US2099092A - Liquid fuel burner - Google Patents

Description

3 Sheets-Sheet l E. E. ARNOLD LIQUID FUEL. BURNER Filed March 24, 1954 Q INVENTOR Eowm E-ARNoLD Nov 16, 1937.

W''TNE. Es;

ATTOHYM `Patented Nov. 16, 1937 UNITED STATES PATENT OFFRE LIQUID FUEL BURNER Pennsylvania Application March 24,

7 Claims.

My invention relates to liquid fuel burners of the type in which liquid fuel, for example, oil, is projected toward the zone of combustion by a rotary fuel distributing device. Y

An object of my invention is to provide an improved burner of the character set forth which shall be capable of efficiently burning low-grade fuels.

A further object of my invention is to provide for progressive combustion of the fuel.

Further objects of my invention are to facilitate the vaporization of the fuel and to reduce flame roar to a minimum.

Still further objects of my invention are to provide an improved liquid fuel burner which may be easily assembled and disassembled; in which vibration is substantially eliminated and which may be readily adjusted for obtaining best operating conditions.

In practicing my invention, I provide a hearth structure, having spaced members, the opposed faces of which dei-lne a converging-diverging passageway through which a mixture of vaporized fuel, air and products of combustion is projected by a rotary distributor; the latter being driven at a relatively high speed by a motor.

The distributor is disposed within an opening in the hearth structure and carries blades for translating air through the opening and into the converging portion of the passageway. The distributor may be adjusted axially of the opening to adjust the volume of air translated. Means are provided for automatically initiating and terminating the ilow of fuel to the distributor when the latter is started and stopped.

The fuel and airprojected by the distributor commingle at high velocity between the distributor and the contracted portion of the passageway and it is adjacent said contracted portion that flame propagation is initiated. The mixture is expanded into the diverging portion of the passageway and its velocity gradually reduced. Flame roar, which accompanies a rapid rate of change in velocity is substantially reduced. The diverged portion of the passageway is so shaped that a certain amount of turbulence is imparted to the mixture which also assists in its efficient combustion.

In order that combustion may be delayed, an inert gas, for example products of combustion, is mixed with the atomized fuel and air as they are discharged by the distributor, and therefore, combustion, adjacent the distributor, is prevented. The .products of combustion are drawn toward the distributor by the high velocity fuel 1934, Serial N0. '717,137

and air as they enter the converging entrance to the passageway. The hot products of combustion also facilitate the vaporization of the fuel by mingling with and heating the mixture discharged by the distributor.

The arrangement of the various elements of my improved burner construction is such that they may be easily disassembled for inspection or repair. 'Ihis feature will be made apparent upon reference to the embodiments of my invention disclosed hereinafter.

These and other objects are effected by my invention as will be apparent from the following description taken in connection with the accompanying drawings, forming a part of this application, in which:

Fig. 1 is a vertical section through a burner constructed in accordance with my invention;

Fig. 2 is a section taken along the line II-II of Fig. 1;

Fig. 3 is an enlarged sectional the line III-III of Fig. 1;

Figs. 4 and 5 are perspective views of hearth details;

Fig. 6 is a sectional view, similar to Fig. 1, illustratingl a further embodiment of my invention; and

Fig. 'l is an enlarged view of certain elements shown in Fig. 6.

Referring now to the drawings, I have'shown my burner applied to a furnace of the type usually installed in residences and including a boiler I carried by a base member I I. A hearth, generally indicated at I2, is disposed adjacent the bottom of the boiler I0 and defines, with the walls thereof, a combustion chamber I3. A rotatable fuel distributing head I4 cooperates with the hearth I2 and is rotated by a `driving mechanism I5 which is disposed within a compartment I6 beneath the hearth I2.

'Ihe hearth I2 includes a plurality of refractory segments I'I, arranged, for example, in a circle within the boiler ill and supported by a platform I8. The platform I8 may be supported in any convenient manner, as, by the base II. The segments I'I when assembled form an annular horizontal wall I9 and a cylindrical vertical wall 2I in proximity to the walls of the boiler Ill. The vertical wall portions of the segments I'I are notched as shown at 22 for a purpose to be referred to hereinafter. An opening 23 is formed in the wall I9 within which the fuel distributing head I4 is arranged. The junctions of the horizontal wall I9 with the vertical wall 2| and the view taken along opening 23 are rounded as shown at 24 and 25, respectively.

