US2991941A - Liquid fuel burners - Google Patents

Description

July 11, 1961 R. E. ZOLLER LIQUID FUEL BURNERS Filed Maroh 20, 1959 pm WM WW mm m INVENTOR. Ronald E. Ziiller ATTORNEY United States Patent g y 2,991,941 LIQUID FUEL BURNERS Ronald E. Zoller, London, England, assignor to Babcock 8: Wilcox, Limited, London, England, a company of Great Britain Filed Mar. 20, 1959, Ser. No. 800,797 Claims. (Cl. 239-426) This invention relates to liquid fuel burners and to a method of generating heat at a variable rate. More specifically, the invention relates to liquid fuel burners of the kind having a whirl chamber with a discharge orifice for the passage from the whirl chamber of whirling fuel. Various modes of regulating the output of such burners have been adopted in the past. For example, according to one mode the output of a burner is varied by regulating the pressure at which the fuel is supplied to the burner. However, such regulation is suitable only for a limited range of output since reduction in pressure tends adversely to effect fineness of the spray, and therefore leads to deterioration in the combustion process. According to another mode a variable proportion of fuel is returned from the whirl chamber to the fuel supply system. Whilst with this method a fine spray may be obtained over a wide range of output, the regulation is accompanied by a relatively great variation in the spray cone angle and this variation is liable to lead to difliculties.

The invention provides an improved means for regulating rate of firing, and an improved method of generating heat at a variable rate by means of a burner of the kind described.

In a liquid fuel burner of the kind specified in accordance with the present invention, beyond the orifice is an interceptor adapted to intercept a variable proportion of the cone of spray projected from the orifice and to direct the intercepted fuel towards collecting means.

The invention also includes a method of generating heat at a variable rate by combustion of liquid fuel delivered by a burner of the kind having a whirl chamber with a discharge orifice for the passage from the whirl chamber of whirling fuel, according to which at least over a part of the range of heat demand a proportion of the cone of spray discharged from the orifice is intercepted and led to collecting means and the proportion is varied in order to satisfy the demand for heat.

In one embodiment of the invention, the interceptor is formed, for the passage of spray to a combustion space, with an aperture co-axial with the whirl chamber and adapted to determine the proportion of the cone of spray which reaches the combustion space.

Generally, the aperture will be circular, although by choice of the shape of the aperture, the form of that part of the cone of spray which passes the aperture, and therefore the flame shape, may be controlled. By way of example, by the use of an oval aperture of suitable dimensions a flame of transverse dimensions in one direction greater than its transverse dimensions in a direction at right angles to the first direction may be produced.

The invention further includes a liquid fuel burner of the kind having a whirl chamber with a discharge orifice for the passage from the whirl chamber of whirling fuel, wherein beyond said orifice is a member which forms a wall of a chamber around the orifice, and an aperture aligned with said orifice is provided in said wall for passage therethrough of fuel from said aperture, and means are provided for effecting relative movement between said wall and said orifice to vary the proportion of fuel from said orifice which passes through said opening.

An embodiment of the invention will now be described,

ice

by way of example, with reference to the accompanying drawing, in which:

dFIG. 1 is a sectional elevation of a liquid fuel burner, an

FIG. 2 is a section on the line 11-11 of FIG. 1.

Referring to the drawing, the burner which may be used in firing a combustion space, e.g., that of a steam generator, includes a barrel or fuel conduit 10 into which liquid fuel at suitable temperature is supplied in a conventional manner through inlet 11. A whirl chamber 12 at the discharge end of the barrel 10 has a discharge orifice 13 which is formed as a recess or opening in sprayer plate 14. Fuel from barrel 10 passes to chamber 12 thrugh a spacer or distributor plate 15 which forms the rear wall of chamber 12.

