In coke ovens that have been produced for many years, cracks, melting, deformation and even collapse of the regenerator and the main wall are caused by factors such as temperature. The checker bricks are easy to be blocked, and even deform and melt at high temperatures. When these defects seriously damage the heating system, the regenerator should be renovated.
Renovating the regenerator will cause the increase and expansion of the single and main wall cracks due to cold air entering the room, so this is generally not done. In the case of forced renovation, the internal masonry should also be protected from damage, corresponding insulation measures should be taken, continuous operation should be maintained to shorten the renovation time, and coke oven gas should be used to heat the furnace when conditions permit .
1. Replacement of checker bricks in the regenerator
(1) Melting and creep of checker bricks
Judging from the creep checker bricks taken out of the coke oven regenerator, the damaged shape and volume expansion, the internal structure of the material is loose, the holes are blocked, and the severely damaged parts are concentrated in the upper part of the gas regenerator, generally no more than three layers of bricks, the upper layer The most serious, and the upper part of each piece creeps more than the lower part. A factory samples and inspects clogged checker bricks.
(2) Replacement measures
Prepare all necessary tools and refractory materials before construction, and install low-voltage lamps for temporary use. Use a special iron plate to cover the upper surface of the waste gas pan connected to the refurbished regenerator to prevent the scrapped bricks from jamming the exchange equipment.
Production organization. During the repair period, there will be one buffer furnace number adjacent to each other, and the furnace will not be drawn during the repair period. The actual coking time of the repaired furnace number depends on the length of the repair time, the maturity of the coke cake and the temperature of the combustion chamber. The coking time of the buffer furnace number is set at 36h, the second buffer furnace number is set at 30h, and the coking time difference between adjacent furnace numbers is more than 4h. In terms of furnace temperature management, the standard temperature for repairing furnace numbers and buffer furnace numbers should be lowered accordingly. If it is blast furnace gas heating, it needs to be temporarily stopped. To ensure that the furnace body in the combustion chamber area is not damaged, the adjacent units and coke sides should be used at the same time. Less, the coke oven gas is heated intermittently, and the temperature should not exceed 1200°C. After the checker bricks are replaced, the coke oven gas is used to heat up for 2 to 3 hours when the temperature is raised, and then converted to blast furnace gas for heating (if there is no coke oven gas, the supply of blast furnace gas will be temporarily suspended during the maintenance period). The replacement measures are as follows.
①Consult the furnace release plan before construction, select the furnace number with the coking time in the middle, and remove the pressure measuring hole with a crowbar. For the regenerator with a heat shield and a small furnace column with a single (main) wall, before removing the masonry, The small furnace column, beam and heat shield should be removed first. And close the corresponding blast furnace gas valve and the blast furnace gas valve on the adjacent unit and coke side, disconnect the mound rod from the exhaust gas stroke, and adjust the opening of the exhaust plate flap.
②Pick off the wall tiles from the horseshoe cover, take out part of the checker bricks, continue to remove the wall to the bottom, hang the windshield above, insert the iron plate in the gap between the two checker bricks under the replaced checker bricks, and use the ramp Blocked with thermal insulation cloth.
③Use a single hook to remove the checkered bricks. If the checker bricks are tightly packed with the single and main walls or the checker bricks are fused together, the furnace head can be smashed with a crowbar and then pulled out, and the deep ones can be smashed and taken out with a live joint shovel. As the checker bricks are pulled out, the iron plate gradually moves to the depths of the regenerator.
④ There is one layer of checker bricks on the burner fire channel, and wooden boards are laid on the top for easy access and removal. They are formed into a ladder shape, each layer is 4 to 5 pieces, and all the upper three layers are required to be replaced.
⑤Before installing checker bricks, clear out the broken pieces in the holes. Gunning and repairing the cracks of the single and main walls, and using a multi-section blower to blow the checker bricks until the blower inspection is unblocked. When blowing, pay attention to the blowing hole not to face the single (or main) wall, but to move slowly and repeatedly from the outside to the inside and from the inside to the outside of the hole. Strip off the bottom of the burner and fire, and clean the dirt in the grates and small flues.
