US1868051A

US1868051A - House heating system

Info

Publication number: US1868051A
Application number: US279634A
Authority: US
Inventors: Henry L Doherty
Original assignee: COMBUSTION UTILITIES CORP
Current assignee: COMBUSTION UTILITIES CORP
Priority date: 1925-01-22
Filing date: 1928-05-22
Publication date: 1932-07-19
Anticipated expiration: 1949-07-19

Description

July 19, l932. H. DOHERTY HOUSE HEATING SYSTEM Original Filed Jan. 22, 1925 2 Sheets-Sheet 1 Svwemtoz HENRY L, DOHERTY m WW July 19, 1932. H. L. DOHERTY 1,868,051

HOUSE HEATING SYSTEM Originai Filed Jan. 22, 1925 2 Sheets-Sheet 2 vwewtoz HE/VR) L. DOHERTY 351 /1/5 flttol/WJ Patented July 19, 1932 UNITED STATES PATENT OFFICE HENRY L. DOHERTY, OF NEW YORK, N. Y., ASSIGNOR TO COMBUSTION UTILITIES COR- PORATION, OF NEW YORK, N Y., A CORPORATION OF MAINE HOUSE HEATING SYSTEM Original application filed January 22, 1925,- Serial 110. 3,907. Divided and this application filed Kay 29,

1928. Serial The present invention relates to fluid fuel heating systems. More particularly the invention relates to domestic furnace burners and combustion controlling apparatus. This invention wasoriginally described in my application Serial No. 3,907, filed Jan. 22, 1925, of which this is a division. This original application has matured into U. S. Patent No. 1,819,459, dated August 18, 1931.

It'has been proposed to operate systems for heating houses, raising steam, and like purposes, automatically, the fire under the boiler being controlled automatically by a thermostat or by means responsive to the pressure in the boiler, or in other ways in order that the furnace, or furnace and boiler, should require a minimum of attention. Certain of the automatic systems just referred to burn gas, oil, or coal, but the majority of the features of the present invention have to do with the use of gas or oilseparate'ly and jointly.

.The automatic gas heating systems have been handicapped by the high cost of furnishing gas for domestic heating. Such a. system must be designed to furnish enough heat for the coldest days of the year. The gas company must therefore provide equipment including gas generating plant and auxiliaries as well as distributing mains, regulators, meters and the like, for supplying the large occasional demand for heating gas and then permit the equipment forthis purpose to be idle most of the time. Therefore if the gas for house heating and the like is charged its proper part of the fixed charges incurred in its manufacture, the cost of heating entirely by gas becomes too high to be considered except by those having unusually large incomes.

On the other hand, the domestic oil burning systems have been limited to the use of a relatively high priced quality of oil. Also, they often give off an unpleasant odor. Moreover, both the gas systems and the oil systems have been relatively expensive to operate and complicated in construction as compared with coal burning systems.

One object of the invention is to provide apparatus for burning fuel in a domestic furnace by which a relatively expensive and readily inflammable fuel such as gas is used for the normal load heating purposes of the furnace with the supply of gas being limited to a fixed amount and when the demand for more heat is required than will be provided by the fixed amount of gas, it will. be supplemented by a relatively cheap and not easily ilflarlnmable fuel such as the cheaper grades o 01 A second object of the present invention is to improve the performance of automatic house heating systems and steam raising systems from the standpoint of the householder, or person in charge of the apparatus.

A third object of the present invention is to provide a combined gas and oil burning system having high eificiency and reliability.

Another object of the present invention is to provide an odorless apparatus for burning oil in domestic heating systems.

A further object of the present invention is to provide apparatus capable of satisfactorily burning heavier, and therefore cheaper oil, than is now commonly used in automatic house heating systems.

The novel features of the present invention are pointed out with particularity'in the appended claims.

The invention, together with further objects and advantages, will best be understood from the following description taken in connection with the accompanying drawings, in which Fig. 1 is a view of an apparatus adapted to operate in accordance with the present invention the view being partly diagrammatic, parts shown in section, and parts in elevation for purposes of illustration.

