US3145764A

US3145764A - Gaseous fuel burner and control therefor

Info

Publication number: US3145764A
Application number: US130434A
Authority: US
Inventors: John M Rackley
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1961-08-09
Filing date: 1961-08-09
Publication date: 1964-08-25
Anticipated expiration: 1981-08-25
Also published as: DE1401852A1

Description

g- 1964 J. M. RACKLEY 3,145,764 GASEOUS FUEL BURNER AND CONTROL THEREFOR Filed Aug. 9, 1961 3 Sheets-Sheet l O 7 18C 10 13A 17; 11/0 FIG. 1 5A +3 L 10 F|G.3

19 17/ { 18C 17A 17c 18C' 16 2 INVENTOR. 17 John M. Rackley ATTORNEY Aug. 25, 1964 J. M. RACKLEY 3,145,764

GASEOUS FUEL BURNER AND CONTROL THEREFOR Filed Aug. 9, 1961 3 Sheets-Sheet 2 FIG. 6

IN V EN TOR.

130 John M. Rackley 118 116D ATTORNEY s- 5, 9 J. M. RACKLEY 3,145,764

GASEOUS FUEL BURNER AND CONTROL THEREFOR Filed Aug. 9, 1961 3 Sheets-Sheet 3 INVENTOR. John M. Rackley AT TORNEY United States Patent 3,145,764 GASEOUS FUEL BURNER AND CQNTROL THEREFOR John M. Rackley, Alliance, Ohio, assignor to The Bahcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Aug. 9, 1961, Ser. No. 130,434 Claims. (Cl. 153-125) This invention relates in general to the burner art and more particularly to an improved burner construction and a means for igniting and monitoring the flame of a burner.

Chemical recovery boilers, as for example boilers commonly referred to in the art as black liquor units of the type disclosed in US. Patent 2,416,462, generally include a furnace construction having tiers of relatively small air ports extending through the furnace walls for for admitting combustion air to the furnace at different elevations for supporting the combustion of a residual liquor resulting from a chemical process. The present practice, in the operation of such boilers, frequently requires firing of auxiliary burners through certain of the air ports, during start-up, or for stabilizing the firing within the furnace, or for controlling localized black outs of the fuel bed within the furnace.

Heretofore, the auxiliary firing of such chemical recovery units was attained preferably by inserting a gas spud into the furnace through one of these air ports. Generally the gas spuds were introduced through either the primary or the secondary air ports whenever their use was required. Not infrequently the auxiliary gas spuds were fired through the tertiary air port to facilitate carrying the load of the unit or to complete combustion of the gases rising from the fuel bed. Regardless of which ports the auxiliary gas spuds were inserted into, except during start-up periods, the gases issuing from the gas spuds were ignited either by the radiant heat and/ or the hot gases present within the furnace.

It has been recognized that the method of firing whereby a gas spud is inserted into a furnace through an air port is unreliable and may be very dangerous. It many instances the air velocity through the port is greatly in excess of the flame propagation rate due to the size of the air port in relation to the quantity of air required to completely burn the fuel (normally to ZSMK B.t.u. per hour) introduced through the spud inserted therethrough. As a result, the flame may be initiated as much as 2 feet from the point of emission of the gaseous fuel from the spud.

Mishaps resulting in both loss of life and excessive boiler damage due to explosions have been known to occur as a result of this practice. Also it has been noted that pluggage of the auxiliary gas spuds from falling char and running smelt have created additional igniting and mechanical difliculties during the firing of such auxiliary gas spuds, particularly when such spuds were fired in the area of the primary air ports.

Therefore, an object of this invention is to provide an improved burner construction that is particularly applicable for the auxiliary firing of a chemical recovery unit, through an air port thereof during start-up, or during unstable firing of the furnace, or during black out of the fuel bed within the furnace, or to carry the load with increased safety and reliability.

Another object of this invention is to provide a burner construction adapted to fire through an air port in the furnace wall of a chemical recovery boiler in a manner so as to protect the burner from contamination by the smelt or liquor within the furnace.

Still another object is to provide an improved burner construction having its own reliable ignition source.

Patented Aug. 25, 1964- Another object of the invention is to provide a burner construction in which a low velocity, excess air zone is maintained therein so as to obtain a continuous flame.

Still another object is to provide a burner construction that is readily applicable for use either in existing or future chemical recovery units, as well as in furnace constructions of general utility.

Another troublesome problem encountered with burners, and particularly with burners employed in the auxiliary firing of a chemical recovery unit, is that of detecting and verifying with certainty the presence or absence of a flame at the burner tip. Heretofore, ultra violet detectors or infra red detectors have been utilized to detect the presence or absence of a burner flame. However, each of these detector types is subject to false indications caused by incorrect sighting, poor sensitivity or some other extraneous influence, such as radiating refractory. For example, the highly variable flow patterns within the furnace makes sighting of an ultra violet or infra red detector very difficult. Also an ultra violet detector, when applied .to black liquor units is unreliable because the flame and smoke resulting from the com bustion of liquor within the unit tend to block and absorb the ultra violet rays.

Therefore another object of this invention is to provide a system for insuring positive ignition of a burner flame, and thereafter positively monitoring the flame.

Still another object is to provide an igniting and flame detecting system that includes a spark ignitor arranged in an electrical circuit whereby the spark ignitor functions as the means for initially igniting the fuel mixture of the burner, and also as the means for detecting the presence or absence of such flame after ignition of the fueland air mixture.

In accordance with this invention, an improved system for insuring positive ignition and subsequent monitoring of the burner flame is attained by disposing a pair of electrodes in igniting relationship to the fuel and air mixture of the burner, and in flame impinging relationship with the flame of the burner after ignition of the fuel so that the electrodes function both as a spark ignitor and a flame detector. To accomplish this the electrodes are connected in an electrical circuit which includes means for energizing the electrodes to produce a spark therebetween, a flame detector in parallel with the energizing means for sensing the presence of a flame impinging on the electrode, and a switch for connecting the electrode to either the flame detector or the energizing means.

