US1807090A - Charging means for electric furnaces - Google Patents

Description

May 26, 1931.

G. PISTOR CHARGING MEANS FOR ELECTRIC FURNACES Filed May 17, 1928 3 Sheets-Sheet 1 gnmhtob I W myflm May 26, 1931. G. PISTOR Filed May 17, 1928 3 Sheets-Sheet 2 e. PISTOR CHARGING MEANS FOR ELECTRIC FURNACES May 26, 1931.

Fiied ma 17, 1928 s Sheets-Sheet s 7. Iii- -31 1....inS-l f u a 0 W game/rem Lagg mim Patented May 265 1931 ,UNITED s'ra'naz s PATENT OFFICE GUSTAV BISTOR, F LEIPZIG, GERMANY, ASSIGNOB TO I. G. FABIBEN'INDUSTFIE v AKTIENGESELLSGHAFT, 0F FRANKIORT-ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY CHARGING MEANS FOR ELECTRIC FURNACES Application filed May 17, 1928, Serial No. 278,463, and in Germany Kay 18, 1927.

This invention relates to a method of charging electrical furnaces and to apparatus for carrying out said method. 7

The char 'ng material for electrical furnaces usual y consists of mixtures of raw materials of various kinds and of varying granular size and specific gravity, such as, for example, coke and'lime in carbide fur- .naces; coke, raw hos hates and silica (and 1 if necessary aluminium compounds) in phosphorus furnaces. It is only in the rarest cases that the ideal condition is realized, namely, that the size of the pieces or grains of the individual parts of t e charge is so uniform that no se regation occurs in charging or in the heap ormed on charging in the furnace. Reducing the pieces, to uniform size is generally attended with too much e2;-

pense, and owing to the different specific g0 gravities of the constituents of the mixture, does not prevent segregation. Segregation, however, is of considerable disadvantage since it leads to very troublesome irregularities in the operation of the furnace, such as variations in the conductivity of the charge at various points, local displacements of the path taken by the current, shortcircuits,

damage to the lining, im aired energy yield, and irregular removal 0 gas.

- It has now been found that in spite ofvery considerable differences in the size of the pieces or the specificgravity of the constituentsof the mixture, it is possible, by employing the'method of charging hereinafter described with reference to the accompanying diagrammatic drawings to attain uniform distribution of a composite mixture of raw materials in an electric furnace, i. e., a

distribution] which is not liable to segrega- 0 tion.

In the drawings, Fig. his a sectional elevation of one embodiment of the invention;

Fig. 2 is a sectional plan on the line 22 of Fig. 1; Y

Figs. 3 and 4 are "a partial sectional elevation and a partial sectional plan, respectively, of another embodiment of the invention;

Figs. 5 and 6 are a. partial sectional elevation and a partial sectional lan, respectively, of a third embodiment of t e invention; and

Figs. 7, 8 and 9 illustrate alternative modifications of the invention as applied to threephase electric furnaces.

represents the shell of the furnace, 2 represents the wall or lining, 3 are electrodes, 4 and 4a are pipes for charging raw materials,

5a, 5b and 5c are distributingguides which will be more fully described hereinafter.

Figs. 10 and 11 show in a rather diagrammatic form the continuous flow of the charge within an open and within a closed furnace zfind the persistent conditions resulting thererom.

According to the invention a definite path leading to the electrode is prescribed by means of guides for the material of the charge which is introduced in a continuous stream and any other movement of the same which may lead to segregation or other action is prevented. The guides employed consist of distributors 5a, 5b and 50, which are arranged in the furnace at a definite, and if desired adjustable, height and inclination, in such a manner that,they-conduct the charge (which may be shovelled in by hand or introduced from bunkers through pipes 4) to the electrode or electrodes 3, by virtue of their inclined position. The pipes 4 may open direct into the distributing surfaces-5 (as in Figs. 3 and 4), or they may be kept separate therefrom (as in Figs. l and 2). These distributing surfaces may be made of cooled or uncooled sheet metal, refractory brick or other suitable material.

