Large Rotating Machines

Solid Energy
New Rotary Breaker at Coal Handling Plant
6 months

The Rotowaro coal field is located 15mins west of Huntly and provides quality coal to the Genesis Huntly Power Station via an extensive conveyor belt system.

The coal is firstly mined in the Rotowaro open cast mine before being transported by large dump truck to the coal handling plant. The truck then empties its coal load into a vertical chute which in turn feeds the rotary breaker.

A rotary breaker consists of a large steel drum (similar to a concrete mixer) where the large pieces of coal rotate internally and smash into other pieces of coal and therefore gradually break into smaller and smaller pieces.
The steel drum has large holes in the side so that small pieces only of coal can fall through onto the conveyor belt underneath and away to the graded coal stockpiles.

The existing site rotary breaker was too small for the product throughput required and larger pieces of coal were jamming the system. Therefore Solid Energy decided to install a much larger rotary breaker with a 110KW drive motor/gearbox delivering more torque than the existing motor.

Our engineering team in association with Dobbie Engineers Ltd helped design and build a control solution that would safely ramp the motor up to full speed in a short time frame even if the rotary breaker was already full of coal.

At all times the control system is monitored via SCADA by operators in the coal grading area control station.

Work carried out included:

  • Install VSD cabinet including line chokes and 130KW variable speed drive.
  • Install self regulating ventilation system to top of vsd panel to remove unwanted heat buildup.
  • Provide and install 230metre length of specially manufactured VSD cable from MCC to motor position via tower and overhead bridges.
  • Modify existing control circuits on PLC equipment for new system automation process.
  • Design and install rotation detection system detect when large rocks or tree stumps jam rotary breaker.
  • Provide full software design to implement changes to existing PLC programs and SCADA.
  • Commission installation and assist client’s automation engineers.
  • Ongoing maintenance and breakdown support.

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