RU2631074C1 - Method for automatic stabilization of electrolyser anode body position for prodicing aluminium - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves regularly moving the anode body relative to the anode fixed on the anode frame upwards in automatic mode. At that current value of anode body position is measured and current value of anode body position is compared to required anode body process position value to determine the deviation from the required anode body process position value. Based on the obtained comparison, the actual position factor of the anode body is continuously calculated by dividing the deviation result by anode body movement rate and anode frame and summing the time of all anode body and anode frame movements to the obtained value. The need to move the anode body with process specified frequency is determined. When obtained value of anode body actual position is negative, anode body is moved to the anode body displacement setting or to the actual position of the anodebody, which is equal to zero.

EFFECT: increase efficiency of aluminium silicate automatic feeding systems, increase service life of gas bell, reduce frequency of anode effects and improve aluminium quality.

2 cl, 2 dwg, 2 tbl

Description

FIELD OF THE INVENTION

The invention relates to ferrous metallurgy, in particular to the automation of electrometallurgical processes for the production of aluminum.

State of the art

Control of the position of the anode casing of the electrolyzer has become especially important when introducing systems for the automatic supply of alumina (APG) to the electrolyzer. For the effective operation of the APG systems, its position relative to the cell of the electrolyzer should be within the specified limits. Since the APG system is rigidly fixed to the anode casing, its position relative to the cell shaft depends on the position of the anode casing of the cell. The position of the anode casing, in turn, depends on the operation of the main and auxiliary jacks. Using auxiliary jacks, the anode casing moves only upward relative to the anode mounted on the anode frame; using the main jacks, the anode casing moves together with the anode, ensuring the operation of the electrolyzer within the specified voltage limits. The operation of the mechanisms is controlled by the process control system, with an increase in voltage above the upper boundary, the anode frame moves down, with a decrease in voltage below the lower boundary, the anode frame moves up.

There is a method in which the movement of the anode casing is carried out as the gas collection bell approaches the surface of the electrolyte. The distance of the gas collection bell to the electrolyte should be within 10-12 cm ("Anodes of aluminum electrolysis cells", 2001, E. Yanko, p. 645).

The disadvantage of this method is: the lack of constant monitoring of the position of the anode casing relative to the cathode; the need for physical measurements to decide on the feasibility of moving; binding to the melt level increases the likelihood of erroneous decisions about the movement of the anode casing, because melt variations during the day can be 4 cm or more.

There is a method of using automatic devices that allow you to raise the anode casing once a day to a height of 2-3 cm and only if the distance from the bottom of the gas collection bell to the surface of the electrolyte is less than 12 cm (Aluminum Metallurgy, 1999, Yu.V Borisoglebsky, G.V. Galevsky, N.M. Kulagin, M.Ya. Mintsis, G.A. Sirazutdinov, p. 191, 192 and 223). ("Electrometallurgy of aluminum", 2001, M.Ya. Mintsis, P.V. Polyakov, G.A. Sirazutdinov, p. 217).

The disadvantage of this method is the lack of constant monitoring of the position of the anode casing relative to the cathode, necessary for the effective operation of the APG systems (Monitoring is carried out once a day). Raising the anode casing at a time of 2-3 cm adversely affects the management of the anode technology (proteins, shedding of the side surface of the anode).

The well-known "Method of controlling the position of the anode shirt (anode casing) of the electrolyzer to produce aluminum" (patent SU 618453, IPC C25C 3/20, published 05.08.1978), in which the movement of the anode casing (PAK) is carried out automatically with a frequency of 1-10 once a day by an amount corresponding to the combustion height of a part of the anode. The frequency of movement of the anode casing and the time of movement are selected depending on the design and operational parameters of the cells. For example, for electrolyzers with a top current lead, the average burning speed of the anode is Va = 17-20 mm / day, and the speed of movement of the anode casing is Vp = 26 mm / minute (0.43 mm / s). To compensate for the burnt part of the anode, the duration of one movement of the anode casing was chosen t = 8 sec, then P is the number of movements of the anode casing per day is determined: P = Va / (Vp * t) = 20 / (0.43 * 8) = 6. Therefore, the frequency of PAK CHPAK = 24/6 = 4 hours. This method involves calculating the frequency of the necessary movement of the anode shell according to the theoretical rate of combustion of the anode, the speed of movement of the anode casing and the duration of one movement, and enter this information into the automated control system for the position of the anode casing (PAK ) The method is also characterized in that it is periodically necessary to measure the position of the sole of the anode relative to the position of the anode casing and, if necessary, disconnect from automatic control.

