US2177053A - Oil burner - Google Patents

Description

' G. A. BOYD oct. 24, 1939.

OIL BURNER Filed Dec. 51, 1936 INVENTOR Gear BY v I? 6250 a ZTTORNEY Patented Oct. 24, 1939 PATENT OFFICE OIL BURNER I George A. Boyd, Chicago, Ill., assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana Application December 31, 1936, Serial No. 118,594 11 Claims. (01. 158--77) l plete and satisfactory mixing of the atomized fuel with the air of combustion.

It is a further object of my invention to provide a centrifugal type of burner which will operate with highly refractory orviscous fuels and I wherein the carbon deposits common to low speed burners will be eliminated.

It is a further object of my inventionto provide a centrifugal type burner to operate with less refractory fuels of high fluidity, differing from the 20- usual mechanical centrifugal burners by being rotated with air.

Other objects of this invention will become apparent from the following description thereof and the appended claims when readin conjunc- 25 tion with the accompanying drawing which forms.

apart of this specification, and in which:

Figure 1 is a vertical sectional view of the preferred embodiment of my burner.

Figure 2 is a plan view. with the rotor removed 20 and part of thebase cut away showing the bowl and symmetrically disposed portstherein.

Figure 3 is an elevational view of. my preferred form of the rotor.

Figure 4 shows 'a modification of the embodi- 38 ment shown in Figures 1 to 3.

My new fuel burner comprises a rotor having H a coaxially disposed cup therein for receivingfuel -to be atomized by centrifugal force andis particularly characterized by the fact that the 40' rotor is entirely supported "ona film of air during normal operation thus eliminating metallic friction.

Referring particularly to Figure 1, a burner I0 is shown comprising a base member I I having a 48 conical bowl l2 in its upper face; A plurality of ports! are symmetrically disposed about the wall of the bowl I2 and a port 13a is located in the bottom thereof. An annular passage [4 for communication with the ports 13 is provided 50' in the base member ll. Conduits l5, l6, connect the annular passage M with a suitable source of compressed air. Conduits 15a and lBa connect port I3a with conduit 16. p

The adjective conical is here used in the broad sense of gradually lessening in circumference". Likewise the word bowl is used in the broad sense of a concave vessel of various forms A rotor 20 is shown, the lower portion 2| of which is formed for reception within the bowl l2 5 for rotation therein. The lower portion 2| of the rotor is preferably provided with turbine-like reaction surfaces 22. The lower portion 2| of the rotor is shown as being in the shape of a cone fitting into a conical bowl l2 of the same shape but obviously other shapes may be employed so long as rotation is provided for. I may even employ a depression of one shape and the rotor bottom of another shape, i. e., curvatures of the two surfaces [2 and 22 may be any shape so long as they are substantially circular in horizontal crosssection.

The above referred to ports l3 are arranged to discharge air under pressure against the reaction surfaces of the rotor for driving the same and for assisting the air discharged from port B11 in entirely supporting the rotor. It is possible to thus eliminate metallic bearing friction during normal operation which, obviously, is an advantage over the usual mechanical centrifugal burn- 25 er. Also because of the elimination of the metallic bearing friction the rotor may be rotated at high speeds not heretofore obtainable in an oil burner.

-If so desired, anti-friction bearings may be provided for reducing friction upon starting and stopping. This arrangement may take the form of ball bearings (not shown) circularly disposed about the periphery of the bowl I2 preferably above the center of gravity of the rotor.

It is acknowledged that air floated and driven rotors are old broadly, as for example in centrifuges, and no claim is made thereto. It is the following described new combination embodying the above and the method of operation to which the 40.

present invention is directed.

My rotor 2| is further provided with a cup 24 coaxially disposed therein for the reception of liquid fuel in a continuous stream to be subjected to centrifugal force and discharged therefrom in a highly atomized condition. I have shown this cup as having a rounded bowl-like bottom 25 joining with a vertical surrounding side wall 26, the side wall in turn diverging to form a mouth portion 21. Where fuels containing solid materials and fuels which carbonize readily are to be used, the cup wal1 26 may be made to diverge slightly in the direction of the mouth to prevent the carbon andother solid matter from adhering to the wall. A funnel-like baflle 28 is mounted in or other spacing and supporting the mouth portion 21 in spaced relation thereto, the function of which will be hereinafter described.

