US3351284A - Methods of operating burners and improved burners - Google Patents

Description

Nov. 7, 1967 H, T. HUTTON ET AL 3,351,284

METHODS OF OPERATING BURNERS AND IMPROVED BURNERS Filed July 8, 1965 74 78 FUEL I L84 7 97 86 8b as 9 a6 1%??? FIG. 2

52 44 g %y '2 V V I -///4' INVENTORS HARRY T. HUTTON CLEO R. GOETJEN JAMES M. OGBORN a AGE/VT 92 SUPPLY M 96 United States Patent O METHODS OF OPERATING BURNERS AND IMPROVED BURNERS Harry T. Hutton, Somerville, N.J., Cleo R. Goetjen, Redondo Beach, Calif., and James M. Ogborn, Eregh, Turkey; said Hutton and said Goetjen assignors to Air Reduction Company, Incorporated, New York, N .Y., a corporation of New York Filed July 8, 1965, Ser. No. 470,634 15 Claims. (Cl. 239-11) ABSTRACT OF THE DISCLOSURE This invention is an apparatus and method of use thereof for protecting the small ports of a scarfing burner from the flying bits of molten metal which are common in a scarfing environment. The small pre-heat ports on a scarfing burner are of such a size that when they are not in use they are easily clogged by flying bits of metal which land on the port and solidify in that position. This occurrence is prevented by this invention through the use of jets of air being expelled through these ports when they are not in use in the scarfing operation for the purpose of repelling any flying bits of molten metal which approach the vicinity of the ports.

This invention relates to burners and especially to burners that are used for scarfing slabs, billets and other workpieces. More particularly, the invention relates to the protection of burners from having airborne and waterborne fine debris enter the fuel jet ports of the burners.

It is an object of the invention to prevent clogging, or partial clogging, of the fuel jet ports by entrance of fine debris into the ports of unused burners during a scarfing process, which does not require the full flame width of the apparatus, and all of the burners between scarfing cycles.

When any of the fuel jet ports of a scarfing burner system is not in use, airborne fines get into the ports, and iron powder slag is often washed into the ports by the quenching water used in the scarfing operation. It is another object of the invention to provide a method and apparatus that supplies barrier gas for preventing the entrance of such debris into the fuel jet ports.

The invention provides a flow of barrier gas through the unused ports with sufficient pressure and velocity to prevent the debris from entering the ports. The barrier gas does not take part in the scarfing operation, and it is supplied only to ports at locations beyond the region of scarfing, and to other ports at times when the burner is not in active use in scarfing operations, that is, between scarfing cycles of the apparatus.

Another object is to provide automatic change from fuel jet flow through the ports to barrier gas flow. In the preferred operation of the invention, the barrier gas is supplied to the fuel jet ports automatically whenever the supply of fuel to the ports is shut off.

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:

FIGURE 1 is a diagrammatic view showing a burner system at a scarfing station and showing a piping diagram with control means for protecting the fuel jet ports of the burner in accordance with this invention; and

FIGUREZ is a greatly enlarged diagrammatic, sectional view showing one of the burners of FIGURE 1.

FIGURE 1 shows a burner system 10 including a row of upper burners 12 in position for scarfing a top 3,351,284 Patented Nov. 7, 1967 ice surface of a workpiece; groups of burners 14 and 16 at the right and left sides, respectively, of the workpiece; and another group of burners 18 for scarfing the bottom surface of the workpiece.

FIGURE 2 shows a workpiece consisting of a slab 20 supported by conveyor rollers 21 and passing under one of the burners 12 in the direction indicated by the arrow 22. The burner 12 has a shoe 24 secured to the bottom of the burner. This shoe rests on the top surface of the workpiece 20 and the burner 12 is ordinarily free to move up and down to accommodate itself to variations in the surface of the workpiece; such variations being the result of bending and warping of the slab.

An oxygen jet 26 is discharged from a large port 28 of the burner 12 and impinges against the workpiece 20 to remove the heated metal surface from the workpiece, in a manner well understood in the art. In order to insure sufficient heat for the scarfing operation, fuel jets 31 and 32 are directed toward the workpiece surface adjacent to the oxygen jet 26 and at a comparatively short distance from the workpiece surface when the burner 12 is in operation position.

