US1336939A - Electric furnace - Google Patents

Description

S. BARFOEII.

ELECTRIC FURNACE.

APPLICAHONHLEU sarnz. 1916.

'LLM WITNESSES:

M We

Patented Apr. 13, 1920.

INVENTOR Svenda'rfod.

ATTORNEYS SVEND BARFOED, 0F BERKELEY, CALIFORNIA.

ELECTRIC FURNACE.

Specification of Letters Patent.

Patented Apr. 13, 1920.

Application led September 25, 1916. Serial No. 121,987.

To all whom t may concern.'

Be it known that I, Svi-inn BARFOED, a subject of the King of Denmark, residing at Berkeley, in the county of Alameda and State of California, have invented new and useful Improvements in Electric Furnaces, of which the following is a specification.

This invention relates to an electric furnacefor fixing nitrogen from air, and particularly to improvements on the furnace shown in my co-pending applicationV entitled Electric furnace for fixing nitrogen from air, filed January 19, 1916, Serial No 72,939.

The problem involved in the fixation of atmospheric nitrogen, that is the combination of nitrogen and oxygen in a stable form, is the production of sufficient heat to cause the combination, and thereafter a rapid cooling of the combined products to cause a permanent fixation.

To accomplish this" result, various forms of electric furnaces have been employed, many of which have been commercial failures due mostly to structural faults, lack of facilities for continuous operation, and a lack 0f proper arrangement of cooling and heating mediums. l

The object of the present invention is to overcome these difficulties and particularly to provide a novel form of water-jacketed furnace.

Another object of the invention is to provide an electrode of special construction and in conjunction therewith, means for evenly distributing the incoming air, and simultaneously cooling said electrode.

Further objects will hereinafter appear.

The invention consists of the parts and the construction and combination of parts as hereinafter more fully described and claimed, having reference to the accompanying drawing in which Figure l is a central vertical longitudinal section of the furnace.

Fig. 2 is an enlarged cross section of the lower electrode. Y

Fig. 3 is a plan View of same. Fig. 4 is an enlarged detail section on line 4 4 of Fig. 3.

Fig. 5 is a view similar to Fig. 2 showing another form of the lower electrode.

Referrin to the drawings in detail, A indicates t e furnace proper. In this instance consisting of a water-jacketed tube 2 into which projects a pair of electrodes 3 and 4. The electrode 3 is preferably solid and constructed of copper, steel, or any other metal desired, while the lower electrode consists of a refractory cup 5 which is, filled with metallic oXid such as indicated at 6 as will hereinafter be described.

The upper electrode is preferably made in sections which are adapted to be joined together by a connection similar to the one indicated at 7, and means have furthermore been provided for rotating said electrode and simultaneously forcing it into the furnace chamber S'at a rate which is just sufficient to maintain afiXed space between the electrodes, as burning away or consumption of the same takes place. The mechanism for rotating and feeding the upper electrode into the furnace chamber is a duplication of that shown in my co-pend'ing application and briefly speaking, consists of two sets of driven gears, such as indicated at 9 and 10. The gear train 10 being provided for the purpose of rotating the electrode and the gear train 9 for feeding the electrode into the furnace as consumption takes place.

Centrally disposed with relation to the furnace chamber 8 is a gas cooler generally indicated at- B. This cooler together with the tubulail casing forming thel furnace chamber 8, is insulated from the lower electrode 4 by a `fiber or asbestos plate 16, secured between flanges 17 and 18 as shown. The upper -electrode 3 passino* through the center of the cooler is therefore insulated from the lower electrode 4, and as this is in turn insulated from the`furnace chamber, it can' readily be seen thatan arc will be formedv between the electrodes.

The gas cooler employed in the present instance is cup shaped and in general appearance a duplicate of the cooler shown in my co-pending application. It is provided with an annular discharge passage 19 which communicates wit-h the furnace chamber 8, and is completely surrounded by a water jacket on both sides, a constant circulation in said jackets being-f maintained through pipes 22 and 23 which are connected with a source of water supply by means of l a pipe 21.