Surrounding the barrel 10 is a housing or casing including an outer barrel 16 and an end member or a front cap 17 of cylindrical form which is screwed onto the front end of the barrel 16. The member 17 is formed with an annular end wall 18 which constitutes an interceptor having the center of its circular aperture 19 on the axis of the barrel. The member 17 and the sprayer plate 14 are relatively movable by control means 20 in order that the member 17 may intercept variable portions of the fuel discharged from the whirl chamber. Fuel caught by end wall 18 is trapped in the chamber 17A within the member 17 and flows along the annular channel between barrels 10 and 16 to outlet 21 wherefrom it is returned to the fuel supply system of the burner.

The sprayer plate 14 and the spacer or distributor plate 15 are positioned between a flanged outer sleeve 22 and an inner sleeve 23. The inner sleeve fits closely around reduced end portion 24 of the barrel 10 and is welded to this barrel as shown at 25. The outer sleeve 22 is screwed on to sleeve 23 to clamp the plates 14 and 15 in position. The discharge end of the barrel portion 24 is spaced from the plate :15 to provide a passageway for fuel from barrel 10. Plate 15 is formed with a rear annular recess 26 and a front annular recess 27, and a series of eight cylindrical passages 28 extend between the two recesses so that fuel from barrel 10 may pass to the front recess 27, wherefrom the fuel discharges approximately tangentially into the chamber 12 through a series of four openings 29 which are formed by slots in the rear face of the sprayer plate 14. The sleeve 22 is a sliding fit within member 17 and is formed with a series of six channels 30 for flow of intercepted fuel to the annular channel between barrels 10 and 16. Member 17 is formed with a series of six fiat portions 31 which allow the end member to be turned by a spanner or the like.

The control means 20 includes an externally graduated end or rear cap 32 mounted on an externally screwthreaded portion of a body member 33 which is screwed onto and forms the end of the outer barrel 16'. Radial arms 34 are fixed to the cap 32 to facilitate manual rotation of the cap. The barrel 10 extends through the member 33 and an end piece 35 is secured to the rear end of the barrel by means of a stud 36 and nut 37 so that the end is sealed in a fluid-tight manner. A stud 38 is adjustably secured in cap 32 to engage stud 36 so that rotation of cap 32 will effect axial movement of the inner barrel 10. A compartment 39 is formed in the member 33 between an annular flange 40 and an apertured plug 41 which is fixed by screws to the member 33. Sealing rings 42 and 43 are provided in the flange and plug, respectively, to render the compartment fluid-tight.

The fuel inlet 11 opens into the compartment 39 and apertures 44 are formed in the barrel 10 for flow of fuel oil from inlet 11 to the interior of the barrel 10. A helical compression spring 45 extends between end piece 35 and plug 41 to urge the barrel 10 rearwardly. An

- 3 annular flange 46 is welded to the inner barrel forwardly of flange 40 at a location beyond which the barrel 10 is reduced in outside diameter. The flange 46 acts as a stop to limit rearward movement. of the barrel 10.

In operation of the burner, suitably heated fuel oil is pumped at constant pressure through inlet 11 to the interior of barrel 10 for discharge through orifice 13 after whirling in chamber 12. Due to centrifugal force the fuel is discharged in a hollow cone 47 of fine spray and, as can 'be seen from FIGURE 1, a substantial part of the cone is intercepted by the wall 18 when sprayer plate 14 is in the rearmost position. The intercepted fuel is trapped between wall 18 and the sleeve 22 and so is caused to flow rearwardly through channels 30 and through the annular channel between barrels 10 and 16 to outlet 21. From the outlet 21 the fuel is pumped back to the fuel supply system at a location between the fuel heater (not shown) and the inlet 11. The remainder 48 of'the spray cone passes into the combustion chamber to burn and so generate heat.