The hearth I2 also includes a plurality of refractory segments 26 which are arranged in a circle within the walls 2l and which are superimposed upon the horizontal wall I9. Each of the segments 26 includes a body portion 21, a supporting foot 28 and a projection 29;' the vfoot 28 resting upon the wall I9 and the projection 29 being fitted within the notches 22 in the vertical wall 2|. The faces of the body portions 21 of the segments 26 which are opposed to the walls 2l and I3 of the segments I1 arel rounded as shown at 3I land 32, respectively. The opposed faces of the segments I1 and 28 define a converging-diverging passageway 33 extending radially of the hearth. The assembled segments 26 provide an opening 34 above the head I4, which opening 34 communicates with the converging` portion of the passageway 33 and the combustion chamber I3. v

Reference will now be had to the fuel distributing head I4 which includes a bowl 35 having an inclined Wall 35 terminating at its upper end in a horizontal disc 31 and at its lower end inran annular trough 38. A cover 39 is secured to the bowl 35 and cooperates with the disc 31 to form a relatively narrow slot 4I through which air passes when the head I4 is rotated. Fan blades 42 are provided on the outside of the bowl 35 for translating air through the opening 23 to the passageway 33. The head I4 is rotated by the driving mechanism I5 by ymeans of a spindle 43 which is tted to the bowl 35 by an arbor 4.4. A boss 45 having a tapered opening therein for the reception of the arbor 44 is secured to the bowl 35 by means of internal webs 46.

Liquid fuel such as furnace oil, is conveyed to the annular trough 38 from a constant level source, for example, the tank 41. A bent tube 48 is arranged Within the bowl 35 for conveying the oil to the trough 38 and is secured in a fitting 49 carried by a bracket 5I. In order that the bent portion of the tube 48 may be properly positioned with respect to the trough 38, an extension 52 is provided on the fitting 49, which extension is adapted to be fitted into a socket 53 formed in the bracket 5I. The extension 52 is fixed with respect to the bent portion of the tube 48 so that, when it is fitted into the socket 53, the bent portion ofthe tube 48 will be properly disposed with respect to the trough 38.V After properly positioning the tting 49 in the bracket 5I,it is held by a nut 54. Oil is conveyed from the tank 41 by a conduit 55 to a duct 56 formed in the bracket 5I. The latter communicates with the tube 48 by means of an opening 51 formed in the fitting 49. An enlarged view of some of the elements just described is shown in Fig. '1.

Any convenient method of obtaining a constant level of oil in the tank 41 may be used but I prefer to employ a pump 51, driven by the mechanism I5 and which is adapted tocirculate a quantity of oil through the tank 41 which is in excess of the quantity used by the burner. Oil is drawn from a reservoir 58 and from the tank 41 by the pump 51 through a conduit 59 and is translated to the tank 41 through a conduit El. A conduit 52 extending upwardly into the'tan'k 41 connects with the suction conduit 59 and provides an overflow connection for the tank 41. It will be apparent that the level of the oil inthe tank will be maintained at the top of the overflow conduit 62 as the amount of oil circulated by the pump 51' is always greater than theamount drawn off through the conduit 55. Flow of oil from the reservoir 58 corresponds to the amount drawn off by the conduit 55 from the tank 41. By this arrangement, a stable level of oil is maintained in the tank 41.

When the burner is shut down, the level of the oil in the tube 48 is maintained slightly below the bend therein and is indicated by the dotted line A, so that, flow of oil from the tube 4S into the trough 38 is prevented during inactive periods of the burner. When the head i4 is rotated, ,air is discharged from the interior of the bowl 35 through the slot 4I by centrifugal action, thereby reducing the pressure in the bowl 35. The level of oil in the tube 48 rises due to atmospheric pressure and spills over into the trough 38. Admission of air to the interior of the bowl 35 may be regulated by an adjustable damper 38a, so that the speed of the head I4 and the` vcorresponding pressure therein may be varied. Further reference to the iow of fuel will be made hereinafter under the description of operation.

