Energy-efficient compressors for Victorian Desalination Project

In June 2007, the Victorian Government announced the Victorian Desalination Project (VDP) as part of its Water Plan, which would create a drought-proof supply of water for Melbourne and Geelong. Compressed air is used to power a number of processes within the desalination plant, including the actuation of a number of the 17,000-plus automated valves.

The operator of the plant, AquaSure, chose to install a Kaeser turnkey solution to meet the plant’s requirements for an energy-efficient source of compressed air. The installation consists of: four Kaeser DSD 238 SFC series frequency-controlled rotary screw compressors; four air receivers; four instrument air treatment skids which include pre- and post- duplex filter sets; and a desiccant dryer.

Every Kaeser rotary screw compressor is equipped with a large, efficient screw compressor block featuring high-performance Sigma Profile rotors. Powered by a direct drive system, the screw compressor blocks in the DSD series compressors eliminate the transmission losses associated with gear-driven systems. This is said to increase reliability and service life.

Benefits of the compressors include efficient power transmission, optimal power consumption, reduced servicing and downtime costs, and significant energy savings. Further energy savings are achieved with the inclusion of the Sigma frequency control (SFC) module.

With the SFC module (variable speed drive), air delivery can be matched to actual air demand, according to the required system pressure, by continuously adjusting drive motor speed within its specified control range. This can lead to significant savings, as only the required compressed air at any one time is produced, with a 1 bar reduction in pressure amounting to a 7% reduction in energy consumption.

The Kaeser system isn’t the only energy-efficiency measure introduced to the plant, which also features minimal power consumption during the reverse osmosis (desalination) process and a compact, modular design that reduces pipework and eliminates inefficient energy use. With a production capacity of up to 150 billion litres of water a year, the VDP will form an important part of Melbourne’s water security in times of future drought.