US3578793A

US3578793A - Variable flame oxy-fuel burner

Info

Publication number: US3578793A
Application number: US733100A
Authority: US
Inventors: Robert D Jones; Keith A Miller
Original assignee: Air Products and Chemicals Inc
Current assignee: Air Products and Chemicals Inc
Priority date: 1968-05-29
Filing date: 1968-05-29
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18
Also published as: GB1273629A; JPS4931165B1; FR2009535A1; DE1924812C3; DE1924812A1; DE1924812B2; BE732375A

Abstract

An oxy-fuel burner for use in a metallurgical furnace is disclosed which can be controlled to regulate the configuration of the burner flame to provide a flame shape varying from a wide ''''umbrella'''' shaped flame to a narrow ''''pencil'''' shaped flame. Several methods of using such burners in metallurgical furnaces are also disclosed.

Description

United States Patent [72] lnventors Robert D. Jones; 3,043,577 7/1962 Berry 239/132.3 Keith A. Miller, Allentown, Pa. 3,202,201 8/1965 Masella et al. 239/132.3 [21] Appl. No. 733,100 3,302,596 2/ 1967 Zinn 239/132.3X [22] Filed May 29, 1968 3,334,885 8/1967 Taylor 239/1 32.3 [45] Patented May 18, 1971 3,346,190 10/1967 Shepherd 239/1 32.3 [73] Assignee Air Products and Chemicals, Inc. FOREIGN PATENTS Anew, 1,249,2s3 11/1960 France 23 9/1323 Primary Examiner-Lloyd L. King VARIABLE FLAME OXY'FUEL BURNER Att0rneysRonald B. Sherer and B7 Max Klevit 6 Claims, 5 Drawing Figs. [52] US. Cl 239/ 132.3 [51] Int. Cl B05b 15/00 I: of Search 1 An oxy fuel burner for use in a metallurgical fur. 423, 433, 434-5 nace is disclosed which can be controlled to regulate the configuration of the burner flame to provide a flame shape vary- [56] References and ing from a wide umbrella shaped flame to a narrow pencil" UNITED STATES PATENTS shaped flame. Several methods of using such burners in metal- 3,224,679 12/1965 Kear et a]. 239/] 32.3 lurgical furnaces are also disclosed.

"4F l6 I4 15 I 2a M so I 1 1a 1 I II/ I i I, 1 /r '5 /%h rollfluuwylmng ee ggggga VARIABLE FLAME OXY-FUEL BURNER BACKGROUND OF THE INVENTION ,of both ferrous metals, e.g., steel and steel alloys, and nonferrous metals, e.g., copper. U.S. No. Re. 26,364, for example, discloses several processes involving the use of oxy-fuel burners for the production of either ferrous or nonferrous metals in various furnaces.

It has now been discovered that the optimum shape of a flame from an oxy-fuel burner depends not only on the type of furnace employed and the location of the burner in the furnace, but also on the material being processed, the condition of the material and the desired objective. For example, it has been found that one flame shape may be most beneficial for melting cold charges, whereas, other shapes may be more beneficial in later stages of the process wherein, for example, more narrow, higher velocity flames may be required to penetratethe slag layer. Prior to the present invention, all known metallurgical burners were of fixed, nonvariable flame shape except for the burner disclosed in US. Pat. 3,224,679 wherein a variable shape flame is produced by movement of a flame orifice relative to a cup structure into which and through the flame is projected. While this type of burner does permit a certain degree of variation of theflamc shape, the maximum width of the flame is severely limited by the surrounding cup structure. In addition, the movement of the flame orifice relative to a surrounding cup requires that a positive and negative pressure seal be provided, preferably in the forward end of the burner, to prevent the explosive oxygenfuel mixture from leaking rearwardly into the back of the burner and possibly exploding therein. Such effective seals are very difficult to provide while still permitting easy relative movement between the burner structure and the cup. Even more importantly, it is virtually impossible to attain any reasonable life of forward position seals due to the extremely hot and oxidizing conditions to which the forward end of the burner is subjected in a metallurgical furnace.

OBJECTS AND SUMMARY OF THE INVENTION 'ingfrom a very wide umbrella flame shape to anarrow pencil flame shape, as well as, to provide certain optimum methods of using such a burner in metallurgical furnaces.

