US1937974A - Burner - Google Patents

Description

G. W. McKEE BURNER Filed Dec. 26, 1951 2 Sheets-Sheet l.

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G. W. MOKEE BURNER Filed DeG. 26, 1951 2 Sheets-Sheet 2 Il Illl ll ll ll Il Il li Il Il Il ll Il Patented Dec. 5, 1933 BURNER Garnet W. McKee, Rockford, lll.

Application December 26, 1931 Serial No.'583,305

s claims. (c1. 15a-119) v The present invention relates generally to gas burners for use in hot air furnaces, enamelling ovens, solution heating furnaces, core baking ovens, metal melting furnaces and like heating apparatus. More particularly the invention relates to that type of gas burner which is known as an atmospheric burner and comprises (1) a hollow burner head which embodies an inlet opening in the bottom portion thereof and is provided with a plurality of discharge ports; (2) an injecting tube which is of the Venturi type and is connected at one of its ends to the inlet opening of the burner head; (3) a nozzle which is connected by a pipe to receive gas under pressure, and is positioned centrally with respect to the other end of the injecting tube and so that the gas is discharged through the tube in jet form and passes to the burner head for discharge via the ports; (4) a valve which lis connected to the gas supply pipe and is adapted to control the flow of gas to the nozzle; and (5) a device which is controlled by a heat responsive element and operates automatically to close the valve when a predetermined temperature is reached.

In burners of this type, the end of the injecting tube to which the nozzle is applied is open to atmosphere and the gas which is discharged by the nozzle in jet form through the tube entrains from the atmosphere a portion of the air which is required for the complete combustion of the gas. This air mixes with the gas as the latter flows through the injecting tube and is known as .primary air. After passing through the lnjecting tube, the gas, together with the primary air, flows into the burner head and is then discharged through the ports in the head. Immediately upon discharge from' supplied from the atmosphere surrounding the burner with such additional air as is necessary to support combustion and, after being. ignited, burns.

In practice it has been found that an atmospheric burner of the high-low variety, that is, one in which a by-pass or leak port is utilized for supplying a limited quantity of gas to the burner head after closing of the valve by the automatic control device so that the burner burns at a low capacity, has many advantages over, and is more efficient in operation than, a burner of the on-and-ofi type wherein the gas is completely shut of when the device is actuated to close the valve and a pilot light is used to reignite the gas after the valve is again opened. Although exceedingly efficient in operation, an atmospheric burner of the high-low variety has proved in most linstances to be impractical for the reason that back firing or flash-back occurs when the burner is turned down to low or minimum capacity. This back firing or hash-back is attributable to the fact that the stream of primary air the ports, the gas is y entering the injecting tube has considerable momentum and for this reason, continues at sub-7 stantially the same rate of flow for a certain period of time after shift of the valve into its closed position by the device with the result that there is suilicient air in the tube to form an explosive mixture with the limited quantity of gas supplied by the by-pass or leak port. When this mixture reaches the ports in the burner head .where combustion is taking place, a sharp explosion occurs in the burner head inasmuch as' rthe rate of flame propagation in such a mixture far exceeds the rate of flow.

One object of the present invention is to provide an atmospheric burner of the high-low type which is an improvement upon previously designed burners of like character in that it embodies simple and eilicient means for preventing back firing or ash-back when the valve is shifted by the device to its closed position in order to turn down the burner to low capacity. In general, this means consists of a flap valve which is designed to close the throat or inlet end of the injecting tube so as to cut off the ow `of primary air into the tube, and is connected to the valvecontrolling device so that it is shifted into its operative position slightly 'before closing of the valve by the device. During operation of the burner at high or maximum capacity, the flap valve is in its inoperative position and consequently the inlet end of the tube is open so that there is no restriction to the volume of the primary air which is entrained by the gas. the valve-controlling device is actuated so that it operates to close the valve in order to turn down the burner to low or minimum capacity, the flap valve is shifted into its operative position wherein itl closes the inlet end of the injecting tube and thus cuts off the flow of primary airY so as to preclude in the tube the formation of a combustible mixture which would explode upon reaching the burner head.

