US2363098A - Burner for fuels containing tetraethyl lead - Google Patents

Description

B. w. 'ruLLls Nov. 2l 1944.

BURNER FOR FUELS CONTAINING TETRAETHYL LEAD Filed Jan. 12, 1942 2 Sheets-Shes?l l INVENTOR Boyd W. Tull/Ls.

Nov. v21, 1944. Q w, TULLls 2,363,098 BURNER EOE FUELS `CONTAININE TETRAETHYL LEAD Filed Jan. 12. 1942 2 Sheets-Sheet 2 79 INVENTOR Boyd W 72H/As. BY

ATTORNEY Patented Nov. Z1, 1944 BURNER FOR FUELS CONTAINING TETRAETHYL LEAD Boyd W. Tullis, Wichita, Kans., assignor to The Coleman Lamp and Stove Company, Wichita, Kans., a corporation of Kansas Application January 12', 1942, nserial No. 42u20 9 claims. (ci. 15s-c1) 'Ihis invention relates to liquid fuel burning appliances and particularly those for burning low l boiling point' petroleum hydrocarbons such as straight run gasolines and naptha. However, fuels'of this type are not always conveniently obtainable and in many localities are not available when needed. Consequently attempts have Y been made to use present day automotive or motor fuels as they are always convenient to obtain even at the most remote outpost of civilization, but fuels of this character have not functioned in such appliances for the reason that they contain considerable solid material such as hydrocarbon gums and coloring materials, as well as antiknock compounds, ,for example tetraethyl lead. When' these materials pass through the extremely hot zone pf the generating devices of such appliances they clog the generators within a very few hours burning time. 'I'his is attrib uted to carbonizingof the gums and decomposition of the tetraethyl lead within the generator by reason of thel intense heat required to effect complete vaporizatlon of the fuel before itis supplied to the burners of the appliances.

It is, therefore, the Vpurpose of the present invention to provide a burner structure and arl rangement thereof which operates satisfactorily using automotive fuels containing tetraethyl lead and other extraneous materials which ordinarily cause clogging of conventional equipment.

Another object of the invention is to provide a simple and inexpensive burner structure for a great variety of andheatlng appliances and which is particularly adapted for military use and for general utility use by motorists.

hunters, Sportsmen andv exploration partiesfbecause asuitable fuel for the burner is always near at hand, namely the 'fuel tank of their motor vehicle, aircraft, motor boat, or the like.

Further objects of the invention are to incorporate with the burnerfeaturespermitting use of motor fuels. instant lighting by air vatomization of the fuel, 'a' shield for limiting external cooling effects upon the bowl of the burner, and e. mechanism for cleaning the discharge orince of the vaporizer. v l y In carrying out my invention, VI und that automotive fuels and the like-may be used success- 'soient readily combustible vapor to maintain combustion of the'higher boiling point fractions and the tetraethyl lead through contact thereof with the flames resulting from the evolved vapors. 'The burning fuels are then vcaused to impinge upon surfaces approaching incandescence and spread thereby into contact with sufficient air to assure complete combustion.

In accomplishing these results', I have p-rovided improved burner structure,l illustrated in the accompanying drawingsuwherein:

Fig. 1 is a vertical sectionI through a stove equipped with afuel supply and burner appa# ratus constructed in accordance with'the present invention.

Fig. 2 is an enlarged vertical `section through the burner, vaporlzer and control valve on lthe line 2--2 of F13. 1.

Fig. 3 *is a cross-section through the vaporizer cn the line 3-3 of Fig. 2. v

Fig. 4 is a cross-section through the ducting connection between the burner bowl and -wall of the vaporizer.

Fig. 5 is a detail perspective view l'of the burner. Referring more indetail to the drawings: -l designates a stove equippedl with a burner and` fuel supplymeans embodying the featurescf the present invention. It is to be understood, however. that the invention is adaptable to any heating or cooking appliance which is to be operated witha hydrocarbon type fuel. The stove illustrated in conjunction with my improved burner is one of generalutility type, character' ized by its ease of transportation and is, therefore, oneA to which\the burner -l is especiallyadapted.