In brief, the present burner is composed of onlythree main components. These are (1) an outer jacket having an annular ring portion, (2) an intermediate, annular ring sometimes referredto as a separator ring, and (3) a central bluff body. These three main components cooperate to vary the orientationof the flame orifice and the resulting shape of the flame. This is accomplished by movement of the bluff 'body and separator ring together relative to the sleeve ringas will be more fully described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a simplified illustration of the complete variable flame burner operating in one type of metallurgical fumace.

FIG. 2 is a fragmentary, cross-sectional view of the forward end of the burner showing one preferred manner of detailed construction.

FIGS. 3A, 3B, and 3C are simplified, schematic illustrations showing the relative positioning of the main burner components and the resultant 3 basic flame shapes which may be produced.

DETAILED DESCRIPTION Referring first to FIG. 1, the complete burner includes a lower, large diameter portion and an upper, smaller diameter portion 12 the latter of which is adapted to telescope into and out of the larger portion by suitable actuating means such as, for example, pneumatic or hydraulic cylinders 14. A simple packing gland 15 including a retainer 16 is provided at the extreme rearward end of the burner between telescoping

portions

10 and 12. A chain hoist system 17 is provided in order to raise and lower the entire burner relative to an associated furnace; a basic oxygen or B.O.F.-type furnace l3 being shown for purposes of example. Of course, many other types of mechanical systems may be employed in place of the cylinders and/or the chain hoist system.

Referring now to FIG. 2, the large diameter portion 10 consists of an outer, water-cooled jacket generally denoted by numeral 20. More particularly, jacket 20 is composed of a pair of elongated, concentric, spaced-apart

sleeves

21, 22 between which there is provided a third sleeve forming a baffle 24. At the forward or lower end of the burner as shown in FIG. v2, an annular, hollow jacket ring 26 is attached to the ends of

sleeves

21, 22 so as to form an end closure for the jacket.

As shown in FIG. I, cooling water is supplied to jacket 20 through an inlet pipe 28 such that it flows downwardly between inner sleeve 21 and baffle 24. The water than flows under the end of the baffle in hollow jacket ring 26 and upwardly between outer sleeve 22 and baffle 24 from which it exits through outlet pipe 30. In actual furnace tests, this particular cooling arrangement has been found to produce superior cooling of the outer sleeve 22 and the jacket ring 26 which are subjected to the highest temperature levels.

At this point, it should be noted that jacket ring 26 is of particular shape which is of critical importance to the burner operation. That is, the radially inner surface of the ring includes an axial surface 30, a smoothly curved surface 32, a straight diverging surface 34 and a second smoothly curved surface 36 which terminates at sharp comer 38. As will be subsequently explained in greater detail, this shape produces what is known as the Coanda effect and this materially contributes to the unique operation of the burner.

Referring now to both of FIGS. 1 and 2, it will be noted that the smaller diameter portion 12 is composed of an elongated sleeve 40 which is concentrically disposed within and spaced from jacket sleeve 21; packing gland 15 serving as a fluid seal between

sleeves

40 and 21. A hollow annular ring 42 is secured to the end of sleeve 40 and a pair of water'cooling pipes 44!, 46 are connected so as tosupply and withdraw cooling water to this ring. The upper ends of these pipes are shown in FIG. I and it will be apparent that water flows down one pipe, aroundthe interior of annular ring 42, and upwardly through the other pipe from which it is discharged. As stated hereinabove, ring 42 isconveniently referred to as a separator ring for reasons which will subsequently become apparent.

The shape of separator ring 42 is also important'to the proper operation of the burner and, in this regard, it will be noted that this ring includes an outer axial surface 5.0, a sharply rounded comer52, a flat diverging surface 54 and an inner axial surface 56.

Referring now to the central portion of FIG. 2, there is provided an elongated pipe 53 at the lower end of which there is provided a hollow bluff body which is generally in the shape of a doorknob. That is, the bluff body includes an axial surface 62, a flat divergent surface 64, a rounded edge 66 and a flat face 68. It has been found that the angle of divergence a should be between 90 and 150 and, most preferably, about 120. A second pipe 70 is disposed within pipe 58 and a circu' lar baffle 72 is secured to the end of pipe 70 within the hollow interior of bluff body 60. As shown in FIGS. 1 and 2, cooling water is supplied to inner pipe 70 through which it flows downwardly and then around baffle 72 and upwardly between

pipes

70 and 58 from which it is discharged.