As shown in the drawings, the barrel 10 carrying the sprayer plate 14 is in the extreme rearward position, i.e., the position in which the maximum proportion of fuel is intercepted by wall 18. To reduce the proportion of fuel intercepted the cap 32 is rotated to move the cap and thus the barrel 10 forwardly. It will be seen that as the sprayer plate 14 moves towards the wall 18 the proportion of fuel intercepted is reduced, and, when the plate 14 engages the wall 18, substantially all the fuel discharged from orifice 13 passes through opening 19. Thus, the wall 18 intercepts a variable annular outer portion of the spray cone 47 and a variable portion 48 of thespray cone is discharged into the combustion space. Since the radially outer portion of the spray cone in which the spray particles tend to be larger is intercepted, the average spray particle size in that part of the cone passing through aperture 19 tends to be relatively small. This is advantageous from the point of view of combustion.

The diameters of the orifice 13 and the opening 19 are chosen to suit the operational requirements of the burner. Although the aperture 19 is shown to be considerably larger than orifice 13 it has been found satisfactory to have aperture 19 only slightly larger than orifice 13.

While the instant invention has been disclosed with reference to a particular embodiment thereof, it is to be appreciated that the invention is not to be taken as limited to all of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

1. A liquid fuel burner comprising an elongated housing having opposed front and rear open end portions, a conduit forming a fuel passage spatially disposed in and extending longitudinally of said housing, said housing and conduit being connected for relative movement, bearing means supporting said conduit within said housing, said bearing means dividing said housing into a fuel inlet compartment and a fuel outlet compartment, said housing having a fuel inlet communicating with said inlet compartment and a fuel outlet in communication with said fuel outlet compartment, said conduit having an opening in communication with said fuel inlet compartment, an atomizing head connected to the discharge end of said conduit, said head including means defining a fuel whirl chamber terminating in an orifice for discharging the fuel therefrom in the form of a spray, a front cap member connected to the housing to close the front end thereof, said cap having a wall portion provided with an aperture therein spaced :from said atomizing head, said aperture being substantially in co-axial alignment with said orifice, and means for adjusting said conduit axially of said housing, said adjusting means including a rotatable rear cap member closing said rear end of the housing whereby a rotation of said rear cap causes a corresponding longitudinal adjustment of said conduit and connected atomiz- 4 ing head relative to said front cap to vary the distance between the aligned apertured wall of said front cap and fuel dicharge orifice, the apertured wall intercepting a varying portion of the fuel spray discharged from said orifice prior to ignition, and means for collecting the intercepted fuel spray and returning the same to said outlet compartment.

2. A liquid fuel burner comprising an elongated housing having opposed front and rear open end portions, a conduit forming a fuel passage spatially disposed in and extending longitudinally of said housing, said housing and conduit being connected for relative movement, bearing means supporting said conduit within said housing and dividing said housing into a fuel inlet compartment and a fuel outlet compartment, said housing having a fuel inlet communicating with said inlet compartment and a fuel outlet in communication with said outlet compartment, said conduit having an opening in communication with said fuel inlet compartment, an atomizing head connected to the discharge end of said conduit, said head including means defining a fuel whirl chamber having an orifice for discharging fuel therefrom in the form of a spray, a cap member having an aperture therein connected to the housing to close the inner end thereof, said apertured cap member being spaced from said atomizing head with the aperture therein being substantially in coaxial alignment with said orifice, and means for adjusting said conduit axially of said housing, said adjusting means including a rotatable rear cap on the rear end of the housing, and a spring means normally biasing said conduit in engagement with said rear cap so that rotation of said rear cap provides for a corresponding longitudinal adjustment of said conduit relative to said housing to vary the distance between said discharge orifice and aligned aperture, so that a variable portion of the fuel spray is intercepted upon discharge from said orifice, prior to ignition, and means for collecting the intercepted fuel spray and returning the same to said outlet compartment, said latter means including a passageway defined by said cap member and atomizing head.

