US2118479A - Submerged combustion burner - Google Patents

Description

May 24, 1938. 'r. 5. SEE ET AL SUBMERGED COMBUSTION BURNER Filed March 24, 1938 5 Sheets-Sheet l vlllAiF t! OOOOOOOOOO 3 Sheets-Sheet 2 T. 5. SEE ET AL SUBMERGED COMBUSTION BURNER Filed March 24 1938 May 24, 1938.

May 24, 1938. T. 5. SEE ET AL SUBMERGED COMBUSTION BURNER I Filed March 24 1938 5 Sheets-Sheet 5 \H o E i m M Qnm mmw .2, mmm Nw$ gal 9% 6% k & @Qn a \Nm EN 1 1 mum HF g \i i Patented May 24, 1938 UNITED STATES PATENT OFFICE SUBMERGED COMBUSTION BURNER Application March 24, 1938, Serial No. 197,940

30 Claims.

This invention relates to an improved method of submerged combustion and a novel submerged combustion burner capable of practicing the method, and has for a principal object the provision of a burner, adapted to perform the novel method, which is rugged and durable in construction in order to withstand the severe usage to which submerged combustion burners are subject, is efficient and economical in operation, and at the same time comparatively simple in design and construction.

Submerged combustion burners of the type which form the subject matter of this application are used for heati purposes and accordingly are to be contrasted with burners of the oxyacetylene or blow torch type. They may be employed in heating tanks, such, for example, as hot water tanks, or they may be employed for such severe purposes as heating pickling baths containing sulphuric acid. A burner of this type, in order to be capable of universal application, must be rigidly and durable constructed, and yet in order to meet the required conditions of performance must additionally be suiilciently simplified in construction that it will operate economically over an extended period of time without breakdown. Additionally, in case of breakdown, it must be so constructed that it can be easily, cheaply and conveniently repaired.

It has been found that in order for burners of this type to be entirely satisfactory they must be capable of being placed in position in a tank to be heated and allowed to remain there indefinitely without removal. This preferably entails 5 the feature of igniting and extinguishing them while they are in position within the tank, protectlng the vital parts from corrosion and other destructive forces, and includes problems of cooling, circulation and the like. Above all, in order to be commercially acceptable, such burners must face and overcome all operation, maintenance and cost problems.

Today'there are no combustion burners available which satisfactorily meet the strict require-- 45 ments outlined above, although several complex and comparatively delicate submerged combustion burners have been designed and are in limited use. Such burners, however, are subject to numerous objections which have retarded their 50 commercial development and have prevented their extensive adoption. They get out of repair easily, require adjustment frequently, or in many other respects fail to meet the standards required of a successful submerged combustion burner.

with the foregoing desiderata in view, an important feature of the present invention resides in the provision of an improved and novel burner which may be placed in position within a tank. allowed to remain there as a more or less perm'anent fixture, and will operate satisfactorily at all times and under all conditions. Another important quality of the invention consists in the fact that the burner is capable of withstanding the severe usage to which it is subjected. Another feature of the invention which contributes to accomplishment of the recited objects resides in the inclusion in the improved burner of ignition means which permits the burner to be turned on and off automatically or manually and operates efliciently under all trying conditions.

Another feature of the invention resides in the provision of a burner which is safe. Backflres and explosions in burners of this type are common and dangerous and any burner which meets the service requirements must be so constructed as to eliminate all hazard or tendency in these directions. A further feature resides in an improved method of admixing air and fuel within the burner in order to economize on fuel and produce high heating efliciency. Still another feature resides in the shape and arrangement of the burner, which comprises the characteristic of being constructed in the shape of an L. The stem of the L is adapted to be disposed vertically along the side wall of a heating or pickling tank and the base of the L is arranged to extend more or less horizontally along the floor of the tank. Attached to the upper extremity of the stem are the connections through which the fuel and ignition devices are admitted to the burner. These connections conveniently overlie the wall of the heating tank, and although the burner as thus balanced in position is a more or less permanent fixture and part of the tank, it can nevertheless be conveniently removed as a unit.

A still further feature of the invention which contributes to the accomplishment oi the recited objects resides in the provision of a burner, the parts and arrangements of which are such that the likelihood of parts burning out or wearing away is largely eliminated. Still further features and objects of the invention will become apparent from a reading of the following specification in the light of the accompanying drawings, in which Figure 1 shows in side elevation a portion of a liquid tank or reservoir with the burner in position, and its attendant control system schematically illustrated;

Figure 2 is a top plan detail view of the burner head shown in Figure 1;

Figure 3 is a view, similar to Figure l, of a heating tank with a burner and the attendant control system shown in outline;

Figure, 4 is a view in side elevation of the burner shown in Figures 1 and 3;

Figure 5 is a diagrammatic view or a heating tank showing several burners in position in a tank and the direction 01' circulation oi the liquid -heated and agitated thereby:

Figure 6 and Figure 7 are detailed views, in section, of two types of burners constructed in accordance with the present invention and embodying the principles thereof; and

Figure 8 is a view ci a burner plate arrangement taken along the line 8-8 of Figure 7.

