A power plant of Xingjiang State Energy - Mill

Challenges

The original coal mill adopts the drive mode of "lubrication oil station + reducer + motor", which has a complex structure;

Using a reducer result in high investment and maintenance costs, as well as a high failure rate;

The overall drive efficiency is low, and power consumption is high;

The equipment has a high surplus coefficient, making its operation uneconomical

In case of long use, the equipment vibrates a lot, which affects the service life of the motor;

The equipment's return-to-factory maintenance duration is long (around 50 days), severely affecting production operations.

Implementation

This project is the technical transformation project of a power plant. The original asynchronous motor and reducer of the coal mill are removed, and the permanent magnet intelligent drive system, which provides the power for the drive and carries the weight from the mill, is installed directly at the original location of the reducer. The system adopts the high-efficiency permanent magnet motor, with a high-power factor of more than 0.95. The intrinsic rated efficiency of the motor can reach more than 96%, by eliminating the reducer structure and shortening the transmission chain, efficiency is enhanced on two fronts.

At the same time, the motor operates at low speed, resulting in minimal mechanical frictional losses and reduced system maintenance. Under continuous operation conditions, equipment vibration is reduced, extending the motor's lifespan. Increased power density and more economical operation can be realized for the same power.

Application effect

After the renovation with vertical coal mill permanent magnet intelligent drive system, the power factor is improved to more than 0.97, the energy saving rate is about 42% for 40% load, 43% for 60% load, and 30% for 80% load, and the average energy saving rate reaches more than 40%.

The power saving of a single unit is about 1932840 kW.h/year, the standard coal saving is about 608 tons/year, and the CO₂ emission reduction is about 1927 tons/year. Due to the reduction of rotation speed and the simplification of the reducer structure, the maintenance workload can be significantly reduced, saving approximately 1.047 million CNY annually.

A domestic power plant-air-cooled island

Challenges

1. The use of reducer causes high failure rate, and high maintenance cost;
2. Low overall drive efficiency and high power consumption;
3. The equipment is configured with a high surplus factor, making its operation uneconomical；
4. Under extended periods of use, the equipment experiences significant vibrations, which affects the lifespan of the motor.

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 an old-to-new project involving a large coal-fired power plant in Shaanxi. The unit has been running for about 10 years, and the original transmission uses the asynchronous motor + reducer drive mode. The site inspection reveals that the requirements of present renovation are met.

The air-cooled island fan direct drive drive system consists of a low-speed and large-torque permanent magnet synchronous motor and a special variable frequency control system. The low-speed permanent magnet synchronous motor drives the fan directly, eliminating the intermediate reducer. The on-site installation is simple. After dismantling the original drive system, a bracket is installed at the original location of gearbox, and the permanent magnet motor is fixed to the bracket to complete the overall installation.

TYVF-110-85YC (380) permanent magnet motor is used at the site of the air-cooled island of the power plant, replacing the original motor.

Application effect

The permanent magnet motor is designed to directly drive the fan by low speed and high torque, removing the gearbox and combining it with the variable frequency speed regulation technology. Not only the power loss of the transmission chain is reduced, but also the operation efficiency of the motor is improved, and the comprehensive power saving rate is about 17% compared with the previous drive structure.