After the kiln masonry is completed, how to steadily rise from the normal temperature to the working temperature, and to ensure the smooth transition of the masonry volume changes in each part is very important. There have been many glass production lines at home and abroad due to improper operation of the kiln, which caused some parts to be rebuilt, or glass quality problems appeared soon after it was put into production, which seriously affected the company's benefits and even endangered the life of the kiln. The following are a few issues that need to be paid attention to during the baking process of the glass furnace.
1. Preparation before heating-up the furnace
(1) Formulation of heating curve.
Formulating a reasonable heating curve and strictly controlling the heating rate is the basis for the work of the kiln. The temperature control accuracy of the hot-air kiln is high, but with the improvement of the gas furnace and the operating level, the heating speed of the gas-fired kiln can also meet the heating Curve requirements.
The temperature rise rate is very slow between 120~350℃. This is a key temperature range of the kiln. The control and adjustment of this range is directly related to the baking quality of the big scorpion.
(2) Check whether the reserved expansion joints are suitable when building the kiln.
In particular, check the expansion joints of the large turret, the expansion joints between the partition wall of the regenerator and the top of the turret, between the wall of the regenerator and the top, the slope wall of the small furnace and the small furnace stack, the bottom plate and the breast wall support iron , Expansion joints before and after the neck hanging wall.
(3) Check whether there is room for moving the steel parts of the card neck hanging wall. There are many glass companies because the steel parts are not reserved enough and the steel parts cannot move after the expansion of the steel parts, which causes the bricks to be cut, which seriously causes the suspension walls to sink or even collapse. After the kiln is officially heated up, always pay attention to the ceiling wire of the suspended wall not to be too tight, otherwise it is easy to squeeze the suspended wall bricks.
(4) Keep warm. In particular, heat preservation of the hanging wall of the neck and the flat chute of the cooling part should be done well.
2. Staffing and measures
The adjustment process of tightening the top wire is a test of the physical strength of the personnel, especially when the temperature rises above 200 ℃, the number of personnel must be sufficient, the labor protection supplies are fully equipped, and the tools must be easy to use.
3. Setting of the expansion ruler (Zezhizi)
It is necessary to set up a large scale expansion ruler reasonably. The expansion ruler is placed in 3 rows horizontally along the dome, 1 row in the center of the dome top, 1 row on each side of the ribs, 3 in each row, 1 in the head, and 1 in the middle. Use this as a reference for the rest of the larger arches.
4. Recording and analysis
The temperature and expansion rule records must be realistic. When the recorder finds something abnormal, he must report to the technician in time. The kiln technician must analyze the record and report in time and take corresponding measures.
(1) Adjust the brace and top wire of the corundum brick body as many times as possible.
The adjustment of the brace of the silica brick between 200~350℃ needs to be sufficient many times. Because the corundum body has a large proportion and a high crystal form transition temperature, the amount of loose top wire and brace should not be too large, otherwise it cannot be saved once the adjustment is overdone. The silicon brick is in the dense crystal form conversion temperature range at 200~350℃, the volume expansion is very concentrated, and the sling span is large, so the number of adjustments should be as many as possible, and the amount of adjustment should be sufficient each time, otherwise it will cause no adjustment. After that, the part that was adjusted first needs to be adjusted again.
(2) The analysis of the expansion rule records should be timely and careful.
Especially in the middle and late stages of the kiln, when it is found that the center of the dome top of a certain section rises, but the two ribs basically do not move or even drop, special attention should be paid and the cause should be actively searched for, usually because of insufficient reserved expansion joints or steel structure. If the cause cannot be adjusted, the cause is unknown or the cause cannot be dealt with even though the cause is found, immediately stop the temperature increase, temporarily keep the temperature warm, and decisively adopt the local pressure method to ensure the normal curvature of the dome body and ensure the safety of the dome.
