Oz milk processor compresses energy and carbon costs

Melbourne, Australia - Australia’s largest milk processor, Murray Goulburn (MGC) aims to save Aus$147,000 in annual energy and maintenance costs and to reduce CO2 emissions by more than 1,908 tonnes over 12 months, following its installation of a new air compressor system. The company also aims to save a further Aus$40,000 in power costs and 677 tonnes of CO2 savings via related projects.

MGC processes 37% of Australia’s milk supply and is the nation’s biggest exporter of processed food. The company's replacement of the existing compressed air system at the Leongatha plant was, in part, linked to Australian government plans to introduce carbon trading in 2010, which include providing funding towards the purchase of new, energy-efficient technologies.

The company decided to implement a complete new system to supply all of the factory’s air requirements used for both plant and packaging processes, to include new compressor units, air supply pipes and dryers. It opted for a CompAir Australasia proposal, based on replacing the four existing units with just one, 300 kW Quantima compressor and leaving two units for standby air.

According to CompAir, its compressor features a centrifugal compression assembly that consumes significantly less power than conventional technologies. The Q-drive design, it said, has only one moving part, the rotor shaft, so there is no friction contact that can result in energy losses and performance degradation over time. In addition, the compressor also has a variable-speed drive that matches airflow to plant demand for further energy efficiency.

The system was commissioned in November 2007. Audit results taken before and after the installation have now been submitted to the Victoria State government and show that MGC has met its power reduction target, achieving overall energy savings of more than 35%, according to Mark Gurney, group maintenance manager for MGC.

“We needed to commission a completely new compressed air system that would optimise energy efficiency at every stage and CompAir Australasia has proved that it could engineer such a solution, said Gurney. "By combining the innovative Quantima compressor with all downstream equipment, including desiccant dryers and new air distribution pipes, we have been able to reduce pressure drops and air leaks dramatically."

Prior to the installation, MGC's compressed air system was using 9.1 kW to generate each cubic metre of air per minute. With the new compressor, this has reduced significantly to just 6.12 kW/Nm3/min, so it it is now taking 33% less power for us to generate a higher air output.

MGC has already realised annualised CO2 savings of 1,908 tonnes. Current expectations are that carbon offset costs will be around $35 a tonne when the NETS commences in 2010, equating to an estimated saving for MGC of at least $66,700.

Remote monitoring

The Quantima compressors are supplied with a predictive maintenance service that enables CompAir to monitor the performance of the compressor, 24 hours a day. Engineers at the equipment maker can, therefore, moderate the machine’s performance remotely to prevent a fault occurring or send a local engineer to site to carry out remedial repairs.

CompAir also interfaced the Quantima compressor into the company’s internal network so that MGC engineers can view the status of the machine locally and make minor adjustments to optimise compressor performance.

To further reduce energy consumption and its reliance on the chilled water supply, the Leongatha site is currently installing new water-cooling towers. These will enable water to be taken straight into the process, which can be up to 8% more energy efficient than using a separate factory chiller to cool the mains water.

CompAir is currently working with MGC to enable the feed from the new water supply to the compressor, a project that will be completed in the next few months. This project is likely to save another 71 kW of installed power , yielding an additional Aus$40,000 in power savings & 677 tonnes of CO2 savings per annum.

“Instead of simply replacing one or two of our existing compressors, we choose to install a complete new system that would deliver a low cost of ownership, with the maximum energy savings possible," said Gurney. "Overall the project will pay back, pre tax, in 22 months.”