US3127156A - Figure - Google Patents

Description

March 31, 1964 T. 1... SHEPHERD COMBUSTION APPARATUS AND METHODS INVENTOR.

THOMAS L. SHEPHERD 2 Sheets-Sheet 1 9 I I I I I t I I I I J J l I I I I I I I I I I I I III:

2 I I, I I I I I I I I I I I United States Patent Oil ice 3,127,156 COMBUSTION APPARATUS AND METHGDS Thomas L. Shepherd, Essex Fells, N.J., assiguor to Air Reduction Company, Incorporated, New York, N.Y., a corporation of New York Filed June 21, 1961, Ser. No. 118,724 12 Claims. (Cl. 263-43) This invention relates to combustion apparatus or burners and combustion methods and techniques, and the use of the apparatus and methods in production of heat, as in furnaces. More particularly, this invention relates to improved burners, as controlled burners, mixing controlled burners, and ring burners and improved controlled combustion methods where a combustible fluid and a combination supporting fluid are controlled when discharged from a burner to produce a flame in advance of the burner, and at controlled locations where the heat produced is most effective for the furnace or other installation in which the burner is used.

Many burners and methods of controlling combustion are Well known in the prior art. In many cases these burners are designed for specific purposes and are not useful in a wide variety of applications. In most instances the burner designs are such that the flame produced is rooted at the face or feed plate of the burner; and the result is that the heat produced is concentrated close to the burner. There is difficulty in controlling the location of heat production away from the burner. This leads to problems in the efficient utilization of the combustible fluid and combustion supporting fluid. In general, prior art burners do not satisfactorily provide suflicient control whereby the heat produced may be controlled as to location, as for example in melting scrap in open hearth furnace. Some burners also present problems of burner deterioration or failure because the heat of combustion is localized close to the burner feed plate or discharge orifices.

It is, therefore, an object of this invention to provide improved burner apparatus for a combustible fluid and a combustion supporting fluid whereby the location of the zone of heat production with respect to the burner feed plate or discharge orifice is controlled.

Another object of this invention is to provide improved methods of combustion of a combustible fluid and a combustion supporting fluid, and control of the combustion zone, and the mixing of the fluids.

More specifically it is an object of this invention to control the location of a combustion zone by controlling the mixing of generally parallel streams of a combustible fluid and a combustion supporting fluid fed to the combustion zone.

Another object is to provide a burner of improved configuration whereby combustion of a combustible fluid and a combustion supporting fluid results in controlled location of a zone of heat production in advance of the burner, and the amount of heat produced is at the base or bottom of the zone of heat production.

A further object of this invention is to control the formation of a combustible mixture between adjacent, generally parallel flowing streams of a combustible fluid and a combustion supporting fluid.

Another object is to provide maximum flame temperature and heat production in various areas of a controlled combustion zone by controlling the amount of a combustible fluid and a combustion supporting fluid fed to various areas of the combustion zone.

It is another object to provide a furnace, and more especially an open hearth furnace, with a burner having the means for preventing mixing of combustible fluid and combustion supporting fluid at the face of the burner,

3,127,156 Patented Mar. 31, 1964 and for controlling their mixing at a location spaced from the burner and where concentration of the most intense heat of combustion obtains most effective operation of the furnace.

A still further object is to provide apparatus for control of the mixing and burning of combustible fluid and combustion supporting fluid streams that issue from a burner, and control for the heating of a furnace, especially an open hearth furnace.

The foregoing and other objects of the invention are attained by the apparatus, methods, and techniques described herein. ln accordance with the invention there are provided procedures whereby an intermediate fluid is maintained between a combustible fluid and a combustion supporting fluid. The purpose of the intermediate fluid is to delay and control the mixing of the combustible fluid and the combustion supporting fluid. The intermediate fluid may also act as a quenching agent in preventing ignition.

Because of the separation or control of mixing provided by the intermediate fluid, combustible mixtures are not formed near the burner and a flame does not root on the burner or burner feed plate. Since the flame is not rooted to the burner, ignition of the combustible fluid and combustion supporting fluid mixture is by an ignition source adjacent the combustion zone. The ignition source may be a material at a high temperature or a pilot flame, or a high temperature atmosphere. By controlling mixing, the location of the region of maximum flame temperature and zone of combustion or heat production is controlled with respect to the burner.