The operation of the flame detecting system of this invention is based on the principle that when combustion occurs, the gases generated are ionized, and thus capable of passing a current of electricity. With electrodes of appreciable size difference placed in this ionized gas and an alternating current imposed across the electrodes, current will flow more readily in one direction than the other. Thus-in essence, the ionized gases act as a rectifier and the alternating current imposed across the terminals of the electrodes, which are disposed in impinging relationship with the burner flame, is rectified to direct current. The sensing device connected to the electrode in accordance with the invention is operated by direct current only, and thus will sense any combustion occurring at the burner. Any short circulating of the electrodes, or

lack of flame at the burner will impose an alternating current upon the sensing device, and cause it to fail safe.

A feature of the invention resides in the provision that the electrodes have a dual function in that they act as an ignitor and as a flame sensing means.

Another feature of the flame igniting and detecting system of this invention resides in the provision of a means for isolating the electrode from the secondary winding of a transformer to positively prevent the high voltages present during spark ignition from entering the flame detecting device and causing injury to its components.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 illustrates a sectional side view of the improved gas burner construction as applied to an air port of a furnace chamber of a chemical recovery boiler.

FIG. 2 is a sectional plan view of the burner taken along line 22 of FIG. 1.

FIG. 3 is a sectional end view of the burner taken along line 33 of FIG. 1.

FIG. 4 is a sectional side view of a modified burner assembly.

FIG. 5 is a right end view of the burner assembly of FIG. 4 with portions thereof broken away.

FIG. 6 is a plan view of the modified burner of FIG. 5.

FIG. 7 is a schematic diagram of the electrical circuit of the igniting and flame detecting system utilized in conjunction with a suitable burner means, and which system is illustrated in its completely de-energized position.

While the burner construction illustrated in FIGS. 1 to 3 may be utilized as a general purpose burner, for description purposes reference will be made to its particular application in a chemical recovery boiler. Referring to FIGS. 1 to 3, there is shown a fragmentary portion of a furnace chamber 10 of a chemical recovery unit having a wall portion thereof defined by a row of furnace upright wall tubes or fluid cooling tubes 11. The furnace construction of chemical recovery units as disclosed in US. Patent 2,416,462 have certain of the wall tubes 11 laterally bent or otherwise displaced to define therebetween air openings or ports 12. A plurality of such openings are usually spaced in rows extending transversely of the furnace chamber 10, with a plurality of rows vertically spaced to define rows of primary, secondary, and tertiary air ports 12. Generally, a casing 13 is spaced from the outer side of furnace wall tubes 11 to form therewith a windbox or air duct 14, connecting with a suitable source of air supply, and through which combustion air is directed to the respective air ports 12. In chemical recovery units these air openings or ports 12 have a relatively small area, e.g. about 2" wide by 13" high.

In accordance with this invention an improved burner assembly 15 is provided to facilitate the auxiliary firing of such chemical recovery units, during start-up, or during conditions of unstable firing within the furnace, or during localized black outs of the fuel bed within the furnace, or to carry the load with safety and reliability. The burner assembly illustrated is constructed and arranged so as to have an output ranging from 3 to 25 million B.t.u.s per hour. This burner construction basically comprises two sections, the main burner 15A at the forward end of the burner assembly, and the constant burning ignitor or pilot section 15B positioned at the rear of the burner assembly, the latter being disposed in igniting relationship to the main burner 15A.

As shown, the burner assembly 15 is fitted through an appropriate opening 13A in the windbox casing 13 so as to be in alignment with an air port 12. The main burner portion 15A of the assembly 15 comprises essentially an endless manifold 16 which defines a fuel-air mixing chamber 30, the manifold being disposed immediately behind the furnace wall tubes 11 and in alignment with the air port 12 defined therein. In the illustrated embodiment FIG. 3, the manifold 16 is defined by spaced inner and

outer conduit walls

17, 18 having rectangularly disposed top 17A, 18A, bottom 17B, 18B and connecting

side walls

17C, 18C respectively, to define therebetween an endless gas receiving chamber 19, the ends of which are closed 1 by

suitable end walls

20, 21. Raw gas is supplied to the manifold 16 through a suitable gas supply conduit 22 which connects with a main gas supply line 23 that in turn connects to a gas supply. Suitably disposed in the gas conduit ahead of the manifold 16 is a solenoid operated gas valve 24 for controlling the gas flow to the burner.

As shown in FIGS. 1 to 3, the opposed side walls 17C of the manifolds inner conduit wall 17 have drilled therethrough a plurality of gas discharge orifices 25. Preferably, the orifices 25 are arrayed in a triangular pattern positioned at the center of the manifold with the apex disposed adjacent the air entrance 26 to the chamber 30 defined by the manifold, and the base of the triangular pattern disposed adjacent the furnace side 27 of the manifold. Drilling of the orifices 25 in the triangular pattern, as described allows for the gradual admission of the raw gas into the stream of air and combustion products flowing through mixing chamber 30. With the construction of the manifold as described, it will be recognized that the velocity of a fluid flow through the mixing chamber 30 defined thereby is lowest at the walls. By concentrating the discharge of the gas at the center of the manifold, high excess air zones are obtained in the low velocity areas at the top and bottom of the chamber 30 circumscribed by manifolds and combustion is thus stabilized.

The rear or pilot burner section 15B of the assembly is connected to the rear end 21 of the manifold 16 in igniting relationship to the fuel and air mixture within the chamber 30 by means of a bracket or casing 28. As shown in FIGS. 1 and 2, the bracket 28 is illustrated as a C-shaped member having its leg portions 23A connected to the rear end wall 21 of the manifold 16. The web portion 28B of the bracket 28 is spaced from the rear end of the manifold and defines therewith side openings 29 through which air from the surrounding windbox 14 is directed to the rear end 26 of the manifold 16 to mix with the gases issuing from the orifices 25 to form a fuel-air mixture within the chamber area 30 defined by conduit 17.

The web 28B of the bracket is provided with a central opening or aperture 280 which is disposed in alignment with the manifold 16. Extending rearwardly of the aperture 28C in alignment therewith is a tubular sleeve 31 for housing and protecting an electrically ignited gas burner or pilot burner 32 disposed therein.