Turning first to Figures 1 and 3, the burner is indicated generally by the reference numeral ill and is mounted within a tank I! containing a liquid to be heated, the surface 01 the liquid being indicated by the reference numeral it. At the right oi the tank, as shown in these figures, is located a control system by means of which the proper operation and functioning of the burner is regulated. Inasmuch as this system will not be claimed in this application but forms the subject matter of my copending application Serial No. 127,068, filed February 23, 1937, it will not be described in detail in the instant application, although in order to illustrate and disclose a complete working system and apparatus a brief rsum of its construction and-operation will be given. Although, as just stated, the burner and not the control system forms the subject matter of this application, the latter rather than the former will be first described in order to dispose oi the unclaimed subject matter at the outset.

Control system A compression unit I! has mounted upon one extremity 01' its rotating shaft an air compressing unit It, and upon its opposite extremity a gas compressor unit 20. Gas or other suitable fuel is supplied from an appropriate source through a conduit 22 which leads to the gas compressor. A governor 24 is included for the purpose oi controlling the gas supply so that its pressure is the same as that 01' the air supply, and to this end, in order to regulate the pressure, one side or the governor 24 is in communication, by means of a conduit 26, with a main air passageway 20 which connects with the air compressor I! through an oil separator 30. In the event that gas for operating the burner is available at a pressure sufliciently high to overcome the resistance due to the head 01 solution in the tank II, the gas main may be connected directly to the governor 24. On the other hand, if the gas pressure available is not sumciently high for this purpose the gas compressor 20 may conveniently be employed to develop the necessary pressure.

From the governor the gas is led to a valve structure 32 which is provided with two solenoid valves 34 and 38, one of which controls the how of gas to a pilot jet, as hereinafter described, and the other of which controls the main supply of gas to the burner. Both the stream of gas flowing to the pilot jet and the main gas supply flow through measuring orifices and control valves. The measuring orifice and control valve for the pilot gas are 38 and II, respectively, and for the main gas supply 42 and II. The orifice for the pilot gas is connected to a manometer 8 located within the instrument case 48, and the orifice l2 1 for the main gas supply is so arranged that a manometer'can be easily connected to connections 50. when and if desired.

From the solenoid valves 34 and 36 lines lead directly to the burner. The pilot gas flows through a pilot jet 52 located in the upper extremity'of the burner, hereinafter to be more fully described, and the main gas flows through a conduit 54 (positioned in the rear of the pilot gas tube as shown in Figure l and clearly shown in Figure 2) and thence into a main gas supply passageway 56, which also will be described more fully further on.

The air supplied by the compressor is also divided into two parts. A small amount of air called the pilot air is fed through a by-pass conduit ill to a pilot air supply line 62, whereas the main air line flows through the conduit 28 to the burner in the manner previously described. The air to the pilot supply flows through a control valve 64 and a measuring orifice 88, and connections may be included in the line 60 so that a manometer can be easily connected when desired in order that the flow of pilot air may be observed.

Turning now to the ignition control, the burner is provided with an igniter 10, the flow oi current to which is controlled by a constant current transformer 14 which consists of a three-pillar laminated iron core with a stationary low voltage secondary coil below and a floating l10-volt primary coil above, both of which are mounted around the central pillar. Any variations in line voltage within 25% above or below normal change the position of the primary coil but will not change the secondary ignition current. The current from the secondary coil of the transformer 14 to the igniter 10 also passes through a thermal element 16. The passage of the current through the thermal element 16 causes it to heat up and bend or expand to the right, as illustrated in Figure 1, actuating the pilot and main gas switches 18 and an. After an interval of sixty to ninety seconds from the beginning 01' the cycle the pilot gas switch 18 closes the circuit to the pilot gas solenoid valve 34, allowing the pilot gas to flow to the burner. After a further interval of ten to fifteen seconds the main gas switch I! closes the circuit to the main gas supply solenoid valve 36, allowing the main gas supply to flow to the burner. At the same time that the main gas supply switch 80 closes the circuit to the main gas solenoid valve 36, it also closes the circuit to a magnet 82. This magnet closes and locks the pilot and main gas switches in closed circuit position and at the same time moves the ignition switch 84 to open circuit position and locks it there. With this ignition switch in open circuit position the current to the transformer 14 is turned off. The control will remain in this position, which is known as running position, until the current to the control is cut off, when all switches will return to their initial position.

