US2564384A - Rotary vaporizing oil burner - Google Patents

Description

N. B. WALES, JR

ROTARY VAPORIZING OIL BURNER Aug. 14, 1951 3 Sheets-Sheet 1 Filed May 7, 1948 INVENTOR. NATHAN/EL B. WALES JR ATTORNEYS Aug. 14, 1951 N. B. WALES, JR 2,564,384

ROTARY VAPORIZING OIL BURNER I Filed May 7, 1948 3 Sheets-Sheet 2 JNVENTOR. NATHAN/EL B. WALES JR.

ATTORNEYS N. B. WALES, JR

ROTARY VAPORIZING OIL BURNER Aug. 14, 1951 3 Sheets-Sheet 5 Filed May 7, 1948 Patented Aug. 14, 1951 UNITED STATES ram OFFICE I 3 Claims.

This invention relates to oil burners and particularly to oil burners in which the oil is vaporized in a rotating retort.

In brief, the invention comprises in an oil burner, the combination of a circular retort supported for rotation on a vertical axis, bearing means to support the retort, said retort being formed with a rim comprising an annular inturned peripheral vaporizing surface adapted to carry and vaporize a thin film of oil, oil supply means connected to the inside of said rim, means for rotating said retort so as to form a thin oil film on said vaporizing surface, an oil preheater secured to said rim adjacent said vaporizing surface and having a heat-generating capacity sufficient to vaporize a thin film of oil substantially instantaneously, and means for energizing said preheater.

By permittin no more than a film of oil to form on or be delivered to the vaporizer surface at any time, such a burner can be made to start reliably under automatic control and to achieve a self-sustaining combustion phase within a short time after starting. These requirements are especially important in a domestic type burner installation.

In order to assure that the rotating retort does not collect a body of fluid oil which would defeat the above requirements, the burner according to the invention preferably includes a rotating electrical heating ring associated with the rotating vaporizing retort together with a sequence control unit which causes the vaporizer surface to be preheated to a predetermined vaporizing degree before the initiation of the rotation or admission of fuel oil to the vaporizing retort. Additionally, by forming the air supply blower integral with the rotating retort, and by simultaneously initiatin the rotation and oil admission to the preheated vaporizer retort, the initial vaporization and air mixture take place before the rotor has attained high speed and therefore under conditions of low air velocity, Which is conducive to reliable ignition.

The foregoing and other features of the invention will be more clearly understood by consideration of the following description taken together with the drawings, wherein:

Fig. l is a sectional view in elevation of a preferred embodiment of my invention showing the essential parts of the oil burner proper;

Fig. 2 is a top view of the burner of Fig. 1, omitting certain parts as indicated by the section line 2-2 of Fig. 1, showing the construction of 2 the annular vaporizig heater and the disposition of the air vane vents;

Fig. 3 is a schematic wiring diagram of the control system of the invention.

As seen in Figs. 1 and 2, a rotating vaporizer retort i of heat-conducting sheet metal is formed so as to comprise an annular vessel capable of centrifugally retaining a film of oil on its inner periphery. Surrounding and secured to the vaporizing surface of retort I is an annular metal casing 9 which supports a helical coil of resistance heater Wire H insulated by ceramic beads iii strung along the coil, thereby comprising an annular heater element. The terminal ends of wire H pass out of easing 9 through ceramic insulating bushings 68. This articulated heater construction permits the heater coil to be properly supported without excessive stresses in spite of the thermal distortions in retort l and easing 9 due to large temperature variations to which the burner is subject.

The central disc portion of retort l is pierced to form a plurality of louvers or vanes 3 which act both as blower blades and as central air delivery ports. Retort l is secured near its axis to hollow shaft 2 Which carries bearing sleeves 5 and is supported on vertical sleeve 4. Sleeve i is secured to base plate 6 which is in turn supported on legs 30, preferably adjustable as to height. Oil delivery tube 28 connects to the lower end of a central opening in sleeve 4, thereby allowing oil to pass axially up to the top of sleeve A and into delivery chamber 12 formed by the inner Walls of shaft 2 between the top of sleeve 4 and the bottom of rotor disc I. A constant level reservoir 37 maintains the static oil level in this chamber at a point intermediate between the top of sleeve 4 and the bottom of rotor disc 5. Oil duct tubes I8 symmetrically spaced radially around the axis communicate between the delivery chamber described above and the centrifugal vaporizing annulus or vessel formed in the periphery of rotary retort I. As seen in Fig. 2, these tubes pass beneath the louver openings so that the oil in the tubes is cooled by the air stream. They may pass upwardly through the louver openings instead of through separate holes as shown.