In the illustrated embodiment the gas burner or pilot 32 comprises a lighter cup 33 defining an ignition or flame retaining chamber 34 having its open end directed toward the opening 28C of the bracket 28 and the chamber 30 aligned therewith. The cup 33 is supported within the protection sleeve 31 by a yoke 35 connected to the end of a longitudinally extending fuel supply conduit 36 which extends through the rear end 31A of the sleeve 31, and which serves to supply the raw gas to the chamber 34 defined by the lighter cup 33.

The discharge end 36A of the fuel supply conduit 36 is constructed to operate with maximum gas flow, i.e. the discharge end of conduit 36 has a Wide open end. As seen in FIGS. 1 and 2, the discharge end 36A is disposed in alignment with and spaced from a gas inlet 33A formed in the rear wall 37 of the lighter cup.

Gas is supplied to the pilot supply conduit 36 through a branch pipe 38 which connects into the main gas supply downstream of the gas valve 24. Thus it will be noted that the valve 24 controls the fiow of gas to both the pilot burner 32 and the main burner 15A.

The air to be mixed with the gas issuing to the pilot burner 32 to form an ignitable mixture therein is admitted through a hole 40 in the protection sleeve 31, the hole 40 being disposed adjacent the discharge end 36A of the gas supply conduit 36. This hole connects the interior of the sleeve 31 with the surrounding windbox and by proper sizing of the hole 40, the amount of air admitted to be mixed with the gas of the pilot burner can be limited. By limiting the quantity of air admitted into this zone it is possible to maintain the low velocities necessary to establish and maintain a very stable ignition source.

In accordance with this invention the amount of air admitted through the opening 4% in the sleeve 31 is insufficient to burn all of the gas at the pilot, but enough air is admitted to form a readily ignitable and burnable mixture. The arrangement is such that upon ignition, the partially burned pilot gas-air mixture emerges from the end of the protection tube to pass through 28C into the rectangular chamber 39 and thence through the firing port 12. Adjacent the rear end 26 of the rectangular manifold 16 additional air admitted through side openings 29 is mixed with the unburned pilot gases and the combustion is completed.

In accordance with this invention the fuel-air mixture of the pilot burner 32 is initially ignited by a spark produced by a pair of spaced electrodes 41 and d2 defining a sparking gap in igniting relationship to the pilot burner fuel-air mixture. As shown, electrode 41 extends longitudinally of the protective housing 31 and it is suitably insulated therefrom and from ground. Electrode 41 extends substantially parallel to the gas conduit 36 and it extends through an appropriate opening 333 formed in the end 37 of the lighter cup 33. The other electrode 42 is grounded to the lighter cup 33. IVhile item 42 may be referred to as the ground electrode, the whole burner With the exception of electrode 41 is at ground potential and is obviously much larger than electrode 41. The whole burner, with the exception of the electrode 41, then acts as the ground circuit for both the sparking and flame sensing circuits. Electrode 42 is used only to give a predetermined spark gap and to definitely locate the point of sparking. Thus it will be apparent that when the

electrodes

41 and 42 are energized for ignition, a spark is produced which will ignite the pilot fuel-air mixture, and this flame in turn will ignite the fuel-air mixture of the main burner portion A.

By concentrating the gases issuing through the orifices of the manifold at the center thereof, an excess air area and low velocity zone are created at the top and bottom portions of the manifold, and combustion is stabilized in these zones due to the formation of eddy currents. In addition, recirculating eddies are obtained at the rear end of the manifold from the action of the air entering at the sides of the manifold and by the jet action of the pilot combustion products entering the manifold to create additional stabilizing eifects on the burner flame.

In addition to maintaining a zone in which initial ignition occurs, preheating of the gases occurring within the mixing chamber results in improved combustion stability and provides a further benefit to be derived from the instant construction.

FIGS. 4 to 6 illustrate a slightly modified burner assembly embodying the instant inventive concept. Referring to FIGS. 4 to 6, it will be seen that the burner assembly 115 is also adapted to be fitted into an appropriate opening 113A formed in the windbox casing 113 and disposed in alignment with an air port 112, defined by wall tubes 111. In this form of the invention the gas and air mixing chamber 130 of the main burner portion 115A is bounded on the sides only by gas receiving chambers or manifolds 116A, 11613 and spaced

plates

116C, 116D which interconnect the

manifolds

116A, 116B for maintaining them in spaced relationship. Each of the

manifolds

116A, 116B is bounded by spaced inner and

outer walls

116F and 116E connected by top, bottom and end

walls

117, 118, 119, respectively, to form a closed manifold chamber 120. Raw gas is supplied into each of the gas manifold chambers by means of a suitable supply conduit 122, which connects into a main gas supply line 123; and as previously described, a solenoid operated gas valve 124 is disposed in the main gas supply line 123 for controlling the flow of gas to the

respective manifolds

116A, 116B.

The opposed inside walls 116]? of the

respective gas manifolds

116A, 116B have drilled therethrough a plu-' rality of gas orifices arrayed in a triangular pattern as previously described with respect to FIGS. 1 to 3. In addition, a gas discharge orifice 125A is provided in the inside wall 116E of the respective manifolds 116A, 1168 adjacent the upper and lower corner portion at the end of the gas manifold remote from the furnace wall. The purpose of these corner disposed orifices 125A is to increase the visibility of the flame as will be hereinafter described.

Spaced from the rear end of the gas manifold 116A, 1163 or fuel-air mixing chamber is the mounting plate 126 of the burner assembly 115. As seen in FIGS. 4 to 6, the upper and

lower plate

116C, 116D defining the upper and lower boundaries of the fuel-air mixing chamber 139 extend rearwardly beyond the rear ends of the gas manifolds. Connecting the main burner portion 115A to the mounting plate 126 are a pair of observation tubes 127. As shown, the observation tubes 127 are arranged so that one end of each observation tube 127 is connected in alignment with an observation port 127A formed in the mounting plate 126 of the burner, and the other ends of the observation tubes are connected to the extended portions of the upper and lower plates 116C, 1161) respectively. Disposed between the observation tubes 127 and extending between the mounting plate 126 and the rear end of the fuel and air mixing chamber 130 is a protection sleeve 131, in which the continuous pilot burner or lighter 11513 is mounted. As shown in FIG. 4, the forward end 131A of the protection sleeve is connected to and between the forward end of the respective observation sleeves 127 and the rear end of the mounting plate 126. As therein shown, each of the

respective sleeves

127 and 131 are spaced from the rear end of the fuel-air mixing chamber 130. Thus the air from the windbox is permitted to pass through the side spacing 130B and into the mixing chamber 130 as hereinbefore described with reference to FIGS. 1 to 3.