The temperature oi the liquid within the tank l2 may be controlled by a thermostat 88 which is immersed in the liquid, and any changes in temperature occurring in the latter tend to actuate a mercury switch 90 which controls the supply of current to the ignition control. The thermostat 88 may be adjusted to control the temperature of the liquid by means of an adjusting screw 92, and the igniting temperature for which the control is set may be indicated by a pointer 84 on a suitable scale 96.

the two gas In operation, a starting button III is pressed. thereby energizing the coil in the starting switch box III. Current is thereupon supplied to the compressor motor it and the ignition control. Air is supplied from the compressor il forcing the liquid from the inside of the burner and the combustion chamber and commencing agitation of the liquid in the tank. Assuming that the thermostatic switch Si is in closed circuit position calling for heat, current iiowsthrough the transformer 14. The igniter ill thereupon becomes heated and after sixty to ninety seconds the thermal element 16 has moved far enough to actuate the pilot gas supply switch 18, causing the latter to move to closed circuit position, thereby opening the pilot solenoid valve SI and allowing the pilot gas to flow to the burner. Approximately ten to twenty seconds after the pilot switch has closed the main gas supply switch it will move to closed position, opening the main solenoid valve 36 and allowing the main gas supply to flow to the burner. This gas will be ignited by the pilot flame in a manner hereai'ter more fully to be described. At the same time that the main gas supply switch 80 moves to closed circuit position the magnet 82 is energized, locking the instrument in running position with the pilot and main gas supply switches 18 and 80 in closed circuit position and the ignition switch 84 in open circuit position. This running position will be maintained until the thermostat 88 moves to open circuit position by heating of the solution in the tank, or until the apparatus is stopped by pushing the manually operated stop control button of the starting switch "it.

As long as the apparatus is running, air is forced through the liquid in the tank l2, aflording a constant agitation while the gas supply is turned on and off in accordance with the temperature requirements, this feature constituting one of the many outstanding characteristics of the system.

The burner As shown in Figures 1 and 3, the burner is L- shaped and is arranged with the stem of the L extending vertically along the side wall of the tank i2 and the base of the L lying horizontally above the floor of the tank. Inorder to observe more clearly the construction of the burner the type illustrated in Figure 1 will first be specifically described.

As shown in that figure, the burner proper comprises an outer, cylindrical, elongated, tubular casing 200 having concentrically'arranged within it a second tubular, elongated casing 204. The latter casing, which is the smaller one and lies within the larger or outer one, is mainly employed for ignition purposes. Pilot gas enters the tube through jet 82, hereinbefore referred to, which is in communication with the pilot gas solenoid valve ii. The jet 52 is arranged to extend downwardly from a burner cap 208 through an annular opening formed within a ring member 208 and terminates slightly above, but in close proximation to, the igniter Iii which, in the operation of the machine, is heated to incandescence by means responsive to temperature variations imparted by the bath or solution to the thermostat I8. As pilot air enters the upper portion of the burner it passes downwardlythrough the annular opening within the ring 208 into the inner or pilot chamber and admlxes with gas or other iuel flowing from the pilot jet 2. The velocity of the pilot air and gas through the inner chamber is comparatively low, and let it be observed that the cross-sectional area of the inner chamber, as defined by the cylindrical casing 2, is quite large as contrasted with the cross-sectional area of the pilot jet 52. As in all other features of the burner now being described, there is a real reason for these proportionate dimensions. Ordinarily there is a tendency on the part of a pilot Jet and the flame which burns at the Jet to destroy or burn out the metal of casing 204, or any other metal immediately nearby, and it has been found that by arranging the cross-sectional areas in the manner described and reducing the velocity of the pilot flame, there is a tendency on the part oi the latter to burn slowly down the center of the tube and not impinge too severely upon the walls of the casing 204, thereby reducing the likelihood of the easing's being burned out by the pilot flame. Furthermore, this floating or slow burning pilot flame entails other features and functions which will presently be described.

The main air supply which supports the combustion, or, perhaps it would be more accurate to say, supplies all of the air for the main combustion, passes through the supply pipe 28 and downwardly through the space defined between the inner casing 201 and the outer casing 200. This passage of air tends to cool the walls of the casing 204, within which is burning the pilot flame, as it moves downwardly through the burner and finally is discharged through openings 228 formed in a burner plate 222. As shown in Figure 8, the burner plate is an annular member which is disposed between the inner casing 204 and the outer casing 200, and is provided with numerous perforations through which the air passes and by which the stream of air is finely divided.

