Aluminum electrolytic cell alumina continuous feeding intelligent shelling device and control method

Abstract

The present invention discloses an intelligent shelling device and control method for continuous feeding of alumina in an aluminum electrolytic cell, in order to solve the technical problems in the prior art that alumina is easily accumulated at the feeding port and the shelling hammer is easily stuck and corroded. The present invention comprises a continuous feeding mechanism, a shelling mechanism, and a control system, wherein the continuous feeding mechanism and the shelling mechanism are both controlled by the control system. The present invention provides a laser distance measuring mechanism to accurately control the shelling stroke, improves the existing shelling pneumatic pipeline structure, and improves the control accuracy of the shelling cylinder stroke; a cooling device is designed to ensure the stable operation of the cylinder stroke laser distance measuring device under high temperature environment; based on the continuous feeding of alumina, by improving the shelling method of the electrolytic cell, the alumina enters the electrolyte more evenly and the dissolution effect is better. The beneficial technical effects of the present invention are: accelerating the dissolution of the electrolyte, avoiding precipitation at the bottom of the cell, improving the current efficiency of the electrolytic cell, effectively extending the life of the shelling hammer, and reducing the intensity of manual labor.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum electrolysis, and in particular to an intelligent shelling device for continuous feeding of alumina in an aluminum electrolysis cell and a control method thereof. Background Art

[0002] Existing aluminum electrolytic cells use a fixed-volume centralized unloading system. The cell controller uses a method of under- and over-dosage control to unload materials at specified intervals, with each unloading amount being approximately 1.2-1.8 liters. Because alumina powder is unloaded into the cell in a short period of time (5-10 seconds), this causes a concentrated amount of room-temperature alumina to enter the electrolyte within a short period of time, dissolving and absorbing a large amount of heat. This lowers the electrolyte temperature near the unloading port, reducing the solubility of the alumina and causing precipitation to form at the bottom of the cell. Over time, this can lead to scarring at the bottom of the cell, increasing the horizontal current within the cell, affecting current efficiency and shortening the cell life. To address this issue, relevant technicians have designed a continuous unloading mechanism that continuously and evenly controls the unloading amount by controlling the spiral unloading speed.

[0003] The existing shelling method is to shell the alumina before unloading it, which ensures that the flame eye is open and the alumina can smoothly enter the electrolyte. Each time the shell is broken, the cylinder moves at full stroke. The shelling hammer head is easily worn and corroded by the shell surface and the electrolyte during long-term shelling operations, which eventually leads to the hammer head being unable to effectively shell. The hammer head life is generally 4-6 months. In addition, the shelling hammer head is deeply immersed in the electrolyte solution, and the hammer head is in contact with the electrolyte for a long time. The upper part of the hammer head frequently forms sticky bags, which seriously affects the smooth entry of alumina into the electrolyte, causing unstable production and operation of the electrolytic cell and a significant increase in electricity consumption per ton of aluminum. At the same time, workers need to deal with hammer head sticking bags on a regular basis and frequently open the cover plate. The upper part of the cell dissipates a large amount of heat, resulting in a large amount of unorganized smoke emissions, and the labor intensity of workers is very high.

[0004] The pneumatic pipeline of the shelling cylinder is connected to the air control cabinet next to the electrolytic cell. A large amount of compressed air remains in the pipeline, causing the solenoid valve in the air control cabinet to move when it receives the command, but the cylinder movement has a large lag, making it impossible to accurately control the cylinder stroke, and thus failing to achieve the purpose of intelligent and precise shelling. Summary of the Invention

[0005] The present invention provides an intelligent shelling device and control method for continuous feeding of alumina in an aluminum electrolytic cell, so as to solve the technical problems in the prior art that alumina is easily accumulated at the feeding port and the shelling hammer head is easily stuck and corroded.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] An intelligent shelling device for continuous feeding of alumina in an aluminum electrolytic cell is designed, comprising a continuous feeding mechanism, a shelling mechanism, and a control system, wherein both the continuous feeding mechanism and the shelling mechanism are controlled by the control system. The shelling mechanism comprises a shelling cylinder, a connecting rod, a shelling hammer, a distance measuring mechanism, and a distance measuring target. A shelling reversing solenoid valve is provided on the top of the shelling cylinder. The shelling reversing solenoid valve is connected to an air inlet pipe and an air outlet pipe to drive the shelling cylinder.