Fig. 2 is an elevation on a larger scale of the gas burner and gas controlling portion of the apparatus illustrated in Fig. 1, parts being shown in sect-ion.

Fig. 3 is a plan of a portion of the gas' burner illustrated in Fig. 2.

Fig. 4 is avertical, central section of the oil drawback device illustrated in Fig. 1.-

Fig. 5 is a plan of the oil burner illustrated in Fig. 1.

Fig. 6 is a section of the oil burner taken refractory material. '40

on the line 66 of Fig. 5, looking in the dimetal plate 16 placed in the lower portion ofthe furnace 12 and resting on the lugs 18 ordinarily used to support the grates. The sheet 16 is centrally apertured to receive the burner apparatus 14 which projects u into the lower portion of the furnace 12. pparatus 14 is mounted at one end of a flue or air box 20 which extends into the ash pit 22 of the furnace 12 through the ordinary doorway for removing the ashes.

- The burner apparatus 14 comprises a gas burner 26 and an oil burner 28, burner 26 being of annular or ringlike form having a central opening through which burner 28 projects. Gas burner 26, Figs. 2 and 4, includes a considerable number of

individual burner tips

30, 30 extending in a ring around its upper edge and has also a number of

tips

32, 32, adjacent the upwardly projecting tips 30, but inclined inwardly somewhat toward the center of the burner 26, so that flames from the tips 32 lie in position to strike the edge of and be drawn into a stream of atomized oil issuing from the centrally positioned oil burner 28. Surrounding the

tips

30 and 32 and extending upwardly above the level of the same is a hell or cylinder 34. Bell 34 may be of cast iron or of fire brick or like refractory material, or it may be cast iron lined with Resting on the upper edge of cylinder 34 is a spider 36 supporting a central plate or button 38, which is made of cast iron, or fireclay, and so positioned as to contact with and spread oil flame issuing from the oil burner 28 and insure the thorough mingling of the oil and oil flame from burner 28 with the gas and gas flame from burner 26. The upper edge of cylinder 34, moreover, is notched as illustrated at 39, Fig. 1, so that flame from

burners

26 and 28 may spread and issue from the cylinder 34 somewhat laterally as well as upwardly.

It is well known that not all types of boilers are equally as eflicient when fired by gas.

When the amount of hot gases passing through the boiler is small as compared to the size of the passages of the'boiler, the efficiency often suffers unless the heating surfaces receive heat by radiation. The apparatus according to the present invention is "therefore designed so that the flame produced in the firebox when using gas only may be made either luminous or non-luminous as required in order to obtain best efficiency with the particular type of boiler with which a given burner apparatus is to be used. Ac-

siderable percentage of their heating surface in position to receive radiation from a coal fire on the grate. Moreover, when the system according to the present invention is applied to a domestic type boiler, the space designed to be occupied by coal and ashes is available to receive heat by radiation from burner 26. It will be clear from the drawing that the active surface of the boiler is notreduced according to the present invention by refractory material placed against it to promote the combustion of the oil. Therefore, when the apparatus is adjusted to give a luminous "flame, the flame issuing from cylinder 34 radiates directly to all parts of the boiler surface which would receive direct heat or radiation from a coal fire. As it is good practice to burn fuel oil with a luminous flame, no attempt is made to provide means for ad usting the apparatus to a non-luminous flame when the oil is being burned.

According to the present invention, moreover, the cylinder 34 has a ring of apertures 40, 40 therein at a level slightly above the ends of the burner tips 30 whereby products of combustion may be drawn into the flame within the cylinder 34 to lengthen the flame and assist in improving eflicient combustion of theioil.

