The vibration occurred immediately after the roll had been lowered. The procedures and parameters were all normal, and the site did not feel the vibration. After checking, the vibrometer was found to be loose, and it was tightened again and the grinding was normal.
The looseness of the vibrometer is an ordinary matter. At this time, there are no abnormalities in the parameters of the control operation screen, and there is no sense of vibration on the spot. To prevent this from happening, you need to pay more attention to the patrol and keep it clean.
The central control vibration is too large, the site found a regular vibration and boring sound inside the vertical roller mill, emergency stop grinding, into the vertical roller mill to check the splint bolts are not significantly loose, there is no foreign matter in the grinding, everything is normal, only to find a roll into the vertical roller mill Loose skin.
Loosening of the roll is a very regular vibration. Because the diameter of the roll is smaller than the diameter of the grinding disk, it shows that the grinding disk rotates less than a week and the vibration occurs once. With the sound recognition on the spot, it can be judged that the roll skin loosens on a certain roll.
The lining plate is loose and generally shows continuous vibration. The site feels three vibrations per rotation of the disc. When it is found that the roll skin and lining plate are loose, it must be immediately stopped grinding, into the vertical roller mill for detailed inspection, and professional guidance to deal with, or when it falls off, it will cause a serious accident.
When the N2 capsules are not balanced, the tension forces of the tie rods are different, causing the mill to vibrate. Too high and too low buffer plate capacity weakened, but also easy to make the mill vibration is too large, so the preload pressure of each N2 capsule should be given strictly according to the set value, and regularly check it to prevent its leakage, leakage Gas, the pressure is not normal.
Mill feeding more, resulting in too much material in the vertical roller mill, mill operating conditions, malignant change, it is easy to instantaneous vibration trip. Because the waste bin can not be used, the slag is directly fed into the vertical roller mill when the grinding is started, and the vibration is large after the roller is lowered. At the same time, the thickness of the material layer is large and the inlet pressure is positive. This is because there are many slags when grinding and the belt weigher feeds. , Into the grinding feed more and cause. At this time, a large number of belt weighers should be reduced, and after the slag is normal, it is added to normal.
When the feed amount is too small, the material in the vertical roller mill is too small and the material layer is thin. The material buffer capacity between the disc and the grinding roller is insufficient, and vibration is easily generated. When the vertical roller mill is used for trial production, the feeding requirement is 70% for the mechanical requirements, so the feeding is small, which is one of the reasons for the large vibration of the neutral mill in trial production. Therefore, the smooth operation of the vertical roller mill can be guaranteed by feeding large particles of material.
Unsteady materials make the internal working conditions of the mills chaos and easy to vibrate. To achieve a smooth operation of the vertical roller mill, one of the important factors is to make the material feed smoothly on average.
When the kiln reduced output to 200t/h, the vertical roller mill started producing a large amount of slag, and if it did not vibrate in two minutes, it thought that the hot air outlet had accumulated more material, but after the clean-up, the vertical roller mill still could not start up. Analysis of reason: Due to less exhaust from the kiln exhaust, the vertical roller mill vibrates due to insufficient air volume. At this time, only the kiln is required to increase production, and the vertical roller mill feed amount is reduced as much as possible in order to start the vertical roller mill. Or increase the cold air baffle opening (or circulating air baffle opening).
Kiln grinding operations require integration. Mill operation affects the kiln and kiln operation also affects the mill. In some cases, the kiln working conditions are not stable, and the air flow from the high-temperature blower fluctuates. At the same time, the air temperature changes, making the working conditions of the vertical roller mill unstable, and it is easy to generate vibration. This can be adjusted by the cold wind and the circulating air damper to ensure that the inlet pressure is reduced. Stable, and try to ensure that the temperature of the vertical roller mill is stable, so that the mill is working properly.
VRM vertical roller mill can obviously feel the effect of grinding pressure rising on the vibration of the mill. When the feeding amount is certain and the pressure is too high, the grinding capacity will be greater than the capacity required for the material to become finished product, resulting in vibration generated by grinding. On the other hand, excessively low pressure causes too much material in the mill to generate large vibrations.
In the initial stage of trial production, the rotor speed is generally not set to the maximum. Because at this time the amount of feed and air volume are very small, when the election speed of the powder machine is too large, easy to produce too grinding, so that the mill fines increased, too much fine powder can not form a solid material bed, grinding roller 'eat' material Deeper, easier to produce vibration. Therefore, when the mill does not reach the designed output, the particles of the input material are required to be large and easy to operate.
When the high temperature fan outlet temperature changes, the mill operating conditions will change, too high to make the grinding plate feeding bed is not easy to form, too low can not dry the material, causing the nozzle ring clogging, etc., thicker material bed makes the mill produce abnormal vibration .
In this case, the conditions of the mill were stabilized by adjusting the water spray in the mill, spraying the water from the humidifying tower, or adding cold air, circulating air, stabilizing the mill inlet and outlet temperatures.
vertical roller mills are generally open-air, and the environment has a great impact on them. In the event of heavy rains and heavy rains, the temperature of the vertical roller mill body and pipes changes suddenly, and the outlet temperature rapidly decreases. This can easily cause the vertical roller mill to jump and must be quickly adjusted: Warming, pulling the wind, reducing the material to normal. The vertical roller mill temperature is affected by changes in the amount and composition of the material to be ground. When the change is large, it is necessary to adjust the spray, the feed, and the baffle opening to stabilize.
