US3092166A

US3092166A - Space heating method and apparatus

Info

Publication number: US3092166A
Application number: US859624A
Authority: US
Inventors: Thomas L Shepherd
Original assignee: Air Reduction Co Inc
Current assignee: Airco Inc
Priority date: 1959-12-15
Filing date: 1959-12-15
Publication date: 1963-06-04
Anticipated expiration: 1980-06-04

Description

June 4, 1963 T. 1 SHEPHERD 3,092,166

SPACE HEATING METHOD AND APPARATUS Filed Dec. 15, 1959 33 l l 5o IN VEN TOR. T/mmas L. Symp/6rd AGENT United States Patent Ofce 3,092,166 Patented June 4, 1963 3,092,166 SPACE HEAHNG METHGD AND APPARATUS Thomas L. Shepherd, Essex Fells, NJ., assigner to Air Reduction Company, Incorporated, New York, NX., a corporation of New Yori;

Filed Dec. 15, 1959, Ser. No. 359,624 6 Claims. (rl. 15S-11) This invention relates to space heating and to burner constructions for space heating.

It is an object of the invention to provide an improved method of space heating by means of liquid fuel used in combination with flames of an oxy-fuel gas mixture. The Oxy-fuel gas mixture supplies a part of the heat, bu-t it serves two other important functions; it atomizes the stream of liquid fuel supplied to the combustion space, and it also provides anchoring flames for preventing instability of the liquid fuel llame when the fuel supply is varied over a wide range to control the rate of heating of the space.

The oxygen mixed with the fuel gas may be commercially pure oxygen or it may be oxygen-enriched air, and for lower e'iciency operation, the oxygen may be that contained in air. The expression Oxy-fuel gas mixture, as used herein, means fuel gas mixed with air or commercially pure oxygen, or combinations thereof, but in the preferred operation of the invention the mixture is one of fuel gas with commercially pure oxygen.

The expression atomize is used in the description in a broad sense to indicate a breaking up of the liquid stream for better and more complete combustion within the projected stream but without denoting any particular Vineness of particle size.

lt is another object of the invention to provide an improved burner for use with liquid fuel, such as oil, together with fuel gas with which oxygen is mixed in a combustion chamber of the burner. The burner is of the rocket type with a combustion chamber open at its discharge end, and orices through which the liquid and gaseous fuel, and the oxygen, are discharged into the combustion chamber of the burner.

The combustion may take place entirely within the combustion chamber at low rates of fuel delivery, but for higher rates of heating the flaming mixture of fuel and oxygen extends beyond the end of the burner and may extend for great distances.

There is always some flame within 4the combustion space of the burner, however, and this ame provides stability for the burner over a remarkably wide range of fuel supply. Relatively low-velocity oxy-fuel gas flames within `the combustion chamber anchor the liquid fuel flame, and lower velocity Oxy-fuel flames near the base of the relatively high-velocity flames serve to anchor these higher-velocity llames.

The heat output of burners made in accordance with this invention 'can be varied from about 20,000 B.t.u. per hour to approximately 100,000,000 B111. per hour by simply adjusting valves and without changing of any burner parts. The arne length can be varied from about three to forty feet by simple valve adjustment. These values are given merely by way of illustration for a burner of relatively small size. Other ranges can be obtained with burners of other sizes.

The invention also provides for control of the temperature and the oxidizing potential of the flame. Valve adjustments may be used to control the oxygen-fuel ratio over a wide range, thereby extering control over flame temperature and the amount of excess oxygen where excess oxygen is desirable. Another advantage of the invention is that it has rapid light-olf under cool conditions. High burner output can be developed within a few seconds after light-off even though the burner is operating into a cool space or in the open air.

