Dale Farm, Dunman

Dale Farm are one of Powertech Refrigeration’s longest-serving customers, with several new installations over the last decade and beyond, and maintenance contracts covering several Dale Farm sites throughout Northern Ireland. Perhaps the most impressive of these new installations is the Megawatt chiller installed at Dale Farm’s Cookstown site.

With limited space and the challenge of integrating two existing systems into the new chiller, a plan was made to install the new chiller in the chemical compound and have the new 8-inch stainless steel pipework continue across a laneway at high level before connecting into two separate systems buffer tanks, providing chilled water at 2.0°C and returning at 8.0°C. The pipework was then insulated using PIR and covered with PIB Sheet for additional protection.

There was a concern that, with one of the existing systems using ammonia, there was potential for ammonia to get into the water solution and get into the chiller on the return circuit. With the standard heat exchanger in the chiller being copper shell and tube, any ammonia would cause serious damage and would be expensive to repair.

Two solutions were proposed: firstly, a stainless-steel plate heat exchanger would not sustain damage from any ammonia that may enter the system and would provide a safer alternative to copper, and secondly, a PH sensor in the glycol solution would provide an alert should ammonia enter the system causing the PH level to rise – this would then close two butterfly valves and stop any flow to or from the chiller. In this case, a stainless-steel heat exchanger was chosen.

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