It is common practice to use a plurality of burners 12 placed side-by-side in a row extending transversely of the workpiece. When operating on workpieces which do not require the full flame width of the apparatus, one or more of the burners can be shut off, or some of the burners can be removed when using the apparatus for workpieces requiring a narrower piece between the burners at the scarfing station. A burner may be provided with a single oxygen port consisting of a slot, or may be provided with a row of oxygen ports 28 supplied with oxygen from a common header 34 within the body of the burner. Oxygen is supplied to the header 34 through a supply line 36 connected with a suitable source of oxygen.

The fuel jets 31 and 32 are supplied from fuel jet ports 41 and 42, respectively, and there is a row of ports 41 supplied from a header 44. There is a similar row of fuel jet ports 42 supplied from a header 46 in the burner body. These ports 41 and 42 are of much smaller cross section than the oxygen port 28 and it is these small ports for the fuel jets which become clogged or partially clogged by airborne and waterborne fines in the region of the burners during scarfing operations and between cycles of scarfing apparatus which is in operation.

Different kinds of fuel can be supplied to the headers 44 and 46. Oxyacetylene mixtures are used where intense heat is required, but other fuel gases and atomized oil are also used. This invention is equally applicable to burner systems using any kind of fuel which is projected in jets from small ports in the face of the burner. In the diagrammatic illustration of FIGURE 2, the header 44 is supplied with fuel through passages 51 and 52; and the header 46 is supplied with fuel through corresponding passages 54 and 55. The passage 55 is connected by a conduit 56 to a T-connection 58 through which the passage 52 communicates with check valve 67 which is then connected to a supply line 60 that supplies fuel to both of the headers 44 and 46.

Another T-connection 62 puts the conduits 52 and 56 in communication with a barrier gas supply line 64 containing a check valve assembly 66 which is shown in FIG- URE 2 as consisting of two check valves 68 and 69 connected in series with one another and oriented so as to permit flow of barrier gas from the supply line 64 to the T-connection 58 but to prevent back flow of gas toward the barrier gas supply line 64.

For the burners with which this invention has been used, experience has indicated that the pressure of the barrier gas in the fuel jet ports 41 and 42 should be at least two pounds per square inch gauge pressure in order to keep debris from entering these ports. Because of the pressure drop between the barrier gas supply line 64 and the ports 41 and 42, the pressure in the barrier gas supply line must necessarily be greater than the pressure required in the fuel jet ports. Pressures higher than two pounds per square inch can be used for the barrier gas discharging from the fuel jet ports 41 and 42, but it is a feature of the invention that the barrier gas is supplied at a pressure lower than the pressure at which the fuel gas is supplied. This pressure differential should be sufficient so that when fuel is being supplied to the supply line 60, the fuel pressure will always exceed the barrier gas pressure at the region of the check valve assembly 66, and preferably by a decisive amount, such as one pound per square inch.

FIGURE 2 shows the supply line 60 with a pressure of nine pounds per square inch and the barrier gas supply line 64 with a pressure of six pounds per square inch. These values are given merely by way of illustration, and as an example of a pressure differential which is decisive at the check valve assembly 66 and which will result in more than two pounds per square inch pressure of barrier gas at the fuel jet ports 41 and 42, even though there are a substantial number of fuel jet ports from which the barrier gas is discharging.

From the foregoing description it Will be apparent that whenever the supply of fuel gas to the supply line 60 is shut off, the check valve assembly 66 opens to permit flow of barrier gas from the supply line 64 through the various connections and passages to the headers 44 and 46, and from these headers through the fuel jet ports 41 and 42 with sufficient velocity and pressure to prevent airborne and waterborne fines from entering the ports 41 and 42. Whenever fuel is supplied through the supply line 60 and check valve 67 to the headers 44 and 46 and their respective fuel jet ports 41 and 42, the check valve assembly 66 closes as a result of the back pressure of the fuel from the T-connection 62 and serves as a controller for shutting off the supply of barrier gas to the ports 41 and 42.

