Cold Link Africa January / February 2020 | Page 13

PROJECT
INCORPORATING COLD CHAIN
conveyer to stores around the country.
This was critical as the lease for the
old factory had been cancelled and
production had to continue to supply all
the stores around town.
The cold room chiller that chills the filling.
minutes to get the room on temperature,
then starts to unload to a point where
it cycles between three and four
compressors for the rest of the day, the
Carel control system alternates between
the compressors to keep run hours equal
across the units.
MANUFACTURER LINE
The pie manufacture line came in from
Switzerland. This line is absolutely state of
The racks in the cooling facility cool the pies in 60 minutes. Once
loaded, the pies move in a spiral motion to the top of the rack and
are fed off onto a conveyor belt.
the art with fitted with VSD and PLCs. The
system can produce 8 000 pies per hour
on certain lines out of a footprint area of
roughly 150m². The only manufacturing
process not handled by the automated
pie line machine is the cooking of the
fillings which still happens via good
old-fashioned love and care with the
chefs mixing up ingredients in automatic
cookers and cooking batches and mixing
them by hand.
The pies flow off the automated pie
line directly into the spiral freezer and
out to the packing area, where a team
of packers slot the pies into boxes
and straight into holding freezers and
delivery trucks.
SYSTEM IMPACT
The difference in power draw on this
system from a traditional simplex design
would be roughly 30% in terms of electrical
The spiral freezer is cooled by a Multiplex
Refrigeration plant with five Large GEA
compressors being cooled by an Evapco
water-cooled condenser. The Multiplex
mechanics and electrics were designed
and assembled by Lutz Refrigeration with a
design very similar to an ammonia system
design with the distinction, however, of
low-charge direct expansion freon gas
to the stainless-steel cooling coil. The
cooling system can provide up 230kW of
cooling in a -34°C room. The advantage
for pie city in going with such a large freon
system, was a much easier set-up in term
of regulation, lower capital cost, lower
maintenance cost and with the water-
cooled design, energy usage was brought
in line with ammonia efficiency.
The Blast freezer runs as low as -35°C,
but in operation it was found that the best
setting was closer to -30°C to trim energy
usage, allowing an entire compressor
to switch off. At these temperatures, the
plant cycles between three and four
compressors out of five. This also keeps the
compressors running more comfortably
within their design envelope at suction
pressures of -38°C and discharge of 35°C,
equating to a coefficient of performance
of 1.5. For every 1kW electricity used, there
is effectively 1.5kW cooling – equivalent to
a comparative water-cooled ammonia
system at these temperatures.
This blast spiral freezer can draw up
to as much as 150kVA when running flat
out. However, being a multiplex design, it
runs hard when switched on for the first 15
SYSTEM OPERATION
Cooling tower being craned in.
COLD LINK AFRICA •
January/February 2020
www.coldlinkafrica.co.za
13