Centrally disposed in the lower portion of the cooler B and projecting into the upper end of the furnace chamber or the lower end of the annular discharge passa e 19, is a water-jacketed tube 24 through w ich the electrode 3 passes. This tube is provided for the purpose of guiding the electrode 3 and also for the purpose of cooling same.

Pipes 25 and 26 connected with the main pipe 21 and the return pipe 2la provides a. means for maintaining a constant circulation in the tube. The tube is furthermore provided with a stufling box 27 at its upper end which positively prevents any escape of gases between the electrode and the tube 24.

The shape and construction of the furnace chamber together with the construction of the lower electrode and means for admitting air to the furnace, constitute the main subject matter of the present invention.

Secured by bolts 30 to the lower flange 17 of the furnace is a cone shaped casing 31 which forms a support for the lower electrode. This electrode is supported on a disk shaped cast iron plate 32 which in turn is supported upon a pipe 33 extending through a stufng box 34 formed in the lower casing, and connected with a source of air supply suchv as a blower or compressor not here shown. The disk 32 is cored out to form a plurality of radially disposed air passages 35 which communicate with an annular discharge opening 36 formed in the periphery of the disk 32. Suitably secured on top of the disk is an insulating ring 37 and secured upon the said ring in any slmple manner 1s the refractory cup 5 which serves as a container for the metallic oxid of which the .electrode is constructed.

It is known that certain gaseouschemical compounds such as oXids of nitrogen are formed by passing air through or into immediate con-t'act with an electric arc. Many attempts have been made to produce compounds of this nature such as nitric acid, etc., on a commercial scale, but these attempts have proven more or less unsuccessful for the following reasons:

No furnace has seemingly been produced which Ais capable ot' continuous operation, nor has any furnace been produced in which the air or gases heated to a high temperature by the arc, is sufficiently rapidly cooled to permit fixation of the combined products. It is known that the gaseous chemical compounds formed at high tempera-tures easily decompose if they are not rapidly cooled from the high temperature at which they are formed, to a comparatively low temperature.`

The former cooler shown in my co-pending application and also in the present application has positively solved the problem of lrapidly cooling the air after it leaves the arc, while minor mechanical difficulties such as cooling of the lower electrode andthe interior wall of the furnace, have been overcome by the construction shown in the pres- -ent case.

In operation when an arc is formed between the electrodes, it is only necessary to admit the air from the blower or compressor under comparatively high pressure to the furnace chamber through the pipe 33 and thc annular discharge passage 36 formed in the base of the lower electrode. The air admitted through the pipe 33'passes through the radially disposed passages 35 then up through the annular passage where it is deflected inwardly against the exterior face of the cup containing the metallic oxid. This manner of admitting the air is of great importance as it cools the electrode to such an extent that boiling over of: any molten material is positively prevented. The air after striking the Iexterior surface of the cup -continues in an upward direction along the 4water cooled wall of the furnace chamber, and will consequently during its passage be brought into such intimate contact with the arc that the gaseous chemical compoundsl are formed. These compounds are however easily decomposed, if they are not rapidlyk cooled from the high temperature at which they are formed to a comparatively low temperature. This is overcome by the present arrangement as the large cooling area provided by the annular passage 19 permits such rapid cooling that comparatively little decomposition can take place. r

' By referring to Figs. 2 and 3 it will be seen that a plurality of angularlyy disposed vanes 40 have been formed in the annular discharge passage 36. This serves the functionA of dellecting the air or imparting a swirling movement to same which causes it to ascend upwardly valong the walls of the furnace chamber in a comparatively solid column. These vanes are of considerable importance as their function is not only one of producing a swirling movement, but also causes a more uniform heating and exposure of all the air passed through the furnace.

The vanes are of further importanceas the centrifugal action produced by the swirling movement of the ascending air column permits the inner layer of air to be acted on by the are while the outer layer serves as a cooling layer or insulation between the arc and the metal surface of the furnace.4 Similarly the heating of the inner layer causes an expansion of same and a circulation which permits it to contact with the outer chilled layer of air, thus permitting a permanent fixation to take place when mixing of the two air layers takes place. The whole air volume being of course cooled to a desirable degree by passing through the annular passage 19 as previously described.