Another advantage is compactness, which facilitates portable use and simplifies applications in which size limitations exist. The construction of the burner of this invention is one which can be used for burners of different size without changing the principle of operation which provides the inherent stability over such a wide range of operating conditions.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FEGURE l is a sectional view through a rocket-type burner made in accordance with this invention;

FIGURE `2 is a sectional View taken on the line 2-2 of FIGURE 1;

FIGURE 3 is a fragmentary, diagrammatic, sectional View illustrating the operation of the burner shown in FIGURES l and 2;

FEGURE 4 is a diagrammatic view showing the connection of the burner with sources of oxygen and fuel, and showing the burner located in position to heat the interior of a furnace; and

FIGURE 5 is a diagrammatic end View showing the preferred slope at which the burner is located when used in a position confronting a similar burner at the other end of a furnace or other space to be heated.

FIGURE 1 shows a burner comprising a housing 10 having an end wall i12 attached to the side wall of the housing by screw threads 14 and sealed against leakage by an O-ring 16.

Within the housing 10 there is a bundle of tubes. This bundle includes long tubes 18 and short tubes 19, all of which extend through a circular partition plate 20. 'I'he

tubes

18 and 19 are rmly secured to the partition plate 20,

The long tubes 18 also extend through a rearward partition plate 22 and are rmly secured thereto. The short tubes 19, however, terminate in the space between the

partition plates

20 and 22. The bundle of tubes is inserted into the housing 10, before the end Wall 12 is screwed into the housing; and the rearward partition plate 22 contacts with a shoulder in the housing 10, to determine the position of the bundle of tubes and to hold the bundle with the forward partition plate 20 substantially even with the forward end of the housing 10.

When the end wall 12 is screwed into position, there are chambers for gas on both sides of the rearward partition plate 22; and there is an O-n'ng 26 for preventing gas in either chamber from mixing with gas in the other chamber. A baffle 28 on the end wall 12 extends across the chamber behind the rearward partition plate 22. There are holes in this bathe for -admitting gas to the open ends of the long tubes 18.

The housing 10 has two threaded inlet openings 30 through which oxygen is supplied to the chamber behind the rearward partition plate 22. There is another threaded opening 32 through the wall of the housing 10 for admitting fuel gas into the chamber ahead of the rearward partition plate 22. Tube or pipe fittings are screwed into these

openings

30 and 32 and communicate with sources of oxygen and fuel gas.

From the construction thus far described, it will bc apparent that oxygen will be discharged from the long tubes 18, and fuel gas from the short tubes 19, into a chamber 36 in front of the forward partition plate 20. This chamber 36 is enclosed within a double-wall sleeve 3S having an inner wall 40 spaced from an outer wall 42 along most of the length of the sleeve 38. Water is 3 circulated through the space between the inner wall 4i) and the outer wall 42. Y

There are iittings 46 connected with the sleeve 38 near V.its forward end and communicating with the space be- ,discharge of cooling water.

' The

walls

46 and 42 are preferably made or" copper for good heat conduction and they are separately threaded to the housing 18 with sealing rings 5U for preventing leakage along the threads. At their forward ends, the walls 49 and 42 are connected by a litting 52 which is free to move with respect to the outer wall 42 so as to compensate for differential expansion of the walls 4i! and 42. Sealing rings 50 prevent leakage of water hetween the fitting 52 and the outer wall 42.

In ythe construction illustrated, there is `a single tube 56`for supplying liquid fuel to the chamber 36. This tube 56 passes through the end wall 12 and through the partition plates 2t) and 22. In the preferred construction .it is secured to the partition plates 2i) and 22 and thus Y constitutes apart of the bundle of tubes. Where it passes through an opening in the end wall `12 a sealing ring 58 is provided for preventing leakage of gas.

FIGURE 2 shows an end view of the forward partition plate 20. The

tubes

18 and 19 are angularly spaced around circles. The outer tubes 18 are at 30 spacing from one another in the construction illustra-ted. There are thus twelve tubes located around the circle.l

The short tubes 19 are angularly spaced around a circle of intermediate ydiameter and are 4spacedfrom one another 'by an angle of 45. This provides for twelve of the short tubes 19. The inner long ltubes 18 'are located around a circle of small diameter with the angular spacing of the tubes 60. This provides for six of the inner tubes 18.V

