GoChill: pushing the boundaries beyond ‘just a cold store’

By Ilana Koegelenberg

GoChill’s new cold store facility for KwaZulu-Natal goes beyond merely renting out space. It offers a ‘one-stop shop’ for fresh fruit exporters through ambient-, chilled-, and cold sterilisation solutions.

GoChill00 18 COVERThe inside of one of the chillers. The chillers contain mobile racking, which helps to optimise the available space.

After more than a decade in the agricultural freight logistics game, the directors of GoReefers Logistics decided it was time to invest in their own cold storage facility under the umbrella of the GoGlobal group of companies, providing clients with complete perishable goods solutions.

They initially investigated purchasing an existing property and refurbishing it, but in the end opted for a custom-designed and purpose-built new facility to suit their needs — and the needs of their clients. And so, the GoChill project got under way.

The rapid cooling tunnels make use of proportional suction control valves to maintain temperatures for export goods accurately.

The project was completed in 2016 with MRE as the refrigeration contractors and WSP the design consultant for the refrigeration and insulated panelling scopes of work. Practical completion was in May 2016, with final completion being during August that year. Various sections of the facility came online throughout this period.

A complete solution

GoChill is a new, ultra-modern, independent, and purpose-built cold storage and fresh fruit handling facility situated close to the Port of Durban in KwaZulu-Natal. With its highly skilled and experienced team, it forms part of the integrated logistical solutions offered by the GoGlobal Group.

The cold store is located only 20 minutes from the port, with no inner-city congestion to deal with — allowing easy access and quick turnaround of incoming trucks from the production areas. It offers a variety of storage solutions, including weighing of cargo, ambient and chilled storage, cold sterilisation protocol shipments, container plug-ins, and transport to port.

Through the use of a modern racking system and a sophisticated electronic pallet tracking system, they ensure access to every pallet, thus enabling clients to manage their load specification and stock rotation with increased efficiency.

The GoChill facility is about 6 500m2 in size and can store up to 6 000 pallets: 4 500 commercial; 1 000 steri; and 500 ambient pallets. It houses about 35 different clients during peak season, focusing predominantly on citrus. However, in the off-season, they also store other products requiring temperature control, like vegetables and deciduous fruits.

The company is currently in the process of expanding the facility to accommodate the growing demand of their clients. But this was anticipated, and the refrigeration plant was designed to keep up with the future plans too. There is a huge demand for steri storage, in particular.

Client brief

The contract went to tender and was based on a detail design by WSP, as designed by David Brouwer. For refrigeration, the brief involved the complete supply, installation, and commissioning of the refrigeration equipment for the new GoChill cold store in Durban.

General plant description

A single-stage ammonia refrigeration plant was designed to service the new GoChill rapid cooling tunnels, chiller stores, and airlock. The cooling tunnels were designed to operate with a coil air off temperature of -1°C, the chillers at an average air temperature of +2°C to +4°C, and the airlock at +12°C.

Four high-stage reciprocating compressors were designed to meet the facility load and operate at saturated suction and condensing temperatures of between -8°C and +34°C, respectively. Three compressors were required to run under peak conditions, with a fourth as standby. The compressors operate at a fixed speed of 1 450rpm.

Two evaporative condensers were installed on strip plinths on top of the new plant room roof and together, the condensers operate at a saturated condensing temperature of +34°C. With one condenser out of operation, the saturated condensing temperature will rise to +37°C.

One horizontal -8°C accumulator vessel is provided for the plant as well as one receiver vessel.

Controls

The refrigeration plant is equipped with an automated control system to ensure that the starting, stopping, and capacity control is fully automated. The refrigeration plant isn’t manned, and the control system therefore accommodates this. In addition, the control system has the facility to allow for plant monitoring, including all room temperatures and cooling tunnel temperatures from the client’s operations office.

A single-stage ammonia refrigeration plant was designed to service the new GoChill rapid cooling tunnels, chiller, stores, and airlock.

The control system also accommodates data logging for temperatures and pressures throughout the refrigeration plant. This data is readily available in the form of tabulated or graphical display.

The control system even sends text messages via the cellular networks to select phone numbers for plant alarm conditions.

The cooling tunnels make use of proportional suction control valves to maintain temperatures for export goods accurately. This control allows for the fastest cool-down rate with least amount of product weight loss, by keeping the log mean temperature difference (LMTD) as low as possible while ensuring that the required cooling profiles are achieved.

Compressors

Four-off Mycom N8M reciprocating compressors were installed and operate at -8°C/+34°C, as mentioned. The compressors are direct-driven by a 220kW, 400V four-pole motor. The capacity at -8°C/+34°C and 1 450rpm, is 827kWr with an absorbed power of 188kW.

All four compressors are star-delta started. Since the N8M compressors all allow for four stages of loading, this allows for sufficient scaling of the applied refrigeration power, based on the facility’s demands. During the off-peak season, there is a special control feature installed that prevents nuisance trips due to boiling in the accumulator. “These are the subtle control aspects that we focus on to deliver an extremely robust and reliable plant to our client,” explains Joshua Pinkerton of MRE.

The compressor packages from MRE were delivered complete with oil separator, pressure gauges, and the full complement of hard-wired safety accessories. The packages also feature what they consider to be essential safety requirements, such as internal pressure relief valves, coupling covers, and isolation valves.

The N8M compressor has four capacity steps —25, 50, 75, and 100% — which is 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 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 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.

List of professionals

Owner  

GoChill

Developer

GCP Projects SA

Architect / Designer 

Mike Paterson Associates

Project manager  

GCP Projects SA

Consulting engineers  

Mechanical

WSP (David Brouwer)

Wet services

WSP

Contractors

Main building

GCP Projects SA

Refrigeration

MRE

Product suppliers 

Ammonia compressors

Mycom

Ammonia condensers

Evapco

Ammonia evaporators

BAC

Ammonia valves

Danfoss

Plant control panels

Ultimate Electrical Solutions

Ammonia pressure vessels

Dowson and Dobson

Source: http://www.goglobal.group  


Click here to read the October 2018 issue of Cold Link Africa

16 Oct 2018;
08:00AM - 06:00PM
Chillventa 2018 - 16-18 October
16 Oct 2018;
08:00AM - 06:00PM
Chillventa 2018 - 16-18 October
16 Oct 2018;
08:00AM - 06:00PM
Chillventa 2018 - 16-18 October

 

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