When- Another object of the invention is to provide an atmospheric burner of the character under consideration in which the nap valve embodies a damper-controlled opening for admitting into the injecting tube a sufficient quantity of primary air for the gas entering the tube when the valve is in its closed position and the burner a low or minimum capacity,

A further object of the invention is to provide an atmospheric burner of the high-low type in which the injecting tube is surrounded by a tubular jacket for supplying air around the burner head for combustion purposes, and the nap valve is extended and shaped so as to ciose the jacket and cut off the supply of air to the burner head when the valve-controlling device is actuated to turn the burner down to its low or, minirzium Capaitl.

A still further object of the invention is to supply a burner of the last mentioned character in which the flap valve' is provided in the jacket closing portion with a damper-controlled opening I fthe top of the head is for admitting into the jacket the necessary quantity of air to eiect complete combustion of the gas while the burner is operating at low capacity.

In addition, it is contemplated as one of the objects of the invention to provide an atmospheric burner of the high-low type which is generally of new and improved construction and is exceedingly ecient in operation.

Other objects of the invention and the various advantages and characteristics of the present burner construction will be apparent from a consideration of the following detailed description.

The invention consists in the several novel features which are hereinafter set forth and are more particularly defined by the claims at the conclusion hereof.

In the drawings which accompany and form a part of this specification or disclosure and in which like numerals of reference denote corresponding parts throughout the several views:

Figure 1 is a vertical longitudinal section of a burner embodying the invention, showing the iiap valve in its inoperative position, that is, the

. position in which it is disposed when the valve is opened and the burner is operating at high, or maximum capacity;

Figure 2 is an enlarged vertical longitudinal section of the nozzle and of the burner showing flap valve in its closed position wherein it serves to cut oli the supply of primary air to the injecting tube when the valve is closed by the lautomatic control device and the burner is burning at low or minimum capacity; and

Figure 3 is an end view of the burner.

The burner which forms the subject matter of the invention is designed to burn gas and is adapted for use in connection with furnaces, ovens and like heating apparatus. It isessentially an atmospheric gas burner and comprises a hollow burner head 4, an injecting tube 5 and a nozzle 6.

'Ihe burner head 4 is formed of cast metal and embodies an inlet 7 at the bottom thereof and an annular series of ports 8 in its side wall. The closed by means of a disk-like plate 9. The latter is secured place by means of a bolt 10 and is of such size that the margin thereof projects beyond the'side wall of the head and forms a baie over the ports 8.

The injecting tube 5 is of the Venturi type and extends horizontally. The throat or inlet end of the tube is open to atmosphere. The discharge end of the tube is connected to the burner head by means of a pipe 11 and an elbow 12. The pipe 11 extends vertically and is secured to and depends from the inlet 7 at the bottom of the burner head. The elbow 12 extends between and is connected to the pipe 11 and the discharge end of the injecting tube and embodies a supporting member 13. This member is flat on the bottom thereof and supports the elbow 12 so that the pipe 11 is held in a vertical position.

