Compressed air plays a vital role within
the machining, moulding and product
finishing processes at Midas
it stops producing air by going offload.
However, as the screw is still turning,
power is still being consumed. VSD
machines work differently; they adjust the
speed of the rotary screw to match the air
requirement – the faster it turns, the more
air is produced. When the air demand is
less, the unit turns slower, producing less
air, consuming less power and eliminating
offload running.”)
Anglian recommended that Midas
replace the small VSD machine with the
larger 37kW GA37VSD+ compressor and
retained the two fixed-speed compressors,
each with an output of 53 l/s, as back-ups.
The GA37VSD+ compressor is said to have
a free air delivery of 133 l/s, enough to
supply all the air that the site requires, and
thereby reducing energy consumption and
service costs.
It was also noted during the survey that
the compressed air system was running
between 9-9.9 Bar − considered to be too
high in relation to the application needs. It
was therefore recommended that system
pressure on the new VSD machine should
be reduced by 0.2 Bar increments on a
weekly basis. At 8.4 Bar, this procedure is
said to have reduced energy requirement
by 10.5%, while further reductions of the
pressure down to 7.5 Bar were not thought
CHEMICAL & PROCESS – ENERGY
to have had any adverse effects on the
performance of the production equipment.
Furthermore, Anglian Compressors
advised Midas Pattern Company of the
benefits to be derived from sectioning off
the factory so that work areas could be
shut down when they were not in use. This
is said to guarantee that no air is wasted.
The firm also recommended that the CNC
machines were pre-programmed to shut
off the swarf removal air blast once the
process was completed. Midas designed
this system of controllers, solenoids and
pipework, and then retrofitted it to each of
their seven CNC machines to ensure that
when the programme finished running, no
further air was consumed.
RESULTS
The combined effect of these measures,
following the introduction of the VSD+
compressor, has reportedly seen
nighttime usage drop from 10-35 l/s
down to 5-20 l/s. Daytime usage is also
said to have been lowered, as workers are
now aware that they should switch off
equipment when not in use. In addition,
the amount of energy used on site for
generating compressed air has also
reportedly been reduced by around twothirds
to just 78,104 kWh, representing
a total saving of £14,554 per year, which
means that the estimated ROI (return on
investment) payback is 1.5 years.
The compressed air system upgrade
Anglian Compressors conducted a
survey of the compressed air system
alone has also reduced the company’s
carbon footprint by some 50 tonnes of
CO2. When combined with the effect of
the other measures that the company has
taken in using less energy and improving
its green credentials across its business,
that figure is said to be closer to 60
tonnes.
MD Rance says: “Midas has achieved
its success by inventing, developing and
implementing techniques analogous to
metal casting. We are, in effect, a plastic
foundry that has invested in cuttingedge
technology while maintaining and
cherishing traditional expertise. We
have always applied this approach with
our equipment suppliers too. It wasn’t
just a question of price; their product
offering had to be the best in terms of
quality, performance, and longevity. But
now, with the Midas Green Initiative, we
see environmental responsibility as the
foremost criterion.
“I am a passionate environmental
advocate, and this is reflected in every
aspect of the company’s climateconscious
ethos. It is self-evident from
the 100% LED lighting throughout the
plant, and our zero-landfill waste output.
“Up until recently the plant heating has
been achieved with 10% biogas and 90%
carbon-neutral gas. Now, I am delighted
to report that we have signed up a threeyear
supply contract for 100% biogas.
That means every unit of gas we burn is
replaced by a 100% truly green one.
“What’s more, our staff and customers
are encouraged to go electric with their
vehicles and use our two free EV charging
points on-site and, as a responsible
plastics manufacturer, we have expressly
excluded all forms of single-use plastics
from our premises.”
Rance concludes: “Midas Pattern
Company, Anglian Compressors and Atlas
Copco share the same green principles
and a common purpose. They were one
hundred percent with me all the way.”
Autumn 2020 www.operationsengineer.org.uk 31
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