The specific structure of the s tove is illustrated and described in detail in an application on Porcameswve. med January 12, 1942, serial No.

426,421, and other than the burner' and fuel supply means and control mechanisms, constitutes no part of the present invention.

fully by initially vaporlzing l.4 part of the4 fuel,

that is by vaporizing the low boiling point fractions within a vaporizer and discharging the liquidtetraethyl lead and higher point "fracf,

tions lwhich ,contain the gumslfrom the vapor-.- izer in liquid or atomired state. The low boiling Vpoint fractions, or those vapor-ized, `provide suf- `".lihe stove includes a tank 42 for containing fuel to be supplied tothe burner 3 which may be an ordinary motor fuel, forv example a gaso line blended to have a high octane value and containing an antiknock compound such las tetraethyl lead. The fuel is admitted to the tank 2 through a filler neck l ordinarily closed by a pressure-tight cap 5. Connected with the tank is a fuel control valve B carrying a vaporizer tube l, which ln, turn supportsrthe burner 3. Carried by the tank on an annular bead l is a spider lll having an opening Il registering with a threaded bore l2 in a bushing Il, the'bushing I3 being heat coni I sealed within an opening i4. Carried by the arms of the spider are posts i extending upwardly alongside of the burner and carrying a grid i3 for supporting a cooking vessel over the flame of the burner 3.

The valve 6 includes a body i1 having an externally threaded leg I3 projected .through they opening in the spider and* threaded into the bushing i3 whereby the valve is supported in rigid position on the tank and the spider is anchored in position on the bead 9 by a jam-nut I3 threaded on the leg and bearing against the upper surface of the spider, as best shown in Fig. 1. Formed in the leg I8 of the valve body is a bore 23, having a threaded portion 2| in whiclrithe threaded neck 22 of a nipple 23 is threaded. The nipple 23 carries an outer tube 24 which depends into the fuelcontained in the -tank and carries a cap 25 on the lower end thereof having an inlet orice 325 located in close proximity to the bottom of the tank. Also carried by-I the nipple 23 is an inner tube 21 of smaller size than the outer tube to form` an .annular passageway 28 therebetween which communicates at its upper end with the air space 23` above thelevel of the liquid in the tank through openings 30 so that under certain ditions air is discharged into chamber-3io! the cap 25 to effect atomizationof fuel admitted through the orifice 26. The mpple 23 has an upperbore 32 connecting with the upper end of the inner tube through which fuel is discharged into the bore 20 and from the bore 20 into a chamber 33 in the valve body. The chamber 33 aligns with-a lateral arm 34 of the valvebody having a threaded axial bore 35' and a packing containing chamber 3B. 'v

Formed in the valve' body coaxially with the bores of the arm A34 is a port 31 having connection with an axial bore 38 opening downwardly within an axial arm 33 of the valve body through an angularly arranged port 40. Rotatably mounted within the bores of the arm 34 is a valve stem 4i having a threaded portion 42 engaging' the internal threads ofthe bore 35 and having a conical end 43 arranged so that the point thereof enters the port 31 for shutting offor throttling ilow of fuel to the upper bore 36 of the valve body. The outer end of the valve stem projects from the arm 34 of the valve body 'and carries a knob 44 whereby the valve may be rotated to move the conical end 43 thereof to and from Athe portv 31.

