Vertical Coal Mill operation
When the bed is unstable, the wet slag that is ground into the mill is extruded in a large amount and cannot be ground. The thickness of the layer can be adjusted by adjusting the height of the retaining ring. The appropriate height and their correspondence with the output of the Vertical Coal Mill should be found first during the commissioning phase. If the material layer is too thick, the grinding efficiency is lowered, and the grinding result is difficult to meet the requirements. If the material layer is too thin, vibration will be caused, and the wear and cost will be increased. If the rolling pressure is increased, the fine powder is generated, the material layer will become thinner; the rolling pressure is reduced, the grinding disc material becomes thicker, the corresponding materials are returned, the grinding efficiency is lowered, and the material layer becomes thick. If the internal air volume is reduced or the speed of the powder separator increases, the internal circulation will increase, and the material layer will be thickened; the internal air volume will increase or decrease the speed of the powder separator, reduce the internal circulation, and reduce the thickness of the material layer. It should be adjusted according to the actual situation. Under normal operation, the thickness of the bed after the roller type Vertical Coal Mill is compacted by the grinding roller should not be less than 25-40 mm. And the grinding and feeding should adopt the operation mode with less wind and small rolling pressure to flatten the material bed to make the Vertical Coal Mill run stably. If the bed is unstable at the time of feeding, the Vertical Coal Mill will not operate normally.
Control the grinding pressure
Grinding pressure is the main factor affecting the output of the Vertical Coal Mill, the grinding efficiency and the power of the Vertical Coal Mill. The Vertical Coal Mill applies high pressure to the material bed and crushes the material with the extrusion between the grinding discs. The pressure increases the honing ability and the output increases. In order to protect the reducer, the Vertical Coal Mill has a large value of pressure. It does not change after reaching this value. Since the slag bed is generally stable and the pressure control is stable, the increase of pressure is accompanied by an increase in power, resulting in an increase in unit energy consumption, an increase in wear of the sleeve and the disc, and therefore a suitable roll pressure. Production, quality and energy consumption are taken into consideration. This value is determined by the slag’s grindability, iron content, feed amount and specific surface area requirements. In the trial production, we should find the proper grinding pressure and negative pressure. The reasonable wind speed and air volume can form a good internal circulation, so that the material layer on the grinding disc is proper and stable, and the grinding efficiency is high. When the material entering the mill is unstable or other abnormal conditions, the grinding pressure should be appropriately reduced to ensure that the Vertical Coal Mill operates within the normal vibration range.
Suitable inlet and outlet temperature
The Vertical Coal Mill is a system of drying, grinding and powder selection. The temperature of the grinding is a comprehensive indicator to measure whether the drying operation is normal. In order to ensure good slag drying, the moisture content of the milled material should be less than 0.8%, and the outlet temperature of the Vertical Coal Mill is generally controlled at about 100 °C. If the temperature is too low, the moisture of the finished product is large, which reduces the grinding efficiency and the efficiency of the powder selection, and increases the load of the motor of the Vertical Coal Mill main motor and the classifier, and may also cause the dust collection system to condense; if it is too high, it will This will increase the coal consumption of grinding and increase the cost, and will increase the amount of returning material. It is worth mentioning that under different grinding conditions, such as before or after overhaul, the honing ability is caused by the different wear conditions of the boring sleeve and the grinding disc. Different from the difference in the ability to select powder, the grinding condition changes greatly, the temperature requirements are also different, and the outlet temperature can be adjusted according to the actual situation, but not lower than 95 ° C, not higher than 110 ° C, I have run through many years It is concluded that the temperature control is relatively low in the early stage of maintenance, but in the later stage of maintenance, in order to make the grinding condition better, the outlet temperature control is relatively high), increase the circulating grinding, and may also burn the dust bag due to the high temperature, which will also affect the harvest. Dust effect. It also affects the dust collector bag and reduces its service life. Therefore, the hot blast stove is required to have sufficient heating capacity and to adapt to the influence of different suction negative pressure on the hot blast stove.
Control reasonable air volume and wind speed
The Vertical Coal Mill mainly relies on airflow to carry animal material circulation. Reasonable air volume can form a good internal circulation, so that the material layer on the grinding disc is proper and stable, and the grinding efficiency is high. However, there are many factors affecting the air volume, mainly the capacity of the exhaust fan, the control speed of the classifier, and the opening of the circulating damper. The air volume is related to the feeding amount. If the feeding amount is large, the air volume should be large; Otherwise, it decreases. The air volume of the fan is affected by the system resistance and can be adjusted by adjusting the fan valve and each air distribution valve. The pressure difference of the Vertical Coal Mill, the pressure difference of the dust collector, and the amount of circulating return can all reflect the amount of air volume.
The pressure difference indicates that the air volume is large; otherwise, the air volume is small. The stability of these parameters indicates the stability of the air volume, thus ensuring the stability of the bed. In addition, the pressure difference is also an important parameter for reacting the internal resistance of the Vertical Coal Mill, and the large differential pressure is large, and vice versa.
Control the specific surface area of slag ultrafine powder
The specific surface area of the slag ultrafine powder is affected by the speed of the powder separator, the system air volume, the internal load of the mill, the operating pressure, and the amount of feed. In the case that the air volume, operating pressure and feeding amount are constant, the fineness can be adjusted by manually changing the speed of the classifier. When the adjustment is increased or decreased by 4r/min each time, the Vertical Coal Mill and the powder are enlarged. Machine load, increase the surface area can also be achieved by increasing the operating pressure, reducing the amount of feed or reducing the amount of air, etc., the four can be adjusted according to the actual grinding conditions.