US3404939A - Fuel burner ignitor - Google Patents

Description

,Oct 8, 1968 A. P. sAHA 3,404,939 FUEL BURNER IGNITOR Filed Oct. 6, 1965 i n {f/mssslkgffssms smX HHH mmf/Hummm mm l l l INVENTOR.

AATTO P. SAHA.

ATTORNEY.

Elsa United States Patent O 3,404,939 FUEL BURNER IGNITOR Aatto P. Saha, Jamesville, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Oct. 6, 1965, Ser. No. 493,444 2 Claims. (Cl. 431-263) This invention relates to an ignitor for use with a dispersible fuel burner and, more particularly, to such an ignitor for providing a highly stable pilot flame in the form of an outwardly 'diverging free spiral vortex.

Various types of ignitors which provide a pilot flame often require critical adjustment, such as exact fuel-air ratio and pressure, in order to function properly, and are often subject to blowout of the iiame.

It is a primary object of this invention to provide a new and improved ignitor for igniting a main flame of a dispersible fuel burner. A related object is provision of such an ignitor which provides a highly stable pilot flame in the form of an outwardly diverging free spiral vortex. A related object is provision of such a flame which is substantially unaifected by the variations in the fuel-air ratio or pressure of the fuel or air, and by the main fuel being ignited and the resultant main fiame.

Additional objects and advantages of the invention will be apparent from the following drawing in which:

FIGURE 1 is a fragmentary, longitudinal sectional view of a dispersible fuel burner, including a preferred embodiment of an ignitor, mounted on an end of a combustion chamber; and

FIGURE 2 is an enlarged, transverse sectional view of the ignitor taken generally along the line II-II in FIG- URE l.

In the embodiment illustrated in the drawing, a combustion chamber 11 includes a cylindrical side wall 12 and an end wall 13. A dispersible fuel burner 14 includes a main supply line 15 to a dispersible fuel main nozzle 16 illustrated as mounted on and opening through the longitudinal center of the end wall 13 for projecting a combustible spray 17 of gas or oil into the combustion chamber 11 to -burn and provide a main burner llame.

An ignitor 18 for igniting the spray 17 from the main nozzle 16 includes/a tube 19 having one end suitably secured to and opening through the combustion chamber end wall 13 to provide an ignitor nozzle orifice 20 for projecting a free spiral vortex pilot flame 21 diverging outwardly from the ignitor nozzle orifice 20 into the spray 17 from the main nozzle 16. The ignitor 18 includes a `body 22 and a vortex carrying combustion passage 23, illustrated as a cylindrical passage extending from the ignitor nozzle 20 at one end to an opposite rear end 24 of the body 22. The ignitor body 22 is mounted on the combustion chamber end wall 13 by means of the tube 19 which has a rear end opposite the nozzle orifice 20 telescopically received in an enlarged socket about the front end of the passage 23 in the body 22 and detachably secured lby a set screw 25. The interior diameter of the tube 19 is substantially the same as the diameter of the portion of the combustion passage 23 in the body 22.

Vortex forming means is illustrated in the form of a plurality of air passages 26 (FIGURE 2) extending through the body 22 and opening tangentially through ports 27 into the rear end 24 of the combustion passage 23 and communicating with an air plenum 28 connected with an air supply line 29 for passing air through the air passages26 to form a free spirtal vortex of combustion air 30 traveling axially slowly through the passage 23 to the nozzle orifice 20 with an axial velocity less than the pilot flame propagation rate, thus substantially preventing popping of the pilot flame 21. The Vortex 30 of combustion air includes an annular portion 31 rotating relatively ICC rapidly about a relatively substantially slower rotating core 32.

A pilot gas supply tube 33 extends through the air plenum 28 and through a bore in the rear end 24 of the ignitor body 22 to an open end discharge portion 34 generally coaxial with the combustion passage 23l and slightly downstream of the vortex forming ports 27 Ifor projecting a jet of combustible gas 35 axially through the vortex core 32. If desired, air ports 36 communicating with the air plenum 28 may be provided in the gas tube 33 to mix a small amount of air with the gas in the tube 33 before formation of a combustible mixture of the vortex air and the gas.

Means for igniting the resultant combustible mixture of vortex air and gas in the combustion passage 23 includes a spark plug 37 threadedly mounted in a nipple 38 suitably secured to the body 22, and opening through a port 39 in the body so that the spark plug electrodes 40 are positioned for igniting the combustible mixture of air formed at the inner face 41 of the rapidly rotating annular portion 31 of the vortex 30. The combustion passage 23 is substantially unobstructed so that the axial velocity of the air and gas moving through this passage is substantially constant below the flame propagation rate, and the resultant flame 21 extends through the combustion passage 23 from substantially the discharge end 34 of the gas supply tube 33 to and through the ignitor nozzle orifice 20.