Contained within the bore 36 and seated against an internal shoulder 45 thereinis a packing 46 retained in sealing relation with the valve stem by a packingnut 41 threaded upon the arm 34 of the valve body. The conical end of lthe valve is spaced from the threaded portion' 42 by a cylindrical portion 46 which, when the valve is closed or slightly'opened, extends across the bore 20 to eilfect depression of a throttling-rod 43, the throttling rod having a head 50 freely mounted in the bore 23 and provided withan annularcollar 5I for seating one end of'a coil spring 52 having its opposite end seating against the nipple 23 for retaining a stem53, on the headof the throttling rod in contact with the `valve stem. The throttling rod also includes a wire 54 `extending downwardly through the bore of the `nipple, through the inner tube, and through the inlet orifice 23 whereby the effective area of the orice is limited so that fuel passing therethrough is caused to move at sumcient velocity in proportion to a stream of air being discharged into the chamber 30 by way of the passage 2 3, producing 7s an atomized fuel mixture, which mixture is dis-l charged through the atomlzer to the burner to start operation of the burner, as later described. After starting'operation, the valve is opened so' the stem 53 rides against the conical end of the valve stem responsive to action of the spring 52 which lifts the throttling rod out of the inlet Vorifice 26 to allow full iiow of fuel therethrough to supply the. full demand ofthe burner and forms a liquid seal to prevent further flow of air downward through tube 24.v

The upper portion of the axial arm 33 is externally threaded, as at 55. and is provided with a bevellediedge 56 for seating a flared ange 51 on the base of the vaporizer tube 1. The vaporizer tube includes a cylindrical wall portion 53 forming .an internal vaporizing chamber- 53. The wall portion 60 oi' the vaporizer above the cham- Aber 53 is substantially thicker than the lower portion so asto better retain the amount of `heat necessary in maintaining a selected temperature for .controlling vapcrization of a selected portion oi' the fuel passing into the vaporizer so that other portions,

the vvaporizer to. clog-, are discharged as an matomized liquid, as later described. The thickened wall portion of the vaporizer tube is internally threaded, as indicated at 6I, mounting the threaded neck 32 of a nozzle tip 63 having `a relatively small discharge or burner feeding orifice 54 opening into a counterbore 65 which allows thefuel discharged from the nozzle to spread within the bowl 36 of the burner 3. The nozzle tip has. an annular shoulder 61 so that when it is threaded into the thickened end of the vaporizer tube the shoulder seats tightly against the tube to `provide a tight joint.

The burner bowl 66 includes a relatively thick collar or base portion 63 formed of heat oo nductive material Aand having an axially threaded bore 63 engaging the external threadson the thickened portion of the tube to connection therebetween and a ready path fo the heat conducted from the burner bowl tothe vaporizer tube. Attention is here directed to the fact that the amount of conductive metal, and

' extent of the thread connection, are accurately determined, as these factors govern the temperature at which the. vaporizing tube operates, which in turn determines the temperature of s the liquid fuel being partially vaporized. This fuel temperature is maintained below the vaporizing temperature of the liquid tetraethyl lead or non-hydrocarbon compounds which pass throughthe nozzle tip 33 and orifice 34 in liquid form together with the vapbrized portion of the fuel. Only gasolines or light napthas whose' compositionp'rovides ample fractions of low temperature volatility will thus operate, therefore, this invention is directed to such fuels. So also. any device which has its vaporizer operating at tem-- peratures sufnciently high to `completelyvaporiite kerosene,- naptha or gasoline.. vwill not accomf plish the` purpose of my invention since the lead in solidl form will be deposited within the -va-l porizer, quickly clogging same.

For example, since the boiling point oi' tetraethyl lead is approximately 400 F. and 450? F. under pressure at which the fuel in my stove isusually subjected during vided a structure which coordinates the elements ofconductivity and radiation to maintain during operation a temperature ofthe fuel being partially vaporlzed at a point which willkvaporiae,

