US3143159A

US3143159A - Oil burner air control

Info

Publication number: US3143159A
Application number: US227492A
Authority: US
Inventors: Charles B Smithson
Original assignee: National Union Electric Corp
Current assignee: White Consolidated Industries Inc
Priority date: 1962-10-01
Filing date: 1962-10-01
Publication date: 1964-08-04
Anticipated expiration: 1981-08-04

Description

Aug. 4, 1964 c. B. SMITHSONY 3,143,159

OIL BURNER AIR CONTROL Filed Oct. 1. 1962 lNVEIYTOR.

United States Patent 3,143,159 OIL BURNER AIR CONTROL Charles B. Smithson, Bloomington, 111., assignor to National Union Electric Corporation, Stamford, Conn, a corporation of Delaware Filed Oct. 1, 1962, Ser. No. 227,492 9 Claims. (Cl. 1581.5)

This invention relates to an oil burner air control and more particularly to control means for controlling the fiow of air through the blast tube of the burner.

One of the factors which affects the efliciency of an oil burner is the flow of air to the combustion zone of the burner. While many oil burners heretofore advanced in clude means for controlling such airflow, many of these cause changes in the flame pattern of the burner because an adjustment of the air flow also necessitates adjustment of the position of the burner nozzle relative to the air cone or blast tube outlet. Changes in the flame pattern are undesirable because the efficiency of the burner may be affected adversely. Moreover, many of the secondary air flow control means currently in use are of a complex construction, which results in an increase in the cost of the burner.

Accordingly, it is a general object of the present invention to provide a novel and improved control for the air flow through the blast tube of an oil burner.

Another object is to provide a novel air flow control which is adapted for use with both low andhigh pressure type oil burners.

A more particular object is to provide a novel control means for controlling the air flow through the blast tube of an oil burner which does not materially change the shape of the flame of the burner upon adjustment of the air flow.

These and other objects will become apparent upon making reference to the detailed description which follows and accompanying sheets of drawings, in which:

FIG. 1 is a side-elevational view, with some parts in section and portions thereof broken away to show underlying parts, of the blast tube of an oil burner employing an air flow control embodying the features of the present invention;

FIG. 2 is an enlarged plan view of a portion of the blast tube of FIG. 12, with a portion of the tube removed to show underlying parts and taken substantially along the line 22 of FIG. 1;

FIG. 3 is a vertical sectional view taken substantially along the line 3-3 of FIG. 1; and

FIG. 4 is a vertical sectional view taken substantially along the line 4-4 of FIG. 1, but with a portion of the structure removed.

Briefly described, the present invention contemplates an improved flow control means for the air flow through the blast tube of an oil burner. Such control means is disposed in the blast tube of the burner immediately upstream of the fuel atomizing nozzle thereof and comprises a centrally disposed axially fixed baffle in the blast tube and an axially shiftable sleeve member having a portion engaging the inner wall of the blast tube, another portion engaging the periphery of the baffle, and an intermediate connecting portion. The baffle engaging portion is provided with a plurality of circumferentially spaced axially extending slots, the effective size of which may be varied upon movement of the sleeve member.

By reason of the foregoing construction, the air flow will be caused to converge as it enters the sleeve member and thereafter to diverge or flow radially outwardly around the baffle toward a ring of whirl vanes and an air cone at the open end of the blast tube. Because of the foregoing location of the control means and the flow path taken by the air passing through and downstream there- 3,143,159 Patented Aug. 4, 1964 of, a more positive control of the flow is obtained. In addition, adjustment of the control means to change the amount of air flow does not change the position of the atomizing nozzle relative to the end of the blast tube. Consequently, the shape of the flame pattern at the discharge end of the blast tube is not changed to any material degree. Moreover, the air control can readily be used with blast tubes of different lengths.

In FIG. 1, a portion of a low pressure oil burner embodying the features of the present invention is illustrated. The oil burner includes a casing, the lower portion of which is indicated at 35, which serves as a mounting for the main components of the burner. Thus, an electric motor (not shown) is mounted at one side of the upper portion of the casing, the motor being drivingly connected to a secondary air fan (not shown) mounted within the upper portion of the casing. The motor also drives a combination oil metering and primary air pump unit mounted on the opposite side of the upper portion of the casing. A portion of the combination oil metering and primary air pump is indicated at 30 in FIG. 1.

The pump unit 30 receives oil from a fuel tank, and a mixture of primary air and oil under pressure is delivered to a diffusor 36 mounted in one end of the lower casing portion 35. A pipe 37 connects the outlet of the pump unit 30 with the diffusor 36. In addition, the secondary air fan delivers a flow of secondary air to the lower casing portion 35 and thence through a blast tube 40 extending outwardly from the opposite end of the casing portion 35.