The lighter or pilot burner portion 115B positioned within the protection sleeve 131 is substantially identical with the pilot burner 32 as previously described. For this reason, further detailed description thereof is not considered essential.

Gas to the pilot burner portion 115B is supplied in the same manner as hereinbefore described, and air to the pilot burner is admitted through an opening in protection tube 131. Because this form of the burner assemblies 115 is provided with observation ports 127A in alignment with observation tubes 127, orifices 125A positioned at the corner of the inside walls 116E of the

manifolds

116A, 116B Will facilitate observation of the flame.

In operation, the modified burner of FIGS. 4 to 6 is similar to the burner assembly 15, as hereinbefore described, and therefore a further discussion is not necessary.

An aspect of this invention relates to disposing the pair of igniting

electrodes

41 and 42 in a novel electrical circuit 50 as shown in FIG. 7 so that the electrodes function both as a spark ignitor for initially igniting a burner flame and thereafter are electrically switched to function as a flame rod or detector after the initial flame is established so as to continually detect and monitor the presence or absence of the flame. To function as a flame rod, the electrode 41 is required to be disposed in flame impingement relationship with the flame to be monitored. In the illustrated embodiment, the

electrodes

41 and 42 are disposed in flame impingement relationship to the flame of the pilot burner as well as being in igniting relationship to the fuel-air mixture therein. The electrode 41, when functioning as a flame rod or flame detector, monitors only the portion of the flame within the burner and not the flame within the furnace; nevertheless, it serves as an effective flame monitor since all of the gas supplied to the pilot and the manifold becomes part of the raw gas stream once the ignition spark ceases.

However, it will be appreciated by those skilled in the art that the

electrodes

41 and 42 may be disposed so as to detect the presence and absence of the main burner flame as well, and the circuitry to be herein described can be readily adapted to a burner installation or assembly which does not require the inclusion of a pilot burner disposed in igniting relationship therewith. In such instances the electrodes are disposed in impinging relationship with the flame of a main burner. In its broadest application the circuitry to be herein described can be readily adapted to monitor any given flame regardless of its source, i.e. be it as pilot flame, or a main burner flame.

Referring to FIG. 7 there is schematically shown the electric circuitry 50 whereby the electrode 41 is arranged to function both as an igniting rod and as a flame rod.

Accordingly,

conductors

51 and 52 connect to a suitable source of alternating current. Connected across the AC.

conductors

51 and 52 is a suitable flame sensing or detecting device 53, as for example a Minneapolis-Honeywell P relay (R 7203). Since the sensing device 53 comprises a standard commercial unit only that portion of it necessary to understand the invention is schematically illustrated. The sensing device 53 is also connected by a conductor 54 to electrode 41.

Also connected across the AC.

conductors

51 and 52 is the primary winding 55 of a step-up igniting transformer T, the secondary winding 56 of which is connected to electrode 41 by a conductor 57. The transformer is thus disposed in parallel relationship with respect to the sensing device 53.

Included in the circuit 50 is a switching relay SR58 by which the electrode 41 is electrically switched to either the transformer T to produce the spark for igniting the flame or to the sensing device 53 upon the establishment of a flame. This switching relay SR58 comprises a relay coil 58A operating normally closed contacts 58B and normally open contacts 58C. As shown, the coil 53A of relay SR58 is connected across the AC.

conductors

51, 52 while the normally closed contacts 58B are disposed in line 57 connecting the secondary winding 56 of the transformer in series with electrode 41. The normally open contacts 58C are disposed in line 54 in series between the electrode 41 and the sensing device 53. Energizing of the switching relay coil 58A will thus open contact 58B and close contacts 58C to place the electrode in the flame detecting side of the circuit, and de-energizing coil 58A will return the electrode 41 to the igniting side of the circuit.

A solenoid coil 59 for operating the gas valve 24 in the gas supply line is also connected across the AC.

conductors

51 and 52. Also a time delay relay TD6E), operably associated with the valve solenoid coil 59 has its coil 60A connected across the AC.

conductors

51, 52 by a conductors 61; and coil 60A controls normally closed contacts 60B disposed in series with the valve solenoid coil 59.

A valve actuating relay VR62 which controls the energizing of the gas valve solenoid 59 has its coil 62A connected across the AC.

conductors

51, 52 by

conductors

63 and 63A so as to be in parallel to the time delay relay TD60. Relay VR62 when energized operates normally open contacts 62B connected in series with its coil 62A and a second normally open contact 62C disposed in series with the time delay contacts 60B. Interconnecting

conductors

61 and 63 so as to place the coil 60A of the time delay relay TD60 and the coil 62A of the valve actuating relay VR62 in parallel is a cnductor 66, the latter interconnecting with conductor 63 between contacts 62B and relay coil 62A.

Connected across the AC.

conductors

51 and 52 and in parallel with the relay coil 62A is a suitable indicator 64, as for example a lamp that is energized only when a flame is established and detected by the electrode 41.

Upon the establishment of a flame at the burner, the gases. generated by combustion are ionized and function to rectify the alternating current to superimpose a direct current on the AC. circuit, the direct current thereafter being amplified by an electronic tube in the sensing device 53. The direct current when amplified powers a plate relay PR65, the coil 65A of which operates normally open contacts 65B, normally closed contacts 65C, normally closed contacts 65D, and normally open contacts 65E. Of these the normally open contacts 65B are disposed in series with the lamp 64 and when actuated will close the circuit for energizing the lamp. Normally closed contacts 65C are disposed in parallel with contacts 65B and in series with both contacts 62B and relay coil 62A. Normally closed contacts 65D are connected in series with contacts 64113 of the time delay relay TD60 contacts 62C of relay VR62; and the normally open contacts 65E are connected in parallel with the serially connected

contacts

65D, 60B and 62C.