The main gas supply in the type of burner shown in Figure 1 enters the cap 206 of the burner through conduit 54 and passes downwardly through a main gas supply line 56 which is disposed in the annular space between the inner and outer casings 2M and 200, respectively. At its lower extremity the main gas supply passageway 56 is joined to a supply ring 224 which is located adjacent the burner plate 222 and directly within the path of the pilot flame emitting from the jet 52.

Thus, as the slow burning pilot flame reaches its point of exit from the inner chamber it impinges upon the gas leaving the supply ring 224 and mixes intimately with air passing through the openings 220 in the burner plate 222. In this manner the combustible mixture is formed at a point below the liquid level ll of the tank and also below the extremity of the inner and outer chambers. Combustion ensues as the mixture, having been ignited by the pilot flame. passes downwardly through the stem of the L and into the combustion chamber 230 formed in the base of the L.

As illustrated, the combustion chamber 230 which extends across the floor oi the tank is provided with outlets extending along its opposite sides and with outlets formed in this fashion the circulation in the tank will follow the direction of the arrows shown in Figure 5. thereby securing an extremely efllcient form of agitation and turbulence, resulting in considerable economy through use of a burner of the type described. At present tanks of this type are generally heated by bubbling steam upwardly through them from openings'in the floor oi the tank, despite the fact that this practice results in tremendous loss of thermal efliciency and likewise does not secure the same amount or degree of agitation that may be obtained through use of the instant invention. For example, in the heating of pickling tanks in steel plants the increased agitation tends to eliminate the hydrogen bubbles. thereby permitting the acid in the solution to reach the metal more thoroughly, in turn reducing embrittlement of the metal. It has been found possible to reduce the pickling time by onehalf through employment of. this burner and still obtain improved results. Thus, by the new method it has been determined that suitable pickling operations can be performed at lower temperatures, namely F. as compared with F., and yet production can be increased by 105%. Furthermore, when steam is employed more acid vapor is released than with the improved burner, thereby causing dilution of the solution through loss of sulphuric acid, resulting in expense which may be substantially eliminated through employment of the burner described herein.

Turning now to the burner illustrated in Figure 6, it will be observed that certain modifications have been made which in no way depart from the scope or spirit of the present invention, although this modification of the burner may be preferable in various installations and under various conditions. The control system for all of the burners shown in the drawings may be the same and therefore need not be referred to in connection with the remaining description which is devoted to the burners themselves. As shown in Figure 6, pilot gas is admitted through an upper conduit 3, pilot air through a next lower conduit 302, main gas through a next lower conduit 3M, and main air through a bottom conduit 306. The pilot gas enters the burner cap 206 and flows downwardly through the pilot jet 52, as in the previously described constructions. Here again, just as in the type of burner shown in Figure 1, the jet is surrounded by an annular ring 208 which permits the passage of pilot air between the ring and the jet 52. The igniter Iii is once more located in close association with the pilot jet to ignite the pilot flame which passes slowly downwardly through the enlarged inner chamber that is defined by an elongated, tubular or cylindrical casing 308. Arranged to surround the inner chamber is an intermediate chamber for the main gas supply defined by a concentrically arranged cylindrical casing 3"]. The main gas entering through the passageway 3M flows downwardly through this intermediate chamber and emerges in the manner shown by the arrows in Figure 6. Located concentrically oi and arranged to surround the casing 3"] is an outer casing 3I2 forming an outer chamber through which the main air supply flows. The burner plate 222 is provided with the customary apertures through which the main air and gas supply and the pilot flame pass to cause the fuel supplies to be intermingled and co-mixed below the burner and to pass into the combustion chamber 230 which extends horizontally across the floor of the tank. It has been found desirable, and herein resides a feature oi the invention, to maintain the supply of main air in the outer chamber at a high velocity as compared with the flow of the pilot flame through the inner chamber, and the purpose of this is to cause the pilot flame to be pulled outwardly in the direction shown by the arrows in Figure 6, thereby flowing across the gas delivering apertures in the burner plate. This arrangement insures proper mixing and prevents the pilot flame from projecting far below the burner plate, in which condition gas pockets are likely to form and explosions are likely to occur. When this burner is in position in the tank it occupies approximately the same relative location as shown by the burner in Figure 3 so that the igniter and the pilot jet are again located above the liquid level and the main gas and air are supplied and mixed below the liquid level and are ignited by the pilot flame at a point below the liquid level. Combustion takes place within the combustion chamber 230 in the manner already described.

