Sullair Australia replaced two of their old single stage compressors with a new two-stage air compressor at the Myuna Colliery of Centennial Coal to achieve significant cost savings with ROI in less than two years.
Compressed air is one of the most convenient yet most expensive utilities in underground coal mining, and is considered an essential and safe source of energy underground for mine de-watering, stone-dusting, cleaning, ventilation, and operation of mining equipment.
Centennial Coal, one of Australia’s leading coal producers used a comprehensive Measurement & Verification Audit to determine electricity savings achievable by replacing two single stage compressors having reached the end of their technical life with one modern two stage compressor.
The audit first measured the actual efficiency of the old compressors over a one-week period providing the baseline for an assessment of the improvement potential. Once the new compressor was commissioned, power consumption of all compressors was metered to determine overall savings.
Results of the audit indicated an ROI of less than two years; better security of supply; estimated total savings of 522 Megawatt Hours per year; and annual reduction in carbon pollution of about 553 tonnes.
The Myuna Colliery of Centennial Coal requires approximately 1,667l/s of compressed air at an average pressure of 800kPa. The existing set-up used two Champion VOC185 compressors and two Sullair LS25-350HAC compressors with the two Champion VOC compressors supplying air to the underground system through an air receiver and an air dryer while the two old Sullair compressors supplied air directly to the underground piping system.
The average compressor efficiency of the Sullair compressors was measured at 1.61l/s/kW, which was approximately 71% of their rated efficiency.
The two old Sullair LS25‐350H compressors were replaced by a new two stage Sullair TS32‐350HAC compressor at the new compressor shed. As per the CAGI Datasheet, the compressor requires a power input of 311kW at 862kPa with a free air delivery of 818l/s. This gives the new compressor a rated efficiency of 2.63l/s/kW, which is 63% better than the operational efficiency of the two old compressors.
To determine actual energy savings a permanent power meter was installed at the compressor shed supply. As this line also supplies the mechanical workshop, an estimate for workshop load was used to determine the actual total compressed air load. Overall 522,000kWh per year energy savings could be achieved resulting in annual cost savings of $90,246. In addition to the savings, $12,259/ year in Energy Savings Certificates (ESCs) could be generated providing an interesting additional income for the colliery.