US2941585A - Oil-gas burner - Google Patents

Description

June 21, 1960 F. A. LoEBEl. ETAI- 2,941,585

OIL-GAS BURNER Filed July 29, 1957 2 Sheets-Sheet 1 i fray 27]. 17u 5e/2 7 and, i' WW' fianza/47.5

Juli 2l, 1960 F A, LOEBEL -.TAL

OIL-GAS BURNER 2 Sheets-Sheet 2 Filed July 29, 1957 United States Patent OIL-GAS BURNER Frederick A. Loebel and Elroy M. Rulseh, Milwaukee,

Wis., assignors to Cleaver-Brooks Company, a corporation of Wisconsin Filed July 29, 1957, Ser. No. 674,874

4 Claims. (Cl. 158-11) This invention relates to combustion apparatus adapted for burning either liquid or gaseous fuel, and has for a general object the provision of a new and improved apparatus of this type.

In combination oil and gas burning apparatus, a nozzle is provided adjacent the combustion zone for discharging oil in an atomized state to be burned in the combustion chamber, and additional means is provided for use alternatively to supply gaseous fuel .for combustion in the same combustion chamber. Normally, the oil nozzle is positioned closely adjacent the combustion zone in order to properly discharge the oil yfor burning, and while the positioning of the nozzle in this manner is necessary and advantageously contributes to the provision of a combination oil and gas burning apparatus, it also givesrise to certain problems. i More speciiically, one of the problems encountered is that excessive heat on the oil nozzle while burning gas may be suiiicient to vaporize and coke any oil droplets left in the narrow nozzle passages, partially or totally blocking the passages. Thus, when burner operation is changed from gas firing to oil firing, oil atomization willbe adversely afected because of the coke in the nozzle passages, and combustion will be poor. Further, it is possible, even if the oil nozzle is properly purged of oil, leaving only a thin film, that the heat on the oil iilm within the nozzle may bake the film so that it is dicult to take the nozzle apart for cleaning.

The problem is best solved by removing the nozzle from the hot zone, but it is essential that the changeover from gas tiring to oil firing and vice versa, be as simple as possible with a minimum of manipulations required. j Accordingly, with the above and other considerations in mind, it is a more specific object of the invention to provide a new and improved combination oil and gas burner apparatus including means mounting the oil burner nozzle for movement from an advanced oil firing position closely adjacent to the combustion zone toV a retracted, protected position to reduce the heat on the nozzle during 'gas tiring.

`Another `object is to provide a new and improved comA bination oil and gas burner apparat-us of the type described in the preceding paragraph including control means to prevent oil iiring when the oil nozzle is in the Aretracted gas firing position. l AOther objects and advantages will become readily apparent from the following detailed description taken in ,connection with the accompanying drawings, in which: v Fig. 1 is a fragmentary vertical sectional view taken along the longitudinal axis of a boiler structure embodying the principles of the present invention;

Fig. 2 is an enlarged fragmentary left end elevational view of the boiler structure illustrated in Fig. l;

e l CC tended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

Referring now to the drawings, as illustrated, the invention Vis embodied in a horizontal iire tube boiler which includes a horizontally disposed tubular boiler shell which may be supported by any suitable means. Near the end of the boiler shell shown in Fig. 1, a tube sheet 11 extends across the shell and is suitably secured thereto as yby welding illustrated at 12, and together with similar means provided at the end of the boiler shell not illustrated provides a means for supporting a lire tube 13. The re tube 13 and additional smaller tubes such as that illustrated at 14, with suitable additional structure, form multiple passes for combustion gases, through the boiler to an exhaust stack all as is conventional in boiler equipment of the type illustrated.