A branch 30 of the air conduit l6 leading from a suitable source of compressed air extends into the cup 24 through the mouth of the funnel-like baflie 28. The fuel conduit 35, enclosed within the branch conduit 30, extends beyond the end of the branch conduit 30 and terminates near the bottom 25 of the cup. The portion of the air conduit on the inside of the cup 24 and surrounding the fuel conduit is provided with a plurality of vertically spaced outwardly and downwardly directed ports 3 I. Each port is formed by a pair of spaced funnel-like members 32 defining a continuous annular opening which effects a funnel shaped discharge of the air therefrom. The funnel-like members '32 are connected together by suitable means such as ribs (not shown). The air is thus directed against the wall 26 of the cup at a plurality of levels to serve two purposes: (1) to give the first premixing of air with the fuel and (2) to prevent the oil from escaping from the surface of the bowl before the maximum centrifugal force is exerted upon it. The funnel-like bafiie 28 above referred to has its outer periphery spaced from the mouth of the cup sufficiently to permit the discharge of fuel between it and the mouth 21 but sufficiently close to prevent the fuel from escaping from the cup without being subjected to the centrifugal effect of the mouth 21 of the cup. The baflle 28 is preferably supported on pipe 30, however, it may be supported on the mouth of the cup as by ribs connections (not shown).

By introducing the fuel conduit 35 through the inside of the branch 30 of the compressed air conduit I6 it is thereby insulated from the heat in cident to combustion. The outside conduit may be streamlined, as indicated at 36, to minimize interference with the fuel and air currents. I have provided a duplicate air conduit 3001 in diametrically opposed relation to the above described air and fuel conduits for insuring a balanced condition of the rotor. This duplicate conduit 3011 may carry a part of the air to the cup or merely act as a standby whose only function, even when not used for supplying air or fuel, is to maintain the rotor in a balanced condition.

A plurality of passages 29 are formed in the rotor for conducting a. portion of the driving air to an /annular surrounding passage 29a formed below the mouth portion 21 of the rotor. The annular passage 29a communicates with a continuous annular orifice or port 291) formed in the mouth portion 21 of the cup 24 for directing air into contact with the atomized fuel as it is discharged from the mouth by centrifugal action to effect further atomization of the fuel and a second mixing of fuel and air. The centrifugal force due to rotation of the cup tends to discharge the atomized fuel horizontally from the lip 21 of the cup. The annular port 291) is-directed upwardly and outwardly to discharge a circular, continuous vjet of air across the horizontal path of discharge of the fuel and hence to cause the fuel to be distributed above its otherwise normal position on a level with the upper edge of the mouth 21 of the cup. A suitable surrounding baflle wall 31 is provided for directing the driving air which is discharged from between the rotor 2| and the wallof bowl I2 into contact with the a mixture of atomized fuel and air discharged from the mouth of the cup. The resultant position of the combustible mixture is indicated by the circle 38 in dotted lines. Obviously this position may be varied by varying the pressure within the supply conduits l5 and I5a and by changing the position of the baflie wall 31 and the direction of the jet from opening 291) in the mouth 21 of the burner, to thus cause burning either on the wall 31 or in space such as indicated at 38.

' The premixing effected by the introduction of air to the cup 24 through the ports 3| and premixing effected by the discharge from jet 2911 are particularly effective in installations. wherein highly refractory fuels are to be used. For some fuels, however, the air discharged from the annular space 23 is suflicient for mixing with the highly atomized oil discharged from the mouth 21 of the cup, without the above described premixing. In all cases additional secondary air may be supplied in the usual manner to supplement that passing through the burner.

Figure 2 is a plan view of the bowl with the rotor removed showing the symmetrically disposed ports I3 therein for discharging the compressed air substantially tangentially against the lower portion of the rotor.

