US2860695A

US2860695A - Gas-fueled igniter system

Info

Publication number: US2860695A
Application number: US465830A
Authority: US
Inventors: Harry E Lake
Original assignee: Preferred Utilities Manufacturing Corp
Current assignee: Preferred Utilities Manufacturing Corp
Priority date: 1954-11-01
Filing date: 1954-11-01
Publication date: 1958-11-18
Anticipated expiration: 1975-11-18

Description

Nov. 18, 1958 H. E. LAKE GAs-FUELED IGNITER SYSTEM 2 Sheets-Sheet JL Filed NOV. l, 1954 INVENT'OR Hamm E. LA K5 l ATTORNEY Nov. 18, 1958 H. E. LAKE GAS-FUELED IGNITER SYSTEM 2 Sheets-Sheet 2 Filed Nov. 1. 1954 /CfODl/Cf' 6,45

E I E 1r.: VENTOR HARRY ,ET LAKE Zr@ .w/ f ^J ATTORNEY United States Patent O VGAS-FUELlED IGNITER SYSTEM Harry'E. Lake, `Bethel, Conn., assignor to Preferred Utilities Manufacturing Corporation, New York, N.-Y., a corporation loflDelavvare Application Novemberl `1, 19.54, Serial No. `465,830

Z Claims. (Cl. 153-4115) This invention relates to a new andimproved igniter `system `which :eliminates `the need for fuel `jets and .includes a self-.compensating feature which insures `correct gas-air ratios .for :the igniter despite variations `in `fuel supply pressure, draft, rate of `fuel consumption, humidity, and other factors.

Since `the .advent of natural gas into lterritories -where automat-ic oil burner `systems are in use, considerable ydiiieultyhas `been experienced `in the use of gas-electric ignite-rs which previously worked satisfactorily on Iproducer gas.

Natural gas, being principally methane, has a very ysmall range of gas-airmiXtu-res at which llame propagation takes place at the necessary speed. Because of this `small gas-.air range, `the air and gas jet adjustments be- `come extremely `critical under the varying conditions of gas pressure, draft, rate `of fuel consumption with its controlled primary and secondary air mixture, humidity, and the introduction of :air .from the burner fan case. in some sections the natural 4.gas `and the producer `gas are mixed creating further problems.

Attempts to meet thi-s situation by .the provision of different size gas jets has -not been 4entirely satisfactory. lt will .be appreciated that gas jet type igniters .using natural gas will `not .function properly should `the gas supply line pressure vary to .any great 'extent andshould `a .break in the line or a large drain thereon develop reducing the supply pressure below `the minimum .operating pressure for the igniter, the igniter will fail cornpletely. Even under normal conditions, the small gas- .air range of natural gas causes ,many difficulties in using gas jets due fto `the extremely delicate adjustments which mustbe made and maintained. The cost .of maintaining such igniters in operating condition is not inconsequential.

By my Vinvent-ion the` problem ,of manufacture, installation and maintenance .of precisely `sized gas jets is eliminated. My invention :comprises an igniter system which has acem-pensating venturi means within .a housingg means are provided `for supplying a ll-ow of air through :the venturi; Aarid means are provided `for .continuously -maintaini-nga `source `of fuel at Ithe venturi which ;is at a predetermined .steady pressure, zero gauge pressure, to enable the formation of a combustible :mix-

ture having a :substantially constant fuel-air ratio for all rates of flow. A suitable Vpressure reducing valve in the `gas supply line lestalzrlishes the source of `zero gauge pressure fuel which will be available over an extremely large `range of supply Aline pressures. My igniter system, therefore, will operate satisfactorily below the `minimum :pressure level :at which gas jet igniters fail. Also in `emn'bination in my ignitcr system is an electric spark means `which "has an 'igniterfrom which `is emitted a .conedike spray of sparks. i

To `protect `the igniter `from becoming short-.circuited Eby .the formation `of carbon :filaments `and to provide `an added venturi effect, .a tube is provided around `the @leggio spark means which has a by-pass hole communicating with fthe air supply. In this manner a protective flowing layer of iair is `formed within the tube .and directed lpast the igniter through the cone-like .spray .of sparks. `Hauling .and fila-ment formation .are thereby prevented., Further the :blanketing stream of air so formed provides :an .added venturi effect on the ue'l Supply `capable of forming a mixture having :a substantially constant :fuel-air ratio for :all rates of how.