The outlet temperature is too high, prone to empty grinding, the material can not form a solid material bed on the disc, resulting in vibration, too easy to plug the nozzle ring, etc., but also easy to produce vibration, then need to adjust the inlet temperature, grinding water, also The amount can be added or reduced.
When the material entering into the vertical roller mill is very humid, large quantities of wind, excessive air flow, excessive feeding, unstable wind speed, etc. will all cause plugging of the outlet ring. If the plugging is severe, the wind speed and air volume around the grinding wheel will be uneven, and the grinding bed will not be loaded. Flat, producing large vibrations. At this time, it is necessary to stop grinding and cleaning. When grinding again, it is necessary to pay attention to reducing large pieces of grinding, increasing the air volume, and reducing the feeding, while maintaining the stability of the grinding conditions and preventing the clogging of the spout ring.
When the lock valve is blocked and no material enters the grind, it will cause an empty grind which will generate large vibrations. When the lock air valve leaks, abnormal vibration may also occur.
Usually pay attention to whether the bolts inside the mill are loose and whether the bolts are off-welded, including the lock valve. Both Danang and Chizhou had three lock-off valve wall shedding, which caused the mill to vibrate. When it is found that there are large pieces of iron in the grinding, it should be stopped and removed. Even if he does not affect the vibration jump stop, it will also cause damage to the mill, such as damage to the bezel ring. This phenomenon has occurred in Chizhou No. 1 grinding mill. Because of the large mill capacity, general iron ore is not easy to find, and finally the bezel is destroyed.
Bulk into the mill, in addition to the possibility of blocking the spout ring, there may be grinding roller, resulting in vibration, so we must put an end to the bulk into the mill.
Adjusting the rotor speed of the separator is the most common method of adjusting the fineness and is the most important method. Usually change the fineness: The first thing that comes to mind is to adjust its speed, and when it is rough, it increases the speed.
In trial production, when using a hot stove or feeding less, the internal ventilation of the mill is small, the speed of the separator is set to 70-80%, and fineness can basically be achieved. With the increase of hot air in the kiln, the ventilation in the mill increases, the baffle of the EP fan increases, and the fineness increases. At this time, the speed of the separator should be gradually increased to ensure the fineness.
For example: When the kiln feeds to full load, the kiln air volume is very large, even if the EP fan is turned on to 100%, and the inlet is still under positive pressure, the fineness is easy to increase. Even if the separator is added to the limit, it cannot be used. Fineness is qualified. At this time, it may be considered to mill the bypass baffle, but this method is more dangerous and it is easy to make the mill trip. Therefore, we must be cautious. Every 1% of opening must be observed for a long time to ensure the smooth operation of the mill and reduce the fineness within a certain range. This method is limited to when the air volume is too large.
VRM vertical roller mill pressure can be given in the middle control. Generally, the pressure is set to the minimum when the grinding is started. As the output rises, the pressure must be gradually increased. Otherwise, the rough running phenomenon occurs due to the insufficient capacity of crushing and grinding.
The exit temperature of the mill rises rapidly, or maintains a higher temperature, the roughing material may also run rough, because during the temperature rise process, the fluid velocity in the mill and the internal energy of the material in the mill are changed, and the fine material is increased to make Brownian motion appear. The oversized material is pulled out of the grinding body. This may be caused by the temperature of the kiln tail, the change of the air volume, or the change in the moisture content of the incoming mill material. The process line of the mill in series with the humidification tower can adjust the water spray of the humidification tower, and can be mixed with circulating wind or cold wind when the air volume is allowed.
Into the mill is not easy to make the working conditions in the mill chaos, wind speed, air volume fluctuations, resulting in intermittent run rough. Solution: Stabilize the amount of grinding material, ensure proper grinding pressure, or reduce the amount of production.
Into the mill material strength and hardness, or large particle diameter of the material, it is difficult to crush and grinding, coupled with the increase in the number of stop grinding cycle, the final performance of too much material in the mill, the solution: a. Improve the grind material into the greasy And diameter b. Appropriate amount of c. Appropriate amount to reduce production.
After the mill has been running for a long time, the blades of the separator, the roller skin, the disc lining plate, the nozzle ring, etc. will be subject to different degrees of wear. This wear can cause the fineness of the mill to run rough.
The powder sorting device, spout ring, etc. should always be maintained with care. If the damage is serious, it must be promptly replaced and repaired. 7, equipment failure and running rough
The classifier was bad and there was material running rough. During a period of time when the powder selector could not be restored, the operator used the control pressure, air volume, and temperature to reduce the fineness to about 21%, basically for kiln calcination.
Usually fineness is not caused by a certain kind of reason, but also reducing fineness is not only a method, you can find the main reason for running rough, for this reason, take measures, and can use other methods to make up for this method The deficiencies in order to achieve the purpose of reducing fineness.
After the rotary valve is blocked, cleaning is very dangerous and very laborious, which severely restricts production. The reasons for the blockage and the methods for handling are mainly the following:
VRM vertical roller mill rotary valve, sometimes a large rock, resulting in the rotary valve body does not move, but the special function of the sliding coupling makes the motor immediately jump and stop, causing the grinding belt to continue to run and blocking materials, to solve this problem It is to reduce the bulk of the material into the mill. In normal production, the phenomenon of blockage caused by the mechanical failure of the lock valve is not much, but it does not rule out the possibility, so pay attention to its maintenance and inspection, and timely find problems in a timely manner.
Raw materials milled into the mill material consists of various components, each of which has different moisture and viscosity. The layer of limestone that was mined earlier in the mine is a layer of non-limestone material. This batch of material has small particles, strong viscosity, and easy to accumulate when the moisture is large.
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