RU2320781C1 - Cathode casing of aluminum cell - Google Patents

Abstract

FIELD: non-ferrous metal metallurgy, namely designs of cathode casings of cells for electrolytic production of aluminum.

SUBSTANCE: cathode casing includes lengthwise and end walls, bottom, support rings embracing walls and bottom and mounted at pitch along length of casing. Lengthwise box cross section beams are mounted in upper part of support rings; said beams are spaced by distance 20 - 300 mm from lengthwise walls of cathode casing and they are rigidly secured to said rings by welding or by means of bolt joint. Arrangement of box cross-section lengthwise beams in upper part of support rings that are spaced from cathode casing walls allows increase useful life period of aluminum cell.

EFFECT: increased useful time period, intensified operation of aluminum cell.

2 cl, 2 dwg

Description

The invention relates to the metallurgy of non-ferrous metals and can be aimed at improving the design of the cathode casing of the electrolyzer to produce aluminum by electrolytic method.

The cathode casing is one of the elements of an aluminum electrolyzer and is used to protect the lining enclosed inside it from the destructive action of the forces arising during the operation of the aluminum electrolyzer. In this regard, it should have the necessary strength, since the durability of the electrolyzer largely depends on the strength of the cathode casing. In addition, the cathode casing should provide heat dissipation, which contributes to the formation of a protective skull and nastily, the presence of which prevents the destruction of the lining and increases the service life, allows you to intensify the operation of the cell. This is of great importance for high power electrolyzers.

Known cathode casing of an aluminum electrolyzer, including the walls and the bottom, frames, covering the walls and the bottom and installed in steps along the length of the casing, using wall and bottom elements as connecting frames. The thickness of the connecting elements is 0,025 0,06 steps of installing the frames, and the ratio of the height of the cross-section of the frames to the thickness of the connecting elements is 15 30 (RF patent No. 2051204, M.cl. C25C 3/08, 1995).

This casing has insufficient rigidity, the stresses arising in it during operation from expansion of the lining lead to plastic deformations of the casing, which reduces its service life.

Closest to the proposed invention in technical essence is the cathode casing of an aluminum electrolyzer, including longitudinal and transverse walls and the bottom, frames along the longitudinal sides, stiffeners along the end sides and a flange sheet, and a horizontal stiffness belt located around the perimeter of the cathode casing above the ends of the frames and stiffening elements. The horizontal stiffening belt is box-shaped and is a support for the flange sheet. The stiffening element of one of the sides of the horizontal belt is the wall of the cathode casing. In the particular case of execution, the horizontal stiffening belt is made of metal strips, while the strips of the longitudinal and transverse sides are connected into a lock and welded together. The flange sheet is connected to the cathode casing by a collapsible connection (RF patent No. 2191225, M.cl. C25C 3/08, 2002).

The disadvantage of the cathode casing of the prototype is that thermal stresses arising during operation, especially during the start-up period, and stresses from the expansion of the lining as a result of its impregnation with salts due to insufficient stiffness of the cathode casing cause significant vertical deformations. Deformations lead to the rise of the middle part of the cathode casing, to the opening of interblock seams and the penetration of the melt into the basement of the lining. In addition, a continuous horizontal box-shaped stiffness belt located above the ends of the frames, one of the sides of which is the wall of the cathode casing, prevents the free passage of air to cool the walls of the cathode casing. As a result, heat dissipation is deteriorating and the walls of the cathode casing are overheating due to the lack of a protective skull and nastily. Consequently, the structural rigidity decreases and the electrolyser fails due to the breakthrough of the melt through the walls of the cathode casing. These disadvantages lead to a decrease in the service life of the cathode casing and the aluminum electrolyzer as a whole.

The objective of the invention is to increase the service life of the cell by increasing the structural strength of the cathode casing.

The technical result consists in reducing the vertical deformation of the cathode casing and achieving a uniform distribution of transverse loads between the frames to ensure uniform compression of the lining and improve ventilation and uniform cooling of the walls and bottom.