The nozzle 6 is positioned centrally with re-A bodies a gas connection 18 and is provided at one end thereof with a screw thread 19 whereby it is connected to the throat or inlet end of the injecting tube. The other end of the bodyis slightly enlarged and forms a mouth whereby air is admitted to the injecting tube. The gas connection 18 is formed integrally with and extends transversely through the body. The outer end of the connection is connected to the gas supply pipe 14 by means of a screw thread 20. The inner end of the connection terminates adjacent the central portion of the casing and embodies an opening 2l in which the nozzle 6 is disposed. The nozzle receives gas from the pipe 14 by way of the gas connection 18 of the mixer body 16 and discharges the gas in jet form into the throat or inlet end of the injecting tube 5. The adjusting pin 17 extends longitudinally of the body 16 and projects through the inner end of the gas connection 18. One end of the pin is provided with a needle point 17a which ts within and controls the orifice in the nozzle 6. The other end of the pin extends through a boss 18a on the connection and is connected tothe boss by a screw thread so that the needle point may be adjusted longitudinally of the nozzle by rotating the pin. The supply of gas to the nozzle is controlled by means of a valve 22 in the pipe 14. When the valve is open, gas flows through the pipe to the nozzle and is discharged into the injecting tube in the form of a jet, as previously pointed out. As the jet of gas flows through the tube, it entrains from the atmosphere surrounding the mouth end of the mixer body 16, a portion of the air which is required for the complete combustion of the gas. This air constitutes the primary air supply and mixes with the gas in the injecting tube. From the injecting tube, the gas, together with the primary air, flows through the elbow 12 and the pipe 11 to the burner head 4 from whence it is discharged through the ports 8. Immediately upon discharge from the ports, the gas is supplied from the atmosphere around 'the burner head with such additional air as is necessary to support combustion and, after being ignited, burns. The air which is supplied to the mixture of gas and primary air emanating from the ports 8 from the atmosphere around the burner head, constitutes the secondary air and is furnished by means of a jacket 23. The latter is tubular in design and consists of a horizontally extending part 24 and a vertically extending part 25. The part 24 is rectangular in cross section and surrounds the injecting tube 5 and the elbow 12. It is formed of plate or cast metal andconsists of a top wall 24B. a bottom wall 24b and side walls 24C. One end of the jacket part 24 is open and is arranged so that it is ush with the mouth end of the mixer body 16. The other end of the jacket part 24 is closed by an end wall 24d. 'I'he top wall 2aa is provided with a circular opening 24e above the elbow 12 and embodies an aperture 24fabove and in alignment with the gas connection 18 for accommodating the. discharge end of the gas supply pipe 14. The jacket part 25 is cylindrical and extends around the vertical pipe 11. The lower end of the part 25 ts within the circular opening 24e in the top wall of the jacket part 24 and is provided with an outwardly extending marginal flange 25a. The latter rests upon the top Wall 24a and forms a support for the jacket part 25. The upper end of the jacket part terminates beneath the burner head 4 so that the air passing through the jacket from the open end of the jacket part 24 is discharged around the head.

ics l narrativi Ordinarily, about six parts of` air are required to eilect complete ycombustion of one part of gas.) Undernormal operation of the burner, the'streamv of gas which is jetted into the injecting tube 5 by' the nozzle 6 -entrains less than one-half of the amount of air necessary for complete combustion and the mixture of gas and primary air within the injecting tube is non-combustible.A When the non-combustible mixture of gas'and primary air is discharged from the burner head by the ports 8, the additional air required for complete combustion of thegas is obtained from the air which is .delivered or supplied around the burner head by the jacket 23.

The burner is controlled automatically by means of a devic'e 26. vThe latter comprises a housing 27 and an electric motor 28, and operates to open and close the valve 22. The housing 27 is positioned above the casing of the valve and supports ashaft 29. The latter is driven by means of suitable gearing from the electric motor 28 and embodies a cam.30 which acts on the stem of the valve and is adapted, when rotated in one direction, to close the valve, and when rotated-in the opposite direction, to release the valve stem so that the valve may be shifted by a spring or like instrumentality intol its open position. The electric motor 28 is supplied with current by a pair of conductors 31 and is of the reversible type so that it may be driven in one direction or theother. It is controlled by means of a thermostat 32 which is located in the space that is heated by the burner, and operates, by means of wires 33, to control switch mechanism for the motor. Whena predetermined temperature is reached, a circuit is established whereby the motor is driven so as to close the valve 22 and thus shut oil the supply of gas to the nozzle 6. When the temperature falls beneath a pre` determined point, the vthermostat operates to complete a circuit whereby the motor is driven in a reverse direction and results in opening of thevalve 22. In order to supply a limited quantity of gas to the nozzle so that the burner operates at low or minimum capacity when the valve 22 is closed by the device 27, a by-pass 34 is provided. This by-pass consists of piping which extends between the inlet side of the valve 22 and the end of the pipe 14 which-is connected to the gas connection 18 of the mixer 15. In order to establish definitely the quantity of gas supplied by .the`

by-pass when the valve is inAits closed position, a fixed orice 35 is included in the ny-pass piping. When the valve 22 is closed by the device 26, the by-pass permits of the ow of a small quantity of gas to the nozzle 6 with the'result that the burner burns at low or minimum capacity.