From the foregoing description, it will be apparent that each of three basic components is internally water cooled and that these components collectively define annular gas passages between them. More specifically,

sleeves

21 and 40 define an annular passage 48 through which fuel such as, for example, natural gas is passed to the forward end of the burner; such fuel gas being supplied at the rear of the burner through fuel inlet pipe 74. Thus, the fuel gas flows downwardly through annular passage 48 and then through an annular nozzle passage 76 formed between

annular surfaces

30, and 50. Similarly, a second annular gas passage 49 is formed between sleeve 40 and pipe 58. This passage is used to supply oxygen from an inlet pipe 78 down to the forward end of the burner at which point it passes through an annular nozzle passage 80 formed by

surfaces

54 and 64. As a result, the fuel gas and oxygen are mixed in the annular region indicated by numeral 82 from which they issue as an annular jet of flame.

OPERATION TO VARY FLAME SHAPE From the foregoing structural description, it will be apparent that the fuel gas flowing through annular nozzle 76 is intercepted and mixed with higher velocity oxygen flowing through annular nozzle 80 such that a combustible mixture isv present in the annular orifice area indicated as 82. Of course, it will be understood that the actual position of the flame front is subject to considerable variation depending upon, for example, the velocity of each of the oxygen and fuel, the type of fuel and the pressure conditions existing in the furnace. Therefore, it is to be understood that although annular space 82 is referred to as the flame orifice, the actual flame front may vary from a position in the region of the throat formed by jacket ring surface 32 and edge 66 of the bluff body, to a position which is beyond the forwardmost edge 38, depending upon the above indicated conditions of operation. However, this variation in the actual position of the flame front in no way effects the ability to produce the flame shapes as will now be described with reference to FIGS. 3A, 3B, and 3C.

Referring first to FIG. 3A, the position of bluff body 60 is shown to be in its forwardmost position with respect to the lo cation of jacket ring 26. Also, as previously described, separator ring 42 is connected to and moves with the movement of the small diameter portion 12. Thus, it will be noted that surface 54 of the separator ring is in direct alignment with surface 34 of jacket ring 26. That is, these two flat surfaces lie along a common straight line. In this position, the flame is projected out of orifice 82 with a predominantly radial component. As a result, the flame jets out substantially purely radially and fonns a very wide, annular flame which looks very much like the shape of an umbrella. In this condition, the shape of jacket ring 26 plays a very important role in that the boundary layer of the fluid effluent strongly tends to adhere to and follow the smoothly curved surface of ring 26 until it reaches sharp edge 38. As previously stated, this boundary layer phenomenon is known and is called the Coanda effect, however, the utilization of this phenomenon in a burner to produce a wide umbrella like flame shape is believed to be unique to the present invention. In addition, it should be noted, that although the illustrated embodiment of the invention shows a sharp comer 38, it is within the scope of the invention to round corner 38 so that the fluid effluent actually issues with a predominantly radial but slightly rearward component of velocity. Such flames have actually been produced and the result is that the axial length of the umbrella flame is slightly shortened. Thus,

I even shorter, wider flames than that shown in FIG. 3A can be achieved by this technique.

Referring now to FIG. 38, it will be apparent that both the separator ring 42 and bluff body have been retracted slightly from the position shown in FIG. 3A. As a result, the fluid does not have a direct line of flow from surface 54 to surface 34. Thus, the Coanda effect is not established and the fluid effluent is deflected slightly forwardly by the jacket ring 26. Of course, there still is some radial component of velocity, but this is approximately equal to the axial component. In this condition, the flame blossoms out and forms a shape which is like a ball; i.e., it diverges radially outwardly but then eonverges slightly due to internal low pressure so as to form a rounded, blossom or ball-like shape.

The third basic flame shape is illustrated in FIG. 3C wherein it will be apparent that the separator ring and the bluff body have been retracted still further relative to ring 26. In this condition, the axial surface 30 of the jacket ring 26 serves to remove the radial velocity component and collimates the fluid effluent into a relatively narrow, axially directed flame which is relatively sharply pointed and pencillike in appearance. In contrast to the umbrella and ball-shaped flames which have a relatively low axial velocity, the pencil shape flame has a much higher axial velocity and, therefore, has greater penetration capability.