The iire tube 13 comprises a horizontally disposed, generally cylindrical tube of suitable metal material having an end tted in an opening in the tube sheet 11 and welded to the sheet as illustrated at 15. The tire tube is lined with suitable refractory material as illustrated at 17 and 118, and insulating material as illustrated at 19, and the re tube, together with the refractory materials form a combustion chamber in which combustion `gclurs during gas tired and oil fired operation of the o er. i

An annular body of insulating material 20 is positioned at the end of the fire tube as illustrated, and is supported by an annular casing 21 having a channel shaped across section and including an outwardly extending mounting iiange 22. The ange 22 is iitted on a series of bolts 23 which are welded to van annular ring 24 in turn welded inside the tire tube. The flange 22 abuts a sealing ring 25 and is secured in position by nuts 26.

At the front end of the boiler, the shell 10 is closed -by an inner front boiler door 30 in the form of a circul lar plate which may be secured to a shell flange 31 by any suitable means such as bolts and nuts, or by a hinge mechanism, or bywboth means. In addition to the inner door 30, the front of the boiler shell is closed by an outer dish-shaped boiler door 33 of generally cylindrical conguration and including an outwardly turned flange 34 which abuts against the inner door 30' and which may be secured to the boiler shell in a suitable manner. The

` ldish-shaped outer door and the inner door 30 define an Fig.- 3 is an enlarged fragmentary sectional view simi i air plenum chamber into which combustion air is drawn from atmosphereand from which the combustion air flows to the combustion chamber to support burning during gas `iiring and oil tiring of the boiler.

A cylindrical `burner tube 36 is aligned with an openL ing 37 in the inner door 30 and with an opening 38 in the refractory 18. The burner tube deiines a chamber in which the oil nozzle 67 is mounted, and also forms an air duct through which combustion air Hows from the plenum chamber to the combustion chamber. The burner tube is supported by an outwardly extending annular ange 39 welded to the tube and supported on the inner door 30 by machine screws 40. A sealing ring 4l is positioned between the flange 39 and the door 30 to prevent leakage of gases.

Combustion air is drawn into the plenum chamber through a `suitable opening 44 provided in the outer door 33 by means of a blower which consists of a fan wheel 45 mounted on the drive shaft of a fan motor 46. The motor 46 may be supported in any suitable manner, but

preferably is conveniently mounted on the door 33. Air drawn into the plenum chamber by the fan passes to the burner-lube 36 througha vaned dittus-er or bafe 48 including a plurality of circumferntially spaced vaines 49 supported at opposite ends respectively by an outer annulai vplate f50 and an inner annular plate 51; The 'outer plate 50 is secured to Vthe outer door 33, with an intervening sealing member 52, by machine 'screws' 53, andthe inner plate 51 is mounted on bolts v54 Welded to the burner tube -tlange 39. Nuts 55 secure the plate S1 in place, and a sealing ring -56 is positioned between the rings 51 and 39.

The end of the burner tube 36 -adjacent the combustionfchamber Tis provided with an air diffuser including 'a cylindrical side wall 58 Whichis iitted in the burner tube and an end Wall 59 which extends across the duct provided by the cylindrical -Wall 58 and the burner tube 36. The end wall 59 is provided with a central opening 60 and a plurality of circumferentially spaced, radially 'extending openings (not visible) Wit-h adjacent baffles or louvers 61 'which function to direct air passing through the idiiluser in a swirling pattern into the com'- bustion chamber to vprovide the proper air ow pattern and a uniform distribution .of combustion air in the combustion zone. v

K Gaseous tuel is supplied to the combustion chamber 'for gas tiring of the burner through a gas conduit 63 which is positioned in outer spaced concentric relationship 'to the burner tube .36. The gas conduit is Welded at one end to the kburner tube fla-nge 39', 4and is welded at the other tend to the channel vshaped casing 21. Theconduit 63, iwi-th the burner tube 36 and the casing 21, for-ms am annular .passage through which gas -ows from a supply z-pipe 64 4to the .combustion chamber. At theY end of the gas passage yadjacent the Vcombustion chamber, la ring 65 is secured insidethe casing 21 as by welding, and fo-nn's Aa restriction in the gas Apassage which creates a slight pressure .drop .suieient to cause an even distribution .of :the gas iowing from the annular gas passage to the combustion chamber. The gas supply pipe 64 leads from the conduit 63 through the .boiler .shell 10 for connection with a source .of gaseous fuel, and is provided with r.a suitable ow controlling valve 66 .of a conventional construction lwhich 4is electrically controlled to open and :close fthe [gas conduit, preferably ib'y `'a1-notorized operator.

