CS214938B1 - Sunken hat of the arc furnace with centric incline - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc furnace hat, particularly for the production of ferroalloys, with the possibility of application to utilize the waste heat generated by the metallurgical process in an arc furnace.

The current rapid development of the steel industry places high demands on expanding the production of ferroalloys for the production of alloyed steels. Outputs of arc furnaces reach outputs of up to 100 MW. A big problem with these furnaces is the dedusting of the escaping gasses and the more the more gasses are produced on the march. In the past, the hats of these furnaces were opened and the amounts of air supplied reached 15 to 20 m ³ per 1 kW of kiln output. In order to reduce air intake, manufacturers are addressing tight hats in two alternatives. Fully tight hats that prevent almost complete air ingestion or partially tight hats that, while limiting the intake of large amounts of air, will burn incoming air beneath the hat leaking carbon monoxide from the charge, resulting in degassing temperatures of 700 to 1000 ° C. Such high temperatures make it possible to introduce steam and possibly electric energy when flue gas is introduced into the flue gas boilers.

Such hats have been developed by manufacturers of arc furnaces such as e.g. by Demgo ELKEM and others.

The shape of such hats, sometimes called even lowered hat, is a cylindrical polyhedron with a flat ceiling of the hat. In terms of stiffness, this ceiling must be reinforced to prevent it from being deformed by the weight of the insulating lining.

Also, the combustion of carbon monoxide, which is formed largely in the space between the electrodes, takes place at low gas velocities, causing considerable pulsations during combustion. For this reason, it is necessary to carefully seal the electrodes through the ceiling of the hat to prevent leakage of polluted offgasses at the transition points of the hat.

The aforementioned drawbacks and the problem are solved by a hat whose ceiling decreases from the edge of the hat towards the center and the exhaust vent holes are located on the edge of the hat. In addition, the suction openings located on the pyramid-shaped suction extensions above the base of the hat create a natural thrust thereby guaranteeing in the event of leakage of the electrode passage through the hat ceiling suction of external air and thus preventing the escape of gasses through these passages. Reducing the top of the hat at the central portion equates the flow of off-gases from the center to the exhaust settings. The solution can be used especially in arc furnaces for the production of ferroalloys. It is preferable especially for large outputs (above 15 MVAJ when the natural tensile effect is more pronounced. It is not excluded to use such a hat also in other arc furnaces such as steel, cast iron etc.).

The accompanying drawings show a possible case of solution where FIG. 1 shows a schematic cross-section through a hat (1) and a furnace (4).

The cap (2) of the hat (1J) decreases from the side walls (3) towards the center at an angle and whose size is from ⁵⁰ to 20 ^° , preferably from 7 to 10 ° for larger furnaces. 11) on the upper part of which the exhaust ducts (12) are located, thereby exhausting the hot exhaust gas from the furnaces The supporting exhaust ducts (11) are inclined from the side walls of the hat (3) to the ceiling (2) at an angle β. 5 to 25, and ⁰ shown exhaust flue gases from the furnace of the cap (1) to the suction pipes (12).

The side walls (3) are either attached to the furnace shells (41) or are mounted on the lining of the furnace (42). The shape of the support suction adjusters (11) may be triangular, square, pyramidal and the like.

In FIG. 2 is a plan view of a hat (1) showing possible locations of the exhaust ducts (12) relative to the electrode openings (13) with the location of a possible central panel (14) facilitating the assembly of the individual parts of the ceiling (2). This central member located between the electrode apertures (13) need not have a slope of the ceiling (2) at an angle and may be horizontal.

Claims (2)

SUBJECT A lowered arc furnace hat, particularly suitable for ferroalloy furnaces, characterized in that the ceiling (2) decreases to the center of the furnace (1) at an angle (α) of from 5 to 20 °. invention 2. Apparatus according to claim 1, characterized in that on the ceiling (2) there are mounted exhaust suction extensions (11) which enclose an angle (β) of 5 to 25 ° with the ceiling (2).