Vibration occurred immediately after the grinding roller was lowered. The operation procedures and parameters were normal, and no vibration was felt on site. After inspection, the vibration meter was found to be loose, re-tightened, and the grinding was normal.
It is common for the vibrometer to be loose. At this time, there is no abnormality in the parameters of the central control operation screen, and there is no vibration feeling at the scene. To prevent this from happening, pay more attention to the inspection and keep it clean.
The vibration of the central control is too large, and regular vibration and dull sounds are found in the mill. The mill is stopped urgently. Check the bolts of the plywood during the mill to check whether there is any looseness in the mill. The skin is loose.
Roller skin loosening is very regular in vibration. Because the diameter of the grinding roller is smaller than the diameter of the grinding disk, it shows that the grinding disk rotates less than one week, and the vibration appears once. In addition, on-site sound recognition, it can be judged that a certain roller has a loose roller skin.
The lining is loose, and generally shows continuous vibration. The scene felt three vibrations per rotation of the grinding disc. When it is found that the roller skin and liner are loose, the grinding must be stopped immediately, the detailed inspection should be carried out, and professional guidance should be given to the treatment, otherwise it will cause serious accidents when it falls off.
When the N2 capsule is unbalanced, the buffering force of each tie rod is different, which causes the mill to vibrate. If it is too high or too low, the capacity of the buffer plate will be weakened, and the vibration of the mill will be too large. Therefore, the preload pressure of each N2 bladder should be strictly given according to the set value, and it should be checked regularly to prevent oil leakage and leakage.
The mill feeds too much, resulting in too much material in the mill, and the working conditions of the mill change badly, so it is easy to vibrate and stop instantly. Because the waste bin cannot be used, the slag is directly fed into the mill when the mill is opened, and the vibration after the grinding roller is too large, and the thickness of the material layer is large, and the inlet has a positive pressure. This is because the slag is spit out when the mill is opened, and the belt scale feeds , The feed into the mill is increased. At this time, the feeding of the belt scale should be reduced by a large amount, and then it will be added to normal after the spit is normal.
If the feeding amount is too small, the material in the mill is too little and the material layer is thin. The material buffering capacity between the grinding disc and the grinding roller is insufficient, and it is easy to produce vibration. During the trial production of vertical mills, due to mechanical requirements requiring 70% feed, the feed is too small, which is one of the reasons for the large vibration of the vertical mill in trial production. Therefore, the feed of large particles can ensure the smooth operation of the mill.
Unstable materials make the working conditions in the mill chaotic and easy to vibrate. To achieve the stability of the vertical mill operation, one of the important factors is to make the materials feed smoothly and evenly.
When the kiln output was reduced to 200t / h, the mill produced a large amount of slag as soon as it was started, and it vibrated and stopped within two minutes, thinking that the hot blast had a lot of material accumulation, but after cleaning, the mill still could not start. Reason analysis: Because there is less exhaust gas from the kiln tail, the mill vibrates due to insufficient air volume. At this time, the mill can only be turned on when the kiln is required to increase production and the feed amount of the mill is minimized. Or increase the cooling air baffle opening (or circulating air baffle opening).
Kiln mill operation requires integration. Mill operation will affect the kiln, and kiln operation will also affect the mill. Sometimes the working condition of the kiln is unstable, the air volume from the high-temperature fan fluctuates, and the wind temperature changes, which makes the working condition of the mill unstable and prone to vibration. This can be adjusted by the cold air and circulating air baffle to ensure the negative pressure of the mill inlet Stable, and try to ensure that the temperature of the mill is stable, so that the mill works normally.
The vertical mill can clearly feel the impact of the rising grinding pressure on the vibration of the mill. When the feeding amount is fixed and the pressure is too high, the grinding capacity will be greater than the capacity required for the material to become the finished product, resulting in the vibration of the mill. On the contrary, if the pressure is too low, there will be too much material in the mill, which will cause large vibration.
In the early stage of trial production, the rotor speed is generally not set at the maximum. Because the feeding volume and air volume are very small at this time, the rotating speed of the elected powder machine is too large, it is easy to produce over-grinding, which increases the fine powder in the mill, and too much fine powder cannot form a strong material bed, and the grinding roller 'eats' the material Deeper, easy to produce vibration. Therefore, when the mill does not reach the designed output, the particles of the milling material are too large and easy to operate.
When the temperature of the outlet of the high-temperature fan changes, the working conditions of the mill will change. If the temperature is too high, the material bed on the grinding disc will not be easily formed, and if it is too low, the material will not be dried, which will cause the nozzle ring to block. .
When this happens, adjust the water spray in the mill, spray the water in the humidification tower, or mix cold air, circulating air, stabilize the temperature of the inlet and outlet of the mill, and stabilize the working conditions of the mill.
Vertical mills are generally open-air, and the environment has a great impact on them. The current heavy rain and heavy rain make the temperature of the mill body and pipeline suddenly change, and the outlet temperature decreases rapidly. This is very easy to cause the mill to stop and must be quickly adjusted: heating , Pull wind, reduce material adjustment to normal. The temperature of the grinding mill is changed by the amount of materials and the composition of the grinding mill at the same time. When the change is large, it is necessary to adjust the water spray, feeding and the opening of each baffle to stabilize.
If the outlet temperature is too high, empty grinding is likely to occur, and the material will not form a strong material bed on the grinding disc, which will cause vibration. If it is too low, it will easily block the nozzle ring, etc., and it is also easy to produce vibration. The output can be increased or decreased in an appropriate amount.
When the feed material is very wet, mixed with large pieces, insufficient air volume, too much feed, unstable wind speed, etc. will cause nozzle ring blockage. When the blockage is serious, the wind speed and air volume around the grinding disc will be uneven, and the material bed on the grinding disc will not Flat, generating large vibrations. At this time, the grinding needs to be stopped and cleaned. When the grinding is started again, it is necessary to reduce the large pieces into the grinding, increase the air volume, reduce the feed, and at the same time keep the grinding working condition stable and prevent the nozzle ring from clogging.
When the air lock valve is blocked and no material enters the grinding, it will cause empty grinding and will produce large vibration. When the air lock valve leaks, abnormal vibration will also occur.
Usually pay attention to whether the bolts in the mill are loose and whether the bolts are de-welded, including the air lock valve. Digang and Chizhou have experienced three-way air lock valve wall falling off, which caused the mill to vibrate. When a large iron block is found in the mill, the mill should be stopped and removed in time. Even if he does not affect the vibration trip, it will cause damage to the mill, such as damage to the baffle ring. Due to the large production capacity of the mill, it is not easy to find the general iron block, and it is only known that the baffle was destroyed in the end.
In addition to the blockage of the nozzle ring, it may also grind the roller and cause large vibration. Therefore, it is necessary to prevent the large block from entering the grinding.