The frothy air-oil mixture obtained from the pump unit 30 is separated into its liquid and air phases in the diffusor 36. Liquid oil under pressure collecting in the bottom of the diffusor 36 is directed axially through the blast tube 40 to an atomizing nozzle 38 by means of a pipe 366 (FIG. 1), the nozzle 38 being disposed upstream of an air cone 44 mounted on the remote end of the blast tube 40. Air under pressure above the level of the oil in the diffusor 36 is supplied to the atomizing nozzle 38 by means of another pipe 367. The separate oil and air flows through the

pipes

366 and 367 are recombined in the nozzle 38 to be thereafter discharged axially outwardly from a central orifice 368 (FIG. 3) in the end of the nozzle.

In order to ignite the atomized oil-air mixture discharging from the nozzle 38, a starting electrode assembly 43 is provided. As will be apparent in FIGS. 1 and 3, the assembly 43 comprises a pair of electrodes 371 mounted in radially spaced axially extending insulators 372 supported by a baffle 46 comprising a portion of a secondary air flow control means 400 to be hereinafter described. The terminal ends, indicated at 373, of the electrodes 371 are closely spaced adjacent the orifice 368 so as to permit a high voltage spark to be maintained thereacross to ignite the atomized fuel-air mixture. Such spark is obtained from the secondary winding of a starting transformer (not shown), the potential being conducted to the electrodes 371 by a pair of wires or cables 374. A spark is maintained across the terminals 373 for a predetermined period suflicient to ignite the mixture from the nozzle 38, the spark thereafter being discontinued unless restarting is necessary. A set screw 375 (FIG. 1) permits adjustment of the entire diffusor assembly relative to the housing portion 35 so as to regulate the distance between the nozzle 38 and the outlet, indicated at 379, of the air cone 44. i

The air flow and flame pattern are controlled in part by a ring of vanes 376 (FIGS. 1 and 4) disposed around the inner peripheral wall of the blast tube 40 adjacent the discharge end thereof and by a tapered end wall 380 on the air cone 44. Each vane 376 is provided with a plurality of edge tabs or fingers 377 (FIGS. 1 and 4) which extend through slits in the blast tube 40, and which are thereafter bent over into engagement with the outer surface of the blast tube to retain the vanes in position. As seen in FIG. 1, each vane 376 extends both forwardly and rearwardly of the nozzle orifice 368, and the forward ends of the vanes 376 extend beyond the end of the blast tube 40 into the tapered portion of the cone 44 defined by the end wall 380 and terminate at or closely adjacent the discharge opening 379 of the cone. The vanes 376 are arranged at suitable angles so as to impart a whirl to the secondary air flow through the blast tube. The angularly disposed vanes 376 and the tapered annular end wall 380 of the cone 44 divert the secondary air into the atomized oil-air stream from the nozzle 38 whereby to obtain intimate penetration and mixing of the two streams and highly efficient combustion. The mounting of the vanes 376 on the blast tube 40 rather than on the air cone 44 facilitates substitution of other cones having different outlet diameters.

Secondary air from the secondary air fan enters the inner or upstream end, indicated at 378 (FIG. 1), of the blast tube 40. The secondary air flow thus proceeds through the blast tube and toward the secondary air flow control means 400 which serves to control the quantity and direction of the secondary air flowing past the control 400 and through the vanes 376 and discharge opening 379 in the air cone 44.

As will be apparent from FIGS. 1 and 2, the secondary air flow control means 400 comprises a shiftable sleeve member 47, the electrode and nozzle support disk or baflle 46, and a manually adjustable means 48 for shifting the sleeve member 47 relative to the baflle 46 and blast tube 40.

As best shown in FIG. 2, the sleeve member 47 comprises a tubular upstream portion 401 engaging the inner surface of the blast tube 40, an intermediate conically tapered or connecting portion 402, and a downstream tubular portion 403 enclosing and peripherally engaging the baflle 46. The baffle 46 is provided with an annular axially extending flange 405 for supporting the tubular portion 403. The upstream portion 401 is of relatively short axial extent, while the downstream portion 403 has a substantial axial length permitting a substantial range of movement without disengagement from the baffle 46. The tubular portion 403 is provided with a plurality of circumferentially spaced axially elongated openings or slots 404 therethrough, such openings extending for substantially the full length of the portion 403 and thus overlying the baffle 46 throughout the range of movement of the sleeve 47. A ring of smaller openings or apertures 406 is provided in the conical portion 402, such openings 406 at all times remaining unobstructed.

The sleeve 47 is supported in the blast tube 40 by means of the wall-to-wall sliding engagement between the portion 401 and the inner wall of the tube 40, by the engagement between the inner wall of the portion 403 and the flange 405, and by a plurality of circumferentially spaced radially outwardly extending legs 407 secured to the outer periphery of the portion 403 at the downstream end thereof, and also engaging the inner wall of the tube 40.

