1、Background
The correct use of the kiln and the maintenance and upkeep of key parts are fundamental to prolonging the life cycle of the kiln, extending the life cycle of the whole line of equipment and improving economic efficiency. In the late stage of the kiln, the workload of thermal repair and maintenance will be greater. If the maintenance and repair are not timely and the method is not innovative, it is still difficult to reach the design kiln age, not to mention extending the life of the kiln. A domestic float plant in the late kiln, through bold and innovative thermal repair, thermal repair and process improvement measures, so that the kiln life cycle extended by more than a year, providing valuable experience for other float glass enterprises in extending the kiln life cycle.
Extending the life cycle of float glass kiln through refractory selection and construction
The original design kiln age of the float glass kiln is 3 years, to the beginning of 1999, has been safely run for 3 years and 2 months, more than the design kiln age. During the operation period, the kiln has experienced five color changes, and its burnout condition and aging equipment have seriously endangered the safety and stability of production, and must be repaired according to the conventional plan. In order to reduce investment and production costs, it was decided to extend the current kiln age of the float line by 1 to 1.5 years.
Kiln after more than three years of operation, the bottom of the pool, pool wall and chest wall, large swan, lattice body, small furnace swan top, heat storage room front wall, small melting department top swan and other parts of serious burn damage, for different parts, take different measures, so that the situation there can be alleviated.
2、Technical measures
2.1 Reinforcement angle iron to solve the problem of the pool bottom brick seam becomes large
The last cold repair, in order to save costs, the kiln pool bottom brick was not replaced, at that time, 3 # small furnace before the pool bottom brick seam has been greater than 20mm. during the cold repair experts made an identification of the situation: the float line to produce mainly colored glass, the current kiln period can not produce less viscous transparent glass, in order to minimize the flow rate of glass liquid, to ease the scouring of the pool bottom brick. However, the current production period, the need to change the product of the kiln from emerald green glass to ocean blue glass. Experimentally determined that at high temperatures, the viscosity of ocean blue glass is smaller than that of clear glass, and if the bottom of the pool brick joints are not handled properly, there is a high risk of glass liquid leakage accidents at the bottom of the pool when producing ocean blue glass. For this reason, before the color change to determine the hot spot parts of the pool bottom brick reinforcement treatment program.
In the pool bottom brick seam larger place, according to the method shown in Figure 1 with a thin sheet of iron brick will be seam plug card, and then use the angle top sheet brick, in order to prevent it from falling, the top edge of both sides of the angle and the pool bottom support steel plate firmly welded together. This effectively prevents the leakage of low-viscosity glass liquid from the gap at the bottom of the pool, run off.
2.2 Strengthen the cooling pool wall and chest wall
Due to the serious burn damage in the late stage of the kiln and the operation of the bias material from time to time, the material pile before and after the pool wall brick has been washed very thin, the chest wall has a number of hook brick ends were burned off or under the gap brick through the fire, so that the support of the place under the palm iron and to iron plate because of the lack of isolation protection and directly exposed to the kiln flame, if not timely or improper treatment, it is very likely that the iron parts (under the palm iron, iron plate) If not handled in time or in an improper way, there is a high risk of deformation of the kiln body due to serious burn damage, which will eventually lead to irreparable tilting and collapse of the small furnace stack and chest wall.
Although the traditional operation method of using fan blowing air to protect iron parts can properly reduce the temperature of burned parts and mitigate the risk of aggravating burn damage by continuous high temperature, the general cooling air blowing air protection scheme is not helpful at the critical moment when the burn damage is more serious in the later stage of kiln use. Therefore, the compressed air pipeline is set up at the gap between the two sides of the pool wall, and a duckbill-shaped compressed air nozzle is made to blow the air directly at high pressure for cooling, with the air pressure kept at about 2MPa to block the flame from further burning the iron parts; at the same time, several rows of 160×40×40 (mm) T-shaped water bags are installed immediately adjacent to the bracket plate, with the water pressure kept at about 1MPa to force cooling on the part. The enhanced double cooling protection measures effectively reduce the burnout of this part.
