Meiden inverters used at Fluorospar plant

Edited by the Engineeringtalk editorial team Mar 22, 2000

By employing the latest drive technology at its Ellesmere Port 'Fluorospar' drying plant, Colin Stewart Minchem has enhanced operating efficiency and reduced initial capital investment.

By employing the latest drive technology at its Ellesmere Port 'Fluorospar' drying plant, Colin Stewart Minchem has enhanced operating efficiency and reduced initial capital investment.

The two production lines, recently commissioned at the site to supply ICI's Rocksavage works, use Meiden Inverter technology coupled with Mitsubishi A1SH Plcs to reduce start-up and operating costs at the plant.

Employed for driving an Atritor's rotating discs that disperse damp mineral into a hot air flow plus the fan pushing the heated air into the chamber, the Meiden drives provide a combination of closed loop variable speed control, long duration ramp up/down times, high initial torque control and power factor correction that together ensure optimum operating efficiency.

These features also permit standard AC squirrel cage motors to be used where larger, more expensive slip-ring motors were used previously.

At an older plant built in the late eighties, Colin Stewart Minchem used slip ring motors to solve the high initial torque demands and various belt and pulley configurations for different ratio outputs.

With the Meiden drive solution, engineered by Agut Control Gear of Blackburn, operating routines are programmed into the units to handle the torque demands and changing product throughput.

Further, linked to sensors, the drives are able to vary running status to match conditions.

For example, on start-up the air pushed into the chamber is cold.

This calls for a higher energy input than when the air is heated.

Sensors monitor the temperature and feed data to the drives that respond by adjusting power input accordingly.

Previously airflow was damped to reduce loading on the fan.

Software for this operation, as for the system's other functions, was written by Agut Control Gear.

Meiden's VT210S drive is used for both the fan (75kW) and the rotating discs (55kW).

Initial load for the fan is 500 Nm, with air being delivered at 12,000ft3/min, and the drive being programmed to provide a controlled ramp on start-up.

The Atritor disc loading is 461 Nm, but during the process is subject to shock loading, which the Inverter controls via the regeneration control unit.

Once the plant is at the correct running temperature, the drives moderate power demands to match running conditions therefore reducing power consumption.

On shut down, the drives again give controlled ramp rates with the regenerated power being dissipated through the braking units and resistor banks.

"Today's more affordable prices for drives combined with their simple operation and versatility, have made the use of Meiden's drives in the co-ordinated package put together by Agut Controls, a practical and cost effective control solution", commented Peter Kitching, Colin Stewart Minchem's consultant.

Meiden drives are also used on the on the variable feed conveyor system delivering the damp calcium fluoride to the drying chamber.

Here, again, the drives respond to data from sensors monitoring material throughput.

The whole project was designed and built around a very tight 4 week delivery schedule, with this being achieved through Meiden's policy for 'Off the shelf ' availability and Agut Control Gear's professional design and build team.