Upon rotation of ducts I8 with retort I about their vertical axis, centrifugal force lifts the oil from its static level in the delivery chamber 12 and delivers it to the periphery of rotating annular retort l. Cowl 8 secured by means of the cylindrical casing l to base plate 6 cooperates with blower vanes 3 to deliver two air streams to the combustion area, the one passin around the outside of lip I4 on the inturned peripheral rim of retort I between the heater casing 9 and the inside periphery of cowl 8, and the other passing around the inside of lip 14 via the pierced louvers 3 in the rotor disc i, as indicated by the arrows. This double air flow results in an intimate and homogeneous mixture of the air with oil vapors escaping around the lip of retort I since no vapor can emerge without encountering both of these enveloping air streams.

The motor 28 may be of the conventional shaded pole squirrel cage induction type consisting of a stator field structure secured to the base 6 and a squirrel cage rotor concentric therewith and secured to rotating hollow shaft 2. Since the power required need be only sufficient to rotate the retort with its air-impelling vanes, this driving motor may'be much smaller than usually required for other oil' burners of comparable ratin g. The intake air ports 4| are positioned to aid in cooling motor 23. To provide electric current to the heater coil II, slip rings 26 and 21 carried by insulating member I3 on shaft '2, are connected to the respective ends of the heater coil II through leads 56 suitably insulated as by ceramic beads, secured to the rotor structure. The insulating brush holders 59 secured to casing I carry the brush assembly 24, 10, 25 which bears on ring 26 and the assembly 22, 1|, 23 which bears on ring 21. Brush springs I0, II provide suitable brush pressure to maintain contact.

The ignition system includes a spark gap 20 between the electrically grounded lip 74 of retort I and the tip of electrode I9 which is supported on cowl 8 by the feed-through insulator 2| It is to be noted that, due to the low starting air velocities and the instant vaporization of the initial oil film, only a very moderate intensity of spark is required reliably to ignite the burner. This permits use of an ignition transformer of only about one-tenththe capacity of those required by the gun-type and centrifugal slingertype burners. A flame switch of fast-action type, incorporated in the burner of this invention, comprises a wire I capable of withstanding flame temperatures, stretched diametrically across the top of cowl 8 and secured thereto at one end by the insulating post stud IT. This wire should be of a metal resistant to oxidation at red heat and having a sufficiently high linear coeflicient of thermal expansion. Such a material is Nichrome, nominally of about 75% nickel, 12% iron and the balance chromium with or without small additions of manganese. The other end of flame-switch wire I5 is secured by a screw IE to the top of lever I3 which is pivoted on pin I4 carried in fork I2 which, in turn, is secured to cowl 8. Thus this end of wire I5 is effectively grounded to the burner. Lever I3 passes through holes 42 in cowl 8 emerging at the bottom to connect with spring 39 secured to cowl 8 soas to maintain the wire I5 under tension. Although lever I3 is shown as passing through cowl 8, it may be secured externally or entirely internally thereof, if desired. In the presence of flame the expansion of wire I5 causes lever I3 to rotate clockwise (as seen in Fig. 1) whereby to open switch 45 which is mechanically coupled to lever I3. Due to the small thermal capacity of wire I5, this system will cause switch 40 to close within a few seconds after the cessation of flame, for any reason, and thus shut down the burner, as explained below. A further safety provision results from the fact that wire I5 is connected in series in the demand switch circuit, as will also later be explained.

The oil delivery line 29 passes from the burner through the constricting needle valve 51, thence through conventional magnetic demand valve 3| and oil level valve 32 before connecting to the oil supply (not shown). The oil level chamber 31 connects to the duct 58 between valves 3! and 32, and contains float 36 secured to lever 35 supported and efiectively pivoted on the bellows type seal 34, thereby permitting chamber 3'! to be sealed, although the movement of the float is transferred to the outside of the chamber by the motion of lever 35 to operate switch 33. Chamber 31 is vented by pipe 38.

