Coal Processing Plant – Australia
Project Background:
Our client is a well-known coal processing plant located in a high-demand industrial area, specializing in grinding coal for power generation and various manufacturing processes. The coal mill in the plant is a key component to ensure efficient production. The company currently has two 200MW units with angle-type pulverized coal burners, equipped with 6 fan coal mills (4 in operation and 2 in standby), and the motor power of the coal mill is 800KW.
The company often found cage fractures during routine maintenance of coal mill motors. Later, after careful investigation, it was found that due to the heavy impeller (23T), large inertia, large starting torque, large current (450-700A), and long starting speed ramp time (60S), during the startup, the motor cage bars flowed a large induction current and heated up quickly, breaking under the shear force of the starting torque and the heating stress of the cleaning rod. Over the years, the existing mechanical couplings continued to have operational problems, which eventually led to expensive downtime and excessive maintenance. The customer approached us, hoping that we could find a more reliable and efficient solution to these ongoing challenges and help them optimize their operations.
Problem Points:
Due to the high power of the motor, the weight of the impeller, the high starting torque and the low speed, many couplings could not provide a solution that could fundamentally solve the problem.
Always downtime: The traditional couplings commonly used in coal mills are constantly under high stress due to the high power requirements of grinding coal. As a result, they require constant attention and repair. Our customers shared their frustration with us: “We are often downtime because the couplings cannot withstand the intense wear. Our maintenance costs are rising and we can’t afford to waste any more time.”
Inefficient torque transmission: Due to mechanical contact, energy is lost in the form of heat and friction in the coupling. This not only affects the energy efficiency of the coal mill, but also causes power losses, which means that the system needs to work harder to achieve the same output. The customer pointed out: “We are wasting energy”
Vibration and noise: Mechanical couplings cannot handle fluctuations in load and speed, causing mechanical vibrations to reverberate throughout the workshop. This not only causes discomfort in the workplace, but also accelerates the wear of critical components. In order to reduce the impact of occupational illness on operators, it was clear that something had to change.
High Temperature Operation: High temperatures are generated during coal grinding, and the previous couplings were not designed to operate in such extreme conditions. This resulted in gradual material degradation, which ultimately affected the performance and life of the couplings.
Solution:
After understanding the customer’s challenges, we planned to perform a soft start modification on a coal mill, using a composite three-disk magnetic coupling to replace the original rigid nylon pin coupling. Combined with the existing installation space, the outer diameter of the magnetic coupling was designed, the foundation remained unchanged, the motor position remained unchanged, and a permanent magnetic coupling was installed between the motor and the coal mill bearing box to achieve light load starting of the motor.
Specifications and Features:
Three-disk Permanent Magnet Coupling is a contactless coupling system that utilizes permanent magnets to transfer torque. By replacing mechanical components with strong magnetic fields, we are able to provide the following specifications based on customer needs:
- Magnet Type: We selected high magnetic strength Neodymium Iron Boron (NdFeB) magnets for the coupling’s drive and driven discs. To handle the high torque requirements of coal mill operations.
- Temperature Rating: The coupling is specifically designed with AH series high grade NdFeB neodymium magnets to withstand high temperature coal mill environments up to 230°C.
- Dimensions and Customization: Based on the customer’s existing power plant and operating space, we designed a coupling that fits perfectly into the existing mechanical setup, ensuring seamless integration.
- Housing Material: Using high strength and corrosion resistant cold rolled steel ensures the coupling can withstand harsh operating conditions for a long time.
- Seals and Barriers: We also use advanced seals to prevent leakage, thus solving the contamination issues that plagued previous couplings.
Result Summary:
By replacing the traditional mechanical coupling with the Three-disk Permanent Magnet Coupling, the customer’s coal milling operations have improved significantly. From increased efficiency to significant cost savings, the magnetic coupling has proven to be a very effective solution. As our customer concluded: “Switching to magnetic couplings was one of the best decisions we have ever made.”
Ultimately, with our strong R&D capabilities and advanced production capabilities, we finally solved the company’s long-standing problem of broken coal mill cages.