that is those normally causing provide a close operation, 1 have prol within 'the vaporizing member that major portion of thefuel possessing low temperature volatility which vapor acting under pressure causes tangular cross-section guidingly supported in the bore 38 of the valve body and has a stem 80 projecting'throughthe vaporizer chamber into au enlarged bore 80 of the nozzle tip which receives a needle 8| of sufllcient diameter to be project-` y able through the orillce 84. 'I'he clean-@out device the extent of contact of bowl to the vaporizing tube, and the conductivity of the vaporizing tube itself are all coordinated with the factor of radiation to maintain the required temperature of the fuel being vaporized es above set forth. The lperiphery of the collar 88 has an annular shoulder encircling a flange 1| encircling the threaded bore 89 thereof in spaced relation with the nozzle tip. The burner bowl has an upwardly and outwardly curved lower portion 12 of substantially semispherical shape, an outwardly. flaring upper portion 13, and an intermediate corrugated belt portion 14. The inner surface of the flaring portion 13 is contacted by flames resulting from ignitionof the fuel and impinging against 4a defiector plate 15.

The deflector 15 includes a substantially concavoeconvex member of smaller diameter than -the flange portion of the bowl so that the periphery` thereof cooperates with the flare ofthe bowl in forming an annular flue-like passageway for the deflected flames and to effect draft of cornbustion supporting air into the burner bowl through air inlet openings 18 in the semispherical portion thereof, the .member 15 being turned so thatthe convex side faces the burner and forms an upwardly and outwardly deflecting surface which. becomes heated intensely. The llame dellector is supported in position by means of radially extendingarms 11 projecting from the periphery thereof and extending through slots 18 in the burner bowl. Cooperating with the semispherical portion of the burner bowl and encircling the flange 1| is an inner bowl 19 closely contacting the burner bowl and having openings 80 therein registering with the air inlet openings 18; The rim of the inner member has corrugations 82. corresponding to the corrugations 1.4 previously described.

In order to control movement of combustion supporting air, limit external cooling effects on the burner bowl, and prevent drafts from interfering with operationtof'theflame, the portion-of is operated by a rock shaft 82 rotatably suppbrted in a laterally extending arm 83 o f the valve body. The .shaft extends through a packing 84 `con-- tained in a shouldered bore 88 of the arm and which is pressed in sealing contact with the rock shaft by a packing gland 98. The inner end of the rockslaft has a crank arm 31 having a pin portion 88 engaged in a transverse groove 88 formed in the head 88 of the clean-out device so that when the shaft is rotated the needle 9| is moved through the outlet orifice 8l to clear it of any matter that may be lodged therein. The end in Fig. 1f.

of the rock shaft projecting outwardly from the packing gland is bent laterally to provide a handle |00 by which it is readily oscillated.

Air pressure is supplied to the fuel tank through the Acontrol valve when the valve is open and to effect atomization when starting the burner. The air is'supplied by means of a pump r|0| carried by the top 'of the tank and havinga barrel portion projecting thereinto. The pressure outlet of the pump has connection with the air space above the fuel through a duct |02 as shown Contained in the pump barrel is a plunger (not shown) whichA is actuated by a plunger rod |03 carrying an actuating knob |04.

In operating the burner'constructed and assembled as described, a. fuel, for example an ordinary automotive gasoline, is poured into the tank through the filler neck I up to the outlet end thereof, which leaves the'air space 29 in the I top of the tank. The control valve 8 is closed and thevplunger rod |03 of the pump |0| is actuatedto build up pressure within the tank to force shaft 92 with the handle |00 to raise and lower the needle 0| through the orifice 84 of the nozzle tip. The control valve is then opened slightly, whereupon liquid "in the tank is discharged through the inlet orifice 28, which, .because of the throttle rod 49, is a relativelysmall quantity, to produce a readily ignited Vmixture with the air passing from the tank downwardly through the n vannular space 28 between the tubes 2l and 21.