The gas port to the housing is 4of ,Suicien-t size `to .supply-the required arnountlof `gaseous fuel to .the venturi means without .appreciable `friction loss. .In `the `average size igniter, the `gas A.port ymay have a minimum size of one-,quarter inch `diameter for it has been discovered `that this 4size port is .suitable for burning `gas with any `heatcontent from .500 to `250.0 B. T. Ufs ,per cubic foot. ltwill be appreciated that larger igniters of Ythe type, for example, capable of `burning ,more than` 50 .cubic feet `per hour of ynatural .gas would require .a larger port .t0 .insure negligible :friction losses. `Therefore the size of the ygas port must .belarge enough to supply the capacity `of the igniter .at `zero `gauge pressure, otherwise the inspiring effect `of the air would be reduced by creating a vacuum on `the gas line. Other .and Afurther advantages 4and objects of my invention will b ecome `more apparent hereinafter as the ,same becomes better understood from an examination .of the specification and claims .in conjunction with the accompanying .drawings wherein:

Fig. `l .is a fragmentary side View partly in section showing a horizontal rotary burner equipped with `an igniter and a pressure reducer for the igniter gas supply;

Fig. 2 is a graph showing the speed of uniform movement of llames of `methane and producer gas in air;

Fig. 3 is a front end fragmentary view `of a horizontal rotary burner, llame rod and the igniter of `my inventiongand p Fig. 4 is a rear end viewpof the igniter `showing the air inlet, the gas inlet, and the electric spark means.

Referring now to Fig. 1, it will be seen that the `igniter 14 is suitably mounted adjacent a horizontal rotary oil burner 15 of conventional design, this type burner beingshownfor `purposes of illustration only. fThe burner 15 is supplied with primary -air by a suitable lblower (not shown), the air lfor, the igniter 14 being directed at the -air inlet V16 from the fan case 17 b y means of a nozzle 18. made, but experimentation has shown this added part to be unnecessary. Where an `induced draft fan is used, the negative pressure in Athe `furnace may be sufficient to draw the required air .through the igniter 14, thereby eliminating `the necessity for Va blower supply.

The igniter 14 is attached to a nozzle shield 19 by means of ears 20 `(Fig. 4) whichextend from the main body 22 of the housing indicated generally `by rnumeral 21. The housing is made up ofthe main body 22 having a venturi `means and -a llame barrel 24 having a flame retention ring 25. The main Vbody has a circular opening 26 `at its forward end `which 4surrounds a concentrically disposed disc igniter 27, the disc igniter being attachedto the forward free endfofian electric spark `means 28. "The rear end portion of theeelectric lspark means `is rigidly `mounted in ithe rear end portion ofvthe main body 22 by suitable means, such as the threaded clamping collar 29 shown in Fig` 11i This collar forces the Vspark plug toward the annular `shoulderi) in the maintbody v22 and clamps the spark plug 28 as well as a protective air tube 31 in proper rigidposition within the main body. The forward body portion .ofthe spark plug visof less diameter than the rearward portion to provide `an annularfair conduit 32 with the forward portion of theprotecfive air tube 31. `The rearward portion ofthe air tube 31` con- Patented Nov. 18, 1958 If desired, a direct pipe connection can be the balance.

Vup of foreign matter on the peripheral edge. vnular air -conduit 32 produces a venturi effect on the gas 'chamber 35 and aids in the production of a final fuel-air l.mixture having a substantially constant ratio for all rates a of air flow. The tube 31 and the annular air conduit 32 vity air. `directy proportion to the air flow and the resultant gas- ,air mixture then flows as an annular cylinder between the ,w-all of the circular opening'26 and the inner annular protective cylinder of air.

tacts and is Ysupported bythe rearward portion of the spark plug 28.