⑥ Put the slideway into the heat storage room and push the checker bricks in. It is required to be close to each other, not to be skewed or toppled, and to align the holes up and down, and not to lean against the furnace wall on both sides.
⑦After installation, first build the inner wall and seal the wall with grout on the outer surface, then build the outer seal wall. After the temperature of the regenerator is normal, joint again, install the protective cover, restore the small furnace column spring tonnage, etc.
(3) Safety precautions for checker brick replacement
① When stopping and replacing the heating of the furnace number in the regenerator of the furnace number, it should be determined whether the furnace number of the plus or minus cock is closed and the furnace number is correct.
② During the construction period, the fans in the corridor of the regenerator and the temperature measurement platform of the storage roof should be kept running to maintain ventilation.
③ In the process of peeling and sealing the wall, prevent scalding.
④ During the construction period, a dedicated person should be assigned to wear a carbon monoxide alarm to monitor the gas concentration on site.
⑤When working on the storage roof operating platform, prevent the first-class parts from being bumped. After taking out the checker bricks, they should be stacked to prevent them from falling.
⑥ It is strictly forbidden for idlers to walk in the corridor of the regenerator near the construction to prevent injuries from falling objects.
(4) Measures to prevent clogging of checker bricks In order to prevent checker bricks of coke oven regenerators heated by blast furnace gas from clogging, the following preventive measures should be adopted.
①Purge the gas regenerator with compressed air regularly.
② The dust content of blast furnace gas should be controlled below 15mg/m3.
③The physical and chemical indexes of clay checker bricks for coke ovens should establish standards. The content of Al2O3 and low melting point substances should be appropriately reduced with reference to foreign standards.
④ Semi-silica checker bricks should be used for the top 3~5 floors of the regenerator of the newly built coke oven.
⑤The checker bricks that have been found to be blocked should be replaced immediately and replaced with semi-silica.
2. Repair of the single (main) wall of the regenerator
For regenerators that have been used for many years, as long as they are carefully taken care of, there are generally no or fewer cracks on the single and main walls. Only the single and main walls of the regenerator where the sealing bricks are often opened are prone to cracks. Generally speaking, the number and width of the cracks are that the single wall is larger than the main wall, and the ends are larger than the inside. When the main wall and the main wall need to be repaired due to serious gas leakage, usually the end part of the checker bricks are removed first until all the gaps in the wall are exposed, and then a thin thermal insulation board slightly smaller than the cross section of the regenerator is attached to the reserved The front of the checker bricks are insulated, and then the large cracks of the single and main walls with a width of more than 5mm are closed with a relatively dry phosphoric acid mud, and the small gaps are sprayed and sealed with a shotcrete machine. If the end of the main wall is severely broken or deformed, or the crack is too large to be eliminated by the above methods, the damaged part should be removed and rebuilt according to the design size.
When the single (main) wall of the regenerator is melted in a large area due to high temperature, not only the wall is deformed, but the checker brick channels are also blocked due to melting. In serious cases, the masonry of the chute will sink due to loss of support. Make the gas leak out of phase. If this happens, the single (main) wall should be renovated in time.
During the renovation, the arrangement of the oven and buffer number, as well as the management of temperature and iron parts are similar to the renovation of multi-fire channels without uncovering the top. Before refurbishment, the carbonization chamber above the pre-repaired regenerator should be emptied. On both sides of the empty furnace, there are 1 to 2 braising furnaces and 2 buffer furnaces on each side. Corresponding measures shall be adopted for heat preservation of all relevant combustion chambers. However, no matter which method of heat preservation is used, the door of an empty furnace is not allowed to be opened, and all empty furnaces, furnace doors of braising furnaces, coal charging hole covers, fire hole covers, etc. are sealed. Then stop all the fire channels connected to the pre-repair regenerator from supplying gas, and the combustion chamber outside the oven should be replaced with coke oven gas for heating.