Great difficulty has been experienced heretofore in using fuel oil for domestic boiler furnaces because the amount of oil burned is comparatively small, the fuel often has a very high viscosity, and-is quite dirty. Accordingly, the oil does not feed uniformly to the burners and there is not sufficient combustion to maintain sufficiently high temperatures for proper combustion. In accordance with the present invention an ideal condition for burn-- ing heavy fuel oils is provided by burning gas within a refractory chamber to maintain a radiating surface which will readily ignite fuel oil. To this end the gas is used as the normal load fuel and is burned within the cylinder 34 in maintaining normal heat requirements of the boiler. When the requirement of heat from the boiler increases above normal, the oil 'is introduced through the burner 28. At this time the gas is burning at its maximum amount. Therefore the oil is introduced into a heated chamber and into a burning gas flame. When the combined combustion of the oil andgas has supplied the heat requirements of the boiler the oil will be cut ofi from the burner 28 before the gas is turned down in the burner 26, and accordingly the amount of oil being burned is sub? stantially uniform and is in suflicient amount to maintain an efiicient and ideally burning luminous oil flame. 4

The means for supplying gas and air to burner 26 and for regulating a flow of the in fine by a bracket 52. The device 50 has a mixing chamber 54 which opens into the flue 20 by way of passage 56 and which connects with the gas chamber 48 by an aperture or passage 58. The gas flowing through aperture 58 draws air through passage 56 and the air and gas after mixing in chamber 54 pass through the pipe 60 within flue 20 to the gas burner 26. In order that the flame of the burner 26 may be regulated as desired, a

needle valve 62 is arranged to govern the passage 58, valve 62 being projected as a pin or like form backwards through the wall of chamber 48 opposite passage 58 and being slidably mounted in the wall of the chamber 48. The outer end of the valve 62 is fixed to a cap 64 slidably mounted on

pins

66,66 fixed in lugs 68 on the exterior of the device 50..

The cap 64 when moved up against the end of the device covers the air passage 56 and shuts off thefiow of air to the mixing chamber 54. At the same time cap 64 carries the valve 62 into such-a position that it closes the gas aperture 58. Therefore by moving the capv 64 in one direction or the other on pins 66, the flow of air and gas to the burner 26 may be regulated as desired and "the cap 64 is so arranged with respect to the valve 62 and the intake end of the air passage 56 that a desired percentage mixture of gas and air is maintained in the pipe and burner 26. The air admitted to mixing chamber 54 through passage 56 is primary air in accordance with the ordinary nomenclature of the art. A

damper 70 is arranged to control the ad.- mission of air into the flue 20 through opening 71, damper 70 bein operated through link 72 connected to a bell lever 74 which operates the cap 64 andneedle valve 62, bell lever *?4 being pivoted to a bracket 76 fixed to the part 52. One end of bell lever 74 is connected to rod 78 and automatic means is provided for operating the rod 7 8 in accordance with the need for heat to be delivered by the system of which the burner apparatus P 14 is a part.

If the burner apparatus is part of a house heating system, the automatic means just mentioned includes a thermostat 80 placed in the room whose temperature it is desired to control. Thermostat 80 includes two fixed

contacts

82 and 84, respectively. It also includes a movable contact arm 86, the position of which is controlled by the temperature of the room on account of the expansion and contraction of the curved metal portion 88. 90 is an electric motor supplied by current through wires 92 from the power line 94. The circuit of motor 90 is extended through

wires

96, 98 and 100 to thermostat 80, wire 96 being normally connected to fixed contact 82, wire 98 being normally connected to the arm 86 and wire 100 being normally connected to fixed contact 84. Wire 100 is also connected to an automatic thermbstat or circuit closing device 102 by means of a branch 101 while wire 98 is interrupted at point 104 and connected to the arm 86 through the loop 99 running through the device 102.

The parts of the flue controlling devices are illustrated in Fig. 1 in the position assumed by them when the burner 28 is inactive. The room whose temperature is controlled by thermostat 80 will therefore be cooling off. a Assuming that the temperature of the room has declined to the lower limit desired, the arm 86 of the thermostat 80 strikes'the contact 82. The motor 90 is so constructed that each time its circuit is closed, it turns its driving shaft 180 degrees and then stops. having been closed as just mentioned, the motor thereupon rotates its shaft 180 degrees from the position illustratedin Fig. 1. The motor 90 and thermostat control therefore just described are similar to those used in the known Honeywell house heating system and form no part of the present invention. The details of motor 90 are therefore neither disclosed nor claimed herein.

