Dynamic control on compressed air supply for sustainable energy savings

Manually controlled compressed air networks are operated inefficiently. A need exists to reduce the electricity cost of a mining complex by optimising the control of the compressed air network. One way to achieve this is by controlling the compressed air supply to accurately match the demand. A locally developed Dynamic Compressor Selector (DCS) controller was improved to better control complex compressed air networks. The DCS controller simulates the required discharge pressure set-point for compressors and then schedules the compressors to maintain the required pressure. The improved strategy calculates the pressure set-points of compressors by considering the consumers' requirements, auto compression, flow loss and pressure drops. It is customisable to a specific site as unique control parameters (specific to the site's requirements) are required to determine when compressors would be stopped or started. This is done to maintain the required network pressure. The improved controller was implemented and tested at a gold mining complex in South Africa. The implementation of this strategy on the specific case study resulted in an average evening peak clip saving in excess of 3 MW.