US3352345A

US3352345A - Combustion device construction

Info

Publication number: US3352345A
Application number: US395238A
Authority: US
Inventors: Harmon B Mclendon
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-09-09
Filing date: 1964-09-09
Publication date: 1967-11-14
Anticipated expiration: 1984-11-14

Description

Nov. 14, 1967 H. B. M LENDON 7 3,352,345

COMBUSTION DEVICE CONSTRUCTION Filed Sept. 9, 1964 2 Sheets-Sheet l I INVENTOR HARMON B. McLENDON BY A TTORNE Y5 NOV. 14, 1967 MCLENDQN 3,352,345

COMBUSTION DEVICE CONSTRUCTION Filed Sept. 9, 1964 2 SheetsSheet 2 INVENTOR HARMON B. McLENDON W z wal ow A TTO RNEYS United States Patent Oflice 3,352,345 Patented Nov. 14, 1967 3,352,345 COMBUSTION DEVICE CONSTRUCTION Harmon B. McLendon, Studio City, Calif. (24352 Highlander Road, Canoga Park, Calif. 91304) Filed Sept. 9, 1964, Ser. N 0. 395,238 5 Claims. (Cl. 158-28) This invention relates generally to the construction of combustion devices and components thereof. It more particularly relates to improvements in combustion de vices made of sheet metal or the like wherein combustion takes place principally in the central part of a chamber, the walls being insulated from the flame by a swirling flow of pressurized relatively cool air entering the chamber through a perforate side wall. The combustion unit is housed within a plenum chamber to which air is supplied under pressure, passing inwardly through the side wall perforations. The device includes an outwardly extending upper flange or rim surrounding a throat through which the flame extends outwardly from the combustion chamber.

A preferred embodiment of the invention will be described and illustrated in the form of a vertically oriented device for burning fuel oil, using air as the oxidizing agent,- with the flame extending upwardly from the center of the chamber for providing heat to using apparatus such as a boiler, furnace or other heat exchange means. Thus the flange above mentioned may constitute the upper of the plenum chamber in which the combustion device is housed.

In accordance with the preferred embodiment, there is provided a'unit having concentric upper and lower sections desirably made of thin sheet metal. The lower section includes a downwardly convergent wall which, as seen in section, may be substantially parabolic or, as in the present embodiment, conical. The upper section terminates upwardly in an axially disposed upwardly directed flame outlet mouth, and desirably its perforated side wall includes a frusto-conical portion, downwardly divergent, the perforations therethrough taking the form of louvered slots to direct incoming air generally tangentially or circumferentially inwardly of the inner surface of the side wall.

The lower section wall may terminate downwardly in a centrally disposed sump or reservoir for collecting unburned fuel, and barrier means are provided in the form of a metal disk extending across the sump above the level of fuel collected therein. The periphery of the disk is spaced inwardly from the lower section wall by only a small clearance to define a narrow annular passage between the disk and the wall. Except for small support tabs fixed to the wall, there is no other high heat transmission path between the disk and the wall, and the disk is thus substantially isolated thermally from the wall. As will be later understood, this permits a rapid rise of temperature of the disk during start-up of the combustion unit, and the presence of the relatively hot disk accordingly tends to insure stable combustion over a wide range of fuel-air ratios, as frequently may exist during start-up as well as, under some conditions, during later operation.

The disk serves also to reduce heat flow to the fuel collected in the sump, and the narrow annular passage between the disk and the wall retards vapor flow from the collected fuel, thereby preventing sudden and objectionable flame enlargement and smoke as the parts approach operating temperature. Thus, during the initial start-up period some fuel in liquid form drips down the inner surface of the walls and collects in the sump at the bottom of the chamber. The main flame accordingly burns at considerably less than its eventual normal rate by reason of the loss of fuel to the sump. The initial lowered rate of burning is of itself not objectionable and in fact is desirable, since it permits the combustion unit, as well as apparatus heated thereby, to come up to operating temperatures more gradually than would otherwise be the case. But eventual burning of the fuel in the sump, if uncontrolled, may take place rapidly and cause a greatly enlarged flame as well as much smoke, both highly objectionable. This is prevented by the barrier disk.

