1 existing problems
Oil leakage of grinding roller often occurs in cement plants with vertical mill, which is a difficult problem that always puzzles vertical mill manufacturers. Oil leakage not only pollutes the environment, but also increases the production cost. There are many causes for oil leakage of vertical grinding roller, which can be summarized as follows:
First, the reason of grinding roller sealing. At present, the vertical grinding roller seal mainly adopts three skeleton lip seals, one dust-proof and two oil-proof. However, the working environment of the vertical mill is very bad, which belongs to the working condition of high dust, high temperature and impact vibration, so the seal is worn quickly. And it is very difficult to replace the seal. It is necessary to turn over the roll and remove the grinding roll from the rocker arm. Its work is time-consuming and laborious, and the maintenance cost is very high.
Second, the oil return of grinding roller lubrication system is not smooth. When the grinding roller works, the bearing will generate some heat and is in a high temperature environment. Therefore, thin oil circulating lubrication is generally adopted, which can take away the excess heat and ensure that the bearing is within the normal temperature range. However, in actual work, if the oil return is not smooth, the oil level in the grinding roller will rise and finally overflow from the oil seal and air cap.
The reasons for poor oil return of grinding roller lubrication system are as follows:
(1) Temperature causes. When the mill is started after shutdown or the ambient temperature is too low, the temperature in the grinding roller and the temperature of the oil return pipe are not high. Because the vertical mill generally adopts the viscosity of 320mm ²/ S lubricating oil has poor fluidity, resulting in poor oil return.
(2) Causes of resistance. The lubrication of vertical mill generally adopts centralized lubrication. Other oil stations, including grinding roller lubrication station, are centrally placed in one room, which is generally far from the lubrication point of vertical mill, so the pipeline resistance is large, resulting in poor oil return.
(3) Cause of air inlet pipe. In fact, the oil supply and return cannot be consistent, so in order to ensure that the oil level is not too high, the oil return is greater than the oil supply. The oil return shall be set at the lowest oil level to be guaranteed. When the oil level is lower than the minimum oil level, the oil return pump will empty, resulting in the decline of the capacity of the oil return pump and poor oil return.
Therefore, when it is difficult to effectively improve the grinding roller seal and grinding roller lubrication system, a high temperature resistant liquid level sensor is added in the grinding roller to achieve good results. The liquid level sensor lead installed on the bearing cover of the grinding roller shaft is led out from the grinding roller shaft, and a three-way electromagnetic ball valve is added on the oil supply pipeline of the oil station. The normally open point is connected with the oil supply pipeline of the grinding roller, and the normally closed point is connected with the oil return pipeline.
When the liquid level in the mill is higher than the upper limit, the electromagnetic ball valve will transfer the oil supplied by the oil supply pump to the oil return pipeline; When the liquid level reaches the lower limit, the electromagnetic ball valve will be converted to the oil supply pipeline; So as to realize the control of lubricating oil level in the grinding roller. Since the grinding roller rotates and fluctuates up and down during operation, and the liquid level changes up and down, we only collect the minimum value within 5S of the liquid level sensor as the actual liquid level value, so as to reflect the real situation of the liquid level.
By adding a liquid level sensor, it can ensure that the grinding roller does not leak oil when the sealing of the grinding roller is worn and the oil return is not smooth; The change of the liquid level in the grinding roller can also be monitored in real time to achieve the purpose of knowing and controlling the oil level, which makes the control of the vertical mill a step towards intelligence.
Raymond Mill solution
Professional ingenuity, high efficiency and low consumption Raymond mill, calcium hydroxide mill