In practice it has been found that when the device 26 closes the valve 22 in response to action of the.thermostat 32, back firing or flash-back occurs in the burner head 4. This, as previously pointed out, is attributable to the fact that the stream of primary air entering the injecting tube via the mixing device15 has considerable mo"- mentum and for this reason, continues at substantially the same rate of iiow fora certain period of time after closing of the-valve 22, with l burner head where combustion is taking place,

the result that there is sufficient air in the tube to form an'explosive mixture with th gas that is supplied by way of the by-pass 34. When this explosive mixture reaches the ports 8 in the an explosion occurs. In order to prevent the back firing' or flash-back, a flap valve 36 is provided. This valve is associated with the nozzle end of the burner and is preferably formed of a rectangular piece of plate metal., It is Supported by means of a pair of ears 3 7 so that it may be swimg downwardly from an inoperative into an operative position wherein it extends vertically and ts against the vmouth endof the mixer body 16. In its operative positio thedlap valve closes the mixer body and thus cuts oifthe' supply of primary air-to the injecting tube. 'The ears 37` are secured to, and project upwardly from, the side walls ,24 of thehorizontal part 24 of the jacket 23 and support a pivot shaft 38.

The latter is secured to a pair of lugs on the nap operates with the earsto form the for the valve. Swinging of the and out ofits operative position, means of a lever 39. This lever valve and pivotal support iia'p valve into is effected by is positioned at one side. of the housing 27 of the valve-controlling device 26 and has one end` thereof'connected to the casing bymeans of a pivot stud 40. The other or distal end of the through the medium of theniemberl 43. The' asf member 43 is'so constructed and arranged that the lever 39 is lowered ini order to swing the ilap valve into its operative position slightly before the cam on the shaft 28 closes the valve 22. As

a result of this arrangement, the flap valve is swung into its closed position and cuts oi the supply of primary air to the injecting tube slightly before the valve 22 is closed so as to turn down the burner. By cutting off the supply of primary air in this manner, no explosive mixturel can form in the injecting tube and back firing or flash-back is eectively avoided. When the valve 22 is opened in response to operation of the controlling device 26, the member 43 on the shaft 29 raises the lever 39 and thus swings the ilap valve into its inoperative position. In such position of the flap valve, the throat or inlet `end of the injecting tube is open to atmosphere so that the stream of gas from the nozzle can 'entrain primary air. When the fiapvalve is in its operative or closed position and the burner is operating at low or minimum capacity, ak small amount of primary air is needed for 4the gas which is supplied to the nozzle by the by-pass 34. In view of this fact, a pair of openings 44 are formed in the flap valve. controlled by a damper 45 and permit entry into the tube 5 of such a quantity of primary air as is necessary when the burner is burning at low capacity. The damper 45 is in the form of a disk 'which is rotatably mounted on the front of the flap valve and has openings. therein for registry with the openings 44. By rotating the damper, the openings 44 may be controlled so as to-admit into the injecting tube the desired quantity of primary air.

In order to cut down the supply of secondary air to the burner head when the burner is turned down to low capacity as aresult of closing of the valve 22, the flap valve 36 is extended so as to close .the end of the jacket part 24 which surrounds the mixer 15. As a result of this arrangement, the jacket 23 is closed so as to curtail 'the supply of secondary air to the burner head when the'valve 22 is closed by the device 26.

These openings are I portionl of the iiap valve which closesthe l,jacket part 24. These'holes are controlled by means of a damper 47 of the rotatable disk type so that the amount of secondary air supplied to the burner during burning of the burner at low capacity may be adjusted to a nicety.

