US2053652A - Smelting furnace - Google Patents

Description

' Sept. 8, 1936. P. c. BLANCHARD' ET AL 2,053,652

SMELTING FURNACE I 2Filed Jan. 12 1935 4 Sheets-Sheet l INVENTORS I ATTORNEYS Sept. 8, 1936- P. L. c. BLANCHARD EI'IAL 2,053,652

SMELTING FURNACE Filed Jan. 12, 1955 4 Sheets-Sheet 2 LJtO [S p 8 19 P. c. BLANCHARD El AL I 2,053,652

SMELTING FURNACE Filed Jan. 12, 1935 4 Sheets-Sheet 3 ATTORNEYS Sept. 8, 1936- P. 1.. c. BLANCHARD ET'AL 2,053,652

SMELTING FURNACE Filed Jan. 12 1935 4 Sheets-Shet 4 flimmQ-w m WAmT/MW MMMNG fl a 4 MWWF EM Patented Sept. 8, 1936 PATENT OFFICE 2,053,652 SMELTING FURNACE Paul Louis Charles Blanchard, Maurice Hlie Valentin Delot, and Roland Arthur Pigal,

Paris, France Application January 12, 1935, Serial No. 1,468 7 In Great Britain January 27,1934

13 Claims. (Cl. 263-33) The present invention relates to smelting furnaces for metallurgical use of the type comprising a burner for liquid fuel and it has chiefly for its object to employ, in such furnaces, burners in which the flame can be made more or less reducing, at will, and assures a perfect fusion of the metal and the exact refining which is desired. I

The burner of the furnaces according to the present invention is so arranged that the provided flame will be annular, i. c. it consists of an inert central part surrounded by a layer of particles of carbon in combustion. Such a flame is preferably obtained by means of a liquid fuel injector, including atomization means adapted to project the atomized liquid obliquely with reference to the longitudinal axis of the injector, in order to form a cloud having the form of an outwardly flaring sheath with thin walls, said injector being so directed that the annular flame will be flattened down when in contact with the liquid bath.

The conditions of thecombustion and distribu' tion of the particles of carbon are modified in the part of the flame in contact with the bath. The number of carbon particles per'unit of surface becomes greater in this part which will thus have a reducing action upon the bath. This reducing action will naturally be greater or less.

according to the greater or less flattening of the flame when in contact with the bath, and the burner is preferably mounted for variable directions, so that the flattening may be regulated: at will.

In spite of the reduction of the heat produced, in contact with the bath, by such flattening, the flame will maintain a constant rate of working when in contact with the arch of the furnace, and the heat imparted by this archwill form a sufficient additional supply in order to raise the bath to the desired temperature.

Use has already been made of liquid fuel injectors with mechanical atomization which produce an annular flame with inert central part, but as far as-we are aware, such burners have never been proposed incombination with metallurgical furnaces.

This use is attended with difficulties, due to the fact that during the operation of the furnace, the injector is subjected to the contact of the hot air of combustion, and also to the strong radiation of the smelted bath of metal.

The invention has further for its object to eliminate all drawbacks which might be found in the use of such burners under these conditions,

and it relates to means for cooling the fuel circulating in the injector during its operation, and preferably in combination with more eflicient means /for cooling the injector when not in operation, thus preventing all coking of the oil -Which may remain in the burner.

The cooling during the operation is advantageously obtained by the use of at least one outer tube or tubes surrounding the injector clear to its end. The interior of such tube is adaptd for a circulation of air or other fluid by which the fuel will be effectively cooled until it leaves the injector.

When air is used for the cooling, it flows at high speed between the said outer tube and. the injector, and this air is then delivered into the furnace, from the end of the injector. In order to prevent the form of the flame from being changed by the sheet of air thus produced, there is preferably mounted, next the outlet of the said outer tube, a deflecting surface or the like, which deflects the stream of air, thus forming a widelyflaring sheet. A

In order to increase the protection, the said outer tube is preferably surrounded by a second outer tube and a circulation of air at --a slowrate between" these two tubes will. prevent all heating of the first mentioned outer tube.

On the other hand, means are provided for circulating air through the interior of the injector when it is not in operation in order to expel the oil and to prevent all formation of coke.

The whole apparatus consisting of the injector and its outer tube is preferably mounted on a member having a curved surface and providing for leakless conditions and telescoping supports afford a ready change of direction for the injector, and its degree of insertion into the furnace can also be regulated.

The invention is preferably applicable to revolving furnaces, of the known types, or of analogous types, and it will greatly improve the qualnace or the like is pierced, near its central part through which the barrel of the burner passes, with a large aperture which may be preferably closed by a movable glazed inspection piece.

