US2772730A

US2772730A - Gas burner and constant pilot

Info

Publication number: US2772730A
Authority: US
Publication date: 1956-12-04
Anticipated expiration: 1973-12-04

Description

Dec. 4, 1956 R. l. WARNECKE 2,772,730

GAS BURNER AND CONSTANT PILOT Filed Aug. 14, 1955 United States Patent GAS BURNER AND CONSTANT PILOT Robert I. Warnecke, Cheektowaga, N. Y., assignor to Roberts-Gordon Appliance Corporation, Buffalo, N. Y.

This invention relates to improvements in gas burners and more particularly to improvements in applying a plot burner to a fluid fuel burner of the type shown in Gordon United States Patent No. 2,183,836 in such manner as to prevent extinguishing of the flame of the burner during initial lighting of the same.

In burners of this type which include a main fuel duct and a pilot burner in close proximity thereto, it occasionally happens that the flame of both the pilot and the main burner become extinguished. This trouble has long been recognized and efforts have been made to overcome this difficulty but heretofore none of these efforts have been successful. This extinguishing of the flame generally occurs during the initial lighting of the burner, when the parts of the furnace are cold and no draft has been established. This condition presumably results in a resistance within the combustion chamber to the expansion of the burning gases and a flaring of burnt gases backward through the air passages is then experienced. These flaring gases may block the passage of air which supports combustion, and thus may extinguish both the main and pilot burners. The pilot burner will be extinguished, if it is located at or near the end of the fuel duct, as is generally the case. i p I When both burners are. extinguished; unburnt gases may continue to flow into the combustion chamber'un'til the control valve is actuated to shut off the gas because 'of the pilot burner being extinguished. This results in inpilot burner tube, so as to position this part of the flame T below the zone of flaring gases. While this arrangement has. proven to be superior to'pilots in which the: entire flame 'is at the upper end of the main fuel duct entirely in the zone of the flaring gases which are experienced-on 2,772,730 Patented Dec. 4, 1956 extinguishing of the entire burner will be prevented and a relighting 'of the fuel discharged from the main burner duct will be quickly accomplished when the normal ignition flame is extinguished and the gas supply to the actuating means is reduced to an amount just suflicient to actuate the device.

Other objects and advantages will be apparent from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawings:

Fig. 1 is a fragmentary elevation, partly in section, of a gas burner installed in a furnace.

Fig. 2 is a sectional elevation thereof, on an enlarged scale, on line 2--2, Fig. 1. v

Fig. 3 is a fragmentary, transverse sectional view thereof on a still larger scale on line 3-3, Fig. 2. v

Fig. 4 is a fragmentary elevation of the upper portion of the pilot burner and the flame guide.

In Fig. 1 there is shown, by way of example, an installation of a fluid fuel burner in a furnace or heater having a combustion chamber 5 into which fuel is discharged by means of a fuel duct 6. This fuel is ignited and impinges against a deflector 7 by means of whichthe flame is deflected against the side walls of the combustion chamber. 8 represents a housing extending out of the furnace or heater and which contains various parts for controlling the flow of fuel and air to the furnace. The fuel duct 6'rnay be provided at the periphery thereof with upwardly extending arms 9 which extendto a horizontal partition 10 forming the bottom of the combustion chamber. V

The pilot burner includes a fuel supply pipe 12 which leads to a mixing chamber 14 having a primary air supply opening 15 therein. A jet of fuelis projected upwardly at substantially'a right angle to the axis of the air inlet 15 into a restricted passage 16 which in turn opens into a larger passage 17 to which a tube or duct 18 open at both ends is connected. To the upper portion of the tube 18 is connected a flame guide tube 19 through which the mixture of air and gas passes, this tube in the construction shown by way of example being formed of a sheet of metal bent partly into cylindrical form, thus leaving a longitudinal opening extending preferably throughout the length of the tube. The upper end of the flame guide tube extends above the upper end of the 1 main fuel duct 6 so that when a pilot flame is maintained a cold start, yet this construction is open to the objection 'main fuel duct and of the pilot during the initial start i of the flame by positioning a part of the flame of the pilot burner below the zone of the flaring gases, and providing means for quickly carrying this flame to the main fuel duct. Another object is to provide a simple and inexpensive construction by means of which the projected .toward the thermostatic element.

atthe upper end of the'flame guide'tube 19, fuel discharged from the fuel duct 6 will be ignited.

