Research on Safety Production of Aluminum Electrolysis Series

I. Introduction

Aluminum production is the electrolysis of a continuous production, a series arrangement of electrolytic aluminum production cell determines the operating mode of the cell production needs to run at a high temperature, strong current production needs endless supply of the electrolytic cell to maintain the electrolysis The energy required for tank production. Once an electrolytic cell is put into production, it indicates that it is continuously running and running. Once it stops running, it will bring huge economic losses to the tank. In particular, the current large-scale production of electrolytic aluminum production enterprises has achieved intensive automation control and large-scale mechanized control, which has improved economic efficiency and reduced production costs. However, its safety production has increased the risk accordingly, because it is now large. In electrolyzers, the cost per unit of electrolytic cell has exceeded 3 million yuan, and the cost of electrolytic aluminum series with an annual output of more than 200,000 tons has exceeded several billion yuan. Once the series is discontinued, the economic losses caused to the company and the country cannot be reduced. Estimate.

On July 1, 2006, the entire Central China Power Grid was blacked out. The electrolysis series that was just put into operation by an aluminum company in western Henan caused a devastating blow in the blackout accident. In December 2007, an aluminum company in Qinghai exploded due to the short circuit of the electrolytic cell. The series of power outages lasted for six hours, and the direct economic losses exceeded 300 million. The painful lessons of the series caused the entire aluminum industry to sound the alarm of safe production. On May 12, 2008, the Sichuan Wenchuan earthquake caused a devastating blow to the Sichuan Aba Aluminum Plant. Human beings seem helpless in the face of natural disasters, but we should be able to prevent any accidents other than this. Only by taking various preventive measures can we ensure the safe operation of electrolytic aluminum production.

Second, the characteristics of aluminum electrolysis production and operation

(1) Characteristics of aluminum electrolysis production process

Aluminum industry production, mainly using cryolite-alumina molten salt electrolysis, the main equipment is electrolytic cell. The simple principle of electrolysis, the electrolytic cell into a powerful direct current, an electrochemical reaction occurs at the anode and cathode, the electrolysis products, anode and carbon dioxide to produce carbon monoxide gas generated in the molten aluminum cathode surface. In the structure of the electrolytic cell, the main structure connecting the anode and the cathode is an aluminum bus bar and a carbon body, and the aluminum bus bar is configured as a main conductor of the electrolysis cell. The electric energy required for electrolytic cell production comes from power generation or online supply, and strong direct current brings potential safety risks to production.

(2) Characteristics of electrolytic cell installation

All aluminum cells are installed in series, and all the cells are connected in series to form a whole circuit. This feature of the cell also poses a safety hazard to safety production. An electrolytic cell must ensure stable and safe operation, avoiding the occurrence of leakage accidents, causing the interruption of the current circuit and affecting the safe operation of the entire series of production.

Third, factors affecting the safety production of aluminum electrolysis series

(1) Series power supply

Aluminum electrolysis production is a high-energy production. The main power source is electric energy. An electrolysis series with an annual output of 200,000 tons consumes hundreds of thousands of kWh of electricity per hour. The supply of these electricity is mainly used in the series. The energy input of the electrolysis tank is used to maintain the energy balance of the electrolysis cell. The electrolysis cell is operated at high temperature. Once the supply of electric energy is lost, the cell temperature of the electrolyzer will decrease rapidly, especially the current production of large electrolysis cells. The electrolysis cell has a faster heat dissipation rate. Short-term power outages may have little impact on production, but the direct result of long-term power outages is that the electrolyte in the tank cools and settles, the aluminum liquid rises on the electrolyte surface, and the settled electrolyte deposits in the lower layer of aluminum liquid to block the current path, causing the electrolyzer The interruption of current, when the current supply is restored, brings great difficulties to the recovery of production, and even causes the series to stop production, which brings huge economic losses.

The main factors affecting the series power supply are sudden shutdown of the generator set or sudden interruption of power supply on the network. On the other hand, the fault of the rectifier transformer power supply equipment suddenly causes the transformer to trip, and then there is a fault such as transformer tripping due to weak lightning protection measures during the summer thunderstorm season.

(2) Series supply air

In addition to the supply of electricity, the normal production of large-scale electrolyzers requires the supply of wind power. This is because the equipment that completes the shell-cutting operation in the normal production of the electrolyzer is a pneumatic device that leaves the wind source and its equipment. Unable to operate and operate, the raw material of the electrolytic cell-alumina cannot be added to the electrolytic cell. If the series supply air is stopped for a long time, the electrolytic cell will not be replenished for a long time, and the electrolytic cell effect will occur in large quantities, not only to supply power to the series. The impact is huge, and the safety of the electrolytic cell itself is also a great threat. The occurrence of a large number of effects causes the cell temperature of the electrolytic cell to rise rapidly, causing a series of power outages caused by a leaking furnace or other accident.