This invention is particularly useful in a furnace, such as an open hearth furnace, where it may be desired to vary the location of the combustion zone and operate so as to maintain the maximum flame temperature or heat production zone at the top of the molten bath or charge, or on the surface of solid scrap. Mixing of the fluids or the location of the heat production zone, is controlled by varying the velocity of the intermediate fluid. Operating at lower velocities of the intermediate fluid results in a flame close to the burner; with high velocities the flame is moved away from the burner.

In the practice of the invention adjacent streams of the combustible fluid and the combustion supporting fluid may be sufficiently close so that they mix at a point in advance of the burner. If the said fluid streams are positioned far apart or issue from the burner so that inadequate mixing takes place, the procedures of the invention will generally be of little or no advantage.

When the invention is used with open hearth furnaces, the operation of the furnace is made more effective and efficient by localizing the generation of maximum heat at a region about midway between the ends of the furnace and at a substantial distance from the burner.

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

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

FIGURE 1 is a longitudinal, sectional view through a burner made in accordance with this invention;

FIGURE la is a diagrammatic view of the end face of the burner shown in FIGURE 1;

FIGURE 2 is a front view of the burner shown in FIG- URE 1;

FIGURES 3 and 4 are sectional views taken on the lines 33 and -4-4, respectively, of FIGURE 1;

FIGURE 5 is a rear view of the burner shown in FIGURE 1;

FIGURE 6 is a vertical sectional view showing a modified form of the invention;

FIGURE 7 is a sectional view taken on the line 77 of FIGURE 6;

FIGURE 8 is an enlarged detail view of the atomizing nozzle shown in FIGURE 6; and

FIGURE 9 is a diagrammatic view of an open hearth furnace having the burner of this invention as the heating means.

FIGURE 1 shows a burner 16 having a first and outer tube 12 containing a second and smaller tube 14 extending for most of the length of the outer tube and radially spaced therefrom to provide an annular chamber 16 for the circulation of water to cool the burners. A ring 18 is brazed or otherwise secured to the ends of the tubes 12 and 14 at the face of the burner for closing that end of the cooling chamber 16.

Another ring 20 closes the rearward end of the cooling chamber 16. There is an inlet fitting 22 at the top of the burner and an outlet fitting 24 at the bottom of the burner for the flow of water, or other cooling fluid, to and from the chamber 16. There are partitions 26 (FIGURE 3) extending along most of the length of the cooling chamber 16 for causing the water to flow from the fitting 22 (FIGURE 1) forward toward the end face of the burner before flowing back to the outlet fiting 24.

Within the second tube 14 there is a third tube 30 spaced from the inside of the tube 14 so as to leave a substantially annular passage 32.

There is a combustion supporting fluid or oxygen supply chamber 34 at the rearward end of the passage 32; oxygen is supplied to the chamber 34 through a fitting 36 at the top of the burner but off-set angularly from the water inlet fitting 22.

A fourth tube 40 is located with the third tube 30 and is spaced from it to leave a generally annular passage 42 which opens through the end face of the burner near the oxygen passage 32. This passage 42 communicates with a chamber 44 that is supplied with the intermediate fluid, ring or barrier gas, preferably air, through a fitting 46.

Within the fourth tube 40, and radially spaced from it, there is a fifth tube 59. A ring 52 at the face of the burner closes one end of the space between the tubes 40 and St) to form one end of an inner cooling chamber 56. Cooling water is supplied to the chamber 56 through an inlet fitting 57, and there is a connection 53 through which water discharged from the fitting 24 flows to the inlet fitting 57. Cooling water leaves the chamber 56 through an outlet fitting 59; and there are partitions 26 (FIGURE 3) in the chamber 56 (FIGURE 1) for making the water flow lengthwise of the chamber during its passage from the inlet fitting 57 to the outlet fitting 59.

A sixth tube 60 is located within the fifth tube 50 and is radially spaced from it to leave another generally annular passage 62 for a combustible fluid or fuel gas, as natural gas. This passage 62 is supplied with natural gas from a chamber 64 at the rearward end of the burner, and there is an inlet fitting 66 (FIGURE 5) for supplying natural gas to the chamber 64.

The burner illustrated is constructed hollow for use of other combustible fluids, such as oil. There is a seventh tube 70 within the tube 66 and there is an annular space between the tubes 60 and 70 providing a passage 72 for compressed air or other atomizing fluids, such as steam that is used to atoinize the oil supplied through the tube 70. A nozzle 74, at the discharge end of the tube 70, cooperates with a throat in the compressed air passage to atomize the fluid or oil discharged through nozzle 74.