' The crank or arm 106'fixed to the shaft of motor 90 is thrown down by the movement of theomotor just mentioned and the spring 108 placed in tension. Spring 108 connects the arm 106 with cord 110, cord 110 running over

pulleys

112, 112 and connecting to a cross head 114 carrying the rod 78, previously mentioned. The downward pull on the spring 108 tends to lift the cross head 114 by virtue of the pulleys 112 and thereby open the gas valve 62 and passage 56 to bring up the gas flame of burner 26. When, however, the temperature of the room is at the upper desired limit, arm 86 of the thermostat 80 strikes the fixed contact 84 again closing the circuit of motor 90 and causing said motor shaft to execute another half The circuit of motor 90' turn or rotary movement of The arm .Fig. 1, the tension of spring 108 being re laxed and the arm 78 permitted to drop to close off the flow of gas to burner 26.

However, according to the present invention it is preferred that the gas flame be increased gradually and turned off gradually, and for this purpose a retarding means is connected to the cross head 114, said retard-' ing means comprising a rod 116 fixed to cross head 114 and extending into the dash pot cylinder 118. Within the dash pot 118, rod 116 is connected to a weighted piston 120, (Fig. 2), the dash pot 118 being filled with light oil, preferably a mixture of kerosene and light lubricating oil, and the ends of the dash pot above and below the piston 120 connected by pipe 122 (Fig. 1), having a retarding valve 124 therein. When the spring 108 has been tensioned by the motor 90 as above described, the tension of the spring is resisted by the weight of piston 120 and the motion of the piston is moreover retarded by the oil in the dash potso that the cross head 114 carrying the operating rod 78 can rise only gradually and the fuel to burner 26 is turned on gradually. Similarly, when the motor 90 is turned into the position illustrated in Fig. 1 so that the spring 108 is relaxed, the weighted piston 120 gradually carries the rod 78 downwardly and the 'movementof' rod 78 correspondingly shuts ofl the flow of as to burner 26, the movement of the piston being resisted by oil flowing through the valve 124. It will be seen that the parts of the gas controlling apparatus just described are illustrated in Fig. 1 in the position assumed by them shortly after the motor 94 has turned the arm 106 to the uppermost position, thereby relaxing spring 108.

The means for supplying oil to burner 28 and forstarting and stopping, the flow of the same according to the present invention will now be described. The movable cross head 114 carries an insulated contact 126. A co-operating contact 128 is mounted on and insulated from the fixed standard 130, the latter mounted on dash pot cylinder 118. Contact 126 strikes contact 128 at the upper limit of travel of cross-head 114 as it moves upward under the influence of spring 108 as previously described. Also, the

contacts

126 and 128 separate as soon as cross head 114 starts downwardly when the tension 011 spring 108,has been relaxed.

Contacts

126 and 128 are inserted'in the circuit of motor 1 132 which drives a pump 134 furnishing oil to oil burner '28. The circuit of motor 132 is taken 011' the power line or circuit 94 through lead 136, passing

throughcontacts

126 and 128 to' the casing of motor 90 and thence through lead 137 to= an emergency circuit opening device 140 and thence by lead 142 to the casing of motor 132 itself from which it returns to the other side of power circuit 94 by lead 144. From the foregoing, it will be seen that the oil pump from that of oil pump motor 132 and the shafts of the motor and pump are directly coupled in alinement. Also intermediate oil pump 134 and motor 132 is an air pump- 136 furnishing air for atomizing oil from pump 134 in burner 28. The casing of air pump 136 is fixed to the casings of motor 132 and pump 134 and its shaft is in alinement with those of the motor and oil pump, motor 132 and pumps 134 and 136 forming a unitary structure. Oil flows to pump 134 through pipe 138 and is forced to burner 28 through pipe 145. Air pump 136 delivers air for atomi-zing the oil through pipe 24 previously mentioned, pipe 24 running between pump 136 and burner 28.