The manually adjustable means 48 for controlling the position of the sleeve 47 comprises, in this instance, an elongated bar or strap 411 secured to the portions 401- 402 of the sleeve 47, the bar 411 extending axially upstream through the inlet end 378 of the blast tube 40 and into the lower casing portion 35. The opposite or upstream end, indicated at 412, of the bar 411 is bent at a right angle and is provided with a threaded opening for receiving the threaded shank of an elongated adjusting screw 413. The screw 413 has an enlarged head 414 provided with a slot to facilitate manipulation thereof, the remote inner end, indicated at 416, of the screw 413 being unthreaded and supported in an opening in the end of an upstream lug 417 formed in the casing portion 35. Thus, manipulation of the screw 413 effects axial movement of the bar 411 and a shifting of the sleeve member 47. A spring 418 is provided between the screw head 414 and the adjacent end wall of the casing portion 35 to maintain the screw 413 in an adjusted position.

It will be apparent that the axial position of the sleeve 47 relative to the bafile 46 determines the eflective area of the sleeve slots, such area being the summation of the open upstream portions, indicated at 404a, of the slots 404 to the left of the bafile 46 as viewed in FIGS. 1 and 2. Thus, axial shifting of the sleeve 47 in the blast tube 40 serves to enlarge or reduce the size of the upstream slot areas 404a thereby varying the effective cross-sectional area of the blast tube with respect to the secondary air flow.

Because of the configuration of the sleeve 47, air entering the inlet end 378 of the blast tube and approaching the sleeve 47 will first be caused to converge toward the center of the tube because of the conical taper of the intermediate portion 402. As the secondary air flow enters the portion 403 its direction is substantially axial, and then the baffle 46 diverts the air flow radially outwardly through the open slot portions 404a toward the wall of the blast tube 40. Such convergence and divergence of the flow is indicated by arrows in FIG. 1. After passing through the exposed slot portions 404a of the sleeve 47, the secondary air flow continues axially through the blast tube until it reaches the vanes 376. As previously mentioned, the vanes 376 impart a whirl or vortex action to the flow which is directed through the opening 379 into the atomized'air-oil stream discharging from the nozzle 38 by the annular inwardly tapering end Wall 380 of the air cone 44. The secondary air flow is thus brought into intimate contact with unburned oil particles, and other combustible products, to thereby insure high combustion efliciency. Such efliciency results from the coaction between the whirling secondary air fiow provided by the vanes 376, the annular inwardly tapering end wall 380, and the size of the opening 379. For example, with the blast tube and air control arrangement just described, it is possible to obtain a C0 content in the combustion gas of about 12-14% as compared with the l012% normally considered to be a high level of efficiency.

Moreover, with the foregoing construction, a generally spherical or ball-shaped flame pattern is obtained throughout a wide range of fuel-air delivery rates, as for example between a range of one-half to two and one-quarter gallons of fuel per hour. This highly desirable result is at-, tributable to the fact that the secondary air is not forced along the central axis of the blast tube, which would tend to produce an elongated torch-like flame, and to the further fact that the spin-imparting vanes for the secondary air i.e. the angular vanes 376) are located solely at the blast tube outlet.

As previously noted, the ring of smaller holes 406 in the conically tapered portion 402 of the sleeve 47 at all times remain open so that regardless of the position of the sleeve, secondary air will never be completely shut off. While the holes 406 are provided primarly to comply with certain safety requirements relating to oil burners, they also contribute to an over-all balancing of the secondary air flow and flame pattern. Another opening 408 in the baflle 46 also serves to balance the flow through and downstream of the control 400. v

The blast tube air control means 400 has been illustrated and described in conjunction with a low pressure oil burner utilizing a mixture of oil and primary air and a diffusor so that the control 400 operates on secondary air. However, it will be apparent that the same blast tube air control arrangement is also usable in a high pressure oil burner which does not employ a dilfusor or separate primary and secondary air sources. In such case, oil alone is supplied under pressure to the nozzle in the blast tube and the blast tube air control 400 regulates the sole supply of air to the blast tube.

Although the invention has been described with particular reference to a certain specific structural embodiment, it should be understood that various modifications and equivalents may be resorted to without departing from the scope of the invention as defined in the appended claims.

I claim:

1. In an oil burner having a blast tube with a nozzle disposed centrally therein, control means for regulating the flow of air through said blast tube, comprising a transverse centrally disposed baffle in fixed relation in said blast tube and of smaller diameter than said blast tube, a shiftable sleeve member having a portion at the upstream side of said bafiie slidably engaging the interior of said blast tube and a portion slidably engaging the periphery of said bafile, said last-named portion having at least one opening therein, and means for moving said shiftable member axially of said blast tube to vary the effective size of said opening at the upstream side of said bafl-le, whereby the flow of air passes axially through said sleeve member to said baflie, thence radially outwardly through said opening, and thence axially between said sleeve member and said blast tube.