Referring now to the control system of Fig. 3, it may be seen that the components of the burner proper are represented at the extreme right of the diagram, whereas the remainder of the diagram represents the components more properly included in the control unit. A five-wire cable, plus suitable connections to ground (viz., the burner), connects these. two portions of the system.

Electric current from the supply line entering at terminals passes through the normally closed contact leaves 49 and 5I of the lookout relay 48 to energize the primary of the step down transformer 55. The low-voltage secondary of this transformer may be connected by the usually remote, conventional thermostat demand switch to energize the demand relay 45. This action closes the normally open relay contacts 45 and 47. Closure of contacts 45 applies the line voltage from terminals 43 to the electric heater element 53 of a thermal bi-metallic type of timedelay switch 59. The bi-metallic element 64 of this time switch is designed when heated to distort enough to close normally-open contacts 65 and 66 which are actuated by strip 64 after approximately two minutes from the time of closure of relay contacts 45. Simultaneously with the closure of demand relay contacts 46, current is also passed from the line through the vaporizer heater element II via the normally (cold) closed flame switch contacts 40 and the slip ring brushes 23 and 25. In addition, current from the line at this time energizes the ignition transformer 61 which is connected in parallel with heater element II. At the end of the mentioned timed preheating interval, contacts 65 and 65 are closed. The closure of contacts 66 applies current fromthe line simultaneously to motor, 28 and to demand valve 3|, there-by bringing oil to the preheated vaporizing retort and initiating combustion due to the existence of a spark as gap 20.

Float switch 33 is arranged to close if oil in the float chamber 31 (Fig. 1) falls below its predetermined level. This closure energizes float relay 6| from the low voltage available at transformer 55, thereby closin normally open relay switch 62 and passing line current through oillevel valve 32 via the demand relay contacts 46. This action opens valve 32 and permits oil from the supply to fill chamber 37 until, at the correct level, switch 33 is again opened, thereby deenergizing valve 32 and shutting off the intake oil flow.

The invention also incorporates a safety lock-- out system including lockout relay 48 which is energized by the line through the normally closed push-button switch 44, if the contacts 54 of normally open thermal lockout timer switch 15 are closed, When the conditions necessary to close contacts 54 have arisen, relay 48 will be energized and'contact arm 49 thereof Will break the main line connection through contact 5| and will close contact 5.0, thus locking itself into energization. By the opening of contacts 49, 5!, the rest of the control system will remain sic-energized until push-button switch 44 is manually opened, which unlocks the system for re-operation. However, contacts 54 will close only if the flame switch 4!] does not open (indicating no flame) for a certain time after contacts 65 have closed, depending upon the predetermined time delay of bi-metallic element 52. In other words, heater 53 for the lockout timer switch receives current only if all the contacts 47, 65 and 40 are closed. This will occur only under abnormal and possibly dangerous starting conditions, viz., when a demand period first causes closure of relay contacts 41, the completion of the preheating period causes closure of contacts 65 and 66, and the absence of flame causes flame switch 40 to remain closed for the specified safety time which is determined by element 52. Push button 44 is preferably located close to the oil burner itself, so that it is necessary for someone to be physically present at the location of the burner where he can observe its condition before he can restore operation of the burner. If the conditions are not normal, the burner will stop shortly after the push button is released.

Operation The operation of the system of my invention is as follows: On closure of the thermostat demand switch 60 the vaporizer retort I is preheated for a time determined by timer 64. At the end of this period the demand valve opens and torque is applied to the rotor .by motor 28. As the rotor I picks up rotational speed, centrifugal force delivers oil to the hot vaporizer annulus in the form of a thin film where it vaporizes substantially instantaneously. Simultaneously, air is delivered at low velocity to the generated oil vapor by the blades 3. Ignition takes place at spark gap 25 due to the presence of a combustible mixture having sufficiently low vapor velocities as to allow attainment of ignition temperature at the spark gap.