, The operation of the burner is as follows:

When the valve 22 is in its opened position, gas in maximum quantity is supplied to the nozzle which discharges the gas into the injecting tube in jet form. The stream or jet or gas entering the injecting tube entrains primary air from the atmosphere around the mixer 15 and flows tothe burner head from which it is discharged through the ports 8. Upon discharge from the burner head, the gas receives from the atmosphere surrounding the burner head, a sufficient amount of additional air to form a combustible mixture, and burns. While the valve 22 is open, the burner burns at high or maximum capacity. When the temperature of the space that is heated by the burner reaches a predeermined point, the device 26 operates to close the/valve 22. This results in the burner being turned down to its low or minimum capacity. Slightly before closing of the valve 22, the device 26 operates through the medium of the lever 39 and the chain 41 to swing the flap valve 36 into its operative position. In this position of the flap valve, the 'supply of primary air to the injecting tube is restricted so that there is no likelihood of backl ring or flash-back taking place in the burner head. When the flap valve is swung into its operative position by the device 26 to restrict the iiow of primary air to the injecting tube, it also closes the intake end of the jacket 23 and thus restricts or cuts off the flow of secondary air to the burner head 4. When the temperature drops to a predetermined point, the valve 22 is opened by the device 26. During opening of the valve, the lever 39 swings the flap valve 36 into its inoperative position wherein the throat or inlet end of the injecting tube is open io atmosphere and the intake end of the jacket is uncovered. l

By adjusting the dampers gi5 and 47, the amount of primary and secondary air admitted to the burner while the ap valve. is in its operative position, may be controlled.

The herein described burner may be manufactured at a comparatively low cost and is extremely efiicient in operation by virtue of the fact that it embodies simple means for preventing back firing or iiash-back upon closing of the valve in the gas supply pipe. I

Whereas the'invention. has been described as having special utility in connection with an atmospheric burner of the high-low variety, it is to be understood that it may be employed advantageously in connection with' atmospheric burners of the on-and-off type. It is also to be unders'ood that the invention is not to be restricted to the details set forth, since these may be modified within the scope of the appended claims, without departing from the spirit and scope of the invention. l

Having thus described the invention, what vI claim as new and' desire to secure by Letters Patent, is:

1. In an atmospheric burner, the combination of a burner head, an injecting tube of the Venturi type having one" end thereof connected to the head and provided at its other end with a mouthpart open to atmosphere, a nozzle adjacent said mouth-part connected to receive gas under pressure and arranged to direct the gas into the tube so that it flows to the burner head and entrains into the tube a part ofthe air required for combustion of the gas, a valve for controlling the sup.y

ply of gas to the nozzle, a valve applied directly to the mouth-part of the tube and arranged so that upon shift thereof into its closed position it immediately shuts off the flow of air into the tube,

and means whereby the air valve is automatically closed in conjunction with, but slightly before, shift of the gas valve into its closed position in order to shut off the iiow of air into the tube prior to stoppage of the gas from the nozzle and thus prevent back firing.

2. In an atmospheric burner, the combination lof a burner head, an injecting tube of the Venturi i type having one end thereof connected to the head and provided at its other end with a mouthv part open to atmosphere, a nozzle adjacent said mouth-part connected toy receive gas under pressure and arranged to direct the gas into the tube so that it flows to the burner` head and entrains into the tubea part of the air required for combustion of the gas, a valve for controlling the supply of gas to the nozzle, a thermo'statically controlled, motor driven device for automatically closing the valve when the space heated by the burner reaches a predetermined temperature, a

valve applied directly to said mouth-part of the tube and arranged sol that upon shift thereof into its closed position, it immediately shuts olf the flow of air into the tube, and means operated by the device for closing the air valve slightly before closing of the gas valve in order to shut off the ow of air into the tube prior to stoppage of the gas from the ynozzle and thus prevent back firing.