A chamber 76 supplies compressed air to the passage 72, and there is an inlet fitting 78 on the burner for connection with a source of compressed air. Liquid fuel, such as oil, is supplied to the tube 70 through a fitting 79. Valves 80 are shown diagrammatically in FIGURE 5 ahead of all of the inlet fittings. These valves 86 are representative of means for controlling the supply of gas or liquid to every fitting independently of the supply to the othter fittings.

From FIGURE 1 it will be apparent that an annular oxygen stream 32 issuing from the passage 32, and represented by the long solid arrows, cannot mix with an annular fuel gas stream 84 issuing from the passage 62 and represented by the short solid arrows.

The mixing is prevented by an annular stream 86 of barrier or ring gas or ring air issuing from the passage 42 and represented by the dotted arrows. The stream 86 is a dynamic curtain of air, or other barrier gas, separating the streams 82 and 84 at the face of the burner.

At some distance from the face of the burner, the barrier or ring stream 86 merges with the other streams 82 and 84 and eventually permits them to mix with one another with the intimacy required for combustion. The location at which such mixing occurs depends upon the relative strength and velocity of the different streams; and the combustion region can be moved further away from the burner by increasing the velocity and flow rate of the ring gas stream 86.

This invention is much more effective and under better control when using annular gas streams, but in its broadest aspects, it is not limited to streams of any particular shape.

FIGURE la is a diagrammatic view showing the ditferences in the radial width of the passages 32, 42 and 62 around their circumferences. The dimensions OR and or are the radial width of the oxygen passage and the bottom and top, respectively, of the oxygen passage. The dimensions RR and rr are the corresponding dimensions for the ring in passage; and FR and fr for the fuel gas.

The annular passages 32, 42, 62 are shown as having somewhat greater radial Widths at their bottom portions. That is, at the front of the burner 10, or the discharge end, the tubes 14, 30, 40, 5t), 60 are somewhat eccentric to form these non-uniform annular discharge orifices for the passages 32, 42, 62. The effect of the non-uniform orifices is that the fluid streams issuing from the burner will have more fluid at the lower part of the mixing zone in advance of the burner. In some operations, such as an open hearth furnace, it is desirable to concentrate the heat produced at the surface or top of the bath or charge. This result can be obtained with the burner illustrated by FIGURE 1.

With the discharge orifices having a larger annular width at the bottom, compared to the top, the non-uniform annular orifices allow a greater quantity of the fluid streams to be directed to the top of the bath of the open hearth furnace, where the maximum heat is desired. The ratio of the bottom annular width to that of the top annular width, of the discharge orifices, should be greater than one. The ratio may be so great that the top width of the discharge orifices becomes negligible, but in such an extreme case the advantages of the ring air are no longer obtained. For concentration of heat at the bottom of the flame, it is most important to increase the radial width at the bottom of the oxygen and ring air passages.

FIGURE 6 shows a modified burner construction for burners of smaller size, and a construction in which the tubes are concentric and the annular orifices are of uniform radial width around their entire circumferences. Tubes 101 and 102 enclose a cooling chamber 103 between them. The end of one of the tubes 101 or 102 is formed to contact the other tube for closing the front end of the cooling chamber 103; and the tubes are bonded toether at 164.

There is an annular oxygen passage 105, between the tube 182 and another tube 106; and there is a barrier or ring gas passage 108 between the tube 106 and a smaller diameter tube 110.

Another cooling chamber 112 is formed between the tube and an inner tube 114 having a flared end bonded to the tube 110 at 116 to close the front end of this cooling chamber 112.

An annular fuel gas passage 118 is formed between tube 114 and a smaller tube 121). In order to make the burner suitable for use with liquid fuel, such as oil, the burner has a central liquid supply tube 122 with a nozzle 124 at its forward end extending into a venturi 125 at the end of the tube 120.

The inside diameter of the tube 120 is larger than the outside diameter of the liquid supply tube 122 so as to leave an annular passage 126 through which air or other gas is supplied to the venturi 125 for the purpose of atomizing the oil or other liquid fuel.

In the construction shown in FIGURE 6, all of the tubes 101, 102, 1%, 110, 114, and 120 fit into counterbores of different diameter in a block 128 and they are secured to the block 128 by silver solder 131 There is a bushing 132 screwed into the end of the block 123. The tube 122 is adjustable longitudinally in the bushing 132 and is secured in any adjusted position by a connector 134 on the rearward end of the bushing 132.