The main body 22 has a venturi means which surrounds the protective air tube 31 and. is arranged to direct a cylinder of air and fuel past the peripheral sparkingy edge of the disc igniter 27, an inner protective cylindrical layer of air alone being supplied also to prevent short circuiting of the disc electrode as will be explained. The venturi means includes an inwardly extending partition member 33 which surrounds and is outwardly spaced from the protective air tube 31 and which defines a rearwa'rd air chamber 34 and a `forward gas chamber 35.

A gas line 36 connects the gas port or opening 37 of i ythe gas chamber to a pressure reducing valve 38 which illustration, however, a well known governor type pres sure reducing valve is shown. In this valve the gas in supply line 39 tends to push the valve disc 40 open, but this tendency is exactly balanced by the upward push against the lower diaphragm 41. The weight of all moving parts is always exactly balanced by the sensitive spring 42. So long as the pressure in the diaphragm case under the upper diaphragm 43 is the same as that above the diaphragm, the valve will not move, but if this pressure drops because gas is drawn yaway through gas line 36 to gas chamber 35, the difference in pressure on the two sides of the upper diaphragm 43 at once moves the valve disc down, allowing more gas to go through to restore Regardless how much gas is being drawn, the valve opening is just enough to supply that much gas at exactly zero gauge or atmospheric pressure or what ever pressure is imposed on top of the upper diaphragm p 43. As the top diaphragm through port 44 is normally open to the atmosphere, the gas delivery pressure is also atmosphericflAny pressure may be selected as a base pressure by connecting port 44 to a source of the desired pressure.

The protective air tube 31 has anannular series of by-y pass holes 46 adjacent the air chamber 34 which bypass air around the venturi `and through the anular air conduit 32 between the protective air tube 31 and the spark l plug 28 to form a protective annular cylinder of air which alone contacts the peripheral sparking edge of the disc igniter 27, thereby preventing the formation of a car- `,bon filament from the disc igniterto the main body. fShould such-a filament form, sparking would cease since the current would pass along the filament.

The protective air tube prevents this as well as any excessive build- The antherefore provide an inner venturi means and the main body 22 including its partition 33 forms in part the outer venturi means. u The inner edge of the partition member 33 is spaced joutwardly fromthe protective air tube 31 to form a constricted annular air passage 47 for the flow of high veloc- This air draws gas from the gas chamber 35 in Sparks from the disc igniterl 27 form au annular spray of outwardly and forwardly moving sparks to the outwardly flared forward end 4S of the main body.

The flame barrel 24 surrounds and is connected by a screw 49 to the reduced forward end of the main body. The flame retention ring 25 is positio-ned within the forward end of the flame barrel, the holes therein causing a portion of the fuel-air mixture to burn as a plurality of small flames which insure continued burning of the main center ame of the igniter at all firing rates.

As seen in Figs. l and 4, the air inlet 16 is an internally threaded opening to the air chamber 34. The oneadjustment needed for this igniter, namely the control of the volume range of air used by the igniter, may be easily made by the addition of a diameter reducing externally threaded tube t-o the air inlet.

The air inlet is on one side of the main body 22 and the gas inlet 37 (which includes a weatherhead fitting) is on the other. It' will be noted that the gas inlet 37 comprises a conduit which extends forwardly through the main body 22 to the opening (Fig. l) in the gas chamber. Through experimentation and tests it has been discovered that the minimum diameter of the gas port to the gas chamber is preferably of the order of one-quarter inch for average size igniters. By making the gas port of sufficient size to supply the required amount of gaseous fuel to the venturi means Without appreciable friction loss, it is possible to obtain the eiiicient and satisfactory burning of methane, which as seen in Fig. 2 has a small gas in air percentage range suitable for flame movement, as well as producer gas which, as seen in Fig. 2, has a larger gas in air percentage range.