\Vhen pump 134 has been operating to force oil to burner 28 and is then shut down by one of the automatic controls previously described, unless means were provided to prevent it, oil would stand in the upper part of the burner 28 when not operating. As the upper part of burner 28 is surrounded by a ring of gas jets from

burner tips

30 and 32, oil so standing in burner 28 would be carbonized by the heat of flames and would soon clog burner28. To prevent carbonizing of oil in burner 28 a draw-back device 146 is provided in pipe 145 intermediate pump 134 and burner 28. Device 146, details of which are set out below, acts automatically to cut 011 pump 134 from burner drops upon shutting down of pump 134 and device 146 then acts to suck back into its own casing some of the oil in pipe 145, so that the oil in'burner 28 is drawn down below the level at' which it can be carbonized by heat from burner 26. A

The two devices, 102 and 140, at the burners and on the boilers, respectively, previously mentioned as formingpart of the system according to the present invention operate only under abnormal conditions. Thermostat device 102 comes into operation upon the extinction of pilot light 46. When the thermostat in device 102 i s maintained at normal temperature by the heat from pilot light 46 contacts are made to connect the two halves of loop 99 so that wire 98 acts as a continuous wire leading to thermostat arm 86 as previously described. When,

however, device 102 cools below a certain temperature it connects wire 101 with the part of loop 99 running to point 104. The action of device 102 when it cools down therefore is the same as that of thermostat 80 when the thermostat is heated up and upon the connection of wire 10-1 with point 104 by device 102, motor if not already in that position turns arm 106 to point upward, thereby first cutting off the oil, if the pump is'in operation and then gradually cutting 013' the gas.

Device 140 controls only the oil-pump motor 132. When the temperature or pressure within the boiler 10 exceeds certain desired limits, device 140 disconnects wire 142 from wire 137, thereby interrupting the circuit of motor 132 and shutting down this motor and oil-pump 134. The oil to burner 28 is thereby shut off.

Secondary air as well as primary air for the gas flame is furnished through opening 71, as reviously mentioned. However, damper 0 governing opening 71 is opened substantially as far as the apparatus can do so before the oil pump 134 is started, a very small movement of

contacts

126 and 128 one way or the other being suficient to start or stop oil-pump motor 132. The damper 70 is adjusted to give the proper supply of air for the maximum flow of gas to burner 26, while primary air for oil burner 28 is supplied through pipe 24, so that it is clear an additional supply of air is needed to furnish secondary air to burner 14 when oil as well as gas is being burned. For the purpose just mentioned there is provided a second air inlet aperture 310 in air duct 20, aperture 310 being closed by damper 312 except when oil is being burned. Damper 312 is illustrated as hinged at 314 to the outside of the top surface of duct 20 whereby this damper closes by its own weight. Of course, if the damper 312 were so placed that it did not close by its own weight some means would need to be provided to hold it normally closed. In order to open damper 312 when needed, a link 316 is connected to the unhinged end of the damper, link 316 being pivoted in turn to arm or lever 318. Lever 318 is pivoted at the end removed from link 316 to a fixed standard 320. Lever 318 lies above and is connected to a flexible operatingdiaphragm 322, diaphragm 322 being attached so as to close the upper end of cylinder 324 which is mounted on the duct, 20. A pipe 328 connects the interior of air pipe 24 with the interior of cylinder 324 beneath diaphragm 322. With this arrangement the same air pressure is maintained in the cylinder 324 which exists in the pipe 24. Therefore when the air pump 136 is put into operation the diaphragm 322 will be actuated to open the damper 310 to admit secondary air. I

At the instant the motor 132, pumps 134 and 136 have been shut ofi by the automatic controls, the burner 28 is still full of oil and, being surrounded by a ring of gas flame, oil in the upper part of burner 28 would soon carbonize and prevent the operation of the burner when the oil is next pumped into it.