`=Fuel oil is supplied to the combustion chamber for oil tiring ofthe fburner by means Vincluding a -nozzle `67 which utilizes fuel foil supplied by an `oil supply lpipe A68 and air under pressure Afor atoinizing the oil supplied by ian :air supply pipe 469 positioned'in outer spaced concentric relationship to the oil pipe 68.

- ,l The air supply pipe 69 is threaded into nozzle body 70 and extends outwardly 'from the nozzle t'o a :tting P71 which in turn has a connection with a ilexible conduit 72 `adapted yfor connection with a source iof atomizing under pressure. lf desired, an vair pressure gauge 7 3 maybe connected with thelitting 71.

At the `discharge end, Athe oil supply pipe 68 opens into nozzle tip 775 vand is supported therein. At the other end, the oil pipe is connected to a litting 76 in vturn connected to a supply conduit including a exible portion 77 and a rigid portion 78. The rigid conduit portion 78 is adapted for connection with a suitable source of fuel oil, and vis provided with a flow controlling valve :80 of a conventional type which is electrically controlled to `open and close the oil conduit -to control the -ow -of jfuel `oil to the nozzle, preferably by a solenoid means.

The oil nozzle 67 and the air vand oil supply pipes 68 and-69 are supported :in Van elongated tubular support 82 Twhich slidably Yreceives the inozzle 4body 70 and a collar 83on the ai'r pipe :.69 so that the -nozzle is mounted for movement from an advanced oil burning position illustrated :in :full "-lines in Fig. `l to a retracted position for gas tiring illustrated in broken lines in Fig. 1.

The tubular support 82 is mounted at the end adjacent port, and spaced radial legs 86 extending outwardly from the hub and having outer ends secured to the cylindrical ywall 5S of the ditluser. At the opposite end, the tubular support is litted in a collar 87 provided on a closure plate 88 which is mounted on bolts 89 extending from the diuser plate50. Y

The oil nozzle may be locked in either the advanced oil tiring position or the retracted position for gas firing by means including a pivoted latch member 91 supported on a plate '92 having an integral collar 93 secured on the atomizing air pipe .69. The pivoted latch member is thereby mounted for movement with the nozzle and the air and oil pipes during advance or retraction of the latter, and is positioned to cooperate with a locking pin 95 suitably secured .to the closure plate 88 and provided with a pair of spaced notches, such as that illustrated' at 96, one -for engagement by the hooklike Vend portion 91a of the latch member when the nozzle is in the Iadvanced oil tiring position land one for engagement by the latch member when the nozzle yis in the retracted position. f

In order to Vprevent the initiation of oil tired burner operation when the oil `nozzle is in the retractedY g'as ring position, an `interlocking control switch 98 lis secured to the outside of Athe closure plate 88, `and is Cp'r'ovided With a switch actuating plunger V-99 engag'eahle by the 4plate "92 on the air pipe when the -nozzleis inthe advanced oil ring position to close the switch to permit oil red `burner operation. When the Vnozzle is in the -retracted position for gas firing, the plate 92 frees the plunger 99 and the switch is lopened to prevent oil fired burner operation, as will be explained in more detail prmently in describing the electric circuit.

