US756891A - Rotatory electric tube-furnace. - Google Patents

Description

No. 756,891. PATENTBD APR. 12, 1904.

H. N. POTTER. l

ROTATORY ELECTRIC TUBE JFURNACE.

APPLICATION FILED 11011.21, 1901.

No MODEL.

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UNiTED STATESn resented April 12, 1904.

PATENT OFFICE.

HENRY NOEL POTTER, OF NEW ROCHELLE, NEW YORK, ASSIGNOR TO GEO. WESTINGHOUSE, OF PITTSBURG, PENNSYLVANIA.

ROTATORY ELECTRIC TuBE-FURNACE.

SPECIFICATION forming part of Letters Patent No. 756,891, dated April 12, 1904.

Application filed November 21, 1901. Serial No. 83,078. (No model.)

To a/ZZ whom, it may concern:

Be it known that I, HENRY NOEL POTTER, a citizen of the United States, and a resident of New Rochelle, in the county of Westchester and State of New York, have invented cer tain new and useful Improvements in Rotatory Electric Tube-Furnaces, of whichthe following is a specification. Y Owing to the fact that magnesia is the only known metallic oXid which is not reduced by carbon at high temperatures, forming a carbid therewith, it has been proposed by Moissan and others to construct furnaces the main body of which is of carbon and the lining of magnesia. Moissan built such furnaces, heated by the electric arc inside the furnaces. Through the furnaces he passed a carbon tube, within which he carried out reactions not readily possible in contact with the arc-vapors. An objection to this arrangement is that it leads necessarily to an unequal distribution of the heat in the interior of the tube. Besides, the arc-furnace cannot be as thoroughly jacketed as the tube itself, for which reason more heat is required than if the tube were heated by passing electric current di; rectly through it. It has, indeed, been suggested that a carbon tube constituting the main part of a furnace-wall shall be heated by the passage of current, an independent tube of zirconia, magnesia, or the like being inserted within the carbon tube and designed to act as the lining of the furnace. 4It is found, however', that such a lining-tube When made of magnesia and subjected to the great heat developed in the tube of carbon undergoes great shrinkage and buckles out of shape, so that the lining is of small practical utility. When zirconia is used, carbid of zirconium is formed, and with either of the materials named disturbances of the reactions withinv the furnace and of the tube itself are liable to take place by reason of the porosity of the lining material. ismelted, it becomes very dense, solidifying on cooling into a transparent non-porous crystallinemass, through Which vapors cannot pass. Being under these conditions in the state of highest density and having no fur- When, however, magnesia` ther tendency to polymerize, the magnesia does not shrink under the action of heat. The

present invention contemplates utilizing these.

properties of fused magnesia in the construction of an electric furnace in which a carbon tube is lined with fused magnesia, the lining being attached by actually fusing the lining material to the wall of the carbon tube. By virtue of the described construction I obtain not only the advantages arising from the magnesia being in a fused state, but I also prevent any warping or buckling of the lining material, since the latter adheres strongly to the carbon surface and is not detached or distorted .by the heat.

In specifying fused magnesia as the material of they lining I do not necessarily mean magnesia which is actually melted at the time of use.

It is my purpose not only to line the carbon tube with fused magnesia, as above set forth, but also to coat the tube externally with the same material and vby substantially the same process.

In the present specification I not only show and describe a furnace constructed as above, but I also illustrate a method of attaching the magnesia in a fused state to the interior of the carbon tube.

It will be understood that the entire tube, consisting of the wall of carbon, with its lining and coating of fused magnesia, is to be Well jacketed by some good heat-resisting material, such as calcium oXid.

The first step in the manufacture of the described furnace is to prepare the carbon tube and coat it, preferably with fused magnesia, and then jacket it with calcium oXid and provide circuit-terminals for the carbon tube. The next and final step in the manufacture of the furnace is to attach the lining of fused magnesia. This I accomplish by arranging the otherwise-ready tube in a suitable cage, so that the tube shall be horizontal. Then by including the carbon tube as a resistance between the terminals of the circuit (or any other suitable way) I vheat it hot enough to melt the magnesia, and I then rotate the tube, so as to cause the molten magnesia to floW over the inner surface of the carbon tube. In this way when suitable care is taken a dense even lining of fused. inagnesia can be spread upon the inner surface of the tube, thus suppl ying' a highly-refractory surface to the furnace-wall.

For many purposes, such as the Continuous operation required for producing metallic chromium, it is of advantage to set the completed furnace at an angle, say, of thirty degrees with the horizontal, .introducing the chrome oxid, with carbon, into the upper end of the furnace and working it steadily through until metallic chromium runs out from the lower end into a suitable crucible. Such a process is described by Moissan, and other continu ous processes, wherein a liquid (especially a viscous one) or a powder has to pass slowly through a tube by reason of its own weight, are known to the art. All such processes are aided by turning or rotating the tube, and for this reason the present invention further contemplates the construction of a rotatory elect-ric tube-furnace having' the capacity for rotation already described and also having the capacity of causing' the tube to assume any desired angle, as may be required by the different characteristics of the materials treated in the furnace. Accordingly one feature of my invention relates to the means whereby such rotation, whether horizontal or angular, may be obtained.