According to another characteristic of the in vention, the said chamber is so arranged that a sheet of air, at the side of the inspection aperture next the furnace, will protect the glass from the heat radiated from the furnace and from all heating due to the hot air of combustion.

In a preferred form of construction, a register having a sight-hole covered with a clear glass pane and another sight-hole covered with a coloured glass pane, is slidable in front of the abovementioned aperture, in such way that it may be opened or may be closed .by one or the other of the said glazed sight-holes.

This arrangement permits-and to our knowledge this has never as yet been obtained-a permanent inspection of the hearth of a revolving smelting furnace, without stopping or changing the operation of the burner or the furnace, and it is further possible to make, in the same conditions, 9. pyrometric examination of the furnace and of the metal.

On the other hand, the size of this opening when it is uncovered may be such as to give passage to an appliance for taking out samples or for adding certain substances to the smelted mass, without interfering with the operation of the burner or the furnace.

The said chamber for air circulation provided with the barrel of the burner is pivotally mounted on a column or the like which is distinct from the rotary part of the furnace and the opening which the said conduit uncovers when it is pivoted about will provide, if need be, for a rapid charging of the furnace.

The air for the combustion is preferably brought to the said conduit through the interior of the said column which is preferably hollow.

Further characteristics and advantages of the invention will be set forth in the following description with reference to the accompanying drawings which are given solely by way of example.

Figs. 1 and 2 are diagrammatic views, in longitudinal and in cross section, of a furnace according to the invention with the use of a moderately reducing flame upon the bath;

Figs. 3 and 4 show the same furnace with a strongly reducing flame upon the bath;

Fig. 5 shows the end part of a furnace according to the invention as an elevational view with parts broken away;

Fig. 6 is a section on the line VIVI of Fig. 5;

Fig. 7 is a section on the line VII-VI[ of Fig. 5;

Fig. 8 is a partial section of a burner on a larger scale;

Figs. 9, l0 and 11 are sections on the lines IX-IX, XX and XI-XI of Fig. 8.

Fig. 12 is a partial section on the line X|IX[I of Fig. 13 of the end of the injector and Fig. 13 is a corresponding partial longitudinal section.

In the form of construction shown in Figs. 1

' 1 and 2, the revolving furnace comprises a chamher I provided with rings 2 co-operating with rollers 3 and adapted for rotation by means of a motor 4. The chamber I is provided with a refractory lining 1 in which is an orifice 8 for the entrance of air and an orifice 9 for the discharge of the burnt gas, leading into an ofitake conduit III. A blast box I2 is mounted on the chamber l adjacent the orifice 8, and it is provided with an air inlet conduit An injector i3 traverses the blast box l2 and opens into the oriflce 8. The oil is supplied to the injector l3 through the conduit I4, and leaves the injector through an atomizer |5 which is mounted at the other end of the injector I3 and comprises for instance a great number of small orifices through which the oil issues'tangentially to a cone IS. The inclination of the injector |3 in the orifice 8 may be changed in any suitable manner.

The operation is as follows:

A layer of smelted metal I1 is located on the hearth of the furnace and the flame consists of a neutral region l8, bounded by a surface IQ of revolution about the axis of the injector l3. This surface I9 is surrounded by an annular combustion region 20 (Fig. 2). This'region is flattened in the part in contact with the bath l1 and there is thus formed a region 2|, in contact with the bath in which the combustion is disturbed and which has a reducing effect as above explained.

Figs. 3 and 4 show the injector which is inclined with reference to the bath, that is with reference to the revolution axis of the furnace. In this case, there is formed in contact with the bath a region 23 in which the combustion is quite incomplete, and in which the flame has a marked reducing action. An intermediate combustion region 24 connects this region 23 with the complete combustion region 20 in which the flame produces the maximum heat. It is observed that in all these cases, the part of the furnace forming the arch is highly heated and that the exchange of heat by convection and conduction are thus very effective.

Figs. 5, 6 and 7 show, with certain details, the part of the furnace provided with the burner |3 which is mounted at the centre of the back part 25 of the conduit |2 for the air of combustion. An aperture 26 is provided in said part 25. At the outer part of this aperture and on its sides are mounted two guides in which is slidable a register 28 having three openings 29, 30, 3|, and on whose side is mounted a rack 32. Into the openings 29 and 3| is fitted a white glass pane and a coloured glass pane respectively. A pinion 33 mounted on a shaft 34 engages the rack 32 and can be operated by a lever 35. Two setscrews 36 and 3! allow of holding tne register 28 in the desired position.

An air chamber 38 connected to the inner part of the blast box 2 delivers a sheet of air through the orifices 39 in front of the register.

During the normal operation of the furnace, the coloured glass pane 29 for instance is brought by means of the rack 32, pinion 33 and lever 35 in front of the aperture 26 and affords the view of the inside of the furnace which is at a white heat and permits a constant inspection.

