PROJECT
INCORPORATING COLD CHAIN
SYSTEM DESCRIPTION
The refrigeration areas consisted of the
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following main systems:
• -4.5°C chiller system
• +2°C chiller system
• +8°C chiller system
• Compressor plant
• Condenser plant.
-4.5°C chiller system
The chiller comprised an ammonia
accumulator vessel, which fed ammonia
to two 2 200kWR thermosiphon plate heat
exchangers (PHE), which cooled the glycol
returned from the process users at -0.5°C to
the required supply temperature of -4.5°C.
The reticulation of the glycol through the
system was done by three pump sets:
one to pump through the chiller and two
pump sets to pump the chilled glycol
to the various process users such as the
fermentation vessels and filtration chiller.
+2°C chiller system
The +2°C chiller system was made up of a
cascade system consisting of three chillers
in series, which cooled the glycol returned
from the process users at +25°C to the
required supply temperature of +2°C. The
chiller stages were as follows:
was used to trim the remaining load. This
allows for the system to run at the highest
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possible COP during Wort cooling.
Stage 1: +25°C to 18°C 900kWR
Stage 2: +18°C to 8°C 1 100kWR
Stage 3: +8°C to +2°C 1 450kWR
+8°C chiller system
The chiller consisted of an ammonia
accumulator vessel, which fed ammonia
to a single 1 400kWR thermosiphon plate
Each chiller consisted of single
thermosiphon PHE fed from their own
accumulator vessel. A single pump set
was used to pump the glycol through the
three chillers and to the process users. The
first two stages were used to chill the bulk
heat exchangers that cooled the water
returned from the process users at 15°C to
the required supply temperature of 8°C.
A single pump set was used to pump the
chilled water through the chiller and to the
HVAC users.
of the load at the higher coefficient of
performance (COP), while the last stage
This brewery was built
with an initial capacity
of 3.2MHL/annum, with
a plan to expand the
capacity to 6.4MHL/
annum in future, making
this brewery the largest
brewery in Africa outside
of South Africa.
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Compressor plant
The compressor plant consisted of nine
ammonia screw compressors (all Grasso
models) as well as one small reciprocating
compressor installed as a pump down
compressor.
Each of the screw compressors was
cooled by means of thermosiphon oil
coolers, which were fed off a priority
feed from the condensers. The screw
compressor motors were all fitted with a
variable speed drive which, together with
the compressor unloading mechanism, 1. +8°C chillers as well as accumulator vessel and pumpset.
maintained the suction pressure of their 2. 4.4MWR, -4.5°C chiller, and accumulator vessel.
respective accumulator vessels. 3. Pumpset for the reticulation of chilled water to users.
COLD LINK AFRICA • January/February 2019
www.coldlinkafrica.co.za
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