2. The structure of claim 1, further characterized in that a plurality of openings are provided in said bafiieengaging portion of said sleeve member, said openings comprising a plurality of circumferentially spaced axially extending slots.

3. The structure of claim 2, further characterized in that said sleeve member includes a tapering portion connecting said blast tube-engaging and bathe-engaging portions, said tapering portion being effective to cause convergence of said air flow toward the portions of said slots upstream of said bafiie.

4. In an oil burner including a blast tube and nozzle means for discharging a fluid stream from said tube, the improved means for controlling a flow of air through said blast tube, comprising a centrally disposed transverse bafiie of lesser diameter than said tube and rigidly secured centrally therein, said bafile providing a support for said nozzle means, a sleeve member mounted in said blast tube and having a portion slidably engaging the inner wall of said tube at the upstream side of said baflie, another portion slidably engaging the outer periphery of said baffle, and a portion connecting said blast tube-engaging and bathe-engaging portions, said baflle-engaging portion having a plurality of openings therein, and manually adjustable means for shifting said sleeve member to control the effective size of said openings at the upstream side of said baffie, said sleeve member and said bafile being eifective to cause convergence of said air flow upstream of said baflie and divergence of said flow radially outwardly through said openings and around said battle.

5. The flow control device of claim 4, further characterized in that said blast tube and baflie are circular in cross section, said blast tube-engaging and baflle-engaging portions are cylindrical, and said connecting portion is conical.

6. The control device of claim 5, further characterized in that said bafiie comprises a circular disk disposed transversely of the axis of said blast tube, said disk having an annular axially extending flange therearound for engaging and supporting said sleeve member.

7. The flow control of claim 4, further characterized in that said blast tube includes a plurality of vanes carried at the discharge end thereof for imparting a whirl to said air flow.

8. The flow control of claim 7, further characterized in that an annular air cone is provided having a cylindrical mounting portion and an annular inwardly tapering outlet portion, said cylindrical mounting portion being fitted around the outside of said end of the blast tube, and said vanes are secured solely to said blast tube whereby to permit replacement of the cone without disturbing the vanes.

9. In an oil burner having a blast tube and centrally disposed nozzle means, the improved means for controlling the flow of air through the blast tube comprising a disk-shaped baffle of lesser diameter than said tube and mounted in fixed relation therein, said bafiie supporting said nozzle means, a sleeve movably mounted in said blast tube, said sleeve having an enlarged diameter portion slidably engaging the blast tube upstream from said bafile and a reduced diameter portion spaced from said blast tube and slidably engaging the periphery of said bafiie, said reduced diameter sleeve portion having a plurality of circumferentially spaced openings, adjustable means for shifting said sleeve axially of said blast tube to vary the size of said openings at the upstream side of said bafiie, whereby air flows axially through said sleeve, radially outwardly through the adjusted openings, and thence axially through the space between said sleeve and said tube, said sleeve being free of whirl-imparting means, and a plurality of whirl-imparting vanes at the discharge end of said blast tube downstream from said sleeve.

Kermode Aug. 8, 1916 Robb Feb. 5, 1963

Claims

1. IN AN OIL BURNER HAVING A BLAST TUBE WITH A NOZZLE DISPOSED CENTRALLY THEREIN, CONTROL MEANS FOR REGULATING THE FLOW OF AIR THROUGH SAID BLAST TUBE, COMPRISING A TRANSVERSE CENTRALLY DISPOSED BAFFLE IN FIXED RELATION IN SAID BLAST TUBE AND OF SMALLER DIAMETER THAN SAID BLAST TUBE, A SHIFTABLE SLEEVE MEMBER HAVING A PORTION AT THE UPSTREAM SIDE OF SAID BAFFLE SLIDABLY ENGAGING THE INTERIOR OF SAID BLAST TUBE AND A PORTION SLIDABLY ENGAGING THE PERIPHERY OF SAID BAFFLE, SAID LAST-NAMED PORTION HAVING AT LEAST ONE OPENING THEREIN, AND MEANS FOR MOVING SAID SHIFTABLE MEMBER AXIALLY OF SAID BLAST TUBE TO VARY THE EFFECTIVE SIZE OF SAID OPENING AT THE UPSTREAM SIDE OF SAID BAFFLE, WHEREBY THE FLOW OF AIR PASSES AXIALLY THROUGH SAID SLEEVE MEMBER TO SAID BAFFLE, THENCE RADIALLY OUTWARDLY THROUGH SAID OPENING, AND THENCE AXIALLY BETWEEN SAID SLEEVE MEMBER AND SAID BLAST TUBE.