A practical approach to investigating energy consumption of industrial compressed air systems

While there are several best practice standards available for minimizing the energy requirement for compressed air use in an industrial context, moving to best practice often requires investment and operational change. In production facilities, there is often a reluctance to commit to this type of change without a clear view of the benefit. Furthermore, there is very little detailed information available in the open literature that allows even a qualitative assessment of priorities. In order to address this shortcoming, a practical approach is proposed to provide detailed compressed air consumption information throughout an industrial site. The energy of the compressed air is evaluated at each key element of the system and the typical end-use application profile assessed. Simple models of the consumption rates are used to relate duty cycle and device count with actual total consumption. This approach is complemented with a novel method of assessing the leak rate from the entire system, based on the pressure decay time. The method, referred to as the 'end use catalogue' has been demonstrated at a manufacturing site with a wide range of compressed air applications. The model has been used to identify the most significant energy-intensive compressed air applications and possible strategies to reduce the energy requirement. In the particular site used as a demonstration, it was found that open blowing operations (e.g. fluidizing) are the largest consumers of compressed air which are amenable to intervention. System leakage accounts for almost 21 per cent of the compressed air generated, representing an energy input of 432 kWh per day. It is concluded that this approach can help to identify priorities for optimizing compressed air use at an industrial site without compromising the production yield.