(3) Series feeding

At present, the feeding mode of the large-scale electrolytic cell is the ultra-dense phase conveying mode, and the electrolytic cell realizes the automatic shelling and blanking, which greatly reduces the individual labor of the employees. However, in the event of a conveying failure, the series stops feeding for a long time, and the electrolytic tank cannot be replenished in time, which also causes a large number of effects of the electrolytic cell, thereby threatening the safety of the electrolytic cell itself and the safety of the series.

(4) The computer is out of control

At present, all the large-scale electrolyzers have realized automatic control, and the use of the automatic control system has also reduced the huge workload of the employees. However, once the control system is out of control, all the actions of the electrolysis cell are stopped, and the induced effect is more difficult to extinguish. The consequences are more serious than the consequences of series feeding and air supply.

(5) Other accidents lead to series safety

The above four are series of accidents caused by series accidents, but there are other accidents in normal production that cause series of accidents. In recent years, there have been many series of power outages due to other operational accidents.

1. Leakage accident

The leakage accident of the electrolytic cell is the most frequent type of power failure caused by the current electrolytic cell, because the series connection of the electrolytic cell determines the operation mode of the electrolytic cell, and the circuit busbar is surrounded by the electrolytic cell, and once the electrolytic cell leaks, The first thing to protect is the safety of the circuit bus. Once the circuit bus is broken, it will cause the series of electrolytic cells to be powered off. Therefore, the series will be powered off, and the power can only be energized after the circuit bus is repaired.

2, short circuit opening shot accident

The short circuit of the electrolytic cell is an important part of the electrolytic cell. The short circuit port of the large electrolytic cell is mostly between the two electrolytic cells (except the terminal electrolytic cell). The insulation of the short circuit is insulated by the phenolic resin insulating plate. In the production of the tank, the anode shell replacement operation will bake the shell block, which will cause the insulation board to lose the insulation effect; in addition, due to the magnetic force of the column bus bar, the iron tool will be sucked up to cause the short circuit port to be short-circuited; Short-term aging of the insulating sleeve in the short-circuit port causes short-circuit of the short-circuit port without insulation. These potential short-circuits may not cause a big accident temporarily, but the consequences are unimaginable once the effect of the electrolytic cell or other accidents causes the short-circuit port to shoot. Caused a series of power outages.

3, the difficult effect accident

The occurrence of the unsuccessful effect is related to the series of supply of wind, and also related to the composition of the electrolyte. If the effect of extinguishing is not taken after the occurrence of the unrelenting effect, the consequences are unimaginable, and the large amount of heat generated by the effect will cause The tank shell is deformed or even melted, and a large amount of high-temperature liquid flows out of the melting circuit bus line, causing the circuit to be interrupted and forced to power down.

4, bus lift operation accident

During the lifting process of the electrolytic cell busbar, the temporary clamp is loosened due to sudden wind break or other reasons, causing the guide rod to slip or fire, or the overall driving of the guide rod causes a hard-to-extinguish effect, resulting in a series of power failures.

5, pressure tank accident

Due to the quenching effect or sudden failure of the hoist caused by the anode overall groove, the electrolyte liquid or aluminum liquid in the tank is squeezed out of the tank, and the series bus is caused to be burned or broken.

6, computer control button adhesion accident

The electrolyzer tank control machine is not repaired for a long time, and the button sticking causes the electrolyzer hoist to continuously rise or fall, causing a series of power outages caused by an anode shooting accident or a pressure tank accident.

Fourth, preventive measures

The snowstorm in December 2007 caused billions of dollars in economic losses to the Guizhou Aluminum Plant. The Sichuan earthquake on May 12, 2208 caused a devastating blow to the Aba Aluminum Plant. Humans appeared so pale in the face of natural disasters. . However, in addition to natural disasters, there are potential human factors behind any accident. Accidents often have a close relationship with management. To do this, preventive measures are the primary measures to prevent series accidents.

(1) Improve the accident plan

The accident plan is a prerequisite for the prevention of accidents. All factors affecting the safety of electrolytic aluminum production must be taken seriously, accidents are expected, and plans for improvement, pre-planning, or accident simulation operations and drills, operations and drills are carried out. The accident plan was discovered and improved, and preventive work was done in a practical manner to minimize the occurrence of accidents or accidents.

(2) Adhere to the supervision of system management and enforcement

The accident plan is only a plan. How to prevent the precautions and accidents, the necessary system management is necessary, and this is also an important measure for people's management. The implementation of preventive measures for accidents must be strict, and there must be no sloppyness. Any unit with poor execution ability is a unit with frequent accidents. Even the best plan does not have a good execution force equal to a piece of paper.

(3) Equipment inspection and maintenance must be done

Comprehensive maintenance and maintenance of equipment to ensure the safe and normal operation of equipment is a necessary condition for accident prevention and a necessary condition for improving economic efficiency and reducing accidents. Therefore, daily equipment inspection and maintenance management is particularly important.

Fourth, the conclusion

Series accidents are the biggest loss for electrolytic aluminum enterprises. The damage caused by a serious series of accidents to a company may be devastating. Therefore, precautions and preventive measures for accidents are an important prerequisite for ensuring the safe production of electrolytic aluminum.

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