To prevent the carbonizing of the oil in burn- .145; and passes into a chamber 330, the top of which is formed by an internal horizontal web 332. The air for burner 28 is pumped thereinto from the pump 136 through the pipe 24, pipe 24 connecting with the burner through threaded ofiset 334 connecting with the air chamber 336 lying within the burner 28 above the web 332. From the chamber 336 the air is conducted upwardly through a nipple 338 leading out of the chamber 336 into a burner cap 340. A pipe 342 extends through the web 332 and runs centrally through chamber 336 and nipple 338 to conduct oil to within the burner cap 340. At the upper end of pipe 342 is a nozzle 344 co-operating with the cap 340 and producing oil flame. Cap 340 has a central upwardly tapering opening 346 therein and the upper end of nozzle 344 tapers upwardly on the line parallel to the taper of the aperture 346 and projects within this aperture, but nozzle 344 is spaced from the cap 340 so that air may pass up around the nozzle through the aperture 346. Nozzle 344 has a central aperture 348 leading upwardly and delivering oil "within the aperture 346 so that air and oil are thoroughly commingled in passing through the upper portion of aperture 346. In order to further atomize the oiland thoroughly mix it with the air, the upper end of the opening 348 in the oil nozzle 344 is enlarged and cap 340 has also a series of air jet apertures 350 arranged around the centhe centre of cap 340 so that the air jets from the apertures 350 produce a swirling action of the flame.

The operation of the apparatus disclosed herein will be obvious to those skilled in the art from the foregoing description. For convenience of reference however the opera tion of the apparatus according to the present invention will be summarized as follows:

' The fuel burning and combustion regulating apparatus of the present invention is applied specifically to a domestic heating furnace of the type usually employed for burning coal. The burners and the controlling apparatus are preferably built up in a unit construction and located immediately adjacent the furnace. The automatic control for the burners and the regulating apparatus consists of a thermostat which should be placed in a room of the house whereby the temperature of this room will be used for controlling the heating of the house. If the room in which the thermostat is located has the nor-- mal temperature desired, say, for example, 70 F., the burners will be turned off and nothing but the pilot burner 4.6 willbe burning. At the time the temperature falls below 70 the thermostat 80 will operate to close the power circuit in the motor 90 and at this timethe dash pot mechanism 118 will be operated by the motor to adjust the needle valve 62 .and air valve 64 so that the gas will be introduced into the mixing pipe 60 and flow to the gas burner 26. The dash pot mechanism is so arranged that the gas will be gradually increased until a predetermined maximum or fixed demand of gas has been reached. When the maximum has been reached

electric contacts

126 and 128 mounted on the dash pot mechanism will be made and the air and oil pump motor 132 will be set in operation to supply oil and, air to the oil burner 28. By the time the gas burner has gradually increased the amountof gas burned to its maximum, the refractory chamber surrounding the gas burner will be highly heated and therefore when the oil is in: troduced into the burner 28, it will be atomized into the gas flame from the burner 26 and into the heated refractory chamber 34. At the time the motor 132 is set into opera-- tion the oil will be supplied to the regulating mechanism 146 in a fixed amount, and the amount of oil flowing to the burner will be uniform as long as the oil burner continues to operate. The oil is supplied to the burner' 28 in a measured quantity, the measuring being accomplished by the pump 134, so that the oil flows through a comparatively large pipe to a burner having a comparatively large discharge orifice. When the gas is turned on by the motor 90 the air valve in the duct 20 is gradually opened as the supply of gas increases. This furnishes the primary and secondary air for the gas flame. When the oil is turned on primary air is introduced by the pump 136 and the secondary air is introduced into the duct 20 through the damper 310 by the regulating diaphragm 322 which is operated by the air pressure used in the oil burner.

