US1841463A - Safety pilot apparatus - Google Patents

Description

Filed March 20, 1930 IVENTORSI H. B. BARBER ET AL SAFETY PILOT APPARATUS Jan. 19, 1932.

BY E. (5. DE Comous ATTORNEY.

R E. B R A B B F H Q g A R Q O H R t v NW mow x w Q .Q 8 3 Patented Jan. 19, 1932 UNETED STATES PATENT OFFICE HUG-H B. BARBER AND ERNEST G. DE CORIOLIS, OF TOLEDO, OHIO, ASSIGNORS TO SUR- FACE COMBUSTION CORPORATION, OF TOLEDO,

YORK

OHIO, CORPORATION OF NEW SAFETY PILOT APPARATUS Application filed March 20, 1930. Serial No. 437,398.

This invention relates to safety pilot mechanism for pressure burners and more particularly for pressure burners adapted to burn self-sustaining mixtures of gas and air, the invention having special utility in connection with burners arranged to fire into a closed chamber where access to the burners for lighting is a difficult matter.

The invention has among its objects to provide means outside of the chamber whereinto the burner fires for continually supplying to the burner a stream of flame of such character and in such manner that irrespective of conditions in said chamber the flame will not blow off to provide means for automaticallyrelighting the pilot burner in case it should become extin ished; to rovide means for automatically shutting o the supply of fuel to the pressure burner during the interval the pilotburner is not functioning, and to provide other improvements as will more fully hereinafter appear.

Referring to the drawings wherein the pre-.

ferred embodiment of the invention is shown:

Fig. 1 is a side elevation of apparatus showing the environment where the present invention finds special application, a portion of the heater, casing wherein the burner to be lighted is contained being broken away.

Fig. 2 is an enlarged sectional view of a portion of the apparatus shown in Fig. 1. V

Fig. 3 is a plan view on an enlarged scale of apparatus shown in Fig. 2.

Fig. 4 is a cross section on line 4-4 of Fig. 3.

Fig. 5 is an enlarged fragmentary view of the main pilot burner shown in Figs. 2, 3 and 4.

Fig. 6 is a lan view on an enlarged scale of Jzhe seconcidry pilot shown in Figs. 2, 3 an 4.

Fig. 7 is a side elevation of the burner shown on Fig. 6.

In Fig. 1, 10 indicatesan oven such as a drying oven to be supplied with a-heated gaseous medium, such as air and gaseous products of combustion, 11 the heater casing, 12 a pressure burner, 13 a. conduit within the casing 11 and which delivers into theoven 10, the burner 12 discharging into the adjacent end of the conduit, 14 a pipe leading from the oven 10 and delivering into the casing 11,

and 15 a fan for withdrawing spent heating gases from the oven and delivering the same into the casing for reheating by passing ifzihrough the conduit into which the burner res.

The mechanism for lighting the burner 12 projects from a reentrant portion 16 formed with the front wall 19 of the air heater casing 11. The type of pressure burner for which the pilot mechanism has been primarily designed is shown in cross section in Fig. 2 and comprises a combustion tunnel 17 formed in a body of refractory material 18 contained within a sleeve-like casing which projects from said front wall 19. Combustible mixture is supplied to the combustion chamber by a nozzled head 20, the nozzle end of which is surrounded by the refractory wherein the combustion tunnel is formed, the head being provided with heat dissipating fins 21. The mixture supply pipe is indicated at 22 and is provided with a suitable valve 23 adapted to be opened and closed; by an electric motor 24 of suitable type.

The combustible mixture delivered by pi e 22 will be formed in any suitable manner y means not shown and will be a self sustaining mixture of air and gas, such mixtures being termed explosive mixtures. This mixture issues from the nozzle head with sufiicient velocity to prevent back firing thereinto and expands and burns in the combustion chamber 17 from whence the hot gases flow into the adjacent end of the conduit 13 where they mingle with the spent gases which find assage thereinto after havm been delivere into the casing 11 by the pipe 14 and fan 15, the mixture of'heated gases flowing from the conduit 13 into the oven 10 as Wlll now be readily understood. The-pressure burner itself forms no part of the present invention, it being merely an element thereof.

In communication with the combustion chamber is a downwardly and forwardly ex- 4 tending passage 25. In axial alinement with and delivering into said passage is an inspirator comprising a body portion 26 having a tube 27 therein and a mouth 28 intermediate its ends. The tube intermediate its ends has a restricted portion forming a jet orifice 29 and has a plurality of entraining openings 39 somewhat removed from said jet orifice. Coupled to the outer end of the body 26 is an air supply pipe 31 for delivering air under pressure to said tube. The air in issuing from the jet orifice 29 will set up an entraining effeet through the openings 30 adjacent thereto as will be readily understood.

Positioned to discharge into the mouth 28 is a gas burner 32 which is supplied with gas by a supply pipe 33, this burner preferabl having an ad ustable sleeve 34 to permit a justment of the burner outlet with respect to said mouth. The gas delivered to this burner is raw gas, that is, gas without admixture with air, no means being provided in conjunction with the burner for supplying air thereto prior to its issuance from the burner tip. The gas issuing from the burner, therefore, burns like any stream of gas would burn in the open air, that is, with a relatively long luminous flame. The flame will enter the mouth 28 on the inspirator body and due to the entraining effect of the jet of air issuing from the jet orifice 29, the flame will be drawn into the tube through the openings 30 for passage to the combustion chamber for lighting the explosive mixture therein. It bein remembered that the flame issuing from t e burner 32 is practically a core of raw gas surrounded by flame sheath, it will be readil appreciated that the addition of air to the ame entering the tube through the opening 30 will supiply ter the necessary air to support combustion a the flame enters the tube 27.