[0008] The bottom of the shell-breaking cylinder is connected to the connecting rod to drive the connecting rod to reciprocate up and down, the shell-breaking hammer head is connected to the bottom of the connecting rod, the distance measuring mechanism is connected to the shell-breaking cylinder, and the distance measuring target is connected to the connecting rod and is arranged corresponding to the distance measuring mechanism.

[0009] The existing shell-breaking pneumatic pipeline structure was modified, and the shell-breaking control solenoid valve originally located in the air control cabinet next to the electrolytic cell was moved to the top of the shell-breaking cylinder on the upper part of the cell and directly connected to the cylinder. The pneumatic pipeline between the shell-breaking cylinder and the shell-breaking control solenoid valve was shortened, avoiding the lag effect of compressed air retained in this part of the pipeline on the cylinder stroke control, and greatly improving the shell-breaking hammer head stroke control accuracy.

[0010] Furthermore, the distance measuring mechanism is a laser distance measuring module, which is fixed to the top of the shelling cylinder through a bracket. The shelling depth is monitored in real time by laser distance measurement, and the shelling action is adjusted in real time in conjunction with the continuous feeding mechanism.

[0011] Furthermore, a heat-insulating cooling cover is provided on the outside of the laser ranging module, an air inlet is provided on the top of the heat-insulating cooling cover, an air outlet is provided on the bottom, the air inlet is connected to a cooling pipe, and the cooling pipe is connected to a separate cooling fan.

[0012] Furthermore, a guide sleeve is provided on the outside of the connecting rod, the guide sleeve is fixed to the bottom of the shell-breaking cylinder, a guide groove is provided on the side of the guide sleeve, and the target is provided in the guide groove and can move up and down along the guide groove.

[0013] The second aspect of the present invention is to design an intelligent shelling control method for continuous feeding of alumina in an aluminum electrolysis cell, which includes the following two shelling methods:

[0014] (1) Shelling mode commanded by slot control machine: The shelling output signal of slot control machine is collected. When the signal is converted to high level, the shelling device is controlled to perform shelling action. The shelling action can be performed according to the full stroke of the cylinder or according to the set stroke distance;

[0015] (2) The shelling method is determined by the cumulative feeding amount: the feeding amount of the alumina continuous feeder corresponding to the shelling device is collected, and the cumulative alumina feeding amount of the feeder is calculated. When the real-time cumulative value is greater than or equal to the cumulative feeding amount setting value, the shelling device is controlled to perform the shelling action according to the set shelling depth, and the real-time cumulative value is reset to zero. The depth of the shelling hammer head entering the electrolyte is set to 0-200mm, and the cumulative feeding amount setting value is 0-1.8kg.

[0016] Furthermore, after each aluminum tapping operation of the aluminum electrolytic cell, the shelling depth setting is dynamically adjusted according to the changes in the aluminum tapping amount and aluminum level. After aluminum tapping, the shelling depth of the hammer head decreases by 0.5-2mm per hour.

[0017] Furthermore, when breaking the shell, the hammer head presses the electrolyte shell surface tightly. If the shell surface is broken within the set time, the real-time collected stroke value is greater than the stroke set value, the hammer head returns, and the normal shell breaking process is resumed; if the shell surface cannot be broken after the set time, an alarm prompts.

[0018] Furthermore, after the shelling is completed, if the real-time collected stroke value is greater than the set stroke, the actual control set value is modified, and the control stroke is set to (control set value - compensation amount) for the next shelling.

