Target profiles for critical parameters in compressed air systems to reduce missed energy savings opportunities

Abstract

The reducing profit margins of South African mines pose a financial and economic risk for South Africa. The decrease in gold production and the increase in operational costs are contributing factors to the reduction of profit margins in the gold mining industry. With electricity being one of the biggest expenses of deep-level gold mines, it is one of the focus points in reducing operational costs and increasing the profit margins of gold mines. An estimated 17% of the total electricity demand of deep-level mines is compressed air. Compressor energy savings initiatives can reduce compressor energy usage by as much as 30%. For this reason, compressor energy savings initiatives are typically implemented on deep-level mines. Sustaining the implemented compressor energy savings initiatives is a challenge in the mining sector. Compressor energy savings initiatives may achieve fewer savings than the maximum achievable savings due to various factors, causing missed energy savings opportunities. Compressor energy savings initiatives may experience missed energy savings opportunities due to: - Interference with automatic control, - high demand or unfavourable conditions, - infrastructure constraints or breakdowns, or - control system problems. Unless the abovementioned causes are identified and rectified, the missed energy savings opportunities will lead to decreased energy savings and unforeseen costs. The reduced energy savings leads to reduced profit margins, despite the efforts to implement such energy savings

initiatives. The literature contains methods to identify missed energy savings opportunities in compressed air systems and rectify the cause of missed energy savings opportunities once it has been identified. The literature lacks a detailed method to identify missed energy savings opportunities and the cause thereof. By applying the case study methodology, a method was developed that can be implemented with existing or previously implemented compressor energy savings initiatives. The method aims to reduce missed energy savings opportunities in compressed air systems by successfully identifying the cause thereof. The method incorporates target profiles for critical parameters in a compressed air system to identify areas where the technical requirements have not been met which results in missed energy savings opportunities. The method was implemented with four previously implemented compressor energy savings initiatives on three gold mining shafts of Mine A. The identification of missed energy savings opportunities and the cause thereof led to solutions implemented that reduced the missed energy savings opportunities calculated at 6.70 MWh per year, which relates to a cost avoidance of R 12 million per year.