PROJECT
INCORPORATING COLD CHAIN
Each Mycom compressor is fitted with a variable speed drive to minimise
energy usage by closely matching cooling capacity to the demand.
To conserve energy and reduce
environmental impact, the compressors
are equipped with soft starters and variable
speed drivers (VSDs). Condensate water
from the pod evaporators is harvested and
used as make-up water for the evaporative
condensers. The steel roof structure has
been strengthened to accommodate
solar panels at a later stage for power
generation. “In considering the high capital
cost and maintenance requirement, we
opted not to install a standby generator,”
said Rautenbach. “Instead, we have
provided a connection for a mobile
generator and have a contract with a
service provider who can have a generator
on site within hours. In the event of a total
power failure, if we limit door opening, we
can maintain temperatures up to 48 hours
or until the mobile generator is connected.”
NATURAL REFRIGERANT AMMONIA
The two-stage ammonia refrigeration
plant has two circuits: -35°C and -10°C.
“For energy conservation and maximum
match between cooling capacity and
demand, we opted for four Mycom 8M
reciprocating compressors, all fitted with
VSD. One is dedicated to high stage, one
to the low stage, and two are piped as
swing machines.”
Each room has four BAC stainless
steel evaporators mounted in pods, with
hydraulically operated flaps to maximise
the defrosting cycle. The stainless steel
coils, because of lower mass, are easier
to handle and require less strength in the
roof structure. All the condenser fans are
also fitted with VSD and can increase or
decrease in speed in response to the heat
of rejection requirements.
“A Hansen automatic air purger
has further reduced energy usage by
purging non-condensables that increase
head pressures,” said Dennis van der
Westhuizen of MRE.
The refrigeration contractor started on site
on 1 August 2016 and by 1 February 2017, all
All ammonia valve stations have dual circuits for the chambers to operate at -25°C or
at chill temperatures of 2°C for the storage of fresh produce or other chilled products.
The mobile racking has 8 500 hi-cubed spaces for the storage of drums. In total, iDube
has capacity to handle 12 000 tonnes of product on racking certified to carry a
maximum of 1.4 tonne per pallet.
The coloured outside cold store panels facing the main road is a striking landmark. Also seen are the insulated pods that house the
six ammonia evaporators.
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www.coldlinkafrica.co.za
COLD LINK AFRICA • November | December 2017