US2255929A - Thermally controlled oil burner - Google Patents

Description

p 1941 M. D.'HUSTON ETAL 2,255,929

frHERMAL Y CONTROLLED 0IL.BURNER Original Filed March 4, 1935 Sheets-Sheet l I fillorz D-f/usian Jackson (ifizlnrorc Gttomq txaminer UNITED STATES PATENT OFFICE THERMALLY CONTROLLED OIL BURNER Milton D. Huston and Jackson G. Gilmore, Co-

lumbus, Ohio, assignors to Columbus Metal Products, Inc., Columbus, Ohio, a corporation of Ohio Application March 4, 1935, Serial No. 9,249 Renewed February 2, 1939 12 Claims.

This invention relates to improvements in hydrocarbon oil burners, and an object thereof resides in the provision of an oil burner wherein is embodied an apertured retort having a closed bottom and an open top and wherein a valve mechanism, thermally responsive to the temperatures prevailing within and adjacent to the retort, is provided for automatically controlling the rate of delivery of the liquid fuel to the bottom of the retort for vaporization and air admixture purposes.

It is another object of the invention to provide a safe, economical and efficient burner of the character indicated which possesses an unusually wide range of operation by which the burner is adapted for high and low stages of combustion without involving the use of extraneous ignition or pilot flames for efiecting or sustaining low-stage operation, and wherein clean steadily maintained combustion is provided at all stages and smoke or soot formation rendered negligible.

For a further understanding of the invention, reference is to be had to the following description and the accompanying drawings, wherein:

Fig. 1 is a vertical sectional View taken through an oil burner and the oil flow controlling valve mechanism employed in connection therewith;

Fig. 2 is a similar view, the plane of the figure being substantially at right angles to that disclosed in Fig. l, as indicated by the line II-JI of Fig. 1;

Fig. 3 is a top plan view of the retort;

Fig. 4 is a detail vertical sectional view of a slightly modified form of the retort and the air distributing passages formed in connection therewith;

Fig. 5 is a view in side elevation of the burner comprising the present invention installed beneath a water tank and also showing diagrammatically the electrical hook-up for a motor used to drive a blower for the burner.

Fig. 6 is a longitudinal sectional view of a modified form of valve provided with a safety feature to prevent over-heating;

Fig. '7 is a vertical sectional view of the upper portion of the retort with a sleeve installed to vary the effective size of the outlet.

The oil burner disclosed in the accompanying drawings comprises a retort l preferably of sheet metal, the said retort embodying a cup-shaped bottom section 2 and a separable substantially frusto-conical upper section 3. The upper edge of the bottom section 2 is flanged to produce an annular seat I adapted for the reception of a seating ring 5 and a lower outwardly flanged portion 6 of the upper section 3. The flange 6 at the bottom of the upper section is engaged with and positioned in an annular groove formed in connection with a bead 1 provided at the lower end of an annular air-receiving housing 8 which constitutes for all intents and purposes an integral part of the upper section 3 of the retort. The retort as a whole is positioned within a drum-like outer casing III, which includes upper and lower members II and I2 respectively, which are united by having their meeting edges outwardly flanged as at l3 and perforated for the reception of threaded fastening devices I. The upper member H of the casing is formed with a central opening surrounded by an upstanding boss 15 which is adapted to closely receive the cylindrical extension l6 formed on the upper end of the retort section 3. A plurality of circularly arranged relatively spaced air outlet openings l6a. are formed in the upper member ll adjacent to the boss IS. The lower member I2 of the casing i0 is provided at the bottom thereof with an inturned flange lla forming an enlarged opening 11 which is of a diameter sulflcient to permit of the passage of the bottom section 2 of the retort therethrough, the opening I! serving to provide for the proper cooling of the bottom section 2 by air flow thereover and further admits of the delivery of secondary air to the interior of the casing.

