A coal mine of China National Coal Group-Scraper (This intelligent working face is a key national science and technology project in 2019)

Challenges

1. Scraper conveyors, tape conveyors, and hoists in the coal mine are the throat equipment of the enterprise, with large design margins and the problem of capacity waste;
2. The transmission system of large-scale mechanical equipment in this coal mine is realized by induction motor + mechanical variable speed method to achieve low-speed operation, with more transmission links, longer transmission chain, low transmission efficiency, and high daily maintenance cost;
3. The electrical drive technology can realize variable speed, but it can't solve the problem of low system transmission efficiency;
4. The design of coupler, reducer, coupling, etc., has a complex transmission system, high failure rate, high maintenance cost, long equipment production cycle, and high processing cost.

Implementation

The coal mine is a mega mine with an annual production capacity of 6 million tons/year of coking coal. After using the intelligent permanent magnet variable frequency speed regulation integrated system, the transportation system can record all the operating parameters of the underground transport equipment in real time, and deal with and solve all kinds of faults in the process of production in a quicker and more effective manner, so as to realize the safe, high-efficiency, and automated operation of the mine; and the system adopts the downstream startup method, which reduces the idle time of the belt conveyor. The system is based on Web, big data, sensor technology, fault diagnosis and Internet+ technology, which can realize remote online monitoring, fault alarm and fault analysis of the transportation equipment.

Configuration of working face: front and rear scraper 2×1000kW, reversed loader 700kW

Application effect

After the project is put into use, it realizes the intelligent control, high torque start, constant speed with load, speed regulation operation and other functions of the scraper conveyor and reversed loader at the working face, and the comprehensive power saving rate can reach more than 25%.

A coal mine in Shaanxi Energy - Trunk Conveyor

Challenges

1. The design of the trunk conveyor takes into account the working condition of the maximum load, the equipment margin is large, and the load of normal operation is generally lower than the rated load, resulting in low power utilization of the equipment and large power loss;
2. The original conveyor uses the high-speed motor, the soft startup device, and the reducer, which leads to low efficiency, poor effect of speed synchronization and power balance during multi-machine drive, and belt slip;
3. The coupler, reducer, coupling and other design have a complex drive system, high failure rate, high maintenance cost, long equipment production cycle, and high processing cost.

Implementation

The coal mine is a mega mine with an annual production capacity of 6 million tons/year, and the transportation system adopts an intelligent permanent magnet variable frequency speed regulation system. The trunk conveyor configuration: 4 units of TBVF-900/40YC(10000) type explosion-proof three-phase permanent magnet synchronous variable frequency motor are installed. Each motor is 10kV, 900kW, equipped with a high-voltage frequency converter. This setup ensures the efficient operation of the conveyor belt and addresses the issue of coal compression on the conveyor belt.

Application effect

After the project is put into use, it realizes intelligent control, low-speed high-torque startup, fixed-speed load, speed-regulated operation, etc., of the trunk conveyor. The trunk conveyor adjusts the output power according to the actual load size, and the comprehensive power saving rate is more than 30%.

Zhengzhou Coal (Group) Xinzheng Coal and Electricity Company's coal mine subsidiary shaft - hoist

Challenges

1. The mechanical structure is complex. The original hoist drive system mainly operated with direct current motors coupled with reducers. During the startup of the hoist, there was a significant mechanical impact, which affected the lifespan of the entire hoisting system.
2. The original hoist drive system is realized by the final output of the reducer, reducer and its lubrication system, which is prone to failure, and high in routine maintenance personnel and cost;
3. The control precision is low, and there's vibration when the system stops and applies the brake.

Implementation

This project is a new project, and the parameters of the supporting permanent magnet motor are specified as follows:

The high-power permanent magnet hoist of the mine adopts high power permanent magnet synchronous motor. Considering the on-site hoist's characteristics, which has high power, low speed, high output torque, and the large size of the permanent magnet direct drive motor, this project employs a permanent magnet semi-direct drive motor. Specifically, the permanent magnet motor comes with a planetary reducer to meet the on-site speed requirements. This permanent magnet drive system is equipped with a special high-voltage frequency converter, the overall operation is stable, the advantages are obvious.

Application effect

The high-power permanent magnet motor used in this project has the advantages of small size, small foot print, and simple mechanical structure. The motor is directly connected to the hoist drum, the reducer is eliminated, and the equipment such as the lubrication oil station is omitted, which results in fewer points of failure. The permanent magnet motor adopts soft variable frequency startup, the startup mechanical impact is smaller while realizing the function of speed regulation, effectively prolonging the service life of the equipment. In addition, the permanent magnet drive system is more efficient and has a higher power factor compared to the original drive system, thereby changing the quality of the grid.

A gold mine-mill

Challenges

1. The original mill had a long transmission chain, which easily led to phenomena such as vibrations and bearing overheating
2. The original traditional drive is equipped with the reducer, resulting in a large footprint;
3. The overall drive efficiency of the original asynchronous drive system is low;
4. The asynchronous motor has rotation error rate, large torque fluctuation, and high energy consumption.

Implementation

This project is a renovation and upgrade project. The parameters for the associated permanent magnet motor are as follows in the table:

This project is for a gold smelting company mill, and the original drive use is for asynchronous motor + reducer supporting. The original deceleration mechanism will be removed after modification. A small amount of renovation of the foundation will be performed. After the foundation renovation, the load is directly connected by the connection equipment. The new drive system combines the high efficiency of the high-voltage, low-speed and high-torque permanent magnet direct drive motor with the precise control of non-inductive vector frequency converters, and the intelligent controller displays the operating status of the permanent magnet motor in real time, i.e., the motor speed, operation, three-phase winding temperature, and front and rear bearing temperatures, thereby protecting the permanent magnet motor in real time, thus completing the intelligent monitoring and controlling of the whole set of permanent magnet drive system.

Application effect

This renovation circumvents the cumbersome maintenance of the reducer, reduce the intermediate transmission link, improve the equipment operation rate, reduce operating cost of the equipment, and has the advantages of low noise and improving the site environment; the efficiency of the permanent magnet synchronous motor reaches the primary energy consumption standards, and the overall power saving rate is about 22%.