Understanding of soft breakage for electrode at SAF Furnace

A large-scale production accident in the production of calcium carbide when the electrode is softly broken but can be avoided if preventive measures are in place. In production, when the electrode is softly broken, it will cause great danger and injury to equipment, production, and especially personal safety.

Table of Contents

1. The phenomenon of electrode soft-breaking

When the leakage of paste in the production causes soft-breaking, the ammeter on the operation interface of the central control room suddenly rises or the current drops instantly after a sudden rise. The voltage of the electrode to the furnace bottom drops to “0”. At the same time, the electrode tube on the fourth floor emits a large amount of black smoke or yellow smoke from the inside of the shield, and the temperature of the furnace gas outlet suddenly rises, and the pressure in the furnace increases suddenly. In severe cases, the electrode paste in the electrode tube will flow out, and the furnace gas will flow from the electrode tube. Spilled and exposed to oxygen will explode, causing injury and damage to personnel and equipment.

2. Reasons for the soft breakage of the electrode

The reasons for soft breakage of the electrode can be roughly divided into the following points:

The quality of the electrode paste is unqualified, the ash content is high, the volatile matter is too large, and the softening point is high.

When the ash content is high, the electrode is easy to delaminate, causing the local current to withstand weakly, so that the current pierces the electrode cylinder and causes leakage. If it is not found in time, the electrode will not be sintered easily, causing the electrode to become soft. After the electrode is pressed and discharged, the current is too large to pierce the electrode barrel; when the softening point is high, the electrode paste will soften too slowly, and the electrode will be soft.

Whether the particle size of the electrode paste is appropriate will also cause the electrode to leak and cause soft disconnection.

If the particle size of the electrode paste is too large or too small, the irregular addition will cause the shed paste or overhead, which will cause the electrode to stratify. After the electrode is pressed and discharged, the current will pierce the electrode cylinder, which will also cause the electrode paste to leak and cause soft disconnection.

The welding quality of the electrode barrel is unqualified.

When the welding quality of the electrode barrel is poor, add electrode paste, and the electrode paste will flow out from the weld after being heated and softened, causing continuous electric stab fire. In severe cases, the electrode barrel will puncture and break directly.

The firing speed of the electrode is lower than the pressure and release speed.

So that the electrode under pressure is not fired properly, and the current is too large to withstand the range of the electrode. The electrode cylinder is pierced to cause the liquid electrode paste that is not sintered to flow out to form a leaking paste, resulting in softness. Off. 5. When the water content of the raw material is too large, it will cause collapse, and the flame will burn the insulating device and the sealing device on the electrode, forming a continuous electric stab fire, piercing the electrode cylinder and flowing out of the liquid electrode paste, causing soft breakage. At the same time, when the flame emerges, the tar in the carbon material will be taken out and adsorbed on the contact element, and after the temperature is reduced, it will condense into a block, which will also form a thorn fire and puncture the electrode tube, causing the electrode tube to leak and softly break.

3. Treatment after the electrode is softly broken.

In normal production, it is found that the current suddenly rises rapidly or the current drops instantly after a sudden rise but does not rise again. At the same time, when the voltage of the electrode to the furnace bottom drops to “0”, it is necessary to decisively cut off the power and evacuate the operators. Afterwards, organize personnel to open the furnace door to observe the situation. When it is found that the paste is leaking, the electrode should be pressed into the furnace in time to make the broken end connected and then compact the charge to reduce the outflow of electrode paste, and lower the electrode to connect with the broken end and remove it. At the same time, find out the leakage of the electrode paste and deal with it. After inspection and repair, confirm that there is no leakage.

Adjust the electrode to manual control for low-load power transmission and baking. The electrode tip and the broken end are connected under firing, thus transferring to normal production. If the broken end cannot be connected to the electrode, the paste is too thin, and the inside of the cylinder is similar to a new shell with a bottom that can be welded. It is similar to the broken end of the electrode when the furnace is newly opened, and it is roasted at a low power load. At the same time, during firing, the pressure and release method was changed to manual and the 24KW heating element was turned on, and the other two-phase electrodes were used to adjust the firing in the way of three belts and one.

4. Measures to prevent soft breakage.

Strictly control and master the length of the electrode working end

Reasonably control the pressure release time, make the pressure release speed and the sintering speed compatible, observe the firing situation of the electrode when the material surface is processed after every 24 hours In order to better control the soft and hard conditions of the electrode (if the surface of the electrode is found to be off-white, dark but not red or reddish, it means that the electrode is baked well; if the surface of the electrode is red, it means that the electrode has been burned; if the surface is black It proves that the electrode is insufficiently baked. You can also use round steel to test the electrode. If it is very hard and can rebound, it means the electrode has been overburned.

If it is elastic, it means it is normal. If it is soft, it means the electrode is underburned.) If the electrode is black or yellow smoke is found It will be immediately judged that the electrode is too soft, and the heating element should be turned on for low-level firing and the pressure release time should be prolonged.

Strictly control the quality of electrode paste to ensure proper volatile matter, ash, and particle size.

Strictly control the welding quality of the electrode barrel (no loopholes for trachoma).

After the power is cut off, the load should not increase too fast. Observe the changes in the electrode quality. Increase the load appropriately according to the electrode baking quality. When the electrode quality is found to be soft, the load should be reduced in time (power failure), and the electrode pressure and discharge time should be strictly controlled (no more than The maximum pressure and release time of this gear) and pressure and release length (strictly control the electrode pressure and discharge overtime at 20mm).

Add electrode paste on time and according to the amount to maintain the specified height of the paste column.

If the operator finds that the paste column has not changed for a long time, organize the staff to smash the paste and smash the overhead paste column firmly. Safe production with good electrode quality.

Strictly control the moisture content of the raw materials and prevent them from being too large, which will burn the insulation.

Make the electrode insulation device and sealing device regularly to keep the electrode in good working condition.

Summary

In production, if the managers will control the production in accordance with the specified process indicators, illegal operations will be eliminated to avoid such accidents, so as to avoid personnel and equipment. damage. Therefore, taking preventive measures for electrode protection is an indispensable duty in production.