Other combinations of tube spacing and numbers of tubes can be'lused but it is an important Ifeature of the A invention that the oxygen and fuel .gas issue ,from a plurality of tubes which are 'spaced from 'one another so that there is some clearance between the jets tof gas which are discharged from the tubes. Yet the tubes must be close enough together so that there is some mixing of fthe eddy currents from the different gas streams. p

The importance of this tube spacing, and of the use of `a plurality of tubes, Vis brought out inV FIGURE 3. Oxygen from the bottom tube 18 is discharged in a stream 62 and there lare some eddy currents 63 -Where theoxygen stream first issues from the tube 18. Fuel `gas issues from Y the tube 19 in fa stream 65 which has eddy currents 66 at VVfrom the tubes-18 and 1,9, causes the Veddy currents 63 and 66 to Vbe extended somewhat further out from the

tubes

18 and 19, Vbut the mixed gases of the edd-y currents are always at low velocity and provide stability for the higher velocity flames within the combustion chamber 36.

It will be apparent that similar 'anchor flames will be producediby mixed gases of eddy currents at all of the clearances between full gas streams and oxygenrstreams across the face of the forward partition plate 2. Y

The oxygen and fuel gas streams 62 'and 65, respectively, spread as they leave the

tubes

18 and 19, and the main portions thereof come together some distance in front of the parti-tion plate 20. The

streams

62 and 65 are turbulent lstreams ias they are `discharged from the

tubes

18 and 19, and when they come together in the combustion chamber 36, they mix with further turbulence. ln FGURE 3 the mixed gases are indicated by the small arcuate marks. The stream of liquid discharged from the vtube 56 is indicated by shout dash lines and is marked with the reference character 67. nere the stream 67 is broken up arnd mixed with the oxygen and fuel gas, this condition is indicated bythe small cross marks and dots in the mixing or combustion chamber 36. This showing is diagrammatic and `simplified for clearer illustration.

The high temperature resulting from the burning of the mixed gas and the atomized liquid in the combustion chamber 36 produces further turbulence in the combustion chamber and provides additional energy `for vatomizing and partially vaporizing the liquid fuel from the stream 67.

One of the reasons that the present torch can develop such large heat output while small in size is that the wall of the combustion chamber is water-cooled. This does deprive the torch of heat radiation from the surfaces of the combustion chamber, such as i's present with other 4types of rocket burners; but it does not decrease the stability of the burner of this invention Ibecause the stability of the ames is not dependent upon the radiation of heat from the inside sur-.faces of the combustion chamber. The mixed gas flame provides an anchoring ame system for the atomized liquid combustion and the low velocity flames, produced by mixing of eddy currents from the separate gas streams, provide anchoring flames for theV Y mixed gas flame system.

No diliiculty is encountered in lighting the burner of this invention, even though ignition is performed in the open .air and with no stabilization contributed by heated refractory material of a surrounding enclosure. The technique used is to turn on the supply of fuel gas alone and the llame length can be increased by simply increasing theV rate of Vliquid fuel feed and concurrently increasing the -oxygen flow to maintain a stable and relatively quiet combustion.

YA wide variation in the length of the llame can be obtained by adjusting the ratio of fuel gas to liquid fuel. For example, when the amount of fuel gas is reduced, there is a larger amount of oxygen mixed with the atomized liquid fuelV close to the Vregion of original atomizing of the liquid fuel, and this tends to produce a short llame. On the other hand, when the amount of fuel gas is in. creased, the oxygen-fuel gas flame which atomizes the liquid stream contains substantial quantities of products of combustion of the fuel gas aud-a much lower percentage Vof oxygen. This has the effect of preventing ignition of the liquid fuel until it has traveled a considerable distance from the discharge tube 56 and it produces a very long, flame thrower type of ame.

Experience indicates that in order to have the anchoring ames produced by the eddy currents, the spacing of the tubes which supply the oxygen and the fuel gas should not be greater than twice the `diameter of the tubes, when the tubes are of the same diameter. Ifthe oxygen and the fuel gas tubes are of different diameters, then the relations should be such that the spacing is not greater than twice the diameter of the tube which has the larger diameter. Since it is necessary to have some clearance in which the eddy current gases can mix and burn, the oxygen and fuel gas tubes should not be too close together. It appears that the spacing should not be less than one half of the diameter of the tubes, when they are both the same diameter; and not less than one half the diameter of the smaller tube when there is a difference in the tube diameters. This range is approximate and is for a burner in which the combustion chamber 36 is long enough to obtain a mixing of the major portions of the gas streams before their discharge from the combustion chamber.

