INCORPORATING COLD CHAIN
PROJECT
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Three-stage system The store has a total of eight low temperature chambers, a dispatch area with 22 doors and a receiving area with 11 doors, all with docking levellers and insulated docking seals. The eight chambers have a combined storage capacity of 45 000 pallets( 1.5m high) or 32 000 packed( 2m high).
The three-stage central ammonia refrigeration plant comprises a total of nine Grasso reciprocating compressors( 7 x V1400 and 2 x V700). There are three compressors on the high stage(-13 ° C,) three on the low stage(-30 ° C), two compressors on the low-low stage(-40 ° C), and one swing compressor is piped to operate on either the high stage or low stage.
The plant has a total refrigeration capacity of 1 402kW with a coefficient of performance( COP) of 4.3. Four of the chambers have dual-valve stations so as to operate as chill rooms or at-20 ° C.
Liquid ammonia is pumped to the evaporators by six CAM-hermetic pumps of which three are standby.
The refrigeration capacity is matched to the demand by the unloading of compressor cylinders and change in compressor speed. Each compressor drive motor has a variable frequency drive( VFD) to vary its speed.
Allowance has been made for the heat rejection from the hot gas circuit to be recovered to heat water in an ammonia to water, plate heat exchanger for ablution and washing.
Defrost condensate is collected and stored in a tank to be used as make-up water for the evaporative condensers. It is envisaged that only occasionally will it be necessary to use municipal water for make-up water.
Compliance with statutory regulations like Pressure Equipment Regulations( PER), SANS 347, SANS 10147 and the OSH Act was a priority in the design and onsite work. The pressure vessels were manufactured by ILVA Engineering and all pipe work and pressure testing was done under the supervision of an AIA, Oliver Survey Group.“ Operating staff were present during the pressure testing and commissioning and have undergone training in the safety and evacuation procedures and basic operation of the plant,” says Vuletic.
State-of-the-art technology The logistics of getting frozen or chilled foodstuffs from producer or processor to retail outlets, industrial caterers or restaurants, demands a high investment in specialised equipment and trained personnel. The new state-of-the-art Imperial Cold Logistics at Linbro Park is the outcome of many months of research and study tours to Europe by a highly motivated Imperial team.“ We aimed to have a facility that would go beyond the expectations of our clients and stay abreast with international developments in refrigerated logistics,” says Van Zyl. He went on to give details of some of the features that will improve productivity, adhere to food safety, conserve energy and provide high levels of service delivery. The mobile racking in the low temperature chambers improves storage capacity and management of product movement. The electronically-managed system pre-determines the opening of aisles according to picking schedules. Reach truck operators do not have to wait for aisles to open. The operators are automatically directed to the pallets to be picked and only the required roof lighting
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1. The regulatory ammonia charging valve is located on the outside of the plant room.
2. Blower coils are mounted in insulated pods with a hydraulically operated flap that closes when coil is being defrosted.
3. All despatch and receiving doors have docking levellers.
4. Three surge drums(-13 ° C,-30 ° C and-40 ° C) installed on a mezzanine floor in the plant room.
5. Six CAM hermetic pumps circulate liquid ammonia to the 32 evaporators.
6. Bob Vuletic of Multistage Cooling maintained workplace safety in accordance with the OSH Act during the installation of the refrigeration plant.
COLD LINK AFRICA • May | June 2016 www. coldlinkafrica. co. za 37