After ignition the rotor picks up speed and the air and oil delivery increase proportionally until the flame has its maximum intensity. When the flame has heated the flame wire I5 to a high enough degree, switch 40 opens thereby deenergizing both heater I I and the ignition transformer 61, and at the same time disabling the lookout safety system. At this point sufficient radiant heat is delivered by the flame back to the surface of retort I to maintain its temperature at the vaporizing point without the assistance of heater II, and the system has reached the selfmaintaining stage. At the end of the demand period, switch 66 opens, thereby de-actuating relay 45 which closes demand valve 3| and removes the supply of current to motor 28.

Due to the fact that all the cooperating components of the system of this invention including the constant oil level device 37, the needle valve 51, the centrifugal lift ducts I8, and the constantly heated retort I have operated to sustain no more than a thin film of oil on the retort surface, the closure of the demand valve leaves oil enough to support combustion only for a few seconds and the air flow for this short period is supplied by the angular momentum remaining in the rotor after removal of the motor torque.

the burning cycle.

This results in a clean, smokeless terminatio f In addition, the subsequent air supplied by this after-rotation or power-off spinning while the retort is still very hot completes the combustion of the non volatile components of the oil which had been centrifugelly retained the retort and which prior to this time had not" had opportunity to undergo combustion. This periodic self-cleanin of the non-volatile products is an important feature of the invention because without it a burner of the vaporizing retort type will accumulate a residue of nonvolatile products until the burner becomes inoperative.

In the rare event that wire I5 breaks, the demand switch circuit will be opened, because, as shown in Fig. 3, wire I5 is connected in series with demand switch 60 through lead I6. Thus failure of wire l5 will automatically shut down the burner by restoring all the controls to nonoperating condition. If after breaking, wire I5 should fall so as to touch the oil burner proper or the casing, the connection through lead I6 would not ordinarily be completed, first, because wire I5 is of very light weight and would, therefore, rest lightly on the surface which it touched. Secondly, the grounded parts of the burner are normally coated with enamel, a carbon deposit, an oxide or other substance of very high resistance. As a result, at the voltage employed, the current which could pass through such a high resistance contact would be insufficient to operate the demand relay 45. However, by a slight modification of the circuit connections spurious operation of the demand relay 45 may be completely avoided. For example, terminal point I6 (Fig. 1) may be insulated from lever I3 and directly connected by insulated wire to the upper side of the secondary of transformer 55 (Fig. 3) omitting the ground connections in the flame switch circuit which would then become unnecessary.

I claim:

1. In an oil burner, the combination of a circular retort supported for rotation on a vertical axis, bearing means to support said retort, said retort being formed with a rim comprising an annular inturned peripheral vaporizing surface adapted to carry and vaporize a thin film of oil, oil supply means connected to the inside of said rim, means for rotating said retort so as to form a thin oil film on said vaporizing surface, an oil preheater secured to said rim adjacent said vaporizing surface and having a heat-generating capacity sufficient to vaporize a thin fllm of oil substantially instantaneously, and means for energizing said preheater.

2. The combination accordin to claim 1, characterized in that said retort is comprised of thin, heat-conducting metal, said preheater comprises a circular electric heater coil covered by articulated insulating beads, and a supporting casing encloses said articulated coil and secures the same in heat-conducting relation to said rim behind said oil-vaporizing surface.

3. The combination according to claim 1, characterized in that said retort is comprised of heatconducting material, said preheater comprises an electric heater coil, and a supporting casing encloses said coil and secures the same in heatconducting relation to said rim behind said oilvaporizing surface.

NATHANIEL B. WALES, JR. (References on following page) Number Name Date REFERENCES CITED 1,594,020 Smith July 27, 1926 The following references are of record in the 1 7 4,747 peckelhofi Dec, 9, 1930 file of this patent: 1 1,862,690 Macrae et a1. June 14, 1932 5 1,935,221 Aldrich Nov. 14, 1933 UNITED STATES PATENTS 2,034,214 Pagano June 15, 1937 Number Name Date 2,122,986 Mason July 5, 1938 1,562,799 Smith Nov. 29, 1925 2,235,468 Vidalie Mar. 18, 1941 1,578,530 Krause Mar. 39, 1926 2,373,759 Hourwitz Apr .17, 1945

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