Seward Refrigeration were awarded the installation contract from a major Ice cream manufacturer to supply, install and commission a pumped Ammonia refrigeration system feeding a, spiral freezer and Individual ice cream freezers. The total plant duty is 800kw, pump ratio 4:1, evaporating -39°C, condensing+32°C. The system feeds a 400kw spiral freezer and ice cream freezers totalling 400kw.
Installed were 3 No Mycom N220JL - HE screw compressors (Run & standby), complete with 250KW ABB IP54 low harmonic inverter drives. Cooling duty for each compressor is 403KW, Speed 3600 RPM, Economised, SST -39°C, CT +32°C. To take care of the THR, 1 No Evapco evaporative condenser was installed. CT + 32°C, WB +21°C.
400 kW Hot Water reclaim system
A further condenser manufactured by Vahterus was installed to the system to provide 400 kW of water heating from the refrigeration system when the plant is in operation. A Monopropylene glycol mix is pumped through the condenser at a flow rate of 17.0 L/s, the design on & off temperatures are +26°C & +32°C. The glycol runs through a secondary plate suitable for heating potable water, this plate is sized for 400 kW with a flow rate of 16 L/s, on & off water temperatures are +24°C & +30°C.
600kW chilled water system
We also supplied a new 600 kW ammonia cooled chilled water system which was connected to the above central plant to provide process water to heat exchangers within the factory area, the plant specification was as follows:
One off reciprocating compressor unit model SMC108LV direct driven, complete with 140kW IP23 VSD motor. The motor speed is varied between 500 rpm and 1800 rpm depending on the load generated by the factory process. The Sabroe compressor was connected to a Vahterus 600 kW plate heat exchanger, the plate was flooded and came from Vahterus with a surge drum/ liquid separator, and ammonia level control is provided by a Danfoss AKS 4100 and drives a motorised valve which is built into a Danfoss ICF control valve module.
The compressor evaporating temperature is 0°C and is accurately controlled by regulating the compressor speed and offloading cylinders as required, the condensing temperature is +32°C. A 9m³ insulated water buffer tank complete with weir plate was supplied to provide for any peak loads originating from the factory processes.