Gas tired Iand oil red operation of the burner apparatus `described lmay be initiated by a conventional electrically controlled ignition system ,generally designated 100 in the wiring diagram of Fig. 4 and, as seen in Fig. 1, including -a gas tired pilot burner 101 and Aa suitable electric igniter 102. The gas burner 101 is in the form of an elongated conduit opening at one `end adjacent the combustion chamber and connected at the opposite end, exte'riorly of the mounting plate 88, to :a suitable pilot gas supply line 103. The electric igniter 102 is encased for =a portion of its length in suitable 1insulating means 104 and extends exterio'rly v.of the mou-nting plate 88 for connection with suitable wiring 105. The gas conduit 103 may be `connected with a supply of gaseous fuel and, as is conventional, mayinclude a solenoid operated pilot valve (not shown) forming a .part of the ignition system. The wiring 105 may be connected with a suitable source `ofelectric powerwhich conventionally includes `an ignition transformer (n'o't shown) vforming -a part Vof the ignitionsystem. v

In operation, the oil nozzle 67 is positioned in the advanced full line position of Fig. l for oil red operation of the boiler, closely adjacent the `combustion chambenin order that the nozzle will properly discharge the atomized oil and air mixture into the combustion chamber to insure proper burning of theoil. When the boiler is operated on gaseous fuel supplied through the conduit 63, the heat of the combustion may vbe suf iicient to cause coking or baking of the oil inthe passages of the nozzle 67 if the nozzle is left in the 'advanced oil firing position. Accordingly, the constructiondescribed permits retraction of the 'nozzle in a direction away'from the combustion chamber `to the broken line positionof Fig. 1 wherein 'the heat on the nozzle lis suiciently 1reduced to preventthe undesirable coking and baking re- Iferred to. Tests have been made, using thermocouple's to ascertain the heat on Vthe nozzle,wh^ich clearlysildicate the temperature reductions atthe lnozzle fat various retracted positions. The tabulationgiven lbelovtfis Temperature at the nozzle tip in degrees Fahrenheit u Retractlon oi oil nozzle from oil burning position,

inches From the tabulation above it will be seen that retraction of the nozzle at least 5 inches from the oil burning position places the nozzle in a relatively cool temperature zone of vabout 215 F., about 115 cooler than in the oil ring position, wherein coking and baking of the oil in the nozzle passages cannot occur. Other tests conducted on larger and smaller boilers show that in these also a 5 inch retraction of the nozzle is suilicient to prevent undesirable coking.

In addition to providing for retraction of the nozzle from the advanced oil tiring position to the withdrawn gas tiring position, the mounting means described above also permits removal of the nozzle and the supply pipes 68 and 69 completely from the tubular support 82 so that the nozzle is accessible exteriorly to permit maintenance and cleaning. If desired, the outer door 33 may beprovided with a conveniently located bracket on which to hang the nozzle structure outside the plenum chamber without the need for disconnecting the flexible air supply conduit 72 or the flexible oil supply conduit 77 while cleaning. y

As seen lin the electric circuit diagram of Fig. 4, a

gas-oil selector switch is provided to selectively obtain either gas tired or oil iired operation of the boiler, The selector switch includes two movable contacts 111 and 112l mechanically connected for `joint operation under manual control. The movable contact 111 is adapted for, closure with la stationary contact 113 in the position illustrated in Fig. 4 or to contact a stationary contact 114, whilethe movable contact 112 cooperates with a stationary contact 115 when positioned as illustrated or with a stationary contact 116. As illustrated, the electric circuit includes, in addition to the elements already referred to, a switch means 117 which is representative of one or more automatically operable limit control switches responsive to upper or lower limits of operating conditions to either open or close the circuits automatically. Typical of such controls are water level, pressure, and temperature controls. Also, the circuit includes a switch means 118 which is representative of one or more manually operable control switches for controlling burner operation at the will of an operator, such as a manually operable burner switch for initiating boiler operation.