The igniter is positioned just above the atomizer of the horizontal rotaryoil burner so that its flame will light the oil from the main burner as soon as it leaves the atomizer. it will be apparent that this igniter may be used on gas burners and other types of oil burners by suitable modifications of design and mounting.

A suitable flame rod Sil of well known design is mounted adjacent the igniter as shown in Fig. 3; its function is to prove that there is a pilot burning before the oil valve on the oil burner can open.

While a specific structure has been shown and described for illustrative purposes, it will be understood that the invention is not so limited and for that reason I wish to limit myself only within the scope of the appended claims.

I claim:

l. A gas igniter system for burners wherein said burners have a primary air source at a pressure higher than the pressure in the furnace which is suflicient to meet the requirements of all firing rates, said igniter systern comprising a hollow main body having an opening at its forward end, an electric spark means mounted at the rear end portion of said main body and extending centrally therethrough and having an igniter disc mounted at its free end concentric withsaid opening, a tube surrounding and outwardly spacedrfrom said spark means and having a forward free end terminating rearwardly of said igniter disc, said tube having'an air bypass hole and forming an annular conduit with the electric spark means, said tube extending approximately to the periphery of said igniter disc, said main body having a venturi means in fluid communication with said opening at said forward end including a partition extending inwardly from the wall of said main body and defining with said wall a rearward air chamber and a forward gas chamber, the inner edge of said partition surrounding and being outwardly spaced from said tube at a point forwardly of said bypass hole whereby one portion of air flow is directed through said bypass hole and the remaining portion of l air ow is directed through said venturi means, said main body having an air inlet opening adapted for conducting air from said primary air source to said air chamber, said main body having a gaseous fuel inlet port of sufficient size to supply the required amount of gaseous fuel to said gas chamber without appreciable friction loss, and means for providing a source for gaseous fuel at a constant pressure of substantially zero gauge pressure, said venturi means being adapted to cause air low from said rearward air chamber to said opening at said forward end to draw gaseous fuel from said forward gas chamber in amounts varying substantially directly with the Varying air flow from said primary source.

2. A gas igniter for burner systems wherein said burners have a primary air source at a pressure higher than the pressure in the furnace which is sufficient to meet the requirements of all firing rates, said igniter comprising a hollow main body having an opening at its forward end, an electric spark means mounted at the rear end portion of said main body and extending centrally therethrough and having an igniter disc mounted at its free end concentric with said opening, a tube surrounding and outwardly spaced from said spark means and having a forward free end terminating rearwardly of said igniter disc, said tube having an air bypass hole and forming an annular conduit with the electric spark means, said tube extending approximately to the periphery of said igniter disc, said main body having a venturi means in iuid communication with said opening at said forward end including a partition extending inwardly from the Wall of said main body and defining with said wall a rearward air chamber and a forward gas chamber, the inner edge of said partition surrounding and being outwardly spaced from said tube at a point forwardly of said bypass hole whereby one portion of air flow is directed through said bypass hole and the remaining portion of air flow is directed through said venturi means, an air inlet opening in said main body communicating with said rearward air chamber, and a gas inlet opening in said main body communicating with said forward gas chamber.

References Cited in the file of this patent UNlTED STATES PATENTS 1,399,010 Dobble Dec. 6, 1921 1,834,130 McKee Dec. 1, 1931 2,147,568 Barber Feb. 14, 1939 2,402,763 Longini June 25, 1946 2,493,743 Benson Jan. 10, 1950 2,499,207 Wolfersperger Feb. 28, 1950 FOREIGN PATENTS 218,082 Germany Jan. 20, 1910 UNITED STATES PATENT OFFICE CERTIFICATE OF ACORRECTION Patent No. 2,860,695 November 18, 1958 Harry E. Lake error appears in theprinted specification It is hereblv certified that uiring correction and that the said Letters of the above 4'numbered patent req Patent should read as corrected below.

Column 2, line 22, for "inspiring" read -f-f inspirating Signed and sealed this 24th day of March 1959.,

SEAL) ttest:

ROBERT C. WATSON KARL H. MINE Commissioner of Patents Attesting Ocer