5. Pay attention to the top wire at the bottom of the kiln and the bottom pool wall
If it is a cold repair of the kiln, pay attention to the top wire at the bottom of the kiln and the bottom wall. Due to the incomplete treatment of the residual glass in the cracks of the kiln bottom bricks or other reasons, the kiln bottom does not expand in the expected direction, and the expansion of the pool bottom bricks is limited or the pool bottom drives the pool wall bricks above it to resist the top wire of the pool wall. If it is discovered and not handled in time, it is very likely that the pool wall will be tilted towards the inside of the kiln (horizontal pool walls are especially prone to occur) or the bottom of the pool will squeeze and bulge. The author has dealt with similar problems. This requires that the reserved expansion joints must be reserved during the kiln masonry process, covered with suitable corundum bricks, and the residual glass in the brick joints should be cleaned up. The top wire should be loosened before the kiln and checked at any time. Especially the front and rear pool walls of the cooling part and the melting part.
6. Temperature control and adjustment after excessive fire
6.1 When there is a big fire
Gas-fired and heavy oil kilns are relatively safer for over-fire. Gas-fired kilns, especially those using gas pipelines, must pay special attention to explosion-proof during over-fire. In addition to the aforementioned sealing, the following must be done. A few points:
(1) Ensure that the temperature of the gas flue reaches 350~450℃. Too low is easy to set off, and too high is easy to burn the gate and the bell of the exchanger.
(2) The disc valve and the main gate of the kiln pipe should be coordinated, and the gate of the branch pipe of the kiln cannot be closed.
(3) The personnel for sealing the kiln holes should be in place, the sealing speed should be fast, and the sealing should be good.
(4) It is necessary to insert the five purge steam guns prepared in advance into the kiln pipe in time (check the steam pressure beforehand), and open the tail end vent pipe at the same time. After the steam is discharged from the vent hole, the air gun in the main line can be turned off. The remaining air guns have been kept for 48 hours. A glass factory pulled out the steam gun a few hours after the fire, causing the kiln pipe to explode. Fortunately, no casualties were caused.
6.2 After the fire
After the fire is over, the heating curve must be strictly implemented, followed by strict temperature control. Since the temperature after a large fire is just around 900℃, it is far from the expansion point of zirconia corundum bricks at around 1100℃. If the temperature is not well controlled, it is difficult to release the expansion of the zirconium corundum masonry smoothly, such as pool walls, breast walls, etc. The explosion was even squeezed and dislocated. A certain glass factory caused water cooling to be repaired because the breast wall tilted inward after the kiln was baked.
The problems that need to be paid attention to after a high fire are: the tongue hanging on the path, the top wire of the breast wall, the top wire of the longitudinal pool wall, and the brace of the regenerator should be paid close attention to after the high fire. The top wire should be adjusted several times, and the top wire can be roasted if necessary. The kiln technicians personally check it, so as not to loose too much and cause the flat wall to sink.
7. Common problems
7.1 Pool wall brick burst
The pool wall is one of the most important parts of the glass furnace. The safety of the pool wall directly affects the safety of the furnace and the glass quality.
The author used the most traditional method in the kiln work for more than a dozen times, that is, wait for the standard temperature to rise above 500℃ before turning on the cooling fan on the pool wall. The opening of the large fan is fully open when it reaches 500℃. Make the pool wall along the thickness direction to form a more natural temperature gradient as much as possible from the beginning. Specifically, the temperature of the outer surface of the pool wall can be maintained at 100~200℃. After gradual improvement, the bursting of the pool wall tiles has been reduced by more than 90%, especially the cracks that appeared before in the subsequent kilns.
7.2 Inclined breast wall
The inclination of the parapet wall is generally caused by the deformation of the brace of the parapet wall or the loosening of the top wire of the parapet wall or the insufficient expansion of the reserved joints. In order to avoid such things from happening, make sure that the parapet pallet is level and tightly integrated with the palm iron during masonry. During the baking process, always pay attention to check whether the top wire of the breast wall and the slope wall are flexible.
8. Hot charging kiln and later adjustment
Before and one month after the hot charging of the kiln, the braces and top wires of the kiln should be adjusted uniformly to ensure the structural integrity of the refractory materials after high temperature shrinkage.
9. Conclusion
The kiln baking process is a complicated technical work. Only by keeping a clear mind, full energy, high sense of responsibility, and more inspection and thinking can we ensure the baking quality of the kiln and lay a solid foundation for the next step of normal production. Foundation and guarantee. The above are the easily overlooked problems in several kilns that the author has repeatedly baked and combined with theoretical analysis. Other normal operations are similar, so I won’t repeat them here.
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