TI Automotive of Flint in North Wales makes 180,000 high density polyethylene (HDPE) moulded plastic fuel tanks a year for vehicles. As part of a group wide initiative to cut energy bills, they considered installing ABB Drives to see where energy use could be reduced.

Three applications running 24/7 were initially selected: a 75kw air compressor motor; an 11kW chiller pump, and a 132kW granulator used for recycling scrap plastic.

The fuel tanks are produced by blow moulding, and the plant uses a large amount of compressed air. A 75 kW ABB inverter drive was installed to an air compressor that had previously been running at a fixed speed.  By running the motor at half speed, the ABB drive reduced consumption from 75 kW to 45 kW, giving a saving of around 35 percent.

The second application was the pumps used on a chilled water circuit needed to cool the mould tools, extruder feed zones and gearboxes, and the mould hydraulics and electrical panels. Installing 11 kW ABB inverter drives on the three pumps produced a 30 percent saving, reducing consumption from 11 kW to 7 kW.

The third application was the granulator, which chops up waste HDPE trimmed from the finished fuel tanks for reuse in the blow moulders. Although running 27/7, the granulator is only working for 10 seconds a minute.  For the other 50 seconds, the motor is still running at full speed but under no load.

12 month payback  time

A 132 kW ABB inverter drive with flux optimisation was used to detect the torque demand and ramp up the torque when chopping material. Running the granulator motor a constant fixed speed reduced the motor power consumption from 42 kW to only 15 kW, a saving of 27 kW.  This 65 per cent reduction and gave a payback period of one year.

Overall, the plant is saving around £2,000 a month on its energy bill; some 10 per cent of its total plant energy expenditure.

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