Bespoke System Helps Scottish Salmon Industry

The Client –

Scottish Salmon Producer


The Challenge –

Expansion Of Production Facility


The Solution –

Custom Designed Cooling System

When a seafood company looked to expand their salmon production across Scotland, Aqua were commissioned to design a fully bespoke cooling system to upgrade their existing facility.

The client, one of the worlds’ leading producers of farmed salmon, was looking to upgrade their salmon hatchery in a drive towards longer term sustainability and efficiency. The new hatchery would not only dramatically increase the number of employees on site but also improve their ability to grow out smolts which would then supply their network of Scottish sea farms.

A smolt is a young salmon and refers to the development stage before full adulthood. The salmon start their life in hatcheries or loch farms before moving on to sea farms where they grow to full adulthood.
Aqua supplied a 1,550 kW custom designed system which worked on the principle of water being taken from a local river, into a large buffer tank. This water is circulated through two chillers which are specially designed with cupro-nickel water cooled condensers so they can operate on river water. The chillers then supply four plate heat exchangers to separate the salt water from the chilled water and to protect the livestock. Each of these heat exchangers is associated with an independent tank which either houses the very small salmon fry or the larger smolts.

As well as keeping the tank temperature at the optimum for the well-being and development of the salmon, the system is designed for maximum energy efficiency. Each chiller has 6 highly efficient multiple scroll compressors which are installed in 3 fully independent circuits with 2 compressors – giving 6 separate capacity stages. They each also have triple circuit shell & tube evaporators as well as shell and tube condensers. Each chiller unit has a COP (Coefficient of Performance) value of just 5.11 under full load conditions.

The full solution included:

  • 2 x 770kW water cooled chillers
  • 8,000 litre polypropylene buffer vessel
  • IE3 motor, run and standby pump system
  • Energy efficient design – including R410a refrigerant
    and COP value of 5.11 for compressor under full load conditions
  • Reduced noise specification – including
    acoustic jackets on chiller compressors
  • Centralised control system
  • Full design service plus electrical and mechanical installation

The versatile design of the cooling system means that during the warmer months when the ambient temperature is higher both chiller units can be fully operational. But, during the cooler Spring & Autumn months the system can simply reduce to medium/low load. In this scenario just one chiller needs to operate – massively increasing operating costs and efficiency, by turning the pump motors off – yet the control system will rotate between both units at start up so that they are both used equally.

Ian Clynes, Aqua’s Northern Project Manager, explains; “Scottish salmon has a great reputation around the world and the aquaculture process is vital to the country’s economy, so this was a great project to be involved with. The unique system design is a fantastic example of Aqua’s ability to engineer energy efficient solutions that can really make a difference to clients’ businesses.”

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