Case study
Panda Group of Companies
Ammonia refrigerating plant for distribution centre in Riyadh
Key information
Client:
Panda Group of Companies
Supplier:
Johnson Controls International
Type of facility:
Central ammonia refrigerating plant
System start-up:
2008
The Saudi Arabian food retailer Panda Group of Companies built a state-of-the-art distribution centre in Riyadh that was put into operation in 2008. For this purpose Johnson Controls International implemented a central ammonia refrigerating plant.
Requirements
The food retailer was interested in a central refrigeration design that had to be energy- and cost-efficient.
Solution
The refrigeration needed for the different store rooms is generated centrally by three systems:
a) HT gravity circulation ammonia system using two T20-BWFG plate heat exchangers with three Frick screw compressors RXF68, 1,018 kW each, two on-duty and one stand-by producing 12 ºC; one chilled water facility for cooling the regular storage rooms
b) MT gravity circulation ammonia system using two T20-MWFG plate heat exchangers with 4 Frick screw compressors RWF II-134, 750 kW each, all on-duty producing chilled propylene Glycol at -10 ºC required for all MT applications
c) LT pump circulation system with two -36 ºC low-stage compressors RWF II-134 , 330 kW each, all on-duty with one swing compressor RWF II-134, 750/330 kW, for LT freezer room applications
7 banana ripening rooms connected with the MT glycol circuit, controlled by 110 propa controllers via central PC
2 forced-air wet coolers with -12 ºC pump circulation system connected with the MT system; serves to pre-cool all vegetables
All systems are controlled and monitored by a central PC unit using Johnson Controls DDC controllers FXO6, FX14, FX16. All coolers were assembled with variable-speed, built-in fan motors. I.e. the speed and temperature can be controlled to reduce power consumption and running costs.
Technical data
Cooling capacity:
HT = 2,036 kW at 12 ºC, MT = 3,000 kW at -13 ºC, LT = 660 kW at -36 ºC
Refrigerant volume:
500,000 m³ in the HT areas at 12 ºC, 60,000 m³ in the MT areas at different medium temperatures, 22,000 m ³ in the LT freezer rooms
Secondary refrigerant:
Water, glycol
Main components:
Screw compressors by Frick
Module-welded plate heat exchangers by Alfa Laval
Evaporative condenser by BAC
Evaporators and air coolers by Thermofin
Special features:
Glycol absorbs the heat given off by the ammonia going through the plate heat exchangers. The hot glycol circuit is then used for MT defrosting and under-floor heating.
