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Analysis of the causes of deformation of the 6m coke oven door frame and online replacement method

Analysis of the causes of deformation of the 6m coke oven door frame and online replacement method

The coke oven door frame is an important coke oven equipment. It not only supports the coke oven door, but also has a certain protective effect on the coke oven body to adapt to the stress changes caused by the thermal expansion of the masonry. When the protective pressure of the masonry is insufficient or cannot be adjusted, the masonry will suffer varying degrees of damage, cracks will appear, and the structural strength will be significantly reduced. In severe cases, the furnace head will collapse and the carbonization chamber wall will deform, affecting the normal production of the coke oven. Therefore, keeping the oven door frame intact is crucial to extending the service life of the coke oven.

coke oven equipment

1 Cause analysis and preventive measures for coke oven door frame deformation

In addition to mechanical forces, the coke oven door frame also bears thermal stress caused by temperature differences under hot working conditions. If the coke oven body expands abnormally, it will exert a large bending force on the coke oven door frame. The coke oven door frame is easily deformed under various forces, causing the coke oven door to smoke and fire, seriously affecting the normal production of the coke oven.

1.1 Cause analysis

Our factory has a total of two 50-hole 6m roof-mounted coke ovens. In August 2016, the door frame of the coke side oven caught fire, causing the oven door frame to be severely deformed. In November 2016, the deformed oven door frame was replaced hot online. The causes of deformation are analyzed as follows.

1) The hook bolts of the coke oven door frame are loose in many places, causing the coke oven door frame to be loosely sealed, causing a fire for a long time after coal is loaded and deforming the coke oven door frame.

2) The pressure in the gas collecting pipe is unstable, which can easily cause leakage in the carbonization chamber, coke oven door, and coke oven door frame. In severe cases, the coke oven door frame can catch fire and deform.

3) The coke oven door knife edge is not tightly sealed and the coke oven door and coke oven door frame are not cleaned cleanly, which makes it difficult to open the door. This may easily cause the coke oven door knife edge to catch fire, and long-term fire may deform the coke oven door frame.

4) Due to improper operation, turning on high-pressure ammonia water for a long time or using high-pressure ammonia water to eliminate smoke caused serious leakage in the oven body and deformation of the coke oven door frame.

5) The large temperature difference after rain in summer causes the coke oven door frame to deform.

6) The long-term aging of the asbestos rope pressed against the coke oven door frame will cause the coke oven door frame to be loosely sealed, causing a fire for a long time after coal is loaded and deforming the coke oven door frame.

1.2 Preventive measures

1) Regularly check and tighten the hook bolts to prevent the hook bolts from loosening due to mechanical force, etc., causing gaps in the coke oven door frame to compress the asbestos rope, resulting in smoke and fire.

2) Ensure the stability of the gas collecting pipe pressure and prevent the coke oven door frame from leaking due to fluctuations in the gas collecting pipe pressure.

3) If there is smoke and fire at the edge of the coke oven door, it should be blocked in time, and the coke oven door and door frame should be thoroughly cleaned. If there is smoke and fire on the coke oven door frame, it should be blocked with asbestos rope from the outside first. If there is no effect, it should be thoroughly dealt with inside the furnace.

4) Formulate regulations on the use of high-pressure ammonia water. It is strictly prohibited to turn on high-pressure ammonia water for a long time or use high-pressure ammonia water to eliminate smoke.

5) The coke oven door frame should be inspected after rain, and any smoking coke oven door frame should be dealt with promptly.

6) The area where the coke oven door frame presses the asbestos rope is normally sealed with graphite. However, when the gas collecting pipe pressure is unstable or the coke oven door leaks, the sealing graphite will be burned and the asbestos rope will fail. When a similar situation occurs, the asbestos rope should be replaced in the furnace.

7) Measure and maintain furnace iron parts in a timely manner according to regulations.

2How to replace the coke oven door frame online

It is more difficult to export waste gas on the coke side of a single gas header than on the machine side, and it is more likely to cause deformation of the coke oven door frame. Take the online replacement of the coke side coke oven door frame as an example. When replacing the coke oven door frame, the carbonization chamber is empty. Two coke traps and fake coke oven doors are used to dismantle and replace the coke oven door frame.

2.1 Material preparation

The equipment and spare parts materials are provided in Table 1.

Table 1 Equipment and spare parts material configuration list
Machinery Quantity/set (set) Spare parts materials number
50t crane 1 Coke side oven door frame/set 1
electric wrench 2 Coke side empty furnace door/piece 2
welder 2 Ceramic fiber felt/box 2
10t hand chain hoist 2 φ32mm asbestos rope/m 30
3t hand chain hoist 3 φ25mm asbestos rope/m 30
hand wrench 1 Positive hook head bolt/set 10
Oxygen, acetylene welding 1 Reverse hook head bolt/set 10
Lifting fixture 1 Focus side grinding plate/set 1
Fixed fixture 1 Grinding plate bolt/set 2
retaining wall ladder 1 Focal side gasket/set 1
crowbar 4 Clay brick/t 2
Clay fire clay/t 0.5

2.2 Preparation work

2.2.1 Determine the replacement time

According to the coke pushing production plan, the coke oven door frame number that needs to be replaced is delayed and pushed to the end position of the furnace. After the coke oven door frame number is pushed and replaced, the carbonization chamber immediately enters the maintenance time. Then the last furnace time before maintenance is the best starting point for replacing the coke oven door frame. The maintenance time can be guaranteed to be at least 1 hour, and another coke oven will be released after 1 hour. If the operation of a single oven is calculated as 10 minutes, the operation time after production is 100 minutes. It takes about 2.5 hours to replace the entire coke oven door frame, which will not affect the smooth production of the coke oven.