The disadvantage of this method is the lack of control over the position of the anode casing relative to the cathode, which is necessary for the efficient operation of APG systems.

Closest to the claimed invention is a method of controlling the movement of the anode casing of an aluminum electrolyzer, providing for the automatic movement of the anode casing according to the electromechanical feedback sensors rigidly fixed to the fixed structural elements of the cell and actuated by a lever rigidly fixed to the anode casing as a movable element (RU Patent 2213164, IPC С25С 3/20, published September 27, 2003). The essence of the known method is to automatically maintain the anode casing in a given position.

The disadvantage of this method is: an increase in the cost of production of aluminum due to the cost of acquiring electromechanical sensors, wires, clamps, their installation and maintenance; the need to restore the given position of the anode shirt after performing other operations, for example, moving the anode shirt and the kinematic system of wires, levers, clamps; the inability to quickly change the set position of the anode casing according to the requirements of electrolysis technology.

Disclosure of invention

The objective of the patented invention is to increase the service life of the flue bell, reducing labor costs.

The technical result of the proposed method is to reduce the transition of iron impurities into the electrolyte, reducing the frequency of the anode effects by providing continuous automated control and timely movement of the anode casing, providing a predetermined position of the APG systems relative to the cathode.

The technical result of the invention is achieved in that in a method for automatically stabilizing the position of the anode casing relative to the cathode of an aluminum electrolyzer, including the periodic movement of the anode casing relative to the anode, mounted on the anode frame upward in automatic mode

a) measure the current value of the position of the anode casing and compare the current value of the position of the anode casing with the technology value of the position of the anode casing, determining the deviation from the required technology value of the position of the anode casing,

b) based on the comparison obtained, the coefficient of the actual position of the anode casing is constantly calculated, dividing the deviation result by the speed of movement of the anode casing and the anode frame and summing the time of all movements of the anode casing and the anode frame to the obtained value,

c) with the frequency set according to the technology, the need to move the anode casing is determined, when the negative value of the coefficient of the actual position of the anode casing is received, the anode casing is moved to the setpoint for moving the anode casing or until the coefficient of the actual position of the anode casing is equal to zero. The coefficient of the actual position of the anode casing can be calculated by the formula:

Z = (Y-X) / Vп + A + B, where

Z is the coefficient of the actual position of the anode casing, sec;

X - the required value of the position of the anode casing, mm;

Y is the measured current value of the position of the anode casing, mm;

VP - the speed of movement of the anode casing and the anode frame (mm / sec);

And - the time of movement of the anode frame, sec;

In - time the movement of the anode casing, sec.

Brief Description of the Drawings

In FIG. 1 shows the measured current value of the position of the anode casing relative to the flange sheet of the cathode.

In FIG. 2 shows a schedule of the method for 13 hours.

The implementation of the invention

In the inventive method for controlling the position of the anode casing, the required value (X) of the position of the anode casing 1 is set from the top of the gas collection bell (HSC) 2 to the flange sheet 3 of the cathode 4 (for example, “Target HSC-flange = 460 mm), then the current value is measured (Y) the position of the anode casing 1 from the top of the HSC 2 to the flange sheet 3 (for example, HSC-flange = 473 mm), the deviation of the measured current value of the position of the anode casing from the required value of the position of the anode casing (473-460 = 13 mm) is calculated . Knowing the speed of movement of the anode casing and the anode frame (Vп = 0.43 mm / s), the coefficient of the actual position of the anode casing (YX) / Vп (Position of the an.casing = 13 / 0.43 = 30.2 sec) is calculated in real time summing up to the obtained value the time of all movements of the anode casing (PAC) caused by both the operation of the main (moving the anode frame A) and auxiliary (moving the anode casing B) jacks, the upward movement is a positive value, the downward movement is a negative value. Then, at a frequency specified by the technology (for example, the frequency of movement of the anode casing = 3 hours), an analysis of the advisability of moving the anode casing is performed, if at this moment the coefficient of the actual position of the anode casing has a positive sign, then the anode casing is higher than the value required by the technology and the movement of the anode casing it is not carried out if the sign is negative, then the anode casing is lower than the position value of the anode casing specified by technology and the anode casing is moved to position the top of the anode casing of zero (X = Y), or by setting the anode casing movement (for example, the maximum setting PAA = 10 sec).

