The working principle of vertical roller mill:
The main motor of the vertical roller mill drives the grinding plate in the grinding machine through the transmission of the reducer. The grinding roller rotates around the pins under the friction of the grinding plate. After the feeding screw is dropped into the center of the grinding plate,it is moved to the edge of the grinding plate by the centrifugal force. When passing through the grinding rail, it is crushed and grinded between the grinding roller and the grinding plate.
The pulverizing pressure of the grinding roller relative to the material and the grinding plate is provided by the stretching device of the hydraulic cylinder. During the pulverization process, the material is subjected to the pressure of the grinding plate and the shearing force generated by the movement between the grinding plate and the grinding roller. After the material is extruded, a bed is formed on the track of the grinding machine, and mutual extrusion and friction between the particles of the material bed causes peeling of the edges and edges, which further pulverizes.
The ground material continues to move toward the edge of the plate until it overflows the plate. A special structure of the pressure plate is designed on the side of the grinding roller, and the material can be continuously pressed into the grinding roller for extrusion. An air inlet ring is arranged around the grinding plate, and the airflow from the high pressure fan rises from the material of the air intake ring from the bottom to the high speed, and enters the multi-wheel classifier above the main machine for coarse subdivision, and the powder is in the grading process. Subject to centrifugal force, fluid resistance and self-gravity, the coarse powder larger than the converging point falls back to the plant area.
The central cone of the mill is ground again together with the pellets. The graded fine powder that meets the fineness requirements is used as the finished product. After the airflow is taken to the upper outlet of the casing and enters the dust collector, it is collected and sent to the finished product warehouse by the pneumatic conveying system . The rising airflow at the air inlet ring also allows the particles with a larger specific gravity to fall under the air intake ring, and is discharged from the slag discharge port at the lower part of the mill, and returned to the feed system by the return screw conveyor to re-enter the mill.
- material bin 2. feeding system 3. main processing machine
- deduster 5. air blower
Advantages of vertical roller mill:
The contact surfaces of the grinding plate and the grinding wheel are specially designed to ensure efficient and stable operation.
The roller hydraulic system has an adjustable spring rate that is applied to the bed through a hydraulic pull rod.
The designed vertical roller can be easily flipped over the casing and the roller lining is easy to maintain.
The material of the roller and the grinding plate are made of alloy wear-resistant linings with long service life.
A highly efficient airflow classifier that is easy to adjust to grade different sizes of products.
The unique central funnel unit can effectively mix coarse and new materials, enabling the mill to be stably and continuously fed.
Reliable roller air seals eliminate unnecessary airflow into the mill.
The special sealing design of the roller bearing prevents dust from penetrating.
A robust gear reducer is used to ensure efficient and stable power transmission.
Brief description of vertical roller mill operation:
The most basic reason why vertical roller mill is widely used is that it has low power consumption, and several units are operated in one machine, and it exhibits excellent operational flexibility and can produce various kinds of The different high-quality products are now briefly described as follows:
Crushing: 400-500mm stone material is crushed and broken in two stages and iron is removed into the raw material barrel to be ground.
Feeding: The pulverized pellets are accurately metered from the raw material barrel through the belt scale and sent to the central funnel of the grinding unit and the multi-rotor high efficiency classifier.
Raw material grinding: The three grinding wheels are used to apply force to the turntable to the bed, and the granules are pulverized into fine powder. The raw material falls from the central funnel to the center of the grinding plate, and the raw material is taken out by centrifugal force, the fine powder is formed by the roller group and the grinding plate gap controlled by the hydraulic pressure.
Drying of the raw material: After passing through the dam ring at the edge of the grinding plate, the ground fine powder rises with the airflow transmitted by the diversion ring located around the grinding plate, activates through the fluid bed, and achieves the functions of drying and solid-gas mixing.
Pre-grading: As the fine powder rising through the airflow of the diversion ring passes through the middle section of the mill, the coarse powder will fall into the grinding plate again due to the change in speed, and will re-grind with the pellets; the fine powder will continue to follow the airflow. Enter the rating area to grade.
Final classification: The classification of the fine powder was carried out using a classifier having 3 to 6 rotors (a classifier installed in the upper portion of the mill). In the classification zone, the powder is subjected to centrifugal force, fluid resistance and gravity, and the powder larger than the converging point is sent back to the central hopper of the mill, and is re-grind with the new material; The fine powder of the diameter will follow the fan airflow and pass through the classification zone to become a fine powder product.
Product collection: After passing through the airflow classifier, the fine powder is immediately taken out by the airflow from the mill and collected in a pulse jet bag filter. After passing through the dust collector, a portion of the clean, high-temperature, wet air stream is discharged from the system into the atmosphere to maintain the normal circulation of the grinding system at the dew point temperature.
Product storage/transportation: The fine powder collected by the bag filter will be sent to the finished product barrel by the dense phase air transporter (or mechanical conveying system) according to its product specifications, and the packaging machine will be placed under the finished product barrel. For bagging and shipping.
|Feeding material moisture(%)