A voltage protection method and protection system for an electrolytic cell

Abstract

An electrolytic cell voltage protection method and protection system, comprising a cell voltage detection circuit, a protection system control unit, a protection system outlet circuit, and a protection system network structure; the electrolytic cell voltage detection circuit is an ungrounded system, and the ideal zero point When other possible grounding occurs during the operation of the electrolytic cell, the zero point will move to the grounding point; the theoretical zero point is at the midpoint of the series, and the voltage to the ground at both ends of the electrolytic cell can reach 750VDC; when there are other grounding zero points, the electrolytic workshop enters the line The end-to-ground voltage can be as high as 1500VDC; the present invention accurately judges various process conditions by collecting the voltage and series current of the electrolyzer, sends out alarm signals and protection action signals, and organically integrates with the rectification station's current stabilization system and rectification station The automation system is integrated to realize the rapid reduction of series current in case of failure, and the series of power outages when necessary, so as to minimize accidents, ensure personal and property safety, and facilitate faster recovery of production.

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 tank voltage judgment, 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 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 blackouts, 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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