FIGURE 7 shows a water inlet 136 and partitions 138 for making the water flow to the front end of the chamber 103 and back through the upper end of the chamber to a Water outlet 140. An outside connection 142, shown mostly in section because it is ahead of the plane of section of FIGURE 7, carries the cooling water to an inlet 144 for the other cooling chamber 112 which also has partitions 138. There is a water outlet 146 from the chamber 112; and there are inlet openings in the block 128 at angularly spaced locations around the block 128 in positions to communicate with enlarged diameter sections of the counterbores ahead of each connection by silver solder 1311 as shown clearly in FIGURE 6. These inlets are indicated in dotted lines where they are behind the plane of section and in dot-and-dash lines where they are ahead of the plane of section.

These inlets which are illustrated diagrammatically in FIGURES 6 and 7 include an inlet 151 leading into the oxygen passage 105; an inlet 152 leading into the barrier or ring gas passage an inlet 153 leading into the fuel gas passage 11%; and an inlet 154 leading into the atomizing air passage 126.

The passage in the torch shown in FIGURES 6 and 7 can be made eccentric, as described previously for the torch illustrated in FIGURES 15, but this construction shown in FIGURES 6 and 7 does not lend itself to such convenient manufacture with eccentric locations of any of the tubes.

FIGURE 8 is an enlarged view of the nozzle 124 and shows its connection to the tube 122. At its rearward end, the nozzle 124 has a shank portion 158 of a diameter that fits into the tube 122 with a press fit. It may be bonded, if desired.

At the forward end of the shank portion 158, there is a shoulder 160 that abuts against the end face of the tube 122 to limit the extent of the nozzle into the tube 122. At its forward end, the nozzle 124 has a frustoconical face 161. A passage 162 extends through the nozzle and has four branch passages 164 that open through the frusto-conical face 161. Three of these passages 164 show in FIGURE 8. The other is ahead of the plane of section. The diameter of the passage 162 is reduced beyond the branch passages 164i and it opens through the end face of the nozzle 124 as an orifice 166.

In FIGURES 1 and 6 there are illustrated representative burners that are useful in this invention and that form a part of the invention. As already explained, the illustrated burners provide a series of orifices for discharging generally parallel streams of fluids, and these burners also have provisions for an atomized oil stream, which is a combustible fluid. In practicing this invention, the burners may be specifically designed for various combinations of fluids, the only requirement being that the combustible fluid be separated from the combustion supporting fluid by an intermediate fluid. In general, the burners of this invention are capable of providing for a series of fluid streams, and the number and variety of the fluid streams will depend on flame temperatures and heat production desired. Thus, there may be more than one stream of combustible fluid or combustion supporting fluid or intermediate fluid. While other burner design configurations are possible, it is preferred that orifices which are generally annular be used to provide the fluid streams issuing from the burner. Where the combustible fluid is atomized, as atomized oil, it is desirable and preferred that the oil be fed from the center of the burner.

By issuing an intermediate fluid stream between generally parallel issuing streams of a combustible fluid and a combustion supporting fluid, the mixing of fluids is prevented and delayed. If the intermediate fluid or a portion of the fluid does not enter into a combustion reaction with the other fluids, it will give a quenching effect to any combustible mixtures formed. The burner should be designed and operated so that the intermediate fluid does not substantially interfere with subsequent mixing of the combustible fluid and the combustion supporting fluid. That is, a combustible mixture of the fluids must occur in the combustion zone so that eificient and controlled combustion takes pplace. Thus, the velocity and quantity of the intermediate fluid should not be such that any of the fluids are forced away from the combustion zone.

The intermediate fluid that is used to control mixing of the combustible fluid and combustion supporting fluid can be any of a wide variety of fluids, for example, inert gases, as nitrogen and argon, liquids such as liquid oxygen, liquid nitrogen-and Water, or other gases, such as steam and air. In the procedures of this invention, using air has been found to be advantageous because it is most practical to use from a cost standpoint and the resultant quenching effect produced. Using air allows the oxygen present in the air to take part in the combustion process.

The combustible fluids that may be utilized in this invention include most combustible fluids as hydrocarbons, for example, natural gas, methane, propane, acetylene; gases such as hydrogen and materials that may be termed fluids, as atomized oil. Combustion supporting fluids include oxygen, fluorine, chlorine, nitrous oxide, ozone, and hydrogen peroxide. In general, any combustible fluid and combustion supporting fluid may be used in the practice of this invention.

