The level of output of the vertical mill not only affects the realization of production goals, but also affects the power consumption and energy consumption, which in turn affects the cost and benefit of the enterprise. The following introduces feasible methods for improving vertical mill production capacity and saving energy and reducing consumption through repair and improvement.

1. Wear and tear of the internal structure of the mill

The internal parts of the mill that affect the output of the table are: the grinding rollers and grinding discs that directly participate in the grinding, the baffle ring that controls the material layer, and the nozzle ring that controls the direction of the hot air.

1.1 Wear of grinding rollers and grinding disc linings

From the working principle of the mill, it can be seen that the vertical mill grinds the material by applying pressure from the grinding roller. After a long time of operation, the grinding roller and the grinding disc become uneven and irregular due to wear and tear. Efficiency drops, and output drops with it.

In this case, the wear of the lining plate should be checked regularly. When the wear amount of the grinding roller approaches 25mm and the wear amount of the grinding plate approaches 10 mm, the size of the grinding roller and the grinding plate can be repaired by surfacing welding to ensure the output. , to avoid the increase of vibration caused by the wear of the lining plate, which will affect the operation safety of the main reducer. If it is found that the base metal of the grinding disc lining is damaged, the lining should be replaced in time.

1.2 Wear of the retaining ring

The function of the retaining ring is to enable the material to be fully ground on the grinding disc, and the height of the retaining ring determines the thickness of the material layer.

When the thickness of the material layer is large, the vibration of the mill will increase, and the coarse powder will enter the external circulation under the action of centrifugal force if it is not fully ground, so that the total amount of grinding will increase and reduce the output per hour. . When the retaining ring is too low, it is difficult to ensure a stable material layer thickness. Under the action of the grinding roller pressure and the self-weight of the grinding roller, there will be intermittent direct collision between the roller and the disc, causing vibration, which affects the normal operation of the production. Therefore, setting the height of the retaining ring reasonably and repairing the size of the retaining ring have a positive impact on improving the output.

1.3 Wear of the nozzle ring

The main function of the spout ring is to change the wind direction through the wind guide vanes to ensure that the airflow direction is consistent. The inclination angle, height and wear condition of the wind guide vanes all have an impact on the airflow. The size of the angle of the air deflector determines the time for the air material to reach the powder selection area from the separation, and the length of time affects the internal working conditions of the mill.

The damage of the air guide vanes will make the air volume passing through the nozzle ring not evenly distributed, unable to form a stable upward airflow, the airflow will be turbulent, the ability of the gas to carry mineral powder will be weakened, and the material will return to the grinding disc or fall into the nozzle ring. The scraping chamber at the bottom causes uneven thickness of the material layer, which increases the circulation and reduces the hourly output of the mill table. After shutdown, the damaged nozzle ring must be repaired to avoid disrupting the internal grinding cycle.

2. Addition of scraper

In order to reduce the accumulation and hardening of the material in the center of the grinding table and improve the control of the material layer by the auxiliary roller, a scraper plate is added in the center of the grinding table, with a height of 20cm from the grinding table. It can scrape the material in the center area of ​​the grinding disc, better stabilize the material layer, and ensure that the material is evenly ground; it can also effectively reduce the wear of the mill body.

3. Hydraulic system pressure

Under the condition that other factors remain unchanged, the grinding pressure is proportional to the output. The greater the grinding pressure, the greater the positive pressure acting on the material on the grinding disc, and the better the grinding effect. However, too high pressure will increase the probability of causing vibration, and the motor load will increase accordingly. Therefore, the operator should consider the setting value of the grinding pressure according to the grindability of the material, the output and fineness indicators, the thickness of the material bed and the vibration situation.

Failure of hydraulic system valves, abnormal pressure switch or internal leakage will cause the pressure to drop. The pressure value in the nitrogen cylinder and the accumulator fails to meet the requirements, which will affect the output per hour.

Use each shutdown time to check the pressure of the nitrogen cylinder to ensure that the nitrogen pressure of the piston accumulator is 8bar. Insufficient pressure will lead to increased vibration and frequent shutdown; the nitrogen pressure of the bladder accumulator is 40bar, and the pressure is insufficient. It will cause the roller to overtime and the system to respond slowly. In production, the leakage of the positive and negative pressure oil pipes of each hydraulic cylinder should also be checked, and it should be dealt with during the shutdown for maintenance.

4. Materials

The requirements of vertical mills for materials are mainly manifested in ease of grinding and particle size. The higher the hardness of the material, the longer the time for the material to be milled into a finished product, the more cycles in the mill, and the greater the wear and tear of the equipment. Moisture-containing slag accumulates and hardens on both sides of the feeding pipe, causing blockage of the feeding and feeding pipe, and the rotary feeder is frequently shut down due to overload, making the mill unable to produce normally.

A manhole is added under the rotary feeder, and a simple dredging is carried out every 4d; when the machine is stopped once every 15d, the manpower is concentrated to dredge the accumulated material in the feeding pipe, and the air cannon is used to assist in clearing the block, so as to fully guarantee the production of the mill.

5. Differential pressure

The pressure difference is composed of two parts: the pressure difference in the mill and the pressure difference in the bag collector, which is the key factor to improve product quality and output.

5.1 Pressure difference in the mill

It is mainly composed of two parts: one is the local ventilation resistance caused by the nozzle ring of the hot air entering the mill, and the other is the fluid resistance of the suspended material between the top of the nozzle ring and the pressure point. The sum of these two resistances constitutes the internal pressure of the mill Difference.

The size of the feeding amount and the amount of circulating material in the grinding chamber will cause the change of the fluid resistance in the grinding chamber, resulting in the change of the pressure difference. In order to measure pressure changes more accurately, the measuring line can be cleaned with compressed air.

5.2 Pressure difference of bag collector

It is determined by the fluid resistance of the suspended material in the bag collector. Factors such as the poppet valve, the pulse valve, the permeability of the filter bag, the flow direction of the air flow in the filter bag, and the tightness of the cover plate can change the resistance.

By repairing the damaged poppet valve, pulse valve, replacing the filter bag regularly, adjusting the position of the bag cage, repairing the damaged shell, etc., the transportation efficiency of the material in the bag collector is guaranteed and the output is increased.