The mixture 'is discharged upwardly through the valve body and vaporizer tube at suillciently high velocity and pressure to be discharged vfrom the nozzle tip in-a une mist, which is readily ignited to start the burner. The resultant flame plays against the deector and is directed outwardly upon the inner surface of the flaring portion of the burner bowl to heat the metal thereof and cause anupdraft of'air from the lower end of the tubular shield 83 through the open;

ings 18 and 80, into the burner bowl, and through Y in close relation with the vaporizer tube to coo operate with the heat conductive capacities thereof in maintaining `lthe desired predetermineduniform temperature ofthe vaporizer walls. r

In 'order to vassist in vaporization of the fuel,

` the vaporizing chamber has a plurality of layers umm external comme eaeets on the bowl The the passage 84 formed between the deflector 18 and flaring portion of thebowl. It will be ntedthat the portionfof the-shield .which enclrcles the flame contacting portion ofthe burner bowl.

heat is conducted downwardly through the semispherien portion ofthe .bowl te tne'eene u thereof and through' the threaded connection into. the thickened wallportion 88 ofthe vaporlzer tube, the rate of heat conduction being controlled, as above stated, by the extent of engage-Q mentor the collar with the vaporlzer tube and" in me name 4 Y i thethi'ckness ofthe metal of the burner bowl so that the heat is ut ilized to cause vaporization of the lower boiling point fractions ofthe fuel mixture passingthrough the vaporizing chamber. As -soon as gas begins to,..discharge into the burner delivered from the tank -into'the vaporizer tube.

' I iind that ordinary leadedmotor or automotive fuels may be lpreheated to approximately 400 F. fand `under some-conditionsmay befraised to 450 iitviiiliiiit sppreciablelistillationfof the heavier fractions which contain .the objectionable gums A asaaoss l i be heated .syfepmbusaawnmn the vbnrnerbowi and having a limited'portion in variable heat `v conductive contact with said thick-wall portion of'l the' vaporizer for conducting an amount of heat necessary to maintain the fuel within the vaporizer at a vanorizing temperaturev below the decomposing point of said compound so that the compound 'is discharged into the burner bowl without being decomposed in the vaporizer, a

and lead. The tetraethyl lead content ,becomes f volatile at these cqmparativ low temperatures and does not begin to separate and'fon'n solid depositsuntil the ltemperature reaches 400 F.

, and under operating pressure might rise to450' Vvthrough the orifice of said nozzle tip.

clean-out needle supported in the vaporizer, and means for selectively lprojecting the needle 2. An apparatus for burning liquid hydrocarbon fuel containing acompound which produces objectionable deposits when'saidi compound is heated to decomposing tempeature.- including a burner for burning said fuel 'nd having an air inlet to supply combustion supporting air ,into

the burner, a vaporizer vhaving an externally threaded end, a fuel discharge nozzle projecting from said end of the vaporizer to discharge fuel F. Therefore, since the burner structure is delsigned to maintain a vaporizer temperature between 400 and 450 F. it is not hot enough to effect vaporlzatiorr of the higher boiling point fractions -of the fuel or break down ofthe tetra- .ethyl lead compound, consequently these parts are dischargedfrom the vaporizer in the form of atcmized liquid into burning vapor resulting from the Vaporized lower boiling point fractions. It is thusv obvious that the portions of the fuel ordinarily tending to clog the burner cannot break down until they have reached the hotter zone in the burner bowl where they are readily consumed nd substantially complete combustion is effected. The flame playing against the deflector soon brings the metal to an intense heat.

It is obvious that the partially vaporized fuel is delivered upon the superheated deector plate with considerable force and at atmospheric pressure, which assures complete vaporization and causes dissipation of any solid particles thatv might be formed in the burner bowl.