The burner driving mechanism l5 preferably includes an electric motor 65 for driving the head I4. The latter is driven at a relativey high speed and in order that a standard rela tively low speed motor may be used, I prefer to interpose gearing therebetween. Therefore, a

gear 66, directly driven by the motor 55 is arranged to drive the high speed pinion 81, the latter being connected to the head I4 by means of the spindle 43. The spindle 43 is connected to the pinion 61 by means of anarbor 68 which is fitted into a tapered hole in the pinion. The

spindle 43 allows a certain amount of flexibility vwhen driving the head I4 at high speed. The

tendency of the latter is to rotate about its own center of gravity which may be `slightly out of alignment with the axis of the pinion 51.

The gear and pinion are housed in a casing 68 and preferably operate in a bath of lubricant. The gear 65 .is fixed to a stub shaft 1I which is journalled in bearings 12 carried by the casing S9. tothe motor shaft 14 by means of a coupling 15 and its other end is attached to the stub shaft 1I. This construction permits slight misalignments of the motor shaft 14 with respect to the stub shaft 1IV without affecting the operation.

The pinion 61 is journalled at its upper end in a suitable bearing 16 carried by the casing 89. ',Ihe bearing 16 preferably includes a plurality of sleeves 11 and 18 which are so proportioned that an appreciable clearance exists between the sleeves 11 and 18 and between the sleeve 18 and the casing 69. Rotation of the sleeves and axial movement thereof is prevented by a screw 19. When the pinion 61 is rotated at high speed, oil is gathered from within the casing by an oil groove 8l and is lifted to a chamber 82 above the bearing 16. Oil from the chamber 82 seeps through the clearance spaces defined by sleeves 11 and 18 and casing 69, and provides a cushioning film for maintaining the pinion 61 and the sleeves 11 and 18 in axial alignment and for absorbing any vibration which may be present in the pinion E51. A thrust bearing 82 is provided for the lower end of the pinion 61.

' In order that they amount of air translated by the blades 42 may be varied at will, adjusting means are provided which, preferably, effects axial movement of the head I4 within the opening 23 formed in the hearth I2. Air translated by the blades I4 passes through the annular A quill shaft 13 is secured at one end .f

space dened by the perimeter of the disc 37 and the rounded wall 25 so that, by moving the head I4 axially, it will be apparent that the area of the annular space will be varied and, therefore, the amount of air conveyed therethrough. The proper mixture of air and oil may be effected by this adjustment. Y

Axial f movement of the head I4 is accomplished,'preferably by means of a wedge 83, upon the inclined surface of which a pin 84 rests. The latter carries a cage 85 which supports the thrust bearing 82; the cage 85 being supported by the casing 33 in sliding relation. The wedge 83 is slidably carried by a fixed member 86 supported in any convenient manner. Movement of the wedge 83 may be effected by a rod 81 and adjusting nuts 88. Adjustment of the head upwardly may be effected by moving the wedge 83 to the right as viewed in Fig. 1. This causes the pin 84 to ride up on the inclined surface of the wedge 83, whereby upward movement of the cage 85,?thrust bearings 82, pinion 61, spindle 43, and head I4 is effected. The toothed portion of the pinion 3? is elongated so that proper mesh with the gear 63 is maintained throughout the range of adjustment. Conversely, downward movement of the head I4 and its associated elements is effected by movement of the wedge 83 to the left. When the proper adjustment is obtained, the wedge is locked in position by the nuts 88. Leakage of lubricant from the casing 69 may be prevented by a seal, which includes an expansible bellows 89 secured at one end to the cage 85 and at its other end to the casing 89 `by fluidtight joints.

Operation When the burner is inactive, delivery of oil to the head I4 by the tube 48 is prevented; as the level of oil in the tube 48 is below the bend therein. Operation of the burner is effected by energizing the motor which functions to drive the head I4 through gears 86 and 61. Incidentall the pump 51 initiates the circulation of oil through the constant level tank 41 with the starting of the motor 65. As the speed of the head I4 increases, air within the bowl 35 is discharged through the slot4| due to centrifugal action and, as the admission of air to the bowl 35 is restrictedby the damper 38a, the pressure within the bowl drops. When the pressure within the bowl 35 is reduced to a predetermined value, as determined by the speed of the head I4 and theadjustment of the damper 38a, atmospheric pressure forces the level of oil in the tube 48 above the bend therein and it flows into the annular trough 38. The amount of oil delivered by the tube 48 to the trough 38 may be regulated by means of a valve 9! connected in the supply conduit 55.