The combustion unit in accordance with the present invention includes means for improving the flow of air and of the burning fuel and air mixture through the unit. Thus, in order to minimize blower size for a combustion unit of a given capacity, it is desirable to insure that pressurized air introduced into the chamber through the side wall louvers does not escape from the chamber without entering into the combustion process. Similarly, it is desirable to supply air for the later stages of the combustion process directly to the flame rather than forcing such air through the chamber, and to control any recirculation of combustion gases which tend to re-enter the combustion chamber. Means are provided in accordance with the present invention for accomplishing such control of the flow of air and gases. In the throat constituting the upwardly directed flame opening, an annular lip may be provided extending inwardly from the upper end of the upper section, to form a restricted opening for the exitingflame and acting as a baffle preventing upward passage of air from the chamber. Furthermore, the flange or rim extending outwardly around the upper end of the combustion chamber may be provided with a plu rality of spaced holes immediately outwardly of the upper edge of the upper section, and air is thereby supplied directly from the plenum chamber to the portion of the upwardly moving flame external of the exit throat.

Outwardly of the holes, there may be provided a baflie in the form of an upstanding annular collar extending upwardly from and fixed to the rim and serving to prevent combustion gases from being drawn toward the throat and into the combustion chamber. The collar also tends to enlarge the cross-section of the exiting enabling better mixture of the air passing through the holes.

Flow of air and fuel, and of the resulting flame and combustion gases, through the unit is further enhanced by the mounting of the electrode and nozzle assembly in the side wall of the unit in accordance with the invention. It is necessary that the fuel-injecting nozzle and the ignition electrodes be positioned properly for optimum performance of the unit, and that they be accurately replaced after removal for repair or maintenance. The present assembly accurately positions the electrodes and nozzle rel ative to one another and relative to the combusion unit proper. In its mounting in the wall of the combustion unit, the nozzle is maintained at a comparatively low temperature by incoming cool air passing around the nozzle, and the nozzle is substantially shielded from radiant heat from the flame. The electrodes are mounted in tubular insulating sleeves and are spaced coaxially within the sleeves, providing an exceptionally long surface path and minimizing the possibility of short circuiting or grounding in spite of'deposits of coked material and the like on the insulator surfaces after prolonged use. Possible fouling of the insulator surfaces is further avoided by locating the electrodes relative to the nozzle such that the are between the electrodes during ignition bends or curves downstream to the region adjacent the nozzle.

Accordingly it is a principal object of this invention to disclose novel improvements in combustion devices and components thereof. Other objects and purposes are to provide, in a combustion unit wherein air enters and swirls in vortex fashion, means for retarding combustion of liquid fuel collected during and prior to start-up of the unit; to provide baflle means for insuring that air forced under pressure to enter the chamber will be mixed with fuel for burning, and will not escape unburned; to provide air passage means bypassing the combustion chamber for supplying air to the flame exiting from the chamber; to provide in such a unit means for preventing reverse flow of combustion gases back into the combustion unit; to disclose an improved nozzle and electrode assembly to insure proper combustion in such a unit; and for other and additional objects and purposes as will be understood from a study of the following description of a preferred embodiment of the invention taken in connection with the accompanying drawings in which:

FIG. 1 is a side elevational view of a typical installation embodying the present invention, the plenum chamber being shown in section.

FIG. 2 is vertical sectional view of the combustion device proper.

FIGS. 3 and 4 are views taken on lines 3-3, 44, respectively of FIG. 2.

FIG. 5 is a view taken on lines 55 of FIG. 2 sho-w' ing thevnozzle and electrode assembly in its operative position in the mounting bracket.

FIG. 6 is a view similar to FIG. 5 except that the nozzle and electrode assembly is shown withdrawn from the mounting bracket and the front'portion of an electrode insulating sleeve is shown in section.

FIG. 7 is a fragmentary view takenon line 7-7 of FIG. 2.

FIG. 8 is a view taken on line 88 of FIG. 7.

FIG. 9 is a vertical section view of the combustion device including a diagrammatic representation of the flow path of air and burning fuel therethrough.

Referring in detail to the drawings, and firstto FIGS. 1 and 2 thereof, there is indicated generally at 10 a combustion device embodyingthe present invention, including a perforate upper section indicated generally at 12 and a lower section indicated generally at 14..Both of the sections are desirably made of sheet metal, and are joined together at their common major diameter by suitable means, such as by welding of their juxtaposed outwardly extending

attachment flanges

16 and 18 respectively.

The upper section 12 includes a downwardly divergent side wall 20 having a smoothly concaved inner surface, preferably frusto-conical in shape, the side wall 20 being fixed at its upper end to a mounting rim indicated generally at 22 by suitable means such as an outwardly turned annular lip 24 welded to the lower face of the rim 22. The mounting rim itself is desirably frusto-conical in shape as shown, upwardly divergent, terminating outwardly in an annular flat attachment portion 28. The latter may be fastened by suitable means 29 to a support mounting lip 30 extending inwardly from the cylindrical side wall 32 of a structural member indicated generally at 34, constituting the lower portion of the apparatus to be heated by the combustion device.

