US1336807A - Dabena - Google Patents

Description

L. ALMAGIA AND E. GUERRESCH|.

ELECTRIC FURNACE. APIPLICATIQN, FILED SEPT-23, 1912.

Patented Apr. 13, 1920.

UNITED STATES PATENT OFFICE.

LEONE ALMAGIA, 0F CORNIGLIANO LIGURE, AND ERALDO GUERRESCHI, 0F SAMPIER- DARENA, ITALY, ASSIGNORS TO SOCIETA ANONIMA ITALIANA GIO. ANSALDO & (3.,

OF COBNIGLIAN LIGURE, ITALY.

ELECTRIC FURNACE.

Application filed September 23, 1918.

To all whom it may concern Be it known that we, LEONE ALMAGIA, engineer, subject of the King of Italy, and residing at Cornigliano Ligure, Italy, and ERALDo GUERRESOHI, engineer, subject of the King of Italy, and residing at Sampierdarena, Italy, (the post-oflice address of both is: Societa Anoniina Italiana Gio. Ansaldo & (3., Cornigliano Ligure, Italy), have invented certain new and useful Improvements in Electric Furnaces, of which the following is a specification.

This invention has for its object to provide an improved apparatus and an improved electric furnace whereby, with the aid of an electrical machine, there can be obtained the control and the regulation of the distribution of the heat in the various parts of the bath, and an instantaneous automatic regulation of the short-circuit points, thus rendering it possible to supply the furnace with current fromany desired distri bution cables, even if such cables are employed for lighting a large district. This invention has also for its object to produce steel of superior quality.

One way of performing this invention is illustrated by way of example in the accompanying drawings in which:

Figure 1 illustrates an apparatus for a furnace worked with tri-phase current on the Heroult system. 7

Fig.2 is a diagram illustrating the voltages A, B, C between the electrodes.

Fig. 3 illustrates an apparatus for a furnace worked with tri-phase current on the Girod system.

Fig. 4 is a diagram illustrating the voltages:

AB=Bo= /5 being the voltages of each phase of the transformer.

Fig. 5 illustrates an apparatus for a furnace worked with tri-phase current on the Ansaldo system.

Fig. 6 is a diagram illustrating the voltages: ABIBCZGA being the voltages between the upper electrodes; ab=b0zoa being the voltages at the lower electrodes; aA=bB=cC being the voltages of each phase of the transformer.

Fig. 7 illustrates a furnace worked with Specification of Letters Patent.

Patented Apr. 13, 1920.

Serial No. 255,377.

tr -phase current on the Ansaldo system, with apparatus comprising an auxiliary transformer T Fig. 8 is a diagram showing the voltages without the auxiliary transformer T F 1g. 9 is a diagram showing the volta es with the transformer T ABzBOzaA being the voltages between the upper electrodes; abzbczca being the voltages between the lower electrodes; aAzbB OC being the voltages of each of the phases of the transformer.

The improved furnace, provided with the device shown in Figs. 3 and 7, differs from the electric furnaces at present in use in this that electrodes connected to the beginning and to the end of the several phases of a transformer (or alternator) are arranged upon the surface of the furnace and upon the bottom of the bath, the arrangement being such that the electric current is compelled to pass from an electrode to another at the surface of the bath, and from an electrode at the bottom to another electrode at the bottom, and from an electrode at the surface to an electrode at the bottom through the bath, in such a manner that the bath is traversed by electric currents in all directions and is thus heated not only at the surface as in furnaces at present in use, but is heated both at the surface and in the interior and at the bottom.

hloreover, in the apparatus shown in Fig. 7 with the transformer T a control of the heat is obtained, which heat may be regulated at the will of the operator during the metallurgic process, and therefore during the period of fusion, and in case great variations of current are perceived, the heat can be concentrated upon the bottom of the furnace.

During the refining process, it will be advantageous to heat also the slag zone for effecting desulfuration and dephosphoration, and to modify in other respects the heating of the bath according to the requirements of the moment, and with relation to the metal which it is desired to produce, by rendering the heating uniform throughout the mass of the bath during periods of time suggested by experience, thereby producing a metal of superior quality.

The transformer T besides permitting an ideal regulation of the heat, allows also Figs. 1, 2, 3 and 4;; if ,e represents the impedance of the system and Vs the voltage for the upper electrodes, there frequently occurs a short-circuit current represented by the following formula:

wherein C is a constant.

In the furnace on the Ansaldo system illustrated in Figs. 5 and 6, with theprinciples of the phases of transformer at the upper electrodes, we have 'on the contrary:

i where Z is the impedance of the hearth .or

bottom of the furnace. v

From this it results that the short-circuit current is already considerably smaller than in other furnaces; and is stillmore reduced in the apparatus shown in Figs. 7, 8 and 9 comprising a transformer T the transforming ratio of which is -0b7, so that we have now r V O V By making ia variable, it is possible to vary the heating at any point whatever of the bath either near the bottom or near the surface. 7

In fact, if we limit by WVsthe Watts used at the surface, 2' the watts used at the bottom,

we have:

W8 =f[ 1( l a =f[ 1( where the first function diminishes with the increase of a or vice versa, the second ing li ise 1W 3 Wz': a constant h nc it l w that the transformer T limit the points of shortfcircuit within the d s r d l mits n ll ws f teg et ngth-e eat f th furnace.

Ha ng n wp rt eju erly de i and ascertained the "nature 10f our Said invenim nd t meml r in whi h th s me is to be performed we declare that what we claim, is:

A device of the character described inu ng h ar h; a ov h r fo lelee former conducting wires T between the transother conducting wires between the transformer and the elec r d s th hearth, and a second transformer interposed in the st m t ned o duct ng Wi es a i series therewith.

In testimony whereof. we have hereunto ig ed ou ames in th p e n of two Wit- IIBSSGS. i

; LEONE ALMAGIA;

Witnesses:

CARLO LAR ZSI, AGOBTWO SALOMME- EB-ALDQ GUERBESCHI,

' ro esi h ea th an the cover, a trans r 7 former and the [electrodes in the cover,

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