Independent thesis Advanced level (professional degree), 20 credits / 30 HE credits
The project was performed at Siemens
Industry Drive Technologies with the
objective to provide actual values for
the energy savings potential within
Siemens scope of practice.
In Sweden the electrical drives stand
for about 30 % of the total electricity
consumption and about 60 % of the
electricity consumption within the
industry. During the pre-study phase
electrical drives with pump applications
were identified as large energy users.
Because of this a case study at one of
Siemens customers, Stora Enso Fors was
performed. The system that was evaluated
during the case study was a throttled
system with a centrifugal pump for
The results yielded that a saving of
over 50 % could be achieved by replacing
the throttle valve with a variable speed
drive, a frequency converter. The
payback period was two years and two
months and the present value for the
total life cycle cost of the variable
speed system was 662.566 SEK lower than
for the throttled system. As a
consequence, Stora Enso Fors is advised
to invest in a frequency converter for
regulation of the system.
The general conclusion is that a focus
on system efficiency is the most
important factor in energy efficiency
projects and that the system regulation
method has a large impact on the overall
system losses and hence its efficiency.
Energy efficiency potential for
throttled systems with centrifugal pumps
is large and significant economical
savings can be made through investments
with short payback time.
2013. , 48 p.