaced'nozzle slots 36 having their radially outer ends registering with' the fuel pas- 50 sages 32 and their discharge ends tangentially arranged relative tothe outer endof the whirl chamber. The furnace or tapered end of the whirl chamber 35 terminates in an orice 31 and the furnace face 38 of the sprayer member 55 is formed with a flaring continuation 31a of the discharge orifice 31, the walls of the continuation having a greater flare than the walls of the air. lfuel stream and the annular form of the sur-` whirl chamber. The sprayer member and nozzle member are held in their assembled position relative to the fuel pipe and burner barrel by a tip member 39 which has an internally threaded outer end portion 39a mounted on the burner barrel.

With the fuel burner parts constructed as described, the burner may be operated as a straight mechanical atomizing liquid fuel burner. In this mode of operation, the liquid fuel, such as a suitable fuel oil, delivered by the supply connection 29 under a substantial pressure, passes at a relatively high velocity through the pipe 28, through the series of passages 32 and slots 36 in separate streams into the conical whirl chamber 35. The tangential delivery of the liquid fuel to the conical whirl chamber at a high velocity causes it to whirl at a high peripheral speed around the chamber and to be discharged from the orifice in the sprayer plate in the form of a flaring hollow cone of minute particles of fuel. 'I'he conical fuel stream is then contacted by the rotating stream of air passing through the opening I0 and converging towards the fuel stream. The air stream continuously scrubs the surface of the fuel cone and combustion progresses according to the effectiveness of the mixing of the fuel and The relatively smooth conical form of the rounding air stream are not conducive to ex tremely rapid combustion of the fuel and a relatively long flame results.

I have found that the rate of fuel combustion can be substantially accelerated with a correspondingly shorter flame resulting, by causing jets of gaseous fluid at a relatively high velocity to sweep across the boundary surface of the fuel cone at spaced points and in different directions at the same angle to the cone axis. For this purpose the sprayer member 34 is formed with a series of fluid passages 40 extending through the member at an oblique angle to the axes of the burner and the cone of fuel spray. 'Ihe passages 40 are symmetrically arranged relative to the axis of the sprayer member and directed so as to discharge a circular series of non-intersecting fluid jets collectively directed in a direction opposite to the direction of vrotation of the air stream. 'I'he passages 40 have their outer ends registering with the inner ends of corresponding passages 33 in the nozzle member and their' discharge ends opening through the furnace face 38 of the sprayer member at approximately the junction therewith of the flaring continuation 31H.

with this construction the nquld fuel win be discharged as previously described. As the fuel cone leaves the sprayer member it is swept by the series of gaseous fluid jets. lA turbulent condition is thereby effected at intervals in the zone of contact of the air and fuel streams, causing air to be swept `into the fuel stream and fuelv particles to be thrown into the air stream. A rapid and intimate mixture of the air and fuel resultsand the flame is considerably shortened.

. The described location of the discharge ends of operation over a wide range of fuel capacities with a consistenthigh degree of fuel burning efficiency. With high rates of fuel consumption and correspondingly high fuel pressure, the gaseous fluid supply may be cut off and the burner operated as a straight mechanical atomizing burner. When the fuel rate and/or pressure drop. below the point at which the desired combustion conditions can be maintained, the gaseous fluid supply is opened. The greater the degrecl of mechanical atomization of the fuel effected when the burner is operated as last mentioned, the less is the amount of gaseous fluid required to secure the desired combustion conditions.

In one installation of liquid fuel burners constructed in accordance with my invention, the burners carried '70 per cent of the rating with fuel oil alone at lbs. oil pressure at the burners. When the load dropped to about 20 per cent of rating the burners were operated with steam jets as described with the oil pressure at 15 to 20 lbs. per sq. in. and steam at a pressure of 50 to 60 lbs. per sq. in. Under these conditions the flame was observed to be short and bright without the presence of sparklers or smoke. These burners were also satisfactorily operated with the steam jets in use with an oil pressure as low as l0 lbs. per sq. in. Without the steam jets in use with such low oil pressures, continuous combustion was found to be impossible.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form of my invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a c orresponding use of other features.

l. A liquid fuel burner for mounting in a furnace wall air inlet opening and comprising a discharge head having a discharge orifice with a flaring continuation at its furnace side for discharging liquid fuel in a conical spray, a whirling -chamber communicating with said discharge orifice, a nozzle slot having its inner end opening substantially tangentially into said whirling chamber, a liquid fuel supply connection to the outer 'en'd of said slot, and means directing a gaseous fluid jet along the peripheral surface of the fuel stream leaving said discharge orifice continuation.

,I 2. A liquid fuel burner for lmounting in a furnace wall air inlet opening and comprising a discharge head having a discharge orifice with a flaring continuation at its furnace side for discharging liquid fuel in a conical spray, a whirling chamber of substantially circular cross-section communicating with said discharge oriilce, a nozzle slot having its inner end opening substantially tangentially into said whirling chamber, a liquid fuel supply connection to the outer end of said slot, a series of passages having their discharge ends arranged at the furnace end of said discharge orifice continuation, and means for supplying a gaseous fluid to said passages.