[0019] Furthermore, when the distance measuring mechanism is abnormal, the shelling mode determined by the cumulative feeding amount is automatically switched to the full-stroke shelling mode commanded by the slot control machine and an alarm is issued.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are:

[0021] The present invention can cover the discharge port of the electrolytic cell with a certain thickness of alumina. At this time, when the fluorine-containing hot flue gas discharged from the discharge port passes through the alumina layer above it, the alumina boils and fully contacts with the fluorine-containing hot flue gas. The alumina is heated and absorbs the fluoride therein to form dispersed, boiling, preheated, fluorine-loaded alumina, which can greatly improve the dissolution rate of the alumina after entering the electrolyte; by controlling the alumina discharge amount and the shelling depth in each shelling cycle, the alumina can be uniformly introduced into the electrolyte in an appropriate amount to avoid excessive alumina entering the electrolyte at one time and being unable to be completely dissolved; when returning after shelling, the hot electrolyte carried by the shelling hammer head automatically falls off as a plurality of small electrolyte blocks at 600-800°C, and the hot electrolyte small blocks are dispersed and fall into the alumina powder below, which can heat the alumina around them. In the next shelling cycle, the small electrolyte blocks are mixed with the alumina and enter the molten electrolyte. The small electrolyte blocks wrapped by the alumina are melted by the heat and work together with the molten electrolyte in the cell to accelerate the dissolution rate of the alumina. The above factors can effectively improve the dissolution effect of alumina, increase the uniformity of alumina dissolution, avoid the formation of sediment at the bottom of the tank, and improve the current efficiency of the electrolytic cell. At the same time, it can achieve precise control of the shell hammer stroke, which can effectively extend the life of the hammer, reduce consumption, and reduce the labor intensity of workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is one of the structural schematic diagrams of the intelligent shelling device for continuous feeding of alumina in aluminum electrolysis cells of the present invention.

[0023] Figure 2 This is the second structural schematic diagram of the intelligent shelling device for continuous feeding of alumina in aluminum electrolysis cell of the present invention.

[0024] Figure 3 This is one of the top schematic diagrams of the intelligent shelling device for continuous feeding of alumina in aluminum electrolysis cells of the present invention.

[0025] Figure 4 This is the second top schematic diagram of the intelligent shelling device for continuous feeding of alumina in aluminum electrolysis cells of the present invention.

[0026] Figure 5 This is a schematic diagram of the installation of the ranging target in the present invention.

[0027] In the figure, there are a shelling cylinder 1, a connecting rod 2, a distance measuring mechanism 3, a heat-insulating cooling cover 31, a distance measuring target 4, a shelling reversing solenoid valve 5, a guide sleeve 6, an air inlet pipeline 51, an air outlet pipeline 52, a cooling pipe 53, and a guide groove 7. DETAILED DESCRIPTION

[0028] The specific implementation modes of the present invention are described below with reference to the accompanying drawings and examples. However, the following examples are only used to illustrate the present invention in detail and are not intended to limit the scope of the present invention in any way.

[0029] Example 1: An intelligent shelling device for continuous feeding of alumina in an aluminum electrolysis cell, see Figure 1 , including a continuous feeding mechanism, a shelling mechanism, and a control system, wherein the continuous feeding mechanism and the shelling mechanism are both controlled by the control system. The continuous feeding mechanism is a vertically arranged spiral feeding mechanism with a discharge tray at the bottom, which can allow the alumina powder to enter the electrolytic cell slowly and evenly, changing the instantaneous concentrated feeding method of the existing constant volume feeder, which is beneficial to the dissolution of alumina powder. The continuous feeding mechanism and the shelling mechanism are arranged vertically side by side above the electrolytic cell. The electrolyte in the electrolytic cell will form a hard shell when exposed to the air, and the alumina will not be able to enter the electrolyte. The shell surface needs to be broken regularly with the shelling mechanism so that the alumina can enter the electrolyte smoothly.

