Kerry Foods,
Hyde

The Solution

The existing IQF freezer was operating at -42⁰C  saturated conditions based on 2.5 tonnes per hour. The compressor connected to the refrigeration system delivered 253kW in total in conjunction with a frequency regulated drive.

JD Industrial worked closely with Kerry Food’s team to design a system that accommodates the increase in product load – the result – an energy efficient package that now delivers an additional 237kW of Qcooling capacity that is able to turn down ratio for minimum load and also over clock to 60 cycles to deliver the upper cooling capacity.

Should one of the machines become out of service, the new package will now able to operate at 57% (2,350 tonnes) at the peak design ambient conditions.

IQF Spiral Refrigeration Package (Ammonia):

• Fixed Speed Screw Compressor Package – 237kW cooling capacity with Unisab III controller. Laser alignment to the screw machine was also carried out.
• 450kw Ammonia Surge Drum Package – Qcooling capacity of 450kw, ET:-42⁰C.
• Evaporative Condenser – Accommodating the total heat rejection of the compressor plant, design conditions at 32^oC, condensing pressure and 21^oC wet bulb temperature at 394kW. Due to the redundancy of the previous installation, a larger condenser was installed at QTHR 460kW. This included separate coil section for glycol cooling on compressor oil cooling circuit. The condenser has two 4kW fans, a 4.0kW spray pump and a 6kW electrical heater.
• Glycol Oil Cooling Pump – Serving the oil cooling requirements of 122kw, fluid in @ 32^oC and outlet of 42^oC based on 15% glycol at 3.02kg/s mass flow.
• Stainless pipework – For the oil cooling circuit.
• Hot Gas Pipe – For the defrost facility to the spiral freezer coils.
• Three ammonia hot gas defrost valve stations with three extract fan hoods.
• Gas Detection Monitoring and Ventilation System comprising:
• Single speed zone 2 ventilation fans rated providing normal ventilation for temperature control and emergency ventilation at a minimum of 15 air changes per hour.
• 8-point TQ ammonia detection system with the head detectors.
• Ammonia valves, pipework and controls.
• Secondary coolant (Glycol) valves, pipework and controls.
• Thermal Insulation (PIR) – Applicable to the low temperature ammonia pipework.

Electrical Works

• Control panels serving all refrigeration equipment.
• Field wire to all refrigeration equipment.
• Siemens central PLC node with Profibus DP communications protocol.

Energy Saving Features

A number of additional energy saving measures were employed into the design to conclude in optimum efficiency at all heat load and ambient conditions:

• Oil separators were sized for the specific volume of gas at low condensing saturated temperature of 20⁰C.
• Floating suction pressure.
• Floating discharge pressure control in relation to optimal ambient wet temperature.
• Design of compressors and other components to allow operation at low condensing conditions and therefore lower energy consumption.
• (IE3) drive motors on the compressors.
• Overall mechanical and electrical efficient design.
• Automated permanent refrigerant leak detection system (on the ECA list).
• Central controller with up to 8 sensors.