The'pilot burner also includes a control member 20 which is only partly shown in Fig. 2, and which is shown in broken lines in Fig. 1. This control. member generally includes a thermostatic element which acts through well known means to close avalve supplying fuel to the main fuel "duct 6 when the pilot'flame becomes extinguished. The pilot is so constructed that it deflects a small flame toward the thermostatic elementof the control device so as to heat the same when the pilot flame is burning. In order to accomplish this result, the pilot tube 18 is provided with a slot 21 which is' so arranged that a, small quantity of fuel will pass through this slot andwill be This slot extends upwardly to the'upper open end of the tube 18 and is in registration with the opening in the flame guide tube so that fuel burning at slot 21 will readilyv ignite fuel escaping through the open end ofthe tube 18 and flame guide tube'19'. 24 representsia duct or cover for the back of the pilot burner. Secondary air for the pilot flame enters at the lower open end of this cover, which is well below the zone of flaring gases. 25 represents a pin or rivet which extends across the fuel passage or duct 18. of the pilot burner and consequently tends to deflect fuel passing upwardly within this passage through the slot 21. The pin or rivet may also be used to form a connection between the flame guide 19 and the pilot tube 13.

When, because of reasons heretofore mentioned, a flareback of burnt gases results in the combustion chamber, these gases will pass downwardly through the air passages of the burner to a limited extent, and thus prevent the passage of secondary air to the upper end of the fuel duct 6, which may result in extinguishing both main and pilot ignition flame. These flaring gases, however, will not extend downwardly far enough to extinguish the flame burning at the lower part of the slot 21, although in most cases the backwardly flaring gases will extinguish all flame above this point. Furthermore, as heretofore mentioned, the air supply to the pilot burner enters the lower open end of the cover 24, and because this opening is well below the point of the flaring gases, the pilot flame at the slot will be maintained even though the ignition flame at the end of the flame guide tube is completely smothered out. As heretofore stated, in burner constructions as heretofore made, the slot 21 extended downwardly far enough to maintain flame during the flareback at the lower end of this slot. However, after a flareback occurred, a considerable time interval elapsed before this small flame would ignite the gas at the upper end of the pilot burner, andin turn, the gas discharged from the main fuel duct 6. During this time interval, a quantity of unburnt gases would pass upwardly through the main burner'duct without becoming ignited. When ignition finally took place, the ignition of the unburnt gas in the combustion chamber would cause a disturbance in the form of a popping noise or slight explosion.

It is consequently very desirable to use this small remnant of flame at the lower part of the slot 21' of the burner for. more rapidly relighting the burner before any substantial quantity of fuel passes through the fuel duct 6 into the combustion chamber, and for this purpose I have provided the main fuel duct 6 in the side facing the pilot burner with a slot 28 extending downwardly from the upper edge of the main fuel duct through which combustible mixture from thefuel duct may be deflected outwardly to the pilot burner to become ignited from the small remaining flame at the lower end of the slot 21. When such a jet of fuel passing out through the slot 28 becomes ignited, the flame will quickly be carried up to the upper edge of the main burner duct 6 so that the fuel discharged from this duct will be quickly re-ignited.

In order to make sure that combustible mixture passing out through the slot 28 will be deflected downwardly to the flame at the lower end of the slot 21, I provide within the fuel burner a small channel 30 having its open side facing the wall of the main fuel duct 6 and open at its lower end to receive a small portion of the combustible mixture passing upwardly in the fuel duct. This channel is arranged in such a manner. that a portion thereof 'will straddle the slot 28. The channel 34) may be held in place on the main fuel duct 6 in any suitable manner, for example, by means of a screw or bolt 31 extending through a hole in the wall of the main fuel duct 6 and having a threaded engagement with a threaded hole in the channel, The channel is closed or partly closed at its upper end to ensure the passage of fuel out of the main duct through the slot 28, for example, the channel may be provided at the upper end thereof with a downwardly inclined deflector 32, which slopes downwardly toward the slot 28, wellabove the lower end thereof. The outer end ofthe deflector 32 is spaced from the slot .28 and the inner surface or wall of. the main burner duct 6, so as to allow for a continuous unbrokencarry-over flame at the slot 28. It is important that a-carry-over flame'should be continuous to ensure continuing of the. flame to the discharge port of the main burner duct 6. This arrangement as shown is such that the deflector will project a jet of fuel toward the slot 21, but will still allow fuel to be ejected through the slot in its entirety, in such manner that when this fuel is ignited, it burns in a continuous flame lengthwise of the slot to ensure ignition at the main burner duct 6, rather than forming two jets separated at some point near the deflector, in which case the upper jet may not be readily ignited, thus resulting in delayed igniton of the gas at the main burner port.

As a result of this construction, it will be obvious that primary air and gas mixture passing upwardly in the channel 30 and impinging against the deflector 32 will be de flected outwardly through the slot 28 toward the flame at the lower portion of the slot 21. This flame will ignite the air and gas mixture and the flame will rapidly be propagated upwardly along the slot 28 to the upper end of the main fuel duct 6, whereupon the burner will be again in operation. The channel 30 is so formed that a considerable quantity of fuel will flow upwardly along the slot 28 so that flame from the lower end of the slot 21 will pass rapidly to the upper edge of the duct 6. When thecombustible mixture of gas and air in the pilot burner reaches the upper end of the flame guide tube 19 of the pilot burner, this combustible mixture will, of course, be ignited from the flame maintained at the slot 21.

