RU1770392C - Method of electrode salt bath lighting up - Google Patents

Abstract

The essence of the invention: the ignition of the salt bath is achieved by creating a temporary local zone of ignition between the additional and one of the main electrodes, resulting from the melting of a portion of dry salt poured on the coke, which is installed between one of the main electrodes and the additional electrode, connecting to the second main electrode by passing electric current through electrodes and coke. 2 s.p. crystals, 1 tabl, 1 silt

Description

The invention relates to the heat treatment of products heated in molten corrosion-active salts and can be used in thermal and tool shops of engineering, tool and other plants in the manufacture of tools subjected to heat treatment with heating in molten salts.

A known method of starting freshly laid electrode baths, including the melting of salt due to the electric arc arising between the ends of the additional and main electrode. The disadvantage of this method is that it is acceptable only for the initial start-up of the electrode baths, for restarting it is not acceptable, because the ends of the electrodes will be in solidified salt. In addition, to create an electric arc, the voltage stage switch on the transformer is set to maximum current, which causes increased consumption of electric energy, rapid wear of the electrodes and the duration of the ignition.

A known method for starting electrode salt baths is the use of a salt melt due to the heat generated by a graphite plate installed between the main electrodes of the bath. The disadvantage of this starting method is the quick destruction and short life of the electrodes due to the formation of necks on the electrodes in places where the surfaces of the electrodes come in contact with graphite plates. And the start-up itself is time-consuming, due to the need to repeatedly switch the steps of the transformer with the maximum current strength to the operating current.

The closest to the claimed method of ignition of the electrode salt bath according to the technical essence and the achieved result is ignition, including fixing additional elements on the main electrodes, batch loading

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dry salt between the additional electrodes and the creation of a temporary volumetric zone of ignition in the center of the bath between the additional electrodes and loading an additional portion of dry salt onto the coke. The disadvantage of this method of ignition is the need to manufacture and install additional electrodes on the main electrodes, creating ..-- up to a 14 volumetric volume zone for ignition by switching voltage levels on a working transformer or due to another autonomous transformer and after forming a volumetric zone of ignition, additional electrodes must be removed be from the main electrodes. All this causes an increase in the ignition time of the electrode salt bath, and leads to uneven wear of the electrodes.

The purpose of the invention is to reduce the duration of ignition of an electrode salt bath while increasing the duration and uniformity of electrode wear.

This goal is achieved due to the fact that in the method comprising installing an additional electrode in the bath and connecting it to the opposite main electrode, portioning the dry salt, creating an ignition zone by placing coke on the dry salt in contact with the electrodes and turning on the transformer, igniting the salt electrode bath is due to the location of dry salt and the ignition zone between the main and secondary electrodes. Uniform wear of the electrodes is achieved by the fact that the place is in contact coke from the electrode firing zone is moved upwardly along the height of the electrode by providing a cushion of dry salt under the coke. As the ignition zone of the main electrode is worn to ensure uniform wear of the electrodes, the additional electrode is connected to the opposite main electrode alternately after 10 ignition cycles. The installation of an additional electrode between two main electrodes, the connection of an additional electrode with one of the main electrodes makes it possible to create a temporary local zone of ignition due to the heat generated by the electric current passing through the coke. A temporary local area is created at the operating voltage of the secondary winding of the transformer. As the dry salt melts, the temporary initial zone increases in volume, and the salt of the electrode bath begins to melt. After the volume of molten salt closes the main electrodes of the bath, an additional electrode is disconnected from the main electrode and further melting of the salt occurs due to electrical and thermal conductivity

molten salt between the two main electrodes of the salt bath.

Thus, the proposed method of ignition of the electrode salt bath satisfies the criterion of Significant difference, because It is characterized by simplicity and reliability, high ignition speed, economy, increased resistance and uniform wear of the electrodes.

The drawing schematically shows

5 implementation of the method:

1 - hardened salt of an electrode salt bath;

2- main electrodes;

3 - additional electrode;

0 4 - ignition zone of the main electrode;

5- coke;

6- dry salt;

7- connector;

8-current leads.

5 When firing the electrode salt bath between the firing zone of the main electrode 4 and the additional electrode 3, a piece of coke 5 is installed and a supply voltage is applied to the main electrode 4

0 and an additional electrode 3 through connector 7 and current leads 8. In this case, coke 5 is heated to a high temperature and dry salt melts, then the frozen salt of electrode 5 of the salt bath 1 begins to melt. After the salt melt closes the main electrodes 2, an additional electrode 3 is disconnected from the main electrode, and further ignition occurs due to the electric and thermal conductivity of the molten salt.

As wear occurs, the ignition site on the electrode is moved up the height of the electrode by creating a cushion of dry salt under the coke.

5 Example. For electrode ignition

furnace baths SP 35/10 install an additional electrode dia. 60 mm between the two main electrodes. An additional electrode is connected to the main

0 electrodes. An additional electrode is connected to the main electrode. Between the ignition zone and the additional electrode, we install a piece of coke, onto which we pour a portion of dry salt. Turn on the stove 5 bath. After the volume of molten salt closed between the main electrodes, the additional electrode was disconnected from the main one. Further ignition was carried out due to the electrical and thermal conductivity of the molten salt and through the main

electrodes. Operational tests of the electrode furnace bath SP 35/10, subjected to ignition by the claimed method and the prototype method are shown in the table. Conclusions: from the analysis of the table it follows that the ignition time is shorter, and the life of the electrodes and the uniformity of wear are higher with the claimed method than with the prototype.

The technical and economic efficiency of the claimed method is achieved by increasing the operating life, increasing the inter-shift periods of electrode replacement and reducing the time of the preparatory-final ignition operations.

Efficiency calculations were made for a site having 8 electrode salt baths.

Claims (3)

1. The method of ignition of the electrode salt bath, including the installation of an additional electrode in the bath and connecting it to the main electrode, portioned loading of dry salt, creating a zone of ignition by location on a dry salt of coke in contact with electrodes, the inclusion of a transformer, characterized in that that, in order to reduce the duration of ignition of the salt electrode bath while increasing the life of the electrodes, dry salt and the ignition zone are located between the main and additional electrodes, and an additional an electrode is connected to the opposite main electrode. 2. The method according to claim 1, characterized in that, in order to ensure uniform wear of the electrodes, the place of contact of the coke with the electrode of the ignition zone is moved up the height of the electrode by creating a cushion of dry salt under the coke. 3. The method according to p. 1. characterized in that, in order to uniform wear electrodes, the connection of the additional electrode with the opposite main electrode is alternated after 10 ignition cycles. Information about the operation of the furnace bath SP 35/10, ignition according to the claimed method and prototype.