With diesel fuel costs soaring, Agincourt Resources decided it had to take further steps to reduce the energy bill at its remote Wiluna gold mine, 1000 km north east of Perth.
With a combination of gas and diesel engine generator sets providing 12 MW of base load power, Agincourt decided to install additional gas-powered generators to eliminate the use of the diesel units.
The gas generators tap into the 1380 km Goldfields Gas Pipeline which carries offshore natural gas from WA’s North West Shelf to the Pilbara and Goldfields regions, and Esperance.
After weighing up all proposals, Agincourt decided that Cummins Power Generation offered the ideal technical and commercial solution with the supply of two 1.75 MW gas engine generator sets.
The estimated savings in fuel costs were $1.8m a year which fitted perfectly with Agincourt’s commitment to production increases and cost reductions at the Wiluna mine.
The Cummins QSV91G generator sets, each capable of producing 1.75 MW, have been operating since August 2005. The sets are powered by lean-burn, spark-ignited Cummins gas engines – 91-litre, V18 units with turbo-charging and after-cooling.
According to the powerhouse supervisor at the Wiluna mine the generator sets are meeting load requirements with good fuel economy. Before these additional gas engine generators were installed, 12,000 litres of diesel a day was used for power generation in addition to the fuel being used by existing gas units.
Now, the total power demand can be met by the gas engine generators and that means substantial cost savings.
He says that generator reliability is critical in the often harsh environment where temperatures range from minus 10C in the winter to an intense 480C in summer.
Not only are living standards at the mine site dependent on generator reliability but also the efficient operation of the ore processing plant. Plant shutdown can cost in the range of $8,000 to $10,000 an hour.
Cummins’ Energy Solutions Business provided total project management of the gas engine generator design, installation and commissioning.
According to Cummins, it was responsible for not only the generators but also the supply and installation of the safety certified gas trains, acoustic enclosures, cooling systems and control systems.
A feature of the 91-litre Cummins gas engines is their lean-burn technology which means that combustion is lean because excess air is introduced into the engine along with the fuel.
This excess air reduces the temperature of the combustion process which in turn greatly reduces the amount of NOx (oxides of nitrogen) emissions. Also, since excess oxygen is available, combustion is more efficient with more power being produced from the same amount of fuel.
The full authority electronic engine controls ensure the combustion process is controlled within critical boundaries through regulation of fuel flow, air/gas mixture and ignition timing.