The combustion device .10 is mounted in a plenum,

chamber indicated generally at 40 including a flat base 41 and a preferably cylindrical side wall 42 having an open ing 44 formed therein for receiving pressurized air through conduit 46 from blower means indicated generally at 48. A removable access plate 47 may be provided in conduit 46.

Pressurized air thus existing within plenum chamber 40 is introduced into the upper section 12 of the combustion device 10 through a plurality of openings 50 formed in the side wall 20 of the upper section. The openings 50 are desirably in the form of elongated slots or louvers so formed that air entering therethrough is deflected tangentially adjacent the inner surface of the wall 20. The centrifugal force of the rotating air mass thus produced, in view of the downwardly divergent configuration of side wall 20, causes the entering air to move generally downwardly in its swirling path toward lower closed end of the combustion unit formed by the lower section 14. In the present embodiment of the invention, the latter section includes an imperforateside wall 56 which may be frusto-conical in shape and is downwardly convergent,v

terminating downwardly in a central sump or reservoir 58 r in the bottom portion 60 which may be enlarged by being downwardly deformed as shown.

Under some conditions in the operation of a combustion device of the present character, a quantity of liquid fuel may collect at the bottom of the lower portion 14 of thedevice. This may occur, for example, as a result of after-drip from the fuel-supplying nozzle after the fuel supply thereto, is shut off. Liquid fuel may also collect in the bottom of the lower section during initial start-up by reason of incomplete entrainment of liquid fuel in the swirling mass of air in the burner. The collection of, such liquid fuel in the bottom, if directly exposed to the main flame, is disadvantageous in that it will suddenly become ignited as the main flame rapidly heats it through its vaporization range, causing substantial enlargement of the main flame exiting from'the combustion chamber, as well as causing smoke, both of which effects are objectionable. In order to prevent this, there may be provided flame retarding or barrier means defining a restricted passageway for fluid flow between the sump and the upper portions of the device and thereby insuring that the liquid fuel in the sump is permitted to vaporize only relatively slowly.

In the present embodiment of the invention, and with particular reference to FIGS. 7 and 8, such barrier means may comprise a barrier disk indicated generally at 64 extending across the bottom 60 of the lower section 14 and spaced well above the uppermost level of liquid fuel which may collect in sump 58. The disk 64 is held in place by suitable means such as attachment tabs 66, preferably formed integrally with the disk, the tabs being fixed as by welding to the inner surface of the lower section wall 56.The periphery of disk 64 is spaced only slightly inwardly out of contact with the inner surface of wall 56, whereby to provide a narrow passageway 68 therebetween. Such passageway, permits liquid fuel to move downwardly past barrier disk 64 into sump 58, but the passageway restricts upward movement of vaporized fuel so that such fuel, slowly added to the burn ing mixture thereabove, does not change the design conditions of the burner to any objectionable degree. Disk 64 is desirably slightly convex upwardly as shown, both to prevent any collection of fuel on its upper surface and to minimize possible warpage or other deformation during operation.

Disk 64 is advantageous also in that it stabilizes combustion by reason of its being hotter'than adjacent portions of wall 56, both during start-up and subsequent operation. Thus the disk receives heat from the flame by radiation and also through the relatively thin layer of air between it and the flame, and heat so received is not easily transmitted elsewhere since the disk is comparatively isolated thermally from adjacent parts of the device.

The flow of air, flame and combustion gases through and out of the combustion device will be best understood by reference to the diagrammatic showing of FIG. 9. As there appears, air 70 entering through louvers 50 swirls downwardly as indicated by the arrowed path 72 and mixes with ignited fuel from the electrode and nozzle assembly indicated generally at 90, described in detail hereinafter. Combustion of the fuel-air mixture is spaced inwardly from walls 20 and. 56 by a swirling layer of unburned air, and continued downward swirlingmovement of the burning gases in the lower section 14 forces such gases into successively decreasing radii at 74. Since the bottom of the lower section 14 is closed, the swirling flame then commences to move upwardly centrally of the combustion device as indicated by the arrowed path 76..

In order to insure optimum performance and maximum utilization of pressurized air supplied through the louvered slots 50, it is desirable to prevent any such air from escaping unburned upwardly through the flame outlet mouth at the upper end of the upper section 12. There accordingly may be provided baffle means including an inwardly extending annular lip 80 having a central opening 82 constituting the flame outlet mouth of the combustion chamber. Lip 80 is desirably an inward extension of the mounting flange or rim 22 previously described.