A tube-furnace such as that above described having a bore of two inches and a length of one foot might well take over one thousand amperes at live volts. I propose to transform this current into a current of, say, live arnperes and one thousand volts, and as a matter of convenience I propose to mount an adequate transformer or transformers, together with the tube-furnace as a whole, in a barrel or on trunnions within a suitable cage and rotate the whole combination. This is another detail of my invention which will be fully described in the present specilication.

The foregoingligures are given merely as an example of magnitudes which it is possible to use with a furnace such as I have invented.

My invention is illustrated in the accompanying drawings, in whichH Figure 1 is a longitudinal section through my electric furnace. Fig. 2 is a transverse section therethrough; and Fig. 3 is an elevation and a part section of a completed furnace, showing the means for rotating' the same and of adjusting its angular position.

Referring to Figs. 1 and 2, 1 is a tube of carbon, and 2 is the lining of fused magnesia. rI`he covering of fused magnesia is represented at 3, and end pieces of magnesia are shown at 4 4. r1`he whole is jacleted with calcia or some other goed heat resisting material (shown at 5) and this may in turn be surrounded by an outer casing-tube 6, of tile or Portland cement. The terminal connections are made tl'nough the medium of split rings of metal, rings 8 8, of carbon, being inter posed between the split metallic rings and the ends of the carbon tube. The split rings 7 7 are provided with flanges 9 9 to assist in holding the end pieces f1- 1. A furnace thus constructed may be mounted, as shown in Fig. 3, in a frame made up of beveled rings 1() 11 and crosspieces 12 12, secured to the said beveled rings. The furnace is mounted in collars 18 18, secured to rings 10 11, and its split-ring terminals 7 7 are connected by leadwires let 1&1 to the secondaries 15 15 of transformers 16 16, the primaries 17 17 of which are joined by wires 18 18 to collect nriugs 19 20. Through brushes 21. 22, which bear upon the collector-rings 19 20, the primaries of the transformers are coi'mected to the circuit 23 24 of the generator 25. At 26 I show a controlling-switch for the generator-circuit and at 27 a conventional regulator. rlhe furnace, (the outside casing of which appears at 6 in Fig. 3,) the transformers 16 16, and the collector- rings 19 and 20, together with the insulated support 89 for the said rings, are all mounted on and held in position relative to one another by the frame already described. The transformers 16 16, as well as the collector-ring support 89, are fastened to the cross pieces or braces 12 12, as shown. The ring 10 :is plain, and the ring 11 is provided with gear-teeth. l he described frame and its attached part are rotatory about the axis of the furnace, and to this end it is carried in a cage carrying rollers 27, 28, 29, and 30 and others not in the plane of the drawings, but similar and similarly mounted. The cage consists of rings 31 32, yolced by straps 88 84. r1`he rollers 27 28 29 3() are mounted in the rings 31 and 82. The rollers 29 and 80 are mitergeared and mesh with the gear of the ring 11, the roller 30 being provided with a crank or turning it when the ring llland the parts connected therewith are to be rotated within the cage 31 82 38 81. The rollers 27 28 are smooth faced and against them bears the ring 10. The cage is supported from an eyebolt 36 and chain 87, there being' a second eyebolt 38 at the opposite end of the cage for tipping the cage at various angles other than that at which it will hang from a single chain.

In operation current enters the transforrners from the line, and the sccondaries supply the requisite voltage and current through the tube 1, heating' it.

To form a lining for the tube, the latter is brought so that its axis is horizontal, and a rod of inagnesia is inserted. The li'urnace being heated enough to meltthe magnesia is ro tated by the handle 86 to cause themelted magnesia to flow over the inner-tube surface.

Vhen used for the purposes of a furnace, the latter is easily hung at an angle and the material to be heated passed .in from the upper end, the rotation of the furnace causing IOS IIO

current-transformers for supplying current thereto, the furnace and the transformer or transformers being attached to a common support, and the said support being adapted to rotate.

3. A rotary furnace having one or more current-transformers connected thereto by suitable'terminals, the furnace and the transformers being mounted upon a common support, the said support being provided with suitable terminals connected withv the primary or primaries of the transformer or transformers, and being adapted to rotate in combination with sliding or flexible connections coperating with the said terminals.

4c. A tubular electric furnace open at both ends and adapted to rotate during its operation about the aXis of the tube or a parallel axis, means for maintaining said tube in any one of a selected number of positions with relation to the horizontal, and means for causing the rotation of the tube in any selected position.

5. A tubular electric furnace adapted to rotate about the aXis of the tube, means for maintaining said tube in any one of a selected nurnber of positions with relation to the horizontal, means for rotating the furnace in the selected position, the whole being supported in an adjustable cage, as set forth.

6. A tubular electric furnace mounted in a suitable frame, in combination with a cage outside the frame, and means for rotating the frame within the cage.

7. A tubular electric furnace mounted in a suitable frame, in combination with a cage outside the frame,means for rotating the frame within the cage, and means'for adjusting the angle of the cage and the parts separated thereby.

8. Atubular electric furnace, a frame supporting the same, a cage surrounding the frame, means for rotating the frame within the cage, and means for suspending the cage in a variety of positions with respect to the horizontal.

Signed at New York, in the county of New York and State of New York, this 19th day of November, A. D. 1901.

' HENRY NOEL POTTER.

Witnesses:

GEORGE-H. STOGKBRIDGE, WM. H. CAPEL.

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