In order to admit oil in regulated quantities into the bottom of the retort for vaporization and combustion purposes, the lower wall l8 of the cup-shaped bottom section 2 is provided centrally with a convex depressed region I! which is received within a corresponding socket 20 provided in a boss 2| formed in connection with a valve barrel 22. This valve barrel is preferably formed from a material possessing good heat conductivity and a relatively high coeflicient of expansion, such as an aluminum alloy. A screw 23 having a convex head and an axially extending port 24 has its threaded shank received in a vertically threaded opening formed centrally of the barrel 22 whereby the tightening of the screw 23 serves to unite the valve mechanism with the bottom of the retort, the port 24 providing for oil flow from within the valve barrel to the bottom of the retort. Additionally, the valve mechanism and the bottom of the retort are operatively supported for convenient removal in connection with the burner, by means of a bail 25, which is pivotally secured as at 26 to the lower member 2 of the casing l0. When positioned as disclosed in Fig. 2, the lower part of the bail underlies the central region of the valve barrel 22 and is equipped with a hand screw 21, the upper end of the latter engaging with a bearing 28 provided in the under part of the barrel 22. By loosening the screw 21, the bail may be swung to a position permitting of the withdrawal of the bottom section 2 of the retort from the outer casing.

One end of the barrel 22 is provided with an internal threaded socket for the reception of the threaded extension 29 of an orifice plug 30, the latter being formed with an external collar 3| which is arranged for close engagement with the adjoining end of the barrel 22. The plug 30 is formed with a longitudinally extending passage 32 which communicates with an oil supply pipe 33 leading from any suitable source of liquid fuel supply, the oil being fed through the pipe 33 preferably by gravity. A coupling 34 is utilized to connect the pipe 33 with the outer end of the plug 30'. The passage 32 terminates at its inner end in a valve seat 35 with which normally engages a conical head 36 of a valve rod 31. The valve rod is formed from a metal having a lower coefiicient of expansion than the materials from which the barrel 22 is formed, such, for instance, as Invar steel. The rod 31 is disposed within a chamber 38 formed in the barrel 22 and which is in open communication with the port 24 leading to the bottom of the retort, passage of oil from the supply pipe 33 into said retort being normally prevented by the engagement of the head 36 with the seat 35 of the plug 30.

To maintain this engagement of the head 36 with the seat 35, the opposite end of the barrel 22, with respect to that which receives the plug 30, is also formed with a threaded socket for the reception of a metallic fitting 39. The outer end of this fitting is provided with a stufiing box or packing gland 40 for the stem 4| of a tem- Derature regulating wheel 42. The inner end of the stem 4| is threaded as at 43 within an internally threaded socket formed in the fitting 39, and, also, the inner end of the stem 4| is provided with a socket 44 in which is received a relatively strong coiled spring 45, the latter being confined between the closed end of the socket 44 and a spherical head 46 provided on the end of ,the valve rod 31 opposed to the end of the latter provided with the conical head as.

In operation, it will be seen that the force exercised by the spring 45 will serve to normally maintain the conical head 36 of the valve rod in fiuid flow arresting engagement with the seat 35. However, when the valve barrel 22 becomes heated, the same will expand to a considerably greater extent than the thermally unresponsive valve rod 31. Since one end of the valve rod is in eifect carried by the valve barrel, the expansion of the latter will result in moving the conical head 36 of the valve rod from engagement with the seat 35, thereby allowing oil to flow from the supply pipe to the chamber 38 and thence through the port 24 into the bottom of the retort Conversely upon the cooling of the valve barrel, the conical head 36 of the valve rod will again be brought into firm seating engagement with the seat 35 and will be held in such engagement by the force of the spring 45, arresting oil flow to the retort. By adjusting the wheel 42, toward and away from a fixed stop arm 41, the response of the valve rod to variations in temperature of the valve barrel may be regulated, whereby to render the burner adaptable to varying grades of oil having different boiling ranges and to adapt the burner to minor variations in air supply. Obviously, by turning the wheel 42 so that the socket 44 in the stem 4| thereof permits of maximum penetration of said head into the socket, against the resistance oifered by the spring 45, the more delayed will be the response of the valve rod to the expansion of the valve barrel in permitting the flow of oil past the orifice seat 35. However, with the head 46 in the outer end of the socket 44, as shown in Fig. 1, virtually any ex pansion on the part of the valve barrel will result in the opening of the valve orifice 35 so that when the head 46 of the valve rod is thus positioned, a maximum delivery of oil to the retort may be readily procured.

