Since the ball mill is a large-scale equipment, the power consumption is very large. Therefore, with the development of the social economy and the expansion of the production scale of the enterprise, the drawbacks of the direct industrial ball mill have been exposed, and the rapid development of various industrial enterprises has been seriously hindered. This prompted people to study the ball mill energy-saving program - ball mill frequency control energy-saving control system.
First, the working principle of the ball mill:
In cement, ceramics, metallurgy companies, the mill due to the relatively large power, accounting for more than 80% of the total electricity consumption of the enterprise, the basic structure of all kinds of ball mill about the same, but some of their components are different. Ball mills generally consist of a cylinder, a liner, a feeder, a discharger, an air shaft, a bearing, a transmission, and a lubrication system. The circular cylinder is welded by several steel plates, and the two ends are welded with the French blue, so as to connect the discharge end cover of the cast steel end cover, and the liner is provided with a replaceable liner, in order to make the liner and the cylinder The inner wall is in close contact with and buffers the impact of the steel ball on the cylinder, and a plywood is placed between the lining plate and the cylinder. In order to facilitate the replacement of the lining and checking the internal condition of the cylinder, an inlet hole is formed in the cylinder, and the inlet hole is Rectangular, generally 350 to 550 mm in length. The feeding part is composed of an end cap combined with a hollow journal, a fan-shaped lining, and a journal inner sleeve. The hollow journal inner sleeve prevents the inner surface of the journal from being worn by the feed, and the inner surface of the inner sleeve With a spiral to help feed.
Second, the inevitability of energy-saving transformation of ball mill
The ball mill belongs to the low-speed heavy-duty equipment. It has a large load and a large starting moment. It is generally necessary to install a hydraulic coupler to complete the start-up and speed regulation of the drive system. Cement, ceramics, and metallurgical ball mills are usually started with an additional starter motor shock start or soft start device, which has a large impact on the power grid and reduces the required torque when the start is completed, so there is a lot of room for energy conservation. The driving methods currently widely used are: three-phase AC motor-hydraulic coupler-gear reducer-belt reducer. Since the ball mill is a constant torque load, when the speed is adjusted by the hydraulic coupler, the speed regulation efficiency is equal to the speed ratio, and a large part of the energy is wasted in the fluid coupler.
Ball mills are typically operated at a fixed speed, and the barrel speed is determined by the pulley or gear reduction mechanism (which also has a fluid coupling). The rotation speed of the ball mill directly affects the movement condition of the steel ball and the material and the grinding process of the material, and the movement of the steel ball and the material in the cylinder at different rotation speeds. When the rotation speed is low, the steel ball and the material rise with the inner wall of the cylinder. When the inclination angle of the steel ball and the material is equal to or greater than the natural inclination angle, the steel ball slides down along the inclined surface, and a sufficient drop cannot be formed, and the grinding effect of the steel ball on the material is small. The efficiency of the ball mill is very low. When the rotation speed of the cylinder is at a certain rotation speed between the two, the steel ball is brought to a certain height and then falls along the parabola, and the impact on the bottom material is the largest, and the grinding efficiency is the highest. Good working speed. If the rotation speed of the cylinder is high, due to the centrifugal force, the material and the steel ball are no longer separated from the cylinder wall, and rotate together with the steel ball, and the steel ball has no impact on the material, and the grinding efficiency is very low. The lowest speed of the state is called the critical speed.
Third, the modified ball mill system should meet the following requirements:
1. The modified ball mill should have enough starting torque to meet the requirements of large load of the ball mill, and ensure that the equipment runs smoothly under the variable frequency operation state to ensure the motor has constant power characteristics;
2. Use the variable frequency speed control system to modify the normal operation of the original ball mill at low speed, ensure normal process control requirements, extend the service life of the ball mill and motor, and reduce maintenance.
3. Prevent excessive grinding of materials, reduce grinding cycle, improve grinding efficiency, and reduce power consumption per unit.
Fourth, the conclusion of the transformation
The modified ball mill can realize automatic control, as well as mains/power saving switching function, and can overcome the rebound voltage caused by the large inertia of the ball mill, effectively ensuring the normal operation of the ball mill. Since the starting current of the ball mill is greatly reduced, the impact on the power grid and the voltage drop of the power grid are not caused, and the switching or malfunction of other electric equipment caused by the start of the ball mill is eliminated. Under the same grid capacity, the number of installed units can be increased, and the built-in current feedback system can automatically operate. The ball mill can be easily set by grinding frequency, grinding time and automatic stop function, making the operation more intelligent and user-friendly.
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