In operation, in'order to obtain gas iired boiler operation with the limit control switch 117 and the operating control switch 118 closed, the gas-oil selector switch is moved from the position illustrated in Fig. 4 to a position in which the movable contact 111 engages the stationary contact 114 and the movable contact 112 engages the stationary contact 116. With the selector switch thus positioned, a circuit is completed from a suitable source of electric power through a wire 120, the control switches 117 and 118, the movable contact 111, the stationary contact 114, -a wire 121, the movable contact 112, the stationary contact 116, -a wire 122, the electric gas valve 66, and a wire 123 back to the source of power to energize the operating means lfor the gas valve to open the valve, admitting gaseous fuel to combustion chamber. At the same time, a circuit is completed from the movable contact 111, through stationary contact 114, a wire 124, a wire 125, and the ignition 100 to energize the ignition system. Simultaneously, a circuit is completed from the wire 124 through a wire 126 and the motor 46 to energize this motor thereby driving the fan 45 to supply combustion air to the combustion chamber. The` ignition system functions to admit gaseous fuel to the pilot burner and to ignite such fuel, and the pilot burner in turn ignites the main supply of gaseous fuel. lIt will be seen lthat in obtaining gas red burner operation in this fashion, the interlocking control switch -98 which is responsive to the position of the oil nozzle is by-passed in energizing the gas valve, the ignition system and the blower motor, so that the condition of the interlocking control switch is of no consequence to this operation.

In order to obtain oil tired operation of the boiler, the gas-oil selector siwtch is positioned as illustrated in Fig. 4, completing a circuit through the movable contact 111 the stationary contact 113, a wire 127, the control switch 98, the wire 126 and motor 46 to energize the motor, driving the fan to supply combustion air to the combustion chamber. At the same time, a circuit is completed through the wire 127, and the Wire 125 to energize the ignition system 100. Also, a circuit is completed through the wire `125, the wire 124, the wire 121, the movable contact 112, the stationary contact 115, and a wire 128 to energize the electric oil valve 80, opening the oil supply conduit 77 to permit the flow of fuel oil to the burner nozzle. Thus, it will be seen that Ioil tired burner operation requires closure of the control switch 98, and thereby requires that the nozzle be positioned in the advanced oil burning position in order to obtain energization of the motor 46, the ignition system and the oil valve 80. Accordingly, oil fired burner operation cannot be initiated if the oil nozzle 67 is in the retracted gas ring position.` This serves to prevent an attempted oil red burner operation unless the oil nozzle is properly positioned for such operation.

It should be understood that the boiler operating control circuit illustrated :in fFig. 4 is a simpliiied circuit for purposes of clarity in describing the interlocking control switch 98, and in actual practice the circuit will include additional controls not illustrated such as the limit controls represented at 117, the operating controls represented at 118, starters or the like for the motor 46 and program controls in the ignition system which have not been illustrated in detail.

We claim:

1. In a burner apparatus for alternatively burning liquid or gaseous fuel, means forming a combustion chamber open at one end for admitting fuel and air to support combustion, a burner nozzle positioned centrally in the open end of the combustion chamber for discharging liquid fuel in an atomized state into the combustion chamber, an air conduit disposed concentrically around the burner nozzle for discharging combustion air into the open end of the combustion chamber, a gas conduit disposed concentrically around the air conduit for discharging gaseous fuel into the open end of the combustion chamber, means mounting the burner nozzle for movement between a rst, advanced position adjacent the open end of the combustion chamber for burning liquid and a second retracted position away from the open end of the combustion chamber during gas tiring, a fan for delivem'ng combustion air to the air conduit for gas tiring and liquid firing, an electric motor for driving the fan, an electrically controlled liquid valve controlling the flow of liquid fuel to the burner nozzle, an electrically controlled gas valve controlling the ow of gaseous fuel to the gas conduit, electrically controlled ignition means for initiating gas firing and liquid firing, circuit means including vsaid motor,l said valves, said ignition means and a selector switch selectively Vpositionable alternatively energizing said liquid valve, said motor and .said ignition means for liquid iin-ing or said gas valve, Vsaid motor and said ignition means for gas lining, .and switch means in said `circuit means responsive to the position ofthe burner nozzle for preventing energization of the liquid valve, the motor andthe ignition means when the selector .switch is positioned lfor liquid firing and :the burner nozzle is in the retracted gas ring position, Y