The oil thus admitted to the bottom of the retort in response to the opening and closing of the thermally actuated valve mechanism, spreads in the form of a thin body on the bottom |8 of the retort. During the normal operation of the burner, the heat generated by the combustion of the fuel sometimes within but generally above the retort heats the fuel to vaporizing temperatures and the fuel vapors pass upwardly into the frusto-conical upper section 3 of the retort, wherein the fuel vapors are admixed with primary air to produce a hydroxylated fuel mixture. To attain such hydroxylation, the present invention provides the upper section 3 of the retort with horizontal rows of spaced perforations 48, 49 and 5|. The perforations 48 are so disposed as to communicate with the housing ring 8, and as shown in Fig. 2, this ring connects with a conduit 50 which preferably leads to a relatively small motor driven fan by which air under atmospheric pressure or with several ounces of pressure may be admitted into the housing ring and thence forced through the perforations 48 into the interior of the retort for admixture with the vaporized fuel. The axes of the lower row of perforations 48 are preferably downwardly inclined toward the bottom I8 in order to direct air toward the bottom of the retort.

The perforations 49 establish communication between the interior of the retort and the casing I0, permitting air under atmospheric or flue pressure to pass through the perforations 49 for admixture with the fuel vapors, the primary body of air coming from the housing 8 or the atmosphere through perforations 48, 49 and 5| Near the upper end of the section 3, at the bottom of the extension l6 thereof, the retort is provided with an upper row of perforations as indicated at 5| for admitting air into the retort. This primary air is admitted only in suflicient quantities to effect the formation of what is known as a hydroxylated mixture but insuflicient to'effect active combustion.

To further control the combustion or flame of the burner, the upper member of the casing I0 is provided with a removable goose neck" conduit 52 which is open at its lower end and communicates directly with the interior of said casing, providing air travel through the conduit 52 toward the downwardly directed outlet 53 at the upper end thereof. Surrounding the outlet 53 is an air distributing cone 54 which is supported in connection with said conduit by means of a threaded screw 55, the cone 54 being provided contiguous to its base, with a row of down- Wardly and outwardly directed perforations 56. In addition to the normal supply of air through the ooiiduit 52, a more positive advance thereof may be effected, as disclosed in Fig. 4, by providing the air supply pipe 50 with an upwardly directed nozzle 51, which enters the bottom of the conduit 52, whereby the upwardly moving coluirm of air may be discharged under a small positive pressure through the perforations in the cone 54, if desired.

In the operation of this oil burner, there exists the principle of reciprocal action between the oil-admitting valve and the temperatures developed by the burning of the fuel. The valve 31 opens and closes entirely by reason of temperature changes which are developed by the operation of the burner itself. When active combustion initially takes place within the retort, near its bottom wall Hi, the temperature of the lower portion of the retort is increased, and this increased temperature is transmitted to the heat-conducting material from which the valve barrel or casing is formed, causing the latter to expand and move away from the tapered end of the valve rod to increase the flow of oil into the retort. This results in producing a greater body of oil within the bottom of the retort, which vaporizes and removes heat from the bottom wall l8, causing the cooling of the valve barrel or casing and consequent diminution in the flow of oil to the retort.

The vaporized fuel within the retort is admixed with air forced into the retort through the conduit 50 and the perforations 48 and with a body of air admitted through the perforations 49 under substantially chimney draft pressure. Also, when the burner is actively operating at high stage combustion, air will be introduced into the vaporized fuels by way of the perforations lid and 5| and the air distributing cone 54. When the burner is operating to produce its maximum delivery of heat, combustion takes place above the mouth N5 of the retort in the form of a round pan-like flame. However, as the supply of oil is diminished, this flame recedes within the retort or toward the bottom I thereof, thereby increasing the temperature of the valve casing 22 and increasing automatically the supply of oil to the retort. In other words, when the fire begins to be starved for lack of oil to support it, the flame drops from its normal position at the top of the burner down into or toward the retort, where its proximity to the oil valve causes the valve to open and release more oil. As more oil is delivered to the bottom of the retort providing for greater vaporization or formation of larger quantities of oil vapor, the flames travel upwardly to again assume their normal position.

The provision of the conical upper section 3 of the retort provides for increased velocity of travel of the oil vapors following their generation through or toward the upper portion or mouth of the retort and provides an eiiective inter-mixing of the generated oil vapor with the primary bodies of air, enabling efficient combustion to be maintained over widely varying combustion ranges. In fact, a combustion range of to 1 can be readily maintained without fouling of the burner by reason of carbon or soot formation. This extreme range of flexibility enables the burner to operate efficiently when heat demands are either large or small. The burner has the advantage of being composed of but Framiner few and simple parts which are readily seperable for inspection, cleaning or repair purposes.