It is preferred that the adjacent streams of combustible fluid and combustion supporting fluid be as close as possible for maximum utilization of the fluids in the combustion reactions. As in the case of utilizing oxygen as the combustion supporting fluid it is desirable that as much as possible of the oxygen be utilized in the combustion zone, because of the expense involved in the use of oxygen. The only limitation, on the closeness of the fluid streams, is that there must be suflicient room to provide the intermediate fluid, as ring air, of this invention. Thus, there must be suflicient room for an intermediate annular fluid passage or other discharge orifices of a size suflicient to provide the control over the location of the combustion zone. In no event should the distance between issuing streams of combustible fluid and combustion supporting fluid be greater than about four inches. This distance is measured from the outer edge of the combustible fluid stream to the outer edge of the combustion supporting fluid; or if no cooling passages were required, it would be the distance or width of the intermediate fluid orifice plus the thickness of the walls that provide the intermediate fluid passage.

Generally, in the burner of this invention, cooling passages are provided, which result in a separation of the stream of the fluids issuing from the burner feed plate or face. Also, the walls forming the passages for the fluids give a separation. It is desirable that the separation of adjacent fluid streams be as small as possible. If the streams are far apart, turbulence between adjacent streams will result and the turbulence leads to mixing. For example, when using oxygen as the combustion supporting fluid it is desirable that the distance between the oxygen and intermediate fluid be as small as possible. If this distance is too large, turbulence results and the intermediate fluid stream becomes enriched with oxygen so that mixing with the combustible fluid forms a combustible mixture. A greater distance can be tolerated between the intermediate fluid and the combustible fluid streams, as the turbulent mixing is not as critical in this case.

As indicated, the intermediate fluid controls the mixing of the combustible fluid and the combustion supporting fluid. The location of the combustion zone will depend primarily on the fluid stream velocities. When operating at fixed velocities of combustible and combustion supporting fluids, varying the intermediate fluid velocity will change the position or location of the combustion zone. That is, increasing the intermediate fluid velocity moves the combustion zone away from the burner, while decreasing the intermediate fluid velocity allows the combustion zone to move closer to the burner.

It is desirable that the intermediate fluid velocity not exceed substantially the velocity of an adjacent outer fluid stream or the outer stream may be blown away by the intermediate fluid.

By using larger quantities of intermediate fluid, with a larger intermediate fluid orifice or passage, smaller velocities of the intermediate fluid will be required. The amount and velocity of the intermediate fluid used determines the extent of separation of the combustion reactants, and the location of the combustion zone.

Example I A burner was constructed according tto the procedure described, and it was a burner having uniform annular Width orifices and is of the type illustrated by FIGURE 6. The burner was designed for use with oxygen, natural gas, and atomized oil, with air or ring air as the intermediate fluid. Concentric passages and uniform annular width discharge orifices were provided for the oxygen, natural gas, and air. The atomized oil was fed through the center of the burner feed plate. The annular orifice widths were as follows: oxygen passage, 0.0937 inch; ring air passage 0.1094 inch; natural gas passage 0.125 inch. The burner had an outside diameter of two inches. The outer annular orifice was for oxygen, the next for ring air, and the inner orifice was for natural gas. The cooling passage on the outside of the oxygen passage was 0.18 inch wide; while the cooling passage between the ring air and natural gas passage was 0.125 inch wide.

This burner was operated in a small open hearth furnace, of 25 ton capacity, used normally in a steel foundry for scrap melting and refining. The furnace was approximately 25 feet long, 8 feet wide and 8 feet high. The burner was placed at one end of the furnace, through the furnace door. The furnace charge was steel scrap. The burner was first operated as a regular rooted burner and the flame projected from the burner into the furnace interior. Oxygen flow was 12,000 cubic feet per hour, natural gas flow was 3,500 cubic feet per hour, and oil flow was 85 gallons per hour.

Operating under the procedures of this invention, the ring air was turned on, and supplied at 40 p.s.i.g.; gas and oil were maintained at the previous rate of flow and oxygen flow was reduced to 8,000 cubic feet per hour. When using ring air the flame was no longer rooted to the burner, but was located in the interior of the furnace at a point more than 4 feet ahead of the burner. When using ring air, ignition of the combustible mixture was provided by the hot steel scrap, previously heated by the rooted burner operation.

