Investigating the effect of pump availability on load shift performance

Abstract

Due to the high electricity consumption trends of pumping operations in the mining sector, numerous load-shifting projects have been implemented to reduce peak TOU demand for electricity. A lack of maintenance on pump de-watering systems has caused some deterioration in load shift performance. Many studies have been conducted, focusing on the maintenance of mining de-watering systems to improve the load shift performance during the performance tracking period. However, limited research has been published that evaluates the effect that pump availability has on load shift performance. No method was found in existing literature that investigates the effect that pump availability has on load shift performance. The need to investigate such effect of pump availability on load shift performance is identified. A method is required that enables investigation and quantification of the effect that pump availability has on load shift performance. Furthermore, the method should enable one to schedule and prioritise maintenance on a de-watering system. A step-by-step methodology is developed from the research to investigate the effect of pump availability on load shift performance. The methodology consists of four phases supported by eight individual steps. The methodology assists in the development of a simulation model to investigate the effect that pump availability has on load shift performance. Additionally, the methodology outlines how to use the simulation model to obtain quantifiable results. The methodology is applied to the de-watering systems on three different mines. Each de-watering level of the mine is isolated from the adjacent de-watering levels. Eight case studies are described in the study. The results obtained from the case studies revealed reduced pump availability. The reduced availability correlated to poor load shift performance. Specifically, hours of reduced availability preceded peak TOU. It is also found that reduced availability of pumps for more than one hour further decreases performance. The results proved that if the availability of one pump is reduced for one hour, the operating cost can increase to a total of R1.4-million p.a. for the above mentioned three mines. If the availability of one pump is reduced for two hours, the operating cost can increase to a total of R 4.6-million p.a. for the three mines. Lastly, it is found that maintenance should be conducted during the peak TOU periods. If maintenance is conducted during these times, then no effect will be seen on the load shift performance due to unavailable pumps. If maintenance cannot be conducted during these times, then maintenance should be conducted in the hours not preceding the four hours of peak TOU.