Cold Link Africa Cold Link AfricaOctober 2018_digital | Page 27

PROJECT
INCORPORATING COLD CHAIN
1
3
4
achieved with the help of three solenoid
valves. The control system provides
for all capacity steps on each of the
compressors. MRE also included the initial
charge of oil for the compressors, one
commissioning oil filter, plus one spare filter
— as per the consultant’s specification.
These compressors require a water
cooling circuit to cater for 5kW of heat
rejection from the oil cooler and 14.3kW
head cooling on each compressor. The
cooling water circuit was designed to
operate at a compressor inlet water
condition of 35°C and an outlet water
condition of 45°C.
CONDENSERS
Two Evapco condensers were installed to
meet the heat rejection of the refrigeration
plant at the GoChill facility. Both condensers
were supplied with a split coil for compressor
cooling water.
Each condenser can accommodate
the full water cooling load from three
running compressors. Both condensers
were placed on concrete plinths with
2
galvanised supports on top and pipe
supports around the condensers.
The condensers were supplied with one
7.5kW and one 4kW fan motor. The water
pump has a 5.5kW motor.
AMMONIA PUMPS
MRE also supplied, installed, and
commissioned two-off hermetic pumps.
“Hermetic pumps (in general) have lower
maintenance costs associated with
the design than most other ammonia
pump types,” explains Pinkerton. “That
said, hermetic pumps need very reliable
protection systems to be installed to
prevent them from cavitating during
operation.” All pumps were supplied
complete with minimum and maximum
flow orifices as well as inducers. The pumps
also run on variable speed drives.
SAVING WATER
The facility makes abundant use of water
accumulated on the roof during periods
of rainfall. The water is saved and can be
used for various purposes. One notable
1. A ground-level control panel for the rapid cooling tunnels.
2. The accumulator vessel and stand.
3. Motors powering the Mycom N8M ammonia compressors in the plant room.
4. The control panels for the plant room. The controls were designed by MRE.
application is the use of rainwater for the
ammonia system condensers.
It should be noted that this water
still sees the effects of correct water
treatment before making contact with the
condensers, explains Pinkerton.
CHALLENGES
“The drawings and detail design provided
by WSP made implementation of the project
a lot easier,” said Pinkerton.
However, as the facility was the first
built in the new industrial park, power was
not available from the grid for the first
few weeks of operation. A huge mobile
generator had to be hired by the client to
power the system until Eskom was able to
connect them to the mains.
But in the end, everything came together
as planned and the client is very happy
with the installation and how it has been
operating. CLA
Source: http://www.goglobal.group
LIST OF PROFESSIONALS
Owner   GoChill
Developer GCP Projects SA
Architect / Designer  Mike Paterson Associates
Project manager   GCP Projects SA
Consulting
engineers 
Contractors
Product suppliers 
Mechanical WSP (David Brouwer)
Wet services WSP
Main building GCP Projects SA
Refrigeration MRE
Ammonia compressors Mycom
Ammonia condensers Evapco
Ammonia evaporators BAC
Ammonia valves Danfoss
Plant control panels Ultimate Electrical Solutions
Ammonia pressure vessels Dowson and Dobson
COLD LINK AFRICA • October 2018
www.coldlinkafrica.co.za
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