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Coke oven door structure and basic requirements

The machine side and coke side of the carbonization chamber are closed with coke oven doors. Coke pushing and coal loading operations can be carried out by lifting and hanging the coke oven doors. The tightness of the coke oven doors is crucial to preventing smoke, fire, and deformation of the door frames and furnace columns. , failure is closely related. Therefore, the coke oven door which does not belong to a coke oven protection device is actually a very important protection device for a coke oven. As the height of the carbonization chamber increases, improving the coke oven door has become an important issue.

 

1. The overall structure and basic requirements of the coke oven door

 

COKE OVEN DOOR

 

Modern coke ovens use self-sealing sealing edge oven doors whose basic requirements are simple structure, tight sealing, light operation, easy maintenance, and easy cleaning.

In order to improve the sealing performance, reforms are currently being implemented from two aspects: first, reducing the raw gas pressure on the inside of the coke oven sealing edge, such as air channel type coke oven door lining bricks; second, improving the sealing and adjustability of the coke oven door sealing edge, such as double sealing edge and percussion sealing edge.

In order to facilitate operation, efforts are now mainly made on the door bolts mechanism, such as spring door bolts, airbag door bolts, and self-weight coke oven doors. An effective way to make cleaning easier is to air-seal the coke oven door. Since the tar residue deposited near the door is greatly reduced and its texture is soft, it is easy to remove. This method also effectively improves the sealing degree between the sealing edge and the coke oven door frame.

 

2. Beat-type sealing edge

 

The sealing edge is made of flat steel. Fastened by bolts. When adjusting, loosen the nut and tap the fixed clip to make the sealing edge close to the coking door frame. In order to prevent the sealing edge from retreating under external impact, there are clamps with various structures. We recommend a sealing edge with a cam clamp – it is used as a clip with a cam that blocks the sealing edge, and the cam resists the sealing edge. When external force is applied to the sealing edge, the radius of the cam in contact with it will increase as the bolt rotates, thereby preventing the sealing edge from retreating. This type of sealing edge is easy to make, replace and adjust, is cheap, and can adapt to slightly deformed coke oven door frames, so it is widely used at home and abroad.

The thickness of the sealing edge generally does not exceed 2mm, the welding joint is required to be straight and the surrounding dimensions meet the requirements. Install an adjusting jackscrew on the solid length of the sealing edge bracket to adjust it so that it is tightly sealed with the coke oven door frame. Whether the coke oven door sealing edge is intact has a great relationship with whether the tightness of the coke oven door can be ensured. For this reason, when the door is taken off, the residual substances such as tar residue and coke powder on the sealing edge, coke oven door frame and coke oven door lining bricks must be cleaned immediately. Otherwise, the residue will accumulate thicker and thicker, and the coke oven door sealing edge will gradually lose its self-sealing function, causing smoke and fire.

Due to the frequent lifting and hanging of the coke oven door and its contact with the atmosphere, the temperature changes drastically, so the sealing edge and lining bricks are easily damaged. For this reason, coke ovens are equipped with oven door repair stations, and oven door repair work is carried out on a scheduled basis.

 

3. Spring door latch

 

Generally, the coke oven door is held tight by horizontal iron bolts. When removing and hanging the door, the bolt-tightening mechanism of the coke-pushing car and the coke-blocking car is used to tighten the horizontal iron bolts. The operation takes a long time and the force is difficult to control. The spring door latch uses spring pressure to hold the coke oven door tightly. The operation time is short, the force on the door is stable, and it can also simplify the mechanism of lifting and hanging the coke oven door.

The spring load varies depending on the height of the carbonization chamber. It is 2×104N for a carbonization chamber of about 2m and 5×104N for a carbonization chamber of about 4m. Newly built large coke ovens with a height of 6m in China all use spring oven doors. Since the spring door bolt cannot change the pressure of the sealing edge on the door frame, it is often combined with a beat-type sealing edge in order to have better adaptability to slight deformation of the door frame or local accumulation of oil residue. In addition, it can also be combined with a gas-sealed coke oven door to work better when the sealing edge and coke oven door frame are clean.

 

4. Gas sealed coke oven door

 

The recycled gas purified by the recycling workshop is sent into the gas chamber at the coke oven door through a pipeline, and then slowly flows away from the gap between the door iron trough and the coke oven door frame sealing surface, so that the gap between the sealing edge and the coke oven door frame sealing surface is, forming a bottom-up flowing gas sealing zone. The pressure of the clean gas in the zone is slightly higher than that of the nearby raw gas to prevent the tar-containing raw gas from approaching the sealing edge, which greatly reduces the cleaning workload and improves sealing. Effect. However, after the gas-sealed gas enters the carbonization chamber, it is discharged together with the waste gas, which increases the load of the gas recovery and purification system.

At present, the gas-sealed coke oven doors being used and tested at home and abroad have various structures, but they are generally similar. As the airflow used for gas sealing, in addition to coke oven gas, some are introduced into the exhaust gas after burning coal gas and air, and some are introduced from the burner fire channel exhaust gas, which can not only act as a gas seal but also increase the temperature of the burner.

In recent years, coke oven doors have been used as important equipment to control coke oven smoke and achieve environmental protection. In addition to the above measures, various countries have conducted a lot of research on the structure and materials of coke oven doors. For example, some factories are developing a flexible door, and a spring sealing ring is made of heat-resistant nickel-chromium alloy steel that is larger and insensitive to thermal deformation and is used to replace the fixed sealing edge; another example in Japan is that the bending of the oven door due to heat is the main cause of seal damage, so it uses the coke oven door with an air insulation layer between the door bodies and bricks to reduce the heat that transfers from the carbonization chamber to the coke oven door body and reduces the thermal deformation of the door.

Coke oven door

Coke oven door frame

 

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coke ovens
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