The ratio of the combustion chamber length to its inside diameter depends upon the service for which the burner is intended. It may be between 1 to l and approximately 12 to l. In the preferred construction, the combustion chamber has an inside diameter of approximately 21/2 inches and a length of between 12 and 24 inches. These Values are given merely by way yof illustration.

The oxygen and fuel gas streams discharged from the tubes at the partition plate 20 issue at substantial velocity :and they impart some kinetic energy to the particles of liquid fuel when they atomize the stream of liquid fuel. The initial velocity of the liquid fuel stream, as it issues from the discharge end of its supply tube, must be Sullicient, after making allowances for the kinetic energy which the gas streams will supply, to carry the liquid stream along a trajectory that will clear the side wall of the combustion chamber. A lower velocity of liquid stream is objectionable because any liquid Iwhich strikes the side wall of the combustion chamber is cooled by contact with the combustion chamber and dribbles out of the end of the chamber without being taken up lby the flame system.

If adjustments are made which approach instability, the llame system will produce a screaming noise. Por example, if the burner is operated with the fuel supply at a very low pressure, the screaming characteristic of instability is produced, but the burner will operate over considerable screaming range, and with the sound spread over a Wide region of wave lengths, without actually losing the ame.

FIGURE 4 shows a burner, made in accordance with this invention, and having its housing supported from an end wall 72 of a furnace 75 Oxygen is supplied to the burner through piping 78 which includes a pressure regulator 79. Fuel gas is supplied through piping 81 including a pressure regulator 82. Liquid fuel is supplied through piping 84 and a liquid pump 86 is driven by a motor 88.

The rate of ilow of the oxygen and fuel gas is controlled by adjusting the output pressure of the

regulators

79 and 82. The rate of flow of the liquid fuel is controlled by adjusting the speed of the motor 88 through a speed con- .trol 90. A llame 92 discharged from the end of the burner may be increased in size until it substantially lls the entire length of the furnace 75.

In FIGURE 4 there is a second burner 95 at the opposite end of the furnace from the yburner 7l. These burners are used alternately, and when one burner is in operation, it is likely to blow molten metal or `slag toward the other burner. If a large mass of such material enters the combustion chamber of the inoperative burner, it may stick to the partition plate and plug the openings through which the oxygen fuel gas and liquid fuel are discharged when the burner is in operation.

This result is avoided by having the

burners

71 and 95 constructed with long combustion chambers and by tilting the burners downwardly so that particles projected lengthwise of the furnace, as indicated by the arrows 97 in FIGURE 4, will not strike directly against the partition plate within the burner.

This result is illustrated in FIGURE 5 -where the top edge 99 of the front end of the combustion chamber of the burner 95 is at a level slightly lower than a bottom edge 101 of the partition plate. The particles are considered as being projected horizontally and in order to prevent them from striking the partition plate 20, the

6 torch must be at an angle of A to the horizontal. It will be apparent from FIGURE 5 that the angle A is equal to arc tan Where d is the inside diameter of the combustion chamber of the torch 95 and L is the length of the combust-ion chamber of the burner.

The preferred rembodiment of this invention has been illustrated and described, but changes and modifications can be made and some features can be used in different combinations without departing from the invention as defined in lthe claims.