Oil from the trough 38 moves upwardly along the inclined wall 35, in a thin film, due to centrifugal action, and flows outwardly over the top surface of the disc 31 to the perimeter thereof. The oil is projected from the high-speed disc 37 at high velocity and in an atomized condition, toward the passage 33. Air from the compartment I6 is translated through the opening 23 and is directed outwardly toward the passage 33 and into contact with the atomized oil. The atomized oil and air become thoroughly mixed at high velocity inthe converging portion of the passage 33 and a combustible mixture oi vaporized oil and air is obtained in the restricted throat of the passage 33. This mixture may be ignited in any convenient manner (not shown).

Propagation of flame is initiated near the throat portion of the converging-diverging passage 33 while the mixture is moving at high velocity and continues in the diverging portion of the passage 33 at progressively reduced velocities. The areas of the throat of the passage 33 and the discharge opening, defined by the surfaces of the walls 2| and 3I, are such that I obtain a low rate of change in the velocity of the mixture. Flame roar, which accompanies a rapid change in velocity is substantially reduced. A substantial amount of heat is retained by the hearth I2, which heat is delivered to the boiler after the burner has been shut down. The number of cycles of operation of the burner Within a given period is therefore reduced.

In order to prevent combustion contiguous to the distributing head I4, I introduce products of combustion into the mixture of air and atomized fuel as it is discharged from the head. 'I'he high velocity mixture of oil and air, as it enters the converging portion of the passage 33, induces a ow of products of combustion from the chamber I3 through the opening 34 and into engagement with the projected atomized oil and air adjacent the head I4. The products of combustion dilute the primary mixture of the oil and air, and thereby retard combustion adjacent to the head I4.

Radiant heat from above as well as the hot products of combustion impinge on the cover 39 of the bowl 35, after passing through the opening 34, and, as the cover is formed of material having high heat-conducting qualities,a substantial amount of heat is radiated downwardly. This radiated heat increases the temperature of the iilm of oil on the walls 36 and disc 31 so that it may be more readily vaporized.

Operation of the burner is terminated by deenergizing the motor 65. As the head I4 decelerates, the pressure within the bowl 35 increases with consequent lowering of the level of oil in the tube 48. Flow of oil ceases when the level has dropped below the bend in the tube 48. The pump 57 continues to circulate oil through the tank 4l after the delivery of oil by the tube 48 has stopped; the circulation of oil through the tank 41 ceasing when rotation of the motor is l terminated.

From the foregoing, it will be seen that I have provided a novel form of rotary fuel burner in which liquid fuel is vaporized in a body of air at high velocity, after which ignition occurs, and flame propagation is effected at some distance from the rotating distributor. Progressive combustion from the throat of the passage 33 to the diverged exit of the same is the rate of change in velocity the diverging portion of the passage is slow, flame roar, which accompanies a rapid change in velocity, is substantially reduced.

It will also be apparent that'I have provided a burner construction which may easily be assembled or disassembled and in which vibration and noises which accompany it, are substantially reduced. The various elements which complete the structure are so proportioned that they may easily be dismantled for inspection or repair. With reference to the latter feature, it will be seen that the segments I 'I and 26, constituting the hearth, may be removed from the boiler IU through the conventional fire door in the same or through a hand-hole provided for that purpose. The head I 4 may be removed in a similar of the mixture in obtained and, as

manner. The driving mechanism I5 is 'accessif ble, and may beremoved from below the hearth as a unit, when desired. The assembly, including the bracket 5I and tube 48, may also be removed in the same manner.

