Compressors help Alcoa to up productivity, lower maintenance costs
24 May 2011
San Ciprián, Spain – Aluminium producer Alcoa has installed 33 compressors as part of plans to increase productivity and lower maintenance costs at its San Ciprián refinery.
The Spanish refinery, situated on the coast of Lugo, focuses on the production of primary aluminium from bauxite. The raw material is transformed into alumina through the ‘Bayer’ process and subsequent conversion of the alumina into liquid aluminium by an electrolytic process.
Hydrovane compressors, from CompAir, are installed on the overhead gantry cranes working above the electrolytic cells. The compressed air is required at the refinery to actuate pneumatic cylinders within multiple machine tools, for fluidisation in the transport and loading of alumina and for the removal of liquid metal (casting) from tanks by the venturi vacuum effect.
“Our compressors are running for almost 24 hours a day, but it is during the casting operation when there is a greater requirement for air. To achieve a vacuum – the venturi effect – the pressure must not drop below 6 kg/cm2,” said Miguel Ángel Román Calderero, head of plant maintenance at Alcoa.
The existing Hydrovane compressors at the Alcoa refinery had been in use for over 30 years and were in need of repair or replacement.
Due to the complex nature of the application, Hydrovane conducted a site visit to review and assess Alcoa’s compressed air needs. Following the results of the assessment, Hydrovane provided two trial units for Alcoa to test before making the investment in new equipment.
“The trial units suited our needs, particularly as it was a similar size to our existing compressors and offered ease of access to all parts of the machine”, says Calderero.
Following the trial, 33 bespoke Hydrovane units, rated at 37kW , were installed on overhead gantry cranes at the refinery.
A factor for installing the new Hydrovane compressors is that the motor runs at just 1450 rpm, according to Calderero, noting that the alternative solution was a screw compressor running at 3000 rpm.
“The use of a screw compressor would have resulted in increased wear and maintenance costs, especially in an arduous environment such as alumina suspension, where high temperatures and aggressive gases exist,” he explained.
The new compressors are supplied as a purpose-built package, with a bespoke base mounting for installation on to the gantry crane. The starter is in an IP65 enclosure, which incorporates electronic control, with local and remote options and an alarm output.
The compressor package also features an oversized oil chamber to allow oil to cool quickly, a high flow fan with oversized cooler, remote cyclonic air intake filtration and motor specification that ensures the compressors can be operated efficiently within the refinery’s harsh atmosphere and high temperatures.
Since the installation, the Alcoa site has noted a reduction in the number of incidents or failures during metal casting operations.
“The new units’ oversized oil chamber allows oil to be changed at 2000 hours, instead of 500 hours as with the previous units, which has reduced equipment downtime. The preventative maintenance programme provided by CompAir Iberia has also resulted in a reduction in man-hours devoted to equipment failures,” Calderero said.