What is claimed is:

1. The method of heating a space by burner means including a burner located near one end of the space, which method comprises projecting a turbulent Oxy-fuel gas stream from the burner and burning the Oxy-fuel stream at least partially within the burner, forming anchoring flames by delivering the oxygen gas and fuel gas for said Oxy-fuel gas flame in a plurality of substantially parallel, closely adjacent streams that create between them a relatively lower velocity mixture of said fuel gas and oxygen gas drawn from said streams and which burns in a ame zone in advance of the Oxy-fuel gas flame of said turbulent gas stream, projecting a stream of liquid fuel from the burner into Iche ame of said turbulent gas stream, atornizing the stream of liquid fuel by contact with said turbulent gas stream and thereby admixing finely dispersed particles of liquid fuel with the turbulent gas stream, burning the liquid fuel while mixed with the llame and with products of combustion therefrom to form a ame system, adjusting the supply of liquid fuel to regulate the heating of said space, continuing steady combustion of the flame of burning liquid fuel by contact of the burning liquid `fuel with the Oxy-fuel gas flame of said turbulent gas stream, and continuing steady combustion of the VOxy-fuel gas llame of said turbulent gas stream by contact of the turbulent gas stream with said anchorring dames along the Oxy-fuel gas llame at a location before the Oxy-fuel gas llame mixes in combustible proportions With the stream of liquid fuel, increasing the volurne and velocity of the liquid fuel supply to increase the length of the llame system, and discharging the products of combustion of the ame system into the space to be heated.

2. The method of heating described in claim l characterized by burning only a portion of the liquid fuel and the Oxy-fuel gas stream within the burner before discharging the ame system into the space to be heated, and controlling the heating of the space by regulating the ylength of the llame system.

3. The method of heating described in claim il, characterized by locating the burner substantially at one end of an elongated space of substantial length, controlling the hea-ting by Varying the length of the flame system, and increasing the ilame system to substantially the full length of the space for maximum heating.

4. 'Ihe method of heating a space by means of a burner having an elongated combustion chamber with a discharge opening through which a space heating flame is discharged into said space, which method comprises delivering a plurality of separate, substantially parallel streams of oxygen gas and fuel gas substantially axially into the elongated combustion chamber, turbulently mixing said gas streams into a combustible mixture at a intermediate zone of said chamber, igniting said mixture to form a main flame at least partially within said combustion chamber, discharging the `oxygen and fuel gas streams into the chamber closely adjacent to one another and with the space between adjacent streams constituting zones into which a portion of the gas from each fof the respective streams is drawn -to form a relatively low velocity combustible gas mixture in said zones, burning said relatively low velocity gas mixture close to the root 'of the main flame to ferm anchoring flames for said main flame, discharging .a stream of liquid fuel into said intermediate zone toward said discharge outlet to effectively mix said fuel stream in said main flame, and burning said liquid fuel at least partly in said chamber and directing the ame produced thereby and said main flame into said space to be heated.

5. The method described in claim 4 characterized by regulating the relative flows of said oxygen gas streams andfuel gas streams to control the `oxygen for combus tion of the liquid fuel.

6. A combination liquid `and gaseous fuel burner comprising an elongated, unobstructed combustion chamber having an open discharge end and an opposite closed end through which a plurality -of substantially parallel gas passageways extend to said chamber, adjacent alternate ones of said passageways being connected respectively to sources of an oxygen gas and a fuel gas to deliver corresponding, spaced, substantially-parallel streams of an oxygen gas and a fuel gas into the closed `end of said chamber directed substantially toward said chamber discharge opening, said gas streams merging With onewanother at an intermediate zone of said chamber, in a relatively high velocity combustion mixture of said oxygen gas and fuel gas and burning in a flame con-lined at least in part Vby the walls of said chamber, the parallel gas passageways being closely adjacent to one another with zon between them into which gas from the streams is drawn to form la relatively low velocity mixture of oxygen gas and fuel gas whose combusti-on forms anchoringV ames contiguous with said gas streams eectively pre- Y venting extinction of the flame formed by combustion of said relatively high velocity combustion mixture, and a liquid delivery passageway extending substantially centrally through said closedrend of said chamber having means for discharging Ia vstream of liquid fuel therethrough toward said chamber discharge opening into said relatively high velocity gas mixture wherein said relatively high velocity mixture effectively atomizes said ,liquid stream to facilitate combustion thereof, and gas ow regulating means for the oxygen vand fuel gas, the regulating means for the oxygen and fuel gas being independently adjustable for controlling the supply of oxygen gas for combustion With said liquid fuel by `controlling the relative flows of said oxygen gas and fuel gas streams.