Turning now to Figure 7, there is there shown a still further modification oi the burner in which the pilot gas enters through the jet 52 in the manner already described and the pilot air through the annular ring 208, also previously described. Main air is admitted to the outer chamber through a conduit 320 and mixes with the pilot flame below the burner plate 222. As

shown in this modification, there is no main gas supply and in accordance with this treatment of the invention sufilcient gas may be introduced through the jet 52 to supply all'that is needed for proper combustion, or alternatively, a combined mixture of main air and main gas may be sup plied through the conduit 320 to flow downwardly through the outer chamber and to become ignited by the pilot flame after it has passed through the burner plate 222. Both of these modifications are contemplated, although ordinarily separate provision for the admission of main air and main gas will be found preferable. In the arrangement shown in Figure '7 the igniter 10 is present in the position heretofore described, and from the description that has been given in connection with previous constructions and figures the operation of the burner will be apparent.

Before departing from a discussion of the burner it is appropriate to devote a few words to mention of its simplicity. Complex and involved burner structures with moving parts or parts which burn out exist today. but such structures are to be contrasted with and distinguished from the type of structure described herein which is extremely simple in design and operation and carefully avoids all presently determinable possibilities of falling into disrepair through the operation of moving parts, parts being burned away, improper adjustments or complex structures. The parts of the burner are largely ordinary tubes but they have been so shaped, so coordinated and so arranged as a result of many years trial and experience that they function properly and efficiently despite the severe conditions of usage to which the burner is submitted. Such parts as the pilot jet and the igniter are above the liquid level and out of contact with the solution, thereby preventing attack at these points. Ignition occurs above the liquid level and the pilot flame only is conducted downwardly through the inner chamber until it reaches a point below the liquid level, whereupon the main combustible supply is admitted, following which combustion takes place.

Owing to the fact that both heat and acid may be present within the solution within the tank and also within the burner, the metal parts of the burner have been found to be subject to severe wear and attack. and in order to reduce the likelihood of destruction as far as possible, experimentation has revealed that certain alloys manufactured by the Carborundum Company and sold (ill under the trade-marks "Hastelloy C and "Hastelloy D" are suitable for the construction of the burner parts. "Hastelloy C" comprises nickel 58% to 60%, molybdenum approximately 17%, and chromium approximately whereas "Hastelloy D" contains nickel approidmately 85% to 90% and approximately 3% of copper. The exact chemistries of these metals can be obtained by reference to the manufacturers or proper chemical analysis, although an important discovery resides in the selection of this metal for the purpose of constructing the burner parts which are subject to attack, and invention is believed to reside in the employment of these specific metals for these specific purposes, although no attempt to claim them will be made in this application.

Installation and operation The burners may be constructed in varying sizes and of course their exact form may be modifled within the limits of the invention without departing from the scope and spirit thereof, as set forth in the claims appended hereto. As illustrated in Figures 1 and 3, burners suitable for use in pickling tanks and, of course, other tanks oi similar nature are illustrated. These burners are large and heavy and when they are installed they are intended to remain in position for months and operate day and night without the necessity of removal for any purpose whatsoever. They may weight several hundred pounds, and when put in position constitute fixtures, more or less, of the tanks in which they are installed. However, the burners are constructed in such a manner that ii for any purpose they have to be inspected or repaired, removal may be eflected readily without damage to the tank or disassembling the burner.

In operation. gas and air are supplied to the burner by the air and gas compressor at pressures sufhclent to deliver the products of combustion against the head of the liquid in the tank. The flow of gas is controlled by the governor so that the correct air and gas ratio is maintained at all times. The ignition of the air-gas mixture is accomplished in three steps. First, the hot wire igniter is heated to incandescence by the passage through it of a high amperage, low voltage current; second, the pilot jet is ignited by the hot wire igniter; and third. the main flow of gas and air is ignited by the pilot Set. In order to maintain a constant rate of agitation in the solution tank irrespective oi the delivery of the solution. the air delivered by the compressor is fed continuously through the burner and the liquid. However, if the temperature 01' the liquid falls below the set control point, the thermostat whichis immersed in the solution acts to turn on the gas supply, causing main gas to be fed to the burner and ignited by it. When the solution is raised to the desired temperature the gas is automatically turned off. In this way a constant rate of agitation and constant temperature are maintained, and in this feature resides an important aspect of the invention. The apparatus is started and stopped by pressing a button in the starting switch. Nothing more in the way of operation or supervision is required on the part of the operator. The various operations necessary for the ignition cycle, temperature control and continuous regulations are all accomplished automatically. Ordinarily a single installation will consist of a compressor unit, a burner and the necessary apparatus for ignition and control, although when the liquid is overheated no fuel passes to the burner and no fuel is wasted or lost. Not even the pilot flame burns during such intervals, although without departing from the spirit of the invention it would be possible, it desired, to permit the pilot to burn after shutting off the main gas supply. This is a feature of economy that can well afford to be mentioned.

