SU804696A1 - Method of incresaing strength of electric arc furnace crown - Google Patents

Description

(54) METHOD FOR INCREASING THE STABILITY OF THE ELECTRIC ARC FURNACE

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The invention relates to the production of metals and alloys and can be used in electric and steelmaking shops of metallurgical and machine-building plants.

Methods are known for improving the durability of electric arc furnaces by using artificial cooling of masonry. However, a sharp increase in the resistance of the roof, which is achieved by using artificial cooling, is associated with an increase in the specific energy consumption for smelting a ton of steel.

There is a method of improving the durability of a brick vault of an electric arc furnace by heating its inner surface during the periods between melts. In one of such constructions, curved collectors are located around the perimeter of the roof for supplying fuel to the burners directed towards the center of the roof Tl.

The disadvantage of this method is that fuel is consumed for heating the roof.

In addition, when installing a hot roof on the furnace after the charge is filled, the refractory brick will abruptly cool down, which leads to chipping.

It is known that at heating and cooling rates of masonry from basic refractories of 20 degrees / min or more, stresses occur in the brick, resulting in chipping.

A known structure in which the burners are installed in the roof, which allows it to be heated not only during the periods between melts, but also into the melting of C2,

The disadvantages of this design include significant energy costs for maintaining the temperature of the roof, the complexity of the implementation of the method of increasing resistance.

Claims (3)

The closest to the invention is a method for increasing the resistance of the holy arc of an electric steel-making furnace by leveling the temperature conditions of the arch masonry. The way is. that in the period between melting and melting of the shnhta, the inner surface of the roof is heated to GB. However, this method is effective only in the g case, if the inner surface of the vault is uniformly heated in area so that the rate of change of temperature e e of the inner surface is sufficiently low. In addition, the implementation of the method is associated with high energy costs for heating, especially in furnaces of engineering plants operating 1-2 shifts per day. The purpose of the invention is the elimination of thermal shocks of the arch during the period between melts. The goal is achieved by the fact that during the period between melting the inner surface of the roof is insulated, and the flow rate of the gas-air mixture is controlled during the campaign to reduce the temperature of the inner surface of the roof within 5-15 degrees / min. FIG. 1 shows a scheme for implementing a method for increasing the durability of a set of electric arc furnaces; in fig. 2 — node 1 in FIG. 1. After the melt is discharged, the vault 1 is withdrawn from the furnace 2 and is isolated from the environment by placing it on a support 3 made of tetsoiaol cytopic material (for example, chamotte). The installation of arch 1 on the stand 3 eliminates heat transfer from the inner surface of the arch by convection. The radiation of the inner surface of the roof leads to the heating of the insulating layer of the base. In order to avoid thermal shocks, the rate of cooling of the inner surface of the roof is regulated by feeding the gas-air mixture through the burner 5 into the cavity 4 formed by the inner surface of roof 1 and stand 3, which must be maintained within 5-15 degrees / minute. . If the cooling rate of the pack is maintained at less than 5 K / min, then by the beginning of the melting, the inner surface of the dome will have a temperature above 13OO C. Starting from this temperature, it will sharply decrease due to heat transfer from the cold ones piled into the furnace. At a rate on the cooling of the inner surface of 8 4 and more than 15 deg / min, stresses will arise in the lower layers of the refractory, resulting in chipping. Maintaining the rate of change of the temperature of the arch within 5-15 degrees / min allows to avoid thermal shock, which is dangerous at 12OO-1300 ° C. The implementation of the proposed method for increasing the durability of the arch of an electric arc furnace is not reduced to heating its inner surface during the period between melting, but to slow cooling 4Tq ensures the operation of arch refractories without chipping, because after filling the cooled arch is placed on the furnace where the cold mixture is filled. The implementation of the proposed method reduces the proportion of heat used, accumulated by the laying of the roof, which is transferred to the charge in the known method, leads to a decrease in the consumption of electrodes, since the convective currents of cold air through the electrode holes in the period between melts will be excluded. If..the loss of heat accumulated by the masonry in comparison with the known; in a way in terms of value is compensated by saving the electrodes, the economic effect can be calculated from the condition of increasing the resistance of the arch by 25%. Claims of the invention The method of increasing the resistance of the arch of the electric arc furnace, which includes the gas-air mixture under the vaults, is characterized in that, in order to avoid thermal shocks, the inner surface of the vault is insulated during the period between melts the inner surface of the arch is within 5-15 degrees / min. Sources of information taken into account in the examination 1. USSR author's certificate number 247971 ,.kl. C 21 C 5/52, 1968; 2. USSR author's certificate NS 44О416, cl. C 21 C 5/52, 1973. 3. USSR author's certificate number 438704, cl. C 21 C 5/52, 1974.