In Figs. 6 and 7, I have shown a modification of the burner `described heretofore. The hearth I2 is similar to that shown in connection with Fig. 1 and includes the converging-diverging passage 33. The head I4 `in the modification is disposed within a flared, annular conduit |02, which is arranged within the opening 23 and spaced from the walls thereof. 'I-'he conduit IIIZ includes a flared annular wall |03, terminating at the topin a ange |04 which extends in a substantially horizontal plane. The lower end of the conduit |02 lis open and communicates with the chamber I6, beneath the hearth I2. An annular duct I is dened by the conduit |02 and the walls of the opening 23 and provides communication between the chamber I5 and the converging portion of the passage 23. The duct Ii is provided for conveying air `from the chamber I5 and is controlled by a damper |06; adjustment of the latter being effected in any convenient manner, as by screws |01.

The head I4 is similar in construction to the one shown in Fig. l and is supplied with oil in the same manner. In the modification, however, I prefer to show the head I4 driven by a relatively high-speed, vertical motor |08 by means of a spindle |09. The motor |08 is Carried by a supporting housing III), and vertical adjustment of the motor |08 is provided by a screw III threaded in the housing IIII and supporting the motor |08. The volume of air delivered by the blades 42 to the atomized fuel is varied in a manner similar to that described in connection with the first embodiment. The head Iii and, consequently, the spindle |09 and motor Ica are adjusted upwardly or downwardly by means of the screw III. When the proper amount of air is being delivered by the blades 42, the screw III is locked by a nut II2.

The tube 48 is supplied with oil from the constant level tank 41 in the same manner as previously described. In the modification, the pump 5I is shown driven by a separate motor |I3; the piping connecting the pump 51, tank 41, and reservoir, being similar, however, to the piping of the first embodiment.

Operation Assuming the burner to be shut down, the motors Ii and II3 are deenergized and the level of oil in the tube 48 is below the bend therein as shown by the dotted line A (Fig. 7) due to the equalization of air pressure in the tank 41 and head I4. Accordingly, there is no flow of oil from the tube 423` to the trough 38. Operation of the burner is initiated by energizing the motors Il and H3 simultaneously. Circulation of oil through the tank 41 is immediately effected by the operation of the pump 51. As the head I4 is accelerated, the pressure therein is reduced and iiow of oil thereto is initiated when the speed of the head reaches a predetermined value.

Atomized oil is projected from the perimeter of the disc 3i at high velocity and is contacted by a limited amount of air propelled by the blades 42 through the conduit |02. The mixture of atomized oil and air passes outwardly above the flange H363 toward the converging entrance of the passage 33 at high velocity. A second body of air from the chamber I6 passes through the annu- `attains a. predetermined value.

lar duct IIJ?) and engages the rich mixture of atomized oil and air adjacent the perimeter of the flange IIIII. The flow of air through the duct |65 is induced by the natural draft of the furnace and by the mixture of air and oil entering the converging portion of the passage 33, the latter producing a relatively low pressure area adjacent the top of the opening |05. The mixture discharged by the head I4 commingles with the secondary air from the duct |95 and a combustible mixture is obtained in the throat of the passage 33 where ignition takes place, The diverging portion of the passage 33 is so proportioned that expansion o f the mixtureV occurs and its velocity is progressively and evenly reduced so that flame roar is minimized.` Progressive combustion is obtained from adjacent the throat of the passage 33 to its exit at decreasing velocities.

In this embodiment, `as in the prior'one, products-of combustion are drawn from the combustion chamber I3 through the opening 34, to be mixed with the mixture discharged by the head I4. The admission of the products of combustion to this mixture prevents combustion adjacent the head I4, and, as stated heretofore, heat is imparted to the oil within the head I4 by these products of combustion whereby the vaporization of the oil is facilitated.

In terminating operation of the burner, both motors |88 and IIS are deenergized. The head I4 decelerates and flow of oil thereto is automatically stopped as the pressure within the head Circulation of oil through the tank41 is terminated with the stopping of the pump 51. u Y

The desirable operatingfeatures referred to in connection with the first embodiment are obtained in the present embodiment which also permits the use of a smaller head I4, with a corresponding reduction in weight of the moving parts.

While I have shown. my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and modifications, without departing from the spirit thereof, and I desire, therefore, thatonly such limitations shall be placed thereupon as are imposed by the prior art or as are specically set'forth in the appended claims.