A push button P1370, actuating normally open contacts 79A, normally closed contacts 70B, and normally open contacts 70C, all connected in parallel, serves to open and close the circuits to the time delay coil 60A, coil 58A of the switching relay SR53, and to the primary 55 of the transformer T respectively.

Completing the circuit is a line switch 71 and a fuse 72 connected in series therewith.

In the circuitry 50 described, the circuit of the flame detecting device 53 is typical of the known detecting circuits. Briefly, its function is as follows:

When coil 53A of the switching relay SR58 is energized, the normally closed switching relay contacts 5813 open, and the normally open contacts 58C close. When this occurs, electrode 41 is connected directly to the flame detecting device 53 through conductor 54, and thus electrode 41 is in position to function as a flame rod or detector through the circuitry of device 53. The sensing device 53 imposes an AC. voltage between electrode 41 and the grounded electrode 42. If a flame is present and it is impinging upon both electrode 41 and the ground electrode 42, the flame with its ionized combustion gases will rectify the alternating circuit to a direct current of small magnitude. This direct current is then superimposed on the AC. circuit and is amplified by a suitable electronic tube such as a 12SN7 or an equivalent thereof, in the sensing device 53. The amplified direct current then powers the coil 65A of plate operated relay PR65. The actuation of the plate operated relay coil 65A upon the presenece of a flame holds the gas valve 24 open to insure a gas supply to the burner and effects the energizing of the indicating lamp 64. However, if the electrode 41 should be grounded, or in the event a flame is not detected, an alternating circuit will be imposed on the amplifying tube 12SN7. When this happens, the plate relay 65 cannot be powered, and the sensing device 53 will fail safe.

A particular feature of this invention is directed to the circuitry by which the electrodes are switched to function either as an igniting means or a flame detecting means by a circuit external that of the flame detecting device. This is accomplished in the following manner:

FIG. 7 illustrates the circuit 50 completely de-energized prior to the closing of the line switch 71. When the line switch 71 is closed, the switching relay coil 58A becomes energized. Energizing of the coil 58A in turn opens its normally closed contact 58B and closes its normally open contact 53C. This places the electrode 41 in the flame detecting circuit of device 53. Since the flame has not yet been established, no action occurs at this time.

The closing of the line switch also energizes the flame detecting device 53. Since this device contains an electronic tube a brief delay is required before proceeding with the operation of the circuit in order to permit time for the tube to Warm up.

After a lapse of approximately 30 seconds or so, the push button R370 is actuated. In doing so, contact 703 opens and thus breaks the circuit to the switching relay SRSS de-energizing coil 58A, thereby returning contacts 583 to closed position and contacts 58C to open position. Thus the electrode 41 is now directly connected to the secondary 56 of the transformer T and is therefore ready for use as an ignition means, as the push button 70 also serves to close

contacts

70A and 70C. The closing of contacts 70A on pressing the push button effects energizing of the time delay coil 66A to start its preset timing cycle; the lapse of which will cause its closed contacts 608 to open.

The closing of contacts 70A also results in energization of the coil 62A of the gas valve relay VR62, which in turn effects the closing of normally open contacts 62B and 62C. Upon the closing of contacts 62B, the coil 62A becomes energized through the normally closed plate relay contact 65C and its own contact 6213.

Contacts 62C, when closed effects the energizing of the gas valve solenoid 59 through the normally closed plate relay contacts 65D, normally closed time delay contact MP3, and the closing of its own relay contact 62C. This permits gas to flow through the valve 24' to the gas burner.

When contact 70C of the push button '70 is closed, the primary coil 55 of the transformer is energized. In energizing the transformer, a voltage of 5,000 to 10,000 volts is introduced in the secondary 56 of the transformer. This results in a spark occurring between the electrode 41 and the ground electrode 42, and it is this spark which supplies the high level energy necessary to ignite the gas-air mixture flowing to the burner.

ft is to be noted that the spark is continuous as long as the push button PB70 is depressed. In the event that the spark should fail to ignite the gas within the burner in a prescribed predetermined interval of time, the time delay contacts 60B will then open and thus effect the (la-energizing of the gas valve solenoid 59 causing gas valve 24 to close. The time delay contact 6913 thus functions as a means for limiting the trial for the ignition period.

It is to be noted that a mechanical lag may be built into the push button PB70 to insure that the switching relay coil 58A is de-energized to effect the closing of contacts SbB and the opening of contacts 58C before the primary 55 of the transformer T is energized. Thus this action allows

contacts

58B and 58C to actuate under a no load condition, allowing for smaller current contacts to be used.

It will be understood that although the sequence of the push button P370 is herein accomplished by mechanical lag, it is also possible to obtain the sequence with a suitable timing device.

A feature of the invention resides in that the switching relay contact 580 is formed with a relatively wide gap between contacts. The purpose of the wide gap is to prevent the high voltage present during the spark ignition period from entering the flame detecting device, and thereby causing injury to its components.

When the flame is established, the push button PB'70 is released. In releasing the push button, contacts 70C open to thus break the circuit to the primary side 55 of the transformer and sparking ceases.

Release of the push button PB70 also opens the line to the time delay relay TD60, however, it will be noted that the time delay TDfitl remains energized since the power is supplied to the time delay relay coil 60A through conductors 63A, plate operated normally closed contact 65C, conductor 63, closed contacts 62B and conductor 66. Thus the time delay coil remains energized after the push button PB7t} is released.

Upon releasing of the push button 70, the switching relay coil 58A is again energized through the closing of contact 70B. This, in turn, effects opening of the contact 58B and the closing of contacts 58C so that the electrode 41 is now placed in the flame detecting circuit of device 53. It is to be observed that releasing of the push button PB7tl first de-energizes the transformer to prevent its high voltage from entering the flame detecting device 53 or from arcing across the switching relay contacts. The high voltage of the transformer is also kept out of the flame detecting device upon the release of the push button due to the time required for the wide gap contacts 58C to move to closed position.

Due to the ionization of gases, the presence of the flame impinging on the electrode 41 will rectify current which is amplified in the detecting device 53. The amplified direct current then energizes the coil 65A of a plate operated relay PR65.