The motor 10 employed in operating the fan H for delivering air under pressure to the retort may be of the type which is connected with a thermostatic switch 12 disposed in spaced relation from the burner, the operation of th fan serving to produce high temperature rates of combustion, while a supply of air under ordinary fiue pressure will be sufficient to maintain the low or stand-by rate of combustion, substantially after the manner of a pilot flame. The device, after combustion has been initiated, is fully automatic in its operation and requires no further attention. To initiate combustion, a small amount of oil may be introduced from the top of the burner into the bottom of the retort and lighted by a suitable taper. As soon as this pilot combustion has been effected, the temperature is transmitted to the valve casing which results in the opening of the valve 31 and its subsequent intermediate opening and closing. However, after a certain period of operation, an equilibrium is attained in which the combustion rate becomes apparently constant.

It will be noted that the valve casing 22, the plug 30 and the supply pipe 33 are arranged at an acute angle with respect to the horizontal and the upper walls of the chamber 38 are reversely angled. This is done in order to prevent minute air and oil vapor bubbles in the oil supply from interfering with the regularity of the oil flow past the orifice 35, since if air bubbles or gas are present, the same will tend to rise toward the highermost portions of the body of oil in which they are disposed. the vapors condensing in the form of oil and the air bubbles venting through inlet port 24 and through suitable vent at end of oil supply pipe 33.

In the modified form of valve shown in Fig. 6, a second seat 58 is formed in a wall 59 provided in connection with the valve casing 22. The head 36a on the valve stem 31a is provided with a tapered rear face and, in the event the unit overheats, the valve casing will expand to such an extent that the rear face of the valve will contact with the seat 58 and cut oil? the oil flow to permit the temperature of the burner to fall.

To further control the burner, a sleeve 60, shown in Fig. 7, is removably positioned upon the upper end 16 of the retort. By varying the size of the opening in this sleeve, the burner may be adapted to various uses requiring different degrees of heat.

What is claimed is:

1. An oil burner comprising a vessel having a bottom, conical side walls and an open mouth of restricted diameter in the upper end thereof, said side walls being provided with distinct groups of primary and secondary openings for admitting air into said vessel, means for introducing oil into the bottom of said vessel, a casing surrounding said vessel and spaced from the walls of the latter providing for the delivery of air under substantially atmospheric pressures through the secondary air admitting openings of said vessel, a. manifold surrounding the side of said vessel adjacent to the primary group of openings, and means for admitting air under forced draft into said manifold for passage into the interior of said vessel through said primary openings, whereby to provide-for increasing the pressure on the air passing through said primary group of openings independently of the secondary group of openings.

2. IQ, oil burning apparatus, a burner vessel havifiE a closed bottom, upwardly extending side walls and an open top, the side walls of said vessel being formed with spaced groups of primary and secondary air-admission openings of restricted diameter, fuel supply means for delivering a regulatable quantity of a, liquid fuel to the bottom of said burner vessel, a casing surrounding said vessel and spaced from the side walls thereof to provide a draft chamber, the lower portion of said chamber being in communication with the atmosphere and the upper portion thereof in communication with said secondary group of openings, whereby to provide a substantially constant volumetric flow of air under atmospheric pressure from said chamber and into said vessel through said secondary air-admission openings, and means for effecting a variable volumetric inflow of air into said vessel through said primary air-admission openings during different stages of burner operation.

3. In oil burning apparatus, a vessel having a closed bottom, upwardly extending side walls and an open top, an open-bottomed casing surrounding said vessel and spaced from the side walls of the latter to provide a natural draft chamber, the top of said casing contiguous to the rim of the open top of said vessel being provided with openings of restricted diameter, the side Walls of said vessel being formed with primary and secondary groups of air-inlet openings of restricted diameter, a manifolding hood surrounding the walls of said vessel for governing the inflow of air into said vessel through the primary group of openings only, means for delivering air to said hood for passage through the primary group of openings controlled thereby into said vessel, means for delivering liquid oil to the bottom of said vessel, and an inturned flange formed with the bottom of said casing, said flange projecting toward the bottom of said vessel and spaced from the latter sufficiently to provide a constant flow of air across the bottom of said vessel and through said natural draft chamber and said secondary group of air inlet openings at all stages of burner operation.