3. In an atmospheric` burner of the character described, the combination of a burner head, an

injecting tube having one end thereof connected to the head and its other end open to atmosphere, a nozzle atthe said other end of the tube connected to receive gas under pressure and arranged to direct the gas into the tube so that it flows to the burner head and entrains into the tube a part of the air required for combustion of the gas, a valve for controlling the supply of gas to the nozzle, means for supplying a limited quantity of gas to the nozzle when the valve is in its closed position, a valve for controlling the flow of air into the tube, means for automatically closing the air valve upon shift of the gas valve into its closed position in order to restrict the ilo-w of air into the tube and thus prevent back firing, and meansy for admitting into the tube a limited quantity of air when the air valve is in its closed position for admixture with the gas supplied to the nozzle by the Asupply means.

4, In an atmospheric burner of the character described, the combination of a burner head, an injecting tube having one end thereof connected to the head and its other end open to atmosphere,

a nozzle at the said other end of the tube connected to receive gas under pressure and arranged in response to shift of the gas valve into its closed position by the device, for closing the air valve in l5@ order to restrict the ow of air'into the tube and thus prevent backv firing, and means for. admitting into the tube a limited quantity cti air when the air valve is in its closed position for admiX- ture with the gas supplied to the nozzle bythe supply means.

5. In an atmospheric burner of the character described, the combination of a burner head, an injecting tube having one end thereof connected to the head and its other end open to atmosphere, a nozzle at the said other end of the tube connected to receive gas under pressure and ar ranged to direct the gas into the tube so that it ows to the burner head and entrains into the tube a part of the air required for combustion of the gas, and a flap valve for controlling the flow of air into the tube supported by a hinge connect-ion so that it may be swung into and out of a closed position wherein it serves to close the said other end of the tube, said ap valve having a damper-controlled opening therein for admitting a limited quantity of air into the tube when the valve is in its closed position.

6. In an atmospheric burner of the character described, the combination of a burner head, an injecting tube having one end thereof connected to the head and its other end open to atmosphere, a nozzle at the said other end of the tube connectedto receive gas under pressure and arranged to direct the gas into the tube so that it ows to the burner head and entrains into the tube a part of the air required for combustion of the gas, a tubular jacket for supplying around the burner head the remainder of the air required for combustion, and arlap valve for controlling the supply of air through the jacket to the burner head supported by a pivot connection so that itmay be swung into and out of an operative position wherein it serves to close the jacket, said flap valve having a damper-controlled opening therein lfor admitting a small quantity of. air into the jacket when the ap valve is' in its operative position. y

7. In an atmospheric'burner of the character described, the combination of a burner head, an *'mjecting tube having one end thereof connected to the head and its other end open to atmosphere, a nozzle at the said other end `oi' the tube connected to receive gas under pressure and arranged to direct the gas into the tube so that it flows to the burner head and entrains into the tube a part of the air required for combustion of the gas, a valve 4for controlling the supply of gas to the nozzle, a tubular jacket for supplying to the burner head the remainder of the air required for combustion, extending around the tube and arranged so that the inlet endv thereof is substantially flush with the said other end of the tube, and a ap valve supported by a hinge from the jacket and arranged so that it may be swung into and out of a fully closed position wherein it extends across the said other end of the tube and the inlet end of the jacket and cuts oil the flow of air into the tube andthe ow of air through the jacket to the burner head.

8. In an atmospheric burner of thecharacter described, the combination of a burner head, an injecting tube having one end thereof vconnected to the head and its other end open toatmosfphere, a nozzle at the said other end .of the tube connected to receive gas under pressure and arranged to direct the gas into the tube so that it flows to the burner head and entrains into the tube a part of thetair required for combustion of the gas, a valve for controlling the supply of gas to the nozzle, anda device for'automatically.

`closing the valve when the space heated by the burner reaches avpredetermined temperature, a tubular jacket for supplying to the burner head the remainder of the air required for combustion, extending around the tube and arranged so that the inlet end thereof is substantially iiush with 'the said other end of the tube, a iap valve suptive automatically in response to 4shift of the gas valve into `its closed position by the device for swinging the flap valve into its operative position.

GARNET W. MCKEE.

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