Upon energizing the plate relay coil 65A, the normally opened plate operated contacts 65E close to supply a continuous current to the valve solenoid 59, even after the time delay contacts 60B open after the lapse of a predetermined time interval. Should the flame be interrupted for any reason following the opening of time delay contacts 69B, the plate relay coil 65A wil be de-energized thus opening contacts 65E to de-energize the solenoid 59 which then closes the gas valve to shut off the flow of gas to the burner.

Energizing of the plate relay coil 65A also causes contacts 653 to close thereby energizing the lamp 64 to indicate that a flame is established and is being detected.

Energizing of the plate relay coil 65A also effects the opening of contacts 65C to de-energize the coil 62A of the gas valve relay VR62. It is to be noted however that if the flame is not detected, and the coil 65A of the plate operated relay is not energized, it will be necessary to momentarily open the line switch 71 to de-energize the gas relay coil 62A.

Actuation of the plate operated coil 65A also effects the opening of contacts 65D to break the circuit to the solenoid 59 through the

contacts

60B and 62C. Also de-energizing of the coil 62A of relay 62 upon the opening of contacts 65C will effect the opening of contacts 62C, and this also functions to break the circuit to the gas valve solenoid 59.

Even if the flame is established, it is necessary that it be verified by the flame detecting device. If it is not verified the time relay contacts 603, after termination of a prescribed time limit will open to break the circuit to the gas valve solenoid holding coil 59 thus shutting off the gas to the burner. This then in effect is a fail safe feature of the circuit since any malfunction of the flame detecting device 53 will shut the flame off or prohibit firing of the burner any longer than the trial period.

While the instant invention has been disclosed with reference to a particular embodiment thereof, it is to be appreciated that the invention is not to be taken as limited to or of the details thereof as modifications and variations thereof may be made without departing from the spirit or scope of the invention.

What is claimed is:

1. A gas burner comprising concentrically disposed and mutually spaced inner and outer conduits to define therebetween a gas manifold having closed end portions, said manifold defining a mixing chamber, means for supplying raw gas to said manifold, means defining a plurality of gas discharge orifices formed in the opposed wall portions of the inner conduit for discharging streams of gas into said mixing chamber, means forming an inlet to said chamber through which combustion air is introduced thereinto to mix with the gas discharged from said manifold, a pilot burner disposed in lighting relationship to the gas and air mixture within said chamber, means for supplying gas to said pilot burner, means to permit the introduction of air to said pilot burner to form an ignitable mixture with the gas in said pilot burner, a pair of electrodes within said pilot burner defining therebetween a sparking gap disposed in igniting relationship to the gas mixture of said pilot burner, an electrical circuit for energizing said electrodes to create a spark across the gap to ignite the gas and air mixture of said pilot burner, one of said electrodes being extended into said mixing l. l chamber, an electrical circuit including a flame detector of the type responsive to the immersion of the last named electrode in a flame in said mixing chamber, and switching means for sequentially connecting said last named electrode to each of the above named electrical circuits.

2. In combination with a main burner, a pilot burner operative to ignite the flame of said main burner, a fuel conduit for supplying fuel to the pilot burner, and a valve in said conduit for controlling the flow of fuel to said pilot burner, a flame igniting and flame detecting system comprising a pair of electrodes defining therebetween a sparking gap disposed in igniting relationship to the fuel mixture of the pilot burner and in flame impingement relationship to the flame of said mixture upon the ignition thereof, an A.C. supply, a flame detecting device connected across said A.C. supply and in series to one of said electrodes, a transformer having its primary winding con .nected across the A.C. supply and its secondary connected in series with said one electrode, an indicator light connected across said A.C. supply, a solenoid operating said valve connected across said A.C. supply, a switching relay connected across said A.C. supply and including a coil, said coil operating normally closed contacts disposed in series between the secondary of said transformer and said one electrode and normally open contacts in series with said detecting device and said one electrode, a valve energizing relay connected across said A.C. supply and including a coil, a time delay relay including a coil connected across said A.C. supply, a lead connecting the coil of said valve energizing relay and time delay relay in parallel, said valve energizing relay operating a normally open contact disposed in a holding circuit connected to the coil of said valve energizing relay and a normally open contact disposed in series with said solenoid, said time delay relay operating a normally closed contact disposed in series with said normally open contact of the valve relay and in series with said solenoid, a relay in said detecting device operating normally closed contacts disposed in series with both the normally open contacts of said valve relay and serially connected normally closed contacts of said time delay relay, normally open contacts connected in series with said solenoid and being in parallel with the normally open contacts of said valve relay and the serially connected normally closed contacts of said time delay relay, normally closed contacts dis posed in series with the normally open contacts of said valve relay, and normally open contacts disposed in series with said indicator light; a push button having a first switch normally opening the circuit to the coil of said time delay relay, a second switch normally closing the circuit to the coil of said switching relay, and third switch normally opening the circuit to the primary of said transformer; and a normally opened line switch in one line of said A.C. supply.

3. A flame igniting and flame detecting system comprising a pair of electrodes defining therebetween a sparking gap disposed in igniting relationship to the fuel mixture of a burner and in flame impingement relationship to the flame of said mixture upon the ignition thereof, an A.C. supply, a flame detecting device connected across said A.C. supply and in series to one of said electrodes, a transformer having its primary winding connected across the A.C. supply and its secondary connected in series with said one electrode, an indicator light connected across said A.C. supply, a solenoid operating said valve connected across said A.C. supply, a switching relay connected across said A.C. supply and including a coil, said coil operating normally closed contacts disposed in series between the secondary of said transformer and said one electrode and normally open contacts in series with said detecting device and said one electrode, a valve energizing relay connected across said A.C. supply and including a coil, a time delay relay including a coil connected across said A.C. supply, a lead connecting the coil of said valve energizing relay and the coil of said time delay relay in parallel, said valve energizing relay operating a normally open contact disposed in a holding circuit connected to the coil of said valve energizing relay and a normally open contact disposed in series with said solenoid, said time delay relay operating a normally closed contact disposed in series with said normally open contact of the valve relay and in series with said solenoid, a relay in said detecting device operating normally closed contacts disposed in series with both the normally open contacts of said valve relay and serially connected normally closed contacts of said time delay relay, normally open contacts connected in series with said solenoid and being in parallel with the normally open contacts of said valve relay and the serially connected normally closed contacts of said time delay relay, normally closed contacts disposed in series with the normally open contacts of said valve rela and normally open contacts disposed in series with said indicator light; a push button having a first switch normally opening the circuit to said time delay relay, a second switch normally closing the circuit to said switching relay, and a third switch normally opening the circuit to the primary of said transformer; and a normally opened line switch in one line of said A.C. supply.

4. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed inner walls and another pair of walls which cooperate with the inner walls to form a passage of substantially rectangular cross-section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air, each of said oppositely disposed inner walls being formed with a multiplicity of orifices arranged in and confined to the pattern of a triangle having its base adjacent said discharge end for the introduction of fuel from the manifold into the pasage so that the proportion of fuel and the dispersion of the entering fuel across the cross-sectional area of the passage progressively increase in the direction of the outlet thereof, means for supplying gaseous fuel to the manifold, and means for supplying combustion air into the opposite end of said passage and effecting mixing thereof with the fuel entering the passage.

5. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed inner walls and another pair of walls which cooperate with the inner walls to form a passage of substantially rectangular cross-section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air, said inner walls being formed with a multiplicity of orifices arranged in and confined to the pattern of a triangle having its base adjacent said discharge end for the introduction of fuel from the manifold into the passage so that the proportion of fuel and the dispersion of the entering fuel across the cross-sectional area of the passage progressively increase in the direction of the outlet thereof, means for supplying gaseous fuel to the manifold, and means for supplying streams of combustion air into said burner from the sides of and immediately to the rear of said passage in opposed directions transverse to the longitudinal axis of said passage and turning said streams of combustion air to flow through said passage to effect the establishment of eddy currents adjacent said inner walls and mixing of said combustion air with the fuel entering said passage.

6. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed inner walls and another pair of walls which cooperate with the inner walls to form a passage of substantially rectangular cross-section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air, a flame detection element extending into the passage and being substantially coextensive with the longitudinal axis of said passage for detecting the presence of flame therein, said inner walls being formed with a multiplicity of orifices arranged for the introduction of gaseous fuel from the manifold into the passage so that the fuel is concentrated around the detection element to effect cooling thereof, means for supplying gaseous fuel to the manifold, and separate means for supplying combustion air into the opposite end of said passage and effecting mixing thereof with the fuel entering the passage.

7. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed inner walls and another pair of walls which cooperate with the inner walls to form a passage of substantially rectangular cross-section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air, a flame rod extending into said passage for detecting the presence of a flame therein, a cooperating flame detection unit of the type responsive to the immersion of said flame rod in a flame within said passage, said inner walls being formed with a multiplicity of orifices arranged for the introduction of gaseous fuel from the manifold into the passage so that the fuel is concentrated around the flame rod to effect cooling thereof, means for supplying gaseous fuel to the manifold, and separate means for supplying a portion of the necessary combustion air into the opposite end of said passage and effecting mixing thereof with the fuel entering the passage to form a wide range of fuel/air mixtures in said passage.

8. A gaseous fuel burner comprising means forming a combustion and mixing chamber within the burner, means for introducing gaseous fuel into said chamber, a pilot ignitor disposed in igniting relationship to the fuel and air mixture within said chamber, means for introducing fuel and combustion air into said ignitor, an electrode extending into said chamber through said ignitor and forming a spark gap in said ignitor, a first electrical circuit including a high voltage source, a second electrical circuit including a flame detection unit of the type responsive to the immersion of said electrode in a flame, and switching means for selectively connecting said electrode to said first circuit to create a spark across said spark gap to ignite the fuel and air mixture within said ignitor, and to said second circuit for detecting the presence of flame within said chamber.

9. A gaseous fuel burner comprising means forming a combustion and mixing chamber Within the burner, means for introducing fuel and combustion air to said chamber, a pilot ignitor disposed in igniting relationship to the fuel and air mixture within said chamber, means for introducing fuel and combustion air into said ignitor, an electrode extending into said chamber through said pilot ignitor and forming a spark gap in said ignitor, a high voltage source, a flame detection unit of the type responsive to the immersion of said electrode in a flame, and means for selectively connecting said electrode to the high voltage source and the flame detection unit to respectively create a spark across said spark gap to ignite the fuel and air mixture within said ignitor and detect the presence of flame within said chamber.

10. A gaseous fuel burner comprising means forming a combustion and mixing chamber Within the burner, a pilot ignitor disposed in igniting relationship to said chamber, means for introducing fuel and combustion air into said ignitor, an electrode extending into said chamber through said ignitor and forming a spark gap in said ignitor, a high voltage source, a flame detection unit of the type responsive to the immersion of said electrode in a flame, means for selectively connecting said electrode to the high voltage source and the flame detection unit to respectively create a spark across said spark gap to ignite the fuel and air mixture within said ignitor and detect the presence of flame within said chamber, means for introducing gaseous fuel into said chamber so that the fuel is concentrated around said electrode to effect cooling thereof, and means for introducing combustion air to said chamber.

11. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed ini4 ner walls and another pair of walls which cooperate with the inner walls to form a chamber of substantially rectangular cross-section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air,tmeans for introducing fuel and combustion air to said chamber, a pilot ignitor disposed in igniting relationship to the fuel and air mixture Within said chamber, means for introducing fuel and combustion air into said ignitor, an electrode extending into said chamber through said ignitor and forming a spark gap in said ignitor a high voltage source, a flame detection unit of the type responsive to the immersion of said electrode in a flame, and means for selectively connecting said electrode to the high voltage source and the flame detection unit to respectively create a spark across said spark gap to ignite the fuel and air mixture within said ignitor and detect the presence of flame within said chamber.

12. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed inner walls and another pair of walls which cooperate with the inner walls to form a chamber of substantially rectangular cross-section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air, a pilot ignitor disposed in igniting relationship to said chamber, means for introducing fuel and combustion air into said ignitor, an electrode extending into said chamber through said ignitor and forming a spark gap in said ignitor, said electrode being substantially co-extensive with the longitudinal axis of said chamber, a first electrical circuit including a high voltage source, a second electrical circuit including a flame detection unit of the type responsive to the immersion of said electrode in a flame, switching means for selectively connecting said electrode to said first circuit to create a spark across said spark gap to ignite the fuel and air mixture within said ignitor and to said second circuit for detecting the presence of flame Within said chamber, said inner Walls being formed with a multiplicity of orifices arranged for the introduction of gaseous fuel from the manifold into the chamber so that the fuel is concentrated around the electrode to effect cooling thereof, and means for supplying combustion air into the opposite end of said chamber and effecting mixing thereof with the fuel entering the chamber.

13. A burner comprising a gas manifold having a pair of opposed gas chamber portions defining therebetween a gas-air mixing chamber, means for supplying gas to said manifold, said gas chamber portions having opposed Wall portions having formed therein a plurality of gas orifices through which opposed streams of gas are discharged into said mixing chamber, means for introducing combustion air into said mixing chamber to form an ignitable mixture with the gas discharged from said gas manifold, a lighter for igniting said mixture, and a combined flame igniting and flame sensing means including an electrode extending through said lighter and into said mixing chamber, said electrode being arranged to selectively effect a spark in said lighter and to detect the presence of a flame in said mixing chamber.

14. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed inner Walls and another pair of walls which cooperate with the inner walls to form a passage of substantially rectangular cross section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air, said inner walls being formed with a multiplicity of orifices for the introduction of the fuel from the manifold into said passage, means for supplying gaseous fuel to the manifold, a C-shaped member cooperating with said manifold to form a pair of air ports disposed on opposites sides of the longitudinal axis of said passage in planes substantially parallel to the planes of said inner walls, and means for passing streams of combustion air through said air ports and turning said streams of combustion air to flow into the opposite end of said passage to effect the establishment of eddy currents adjacent said inner walls and mixing of said combustion air with the fuel entering said passage through said orifices.

15. A gaseous fuel burner comprising means forming a fuel manifold having a pair of oppositely disposed inner walls and another pair of walls which cooperate with the inner walls to form a passage of substantially rectangular cross-section opening at the discharge end and adapted for the mixing and combustion of gaseous fuel and air, said inner walls being formed with a multiplicity of orifices for the introduction of the fuel from the manifold into the passage, means for supplying gaseous fuel to the manifold, means forming a pair of air ports disposed on opposites sides of the longitudinal axis of said passage in planes substantially parallel to the planes of said inner walls, and means for supplying streams of combustion air into said burner through said ports in opposed directions transverse to the longitudinal axis of said passage and turning said streams of combustion air to flow through said passage to effect the establishment of eddy currents 16 adjacent said inner Walls and mixing of said combustion air with the fuel entering said passage.

References Cited in the file of this patent UNITED STATES PATENTS 725,110 Merrill Apr. 14, 1903 1,233,779 Hicks July 17, 1917 1,395,139 Porter Oct. 25, 1921 1,758,790 Fisher et a1 May 13, 1930 1,827,338 Shippee Oct. 13, 1931 2,109,079 Ziegler et al Feb. 22, 1938 2,627,308 Clark Feb. 3, 1953 2,804,919 Kinnison Sept. 3, 1957 2,996,113 Williams Aug. 15, 1961 3,002,550 Schreter Oct. 3, 1961 FOREIGN PATENTS 23,350 Great Britain of 1913 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,145 ,764 August 25 1964 John M. Rackley It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 1, line 17, strike out "for"; line 42, for "It" read In column 7, line 54, for "conductors" read conductor column 8, line 47, for "presenece" read presence column 10, line 42, for "relay" read delay column 12, line 35, for "pasage" read passage column 13, line 28, after "chamber," insert means for introducing combustion air into said chamber,

Signed and sealed this 10th day of August 1965.

(SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attcsting Officer Commissioner of Patents

Claims

1. A GAS BURNER COMPRISING CONCENTRICALLY DISPOSED AND MUTUALLY SPACED INNER AND OUTER CONDUITS TO DEFINE THEREBETWEEN A GAS MANIFOLD HAVING CLOSED END PORTIONS, SAID MANIFOLD DEFINING A MIXING CHAMBER, MEANS FOR SUPPLYING RAW GAS TO SAID MANIFOLD, MEANS DEFINING A PLURALITY OF GAS DISCHARGE ORIFICES FORMED IN THE OPPOSED WALL PORTIONS OF THE INNER CONDUIT FOR DISCHARGING STREAMS OF GAS INTO SAID MIXING CHAMBER, MEANS FORMING AN INLET TO SAID CHAMBER THROUGH WHICH COMBUSTION AIR IS INTRODUCED THEREINTO TO MIX WITH THE GAS DISCHARGED FROM SAID MANIFOLD, A PILOT BURNER DISPOSED IN LIGHTING RELATIONSHIP TO THE GAS AND AIR MIXTURE WITHIN SAID CHAMBER, MEANS FOR SUPPLYING GAS TO SAID PILOT BURNER, MEANS TO PERMIT THE INTRODUCTION OF AIR TO SAID PILOT BURNER TO FORM AN IGNITABLE MIXTURE WITH THE GAS IN SAID PILOT BURNER, A PAIR OF ELECTRODES WITHIN SAID PILOT BURNER DEFINING THEREBETWEEN A SPARKING GAP DISPOSED IN IGNITING RELATIONSHIP TO THE GAS MIXTURE OF SAID PILOT BURNER, AN ELECTRICAL CIRCUIT FOR ENERGIZING SAID ELECTRODES TO CREATE A SPARK ACROSS THE GAP TO IGNITE THE GAS AND AIR MIXTURE OF SAID PILOT BURNER, ONE OF SAID ELECTRODES BEING EXTENDED INTO SAID MIXING CHAMBER, AN ELECTRICAL CIRCUIT INCLUDING A FLAME DETECTOR OF THE TYPE RESPONSIVE TO THE IMMERSION OF THE LAST NAMED ELECTRODE IN A FLAME IN SAID MIXING CHAMBER, AND SWITCHING MEANS FOR SEQUENTIALLY CONNECTING SAID LAST NAMED ELECTRODE TO EACH OF THE ABOVE NAMED ELECTRICAL CIRCUITS.