Means are provided to supply additional air to the upwardly moving flame exiting through flame outlet mouth 82, in order to support the continued and thorough burning of the fuel therein. Thus, immediately outwardly of the upper end of the side wall 20, there may be provided one or more ports 84 through lip 24 and rim 22, preferably circumferentially spaced therearound, for communicating pressurized air within plenum chamber 40 directly to the exiting flame. The improved results of pressurized air thus fed to the exiting flame may be further enhanced by the provision of an annular collar indicated generally at 86 fixed as by welding to the upper surface of the mounting rim 22, the collar extending upwardly outwardly of ports 84. Collar 86 serves an additional purpose in that it controls, and preferably eliminates, any tendency for burned combustion gases to return downwardly along the upper surface of mounting rim 22 toward the flame exiting through mouth 82.

Fuel supply and ignition is desirably provided by the assembly indicated generally at 90, best seen in FIGS. 3, 4 and in its operative position, and shown removed in FIG. 6. The assembly 90 is located well above the bottom of the chamber. The assembly 90 includes a nozzle 92 having an axial orifice 94, the nozzle being mounted at the outer end of a cylindrical tube 96 which is in turn connected by an integral fitting 98 to a supply hose 100. Tube 96 is slidably received in a cylindrical mounting bracket indicated generally at 102 which is fixed to the wall 20 by support arms 104.

A holder indicated generally at 110 is mounted on the rear portion of tube 96 and includes an enlarged portion 112 for receiving a pair of insulating

sleeves

114 and 116 and maintaining the sleeves in a predetermined relation relative to one another and relative to nozzle tube 96. Each

sleeve

114, 116 supports a stiff wire rod spaced coaxially therein, the rod 118 in sleeve 116 being seen in FIG. 6, and the rods terminate in

electrode tips

120 and 122, positioned inwardly of wall 20.

Rod 118 is held in position within insulator sleeve 116 by an insulating bushing 124, and the rods extend rearwardly to

terminals

126 and 128 connected to high voltage leads 127 and 129 respectively. The

insulator sleeves

114 and 116 extend through

openings

115 and 117 respectively formed in wall 20.

When the assembly 90 is in its operative position as seen in FIG. 5, with holder 110 in abutting relation with the outer end of bracket 102, nozzle 92 and its orifice 94 are in alignment with a small port 130 formed in wall 20, the nozzle being spaced slightly outwardly of the wall. The forward edge 132 of bracket 102 is also spaced outwardly from wall 20, and incoming air accordingly passes across the face of nozzle 92 into port 1330, thereby cooling the nozzle. It is further to be noted that the nozzle is substantially shielded from the radiant heat of the flame within the burner by reason of the small size of port 130, and the face of the nozzle itself is slightly outwardly of the wall 20. This arrangement is found to result in unusually cool, and hence beneficial, operation of the nozzle by minimizing clogging of its orifice and internal passage leading thereto.

As best seen in FIGS. 2 and 3, an opening indicated generally at 140 is provided in wall 20 directly beneath the tip of nozzle 92, the opening being desirably in the form of a louvered slot as shown, and the outwardly G projecting lip 142 thereof serves to catch any oil which may drip from nozzle 92. Lip 142 leads such oil into the combustion chamber, whereby the oil may collect in sump 58, thereby preventing the objectionable smoking which would result if the oil were permitted to drip onto the outer wall of the device.

In FIG. 5 arrow 150 indicates the direction of swirling movement of air entering the present device, and it will be noted that the electrode tips and 122 (the latter being aligned behind tip 120 in FIG. 5) are effectively upstream of nozzle 92. Thus the electrodes and their

insulator sleeves

114 and 116 are exposed to incoming air, and deposit thereon of material resulting from combustion is minimized. The efiiect of any such deposit is further minimized by the long electrical path along the inner cylindrical surface 156 of sleeve 1'16, and reduction of surface resistance and possible short circuiting resulting therefrom is virtually eliminated. It will be understood that when high voltage power is applied between

tips

120 and 122, the spark thus formed is carried downstream by the air moving in the direction of arrow to ignite the fuel entering the chamber from nozzle 92.

Modifications and changes from the illustrative form of the invention above described and illustrated may be made without departing from the spirit of the invention, and such modifications and changes are intended to be embraced within the scope of the following claims.