While the oil is burning the gas isburning at its maximum'demand and the oil burns at the predetermined fixed quantity which is normally used when burning oil. These two combined fuels then continue to burn until the heat supplied by the boiler is sufiicient to raise the temperature "in the room of the house in which the thermostat is situated to normal temperature. Then thermostat 80 will make such an electrical contact that the motor 90 will be operated to set the dash pot mechanism in a position for turning off the oil and gas. Immediately upon the operation of the motor for turning off the oil and gas the electrical contact for controlling the circuit of the oil and air pump will be broken, and the motor will stop. As soon as the oil pressure in the feed line and the air pressure in the air line have been decreased the suckback device 146 will act to draw back the oil from the burner 28 and the damper 310 will be closed. The gas however will not be cut off immediately, but the supply of gas will be gradually reduced by the dash pot until it will be entirely out off unless in the meantime the room temperature has fallen so that the thermostat 80 will be operated to actuate the motor for again turning on the gas. In this way the gas is used as the normal load fuel to be gradually increased and decreased as the heat demands require. When however the temperature in the house is such as to require more heat than can be supplied by the burning of the gas alone, then the oil will be turned on to supplement the gasin supplying the heat demands. The temperature and pressure controlling device 140 is used to prevent the development of an excess temperature in a water boiler or an excess steam pressure in a steam boiler whereby the burning of fuel may be checked rather that injuring the boiler. The safety device 102 which is connected with the pilot flame is arranged to operate at the time the pilot flame is extinguished in order to cut off both the oil and gas to prevent them from being supplied to the furnace when the fuel is not ignited or burning.

It will be seen that the present invention provides a heat system particularly adapted although not limited to household heating purposes in that it is fully automatic, but

safe and rugged in operation. Moreover, the system operating according to the present invention burns fuel oil without odor and with. little noise. While the foregoing disclosure is specific in character the appended claims are not to be construed as limited to details of said disclosure except as to details positively included in the claims.

Having described my invention, I claim:

1. A combined. oil and gas burner comprising a refractory cylinder, an atmospheric type gas burner adapted to form a ring of gas flame within said cylinder, and an oil burner arranged to project atomized oil within said ring of gas flame.

2. A combined oil and gas burner comprising a refractory cylinder having apertures in its lower portion, an atmospheric type gas burner adapted to form a ring of gas flame within said cylinder, and an oil burner arranged to project atomized oil within said ring of gas flame.

3. A combined oil and gas burner comprising an oil burner, a gas burner'surrounding said oil burner, a refractory cylinder surrounding and extending above said gas burner, and a refractory spreader supported above said oil burner.

4. A combination oil and gas burner including an annular gas burner having a ring of orifices in its combustion face, and an oil burner having an atomizing nozzle located centrally of the gas burnerycertain of the gas burner orifices being inclined inwardly toward a point in front of the oil burner nozzle.

5. A combination oil and gas burner including an annular gas burner, a ring of orifices in the combustion face of the gas burner, certain of said orifices being inclined inwardly, an oil burner located centrally with respect to the gas burner orifices, a conduit for supplying air to burn the fuel, and means controlling the admission of air to said conduit. v

6. A combination oil and gas burner including an annular gas burner, a ring of orifices in the combustion face of the gas burner,

a portion but not all of said orifices being inclined inwardly, and an oil burner located centrally of the gas burner.

7. In combination with a furnace combustion chamber having an opening therein, means for delivering an atomized jet of fluid fuel and air with a whirling motion to said opening, and an annular burner arranged to direct a flame across the path of said et from all sides thereof at an angle to the axis of rotation of the jet.

8. In combination with a furnace combustion chamber having an opening therein, a gas burner adapted to project a ring' of gas flame within said chamber, an oil burner arranged to project an atomized jet of oil and air within the ring of flame from said gas burner, a draft conduit extending from said opening'to a point at one side of the furnace, and means for adjusting the supply of air to said chamber in accordance with the fuel supply.

In testimony whereof I aifix my signature.

HENRY L. DOHERTY.