This application is a continuation-in-part of my copending application, Serial No. 94,716 filed Aug. 6, 1936.

Having thus described the invention, what we claim as new and desire to secure by Letters Patent of the United States is:

1. A submerged combustion burner of the character described, comprising, in combination, an outer casing, an inner casing spaced from the outer casing, means for supplying a combustible mixture of pilot fuel and pilot air to the inner casing, an igniter associated with the inner casing and adapted to ignite the combustible mixture of pilot fuel and pilot air, means for conducting a main fuel supply to the burner, and means for admitting a main air supply to the space between the inner and outer casings.

2. A submerged combustion burner of the character described, comprising, in combination, a plurality of tubular casings concentrically arranged to form an inner and an outer chamber, said inner chamber being closed from the outer chamber at its upper extremity and in communication with the outer chamber at its lower extremity, and being provided with an interior opening at its upper extremity, a tubular fuel jet adapted to extend through the opening formed at the upper extremity of the inner tubular casing, said tubular jet being smaller than said opening, whereby an annular space surrounds the jet, means for supplying air to the opening surrounding the Jet whereby said air and fuel form a combustible mixture, means for igniting the combustible mixture interiorally of the inner casing, means for introducing a main fuel supply to the burner, and means for introducing a main supply of air to the space between the inner and outer casing.

3. A submerged combustion burner of the character described, comprising, in combination, means for conducting a combustible mixture of fuel and primary air to a point below the level of the liquid in which the burner is submerged and means for introducing a main supply of air to the combustible mixture below the point of said liquid level.

4. A submerged combustion burner of the character described, comprising, in combination, means for conducting a combustible pilot mixture of fuel and air to a point below the level of the liquid in which the burner is submerged and means for introducing a main supply of air to the combustible mixture below the point of said liquid level, together with means for introducing a main supply of fuel to the combustible mixture also at a point below said liquid level.

5. A submerged combustion burner of the character described, comprising, in combustion, an

inner chamber and an outer chamber arranged to extend vertically from a point above the surface of the liquid in which the burner is submerged to a point below the surface of the liquid in which said burner is submerged said chambers having open lower extremities and being otherwise closed, means for introducing fuel to one of said chambers, means for introducing air to another of said chambers, and anigniter-associated with the burner for igniting the fuel.

6. A submerged combustion burner of the character described, comprising, in combination, an inner chamber, an outer chamber, and an intermediate chamber, means for admitting a supply of pilot fuel and air to the inner chamber, means for admitting a supply of main air to the outer chamber, and means for introducing a supply of main fuel to the intermediate chamber, together with an igniter for igniting the admixture of pilot air and fuel as such admixture enters the inner chamber.

7. A submerged combustion burner of the character described, comprising, in combination, means for igniting a combustible mixture of pilot air and pilot fuel, means for conducting the ignited mixture to a point below the level of the water in which the burner is submerged, means for subsequently adding a supply of main air to the ignited mixture, and additional means for subsequently adding a supply of main fuel to the ignited mixture.

8. A submerged combustion burner of the character described, comprising, in combination, an elongated tubular outer casing, an elongated tubular inner casing connected to the outer casing at its upper extremity and extending lengthwise partially through said elongated outer casing, means for admitting an admixture of air and fuel to the inner elongated casing and an igniter permanently associated with said inner casing for igniting the admixture of air and fuel supplied thereto, said burner being at least partially submerged in a liquid.

9. A submerged combustion burner of the character described, comprising, in combination, means for supplying an admixture of pilot air and pilot fuel to the burner, means for igniting said admixture of pilot air and pilot fuel, means for supplying main air to the burner to support combustion and means for supplying main fuel to the burner also to support combustion, said main fuel supplying means being positioned in the path of the flame which results from the ignition of pilot air and fuel.

10. An L-shaped submerged combustion burner wherein combustion is carried out in direct contact with the liquid in which the burner is submerged, comprislng, in combination, fuel and air admixing means positioned within the stem of the L and a submerged combustion chamber positioned within the base of the L.

11. An L-shaped submerged combustion burner wherein combustion is carried out in direct contact with the liquid in which the burner is submerged, comprising, in combination, fuel supply means within the stem of the L and a combustion chamber positioned within the base of the L.

12. An L-shaped submerged combustion burner wherein combustion is carried out in direct contact with the liquid in which the burner is submerged, comprising, in combination, fuel supply means within the stem of the L, an igniter for the fuel supply means and a combustion chamber positioned within the base of the L.

