SU1534099A1 - Apparatus for forecasting anode effects in aluminium electrolyzer - Google Patents

Abstract

The invention relates to automating the process of producing aluminum by electrolysis. The purpose of the invention is to increase the reliability of anodic effect prediction. Two known RC circuits with different time constants, the smaller of which is not more than 10 minutes, the subtractor, the second setting node of the settings, the second comparison node, and the alarm activation node, are additionally introduced into the known device containing the setting reference node and the comparison node. The inputs of the RC circuits are connected to the anode and cathode tires of the electrolyzer, and their outputs to the inputs of the subtractor. The output of the subtractor is connected to the first inputs of the comparison nodes, to the second inputs of which the outputs of the corresponding setting nodes are connected. The outputs of the comparison nodes are connected to the two inputs of the alarm activation node. As the anode effect approaches, due to differences in the time constant of the RC circuits, a signal is formed at the output of the subtractor. In comparison nodes, this signal, naturally changing before the anode effect, is extracted against the background of random oscillations. 2 Il.

Description

This invention relates to automating the process of producing aluminum by electrolysis.

The aim of the invention is to increase the reliability of the prediction of the anode effect.

Figure 1 is a block diagram of the device; figure 2 is an example of its implementation.

The device contains a subtractor 1, the first 2 and second 3 comparison nodes, the first 4 and second 5 settings nodes, the alarm activation node 6.

In the device when the process is stable and xa,

Characterized by insignificant instantaneous voltage fluctuations, on average not exceeding 3%, the elements of R1 and 01 are chosen so that the time constant of the chain R1C1 is 1 min, and the time constant of the chain R2C2 is 5 min. The subtractor is assembled on DA1 and DAZ microcircuits, the first and second comparison nodes are made on DA2 and DA4 microcircuits, respectively; the first and second settings task nodes are made on resistors R10 and R11, respectively;

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About About WITH

The device works as follows

The first node 4 of the settings sets the threshold for voltage change in front of a flash of dPa and 40-60 mV. The second node 5 of the task settings sets the threshold for possible reductions in the average voltage on the 41-n-electrolyzer cell - 10-20 mV.

Long before the onset of the anode effect at the outputs of the RC circuits, equal average voltage values are formed. From the output of the R1C1 circuit, the voltage goes to the first input of the subtractor, and from the output of the R2C2 circuit, to the inverter of the subtractor assembled on the DAZ chip. From the inverter output, the voltage of the same amplitude, but reverse polarity, is fed to the second input of the subtractor. Since the equalizer voltage is applied to the input of the subtractor, then there is no signal at the output. At the exits. the first and second comparison nodes (DA2 and DA4) signals are also absent. There are also no signals on the collectors of transistors VT1 and VT2, and the relays K1 and K2 are off. 20-30 minutes before the anode effect, the voltage on the electrolyzer begins to gradually increase. In this case, the capacitor C1 will have a higher voltage (than the capacitor C2.

At the output of the subtractor, a signal dUc is formed, equal to the voltage difference across the capacitors C1 and C2. When the JUH threshold difference is reached, the output of the DA4 chip generates a signal which is amplified by the transistor VT2, as a result of which relay K2 is activated and closes its contacts in the power supply circuit of relay K1. When the difference aUc of the threshold dUB is reached, a signal appears at the output of the DA2 chip, which, after amplification by transistor VT1, turns on relay K. Relay K1, turning on its contacts K1.1, shunts VT, and contacts K1.2 turns on signaling. Due to the supply of power to relay K1 to the min transistor VT1, slight random voltage fluctuations on the electrolyzer against the background of its systematic increase before the anode effect will not lead to signaling trips. After the anode e is quenched (the difference dUc becomes less than the threshold, the relay K2 is turned off, it opens its contacts in the power supply circuit of the relay K1. As a result, the signaling is turned off.

In the case of an unstable technology, when the instantaneous voltage fluctuations on the electrolyzers on average reach 15–20%, the device is implemented according to the same basic scheme (Fig. 2), with the exception of the elements R, R2, Cl, C2. In this case, these elements are selected so that the time constant of the R1C1 chain is about 10 minutes, and the time constant of the R2C2 chain is about 40 minutes. The threshold for changing the average voltage before the flash is 80-100 mV, the threshold for a possible decrease in the average voltage d1Tn 40-60 mV.

The use of the device makes it possible, through continuous monitoring, to improve the quality of the forecast, timely prevent a greater number of anode effects and thereby reduce electric power losses.

Claims (1)

Invention Formula A device for predicting anode effects on an aluminum electrolysis cell, comprising a comparison unit and a setting unit, connected to a comparison unit, characterized in that, in order to increase the reliability of the anodic effect prediction, it further comprises first and second HC circuits, the second setting node, the second comparison node, the subtractor and the signaling activation unit, the RC circuit inputs connected in parallel to the anode and cathode busbars of the electrolyzer, their outputs to the subtractor inputs, the output of the subtractor to the first inputs of comparing units, to second inputs of which are connected outputs of the respective nodes specifying settings comparing units outputs are connected to two inputs of a node signaling includant. Fig. / + R1 yuk Compiler A.Abrosimov Editor N.Gunko Tekhred L.Serdyukova Proofreader N.Korol Order 24 Circulation 528 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 YES IVri / HGVPG Ctult Rll3K FIG. 2 Subscription