Time to belt up and save energy
January 1st 2008
A factory's plan to save energy by upgrading from vbelts
to timing belts on air handling drives has been
expanded to include a wide range of automation
equipment. This has cut €140,000 from the annual
energy bill, improved the working environment and
suggested further savings
Stryker Orthopaedics manufacture a
range of orthopaedic implants, bone
cements and bone substitute
materials at it's facility in Limerick, Ireland.
Like many other companies it has become
increasingly aware of energy cost
increases and has undertaken several
initiatives to reduce energy usage/costs
and to protect the environment.
Maintenance manager Robert McKillican
calculated that changing from v-belts to
timing belts would reduce energy
consumption by about 10% and called in
Michael Dineen of Dickson Bearings to
discuss the idea.
It was soon realised that slippage of the
v-belts gave a soft starting effect, which
would be lost with a toothed belt. The two
briefly considered the use of electronic soft
starts, but soon decided that variable
speed drives would be better because
they could be used to tune the air
handling to exactly match demand.
The plant's eight extraction fans all
worked quite hard to ensure complete
extraction of dust particles. Initial
calculations suggested that significant
energy savings could be made if each
were tuned to exact local demand, rather
than run faster than necessary.
Additionally, staff numbers and production
levels vary during Stryker's two-shift day so
there was potential to further slow down
the air handling at different times
throughout the shifts.
There were a number of practical issues
to be addressed, not least which drive to
use. Michael recommended the L300P
Series from Hitachi, three at 55kW and five
at 37kW, which are suitable for fan drive
applications.
Meanwhile Robert was unearthing some
practical considerations. The control
panels, for instance, had to be designed to
fit into a small control room. As they would
be close to some sensitive equipment,
chokes would be required on every input
and output to minimise noise generation
and harmonics onto the mains. With the
Hitachi drives it was also possible to set a
maximum total output, so that penalty
charges from the electricity supplier could
be avoided. A PLC would be required to
control the system, and it seemed logical
to stick with Hitachi and use an EH150
series. This communicates with the plant's
existing building management system to
make the whole installation interactive.
Finally it was realised that security staff
as well as control engineers would need
access to the system. Therefore it was
decided to install two touch screen HMIs,
again Hitachi, one in the control room the
other in the security office, and to use
clear graphical displays to make use as
intuitive as possible.
Within days of completing the
installation, energy meters strategically
located around the system were
confirming that considerable savings were
being made. No detrimental effect on
machine performance or other production
compromises were identified. Initially the
drives were configured to give the fans
three set speeds, but the intention is to
upgrade this with PID pressure sensor
feedback so that load matching becomes
exact.
"For many years we were able to ignore
energy issues, but once we started
monitoring usage our attitude changed
completely," says Robert McKillican.
"This is now filtering out to the whole
workforce. The lesson is that monitoring
energy consumption leads to a constant
drive for more savings." More articles from Silverteam Ltd: | 