To solve the problem in the cathode casing, including the longitudinal and end walls and the bottom, frames, covering the walls and the bottom and installed with a step along the length of the casing, according to the invention, at a distance from the longitudinal walls of the cathode casing in the upper part of the frames installed longitudinal beams of box section rigidly attached to them by welding or bolting.

In a particular case, the invention can be characterized in that the longitudinal beams of the box section are installed at a distance of 20-300 mm from the longitudinal walls of the cathode casing.

The remote location of the box-section beam from the heated parts of the cathode casing allows maximum use of the mechanical properties of the material from which they are made.

Rigid fastening of box-section beams with each frame allows:

- significantly reduce the vertical deformation of the cathode casing, namely, to reduce the rise of the middle part of the cathode casing during the start-up period, and accordingly to minimize the likelihood of opening interblock seams and penetration of the melt into the basement of the lining;

- evenly distribute between the frames transverse loads created by the pressure of the lining on the longitudinal walls of the cathode casing, i.e. to ensure uniform compression of the lining along the entire length of the cathode casing and to exclude the occurrence of loads on individual frames, leading to their destruction;

- increase the service life of the cathode casing and lining.

The presence of a gap between the box-section beam and the wall of the cathode casing provides unhindered passage of air for cooling the walls, thereby contributing to improved heat transfer and the creation of a protective skull and nastily.

The gap between the box-section beam and the wall of the cathode casing, comprising 20-300 mm, is determined from the conditions for effective cooling of the longitudinal walls of the cathode casing and ventilation of the casing.

With a gap of less than 20 mm, air circulation between the wall of the cathode casing and the box-section beam deteriorates. The volume of air passing through the small gap is not sufficient for normal cooling of the walls, which leads to overheating of the longitudinal walls in the installation area of box-shaped beams and, accordingly, to a decrease in their bearing capacity, as well as the impossibility of forming a protective covering and skull.

A gap of more than 300 mm does not increase the cooling intensity of the longitudinal walls, and the overall dimensions and mass of the assembly and cathode casing increase.

The invention is illustrated by drawings, where figure 1 shows a half view of the cathode casing from the side, figure 2 is a transverse section of the cathode casing.

The cathode casing of the aluminum electrolyzer consists of longitudinal walls 1, bottom 2, frames 3, longitudinal beams of box-shaped section 4. To install longitudinal beams of box-shaped section 4, frames 3 are provided with supporting horizontal and vertical platforms 5 and 6.

Assembly of the cathode casing is as follows.

On the assembly site, frames 3 are installed with an appropriate step. Then, a shell consisting of longitudinal walls 1, end walls (not shown) and bottom 2 is inserted into the frames and welded to them. Next, the longitudinal beams of the box section 4 are installed.

The longitudinal beams of box section 4 are installed on the horizontal supporting platforms of the frames 5 and are pressed against the vertical supporting platforms 6. There should be no gap between the beams 4 and the supporting platforms 5 and 6. The gaps between the beam and the supporting platforms are eliminated by metal gaskets. Upon completion of the elimination of the gaps, the beams are rigidly fixed to the horizontal and vertical platforms of the frames by welding or bolting.

Thus, the installation of box-shaped longitudinal beams in the upper part of the frames at a distance from the wall of the cathode casing allows to increase the service life of the aluminum electrolyzer, as well as to intensify its work.

Currently, an experimental cathode casing is undergoing a test phase.

Claims (2)

1. The cathode casing of an aluminum electrolyzer, including longitudinal and end walls and the bottom, frames, covering the walls and the bottom and installed with a step along the length of the casing, characterized in that in the upper part of the frames at a distance from the longitudinal walls of the cathode casing installed longitudinal beams of box section, rigidly attached to them by welding or bolting. 2. The cathode casing according to claim 1, characterized in that the longitudinal beams of the box section are installed at a distance of 20-300 mm from the longitudinal walls of the cathode casing.

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