References Cited in the file of this patent UNITED STATES PATENTS 664,526 Blass Dec. 25, 1900 1,416,990 Smith May 23, 1922 1,476,913 Nordensson etal Dec. 11, 1923 1,729,677 Miller Oct. 1, 1929 2,084,830 Barnard et al June 22, 19137 2,333,531 Ferguson Nov. 2, 1943 2,480,459 Fletcher Aug. 30, 1949 2,625,466 Williams Ian. 13, 1953 2,706,887 Grow Apr. 26, 1955 2,911,035 Nieman et al. Nov. 3, 1959 2,931,430 Marshall Apr. 5, 1960 FOREIGN PATENTS 819,977 Great Britain Sept. 9, 1959 820,820 Great Britain Sept. 30, 1959

Claims

6. A COMBINATION LIQUID AND GASEOUS FUEL BURNER COMPRISING AN ELONGATED, UNOBSTRUCTED COMBUSTION CHAMBER HAVING AN OPEN DISCHARGE END AND AN OPPOSITE CLOSED END THROUGH WHICH A PLURALITY OF SUBSTANTIALLY PARALLEL GAS PASSAGEWAYS EXTEND TO SAID CHAMBER, ADJACENT ALTERNATE ONES OF SAID PASSAGEWAYS BEING CONNECTED RESPECTIVELY TO SOURCES OF AN OXYGEN GAS AND A FUEL GAS TO DELIVER CORRESPONDING, SPACED, SUBSTANTIALLY-PARALLEL STREAMS OF AN OXYGEN GAS AND A FUEL GAS INTO THE CLOSED END OF SAID CHAMBER DIRECTED SUBSTANTIALLY TOWARD SAID CHAMBER DISCHARGE OPENING, SAID GAS STREAMS MERGING WITH ONE ANOTHER AT AN INTERMEDIATE ZONE OF SAID CHAMBER, IN A RELATIVELY HIGH VELOCITY COMBUSTION MIXTURE OF SAID OXYGEN GAS AND FUEL GAS AND BURNING IN A FLAME CONFINED AT LEAST IN PART BY THE WALLS OF SAID CHAMBER, THE PARALLEL GAS PASSAGEWAYS BEING CLOSELY ADJACENT TO ONE ANOTHER WITH ZONES BETWEEN THEM INTO WHICH GAS FROM THE STREAMS IS DRAWN TO FORM A RELATIVELY LOW VELOCITY MIXTURE OF OXYGEN GAS AND FUEL GAS WHOSE COMBUSTION FORMS ANCHORING FLAMES CONTIGUOUS WITH SAID GAS STREAMS EFFECTIVELY PREVENTING EXTINCTION OF THE FLAME FORMED BY COMBUSTION OF SAID RELATIVELY HIGH VELOCITY COMBUSTION MIXTURE, AND A LIQUID DELIVERY PASSAGEWAY EXTENDING SUBSTANTIALLY CENTRALLY THROUGH SAID CLOSED END OF SAID CHAMBER HAVING MEANS FOR DISCHARGING A STREAM OF LIQUID FUEL THERETHROUGH TOWARD SAID CHAMBER DISCHARGE OPENING INTO SAID RELATIVELY HIGH VELOCITY GAS MIXTURE WHEREIN SAID RELATIVELY HIGH VELOCITY MIXTURE EFFECTIVELY ATOMIZES SAID LIQUID STREAM TO FACILITATE COMBUSTION THEREOF, AND GAS FLOW REGULATING MEANS FOR THE OXYGEN AND FUEL GAS, THE REGULATING MEANS FOR THE OXYGEN AND FUEL GAS BEING INDEPENDENTLY ADJUSTABLE FOR CONTROLLING THE SUPPLYING OF OXYGEN GAS FOR COMBUSTION WITH SAID LIQUID FUEL BY CONTROLLING THE RELATIVE FLOWS OF SAID OXYGEN GAS AND FUEL GAS STREAMS.