SU808821A1 - Steel melting furnace cooled shaft - Google Patents

Description

(54) COOLED STEEL FURNACE ARCH

The invention relates to metallurgical production and can be used in the smelting of metal.

The water-cooled roof is known, which has a water cavity and a refractory coating, and provides an increase in durability compared to refractory brick vaults by a factor of 15–20, which leads to savings in refractories; reduced electrode consumption f.

The disadvantages of a water-cooled roof are the increased consumption of electricity and cooling water due to heat losses through the roof, as well as reduced safe conditions; his work, due to the possible burning of the lining, which can lead to the ingress of large amounts of water into the working space of the furnace. Evaporation of water in the water cavity and release of hot water vapor into the workshop is also possible.

Also known is a water cooling roof (which is characterized by the fact that its central part is thicker than the peripheral one and it is not cooled, and in the lining of the peripheral part there are channels through which water 2j is fed.

However, the arch has the same drawbacks as the previous one.

Also known is a water-cooled roof, which has a water-cooled cavity with a refractory coating, characterized by the fact that some of the elements are water-cooled.

0 cavity made of plastic masses Sz.

The known arch has the disadvantages inherent in the first two arches, which limit its use.

five

The purpose of the invention is to reduce specific energy consumption and cooling water, as well as to improve safety conditions.

This goal is achieved by

0 that a gap is made between the metal frame and the refractory obmuzka, and the layer of refractory coating from the working surface of the surface is melted, and a heat shield is installed in the gap.

The drawing shows chilled arch.

The cooled roof, for example for an electric arc furnace, has a hollow metal frame 0, in the cavity

which are welded stiffening ribs (not shown), serving at the same time as guides for the most efficient movement of cooling water, and a layer of refractory coating 2 with a smooth glitter surface 3 of the vault facing the furnace working space. Between the metal frame and the layer of refractory coating there is a gap 4 in which a heat shield 5 is installed. Water is supplied to the water-cooled cavity through pressure pipes 6 located along the outer shell of the water-cooled cavity, and the water is drained from the cavity through the center of the water-cooled cavity, and the cross-section of the drain pipe is consistent with the total cross-section of the pressure pipes. The number of pressure pipes at least two. In accordance with the size of the electrodes, holes 8 are made in the arch for the electrodes.

The code works as follows.

The radiant heat incident on the roof is partially reflected by the melted shiny surface 3 of the roof due to the fact that it has a lower degree of blackness, estimated at about two times the degree of blackness of the surface of conventional archs, while also reducing heat losses through the arch two times compared with the known water-cooled vaults, as can be seen from the formula

Q -r.). 4 oL4oo / MOO / J

where d is the heat flux through the roof (W / m);

 „- degree of blackness of the surface

vault;

GO is the radiation coefficient of an absolutely rigid body (W / m2. K4). Tr.r- gas temperature in the working

furnace space (K); T is the temperature of the surface of the roof of the refractory coating (K).

The remaining heat is absorbed by the refractory coating 2 and transferred to the gap 4. The screen 5 installed in the gap 4 also reflects a certain amount of heat. The calculation of the effectiveness of screen reflections is carried out according to the formula

. gg-n

-I

o „nd„ tt,% S.n e.p. oh

where g is the heat flux through the roof in the presence of a screen (W / m)

g - heat flux through the vault without screen (W / m);

 oe e.g.p reducible coefficients of radiation systems, respectively, the surface for cr-. Plasma coatings - screen surface; screen surface - heat pipes surface; - surface for fastening coatings - heat pipes surface (W / m – K).

The results of the calculations show that even the oxidized steel sheet with a degree of blackness of 0.7-0.8 surfaces is used to fasten the coating, the screen and the surface of the metal frame facing

5. To the 3 tap it will allow to reduce the heat flow not less than twice. If necessary, the gap 4 is filled with an inert gas.

Thus, the overall decline

0 heat flux through the arch with the use of a glossy surface 3, refractory coating 2 and screen 5 will be about 75% of the heat flux through the water-cooled arch. The rest of the heat from screen 5 is transferred

water circulating continuously in the metal frame 1.

The total cross section of the pressure pipe 6 is consistent with the cross section of the discharge

pipes 7. When the frame 1 is mechanically damaged, water fills the gap 4 between the screen 5 and the frame 1, and if the screen 5 is damaged, the entire gap

4 between the refractory coating 2 and the frame 1, while the proposed arch can continue to work as a normal water-cooled arch. The increase in temperature exiting

vault, indicates that the vault is out of order, when this water from the frame 1 does not fall into the working space of the furnace.

The proposed cooled water, for example, for a steel-smelting electric-arc furnace, provides, along with savings of refractories, a reduction in heat loss through it, which leads to a decrease in specific energy and cooling water consumption, as well as the safe operation of the Steelmaking Department personnel.

Claims (3)

1. Metallurg 1974, p. 2324. 2. Japanese Patent 51-34362, cl. C 21 C 5/52, 1971. 3. Authors certificate of the USSR 5 505870, cl. F 27 D 1/02, 1974.