The deected'ame playing upon the viared lwall of the burner bowl supplies heat to the vaporizer almost entirely through conduction and since the movement of combustion supporting air through the burner is substantially constant, the temperature 'of the vaporizer is kept approximately uniform and cannot reach the point where the objectionable elements are deposited in lthe vaporizing chamber and-clog the oriilce of the needle tip. Should any objectionable matter be deposited it is so light and lnilnitesimal that the orice of the nozzle -tipis readily cleared into the burner, means for supplying said lfuel to the vaporizer for discharge into the burner, and

a collar having heat conductive connection with the burner to conduct heat of combustion within the burner and having c threads engaging the threaded end of the` vaporizer toh conduct said heat to the vaporizer, said collar being adjustable to vary the extent of engagement of the threads so that heat may be conducted in an amount substantially proportional to the extent of engagement of said threads for maintaining the fuel within the vaporizer at a Vaporizing temperature below the decomposing pointl of said compound so that the compound is discharged into the burner without being decomposed With- I inthe vaporizer.

3. An apparatus for burning liquid hydrocarbon fuel containing a portion which produces. objectionable depositsl when heated to decomposing temperature, including an open 'top burner bowl for burning said fuel and having an air inlet to supply combustion supporting air into the burner bowl for maintaining combustion of fuel within the burner bowl, a vaporizer having an outlet discharging into the burner bowl, means l for supplying the liquid hydrocarbon fuel to the vaporizer under pressure, fuel atoinizing means thereof by the cleaning needle. Therefore the vaporizer will operate overa long period of time without repair or replacement even'though automotive fuels are used in the stove.

What I claim and desire to secure by Letters Patent is:

Al. An'apparatus for burning liquid hydrocarbon fuel containing a compound which produces objectionable deposits when said compound is heated to decomposing temperature, including a lburner bowl for burning said fuel and having an air inlet to supply combustion supporting air into the burner bowl; a vaporizer having a nozzle tip provided with a fuel outlet orice arranged to discharge into the burner bowl, means for supplying said fuel to the vaporizer, said vaporizer having a thick wall portion surrounding the nozzle tip and spaced from the outlet orifice, heat conducting means having a portion in position to cooperating with the fuel supply means for initially delivering'air with the fuel for atomizing said fuel discharged into the burner bowl during starting operation to initially heat the burner bowl, and a heat conductive connection between the burner bowl and .said vaporizer to conduct a predetermined amount ofl heat from the burner bowl to the vaporizer for heating the fuel within the vaporizer to a temperature below the decomposing point of said objectionable portion of the fuel and sumcient to vaporize portions of the fuel having a lower distillation point whereby the objectionable y portion is discharged from. the vaporizer into the burner bowl in substantially liquid form and said other portions in vapor form for continuing operation of said apparatus.

,'4. An apparatus for burning liquid hydrocarbon fuel containing a portion which produces objectionable deposits when heated to decomposing temperature, including an open' top burner bowl for burning said fuel and having an air inlet to supply combustion supporting air into the burner bowl for maintaining combustion of fuel within the burner bowl, a vaporizer having an outlet clischarging into the burner bowl, means for supplying the liquid hydrocarbon fuel to the vaporizer under pressure, fuel atomizing means cooperating with the fuel supply means for initially delivering air with the fuel foi` atomizingsaid fuel discharged into the burner b`owl during starting operation to initially heat the burner bowl.and a collar having heat conductive connection with the burner bowl and engagement with a' limited portion of said vaporizer belowrsaid outlet to 'conduct a pref determined amount of heatv from the burner bowl to the vaporizer for heating fuel within the valing temperature, including an open top burner bowl for burning said fuel and having an air inlet to supply combustion supporting air into the burner bowl for maintaining combustion of fuel within the burner bowl,l a vaporizer having an outlet discharging into the burner bowl, means for supplying the liquid hydrocarbon fuel to the vaporizer under pressure, fuel atomizing means cooperating with the fuel supply'means for initially delivering air-with the fuel for atomizing said fuel discharged into the burner bowl during starting operation to initially heat the burner bowl, 'a'ame deector, means supporting the flamedeflector within the open top of the burner bowl to deflect flame resulting from combustion of said atomized fuel into contact-with an upper portion of the burner bowl to'initially heat the burner bowl, and 'a heat conductive connection between the burner bowl and said vaporizer to conduct -a predetermined amount of said heat from the burner bowl to the vaporizer for heating fuel within the vaporizer tba temperature below thedecomposing point of said objectionable portion of the fuel and suiiicient to vaporize portions of they fuel having a lower distillation point whereby the objectionable portion is discharged from the vaporizer into the burner bowl'in substantially liquid form and other portions of the fuelin vapor form for continuing operation of said apparatus.