Figure 3 "is an elevational view of the rotor showing the arrangement of turbine-like reaction surfaces 22 on the lower portion thereof.

Figure 4 is a modification of the arrangement shown in Figure l and differs therefrom in the method of introducing the fuel into the cup. In this modification the fuel is introduced through the bottom of the rotor 20 -by passing the conduit 35 through coaxial opening 40 therein. This opening is slightly larger than the conduit 35 there being no appreciable bearing contact between the rotor 20 and the conduit. The air which passes up through the opening 40 about the pipe 35 is effective to reduce bearing friction to a minimum and to produce a first premixing of air and fuel. An annular well 4| is formed in the bottom of the cup surrounding the conduit, for preventing the fuel from spilling into the opening 40 around the conduit 35 The upper end of the conduit 35 .is formed into two outwardly diverging branches 42 and 43 to assist in preventing fuel from leaking through opening 40.

Fuel pipe 35 is passed up through a conduit 44 admission of air through conduit 44. In other re- 1 spects the arrangement in Figure 4 is identical with that described in Figure 1.

Liquid fuels which can be used include petroleum oils, other combustible liquids and colloidal fuels such as dispersions of solid fuels in liquid fuels.

I have referred throughout the description to the use of air as the driving medium but it is apparent that other gases, e. g., flue gas, mixtures of air with other gases, and even liquids can be used. I

The drawing is not made to scale as the actual features of engineering design necessarily incorporated in my burner are within, the'skill of the expert .in the art.

Operation It is believed that a better understanding of my burner may be gained from an exemplary operation taken in connection with Figure 1. Air under pressure is discharged from the port 13a and the symmetrically disposed ports I 3. The air from ports 13 impinges against the turbinelikereaction surfaces'22 driving and supporting the rotor 20 while the air from port 13a has a supporting effect only.

Speeds as high as 165,000 R. P. M. have been obtained under experimental conditions for this type of apparatus; however, such extreme speeds are not necessary under actual operating conditions. Speeds of 50,000 to 100,000 R. P. M. are all that are needed to effect the complete atomization of the more refractory fuels. For the less refractory fuels speeds as low as 10,000 to 50,000 R. P. M. may be used. A

While the cup 24 (see Figure 1) is rotating, fuel is continuously introduced into its lower portion through the 'inner conduit 35. Air under pressure is passed through the outer coaxial conduit 30 into the cup 24 through the funnel shaped ports 3| for effecting'a first premixing and forcing of a film of fuel out against the wall 26 of the cup 24. From the bottom of the rotating cup the fuel flows in a very thin film along the vertical wall by virtue of the centrifugal force to which it is subjected. As this film moves outwardly over the curved surface formed by the mouth 21 of the cup, it covers a larger area and hence is subjected to additional thinning. This additional thinning aids in breaking the intrafilm bonds. As the atomized fuel is discharged from the mouth 21 of the cup it is subjected to an additional atomization and a second mixing of air therewith by the cross current of air discharged from the annular passage 2% in the mouth 21 of the rotor. The air from the vortical film below the rotor is also directed into contact with the above stream of air and atomized fuel by suitable baffles 37. Additional air may also be supplied in the usual manner.

A suitable device such for example as an electrical igniting circuit may be employed for initiating combustion in a conventional manner (not shown).

While I have described my invention in connection with certain specific embodiments thereof, it is to be understood that these are by way of illustration rather than by way of limitation and I do not mean to be limited thereby except as indicated by the scope of the appended claims which should be construed as broadly as the prior art will permit.

I claim: 1. A fuel burning device comprising a stator formed with a conical bowl in the upper portion thereof, a rotor operable in said bowl, means for discharging air between said stator and rotor for supporting and driving said rotor, a coaxially disposed cup in said rotor, and means for continuously supplying fuel to the inside of said cup, said fuel being subjected to centrifugal force and continuously discharged from the mouth of said cup in a highly atomized condition.