It will be obvious from the foregoing that when a flareback occurs, the gas discharged from the burner will be instantly relighted, since the time required for fuel and flame from the lower end of the slot 21 to pass upward-1y to the upper end of the pilot flame guide tube 19, and then to the gas discharged from the main duct'6 will obviously be considerably greater than the time required to light a current of gas passing from the lower end of the slot 28 of the main duct 6 to the slot 21 of the pilot burner. Flame is propagated or spread at a much faster rate of speed than the flow of gaseous fuel, and conse quently, flame will reach the upper end of .theslot 28 at approximately the same time or very slightly after the fuel reaches the upper end of the duct 6. It has, consc quently, been found that by'means of the improvement herein described, re-ignition after a flareback is accomplished so quickly that no explosion or even a popping noise occurs when re-ignition takes place, due to the fact that the fuel discharged from the main duct 6 is ignited so quickly that no accumulation of fuel in the combustion chamber takes place before ignition.

In pilot burners as heretofore constructed in which a slot was provided in the side of the pilot burner tube and so located that the lower end of this slot would be below the zone of flaring gases, there was also the hazard that particles of scale, rust or other material might lodge in the pilot burner for example, on thepin 25, in position to partly obstruct the slot 21 and prevent the flame from spreading upwardly to the point of ignition of fuel flowing from the main fuel duct 6. Under these conditions, the entire furnace might be filled with a combustible'mixture before being ignited by the flame maintained at the lower portionof-the slot or opening in the side of' the pilot burner. This condition might. readily, result in an explosion which could damage, the furnace or parts thereof.

. By-means of the construction described, it will be obvious that even if suchobstruction'of the pilot burner occurs, the fuel discharged from the fuel duct 6 will still be quickly ignited by the flame at the lower end of the slot 21.

It will be understood that various changes in the details, materials, and arrangements of parts which have been herein described; and illustrated in order. to explain the nature of the invention, may be made by those skilled in the art within the principle and sco'peof the invention, .as expressed in the appended claims. 4

I claim as my invention: 1 p '1 1. A-gas burner. for re-igniting' the 'fuelafteriflareback of burnt gas during the ignitionof the burner, said iburner including'a main fuel duct having a fuel discharge outlet, a pilot burner tube located adjacent to said main fuel duct and terminating at its upper cm above said discharge outlet of said main fuel duct, said main fuel duct having a slot in a side thereof extending from said outlet substantially lengthwise thereof and adjacent to said pilot burner tube, said pilot burner tube having an opening in the side thereof through which fuel is discharged to maintain a flame, said opening extending below the lower end of said slot in said main burner duct and adjacent said slot whereby gas flowing from said slot will pass by said opening, and gas deflecting means in said main fuel duct for deflecting some of the fuel flowing therein outwardly toward said opening in said pilot tube through said slot and in igniting relation thereto, said deflecting means including a channel-shaped member secured to the interior of the main duct and having the open side thereof extending across said slot, said channel being open at the lower end thereof and having a deflector at the upper end thereof for deflecting fuel from said channel through said slot.

2. A gas burner construction for re-igniting the fuel after a flareback of burnt gas during the ignition of the burner, said burner including a main fuel duct having a fuel discharge outlet, a pilot burner tube located adjacent to said main fuel duct and terminating at its upper end above said discharge outlet of said main fuel duct, said main fuel duct having a slot in a side thereof extending from said outlet substantially lengthwise thereof and adjacent to said pilot burner tube, said pilot burner tube having an opening in the side thereof through which fuel is discharged to maintain a flame, said opening extending below the lower end of said slot in said main burner duct and adjacent said slot whereby gas flowing from said slot will pass by said opening, and gas deflecting means in said main fuel duct for deflecting some of the fuel flowing therein outwardly toward said opening in said pilot tube through said slot and in igniting relation thereto, said deflecting means including a channel-shaped member secured to the interior of the main duct and having the open side thereof extending across said slot, said channel being open at the lower end thereof and having a deflector at the upper end thereof which partially closes said upper end and slopes downwardly toward said slot and spaced from said slot for deflecting fuel from said channel outwardly through said slot.

References Cited in the file of this patent UNITED STATES PATENTS 951,724 Cole Mar. 8, 1910 2,101,393 Herbster Dec. 7, 1937 2,110,217 Gardner et a1 Mar. 8, 1938 2,365,102 Olds Dec. 12, 1944 2,728,384 Anderson Dec. 27, 1955