The leakage of the furnace door is one of the main pollution sources of the coke oven. In addition, the improper carbonization chamber of the furnace door will cause the waste gas in the carbonization chamber to escape under positive pressure, affecting the recovery of coke oven gas and chemical products. At the same time, the waste gas will deteriorate the operating environment and burn out the iron parts of the furnace, causing the coke oven body to be easily damaged and shortening the service life of the furnace body. At the end of coking, due to pressure fluctuation of gas collecting pipe and other reasons, air will leak into the carbonization chamber, causing serious damage to the graphite in the brick seam of the furnace wall, causing the furnace wall to leak each other, burning off part of the coke at the same time, increasing the ash content in the coke, reducing the quality and output of the coke. Therefore, the tightness of the furnace door is closely related to the prevention of smoke, fire and the deformation and failure of the furnace door frame and furnace column.

The cause of smoke from the furnace door

In daily coking production, the main causes of smoke from the furnace door are deformation or damage of the furnace door knife edge, deformation of the furnace frame, improper cleaning of the furnace door frame, inaccurate alignment of the furnace door or coke clamping when aligning the door, damage to the furnace door pressing equipment, etc.

1. The problems of furnace door

The self-sealing spring knife edge furnace door is adopted. The top tightening force of the knife edge to the furnace frame is generated by the spring. The edge can not only compensate the deformation difference between the furnace door body and the furnace door frame. In actual production, due to the poor working environment, high working temperature, large load and short compressible stroke of the spring, the compression amount of the spring is limited and cannot play the due rebound effect, the pressing force of the knife edge to the furnace frame is not enough, and the deformation of the furnace door body cannot be completely consistent with the deformation of the furnace door frame, resulting in poor sealing and gas leakage.

Since the web thickness of the original furnace door is 1.5mm, the web is thin, and the toughness and strength are poor, the butt joints at the four corners of the web are welded. Working at high temperature, the upper and lower horizontal heads of the knife edge and the web plate will creep, which will change the gap between the upper and lower horizontal heads of the knife edge and the four corners of the web plate and the door frame of the furnace. Over time, the four corners will crack and smoke frequently. At the same time, it can not overcome the damage to the knife edge caused by the door picking operation.

After the furnace door is removed from both ends of the carbonization chamber before coke pushing, a large amount of tar will adhere to the refractory brick surface of the furnace door and the knife edge groove. The tar in the knife edge groove of the furnace door and the corner of the furnace door is not easy to clean. If the furnace door is installed intact without frequent cleaning, the sealing effect cannot be guaranteed. During the coking process, a large amount of gas will leak out from the knife edge groove of the furnace door, seriously polluting the environment and waste energy.

2. Furnace door brick problem

In order to increase the coal loading in a single hole and thus increase the coke output in a single hole, the furnace door brick was reduced from 378mm to 278mm and the thickness was reduced by 100mm. In order to ensure the maturity of the furnace head coke, the furnace head gas orifice plate on the coke side was increased from 11.8mm and 12.5mm to 12.3mm and 12.5mm respectively. Although the orifice plate was increased, the furnace head temperature was reduced to 1200 ℃, which was about 30 ℃, although the amount of coal charged in a single hole is increased, due to the low temperature of the furnace head, the graphite on the surface of the furnace door brick and the bottom of the furnace wall 1 and 2 eyes increases, and the difficulty of cleaning also increases. Due to the low surface temperature of the furnace door, tar oozes from the web and bottom of the furnace door at the beginning of coking, and condensed water flows out in winter, which affects the clean surface of the furnace door. At the same time, after picking the door, due to the low coke temperature on the side surface of the machine coke, black smoke and fire came out, which not only blackened the frame of the furnace door, but also polluted the environment.

3. Door-to-door operation

One-time alignment should be accurate to prevent the tightness of the furnace door from being damaged due to improper operation. At the same time, the cleaning management should be strengthened. The coke residue, coke powder and other residues on the surface of the furnace door knife edge, furnace door frame and door lining brick should be carefully cleaned, especially the tar in the furnace door knife edge groove and furnace door corner should be cleaned to ensure the normal contact and self-sealing tightness of the furnace door knife edge and furnace door frame. Moreover, the coal should be filled, leveled and packed. It is strictly prohibited to cut corners on both sides of the machine coke, resulting in high furnace head temperature and damage to the furnace door.

4. Furnace door repair

The furnace door shall be maintained regularly to improve the quality of the door repair, and the smoke and damaged furnace door shall be repaired in time. The furnace door should be periodically cycle maintenance once, the cycle should be 3 months is appropriate, after the maintenance of the furnace door, all parts must be in good condition, pressure frame bolts, springs should be flexible, knife edge leveling with adjustability. At the same time, check the integrity of the lining brick of the furnace door. If the damage is serious, it will cause the local temperature of the furnace door to be too high, resulting in deformation, breaking the tightness of the furnace door, and causing the furnace head to collapse when picking the door, so it should be replaced in time.

The above is about the cause of the smoke of the coke oven door and the harm.