For the purpose of permitting an even burning of the electrodes, a continuous rotation is imparted to the `upper electrode by means of the gear train 10. The lower electrode 4 will however remain stationary and would therefore have a tendency to burn unevenly unless means for swinging the arc isv employeda his is accompi' hed by a portion oi the annular discharge passage 336 by covered plate 50 or the like. 'lhe provision or' this cover plate prevents any air from discharging between the vanes at point of the annular discliarffe passage, and consequently causes an unbalancing or the ascending air column. Such unbalancing causes the arc to swing in a circ-le around the lower electrode, the radius oi the swinging movement depending entirely upon the degree ot' unbalancing produced, this being in turn regulated by increasing or decreasing the size of the covering plate 50. An even burning of both the electrodes is in this manner obtained Without resortin to any mechanical movement as tar as t e lower electrode is concerned, in fact it has been found in actual practice that rotation of the upper electrode may also .be eliminated in this instance as the 'unbalancing of the ascending air column will cause the arc to swing in a circle over both faces of the electrodes.

rlhe electrode shown in Fig. 5 is substantially the same as that shown in Fig. 2, the only di'derence being that the metallic oxid is entirely supported within a refractory cup 5, through the bottom portion oi which extends a plurality ci? metallic pins i6 which are provided for the purpose ci establishing a circuit through the cup.

inother feature provided in connection with this torni oi electrode is the annular groove i?, which serves the function of col looting any metallic oxid which might have a tendency boil overe rihe niateriais and nnish of the several parts of the device may otherwise be such as the experience and judgment oi the manuv facturer may dictate.

l Wish it understood that various changes in form, proportions and minor details or construction may be resorted to Within the scope oi the appended claims, and that l do not ivish limit myself to the specific design or construction here shovvne Having thus described my invention, what l claim and desire to secure by `Letters Pat ent is in electric furnace comprising an elongated Water-iaclreted tube, an electrode in each end or the tube, means for adinittiniair or gas at one end oi the tube and directing it through the sphereo action oi the electric arc, and means forming a continuation ora the other end of the tube rior rapidly decreasing kthe temperature oi the air or gas after it leaves the electric arc.

2. 1in electric iurnacecomprising an clonu gated Waterjaclreted tube, an electrode in. each end oi the tube, means ior admitting air or gas through an annular air passage formed at one end of the tube around oneoii the electrodes and directing it through the sphere of action of the electric arc, means ior imparting a swirling movement to the air during its passage through the tube, and means forming a continuation of the other end of the tube for rapidly decreasing'the temperature ot' the air or gas after it'leaves the electric arc.

3. The combination with an electric fur nace, of an electrodev mounted in one end or the furnace, said electrode comprising a holloW base member having an air intaire'open-v ing formed therein and an annular discharge passage and a cupshaped member on said base surrounded by the annular discharge passage and adapted to be cooled by the discharging air. y

i. The combination with an electric iurnace, of an electrode mounted in one, end oi the furnace, said electrode comprising a hollow base member having an air intake opening formed therein and an annular discharge passage, a cup shaped member pn said base surrounded by the annular discharge passage and adapted to be cooled by the discharging air, and deflectinn` members in the annular discharge pasage adapted to impart a swirling movement to the air as it leaves said passageu 5. rihe combination with an electric' i'urnace, oi an electrode mounted in one end'oi the furnace, said electrode comprising a huilloiv base member having a central air intake opening formed therein and an annular dis-1 charge passage, a pipe connected at one end with the central intake opening1 and at the other end with a source or air pressure supply, and a cup shaped member on said base surrounded by the annular discharge passage adapted to be cooled on its exterior surr'ace` by the discharging air, said cup serv ing as a container for a metallic oXid,

6. rllhe combination with an electric iurnace and the electrodes mounted therein, oi means ior rotating one oli the electrodes to continuously change the position oi the arc between the electrodes to permit even burning oi saine.

ln testimony whereof l'have hereunto set my hand in the presence of two subscribing Witnesses.,

SVEN@ BARFED,

Witnesses: y

donn il. limitarne, W. Eleanor',

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