3. A liquid fuel burner comprising an elongated housing having opposed front and rear open end portions, a conduit forming a fuel passageway, said conduit being disposed in and extended longitudinally of said housing, heating means for slidably supporting said conduit within said housing for movement relative to one another, said bearing means dividing said housing into a fuel inlet compartment and a fuel outlet compartment, said housing having a fuel inlet connecting with said inlet compart ment and a fuel outlet connecting with said outlet compartment, said conduit having an opening in communication with said fuel inlet compartment, an atomizing head connected to the discharge end of said conduit, a flanged plug means sealing the other end of said conduit, said atomizing head including means defining a fuel whirl chamber having an orifice for discharging fuel therefrom in the form of a spray, a cap member having an aperture therein connected to the housing to enclose the front end portion of said housing with the aperture thereof being in substantially co-axial alignment with said orifice, and means for adjusting said conduit axially of said housing for varying the distance between said orifice and aligned aperture, said adjusting means including a rotatable rear cap threaded to the rear end of said housing, a coil spring concentrically disposed about said conduit and in engagement with the flanged plug thereof for normally biasing said conduit in engagement with said adjusting rear cap so that rotation of said rear cap provides for a corresponding longitudinal adjustment of said conduit relative to said housing for varying the distance between :said orifice and aligned aperture whereby a variable outer peripheral portion of the fuel spray is intercepted by said apertured cap upon discharge from said orifices prior to ignition, means connected to said adjusting rear cap to provide for vernier adjustments, said latter means including a stud threaded into the end of the adjusting rear cap, said stud being disposed in axial alignment with and in engagement with the flanged plug of said conduit for finely adjusting said conduit within said housing.

4. A liquid fuel burner comprising a housing, a conduit forming a fluid passage extending into said housing, means for supplying a liquid fuel to said conduit from a suitable source of supply, an atomizing head connected to the discharge end of said conduit, said atomizing head including an orifice through which liquid fuel is discharged as a spray, means connected to the end of said housing for intercepting a portion of the dispersement of said spray, means for moving said atomizing head axially relative to said spray intercepting means through the actuation of said conduit connected to said head whereby relative movement therebetween varies the amount of spray dispersement intercepted by said spray intercepting means and the angle of the unintereepted portion of said spray, and said intercepting means and atomizing head being disposed in spaced relationship to one another to define within said housing a return flow passageway for the intercepted portion of the fuel.

5. A liquid fuel burner comprising an elongated housing having opposed front and rear open end portions, a conduit forming a fuel passage spatially disposed in and extending longitudinally of said housing, means for connecting said housing and conduit for relative movement with respect to one another, bearing means supporting said conduit within said housing and dividing said housing into a fuel inlet compartment and a fuel outlet compartment, said housing having a fuel inlet opening communieating with said inlet compartment and a fuel outlet opening in communication with said outlet compartment, said conduit having an opening in communication with said fuel inlet compartment, an atomizing head connected to the discharge end of said conduit, said head including means defining a fuel whirl chamber having an orifice for discharging the fuel therefrom in the form of a spray, a cap member having an aperture therein, said cap being connected to the housing to close the front end thereof, whereby said apertured cap member is adapted to intercept a portion of said fuel spray before ignition, said cap member and atomizer head defining therebetween a return flow passageway for returning the intercepted portion of the fuel spray to said fuel outlet compartment, and adjusting means connected to the rear end of the housing, said adjusting means providing for external longitudinal adjustment ofsaid conduit relative to said housing during burner operation to vary the axial distance between the orifice and said intercepting apertured cap member to control the portion of the fuel spray introduced into a combustion space.

References Cited in the file of this patent UNITED STATES PATENTS 2,177,781 Haynes et a1 Oct. 31, 1939 2,613,112 Fletcher Oct. 7, 1952 2,736,608 Martin Feb. 28, 1956 2,873,099 Witlke Feb. 10, 1959 FOREIGN PATENTS 761,823 France Ian. 13, 1934 39,654/57 Great Britain Dec. 20, 1957 454,522 Belgian Dec. 19, 1958 234,405 Holland Dec. 19, 1958 27/80 Italy Dec. 16, 1958 44,346/58 Austrailia Dec. 17, 1958 66,158/58 India Dec. 17, 1958

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