[0030] The shelling mechanism includes a shelling cylinder 1, a connecting rod 2, a distance-measuring mechanism 3, and a distance-measuring target 4. A shelling reversing solenoid valve 5 is installed at the top of the shelling cylinder 1. This solenoid valve is connected to an air inlet 51 and an air outlet 52 to drive the shelling cylinder. The shelling reversing solenoid valve 5 is mounted on the top of the shelling cylinder 1 via a mounting plate. The distance-measuring mechanism 3 is a laser distance-measuring module, secured to the top and side of the shelling cylinder via a bracket. The connecting rod 2 is connected to the bottom of the shelling cylinder 1, driving the connecting rod 2 in reciprocating motion. A shelling hammer is located at the bottom of the connecting rod 2. The distance-measuring target is connected to the connecting rod and positioned in correspondence with the distance-measuring mechanism 3.

[0031] The existing shell-breaking pneumatic pipeline structure was modified, and the shell-breaking control solenoid valve originally located in the air control cabinet next to the electrolytic cell was moved to the top of the shell-breaking cylinder on the upper part of the cell and directly connected to the cylinder. The pneumatic pipeline between the shell-breaking cylinder and the shell-breaking control solenoid valve was shortened, avoiding the lag effect of compressed air retained in this part of the pipeline on the cylinder stroke control, and greatly improving the shell-breaking hammer head stroke control accuracy.

[0032] In this embodiment, a guide sleeve 6 is provided on the outside of the connecting rod 2, fixed to the bottom of the shelling cylinder. A guide groove 7 is provided on the side of the guide sleeve 6, and the target 4 is positioned within the guide groove 7 and can move up and down along the groove. A clamping block is provided at the movable end of the shelling cylinder, within which the top end of the connecting rod 2 is fixed, and the distance measuring target 4 is fixed to the surface of the clamping block. The installation of a guide sleeve during the stroke of the shelling cylinder in aluminum electrolytic cells and the attachment of the target to the connecting rod of the shelling cylinder, with the target operating within the guide slot of the guide sleeve, significantly improves the target's operational stability and stroke detection accuracy.

[0033] Example 2: As a further improvement of Example 1, see Figures 2 to 5Since the temperature at the top of the slot is relatively high, in order to prevent the laser ranging device from overheating, a heat-insulating cooling cover 31 is provided on the outside of the ranging mechanism 3. The top of the heat-insulating cooling cover 31 is provided with an air inlet, and the bottom is provided with an air outlet. The air inlet is connected to a cooling pipe 53, and the cooling pipe is connected to a cooling fan. The cooling fan is fixed on the top of the shelling cylinder 1.

[0034] An air cooling device is added, equipped with a cooling fan and air cooling pipes to centrally cool the laser ranging device above the tank. An insulating cooling cover is installed outside the laser ranging device. The cover is designed with an air inlet on the top and a measurement air outlet on the bottom. Cooling air is introduced into the insulating cooling cover through the air inlet and discharged through the exhaust hole at the bottom without affecting the measurement, thus achieving cooling of the laser ranging device.

[0035] Example 3: A method for controlling the continuous feeding of alumina in an aluminum electrolysis cell by intelligent shelling, including the following two shelling methods:

[0036] (1) Shelling mode commanded by slot control machine: The shelling output signal of slot control machine is collected. When the signal is converted to high level, the shelling device is controlled to perform shelling action. The shelling action can be performed according to the full stroke of the cylinder or according to the set stroke distance;

[0037] (2) The shelling method is determined by the cumulative feeding amount: the feeding amount of the alumina continuous feeder corresponding to the shelling device is collected, and the cumulative alumina feeding amount of the feeder is calculated. When the real-time cumulative value is greater than or equal to the cumulative feeding amount setting value, the shelling device is controlled to perform the shelling action, and the real-time cumulative value is reset to zero. The method for collecting the alumina feeding amount is as follows: the feeding motor of the feeder adopts frequency conversion control. The feeding amount is related to the motor speed. The corresponding relationship between the speed and the feeding amount is determined. When feeding, the motor speed corresponding to the frequency converter is collected, and the real-time feeding amount can be converted accordingly.