What I claim is:

1. In liquid fuel burning apparatus, the combination of a furnace having a combustion chamber therein, a hearth arranged at one end of the combustion chamber and including a wall defining anl end of the combustion chamber and an annular structure disposed in said combustion chamber and spaced from the wall, said wall and annular structure having surfaces opposed to each other and forming a passageway which converges and diverges from adjacent a central portion of the hearth toward the periphery thereof, and a rotatable head disposed adjacent the center of the hearth for projecting atomized fuel and air directly into the converging portion of said passageway.

2. In liquid fuel burning apparatus, the ccmbination of a furnace having a combustion chamber therein, a hearth arranged at one end of the combustion chamber and including a wall defining .an end of the combustion chamber and an annular structure disposed in said combustion chamber and spaced from the wall, said wall and annular structure having surfaces opposed to each other andl forming a passageway which converges from adjacent a central portion of the hearth toward the periphery thereof, and a rotatable head disposed adjacent the center of the hearth for projecting atomized fuel and air directly into the converging portion of said passageway.

3. In liquid fuel burning apparatus, the combination of a furnace structure having side walls defining a combustion chamber, a wall member dening one end of the combustion chamber and including a peripheral portion extending into the combustion chamber, an annular structure spaced from the wall member and within the peripheral portion thereof, said annular structure and said wall member having surfaces which are disposed in opposed relation and so shaped that they define an annular passageway which converges and diverges outwardly from a central portion of the wall member toward the peripheral portion thereof and a rotatable head for projecting atomized fuel and air directly into the converging portion of said passageway.

4. In liquid fuel burning apparatus, the combination of a furnace having side walls defining a combustion chamber, a refractory hearth disposed adjacent the bottom of the furnace and defining the bottom of the combustion chamber, said hearth including a horizontal wall and an annular structure having portions spaced above theV horizontal wall andI inwardly from the side walls of the combustion chamber, said horizontal wall and spaced annular structure having opposed surfaces for defining a horizontally eX- tending passageway which converges outwardly from adjacent a central portion of the hearth, and a rotatable head centrally disposed with respect to the hearth for projecting, at relatively high velocity, atomized fuel and air directly into said converging passageway.

5. In liquid fuel burning apparatus, the coinbination of a furnace structure having side walls defining a combustion chamber, a wall member defining one end of the combustion chamber and including a peripheral portion extending into the combustion chamber, an annular structure spaced from the wall member and Within the peripheral portion thereof, said annular structure having a surface disposed in opposed relation with surfaces of the wall member and the peripheral portion thereof, said surfaces being so shaped that they form a passageway which converges outwardly from adjacent a central portion of the wall member and diverges within said peripheral portion of the wall member toward the combustion chamber and means for projecting a mixture of atomized fuel and air into the converging portion of the passageway.

6. In liquid fuel burning apparatus, the combination of a furnace structure having side walls defining a combustion chamber, a wall member defining one end of the combustion chamber and having a centrally disposed opening formed therein for the passage of air for combustion, an annular structure spaced from the inner side of said wall member and aligned substantially in oo-axial relation with the opening in the wall member, said wall and annular structure having surfaces opposed to each other forming a passageway extending from adjacent said opening toward the side walls of the combustion chamber, and a rotatable head coaxially arranged within said opening for projecting a mixture of atomized fuel and air into said passageway,

whereby secondary air is drawn through the opening and entrained in the projected mixture of fuel and air.

7. In liquid fuel burning apparatus, the combination of a furnace structure having side walls defining a combustion chamber, a wall member defining one end of the combustion chamber and having a centrally disposed opening formed therein for the passage of air for combustion, an annular structure spaced from the inner side of said wall member and aligned substantially in coaxial relation with the opening in the wall member, said wall and annular structure having surfaces opposed to each other forming a converging-diverging passageway extending from adjacent said opening toward the side walls of the combustion chamber, and a rotatable head co-axially arranged within said opening for projecting a mixture of atomized fuel and air into the converging portion of said passageway, whereby secondary air is drawn through the opening and entrained in the projected mixture of fuel and air.

EDWIN E. ARNOLD.

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