Process for online power cut out of an aluminum reduction cell

Abstract

A process for online cut out of an aluminum reduction cell (pot) including the steps of leveling of the side beams of the reduction cell to around 150 mm; punching holes on both sides of the pot to ensure that the bath does not get overflow and ensure the dipping of the anodes through these punch holes; blowing air thoroughly all around the insulated shorted joints of all the risers to clean the joints from dust and large chunks of bath; applying lubricating oil to the shorted joint bolts to conform proper movement of nuts; breaking the side crust of all the four corner anodes; tapping the bath with at least one ladle; lowering the anodes such that there is no liquid overflow over the deck plate onto the catwalk; lowering of the beam by around 70 mm to 100 mm until the voltage falls below around 1.0 V-1.5 V at around 320 kA; loosening all riser bolts of the shorted joint of all the five risers using a pneumatic wrench after confirming that the anodes are dipped into the metal; removing insulated insert plates from the shorted anode riser joints and retightening all the five riser bolts using a pneumatic wrench and then taking the pot offline.

Description

BACKGROUND[0001]1. Field of the Invention[0002]The present invention relates generally to a process for an online power cut out of aluminum reduction cell and more particularly a process for isolating (cut off) a pot (aluminum reduction cell) online during continuous production without affecting or influencing other cells connected in series.[0003]2. Description of the Prior Art[0004]Metal aluminum is produced industrially by igneous electrolysis, i.e. by means of electrolysis of alumina in solution in a molten cryolite bath, referred to as an electrolyte bath according to the well-known GAMI technology. The electrolyte bath is contained in pots, referred to as “electrolytic pots”, having a steel shell which is lined internally with refractory and / or insulating materials with a cathode assembly located at the base of the pot. Anodes made of carbonaceous materials are partially immersed in the electrolyte bath. The assembly formed by an electrolytic pot, its anode(s) and the electrol...

AI Technical Summary

Benefits of technology

The present invention provides a new procedure for the continuous production of aluminum without production losses. The procedure includes steps to cut off a pot online, without reducing the line amperage to 0 KA. The procedure includes leveling of the side beams of the reduction cell, punching holes on both sides of the pot, blowing air thoroughly all around the insulated shorted joints of all the risers, applying lubricating oil to the shorted joint bolts, breaking the side crust of all the four corner anodes, tapping with at least one ladle of the bath, lowering of the anodes, leveling of the beams, lowering of beam by around 70 mm to 100 mm until the voltage falls below around 1.0 V-1.5 V at around 320 kA, loosening all the riser bolts of the shorted joint of all the five risers using pneumatic wrench after confirming that the anodes are dipped into the metal, and then taking the pot offline. The new procedure increases production, stabilizes operating pots, and eliminates frequent power outages.

Problems solved by technology

The disadvantages of the prior art methods of pot cut off can be summarized as follows:1. Intermittent load throw off, thus unnecessary inducement of stresses in turbine & related equipment.

2. Boiler tube leakage—due to sudden change in the stresses.

Blackouts caused by the above problems.

Apart from the many disadvantages linked with pot room operation such as normal anode effect, increase in its duration happens because of outages.

Of course one of the main disadvantages is simply the loss in production.

According to the factors listed above, the main problems with cutting power to pots are:1) Disturbances to the running operating pots.2) Impact on the power plant operation as well as on its equipment.3) Production losses due to decrease in line amperage during power on of pots.

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