BURNER OPERATION IN FURNACES The above described burner has been operated in a metallurgical furnace wherein it produced a number of substantial benefits. In an open hearth furnace for example, the burner was first used to assist in melting solid scrap and pig iron which had been charged into the furnace. During this melting portion of the process, the burner was operated as shown in FIG. 3A. Also, it was operated as shown in FIG. 38, as well as in intermediate positions. In any event, it was operated with a relatively wide flame so as to melt as large a diameter role as possible in the solid charge without undue harmful effects to the furnace lining. As melting proceeded, the burner was repeatedly lowered by the chain hoist so that the flame was substantially always in direct contact with the solid charge as it melted down. As a result, the melting period was significantly reduced as compared with conventional open hearth practices. In addition, the burner was used later in the process during the refining period. At this time, the burner was operated as shown in FIG. 3C such that the concentrated, high velocity flame was able to penetrate the slag layer and directly'contact the molten metal undergoing refining. As a result, the bath temperature was increased more quickly and, by suitably increasing the oxygen to fuel ratio, the rate of decarburization was increased, Thus, there was a decided overall benefit in adjusting the flame shape at different periods of the steel making process.

From the foregoing description of burner operation, it is apparent that similar benefits may be obtained in various types of furnaces including both ferrous and nonferrous types. For

example, in a B.O.F. furnace charged with at least a partly solid charge, the present burner may be used for preheating and/or melting such as shown in FIG, I. Depending upon the size of the burner and the diameter of the furnace, the wide flame used for preheating or melting may be either the um- I brella shape, the ball shape, or some intermediate shape consistent with the furnace and burner size. Thereafter, in the refining period, the burner may be operated with a relatively more narrow flame when slag penetration is required. Thus, the burner may be used to produce the umbrella flame for melting and the bail flame for refining. On the other hand, if the umbrella flame is too wide for a given furnace diameter, the burner may be operated to produce a ball flame during melting and a pencil flame during refining.

Lastly, it must be emphasized that the three flame shapes illustrated in FIGS. 3A, 3B, and 3C are merely illustrative of not intended to be limited other than as three basic shapes which can beproduced and that these are in no way limiting since an infinite number of variations are obviously possible by proper relative movement of the three 7 main components. In addition, it is to be understood that the above described apparatus is inherently capable of operating "as an oxygen lance merely by shutting off the fuel supply.

' remove one burner and replace it with a lance. Furthermore,

there is the added advantage of varying the relative position of the bluff body such that the oxygen may be jetted into the bath with sufficient axial velocity to penetrate the slag without such undue velocity as would produce excessive splashing. That is, there is the option of injecting the oxygen as a substantially solid jet corresponding to the pencil flame, or as an annular jet corresponding to the lower axial velocities produced in the umbrella or ball-shaped flame.

From the foregoing description it will be apparent that the present burner is exceedingly versatile in its modes of operation and in the methods of use in various types of furnaces. In addition, it will be obvious that numerous modifications are possible including, for example, reversing the use of

passages

48 and 49 such that oxygen flows down passage 48 and fuel flows down 49. Of course, in this event the relative gas pressures and/or the nozzle geometry must be adjusted so that the velocity in diverging noule 80 is greater than that in axial nozzle 76. Obviously, this is necessary in order for the resultant mixture to have the required radial component of velocity so as to form the umbrella and ball shapes.

Other obvious modifications include reversing the direction of coolant flow, however, it has been found that the illustrated flow patterns produce the optimum cooling of the jacket ring and bluff body. Nevertheless, it is to be understood that the foregoing description is intended to be only illustrative of one embodiment of the invention, and thatthe true invention is expressly set forth in the following claims. 1

lclaim:

l. A metallurgical burner for use in a metallurgical furnace comprising, an outer elongated jacket extending along the major portion of the axial length of the burner, an annular jacket ring secured to the forward end of said jacket, an annular separator ring disposed concentrically within and slightly rearwardly of said jacket ring, said jacket ring and said separator ring being radially spaced apart so as to form a first annular nozzle passage therebetween, a bluff body disposed concentrically within and forwardly of saidseparator ring, said bluff body and said separator ring being spaced apart so as to form a second annular nozzle passage therebetween, said second nozzle passage diverging radially outwardly,'said bluff body and said jacket ring being radially spaced apart so as to form an annular flame orifice in fluid communication with both of said nozzle passages, means for supplying oxygen to one of said nozzle passages, and means for supplying fuel to the other of said nozzle passages for producing a combustible mixture in said annular flame orifice between said jacket ring and said bluff body.