An inert gas such as nitrogen is preferred as the barrier gas, but where nitrogen is not readily available, or where the cost of nitrogen is a substantial item, air can be used as the barrier gas. When air is to be used, the barrier gas should be supplied to the fuel passage as closely as possible to the burner. The construction shown in FIGURE 2 of the drawing obtains this result.

Referring again to FIGURE 1, the lefthand burner 12 is shown as connected with the check valve assembly 66. The barrier gas supply line 64 supplies barrier gas to all of the burners 12, and the fuel supply line 60 supplies fuel to all of the burners 12. However, in the preferred construction shown. in the drawing, each of the burners 12 is supplied with its own check valve assembly, which is the same as check valve assembly 66 and indicated by the reference character 66. Each check valve assembly 66 (or 66) can be made with only one check valve (as shown in the fuel line 60 in FIGURE 2) in place of the series-connected check valves illustrated in FIGURE 2, but the series-connected check valves provide additional insurance against possible back flow of fuel into the barrier gas supply line in the event of check valve leakage.

The burners 14 and 16, which scarf the sides of the workpiece, are supplied with barrier gas from supply lines 74 and 76, respectively, and with fuel from supply lines 78 and 79, respectively. The lower burners 18 are supplied with barrier gas from a supply line 82 and with fuel from a supply line 84.

The various supply lines for barrier gas are interconnected by hoses 86 to a common supply line 88 having a pressure regulator 89 which can be adjusted to regulate the pressure of the barrier gas and which can be used for shutting off the flow of barrier gas. The various supply lines for fuel are interconnected by hoses 92 with a main fuel supply line 94 having a pressure regulator 96 for adjusting the pressure of the fuel supply. A shut-off valve 97 is shown for shutting off the fuel, but this valve 97 is merely representative of fuel shutoff means and ordinarily the fuel is shut off by valves located closer to the burners but which are omitted in the diagrammatic illustration of FIGURE 1 in order to simplify the drawing. It is noted that the invention is not limited to the use of pressure regulators but could use any means of supplying gas flow at a controlled pressure.

The preferred apparatus and method of this invention have 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 the claims.

We claim:

1. A scarfing burner system including a fuel jet port from which a combustible stream is projected against a workpiece, means operable selectively to supply and to shut off fuel to the upstream end of the port, other means for supplying noncombustible barrier gas to the upstream end of the port, said other means including a controller responsive to the operation of the first means to shut off the supply of barrier gas when the first means supplies fuel and to supply barrier gas when the first means shuts off the supply of fuel.

2. The scarfing burner system described in claim 1 characterized by said control including a pressure-responsive element that is exposed to back pressure of the fuel for operating the controller to shut off the flow of barrier gas when the first means is operating to supply fuel to the scarfing burner system.

3. The scarfing burner system described in claim 2 characterized by the controller of said other means including a check valve that opens for flow of barrier gas toward the scarfing burner system and that closes against back flow from the scarfing burner system, and a pas sage through which barrier gas from the check valve flows to the upstream end of the port, the means for supplying fuel to the scarfing burner system being connected with said passage between the check valve and the upstream end of the port.

4. The scarfing burner system described in claim 3 characterized by the controller for said other means including two check valves connected in series with one another.

5. The scarfing burner system described in claim 1 characterized by the scarfing burner system including a burner unit with a large port for the discharge of a stream of oxygen against the surface of the workpiece, and a plurality of fuel jet passages opening through a face of the burner adjacent to the oxygen port and adjacent to the workpiece when the burner is used for scarfing.

6. The scarfing burner system described in claim 5 characterized by the system including a plurality of burner units, and said other means including a separate check valve for each of said burner units.

7. The scarfing 'burner system described in claim 5 characterized by means for supplying the barrier gas at a controlled gauge pressure greater than approximately two pounds per square inch and substantially less than the pressure at which the fuel is supplied to the ports.

8. The scarfing burner system described in claim 7 and in which the means for controlling the barrier gas supply is a pressure regulator adjustable to regulate the pressure of the barrier gas.