In order to make a pyrometric observation, the white glass pane 3| is brought in like manner in front of the aperture 26.

In order to take out samples, or to make any desired additions, the aperture 26 is uncovered by means of the opening 30.

The register is held in place at will by screws 36 and 31.

The chamber |2 for air flow is pivotaliy mounted on a column 40 which is distinct from the rotatable part of the furnace. The air enters through this column and supplies the conduit through an aperture 4|.

Leakless conditions between the column and the conduit are obtained by means of two packing pieces 43 and 44 which provide for the free expansion of the column 40 when the hot air circulates in the same.

The opening 45 which is uncovered by the rotapacking piece 41.

tion of the conduit about the column 40 is of sufficient size to allow the charging of the furnace if necessary.

The burner is mounted on the back part 25 by means of a bearing piece with curved surface 46, whose leakless mounting is assured by a spherical The leakless mounting of the burner in the said bearing piece is obtained by a packing piece 48 which allows the burner to slide in the piece 46 when it is to be more or less inserted into the furnace,

Three telescoping supports 50, 50', St I are mounted between the back part 25 and the burner. The length of said supports may be kept constant by nuts 52, 52', 53. The support 5! permits to change, at will, the direction of the burner in the horizontal plane and the supports 50, 50', in the vertical plane, leakless conditions being always assured by the packing 41, 48.

As shown in greater detail in Figs. 8 to 13, the injector of the known type consists of a cylindrical body 54 terminated by a feeding device 55 provided with perforations 55'. The liquid fuel is circulated through these perforations 55? into the annular channel 56' communicating by tangential inlets 56 with a tapered atomizing chamber 51. chambersets up a movement of rapid rotation and is projected outwardly, obliquely with reference to the longitudinal axis of the injector, thus forming a hollow conical cloud. The liquid fuel is supplied under pressure by the conduit 6| (Figs. 5, 6 and 7) between the cylindrical member 54 and an inner tube 6ll, and the part of said liquid which is in excess passes through the orifices 50' into said tube 60 which is adapted to return it to a tank or the like. i

The injector is surrounded by an outer tube 62 clear to its end. Said tube is connected with the burner, within the furnace, by a threaded cap 63 pierced with'holes 64 (Figs. 8 and 9). The cap 63 is provided, adjacent the outlets of the holes 64, with a deflecting member 65 whose direction is such that it will deflect the air issuing from these orifices in a plane which is practically perpendicular to the latter. The tube 62 is pierced in its portion situated outside the furnace with an aperture 66 making connection with a tube 67 for an intake of air, and the space between the tube 62 and the cylindrical body 54 is closed next the tube 61 by a plug 68.

The tube'62 is surrounded by an additional outer tube m which is held concentric with the tube 52 by a member H pierced with transverse orifices l2 (Figs. 8 and 10). The space between these two tubes is open, in the interior of the furnace, and-is closed at the end outside the furnace by a threaded member 13. The tube l carries a support 14 whose cylindrical interior serves to contain the tube 61 and comprises, in the same transverse plane, the projections l cooperating with the telescoping members 50, 50',

The tube 61 is simply inserted into the support M and is more or less driven against the tube 62 by a nut 16 which is screwed to said support and co-operates with a projection 1'! provided on the outside of the tube 61. On the other hand, the arrangement is such that the tube 61 will not have a leakless connection with the orifice 66 of the tube 62 and thus a part of the air delivered into the tube 61 will escape into the space between the tubes 62 and 10.

The air under pressure supplied to the tube 61 and flowing at high speed in the outer tube- The oil introduced tangentially into this 62 will cool the injector and will escape through the orifices 64.

This cold air escaping at'the end of the burner will be deflected by the deflector 65, and this will give this air the form of a practically fiat sheet which will offer no prejudice to the fiame and will not change its shape. The leaking between the tube fill and the orifice 66 allows the flow of a certain amount of air between the two tubes 62 and '10, so that the tube 62 is'protected in the most approved way, and can operate without difficulty in a furnace employed in metallurgy.

Piping 80 (Fig. '7) provided with a gate-valve 8! provides for the circulation of the air in the interior of the injector when it is not operating, in order to expel the whole of the oil and to prevent all formation of coke when the fuel feed is parts without departing from the principle of our invention'as comprehended within the scope a of the appended claims;

What'we claim is:

1. In the combination of a smelting furnace, the bottom part of which is adapted to contain a smelted bath with a liquid fuel burner, a liquid fuel injector forming part of said burner, and provided with anatomization chamber at least a part of which is of conical form, meansfor supplying to said chamber liquid fuel under pressure, said chamber being adapted to form with said fuel a cloud having theform of a hollow sheath with thin walls and whose beginning part is of conical form, a refractory conduit disposed around said injector and along at least a part of the length of the latter, means for blowing air under pressure in said conduit, said injector being so directed with reference to said bath that the flame obtained will be in contact with the smelted bath andthus flattened.