Example II A burner was constructed having generally annular orifices not having a uniform width. This burner has been described previously and is illustrated in FIGURE 1. This burner is designed to project a greater quantity of combustion supporting fluid to the bottom of the flame system and on the top of the furnace charge. The burner is useful in open hearth furnaces having a capacity of 200 to 400 tons. The location of the combustion zone can be controlled up to 15 feet or more from the burner. The capacity of the burner is as follows: oxygen, 65,000 standard cubic feet per hour at 100 p.s.i.g.; ring air, 0 to 60,000 standard cubic feet per hour at 90 p.s.i.g.; natural gas, 40,000 standard cubic feet per hour at 20 p.s.i.g.; oil, 650 gallons per hour at p.s.i.g.; atomizing air 2,000 to 5,000 standard cubic feet per hour at 20 to p.s.i.g. and cooling water, 30 gallons per minute at 50 p.s.i.g.

The burner was constructed from a series of tubes. The outside diameter of the burner or first tube is 6.625 inches, with inside diameter of 6.05 inches. The second tube has an outside diameter of 5.63 inches, with inside diameter of 5.062 inches. The first and second tubes are concentric and the space between these tubes is for cooling water.

The second and third tubes form the passage for oxygen. The third tube has an outside diameter of 4.5 inches with inside diameter 4.260 inches. The third tube is not concentric, but is ofiset so that the annular width at the top of the oxygen orifice is 0.1562 inch, while the annular width at the bottom is 0.4058 inch.

The third and fourth tubes form the passage for ring air. The fourth tube has an outside diameter of 3.5 inches, with inside diameter of 3.232 inches. The annular width of the top of the ring air orifice is 0.25 inch, while that of the bottom is 0.51 inch. A cooling water passage is provided between the fourth and fifth tubes. The fifth tube had an outside diameter of 2.75 inches, with inside diameter 2.62 inches. The fifth tube is concentric with respect to the fourth tube. The natural gas passage is provided between the fifth and sixth tubes. The sixth tube has a one inch outside diameter. The natural gas orifice has a uniform annular width of 0.81 ingh. Atomized oil is fed through the center of the sixth tu e.

The burners and techniques of this invention have been described and illustrated with regard to the preferred embodiments of generally concentric tube type burners, in one case with generally uniform annular Width orifices and in the other case of non-uniform annular width orifices. The concentric orifice type burners are advantageous, since they allow maximum utilization of the intermediate fluid. That is, the intermediate fluid orifice and stream will completely surround the interior fluid and will in turn be surrounded by the outer fluid in the case of a three fluid burner. This invention is not, however, limited to the use of only three fluids as a larger number of concentric orifices for combustible fluid, combustion supporting fluids and intermediate fluid may be utilized. The only limitation being that the combustible fluid is separated from the combustion supporting fluid by an intermediate fluid stream.

Burners having circular orifices or ports, instead of annular ones, for the combustion reactants, can be controlled by providing an intermediate fluid between the combustion reactants.

FIGURE 9 is a diagrammatic view of an open hearth furnace 1170. Material 172, which is to be heated, is shown on a hearth 174 of the furnace and there is a burner 10 supported by a Wall 176 at each end of the furnace. When the furnace is charged with a substant al percentage of molten iron, this iron is above the ignition temperature of the oxy-fuel mixture from the burners 10 and it is not necessary that the burner flames be rooted at the burner. When no such source of ignition is present, the burners are initially operated without the ring air to obtain a stable system.

The amount of heat that will be developed by each of the burners 10 depends upon the rate at which fuel and oxygen are supplied to the burner. The distance from the burner at which the oxygen and fuel stream mix sufficiently for ignition can generally be controlled by adjusting only the supply of barrier or ring air. Valves 180 (FIGURE for controlling the rate of flow to all passages of the torch are shown diagrammatically in FIGURE 5 and are merely representative of the means for controlling the rate of flow and the resulting pressure and velocity of the streams from the various passages that open through the face of the burner.

By adjusting adjacent streams to different flow velocities the streamlines can be made to curl away from the side on which the higher velocity stream is located, and this affects the location at which mixing occurs. There is some mixing by diffusion and when combustion is to be at a great distance from the burner, the adjacent streams should be parallel. Laminar flow can be used, but is not necessary.

Burners may be designed for sonic velocity when a gas is discharged through the end face of the burner. Sonic velocity is different for different gases and at different temperatures, and in addition to the design of the burner, the supply pressures may be adjusted to obtain stream discharges at sonic velocities.