2.3 Cooling and direct repair of the large swan
The fire penetration is more serious after the burnout at the expansion joint of the large swan in the late stage of the kiln. The traditional hot repair operation is to cover with hot patching material, which is difficult to operate on the one hand, and on the other hand, due to the operation process, it is easy to cause the hot patch and the dirt outside the top of the swan to fall into the kiln and produce inclusions in the melting process, which directly affects the quality of the glass plate surface. In order to ensure the quality of the glass plate surface, the use of traditional thermal repair program is not suitable. For this reason, the cooling air box or axial fan is set up near the top of the large swan through the fire, in order to improve the operating environment. The operator wears good heat-insulating labor protection equipment and uses “spare swan bricks to directly re-swan”, which is easy and quick, but also economical and practical. The effect of mature repair is good and has almost no effect on normal production.
2.4 Unclogging lattice body
Late kiln lattice hole accumulation speed is fast, blockage is serious, individual small furnace lattice body has local collapse phenomenon, which not only affects the stability of flame control, and may be due to careless operation and deterioration of the situation, leading to early cold repair.
For the lattice body blockage, the technically more mature grasping skid and put long fire high-temperature melting and unblocking method combined measures to ensure the smooth flow of air in the lattice body of the kiln later. The traditional method of picking up the skid is to use an elongated, socketed steel pipe to poke up and down directly from the bottom channel of the regenerative chamber. Put long fire high-temperature melting and unblocking method operating principle: the blockage in the accumulation chamber lattice body is mostly glass body and sulfide and other substances eutectic, the use of its melting point is lower than the lattice body brick characteristics, the opposite small furnace combustion lance flame is extended, the temperature rises and controlled in the upper lattice brick load softening temperature below, and then the blockage in the upper layer of the lattice body is burned and melted and fall naturally. Grubbing skid and put long fire high-temperature melt unblocking method combined with the use of measures to achieve the strengths and weaknesses, complementary effects, unblocking lattice body more thoroughly, to provide technical assurance of stable process control. For individual small furnace (such as hot spots in the South 3 #, South 4 # small furnace) lattice body of the local collapse of the situation, in order to achieve timely monitoring and slow down the development of deterioration, the following measures were taken: (1) strengthen the number of inspections, (2) clean up the pit in the fallen brick, (3) shut down the South 3 # small furnace combustion wind and lance, on the one hand, to stop the airflow to further flush the local collapse parts, on the other hand, save energy, to Eliminate meaningless waste, (4) control the flame length of the opposite small furnace (such as the north 3# small furnace), and strictly prohibit the opposite flame is too long and aggravate the burning loss of the lattice body.
2.5 small furnace swan top
Individual small furnace due to swan top burn thin, top swan appear large area red, processing is not timely, will seriously affect the use cycle of the furnace. In order to prevent the top swan of small furnace from burning through and collapsing, the same method of direct thermal restoration of the swan is adopted as that of dealing with the expansion joints of the large swan through the fire for thermal repair, with better effect.
2.6 Repair of the hole in the front wall of the heat storage chamber
In this kiln period, a hole as large as 300mm×700mm was burned through in the front wall of the heat storage room, and such a burned condition was never seen in the history of kiln thermal repair in this plant. Faced with the situation of large burn-through hole area, small operation space (small furnace neck size is narrow), inconvenient foothold, no suitable replenishment materials, no ready-made operation experience and methods, we had considered hiring foreign experts to use the jet method of thermal repair, but it cost $800,000 and the cost was relatively high. The plant, according to the previous thermal repair experience, after repeated preferences, adopted “zirconium thermal patching material mixed with old refractory brick slag with particle size of 3-10mm” as the thermal patching material, and in order to solve the problem of small operating space and inconvenient thermal repair operation, a temporary shelf was built on the slope of the small furnace swan, so that the thermal repair operator can easily lie on the shelf In order to solve the problem of small operating space and inconvenient thermal repair operation, a temporary shelf was set up on the slope swan of the small furnace, so that the thermal repair operator could easily recline on the shelf to open the wall in sections, and then hot patch in sections.
2.7 small melting part of the top swan part
After the glass variety changed to ocean blue, the small melting part of the top of the swan melt, dripping material increased, resulting in the glass surface swan debris increased, the amount of substandard products is higher. Response measures are to strengthen the maintenance of kiln pressure control equipment to minimize fluctuations in kiln pressure; while improving the melting process system, so that the end of the small furnace (6 # small furnace) oil flow control from the original 7 ~ 8kg / min down to 2 ~ 2.5kg / min, in order to best flame control. As a result, the amount of defective glass selected due to large inclusions dropped by more than half from about 50,000m2/month, while the ash accumulation rate in the runner part also slowed down accordingly, and the frequency of blowing in the runner part was reduced from 2~3 times/month to 1 time, which increased production and efficiency quite obviously.
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