3. A liquid fuel burner for mounting in a furnace wall air inlet opening and comprising a discharge head having a discharge orifice flaring towards its furnace side for discharging fuel in a conical spray, a whirling chamber of substan- `tially circular cross-section communicating with said discharge orifice, a series of lsymmetrically arranged nozzle slots having their inner ends opening substantially tangentially into said whirling chamber, a liquid fuel supply connection to the outer end of each of said slots, a series of passages arranged substantially symmetrical relative to said discharge orifice and having their discharge ends opening adjacent the furnace end thereof and directed'along the peripheral surface of said conical spray, and means for supplying steam to said passages.

4. A sprayer member for a liquid fuel .burner adapted to be mounted in a furnace wall air inlet opening and having a discharge orifice, a whirling chamber of circular cross-section formed in one face thereof and discharging through said discharge orifice, a fuel nozzle slot formed in said face and having its discharge end opening substantially tangentially into said chamber,` and a gaseous fluid passage having its discharge end opening at the furnace side of said discharge orice.

5. A sprayer member for a liquid fuel burner adapted to be mounted in a furnace wall air inlet vopening and having a discharge orifice flaring towards its furnace side, a central whirling chamber of circular cross-section formed in one face thereof and discharging through said dis charge orifice, a fuel nozzle slot formed in said face and having its discharge end opening substantially tangentially into said chamber, and a series of gaseous fluid passages arranged substantially symmetrical relative to said discharge orice and having their discharge ends opening at the furnace end thereof.

6. A sprayer member for a liquid fuel burner adapted to be mountedin a furnace wall air inlet opening and having a discharge orifice fiaring towards its furnace side, a central whirling chamber of circular cross-section formed in one face thereof tapering towards and discharging through said discharge orice, a fuel nozzle slot formed in said face and having its discharge end.

opening substantially tangentially intol said chamber, and a series of fluid passages arranged substantially symmetrical relative to said discharge` orifice and at an angle to the axis thereof and having their discharge `ends opening adjacent the furnace end thereof.

'7. A liquid fuel burner for, mounting in a furnace wall air inlet opening and comprising a discharge head having means therein for causing liquid fuel to be discharged therefrom in a conical spray, and means directing a gaseous uid jet substantially tangential to the boundary surface of said conical spray.

8. A liquid fuel burner for mounting in a furnace wall air inlet opening and comprising a discharge head having means therein for causing liquid fuel to be discharged therefrom in a conical spray, and means directing gaseous fluid jets substantially tangential to the boundary surface of said conical spray at circumferentially spaced points,

9. A liquid fuel burner-for mounting in a furnace wall air inlet openingand comprising a discharge head having means therein for causing liquid fuel to be discharged therefrom in a conical spray, and means directing gaseous fluid jets substantially tangential to the boundary surface of said conical spray at circumferentially spaced points and in different directions at the same angle to the spray axis.

l0. A liquid fuel burner for mounting in a furnace wall air inlet opening and comprising a discharge head having a discharge orifice for discharging liquid fuel in a conical spray, a, whirling chamber communicating with said discharge orifice, a liquid fuel supply connection .having a tangential entry to said whirling chamber, and means directing a high pressure gaseous fluid jet substantially tangential to the peripheral surface of the fuel stream discharged from said discharge orice.

11. A liquid fuel burner for mounting in a furnace wall air inlet opening and comprising a discharge head having a discharge orifice with a iiaring continuation at its furnace side for discharging liquid fuel in a conical spray, a whirling chamber of substantially circular cross-section communicating with said discharge orice, a liquid fuel supply connection to said whirling chamber, and a series of gaseous fluid passages arranged substantially symmetrical relative to said discharge orifice and having their discharge ends opening at the furnace end of said discharge orifice continuation and directed substantially' tann gential to the peripheral surface of said conical spray.

12. A liquid fuel burner comprising a barrel having a liquid fuel passage therein, a discharge head at one end of said barrel having a liquid fuel whirling chamber therein terminating in a restricted discharge orifice, said discharge head including a liquid fuel passage having a substantially tangential entry into said whirling chamber and communicating with said barrel passage, said discharge head having a series of gaseous fluid passages therein with their discharge ends opening at the discharge side of said orifice and directed towards the path of the liquid fuel discharged from said orifice, and conduit means for delivering a gaseous fiuid at a relatively high pressure to said gaseous fluid passages.

13. Al liquid fuel burner sprayer member having a fuel whirling chamber tapering at its discharge end to a restricted discharge orifice intermediate the width of said member and having a aring continuation to the furnace face of the memberfland a series of high pressure gaseous uid passages in said member having their discharge ends opening to the furnace face of the member at points symmetrically spaced about the periphery of the furnace end of said discharge orifice fiaring continuation and direct.

ed substantially tangential to the peripheral surface of the fuel stream discharged therefrom. THOMAS B. STILLMAN.

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