JPS582574B2 - Direct current electric heating reduction furnace - Google Patents

Description

[Detailed description of the invention] The present invention relates to a passion reduction furnace using direct current.

The first electrically heated reduction furnaces that came into operation towards the end of the 19th century were of the direct current type.

As a result of the advent of three-phase alternating current generators and improvements in power transmission, electrothermal reduction furnaces could now be operated using alternating current.

However, improved methods of converting alternating current to direct current using dry rectifiers have recently opened up new possibilities for using direct current in electrothermal reduction furnaces.

With respect to electrothermal reduction processes, all such DC type furnaces that have been used in the past, to the best of the inventor's knowledge, have a single top electrode and a single bottom electrode.

Such furnaces are much smaller than normal industrial AC furnaces and are mainly used for experiments.

However, direct current has some advantages for certain methods since it has lower specific current consumption due to lower current losses.

When using a DC furnace, as in the case of electrolysis plants, it is necessary to provide a dry rectifier between the furnace and the second side of the furnace transformer.

This transformer is provided with a step connector so that it is always possible to obtain a voltage that is compatible with the process and furnace load.

Within a certain voltage range, the size and cost of a rectifier depends only on its current.

Therefore, relatively large and costly electrical equipment is required to achieve the same load as in a three-phase AC furnace with three top electrodes.

Thus, even if this type of DC furnace is large, it is questionable whether it can economically compete with the Sanwa AC reactor, and attempts to create a competing DC reactor have not been successful so far.

The inventor has now discovered a connection arrangement that allows the voltage and furnace load to be increased without increasing the cost of the electrical equipment.

The furnace of the invention is not provided with a bottom electrode, but instead has four top electrodes with pairs of electrodes connected in series.

With a furnace with two top electrodes, the same amount of current as with a furnace with one top electrode and one bottom electrode, with a doubling of the voltage, and with the use of the same rectifier in both cases, the furnace load is doubled. is obtained.

The furnace of the invention is equipped with a circular furnace pot with four electrodes arranged in square positions, whereby a very good utilization of the furnace area is achieved.

The top electrodes are connected in series in pairs, with the same electrode dimensions providing current doubling as well as voltage doubling.

That is, the furnace load will be four times greater than for a furnace with a single top electrode and a single bottom electrode.

A polarity reversal device prevents crater formation over a long period of time.
) and equal electrode consumption is obtained.

A single polarizer is used in the busbar system for each counter electrode.

This polarity changer consists of a contact that acts as a connecting member, and the change of pole occurs when the contact moves transversely to the busbar midway through the busbar.

Pole conversion can also be adapted to branch paths.

As mentioned above, such polar conversion results in uniform consumption for different electrodes.

Compared to a circular AC furnace with three electrodes of the same size, the load of the furnace according to the invention is 4/3 times greater due to the use of a DC furnace with four top electrodes connected in series in pairs. It can be.

The use of larger electrodes in DC furnaces makes the furnace even larger.

The reason is that with alternating current the current displacement increases greatly with the largest electrode dimension.

This also means that electrodes in a DC furnace can be supplied with a larger amount of current than corresponding electrodes in an AC furnace.

Next, the present invention will be further explained with reference to the drawings.

FIG. 1 shows a melting furnace including a charge 2 and a melting bath 3, where 4 is an electrode.

The current from the rectifier 5 passes through the bus 6 to two bar bundles.
bundle) 7 and from there to the paired electrodes (one rod bundle is provided for each counter electrode).

The two electrodes in each pair are connected in series.

A current flows from the electrode acting as an anode through the semi-molten charge 2 to the electrode acting as a cathode, with the main part of the current flowing into the molten bath 3.

In each rod bundle 7 there is provided one pole inverter 8 which can be controlled remotely.

A given polarity change cycle can also be ensured such that four different arrangements of anodes and cathodes are obtained in a suitable arrangement.

Losses due to current displacement, eddy currents and hysteresis are significant problems in the largest AC reactors installed today.

These losses are avoided by using direct current.

Thus, after a certain period of time, savings in electrical consumption are obtained that are comparable to the additional costs associated with electrical equipment.

Also, best utilization of the rectifier is achieved by connecting two or more furnaces in series so that a larger number of electrodes are connected in series.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a circular furnace with four top electrodes, and FIG. 2 is a top view of the same furnace as FIG. In the figure, 1 is a melting furnace, 2 is a charge, 3 is a molten bath, 4 is an electrode, 5 is a rectifier, 6 is a bus bar, 7 is a rod bundle, and 8 is a polarity switch.

Claims (1)

[Claims] 1. Using four electrodes arranged in square positions, connected in series in pairs such that one electrode in each pair acts as a cathode and the other electrode acts as an anode. An electric heating reduction furnace operated by direct current applied by a vertical electrode group inserted into the electric heating reduction furnace from above. 2. Claims consisting of the fact that the mechanical properties of the pair of electrodes can be reversed by a polarizer, and the polarizer is arranged to connect the paired electrodes between the pair of electrodes and the rectifier. 1st
The electric heating type reduction furnace described in section.