I claim:

1. A combustion apparatus comprising:

means forming an upwardly open combustion chamber including a closed lower end and a concave side wall provided with openings formed therein spaced from said closed lower end for admitting air into the chamber, said openings being provided with guide means for forming an air layer swirling downwardly generally circumferentially adjacent said side wall, said side wall having fuel receiving and electrode receiving ports formed therein between said lower end and the uppermost of said openings;

a fuel supply and ignition assembly including an igniter element in said air layer; and a fuel introducing means having an opening aligned with the fuel receiving port in the side wall, said igniter element being located circumferentially upstream relative to said air layer of the fuel receiving port;

and means for supplying pressurized air to said openings and ports.

2. The invention as stated in claim 1 including a bracket fixed to the side wall and projecting outwardly therefrom for removably retaining said assembly in its defined operative position, said bracket including a sleeve portion and said assembly including a member having a cylindrical surface slidably received in the bracket sleeve.

3. The invention as stated in claim 2 wherein said cylindrical surfaced member is coaxially aligned with said fuel introducing means and said sleeve is spaced outwardly of the chamber wall whereby the fuel introducing means is in the path of air entering the fuel receiving port.

4. A burner structure comprising: an open ended vessel having a side wall of circular cross-section, a closed end wall opposite the open end thereof, and means defining a flame throat in said vessel near the open end thereof; a housing spaced about said vessel and substantially concealing outer surfaces thereof from the atmosphere; fuel injector-igniter means passing into said housing and said vessel for injecting fuel into said vessel and igniting the same; and means for pumping air under pressure into said housing; wherein inlet openings are formed in said vessel including guide means therefor extending outwardly from and positioned on said side wall exteriorly to said vessel and tangentially to said side wall, said guide means being so directed and said openings being so located as to introduce said air tangentially towards said end wall at a re- 7 gion spaced from both said throat and said end wall; and further wherein said vessel is adapted to be positioned with the end wall. lying under the open mouth, is constructed with said end wall forming a sump portion and includes a baffle means overlying the sump portion and, defining therewith a restricted fluid flow path between said sump and the body of the vessel.

5. A burner structure comprising: an open ended vessel having a side wall of circular cross-section, a closed end wall opposite the open end thereof, and means defining a flame throat in said vessel near the open end thereof; a housing spaced about said vessel and substantially concealing outer surfaces thereof from the atmosphere; fuel injector-igniter means passing into said housing and said vessel for injecting fuel into said vessel and igniting the same; and means for pumping air under pressure into said housing; wherein inlet openings are formed in said vessel including guide means therefor extending outwardly from and positioned on said side wall exteriorly to said vessel and tangentially to said side wall, said guide means being so directed and said openings being so located as to intro- References Cited UNITED STATES PATENTS 1,747,798 2/1930 Scrimgeour 158-28 2,295,799 9/1942 Focke et a1 158-9l 2,420,598 5/1947 Jackson 15828 2,506,138 5/1950 Clark 158--9l 2,581,238 1/1952 Cauley 158-91 2,680,478 6/1954 Schultz et al. 158--91 3,200,870 8/1965 Hanley et a1. 15891 X 20 JAMES w. WESTHAVER, Primary Examiner.

FREDERICK KETTERER, Examiner.

Claims

1. A COMBUSTION APPARATUS COMPRISING: MEANS FORMING AN UPWARDLY OPEN COMBUSTION CHAMBER INCLUDING A CLOSED LOWER END AND A CONCAVE SIDE WALL PROVIDED WITH OPENINGS FORMED THEREIN SPACED FROM SAID CLOSED LOWER END FOR ADMITTING AIR INTO THE CHAMBER, SAID OPENINGS BEING PROVIDED WITH GUIDED MEANS FOR FORMING AN AIR LAYER SWIRLING DOWNWARDLY GENERALLY CIRCUMFERENTIALLY ADJACENT SAID SIDE WALL, SAID SIDE WALL HAVING FUEL RECEIVING AND ELECTRODE RECEIVING PORTS FORMED THEREIN BETWEEN SAID LOWER END AND THE UPPERMOST OF SAID OPENINGS; A FUEL SUPPLYING AND IGNITION ASSEMBLY INCLUDING AN IGNITER ELEMENT IN SAID AIR LAYER; AND A FUEL INTRODUCING MEANS HAVING AN OPENING ALIGNED WITH THE FUEL RECEIVING PORT IN THE SIDE WALL, SAID IGNITER ELEMENT BEING LOCATED CIRCUMFERENTIALLY UPSTREAM RELATIVE TO SAID AIR LAYER OF THE FUEL RECEIVING PORT; AND MEANS FOR SUPPLYING PRESSURIZED AIR TO SAID OPENINGS AND PORTS.