Expanding compressed air demand side management through selective level control

Abstract

Compressed air is a resource which is used across the deep-level mining industry for a variety of purposes throughout the 24-hour mining cycle. It has been noted that compressed air is a particularly inefficient source of mechanical power, not only in the mining industry but in global industries as well, with efficiencies as low as 10%. The low efficiencies seen across all industries stem from the same root causes, namely: Leakages as a result of poor maintenance protocols and misappropriation of compressed air. In an attempt to address the low efficiencies in deep-level mining compressed air systems, previous studies investigated several demand side management initiatives. Existing control valve demand side management initiatives had five main shortfalls which limited their success and sustainability: either the energy impact of the initiative was too low or the capital costs, required maintenance, project lead time and resource intensities were too high. Therefore, a hybrid control philosophy, in which a surface control valve is installed in conjunction with selected level control valves, was proposed with the aim of maximising the energy impact and minimising the capital costs, required maintenance, project lead time and resource intensities. In this dissertation, the main study objective was the development of an analysis methodology which could be used to select the level control valves which maximised the benefit of a hybrid control approach in a deep-level mining operation. The analysis methodology enabled the identification of the hybrid control philosophy which maximised the energy impact and minimised the capital costs, required maintenance, project lead time and resource intensities. The analysis methodology was applied to a deep-level platinum mine in the North West province of South Africa and the optimal hybrid control philosophy was identified. Upon implementation, the hybrid control philosophy achieved an annual energy impact of 10.88 GWh whilst also minimising the capital cost, required maintenance, project lead time and resource intensity. Thus, achieving the study objective.