4. An oil burner of the hydroxylating type comprising 'a vessel having a closed bottom, upwardly extending side walls and an open top, a casing surrounding said vessel and spaced from the bottom and side walls thereof to provide a natural draft chamber, the top of said casing contiguous to the rim of the open top of said vessel being provided with openings of restricted diameter; the side walls of said vessel being formed with primary and secondary groups of air-inlet openings of restricted diameter, a manifolding hood partially surrounding the side walls of said vessel for governing the inflow of air into said vessel through the primary group of openings only, means for delivering air to said hood and the interior of said vessel through the primary group of openings controlled by said hood, means for delivering liquid oil to the bottom of said vessel, and an inwardly directed flange formed with the bottom of said casing, said flange providing for a constant flow of air exteriorly over the bottom of said vessel and upwardly through said draft chamber under atmospheric pressures for passage into said vessel through the said secondary group of openings and through the restricted openings formed in the top of said casing for admixture with vaporized or burning fuels exiting from the open top of said vessel.

5. Oil burning apparatus comprising a burner vessel having a closed bottom, upwardly extending side walls and an outlet in the top thereof, means for maintaining a pool of liquid oil in the bottom of said vessel, the side walls of said vessel above said pool of liquid oil being provided with a group of restricted relatively spaced primary air admitting openings, a second group of spaced restricted openings formed in said side walls between said primary group and the outlet in the top of the vessel, a casing surrounding said vessel and forming a draft chamber between the outer walls of said vessel and the inner walls of the casing, said casing having a top wall formed with an opening through which the outlet of the burner vessel projects, air conducting means connected with said vessel for supplying air from the exterior of said burner apparatus directly to the first group of openings in the side walls of said burner vessel, and a plurality of air supplying openings formed in said top wall immediately adjacent to the outlet of the burner vessel and operative to effect the mixing of air withdrawn from said draft chamber into the fuel mixture escaping from the outlet of said burner vessel.

6. Oil burning apparatus comprising a burner vessel having a closed bottom, upwardly extending side walls and an open throat of restricted diameter in the top thereof, means for maintaining a pool of liquid oil in the bottom of said vessel, the side walls of said vessel above said pool of liquid oil being provided with a group of restricted relatively spaced primary air-admitting openings, a second group of spaced air-admitting openings formed in said side walls between said primary group and outlet throat, a casing having an open bottom and a top wall, said casing surrounding said burner vessel and spaced from the walls thereof to form a draft chamber for the passage of air into said vessel through the second group of openings, a manifolding hood surrounding said vessel and covering said primary group of openings, means extending exteriorly of said casing for supplying air to said hood and primary openings, and a third set of air admitting openings formed in the top wall of said casing and disposed contiguous to and surrounding the outlet throat of said vessel, said third set of openings serving to admix air withdrawn from said draft chamber into the fuel mixture issuing from said throat to promote combustion of said mixture.

7. Oil burning apparatus comprising a burner vessel having a closed bottom, upwardly extending side walls and an open throat of restricted diameter in the top thereof, means for maintaining a pool of liquid oil in the bottom of said vessel, the side walls of said vessel above said pool of liquid oil being provided with a group of restricted relatively spaced primary air-admitting openings, a second group of spaced air-admitting openings formed in said side walls between said primary group and outlet threat, a casing having an open bottom and a top wall, said casing surrounding said burner vessel and spaced from the walls thereof to form a draft chamber for the passage of air into said vessel through the second group of openings, a manifolding hood surrounding said vessel and covering said primary group of openings, means extending exteriorly of said casing for supplying air to said hood and primary openings, a third set of air admitting openings formed in the top wall of said casing and disposed contiguous to and surroundingAlfi outlet throat of said vessel, said third set of openings serving to admix air withdrawn from said draft chamber into the fuel mixture issuing from said throat to promote combustion of said mixture, a hollow elbow member arising from the top wall of said casing, the interior of said member being in open communication with said draft chamber, and a perforated air discharging head formed with the outer portion of said elbow member, said head being arranged above said outlet in the path of flow of the iuel mixture leaving the outlet.