2. The metallurgical burner claimed in claim 1 including means for varying the axial position of said bluff body and said separator ring relative to said jacket ring so as to vary the orientation of said annular flame orifice.

3. The metallurgical burner claimed in claim 1 wherein said bluff body is doorknob-shaped including an annular divergent surface forming one side of said second nozzle passage.

4. The metallurgical burner claimed in claim 2 wherein said jacket ring includes an axial surface portion forming one side of said first nozzle passage, a smoothly and radially outwardly curved surface portion, and a divergent surface portion, said surface portions forming a Coanda effect surface whereby said combustible mixture adheres to and flows along said 'acket ring surfaces and is discharged from the burner 18 a su stantially radial direction when said divergent surface of said bluff body is aligned with said divergent'surface of said jacket ring.

5. The metallurgical burner as claimed in claim 1 wherein said jacket comprises concentric, spaced apart outer and inner sleeves, a baffle member intermediate said sleeves and dividing said space into first and second annular coolant passages, said jacket ring being hollow and being secured to the forward ends of said sleeves so as to form a connecting coolant path around the end of said baffle, first conduit means at the rear of said burner for supplying coolant to one of said coolant passages and, second conduit means at the rear of said burner for discharging coolant from the other of said coolant passages.

6. The metallurgical burner as claimed in claim 1 wherein said bluff body is hollow, elongated conduit means extending from the rear of the burner to the interior of said bluff body,

' baflle means secured to the end of said conduit means and spaced from the interior of said bluff body whereby coolant flows through said conduit means and around said baffle means within said bluff body and, conduit means extending from said bluff body back to the rear of the burner for discharging coolant from said bluff body at the rear of said burner.

2292333? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 57 793 Dated y 18 9 7 Inventor(s) Robert D. Jones and Keith A. Miller It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

It is certified that error appears in the above-indicated patent and that said Letters Patent are hereby corrected as shown below:

In the title block, delete the name of "Robert D. Jones" Column 2, line 38, change "than" to -then--.

Column 4, line 23, change "pencillike" to -pencil-like.

Column 6, line 25, change "is" to --in-.

Signed and sealed this 19th day of October 1971.

(SEAL) Attest:

EDWARD M.F'LETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents

Claims

1. A metallurgical burner for use in a metallurgical furnace comprising, an outer elongated jacket extending along the major portion of the axial length of the burner, an annular jacket ring secured to the forward end of said jacket, an annular separator ring disposed concentrically within and slightly rearwardly of said jacket ring, said jacket ring and said separator ring being radially spaced apart so as to form a first annular nozzle passage therebetween, a bluff body disposed concentrically within and forwardly of said separator ring, said bluff body and said separator ring being spaced apart so as to form a second annular nozzle passage therebetween, said second nozzle passage diverging radially outwardly, said bluff body and said jacket ring being radially spaced apart so as to form an annular flame orifice in fluid communication with both of said nozzle passages, means for supplying oxygen to one of said nozzle passages, and means for supplying fuel to the other of said nozzle passages for producing a combustible mixture in said annular flame orifice between said jacket ring and said bluff body.

4. The metallurgical burner claimed in claim 2 wherein said jacket ring includes an axial surface portion forming one side of said first nozzle passage, a smoothly and radially outwardly curved surface portion, and a divergent surface portion, said surface portions forming a Coanda effect surface whereby said combustible mixture adheres to and flows along said jacket ring surfaces and is discharged from the burner is a substantially radial direction when said divergent surface of said bluff body is aligned with said divergent surface of said jacket ring.

6. The metallurgical burner as claimed in claim 1 wherein said bluff body is hollow, elongated conduit means extending from the rear of the burner to the interior of said bluff body, baffle means secured to the end of said conduit means and spaced from the interior of said bluff body whereby coolant flows through said conduit means and around said baffle means within said bluff body and, conduit means extending from said bluff body back to the rear of the burner for discharging coolant from said bluff body at the rear of said burner.