Theshape of the distributing surfaces 50, 5b and 5c is solely determined in accordance with the attainment of their purpose. When the chargin pipe is in' dlrect connection therewith, t e triangular form 56 appears to be most suitable for the distributing vanes, the charge being admitted to one apex of the triangle from which it runs down in a continuous stream, at a rate corresponding to its consumption in the furnace, to the opposite lower side' (facing the electrodes). In order to prevent premature lateral overflow, the distributing vane can be made concave or provided with a rim.

reduction in the speed of the individual parts Preferably every electrode is surrounded according to its diameter by severalof such distributing vanes. If several electrodes are disposed sufliciently close together tobe served, for example, by one charging pipe, surrounded by the three electrodes of a threephase alternating current furnace (Fig. 7), the distributing vanes maybe allotted to'a common pipe, or inasmuch as; owing to the limited space, segregation cannot very well occur between three electrodes, the arrangement of a central distributihg vane can be dis pensed with in this case, so that only the outwardly directed sides of the electrodes receive the charge of material through distributing vanes. V

Where a freeoutlet is provided for the material from the charging-pipe, the dis tributing vanes 5a may" be approm'mately rectangular. The individual vanes may also consist (in case of one electrode) of a closed truncated cone (50, Fig. 6), or, when there are three electrodes, these may be triangularly disposed in relation to three partially open truncated cones interconnected at the points of intersection.

Owing to the broadeningof the current of material and to the check sustained at the electrodes, the manner in which the charge is distributed onto the vanes causes a uniform and lessens the tendency to segregation during the consumption of the mixture in the furnace. Thus, for example, it prevents the coarser constituents from rolling away quicker than the finer constituents, and the latter from remaining at the electrode, as usually occurs :in the case of a free slope as, for example, thevknownannularn'iethod of distribution at the electrode. a

In the method of charging of this invention, materials, the constituents of which vary to an extraordinary degree in point of' tions and must fall down thereon at the rate at which they melt away at the lower end of the electrodes. For example, prior to startlng, the furnace may be charged uniformly to the desired height, and such dportions of the, charge as are situated outsi action of the electrode will remain substantially unconsumed, the supply of new material remaining restricted to the reaction zone.

'(Fig. 10 and 11.) By this means, not only is the melting or reaction zone concentrated in a definite and invariable area, where the full action of the heating current can occur, but

e the range of also the uniformity of the throughput of material is assured. At the same time, uniform discharge of the reaction gases is secured,

these -flowing in counter-current to the cold charging mixture which descends directly along the electrodes, and preheating said mixture. The result of this heat exchange is that the gases generated during the reaction escape at a temperature of only a few hundred degrees centigrade,'while the mean to any disturbances resulting from the operation of the furnace.

The mixture of raw mater'al in-this case is placed, for example, in elevated bunkers outside the furnace, and ispassed from these to the electrodes through thecover of the furnace in closed pipes which are automatically kept full and which open into the distributing vanes at the required points.

Moreover, the hereindescribed method is not restricted to the use of the aforesaid mixtures of crushed or comminuted raw material, but homogeneous (for example, briquetted) charging stock can be fed in the same way. Similarly, even with other than round electrodes (forexample, sheaves of block electrodes) the new method of charging can be employed if the distributing surfaces be modified accordingly. The field of application of the method is also not restricted to the use of-circular furnaces; Figs. 8 and 9 showing embodiments for rectangular furnaces. It is essential in all cases that the charge should be admitted direct to the zone around the electrode as being the zone of consumption.

' .It has already been proposed to feed the charge to the electrodes into closed vertical furnaces from closed bunkers by leading the material at intervals over chutes to the elec-' trode and causing it to drop down along the latter. However, this method of charging lacks the characteristic feature of passing regulated, from the I tion cannot be obtained in the known processes' because, after leaving the sliding surand thereby undergoes segregation.

Exhaustive-researches haveshown that it faces, the material drops freely onto the heap is only by the complete avoidance of an free movement of the constituents of the c arge that the result attained by the present invention can be attained.

I claim:

1. An electrical furnace comprising, in combination, an electrode extending into the lower part of the furnace, means for passing means for withholding the charge from the upper part of the electrode, said means being placed within the furnace at a moderate distance above said distributing surface.

2. An electrical furnace comprising, .in

combination, an electrode extending into the lower part of the furnace, at least one substantially plane-shaped distributing surface slantingly protruding towards and into close proximity of the lower part of the electrode, so as'to allow the chargeafter having passed over the distributing surface to descend into the reaction zone in contact with the electrode through the gap, thus formed, and at least one pipe-like conduit for the charge deduit being arranged at a moderate distance scending into the furnace, at least part of the circumference of the lower aperture of said conduit being arranged at a moderate distance above said distributing surface.

3. An electrical furnace comprising, in combination, an electrode extending into the lower part of the furnace, at leastoone shovelshaped distributing surface slantingly protruding towards and into close proximityl the lower part of the electrode, so as to a the charge after having passed over the distributing surface to descend into the.reaction zone in contact with the electrode through the gap, thus formed, and at least one pipe-like conduit for the charge descending into the furnace, at least part of the circumference of the lower aperture of said conabove said distributing surface.

In testimony whereof, I aflix m signature. v

GUSTAV ISTOR.

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