9. The method of protecting the fuel jet ports of a burner which comprises maintaininga supply of noncombustible gas to the upstream ends of said ports and at a pressure that produces flow of noncombustible gas through the fuel jet ports at suificient velocity to pre-.

vent entry of the fine debris into the ports at their outlet ends, supplying a stream of fuel to the upstream ends of the ports when the burner is in operation, and shutting ed the supply of noncombustible gas by the pressure of said fuel so long as, and only as long as, the supply of fuel to the burner is continued where-by noncombustible gas flows through the burner ports when the supply of fuel is discontinued.

10. The method of protecting the fuel jet ports of a burner as described in claim 9 characterized by supplying the fuel at higher pressure than the noncombustible gas and utilizing the direct pressure of the fuel to shut off the flow of noncombustible gas to the upstream ends of the ports.

11. The method of protecting the fuel jet ports of a burner as described in claim 10 characterized by supplying the noncombustible gas to the burner through a check valve that opens for flow toward the burner, and closing the check valve against flow toward the burner by back pressure of the fuel against the downstream side of the check Valve.

12. The method of protecting the fuel jet ports of a burner as described in claim 9 characterized by supplying the noncombustible gas to the upstream ends of the ports at a pressure of at least two pounds per square inch and supplying the fuel to the burner at a pressure greater than that of the noncombustible gas by at least one pound per square inch at the upstream end of the ports.

13. The method of protecting the fuel jet ports of a burner as described in claim 9 characterized by introducing the noncombustible gas into the same space from which the fuel is supplied to the upstream ends of the ports and at a location near the upstream ends of the ports.

14. The method of protecting the fuel jet ports of a scarfing burner that has ports through which streams of oxygen are discharged against a workpiece while fuel jet flames are directed by the fuel jet ports against the workpiece adjacent to the oXygen streams, which method comprises shutting off the fuel at times between successive cycles of a scarfing operation when the burner is not directing streams of scarfing oxygen against the workpiece, and supplying streams of noncombustible gas through the fuel ports when the fuel supply is shut off to prevent entry of airborne and quenching waterborne debris into the fuel jet ports, and controlling the substitution of noncombustible gas streams for the fuel flow through the fuel jet ports by automatic response to the supplying and shutting off of the fuel.

15. The method of operating a scarfing burner system that has a plurality of groups of fuel jet ports in a row extending transversely of the burner system for directing heating flames against a surface of a workpiece and that has a row of scarfing jet ports adjacent to the fuel jet ports with means for controlling the number of scarfing jets from which oxygen is projected in accordance with the width of the workpiece, which method comprises independently controlling the flame width of the burner by changing the number of fuel jet ports to which fuel is supplied, and projecting noncombustible gas through those flame jet ports that are not supplied with fuel at any particular time including the time when fuel is being projected from the ports of the part of the flame system which is in use.

References Cited UNITED STATES PATENTS 752,195 2/1904 Best 158-36 2,478,557 8/1949 Bell et al. 239291 2,622,048 12/ 1952 Moesinger 222-394 2,818,110 12/1957 Rulseh 15836 2,943,797 7/ 1960 Neilson 239305 2,953,248 9/1960 Troland 239112 3,139,238 6/1964 Norstrud et a1. 222133 EVERETT W. KIRBY, Primary Examiner. M. HENSON WOOD, JR., Examiner.

R. S. ST ROBEL, Assistant Examiner.

Claims (1)

1. A SCARFING BURNER SYSTEM INCLUDING A FUEL JET PORT FROM WHICH A COMBUSTIBLE STREAM IS PROJECTED AGAINST A WORKPIECE, MEANS OPERABLE SELECTIVELY TO SUPPLY AND TO SHUT OFF FUEL TO THE UPSTREAM END OF THE PORT, OTHER MEANS FOR SUPPLYING NONCOMBUSTIBLE BARRIER GAS TO THE UPSTREAM END OF THE PORT, SAID OTHER MEANS INCLUDING A CONTROLLER RESPONSIVE TO THE OPERATION OF THE FIRST MEANS TO SHUT OFF THE SUPPLY OF BARRIER GAS WHEN THE FIRST MEANS SUPPLIES FUEL AND TO SUPPLY BARRIER GAS WHEN THE FIRST MEANS SHUTS OFF THE SUPPLY OF FUEL.

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