Method for protecting electrolyzer voltage and protective system

Abstract

The present invention provides a method for protecting electrolyzer voltage and a protective system which includes a tank voltage detecting loop, a protective system control cell, a protective system output loop and a protective system network structure. The tank voltage detecting loop, an electrolysis shop is an ungrounded supply system, an ideality null point is that: when the electric tank appears other possible ground strap connection in running process, the null point moves to the earth point; a theory null point is in a series mid-point, two end of the electric tank has 750VDC ground voltage; when other ground null point exists, the ground voltage of electrolysis shop lead-in terminal is as high as 1500 VDC. The method and the system collect tank voltage and series electrical current of the electric tank for judging various technique state accurately, emitting alarm signal and protective action signal, and combining a rectify viscous liquid flow system and a rectify integrated automation system organically as a whole, realizing reducing series electrical current in default rapidly, series stopping current in necessary to minimize accident and ensuring personal and assets sureness which is convenient for recovery producing rapidly.

Description

technical field [0001] The invention belongs to the technical field of electrolytic cell voltage protection systems in electrolytic aluminum plants, and in particular relates to an electrolytic cell voltage protection method and a protection system. technical background [0002] At present, the known electrolytic aluminum plant uses alumina to generate aluminum and carbon dioxide after direct current electrolysis in the electrolytic cell; the electrolytic aluminum plant is composed of a rectifier, an electrolytic workshop, and other auxiliary workshops. Such as figure 1 The shown rectification station is a terminal substation, and the general voltage level is 110kV or 220kV. The rectifier station is equipped with a rectifier unit, including components such as rectifier transformer (2), saturated reactor (3), rectifier cabinet (4) and primary equipment such as power transformer; the rectifier unit operates in parallel, figure 1 Among them, the rectifier transformer adjusts ...

AI Technical Summary

Problems solved by technology

[0012] 4) Depolarization: When the current in the electrolytic cell is seriously biased, when the current passing through a group of anodes exceeds the current that the guide rod can withstand, depolarization occurs, and the depolarization of a group of anodes will transfer the current to other Passing over the anode of the anode will cause greater bias current on other anodes, and it is easy to form multiple sets of anode depolarization. When the remaining anodes of this electrolytic cell cannot withstand the full current, it will cause rapid and comprehensive anode shedding, and the electrolytic cell will depolarize. Explosion; the electrolytic cell and sick cell in the roasting period have the possibility of depolarization

[0013] 5) Affecting the safety of the power grid: When a major accident occurs in the electrolytic aluminum plant, the power load of up to 300,000-400,000 KW is instantly dumped to the power grid, which can easily cause grid fluctuation accidents

This protection cannot avoid accidents caused by continuous conduction of the control circuit caused by contact adhesion

[0021] 50V protection system: a 50V alarm output contact is set in the tank control box to block the anode lifting operation circuit. When the tank voltage reaches 50V, the anode lifting operation is blocked to prevent the anode from being raised too high when the tank voltage exceeds the set voltage The phenomenon of depolarization occurs; the 50V protection system does not use the series current to block the voltage judgment of the tank, and the set value of 50V is also the set value of the corresponding series current during normal operation. According to the series voltage U=series current I*series resistance R, when When the series current becomes small, even if the tank voltage does not reach the set value of 50V, pole separation may occur; when the 50V protection system fails, there are no follow-up measures, such as reducing the series current, or tripping the rectifier unit, series power failure, etc.

[0022] The inventor has found through experiments that the above two protections cannot protect the high voltage and depolarization accidents caused by the drop of the mirror surface of the aluminum liquid when the aluminum is tapped and the drain

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