[0038] After each aluminum tapping operation in the aluminum electrolytic cell, the shelling depth setting is dynamically adjusted according to the changes in the aluminum tapping amount and aluminum level. After aluminum tapping, the shelling depth of the hammer head decreases by 0.5-2mm per hour, so that the depth of the shelling hammer head entering the electrolyte remains basically consistent to ensure the shelling effect.

[0039] When breaking the shell, the electrolyte crust blocks the hammer, causing the real-time collected stroke value to be less than the lower limit of the stroke setting. The cylinder continues to output and the hammer presses the electrolyte shell surface. If the shell surface is broken within the set time, the real-time collected stroke value is greater than the stroke setting value, the hammer returns, and the normal shell breaking process is resumed; if the shell surface cannot be broken after the set time, an alarm is triggered; repeat the above shell breaking process 1-2 times, and it still cannot be broken, an alarm prompts manual processing, and the processing is completed and the manual reset is performed.

[0040] Due to compressed air fluctuations and other reasons, the real-time stroke is greater than the upper limit of the stroke setting. After the shelling is completed, the real-time collected stroke value is greater than the set stroke, and the gap is large. The compensation amount is automatically calculated, the actual control setting value is modified, and the control stroke is set to (control setting value - compensation amount) to perform shelling.

[0041] When the laser rangefinder is abnormal, the shelling mode determined by the cumulative feeding amount is automatically switched to the full-stroke shelling mode commanded by the control system, and an alarm is issued.

[0042] In addition, as a further improvement, the above method utilizes a control system to observe and collect data on various process conditions of the electrolytic cell, thereby optimizing the corresponding relationship between the alumina feeding amount and the shelling action.

[0043] Based on the transformation of alumina constant-volume feeding to continuous feeding, the above method establishes a mathematical model for shelling and feeding through an intelligent control algorithm. The alumina feeding volume of a single feeder is statistically analyzed. When the cumulative feeding volume reaches the set value, intelligent shelling is performed. The shelling depth is set according to the working conditions of the electrolytic cell. When the shelling hammer reaches the set depth, it automatically returns. This method can control the amount of alumina entering the electrolyte during each shelling cycle, avoiding the drawbacks of the traditional centralized feeding method of constant-volume shelling, such as large accumulation of alumina at the feeding port and sinking to the bottom. After preheating, the alumina can be evenly introduced into the electrolyte in an appropriate amount, effectively improving the dissolution effect of alumina, increasing the uniformity of alumina dissolution, avoiding the formation of sediment at the bottom of the cell, and improving the current efficiency of the electrolytic cell. At the same time, precise shelling hammer stroke control is achieved, which can effectively extend the life of the hammer, reduce consumption, and reduce the labor intensity of workers. It effectively extends the life of the hammer and reduces the labor intensity of workers.

[0044] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, those skilled in the art will appreciate that, without departing from the spirit of the present invention, the specific parameters in the above embodiments may be modified to form multiple specific embodiments, which are all within the common variation range of the present invention and will not be described in detail here.

