More than £25,000 in energy costs
per year is being saved by Express
Asphalt in Darwen following the
fitting of ABB variable speed drives.

Steam and dust from the aggregate
drying is extracted by an exhaust fan.

This 90kW fan, running at full speed
with output damped, wasted energy.

Beta Power supplied a 110kW
ABB standard drive for the fan. This
had its damper in the fully open
position and the dryer pressure was
controlled via a pressure transmitter
feeding a signal back to the drive.

Invertech Solutions installed a
30kW ABB drive to the dryer. The
burner supplying heat to the dryer
uses kerosene and it was found that
running the drive at 55Hz gives the
optimum drum rotation speed.

Express Asphalt now uses 0.5L/t less
of kerosene, saving £8000 per annum
in burner fuel costs.When not drying
aggregate, the drive ramps down to a
low speed. This led to savings of
£500 a month on electricity to run
the exhaust fan.With other ABB VSDs
fitted and other energy saving
components, the plant is saving £1500
a month on its energy costs, in
addition to the £600 a month
reduction in burner costs.