2.2.2 Preparation of coke oven door frame and false furnace door

After the spare parts of the coke oven door frame are prepared on site, use Φ32mm asbestos rope to bond one circle with 502 glue inside the outer frame, and use Φ26mm asbestos rope to bond 2 circles with 502 glue inside the inner frame. It must be ensured that there is no gap between the asbestos rope and the coke oven door frame. And use thin iron wire to tie and fix the asbestos ropes of the inner frame and the outer frame at intervals of 0.5m to prevent the asbestos ropes from falling off during transportation and replacement.

The two false coke oven doors are lined with standard clay bricks (two layers are enough) to prevent excessive lining bricks from adding load to the door system of the coke blocker. One of the false furnace doors is aligned offline with the spare coke oven door frame, and the ends of the upper and lower horizontal irons are hooked and welded with iron plates to prevent the false coke oven door from becoming disconnected from the coke oven door frame during transportation. The other false oven door lined with standard clay bricks is transported to the other side of the coke oven and lifted to the fixing frame of the oven door repair station. Before replacing the coke oven door frame, all hook bolts must be replaced to prevent the replacement time from being affected by poor removal of the hook bolts.

2.3 Replacement process and production organization

2.3.1 Disassemble the coke oven door frame online

Use the coke blocking machine on one side of the door frame of the new furnace to perform the coke guide operation of changing the number. When the coke pushing is completed, the coke guide grid is returned, use the ladder retaining wall to insulate, and quickly remove the grinding plate and gasket at the bottom of the coke side coke oven door frame. , and remove the ladder retaining wall. After finishing, the coke blocking machine will drive towards the corresponding coke oven door repair station. After reaching the position, the coke oven door on the vehicle will be hung to the fixed frame of the coke oven door repair station. Before coke is pushed into the carbonization chamber of the replacement number, another coke blocking machine removes the false coke oven door hanging from the fixed frame of another coke oven door repair station and drives to the direction of the carbonization chamber of the replacement number to wait. When the coke pushing in the carbonization chamber of the replacement number is completed and the coke blocking machine with the coke oven door drives away, the coke blocking machine carrying the fake coke oven door will align the fake coke oven door with the door frame of the carbonization chamber of the replacement number. After the horizontal iron is lowered, immediately use iron plates to weld the upper and lower horizontal iron hooks to ensure that the false coke oven door and the coke oven door frame become a whole and cannot fall off. After the welding is completed, align and hook the door to the furnace door of the replacement number, and remove the hook head bolt of the number. After the hook bolts are disassembled, the coke blocker will remove the replacement fake coke oven door and coke oven door frame as a whole, drive them to the corresponding coke oven door repair station, and use a crane to hoist them down as a whole. This coke blocker can perform the unloading operation of another coke oven. . It takes about 1 hour to disassemble the coke oven door frame.

2.3.2 Online installation of coke oven door frame

After the coke blocker hangs the replacement furnace door to the fixing frame of the coke oven door repair station, the crane lifts the fake coke oven door and the new coke oven door frame to the door removal device of the coke blocker. After completion, the crane drove to another coke oven door repair station to wait for the old oven door frame to be hoisted down. After the old coke oven door frame is disassembled and removed, immediately put the ladder insulation retaining wall into the carbonization chamber, and clean the protective plate, alignment pin slot, etc. After the cleaning is completed, the ladder insulation retaining wall is withdrawn, and the coke blocker that hangs the false coke oven door and the new coke oven door frame to align the replacement carbonization chamber. The alignment must be quick and accurate. If the time is too long, the asbestos rope on the new coke oven door frame will deteriorate and the sealing effect will be lost. The on-site commander observes the position of the alignment pin of the coke oven door frame and directs the coke arrester to quickly align. After alignment, install the hook bolt immediately. After installation, gas weld the fixed parts of the upper and lower horizontal iron hooks to be removed. Then use this coke blocking machine to take off the fake coke oven door and move it to the fixed frame of the corresponding furnace door repair station, and then remove the real coke oven door of this number. When the coke blocking machine takes off the fake coke oven door of this number and replaces the real furnace door, put the ladder insulation wall into the carbonization chamber, install the coke side coke oven door frame backing plate and grinding plate, and align the real coke oven door after the installation is completed. Then carry out the coal loading operation of this number. The installation time of the coke oven door frame is approximately 1.5 hours.

2.3.3 Furnace temperature control

The online replacement of the coke oven door frame takes about 2.5 hours. Since the carbonization chamber of the replacement number is in an empty furnace state, if the temperature is not properly controlled, the carbonization room will be too high or the temperature will drop too fast, which will affect the service life of the furnace wall tiles in the carbonization chamber. The operation time of online replacement of the coke oven door frame is about 40 minutes, and most of the operations have ladder insulation walls to reduce heat loss. The coke oven door remains closed for about 2 hours. By reducing the amount of gas in the heating replacement combustion chamber by 1/2, the temperature of the adjacent carbonization chamber can be controlled and the temperature of the replacement carbonization chamber will not be too high or too low. The horizontal temperature of the heating replacement combustion chamber is measured every hour, and special adjustments are made according to the temperature changes.

3 Conclusion

The coke oven door frame is an important part of the iron protective parts of the coke oven. If it is not properly sealed, it will cause environmental accidents such as smoke and fire. In severe cases, important iron protective equipment such as horizontal braces and steel columns will be burned, seriously affecting production. . Damage to the coke oven door frame can be reduced through equipment maintenance and operation management. The damaged oven door frame is replaced online without affecting the normal production of the coke oven, ensuring the smooth production of the coke oven.

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