Metallurgical apparatus – Means for treating ores or for extracting metals – By means applying heat to work – e.g. – furnace
Patent
1996-12-06
1998-04-14
Kastler, Scott
Metallurgical apparatus
Means for treating ores or for extracting metals
By means applying heat to work, e.g., furnace
266184, C21B 708
Patent
active
057388229
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a shaft furnace charging device with rotating chute, comprising a supporting structure overhanging the shaft furnace, a batch hopper supported by this supporting structure, a drive housing for the chute which is connected in a sealed manner on one side to the batch hopper and on the other side to a mounting flange to be fixed rigidly to the shaft furnace, and at least one large diameter roller ring mounted in the housing in order to support said rotating chute.
Devices of this kind are described, for example, in the documents U.S. Pat. No. 3,693,812; U.S. Pat. No. 3,880,302; U.S. Pat. No. 3,81 4,403; U.S. Pat. No. 4,941,792 and U.S. Pat. No. 5,022,806. In these devices, the chute is suspended in a rotating cage, which is supported in the housing by means of a large diameter roller ring. The rotating cage defines the lower part of an axial flow channel connecting the batch hopper to the chute, and the large diameter roller ring surrounds this axial flow channel on the outside. The roller ring is designed to take up a large axial force and a large tilting moment. It comprises two coaxial rings connected by rolling elements. One of the two rings is fixed rigidly to the rotating cage, while the other ring is fixed rigidly to a supporting plate incorporated in the housing. The housing itself has a lower flange by means of which it is rigidly supported on the mounting flange fixed to the shaft furnace. The batch hopper is connected in a sealed manner to the housing, either rigidly or through the intermediary of an expansion joint. In short, in known devices, the weight of the chute is rigidly transmitted through the supporting plate and the housing to the mounting flange of the shaft furnace.
Many charging devices fitted with a suspension for the chute of this type have been in service on blast furnaces for more than 20 years. The large diameter roller ring is the most reliable method currently known for providing the rotating suspension for the chute in the housing.
Although this type of suspension for the rotating chute gives complete satisfaction, it should nevertheless be pointed out that the working life of the large diameter roller ring achieved in practice is substantially lower than the working life that could be expected according to calculations. This phenomenon has been known for some ten years, but one skilled in the art could not until now explain why in practice the roller ring has to be replaced sooner than predicted by calculations.
SUMMARY OF THE INVENTION
The basic problem addressed by the present invention is to increase the working life of the roller ring in a device of the type described in the preamble.
This problems finds its solution in at least one deformable linking element which is incorporated in the chain of rigid elements mechanically connecting the mounting flange, fixed rigidly to the shaft furnace, to the roller ring supporting the rotating chute, in such a way that a transmission of the deformations of said mounting flange to said roller ring is largely avoided.
A certain merit of the present invention is to have understood that the mounting flange fixed rigidly to the shaft furnace undergoes asymmetrical deformations which affect the working life of the roller ring. These deformations of the shaft furnace mounting flange are due on the one hand to the internal pressure prevailing in the shaft furnace and on the other hand to thermal expansions of the shaft furnace. Their asymmetry is probably due to the fact that the dome of the shaft furnace, to which the mounting flange is rigidly fixed, is a non-symmetrical structure which has, for example, several large local openings. Consequently, this dome is asymmetrically deformed under the combined effect of the internal pressure and the stresses of thermal origin. Moreover, this dome is not necessarily heated uniformly. In fact, the internal refractory lining may be thinner at certain places, which naturally produces an asymmetrical heating of the dome and hence, in the
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Lonardi Emile
Reuter Georges
Thillen Guy
Kastler Scott
Nath Gary M.
Paul Wurth S.A.
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