As the pilot llame 21 emerges from the orifice 20, it diverges outwardly because of the centrifugal force of the various gases emitted from the orifice, to form a hollow conical pattern including combustible mixture and flame which penetrates and ignites the spray of combustible mixture 17 from the main nozzle 16. Satisfactory results may be obtained with a combustion passage diameter of 1% and length from tube open end 34 to 2", four equally spaced air passages 26 of 1A diameter, a 1/2" diameter gas supply tube 35, plenum airpressure drop and natural gas supply pressure drop across the ignitor of 1 water.

Should a quantity of gas in excess of the optimum fuel-air ratio be projected through the gas tube 33 into the vortexcore 32, the excess gas, as 42, is projected through the eye of the conical pilot flame 21 and into the combustion chamber 11 to burn" therein with the arne from the main nozzle 16. Similarly, should an excess quantity of combustion air bey provided in the vortex 30, the excess air, as 43, will spill outwardly about the conical flame 21 and combine with the ame from the main nozzle` '16. In the event of actual blowout of the conical pilot flame 20, as by the combustible mixture or llame from the main nozzle 16, for example, the combustible mixture burning a substantial distance within the combustion passage 23 again immediately ignites the conical portion of the pilot flame, so that, in effect, the pilot flame does not blow out. Only a small portion of the gas and air available to form a pilot combustible mixture is burned within the ignitor body, leaving most of the pilot combustible mixture to establish a relatively large pilot flame in the combustion chamber 11. Spreading of the conical pilot flame toward the combustible mixture from the main nozzle 16, makes positioning of the ignitor less critical relative to the main burner nozzle 16.

While a preferred embodiment of the invention has been described and illustrated, it should be understood that the invention is not limited thereto but may be otherwise embodied within the scope of the following claims.

I claim:

1. In an igniter for use with a dispersible fuel burner to provide a pilot flame for igniting a main combustible mixture, the combination of a tube having one end opening through a combustion wall chamber of the burner to provide a nozzle orifice for projecting a free spiral Ivortex ame diverging outwardly from the nozzle orifice, a body forming a vortex carrying combustion passage extending from the nozzle orice to the opposite rear end of the body, said body being mounted on said tube, vortex forming means including a plurality of air passages extending through the body and opening tangentially into the rear end of the combustion passage to form a free spiral vortex of combustion air adapted to travel axially through the passage to the nozzle orifice with an axial velocity less than the pilot ame propagation rate, the vortex including an annular portion rotating relatively rapidly about a relatively slower rotating core, a pilot gas supply tube extending generally coaxial with the combustion passage and slightly downstream of the openings of said air passages for projecting a jet of cornbustible gas axially through the vortex core, and igniter means for igniting the combustible mixture in said combustion 4passage to provide a pilot ame, said tube nozzle orifice discharging the pilot flame from said combustion passage in an outwardly diverging hollow conical pattern to ignite the main combustible mixture.

2. An igniter according to claim 1 in which a plurality of air ports are provided in the gas supply tube.

References Cited UNITED STATES PATENTS 1,369,602 2/1921 Amsler 158-109 XR 2,117,356 5/1938 Perry 158-991 X 2,723,659 11/1955 Young et al 158-991 X 2,876,832 3/1959 Peters 158-115 2,952,307 9/1960 Schram et al 158-110 X 3,002,819 10/1961 Brace et al 239-405 X 3,265,113 8/1966 Thurley et al 158-109 3,273,623 9/1966` Nesbitt 15S-991 X FREDERICK L. MA'ITESON, JR., Primary Examiner.

H. B. RAMEY, Assistant Examiner.

Claims (1)

1. IN AN IGNITER FOR USE WITH A DISPERSIBLE FUEL BURNER TO PROVIDE A PILOT FLAME FOR IGNITING A MAIN COMBUSTIBLE MIXTURE, THE COMBINATION OF A TUBE HAVING ONE END OPENING THROUGH A COMBUSTION WALL CHAMBER OF THE BURNER TO PROVIDE A NOZZLE ORIFICE FOR PROJECTING THE FREE SPIRAL VORTEX FLAME DIVERGING OUTWARDLY FROM THE NOZZLE ORIFICE, A BODY FORMING A VORTEX CARRYING COMBUSTION PASSAGE EXTENDING FROM THE NOZZLE ORIFICE TO THE OPPOSITE REAR END OF THE BODY, SAID BODY BEING MOUNTED ON SAID TUBE, VORTEX FORMING MEANS INCLUDING A PLURALITY OF AIR PASSAGES EXTENDING THROUGH THE BODY AND OPENING TANGENTIALLY INTO THE REAR END OF THE COMBUSTION PASSAGE TO FORM A FREE SPIRAL VORTEX OF COMBUSTION AIR ADAPTED TO TRAVEL AXIALLY THROUGH THE PASSAGE TO THE NOZZLE ORIFICE WITH AN AXIAL VELOCITY LESS THAN THE PILOT FLAME PROPAGATION RATE,

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