2. A fuel burning device comprising a stator formed with a conical bowl in the upper face thereof, a rotor operable in said conical bowl, means for discharging air between said stator and rotor for "entirely supporting and driving said rotor, said means comprising a vertically disposed port for directing air vertically against the lowermost portion of said rotor and a plurality of ports circularly disposed about said conical bowl for directing air against the under side of said rotor for driving the same, said rotor being further provided with a coaxially disposed cup therein, and means for continuously supplying fuel to the inside of said cup, said fuel being subjected to centrifugal force and continuously discharged from the mouth of said cup in a highly atomized condition.

3. The structure as defined in claim 1 wherein said rotor is formed with a circular opening coaxial with the axis of rotation of said rotor and opening into the bottom of said cup, and including a fuel pipe of slightly smallerdiameter than said opening positioned therein for introducing fuel into said cup from below said rotor.

4. The structure as defined in claim 1 wherein said rotor is formed with an opening coaxial with the axis of rotation of said rotor and opening into the bottom of said cup, and a fuel pipe positioned in said opening for introducing fuel into said cup from below said rotor, an inner flange at the base of said cup forming an annular well in the bottom of said cup surrounding said opening and means on said fuel pipe for directing fuel against the wall of said cup above said annular well.

5. The structure as defined in claim 1 wherein the means for introducing fuel into said cup comprises a fuel conduit passed upwardly adjacent the outside of said rotor over the rim of and down into said cup, a second conduit of slightly greater diameter than said fuel conduit disposed thereabout and adapted to convey air for insulating said fuel conduit and supplying air for a first premixing of air and fuel, and a third conduit, also adapted to convey air symmetrically disposed with respect to said second conduit for effecting a balancing of said rotor.

6. In a burner device for burning liquid fuel, centrifugal means for effecting a high degree of atomization of said fuel, comprising a rotor having a coaxially disposed cup therein and being provided with reaction surfaces thereunder, means for continuously delivering said fuel to the inside of said cup, means symmetrically disposed about the under side of said rotor for directing air under pressure against said reaction surfaces to form a vortical film of air therebeneath for entirely supporting said rotor and driving the same at high speed, said fuel being formed into a fine film against the wall of said'cup by a centrifugal action and continuously discharged from the mouth of said cup in a highly atomized condition, and means for directing said driving air into contact with said atomized fuel for mixing therewith for supporting combustion.

7. An oil burner comprising a rotor, having a cup formed coaxially therein, means for continuously introducing a liquid fuel into said cup, means for supporting said rotor. on a film of air comprising a base member having a conical bowl formed therein, said bowl being defined by a surrounding wall which continuously diverges upwardly, the lower portion of said rotor being complementarily formed for reception within said bowl, means disposed about the conical bowl for directing air under pressure substantially tangentially against said lower portion of said rotor, said air directing means, said diverging wall and said lower portion of said rotor being effective to cause said air to form a vortical film beneath said rotor for entirely supporting and rotating the same at an extremely high speed, whereby said fuel is subjected to centrifugal force and continuously discharged from said cup in a highly atomized condition.

8. A fuel burner comprising a rotor provided with a coaxial fuel cup therein and with reaction surfaces on the under side thereof, means for directing a fluid against said reaction surfaces for impelling and supporting said rotor, means for introducing a fuel into said fuel cup so that it may come under the influence of the rotor and be discharged therefrom by centrifugal force, and means for mixing air with said fuel for supporting combustion 9. The fuel burner of claim 8 which includes means for bringing the fluid which has been used for supporting and impelling the rotor into contact with fuel discharged from said'rotor.

10. In apparatus of the class described a rotor having in the top a coaxial cup with tapered sides terminating in a mouth portion and having at the bottom thereof a plurality of reaction surfaces, means for directing air against said reaction surfaces for supporting and rotating said rotor. means for introducing a liquid fuel into said cup 5 so that the rotation of the rotor may force said liquid fuel by centrifugal action along the sides of said cup and from the mouth thereof, and means for directing at least a part of the air which has been used for supporting and rotating m 11. The apparatus of claim 10 which includes 15 means for introducing air as well as liquid fuel into said cup.

GEORGE A. BOYD.

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