2. VInra burner apparatus for `burning either gas or oil, means forming a combustion chamber, a conduit positioned to .discharge gaseous fuel into the combustion chamber for gas firing of the burner, an oil burner nozzle positioned adjacent the combustion chamber for Idischarging atomized fuel oil into the chamber for oil iii-ing of the burner, means mounting the oil nozzle for movement from an advanced position adjacent the Vcombustion chamber for oil Afiring to a retracted position spaced from the combustion chamber to reduce the heat on -the nozzle during gas firing, an electrically energizable gas valve vcontrolling the lflow of gaseous fuel tothe gas conduit, an electrically energizable oil valve controlling the flow of oil to the nozzle, electrically energizable ignition means Yfor initiating gas firing and oil firing, an electric circuit including said valves and said ignition means, switch means in said circuit selectively positionable for alternatively energizing either said gas valve and said ignition means for gas firing or said oil valve and said ignition means for oil tiring, and 'a switch in said circuit responsive to the position of the burner nozzle for preventing energization of the oil valve and .ignition means when the selectively positionable switch means is positioned for oil firing and the burner nozzle is in the retracted `gas ring position.

3. In a burner apparatus for burning `either gas or oil, means forming a combustion chamber, a conduit positioned to discharge gaseous fuel -into the combustion chamber for gas firing of the burner, lan oil burner nozzle positioned adjacent the combustion chamber Vfor discharg- -ing atomized fuel oil into the chamber for oil firing of the lburner, means mounting the oil nozzle 4for movement lfrom an advanced position adjacent the combustion chamber for oil iiring to a retracted position spaced from the combustion chamber to reduce the heat on the nozzle during 'gas tiring, a fan for delivering combustion air -to the combustion chamber for gas ring and oil tiring, an electric motor for driving the fan, an electrically energizable gas lvalve controlling the flow of gaseous .fuel tothe gas conduit, an electrically energizable oil valve controlling the ow .of .oil to the nozzle, an electric circuit including said motor and said valves, switch means in said circuit se.- lectively positionable for alternatively energizing said gas valve and said motor for gas firing or for energizing said oil valve and said Vmotor for oil iiring, and a `switch in said circuit responsive to the position of the burner nozzle for preventing energization of the oil valve and the motor when said selectively positionable switch means is positioned for oil Vfiring and the burner nzfZle is Qin tht/.1o -tracted gas ring position. Y Y' Y 4. In a burner apparatus for burning either Oil or gas, means forming a combustion chamber, a conduit posi; tioned to discharge Vgaseous fuel into the .combustion chamber for gas tiring .of the burner, an Aoil .burner nozzle positioned in an opening to the combustion chamber for discharging atomized oil linto the chamber for oil tiring of the burner, a fuel oil supply ,conduit having one end connected to the o il nozzle for supplyllgl thereto, means slidably supporting the oil nozzle and toil conduit for retraction from an advanced position .wherein the nozzle is immediately adjacent ,the combustion for oil ring to a second position wherein the nozzle 4`is withdrawn and spaced from the combustion chamber dub ing gas firing to reduce vthe heat on thenozzle ,andthereby reduce coking of oil in the nozzle, and means for Ylocking the oil nozzle and `oil conduit in either position, A cornprising, a latch `member support mounted for Amovement with the .oil conduit, a pivoted latch member :on the latch member support, and a'latch .pin positioned alongside the path of the pivoted latch member lwhen moved with the oil conduit, and having latching notches Atherein at spaced positions for engagement by the latch-member respectively when the nozzle and conduit are .in :the advanced and retracted positions.

l References .Cited in the file of this patent UNITED STATES PATENTS

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