The passage from which the gas streams are discharged need not be round, but round passages are advantageous because they avoid boundary layer interaction at the corners of non-round streams.

In operating the burner of the invention, the fuel and oxygen are supplied first and no ring air is used. A stabilized flame is obtained, rooted at the face of the burner. The ring air is then supplied to the burner and is used to prevent the oxygen and fuel from mixing near the face of the burner. The flame is, in effect, blown away from the face of the burner and the oxygen and fuel streams are prevented from mixing with the intimacy necessary from combustion until they reach the location Where heat is required. In open hearth furnaces this is important because it permits the heat to be concentrated over the material on the hearth whereas generation of the same heat near the burner face and end wall of the furnace would be too localized and could damage the furnace.

With one mol of fuel per second, such as natural gas or conventional fuel oils, the burner of this invention may use from 1 /2 to 2 mols of oxygen, and up to 2 mols of ring air. These values are given merely by way of illustration.

The limit on the pressure of the ring air is that it must not be so high that the ring air will blow away the oxygen into the atmosphere of the furnace where it will never mix with the fuel stream to make a combustible mixture. It is advantageous to have the oxygen stream outside of the ring air, but this is not essential.

While preferred embodiments of the invention have been described, it is to be understood that changes and variations may be made without departing from the spirit and scope of the invention as defined by the appended claims.

What I claim is:

1. A burner including an end face from which separate streams of a combustion supporting fluid and a combustible fluid are discharged, first passage means opening through the end face, means for supplying combustion supporting fluid to said first passage means for discharge as a stream through said end face, different and second passage means opening through the end face close to the first passage means, means for supplying combustible fluid to said second passage means for discharge as a stream through said end face, the first and second passage means being generally parallel to one another at their discharge ends so that the streams are discharged generally parallel to one another, and means for controlling the location at which the streams mix including intermediate passage means extending substantially parallel to the first and second passage means and opening through the end face of the burner between the first and second passage means, a source of intermediate fluid, a conduit through which the intermediate fluid is supplied to the intermediate passage means, and control means for changing the rate of flow of the intermediate fluid to control the distance from the end face of the burner at which the combustion supporting fluid and combustible fluid streams mix.

2. The burner described in claim 1, and in which each of the first and second passage means opens through the end face of the burner around an annular area, and one of the annular areas surrounds the other, and the intermediate passage means open through the end face of the burner around an annular area that is between the other annular areas.

3. The burner described in claim 1 and in which the first passage means is radially outward of the intermediate passage means, and the second passage means is radially inward of the intermediate passage means.

4. The burner described in claim 2 and in which the annular area opening of the first passage means are of greater radial width toward one side of the end face of the burner for providing a wider stream from the burner at the bottom of the stream when the burner is used in a position with the streams having a horizontal component of direction and with the wider part of the annular stream of combustion supporting fluid lowermost.

5. The burner described in claim 4 and in which the annular area opening has a larger annular width at the bottom compared to the top, and the ratio of the bottom an nular width to the top annular Width is greater than one.

6. The burner described in claim 1 and in which second passage means are located at the center of the face of the burner and include a liquid fuel supply conduit, a gas supply conduit, and a nozzle at which the liquid fuel is atomized by gas from said gas supply conduit.

7. A ring burner comprising a group of tubes of different diameters and located within one another, the outside diameter of each tube being somewhat less than the inside diameter of the next surrounding tube so as to leave spaces between successive tubes, the tubes having end faces that form the end face of the burner, the outer tube and the first inner tube having the space between them closed at the end face of the burner to provide a cooling water chamber, the space between the first and second inner tubes opening through the end face and constituting an opening for discharge of a combustion supporting fluid stream from the end face of the burner, the space between the second and third inner tubes being also open through the end face and constituting a passage for the discharge of intermediate fluid adjacent to but radially inward from the combustion supporting fluid stream, the third and fourth tubes having the space between them closed at the end face of the burner to provide another cooling water chamber, and an inner tube opening through the end face of the burner and from which a stream of combustible fluid is discharged from the burner surrounded by the stream of intermediate fluid.

8. In an external-mixing burner wherein separate streams of oxygen and fuel gas are discharged through separate discharge outlet means in an end face of a burner, the improvement which comprises substantially parallel discharge passageway means for the oxygen and fuel streams terminating in said outlet means, and means for delaying the mixing of the oxygen and fuel streams including a discharge outlet means intermediate said outlet means for said oxygen and fuel gas streams in position to flow a stream of barrier gas between the other streams, and means for supplying and regulating the rate of discharge of the barrier gas stream.