13. An L-shaped submerged combustion burner wherein combustion is carried out in direct contact with the liquid in which the burner is submerged, comprising, in combination, means for introducing a supply of fuel and air to the stem of the L, means for igniting the fuel and air so supplied and means for conducting the ignited admixture of fuel and air to a submerged combustion chamber located in the base of the L.

14. An L-shaped submerged combustion burner wherein combustion is carried out in direct contact with the liquid in which the burner is submerged, comprising, in combination, a plurality of chambers positioned within,the stem of the L, means for admitting a combustible supply of fuel and air to one of the chambers within the stem, means for igniting the combustible mixturs thus introduced, means for introducing a main supply of air to the stem of the Lrand a submerged combustion chamber located in the base of the L.

15. An L-shaped submerged combustion burner wherein combustion is carried out in direct contact with the liquid in which the burner is submerged, comprising, in combination, a plurality of chambers positioned within the stem of the -L, means for admitting a combustible supply of fuel and air to one of the chambers within the stem, means for igniting the combustible mixture thus introduced, means for introducing a main supply of air to the stem of the L, additional means for introducing a main gas supply to the stem of the L, and a submerged combustion chamber located in the base of the L.

16. An L-shaped submerged combustion burner wherein combustion is carried out in direct contact with the liquid in which the burner is submerged, comprising, in combination, means for igniting an admixture of fuel and air in the stem of the L, and a submerged combustion chamber located in the base of the L.

17. An improved method of submerged combustion within a pool of liquid which comprises initially igniting an admixture of fuel and primary air, advancing the ignited admixture in the form of a column, surrounding the column with a supply of main air and admitting the air to the advancing column after the latter has moved a substantial distance surrounded by said supply of main air.

18. That improvement in methods of submerged combustion within a pool of liquid which comprises forming and igniting an advancing column of fuel and air, surrounding the advancing column with a column of main fuel, surrounding the column of main fuel with a column of main air and admixing the said columns after the ignited inner column of fuel and air has advanced a substantial distance.

19. That improvement in methods of submerged combustion within a pool of liquid which comprises forming a combustible column of fuel and primary air, advancing said column at relatively low velocity, associating the advancing column with a supply of main air advancing at a relatively high velocity and subsequently admixing the said columns.

20. That improvement in methods of submerged combustion within a pool of liquid which comprises forming an inner column of admixed fuel and air, advancing said column at a relatively low velocity, surrounding the column with a supply of main fuel, advancing said main fuel supply, surrounding said main fuel supply with a main air supply, advancing said main air supply at a relatively high velocity and admixing all of said advancing columns.

21..That improved method of submerged combustion within a pool of liquid which comprises igniting an admixture of main fuel and air at a point above the level of the liquid in which combustion is to take place, directing the ignited admixture in the form of a stream to a point below the liquid level and adding an air supply to the stream at a point also below the level of said liquid.

22. That improved method of submerged combustion which comprises igniting an admixture of fuel and air at a point above the level of the liquid in which combustion is to take place, directing the ignited admixture in the form of a stream to a point below the liquid level and adding an air supply and main fuel supply to the stream at a point below the level of said liquid.

23. That improvement in methods of submerged combustion which comprises igniting a stream of combustible gas above the liquid in which combustion takes place, simultaneously admitting a ring of air around said gas stream, projecting the resultant flame to a combustion none beneath the liquid level and adding main air and main fuel to the flame at a point beneath the liquid level.

24. An improved method of submerged combustion which comprises the steps of continuously applying compressed air to the liquid to be heated, periodically supplying fuel to the compressed air and igniting the admixture of fuel and air whenever the fuel is added to the compressed air.

25. An improved method of submerged combustion which comprises the steps of continuously supplying a stream of air to the liquid to be heated and supplying fuel to said air stream whenever the temperature of the liquid falls to a predetermined minimum in order to form a combustible fluid.

26. An improved method of submerged combustion which comprises the steps of continuously supplying a stream of air to the liquid to be heated, supplying fuel to said air stream whenever the temperature of the liquid falls to a predetermined minimum in order to form a combustible fluid. and igniting the combustible fluid so formed.

2'7. An improved method of submerged combustion which comprises the steps of continuously supplying a stream of air to the liquid to be heated, supplying fuel to said air stream whenever the temperature of the liquid falls to a predetermined minimum in order to form a combustible fluid, igniting the combustible fluid so formed, extinguishing the combustible fluid and cutting ofl the fuel supply when the temperature of the liquid reaches a predetermined maximum.

28. An improved method of submerged combustion in a pool of liquid which comprises admixing a supply of fuel and air in a downwardly moving column, burning the admixture in a horizontally moving stream and dividing the horizontally moving stream into a plurality of smaller streams flowing outwardly therefrom.

