Our client is the world's largest manufacturer of frozen potato products and their existing production facility on England’s North Sea Coast was antiquated, and a major investment was necessary.
Seward Refrigeration Ltd were awarded the installation contract to install and commission a new multi-megawatt, standalone ammonia system to provide freezing and cooling duty for our customers new production facility.
The first phase of the project was to safely decommission the existing ammonia cold store refrigeration systems. Once the cold stores achieved ambient temperature the building work then commenced ready for the next phase of the project.
Total plant duty – 9,737kw
New IQF Tunnel Freezer No1 - The new tunnel freezer was designed for an operating ammonia temperature of -28/-32°C, providing a total duty of 2159 kW, and fitted with seven double mounted top feed bottom outlet connected coils. All of the coolers receive pumped ammonia from the new surge drum at -32°C with a pumping ratio at 5:1. The valve stations were installed within the access passageway between the two freezers, including extract ventilation.
New IQF Tunnel Freezer No1 Refrigerated Precooled Section - The new tunnel freezer precooled section is designed for an operating ammonia temperature of -1°C, providing a total duty of 925 kW and fitted with one double mounted top feed, bottom outlet connected stainless steel coolers. The coolers receive pumped ammonia from the new surge drum at -1°C with a pumping ratio at 5:1. The valve stations were installed within the access passageway between the two freezers, including extract ventilation.
New IQF Tunnel Freezer No2 - The new tunnel freezer was designed for an operating ammonia temperature of -28/-32°C, providing a total duty of 2159 kW, and fitted with seven double mounted top feed bottom outlet connected coils. All of the coolers receive pumped ammonia from the new surge drum at -32°C with a pumping ratio at 5:1. The valve stations were installed within the access passageway between the two freezers, including extract ventilation. To provide the duty, two Mycom single stage, economised ammonia screw compressors were installed operating between -28/-32°C (Total duty 2440 kW) Including sequential hot gas defrost load)
New IQF Tunnel Freezer No2 Refrigerated Precooled Section - The new tunnel freezer precooled section is designed for an operating ammonia temperature of -1°C, providing a total duty of 925 kW and fitted with one double mounted top feed, bottom outlet connected stainless steel coolers. The coolers receive pumped ammonia from the new surge drum at -1°C with a pumping ratio at 5:1. The valve stations were installed within the access passageway between the two freezers, including extract ventilation.
Coldstore - Three 134kw ceiling mounted, hot gas defrosting evaporators were installed in part of the old existing cold store, selected based on an high infiltration load and minimum fin spacing at 10 mm providing -18°C operating temperature.
ATL Dispatch Bay - Four 60kw ceiling mounted, hot gas defrosting coolers were installed for the new Auto Truck Loading Bay, selected based on an high infiltration load and minimum fin spacing at 10 mm providing -18°C operating temperature.
Batter Chilling and Glycol Air Coolers - One 850kw flooded Vahterus plate in shell ammonia/ CoolFlow DTX glycol heat exchanger, supplying chilled glycol to the Cryolator, potable water skid, weighing deck area evaporators, Manta operating room and Freezer outlet area coolers. The Vahterus heat exchanger is fitted with a twin system that incorporates two plates into one common shell operating on the flooded principle with ammonia evaporating at -11°C. The 0°C secondary glycol side provides a duty of 620 kW and the -6°C side provides a duty of 180 kW
Both glycol systems consisted of hot and cold side buffer tanks, vertical type with internal weir plate. The circuits include independent glycol pumps for the potable water heat exchanger, glycol coolers, recirculating pumps and valve stations.
Future - Roast Product Spiral Freezer - This will be a self-contained spiral freezer and will be connected onto the -32°C satellite packaged surge drum in the future.
To conclude the installation of the new refrigeration plant took just under two years to complete. The two new cold stores were commissioned first to allow product to be stored in dispatch at the required temperatures. Once the new system was partly commissioned the existing tunnel freezers were switched off individually and product was diverted to the new freezer tunnels.
When each of the new tunnel freezers were fully commissioned and in operation and the client was producing the required quantity of product, we then proceeded to decommission each of the existing tunnel freezers. In total including the existing cold stores, 29,000 KG of ammonia was safely removed from site, with the new refrigeration system being charged with 15,900Kg of ammonia in total.
The new refrigeration system is controlled via a state of the art SCADA system. Graphics and instrumentation (pressure and temperatures) are all visible on the screens which makes it ideal for site and our service engineers to diagnose issues with the system. The refrigeration plant is fully automated and requires little involvement from sites engineers to operate the system. Seward Refrigeration completed the control narrative and fully commissioned the new plant alongside software engineers.