Claims

1. An intelligent shelling device for continuous feeding of alumina in an aluminum electrolytic cell, comprising a continuous feeding mechanism, a shelling mechanism, and a control system, wherein: The continuous feeding mechanism and the shelling mechanism are both controlled by a control system, which is characterized in that the continuous feeding mechanism is a vertically arranged spiral feeding mechanism with a discharge tray at the bottom, the shelling mechanism includes a shelling cylinder, a connecting rod, a shelling hammer, a distance measuring mechanism, and a distance measuring target, a shelling reversing solenoid valve is provided on the top of the shelling cylinder, and the shelling reversing solenoid valve is connected to an air inlet pipe and an air outlet pipe to drive the shelling cylinder; the bottom of the shelling cylinder is connected to the connecting rod to drive the connecting rod to reciprocate up and down, the shelling hammer is connected to the bottom of the connecting rod, the distance measuring mechanism is connected to the shelling cylinder, and the distance measuring target is connected to the connecting rod and is arranged corresponding to the distance measuring mechanism; The distance measuring mechanism is a laser distance measuring module, which is fixed to the top of the shelling cylinder by a bracket; a heat-insulating cooling cover is provided on the outside of the laser distance measuring module; an air inlet is provided on the top of the heat-insulating cooling cover, and an air outlet is provided on the bottom; the air inlet is connected to a cooling pipe, and the cooling pipe is connected to a cooling fan; The feeding amount of the aluminum oxide continuous feeder corresponding to the shelling device is collected, and the cumulative aluminum oxide feeding amount of the feeder is calculated. When the real-time cumulative value is greater than or equal to the cumulative feeding amount set value, the shelling device is controlled to perform shelling according to the set shelling depth.

2. The intelligent shelling device for continuous feeding of alumina in aluminum electrolysis cells according to claim 1, characterized in that: A guide sleeve is provided on the outside of the connecting rod and is fixed to the bottom of the shell-breaking cylinder. A guide groove is provided on the wall of the guide sleeve. The target is provided in the guide groove and can move flexibly up and down along the guide groove.

3. A method for controlling the continuous feeding and intelligent shelling of aluminum oxide in an aluminum electrolysis cell, using the intelligent shelling device for continuous feeding and intelligent shelling of aluminum oxide in an aluminum electrolysis cell according to any one of claims 1 to 2, characterized in that: There are two shelling methods: (1) Shelling mode commanded by slot control machine: The shelling output signal of slot control machine is collected. When the signal is converted to high level, the shelling device is controlled to perform shelling action. The shelling action can be performed according to the full stroke of the cylinder or according to the set stroke distance; (2) The shelling method is determined by the cumulative feeding amount: the feeding amount of the alumina continuous feeder corresponding to the shelling device is collected, and the cumulative alumina feeding amount of the feeder is calculated. When the real-time cumulative value is greater than or equal to the cumulative feeding amount setting value, the shelling device is controlled to perform the shelling action according to the set shelling depth, and the real-time cumulative value is reset to zero. The depth of the shelling hammer head entering the electrolyte is set to 0-200mm, and the cumulative feeding amount setting value is 0-1.8kg.

4. The method for controlling the continuous feeding and intelligent shelling of alumina in an aluminum electrolysis cell according to claim 3, characterized in that: After each aluminum tapping operation in the aluminum electrolytic cell, the shelling depth setting is dynamically adjusted according to the changes in the aluminum tapping amount and aluminum level. After aluminum tapping, the shelling depth of the hammer head decreases by 0.5-2mm per hour.

5. The method for controlling the continuous feeding and intelligent shelling of alumina in an aluminum electrolysis cell according to claim 3, characterized in that: When breaking the shell, the hammer head presses the electrolyte shell surface tightly. If the shell surface is broken within the set time, the real-time collected stroke value is greater than the stroke set value, the hammer head returns, and the normal shell breaking process is resumed; if the shell surface cannot be broken within the set time, an alarm prompts.

6. The method for controlling the continuous feeding and intelligent shelling of alumina in an aluminum electrolysis cell according to claim 3, characterized in that: After shelling is completed, if the real-time collected stroke value is greater than the set stroke, the actual control set value will be automatically modified, and the control stroke will be set to (control set value - compensation amount) for the next shelling.

7. The method for controlling the continuous feeding and intelligent shelling of alumina in an aluminum electrolysis cell according to claim 3, characterized in that: When the distance measuring mechanism is abnormal, the shelling mode determined by the cumulative feeding amount is automatically switched to the full-stroke shelling mode commanded by the slot control machine and an alarm is issued.

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