6. An apparatus for burning liquid hydrocarbon fuel containing a portion which produces objectionable deposits when heated to decomposing temperature, 'including' an open top burner bowl for burning said` fuel and having an air inlet to supply combustion supporting air into the buiner bowl for maintaining combustion of fuel within the burner bowl, 'a vaporizer having an,

outlet discharginginto 'the burner bowl, means 'for supplying the liquid hydrocarbon fuel to the vaporizer under pressure, fuel -atomiaing means cooperating with the fuel supply means for initial'y delivering, air with the fuel for atomizing `and suiliclent to vaporize portions of the fuel having alower distillation pointwhereby the objectionable portion is discharged from the vaporizer' into the burner bowl in substantially/ liquid form and said other portions in vapor form forv continuing operation of said apparatus, and a shield encircling the burner bowl for limiting external cooling effects on said burner bowl.

7. An` apparatus for burning liquid hydrocarbon fuel containing a portion which produces objectionable deposits when heated to decomposing temperature, including an open top burner bowl for burning said fuel and having an air -inlet to supply combustion supporting air into the burner bowl foi-.maintaining combustion of fuel within the burner bowl, a vaporizer .having an outletgdischargingtinto the burner bowl, means for supplying the liquid hydrocarbon fuel to the vaporizer under pressure, `fuel atomizing means cooperating with the fuel supply means for initially delivering air with the fuel for atomizing vsaid 4fuel discharged into'the burner bowl during l starting operation to initially heat the burner bowl, a flame deflector, means supporting the flame deflector within the open top of the burner bowl to deect flame resulting from combustion of said atomized fuel into contact with an upper portion of the burner b owl to initially heat the burner bowl, a heat'conductive connection between the burner bowl and said vaporizer to conduct a predetermined amount of said heat from the burner bowl to the lvaporizer for heating fuel bowl contacted by said flame for limiting external cooling effects on said burner bowl.`

8. An apparatus for burning liquid hydrocar-A bon fuel containing a compound which produces objectionable deposits when said compound is heated to decomposingtemperature including, r

an open top burner bowl-for 4burning said fuel and having air air inlet to supply combustion supporting air Aint'o the burner bowl, a vaporizer having an outlet for discharge into the burner bowl, means for supplying said fuel to the vaporlzer for discharge into the burner bowl, heat conductive means connecting the burner bowl with a limited portion of said vaporizerI for. conencircling the portion of the burner bowl conn resulting from combustion of fuel in the burner y bowlfor deilecting the flame into contact with an upper portion of the burner bowl, and a shield to decomposing temperature including, an open top burner bowl'for burnirm said fuel and having an air inlet to supply combustion supporting air into the burner bowl, a vaporizer having an outlet for discharge into the burner bowl, means for `supplying said fuel to the vaporizerfor discharge he t from the burner bo'wl'to'the vaporizer nec--4 4 to maintain'the temperature of yfuel 4Within thelveporizer beiowthedecomposing temper-` ature of said compound so that the compound is di'sciarged limo the burner bowl without being decomposed in the vaporizer. a llame defiector located m the borner bowl within themen cfm meente "y v t l discharge from the vaporizex" enclin position to be contacted by the'fiame resulting from combustion of fuel within the burner for detecting-the flame into contact with an upper portion of the burner bowl, and a shield encircling the portion otthe burner bowl contacted by said fime and depending below Zsaid heat conductive means for limiting external cooling effects on'said heat conductive means.

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