8. Oil burning apparatus comprising a burner vessel including a pan-shaped bottom section and a hollow frusto-conical top section separably secured to the bottom section, said top section terminating at its upper end in a restricted outlet throat, means for maintaining a pool of liquid oil in the bottom section of said vessel, the side walls of the frusto-conical upper section of said vessel being provided with a group of relatively restricted and spaced primary air-admitting openings, a secondary group of spaced restricted air-admitting openings formed in the side walls of said top section between said primary group of openings and the outlet throat of the burner a casing having an open bottom and a top which terminates immediately contiguous to said outlet throat, the casing being open at its bottom to provide for the passage of air between the outer walls of said vessel and the inner walls of the casing, the top wall of said casing immediately adjacent to said outlet throat being provided with a series of openings adapted for the passage of air from said draft chamber into admixture with the combustible gases or vapors issuing from said throat in an upward direction, a manifolding hood surrounding the primary group of openings formed in the top section of said burner, and means for supplying said hood with air from a source of supply exterior to said casing.

9. Oil burning apparatus comprising a burner vessel having a closed bottom, upwardly extending side walls and an outlet in the top thereof, means for maintaining a pool of liquid fuel in the bottom of said vesselfthe side walls of said vessel above said pool being provided with vertically spaced banks of restricted air-admitting openings, a casing surrounding said burner vessel and spaced therefrom to form an annular chamber, the upper end of said chamber being closed by the top wall of said casing and the lower end being open to the atmosphere, the top wall of said casing being provided with a plurality of restricted openings adjacent the outlet of said burner vessel, a manifold hood enclosing a portion of said burner vessel and a lower bank of openings, means for introducing air from the exterior of said burner directly to said hood to supply air to said burner vessel through the openings enclosed by the hood, and thermostatically controlled means for varying the amount of air supplied to said hood.

10. Oil burning apparatus comprising a burner vessel having a closed bottom, a restricted outlet LAG! at the top, and side walls extending from the bottom to the top, said side walls being formed with vertically spaced banks of restricted air inlet openings, means for maintaining a pool of liquid fuel in the bottom of said burner vessel, a casing surrounding said burner vessel and spaced therefrom to provide an annular chamber, the upper end of said chamber being closed by the top wall of said casing and the lower end being open to the atmosphere, the top wall of said casing being provided adjacent the outlet for the burner vessel with concentric groups of restricted openings, a manifold hood enclosing a portion of said burner vessel and a lower bank of air inlet openings, and means for introducing air from the exterior of said burner directly to said hood to supply air to said burner vessel through openings enclosed by the hood.

11. Oil burning apparatus comprising a combustion vessel having a closed bottom, an annular upwardly extending side wall and an open top, means for maintaining a controlled flow of oil to the bottom of said vessel, the side wall being provided with a plurality of vertically spaced groups of circumferentially spaced openings, a casing having top and side walls surrounding said combustion vessel and spaced therefrom to provide an air chamber, the upper end of said chamber being closed by the top wall of said casing and the lower end being open to the atmosphere, the top wall of said casing being provided with a central opening coinciding with the open top of said combustion vessel and a plurality of reduced openings surrounding said central opening to permit limited air flow from said air chamber, and means connected with the side wall of said combustion vessel for supplying primary air directly from the exterior of said apparatus to the interior of said combustion vessel through a lower group of openings in the side wall thereof.

12. Oil burning apparatus comprising a combustion vessel having a closed bottom, an annular upwardly extending side wall and an open top, means for introducing oil to said vessel through the central portion of the bottom wall, the side wall of said vessel being provided with a plurality of vertically spaced annular rows of air admitting openings, said openings being provided around the oomplete circumference of said combustion vessel, a manifold extending around the lower portion of the side wall of said combustion vessel and separating a lower row of air admitting openings from the upper rows of openings, a casing having side and top walls enclosing said combustion vessel, the walls of said casing being spaced from the walls of said combustion vessel to provide an air chamber having an open bottom, the top wall of said casing having an opening registering with the open top of said combustion vessel, and air conducting means connected with said manifold for supplying air from the exterior of said casing directly to the interior of said combustion vessel throughout the entire circumference thereof through the openings enclosed by said manifold.

MILTON D. HUSTON. JACKSON G. GILMORE.

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