Challenge
The installation of a new production line, complete with spiral freezer, designed for the manufacture of a variety of puff pastry products, prompted the company to look at improving its energy efficiency. For many companies in the food manufacturing sector, refrigeration can account for 70-80% of the electricity bill, so any savings made in this area are likely to be significant.
Solution
Installers of the Refrigeration equipment chose ABB drives to run two of the major components in the refrigeration system, which operates on pumped ammonia refrigerant at an operating temperature of -40 °C. The condenser is an evaporative type with the fan controlled by an ABB standard drive. Variable speed operation of the fan gives significant reduction in power even for a small reduction in speed. For example, a 10% speed reduction gives 30% less energy consumption.
A single 315 kW screw compressor is used to provide refrigerant for the spiral freezer. Using an ABB drive permits energy saving at part load conditions. The screw compressor can operate at speeds between 1500 and 3600 rpm at 100% slide valve position. With this mode of operation, the machine operates at optimum efficiency for any given speed.
"Although the full load efficiency of screw compressors is good, part load performance with slide valve control is generally poor. With variable speed control of the compressor they now have the best of both worlds: "good efficiency at both part load and full load," claims Refrigeration Plant supplier.
The screw compressor uses a low harmonic, ABB industrial drive, which minimizes harmonic interference on the mains supply and avoids the use of complex solutions to ensure conformity with G5/4 requirements.
Benefits
An 11% cut in the cost of electricity was expected following the installation of the ABB drives. The reduction will see costs cut by over £6,200 ($9,845), giving a payback for the project of 2.3 years.
Other advantages of the ABB industrial drive include operation at unity power factor, allowing reactive power charges to be avoided. The stand alone design of the drive gives it a small footprint, minimizing space requirements in the control room.
If you would like further information, please contact us or phone 0113 2631509