29. An improved method of submerged combustion within a pool of liquid which comprises burning a combustible mixture in a horizontally moving main stream and dividing the said main stream into a plurality of smaller streams extending substantially perpendicular from the said main stream.

30. That improvement in methods of heating liquids by means of a plurality of adiacently disposed submerged combustion burners which comprises the steps of discharging the products of combustion from said burners in a plurality of substantially horizontal streams beneath the surface of the liquid in which'the burner is submerged and causing the horizontal streams from adjacent bu-ners to impinge upon one another to deflect the said streams and cause them to flow upwardly.

THEODORE 8. SEE. JOHN EDWARD TEGARDEN. ARTHUR WILLIAMS.

OERTIF ICATE 0F CORRECTION Patent No. 2,ll8,i .79.

TEEODQRE 8. SEE, ET AL.

It isheneby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 52, for the word "weight" read weigh; and second column, line 75, claim 5, for "combustion" read combination; and that the said Letters Patent should be read with these corrections therein that the same may eonform to the record of the case in the Patent Office.

Signed and sealed this 19th day of July, A. D. 1938.

(Seal) Henry Van Arsdale, Acting Commissioner of Patents.

ply at a relatively high velocity and admixing all of said advancing columns.

21..That improved method of submerged combustion within a pool of liquid which comprises igniting an admixture of main fuel and air at a point above the level of the liquid in which combustion is to take place, directing the ignited admixture in the form of a stream to a point below the liquid level and adding an air supply to the stream at a point also below the level of said liquid.

22. That improved method of submerged combustion which comprises igniting an admixture of fuel and air at a point above the level of the liquid in which combustion is to take place, directing the ignited admixture in the form of a stream to a point below the liquid level and adding an air supply and main fuel supply to the stream at a point below the level of said liquid.

23. That improvement in methods of submerged combustion which comprises igniting a stream of combustible gas above the liquid in which combustion takes place, simultaneously admitting a ring of air around said gas stream, projecting the resultant flame to a combustion none beneath the liquid level and adding main air and main fuel to the flame at a point beneath the liquid level.

24. An improved method of submerged combustion which comprises the steps of continuously applying compressed air to the liquid to be heated, periodically supplying fuel to the compressed air and igniting the admixture of fuel and air whenever the fuel is added to the compressed air.

25. An improved method of submerged combustion which comprises the steps of continuously supplying a stream of air to the liquid to be heated and supplying fuel to said air stream whenever the temperature of the liquid falls to a predetermined minimum in order to form a combustible fluid.

26. An improved method of submerged combustion which comprises the steps of continuously supplying a stream of air to the liquid to be heated, supplying fuel to said air stream whenever the temperature of the liquid falls to a predetermined minimum in order to form a combustible fluid. and igniting the combustible fluid so formed.

2'7. An improved method of submerged combustion which comprises the steps of continuously supplying a stream of air to the liquid to be heated, supplying fuel to said air stream whenever the temperature of the liquid falls to a predetermined minimum in order to form a combustible fluid, igniting the combustible fluid so formed, extinguishing the combustible fluid and cutting ofl the fuel supply when the temperature of the liquid reaches a predetermined maximum.

28. An improved method of submerged combustion in a pool of liquid which comprises admixing a supply of fuel and air in a downwardly moving column, burning the admixture in a horizontally moving stream and dividing the horizontally moving stream into a plurality of smaller streams flowing outwardly therefrom.

29. An improved method of submerged combustion within a pool of liquid which comprises burning a combustible mixture in a horizontally moving main stream and dividing the said main stream into a plurality of smaller streams extending substantially perpendicular from the said main stream.

30. That improvement in methods of heating liquids by means of a plurality of adiacently disposed submerged combustion burners which comprises the steps of discharging the products of combustion from said burners in a plurality of substantially horizontal streams beneath the surface of the liquid in which'the burner is submerged and causing the horizontal streams from adjacent bu-ners to impinge upon one another to deflect the said streams and cause them to flow upwardly.

THEODORE 8. SEE. JOHN EDWARD TEGARDEN. ARTHUR WILLIAMS.

OERTIF ICATE 0F CORRECTION Patent No. 2,ll8,i .79.

TEEODQRE 8. SEE, ET AL.

It isheneby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 52, for the word "weight" read weigh; and second column, line 75, claim 5, for "combustion" read combination; and that the said Letters Patent should be read with these corrections therein that the same may eonform to the record of the case in the Patent Office.

Signed and sealed this 19th day of July, A. D. 1938.

(Seal) Henry Van Arsdale, Acting Commissioner of Patents.

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