9. The combination with a furnace having a hearth on which is placed material to be heated, of burner means at a fixed location with respect to the hearth, a terminal discharge passageway means in the burner means for directing a stream of oxygen and a separate and substantially parallel terminal discharge passageway means for directing a stream of fuel for mixing outside of the burner, and other means for controlling the location beyond the burner at which the streams of oxygen and fuel mix sufliciently for combustion, said other means including discharge outlet means in the burner means, and extending substantially parallel to the discharge passageway means for said oxygen and said fuel streams and located between said discharge passageway means, and means for supplying a stream of another and a barrier gas between said fuel and oxygen streams.

10. The combination with an open hearth furnace of a burner at an end wall of the furnace with separate terminal discharge passageway means extending generally parallel to one another and from which separate streams of oxygen and fuel are supplied to the furnace, and means for locating the region of maximum heating by the combustion of the oxygen and fuel streams at a desired location with respect to the hearth including apparatus for delaying the mixing of the streams to the intimacy necessary for combustion prior to the flow of said streams into the region of the material to be melted on said hearth, said means including discharge outlet means in the burner extending substantially parallel to the discharge passageway means for said streams of oxygen and fuel and lo cated between said discharge passageway means, and means for supplying a stream of another and a barrier gas between the fuel and oxygen streams.

11. A method of controlling the combustion reaction between a combustion supporting fluid and a combustible fluid which comprises discharging separate streams of a combustion supporting fluid and a combustible fluid from a burner, confining said streams to generally annular cross-sections as they issue from the burner and confining said combustion supporting fluid stream to a greater annular Width at the bottom of the stream, and controlling the location of the combustion reaction by introducing a generally annular stream of an intermediate fluid between said combustion supporting fluid and combustible fluid streams.

12. The method of controlling the distance of maximum heating intensity beyond the end face of a burner, which method comprises discharging separate streams of combustion supporting fluid and combustible fluid from the burner wherein one of said fluids forms an inner stream and said other fluid forms an outer stream surrounding said inner stream, and delivering between said combustion supporting fluid stream and combustible fluid stream an intermediate stream of fluid continuously surrounding said inner stream and providing a barrier intermediate said inner and outer streams, delivering said intermediate fluid stream at a velocity not greater substantially than the velocity of said outer stream, and regulating the flow of said intermediate fluid stream to determine the location beyond the burner at which combustion will occur.

References Cited in the file of this patent UNITED STATES PATENTS 1,406,238 Stevenson et al. Feb. 14, 1922 1,531,678 Millward Mar. 31, 1925 2,021,245 Tonnar Nov. 19, 1935 2,800,175 Sharp July 23, 1957 FOREIGN PATENTS 1,249,283 France Nov. 21, 1960 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,,l2'Z l56 March 31, 1964 Thomas Lo Shepherd It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected beloww Column l line 16 for "combination" read combustion column 3 line 24 for "fiting" read fitting column 4 line 3, for 'othter read other column 6, line 25 for 'pplace" read place line 71, for "stream" read streams column 7 line 34, for "tto" read to column 9, line 7 before "means" strike out "the".,

Signed and sealed this 8th day of September 1964,

(SEAL) Attest:

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

Claims (1)

1. 8. IN AN EXTERNAL-MIXING BURNER WHEREIN SEPARATE STREAMS OF OXYGEN AND FUEL GAS ARE DISCHARGED THROUGH SEPARATE DISCHARGE OUTLET MEANS IN AN END FACE OF A BURNER, THE IMPROVEMENT WHICH COMPRISES SUBSANTIALLY PARALLEL DISCHARGE PASSAGEWAY MEANS FOR THE OXYGEN AND FUEL STREAMS TERMINATING IN SAID OUTLET MEANS, AND MEANS FOR DELAYING THE MIXING OF THE OXYGEN AND FUEL STREAMS INCLUDING A DISCHARGE OUTLET MEANS INTERMEDIATE SAID OUTLET MEANS FOR SAID OXYGEN AND FUEL GAS STREAMS IN POSITION TO FLOW A STREAM OF BARRIER GAS BETWEEN THE OTHER STREAMS, AND MEANS FOR SUPPLYING AND REGULATING THE RATE OF DISCHARGE OF THE BARRIER GAS STREAM.

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