Consider an example of controlling the position of the anode casing of the electrolyzer.

Table 1 shows for example the parameters necessary to control the position of the anode casing.

According to table 1, the process control system calculates the deviation of the current position of the HSC flange from the required value for the position of the anode casing (13 mm), knowing the speed of movement of the jacks (the movement of the anode casing and the anode frame) calculates the time required to move the anode casing to the required technology position anode casing, and assigns it to the current position of the anode casing (30.2 sec) to further achieve the goals of the HSC flange.

Table 2 presents an example of the method for 13 hours.

Consider table 2. Due to the fact that the specified PAA frequency is 3 hours, therefore, in our case, the automatic process control system will determine the need to move the anode casing (PAA) at 3, 6, 9, and 12 hours (highlighted in color in column 1). The movement of the anode frame by the process control system is shown in column 2. The position coefficient of the anode frame is shown in column 3. The position coefficient of the anode casing is shown in column 4. The movement of the anode casing is shown in column 5.

The first changes in the position of the anode frame occurred at the third hour, namely, the anode frame moved down 30 seconds (Fig. 2 the dashed down arrow at 3 hours), therefore, the position coefficient of the anode casing became 30.2-30 = 0.2 sec (Fig. 2). In accordance with the PAK frequency of 3 h, the process control system determines the need for PAK, the position coefficient of the anode casing has a positive sign (0.2 sec), therefore, PAK is prohibited. At 5 hours, the process control system moves the anode frame down another 20 seconds (Fig. 2, the dashed arrow down at 5 hours), the position coefficient of the anode casing is set to “-19.8 sec." At 6 o’clock, the position coefficient of the anode casing has a negative value (-19.8 sec), the process control system produced PAA for 10 sec, (Fig. 2 6 h up arrow), the position coefficient of the anode casing changed by -9.8 sec (Fig. 2) . At 9 hours, the process control system produces PAK for 9.8 seconds until the position coefficient of the anode casing is equal to zero (Fig. 2, 9 hours, up arrow). At 11 hours, the process control system moves the anode frame up for 20 seconds (Fig. 2, the dashed arrow up at 11 hours), the position coefficient of the anode frame takes the value “-40 sec”. At 12 o'clock, the control system established a ban on PAK, as the coefficient of position of the anode casing has a positive value of "+20 sec."

It can be seen from the presented example how the automatic process control system in real time controls the position of the anode casing relative to the value of the position of the anode casing required by the technology.

The inventive method takes into account all the movements of the anode casing, both the movement of the anode casing together with the anode under the action of the main jacks, and the movement of the anode casing relative to the anode under the influence of auxiliary jacks, as well as the position of the anode casing relative to the cathode and maintains it at a predetermined level, which in turn increases the efficiency of the APG systems, the life of the flue bell, reduces the transition of iron impurities into the electrolyte, reduces the frequency of anode effects.

Claims (12)

1. A method for automatically controlling the position of the anode casing relative to the cathode of an aluminum electrolyzer, including the periodic movement of the anode casing relative to the anode, mounted on the anode frame up in automatic mode, characterized in that a) measure the current value of the position of the anode casing and compare the current value of the position of the anode casing with the technology value of the position of the anode casing, determining the deviation from the required technology value of the position of the anode casing, b) based on the comparison obtained, the coefficient of the actual position of the anode casing is constantly calculated by dividing the deviation result by the speed of movement of the anode casing and the anode frame and summing with the obtained time value all the movements of the anode casing and the anode frame, c) when the negative value of the coefficient of the actual position of the anode casing is received, the anode casing is moved to the setpoint for moving the anode casing or until the coefficient of the actual position of the anode casing is equal to zero. 2. The method according to p. 1, characterized in that the coefficient of the actual position of the anode casing is calculated by the formula: Z = (Y-X) / Vп + A + B, where Z is the coefficient of the actual position of the anode casing, sec; X - the required value of the position of the anode casing, mm; Y is the measured current value of the position of the anode casing, mm; VP - the speed of movement of the anode casing and the anode frame (mm / sec); And - the time of movement of the anode frame, sec; In - time of movement of the anode casing, sec.

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