The inspirator may be of any preferred type. As shown the body is preferably chambered about the tube intermediate its ends primarily, to simplify manufacture since in side machining of the body is then required only where the ends of the tube are supported, the tube being, of course, removable from the body. For convenience of description the gas burner 32 may be termed the main pilot, there being provided for lighting the main pilot a small gas burner or secondary pilot, this secondary pilot being in turn ignited by a spark plug, the secondary pilot also serving to heat a thermal element which in turn controls the main gas valve motor 24, as will presently appear.

Adapted for securement to the wall 19 is a bracket 40 having an upturned angle 41 through which the gas pipe 33 extends for support and through which also extends a gas pipe 42 at the outer end of which is a relatively small gas burner 43 having a restricted tip and having jet openings 44 for some distance below its tip whereby gas may issue from said openings for burning-along with the gas issuing from the tip. This burner 43 may be termed a secondary pilot, one of its functions being to present a light for the main pilot 32 which is materially larger than the burner 43 and consequently discharges considerably more gas. Carried by a wing 45 on the angle 41 of the bracket is a spark plug 46 for igniting the gas issuing from the secondary pilot, the wiring system being presently described.

Supported by a suitable arm 47 on the bracket 40 is an elongated arm or member 48 shown as having upwardly and inwardly turned ends. Secured to one end of the arm 48 is a bimetal blade or thermal element 49, it being noted that the blade is at one side of the two burners 32 and 43. Secured to the blade in thermal relation there-with is a laterally projecting plate 50, this plate preferably being arranged at one side of the tip of the burner 43 as clearly shown in Fig. 3 and adapted to be heated from below primarily by the flames issuing from the underlying jet orifices 44 in the burner 43. The spark plug 46 is so mounted with respect to the burner 43 that gas issuing from the adjacent jet orifices 44 thereof will be ignited by the spark across the terminals of the spark plug as will be readily understood.

At the free end of the blade 49 is a suitable terminal 51 adapted to make contact with opposite terminals 52 and 53 carried by the arm 48. When the blade 49 is hot its terminal will contact with terminal 52 and when cold with terminal 53. Connecting with terminal 51 is a power lead 54. The other power lead 55 connects with motor 24 from whence it continues as wire 56 to terminal 52. indicates a transformer having a lead 57 running to lead 55 and a lead 58 running to terminal 53. The spark plug is in circuit with the .transformer by the direct wire 59 and the ground wire 60. When terminals 51 and 52 make contact (the blade 49 being hot) the motor 24 will be actuated to open the pressure burner gas valve 23, the motor being of such type that when its circuit is broken the valve will automatically close. It follows therefore that when the blade 49 breaks contact between terminals 51 and 52, the valve remains closed until contact between said terminals is again established. When terminals 51 and 53 are in contact the spark plug circuit is closed which, of course, means that sparks will flow across the spark plug terminals and ignite the jets of gas issuing from the adjacent jet orifices 44 in the secondary pilot burner 43, whereon both of the pilot burners 43 and 32 will be ignited.

It is preferred to provide a screen case 61 in front of the reentrant portion 16 wherein the safety pilot mechanism is contained to reduce explosion hazard in case the pilot burners should become extinguished. Both pilot burners may be supplied with gas from a common supply pipe 62, each of the burner supply pipes being provided with suitable regulating valves-63.

- While the invention finds special utility in connection with pressure burners firing into air heaters, it has other applications as will be readily appreciated.

What is claimed is a 1. In combination, means forming a flow path for combustible mixture, a passage opening into said path, an inspirator forming a continuation of said passage, means for supplying air under pressure to said inspirator to serve as an inducin medium, means for producing a flame in su ciently close roximity to the inspirator to permit the ame to be entrained thereby.

2. In combination, means forming a flow path for combustible mixture, an inspirator delivering into said path, means for directing a flame towards the inspirator from one side thereof, means for supplying an inducing medium to said inspirator, said means and inspirator being in such relation that said medium in flowing through the inspirator will induce the flame to entersaid inspirator for flow through said path.

3. In apparatus for lighting a stream of combustible mixture by means of a flame, the combination with a passageway for delivering astream of air into said mixture, of means for producing said flame at one side of said passageway and means associated with said passageway for drawing said flame into the stream of air for delivery therewith into the flow path of said combustible mixture.

4. In combination, a wall having a reentrant portion, a burner projecting from said wall adjacent said portion, an inspirator within said portion and delivering to said burner, and-a pilot delivering flame to said infpirator, said inspirator being above said i ot. 40 p 5. In combination, a combustion tunnel, an inspirator delivering into said tunnel at an angle to the axis thereof, means for supplying flame to the inspirator from below the same, and means for supplying air under pressure to said ins irator-whereby to deliver the flame to sai tunnel; 4 In testimony whereof we afiix our signatures. j HUGH" B. BARBER. n.

ERNEST G. on CORIOLIS.

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