Energy-saving application of Sunwoele high-power VFD (Variable-frequency Drive) on belt conveyors

Abstract: When transporting ore from the mine to the production plant, as long as there is a certain height difference and a certain potential energy, VFD (Variable-frequency Drive) can be used to excite the motor to generate electricity. VFD (Variable-frequency Drive) is a regenerative energy transmission system. , which can feed regenerative energy back to the grid. The general situation is that it is transported continuously 24 hours a day, the amount of ore transported is large, the motor generates a large amount of electricity, and there is a lot of electrical energy feedback. Judging from the current situation of China's domestic mines, large-tonnage mining trucks are basically used to transport ore from the mountain to the mountain. This not only wastes oil, pollutes the environment, but also takes up a lot of cultivated land. It is a pity. . Using a VFD (Variable-frequency Drive) driven belt conveyor with a generator to transport ore can recover a large amount of electrical energy, reduce production costs, and enhance the competitiveness of enterprises. This method is of great significance and is worth promoting.

I. Overview

In the new dry process cement production line, the limestone raw material mine is located on the mountain several kilometers away in a straight line. The traditional transportation method uses large-tonnage mining trucks to transport ore from the mountain to the mountain. In order to ensure the normal production, a road must be built for the mining trucks to travel. As long as the cement production line does not stop, Mine carts must continuously transport limestone from the mountain to the bottom. This road should be able to withstand the crushing of large-tonnage mining trucks. Its length is more than several kilometers and covers a large area. The investment is naturally large, and a lot of fuel is consumed during transportation. In addition, considering the equipment and road conditions, Maintenance and operating costs are high, and cement production costs increase, which is not conducive to market competition. In order to reduce production costs, it is considered that during the transportation of limestone from the mountain to the bottom, the potential energy is continuously reduced. By utilizing the potential energy of the limestone itself, the limestone can be safely transported from the mountain to the bottom of the mountain without consuming other energy or consuming very little electrical energy. Belt conveyors are now used more often. The belt conveyor described in this article not only serves as a tool for transporting limestone, but also uses potential energy to generate electricity. The energy-saving efficiency is not trivial, and reducing the power consumption of cement production is of great significance.

2. Belt conveyor

Belt conveyor is mainly composed of steel wire rope core belt, roller, roller, intermediate frame and support pusher. It is widely used in various industries such as mining, metallurgy, coal, port, power station, building materials, chemical industry, light industry, petroleum and so on. It is used to transport loose materials or finished items. According to the requirements of the transportation process, it can be transported by a single unit, or it can be composed of multiple units or combined with other conveying equipment to form a horizontal or inclined conveying system to meet the needs of different layouts of operating lines. The belt conveyor has the characteristics of simple structure, standardized components, convenient maintenance, large conveying capacity, simple operation and maintenance, low operating cost, and wide application range. The long-distance belt conveyor is a large-capacity conveying equipment. It has the characteristics of continuous and reliable conveying, high degree of automation, small equipment maintenance workload, networked and unified management with the factory general control system, and the conveying lines are arranged according to the terrain and occupy less cultivated land. ; At the same time, the materials are relatively stable during transportation, with few dust points and little environmental pollution.

A cement company has two 500t/d dry process cement production lines. The limestone raw materials are transported by long-distance curved belt conveyors with a transportation capacity of 1800t/h. The horizontal distance from the crushing station to the factory silo is about 5451m; the mining crushing station The floor elevation of the tipping platform is approximately 680m, the elevation of the belt feeder outlet of the crushing station is approximately 662m, the floor elevation of the cement plant at the conveyor end point of the belt conveyor is 290m, the elevation of the unloading point at the conveyor head is 310m, and the conveyor lowering height is approximately -352m. .

The above data shows that 1800t of limestone was transported 352m in 1 hour. From this, the kinetic energy generated by the change in potential energy of the downward movement of the material can be calculated (ignoring frictional resistance):

W=mgh=1800×1000×9.8×352=6209280 (kilojoules)

Assuming that all the kinetic energy is converted into electrical energy through the generator, the adapted motor power is:

P=W/t=1800×1000×9.8×352/3600=1724.8 (kW)

3. Belt conveyor control scheme

1. Technical parameters of belt conveyor

Belt conveyor transport capacity: 1800t/h

Belt conveyor horizontal projection length: 5451m

Maximum lifting height of belt conveyor: -352m