2. In the combination of a revolving furnace in the bottom of which is a smelted bath with a liquid fuel burner, a burner adapted for mechanical atomization, a chamber one wall of which is transversal with reference to the revolving axis of the furnace, forms one end of said furnace and carries said burner, means for circulating air through the inner part of said chamber into said furnace, an aperture in said wall near the central part of said end wall, a piece at least a part of which is transparent and adapted to close said aperture.

3. A combination as claimed in claim 2 comprising further a chamber open along at least one side of said aperture, means for connecting said last named chamber to the inner part of said first named chamber in order that a sheet of air will be transversely formed in said aperture.

4. A combination as claimed in claim 2 wherein said piece comprises a sight hole covered with a clear glass pane and another sight hole covered by a coloured glass pane, means for sliding said piece in front of said aperture in such way that it be closed by one or the other of said sight holes or may be opened.

5. In combination of a revolving furnace with a liquid fuel burner, an injector adapted for mechanical atomization, a chamber one wall of which is transversal wit? reference to the revolving axis of the furnace, forms one end of said furnace and carries said burner, means for circulating air through the inner part of said chamher into said furnace, a fixed hollow column, means for pivotally connecting said hollow column and said chamber, an aperture in the lateral wall of said column opening the inner part of said latter through which air is blown to the inner part of said chamber.

6. In the combination of a revolving furnace in the bottom of which is a smelted bath with a.

liquid fuel burner, a burner adapted for mechanical atomization, a chamber one wall of which is transversal with reference to the revolving axis of the furnace and forms one end of said furnace, a central aperture in said wall, a fuel injector angularly and lengthwise movable in said aperture, at least two supports between said injector and the outer part of said wall, means for varying the length of said supports.

7. In the combination of a revolving furnace containing a smelted bath of metal with a liquid fuel burner, a liquid fuel injector forming a part of said burner, means for supplying said injector with liquid fuel under pressure, said injector being adapted to form with said fuel a cloud having the form of an outwardly flaring hollow sheath with [thin walls, a refractory conduit disposed around said injector and along at least a part of the length of the latter and means for blowing air under pressure in said conduit.

8. A liquid fuel burner more particularly adapted for a smelting furnace and comprising a liquid fuel injector, at least one tube surrounding said injector, means for supplying the space between said tube and said injector with air traversing said latter, a deflecting member outwardly flaring in front of the issuing end of said space, making contact with the outer surface of said injector, and adapted to deflect said air substantially transversally with reference to said injector and further means for circulating cooling air within the injector when it is not operating.

9. A liquid fuel burner more particularly,

adapted for a smelting furnace and comprising a liquid fuel injector, at least one tube surrounding said injector, means for supplying the space between said tube and said injector with air traversing said latter, a deflecting member outwardly flaring in front of the issuing end of said space,

making contact with the outer surface of said injector, and adapted to deflect said air substantially transversally with reference to said injector and a further tube surrounding said flrst named tube, means for supplying the space between said tubes with air traversing said latter and issuing at the end of the burner.

10. A liquid fuel burner comprising a liquid fuel injector, a tube surrounding said injector and provided with an opening,afurther tube surrounding said last named tube, a tubular projection on said last named tube in front of said opening, a tubular member slidably mounted in said projection and whose section is greater than the section of said opening, means for fixing said tubular member and means for supplying said tubular member with air.

11. In the combination of a smelting furnace the bottom part of which is adapted to contain a smelted bath with a liquid fuel burner, a liquid fuel injector forming a part of said burner, means for supplying said injector with liquid fuel under pressure, atomization means included in said injector and adapted to project atomized fuel obliquely with reference to the longitudinal axis of said burner thus forming said fuel into a cloudy outwardly flaring hollow sheath with thin walls, a conduit disposed around said injector and along at least a part of the length of the latter and means for blowing air under pressure in said conduit, said burner being further adapted to be so directed with reference to the bath surface that the flame will become flattened when in contact with said bath.

12. A combination as claimed in claim 11 including further at least one tube surrounding said injector, means forsupplying the space between saidtube and said injector with air traversing said latter, a deflecting member outwardly flaring in front of the issuing end of said space, making contact with the outer surface of said injector, and adapted to deflect said air substantially transversally with reference to said injector.

13. A combination as claimed in claim 11 wherein said furnace is of the revolving type.

PAUL LOUIS CHARLES BLANCHARD. MAURICE HELIE VALENTIN DELOT.

ROLAND PIGAL.

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